INFLUENCE OF GRAFT TYPE AND DIAMETER ON KNEE FUNCTIONAL OUTCOME RESULTS AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

(1)

LITHUANIAN UNIVERSITY OF HEALTH SCIENCES MEDICAL ACADEMY

Rokas Jurkonis

INFLUENCE OF GRAFT TYPE AND

DIAMETER ON KNEE FUNCTIONAL

OUTCOME RESULTS AFTER ANTERIOR

CRUCIATE LIGAMENT

RECONSTRUCTION

Doctoral Dissertation Biomedical Sciences, Medicine (06B) Kaunas, 2018

(2)

Dissertation has been prepared at the Institute of Sports, Medical Academy of Lithuanian University of Health Sciences during the period of 2013–2018.

Scientific Supervisor:

Prof. Dr. Rimtautas Gudas (Lithuanian University of Health Sciences, Biomedical Sciences, Medicine – 06B).

Dissertation is defended at the Medical Research Council of the Medical Academy of Lithuanian University of Health Sciences:

Chairperson

Prof. Dr. Žilvinas Dambrauskas (Lithuanian University of Health Sciences, Biomedical Sciences, Medicine – 06B).

Members:

Prof. Dr. Andrius Macas (Lithuanian University of Health Sciences, Biomedical Sciences, Medicine – 06B);

Prof. Dr. Šarūnas Tarasevičius (Lithuanian University of Health Sciences, Biomedical Sciences, Medicine – 06B);

Prof. Habil. Dr. Narūnas Porvaneckas (Vilnius University, Biomedical Sciences, Medicine – 06B);

Prof. Dr. Natalia Balague Serre (University of Barselona, Biomedical Sciences, Medicine – 06B).

Dissertation will be defended at the open session of the Medical Research Council on the 17th_{of July, 2018, at 14:00 in the Great Auditorium of the} Hospital of Lithuanian University of Health Sciences, Kauno klinikos. Address: Eivenių g. 2, LT-50161, Kaunas, Lithuania.

(3)

LIETUVOS SVEKATOS MOKSLŲ UNIVERSITETAS MEDICINOS AKADEMIJA

Rokas Jurkonis

TRANSPLANTO TIPO IR DIAMETRO ĮTAKA

KELIO SĄNARIO FUNKCIJOS ATGAVIMUI PO

PRIEKINIO KRYŽMINIO RAIŠČIO

REKONSTRUKCIJOS

Daktaro disertacija Biomedicinos mokslai,

medicina (06B)

(4)

Disertacija rengta 2013–2018 metais Lietuvos sveikatos mokslų universitete, Medicinos akademijos Sporto institute.

Mokslinis vadovas:

prof. dr. Rimtautas Gudas (Lietuvos sveikatos mokslų universitetas, biomedicinos mokslai, medicina – 06B).

Disertacija ginama Lietuvos sveikatos mokslų universiteto Medicinos akademijos medicinos mokslo krypties taryboje:

Pirmininkas

prof. dr. Žilvinas Dambrauskas (Lietuvos sveikatos mokslo universitetas, biomedicinos mokslai, medicina – 06B).

Nariai:

prof. dr. Andrius Macas (Lietuvos sveikatos mokslo universitetas, biomedicinos mokslai, medicina – 06B);

prof. dr. Šarūnas Tarasevičius (Lietuvos sveikatos mokslo universitetas, biomedicinos mokslai, medicina – 06B);

prof. habil dr. Narūnas Porvaneckas (Vilniaus universitetas, biomedicinos mokslai, medicina – 06B);

prof. dr. Natalia Balague Serre (Barselonos universitetas, biomedicinos mokslai, medicina).

Disertacija ginama viešame Lietuvos sveikatos mokslų universiteto Medicinos akademijos medicinos mokslo krypties tarybos posėdyje 2018 m. liepos 17 d. 14 val. Lietuvos sveikatos mokslų universiteto ligoninės Kauno klinikų Didžiojoje auditorijoje.

(5)

ABBREVIATIONS

ACL – the anterior cruciate ligament

ACLR – anterior cruciate ligament reconstruction

AM – anteromedial

AP – anteroposterior

BMI – body mass index

BPTB – bone-patella-tendon-bone CI – confidence interval

GNRB – GeNouRoB robotic arthrometer

HT – hamstring tendon

ICN – intercondylar notch

IKDC – International Knee Documentation Committee

LSI – limb symmetry index

MRI – magnetic resonance imaging

NWI – notch width index

N – Newton

n.s. – non significant

OA – osteoarthritis

PCL – posterior cruciate ligament

PL – posterolateral

RTC – randomised control trial

SD – standard deviation

(8)

INTRODUCTION

Sport activities are highly prioritized nowadays, and, probably due to active way of life, more and more people are involved in sport related injuries, regardless of age, gender or playing level. Some injuries, such as sprains, do not keep an active person or athlete sidelined, but an increasing number of such persons are subjected to a much more serious injury – anterior cruciate ligament (ACL) rupture. Injuries of the ACL are one of the most common knee problems in athletes and in people who participate in sports at a recreat-ional level [38, 77, 130, 173, 197]. According to the data collected by the National Collegiate Athletic Association (NCAA in the USA), football had the highest number of reported ACL knee injuries (53% of all recorded ACL injuries), but ACL injuries, regardless of the mechanism, accounted for ap-proximately 3% of all injuries [100]. In professional female soccer players Giza et al. [82] found an ACL injury incidence rate of 0.09 injuries per 1000 player hours. Other studies indicate that 70% of injuries occur through non-contact mechanisms, especially in pivot sports associated with stopping suddenly or slowing down while hasting [77, 88]. It has been reported that the incidence of ACL tears in female athletes is from 4 to 6 times greater than in male athletes competing in similar sport activities [20, 174]. As such trauma occurs, absence of anterior cruciate ligament functioning leads to a change in knee kinematics, a recurrent injury and has been postulated to be responsible for abnormal joint wear [152, 157].

The management of ACL injuries is one of the most challenging issues in orthopaedics in order to avoid the earlier mentioned outcomes. Surgical reconstruction of the ACL is the best treatment solution, especially in profess-ional athlete, as conservative treatment leads to functprofess-ionally unacceptable outcomes [76]. The goal of surgical treatment is to restore the normal knee function and stability by using a tendon autograft, which is inserted in one tibial and one femoral tunnel in accordance with anatomical reconstruction guidelines.

Nowadays, graft choice is still one of the topics of discussion in literature.

Historically, the bone-patellar-tendon-bone (BPTB) graft was used as the golden standard, but due to complaints of anterior knee pain and the complexity of surgical methods, the hamstring tendons (HT) have turned out to be a good alternative with similar outcomes [119, 165]. The most fre-quently used hamstring graft configuration is a 4-strand graft consisting of doubled semitendinosus and gracilis tendons [128]. Biomechanical studies show superiority and lower harvest site morbidity as compared with patellar tendon autograft and continue to support the use of hamstring autograft [91,

(9)

177]. As the development of this anatomic concept is quite recent, it still remains unclear which technique yields the best outcome for the patient and considerable controversy continues over the use of BPTB versus HT, since there is a lack of comprehensive studies comparing the clinical effectiveness of the two grafts. The first objective of this study was to compare and

analyse the stability of the knee joint after these two reconstruction methods by using BPTB autograft and HT autograft, which is

biome-chanically comparable in tensile properties [6,11, 21,29,81,176].

