RESTORATION OF HIP JOINT CONGRUENCY AFTER PERTHES DISEASE WITH PARTIAL ARTHOPLASTY: A NEW TECHNIQUE

Abstract

Introduction: Perthes disease often leaves young adults with hip joint incongruency due to femoral head asphericity, (an extra-articular extrusion and a superior flattening). This causes femoroacetabular impingement, a reduced range of movement and early degenerative change. We report a novel method for restoration of femoral head sphericity and femoroacetabular congruency.

Methods: 2 males (21 & 22 years) presented with groin pain and severe hip stiffness after childhood Perthes disease. Imaging confirmed characteristic saddle shaped deformities of the femoral head, with central depression and overlying cartilage loss. A new method of treatment was proposed. Both cases were treated in the same manner.

Results: Using a surgical dislocation with the trochanteric flip osteotomy it was possible to remove the extra-articular bump to reduce femoroacetabular impingement. We found that the sphericity of the femoral head could be restored using a HemiCap partial resurfacing (Arthrosurface, MA, USA). The radius of the implant was selected to match that of the acetabulum.

Restoration of the height of the flattened portion of the weight-bearing surface of the femoral head reduces abnormal loading of the acetabular articular cartilage by improving congruency of the joint.

At a minimum of 3 year follow up both patients had sustained improved range of movement, pain and Oxford hip score. Repeated imaging shows no evidence of joint space narrowing or loosening at this stage.

Conclusion: We conclude that this novel treatment functions well in the short term. Further studies are needed to confirm that after Perthe’s disease this treatment results in improved long term durability of the natural hip joint.