Cementless total hip replacement using the AML stem. 0-10 years results using a survivorship analysis

343 primary arthroplasties using the AML stem were performed between 1978 and June, 1984 with a mean follow-up of 4.8 years. All had a two-year reading of stem fixation as: 1) bone ingrown or optimum (81%), 2) fibrous encapsulated or suboptimum stable (16%), or 3) unstable (3%). Using a roentgenographic end-point, we performed a 0-8 year survivor analysis of stem fixation. The cumulative survivorship rate (CSR) was 85% at eight years. Among 142 undersized stems, thirteen failed by migration after one year and two by stem fracture, giving a CSR of 71% at eight years. By contrast, no failure was recorded in 201 canal filling stems. Proximal stress shielding occurred only in bone ingrown stems and was slightly progressive. Widening of the intramedullary canal occurred with unstable stems. The clinical results were superior in patients with bone ingrown stems and functional recovery in those cases was equivalent to that of cemented arthroplasty.