Exercise for multidirectional instability of the shoulder

Objectives

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To assess the benefits and harms of exercise therapy for multidirectional instability of the shoulder.

Background

Description of the condition

Multidirectional instability of the shoulder is defined as 'symptomatic glenohumeral subluxation or dislocation in at least two directions' (Bahu 2008; Neer 1980), with the humeral head inadequately stabilised within the glenoid fossa during shoulder motion. To maintain suitable stability, the rotator cuff centralises the humeral head toward the glenoid fossa. The surrounding ligament and capsule also contribute to joint stabilisation by increasing their tension during motion (Pagnani 1994). Thus, disruption of these mechanisms is associated with the development of multidirectional shoulder instability.

Most reports suggest that people with multidirectional instability have nontraumatic, repetitive microtrauma, or to a lesser extent, trauma (An 2000; Bahu 2008; Beasley 2000; Guerrero 2009; Misamore 2005). The incidence of multidirectional instability has been reported in 17 of 75 elementary school students (22.6%) and 52 of 457 elite female gymnasts (11% (Caplan 2007; Emery 1991)). One cohort study reported that 117 of 4141 adults experienced traumatic shoulder instability events during a one‐year period. Of these, 11/117 cases (9.4%) presented with multidirectional instability (Owens 2007). Multidirectional instability occurs predominantly in females in their 20s and 30s, and in people who participate in sports or work that require repetitive overhead movements (Beasley 2000; Neer 1980). It causes a variety of symptoms (e.g. discomfort, apprehension, or pain) in the shoulder, which affects daily activities and work (An 2000; Bahu 2008). In contrast, people with traumatic shoulder dislocation have a history of significant trauma (e.g. a fall with resulting dislocation), with more than 95% in the anterior and 5% in the posterior or inferior directions (Khiami 2015). Traumatic shoulder dislocations are accompanied by soft tissue or bony structural lesions, or both, in the glenohumeral joint, resulting in unidirectional instability (Hayes 2002).

The aetiology of multidirectional instability is multifactorial, with congenital, acquired, and traumatic factors contributing to the condition (Guerrero 2009). A common hallmark of multidirectional instability is laxity of the glenohumeral ligaments and capsule, which provides anterior, posterior, and inferior shoulder stability during motion (Pagnani 1994; Schenk 1998). Multidirectional instability involves both shoulders in some people and is frequently accompanied by ‘general joint laxity’, which is laxity in various joints of the body (Altchek 1991; Johnson 2010). The prevalence of general joint laxity in people with multidirectional instability ranges from 40% to 70% (Saccomanno 2013). Disruption of the stabilising mechanism, such as general joint laxity, eventually leads to multidirectional shoulder subluxation or dislocation. Dysfunction of dynamic stabilisers (i.e. rotator cuff and surrounding soft tissue) also leads to multidirectional instability. Scapular malposition is observed in 50% to 80% of people with multidirectional instability (Kibler 2016; Spanhove 2020), limiting the upward rotation and glenoid inclination during arm elevation (Ogston 2007). Thus, dysfunction of dynamic stabilisers and scapular movement is associated with the development of multidirectional instability, in addition to glenohumeral ligaments and capsule laxity.

Description of the intervention

Exercise therapy is a non‐operative treatment for multidirectional instability, and may be delivered by physical therapists, chiropractors, and osteopaths, among others (Burkhead 1992; Watson 2018). It can be done under the supervision of a clinician or unsupervised, at home. Exercise environments can be land‐ or water‐based. It consists of isometric and isotonic exercises, which aim to increase the rotator cuff and deltoid functions and improve congruity between the humeral head and glenoid (Guerrero 2009). Scapular dyskinesis, which affects scapular motion and position (e.g. decreased scapular upward rotation), is observed in multidirectional instability and needs to be addressed (Ogston 2007). Periscapular muscle strengthening (e.g. scapular upward rotation, elevation exercise drills, and push‐up training) helps normalise scapular motion in multidirectional instability (Watson 2016; Watson 2017).

Proprioception and perturbation exercises are also included. Proprioceptive exercise increases scapular tension, rotator‐cuff strength, and neuromuscular control mechanisms, thereby improving joint stability and mobility (Merolla 2015). Perturbation exercises induce rapid postural responses to unexpected external perturbations, thereby improving reactive postural control.

How the intervention might work

To date, little evidence has been provided regarding the effects of exercise therapy on multidirectional instability (Warby 2014; Warby 2016). Exercise therapy is hypothesised to increase the stability and active control of the shoulder, improving glenohumeral instability caused by capsule laxity and scapulothoracic dysfunction resulting from muscular imbalance (Kibler 2016; Watson 2018). This is based on the rationale that muscle strengthening improves shoulder stability (Beasley 2000; Guerrero 2009; Mallon 1995). Thus, exercise therapy may contribute to the functional improvement of dynamic stabilisers, ultimately alleviating symptoms in people with multidirectional instability.

