Evaluation and management of patellar instability in pediatric and adolescent athletes

Abstract

Context: The rising popularity and intensity of youth sports has increased the incidence of patellar dislocation. These sports-related injuries may be associated with significant morbidity in the pediatric population. Treatment requires understanding and attention to the unique challenges in the skeletally immature patient.

Evidence acquisition: PubMed searches spanning 1970-2013.

Study design: Clinical review.

Level of evidence: Level 5.

Results: Although nonoperative approaches are most often suitable for first-time patellar dislocations, surgical treatment is recommended for acute fixation of displaced osteochondral fractures sustained during primary instability and for patellar realignment in the setting of recurrent instability. While a variety of procedures can prevent recurrence, the risk of complications is not minimal.

Conclusion: Patellar stabilization and realignment procedures in skeletally immature patients with recurrent patellar dislocation can effectively treat patellar instability without untoward effects on growth if careful surgical planning incorporates protection of growth parameters in the skeletally immature athlete.

Keywords: adolescent; patellar dislocation; patellar instability; pediatric.

Figure 1.

Crossing sign on a lateral radiograph is the intersection of the trochelear floor and the most anterior edge of the lateral femoral condyle. Reproduced with permission from Dejour et al.

Figure 2.

Lateral soft tissue structures.

Figure 3.

The tibial tubercle–trochlear groove (TT-TG) distance is determined by a line from the most anterior point of the tibial tuberosity to the line running through the trochlear groove (orange). Modified from Cooney et al with permission.

Figure 4.

Medial patellofermoral ligament (MPFL) insertion site with the adductor tubercle and the medial femoral epicondyle. Blue dot, adductor tubercle apex; white triangle, medial femoral epicondyle; red area, MPFL insertion site. Modified from Fujino et al with permission.

Figure 5.

The medial patellofemoral ligament (MPFL). Reproduced with permission from Amis et al.

Figure 6.

The moving patellar apprehension test. The examiner moves the knee from full extension into flexion while simultaneously translating the patella laterally as far as possible in the first part. In part 2, the examiner flexes the knee to 90° and subsequently returns the knee to full extension while applying medial force of the patella. For a positive test, the patient expresses apprehension and/or activates the quadriceps with flexion and lateral translation of the patella during the first part of the test, while also experiencing no discomfort during the second part of the test. Reproduced with permission from Ahmad et al.

Figure 7.

Sulcus angle (θ_s) is the angle between 2 intersecting lines drawn between the highest point of the medial femoral condyle (A), lowest point of the intercondylar sulcus (C), and the highest point of the lateral femoral condyle (B).

Figure 8.

The congruence angle (θ_c) is determined by measuring the angle formed between a line bisecting the sulcus angle (θ_s), labeled “bisector line” in the figure, and a line from the lowest point of the intercondylar sulcus (C) and the lowest point on the articular ridge of the patella (D).