Background
Unicompartmental knee arthroplasty is a surgical procedure used to relieve arthritis in one of the knee compartments in which the damaged parts of the knee are replaced. UKA surgery may reduce post-operative pain and have a shorter recovery period than a total knee replacement. Also, UKA may have a smaller incision because the implants may be smaller.
Patients and Methods
Over a period of30 months, 11 patients with medial unicompartmental osteoarthritis of the knee underwent partial knee replacement using the Oxford unicompartmental knee. Seven patients were females and 4 were males with a mean age 47.2 years (range 43 -55 years). Proper patients' selection was done based on clinical, lab and radiological examination. The patients' condition was assessed clinically using the Knee Society Score wltich is divided into a knee score and a functional score. The patients were followed up for a mean of 15 months (range 3 -27 months).
Results
Post-operatively due to strict indications for surgery, 9 patients (81.8%) reported adequate reliefofpain. Regarding the Knee Society Score, the Knee component had an average 85 points (73 -92) and the functional component had an average 83 points (69 -90). The average flexion range was 119° and average fIXed flexion was 6°. The plain radiographs showed 8 Knees in varus alignment with a mean of 4° varus and 3 knees in valgus alignment with a mean of 2.5°. Four knees showed degeneration ofthe patellofemoral joint and in two knees the lateral compartment showed signs of degeneration.
One case shows post-operative dislocation of the insert which was reduced by open reduction with no recurrence.
Conclusion
Unicompartmental knee replacement is a worthwhile procedure in selected patients. It replaces the missing bearing surface only and in the tibiofemoral joint should not be used to correct extra-articular alignment. When successful it can allow patients to return to near normal existence for their age.