Scientists still argue if graft size matters in anterior cruciate ligament reconstruction (ACLR) and try to base their suggestions on historical biomechanical data and support it by consistent clinical evidence [128,133, 148]. Although a HT graft (“4 strand looped graft”) has been shown to offer potentially higher load-to-failure values at time zero than BPTB grafts, there is likely much more variability in these values [37]. Recent studies have pointed to a higher early failure rate of HT grafts in patients with grafts 8 mm or less in diameter when compared with grafts > 8 mm in diameter [52, 128]. Corry et al [53] first reported a difference in laxity between men and women after single-bundle ACLR with a HT autograft. They found that female patients with HT grafts had greater laxity on arthrometer testing than did female patients with BPTB and male patients with either HT or BPTB grafts. The study of Tuman et al [202] reported that women had significantly smaller hamstring graft diameters than men and we know, that hamstring graft with a small diameter can also induce residual anterior laxity even after anatomic ACLR. However, there is still lack of scientific studies comparing graft diameter and knee laximetry to determine functional outcomes. The second

objective of this study was to evaluate and analyse stability of the knee joint after ACLR using different diameter hamstring tendons.

Accurate assessment of knee laxity is critical for many steps in the ma-nagement of ACL. A recent study from Spragg et al [194] identified that within the range of 7 mm to 9 mm in graft diameter, the risk for re-ruptures would decrease significantly with each 0.5-mm increment in the graft diameter. However, there is lack of studies comparing graft diameter and knee laximetry in clinical examination. Clinical diagnosis of ACL tears (Lachman test and Pivot shift test in valgus and internal rotation) is reliable in case of complete ACL tear but reveals itself elusive in case of partial tears, so quantitative assessment of anterior tibial translation proves to be imprecise, subjective and poorly reproducible [171]. Earlier, measurements in other countries were commonly obtained using the KT-1000 laximeter (Medmetric, San Diego, CA, USA), that was first introduced in the early 1980s by Daniel et al. [54]. The KT-1000 arthrometer is the most widely used knee ligament

(10)

testing system because it is an easy-to-use device and still remains a reference instrument in the many published scientific papers, but in our study we used GNRB® system, developed in 2005, in France. It is a robotic arthrometer designed to avoid operator-dependent and relaxation-dependent error. This system is proven to be used in diagnosis of partial and complete ACL tears and for clinical follow-up of operated or not ACL tears [171]. This medical device allows running dynamic tests on the knee, and it is an automated dynamic laximeter (arthrometer). This characteristic makes this device unique of a kind much more efficient than any other arthrometer as it enables the user to objectively evaluate the knee stability and its displacement differential whereas other laximeters only put forward the displacement differential. And the measurement accuracy of the GNRB® is only 0.1 mm [171]. This testing system is fully computerised.

Functional outcomes after ACLR commonly are evaluated by single-legged hop tests. Single-single-legged hop tests are performance-based measures used to assess the combination of muscle strength, neuromuscular control, confidence in the limb, and the ability to tolerate loads related to sports-specific activities and these tests are commonly used to quantify knee performance in patients after ACL reconstruction [168, 170, 208]. These tests can determine between those individuals who returned to previous activity level from those who did not return after ACL reconstruction [18, 71]. Logerstedt et al. [122] states, that hop tests are clinically useful in predicting future outcomes and help predict who will have knee function within or below normal ranges in the medium term (one year after ACL reconstruction). We conducted a scientific study to analyse the influence of diameter of ACL graft to knee laxity and functional recovery outcomes after ACLR. In our study, we used GNRB® laximeter precisely to measure ACL laxity at different time-points after reconstruction. Final functional outcomes were evaluated by single-legged hop tests 12 months after ACLR.

Scientific novelty

This study seeks to determine whether the diameter of the tendon graft influences the outcome of the ACL reconstruction when measured using precise laxity measurement device (GNRB®) before ACLR and three, six and twelve months after ACLR. It is relevant to evaluate gender, body mass index (BMI) and period from injury to surgery influence on functional recovery outcomes after ACLR. According to scientific research results, literature review and our knowledge, there is only one very recent scientific study which evaluates graft diameter influence to outcome results using GNRB®

(11)

system after ACLR [131]. The authors of that study did not evaluate function-al outcomes after ACLR, Tegner activity score (TAS) and did not anfunction-alyse IKDC data. However, we assume that it is important to investigate functional outcomes to achieve significant conclusions.

Practical and theoretical significance

A focus on the ACL injury problem has been growing recently, not just in the research field, but also among coaches, athletes, health care personnel and even the public at large. It is probably one of the most escalated sports injuries, which greatly limit the further human sports life, meanwhile the knee joint after such an injury has a greater risk for the degeneration processes to establish. We presume that laximetry using GNRB® is a useful technique in clinical practice, especially for aiding in the diagnosis of complete ACL tears, controlling the treatment process and applying the best surgical treatment option. It is important to gather more information about knee laxity after different graft diameter ACLR – is it enough a lesser graft diameter for wo-men or maybe BMI has impact for knee laxity according to graft diameter or whether ACLR with greater graft diameter has better outcomes in patients, with performed reconstruction in later period. The ultimate purpose of this study was to determine whether graft diameter or patient related factors have impact on functional outcomes of ACLR and to combine old and new research findings in order to improve the outcomes of ACL reconstructive surgery and raise the quality of quick patient recovery. This study results will help to answer the scientific questions and will allow to create practical recommendations to improve treatment quality and help to choose the optimal methods of rehabilitation and kinesiotherapy methods.

(12)

1. THE AIM AND OBJECTIVES OF THE STUDY

The aim of the study:

To evaluate graft type, diameter and patient related factors influence on functional recovery outcome results after anterior cruciate ligament reconstruction.

Objectives of the study:

1. Evaluate stability of the knee joint after two different anterior cruciate ligament reconstruction methods with two graft types.

2. Evaluate stability of the knee joint after anterior cruciate ligament reconstruction using different diameter grafts.

3. Evaluate functional outcomes of the knee joint after anterior cruciate ligament reconstruction using different diameter grafts.

4. Evaluate influence of anterior cruciate ligament graft diameter and patient related factors on clinical and functional recovery outcomes after anterior cruciate ligament reconstruction.

(13)

2. LITERATURE REVIEW

2.1. Anatomy and function of the knee

The knee joint is the largest and apparently one of the most important joints within the human body. This complex joint provides both stability (allows weight bearing) and mobility (allows fluent movement). Knee joint is invol-ved in many important daily human activities such as standing up, walking, running, stair climbing, squatting etc., due to its mobility. Hinge-like joint allows movement in flexion and extension also small rotational movements in flexion are possible as well [45, 180, 195]. Knee joint injury can signifi-cantly affect training and sports performance. Knee joint consist of distal part of femur, proximal part of tibia and patella, lying in front of the joint. All these bones are covered with articular surfaces (articular cartilage) which provides cushioning and smooth motion. The knee joint is covered by synovial membrane and all chambers are filled with synovial fluid. The joint is surrounded by muscles and is protected anteriorly by patella. The patella

via patella tendon is connected to tibia (tuberositas tibiae), the proximal part

of patella is connected to quadriceps muscle and acts as a mechanical lever [8, 195]. The quadriceps muscle, the largest in the body, is the main extensor of the knee joint and has four parts: rectus femoris and the three vastus muscles- lateralis, intermedius and medialis [136]. The anterior, lateral and posterior aspects of the extra-articular structures of the knee joint are shown in Fig. 2.1.1. Ligaments play a colossal role in knee joint stability. Laterally and medially are collateral ligaments. Inside the joint (in the intercondylar notch) lie anterior and posterior cruciate ligaments responsible for smooth joint movement at bending and extending manoeuvres. The intra-articular structure of the knee joint is shown in Fig. 2.1.2. The condyles of the femur articulate with the condyles of the tibia, but are asymmetrical and appear to have no inherent stability.The larger medial femoral condyle is round, and the lateral condyle is longer and wider at contact area with the tibia. Condyles are separated posteriorly by intercondylar notch. The upper surface or plateau of the tibia possesses two separate articular facets, each slightly concave. The medial facet lies wholly on the upper surface of the condyle, but the lateral facet becomes slightly convex at the back where it curves back over the posterior margin of the tibial condyle [136]. Both tibial plateaus have a posterior inclination of 10 degrees.

