Chronic patellar dislocation in adults

Transcription

1 CASE STUDY 11 Chronic patellar dislocation in adults What are the reasons for chronic dislocation? Which is the best imaging modality for documentation? How can we treat it? Table CS11 Patellofemoral joint examination Diagnostic clues Findings Diagnostic clues Findings Pain Diffuse patellofemoral joint Patellar gliding mechanism Unstable with lateral patellar dislocation near extension and partial reposition with knee flexion Tenderness Medial and lateral Patellar apprehension Severely positive to lateral Effusion With overload Q angle Normal value Swelling With overload Catching Lateral Patellar position, relaxed, 0 Severe lateral subluxation Locking Sometimes between extension and 30 flexion Patellar position, Lateral dislocation Range of motion Decreased in flexion, painful contracted, 0 Patellar position, Lateralization, 30 subluxation and patellar tilt Patellar mobility Increased to lateral, decreased to medial Radiographs Other Dysplastic trochlea, severe patellar subluxation Weakness Patellofemoral Disorders: Diagnosis and Treatment. Edited by Roland M. Biedert 2004 John Wiley & Sons, Ltd ISBN:

2 206 CASE STUDY 11 CHRONIC PATELLAR DISLOCATION IN ADULTS History A 27 year-old female came to our clinic complaining about chronic patellofemoral pain, weakness and feelings of patellar instability. At the age of 14 years, she had had a surgical lateral release and purse-string sutures of the medial retinaculum on the left knee. She was disabled in daily life and sports activities. Comments The patient s history already revealed the problem of patellar instability with episodes of complete patellar dislocation. Complaints in both knees in young age are suggestive of severe dysplastic conditions of the patellofemoral joint. Course of action Physical examination The physical examination of this patient revealed identical findings on both sides. The patella severely subluxed to the lateral side in extension with relaxed muscles (Figure CS11.1). Contraction of the quadriceps muscle caused complete patellar dislocation. The apprehension test was severely positive laterally. On moving the knee joint passively from extension to 30 of flexion, the patella reduced medially on the femur. The apprehension test was now negative and remained negative with increased flexion. Physical examination in the standing position showed normal static situation of the feet but excessive external rotation of the proximal tibia. Accordingly, the tibial tubercle was positioned extremely laterally. Examination of the hip joint was normal. Radiographs The anteroposterior view in extension showed severe lateral subluxation of the patella. The lateral views revealed a severe dysplastic trochlea. 1 4 The axial views, performed in 30 of knee flexion, showed well-centred patellae in the trochlea Figure CS11.1 Severe lateral patella subluxation (left knee, extension, relaxed) Figure CS11.2 Well-centred patellae on both sides (radiographs, axial views, 30, relaxed) on both sides (Figure CS11.2). This documented the significant difference of the patella position between extension and 30 of flexion. Axial CT evaluation Moderate lateral dislocation of the patella is documented with axial CT scans in extension (Figure CS11.3). 5,6 Quadriceps contraction even increases the amount of dislocation

3 PLAN 207 Figure CS11.3 Moderate lateral patellar dislocation on the left side (axial view, extension, relaxed) Figure CS11.5 Partial reduction of the patella with flexion (axial view, 30, relaxed), left leg but increased external rotation of the proximal tibia of 38 on the right and 34 on the left side. 2,4,8 Special considerations Figure CS11.4 Severe lateral patellar dislocation on both sides with quadriceps contraction. Note the dysplastic trochlea (missing trochlear groove). A neo-articulation is formed between patella and lateral condyle (axial views, extension, contracted) (Figure CS11.4). The trochlea is severely dysplastic and the sulcus angle cannot be measured. 7 Partial reposition of the patella on the trochlea is noted in 30 of flexion (Figure CS11.5). Additional CT scans to analyse the alignment of the lower extremity show normal femoral antetorsion Chronic habitual patellar dislocation is a severe problem. A long history, beginning with complaints at a young age and persisting disability, documents this problem. A severe dysplastic trochlea is the underlying pathoanatomy in most of these cases and is the target of the treatment concept. Plan The goal of the treatment is to eliminate the dislocation of the patella. We must consider that a dysplastic trochlea is present, the medial soft tissue structures are overstretched, and the lateral structures are too tight. In addition, the patella is partially reduced in 30 of flexion during physical examination, when the femoral condyle moves

