The aim of this study was to determine prospectively whether a lateral capsular approach to the knee joint for the purposes of total knee arthroplasty confers any advantage over the traditional medial capsular approach. One hundred consecutive valgus osteoarthritic knees with greater than 10′ deformity were randomised into two groups each using a different surgical approach to the knee joint but all patients receiving the same type of arthroplasty components. One group had the replacement arthroplasty utilising a standard medial para-patellar approach and incorporating a lateral retinacular release where required whilst the other group received a modified lateral capsular approach avoiding osteotomy of the tibial tubercle and repositioning vastus lateralis at closure. Both groups were well matched in terms of age and sex. Each patient was reviewed in a special clinic at one year post-op to establish functional outcome and to review post-operative complications and length of stay and to conduct a radiological assessment of the implant. Pre and post-operative assessment utilised the HSS and Oxford knee scores. The assessor (a research physiotherapist) was blinded to the randomisation. Results: All one hundred patients will have had their twelve month follow-up by February 2002. The results of the first 67 knees have been analysed in a preliminary study. The knee post-operative HSS and Oxford scores for the medial capsular group were 77.4 and 26 respectively and for the lateral capsular group 81.2 and 26.8. 79.4% of the patients in the medial group and 88% of patients in the lateral group showed good to excellent results on HSS scoring. Average patient satisfaction on a scale of 10 was 7.9 for the medial group and 8.5 for the lateral group. Other criteria such as range of motion, correction of deformity and stability were comparable in the two groups but it was noted that there was a tendency to use more constrained implants in the medial group. The differences between the two sets of results are not statistically significant in this preliminary report. There was no increase in wound complications in the lateral group despite incomplete closure of the capsule.
67 knees (47 patients) with a valgus deformity of more than 10° suitable for total knee replacement were randomised to two different approaches. One group (36 knees) had their knees replaced by the standard medial para-patellar approach, whilst the other (31 knees) received a modified lateral approach (without an osteotomy of the tibial tubercle and with repositioning of the contracted vastus lateralis). Both groups were well matched with a predominance of females and mean age of 67 years. The average follow up was 29 months. Patients were assessed both pre and post operatively by the HSS (Hospital for Special Surgery) and Oxford knee scores, radiologically by weight bearing AP and lateral radiographs and by patient satisfaction scores on a scale of 10. The mean pre operative HSS and Oxford scores for the medial group were 35.3 and 46.3 respectively and for the lateral group were 35.3 and 46.3 respectively. The mean post operative HSS and Oxford scores for the medial group were 77.4 (mean improvement of 41.4 points) and 26 respectively and for the lateral group was 81.2 (HSS score, mean improvement of 45.9 points) and 26.8 (Oxford score). 79.4% of patients in the medial group and 88% of patients in the lateral group showed good to excellent results (using the HSS scoring system). At two years none of the knees were radiologically loose or mal aligned. Average patient satisfaction on a scale of 10 was 7.9 for the medial group and 8.5 for the lateral group. One patient reported no relief of pain and an acute limitation of function at two years. She suffers from severe Parkinson’s disease and disabilities arising from multiple joint pathologies. There was no incidence of an early or late infection. Pain relief, range of motion, deformity correction and stability were comparable in the two groups. The results suggest that a lateral capsular approach for the replacement of valgus knees may give higher knee scores than a conventional medial approach. The differences between the two sets of results are not however statistically significant. There was no increase in wound complication in the lateral group despite incomplete closure of the capsule. The lateral capsular approach is as safe and effective as the medial capsular approach for replacement of the valgus osteoarthritic knee.
