12.1 Definition of terms particular to thesubject of internal fixation of femoralneck fractures APPENDIX Chapter 12

APPENDIX

12.1 Definition of terms particular to the subject of internal fixation of femoral neck fractures

Classification of hip fractures 1. Intracapsular (medial)

(a) Subcapital neck fractures

(b) Transcervical neck fractures (the distinc- tion is of little clinical significance)

2. Extracapsular

(a) Lateral neck fracture (part of the neck re- mains attached to the caudal fragment. If this part lies in the region of Adam’s arch, the screw can still find support on the 2nd buttressing point. An angle-stable implant is therefore not necessary. Exceptionally, this fracture can run partly intracapsular (due to a variation of the course of the capsule); consequently, immediate surgery is recommended).

(b) Base of neck fracture (part of the neck does not remain attached to the caudal frag- ment. The trochanteric area, however, re- mains intact. Use of an angle-stable DCD plate is always recommended)

(c) Trochanteric (per-intertrochanteric) fracture

(d) Subtrochanteric fracture Undisplaced femoral neck fractures

Overall term for Garden-I and -II fractures. Previ- ously, the Garden-I fracture was known as impacted valgus or abduction fracture of the femoral neck.

Displaced femoral neck fracture

Overall terms for Garden-III and -IV fractures.

Previously, they were known as varus or adduction fractures.

Garden alignment angle, measured in the a.-p. pro- jection

Normally, a line along the medial cortex of the fe- moral shaft and a line going through the center of

the compression trabeculae of the femoral head form an angle of 160º (see Fig. 69a).

If the angle is greater than 160º, we speak of val- gus position. If it exceeds 190º, the term hypervalgus is used and if it is below 160º, it is termed varus position.

A valgus position between 160 and 180º is ac- ceptable. In respect to stability it is even desirable.

An increased risk of avascular necrosis exists in instances of hypervalgus. If the angle is less than 150º, the danger of loss of reduction is higher. In both cases a reduction is mandatory.

Garden alignment angle, as measured in the lateral projection

This is defined as an angle formed by a line going through the center of the femoral neck and by a line going through the center of the compression trabec- ulae of the femoral head; it amounts normally to 180º (see Fig. 69b). If the Garden alignment angle is smaller than 180º in the lateral projection (open pos- teriorly, the apex pointing anteriorly), we speak of antecurvature. If the angle exceeds 180º, (open an- teriorly, the apex pointing posteriorly) we are deal- ing with a recurvatum.

Still acceptable is an angle between 180 and 160º. A fracture having an antecurvature of < 160º has a tendency for loss of reduction. A recurvatum

> 190º carries the increased risk of avascular necro- sis. In both instances a reduction is mandatory.

Garden alignment index

Anatomically, the ratio of the a.-p. Garden angle over the lateral Garden angle amounts to 160/180º.

Acknowledging an acceptable margin of error of 5º this index is the most precise parameter of displace- ment of a femoral neck fracture or of the quality of reduction in both planes.

Adam’s arch

In the a.-p. projection this bony structure is seen as

a cortical thickening at the medial side of the

femoral neck.

Calcar femorale

A cortical thickening in the posterior half of the proximal femur extending through the cancellous bone. The calcar femorale together with Adam’s arch forms a U-shaped gutter in the caudal part of the neck extending to the femoral head. The calcar femorale is a continuation of the posterior cortex of the femoral diaphysis. Appositional growth of the lesser trochanter during organogenesis leads to its migration to the center of the neck.

A reduction is needed when on a.-p. radiograph the following signs are seen (see Sect. 7.6)

Varus: < 150º Valgus: > 190º

Too strong (causing a caudal translational – ad latus – displacement) or inadequate traction on the limb (causing a cranial translational displace- ment) is defined

– by the translational displacement exceeding one cortical width;

– by the width of a fracture gap inferiorly – rarely superiorly – exceeding 3 mm (in general, a smaller gapping corrects itself spontaneously during the postoperative phase. To obtain, how- ever, a good early metaphyseal drainage it is ad- visable to use the adapter during the operation to reduce or eliminate any gapping).

Diastasis involving the entire fracture line: an im- mediate correction using the adapter is absolutely necessary.

A reduction is needed when on a lateral radiograph the following signs are seen (see Sect. 7.6)

Antecurvature: < 160º Recurvatum: > 190º

Too strong or inadequate rotation (exaggerated or insufficient internal rotation of the limb around the longitudinal axis of the femur) is defined by a posterior step (too strong) or by an anterior step (in- sufficient rotation) exceeding a quarter of the width of the femoral neck.