(14)

(15)

On full flexion of the knee there is a posterior translation of the tibial on the femur through a combination of gliding and rolling of the femur [42, 103].

Fig. 2.1.2. The anatomy of the knee (ligaments)

Anterior Cruciate Ligament

The intercondylar notch (ICN) of femur houses the anterior and posterior cruciate ligaments. ICN is wider in the posterior part and converges toward the anterior direction. It is known that significant osteophyte formation and stenosis of the outlet of the anterior outlet of the intercondylar notch occur early in the ACL-deficient knee [215]. In these cases, a notchplasty should be considered at ACL reconstruction. The width of the notch is reported to be smaller in females when compared with males [15, 92, 185, 192, 199]. This could be another factor in explaining the higher incidence of ACL injuries in female athletes besides gender specific neuromuscular differences. The fe-males also get injured at a younger age than men [174]. A recent study found small gender differences in the overall risk of sustaining an ACL tear, although gender differences in injury rates were found when specific sports were compared [142]. As far back as 1938, Palmer [157] was the first investi-gator to describe mechanisms that a narrow intercondylar notch may place the ACL at risk for injury, as the ligament is stretched over the medial ridge

(16)

of the lateral femoral condyle. Since that time, a number of studies have been conducted to evaluate the role of a narrow intercondylar notch as a risk factor for acute ACL injury. While a group of authors reported that a narrow inter-condylar notch is associated with a higher risk of ACL rupture [114, 125, 184, 185, 190, 191], others stated insignificance [96, 123].

ACL (as it is shown in Fig. 2.1.3.) is attached to the anterior intercondylar area of tibia and to the posterior part of the medial surface of the lateral femoral condyle. Due to the ligament’s anterior attachment to the tibia (in relation to the posterior cruciate ligament, and these two ligaments “cross” inside the knee joint) the ligament was given the name anterior cruciate ligament. Despite its relatively small size, ACL plays an important role in the knee. Literature sources indicate, that anatomically ACL can be divided into two parts – anteromedial (AM) and posterolateral (PL) bands [215]. These structures are in tense in different portions of the knee joint range of motion, but recent studies suggest that both bundles are parallel and have a comple-mentary behaviour [104, 196]. Both bundles have similar diameters, with an overall diameter ranging from 7 to 17 mm (average = 11 mm according to Girgis et al. [80]). The primary blood supply to the ACL is the middle genicular artery, the branch of the popliteal artery, secondary supply are the inferomedial and inferolateral genicular arteries from the anterior fat pad [8, 136].

When the knee is extended, the PL bundle is tight and the AM bundle is moderately lax. As the knee is flexed, the femoral attachment of the ACL becomes a more horizontal orientation; causing the AM bundle to tighten and the PL bundle to loosen up. This concept has been confirmed by a biomechanical study performed by Amis and Dawkins [13].This study has

(17)

shown that the PL bundle is stretched in extension and the AM bundle is stretched in flexion, but none of the ACL fibres behave isometric.

Several studies have proposed that a smaller, biomechanically weaker ACL may be found in a smaller notch [14, 58, 192]. Davis et al [58] found a positive correlation, suggesting that a narrow ACL width represents a weaker, more susceptible ACL. However, other scientific studies have reported that the size of the notch did not correlate with the size of the ACL [14, 143]. The ACL receives nerves from branches of the tibial nerve that penetrate the joint posteriorly. Some nerve fibres with sensory ends are located in the ligament, isolated from the vessels [89, 108, 216]. Pitman et al. [163] have hypothesized that these nerve endings have an important proprioceptive function in the knee. Adachi et al. [2] found a positive correlation between the number of mechanoreceptors and accuracy of the joint position sense, suggesting that proprioceptive function of the ACL is related to the number of mechanoreceptors.

2.2. Biomechanics, injury and consequences of rupture of ACL

In daily activities joint sustains many external and internal forces but knee joint is stabilized with the help of four major ligaments: anterior and posterior cruciate ligaments, medial and lateral collateral ligaments (Figure 2.1.2.). The use of muscles assumes a key part in ordinary flexion and extension motion of the knee joint. The movement of the knee joint is governed by its ligaments, other supporting soft tissue structures, and the geometric constraints of the articular surfaces [211]. Forces transmitted through ACL vary with knee-joint position [187]. Arrangement of anatomic interrelationships allows the knee six degrees of freedom of motion: three rotations and three translations: the translations are anteroposterior (5 to 10 mm), compression-distraction (2 to 5 mm), and mediolateral (1 to 2 mm) [45]. These motions are limited by the ligaments, surrounding capsule, and to some degree the intra-condylar eminences of the tibia and are of small magnitude in the normal knee [187]. The rotations in the knee joint are flexion-extension, varus-valgus, and internal–external rotation, and in general, they are much more extensive than the translations. Normal flexion and extension of the knee is variable, ranging from 0° to 15° of hyperextension form 130° to 150° of flexion. Internal and external rotation ranges from little or no motion in full extension to 20° – 30° with the knee flexed. Tightening of the capsular and ligamentous structures, which is greatest in full extension, accounts for this variation [45]. Gabriel at al [78] tested an anterior tibial load and reported that the greatest forces transmitted through the AM bundle were at 60 and 90 degrees of flexion.

(18)

The force was the greatest for the PL bundle at full extension. Forces, transmitted through ACL estimated in vivo from force plate analysis, and found a peak load of 169N in level walking, 27N in ascending stairs, about 93N in descending stairs, 67N in ascending ramp and 445N in descending ramp [111, 141]. While other studies estimated the tensile forces in the ACL to be 67N in ascending stairs, 133N descending stairs and 630N in jogging [47]. Noyes et al. [149] have demonstrated the native ACL has an ultimate tensile strength of approximately 1725 ± 269N. Other studies [212, 213] reported that failure load of an ACL is to be about 2160 ± 157N in young individuals, and ultimate load and energy absorbed decrease significantly with age. Chandrachekar et al. [44] stated that load at failure is about 1818 ± 699N in males and about 1266 ± 527N in females.

However, during daily activities the ACL is loaded only to about 20% of its failure capacity [34, 99].

Injury of ACL

Rupture of the ACL was first described by J. Stark in the Edinburgh Medical and Surgical Journal in 1850 [56]. Since then, and especially during the last decades, this injury has been the topic of many publications. According to the literature, the ACL is the most frequently disrupted ligament in the knee joint [33, 100, 187, 196] and, of course, it occurs more frequently in athletes [20, 82, 100]. An ACL injuries may result in the early end of athletic careers and a serious disability in non-athletes [187]. Evaluating mechanisms of trauma, an anterior cruciate ligament tears are thought to occur with unsuccessful postural adjustments and with the result of abnormal dynamic load across the knee [87].

