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INTRODUCTION: Musculoskeletal (MSK) injury is an inherent risk for military personnel that can potentially impact job performance, productivity, and military readiness. Evidence is needed to show the efficacy of nonpharmacological, self-managed therapies to reduce MSK symptoms at common injury sites that are feasible for use during expeditionary operations and home stations. This systematic review and meta-analysis identified, summarized, and synthesized available evidence from randomized and non-randomized trials on the effectiveness of self-managed, home-use therapies to improve pain, muscle strength, and physical performance in military personnel with MSK injuries, when compared to controls. METHODS: The electronic databases of MEDLINE ALL Ovid, Embase.com, Cochrane Library, Scopus, Clinicaltrial.gov, and CINAHL Complete via EBSCO were systematically searched for relevant reports published in English. Utilizing the Covidence platform and consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, multiple reviewers, using pre-determined data fields, screened for eligibility, assessed risk of bias (RoB), and performed data extraction. Evaluation of treatment effectiveness was determined using multilevel mixed-effects meta-analysis. RESULTS: The database and register search yielded 1,643 reports that were screened for eligibility. After screening of titles/abstracts and full texts, 21 reports were identified for evidence synthesis. Of these, two reports were excluded and two described the same study, resulting in a final list of 18 studies (19 reports). For quality assessment, the overall RoB for the 18 studies was categorized as 33.3% low risk, 55.6% with some concerns, and 11.1% high risk. Across the five domains of bias, 70% of the reports were classified as low risk. This systematic review found that the differences in interventions, outcome measures, and design between the studies were associated with a substantial degree of heterogeneity (I2 = 60.74%), with a small overall improvement in outcomes of the interventions relative to their specific control (standard mean difference 0.28; 95% CI, 0.12 to 0.45). There were varying degrees of heterogeneity for individual body regions. This was due, in part, to a small number of studies per bodily location and differences in the study designs. For the neck/shoulder, heterogeneity was moderate, with the clearest positive effect being for physical performance outcomes via other medical devices. For the back, there was substantial heterogeneity between studies, with modest evidence that pain was favorably improved by other medical devices and exercise interventions. For the leg, one study showed a clear large effect for other medical devices (shockwave treatment) on pain with substantial heterogeneity. The best evidence for positive effects was for the knee, with mainly negligible heterogeneity and some benefits from bracing, electrotherapy, and exercise. CONCLUSION: Evidence showed small beneficial effects in pain, strength, and physical performance by individual body regions for some interventions, compared to controls. The best evidence for a positive effect was for the knee. The findings suggest that some benefit may be obtained by including several treatments during deployment in austere environments and prolonged casualty care scenarios of military personnel with MSK injuries. Further research is warranted to better assess the potential benefits of using these treatments during deployments in austere environments as part of an individualized, multimodal approach for MSK injuries.
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INTRODUCTION: The high prevalence of patellofemoral pain in military service members results in strength loss, pain, and functional limitations during required physical performance tasks. Knee pain is often the limiting factor during high-intensity exercise for strengthening and functional improvement, thus limiting certain therapies. Blood flow restriction (BFR) improves muscle strength when combined with resistance or aerobic exercise and may serve as a possible alternative to high-intensity training during recovery. In our previous work, we showed that Neuromuscular electrical stimulation (NMES) improves pain, strength, and function in patellofemoral pain syndrome (PFPS), which led us to ask whether the addition of BFR to NMES would result in further improvements. This randomized controlled trial compared knee and hip muscle strength, pain, and physical performance of service members with PFPS who received BFR-NMES (80% limb occlusion pressure [LOP]) or BFR-NMES set at 20 mmHg (active control/sham) over 9 weeks. METHODS: This randomized controlled trial randomly assigned 84 service members with PFPS to one of the two intervention groups. In-clinic BFR-NMES was performed two times per week, while at-home NMES with exercise and at-home exercise alone were performed on alternating days and omitted on in-clinic days. The outcome measures included strength testing of knee extensor/flexor and hip posterolateral stabilizers, 30-second chair stand, forward step-down, timed stair climb, and 6-minute walk. RESULTS: Improvement was observed in knee extensor (treated limb, P < .001) and hip strength (treated hip, P = .007) but not flexor over 9 weeks of treatment; however, there was no difference between high BFR (80% LOP) and BFR-sham. Physical performance and pain measures showed similar improvements over time with no differences between groups. In analyzing the relationship between the number of BFR-NMES sessions and the primary outcomes, we found significant relationships with improvements in treated knee extensor strength (0.87 kg/session, P < .0001), treated hip strength (0.23 kg/session, P = .04), and pain (-0.11/session, P < .0001). A similar set of relationships was observed for the time of NMES usage for treated knee extensor strength (0.02/min, P < .0001) and pain (-0.002/min, P = .002). CONCLUSION: NMES strength training offers moderate improvements in strength, pain, and performance; however, BFR did not provide an additive effect to NMES plus exercise. Improvements were positively related to the number of BFR-NMES treatments and NMES usage.