Page 187 - Reconstructive Techniques in Musculoskeletal Tumor Surgery

tumor. In all cases, we used a rotating hinged MUTARS distal femoral or proximal tibial replacement. A polyethylene locking mechanism connected the femoral and tibial components. Until March 2003, we used the conventional polyethylene lock. From then onward, the PEEK-OPTIMA (Invibio Ltd, Thornton-Cleveleys, UK) lock was used. Extension of the implant was possible in 20-mm increments. All stems and extension pieces were equipped with sawteeth at the junctions to allow rotational adjustment in 5° increments. The hexagonally shaped stems were available for uncemented (TiAl6V4) or cemented (CoCrMo) xation. Femoral stems were curved to match the natural anterior curvature of the femoral diaphysis. We generally preferred uncemented xation, unless we were unable to obtain adequate press- tting or in cases in which bone quality was deemed insu cient for uncemented xation. In the early period under study, we routinely used uncemented uncoated implants because at that time, the MUTARS system did not come with hydroxyapatite (HA)-coated stems standardly; HA-coated stems were mainly used in cases with a presumed higher risk of loosening such as patients with a failed previous reconstruction. Later, HA-coated implants were the standard for primary reconstruction. The medullary cavity was reamed with a hexagonal rasp to secure optimal contact between the bone and implant. In case of uncemented xation, the medullary cavity was under-reamed by 1 mm. In case of cemented xation, we over-reamed the canal for 2 mm and third-generation cementing techniques were used.
Table 2. Procedures performed before implantation of the primary MUTARS, subsequent reconstructions, and reasons for failure.
9
Procedure Reconstruction
Number Reason(s) for reconstruction failure
6 Allograft collapse (n = 2), allograft fracture (n = 2), nonunion (n = 1), infection (n = 1)
4 Prosthetic fracture (n = 2), loosening (n = 1), infection (n = 1)
3 Nonunion (n = 2), allograft fracture (n = 1)
2 Allograft fracture 1 Resorption
1 Recurrence
5 Recurrence
3 Recurrence 1 -
MUTARS knee replacement
En bloc resection
Curettage Arthroplasty
Allograft prosthetic composite
Kotz prosthesis Intercalary allograft
Osteoarticular allograft Extracorporeally radiated autograft Inlay allograft
Cancellous bone grafting
Cement
TKA
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