Adolescent patellar osteochondral fracture following patellar dislocation

Purpose

Patellar dislocations in adolescents may cause osteochondral fractures of the patella. The aim of this study was to review the outcomes of adolescent patients who underwent surgical intervention for patellar osteochondral fracture following patellar dislocation.

Methods

Nine patients who underwent surgery for osteochondral fracture of the patella following dislocation were identified retrospectively. Following arthroscopic examination, if the fragment was large enough to support fixation, headless screws or bioabsorbable pins were used. Otherwise, the loose body was excised, and the donor site was managed with a microfracture. Postoperatively, patients were assessed using the International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS) outcome measures.

Results

The average age of the patients was 14.6 with average follow-up 30.2 months. Four of the nine patients underwent fixation, while five patients underwent removal of loose body with microfracture. The average defect size in the nonfixation group was 1.2 cm² compared with 3.2 cm² in the fixation group. The IKDC scores for fixation and nonfixation groups were 63.9 (SD = 18) and 76.1 (SD = 11.7), respectively. The KOOS subscale scores for symptoms, function in sports and recreation, and knee-related quality of life were higher for the nonfixation group when compared to the fixation group.

Conclusions

This is the first known series examining surgical outcomes of osteochondral fractures of the patella following patellar dislocations in the adolescent population. While patients without fixation were less symptomatic in this series, this may be attributable to more severe injuries in patients undergoing fracture fixation.

Level of evidence

Retrospective case series, Level IV.     

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.     

Locked lateral patellar dislocation: a rare case of irreducible patellar dislocation requiring open reduction

Irreducible patellar dislocations are rare injuries, but those that do occur are mainly directed intra-articularly. In this case, a 53-year-old woman sustained a locked lateral patellar dislocation when falling from a chair. A preoperative CT-scan revealed bony avulsions at the insertion of the vastus medialis muscle, the medial retinaculum, and partial disruption of the ligamentum patellae from the apex patellae. Open reduction was necessary and the torn structures were reattached with anchor systems and sutures. Postoperative management included intensive physiotherapy. At 1 year after surgery, the patient was without swelling or pain and had a normal gait, but flexion was restricted to 120°. All postoperative radiographs showed the patella correctly placed in the femoral groove. Received: 21 December 1998 Accepted: 15 April 1999     

Tibial tuberosity transfer for episodic patellar dislocation

Numerous surgical techniques have been described to address episodic patellar dislocations. Some of them involve the soft tissues whereas others primarily address a bony correction. Four principal anatomic factors have been identified that increase the risk for episodic patellar dislocations: trochlear dysplasia, patella alta, patellar tilt, and an excessive tibial tubercle-trochlear groove distance. A treatment algorithm has been proposed to correct each of these factors. It includes the tibial tuberosity transfer, which is able to correct both a patella alta and an excessive tibial tubercle-trochlear groove distance. The tibial tuberosity can be transferred distally or medially or more frequently a combination of both. It will realign the extensor mechanism and increase patellofemoral stability. This procedure may be associated with a medial patellofemoral ligament reconstruction in case of excessive patellar tilt or rarely with a trochleoplasty for major abnormal patellar maltracking.     

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.     

Recurrent patellar dislocation after medial patellofemoral ligament reconstruction

We report on three cases of recurrent lateral patellar dislocation following a medial patellofemoral ligament (MPFL) reconstruction for patellar instability. In all three cases, an isolated MPFL reconstruction was performed with a double autogenous gracilis graft. The patellar fixation was done through bone tunnels. All three patients presented with a definite moderate to severe traumatic episode resulting in a recurrent patella dislocation and a transverse avulsion fracture at the medial rim of the patella. All three were treated by an open reduction and internal fixation with good results. No complication or recurrent dislocations occurred. We suggest that this complication is caused by the original underlying pathology such as dysplastic trochlea, abnormal TT–TG, patella alta and hyperlaxity, resulting a greater reliance upon the reconstructed MPFL for patellar stability. When subjected to a severe stress, the graft, which is stronger and stiffer than the original MPFL, will cause a fracture through the medial edge of the patella. This weak area results from the previous drill holes, which act as stress risers.     

Cartilage lesions of the patella in recurrent patellar dislocation

BACKGROUND: The etiology of patellar cartilage lesions in recurrent patellar dislocation has been poorly understood. HYPOTHESIS: The pathology of cartilage lesions of the patella accompanied by recurrent patellar dislocation can be analyzed. STUDY DESIGN: Series of case reports. METHODS: In 70 knees from 57 patients with recurrent patellar dislocation, the cartilage lesions of the patella were examined using arthroscopy and/or macroscopic observation. The average age of the patients was 22 years (range, 13 to 40 years). Lesions that involved only softening were not included. RESULTS: Sixty-seven knees (96%) had articular cartilage lesions of the patella, and only 3 knees had no change. Fissuring was observed in 53 knees (76%). The most common site of fissuring was on the central dome. There were basically two types of fissuring: multiple longitudinal fissuring and marginal/radial fissuring. Fibrillation and/or erosion were observed in 54 knees (77%). Of these, 40 knees had fissuring and 14 did not have fissuring. The main site of fibrillation and/or erosion was the medial facet. CONCLUSIONS: Cartilage lesions of the patella in recurrent patellar dislocation cases were very common. Fissuring was observed mainly on the central dome, and fibrillation and/or erosion were observed mainly on the medial facet.     

