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PubMed1985

Patellar dislocation following total knee replacement.

The reported incidence of patellar problems after total knee replacement has ranged from 5 to 30 per cent. Patellar dislocation is infrequent but can cause disabling symptoms. Between January 1974 and May 1982, eleven patients (twelve knees) with symptomatic lateral dislocation of the patella after total knee replacement were treated at The Hospital for Special Surgery by realignment of the extensor mechanism. All of the patients were women. Their average age was sixty-two years and average weight, eighty-seven kilograms. The diagnosis was osteoarthritis in seven knees and rheumatoid arthritis in five. Most of the patients had had preoperative valgus deformity (average, 18 degrees). The cause of dislocation was trauma in three knees, incorrect tracking of the patella after replacement in six, and malrotation of the tibial component in three. Four different prosthetic designs had been used. The design of the implant did not appear to be a factor causing dislocation in this group. The patellar dislocation was treated by proximal realignment of the quadriceps in ten knees, lateral retinacular release alone in one, and revision of the tibial and femoral components combined with proximal realignment in one. After an average follow-up of thirty-four months (range, twenty-four to fifty-seven months), the results according to The Hospital for Special Surgery knee-rating scale were excellent in ten knees and good in two, and there had been no redislocations.

Arthritis, Rheumatoid↗

PubMed1978

Acute patellar dislocation: results of immediate surgical repair.

Seventeen cases of acute, first time, lateral patellar dislocations without fracture treated by immediate surgical repair were reviewed and evaluated. Nine patellar tendon realignments and 8 medial side reefing procedures were performed. There were no recurrences of patellar dislocation. Twelve knees were painful, of which 8 were rarely painful. All but one patient were satisfied with their results and participated in any desired sport. Surgical repair of acute patellar dislocation is advocated in the young patient who anticipates future participation in athletics.

Acute Disease↗

PubMed2002

Locked lateral patellar dislocation with impaction fracture of patella.

Irreducible lateral patellar dislocation is rare. It has previously been described with rotation around a vertical axis. We describe a case of irreducible lateral patellar dislocation in a 66-year-old lady with an impaction fracture of medial facet of patella locked on the lateral femoral condyle. Closed reduction was unsuccessful and the patient was treated by total knee replacement. Such a case has not been described previously in the literature.

Aged↗

PubMedDate not supplied

The cartilaginous femoral sulcus in children with patellar dislocation: an ultrasonographic study.

One hundred and sixteen knees of 33 patients with patellar dislocation and 25 normal children 12-18 years of age were examined by ultrasonography to measure the cartilaginous sulcus angle on the patellar surface of the femur. In knees with patellar dislocation, the cartilaginous sulcus angle measured between 154 and 195 degrees, exceeding the corresponding values of normal knees (134-153 degrees). In patient knees, the cartilaginous sulcus was also consistently wider than the underlying osseous sulcus. This suggests that in pediatric patients with patellar dislocation, the actual patella-stabilizing ability of the femoral sulcus is weaker than the osseous outline in axial radiographs would lead one to suppose. It would appear also that by measuring the cartilaginous sulcus angle of the femur, a clear distinction can be made between normal knee joints and joints displaying patellar instability.

Adolescent↗

PubMed1995

Surgery in acute patellar dislocation--evaluation of the effect of injury mechanism and family occurrence on the outcome of treatment.

A retrospective study was made of 270 patients and 284 knees with acute patellar dislocation treated operatively. The mean follow up time was 4.1 years. Medical history revealed 21.1% of cases with previous dislocations and 15.6% of cases with family occurrence of patellar dislocation. The dislocation resulted from an athletic performance in 41.5% of cases. The sport events most often associated with patellar dislocation were soccer, gymnastics, and ice hockey. All cases were treated with reefing of medial capsule. Release of lateral patellar retinacula was performed in 243 cases. Two cases were treated primarily with the Elmslie-Roux-Trillat procedure. The subjective result of operative treatment was better and the redislocation rate was lower if the injury mechanism was traumatic rather than non-traumatic and if there was no history for family occurrence of patellar dislocation.

Acute Disease↗

PubMed2003

Sonographic appearances of medial retinacular complex injury in transient patellar dislocation.

AIM: To describe the sonographic appearances of the medial retinacular (MPFR) complex of the knee in patients with acute and recurrent patellar dislocation. MATERIALS AND METHODS: Thirty patients were scanned within 2-4 weeks of an acute episode of lateral patellar dislocation. Eleven gave a history of recurrent patellar dislocation. Ten patients had examination under anaesthesia with arthroscopy and repair of the injury. The sonographic and operative results were compared. RESULTS: The normal sonographic appearance of the MPFR is described. Of the 10 patients who underwent examination under anaesthesia, four patients had complete avulsion of the MPFR from the patella, two patients had avulsion of the MPFR from the adductor tubercle and four patients had avulsion of the MPFR from both the patella and adductor tubercle. There was complete correlation between the sonographic and operative findings for injuries of the MPFR. Other findings included partial retinacular tears, injury to the medial collateral ligament, haematoma within vastus medialis obliquus (VMO) and bony avulsions from the patella and adductor tubercle CONCLUSION: Sonography gives reliable information regarding the site of the injury and its extent thus helping to decide whether conservative or operative treatment is the most appropriate approach to management of the injury.

