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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↗
PubMed2004

Epidemiology and natural history of acute patellar dislocation.

BACKGROUND: The goals of this study were to (1) define the epidemiology of acute patellar dislocation, (2) determine the risk of subsequent patellar instability episodes (subluxation and/or redislocation) during the study period, and (3) identify risk factors for subsequent instability episodes. STUDY DESIGN: Prospective cohort study. METHODS: The authors prospectively followed 189 patients for a period of 2 to 5 years. Historical data, injury mechanisms, and physical and radiographic measurements were recorded to identify potential risk factors for poor outcomes. RESULTS: Risk was highest among females 10 to 17 years old. Patients presenting with a prior history of instability were more likely to be female (P < .05) and were older than first-time dislocation patients (P < .05). Fewer first-time dislocators (17%) had episodes of instability during follow-up than patients with a previous history of instability (49%) (P < .01). After adjusting for demographics, patients with a prior history had 7 times higher odds of subsequent instability episodes during follow-up than first time dislocators (adjusted odds ratio = 6.6, P < .001). CONCLUSIONS: Patellar dislocators who present with a history of patellofemoral instability are more likely to be female, are older, and have greater risk of subsequent patellar instability episodes than first-time patellar dislocators. Risk of recurrent patellar instability episodes in either knee is much higher in this group than in first-time dislocators.

Acute Disease↗
PubMed2004

Revision surgery for patellar dislocation after primary total knee arthroplasty.

This study evaluated risk factors for patellar dislocation after primary total knee arthroplasty and determined functional outcomes in patients following revision. Thirty-nine knees in 39 patients averaging 68 years (range, 27-91 years) at the time of revision were evaluated at a mean of 3.2 years (range, 2-7 years). Mean Knee Society and Function scores significantly improved from 34 and 35 to 77 and 54, respectively. Patellar dislocation most commonly resulted from errors in technique such as soft-tissue imbalance and malaligned components that led to poor tracking of the patella. Patellar tracking only improved after soft-tissue realignment in combination with revision of malaligned or loose components. Although revision significantly improved active knee extension and Knee Scores, two thirds of the patients had residual disabilities and pain.

Adult↗
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↗
PubMed2006

Hybrid medial patellofemoral ligament reconstruction using the semitendinous tendon for recurrent patellar dislocation: minimum 3 years' follow-up.

PURPOSE: The purpose of this study was to evaluate the results of a new hybrid medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar dislocation. METHODS: Hybrid MPFL reconstruction by use of the semitendinous tendon was performed in 12 knees with recurrent patellar dislocation. The results were evaluated at a minimum follow-up of 3 years (mean, 4.2 years). RESULTS: According to the grading system of Insall et al., the results were classified as excellent in 8 knees (66%), good in 2 (17%), and fair in 2 (17%), with none being classified as poor. The mean Kujala score was 56.3 points (range, 29 to 82) preoperatively and 96.0 points (range, 84 to 100) at follow-up. There were no patients with recurrent dislocation and subluxation. No knees had a positive apprehension sign, and there were no postoperative complications. CONCLUSIONS: At a midterm follow-up, hybrid MPFL reconstruction by use of the semitendinous tendon for recurrent patellar dislocation should be considered as an effective operation for cases without severe predisposing factors. LEVEL OF EVIDENCE: Level IV, therapeutic case series, no or historical control group.

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

[Resorbable pin refixation of an osteochondral fracture of the lateral femoral condyle due to traumatic patellar dislocation: case management, follow-up and strategy in adolescents].

AIM: Intraarticular osteochondral fractures resulting from traumatic patellar dislocation in children are reported most frequently between 13 and 15 years of age. Fracture localization concerns, apart from loose intraarticular bodies, the inferiomedial patellar facet and the lateral femoral condyle. Osteochondral fractures of the lateral femoral condyle with more than 50 % of its surface are extremely rare and reported infrequently. METHOD: We report a traumatic patellar dislocation in a 14 year old patient that let to an osteochondral fracture of the lateral femoral condyle. MRI-scan demonstrated an extensive fracture size concerning more than 50 % of the condylar surface with intraarticular dislocation. Initially arthroscopic surgery followed an open reduction and internal refixation of the osteochondral fragment with resorbable, poly-p-dioxanon pins. RESULTS: Follow-up MRI-scan revealed 7 weeks after surgery an adequate repositioning of the fragment with correct pin placement. Second-look arthroscopy demonstrated an osteochondral reintegration of the fragment within a period of 7 months after prior surgery. CONCLUSION: Resorbable poly-p-dioxanon pins as a mean for refixation of an osteochondral, intraarticular fracture in an adolescent, with an arthroscopic confirmed acceptable result, seem to be a considerable therapy option.

Absorbable Implants↗
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↗
PubMedDate not supplied

Functional treatment of patellar dislocation in an athletic population.

Fifty-eight athletically active study participants with 69 knees that had experienced patellar dislocations were available for followup after being selected for a functional rehabilitation program without antecedent immobilization. Follow-up evaluation was at a minimum of 24 months after onset of treatment and averaged 46.2 months. Good or excellent results occurred in 39 (66%) knees treated after an initial patellar dislocation and in 15 (50%) knees with a chronic history of patellar instability. Twenty-six percent of the 69 knees had experienced recurrent patellar instability at followup. Overall, 42 patients (73%) were satisfied with their knees after this nonsurgical management. Anatomic predisposition and onset of bilateral instability at an early age were found to be significant factors associated with a less favorable outcome.

Adolescent↗
PubMed1996

External tibial torsion: an underrecognized cause of recurrent patellar dislocation.

Seventeen patients (18 knees) with recurrent patellar dislocation were identified with increased quadriceps angles secondary to excessive isolated external tibial torsion. Traditional realignment procedures attempted in these knees were unsuccessful because of failure to align the biomechanical axis of the extensor mechanism. Derotational osteotomies of the tibia just proximal to the patella tendon insertion were used to reduce the quadriceps angle to within normal limits to improve the biomechanics of the extensor mechanism. Seventeen (94%) knees were available for clinical and subjective followup at an average of 25 months (range, 1-3.2 years). Overall, 13 of the 17 knees were graded as good to excellent (76%). Five of the 17 patients also had well established anterior knee pain in addition to recurrent dislocation and were treated with a combined derotational and Maquet type osteotomy, with 4 patients obtaining a good to excellent result. Knees that subjectively and functionally demonstrated less painful symptoms preoperatively were associated with excellent results. Poor outcomes were associated with knees that were operated on multiple times.

Adolescent↗