At the time of trauma, ACL tear occurs followed by a sudden pain, espe-cially on the inner side of the knee. The athlete may also feel like the whole knee shortly went out of place and may have a sense of instability and inability of walking. Additionally, severe swelling of the knee occurs within six hours of the time of injury. The athlete should seek the advice of an orthopaedic surgeon immediately. One of the failure mechanisms that litera-ture sources describe as the classic "unhappy trio" and, that occurs with ACL rupture, damage to the medial collateral ligament and rupture of the medial meniscus, is caused by a forceful valgus-external rotation of the knee [69]. This injury often occurs while skiing, when the knee is bent into valgus, and the tibia goes into external rotation. There are also non-contact injuries, often occurring with the knee close to extension during a sudden deceleration (changing direction and this involves rotational manoeuvres or lateral bending of the knee into a valgus position with the knee extended and the

(19)

tibia rotated) or landing motion. Contact injuries are frequently the result of a contact bump to the lateral aspect of the leg or knee, a motion that causes a valgus collapse [187, 196]. Dislocation of the knee, caused by high-energy trauma (motor vehicle accidents for instance) leads also to complete rupture of the ACL.

Review of the literature indicates that soccer (football) is the main reason for ACL rupture (in Unites States [75, 82, 100] for instance), but other contacts sports such as basketball, handball, football and even alpine skiing are common activities that result in injury as well [100, 138, 147]. ACL injury in Sweden occurs at an incidence rate of 78 to 81 per 100 000 [148] inhabitants per year, and almost 40% of those who become injured undergo reconstructive surgery [148]. Males sustain ACL injuries more frequently than females due to the greater number of male participants in sport activities [88]. In spite of that, the risk of sustaining an ACL injury is reported to be higher among female athletes compared to their male counterparts [4,20,88, 147,174].

Consequences of the injury

Studies consistently demonstrate that ACL rupture leads to increased laxity of the knee [54, 121, 178]. In order to decrease the risk of long-term deterioration of the cartilage, the reconstruction should restore normal kinematics to the knee [17, 72]. However, isolated ACL ruptures occur rarely. The injuries, including other ligament sprains, meniscal tears, articular carti-lage injuries, and bone bruises, complicate the treatment and outcome of ACL ruptures. There can be no doubt that the addition of one or more of these associated injuries adversely affect the outcomes of treatment, but it is very difficult to quantify or predict exactly how they will alter the results. Meniscal rupture frequently occurs at the time of an ACL injury, and the incidence increases in patients who do not undergo reconstruction [73]. Reports of articular cartilage injury associated with acute ACL disruption range from 15% to 40% and become much higher with chronic ACL deficiency [41, 117]. Nearly 50% of ACL related injuries are combined meniscus injuries [3, 40, 48, 156, 200]. However, ACL injury increases the risk of posttraumatic osteo-arthritis [164]. The systematic review concluded that there was a up to 13% knee osteoarthrosis (OA) prevalence 10–15 years after an isolated ACL injury and that patients with combined ACL and meniscal injuries had a prevalence of 21–48% [155]. It is reported, that secondary osteoarthritis is caused by factors, such as age and BMI [57, 172]. Several studies reported that more than 80% of ACL injuries were associated with bone bruises in the lateral compartment [102, 193]. Also, there is an increased risk of posttraumatic

(20)

osteoarthritis after an intraarticular fracture, even if the fracture is anato-mically reduced [16]. Even though many factors have been studied and the epidemiological connection between a traumatic knee injury and a post-traumatic secondary OA is clear, the mechanism responsible for secondary OA after an ACL injury is still yet unknown [43, 46, 66, 207].

2.3. Assessment of knee joint function

A detailed history assessment and physical examination to assess knee stability is the first thing to do while clinically diagnose ACL rupture. Acute ACL ruptures often produce a “popping” sound at the time of injury, and patients experience pain and instability secondary to laxity of anterior trans-lation (AP laxity) in an ACL deficient knee [73, 181]. Physical examination frequently establishes a diagnosis of ACL injury, especially if the examin-ation is done soon after the injury before swelling, pain, and muscle guarding occur. There are several methods to identify ACL rupture. In the clinical practice, knee laxity is evaluated using a Lachman test. This test is consider-ed clinically to be the most reliable diagnosis for an anterior cruciate ligament lesion [121, 153, 201]. The Lachman test is usually performed at 20° to 30° angle of knee flexion, stabilizing the distal femur with one hand while firm pressure is applied to the posterior aspect of the proximal tibia in an attempt to translate it anteriorly and anterior laxity is assessed in the degree of anterior translation of the tibia relative to the femur. The results should be compared with the non-injured knee. The Lachman test has been found to have a sensitivity of 85% and a specificity of 94% for ACL rupture [187]. The Lach-man test is a good qualitative assessment of the anterior drawer, but quanti-tatively speaking, this test correlates poorly with objective measurements. Considering the poor inter-examiner reproducibility in grading the Lachman test, a positive, doubtful or negative Lachman test should provide enough information [32]. The Pivot-shift test has been widely used to evaluate the integrity of ACL as well as provide information on the medial and lateral secondary ligament restraints after ACL rupture [151]. The test is performed to produce the pivot shift phenomenon, which was characterized by Galway et al. [79] as an anterior subluxation of the lateral tibial plateau in relation to the femoral condyle. The subluxation occurs as the knee approaches exten-sion, with reduction produced with knee flexion. When using the pivot shift test, a correct interpretation depends upon an accurate analysis of the knee rotations and translations that occur and the corresponding tibiofemoral subluxations also induced by the examiner [151]. As examiners often use dif-ferent pivot shift testing technique, the motions and subluxations induced may

(21)

differ, including the magnitude, and this may affect the diagnosis of ligament injury as well.

Functional (dynamic) instability also can be evaluated with a group of objective functional and strength tests and subjective functional knee scores, which may be helpful in determining who can potentially cope with the injury without surgery [61, 101, 106], and naturally also to assess ACLR outcome [22, 200]. Clinical diagnosis of ACL tears (Lachman test and Pivot shift test in valgus and internal rotation) is reliable in case of complete ACL tear but reveals elusive in case of partial tears. Quantitative assessment of anterior tibial translation proves to be imprecise, subjective and poorly reproducible [171].

In order to manage an anterior cruciate ligament injury, accurate assessment of knee laxity is crucial to be efficient. While clinical physical manoeuvres are essential, they often rely on subjective factors such as clinician (physician) experience, patients’ muscles relaxation, and inherent knee variability. To analyse the state and performance of the ACL, advanced imaging techniques such as the Magnetic Resonance Imaging (MRI) can also be used but cannot directly evaluate knee stability. Therefore, it is against this background that laximetry was set, to supplement physical exam findings. In the past, laximetry was only used for research purposes because of its object-ive results, which allowed comparison of different factors such as surgical techniques or rehabilitation regimens, but nowadays, it is more and more common to use laximetry to monitor post-operative laxity.

These days, measurements are commonly obtained using the KT-1000 (or KT-2000, newer version of KT-1000) laximeter (Medmetric, San Diego, CA, USA) first introduced in the early 80s by Daniel et al. [54]. The KT-1000 arthrometer is the most widely used knee ligament laxity measurement system because it is an easy-to-use device and still remains as a reference instrument in the many published scientific papers over the past few decades [171]. There is one more arthrometer, the Rolimeter (Aircast, Summit, NJ, USA) developed by Roland Jacob [179]. But these both measurement devices are operator-dependent, they do not take into account muscular relaxation of the patient’s thigh thus likely to induce false negative results and poor reproducibility [171].

