Wrist flexion and extension strength in patients with work-related chronic elbow pain: the isokinetic effort factor and its implications

Background: The validity of isokinetic strength findings relating to forearm muscles in patients with chronic elbow pain and/or epicondylitis is not well established. Furthermore, given the nature of this disorder, ensuring maximal effort in performing the tests is an essential prerequisite. The isokinetic-based DEC parameter (defined as the difference between high-and low-velocity eccentric-to-concentric ratios of a given muscle) has been shown to efficiently detect maximal effort. The purpose of this study was therefore to assess the validity of isokinetic strength tests in patients with chronic elbow pain and/or epicondylitis. Methods: A cohort consisting of 44 male patients with chronic elbow pain (average evolution time, 262 +/- 193.04 days) was recruited. The wrist extensor and flexor concentric and eccentric isokinetic strength of the involved and uninvolved sides was measured. The involved-uninvolved and flexor-extensor (F/E) ratios, as well as the DEC (eccentric-concentric difference), were computed based on peak moment values. Work disability and relapse within the first year were registered. In maximal performers, associations between deficits, F/E ratios, work disability, and symptom relapse were explored applying multiple comparisons. Results: Of the patients, 68.2% met the maximal-effort criteria, with the involved-side muscles being significantly weaker than their uninvolved-side counterparts in most cases. Although the mean deficit in this group was not associated with either work disability or relapse, patients with a relapse of symptoms within the first year had a significantly higher F/E ratio than those without relapse. Conclusion: In patients presenting with chronic elbow pain who perform at the maximal level of effort, high wrist F/E strength ratios may predict symptom relapse. (C) 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.