Case Report
History
A 37-year-old male farmer underwent an arthroscopic partial medial meniscectomy in his right knee at an outside center. Unfortunately following his surgery, the patient developed an acute staphylococcal infection, which was ini- tially treated by arthroscopic irrigation and debridement, followed by an open irrigation and debridement two weeks later. He was placed on a six-week course of intravenous antibiotics and concurrently received physical therapy in an attempt to improve the range of motion of his stiff knee. Despite physical therapy, he con- tinued to have swelling and decreased range of motion.
Approximately 18 months later, the patient was treated by another physician at an outside center with an arthroscopic lysis of adhesions, manipulation under anesthesia, and postopera- tive physical therapy for persistent stiffness.
Subsequently, his range of motion reportedly improved to 5° to 120° of flexion. However, the patient reinjured his knee while performing exercises less than one year later. He again expe- rienced a gradual loss of motion with intermit- tent swelling as well as medial-sided knee pain.
The patient was then prescribed a course of Prednisone and Celebrex, which did not provide any significant relief.
The patient presented to our center with the primary complaint of right knee stiffness, par- ticularly in flexion, which caused him difficulty working on his farm and stepping down stairs or inclines. He was also experiencing mild pain in the anterior and medial aspects of his knee, but the pain was tolerable. His past medical and social history were noncontributory.
Physical Examination
On examination, he was mildly overweight with a normal gait. His right knee was neutrally aligned and his left was in 2° of valgus. The squat was lim- ited to 90° on the right side secondary to pain.
His active and passive ranges of motion were equal, with a range of 3° to 90° for the right knee and 0° to 130° for the left. His right quadriceps muscle was 10% atrophied and he had no effu- sion. Patellar exam revealed a −10° tilt for his right patella compared with a 0° tilt for the left.
For the right knee, patellar glide was 1+ laterally, and 0 medially, superiorly, and inferiorly. His left knee had a 2+ medial and lateral patellar glide.
Ligamentous exam revealed a symmetric, stable knee. The patient had 2+ joint line tenderness of the right knee in the middle and posteromedial aspects and no lateral joint line tenderness.
Flexion McMurray test was negative.
Imaging Studies
Knee flexion weightbearing, lateral, Merchant, and long-cassette radiographs and an MRI were obtained (Figures 22.1 and 22.2). The radiographs were significant for medial joint space narrowing and positive Fairbanks changes. Mild to moderate changes were noted in the patellofemoral com- partment and the lateral compartment appeared normal. The lateral radiograph revealed 1 cm of patella infera on the right knee compared to the left. Abundant retropatellar scar tissue was observed on the MRI.
Diagnosis
1. Arthrofibrosis secondary to postoperative septic arthritis, including patellar entrapment and early patella infera.
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Arthrofibrosis and Patella Infera
Christopher D. Harner, Tracy M. Vogrin, and Kenneth J. Westerheide
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Figure 22.1. Flexion weight-bearing view with patella infera visible in the right knee (a). Lateral radiographs demonstrating patella infera on right knee (b).
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2. Moderate medial compartment degenerative joint disease and mild patellofemoral degen- erative changes.
Initial Management
For treatment of the arthrofibrosis, alternatives discussed with the patient included splinting or bracing, physical therapy, CPM, and manipula- tion under anesthesia. It was recommended that arthroscopic or open excision of scar tissue be
performed with the goal of increasing his flexion by 10 to 20 degrees. If this could not be achieved, the patellar tendon would be reconstructed using semitendinosus autograft. Following dis- cussion of options, surgical techniques, and risks and benefits, the patient elected to undergo the surgery.
In addition, a medial unloader brace was rec- ommended for treatment of the medial com- partment degenerative changes. We believed
Figure 22.2. Three sagittal views of a T1-weighted MRI demonstrating retropatellar tendon scar tissue (a,b,c).
that an osteotomy would be unlikely to provide significant benefits until his range of motion was improved.