Why it is important to do this review

Physicians commonly recommend exercise therapy as the first choice for non‐operative treatment of multidirectional instability (Warby 2017). In 2014, a systematic review analysed seven non‐randomised controlled trials investigating the effects of exercise therapy alone in people with multidirectional instability (Warby 2014). Neither review identified any randomised controlled trials that compared exercise therapy with no treatment or a placebo; thus, the effectiveness of exercise therapy alone could not be demonstrated.

Surgical intervention may be considered when multidirectional instability is refractory to non‐operative treatment. Surgery aims to restore joint stability by reducing the capsular volume, and includes inferior capsular shift, thermal capsulorrhaphy, and capsular plication. In 2016, a systematic review analysed the effects of exercise therapy and surgical treatment on multidirectional instability in four non‐randomised controlled trials (148 participants in the exercise group and 86 participants in the surgical group, totalling 234 participants (Warby 2016)). The results showed that surgery improved shoulder function and a return to sports better than exercise therapy, whereas exercise therapy improved shoulder instability (Rowe score) and patient satisfaction more than surgery. Therefore, the efficacy of exercise therapy remains unclear.

Two randomised controlled trials that analysed specific forms of exercise and other comparative treatments for people with multidirectional instability have been published since 2018 (Spanhove 2022; Warby 2018).

Therefore, it is important to undertake this systematic review to capture any additional trials, synthesise the existing data, and identify the safety and effectiveness of exercise therapy for treating multidirectional instability. We aim to conduct the first Cochrane review assessing the benefits and harms of exercise therapy for multidirectional instability.

Objectives

To assess the benefits and harms of exercise therapy for multidirectional instability of the shoulder.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomised controlled trials. We will include parallel and cross‐over trials (only data from before cross‐over), and cluster‐randomised trials. We will include studies reported as full text, those published as abstract only, and unpublished data.

Types of participants

We will include studies that recruited participants with traumatic or non‐traumatic multidirectional instability (as defined by trialists) with any symptom duration. We will include studies with participants with various shoulder disorders only if the results for participants with multidirectional instability are presented separately.

We will exclude studies that included participants with systemic inflammatory conditions, such as rheumatoid arthritis, osteoarthritis, and hemiplegic shoulders.

Types of interventions

We will include any type of exercise therapy for multidirectional instability. Eligible interventions include supervised or unsupervised exercises, individual exercises, or combinations of various types. Exercise can be land‐ or water‐based, but should consist of shoulder‐specific exercises rather than general activities (e.g. swimming or running). We will accept trials with any content, duration, frequency, or intensity of exercise.

Comparisons

1. Exercise therapy versus placebo

2. Exercise therapy versus no treatment, waiting list, or usual care

Co‐interventions (e.g. electrotherapy and taping) will be allowed as long as they are applied equally to all study groups.

Types of outcome measures

Major outcomes

1. Overall pain: mean or mean change, measured by visual analogue scale (VAS), numerical, or categorical rating scale

2. Shoulder instability, measured on validated self‐reported outcome measures. When the trialists report outcome data for more than one instability score, we will extract data on the scale that was highest on this defined list: (1) Rowe score for instability (Rowe 1978; Rowe 1981; Rowe 1982; Rowe 1988), (2) Western Ontario Shoulder Instability Index (Kirkley 1998), (3) Oxford instability shoulder score (Dawson 1999), (4) Melbourne instability shoulder score (Watson 2005), and (5) any other shoulder‐specific instability scale. When trialists do not report a shoulder instability measure, we will extract data on the validated function scale that was highest on this defined list: (1) Constant Murley Score (Constant 1987), (2) American Shoulder and Elbow Surgeon Score (Richards 1994), (3) University of California at Los Angeles Score (Esch 1988), and (4) any other validated shoulder‐specific function scale.

3. Participant's global assessment of treatment success (participant satisfaction or any other self‐reported measure of success), or as defined by the trialists (such as the proportion of participants with significant overall improvement)

4. Health‐related quality of life (HRQoL), assessed by the Mental Component Score (MCS) of the Short Form‐36 (SF‐36 (Ware 1992))

5. Number of participant withdrawals due to adverse events

6. Number of participants who experienced an adverse event

Minor outcomes

1. Range of motion (ROM): flexion, abduction, external rotation, and internal rotation, measured in degrees or other scales (e.g. hand‐behind‐back distance in cm). If the trial authors report outcome data for both active and passive ROM measures, we will only extract data for active ROM measures.

2. Muscle strength: strength of any shoulder muscle, measured using a digital hand dynamometer, isokinetic peak torque, or others

3. Number of participants experiencing subluxation or dislocation, as defined by the study authors

4. Number of participants who undergo surgery for multidirectional instability

Absence of the major and minor outcomes will not be criteria for excluding studies from the review.

