Between 1983 and 2006 at Rizzoli 669 knee modular uncemented prostheses were implanted after resection of the distal femur, total femur or proximal tibia. These prostheses include 126 KMFTR prostheses and 543 second generation HMRS prostheses. Patients were followed periodically in the clinic. Data was obtained from clinical charts and imaging studies with special attention to major complications requiring revision surgery. Revision for polyethylene wear was considered a minor complication, since it did not imply failure of the implant. Functional results were assessed according to the MSTS system. Since data could be misleading due to deaths in an oncologic population (although 2/3 of patients were cured or long survivors), to censore the implant unrelated events Kaplan-Meyer curves of implant survival were studied.

In 126 KMFTR group infection rated 13.5%, stem breakage 13%, aseptic loosening 9.5%; change of polyethylene rated 44%. In 543 HMRS prostheses infection rated 8.6%, stem breakage 3%, aseptic loosening 4.8%; revision for polyethylene wear rated 9.6%. Techniques of revisions and their outcome analysed showed about 2/3 of good results, but increased risk of further complications in revised implants. Functional results (MSTS system) were good or excellent in 80% of KMFTR prostheses and in 90% of HMRS.

Decrease of major complications in newer prosthetic design was statistically significant and possibly due to newer materials and modified stem design. Polyethylene wear also decreased significantly. Function was satisfactory in most patients without complications for both groups. Revision surgery is technically demanding and appropriate timing of revision is crucial, since early treatment can improve final outcome.

From October 2003 to September 2007 at Rizzoli 161 GMRS^® prostheses were implanted after resections of the lower limb. This is a modular system with a knee rotating hinge mechanism, cemented and uncemented stems, in titanium and chromium-cobalt-molybdenum, curved and straight-fluted, with or without hydroxyapatite coating. Adaptors are available to revise HMRS^® prostheses with hybrid implants. This study includes 88 males and 73 females ranging in age from 9 to 80 years. Sites of reconstruction were 109 distal femurs, 19 proximal femurs, 1 total femur and 32 proximal tibias. There were 149 oncologic and 12 non oncologic diagnoses, including 96 primary reconstructions and 65 revisions for failures of previous reconstructions. Analysis of imaging and complications was performed and function assessed according to MSTS system. Kaplan-Meier curves were used to statistically evaluate implant survival.

At a mean follow up of 2.5 yrs. 106 patients are continuously NED, 31 NED after treatment of relapse, 7 AWD, 5 DWD. There were 10 major complications: 8 infections (4.7%) (5 in primary and 3 in secondary implants) and 2 aseptic loosenings (1.2%) (1 each). There were 9 minor complications requiring minor revisions. Comparative statistical analysis of implant survival showed no statistically significant difference between primary and secondary implants. Functional results were good or excellent in 95% of patients, without any poor.

Middle term results are promising with no breakages of implant components. Besides oncological cases, there are selected indications in non oncological settings, such as revisions of prosthetic or allografts failures. While a higher complication rate was expected in secondary implants, statistical analysis shows similar survival.