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Abstract
Objectives Treatment for degenerative rotator cuff disease of the shoulder includes physiotherapy. Dynamic humeral centering (DHC) aims at preventing subacromial impingement, which contributes to the disease. The goal of this study was to assess the effectiveness of DHC.
Method 69 patients with shoulder pain and impingement syndrome were prospectively included in a single-centre randomised trial with a 12-month follow-up. Patients and assessor were blinded to the study hypothesis and treatment, respectively. DHC and non-specific mobilisation as control were performed for 6 weeks, in 15 supervised individual outpatient sessions, and patients performed daily home exercises. The planned primary outcome was the Constant score including subscores for pain, activity, mobility and strength at 3 months. Secondary outcomes were the Constant score and subscores at 12 months, and medication use for pain at 3 and 12 months.
Results The DHC group did not differ from the control group in the total Constant score at 3 months. However, the DHC group showed a higher Constant subscore for pain (12.2 (SD 2.8) vs 9.9 (2.9), least square means difference 2.1, 95% CI 0.7 to 3.5, p=0.004). At 3 months, the DHC group also showed a higher rate of no medication use (96.7% vs 71%, proportional difference 25.7, 95% CI 3.7 to 51.9, p=0.012). There was no other intergroup difference.
Conclusions There was no difference in the total Constant score between DHC and controls. However, pain was improved at 3 months after DHC. The differences found in subscores for pain should be explored in future studies.
Trial registration clinicaltrials.gov Identifier: NCT 01022775.
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Shoulder disorders are frequent in the adult population.1,–,3 Approximately 2% of patients consult for shoulder disorders in primary care.4 5 Shoulder disorders also account for up to 10% of all referrals to physiotherapists.6 Chronic shoulder pain can be attributed to non-specific conditions, muscular causes, degenerative cuff disease, adhesive capsulitis, or glenohumeral arthropathic abnormalities.1,–,5 7 Degenerative rotator cuff disease is the main cause of chronic shoulder pain in general practice8 and in rheumatology clinics.9 Degenerative rotator cuff disease is also of concern in the working population. Systematic surveys indicate that it is the leading upper-limb musculoskeletal disorder and greatly contributes to occupational disability.10 11
The pathogenesis of rotator cuff disorders involves tendon impingement and intrinsic tendinopathic abnormality.12 Some of the anatomopathological features of the disease are thought to occur naturally with ageing.13 Degenerative changes of the rotator cuff including tears are found in asymptomatic populations, with the prevalence increasing over time.14,–,19 Degenerative rotator cuff disease can generate pain, weakness and active mobility restriction of the shoulder.7 Passive mobility is generally preserved compared with capsulitis and glenohumeral arthropathy.20 Pain in the natural history of degenerative rotator cuff disease may be explained by subacromial bursitis, peritendinous inflammation and progressive tearing.13 Weakness is associated with tendinous tearing and fatty muscle degeneration.
The first-line recommended treatment for degenerative rotator cuff disease is conservative and includes levels 1 and 2 oral analgesics; a short sequence of non-steroidal anti-inflammatory drugs (NSAID), if necessary; local injection of corticosteroids and physiotherapy.20 Different modalities of physiotherapy have been proposed. They mainly consist of shoulder mobilisation, muscle stretching and muscle strengthening. Dynamic humeral centering (DHC) consists of a selective solicitation of depressors of the humeral head, pectoralis major and latissimus dorsi during active abduction of the arm in the scapular plane.21 22 DHC can therefore be considered as specifically adapted to an impingement mechanism that contributes to degenerative rotator cuff disease. Despite its rationale, little evidence exists of its effectiveness in degenerative rotator cuff disease. A three-dimensional analysis suggested an improvement of joint stability.23 One retrospective study described short-term clinical improvement with DHC in patients with rotator cuff tear.24
We aimed to assess the effectiveness of DHC in degenerative rotator cuff disease with impingement syndrome in a randomised clinical trial. Our hypothesis was that DHC prevents subacromial impingement and provides clinical improvement in patients with such a condition. The therapeutic effect of physiotherapy for musculoskeletal diseases is multifactorial, involving specific effects and regular contact with the physiotherapist, the beliefs of the patient and the therapeutic environment.25 We therefore used a non-specific mobilisation programme as a control to assess the effect of DHC on the basis of its aetiological mechanism of action. We considered that non-specific mobilisation that we used as control has no effect on subacromial impingement. Lowering the humeral head was indeed not sought during non-specific mobilisation.
