BACKGROUND: Medial meniscal extrusion (MME) is both a contributor to and a consequence of medial knee osteoarthritis (OA), with each condition exacerbating the other.High tibial osteotomy (HTO) realigns varus to valgus to alleviate medial compartment stress.This study conducted a systematic review and meta-analysis to evaluate alterations in medial meniscus extrusion values and clinical outcomes following high tibial osteotomy (HTO). METHODS: Eligible studies were identified through a comprehensive search of databases including PubMed, Scopus, Web of Science, Ovid, Embase, Cochrane Library, and CNKI up to May 13, 2024.The primary goal was to assess the values of medial meniscus extrusion before and after HTO surgery.Secondary objectives were other clinical outcomes such as imaging assessments and clinical functional assessments in medial knee OA patients.All meta-analyses used random effects models, assessing between-study heterogeneity in effect sizes with the I2 statistic and P values.A P value under 0.05 was considered statistically significant. RESULTS: Eight observational studies were included, involving 316 affected knees from 311 patients.The mean difference(MD) in the change in MME values was 2.78 (95% CI, 2.65 to 2.92
P <
0.0001).The other imaging assessments, HKA angle (MD, 8.82
95% CI, 8.57 to 9.07
P <
0.0001), WBL ratio (MD, -34.98
95% CI, -36.03 to -33.93
P <
0.0001), medial proximal tibial angle (MD, -8.61
95% CI, -9.17 to -8.04
P <
0.0001) and posterior tibial slope angle (MD, -1.19
95% CI, -2.10 to -0.27
P = 0.011), changed obviously in postoperative period.Post-surgery improvements were noted in clinical assessments, including KOOS (MD, -38.41
95% CI, -39.28 to -37.55
P <
0.0001), Tegner activity scale (MD, -2.55
95% CI, -2.74 to -2.37
P <
0.0001), Pain VAS (MD, 5.73
95% CI, 5.44 to 6.02
P <
0.0001), and WOMAC scores (MD, 36.52
95% CI, 34.46 to 38.59
P <
0.0001) compared to preoperative values. CONCLUSIONS: This systematic review and meta-analysis demonstrated that HTO effectively reduced MME values in patients with medial knee OA and concurrent MME.Simultaneously, HTO corrected lower limb force lines, significantly enhancing imaging and clinical functional assessments in patients.