Congenital dislocation of the patella

Purpose Congenital dislocation of the patella is permanent and manually irreducible, and it manifests immediately after birth with flexion contracture of the knee, genu valgus, external tibial torsion and foot deformity. We retrospectively reviewed the results of operative treatment of seven knees in six patients with congenital dislocation of the patella. Methods The age of the six patients at diagnosis ranged from 8 days to 3.6 years, with an average of 1.3 years, and their age at the time of operation ranged from 0.6 to 3.9 years, with an average of 2.1 years. Serial casting and/or a brace was attempted before surgery in five of seven knees, leading to improvement in the flexion contracture of the knee. All knees were treated operatively in combination with lateral release, medial plication, V-Y lengthening of the quadriceps, medial transfer of the lateral patellar tendon and posterior release of the knee. Results Although these deformities were noticed at birth in all seven knees, diagnosis was delayed in three knees due to the low suspicion of the disease and invisible patellae on radiographs. Ultrasonography confirmed the diagnosis of dislocation. The patella was centered in the groove of the femoral condyle after surgery in all knees, but subluxation of the knee with flexion was observed in one knee in which the operation was performed at 3.9 years. Genu valgus and external tibial torsion improved after surgery in all knees. The operated knee was mobile in all cases, with less than 10° flexion contracture of the knee. Flexion contracture did not increase in any of the knees. Conclusion Congenital dislocation of the patella should be suspected in every patient with knee flexion contracture, genu valgus, external tibial torsion, foot deformity and delayed walking. Successful results were obtained when the operation was performed in younger children. Other procedures, such as the semitendinosus tenodesis or tendon transfer, might have to be combined to achieve better stability with flexion in older children. None of the authors received financial support for this study.     

Patella dislocation

The patella dislocation is defined as a non-recurring or recurrent dislocation of the patella from the patella surface of the femur. In general the patella dislocates in the lateral direction. Patella dislocations are subdivided in congenital, habitual or traumatic dislocations. Furthermore patella dislocations are differentiated in recurrent and chronic dislocations. Etiology of patella dislocations is not consistent and can be due to genu valgum, patella dysplasia or patella alta etc. Frequently the patella reposes spontaneously after dislocation. Besides examination of the knee, x-ray and magnetic resonance tomography belong to clinical diagnostics of the knee joint. Decision between conservative and operative therapy is addicted to accompanying injuries like fractures or ligamental injuries.     

Patellaluxation

The patella dislocation is defined as a non-recurring or recurrent dislocation of the patella from the patella surface of the femur. In general the patella dislocates in the lateral direction. Patella dislocations are subdivided in congenital, habitual or traumatic dislocations. Furthermore patella dislocations are differentiated in recurrent and chronic dislocations. Etiology of patella dislocations is not consistent and can be due to genu valgum, patella dysplasia or patella alta etc. Frequently the patella reposes spontaneously after dislocation. Besides examination of the knee, x-ray and magnetic resonance tomography belong to clinical diagnostics of the knee joint. Decision between conservative and operative therapy is addicted to accompanying injuries like fractures or ligamental injuries.     

Diagnostic imaging of the knee in children with arthrogryposis and knee extension or hyperextension contracture

PURPOSE: Amyoplasia (type 1), characterized by quadrimelic limb involvement, is one of the most common types of arthrogryposis. In children with hyperextension or extension contracture of the knee, subluxation or dislocation of the knee joint with an associated subluxation or dislocation of the patella is frequently seen. Patellar malpositioning may be secondary to congenital hypoplasia of the patellar groove of the femur and/or dysplasia of the patellofemoral joint. A contracted quadriceps tendon and illiotibial band, as seen in extension contractures of the knee in arthrogryposis, may also contribute to patella alta and lateral subluxation of the patella. The aim of our study is to determine the position of the patella in children with quadrimelic arthrogryposis and knee extension contracture. METHODS: The inclusion criteria for this study were as follows: patients diagnosed with arthrogryposis multiplex congenita group 1, a knee extension contracture present from birth, follow-up from birth or early childhood, at least yearly physical examinations, and a knee ultrasonography or magnetic resonance imaging study performed. Patellar position was determined, and the cartilaginous femoral sulcus angle, as well as the osseous femoral sulcus angle, was measured. RESULTS: Clinically, none of patella in any of the patients could be palpated before surgery. The patella was displaced superiorly and laterally in 16/16 knees as seen on ultrasonography. Magnetic resonance imaging also showed the patella to be displaced superior and laterally. CONCLUSIONS: All patients in our series with extension contracture of the knee and type 1 arthrogryposis had a patella that was superior and lateral to the patellar groove. We found that quadricepsplasty and relocation of the patella improved knee flexion. All patients regained active knee extension in 6 months postsurgery. LEVEL OF EVIDENCE: Level III-diagnostic.     