Methods
Design
The study was a prospective single-centre randomised controlled trial with blinded patients and assessor (figure 1). It involved a 6-week intervention and a 1-year follow-up.
Study flow diagram.
Participants
Patients with pain originating from the shoulder were assessed during consultation and were considered for inclusion by the same assessor (JB). Criteria for inclusion were age greater than 30 years; pain duration longer than 1 month; the presence of at least two positive impingement test results from Neer, Yocum and Hawkins testing;26 and a total Constant score less than 80.27 28 Patients with the following shoulder conditions were excluded: reduced passive range of motion, anteroposterior instability, tendinous calcification, corticosteroid injection within the previous 30 days, previous surgery, humeral fracture, inflammatory joint disease and neoplastic disorders.
Randomisation and allocation
Following the clinical screening, patients meeting the inclusion criteria and accepted as participants underwent random assignment. Patients were assigned in permuted blocks of six to either DHC or non-specific mobilisation treatment. Allocations were sealed in opaque and consecutively numbered envelopes. Envelopes were opened by an independent investigator who was not involved in the eligibility assessment, outcome assessment or treatment. Allocation was revealed to the physiotherapist before the patients presented for treatment. Two musculoskeletal physiotherapists in our unit were involved in the study. If both were available at the time of patient inclusion, patients were also assigned in permuted blocks of six to either physiotherapist 1 or physiotherapist 2, to undergo the allocated treatment. If only one physiotherapist was available, patients were directly assigned to this one. Each of the two physiotherapists involved in the study performed both treatment programmes, and the same physiotherapist therefore treated both groups of patients.
Interventions
Both musculoskeletal physiotherapists had received education and training in the control and DHC treatments. These treatments were standardised (see supplementary information, available online only). Treatment involved individual outpatient sessions lasting 30 min, three times a week for the first 3 weeks, and twice a week for the next 3 weeks. Each session began with a 10 min massage of the neck and shoulder region with the patient lying on one side or sitting. Physiotherapists were allowed to adjust the intensity of the treatment according to the patient's capabilities. At the end of each session, the physiotherapist recorded the content of the session and the stage of the technical progression to ensure compliance with the standardised procedure. Patients also performed exercises at home depending on the intervention group. Patients recorded home exercises in a logbook, which was assessed at each follow-up visit. Adherence was expressed as the percentage of physiotherapy sessions effectively completed and the percentage of days of home exercises. Patients recorded co-interventions, including medication use for pain and other care, in a logbook for assessment at each follow-up visit. Co-interventions were prescribed by patients’ usual care providers, who were not involved in the trial nor were aware of the study hypothesis.
DHC programme
The DHC programme was divided into two successive parts (see supplementary information, available online only). The first part consisted of learning the lowering of the humeral head during passive abduction of the shoulder. It included muscular control of the scapula, perception of the passive lowering of the humeral head in the glenohumeral joint, active contraction of the pectoralis major and latissimus dorsi, perception of the lowering effect and co-contraction of these muscles during passive abduction of the shoulder. The second part consisted of actively lowering the humeral head by co-contraction of the pectoralis major and latissimus dorsi during active abduction of the shoulder. It was first performed with the elbow in a flexed position at 90°, from 0° to 90° of shoulder abduction. The active movement with the co-contracted pectoralis major and latissimus dorsi was then repeated with the elbow in an extended position, covering the entire range of shoulder abduction without and then with the patient holding a 0.5 kg weight. Home exercises consisted of 10 co-contractions of the pectoralis major and latissimus dorsi three times a day, the shoulder actively positioned in abduction and the elbow in the flexed or extended position according to the stage of progression.