Acute Disease↗

PubMed2003

[Study of the patellar apex in objective patellar dislocation].

PURPOSE OF THE STUDY: The purpose of this work was to study the morphology of the patella in search of dysplasia typical of objective patellar dislocation. MATERIAL AND METHODS: One hundred forty patients (190 knees), 80 women and 60 men, who underwent surgery between 1988 and 1999 were included in this study. Mean age was 22.6 years (range 13-47). Patellar morphology was analyzed on the preoperative lateral x-rays (n=190) taken at 30 degrees flexion. The apex of the patella was measured as well as the length of the patellar tendon. The width of the patella was measured on the computed tomography scan (n=158). For 64 knees, magnetic resonance images of the patella were available on which the length and width of the patella, the articular surface, and the patellar tendon were measured. Ninety contralateral knees were symptom free and x-rays were available for 67. RESULTS: According to the Grelsamer classification, 80% of the patellae presented a normal apex. The length of the patellar apex was significantly shorter when the patellar ligament was longer. Using the Wiberg classification, men had more dysplasic patellae (grade C) (p=0.007). There was also a correlation between the Wiberg classification and the Maldague classification. The length of the medial border of the patella and the patellar angle were 2 factors directly related to the Wiberg classification. Mean width of the patella was 39.1 mm (computed tomography measurements). The mean length of the patellar tendon was 53.8 on the magnetic resonance images with a mean articular surface measuring 30.8 mm, a mean patellar length measuring 40.6 mm, and a mean width measuring 38.7 mm. There was no correlation between trochlear dysplasia and patellar morphology. DISCUSSION: There is little data in the literature concerning patellar morphology since Wiberg's work in 1941. The hypothesis of patellar dysplasia rather than trochlear dyplasia, the principal factor involved in objective patellar dislocation, has not been explored extensively. The presence of a hypoplasic medial border, Wiberg grade C, or a short patellar apex suggests that a particular patellar morphotype would be involved in objective patellar dislocation.

Adolescent↗

PubMed2003

Chondral and osteochondral injuries associated with acute patellar dislocation.

PURPOSE: The purpose of this study was to evaluate the frequency and precise pathology of articular cartilage injuries after acute patellar dislocation. TYPE OF STUDY: Case series. METHODS: In 39 consecutive knees with initial lateral patellar dislocation, the articular cartilage injuries were examined using arthroscopy or macroscopic observation. RESULTS: Thirty-seven knees (95%) had articular cartilage injuries of the patellofemoral joint and 2 knees (5%) had no cartilage injury. In all 37 knees (95%), articular cartilage injuries were observed in the patella. The appearances were categorized into 3 groups: cracks alone (9 knees), cartilage defect caused by osteochondral or chondral fracture (7 knees), and cartilage defects caused by osteochondral or chondral fracture associated with cracks (21 knees). The main site of osteochondral fracture was the medial facet, and the main site of cracks was the central dome. Twelve knees (31%) had cartilage injury of the lateral femoral condyle. CONCLUSIONS: From this study, articular cartilage injuries, especially of the patella, seem to be common occurrences after acute patellar dislocation. Chondral and osteochondral injuries of the patella were classified into 3 groups.

Adolescent↗

PubMed1999

Medium-term results of the operative treatment of recurrent patellar dislocation by Insall proximal realignment.

Between 1984 and 1991, 36 patients with the diagnosis of recurrent patellar dislocation were treated operatively using the proximal realignment procedure. Thirty patients were available for follow-up. The average follow-up period was 6.3 years (range 2-9.6 years). The average age at injury was 21.3 years with a predominance of female patients. At follow-up all knees were physically examined. The results were evaluated using the score of Larsen and Lauridsen as well as the Tegner score and subjective assessment. Radiographs from 19 patients (63%) were available for review. At follow-up one patient suffered from a recurrence of patellar dislocation. All patients had stable knee joints and a full range of motion. There was no statistically significant difference between pre- and postoperative sports activity level. Seven patients (23.3%) had excellent results, 12 patients (39.9%) good results and 1 a poor result using the Larsen and Lauridsen score. Subjective assessment revealed the operative result as very good, good or satisfactory in 90%. Patellofemoral osteoarthritis was seen in 7 of 19 patients (36.8%). With a proximal realignment procedure good clinical results can be achieved for recurrent patellar dislocation. Subjective satisfaction with this procedure is rated as good. It is successful in preventing redislocation.