Anterior positioning of insertion of the first cannu- lated screw

An optimal position for the start of drilling should produce a placement of the first caudal screw 3 mm anterior to the midline of the neck. At this site the

gutter formed by Adam’s arch and calcar femorale is situated, it forms the site of the second buttressing point. Its course is well seen in bony, cross sections of human specimens and in sagittal serial CT cuts.

In this way the caudal, more important first screw is optimally secured in the gutter. If we start drilling in the midline of the neck, we injure the calcar femorale, the posterior wall of the gutter.

As described in Sect. 5.7 the first step of drill bit placement is the insertion of the two-hole drill guide with its attached handle into the soft tissue sleeve also having a handle. A short Kirschner wire is driven through the center hole of the drill guide to prevent its slipping from the midline. Imaging in the lateral projection must confirm the wire’s place- ment in the center of the neck. 3 mm anterior to the guide wire hole is the hole for the 3.2 mm spiral drill bit. If the handle of the two-hole drill guide points strictly posterior, a drilling 3 mm anterior to the midline of the neck is assured and the 3.2 mm drill bit cannot slip on the convex cortex. Thanks to the use of the two-hole drill guide the position of the caudal screw in the center of the gutter is guaran- teed (anterior positioning) (see Fig. 164).

Assessment of internal fixation (see Sect. 8.4)

Adaptation and settling (sliding)

Even after a perfect reduction the surfaces of a dis- placed fracture do not fit exactly. In the majority of patients a spontaneous fitting of the surfaces is taking place already during the postoperative re- turn of the muscle tone and also later at the be- ginning of mobilization and during consolidation.

We term this fitting adaptation. In the course of this process the femoral neck shortens usually due to an impaction. A slight varus displacement is also possible. A lateral measurable protrusion of the screw end accompanies this process (settling, slid- ing). The position of the screw’s tip in the femoral head is not affected by this process.

We attempt already intraoperatively to reduce or eliminate a possible gapping (diastasis) as seen on the monitor. Careful use of the adapter helps to achieve an adaptation of the fracture surfaces. Its use is always recommended, when a gap is seen dur- ing surgery; it is obligatory, when the gap is wide.

280 Chapter 12: Appendix

A certain degree of settling is already discernible on radiographs taken after postoperative mobiliza- tion. Small gaps, usually associated with intraopera- tive exaggerated distraction or defects at the fracture surfaces, have disappeared and the slight rotation is corrected.

In the majority of patients a further backing-out of the screw end is evident on radiographs taken after four months. The cause of this settling during consolidation is a further impaction and also a re- sorption of small fragments and the fracture sur- faces, all explaining the shortening of the femoral neck.

Degree of settling

Small degree of settling (< 1 cm), usually fa- vorable as it increases the stability.

Moderate settling (1–1.5 cm), the fracture most often consolidates

Considerable settling (> 1.5 cm), in the ab- sence of an axial malalignment indicates a serious circulatory disturbance. If accompanied by a varus alignment, it is usually a sign of an imminent loss of reduction. Only in exceptional cases the fracture may consolidate.

In instances of a marked settling, radiographic controls at shorter intervals are recommended and a prolongation of partial weight bearing may be necessary.

Summary of methods for enhanced fixation of the femoral neck fracture

(Figs. 241 and 242)

The phases of uneventful consolidation of femoral neck fractures

Consolidation – end of the 4th month: the patient is symptom-free, radiographs show the be- ginning of healing and remodeling and no signs of imminent complications are present such as loss of reduction, femoral head perforation and gaping.

Remodeling – end of year 1: the patient is symptom-free, in general the fracture gap has dis- appeared, no radiographic evidence of complications such as non-union, necrosis etc.

Healed fracture – end of year 3: the patient is symptom-free, the fracture cannot be recognized anymore, contour and cancellous bone structure of

the femoral head are normal, no evidence of necrosis (uncomplicated healing).

Disturbances of healing in femoral neck fractures Loss of reduction: occurring up to the end of the 3rd month (sometimes 6th month), displaced fracture, need for revision surgery. No necrosis!

Delayed union: three to six month after injury:

no or inadequate callus formation on radiographs.

