Intraarticular abnormalities in residual Perthes and Perthes-like hip deformities.

BACKGROUND: Residual Perthes and Perthes-like hip deformities are complex and may encompass proximal femoral deformity, secondary acetabular dysplasia, and associated intraarticular abnormalities. These intraarticular abnormalities have not been well characterized but may influence surgical technique and treatment outcomes.

QUESTIONS/PURPOSES: We (1) determined the characteristics of intraarticular disease associated with residual Perthes-like hip deformities; and (2) correlated these intraarticular abnormalities with clinical characteristics and radiographic parameters of hip morphology.

METHODS: We retrospectively reviewed 35 patients (36 hips) with residual Perthes or Perthes-like deformities and hip symptoms treated using a surgical dislocation. There were 24 males and 11 females; mean age was 18.5 years (range, 10-36 years). We prospectively documented all intraoperative findings and comprehensively reviewed all radiographs.

RESULTS: Labral abnormalities and acetabular and femoral head cartilage abnormalities were present in 76%, 59%, and 81% of hips, respectively. Male sex was associated with severe chondromalacia (64% versus 27%), femoral head chondromalacia (92% versus 55%), and advanced radiographic osteoarthritis (44% versus 9%). Stulberg classification of 3 or greater was associated with moderate to severe acetabular chondromalacia (71% versus 30%). Lateral center-edge angle > 20° and acetabular inclination < 15° correlated with severe chondromalacia (73% versus 38%; 23% versus 70%). Center-trochanteric distance < -1.7 was associated with labral tears (90% versus 57%).

CONCLUSIONS: Chondral lesions and labral tears are common in symptomatic patients with residual Perthes or Perthes-like deformities. Male sex, a high trochanter, and joint incongruity are associated with more advanced intraarticular disease. Secondary acetabular dysplasia seems to protect the articular cartilage in that hips with acetabular dysplasia had less chondromalacia.