Adolescent↗

PubMed2000

Delayed proximal repair and distal realignment after patellar dislocation.

Twenty athletes with distal malalignment who sustained unilateral traumatic patellar dislocation remained impaired by chronic instability. Surgery was performed at a mean age of 18 years. Posttraumatic attenuation of the medial patellofemoral ligament was repaired near the margin of the patella in 10 knees and avulsion or attenuation posterior to the vastus medialis obliquus in 10 knees. Advancement of the medial patellomeniscal ligament at the margin of the patella and normalization of the Q angle to 10 degrees by tibial tubercle osteotomy were performed in each knee. Distal lateral retinacular release without release of the normal vastus lateralis tendon was performed. Results were judged according to Turba et al, and activity levels were evaluated per guidelines of the International Knee Documentation Committee. Eighteen (90%) patients achieved good or excellent results and were unimpaired at a minimum of 24 months. Two patients achieved fair subjective results with some impairment in vigorous activity. There was no recurrent instability. Radiographically, the mean preoperative patellofemoral congruence angle improved from 20 degrees to 0 degree. Athletes who sustain an initial traumatic patellar dislocation after physeal closure and in whom conservative management fails can be treated successfully by repair of the medial patellofemoral ligament at the site of disruption and advancement of the medial patellomeniscal ligament combined with correction of an elevated Q angle.

Adolescent↗

PubMed1998

Vertical patellar dislocation: a case report.

The purpose of this case report is to highlight an unusual diagnosis and mechanism of injury. Vertical patellar dislocation is an uncommon entity. Relatively few cases have been reported in the literature, and most of these have occurred in adolescent boys who have sustained a direct blow to the knee while engaging in some form of contact sport. The case reported here is a vertical patellar dislocation that happened to a 10-year-old girl without any trauma. This is an unusual case and seemingly atypical for a vertical patellar dislocation. The knowledge of this diagnosis might assist clinicians in the understanding of unlikely mechanisms of injury in the assessment and treatment of this musculoskeletal disorder.

Child↗

PubMed1988

Arthroscopic treatment of acute patellar dislocations.

Twenty-nine patients treated with arthroscopy alone for acute patellar dislocation were reviewed. All had a significant traumatic episode with hemarthrosis in a previously asymptomatic knee. Clinical follow-up averaged 25 months (range 5-64 months). Fifteen patients had concomitant percutaneous lateral release (LR). Significant-sized osteochondral defects not radiographically visible preoperatively were discovered in 40%. Fragments were excised and corresponding craters debrided or abraded. Additional intraarticular pathology discovered included two meniscal tears and one anterior cruciate tear. Overall excellent (E) and good (G) results were 83%. The recurrence rate was 14%, all of which occurred in the LR group. All recurrent dislocations occurred within 1-year post injury. The LR group had 73% G and E results compared with 93% in those without LR. Arthroscopy followed by immobilization was an efficacious approach to acute traumatic patellar dislocations in this specific group of patients. The addition of LR with early motion, however, detracted from the results.

Acute Disease↗

PubMedDate not supplied

Acute patellar dislocations. The natural history.

Of 27 patients sustaining primary patellar dislocations, 20 were treated with immobilization and subsequent physiotherapy (including nine patients who underwent arthroscopy) and seven with immediate surgical stabilization and lateral release. The patients with predisposing factors such as patellofemoral malalignment, abnormal patellar configuration, and a history of prior symptoms of instability were more prone to recurrent dislocation and may benefit from operative intervention. Although the incidence of recurrence among those individuals can be decreased, at least 30% to 50% of all patients having sustained a primary patellar dislocation will continue to have symptoms of instability and/or anterior knee pain.

Acute Disease↗

PubMedDate not supplied

Treatment of acute patellar dislocation.

To determine the effectiveness of nonoperative and operative treatment of initial acute patellar dislocation, we reviewed the charts of 399 patients with the diagnosis of an acute dislocation, seen during a 30 year period. One hundred patients (103 knees) met the criteria for inclusion in the study. The average age of the patient at injury was 21.7 years (range, 9 to 72 years). Length of followup averaged 8 years (range, 2 to 26 years). Retrospectively, we divided the patients into two groups, according to the examination of their unaffected knee. Group I (69 knees) showed evidence on examination of congenital abnormality of the extensor mechanism in the unaffected knee, indicating a predisposition to dislocate with less significant trauma. Group II (34 knees) showed no clinically perceptible congenital predisposition to dislocate based on examination of the unaffected knee. In the nonoperatively treated knees in Group I, there was a 52% (28/54) incidence of good or excellent results. The nonoperatively treated knees in Group II had a 75% (15/20) incidence of good or excellent results. Acute dislocation occurred more frequently in males than in females. Recurrence was rarer in patients whose initial dislocation had occurred when they were over 15 years old. Contrary to recently published reports, primary acute traumatic patellar dislocations can be treated with nonoperative therapy with good or excellent results. Initial evaluation should include examination of the uninvolved knee which, if found to have signs of congenital abnormality, would indicate a worse prognosis.

