Clausen M.B.1,2,3, Merrild M.B.1, Witten A.2, Christensen K.B.4, Zebis M.K.1, Hölmich P.2, Thorborg K.2,3
1Faculty of Health and Technology, Metropolitan University College, Bachelor's Degree Programme in Physiotherapy, Department of Physiotherapy and Occupational Therapy, Copenhagen, Denmark, 2Copenhagen University Hospital, Amager-Hvidovre, Sports Orthopaedic Research Center - Copenhagen, Department of Orthopedic Surgery, Hvidovre, Denmark, 3Copenhagen University Hospital, Amager-Hvidovre, Physical Medicine and Rehabilitation Research-Copenhagen (PMR-C), Copenhagen, Denmark, 4University of Copenhagen, Department of Biostatistics, Copenhagen, Denmark
Background: Patients with Subacromial impingement syndrome (SIS) are characterized by subjective sensation of pain and loss of function. In addition, significantly impaired strength in external rotation (ER-Strength) and abduction (AB-Strength), as well as abduction range of motion (AB-ROM), has been reported, with patients lacking ~50% to reach the levels of the healthy opposite shoulder or healthy controls. Importantly, however, strength improvements are varying (4-42%) in controlled trial-settings, and unknown in real-life practice settings. Furthermore, improvements in objective and subjective impairments might depend on specific rehabilitation parameters, such as the time spent on exercises (Exercise-time), number of physiotherapy sessions (Physio-sessions) and number of corticosteroid injections, respectively. However, this has not previously been investigated.
Purpose: The purpose of this study was, 1) to describe changes in ER-Strength, AB-strength, AB-ROM, patient-reported function and pain, and 2) to explore the association between changes in subjective and objective outcomes and specific rehabilitation parameters, in conservatively treated SIS-patients.
Methods: Patients diagnosed with SIS at initial assessment at an outpatient hospital clinic using predefined criterias, who had not undergone surgery when contacted after 6-8 months, were invited to a follow-up testing session. This included testing of AB-ROM, ER-Strength and AB-Strength, pain during each test (NRS:0-10), Shoulder Pain and Disability Index (SPADI: 0-100) and average pain (NRS:0-10), outcomes which were also collected at baseline. Rehabilitation parameters (amount of Physio-sessions, corticosteroid injection and Exercise-time) were recorded from a standardized telephone-interview at follow-up. Changes in outcomes were analyzed using Wilcoxon Signed-Rank test, and the corresponding effect sizes (ES) were estimated. The associations between changes in outcomes and rehabilitation parameters were explored using multiple regression analyses, including the baseline score of the relevant outcome as covariate. A significance level of 0.05 was applied.
Results: Sixty-three of the 98 conservatively treated SIS-patients reached by telephone 6-8 months after baseline completed both baseline and follow-up testing. Significant improvements were seen in SPADI (19 points, ES:0.53, p 0.001) and all pain variables (median 1-1.5 points, ES:0.26-0.39, p 0.01), but not in AB-ROM, ER-Strength and AB-Strength (ES:0.9-0.12, p>0.2). A higher number of Physio-sessions was significantly associated with larger improvements in ER-Strength (0.6 Newton/session, p=0.048), and higher Exercise-time was significantly associated with decrease in average pain (-0.2 points/1000min., p=0.048).
Conclusion(s): Medium to large effect sizes were seen for improvements in subjective outcomes of function and pain 6-8 months following initial assessment, in conservatively treated SIS-patients. Surprisingly, strength and ROM did not improve. Two significant associations were identified between self-reported specific rehabilitation parameters and outcomes. However, the small gains per Physio-session or 1000 min of Exercise-time reduces the clinical relevance of these relationships. Collectively, these findings challenge the effectiveness of current rehabilitation, on objective clinical outcomes such as strength and ROM. Future research should evaluate the importance of various rehabilitation parameters and the relevance of improving strength and ROM outcomes in these patients.
Implications: The findings from the current study suggest that physiotherapist should pay extra attention to the progression of objective strength and ROM outcomes, when these outcomes are believed to be relevant to the rehabilitation of the patient.
Funding acknowledgements: The study was funded by the Metropolitan University College; SORC-C, Department of Orthopedic Surgery, Copenhagen University Hospital and Praksisfonden.
Topic: Musculoskeletal: upper limb
Ethics approval: The Capitol Region Committee on Health Research Ethics in Denmark, did not consider the project to be notifiable (H-3-2013-FSP29).
All authors, affiliations and abstracts have been published as submitted.
