Abstract
Introduction: We discuss the use of the SMILES (Stanmore Modular Individualised Lower Extremity System) in revision knee arthroplasty and review the outcome of 32 cases.
Methods: The SMILES prosthesis incorporates a rotating hinge knee joint. It can overcome the major problems of bone loss and ligamentous laxity. 32 prostheses were used in 30 patients as salvage revision procedures between Sept. 1991 and Sept. 1998. Patients receiving surgery for tumours were excluded. The minimum follow-up was two years with a mean follow-up of 4 years and six months. The age of the patients ranged from 36–85 years (mean 68years and 6months). 18 of the patients were male. The original pathology was OA in 23 patients and RA in 7 patients. The number of previous arthroplasties ranged from 1–4. The main indications for a SMILES prosthesis were aseptic loosening, periprosthetic fracture and infection, in the presence of bone loss and ligamentous laxity.
Results: The patients were assessed using the Knee Society Rating Score. The mean knee score improved from 26 pre-op to 68 post-op while the mean fiction score improved from 27 to 75. Overall Knee Society scores improved from a mean of 26 to 72. The average range of motion was 60 degrees pre-op and 90 degrees post-op. Complications included: failure to eradicate infection in two patients, with one patient needing amputation; infection of the prosthesis leading to revision in one, and failure of the tibial component needing revision.
Conclusion: The Smiles has produced satisfactory results in the short to medium term, offering an alternative to amputation in some cases. The cost compares favourably with other designs and the use is increasing in frequency.
The abstracts were prepared by Mr R. B. Smith. Correspondence should be addressed to him at the British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
