Knee Osteoarthritis Following Partial Meniscectomy:Effect Of Various Degree Of Meniscal Resection

Part Ⅰ-Introduction of an MR-based semi-quantitative score for assessing partial meniscectomyPurpose: Conservative treatment for meniscal tears has been advocated over meniscectomy to reduce the risk of knee osteoarthritis(OA).However,arthroscopic partial meniscectomy is to some extent unavoidable and is one of the most frequent orthopaedic surgical procedures.However,few studies have documented the amount of meniscal resection in clinical practice;thus,it is not known how the amount of meniscal resection impacts disease burden and progression.The goal of this study was therefore to develop a MRI-based semi-quantitative scoring technique for postoperative assessment of the amount of meniscal resection and to test its reproducibility.Materials and Methods: The right knees of 158 participants from the Osteoarthritis Initiative were selected,who underwent meniscal resection.Using a newly developed semi-quantitative meniscal resection score(Men RS),the extent of meniscal resection was assessed on baseline 3.0T MRIs.Conventional 2D MRI sequences and 3D dual-echo steady state(DESS)sequences are selected and analyzed.Dividing the meniscus into radial and circumferential zones and grading each zone on a 3-point scale amount of meniscal resection was scored from 0(none)to 18(complete resection).To validate the score,findings were compared with the contralateral meniscus,which was used as a reference.Statistical analysis included intra-class correlation coefficients(ICC)and Bland-Altman plots to determine reproducibility.Results: The evaluation of amount of the resected meniscus on each knee required only 5-7 min for a musculoskeletal radiologist.Comparing the corresponding menisci of the resected right knee and the control left knee,differences in meniscal morphology were found in 110 of 158 menisci with a meniscal resection of Men RS=1–18;while 48 subjects showed no visualized differences,and therefore we scored them as Men RS = 0.For intra-and inter-reader agreement of Men RS,ICCs for the overall meniscus were 0.980 and 0.977;and in the Bland-Altman plots,most of the values ranged within a mean difference ± 1.96 SD of-0.15 ± 2.72 and-0.05±2.95,respectively.Conclusion: Using routine knee MRIs,the new meniscal resection score allows to analyze the amount of meniscal resection in a concise and semi-quantitative way with high reproducibility.Part Ⅱ-Amount of Partial Meniscectomy Impacts Severity and Worsening of Knee Osteoarthritis-Data from the Osteoarthritis InitiativePurpose: A large number of studies have counted amount of meniscectomy as the strongest predictive factor for the knee OA occurrence after meniscectomy.The goal of this study was to investigate how the Men RS-detected amounts of meniscal defect correlate with the severity and worsening of degenerative changes after meniscectomy.Materials and Methods: We studied the right knees of 135 participants from the OAI database that underwent meniscal surgery an average of 14 years previously.The amount of meniscal resection was assessed on baseline 3.0-T MRIs by a newly developed semi-quantitative meniscus resection score(Men RS)with a range of 0 to 18.Knee osteoarthritic abnormalities at baseline and 48 months were graded using a modified Whole-Organ Magnetic Resonance Imaging Score(WORMS).Subjects were also stratified according to meniscal resection performed after injury versus without preceding injury.Statistical analysis included regression models and partial correlation to correlate Men RS with baseline and change in WORMS grades.Results: The amount of meniscal resection was significantly associated with baseline WORMS grades throughout the knee: higher Men RS were associated with higher total WORMS grades(p=0.004)as well as cartilage(p=0.004),and ligament(p<0.001)subscores.Correlations were higher when analyzing the associations between WORMS abnormalities in the index compartment separately(p<0.001).However,there were no significant correlations of Men RS and change in WORMS grades over 4 years.The association of Men RS with baseline WORMS grades did not vary after further adjusting for a reported history of knee injury.Conclusion: A significant association between the amount of meniscal resection measured using the newly developed score and the degree of overall knee joint degenerative disease and cartilage defects was found.The Men RS system may be a useful predictor of knee osteoarthritis after various degrees of partial meniscectomy.