Medial patellar ossification after patellar instability: a radiographic finding indicative of prior patella subluxation/dislocation

Objective  To describe the correlation between medial patellar ossification and prior patella subluxation and/or dislocation. Materials and methods  A retrospective billing database search identified 544 patients who had been diagnosed with patellar instability over a 13-year period. One hundred twenty-eight patients met the inclusion criteria. After review by a staff orthopedic surgeon and two musculoskeletal radiologists, 28 patients were found to have medial patellar ossification. The size and location of medial patellar ossification was recorded. Results  Of the 28 patients (20 males, eight females, age 13–66 years, mean 28 years) who were found to have medial patellar ossification, 22 had radiographs, 16 had magnetic resonance imaging, and ten had both. The medial patellar ossification ranged in size from 2 to 18 mm with an average of 6.8 mm. Twelve were located in the medial patellofemoral ligament (MPFL), 14 in the medial joint capsule, and two in both the MPFL and joint capsule. Twenty-seven of 28 patients had a single ossification, and one patient had two ossifications. The timing from injury to first imaging of the lesion ranged from 10 days to a chronic history (≥35 years) of patellar instability. Conclusion  Medial patellar ossification correlates with a history of prior patella subluxation and/or dislocation. The medial ossification can be seen within the MPFL or the medial joint capsule, suggesting remote injury to these structures. The presence of this lesion will prompt physicians to evaluate for patellar instability.     

Isokinetic thigh muscle performance after long-term recovery from patellar dislocation

Eighty-two patients (50 women, 32 men) underwent isokinetic muscle testing on average 13 years after a conservatively treated unilateral primary patellar dislocation. Three study groups were formed according to the natural history of recovery: group A (n = 32), patients with only primary conservative treatment; group B (n = 34) patients with conservative (group B1; ¶n = 24) or surgical (group B2; n = 10) treatment of redislocations; group C (n = 16) patients with other residual complaints (anterior knee, pain subluxations) requiring surgery. The Cybex 6000 dynamometer system was used as the testing machine for quadriceps and hamstrings muscles, with proportional deficits of peak torque as the test parameter. Isokinetic testing revealed both quadriceps and hamstring muscle atrophy even after long-term recovery from injury. There were statistically significant differences between the three study groups at both tested speeds of quadriceps muscles ¶(60 rad/s, P < 0.002; 180 rad/s, ¶P < 0.009). Groups B1 and B2 presented similar results. The muscle performance findings are probably due to more than one factor: primary immobilization, poor outcome, patellofemoral degeneration, redislocations, and residual knee complaints followed by surgery and deficiency in motor control of thigh muscle had – together or separately – an effect on muscle performance.     

Immediate surgical repair of the medial patellar stabilizers for acute patellar dislocation. A review of eight cases

An open surgical repair of the injured medial patellar stabilizers, including the vastus medialis obliquus muscle and the medial patellofemoral ligament, after acute patellar dislocation was studied in eight patients. At initial examination, all patients had tenderness over the adductor tubercle and a positive patellar apprehension sign. Four of eight patients had obvious ecchymosis over the adductor tubercle. Magnetic resonance imaging, diagnostic arthroscopy, and open surgical exploration documented injury to both the medial patellofemoral ligament and the origin of the vastus medialis obliquus muscle. In all patients, the torn muscle was retracted in an anterior and superior direction and an arthroscopic lateral release was performed followed by open primary repair of the medial patellofemoral ligament to the adductor tubercle and repair of the vastus medialis obliquus muscle to the adductor magnus tendon. Patients were evaluated postoperatively with the Kujala scoring questionnaire. The average follow-up was 3.0 years, with a minimum of 1.5 years. No patients experienced a recurrent dislocation. The average Kujala score was 91.9. Patients rated their return to athletic activity at an average 86% of their pre-injury level. The average subjective satisfaction was 96%. In appropriate cases of acute patellar dislocation, we recommend primary repair of the medial patellofemoral ligament and the vastus medialis obliquus muscle to avoid recurrent dislocation, chronic subluxation, pain, and disability.     

