Knee osteoarthritis (OA) is one of the most common musculoskeletal disorders, especially among the elderly [
1‐
3]. About 8 million and 25 million individuals are affected by symptomatic and asymptomatic knee OA, respectively, in Japan [
4]. Surgical approaches to the treatment of advanced medial unicompartmental knee OA have received considerable attention, and recent studies have highlighted the efficacy of osteotomy and prosthetic arthroplasty [
5‐
7]. Due to advances in both materials and designs, the longevity of total knee arthroplasty (TKA) has increased, and patients from a diverse age range are now undergoing this procedure [
6,
7]. However, TKA has some problems with material durability, the risk of metal allergies and patient dissatisfaction with joint range of motion (ROM), especially in young, physically active patients [
8‐
10]. Moreover, concerns have been raised regarding complications such as deep or superficial implant-associated infections, wear of the prosthesis, and vein thromboembolism [
11‐
13]. Therefore, osteotomy procedures have been recommended for young and physically active patients wanting to maintain wide ROM, or for individuals who participate in high-demand activities and want to avoid prosthetic arthroplasty [
14,
15]. Open-wedge high tibial osteotomy (HTO), the most common osteotomy procedure for treating knee OA [
15,
16], is based on the concept of realignment to redistribute weight-bearing and mechanical stress laterally to areas with less destruction, thus relieving pain and improving function [
16]. As tibiofibular joint disruption and peroneal nerve injury are potential complications associated with lateral closed-wedge HTO, the medial-approach open-wedge HTO, which avoids such complications, has gained popularity [
17‐
19]. Recent developments in internal fixator devices, surgical techniques, and artificial bone graft have enabled early bone union and gap filling, contributing to better clinical outcomes [
20]. Even in open-wedge HTO, however, risks include lateral hinge fracture, damage of neurovascular tissue by long proximal screws, loss of correction, and overcorrection due to implant loosening and nonunion [
5,
19,
21]. Furthermore, negative effects on the patellofemoral (PF) joint, limited knee extension, and disease progression due to ligamentous joint laxity remain a concern [
22‐
24]. Knee OA with a Kellgren-Lawrence (K/L) grade [
25] ≥ 2 or laxity of the knee joint represent risk factors for declining clinical outcomes after HTO [
24,
26]. Hence, in terms of indications, HTO is restricted to patients with mild to moderate medial knee OA in which high joint stability is maintained [
5,
15].
Tibial condylar valgus osteotomy (TCVO), a novel L-shaped osteotomy developed in the 1990s in Japan, also corrects lower extremity alignment from varus to valgus and shifts the weight-bearing (mechanical) axis laterally [
27]. TCVO together with remodeling of the shape of the tibial plateau can improve femorotibial joint congruity and stability. The combined features of osteotomy and arthroplasty are thus promising for effective treatment of severe knee OA [
28]. Due to improvements in implants in recent years, TCVO is now making use of locking plates, resulting in shorter postoperative rehabilitation. In our institute, HTO and TCVO are selected individually on a case-by-case basis for medial knee OA and have yielded almost all successful results [
27]. However, TCVO is not widespread because of the technical difficulties and uncertain universal radiological indications. To date, no studies have investigated radiological features of TCVO compared to HTO, and radiological indication criteria for TCVO have not been identified.
The purpose of this study was to evaluate differences in radiological features between HTO and TCVO in detail, and to clarify the radiological indications for TCVO, to facilitate decision-making when choosing between the two surgical techniques.