Ashley A. Herda1, Traci Smiley2, Kyle Martin2, Kyle Veazey2, Christopher J. Cleary1, and Bryan M. Vopat2,3

1University of Kansas, Department of Health, Sport, and Exercise Sciences, Overland Park, Kansas; 2University of Kansas Health Systems, Sports Medicine and Performance Center, Overland Park, Kansas; 3University of Kansas Health Systems, Department of Orthopedic Surgery and Sports Medicine, Overland Park, Kansas

PURPOSE: The purpose of this investigation was to document the progressive changes in muscle following knee arthroscopy. METHODS: Seven males (mean ± SD: age (yrs): 18.3±1.3; height (cm): 185.1±6.6; body mass (kg): 83.2±8.7) were observed before and up to 12-weeks after knee arthroscopy. The patients data was collected using a retrospective chart review and intermittent ultrasound monitoring to quantify muscle mass cross-sectional area (mCSA) of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM). Imaging was conducted using a diagnostic ultrasound with linear array probe and transverse plane imaging software. The treatment provided to patients included the standard of care with pre-and post-operative consultation and education on treatment plan, twice weekly physical therapy (PT) sessions, and, as necessary, blood flow restriction therapy (BRFT) during the sessions. The time points of capture included 2-, 6-, and 12-weeks post-operative PT visits. Data analyses include three, (2 X 3) two-way repeated measures ANOVAs (OP vs. NO) X (2W vs. 6W vs. 12W) for each mCSA. Level of significance was set at an alpha of 0.05 for all analyses. RESULTS: The 2-way ANOVAs resulted in no significant interaction for VL and VM mCSA (p=0.398 and p=0.301, respectively), however there was a main effect for time (p<0.001 and p<0.001, respectively) and leg (p=0.01 and p=0.01, respectively). Follow-up analyses indicated there was a drop in mCSA from 2W to 12W and 6W to 12W (p=0.016, mean difference=4.0 cm2 and p=0.006, mean difference=5.1 cm2, respectively) for VL and 2W to 12W (p=0.030, mean difference=2.4 cm2) for VM. Additionally, OP was smaller than NO across times (VL: p=0.001, mean difference=7.3 cm2; VM: p=0.006, mean difference=4.73 cm2). There was no interaction for RF mCSA (p=0.708), nor was there a main effect for time (p=0.882) or leg (p=0.062). CONCLUSIONS: These preliminary data suggest all superficial quadriceps muscles significantly atrophy through the 12-weeks of PT post knee arthroscopy. These first 6-12 weeks seem to be a critical time where rapid atrophy is occurring. Implementation of the most restorative treatments, such as BFRT, may be most beneficial if they extend beyond 12 weeks.

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