Adolescent↗

PubMed1982

Rotational knee strain resulting in patellar dislocation. An experimental study in rabbits.

The right lower extremities of 64 young rabbits were immobilized by a plaster spica. The animals developed a gait pattern, which included internal tibial rotation and adduction of the left (unimmobilized) tibia. Twenty-one of the animals developed medial patellar dislocation in the unimmobilized lower extremity. The mechanism of the patellar dislocation in this experimental model was possibly overstretching of the lateral colateral ligament and the lateral side of the joint capsule, associated with medial rotation of the tibia and the tibial tubercle. The direction of patellar pull when gliding inferiorly during knee flexion was shifted medially, resulting in patellar dislocation and secondarily, in formation of an exostosis under the displaced patella. Hip arthrodesis in humans, as a course of rotational instability of the contralateral knee, resembles some aspects of this experimental condition.

Animals↗

PubMed2002

Patellar dislocation in Kabuki syndrome.

We describe four individuals (two females and two males) with Kabuki syndrome and recurrent dislocation of the patella. The age of diagnosis of patellar dislocation ranged from 11 to 23 years. One individual underwent excision of the free fragment and transfer of the tibial tuberosity with good outcome. Two required patellar brace for instability. Characteristics of individuals with the syndrome at a high risk of patellar dislocation include female, adolescence or young adulthood, joint laxity, and obesity.

Abnormalities, Multiple↗

PubMedDate not supplied

Characteristics of patients with primary acute lateral patellar dislocation and their recovery within the first 6 months of injury.

We prospectively studied the characteristics and early recovery of an unselected population of patients who had acute first-time lateral patellar dislocation. The recovery program used standardized rehabilitation, emphasizing range of motion, muscle strength, and return of function. Patients returned to stressful activities including sports as tolerated when they regained full passive range of motion, had no effusion, and when quadriceps muscle strength was at least 80% compared with the noninjured limb. Seventy-four patients met the enrollment criteria; 37 men and 37 women. The average age was 19.9 years, and preinjury sports participation was similar to that of ligament-injury patients. Four percent of patients (N = 3) had a history of birth complications, 3% (N = 2) had a history of lower extremity problems as an infant or child, and 9% (N = 7) had a family history of patellar dislocation. Radiographs revealed a 50% incidence (N = 37) of patella alta; all patients demonstrated lateral patellar overhang. Patients regained range of motion (mean, 0 degrees to 132 degrees) by 6 weeks. Sports participation remained significantly reduced throughout the first 6 months after injury, with the greatest limitations in kneeling and squatting. At 6 months, 58% of patients (N = 43) noted limitation in strenuous activities. The patients who had acute primary patellar dislocation were young and active. Most injuries occurred during sports, and few patients had abnormal physical features, contradicting any stereotype of an overweight, sedentary, adolescent girl whose patella dislocates with little or no trauma.

Adolescent↗

PubMed2004

Traumatic patellar dislocation in children and adolescents: treatment update and literature review.

PURPOSE OF REVIEW: Traumatic patellar dislocation in children and adolescents is a complex problem resulting from a range of anatomic and mechanical conditions. A careful review of the literature demonstrates certain risk factors that predispose children to recurrent dislocation. With this understanding, these conditions can be managed more aggressively in the hope of an improved outcome. Additionally, a vast number of surgical procedures to correct patellar instability have been described, and recent cadaveric studies are now guiding surgical interventions. RECENT FINDINGS: Risk factors for recurrent dislocation may include various skeletal abnormalities, increased quadriceps angle, generalized ligamentous laxity, and family history. Recent anatomic and biomechanical studies have demonstrated that the medial patellofemoral ligament and the vastus medialis obliquus are the primary restraints to lateral translation and ultimately dislocation of the patella. Management should therefore be directed both at correcting anatomic abnormalities when indicated and at reconstruction of medial restraints to patellar tracking. SUMMARY: The recommendation for management of a traumatic patellar dislocation in a skeletally immature patient is initially conservative, emphasizing early motion and quadriceps strengthening. However, in patients for whom conservative management has failed or who are at particularly high risk for dislocation and require surgical intervention, repair or reconstruction of the medial patellofemoral ligament is the treatment of choice. Recent works have included investigation of less invasive techniques in children.

Adolescent↗