Arthroscopic release of the vastus lateralis tendon for recurrent patellar dislocation

BACKGROUND: Arthroscopic release of the vastus lateralis tendon for treatment of recurrent patellar dislocation has been criticized on the grounds that it may weaken the quadriceps. HYPOTHESIS: Quadriceps strength and outcome measures improve after arthroscopic release of the vastus lateralis tendon in patients with documented patellar dislocation. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Twenty patients who had recurrent patellar dislocation underwent arthroscopic lateral retinacular release that included a complete release of the vastus lateralis tendon from the superior pole of the patella and were observed prospectively. Bilateral quadriceps strength was tested preoperatively and at follow-up with an isokinetic dynamometer. Patients also completed the International Knee Documentation Committee Subjective Knee Form and the Short Form-36 preoperatively and postoperatively. RESULTS: Follow-up averaged 27 months (range, 24-43 months). There were no redislocations. Mean quadriceps strength improved by a mean of 28% (from 32.3 to 41.4 N x m). The mean quadriceps torque ratio (involved/uninvolved) improved significantly from a preoperative value of 63% (31/51 N x m) to 80% (42/52 N x m) at follow-up (P = .017). Fourteen patients (70%) increased quadriceps torque, and 6 patients (30%) decreased quadriceps torque. Only 1 patient failed to improve on International Knee Documentation Committee and Short Form-36 scores. The International Knee Documentation Committee scores improved from 45 points preoperatively to 76 points at follow-up (P = .001). The Short Form-36 physical component summary scores improved from 38 points preoperatively to 50 points at follow-up (P = .007), and the Short Form-36 physical functioning subscale scores improved from 53 points to 86 points (P = .015). CONCLUSION: Arthroscopic release of the vastus lateralis tendon and lateral patellar retinaculum in patients with recurrent patellar dislocation can improve quadriceps strength and knee function.     

关节镜辅助早期手术治疗创伤性髌骨脱位

目的探讨利用膝关节镜技术辅助治疗创伤性髌骨脱位的手术方法并评估其治疗效果。方法选择2009年10月至2012年10月沈阳军区总医院应用关节镜治疗创伤性髌骨脱位的26例患者为研究对象。其中,男性10例,女性16例;复发性髌骨脱位22例。术前行X线、三维CT及MR等影像学检查,评估髌股关节形态学变异及损伤情况。先行膝关节镜检查,处理关节内合并损伤,清除关节内积血、游离的软骨及骨碎片,镜下可以清楚观察髌内侧及髌骨下极骨软骨损伤及内侧支持带损伤情况,同时处理并存的半月板等关节内结构损伤。于镜下行髌外侧支持带松解完成关节镜操作,辅助小切口修复内侧支持带复合体稳定结构。结果平均随访24.2个月,术后均未出现髌骨再次脱位,膝关节屈伸膝活动度无明显受限,膝关节Lysholm评分优良,无髌骨弹响及不稳感,6~8周恢复日常生活及工作。结论关节镜辅助治疗创伤性髌骨脱位,安全可靠,值得推广。     

软组织联合手术治疗儿童习惯性髌骨脱位

目的探讨治疗儿童习惯性髌骨脱位的手术方法。方法对8例儿童习惯性髌骨脱位患者,采用髌外侧筋膜支持带广泛松解,髌内侧筋膜支持带紧缩,股内侧肌支点移位,使髌骨得到有效固定。结果 8例患者均得到随访,平均随访6月～3年,按一般膝关节损伤的功能评定方法:正常8膝,优6膝,良2膝,疗效满意。结论采用软组织联合手术治疗儿童习惯性髌骨脱位,不仅能实现髌股关节的稳定,股骨外髁发育不良和股骨滑车沟变浅也能获得明显改善,手术操作较简单,效果满意。     

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.     

Incidence and radiologic predictor of postoperative patellar instability after Fulkerson procedure of the tibial tuberosity for recurrent patellar dislocation

Purpose

Excellent results of anteromedialization of the tibial tuberosity for recurrent patellar dislocation have been reported; however, the contribution of the preoperative anatomic factors to postoperative patellar instability has not been well established. The purpose of this study was to investigate the mid-term results and the incidence of postoperative patellar instability after Fulkerson procedure for recurrent patella dislocation, and to determine the radiologic predictor of the postoperative patellar instability.

Methods

Sixty-two knees of 41 patients underwent Fulkerson procedure with or without lateral retinacular release for recurrent patellar dislocation and were followed-up for 85–155 months. Predisposing anatomic factors for recurrent patellar dislocation were evaluated preoperatively, including valgus knee alignment (femorotibial angle), patella alta (Insall–Salvati ratio), trochlear dysplasia (trochlear depth), lateral patellar displacement (congruence angle) and lateral malposition of the tibial tuberosity (tibial tuberosity-trochlear groove distance). The relationship between the measurements of anatomic factors and postoperative patellar instability, which was defined by the patellar re-dislocation or residual apprehension after surgery, was analyzed.

Results

The Fulkerson score and the Kujala score were significantly improved from the median of 65 (35–80) points and 68 (36–82) points preoperatively to 95 (60–100) points and 92 (57–100) points at the final follow-up, respectively. Three knees (4.8%) experienced postoperative patellar re-dislocation and 4 knees (6.5%) showed the positive apprehension sign at the final follow-up. The statistical analysis showed that the postoperative patellar instability correlated with only patella alta.

Conclusion

Patella alta was the only predictor of postoperative patellar instability after Fulkerson procedure. These results indicated that isolated Fulkerson procedure should not be indicated for recurrent patellar dislocation with severe patella alta.

Level of evidence

Case–control study, Level III.