4 208 CASE STUDY 11 CHRONIC PATELLAR DISLOCATION IN ADULTS posteriorly on the tibia and the patella runs deeper into the trochlear groove. 9 The trochlea is dysplastic in the proximal part, but almost normal distally. These considerations determine the choice of the various surgical steps, which 8,10 13 consist of: Lengthening of the lateral retinacula, the iliotibial tract and the vastus lateralis tendon muscle unit. Trochlearplasty with raising of the lateral condyle. Medialization and distalization of the tibial tuberosity. Doubling of the medial retinaculum and the medial patellofemoral ligament. (Note: In 1999, Teitge, in a handout, endorsed these considerations and surgical steps.) The intervention starts with a parapatellar lateral incision and osteotomy of the tibial tuberosity with a bone fragment of 8 1 1cm. The pes anserinus remains attached at the tibial tuberosity. Then a lateral arthrotomy is performed, separating the lateral structures into two layers (see Case Study 3). Incomplete osteotomy of the lateral condyle is made with a curved chisel (see Case Study 6). The osteochondral flap is carefully raised 5 6 mm, using the chisel or an osteotome. Cancellous bone, which was taken at the beginning of surgery from the area of the tibial osteotomy, is put into the gap and carefully impacted (see Case Studies 6 and 18). This raises the lateral femoral condyle and forms the lateral trochlea. The bone fragment of the tibial tuberosity is moved medially and distally until the patella glides in the centre of the newly-shaped trochlea. It is important to control the position of the patella in extension and flexion. Temporary fixation of the tibial tuberosity using Kirschner wires allows precise corrections. The tibial tuberosity is finally fixed with two or three 4.0 cancellous screws (Figure CS11.6). The medial structures are Figure CS11.6 Sagittal radiographs after reconstruction shortened and doubled according to the new position of the patella and in reference to the patellar glide test. The lateral structures are reattached and lengthened in of knee flexion. A diastasis remains in most cases. At the end of this individual reconstruction, the patella was 8 mm distalized and 12 mm medialized. The risks of this technique include breaking of the osteochondral flap of the trochlea and too much distalization and medialization of the tibial tuberosity. The most difficult part is the correct balancing of the medial and lateral soft tissue structures. Postoperative care and rehabilitation Goals To keep the patella in the trochlea. To protect the healing of both osteotomies. To activate all stabilizing muscle groups and later to strengthen them.

5 REFERENCES 209 Timeline Hospital 7 days Mobilization 2nd day Weightbearing Partial 10 kg for 6 weeks Complete Depends on healing of osteotomies and quality of muscle control Sports Bicycle, After 6 weeks swimming Everything Depends on final result Figure CS11.8 Minimal lateralization of the patella under quadriceps muscle contraction (axial views, extension, contracted) Discussion The case study described represents one of the most difficult patellofemoral problems. The underlying pathoanatomy requires different surgical steps which must be adapted to each other. The correct balancing of the soft tissue structures and the amount of correction with the osteotomies need great experience. The long-term result of the present case was very positive at the Figure CS11.9 Well-centred left patella in flexion. Note the severe lateral subluxation of the right patella, even in flexion (axial views, 30, relaxed) 8 year follow-up, with correction of the left side only (Figures CS11.7, CS11.8 and CS11.9). Summary Multiple corrections and reconstructions at the same time in cases with most difficult pathologies can improve the problem but must remain in the hands of an experienced person to avoid impairment. Figure CS11.7 Well-centred patella on the left side in extension. Note the healed osteotomy of the lateral femoral condyle. The lateral trochlea is raised in comparison to the nonoperated right side (axial views, extension, relaxed) References 1. Walch G, Dejour H (1989) [Radiology in femoropatellar pathology]. Acta Orthop Belg 55:

6 210 CASE STUDY 11 CHRONIC PATELLAR DISLOCATION IN ADULTS 2. Dejour H, Walch G, Nove-Josserand L, Guier C (1994) Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc 2: Dejour H, Walch G, Neyret P, Adeleine P (1990) [Dysplasia of the femoral trochlea]. Rev Chir Orthop Reparatrice Appar Mot 76: Galland O, Walch G, Dejour H, Carret JP (1990) An anatomical and radiological study of the femoropatellar articulation. Surg Radiol Anat 12: Biedert RM, Gruhl C (1997) Axial computed tomography of the patellofemoral joint with and without quadriceps contraction. Arch Orthop Trauma Surg 116: Martinez S, Korobkin M, Fondren FB, Hedlund LW, Goldner JL (1983) Diagnosis of patellofemoral malalignment by computed tomography. J Comput Assist Tomogr 7: Delgado-Martins H (1979) A study of the position of the patella using computerised tomography. J Bone Joint Surg Br 61-B: Teitge RA, Faerber WW, Des Madryl P, Matelic TM (1996) Stress radiographs of the patellofemoral joint. J Bone Joint Surg Am 78: Müller W, Wirz D (2000) Anatomie, Biomechanik und Dynamik des Patellofemoralgelenks. In: Wirth CJ, Rudert M (eds), Das Patellofemorale Schmerzsyndrom. Darmstadt, Steinkopff-Verlag, pp Rillmann P, Dutly A, Kieser C, Berbig R (1998) Modified Elmslie Trillat procedure for instability of the patella. Knee Surg Sports Traumatol Arthrosc 6: Cash JD, Hughston JC (1988) Treatment of acute patellar dislocation. Am J Sports Med 16: Hughston JC, Walsh WM, Puddu G (1984) Patellar Subluxation and Dislocation. Saunders Monographs in Clinical Orthopaedics, volume V. Philadelphia, PA, WB Saunders 13. Albee FH (1915) The bone graft wedge in the treatment of habitual dislocation of the patella. Med Rec 88: