Introduction

Rotator Cuff-Related Shoulder Pain (RCRSP) accounts for up to 85% of all painful musculoskeletal shoulder conditions and is frequently encountered in physiotherapy practice. Recovery can take several months, and since it affects people through pain and restricted movements, it has a significant impact on their daily lives. Recovery rates are suboptimal, with only 60-65% of people reporting recovery after six months. Exercise is a widely recommended treatment option, but improvements seem modest compared to the natural history of the condition. (Dickinson et al. 2019) Therefore, ways to accelerate recovery are being looked for. One possible way to speed up recovery is the addition of mobilization with movement in RCRSP. Especially since RCRSP affects movement, the rationale of adding mobilizations with movement lies in helping people improve active motion. The current study compared real and sham mobilizations added on top of an active exercise program.

Methods

Eligible participants were people with unilateral atraumatic shoulder pain lasting for more than 6 weeks. They had to be between 18 and 65 and referred by a shoulder specialist with a diagnosis of rotator cuff injury (tendinitis or tendinosis), subacromial impingement syndrome, subacromial pain, or bursitis.

A positive test on at least 3 of the following cluster of tests was necessary:

• Hawkins-Kennedy test
• Neer test
• Painful arc test
• Empty/Full can test
• Resisted external rotation

The following interventions were delivered.

The participants in the experimental group chose one functionally relevant shoulder movement they struggled with. With the assistance of the physiotherapist, one out of four joints (cervical, thoracic, scapulothoracic, glenohumeral or acromioclavicular) was chosen to apply the mobilization with movement to. The positioning could be in standing, sitting or lying. Based on the assessments, one technique was chosen that best improved the active range of the patients’ relevant shoulder movement.

The same protocol was followed in the control group, but the mobilization with movement was a sham procedure.

Both groups participated in shoulder exercises performed in a standing position:

• Shoulder internal rotation
• Shoulder external rotation
• Forward punch
• Rowing
• Scapular retraction
• Shoulder elevation with co-contraction of the external or internal rotators
• Stretching: anterior and posterior shoulder stretch and hand behind back

The following shoulder exercises were done in a lying position:

• Shoulder flexion in side lying
• Shoulder external rotation in side lying
• Shoulder protraction in supine

The Shoulder Pain and Disability Index (SPADI) was the primary outcome, together with the Numeric Pain Rating Scale assessing pain at rest, at night, and on movement. The outcomes were captured at baseline, after 5 and 9 weeks.

Results

Seventy participants were included and equally randomized to receive either the control treatment of sham mobilization with movement plus exercise or the intervention with real mobilization with movement plus exercise. They were on average 48 years old and about 60% of the sample were women. Their average pain duration was 10 months.

Investigating the primary outcome measure SPADI revealed that after 5 weeks of treatment, a significant between-group difference of 15 points favored the intervention group. Both groups improved but the intervention group receiving exercise plus mobilization with movement in RCRSP had a larger effect. At nine weeks, the between-group differences in SPADI were 9 points, in favor of the intervention group.

Pain at rest reached no statistically significant difference at five or nine weeks. Interestingly, pain at night and pain on movement did. A significant and clinically relevant between-group difference of -2.1 points and -1.9 points on the NRS for pain at night at 5 and 9 weeks respectively indicated a beneficial effect of exercise plus mobilization with movement in RCRSP compared with sham mobilization with movement plus exercise.

For pain on movement, the between-group difference was statistically significant at five weeks, but the difference remained below the threshold of clinically important change.

Questions and thoughts

Exercise plus real mobilization with movement in RCRSP produced a significantly larger beneficial effect compared with sham mobilization and exercise at five weeks. This between-group difference was 15 points, indicating an important difference that exceeded the minimal clinical important difference (MCID). Yet, the confidence interval ranges from -24 to -7, revealing that some participants benefited greatly from the intervention, while others did not reach the threshold for clinically important differences. At week nine, the between-group difference was lower and it was uncertain whether it corresponded to a clinically relevant change.