Surgical Findings and Technique
Bilateral extremities were prepared and sterilely draped to enable intraoperative comparisons of range of motion and patellar height (Figure 22.3).
The patient’s previous midline incision was used and extended from 3 cm above the superior patel- lar pole down to the level of the tibial tubercle.
Sharp dissection was continued down to the level of the fascia, preserving full thickness flaps (Figure 22.4). This enabled visualization of the entire width of the extensor mechanism, which revealed extremely poor patellar motion. Scar tis- sue was palpable throughout the extensor mech- anism, as well as between the subcutaneous tissues and the tendon itself.
A medial arthrotomy was made, curving along the patella and paralleling the medial side of the patellar tendon. Abundant scar tissue was noted behind the patellar tendon and was resected, taking care to preserve the meniscus (Figure 22.5). Another arthrotomy was made along the lateral aspect of the patella in order to remove scar tissue from the retropatellar area and the lateral fat pad. The extensor mechanism
was found to be scarred down to the femur itself.
Metzenbaum scissors were used to release this tissue and recreate the suprapatellar pouch as well as the medial and lateral gutters.
After releasing the scar tissue, knee flexion was improved but still not equal to the contralat- eral side. It was thought that central third of the patellar tendon was providing the majority of the restraint. Therefore, the decision was made to
“pie-crust” the central third of the patellar ten- don (Figure 22.6). Multiple relaxing incisions in a transverse orientation were first marked care- fully using a pen and then made using a #11 blade. Upon flexion, the relaxing incisions lengthened, providing 120 degrees of flexion, which was slightly less than the contralateral side. A lateral release was performed to improve patellar mobility and tracking. After deflating the tourniquet and performing hemostasis, the arthrotomies were closed anatomically with the knee maximally flexed. A brace was applied and the knee was locked in full extension.
Post-Op Rehabilitation
Immediately postoperatively, the patient was locked in extension in order to protect the exten- sor mechanism, and allowed to weight-bear as tolerated. In order to maintain the flexion that
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Figure 22.3. Intraoperative comparison demonstrating decreased flexion in the right knee.
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was achieved, continuous passive motion was started immediately from 0 to 50 degrees of flexion for two sessions per day for two hours each.
These sessions were increased by 5 degrees per session if tolerated, up to a maximum of 120 degrees. He was also directed to perform straight leg raises, quadriceps sets, and heel slides.
Physical therapy was initiated in order to main- tain his range of motion.
Case Discussion
Arthrofibrosis is a potentially severe complication of knee surgery or trauma, including arthroscopy, cruciate ligament reconstruction, prolonged immobilization, or septic arthritis as in this case example.1-7It is characterized by a wide spectrum of pathologies that result in a loss of motion due to inflammation and scarring. This may include intra-, peri- and extra-articular adhesions, with the resulting development of Cyclops lesions, patellar entrapment syndrome, patella infera, or infrapatellar contracture syndrome.1-7
Making the Correct Diagnosis
Prevention and early diagnosis are key for the successful treatment of an entrapped patella.
Therefore, obtaining a complete history is criti- cal, including the date of surgery, length and type of immobilization and rehabilitation, and onset of pain and stiffness. Typically, the patient will complain of knee stiffness and pain, with physical examination revealing alterations in
gait, crepitation, and possibly quadriceps weak- ness. Patellar glides are often reduced due to entrapment. If patella infera is present, the knee may lose its rounded contour at 90 degrees of flexion; however, this may not be obvious if swelling is present.3If the patient is diagnosed and treated early (i.e., within three months), he or she can still be successfully treated.7
Pathoanatomy
Patella infera is a manifestation of severe arthrofibrosis, resulting in tightening of the extensor mechanism, increased articular pres- sures in the patellofemoral joint, and restricted knee flexion.3Inflammation in the joint results in fibrous proliferation behind the patellar tendon, which then adheres to the tibia. Subsequently, the patella may adhere to the fat pad, occupying the entire space between the notch and joint lines. The fatty tissue is replaced by a dense fibrotic tissue that is abundant anteriorly and in the medial and lateral gutters.3 If the patella infera is present for more than six months, a pannus may form that impinges into the joint and may damage the cartilage. Tendon shorten- ing may also occur, as in this case example, sec- ondary to the fibrosis and quadriceps atrophy.7
Paulos and colleagues described the Infra- patellar Contracture Syndrome (IPCS), which is the combination of patellar entrapment due to arthrofibrosis and loss of both flexion and extension.3It may occur secondary to knee
Figure 22.4. Midline incision with full thickness flaps for exposure.