Control programme
The control programme was divided into three parts (see supplementary information, available online only). The first part consisted of passive mobilisation of the shoulder with a painless range of motion. Home exercises were at this stage 10 pendular movements of the shoulder three times a day. The next part consisted of active mobilisation of the shoulder with a painless range of motion. The home exercises were then 10 active anterior elevations of the shoulder in the lateral rotated position three times a day. The final part included active mobilisation of the shoulder performed with slight manual resistance applied by the physiotherapist along with the second part of the home exercises.
Blinding
Patients were informed that two treatment procedures were being evaluated, with no further information on the superiority of one treatment over the other. Patients were therefore blinded to the study hypothesis. An assessor blinded to treatment assessed all outcomes. Participants were requested to refrain from discussing their physical treatment with the outcome assessor.
Outcomes
Evaluations were carried out immediately before treatment, and at 3 and 12 months after the beginning of treatment. Evaluations included the 0–100-point Constant scale27 28 with the subscales for pain (0–15 points), activity (0–20 points), mobility (0–40 points) and strength (0–25 points), and analgesic and NSAID use. For the Constant scale and subscales, zero value indicates the highest impairment. Analgesic or NSAID use was considered if patients used more than one-third of the daily maximal dosage. Medication use was expressed as the number and percentage of patients requiring such treatment or not. The planned primary outcome of the trial was the Constant score including subscores for pain, activity, mobility and strength at 3 months. Secondary outcomes were the Constant score and subscores for pain, activity, mobility and strength at 12 months, and medication use at 3 and 12 months.
Statistical analysis
For sample size calculation, the two-sided significance level was set at 5%, and the power was 80%. The Constant score SD was 15 according to our experience of the scale in non-included patients with rotator cuff disease (SD 14.2, n=26). We required 35 patients in each group to detect a 10-point difference in the Constant score. We used an intent-to-treat analysis. For continuous variables, missing data were replaced by the multiple imputation method.29 Comparisons between groups involved parametric or non-parametric analysis of covariance with the baseline value of the parameter used as a covariate. A sensitivity analysis without any imputation was secondarily performed. For categorical variables, comparisons involved the use of the χ2 or Fisher's exact test. Least square means differences and corresponding 95% CI were reported for each comparison of continuous variables. Proportion differences and their corresponding 95% CI, or the exact CI when the Fisher's exact test was used, were reported for each comparison of categorical variables. We used the Simes procedure for multiple comparisons.30 We considered the 3 and 12-month data, and adjusted for multiplicity based on six comparisons. All analyses involved the use of SAS v9.2.
Results
Flow of patients through the trial and baseline characteristics
The trial was conducted from 30 April 2001 to 26 February 2007. In total, 149 patients were assessed for inclusion (figure 1). Of these, 70 patients were selected and randomly assigned to receive DHC or control treatment. One patient with a Constant total score greater than 80 was excluded. A total of 34 patients underwent DHC and 35 control treatment. At 3 months, 90% of included patients were available for assessment, and at 12 months 70%. The two groups did not differ statistically in baseline characteristics (table 1).
Baseline characteristics of the study population undergoing DHC or control programme
Physiotherapists and treatment distribution
Depending on their availability or the randomisation procedure, each of the two physiotherapists treated 24 and 45 patients, respectively. The treatment groups did not differ in distribution by physiotherapist: one physiotherapist treated 12 patients in each group, and the other treated 22 patients in the DHC group and 23 patients in the control group. The median percentage of supervised sessions completed per patient was 100% (IQR 93–100) for the DHC group and 100% (88–100) for controls. The median percentage of days of home exercises for the DHC and control groups was 32% (0–54) and 59% (30–78) at 3 months, and 9% (0–36) and 14% (0–40) at 1 year, respectively. The two groups did not differ in the percentage of supervised sessions or the percentage of days with home exercises. One patient in each group received one local injection of corticosteroids. No patient underwent complementary physiotherapy or surgical procedure during follow-up.
