Abstract
Introduction
We discuss the use of the SMILES (Stanmore Modular Individualised Lower Extremity System) in salvage revision knee surgery and review the medium-long term results of 42 cases.
Methods
This is a prospective, single-centre study. The SMILES prosthesis is a custom-made implant incorporating a rotating hinge knee joint. 42 prostheses were used in 40 patients as salvage revision procedures between September 1991 and September 1999. Patients undergoing surgery for tumours were excluded. The minimum follow-up was seven years with a mean follow-up of ten years and six months. Patients were independently assessed using the Knee Society Rating Score. The age of the patients ranged from 36-85 years (mean 68 years and 6 months). 23 of the patients were male. The original pathology was osteoarthritis in 32 patients and rheumatoid arthritis in 8 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
There was a highly statistically significant improvement in overall Knee Society scores from a mean of 26 pre-op to 72 post-op. The mean knee score improved from 26 pre-op to 68 post-op while the mean function score improved from 27 to 75. 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 medium to long term, offering an alternative to amputation in some cases. The cost compares favourably with other designs and the use is increasing in frequency.
