The Journal of Bone and Joint Surgery, Vol 77, Issue 12 1836-1844, Copyright © 1995 by Journal of Bone and Joint Surgery, Inc
Failure of intraoperatively customized non-porous femoral components inserted without cement in total hip arthroplasty
AV Lombardi, TH Mallory, RW Eberle, MB Mitchell, MS Lefkowitz and JR Williams
Department of Orthopaedic Surgery, Ohio State University Medical Center, Columbus 43215, USA.
Seventy-four primary total hip arthroplasties were performed in sixty-eight
patients between August 1990 and September 1991. Clinical assessments were
made with use of the Harris hip score and, specifically, the pain component
of that score. The preoperative radiographs were digitally quantified for
calculation of the so-called canal-to-calcar ratio and the so-called
cortical index. The postoperative radiographs were evaluated for the
percentage of the cross-sectional area of the femoral canal that was
occupied by the prosthesis; subsidence of the prosthesis; and adaptive
osseous changes, including hypertrophic cortical remodeling, osteolysis,
formation of sclerotic radiolucent lines around the prosthesis, and
formation of a pedestal at the tip of the prosthesis. The indication for
the arthroplasty was osteoarthrosis in fifty hips (68 per cent), avascular
necrosis in fourteen (19 per cent), congenital dysplasia in six (8 per
cent), and another diagnosis in four (5 per cent). The average duration of
follow-up was thirty-one months (range, eleven to forty-six months). The
average Harris hip score (and standard deviation) was 75 +/- 16.8 points
(range, 29 to 100 points), and the average score for the pain component was
37 +/- 7.5 points (range, 0 to 44 points). The average canal-to-calcar
ratio of the hips was 0.44 (range, 0.32 to 0.74), and the average cortical
index was 0.54 (range, 0.33 to 0.66). The average subsidence of the
component was 0.6 centimeter (range, 0.0 to 2.3 centimeters). The average
fill of the canal was 100 per cent proximally, 97 per cent at the middle of
the stem, and 92 per cent distally as measured on the anteroposterior
radiographs made immediately postoperatively and 100, 95, and 90 per cent,
respectively, as measured on the lateral radiographs. A failure occurred in
twenty-one hips (28 per cent) in twenty-one patients, with an average time
to failure of 21 +/- 13 months (range, one to forty-four months). The
Kaplan-Meier survival estimate (and standard error) for this population was
0.45 +/- 0.11 (confidence interval, 0.67 to 0.23) at forty-four months. The
average subsidence of the components that failed was 0.7 centimeter (range,
0.1 to 2.3 centimeters). There was no significant relationship between
failure of the component and the age or sex of the patient, the diagnosis,
or the side of the operation. Postoperative severity of pain (p = 0.09) or
subsidence (p = 0.08) alone did not reach significance for predicting
outcome. The Harris hip score alone (p = 0.05), the Harris hip score in
combination with subsidence of the femoral component (p = 0.01), and the
pain component of the Harris hip score in combination with subsidence of
the femoral component (p = 0.01) were all significant for predicting
outcome. No other measured radiographic variable was predictive of failure.
Despite optimization of the fit of the component within the femoral canal
and the percentage of the cross-sectional area of the femoral canal
occupied by the component, the clinical results indicated a high rate of
failure. Thus, these criteria are not the only requisites for stabilization
of these femoral components without cement. On the basis of these data, we
have discontinued the use of these intraoperatively customized, non-porous,
smooth femoral prosthesis.
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