Recently, a new arthrometer, the GNRB® (Genourob, Laval, France) was developed to eliminate the difficulties of using the KT-1000 or Rolimeter. The GNRB® arthrometer is electrically powered and incorporates pressure and movement sensors facilitating measurements that are more accurate. Results with the GNRB® suggest that this device has better inter- and intra- observer reproducibility than the KT-1000 and a displacement transducer has

(22)

0.1 mm precision [51]. Collete et al. [51] reported, that the GNRB® can be used by any physiotherapist, with no “examiner effect”. This is why we chose to use this laxity measurement system.

Fig. 2.3.1. KT-1000 testing machine [217]

The whole GNRB® system is shown in Fig. 2.3.2. While system measures ligament laxity, the patient is lying on a standard examination table in the supine position with the arms placed along the body, the healthy knees are investigated first. The lower limb is placed in a rigid adjustable leg support, with the knee placed and fixed at 0° of rotation. The knee is in neutral rotation so that the patella is facing anteriorly. The knee has to be placed correctly, that the inferior pole of the patella has to be covered by the lower border of the patellar support. This support exerts a symmetric pressure on the patella during the test, checked by a pressure control. The joint line is palpated and should be located between the thigh support above and the calf support below. An electric actuator exerts slowly (11 mm/s) increasing loads according to the examiner: 134N, 150N, 200N or 250N on the upper aspect of the calf. A displacement transducer (the accuracy given by the company is 0.1 mm) records the relative displacement of the anterior tibial tubercle with respect to the patella. The testing is repeated on both knees, and the amount of tibial translation is compared between the two limbs. All the data are collected on a remote computer. A laxity file is built up for each patient including measure-ment conditions (pressure applied to the thigh, load forces) and results (the

(23)

displacement–load curve, the side- to-side difference in mm and the slope in μm/N) (Fig. 2.3.3.).

Fig. 2.3.2. GNRB® system presentation [218]

To rule out any fractures or bony avulsions it is recommended to perform X-ray imaging of the knee. According to some studies reported, a Segond fracture, for instance, is an indicator of an ACL tear, especially in adoles-cence, characterized as an avulsion fracture of the proximal lateral tibia and proximal to the fibular head [77]. But, MRI is still the gold standard for diag-nosing ACL injury, with the sensitivity from 78 to 94% and specificity from 88 to 100%, and has approximately 94% accuracy [31, 203]. Concomitant injuries can also be identified on MRI, such as injuries to the posterolateral corner, to the collateral ligaments and to the menisci [144]. In addition, there is a good possibility to measure ICN width and other related measurements required for making decision in ACLR. The notch width of the femur can be measured using plain radiographs, and it is a ratio of the width of the inter-condylar notch to the width of the distal femur at the level of the popliteal groove. Studies indicate that the notch width index (NWI) in males is about 0.24 and in female is 0.23 [114]. Souryal and Freeman hypothesized that the

(24)

limit of "critical" stenosis is an NWI of less than 0.20 in males and 0.18 in females [191].

Fig. 2.3.3. GNRB® data file and curves

The notch is larger in males, not simply because of the larger overall size, but because the intercondylar notch simply occupies more space in the distal femur than in females (in relation with femur sizes). Whether this indicates a larger ACL is unknown, however.

2.4. Anterior cruciate ligament reconstruction

Since the first time Palmer [157] reported about ACL rupture was treated with an acute operative procedure [154]. The acute surgical treatment of ACL rupture was provided quite in a while, until a number reports of arthrofibrosis after acute ACLR forced surgeons to change ACLR procedures [134, 183, 186]. As it was mentioned earlier, there are many studies, reporting an increa-sing frequency of meniscus injuries and cartilage lesions with increaincrea-sing time

(25)

between injury and the ACL reconstruction [25, 49, 107, 109, 139, 158]. There are also reports of better results after reconstruction if it is done early on [10, 63, 168]. With the less invasive surgical technique we use today, the risk of complications due to early surgery seems less serious [39], but right time for reconstruction is still not decided.

Once the ACL is ruptured, the patient is offered to undergo ACL reconstruction. In the operating theatre, during ACLR surgery, the torn ACL is replaced by graft material. Initially, the torn ACL removed and tunnels drilled at the insertion sites of the ACL. The graft is placed in the tunnel and secured using various methods (for example, bio-degradable screws for the healing process of tendon into bone). Biological grafts are harvested from one’s own body (autograft) or from cadaver (allografts). The various auto-grafts that are used include the patellar tendon, hamstring tendon, and quad-riceps tendon. The autografts used worldwide are patella- and quadquad-riceps tendons, but here, in Lithuania, the semitendinosus tendon autograft is most commonly used, sometimes complemented with the gracilis tendon. Possibi-lities of using allografts, such as Achilles, tibialis anterior and tibialis posterior tendons are also available [113]. ACL reconstruction can fail due to recurrent instability, arthrofibrosis, or infection. Recurrent instability is the most common cause for ACL reconstruction failure and can be seen in 8% of patients [93]. Reconstruction failure can be subdivided into technical, biological and traumatic scenarios with the primary cause being laxity from ligamentous restraints [205]. ACL re-injury occurs in 6 to 13% of ACL-reconstructed knees and 2 to 6% sustain a contralateral ACL injury [200]. Graft selection

A variety of graft options are available for ACLR [169]. The most commonly used are: BPTB and the 4-strand hamstring tendon made of gracilis and semitendinosus tendons [1]. Both BPTB and HT autografts result in a functionally stable knee in more than 95% of surgeries with a 3% absolute difference in graft failure: 1.9% with BPTB and 4.9% with HS tendon grafts [74, 187]. In a meta-analysis of 24 trials in 18 cohorts with a total of 1512 patients, Biau et al. found similar stability with a BPTB and the HT graft according to the Lachman test, but the BPTB graft resulted in more anterior knee pain, loss of extension and more problems with kneeling [36]. In another meta-analysis, Biau et al. attempted to raise the level of evidence by pooling individual patient data from six RCTs for a total of 423 patients. BPTB and HT were compared according to the pivot shift and they found a decreased risk of a positive pivot shift after a BPTB graft [35]. But biomechanical studies have shown that 4-strand HT graft was equivalent or superior strength

(26)

compared to BPTB graft [91, 209]. A recent Cochrane report by Mohtadi et al. used data from 19 studies with a total of 1597 patients and found more stability with BPTB than HT grafts [140]. The selection of the best graft to use then depends mostly on the morbidity created by the graft harvest produce. An allograft clearly has the lowest donor site morbidity, but other aspects of allograft use make this graft choice controversial, and in Sweden it is rarely used in primary ACL reconstructions [127, 166]. Even recent meta-analyses of comparative studies have failed to identify any significant differences in terms of outcomes when comparing a BPTB autograft versus HT autograft [190].

Spragg et al analysed relationship between HT graft diameter and revision rates. That study revealed, when looking at graft size alone, a patient with a 9-mm diameter graft is 55% less likely to be a case than a patient with a 7- mm diameter graft [194]. Magnusen et al study reported at an average of 14 months, a 1.7% revision rate in grafts >8 mm, a 6.5% revision rate for grafts 7.5 to 8 mm, and a 13.6% rate for grafts <7 mm [128]. Therefore, according to these studies, the smaller grafts also may lead to failure. Park et al study showed different results - there was a significant difference in the failure rate between cases with a graft size <8 mm compared with a graft size >8 mm, with no revisions surgeries in the <8 mm group [159].