Timing of outcome assessments

We will extract data at the end of the intervention (primary time point), and the last follow‐up (≥ 12 months) after the end of the intervention. If data from multiple time points are provided, we will use the longest time point reported for the period after the end of the intervention.

Search methods for identification of studies

Electronic searches

We will search the following databases, without restrictions on language or date of publication.

1. The Cochrane Central Register of Controlled Trials (CENTRAL; current issue)

2. MEDLINE Ovid (1946 to current; Appendix 1)

3. Embase Ovid (1974 to current)

We will also search the US National Institutes of Health Ongoing Trials Register, ClinicalTrials.gov (www.ClinicalTrials.gov), and the World Health Organization Clinical Trials Registry Platform (ICTRP; www.who.int/ictrp/en/) for ongoing or unpublished trials.

Searching other resources

We will check the reference lists of all included studies and review articles identified in the database searches for additional references. We will also contact experts in the field to ask whether they know about ongoing or unpublished trials.

Data collection and analysis

Selection of studies

Two review authors (MK and TI) will independently screen the titles and abstracts we identify through the search, and code them as 'retrieve' (eligible or potentially eligible/unclear) or 'do not retrieve'. We will retrieve the full‐text study reports/publication of those we identify as 'retrieve', and two review authors (MK and TI) will independently screen the full text to identify studies for inclusion, and identify and record reasons for exclusion of the ineligible studies. We will resolve any disagreement through discussion, or if required, we will consult a third person (JK).

We will identify and exclude duplicates and collate multiple reports of the same study under a single reference ID so that each study, rather than each report, is the unit of interest in the review. We will record the selection process in sufficient detail to complete the characteristics of excluded studies table, and a PRISMA flow diagram (Page 2021).

Data extraction and management

We will use a data collection form for study characteristics and outcome data, which has been piloted on at least one study from the review.

1. Methods: study design, total duration of study, details of any 'run‐in' period, number of study centres and location, study setting, withdrawals, and date of study

2. Participants: the number of people randomised, the number of people completing treatment, the number of people who withdrew or were lost to follow‐up, mean age, age range, sex, disease duration, diagnostic criteria, inclusion criteria, and exclusion criteria

3. Interventions: type of exercise, supervised or unsupervised, individually or in a group, measurement and reporting of adherence to exercise, setting in which exercises were performed, qualifications of the exercise instructor, exercise content (frequency, intensity, total number of treatment sessions, duration of each session of treatment, length of program), comparisons, and co‐interventions. We will use the Consensus on Exercise Reporting Template (CERT) to extract the characteristics of exercise interventions (Slade 2016).

4. Outcomes: major and minor outcomes as specified and collected; time points when reported, including a description of the measurement tool (i.e. direction of scale)

5. Characteristics of the design of the trial, as outlined in the Assessment of risk of bias in included studies section

6. Notes: funding for the trial, notable declarations of interest of trial authors, intervention adherence (expressed as percentages or number of participants), information about missing data, and contact with study authors

Two review authors (MK and TI) will independently extract the outcome data from the included studies. We will resolve disagreements by consensus, or by involving a third review author (JK). One review author (MK) will transfer the data to Review Manager Web (RevMan Web 2023). We will double‐check that data are entered correctly by comparing the data with the study reports.

We will follow these decision rules to extract data in the event of multiple outcome reporting in trials.

1. If both final values and changes from baseline values are reported for a continuous outcome, we will extract the final values.

2. If both unadjusted and adjusted values are reported for the same outcome, we will extract adjusted values.

3. If data are analysed on the basis of both an intention‐to‐treat (ITT) sample and another sample (e.g. per‐protocol, as‐treated), we will extract the ITT‐analysed data.

Assessment of risk of bias in included studies

Two review authors (MK and TI) will independently assess the risk of bias for each study using the RoB 2 tool (Sterne 2019), outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2023b). We will resolve disagreements by discussion, or by involving another author (TA).

We will assess the risk of bias according to the following domains:

1. bias arising from the randomisation process;

2. bias due to deviations from intended interventions;

3. bias due to missing outcome data;

4. bias in measurement of the outcome;

5. bias in selection of the reported result.

We will use the signalling questions in RoB 2 and rate each domain as low risk of bias, some concerns, or high risk of bias.

We will summarise the risk of bias judgements for each outcome across different studies for each of the domains listed; the overall risk of bias for the outcome will be the least favourable assessment across the domains of bias.

