An Investigation of Maximal Strength of the Upper Limb Bilaterally in Individuals With Lateral Elbow Tendinopathy: A Systematic Review With Meta-Analysis

Abstract

The aim of this study was to investigate whether there is evidence of bilateral upper limb strength deficits in individuals with unilateral lateral elbow tendinopathy (LET). The electronic databases Medline via Ovid, PubMed, and Scopus were searched from inception to March 2020. Included studies encompassed maximal strength outcomes of any upper limb and appendicular musculature in individuals with LET and an asymptomatic comparator. Study quality was rated using a modified version of the Epidemiological Appraisal Instrument. Hedges g effect sizes (ES) and 95% CIs were calculated for comparisons of maximal strength in the LET group and an asymptomatic control group. Meta-analysis using a random-effects model was performed when possible. Fourteen studies were included. Quality appraisal resulted in a mean Epidemiological Appraisal Instrument score of 46% (SD = 10%). Meta-analysis revealed strength deficits in shoulder abduction (pooled ES = -0.37 [95% CI = -0.62 to -0.12]) and shoulder external rotation (pooled ES = -0.55 [95% CI = -0.83 to -0.28]) of the symptomatic limb compared with an asymptomatic control group. Meta-analysis also revealed maximal strength deficits in the upper trapezius (pooled ES = -0.26 [95% CI = -0.49 to -0.02]) of the asymptomatic limb compared with an asymptomatic control group. There was also consistent evidence for strength deficits in the serratus anterior, lower trapezius, and wrist extensor muscles and deficits in grip strength of the symptomatic limb as well as strength deficits in the wrist extensor muscles of the asymptomatic limb in individuals with unilateral LET. In individuals with LET, there were maximal strength deficits in shoulder abduction, shoulder external rotation, serratus anterior and lower trapezius muscles, and wrist extension, as well as deficits in grip strength of the symptomatic limb compared with an asymptomatic control group. In addition, there appeared to be strength deficits in the upper trapezius muscle, wrist extension, and metacarpophalangeal joint flexion and extension, as well as deficits in grip strength of the asymptomatic limb in individuals with LET compared with an asymptomatic control group. These results suggest bilateral strength deficits. These findings highlight the importance of a thorough physical examination and appropriate strengthening intervention for the upper limb with a focus on shoulder and scapular stabilizers, in addition to forearm muscles, in individuals with LET. In people with tennis elbow, widespread strength deficits, including weakness of the shoulder, forearm, and wrist muscles, may exist. Interestingly, some of these weaknesses appear on both the affected and the unaffected sides in people with tennis elbow. A physical therapist can help strengthen these areas.