3-Month assessment
The two treatment groups did not differ in the Constant total score at 3 months (63.8 (SD 16.9) vs 54.0 (19.8), least square means difference 7.2, 95% CI −1.1 to 15.5, DHC group vs control group, p=0.09) (table 2). However, the Constant subscore for pain at 3 months was higher for the DHC group than the control group (12.2 (2.8) vs 9.9 (2.9), least square means difference 2.1, 95% CI 0.7 to 3.5, p=0.004). Furthermore, the DHC group had a higher rate of patients not using medications at 3 months than did the controls (96.7% vs 71%, proportional difference 25.7, 95% CI 3.7 to 51.9, p=0.012), so the rate of patients using medications for this group was therefore lower than that for controls. The two groups did not differ in the Constant subscores for activity, mobility and strength.
Results of DHC and control programme
12-Month assessment
A trend towards higher Constant subscores for pain in the DHC group than in the control group was observed at 12 months (13.1 (2.0) vs 10.8 (3.7), least square means difference 2, 95% CI 0.4 to 3.5, p=0.012). However, it did not reach statistical significance after adjustment for multiplicity. The two groups did not differ in other outcomes at 12 months.
Sensitivity analysis
The sensitivity analysis without any imputation reinforced the improvement of the Constant subscore for pain after DHC at 3 months (least square means difference 2.2, 95% CI 0.7 to 3.6, p=0.005).
Discussion
This study is the first randomised clinical trial to assess DHC specifically in impingement syndrome. We found no significant effect of DHC compared with non-specific mobilisation on the Constant total score at 3 months. However, DHC improved the Constant subscore for pain and decreased medication use at 3 months. The difference in pain with controls reached 20% and should be of clinical relevance.31 Therefore, we show a specific effect on pain of DHC in impingement syndrome. DHC could be useful in association with other physiotherapeutic approaches aiming at mobilisation, strengthening and functional improvement.
Few data exist on the effectiveness of DHC for degenerative rotator cuff disease. DHC has been proposed to prevent subacromial impingement of rotator cuff tendons during active abduction of the shoulder.21 22 The pectoralis major and latissimus dorsi are depressors of the humeral head and contribute to glenohumeral stability.32 DHC consists of early activation of the pectoralis major and latissimus dorsi during shoulder abduction.21 22 A three-dimensional analysis of abduction of the shoulder in patients with rotator cuff tears demonstrated reduced displacement of the rotation centre of the shoulder after DHC.23 One retrospective study described clinical improvement during a 4-month follow-up in patients with a full-thickness tear of the rotator cuff after DHC.24
Because randomised trials of physiotherapy for shoulder pain have not specifically assessed DHC, we have limited comparative data. In contrast to our control treatment, that of most other studies was not an exercise programme.33,–,40 A few studies suggested that manual therapy plus exercises is more effective than exercises alone,41 and that supervised exercises are more effective than home exercises.42 However, they did not show any difference between customised and standard programmes.43 An exercise programme for impingement syndrome was first evaluated by a randomised controlled trial with a three-group design.33 Exercises were compared by arthroscopic subacromial decompression and placebo laser. Exercises involved strengthening, with gradual resistance. They were performed with a physiotherapist's supervision two times a week and at home daily. The training continued for 3–6 months, and placebo laser was performed only during 12 sessions for 6 weeks. Both active treatment groups showed similar improvement in terms of pain score and success rate at 6-month and 2.5-year follow-up, as compared with placebo laser. Subsequently, subacromial decompression has not been found to be superior to physiotherapy for impingement syndrome.37 38 Standardised manual therapy and home exercises reduced pain and disability as compared with placebo at 22-week follow-up but not at earlier assessment.40 The short-term effectiveness of exercises as compared with no intervention has been demonstrated.35 36 39 Supervised stretching, strengthening and scapulohumeral rhythm exercises produced improvement after 1 month in terms of function, range of motion with pain-free abduction and flexion, as well as self-perception of improvement, in patients with non-specific shoulder pain.34 Progressive resistance training that was also supervised produced improvement in terms of pain score and function after 2 months in patients with impingement syndrome.38 Positive results at 3 months for pain, disability and satisfaction in patients with impingement syndrome were reported for a home programme of six repeated exercises of stretching and progressive strengthening.36