surgery, reflex sympathetic dystrophy, quadri- ceps insufficiency, neuromuscular disorder, or infection.3,7 They described three stages that were indicative of prognosis: The early, or pro- dromal, stage (2–8 weeks) is characterized by induration of the synovium, fat pad, and reti- naculum, and is manifested by painful range of
motion, restricted patellar mobility, and quadri- ceps lag. Often a difficult, painful rehabilitation serves as a clue for diagnosis. In the active stage (6–20 weeks), the indurated tissues may form a shelf beneath the patella, further restricting patellar glides and tilts. The quadriceps lag dis- appears, but quadriceps atrophy and crepitus
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Figure 22.5. Medial arthrotomy and removal of extensive retropatellar scar tissue.
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may be present and the patient cannot achieve full extension. After approximately 8 months, the third, or “burned out” stage is reached, in which the inflammation and induration have subsided and patella infera develops. There is a
loss of both flexion and extension, quadriceps atrophy, severe crepitus, and diminished patellofemoral joint space. Although the patient in this case example did not have a severe loss of extension, it would appear based on his history
Figure 22.6. Pie-crusting central third of patellar tendon.
and examination that the patient in this case example is in the early third stage.
Surgical Indications and Technical Pearls
For those diagnosed in the early stages of arthrofibrosis and patella infera, nonsurgical management can often be successful, such as daily physical therapy with early range of motion exercises, manual patellar mobilization, nonsteroidal anti-inflammatory drugs, corticos- teroids, and electrical stimulation of the quadri- ceps.3,7Manipulation or a drop-out case can also assist in obtaining full extension.
If surgery is needed, it is usually important to wait for 4 to 12 weeks. In this time, the patient can improve quadriceps strength while pain, swelling, and inflammation diminish.3Manipulation and arthroscopic soft tissue release are usually the ini- tial step taken, although repeated attempts to improve motion manually in the presence of fibrous adhesions may only cause further damage to the articular surface.6It is critical to assess the quadriceps function prior to surgery, as the extensor mechanism may be further inhibited and the patella infera will persist.7
When manipulation and soft tissue release fail, open debridement and release is required.2,3,5This enables adequate visualization so that all patho- logical structures can be debrided or excised.2 Open debridement may include anterior, medial, and lateral extra-articular release and partial fat pad resection. The patella is freed intra-articu- larly in the medial, superior, and inferior direc- tions; often a medial arthrotomy may be required to achieve this. The suprapatellar pouch and intracondylar notch are also debrided. Posterior surgical release to improve extension should not be performed unless the previous approach was also posterior and unless release of the tissue can account for the flexion contracture.3
It may be necessary to elevate and release the patellar tendon from the tibia or even reposition the tibial tubercle.7As the patellar tendon can also shorten secondary to the fibrosis and quadriceps atrophy, lengthening of the tendon may be required, as in this example. We prefer to “pie-crust” the tendon, making many small transverse incisions along its length. This results in fractional lengthening of the tendon without disrupting the extensor mechanism.
Expected Outcomes
If diagnosed and treated early – depending upon the severity – a successful outcome can be
obtained. However, if the condition is not cor- rected, degenerative changes may occur in the patellofemoral articulating surface secondary to the abnormal joint loading. At this point in time, only a salvage procedure will be possible.2,7The prognosis does appear to depend on the etiol- ogy, as patients who develop arthrofibrosis sec- ondary to ligament injuries have had better outcomes;1however, this is also likely a function of the population of younger, more athletic patients with ligamentous injuries.
