The Effect of Body Mass Index on Clinical Outcomes in Patients Without Radiographic Evidence of Degenerative Joint Disease After Arthroscopic Partial Meniscectomy

Purpose To examine the effect of obesity on clinical outcomes at 1 year after arthroscopic partial meniscectomy. Methods We conducted a secondary analysis of the ChAMP (Chondral Lesions and Meniscus Procedures) randomized controlled trial (N = 256). The visual analog scale for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), range of motion, and presence of effusion were assessed preoperatively and at 1 year after arthroscopic partial meniscectomy. Body mass index was categorized as normal weight, 24.99 or less; overweight, 25 to 29.99; or obese, 30 or greater. Analysis of variance or the Cochran-Mantel-Haenszel test was used to examine differences in clinical outcomes between body mass index categories, and mean ± standard deviation or number (percentage) is reported. Results Preoperatively, obese patients had worse WOMAC pain (56.2 ± 17.2 vs 61.3 ± 17.2, P  = .02), WOMAC physical function (55.8 ± 17.1 vs 62.8 ± 17.1, P  = .004), pain visual analog scale (4.9 ± 2.1 vs 4.2 ± 1.9, P  = .01), KOOS pain (49.5 ± 14.9 vs 54.0 ± 15.1, P  = .02), and KOOS quality-of-life (27.9 ± 18.3 vs 36.9 ± 17.0, P  = .001) scores, as well as decreased flexion (121.8° ± 22.6° vs 132.3° ± 16.5°, P  = .003), compared with normal-weight patients. Overweight patients (n = 51 [51.5%], P  = .03) and obese patients (n = 56 [52.8%], P  = .002) were more likely to have knee effusion before surgery than normal-weight patients (n = 17 [34%]). At 1 year after surgery, overweight (130.2° ± 7.7°, P  = .03) and obese (128.1° ± 7.1°, P  = .003) patients had decreased flexion compared with normal-weight patients (134.5° ± 8.3°). Conclusions Obese patients had worse pain, physical functioning, and quality-of-life scores, as well as decreased flexion, compared with normal-weight patients before arthroscopic partial meniscectomy. At 1 year after arthroscopic partial meniscectomy, there were no statistically significant differences in clinical outcomes but obesity was associated with decreased knee flexion. Level of Evidence Level II, prospective comparative trial.