Congenital dislocation of the patella. Part II: orthopaedic management

Five patients (eight knees) with diagnosed congenital dislocation of the patella and well-documented charts were reviewed. Age at diagnosis ranged from 4 days to 6 years. A flexion contracture of the knee and femorotibial rotatory dislocation of varying degrees were present in all the cases. The quadriceps was active in all the cases, producing knee flexion in four cases. Foot deformity was associated in all the cases (clubfoot, calcaneovalgus, or congenital vertical talus). Gradual correction of knee flexion contracture with serial casting was attempted in five cases leading to an almost complete extension in two cases. Treatment of patellar dislocation was surgical in all the cases, consisting in extensive quadriceps release (seven knees) or V-Y lengthening (one knee), division of lateral soft tissues, and reefing of the medial retinaculum and capsule. Intraoperative anomalies were recorded. At an average follow-up of 6.9 years, all the patients are able to walk on their operated limb, and the patella is centered in the trochlea in all the cases. Knee mobility, rotatory dislocation, and daily function were improved in seven cases.     

Congenital dislocation of the patella

Congenital dislocation of the patella may occur as a persistent lateral dislocation of the patella that presents with a knee flexion contracture and the patella tethered lateral to the femoral condyles or as an intermittent dislocation of the patella. In the latter syndrome, the patella dislocates completely with each flexion and extension cycle of the knee and is best termed obligatory dislocation of the patella, because the patient has no control over the patella dislocating as he or she moves the knee. The first type of congenital dislocation, which is fixed, often is associated with syndromes such as arthrogryposis and should be corrected surgically by lateral release and realignment of the patella. Obligatory dislocation of the patella tends to be an isolated dysplastic anomaly and may be relatively well tolerated. Rebalancing of the patella usually is done at a later age because of less interference with function. The current author describes the natural history of patella femoral dysplasia, detailing the pathologic changes that are present, and recommends surgical techniques for correcting both types of congenital dislocation of the patella.     

Surgical treatment of congenital dislocation of the patella

Eleven patients with 17 involved knees were surgically treated for congenital dislocation of the patella between 1978 and 1993. Ten patients with 13 involved knees followed up for a minimum of 2 years postoperatively composed the study group. Six patients had both involved knees operatively treated. In four patients, congenital dislocation of the patella was associated with a recognizable syndrome. All patients had fixed, painful lateral dislocation of the patella that could not be reduced. The average age at presentation was 7 years and 9 months (range, 2 months to 15 years). All patients underwent an extensive procedure including lateral release and advancement of the vastus medialis obliquus. Skeletally immature children underwent medial transfer of the entire patellar tendon. Skeletally mature patients underwent medial transfer of the tibial tubercle. Ten patients with 13 involved knees were followed up for > or = 2 years. Mean follow-up was 5.1 years (range, 1-17.5). At last follow-up, all patients reported a marked increase in activity tolerance and relief of pain. Average extension lag improved from 15 degrees before to 2 degrees after surgery. One superficial wound infection occurred; no patient developed a deep infection. One peroneal neurapraxia occurred but resolved with observation. Redislocation of the patella occurred in the immediate postoperative period in one patient. Operative treatment of congenital dislocation of the patella can predictably improve knee function when all aspects of the complex pathologic anatomy are addressed.     