No signs of complications such as loss of reduction, femoral head perforation, gaping are present. If the patient complains about pain, follow-up examina- tions at shorter intervals are recommended.

Non-union: even after six months no evidence of consolidation of the fracture visible. It may happen that an apparently consolidated fracture displaces without adequate trauma. A cortication of the cra- nial fracture surface is present. It is an evidence of femoral head vitality (L. Böhler, 1996) (see Fig. 120).

Migrating non-union: Simultaneous occurrence of total head necrosis and non-union. Remodeling of the fracture only from the caudal fragment. Cranially, the necrotic trabeculae undergo a gradual fragmen- tation. Consequently the fracture line “migrates” cra- nially by 0.5 to 1 cm. Radiographs show the charac- teristic, homogenous radiodensity (Böhler, 1996).

Femoral head necrosis: occurring more than one year after injury: usually progressive changes of the femoral head taking place after remodeling of the fracture. In displaced femoral neck fractures certain vascular disturbances occur almost always;

their prognosis depends on many factors such as anatomic vessel variants, degree of initial displace- ment, length of interval between injury and reduc- tion, quality of reduction and/or internal fixation.

Assessment of femoral head necrosis, stages

The first classification of femoral head necrosis was published by Arlet and Ficat (1968). Today, the following modified and internationally recognized classification is used (Arnoldi, 1994; Mont and Hungerford, 1995). Both classifications are based on the aseptic, atraumatic avascular necrosis, they can, however, also be applied to the posttraumatic femoral neck necrosis.

Stage 0: absence of clinical symptoms, no patho-

logic changes on standard radiographs taken in two

planes. Earliest evidence of vascular disturbances

282 Chapter 12: Appendix

a b c

d e f

h i j

g

k l m

Fig. 241. Series of methods for enhanced fixation of the femoral neck fractures.

a. 2 mm two-hole plate, standard, for the fixation of the caudal cannulated screw;

b. 2 mm three-hole plate, for the fixation of both cannulated screws;

c. 4.5 mm three-hole plate, for enhanced fixation of the caudal cannulated screw;

d. 4.5 mm four-hole plate, for enhanced fixation of both cannulated screws;

e. Four-hole cam-plate, for limited angle-stable fixation of the caudal cannulated screw;

f. Six-hole cam-plate, for limited angle-stable fixation of both cannulated screws;

g. 2 mm five-hole plate (left and right side) for the fixation of three cannulated screws (with the new parallel guide, see Fig. 163);

h. Simple

(Dynamic Collo-Diaphyseal) plate, angle-retaining fixation of the caudal cannulated screw (missing Adam’s arch);

i.

plate and satellite plate, angle-retaining fixation of the caudal cannulated screw (missing Adam’s arch) and fixation of the cranial cannulated screw (against rotational instability);

j. Double angle-stable

plate, angle-retaining fixation of both cannulated screws (comminuted fracture);

k. Flanged screw, plate inserted in the caudal cannulated (longitudinal splitted) screw (against rotational instability);

l. Flange and the same inserted in the screw;

m. Two cannulated screws connected by one flange, increases the stability of the cranial screw (see also Fig. 168)

can be detected by MRI and later by SPECT or DS-intraosseous venography. Vascular disturbances diagnosed by special imaging techniques do not always lead to demonstrable structural signs of necrosis.

Stage 1: Slight symptoms may be present, but the contour of the femoral head is preserved. Plain radiographs taken in two planes show an early, sub- chondral diminished transparency, a zone of “scle- rosis” at the zone of weight bearing of the femoral head. Later on, in the presence of partial necrosis radiodense and atrophic spots may appear and occasionally cystic changes.

Stage 2: Increasing symptoms. The sphericity of the femoral head is lost due to a flattening at the weight bearing surface. The continuity of the bony structure is however preserved. During stage 1 and 2 a core decompression procedure is indicated.

Stage 3: Collapse of the weight bearing surface.

In older patient (> 60 years) a symptomatic femoral head necrosis after neck fractures necessitates an arthroplasty. In younger patients result of the CT is decisive: If the sum of the a.-p. and lateral angles of necrosis does not exceed 200º, a rotational osteo- tomy may be attempted to transfer the collapsed segment out of the weight bearing area (Salacz et al, 1993). The type of osteotomy is determined with the help of radiographic films. After consolidation of the osteotomy a revascularization of the femoral head with a pedicled bone transplant can be attempted.

