Abstract
Objectives:
High tibial osteotomy (HTO) is increasingly performed in physically active patients with medial knee osteoarthritis (OA), who often have high expectations for return to sports (RTS) and work. While several studies have reported on RTS following medial opening wedge HTO (OW-HTO), there is limited information regarding RTS after closing or neutral wedge HTO. We have originally developed an inverted V-shaped HTO for severe varus deformity, which is classified as a neutral wedge (NW) osteotomy that combines hemi-closing and hemi-opening wedge osteotomy techniques (Figure 1). This procedure does not change the patellar height, the tibial length, or bone mass of the tibial plateau, because the center of alignment correction is located approximately at the center of rotation of angulation (CORA) of the lower-limb deformity. However, there were no reports on the details of RTS following NW-HTO. The purpose of this study was to compare RTS rates and clinical outcomes following the NW-HTO procedure with those after OW-HTO.
Methods:
A total of 104 patients (60 women and 44 men, 115 knees) who underwent HTO for a medial OA or a varus knee with spontaneous osteonecrosis of the knee (SONK) of the medial compartment from April 2015 to March 2021 were enrolled retrospectively in this study. Of those, 57 patients (30 women and 27 men, 57 knees) participated in sports activity before surgery. HTO was performed using the inverted V-shaped-HTO procedure (NW group) or OW-HTO procedure (OW group), according to the following indications. The indication of the NW-HTO included (1) a knee in which a valgus correction of more than 10° was needed to change the mechanical axis of the lower limb to 65%, or (2) a knee having patellofemoral (PF)-OA of stage 3 (the Kellgren-Lawrence classification) or more. The indication of the OW-HTO involved (1) a knee in which a valgus correction of 10° or less was enough to change the mechanical axis to 65%, and (2) a knee having PF-OA of stage 0, 1 or 2. In the NW group, 30 knees underwent inverted V-shaped-HTO. In the OW group, 27 patients underwent OW-HTO. We evaluated the pre-symptomatic, preoperative, and postoperative Tegner activity score, sports activity level classified into 4 categories, clinical outcome, and radiographic parameters before and 2 years after surgery. Statistical analyses were made using the paired t test and Mann-Whitney U test. The significant level was set at p=0.05.
Results:
Concerning the preoperative OA grades at the FT (femorotibial) and PF joints, the NW group had significantly higher grades than the OW group (p=0.02 and p<0.01 at the FT and PF joints, respectively) (Table 1). At 2 years postoperatively, 26 out of 30 patients (86.7%) in the NW group and 24 out of 27 patients (88.9%) in the OW group returned to sports activity. There were no significant differences in the RTS rates between the groups. Of the 7 patients who could not return to sports after surgery (3 and 4 patients in the OW and NW groups, respectively), 6 patients (2 and 4 patients in the OW and NW groups, respectively) had been involved in high-impact sports (e.g., baseball, skiing) before surgery. The time to RTS after HTO averaged 8.9 months and 7.8 months in the NW and OW groups, respectively, with no significant difference between the groups. The pre-symptomatic, preoperative, and postoperative Tegner activity scores averaged 4.9 (range: 3-7), 2.3 (0-5), and 4.2 (3-7) in the NW group, and 5.0 (range: 4-6), 2.9 (1-4), and 4.4 (2-6) in the OW group, respectively. The postoperative Tegner activity score was significantly higher than the preoperative score in both groups (p<0.01), with no significant differences between the pre-symptomatic and postoperative scores in either group. 17 patients (65%) and 19 patients (79%) achieved a Tegner activity score equal to or better than their pre-symptomatic level at 2 years postoperatively, in the NW and OW groups, respectively. Concerning clinical outcomes, the functional knee score (Japanese Orthopaedic Association score), Lysholm score, and Knee Injury and Osteoarthritis Outcome Score (KOOS) significantly improved after both types of HTO surgery compared to preoperative values (p<0.01) (Table 2). There were no significant differences in the pre- and postoperative clinical outcomes between the groups. Regarding preoperative coronal lower leg alignment, the NW group had severe varus deformity. Knee alignment showed significant correction in the coronal plane after both HTO procedures (p<0.01). There were no significant differences in the postoperative coronal alignment between the groups. The posterior tibial slope angle did not change in the NW group; however, it significantly increased compared to preoperative measurements in the OW group (p=0.048) (Table 3).
Conclusions:
In this study, 86.7% of the patients who underwent NW-HTO for severe medial OA returned to sports after surgery. 65% of those patients were able to return at pre-symptomatic sport activity level. There were no significant differences in the 2-year clinical outcome between the NW and OW groups. Although the preoperative degrees of varus knee, FT and PF-OA were more severe in the NW group than the OW group, the RTS rates of the patients who underwent NW-HTO were comparable than those who underwent OW-HTO. Therefore, when the patients who wish to RTS have severe varus knee combined PF and FT OA preoperatively, an inverted V-shaped HTO procedure may be one of the surgical options.