The strength of our study lies in several points currently emphasised in quality assessment of non-pharmacological trials.44 45 We have defined the selection of the study population, the modalities of the randomisation and allocation to treatment and the description and application of standardised physiotherapy programmes. We randomly assigned patients to treatment and also randomly assigned physiotherapists. Each of the two physiotherapists involved in the study therefore performed both programmes. Previous studies did not use this procedure. The control we chose included supervised and home exercises. Both conditions, randomly assigned physiotherapists and exercises as control, allowed for direct assessment of DHC, excluding non-specific effects that could have been induced by contact with the physiotherapist, beliefs of the patient and the environment.25 Patients and the assessor were blinded to the study hypothesis and treatments, respectively. Co-interventions were recorded and considered for assessment. Finally, few randomised clinical trials of physiotherapy in rotator cuff disease have included the long-term follow-up of our study.34 37 38 However due to the rate of patients lost to follow-up, the results we showed at 12 months should be considered with caution.
Our trial also has other limitations. Physiotherapists were not blinded to treatment. Therefore, the effect of their beliefs about the treatments they performed cannot be excluded. However, physiotherapists were instructed to apply standardised programmes strictly. As both groups showed marked improvement over time, the effect of the beliefs of the physiotherapists was probably marginal. Patients were requested to refrain from discussing their physical treatment with the outcome assessor, but this point has not been controlled. The control programme we used was an active treatment and not a placebo. This may have contributed to underestimate the effect of DHC. As a result of its reliability, the Constant scale we chose as an outcome may also be involved in this underestimation.46 Because of the flow of patients through the trial, the inclusion period was long. Explanations are likely the single centre design, the size of the medical network we used for the recruitment of patients and the absence of public communication about the study. However, this length does not appear to have affected the quality of the trial. Indeed, the experimental procedure was regularly checked and remained the same over time. Despite our sample size calculation and because of patients lost to follow-up, the trial may have lacked power, which may explain the differing results in outcomes. Finally, included patients had to have positive test results from at least two clinical impingement tests, and they have been treated by experienced musculoskeletal physiotherapists in a single centre. Therefore, our results may not be applicable to an unselected population with shoulder pain. The development of training courses for shoulder pain diagnosis and DHC appear to be necessary.
In summary, we report on the clinical effects of a DHC programme for patients with impingement syndrome at 3 and 12-month follow-up compared with a non-specific mobilisation programme. The main conclusion is that there was no difference in the Constant total scores, but that pain was improved after DHC. DHC may help achieve alleviation of shoulder pain in impingement syndrome. DHC could be useful in physiotherapy for the syndrome, especially because of the pathogenic involvement of subacromial impingement in degenerative rotator cuff disease. Further studies are, however, necessary to explore the difference in subscores for pain.
Acknowledgments
Drs Serge Poiraudeau and Michel Revel contributed to the standardisation of physiotherapy programmes. Laura Heraty participated as a medical editor in the final version of the manuscript.
References
Supplementary materials
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Footnotes
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Funding Assistance Publique–Hôpitaux de Paris and the French Society of Rheumatology funded the study. Assistance Publique–Hôpitaux de Paris and the French Society of Rheumatology played no role in each of the following: design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript. Grant support: Contrat de Recherche et d'Innovation Clinique (CRIC) from Assistance Publique–Hôpitaux de Paris (CRC 99241, P000203). Grant from the French Society of Rheumatology.
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Competing interests None.
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Patient consent Obtained.
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Ethics approval This study was conducted with the approval of the CCPPRB Groupe Hospitalo-Universitaire Pitié-Salpêtrière, Paris, France.
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Provenance and peer review Not commissioned; externally peer reviewed.