The literature sources report good ACLR single-bundle results [62, 63, 115, 129]. There are several studies indicating that nearly 15-25 % of patients still report pain and recurrent instability after reconstruction [74]. There is a risk for young athletes of re-injury and injury for contra-lateral side, because this occurs when they come back to sports too soon and involve strenuous sports activities. A long-term complication after ACL injury, as it was mentioned earlier, is the development of early osteoarthritic changes [70, 74]. Revision surgery is indicated if a patient complained of knee joint instabi-lity (that occurs in later stages), so the way to measure knee function in real-life situations is to assess at what level of activity the patient can function after the ACLR. A number of questionnaires have been developed to assess this information [150], but the Tegner [198] activity scale is a frequently used scale in Europe [77, 95, 189].

2.5. Functional tests for recovery evaluation

Despite advances in ACLR surgical techniques and criterion based rehabilitation, a lack of a gold standard persists in defining a successful outcome following ACLR [125]. The surgical goal of ACLR is the restoration of stability and functional capacity of the knee [19]. Implicit in this

(27)

expectation is the ability of the patient to resume their desired level of sports participation once the normal biomechanics of the knee has been restored. To assist with returning a patient to competitive or recreational sports, many scientist have developed rehabilitation protocols with to return-to-play criteria [1]. There has been no consensus as to which functional tests should be utilized to make determination or what values should be achieved at different time points post-operatively. The most commonly reported tests were the hop tests as well as isokinetic knee flexion and extension strength [1]. Single-legged hop tests are performance-based measure tests used to assess the combination of muscle strength, neuromuscular control, confi-dence in the limb, and the ability to tolerate loads related to sports-specific activities [168]. A limb symmetry index (LSI) of 85 to 90% has often been used for ACLR patients to be regarded as sufficiently rehabilitated [23, 55]. Logerstedt et al. [122] state, that hop tests are clinically useful in predicting future outcomes and help predict who will have knee function within or below normal ranges in the medium term (one year after ACL reconstruction).

Although these tests have good discriminative ability, no studies have examined the predictive ability of hop tests for knee function after ACL reconstruction.

(28)

3. MATERIAL AND METHODS

The study was conducted in the department of Orthopaedics and Trauma-tology, Sports Injuries and Arthroscopy Sector in the Hospital of Lithuanian University of Health Sciences (HLUHS OTD SIAS) by the study plan, approved by Institute of Sports at LUHS Medical Academy. This study was also approved by Regional Biomedical Research Ethics Committee, No.: BE-2-30.

3.1. Study design

To achieve study goals, two independent study parts were conducted.

Study part I

The retrospective study was carried out to evaluate which method of ACLR (using BPTB or HT graft) produce better post operational results (outcomes) by comparing return to pre-injury sport level. The retrospective chart review of prospectively collected data was performed in consecutive patients (HLUHS OTD SIAS), from January 2011 to January 2014. The patients, who met inclusion criteria and with minimum of 2-year follow-up were included. The analysed patients were divided into two groups according to who underwent primary ACLR with BPTB or HT autografts. Graft type, size, patient age, sex, and body mass index were recorded at the time of ACLR. Both groups were matched accordingly to associated meniscal injury and surgical repair incidence.

Patients completed IKDC survey; Tegner activity score was recorded. IKDC is The International Knee Documentation Committee (IKDC) deve-loped evaluation form to classify the outcome after knee ligament injuries (and after ACLR) [94]. IKDC 2000 is an objective form, created in 2001, consists of seven groups of problem areas and filled in by a patient and physician: subjective assessment (effusion), passive motion deficit, ligament examination, compartment findings, donor site pathology, radiological findings and functional tests. Every evaluation point is rated as normal (A), nearly normal (B), abnormal (C) or severely abnormal (D). The lowest rating in every problem area determines the rating for that problem area. The lowest rated problem area determines the final overall IKDC rating. The patients filled subjective IKDC survey, where three main problem areas were evaluated (symptoms, sport activities and function). There are only 10 questions in total. The item scores for questions 1 to 9 are summed up and transformed (using mathematical equation) into a scale from 0 to 100. A score

(29)

of 100 is interpreted to mean no limitation in active daily life or sport activities and no symptoms. IKDC is a reliable and valid instrument to measure symptoms, function during daily activities, and sports activity in patients with different knee problems such as ligament or meniscal injuries, articular cartilage lesions, osteoarthritis, or patellofemoral pain [86]. Although IKDC is generally accepted as standard for reporting the status of the knee, the subjective nature of the grading system and the potential lack of repeatability are significant limitations [167].

The patients assessed their activity score (as it was before injury) and at the current follow-up. The Tegner activity score is a simple freely available measure of activity level that spans work, sporting, and recreational activities. This scale numerically evaluates sport and work activities from 0 to 10. The scale was presented by Tegner and Lysholm in early 1985 and was meant to be used in combination with the Lysholm scale [198]. The level from 7 to 10 corresponds to competitive sports, 4 to 6 to recreational sports and 0 to 3 to activities of daily life.

Surgical technique was as follows - after diagnostic arthroscopy and, if needed, meniscal procedures, the ST/G (semitendinosus and gracilis) or the patella tendon were harvested through a short typical vertical incisions located medial to the tibia tuberosity (hamstring harvest) and medial -

para-patellar incision (patella tendon harvest). Each HT graft was doubled with

sutures at both ends of the graft (Vicryl 2-0 sutures on the femoral side of the graft, and non-absorbable sutures on the tibia side of the graft). The diameter of the graft was measured using a calibrator (accuracy: 0.5 mm) at its middle part. The anatomical [60, 68] femoral tunnels were drilled first. They were created ante grade through one very low anteromedial (AM) portal. Next, the tibia tunnel was prepared; the arthroscopic aimer was inserted to the knee through the AM portal and was adjusted to 45°, when drilling, and was positioned approximately 5 mm in front of posterior cruciate ligament in a middle distance between the anterior horn of lateral meniscus and medial eminence ridge of tibia. After the guide pin was drilled, the drill guide was removed and the knee was passively extended to exclude an impingement on the anterior intercondylar notch and medial wall of lateral femoral condyle. Once a check was performed, the tibia tunnel was established with a cannu-lated reamer to the graft diameter. Intercondylar notch was widened if needed. The reaming debris was evacuated with a synovial shaver to minimize the fat pad inflammatory response. After the tunnels on both the femoral and tibia side were created, the graft was inserted and then fixed with bio-absorbable interference screws proximally and distally. The knee was cycled several times through range of motion and the graft was examined arthroscopically

(30)

to check knee stability, tension and fixation quality and to exclude graft impingement.

The postoperative care and rehabilitation protocol was the same in the two groups. An extension knee brace was used for two weeks with protected weight bearing allowed for two weeks as tolerated. On the second postoperative week, the brace was fixed to allow motion between 0° and 60° of flexion, quadriceps activity against gravity, and hamstring contractions were permitted. Four weeks after surgery, the patients were allowed knee motions between 0° and 90° of flexion, and quadriceps exercises were allowed between 45° and 90° of flexion. At six to eight weeks, full isotonic hamstring contraction, hip abductor-adductor exercises, and swimming were permitted. At eight weeks, the patients were encouraged to achieve a full range of motion, to extend the knee against unlimited resistance between 45° and 90° of flexion, and to ride a stationary bicycle with resistance. At twelve weeks, unrestricted isotonic quadriceps strengthening was allowed between 0° and 90° of flexion. Return to sports activity was allowed gradually eight to 12 months postoperatively, and after one year without any restrictions (if knee stability and function are normal, otherwise extended rehabilitation was recommended).