In selective, early diagnosed cases we may obtain a remodeling of the femoral head on the condition that we support carefully the collapsed segment with auto- genous cancellous bone during the revascularization procedure.

Stage 4: Pronounced deformation of the femoral

head followed by subluxation and coxofemoral osteo- arthritis. In the presence of symptoms an arthro- plasty is indicated (in younger patients perhaps an arthrodesis).

Core decompression

Decompression of the femoral head: with a 5 mm hollow drill bit we remove a bony cylinder from femoral neck and head. We perforate the sclerotic border around the zone of necrosis where the in- traosseous pressure is elevated due to congestion.

The congested blood in the endangered zone can drain through the drill channel. Thus the intra- osseous pressure in this zone can be reduced or eliminated decreasing the risk of progression of

necrosis. Under favorable circumstances a necrosis of limited extent can heal and the patient becomes symptom-free (Hungerford and Lennox, 1985).

Revascularization procedure

If an extensive necrosis in patient under 50 years causes pronounced symptoms, a pedicled bone graft can be transplanted under the weight bearing sur- face.

Optimal treatment

A proper reduction, a stable internal fixation and a state of art rehabilitation are defined as an optimal treatment (Thorngren, 1991a).

284 Chapter 12: Appendix

12.2 Members in charge of the research team “Femoral Neck Fractures” at the National Institute of Traumatology (Budapest)

Manninger Jen˝o 1953–

Szabó László

1953–1964

Borók László

1953–1958

Kazár György

1957–2002

Nagy Ern˝o

1962–1985

Zolczer László

1964–1985

Salacz Tamás 1968–

Fekete Károly 1988–2003

Cserháti Péter 1990–

Szita János 2003–

Laszkó Tibor 1991–

Melly András 1986–

Kádas István 1987–

Flóris István 1995–

Baktai József 1995–

12.3 Foreign teachers, councilors and supporters

Aichner H. A

Allgöwer M. Ch

Beck E. A

Bonnaire F. D

Boyd H. L. USA

Böhler J. ^† A

Böhler L. ^† A

Ehalt W. A

Hungerford D. S. USA

Kaplan M. RUS

Kinzl L. D

Kuderna H. A

Kuner E. H. D

Müller M. E. CH

Olerud S. S

Pannike A. D

Parker M. J. GB

Poigenfürst H. A

Povacz F. A

Rehnberg L. S

Rommens P. M. D

Schneider R.

CH

Schweiberer L. D

Sevitt S. GB

Stock W. D

Thorngren K-G. S

Tscherne H. D

Vécsei V. A

Willenegger H.

CH

Wingstrand H. S

In the early stages of our research team we received

the most encouraging support from Lorenz and Jörg

Böhler and from Hans Willenegger.

286 Chapter 12: Appendix

Fig. 242. Implants and instruments for enhanced fixation of the femoral neck fractures.

Implants

1. Three-hole 4.5 mm plate (Fig. 241. d) 2. Four-hole 4.5 mm plate (Fig. 241. c) 3. Four-hole cam-plate (Fig. 241. e) 4. Six-hole cam-plate (Fig. 241. f)

5–6.

plate for the fixation of the caudal cannulated screw, 140º and 130º (Fig. 192. a) 7.

satellite plate (Fig. 241. i)

8–9.

(Dynamic-Collo-Diaphyseal) cranial supplementary plate allows to double the angular stability, 140º and 130º (Fig. 192. c) Instruments

10. Crown drill bit for preparation of the barrel of

plate (Fig. 196. b) 11. Kirschner wire for fixation of the two-hole parallel drill guide (Fig. 164)

12. The two sleeves for the parallel alignment of the flattened end of the cannulated screws (Fig. 167) 13. 290 mm long 8 mm extension rod for slotted screw (Fig. 161. b/2)

14. Long screw holder (Fig. 161. b/4)

15/1. The new parallel guide for insertion of two or three cannulated screws (Fig. 163. a, b) 15/2, 3, 4. Three special sleeves for the new parallel guide

16/1.

parallel guide for 140º plates (Fig. 196. a)

16/2. Screw for fixation the wedges 19 and 20 to the

parallel guide for 140º plates

17. Two hole drill guide with handle for anterior translation of the caudal cannulated screw (Fig. 164)

18. The adapter used for the intraoperative elimination of diastasis in the fracture gap (Fig. 159)

19–20. Wedges to the

parallel guide for 120 and 130º plates