A prospective study of 100 consecutive Harris-Galante porous total hip arthroplasties. 2-5-year results.

This is a prospective study of the authors' first 100 Harris-Galante porous total hip arthroplasties (THA) that were followed for 2-5 years. The mean age of the 83 patients was 43 years. Using the Harris hip rating system, 80% of the hips were rated as excellent, 13% as good, 5% as fair, and 2% as poor at final evaluation. Eighty percent of the hips had no pain, 11% had slight or occasional pain, 8% had activity-related pain, and 1% had moderate pain. Eighty-seven percent of the hips had no limp, 8% had a slight limp, and 5% had a moderate limp. One femoral component, placed as a conversion of a loose bipolar hemiarthroplasty, has been removed for loosening. Two other hips have been reoperated, one for lengthening the femoral neck and one for changing the acetabular liner. There were no problems with acetabular screw fixation and no component migrated. Only two hips had 1 mm nonprogressive radiolucent lines in all three zones. Femoral component subsidence of 3 or more mm was measured in 16 hips, but was progressive in only 1. Radiolucent and radiodense lines were frequently seen in the nonporous coated regions of the femoral stem. Loss of proximal medial femoral bone density was seen in 59% of hips, and calcar resorption was seen in 16% of hips. Although the clinical results of this uncemented implant system were good or excellent in 93% of hips, the high incidence of femoral component subsidence is worrisome.

A new technique for removal of the total hip arthroplasty acetabular component.

In revision total hip arthroplasty, an arthrographically loose or migrated cemented or porous ingrowth acetabular component may be found to be quite secure and difficult to remove. An acetabular component that is not loose may need to be removed because of infection or malposition. Based on a previous study of torque failure of cemented and uncemented acetabular components in vitro, a pneumatic impact wrench has been developed that delivers repetitive shear loads to the implant-cement or implant-bone interfaces. Eight acetabular components (three polyethylene, two metal backed, and three porous coated) were implanted with polymethylmethacrylate into fresh, unembalmed human anatomic specimen acetabuli. Seven components were easily removed using this new device at an average setting of 16 kg/m of torque. One polyethylene component could not be removed because the studs cut through polyethylene grooves. In one pelvis, a fracture occurred through a pubic anchoring hole when the driver was taken by error through a 40 degrees arc rather than the recommended 15 degrees arc. This device has been used in vivo in four cases, easily removing the components without damage to the surrounding bone.

The window technique for the removal of broken femoral stems in total hip replacement.

Removal of broken femoral stems continues to be a difficult technical procedure in hip replacement surgery, despite the development of metal drilling devices and special extractors placed into the drill hole. The window technique for the removal of broken femoral stems is technically easier than the metal drilling technique and does not require sophisticated instrumentation. This technique is also useful as a back-up procedure when metal drilling procedures fail.