Surgical management of congenital and habitual dislocation of the patella

Twelve patients with congenital dislocation of the patella (CDP) and 23 patients with habitual dislocation of the patella (HDP) were followed for 2-15 years after surgical stabilization of the patella. The underlying pathology in both conditions was contracture of the quadriceps mechanism, which was more severe in CDP. Surgical stabilization in most cases included an extensive lateral release, medial plication, and transfer of the lateral half of the patella tendon. Lengthening of the rectus femoris tendon was required in many cases. With appropriate operative procedures, satisfactory results were achieved in 36 of the 41 knees (87.8%).     

Anterior opening wedge osteotomy of the proximal tibia for anterior knee pain in idiopathic hyperextension knees

We analysed 20 patients with 24 knees affected by idiopathic genu recurvatum who were treated with an anterior opening wedge osteotomy of the proximal tibia because of anterior knee pain. We managed to attain full satisfaction in 83% of the patients with a mean follow-up of 7.4 years. The mean Hospital for Special Surgery score was 90.3 (range 70.5-99.5), and the mean Knee Society score score was 94.6 (70-100) for function and 87.7 (47-100) for pain. The mean Western Ontario and McMaster University Osteoarthritis Index score for knee function was 87.5 (42-100), for stiffness 82.8 (25-100) and for pain 87.3 (55-100). Radiographs showed a significant increase in posterior tibial slope of 9.4 deg and a significant decrease of patellar height according to the Blackburne-Peel method of 0.16 postoperatively. No cases of non-union, deep infection or compartment syndrome were seen. No osteoarthritic changes in the lateral or medial knee compartment were found with more than 5 years' follow-up in 16 patients with 19 affected knees. Three out of the four dissatisfied patients had a patella infera which led to patellofemoral complaints. One patient in the study underwent a secondary superior displacement of the patella with excellent results. We conclude that in a selected group of patients with idiopathic genu recurvatum and anterior knee pain an opening wedge osteotomy of the proximal tibia can be beneficial.     

Vastus lateralis fibrosis in habitual patella dislocation: an MRI study in 28 patients

We studied 28 patients with habitual or recurrent dislocation of the patella with MRI of both thighs. Apart from the 2 patients whose dislocation could be related to trauma, we found signs of fibrosis of the vastus lateralis muscle in all the affected limbs of the 26 patients with an insidious onset of dislocation. This was seen as low signal intensity cords in the muscles in the T2 weighted image. Muscle degeneration was seen as high intensity signals in the T1 weighted image. In patients with unilateral disease, the vastus lateralis muscle of the affected side was hypotrophic, compared to that of the normal side. 2 patients underwent a biopsy of the affected muscle area. Histopathological examination revealed inflammatory cell infiltration, fibrosis, and muscle fiber degeneration. Fibrosis of the vastus lateralis muscle appears to be common in patients with habitual patella dislocation in our population, and may be the cause of the dislocation. Since release of such a contracture may be of value, MRI study of the thigh muscles is helpful in the evaluation of patients with this disorder.     

Vastus lateralis fibrosis in habitual patella dislocation: An MRI study in 28 patients

We studied 28 patients with habitual or recurrent dislocation of the patella with MRI of both thighs. Apart from the 2 patients whose dislocation could be related to trauma, we found signs of fibrosis of the vastus lateralis muscle in all the affected limbs of the 26 patients with an insidious onset of dislocation. This was seen as low signal intensity cords in the muscles in the T2 weighted image. Muscle degeneration was seen as high intensity signals in the T1 weighted image. In patients with unilateral disease, the vastus lateralis muscle of the affected side was hypotrophic, compared to that of the normal side. 2 patients underwent a biopsy of the affected muscle area. Histopathological examination revealed inflammatory cell infiltration, fibrosis, and muscle fiber degeneration. Fibrosis of the vastus lateralis muscle appears to be common in patients with habitual patella dislocation in our population, and may be the cause of the dislocation. Since release of such a contracture may be of value, MRI study of the thigh muscles is helpful in the evaluation of patients with this disorder.     

