Tibial reference point in total knee arthroplasty in patient with proximal tibia vara: A case report

INTRODUCTION: Center of the intercondylar eminence at the proximal tibia had been widely used as a reference point for tibial bone cut in the Total Knee Arthroplasty (TKA) procedure. However, in the presence of preexisting tibia vara, the center of intercondylar eminence as tibial bone cut reference point often leads to varus malalignment after TKA procedure. CASE REPORT: 75 years old male patient complained of worsening pain on the left knee. The patient has had a history of knee osteoarthritis for the past seven years. The radiograph on the right knee revealed osteoarthritis grade 3 and left knee osteoarthritis grade 4, both with tibia vara. We planned to perform total knee arthroplasty surgery on his left knee with a preoperative planning tibial reference point of 10 mm lateral to the center. Six months after the knee replacement, there was minimal pain on activity, and full ROM was achieved on his left knee. On the radiographic X-ray evaluation, the alignment between the tibial implant surface and mechanical axis is 0.43 degrees valgus. CLINICAL DISCUSSION: In a varus knee malignment, the mechanical axis passes through one-third of the medial side of the knee, which makes the medial side of the implant wear off faster, resulting in the collapse of the medial tibia, thus decreasing implant survival and increasing the need for revision for TKA. CONCLUSION: In patients with preexisting tibia vara, tibial bone cut reference point planning before TKA procedure is important to provide longevity of implant survival and better quality of life.