| ObjectiveTo investigate joint line changes after primary total knee arthroplasty in patients of osteoarthritis with fixed flexion deformity(FFD), and to evaluate factors which affect joint line during TKA.MethodsProspectively analysised patients diagnosed with osteoarthritis in the department of Henan arthroplasty center from January 2014 to June 2015. A total of 63 patients were selected and divided into three groups according to the FFD degree. There were33 cases in the non-flexion group( < 5°), 17 cases in the moderate-flexion group(10°~30°) and 13 cases in the severe-flexion group(> 30°). By using the thickness of cartilage to regulate results, the distance of preoperative and postoperative from medial epicondyle to the joint line(MEJL) as well as the most lateral point of the fibular head to the joint line(LFHJL) were measured respectively.The difference of both groups were also evaluated. The FFD degree, ROM, VAS score as well as HSS score were evaluated during preoperative, postoperative and follow-up with 6 months.ResultsThe difference value between preoperative and postoperative of MEJL in non-flexion group, moderate-flexion group and severe-flexion group were0.31±1.84 mm 〠0.86±1.28 mm and 2.17±1.08 mm, respectively. The difference value between preoperative and postoperative of LFTJL were-1.01±1.34 mm,-1.94±1.36 mm and-4.04±0.92 mm, respectively. The difference of two values which mentioned above in those three groups were0.70±2.12 mm,1.07±1.29 mm and 1.87±1.79 mm. The LFHJL difference of preoperative between severe-flexion group and other groups were statistically significant(P<0.05), and the LFHJL difference of difference value within these three groups were statistically significant(P < 0.001). The MEJL difference of difference value between severe-flexion group and other groups were statistically significant(P< 0.05). Comparing with preoperative, the ROM, VAS score and HSS score were improved significantly during follow-up. There were 7 cases(53.8%) in severe-flexion group that joint line changed over 4mm, while none in non-flexion and moderate-flexion group,1 case(5.8%)and 3 cases(23.1%) were found in moderate-flexion and severe-flexion group in 6 month follow-up.Conclusion1. Joint line elevated following TKA both in patients with and without FFD,while elevated significantly in severe FFD, less in moderate FFD and the least in patients without FFD.2. FFD could be benefited by soft tissue releases and additional bone resection of distal femur during TKA. The joint line was significantly affected by additional bone resection of distal femur in severe FFD. Soft tissue release resulted in joint line change was similar in patients with or without FFD.3. Moderate FFD could be managed during TKA, while severe FFD always remained flexion after surgery and affected ROM,VAS score, and HSS score which could improved within 6 month after TKA.4.According to joint line, it is not necessary to totally rectify FFD during TKA by using additional femoral bone osteotomy, because FFD less than 10 degree can amendmented during convalescence. |