Vastus lateralis fibrosis in habitual patella dislocation: An MRI study in 28 patients

We studied 28 patients with habitual or recurrent dislocation of the patella with MRI of both thighs. Apart from the 2 patients whose dislocation could be related to trauma, we found signs of fibrosis of the vastus lateralis muscle in all the affected limbs of the 26 patients with an insidious onset of dislocation. This was seen as low signal intensity cords in the muscles in the T2 weighted image. Muscle degeneration was seen as high intensity signals in the T1 weighted image. In patients with unilateral disease, the vastus lateralis muscle of the affected side was hypotrophic, compared to that of the normal side. 2 patients underwent a biopsy of the affected muscle area. Histopathological examination revealed inflammatory cell infiltration, fibrosis, and muscle fiber degeneration. Fibrosis of the vastus lateralis muscle appears to be common in patients with habitual patella dislocation in our population, and may be the cause of the dislocation. Since release of such a contracture may be of value, MRI study of the thigh muscles is helpful in the evaluation of patients with this disorder.     

Patellofemoral disorders and instability

Originally the main idea was to obtain a stable patella, i.e., to stabilize the "slipping patella". In the past many conditions like patella alta, ligamentous laxity, PF bone hypoplasia, weakness of the quadriceps muscle, genu valgum or genu recurvatum were thought to predispose to patellar instability. For a long period muscle exercises were instituted to strengthen the weak m.vastus medialis and to make vastus lateralis stronger. This pulls the patella laterally, especially during running or jumping, when lateral luxation of the patella occurs. Muscle imbalance as well as anatomical abnormalities are the basis both for patellar instabilities and reasonable surgical procedures were: proximal extensor mechanism realignment, proximal capsular reefing, patellar tendon splitting and its medial transfer. On the other hand bone procedures on the hypoplastic lateral femoral condyle were also performed by Albee, as well as tibial tubercle transfer and trochleoplasty by deepening of the trochlea (Dejour). An understanding of the pathoanatomic basis is the corner stone for     

Long-term outcome of surgically-treated habitual patellar dislocation in children with coexistent patella alta. Minimum follow-up of 11 years

We retrospectively reviewed the operative treatment carried out between 1988 and 1994 of eight patients with habitual patellar dislocation. In four the condition was bilateral. All patients had recurrent dislocation with severe functional disability. The surgical technique involved distal advancement of the patella by complete mobilisation of the patellar tendon, lateral release and advancement of vastus medialis obliquus. The long-term results were assessed radiologically, clinically and functionally using the Lysholm knee score, by an independent observer. The mean age at operation was 10.3 years (7 to 14) with a mean follow-up of 13.5 years (11 to 16). One patient required revision. At the latest follow-up, all patellae were stable and knees functional with a mean Lysholm knee score of 98 points (95 to 100). In those aged younger than ten years at operation there was a statistically significant improvement in the sulcus angle at the latest follow-up (Student's t-test, p = 0.001). Two patients developed asymptomatic patella infera as a late complication. This technique offers a satisfactory treatment for the immature patient presenting with habitual patellar dislocation associated with patella alta. If performed early, we believe that remodelling of the shallow trochlea may occur, adding intrinsic patellofemoral stability.     

Surgical treatment of habitual patella dislocation with genu valgum

Habitual dislocation of patella is a rare disorder. Sometimes it is associated with angular deformity such as genu valgum. We experienced habitual patella dislocation associated with genu valgum that was treated with corrective osteotomy of distal femur and soft tissue realignment procedure including lateral release and medial reefing.     

髌腱内移和髌内侧筋膜肌肉瓣外移治疗先天性髌骨脱位

目的评价髌腱内移和髌内侧筋膜肌肉瓣外移术治疗先天性髌骨脱位的效果。方法自1994年6月～1998年6月,采用髌腱内移和内侧筋膜肌肉瓣外移的方法治疗先天性髌骨脱位5例,男2例,女3例,平均年龄7岁(4～10岁)。4例为单侧髌骨脱位,1例为双侧(只治疗一侧),均未合并其它畸形。结果术后随访1.5～5年,平均3年,无手术并发症,无术后再脱位和半脱位。4例膝关节能完全伸直,1例差10°;2例膝外翻消失;1例10岁女童术后出现髌骨低位,但膝外翻消失、功能正常且伸膝有力。结论先天性髌骨脱位是一种持续、不可复性脱位,需手术治疗。髌内侧筋膜肌肉瓣外移和髌腱内移术操作简单,损伤较小,并发症少,效果优良,是一种值得推荐的手术方法。     

Late results of Hauser procedure for recurrent dislocation of the patella.

