The subluxating or wandering femoral head in developmental dislocation of the hip.

The subluxating ("wandering") femoral head in developmental dysplasia of the hip (DDH) has heretofore not been clearly separated from subluxation. The former is passively reducible, whereas the latter is not. The subluxating hip in paralytic and other connective disorders is well established, but the author has encountered several well-documented cases of this problem in DDH, and four have at least a 2-year follow-up. Three important issues are significant in these cases. The physical findings can be very elusive in the subluxating hip, the radiographic manifestations are different from those encountered in the subluxated hip, and effective treatment requires a pelvic osteotomy that alters the shape of the acetabulum (Pemberton or Dega). The redirectional (Salter) osteotomy does not provide adequate coverage in this situation wherein the femoral head/acetabular relations are so unstable. Two examples are presented to illustrate these issues.