Knee valgus and patellofemoral instability after pediatric anterior cruciate ligament reconstruction: a case report and review of the literature

BACKGROUND: Pediatric athletes who undergo anterior cruciate ligament reconstruction are at risk for a growth deformity if the surgery violates the physes. CASE: A 12-year-old African American boy underwent anterior cruciate ligament reconstruction using a hamstring autograft. The procedure violated the distal femoral growth plate and the perichondrial ring of LaCroix, resulting in a distal femoral lateral physeal growth arrest. Three years later, he had developed a 15° valgus deformity, an increased quadriceps angle and patellofemoral instability. He was able to return to sports after undergoing a distal femoral osteotomy to correct the valgus and medial patellofemoral ligament reconstruction to stabilize the patella. CONCLUSION: Anterior cruciate ligament reconstruction in athletes with open physes has the potential to cause distal femoral valgus deformity, an increased quadriceps angle, and subsequent patellofemoral instability.