Prevalence of extra-articular deformity (EAD) and tibia vara (TV) in patients undergoing total knee arthroplasty (TKA) in Indian population.

Varus deformity is the predominant knee deformity observed in osteoarthritic patients undergoing Total Knee Replacement (TKR). Extra-articular deformities (EADs) have been identified as one of the significant contributors to postoperative dissatisfaction and suboptimal functional outcomes. This study analyzed 500 preoperative knee scannograms from 371 patients. Standing scannograms of both lower limbs were assessed by a trained orthopaedic surgeon to calculate several angular measurements: Hip-Knee-Ankle (HKA), Mechanical Lateral Distal Femoral Angle (mLDFA), Mechanical Medial Proximal Tibial Angle (mMPTA), Joint Line Congruence Angle (JLCA), Center Of Rotation of Angulation (CORA) for both femur and tibia, Epiphyseo-Diaphyseal Angle (EDA), and Tibia Vara Angle (TVA). An EAD was defined based on the CORA location being greater than 7 cm from the knee joint line for the tibia and greater than 3 cm for the femur. The mean age of patients was 66.58 ± 8.19 years, with a male-to-female ratio of 1:2.28. Varus deformities were present in the femur in 279 knees (55.80 %), in the tibia in 206 knees (41.20 %), and in both femur and tibia in 127 knees (25.40 %). Notably, 498 knees (99.60 %) demonstrated increased JLCA, indicating significant joint line alteration. EADs were identified in 51 patients (10.2 %), signifying that approximately 1 in 10 patients operated on for TKA exhibited significant extra-articular deformities. This study establishes that 10.20 % of knees in an Indian cohort displayed significant EADs. Varus deformities were primarily associated with alterations in LDFA, MPTA, and JCLA measurements. The almost universal alteration of joint lines among patients scheduled for TKR underscores the importance of precise preoperative planning. Embracing advanced technologies such as robotics and enhancing our understanding of varus deformity could facilitate a more tailored approach to deformity correction, potentially elevating surgical outcomes.