Patellar dislocations in children, adolescents and adults: A comparative MRI study of medial patellofemoral ligament injury patterns and trochlear groove anatomy

Purpose

The first aim was to compare medial patellofemoral ligament injury patterns in children and adolescents after first-time lateral patellar dislocations with the injury patterns in adults. The second aim was to evaluate the trochlear groove anatomy at different developmental stages of the growing knee joint.

Materials and methods

Knee magnetic resonance (MR) images were collected from 22 patients after first-time patellar dislocations. The patients were aged 14.2 years (a range of 11-15 years). The injury pattern of the medial patellofemoral ligament was analysed, and trochlear dysplasia was evaluated with regard to sulcus angle, trochlear depth and trochlear asymmetry. The control data consisted of MR images from 21 adult patients who were treated for first-time lateral patellar dislocation.

Results

After patellar dislocation, injury to the medial patellofemoral ligament was found in 90.2% of the children and in 100% of the adult patients. Injury patterns of the medial patellofemoral ligament were similar between the study group and the control group with regard to injury at the patellar attachment site (Type I), to the midsubstance (Type II) and to injury at the femoral origin (Type III) (all p > 0.05). Combined lesions (Type IV) were significantly less frequently observed in adults when compared to the study group (p = 0.02). The magnitude of trochlear dysplasia was similar in children, adolescents and adults with regard to all three of the measured parameter-values (all p > 0.05). In addition, the articular cartilage had a significant effect on the distal femur geometry in both paediatrics and adults.

Conclusion

First, the data from our study indicated that the paediatric medial patellofemoral ligament injury patterns, as seen on MR images, were similar to those in adults. Second, the trochlear groove anatomy and the magnitude of trochlear dysplasia, respectively, did not differ between adults and paediatrics with patellar instability. Thus, physicians are confronted with similar anatomical risk factors and similar injuries to the medial soft-tissue restraints in children when compared to adults with patellar instability.     

A long-term follow-up study after medial patellofemoral ligament reconstruction using the transferred semitendinosus tendon for patellar dislocation

The management of patellar dislocation syndrome has traditionally been difficult. There are no golden standard methods for patellar dislocations probably due to the many etiologies. However, it is known that medial patellofemoral ligament (MPFL) is damaged when the patella is dislocated. The purpose of this study is to examine whether our method of MPFL reconstruction is useful for the treatment of dislocated patellae and unstable patellae. Forty-six knees (43 patients) of 68 knees (65 patients) that were operated on using our surgical procedure for MPFL reconstruction with the advancement of the vastus medialis or the MPFL reconstruction with Insalls procedure were followed up for at least 5 years. The patient age ranged from 6 to 43 years. These knees consisted of six habitual dislocation patellae, twenty-six recurrent dislocation patellae, ten traumatic dislocation patellae, and four unstable patellae. The patients were evaluated pre-operatively and more than three times post-operatively at 6, 12, 36, 60, or 120 months. No patient experienced patellar dislocation after surgery. Their post-operative Kujalas scores were significantly improved. On conventional X-ray and on stress X-ray evaluations, the mean values for congruence angle, tilting angle, lateral shift ratio, medial stress shift ratio, and lateral stress shift ratio at the final follow-up (60 or 120 months) were demonstrated to be within the normal range. We conclude that our MPFL reconstruction method with the advancement of the vastus medialis or with Insalls procedure might be recommended for the treatment of habitual, recurrent, and indeed any other type of patellar dislocation, as well as for unstable patellae.     

