PURPOSE: To identify and quantify the presence of extra-articular tibia vara that might influence the mechanical axis alignment after total knee arthroplasty (TKA). MATERIALS AND METHODS: A total of 48 TKAs in 30 osteoarthritic Indian patients were prospectively evaluated. The hip-knee-ankle angle (HKA), joint line convergence angle, and varus angulation at the femur and tibia were measured from the preoperative and postoperative standing hip-to-ankle radiographs. Four different methods were used to measure the varus angulation at the tibia: metaphyseo-diaphyseal angle (MDA), the angle between the anatomical axis and mechanical axis of the tibia, the angle between the proximal third and distal third of tibia and the angle between the proximal half and distal half of tibia. RESULTS: Extra-articular tibia vara quantified using MDA had the most positive correlation with HKA. Receiver operating characteristic plotting showed that MDA of >4degrees predicts abnormal postoperative HKA. Twenty-eight out of 48 knees had MDA of >4degrees, and 78.6% of these had postoperative HKA under-correction and 21.4% had less than ideal tibial component position. CONCLUSIONS: A significant inherent extra-articular varus angulation best measured using MDA exists in the proximal tibia in osteoarthritic Indian patients undergoing TKA. MDA of >4degrees is associated with abnormal postoperative HKA. Computer navigation may be useful for achieving ideal correction in such cases.
Arthroplasty ; Axis, Cervical Vertebra ; Femur ; Humans ; Incidence ; Joints ; Knee ; Osteoarthritis ; Prospective Studies ; ROC Curve ; Tibia

PURPOSE: The poor prognosis in patients with floating knee injuries is mainly contributed to articular involvement (Fraser's type Ⅱ). This study aims to evaluate and compare the functional outcomes among different Fraser's type Ⅱ floating knee injuries after surgical management. METHODS: Twenty-seven patients with Fraser's type Ⅱ floating knee injuries (54 fractures) between September 2014 and December 2015 were enrolled prospectively in this study and were distributed according to Fraser's floating knee classification into three different groups as type ⅡA (ipsilateral femoral shaft and tibial intra-articular involvement, n = 11), type ⅡB (ipsilateral tibial shaft and femoral intra-articular involvement, n = 9) and type ⅡC (both femoral and tibial intra-articular involvement, n = 7). The differences among the groups were evaluated and compared. The functional outcomes of these injuries at one year were analyzed using Knee Injury and Osteoarthritis Outcome Score (KOOS) which covers 5 subscales of pain, other symptoms, activities of daily living, sports and recreation, and quality of life. The result was also compared with standardized age-sex matched healthy population using paired samples t-test. RESULTS: All the patients were male, and the injury mechanism was solely roadside accident. The mean age was 29.8 years and injury severity score 17.9 (comparable in all the three groups). Most injuries were observed on the right side (20 cases, 74.1%). Based on paired samples t-test, the KOOS score of patients with Fraser's type ⅡA was found to be better than that of type ⅡB and type ⅡC. Compared with the reference age-sex matched control group, patients with Fraser's type ⅡB and ⅡC fractures had significantly lower mean score in all KOOS subscales (all p < 0.01). However, Fraser's type ⅡA only revealed significant difference regarding the subscales of activities of daily living (p < 0.0001), sports and recreation (p < 0.0001), and quality of life (p < 0.0001). CONCLUSION The results of this study show that patients with Fraser's type ⅡA fractures had a better functional outcome as compared to those with type ⅡB and ⅡC fractures. This might be due to the open intra-articular involvement of the distal femur of the latter two fracture types.