Socket fixation using a metal-backed acetabular component for total hip replacement. A minimum five-year follow-up.

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Abstract
X years old (average, forty-one years old). Excluding one septic hip and one traumatic dislocation of the acetabular component, three sockets became loose in the remaining fifty-one hips. The results in thirty-four patients who were forty-five years old or younger were compared with those in a group of patients of similar age, reported by Dorr and Takei, in whom sockets without metal backing were used. Thirteen of the forty-three non-metal-backed sockets in their patients became loose or had a continuous radiolucent line at least two centimeters thick around the entire circumference of the cement on an anteroposterior radiograph, which they referred to as impending failure. In comparison, the three loose acetabular components in our thirty-four patients comprised a statistically significant reduction (p less than 0.05). No acetabular components in our series showed evidence of impending failure. We and others have reported finite-element analyses showing that a metal backing on the acetabular component reduces peak stresses in the bone, cement, and polyethylene. These analytical data are now supported by the clinical data reported here; that is, the metal backing of the acetabular component enhanced the duration of cement fixation. We did a follow-up study on fifty-three total hip-replacement procedures in forty-seven patients in whom a metal-backed acetabular component was used. The minimum follow-up was five years (average, six and one-half years). These relatively young patients ranged in age from seventeen to seventy-six years old (average, forty-one years old). Excluding one septic hip and one traumatic dislocation of the acetabular component, three sockets became loose in the remaining fifty-one hips. The results in thirty-four patients who were forty-five years old or younger were compared with those in a group of patients of similar age, reported by Dorr and Takei, in whom sockets without metal backing were used. Thirteen of the forty-three non-metal-backed sockets in their patients became loose or had a continuous radiolucent line at least two centimeters thick around the entire circumference of the cement on an anteroposterior radiograph, which they referred to as impending failure. In comparison, the three loose acetabular components in our thirty-four patients comprised a statistically significant reduction (p less than 0.05). No acetabular components in our series showed evidence of impending failure. We and others have reported finite-element analyses showing that a metal backing on the acetabular component reduces peak stresses in the bone, cement, and polyethylene. These analytical data are now supported by the clinical data reported here; that is, the metal backing of the acetabular component enhanced the duration of cement fixation. Copyright © 1982 by The Journal of Bone and Joint Surgery, Incorporated...