Aim: To assess the medium term survival and radiological outcome of primary cemented modular Freeman Samuelson total knee replacement at Dumfries and Galloway Royal Infirmary, UK

Material and methods: 115 patients (118 knees), who underwent primary cemented modular Freeman Samu-elson total knee replacement from 1991 to1998, were reviewed retrospectively. Proximal cementing technique was used ti fix the metal backed tibial implant. The follow-up x-rays were also reviewed and presence of osteolysis, aseptic loosening and polyethylene wear was noted. The Knee Society radiological evaluation was used to record the osteolysis and the WOMAC score was used to evaluate functional outcome.

Results: The operation was performed for osteoarthritis (87), rheumatoid arthritis (23), psoriasis (4), Pagets disease (2), avascular necrosis (1) and gout (1). The average follow-up was 7.25 yrs (range 5–13 yrs). At the latest review 25 patients had died and 14 had undergone revision surgery. The indications for revision were aseptic loosening and polyethylene wear (3), osteolysis (3), infection (6), instability (1) and loosening of patellar component (1). Patella was resurfaced in 80 patients using press fit uncemented all-polyethylene component. Two patients with unreplaced patella underwent re-operation for patellar resurfacing due to anterior knee pain. Cumulative survival of the implant at 10 years was 93.4% for revision due to aseptic loosening or osteolysis and 86.8% for revision due to any cause. Radiolucent lines were observed in 22 patients. In 4 of these patients, the radiolucent lines were progressive and 3mm or more in size. Osteolytic lesions were seen in 10 patients. None of the patients with osteolysis or radiolucent lines were symptomatic. There was no statistical association between thickness of polyethylene and presence of osteolysis or occurrence of aseptic loosening (chi squared test)

Conclusion: Freeman Samuelson knee replacement provided good and predictable medium term outcome in our patients with tricompartmental arthritis of knee. The results of uncemented press fit all-polyethylene patellar replacement were also excellent. However, the high incidence of osteolysis even though asymptomatic, at an average follow-up of 7.25 yrs is a matter of some concern. Proximal cementing technique may lead to increased incidence of osteolysis and should be avoided in the modular Freeman Samuelson total knee replacement