Abstract
Abstract
Background: Subacromial shoulder pain is a common cause of pain in patients with shoulder complaints. Changes in scapular rotations, termed scapular dyskinesis, have been hypothesized to contribute to the etiology and maintenance of subacromial shoulder pain. The overall aim of this thesis was to add towards understanding of the potential role of scapular dyskinesis in the recovery of subacromial shoulder pain. For this purpose, we assessed: 1) the changes in pain and function scores over time in patients with subacromial shoulder pain; 2) the association between changes in pain or function scores and changes in scapular dyskinesis; and 3) the feasibility of conducting a randomized control trial (RCT) to compare the efficacy of tailored training program with standardized exercise program on improving pain, function and scapular dyskinesis in patients with subacromial shoulder pain.
Methods and results: A systematic review and meta-analysis (Study 1) was conducted to assess the clinical course of pain and function in patients with subacromial shoulder pain who received ‘no intervention’ and ‘usual care’. The results showed patients with ‘no intervention’ reported no changes in pain and function scores over 3 months (maximum follow-up was to 3 months) and patients receiving ‘usual care’ reported an average 30 scores improvement (score ranging from 0 to 100) in pain and function at 12 months with 40% of that improvement occurring in the first 6 weeks from the study entry (maximum follow-up was to 12 months).
Next, the association between changes in pain or function scores was assessed with changes in scapular dyskinesis. For conducting this, first, a laboratory-based study assessed the intra-rater between-day reliability of scapular locator for measuring scapular rotations during scapular plane arm elevation in asymptomatic individuals (Study 2). Findings suggested that the scapular locator has a good to excellent reliability for measuring scapular upward/downward rotation and anterior/posterior tilt (ICC ranging from 0.73 to 0.93) of arm at 60, 90 and 120 arm elevation and a poor reliability for measuring scapular internal/external rotation (ICC ranging 0.37 to 0.62). The results also indicated a poor reliability for measuring all scapular rotations at 30 of arm elevation (ICC = 0.10 to 0.40). The findings of this study supported the use of the scapular locator for measuring scapular upward/downward rotation and anterior/posterior tilt in the subsequent observational study. The observational study assessed the association between changes in pain or function scores with changes in scapular rotations (measured with scapular locator and scapular dyskinesis test) in patients with subacromial shoulder pain, over an 8-week period (Study 3). The results showed changes in pain or function scores are not associated with changes in scapular rotations.
Finally, a feasibility RCT (Study 4) assessed the feasibility of conducting a full RCT to investigate the efficacy of a tailored training program compared with a standardized exercise program in participants with subacromial shoulder pain. Twenty-eight participants with subacromial shoulder pain (aged 18-65 years) were recruited during 41 weeks and were randomly allocated to tailored training (N=13) or standardized exercise (N=15) programs for 8 weeks. Participants in each group were assessed for pain, function and scapular dyskinesis at week 4 and 8 from baseline. The findings showed that it is feasible to conduct a full RCT with the recruitment rate of 3 participants per month, the proportion of eligible participants per participants screened was 23%. The adherence rate was 86.6% for physiotherapist-delivered interventions and 93.1% for home-based exercises. The drop-out rate was 14% (4 participants out of 28 enrolled). The preliminary analysis suggested significant improvements in pain, function in both groups and significant improvement in scapular dyskinesis in the tailored training group. No between-group differences were observed in above outcome measures at 4 and 8 weeks. Based on between-group mean differences in pain and considering a 20% drop-out rate, a total of 88 participants (44 participants in each group) are required for conducting a full RCT.
Conclusion This thesis provided a summary of expected changes in pain and function over time for patients receiving ‘no intervention’ or ‘usual care’. These findings could be used as a reference for future researchers when designing new studies or by clinicians when managing patients. Our findings on the association between changes in pain or function with scapular rotations did not support the contributing role of scapular dyskinesis in subacromial shoulder pain. However, further studies are required to confirm our findings given challenges with scapular measurements. We also suggest assessing whether other factors (e.g., age, shoulder pain duration, physical functioning, and comorbidity) may be confounding variables when assessing the association between scapular dyskinesis and subacromial shoulder pain. Findings from the feasibility RCT suggested it is possible to conduct a full RCT. The full RCT will explore whether a tailored training program leads to better clinical outcomes (e.g. pain, function and scapular dyskinesis) when compared with a standardized exercise program.