In more severe cases, surgical treatment is required. Clinical outcome studies have indi- cated that debridement and soft tissue release can provide significant improvements in range of motion.2,4,5 However, in one series of eight patients with arthrofibrosis, only one was able to return to his previous level of sports.2 Additional risk factors identified included mul- tiple ligament injuries, acute (within 1 month of injury) reconstruction, and septic arthritis.2In a series of 28 patients with IPCS, Paulos found that open debridement and soft tissue release provided an average extension increase of 12 degrees and a flexion increase of 35 degrees.
However, even with these improvements in range of motion, 90% of the patients still had symptoms of patellofemoral arthrosis and 30%
had crepitation. No athletes returned to their previous level of sports, nor were any manual laborers able to return to their previous level of employment.4
Avoiding Arthrofibrosis
The key to avoiding severe arthrofibrosis is prevention and early detection. Severe steps can be taken to prevent the development of arthrofibrosis following arthroscopic or liga- ment surgery. One critical factor is the timing of the surgery. By waiting several weeks, the effusion is reduced and the patient may receive physical therapy to improve range of motion, thereby decreasing the risk of arthrofibrosis.
The postoperative period is critical as well, and prolonged immobilization should be avoided wherever possible. The peripatellar soft tissues should be mobilized as soon as possible following surgery and range of motion exercises should be started early for the tibiofemoral joint. It is also beneficial to start active quadriceps contractions within three days of surgery. Obtaining early lateral radiographs can also be helpful for the early detection of patella infera.7
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Warning signs for the presence of arthrofi- brosis and the development of early patella infera can include the inability to voluntarily contract the quadriceps 1 to 3 weeks following surgery, decreased medial-lateral and superior- inferior patellar mobility, a decrease in the pal- pable tension in the patellar tendon, failure of the patella to elevate with quadriceps contrac- tion, and a distal malposition of the patella com- pared to the other side. Tenderness and warmth around the fat pad and peripatellar tissues can also suggest inflammation and early arthrofi- brosis.
Conclusion
Arthrofibrosis includes a wide spectrum of pathologies that can result in loss of motion of varying degrees secondary to inflammation and scarring. Prevention and early detection of arthrofibrosis remains the key to successful clin- ical outcomes. In situations involving prolonged immobilization or severe inflammation, such as the case presented here, surgical intervention is required. Open debridement and release and
tendon lengthening can be performed in order to restore range of motion.
References
1. Cosgarea, AJ, KE DeHaven, and JE Lovelock. The surgi- cal treatment of arthrofibrosis of the Knee. Am J Sports Med 1994; 22: 184–191.
2. Millet, PJ, RJ Williams, and TL Wickiewicz. Open debridement and soft tissue release as a salvage proce- dure for the severely arthrofibrotic knee. Am J Sports Med 1999; 27: 552–561.
3. Paulos, LE, and JL Pinkowski. Patella infera: The Patellofemoral Joint. In Fox, JM, and W Del Pizzo, eds.
New York: McGraw Hill, 1993.
4. Paulos, LE, TD Rosenberg, J Drawbert et al.
Infrapatellar contracture syndrome: A recognized cause of knee stiffness with patella entrapment and patella infera. Am J Sports Med 1987; 15: 331–341.
5. Shelbourne, KD, DV Patel, and DJ Martini.
Classification and management of arthrofibrosis of the knee after anterior cruciate ligament reconstruction.
Am J Sports Med 1996; 24: 857–862.
6. Sprague, NF III, RL O’Connor, and JM Fox.
Arthroscopic treatment of postoperative knee fibroarthrosis. Clin Orthop 1982; 166: 165–172.
7. Wojtys, EM, B Oakes, TN Lindenfeld, and BR Bach.
Patella infera syndrome: An analysis of the patellar ten- don pathology. Instr Course Lect 1997; 46: 241–250.
