Abstract
Materials & method: From July 1990 to July 1997, we reviewed 58 hips in 47 patients receiving primary cemented hip arthroplasty with porous-coated prosthesis. There were 31men and 16 women. The diagnoses included AVN of femoral head in 18, OA in 4, femoral neck fracture in 33 and RA in 3 patients. The prosthesis included PCA 17, Osteonics in 18, United in 21 and Richard in 1.
Initially, all the femoral canals were prepared with the routine cementless fixation technique modified by the author (rasp-ream-rasp technique). With insertion of the final-size rasp, reliable fixation was not obtained possibly due to poor bone quality or inherent canal geometry. To avoid fracture with insertion of the next-sized stem, bone cement was added as gap-filler to augment fixation of the final-sized stems.
Result: The average age of the patients at operation was 51.1 years old (range, 34 to 88). The mean follow-up was 5.8 years (range, 2 to 10). No patients were lost to follow-up. The mean Harris hip score at final F/U was 92 points. The X-rays taken postoperatively, 3months, 6months, 1 year, 2 years and the last F/U were checked carefully. Radiographically, there was no stem loosening, no measurable subsidence or demarcation line both in bone-cement and implant–cement interfaces. Even in the thinnest area of cement layer, no breakage or fracture was detected. Load transfer predominantly occurred at proximal 1/3 in 38 stems, at middle 1/3 in 20 stems (i.e. junction of porous coating and uncoated surface of the stem). No load transfer was noted at distal 1/3.
Conclusion: When reliable cementless stem fixation is not obtained intraoperatively, cement can be added to function as “gap-filler” for augmenting the initial fixation. The clinical and radiological result is quite favorable. Thin (< 2mm) cement mantle between bone and porous-coated stem will not result in early cement mantle break and implant failure.
The abstracts were prepared by Professor Jegan Krishnan. Correspondence should be addressed to him at the Flinders Medical Centre, Bedford Park 5047, Australia.
