Abstract
Objective
of this study was to analyse results of two stage revisions in infected megaprostheses in lower limb.
Material and methods
Between April 1983 and December 2007, 1036 modular uncemented megaprostheses were implanted in 605 males and 431 females with mean age 33.5 yrs: 160 KMFTR(r), 633 HMRS(r) prostheses, 68 HMRS(r) Rotating Hinge and 175 GMRS(r). Sites: distal femur 659, proximal tibia 198, proximal femur 145, total femur 25, distal femur and proximal tibia 9. Histology showed 612 osteosarcomas, 113 chondrosarcomas, 72 Ewing's sarcoma, 31 metastatic carcinomas, 89 GCT, 36 MFH,68 other diagnoses.
Infection occurred in 80 cases (7.7%) at mean time of 4 yrs (min 1 month, max 19 yrs) in 18 KMFTR(r), 47 HMRS(r), 5 HMRS(r) Rotating Hinge, 10 GMRS(r). Sites: 51 distal femurs, 21 proximal tibias, 6 proximal femurs, 1 total femur and 1 extrarticular knee resection. Most frequent bacteria causing infection were: Staphilococcus Epidermidis (39 cases), Staphilococcus Aureus (17) and Pseudomonas Aeruginosa (5). Infection occurred postoperatively within 4 weeks in 9 cases, early (within 6 months) in 12 cases, late (after 6 months) in 59 cases.
Usual surgical treatment was “two stage” (removal of implant, one or more cement spacers with antibiotics, new implant), with antibiotics according with coltures. One stage treatment was used for immediate postoperative infections, only since 1998.
Functional results after treatment of infection were assessed using the MSTS system.
Results
A two stage revision was attempted in 73 pts (91.2%): in 58 cases a new prostheses was implanted (with negative laboratory tests for infection) at mean time of 5 months (min 2, max 16 months), but in 3 pts infection recurred and they were amputated; 4 pts died before implanting a new prosthesis; 11 pts were amputated after several spacers since infection did not heal. One stage revision was performed in 4 of the 9 immediate postoperative infections, with successful results.
In 3 cases an amputation was primarily performed, to proceed with chemotherapy.
Revisions for infection were successful in 63 pts (79%), while 17 pts were amputated (21%).
Functional results evaluated in 53 revised cases were good or excellent in 43 (81.1%).
Conclusions
Two stage treatment of infected megaprostheses is successful in most cases. One stage has selected indications, mainly in postoperative immediate infections.