The same was found for pain at night at five weeks: the between-group difference favored the intervention group with a difference exceeding the MCID. However, at nine weeks, this difference was just not clinically relevant. Here the confidence intervals also indicate that some people greatly benefit from the combination of exercise and mobilization with movement while others report no effects.

Pain on movement did not reach the level of clinically important differences with a between-group difference of -1.5, which is below the commonly accepted threshold of the MCID of -2 points. Again, the confidence intervals at five and nine weeks indicate that some people benefit from the applied intervention.

Subgroup analyses can be important to conduct since the outcome measures reveal important differences for some participants. Finding who will likely benefit from a combination of exercise and mobilization with movement in RCRSP, compared with exercise, might improve individualized care. It is important to note that both groups had clinically relevant improvements over time. In the intervention group, an improvement of 40 points was attained from baseline to 9 weeks and in the control group, a difference of 31 points was achieved. Natural history of the condition of RCRSP could have played a role in the observed improvements but since both groups participated in exercise therapy, it is more likely attributable to the exercise therapy since these people were already suffering from RCRSP for an average of 10 months with no improvements before enrolling in the trial. Therefore, mobilization with movement seems to accelerate the improvements of exercise therapy in the short term of five weeks.

While pain on movement improved for both groups over time, the observed between-group differences were not clinically relevant. While in the intervention group, the pain improved from a mean of 6 points at baseline to a mean of 1.5 at nine weeks, the control group halved the pain scores from baseline (average 6 points) to 3.2 at the end of nine weeks. This difference indicates again that the addition of mobilization with movement to exercise in RCRSP can be important. This was also reflected in the improvement of active shoulder range of movement as seen below. The intervention group achieved a better range of motion after 5 weeks.

Talk nerdy to me

The authors point to the clinical relevance of the results. This study’s primary outcomes were the SPADI and the Numerical Pain Rating Scale. No corrections were made for multiple comparisons, which may limit the conclusions.

For the SPADI, although significant between-group differences of 15 and 9 points were noted at 5 and 9 weeks respectively, the minimal detectable change (MDC) of 18 points (Roy et al., 2009) was not attained. The Minimal Clinical Important Difference (MCID) of the SPADI is reported to range between 8 and 13.2 points. (Roy et al., 2009)

The MCID and MDC are measures of responsiveness of an outcome measure. The responsiveness of an outcome measure is an important construct since it determines whether the outcome measure can accurately capture what is was designed to measure. The concept of a MCID arose to address the shortcomings of statistically significant differences and to determine a difference that is meaningful enough and desirable enough to repeat the intervention if given the option. (Copay et al. 2007) The Minimal Clinical Important Difference (MCID) of the SPADI is reported to range between 8 and 13.2 points. Thus, a change score of 8-13.2 points may be important and noticeable for the patient, but scores up to 18 points (which is the MDC) may reflect measurement errors when the SPADI is repeatedly administered. However, the MDC and MCID can vary depending on the sample size and population in which they were derived, but can also be different based on the calculation methods and time intervals between the administration of the questionnaire. (Riley et al. 2015)

From a statistical point of view, any difference lower than the MDC of 18 points can be the result of random variation and measurement errors. The MDC is the smallest amount of change that is greater than measurement error. Yet, since the MDC is calculated as a statistical threshold and the MCID is based on a patient response-anchored method, the MDC can be higher than the MCID. Since the MDC does not indicate whether a change is clinically relevant to someone, the MCID must be used alongside the MDC. (Beninato and Portney, 2011) 

Take home messages

Combining exercise and mobilization with movement in RCRSP leads to quicker improvements in shoulder pain and disability in the short term of five weeks. After nine weeks, the improvements were less certain: some may experience large and clinically meaningful benefits while others noted no relevant differences.

Reference

Baeske R, Hall T, Dall’Olmo RR, Silva MF. In people with shoulder pain, mobilisation with movement and exercise improves function and pain more than sham mobilisation with movement and exercise: a randomised trial. J Physiother. 2024 Oct;70(4):288-293. doi: 10.1016/j.jphys.2024.08.009. Epub 2024 Sep 25. PMID: 39327172.