Knee extensor muscle weakness is a risk factor for the development of knee osteoarthritis: an updated systematic review and meta-analysis including 46 819 men and women

ObjectiveTo update a systematic review on the association between knee extensor muscle weakness and the risk of incident knee osteoarthritis in women and men.DesignSystematic review and meta-analysis.Data sourcesSystematic searches in PubMed, EMBASE, SPORTDiscus, CINAHL, AMED and CENTRAL in May 2021.Eligible criteria for selecting studiesLongitudinal studies with at least 2 years follow-up including baseline measure of knee extensor muscle strength, and follow-up measure of symptomatic or radiographic knee osteoarthritis. Studies including participants with known knee osteoarthritis at baseline were excluded. Risk of bias assessment was conducted using six criteria for study validity and bias. Grading of Recommendations Assessments, Development and Evaluation assessed overall quality of evidence. Meta-analysis estimated the OR for the association between knee extensor muscle weakness and incident knee osteoarthritis.ResultsWe included 11 studies with 46 819 participants. Low quality evidence indicated that knee extensor muscle weakness increased the odds of symptomatic knee osteoarthritis in women (OR 1.85, 95% CI 1.29 to 2.64) and in adult men (OR 1.43, 95% CI 1.14 to 1.78), and for radiographic knee osteoarthritis in women: OR 1.43 (95% CI 1.19 to 1.71) and in men: OR 1.39 (95% CI 1.07 to 1.82). No associations were identified for knee injured populations except for radiographic osteoarthritis in men.DiscussionThere is low quality evidence that knee extensor muscle weakness is associated with incident symptomatic and radiographic knee osteoarthritis in women and men. Optimising knee extensor muscle strength may help to prevent knee osteoarthritis.PROSPERO registration numberCRD42020214976.

Plantar flexor muscles of kangaroo rats (D. deserti) shorten at a velocity to produce optimal power during jumping

During jumping by kangaroo rats, the musculotendon work contributions across all joints are not well understood. Namely, measures of external joint work do not provide information on the contributions from individual muscles or in-series elastic structures. In this study, we examined the functional roles of a major ankle extensor muscle, lateral gastrocnemius (LG), and of a major knee extensor muscle, vastus lateralis (VL), through in vivo sonomicrometry and electromyography techniques, during vertical jumping by kangaroo rats. Our data showed that both muscles increased shortening and activity with higher jumps. We found that knee angular velocity and VL muscle shortening velocity were coupled in time. In contrast, the ankle angular velocity and LG muscle shortening velocity were decoupled, and rapid joint extension near the end of the jump produced high power outputs at the ankle joint. Further, the decoupling of muscle and joint kinematics allowed the LG muscle to prolong the period of shortening velocity near optimal velocity (Vopt), which likely enabled the muscle to sustain maximal power generation. These observations were consistent with a LG tendon that is much more compliant than that of the VL.

Comparison of the effectiveness of extensor muscle strengthening exercise by itself, exercise with polydeoxyribonucleotide injection, and exercise with extracorporeal shockwave therapy in lateral epicondylitis: a randomized controlled trial

Background: Extensor muscle strengthening exercises with counterforce bands (EX) is a conventional conservative treatment for lateral epicondylitis (LE) of the elbow. In addition, polydeoxyribonucleotide (PDRN) or extracorporeal shockwave therapy (ESWT) has been recently used for tennis elbow.Methods: Sixty-three patients with chronic LE participated in this study and randomly allocated in three groups (G1: EX, G2: EX+PDRN injection, and G3: EX+ESWT). All of the three groups were taught to perform EX at the first out-patient department (OPD) visit. Group 2 was injected with 3 mL PDRN (5.625 mg/3 mL), while group 3 received ESWT at the first OPD visit. Visual analog scale pain score, Mayo elbow performance score (MEPS), and ultrasonographic examination were checked before, 6 weeks, and 12 weeks after the treatments.Results: Overall functional scores and ultrasonographic findings in all three groups improved after treatment. The mean MEPS in group 2 improved more than groups 1 and 3 at 6 weeks (G1, 56.9>62.4; G2, 54.3>65.0; G3, 55.7>62.6), and more than group 1 at 12 weeks (G1, 56.9>67.9; G2, 54.3>73.6). The mean depth of the common extensor tendon depth (CETD) on ultrasonography in group 2 increased more than groups 1 and 3 at 6 and 12 weeks (6 weeks: G1, 0.385>0.386; G2, 0.332>0.392; G3, 0.334>0.357; 12 weeks: G1, 0.385>0.409; G2, 0.332>0.438; G3, 0.334>0.405 [cm]).Conclusions: PDRN injections combined with EX exhibited a greater improvement in mean MEPS and mean CETD compared to EX only or EX combined with ESWT for LE within the 12 weeks follow-up.

