Bridging the Compatibility Gap in Revision Hip Arthroplasty with 14/16 Tapers: Long-Term Outcomes of the Bioball™ System

Purpose: Revision total hip arthroplasty (RTHA) in the presence of a well-fixed femoral stem is associated with increased risk, as stem removal often results in bone loss, prolonged operative time, and greater blood loss. This problem is particularly relevant for older implants with a 14/16 taper, which is incompatible with most modern femoral heads. The Bioball™ System, a modular head–neck adapter, allows for acetabular or head-only revision while preserving the femoral stem. This study aimed to evaluate long-term clinical and radiological outcomes of RTHA using the Bioball™ System in patients with 14/16 tapers. Methods: A total of 38 patients (23 women, 15 men; mean age 73.5 years) met the inclusion criteria. All procedures were carried out with a well-fixed femoral stem and a 14/16 taper. Revisions were limited to exchange of the acetabular component, liner, or both, avoiding stem removal. The primary indication was acetabular cup loosening (n = 29, 76.3%); liner-only exchange was performed in 9 patients (23.7%). Clinical outcomes were assessed using the modified Merle d’Aubigné and Postel (MAP) score, and radiological evaluation focused on fixation, migration, and loosening. Mean follow-up was 8.44 years. Results: Both the acetabular component and liner were replaced in 76.3% of patients, while 23.7% underwent liner and head exchange only. Longer adapter sizes were most frequently used, and a 7.5° offset adapter was applied in 57.9% of cases. The modified MAP score improved by a mean of 5.7 points (p < 0.05), and VAS pain scores decreased from 7.4 to 2.6 (p < 0.05). No radiological signs of loosening were observed at final follow-up. Conclusions: The Bioball™ System enables effective restoration of hip stability and offset without femoral stem removal, offering favorable long-term clinical and radiological outcomes in revisions involving older 14/16 tapers.