The study is publicized in Medical Science Monitor as second paper, indicated in List of Publications section.

Study part II

Based on Study I findings, in order to eliminate graft type influence on recovery outcomes, the prospective Study II was conducted to find out

influence of graft diameter on recovery results after ACLR using HT

autografts. The baseline data collection for this study was carried out in the HLUHS OTD SIAS, between January 2015 to January 2017. From the total pool of 360 ACLR patients, 214 consecutive patients, who met inclusion criteria, with a completed follow-up of 12 months were enrolled in this study. All patients were hospitalized on the same day of surgery or one day before surgery. Patient’s age, gender, injury date, injured side, either was contact trauma or not, height and weight were recorded and patients’ BMI was calculated. The patients completed IKDC survey, Tegner activity score was recorded and GNRB® was performed for preoperative measurements. Work flow diagram is presented in Fig. 3.1.1.

All patients were tested using GNRB® laximeter on the day of hospital-isation. The procedure was performed exactly as it was described in chapter 2.3. and publicised by Robert et al [171]. The difference between healthy and

(31)

injured leg at 134N force was measured and defined as “Δ134N”. The force 134N used to validate the GNRB® to compare with KT1000™, widely used knee arthrometer.

An anatomical single-bundle ACLR with autologous hamstring (semitendinosus-gracilis) tendon grafts (minimum graft diameter in this study was 7.0 mm) was performed for every single patient. The surgical technique was the same as in Study part I. The diameter of the middle of the graft pre-pared in a close loop was measured using a calibrator. Prepre-pared HT graft is shown in Fig. 3.1.2.

Fig. 3.1.1. Study II work flow diagram

The postoperative care and rehabilitation protocol was as follows: an extension knee brace was used for two weeks with protected weight bearing allowed for two weeks as tolerated. On the second postoperative week, the brace was fixed to allow motion between 0° and 60° of flexion, quadriceps activity against gravity, and hamstring contractions were permitted. Four weeks after surgery, the patients were allowed knee motions between 0° and 90° of flexion, and quadriceps exercises were allowed between 45° and 90° of flexion. At six to eight weeks, full isotonic hamstring contraction, hip abductor-adductor exercises, and swimming were permitted. At eight weeks, the patients were encouraged to achieve a full range of motion, to extend the knee against unlimited resistance between 45° and 90° of flexion, and to ride a stationary bicycle with resistance. At twelve weeks, unrestricted isotonic quadriceps strengthening was allowed between 0° and 90° of flexion. Return to sports activity was allowed gradually eight to 12 months postoperatively, and after one year without any restrictions.

Follow-up examinations were performed at 3, 6 and 12 months postopera-tively. The patients were divided into groups according to differential

(32)

laximetry (∆134N) and results were defined as good, fair and residual laxity while ∆134N ≤ 1.4 mm, 1.5 < ∆134N ≤ 3 mm and ∆134N > 3 mm, respectively.

Upon completion of the 12 month follow-up, the patients performed 4

single- legged hop tests: the single hop for distance (single hop), crossover hop for distance (crossover hop), triple hop for distance (triple hop), and 6-meter timed hop (6-m timed hop) (Fig. 3.1.3.) [152]. These 4 tests have demonstrated good test-retest reliability in normal, young adults [175] and in patients after ACL reconstruction [168].

Fig. 3.1.2 HT graft after preparation

The first, single hop for distance was performed with the patient standing on the leg to be tested, hopping as far as possible, and landing on the same leg. For the crossover hop for distance, the patient stood on one leg, then hopped as far as possible forward tree times while alternately crossing over a marked strip on the floor. The total distance hopped forward was recorded. The triple hop for distance was performed with the patient standing on one leg and performing three consecutive hops as far as possible. The single hop, the crossover hop, and the triple hop for distance were considered successful if the landing was stable. A valid trial considered as the landing on one limb,

(33)

under complete control of the patient. If the patient landed with early touch-down of the contralateral limb, had loss of balance, or had additional hops after landing, the hop was repeated (if no pain or other disabilities) and the trial was considered as failed. The patients were instructed to begin trial with the uninjured leg, behind a marked starting line. The hop distance was measured from the starting line to the patient’s heel with a standard tape measure. For the 6-m timed hop, the patient stood on one leg, then hopped as fast as possible over a marked distance of 6 meters. The time was recorded with a standard stopwatch. The stopwatch was started when the patient’s heel left the floor and stopped when the patient landed over the finish line. Measurements were recorded in 1/100th_{of a second. The single-legged hop} scores were calculated as the average of two measured trials for each limb. The limb symmetry index (LSI) was expressed as a percentage of the averaged involved limb hop distances divided by the averaged uninvolved limb hop distances for each hop distance test. For the 6-m timed hop, LSI was expressed as the percentage of the averaged uninvolved limb hop time divided by the averaged involved limb hop time. An 85% LSI (< 15% difference between limbs) was determined to be satisfactory result for hop tests [24].

Fig. 3.1.3. Single-legged hop test pattern

The patients who completed all four single-legged hop tests were considered to have achieved good functional outcomes and reached pre-injury functional

(34)

level. The numerical value of this functional test constituted a common part of the IKDC objective questionnaire and had a significant effect on the final outcome of the treatment.

3.2. Study population Study part I

Total 183 of 200 patients (91.5%) with a mean age of 25.3 ± 5.1 years (18 to 32 years) who underwent primary ACLR with BPTB or HT autografts were evaluated: anatomical single-bundle HT (n = 95), and single-bundle BPTB (n = 88) (Fig. 3.2.1.). Baseline characters were similar in the two groups (Table 4.1.1).

Fig. 3.2.1. Flow-chart diagram of the study part I

Excluded from study n

= 128 (no contact not

Total eligible patients n = 200

Excluded from study n = 8 (no contact, not met inclusion criteria)

Enrolled for study n = 196

Lost to follow-up n = 9 (lost contact, recurrent trauma, other etc.)

Cases in final follow-up n = 183 (91.5 %)

BPTB

n = 88

HT

(35)

There were 43 professionals (competitive sports level) athletes in the HT group (19 basketball, 11 football, 2 volleyball, 9 handball players and 2 cyclists), and 45 in the BPTB group (15 basketball, 12 football, 10 handball, 5 volleyball and 3 rugby players). Both groups were matched accordingly to associated meniscal injury and surgical repair incidence (Table 4.1.2.).

Study part II

The total of 361 ACLR patients of the year 2015 was targeted for enrol-ment. After screening there were 218 consecutive ACLR patients enrolled in this study (study flow diagram is shown in Fig. 3.2.2.). There were 163 (75%) men and 55 (25%) women with the mean age 33.3 ± 9.7 years (range 18 – 57), median was 33 years. The patients were divided into three groups according to the diameter of the middle of the graft (Ø ≤ 8 mm, 8 mm < Ø ≤ 9 mm, and Ø > 9 mm) and the means of the graft diameter significantly differed in all three groups (p < 0.001).

Fig. 3.2.2. Flow-chart diagram of the study part II

Excluded from study n

= 128 (no contact not

Total ACLR patients n = 361

Excluded from study n = 129 (no contact, not met inclusion criteria)

Enrolled for study n = 232

Lost to follow-up n = 14 (lost contact, re-rupture, inflammation etc.)