Evaluation of Shoulder Muscle Improvement in Patients Following Free Latissimus Dorsi Muscle Pedicle Flap Transfer

Aim: This study aimed to evaluate the clinical outcomes, shoulder muscle strength, and donor site morbidity following the free latissimus dorsi (LD) muscle pedicle flap transfer. Materials: Patients with free LD muscle pedicle flap reconstructions and with asymptomatic shoulders (affected and contralateral side) were included. The follow-up duration was 12 months. The combined shoulder range of motion (ROM), Constant–Murley shoulder (CMS), and quick disabilities of the arm, shoulder, and hand (QuickDASH) scores were measured preoperatively and at 1 year postoperatively. The ratio of the isokinetic muscle strength and total work was measured with an isokinetic dynamometer (Cybex 350®) both preoperatively and at sixth month postoperatively. Results: Twenty patients with a mean age of 37.06 ± 9.74 years and a mean body mass index of 23.49 ± 8.6 kg/m2 were included. The difference in shoulder ROM and CMS and increase in QuickDASH were not significant at the first postoperative year. The peak torque and total work performed decreased by 13%–16% for the adductor and extensor functions at the six month postoperatively, and these differences were significant. Although the adductor peak torque was significantly lower in the postoperative test of the operated side, no significant difference was found between the operated and unaffected shoulder peak torque values. Moreover, no significant difference was noted between the operated and unaffected shoulders in all isokinetic tests pre- and postoperatively. Conclusion: The free LD muscle pedicle flap harvest did not decrease function and ROM at the first postoperative year. The muscle strength and total work of shoulders after the LD muscle transfer returned to the preoperative condition at the sixth month, except adductor and extensor muscle strengths. However, adductor and extensor muscle strengths of the operated shoulders were not significantly different postoperatively. Level of Evidence: Level IV, Diagnostic study

Assessment of the influence of intermittent ischemic compression of latent trigger points on changes on the range of the lumbar spine mobility and myoelectric changes in the dorsal extensor muscle

Introduction: Pain in the lumbar spine (L) is a very serious health problem. The appearance of pain in the area of the back muscles with palpable small, sensitive points may indicate the presence of myofascial trigger points. There are many techniques used in the therapy of trigger points, including ischemic compression, which gives a therapeutic effect in the form of biomechanical normalization of muscle tissue restoring the normal functional state of a given muscle. Aim of the study: The aim of the study was to assessment of the influence of intermittent ischemic compression of latent trigger points on changes on the range of motion of the L spine and on myoelectric changes in the back extensor muscle. Material and Methods: The study included 32 students who were subjected to a single technique of intermittent ischemic compression according to Chaitow. The participants of the study performed the Thomayer test before and after the therapy to assess the range of spine mobility. The myoelectric changes in the back extensor muscle were assessed using NORAXON's EMG before and after the treatments following a protocol specifically developed for this purpose. The statistical analysis of the data was calculated using the Statistica 13 program. Results: One-time ischemic intermittent compression of the back extensor muscle statistically significantly increased the range of spine motion. The mean value of the tension of the back extensor muscle at rest after the therapy was reduced, showing statistically significant changes. The myoelectric changes in the back extensor muscle during flexion were not statistically significant Conclusions: The results showed the effectiveness of the ischemic intermittent compression technique in increasing the range of spine mobility after the treatment on the back extensor muscle. Intermittent ischemic compression leads to a decrease in the resting tension of the back extensor muscle, without affecting any significant changes during the flexion movement.