Patellar dislocation has predisposing factors

One hundred patients with the diagnosis of an acute patellar dislocation treated conservatively and 30 healthy control subjects were studied roentgenographically by lateral and tangential views. The aim of the study was to determine the distribution and incidence of predisposing factors in different study groups. Three study groups were formed as follows: 67 patients (group A) without late problems or operative treatment of redislocation: 33 patients (group B) who underwent a surgical realignment procedure for redislocations or late problems; and 30 healthy control subjects (group C). A statistically significant difference was observed between the patient groups (A, B) and control group (C) when the means, medians and distributions of patellar tendon length (LT), patellar length (LP), tendon to patellar length ratio (LT/LP), tendon to patellar articular surface ratio (LT/LAS), sulcus angle (SA), lateral patellar displacement (LPD), lateral patellofemoral angle (LPA) and morphological classification of the patella (1–5, Jägerhut) were compared. In group A, LPD was also significantly greater than in group B. This study demonstrates a considerably high rate of predisposing factors associated with patellar dislocation.     

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.     

Proximal anterior cruciate ligament avulsion fracture in a skeletally immature athlete: a case report and method of physeal sparing repair

Traumatic rupture of the anterior cruciate ligament (ACL) in adulthood is relatively common and surgical reconstruction is frequently required to allow return to high-level activities. There is growing evidence to suggest that ACL rupture in children is more common than previously thought and a poor outcome is associated with conservative management. The site of rupture in childhood is predominantly tibial avulsion, but mid-substance tears have also been reported. We report a case of a proximal ACL avulsion in an 11-year-old athlete and discuss a method of extra-physeal repair. There are very few previous reports of proximal avulsion fractures in skeletally immature patients.     

Patellofemoral Instability in Children: Imaging Findings and Therapeutic Approaches

Patellofemoral instability (PFI) is common in pediatric knee injuries. PFI results from loss of balance in the dynamic relationship of the patella in the femoral trochlear groove. Patellar lateral dislocation, which is at the extreme of the PFI, results from medial stabilizer injury and leads to the patella hitting the lateral femoral condyle. Multiple contributing factors to PFI have been described, including anatomical variants and altered biomechanics. Femoral condyle dysplasia is a major risk factor for PFI. Medial stabilizer injury contributes to PFI by creating an imbalance in dynamic vectors of the patella. Increased Q angle, femoral anteversion, and lateral insertion of the patellar tendon are additional contributing factors that affect dynamic vectors on the patella. An imbalance in the dynamics results in patellofemoral malalignment, which can be recognized by the presence of patella alta, patellar lateral tilt, and lateral subluxation. Dynamic cross-sectional images are useful for in vivo tracking of the patella in patients with PFI. Therapeutic approaches aim to restore normal patellofemoral dynamics and prevent persistent PFI. In this article, the imaging findings of PFI, including risk factors and characteristic findings of acute lateral patellar dislocation, are reviewed. Non-surgical and surgical approaches to PFI in pediatric patients are discussed.     

体校少年运动员慢性踝关节不稳定调查研究

目的:调查体校少年运动员功能性踝关节不稳定和机械性踝关节不稳定的发病情况。方法:以某市体校7个项目293名少年运动员为对象。采用Cumberland踝关节不稳定问卷(CumberlandAnkle Instability Tool,CAIT)调查功能性踝关节不稳定情况。每个项目随机抽取3名CAIT值为20分以下的运动员,共计21名运动员进行病史调查、专科查体(寻找压痛点、测量踝关节活动度、前抽屉试验、内翻应力试验)以及踝关节MRI检查,调查机械性踝关节不稳定的发病情况。结果:7个项目293例受试者中,CAIT最高分为30分,最低分为9分,左踝平均(23.93±4.63)分,右踝(24.09±4.81)分。以27.5分作为功能性踝关节不稳定的分界点,仅19.45%受试者踝关节稳定性正常,其余80.55%存在单侧或双侧踝关节功能性不稳定的因素。随机抽取的CAIT值为20分以下的21名运动员42踝中,21.43%存在机械性不稳定。结论:功能性踝关节不稳定和机械性踝关节不稳定在体校少年运动员中较普遍存在,与训练时自我防护意识淡薄以及踝关节扭伤后处理不够正规有关。