AimsAn evidence-based radiographic Decision Aid for meniscal-bearing unicompartmental knee arthroplasty (UKA) has been developed and this study investigates its performance at an independent centre.Patients and MethodsPre-operative radiographs, including stress views, from a consecutive cohort of 550 knees undergoing arthroplasty (UKA or total knee arthroplasty; TKA) by a single-surgeon were assessed. Suitability for UKA was determined using the Decision Aid, with the assessor blinded to treatment received, and compared with actual treatment received, which was determined by an experienced UKA surgeon based on history, examination, radiographic assessment including stress radiographs, and intra-operative assessment in line with the recommended indications as described in the literature.ResultsThe sensitivity and specificity of the Decision Aid was 92% and 88%, respectively. Excluding knees where a clear pre-operative plan was made to perform TKA, i.e. patient request, the sensitivity was 93% and specificity 96%. The false-positive rate was low (2.4%) with all affected patients readily identifiable during joint inspection at surgery.In patients meeting Decision Aid criteria and receiving UKA, the five-year survival was 99% (95% confidence intervals (CI) 97 to 100). The false negatives (3.5%), who received UKA but did not meet the criteria, had significantly worse functional outcomes (flexion p < 0.001, American Knee Society Score - Functional p < 0.001, University of California Los Angeles score p = 0.04), and lower implant survival of 93.1% (95% CI 77.6 to 100).ConclusionThe radiographic Decision Aid safely and reliably identifies appropriate patients for meniscal-bearing UKA and achieves good results in this population. The widespread use of the Decision Aid should improve the results of UKA.Cite this article: Bone Joint J 2016;98-B(10 Suppl B):3–10.

Numerous surgical techniques have been developed to treat osteochondral defects of the knee. A study reported encouraging outcomes of third-generation autologous chondrocyte implantation achieved using the solid agarose-alginate scaffold Cartipatch 1 . Whether this scaffold is better than conventional techniques remains unclear. This multicenter randomized controlled trial compared 2-year functional outcomes (IKDC score) after Cartipatch 1 versus mosaicplasty in patients with isolated symptomatic femoral chondral defects (ICRS III and IV) measuring 2.5-7.5 cm 2 . In addition, a histological evaluation based on the O'Driscoll score was performed after 2 years. We needed 76 patients to demonstrate an at least 10-point subjective IKDC score difference with a ¼ 5% and 90% power. During the enrolment period, we were able to include 55 patients, 30 of them were allocated at random to Cartipatch 1 and 25 to mosaicplasty. After 2 years, eight patients had been lost to follow-up, six in the Cartipatch 1 group, and two in the mosaicplasty group. The baseline characteristics of the two groups were not significantly different. The mean IKDC score and score improvement after 2 years were respectively 73.7 AE 20.1 and 31.8 AE 20.8 with Cartipatch 1 and 81.5 AE 16.4 and 44.4 AE 15.2 with mosaicplasty. The 12.6-point absolute difference in favor of mosaicplasty is statistically significant. Twelve adverse events were recorded in the Cartipatch 1 group against six in the mosaicplasty group. After 2 years, functional outcomes were significantly worse after Cartipatch 1 treatment compared to mosaicplasty for isolated focal osteochondral defects of the femur. ß