An 11-year-old male is referred to physical therapy with a diagnosis of Legg–Calvé–Perthes disease (LCPD). Gait analysis reveals an antalgic gait on the affected left side. The child reports 7/10 pain in the hip and groin and difficulty with ambulation and stair climbing. His passive range of motion (ROM) is limited in left hip internal rotation, abduction, and extension. The parents report use of a Scottish-Rite brace was unsuccessful and the child is scheduled for surgical correction. The physical therapist instructs the child in crutch training pre-op and then provides gait training, RMO exercises, and strengthening post-op.

Question: What is the underlying cause for hip and groin impairments with Legg-Calvé-Perthes Disease? What are some likely pathogenesis for this? 

Potential answers:

A. Hip Avascular Necrosis (AVN) with possible pathogenesis of injury, synovitis, infection or vascular abnormalities (either inherited or developed). 

B. Fracture of the Proximal Femur with possible pathogenesis of injury or impaired bone remodeling. 

C. Femoral Nerve Impingement with possible pathogenesis of injury, structural deformity, or prolonged pressure from activity or abnormal growth. 

D. Hip Dysplasia with possible pathogenesis of congenital deformity or chronic femoral subluxation. 

Answer with rationale:  A. Hip Avascular Necrosis (AVN) with possible pathogenesis of injury, synovitis, infection or vascular abnormalities (either inherited or developed). AVN is the basic cause for LCPD, and it can develop from congenital or acquired sources. The AVN leads to destruction/degradation of the hip joint and surrounding structures, including necrosis and deformation. These in turn can lead to the symptoms noted in the patient: antalgic gait, pain, and limited mobility. 

For more information see Chapter 242: Legg-Calvé-Perthes Disease in The Color Atlas of Physical Therapy.