Effect of Slope-Reducing Tibial Osteotomy With Primary Anterior Cruciate Ligament Reconstruction on Clinical and Radiological Results in Patients With a Steep Posterior Tibial Slope and Excessive Anterior Tibial Subluxation: Propensity Score Matching With a Minimum 2-Year Follow-up

Background: A steep posterior tibial slope (PTS) and excessive anterior tibial subluxation of the lateral compartment (ASLC) have been considered to be associated with inferior graft outcomes in primary anterior cruciate ligament (ACL) reconstruction (ACLR). Case series studies have demonstrated that combined slope-reducing tibial osteotomy can greatly improve knee functional scores and stability in revision ACLR. However, there is currently no comparative study evaluating the clinical benefits of osteotomy procedures in primary ACLR. Purpose: To assess the feasibility of combined slope-reducing tibial osteotomy and primary ACLR in patients with a steep PTS and excessive ASLC and to explore the suitable threshold for osteotomy. Study Design: Case series; Level of evidence, 4. Methods: Between 2016 and 2022, of the 108 patients with ACL injuries who had a steep PTS (≥15°) and a follow-up ≥2 years, 30 patients with excessive ASLC (≥6 mm) underwent concomitant slope-reducing tibial osteotomy and ACLR (osteotomy group), and 78 patients underwent isolated ACLR (control group). Propensity score matching at a 1:2 ratio was used to match preoperative variables between the 2 groups. After matching preoperative variables, 25 and 48 patients underwent combined surgery and isolated ACLR, respectively. The primary outcome was ACL graft status (failure and laxity rates). The secondary outcomes were ASLC and anterior tibial subluxation of the medial compartment (ASMC), KT-1000 arthrometer side-to-side difference (SSD), pivot-shift grade, and second-look arthroscopic findings. Stratified analysis was performed with 1° PTS increments to explore the osteotomy threshold. Results: Both groups were comparable in terms of age, sex, side, body mass index, PTS, graft diameter, time from injury to surgery, ASLC, ASMC, KT-1000 arthrometer SSD, pivot-shift grade, and meniscal injuries (all P > .05). The mean PTS significantly decreased from 18.2° to 6.7° ( P < .001) in the osteotomy group. The 2-year rate of ACL graft laxity was 12.0% in the osteotomy group and 35.4% in the control group, with a statistically significant difference ( P = .033). There was no significant difference in the 2-year rate of ACL graft failure between the 2 groups (8.0% vs 12.5%, respectively; P = .559). The final follow-up data showed that improvements in ASLC (4.5 vs 6.4 mm, respectively; P = .012) and ASMC (2.8 vs 4.5 mm, respectively; P = .014) were more significant in the osteotomy group compared with the control group. On the second-look arthroscopic examination, the incidence of graft roof impingement in the control group was significantly higher than that in the osteotomy group (22.9% vs 4.0%, respectively; P = .039). No significant differences were observed between the 2 groups in terms of KT-1000 arthrometer SSD and high-grade pivot shift ( P > .05). Furthermore, stratified analysis revealed that the combined procedure significantly reduced the ACL graft failure rate and improved the KT-1000 arthrometer SSD in patients with a preoperative PTS ≥16°. Conclusion: Slope-reducing tibial osteotomy combined with primary ACLR significantly decreased the amount of anterior tibial subluxation, the incidence of graft roof impingement, and the graft laxity rate for patients with a steep PTS (≥15°) and excessive ASLC (≥6 mm). Furthermore, in patients with a PTS ≥16°, the combined procedure improved anterior knee stability and reduced the graft failure rate. Therefore, a PTS ≥16° plus ASLC ≥6 mm may be considered an appropriate indication for combining slope-reducing tibial osteotomy with primary ACLR.