Shoulder proprioception gives information regarding arm joint position and movement direction. Several studies have investigated shoulder proprioceptive acuity in patients with subacromial impingement syndrome (SIS); however, differences in protocols and between-subjects designs have limited scientific inferences regarding proprioception and SIS. We aimed to determine within-subject differences in shoulder and elbow proprioceptive acuity in 17 patients with stage 2 SIS following treatment of a local anesthetic injection. In addition, we used 17 healthy, age-, sex-, and arm dominance–matched controls to determine the magnitude of differences after treatment. Joint position sense (JPS) was measured before and after treatment in both groups in the sagittal plane for the shoulder and elbow. Our results indicate that patients with SIS have less sensitivity to angular position and tended to overshoot their targets with greater variability during angle-matching tasks for the shoulder (1.8° difference, P = .042) and elbow (5.6° difference, P = .001) than controls. The disparities in JPS found in patients with SIS were not resolved following subacromial injection; in fact, the magnitude of the errors increased after treatment where postinjection errors were significantly greater (P = .046) than controls, with an average difference of 2.4°. These findings suggest that patients with SIS have decrements in either the signaling or processing of proprioceptive information and may use pain to reduce these inequalities.

AIMTo investigate proprioceptive discrepancies in the lower extremity in persons with type 2 diabetes mellitus (T2DM).METHODSIn this cross-sectional study, a total of 46 older persons were divided into a T2DM group (n = 23) and a control group who did not have T2DM (n = 23). Participants were given a brief warm up with stretching exercises. Diabetic neuropathy scores were collected prior to proprioceptive testing. For proprioceptive testing, participants performed leg extensions to randomized target positions of 15°, 30°, 45, 60° degrees of elevation in the sagittal plane, each target was repeated a total of four times. Subjects were guided to target positions in the absence of visual feedback via auditory cues from a custom JPS application. When the participant entered the target position, they memorized the location of their limb in space and subsequently attempted to re-locate this position in space. Proprioceptive errors were measured from the target positioned, target remembered, target repositioned protocol.RESULTSProprioceptive accuracy was lower in the diabetic group at all levels of target angle than the control group (P < 0.05). The diabetic group had 46% greater inaccuracy than the control group at all levels of target position. Diabetics also reported greater neuropathy scores than controls in the past 12 mo P < 0.01.CONCLUSIONDeficits in lower limb localization and greater diabetic neuropathy scores were identified in this study. Our findings may be associated with deafferentation as peripheral neuropathy is a common complication with the disease. These findings may help to explain the declining balance function in the older persons with T2DM which is also commonly reported.

In this study, we aimed to determine if electromyography (EMG) normalization to maximal voluntary isometric contractions (MVIC) was influenced by subacromial pain in patients with subacromial impingement syndrome. Patients performed MVICs in unique testing positions for each shoulder muscle tested before and after subacromial injection of local anesthetic. In addition to collection of MVIC data, EMG data during an arm elevation task were recorded before and after injection. From a visual analog pain scale, patients had a 64% decrease in pain following the injection. Significant increases in MVICs were noted in 4 of the 7 shoulder muscles tested: anterior, middle and posterior deltoid, and lower trapezius. No significant differences were noticed for the upper trapezius, latissimus dorsi, or serratus anterior. MVIC condition (pre and post injection) had a significant influence on EMG normalization for the anterior deltoid and lower trapezius muscle. Results indicate that subacromial pain can influence shoulder muscle activity, especially for the deltoid muscles and lower trapezius. In addition, normalization to MVIC in the presence of pain can have unpredictable results. Caution should be taken when normalizing EMG data to MVIC in the presence of pain.

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