Abhinav Bhatnagar
BACKGROUND
Total Knee Arthroplasty (TKA) nowadays is a commonly used treatment for patients suffering from severe osteoarthritis. The success of TKA is influenced by a complex interaction between the bony anatomy, the geometry of the components and the soft tissue balancing. Valgus angle subtended between the mechanical and anatomical axis of femur is one of the major factors influencing the alignment of implants. The objective of this study is to determine the variation of this valgus angle using a scannogram in patients with severe osteoarthritis presenting for TKA.
MATERIALS AND METHODS
150 consecutive patients of osteoarthritis of the knee joint presenting for total knee arthroplasty participated in our study. All patients underwent a preoperative scannogram, the mechanical and anatomical axis were drawn and the valgus angle was measured on the PACS (picture archiving and communication system) software.
RESULTS
The mean age of patients undergoing TKA was 63.62±8.38 years. Although, the mean valgus angle for the patients was 6.009±0.89 degrees, only 45 (30%) of 150 had valgus angle between 6-7 degrees. 72 (48%) had valgus angle in the range of 5-6 degrees and 9 (6%) had valgus angle in the range of 4-5 degrees. In 21 (14%) knees, valgus angle was more than 7 degrees, while in 3 (2%) knees, it was less than 4 degrees.
CONCLUSION
Fixed valgus angle resection is not reliable in restoring mechanical axis in total knee arthroplasty. A proper preoperative planning to determine the accurate valgus angle is a must to maintain alignment while performing total knee arthroplasty and thereby improve the long-term results. Scannogram is an easy, reliable and cost-effective method to determine the valgus angle.
