Femoral Head Reduction Osteotomy

Abstract

Femoral head reduction osteotomy (FHRO) is the surgical treatment of choice for a misshapen (nonspherical) and enlarged (coxa magna) femoral head in a spherical acetabulum, most often occurring as a sequela of Legg–Calves–Perthes disease, but also arising secondary to skeletal dysplasia and avascular necrosis. Left untreated, the nonspherical femoral head will cause pain due to femoro-acetabular impingement and subsequent femoro-acetabular cartilage damage and labral tear.

FHRO aims to restore sphericity in a nonspherically shaped femoral head. This technique was originally concieved by Ganz (2002) using a safe surgical dislocation technique with resection of the central third of the femoral head to convert an ellipsoid to a sphere, again using osteotomies parallel with the femoral neck. It was modified by Paley (2011), changing the orientation of the osteotomy to be perpendicular to the femoral head elongation which is a more horizontal osteotomy designed for cases where the elongation is not perpendicular to the femoral neck. Paley also introduced the concept of wedge resection for biplanar reduction compared to the always parallel cuts as Ganz proposed. The alternative to FHRO is osteochondroplasty with relative neck lengthening: removing the lateral/anterior protuberance of the femoral head to reduce impingement, while preserving the central portion of the femoral head. The best indication for osteochondroplasty is when the lateral portion of the femoral head is nonspherical or has significant cartilage damage. In most cases, however, the central portion is the location of impingement and damage and the lateral portion is spherical and remains well-preserved. FHRO is indicated in these central impingement/damage cases, since it makes no sense to resect the good lateral cartilage and preserve the damaged central cartilage.