J Korean Orthop Assoc.  2021 Feb;56(1):42-50. 10.4055/jkoa.2021.56.1.42.

Periprosthetic Fracture around Tumor Prosthesis, Comparison of Results with or without Cortical Strut Onlay Allograft

• Kim Y
• Cho WH
• Song WS
• Lee K
• Jeon DG

• KMID: 2512895
• DOI: http://doi.org/10.4055/jkoa.2021.56.1.42

Abstract

Purpose
Periprosthetic fractures of a tumor prosthesis are rare but have difficulties in achieving sound fixation because of the poor bone quality, which increases the risk of loosening or re-fracture, even after bone union. A cortical strut onlay allograft was adopted for peri-prosthetic fractures after hip arthroplasty into the periprosthetic fracture of a tumor prosthesis, assuming that it would assist in firm fixation, shorten the time to union, and increase the bone stock, thereby, lower the chance of loosening and re-fracture.
Materials and Methods
This study reviewed 27 patients (30 cases) of periprosthetic fracture of tumor prosthesis. Sixteen cases (allograft group) had augmentation with an onlay allograft, while 14 cases (conventional group) had internal fixation or conservative treatment. The following were assessed; mode of periprosthetic fracture, difference in the time to union between a strut cortical onlay allograft and without it, and survival of prosthesis, complication, and functional outcome between the two groups.
Results
According to the unified classification system (UCS), 21 cases were type B (70.0%; B1, 14; B2, 1; B3, 6) and 9 cases were type C.The five-, 10-year survival of the 30 reconstructions by Kaplan–Meier plot was 84.5%±4.18% and 42.2%±7.83%, respectively. The average time to bone union of the entire cohort was 5.1 months (range, 2.0–11.2 months). The allograft group (3.5 months) showed a shorter period for union than the conventional group (7.2 months) (p<0.0001). All four cases of major complications occurred in the conventional group. Two cases with loosening and anterior angulation were treated with a change of prosthesis, and another with infection underwent amputation. The remaining case with loosening had conservative management. At the final follow-up, the average Musculosketal Tumor Society score of the allograft group (26.1) was better than that of the conventional group (20.9).
Conclusion
Bone union in periprosthetic fractures of a tumor prosthesis can be achieved, but the minimization of complications is important. An onlay allograft facilitates firm fixation and increases the bone stock with a shortened time to union. This simple method can minimize the risk of loosening, joint contracture, and re-fracture.

Keyword

tumor; prostheses; periprosthetic fractures; allograft