Counteracting Knee Flexors Strength Could Effectively Prevent the Increase in Post-operative Posterior Tibial Slope in Patients Undergoing Open‑wedge High Tibial Osteotomy
Abstract Background A difficult-solved problem is that the posterior tibial slope (PTS) increases after medial open-wedge high tibial osteotomy (OWHTO).Purpose To evaluate effects from knee flexors on changes in the posterior tibial slope after OWHTO and to determine whether counteracting the strength of knee flexors could prevent increase in post-operative PTS.Methods The study retrospectively analyzed 112 subjects (122 knees) [34 males, 78 females; mean age 59.1±6.6 (range 48–76) years; mean body mass index (BMI) 28.06±3.61 kg/m²] who underwent OWHTO. During fixing steel plates, 78 knees keeping suspended and extended to counteract the strength of knee flexors by gravity are comprised the no-flexor group and 44 knees in natural posture without counteracting knee flexors are comprised the flexor group. Patients were clinically assessed according to the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index and a visual analogue pain scale (VAS). Radiological assessment was made according to the changes in the posterior tibial slope between preoperative, 1-day post-operative and final follow-up periods. Ultimately, difference in post-operative PTS changes between the two groups was statistically analyzed. The median follow-up period was 2.2 years (range 1.6–3.7 years).Results In the final follow-up period, significant improvements were observed in the clinical scores of the VAS and WOMAC in both groups (P < 0.001), and no difference was found between the two groups. Radiological assessment showed that the final follow-up PTS was significantly greater than preoperative PTS in the flexor group (t=-6.406, P < 0.001), but no significant increase was seen in the no-flexor group (P =0.482). Increase of PTS in the flexor group was significantly greater than that in the no-flexor group at 1-day postoperative (t=2.243, P=0.030) and final follow-up periods (t=6.501, P<0.001).Conclusion For OWHTO, knee flexors would aggravate the increase in post-operative PTS. Using gravity to counteract the strength of knee flexors when fixing steel plates could effectively prevent the increase in post-operative PTS.