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.

Standard and Short RoM Isokinetic Testing: Comparative Analysis in Identifying Submaximal Shoulder External Rotator Effort.

An isokinetic-related parameter termed the difference between eccentric-concentric strength ratios at two distinct test velocities (DEC) based on 60° (standard) range of motion (RoM) has been proven to be highly efficient detecting feigned muscular efforts. This study aimed to verify whether a DEC derived from a much shorter test RoM (20°) was equally useful than a long RoM-derived one. Eighteen healthy men (32.4 ± 6.4 years old) took part in a study focusing on shoulder external rotation isokinetic strength. Participants performed a genuine shoulder external rotator maximal effort (eight pairs of concentric and eccentric contractions at high and low velocities at short and long RoM) and then instructed to feign maximal effort. Contraction velocities were adjusted accordingly by applying a 1:4 gradient and peak moments registered. Both condition DEC was then calculated by subtracting the eccentric and concentric strength ratios at low velocities from those at high velocities. DEC scores in the feigned effort were significantly higher than maximal effort ones in both conditions in men. It enabled the setting of specific cutoff levels for separating the efforts. Both approaches revealed a coincident sensitivity (78%) whereas short RoM showed an even higher specificity: 88% versus 78%. Thus, the short RoM protocol provides clinically acceptable detection power.

Maximality of shoulder external rotation effort in patients presenting with work related injury: the clinical applicability of the DEC parameter.

The aim of the present study is to examine the applicability of the isokinetic DEC parameter for identifying submaximal effort in workers with potential weakness of the shoulder external rotators. A previous study indicated that the DEC was a powerful identifier of submaximal effort of shoulder external rotation in normal volunteers. Its applicability in shoulder injury patients is of specific interest. Thus, a retrospective study of 74 (33 female and 41 male) patients who claimed compensation for work-related shoulder injury was designed. 52 patients had their injured side DEC values within the normal range and were thus labeled as maximal performers. Ten patients had higher than cutoff DEC values, indicating submaximal effort whereas 12 patients had exceedingly low DEC values. Gender comparison showed a significantly different proportion of maximal performers. Strength deficits registered in patients demonstrating maximal performance correlated with the final outcome. The findings support the application of the DEC for determination of the extent of weakness of shoulder external rotators in male patients. In terms of shoulder external rotators status in male worker injury, the results support the application of isokinetic tests both in the clinical and medicolegal sense. However, the gender discrepancy warrants further research.

Suspected feigned knee extensor weakness: usefulness of 3D gait analysis. Case report.

The purpose of the present case report is to show the potential for use of 3D gait analysis as an assessment method of feigned muscle weakness. We describe a patient complaining of right leg pain and weakness. Physical examination showed severe quadriceps muscle weakness in a highly abnormal gait pattern context. Conventional diagnostic workup did not show any relevant findings. Three-dimensional (3D) gait analysis was performed with a 3D motion capture system. Joint angles, internal moments and powers were computed from the motion data. Lower leg muscle surface-electromyography was also performed. During the late stance phase, flexor moment and negative power peaks (indicating eccentric knee extensor activity) were generated in the knee, together with relevant Rectus femoris activity. All findings were highly inconsistent with true quadriceps weakness and gave objective ground to suspect insincerity of patient complaints. 3D gait analysis might be a valuable clinical assessment tool in suspected feigned lower limb muscle weakness.