Cases after 12-months follow-up n = 218 (94%)

Ø ≤ 8 mm

n = 50 8 < Ø ≤ 9 mm n = 88

Ø > 9 mm

(36)

There were 50 (23%), 88 (40 %) and 80 (37 %) in groups Ø ≤ 8 mm, 8 mm < Ø ≤ 9 mm, and Ø > 9 mm, respectively. The demographic data of the study across the groups are presented in Table 4.2.1.

3.3. Inclusion and exclusion criteria

Study individuals were seen at the hospitalizing visit and again after surgery, and their eligibility for the study was checked based on inclusion and exclusion criteria (Table 3.3.1.). All participants were acquainted with the study and written informed consent was obtained.

Table 3.3.1. Inclusion and exclusion criteria

Inclusion criteria Exclusion criteria Complete ACL tear Partial ACL tear Reconstruction using HT graft Bilateral ACL ruptures Age 18 to 55 years Combined ligament injuries

Tegner activity level recorded Injury of the posterior cruciate ligament Inflammation process in knee joint Concomitant fractures

Graft size <7 mm. Refusal to participate

3.4. Statistical analysis

Statistical analysis was performed by using the Statistical Package for the Social Sciences, version 24.0 for Windows (IBM SPSS®_{24.0). The normality} assumption of data was verified with the Kolmogorov-Smirnov or Shapiro-Wilk tests. All the data that were normally distributed are presented as a mean and a standard deviation (SD), 95% confidence interval (CI) for mean. The mean outcome measures have been presented with mean differences between the groups with 95% CI. All the data that were distributed not normally are presented as median and range. ANOVA was used to compare the normally distributed variable between the three groups. Adjustment for multiple comparisons was made using the Bonferroni comparison test. General Linear Model (Repeated Measures) was used to evaluate follow-up examinations, which were performed pre-surgery and at 3, 6 and 12 months postoperatively. The assessments at four different time points (before surgery, 3, 6 and 12 months postoperatively) for outcome variables were used as time factor

(37)

(within-subject factor) and analysed by investigation groups (between-subject factor). Bonferroni pairwise multiple comparisons test was used for post hoc pairwise comparisons. Comparing the quantitative data that are not distribut-ed according to normal distribution applidistribut-ed nonparametric ordinal analysis. The difference between two independent groups was analysed using Mann-Whitney U test. Kruskal-Wallis (One-way ANOVA on ranks) test was used to determine statistically significant differences between more than two groups of an independent not normally distributed variable. To evaluate diff-erences between categorical factors the Pearson chi-squared (2) test and Fisher’s exact test were used. The relationship between investigated variables was estimated by using the Pearson correlation coefficient and multiple regression analysis. The suitability of the multiple regression model was eval-uated with coefficient of determination R2_{. We calculated the coefficients of} regression equation and their significance levels p. Logistic regression model for potential risk factors was made. The model parameters were determined by maximum likelihood estimation. A variable selection method was Forward Stepwise (Likelihood Ratio). The p value for statistical testing of variable significance for inclusion in and exclusion from the model is generally set to 0.05. The criteria to assess the quality of a classification model were discri-mination. The level of significance was set at 5% for all the tests.

One of our main outcome measurements was the subjective IKDC score. With a difference of 10 points, clinically significant differences between the groups were acknowledged. The minimum sample size required for each sample that would be able to accept the clinically important difference between the means of two populations is given by formula [188]:









2 2 1 1 2 2 2 1











s

z



z



n

_, where: 2 1 s and 2 2

s are variances of pilot samples;  is the smallest clinically important difference of means chosen by the researcher; z1__and z1 are

quantiles of the standard normal distribution. Thus, accepting less than 5% probability of a type I error and a power of 80%, sufficient sample size would be 50 patients in each group.

(38)

4. RESULTS

4.1. Study part I

All data and patients’ outcomes at 2-year after reconstruction were avail-able in 183 patients (91.5%). Demographic data are presented in Tavail-able 4.1.1. The mean time interval from injury to reconstruction was 6.2 ± 6.2 weeks in the BPTB group and 5.1 ± 3.2 weeks in the HT group (p = 0.139). There were 57 concomitant partial medial meniscectomies and 26 partial lateral meniscectomies performed in this study and there was no difference in the prevalence of meniscal tears between the two groups observed. Meniscal procedures did not differ significantly in both groups. Thus, menisci injuries in both groups were equal and equally could bias the results, either repaired or removed, so statistically had the same influence on the difference of the final ACLR results in both groups.

Table 4.1.1. Study part I pre-operative data

HT group (n = 95) BPTB group (n = 88) p value Gender Male Female 66 29 61 27 0.440 Age in years 25.1 ± 4.9 26 ± 5.1 0.200

Body Mass Index 20.5 ± 2.1 20.6 ± 1.7 0.730 Lachman IKDC A IKDC B IKDC C IKDC D 0 0 44 51 0 0 54 34 0.450 Pivot shift IKDC A IKDC B IKDC C IKDC D 0 0 62 33 0 0 57 31 0.410

IKDC subjective score 65.5 ± 5.6 64.8 ± 4.9 0.353 Tegner activity score 6.5 ± 1.1 6.7 ± 1.0 0.140 Professional athletes

(39)

Clinical evaluation and IKDC subjective score

According to the subjective IKDC score, all the patients in two groups got significantly better at the two-year follow-up (p < 0.001). However, the HT ACLR group showed significant lower subjective IKDC evaluation results compared to the BPTB group (88.5 ± 2.8 vs. 89.2 ± 2.5; p = 0.038) (Figure 4.1.1). The IKDC objective evaluations and knee stability IKDC objective results were excellent (grade A) and good (grade B) in 83 of 88 patients (94.3%) after ACLR with BPTB and in 78 of 95 patients (82%) after ACLR with HT graft (p < 0.001) (Table 4.1.2). There was no difference between the groups with respect of range of motion at 2-year follow-up (p = 0.440). The percentage of manual AP knee laxity and positive pivot-shift signs was higher in the HT ACLR group compared to the BPTB group at two years (p < 0.001; Table 4.1.2.). At the two-year point, 81 patients (92%) who had ACLR with BPTB technique had a negative pivot-shift sign, 5 patients (6%) had a glide-positive sign and 2 patients (2%) had moderate and marked subluxation.

Fig. 4.1.1. The mean IKDC subjective score pre-surgery and at 2-year

after the ACLR.

(40)

At the same time-interval, 72 patients (76%) who had an ACLR with HT technique had no pivot-shift sign, 11 patients (12%) had a glide-positive sign and 12 patients (13%) had moderate and marked subluxation (Table 4.1.2.).

Activity level and return to pre-injury sport activities

There were 83 of the 88 patients (94%) in BPTB group and 69 of the 95 patients (73%) in HT group who were successful in returning to their previous level of sports activity at different times after ACLR (Table 4.1.3.).

The average of Tegner activity score in the HT group decreased from 6.5 at injury to 5.8 at two-year follow-up (p < 0.001) and from 6.7 at pre-injury to 6.5 at 2-year follow-up (p = 0.400) in the BPTB group. The ability to restore pre-injury sports activities was higher after ACLR with BPTB graft (6.5) compared to HT graft (5.8) (p < 0.001) (Fig. 4.1.2.).

Fig. 4.1.2. Tegner scores pre-injury and at 2-year after the ACLR. *significant difference at p < 0.001

INFLUENCE OF GRAFT TYPE AND DIAMETER ON KNEE FUNCTIONAL OUTCOME RESULTS AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Rokas Jurkonis