To determine whether the Hauser procedure for recurrent dislocation of the patella prevents repeated dislocation and provides a functional knee without late degenerative arthritis, 52 patients with 67 surgically treated knees were studied clinically and roentgenographically with an average follow-up of 17.1 years. Greater than 70% of patients had an excellent or good result up to as long as 30 years postoperatively. There appeared to be no predisposition to the development of degenerative arthritis. Recurrent dislocation persisted in 7% of cases and female patients with generalized ligamentous laxity had a high incidence of persistant, recurrent dislocation and poorer long-term results. Development of genu recurvatum is a definite risk in patients who have tibial tubercle transfer prior to epiphyseal plate closure.     

Ultrasound in the early diagnosis of congenital dislocation of the patella

INTRODUCTION: Congenital dislocation of the patella is defined as lateral dislocation of the patella present at birth, impossibility of closed reduction and diagnosis before the age of 10 years. We report about a rare case of a bilateral congenital dislocation of the patella. CASE REPORT: Physical examination of an eight-month- old boy showed bilateral knee flexion contractures associated with moderate genu varum. On both sides the patella could not be palpated easily. Radiographic diagnosis could not show the patella as the patella normally ossifies later. Ultrasound examination located the patella lateral to the lateral femoral condyle on both sides. Closed reduction was impossible. An open reduction with division of the lateral soft tissues, lateral release, and derotation of the quadriceps femoris and refining of the medial structures was performed. After cast removal the patellae were both located in the intercondylar grooves as confirmed by clinical and ultrasound examinations of both knees. Active and passive exercises were started. CONCLUSION: Failure of internal rotation of the myotome which contains the quadriceps femoris and the patella is the etiology of congenital dislocation of the patella. The quadriceps acts as flexor, exerting a valgus stress on the knee, causing external rotation of the tibia. Diagnosis is often delayed because of the lack of pathological findings on plain radiographs. Early diagnosis is enabled by ultrasonography. Surgical treatment is necessary and results are good, as long as there are no secondary changes.     

Acquired permanent dislocation of the patella in a patient with rheumatoid genu valgum

A case of acquired permanent dislocation of the patella associated with severe genu valgum in a patient with rheumatoid arthritis (RA) is herein reported. The pain and genu valgum progressed because of poor RA control. The patient had no history of major trauma of the knee before or after the onset of RA. The most reasonable hypothesis to explain this patient''s pathology is that occult patellar dislocation developed after a minor trauma and progressed to permanent dislocation; poor RA control then worsened both the patellar dislocation and genu valgum. Total knee arthroplasty (TKA) with patella reduction was successfully performed with release of the lateral retinaculum and extension of the extensor mechanism by partial snipping of the rectus femoris tendon. Two years after the operation, the patient exhibited improvement in her Knee Society Knee and Function Scores from preoperative scores of 18 and 20 to postoperative scores of 94 and 80, respectively. Acquired permanent dislocation of the patella associated with severe genu valgum in patients with RA is rare. Excellent results were obtained with TKA, and the proximal realignment method was a useful procedure for patella reduction.     

Congenital dislocation of the patella and its operative treatment.

Twelve patients with 18 knees whose congenital permanent lateral dislocation of the patella was irreducible by nonoperative means are reported. All knees were operated on according to the same principles, including medial transfer of the patellar tendon. The age of the patients at operation varied between 3 and 19 years. The average follow-up time was greater than 13 years. All patients benefited greatly from the operation. Active knee extension ability was restored in all knees. Some extension deficit remained in two severely dysplastic patients. Congenital subluxation with habitual dislocation of the patella has been successfully treated by the method described.