For the results of an outcome to be judged at low risk, all domains must be rated at low risk of bias. We will assess an outcome as having some concerns if we rate the risk of bias as having some concerns in at least one domain, and rate none of the domains at high risk of bias. We will assess an outcome at high risk if we identify at least one domain at high risk of bias. We will also classify an outcome at high risk if we judge several domains as having some concerns, as we consider confidence in such an outcome to be considerably reduced (Higgins 2023b).

We will assess the risk of bias for the major outcomes, with a focus on the effect of the assignment to the intervention (the ITT effect).

Measures of treatment effect

If continuous outcomes are measured on the same scale across studies, we will use the mean difference (MD) and 95% confidence intervals (CIs). If different scales are reported across trials, we will use the standardised mean difference (SMD) and 95% CIs. We will back‐translate SMDs to a typical scale (e.g. 0 to 10 for pain) by multiplying the SMD by a typical among‐person standard deviation (e.g. the standard deviation (SD) of the control group at baseline from the most representative trial (Higgins 2023a)). For dichotomous outcomes, we will use risk ratio (RR) and 95% CI.

We will assume a minimal clinically important difference (MCID) of 1.5 points on a 10‐point scale for pain, and 10 points on a 100‐point scale for function or disability (Tubach 2012).

Unit of analysis issues

When multiple trial arms are reported in a single trial, we will include only the relevant arms. When a trial includes multiple relevant treatment arms, we will combine groups to perform a single pairwise comparison. If this results in the identification of potential heterogeneity, we will analyse each group separately against a common control group. However, to ensure that a common control group is not included multiple times in a meta‐analysis that includes several interventions from the same trial, we will divide the control group by the number of intervention groups to avoid double‐counting. In trials that collected data at different time points within each category, we will use the data at the end of the intervention.

Dealing with missing data

We will contact investigators or study sponsors to verify key study characteristics and obtain missing numerical outcome data where possible (e.g. when a study is identified as an abstract only, or when data are not available for all participants). If this is not possible, and the missing data are thought to introduce serious bias, we will explore the impact of including such studies in the overall assessment of results through a sensitivity analysis. We will clearly describe any assumptions and imputations used when handling missing data, and we will explore the effect of imputation through sensitivity analyses.

For dichotomous outcomes (e.g. number of withdrawals due to adverse events), we will calculate the withdrawal rate using the number of participants randomised in the group as the denominator.

For continuous outcomes (e.g. mean change in pain score), we will calculate the MD or SMD based on the number of participants analysed at that time point. If the number of participants analysed is not presented for each time point, we will use the number of randomised participants in each group at baseline.

If necessary, and when possible, we will compute missing SDs from other statistics, such as standard errors, CIs or P values, according to the methods recommended in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2023a). If we cannot calculate the SDs, we will impute them (e.g. from other studies in the meta‐analysis).

Assessment of heterogeneity

We will assess the clinical and methodological diversity of participants, interventions, outcomes, and study characteristics (e.g. study design and outcome measurement tools) of the included studies to determine whether a meta‐analysis is appropriate. We will assess statistical heterogeneity by visually inspecting the forest plots for obvious differences between study results, and using I² and Chi² statistics. We will interpret the I² statistic as recommended in the Cochrane Handbook for Systematic Reviews of Interventions: 0% to 40% might not be important; 30% to 60% may represent moderate heterogeneity; 50% to 90% may represent substantial heterogeneity; and 75% to 100% represents considerable heterogeneity (Deeks 2023). We will keep in mind that the observed value of I² depends on: (i) the magnitude and direction of effects, and (ii) the strength of evidence for heterogeneity.

When the Chi² has a P value ≤ 0.10, we will interpret this as evidence of statistical heterogeneity.

If we identify substantial heterogeneity (at least 50%), we will report it and investigate the possible causes by following the recommendations in the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2023).

Assessment of reporting biases

We will create funnel plots to explore possible small study biases if we have at least 10 studies in a meta‐analysis. If we are able to pool more than 10 trials, we will undertake formal statistical tests to investigate funnel plot asymmetry (Egger 1997), and follow the recommendations in section 13.3 of the Cochrane Handbook for Systematic Reviews of Interventions (Page 2023).

To assess outcome reporting bias, we will check trial protocols against published reports. For studies published after 1 July 2005, we will screen clinical registers at ICTRP and ClinicalTrials.gov for the trial protocols. We will evaluate whether selective reporting of outcomes is present.

Data synthesis

We will undertake meta‐analyses only when this is meaningful, i.e. if the treatments, participants, and underlying clinical questions are similar enough for pooling to make sense. We will consider the following comparisons.

Comparisons

1. Exercise therapy versus placebo

2. Exercise therapy versus no treatment, waiting list, usual care

We will analyse the data using Review Manager Web (RevMan Web 2023). We will use a random‐effects model in the meta‐analysis, based on the assumption that clinical diversity and methodological heterogeneity is likely to exist, and have an impact on the results. We will include all studies in the primary analysis, regardless of the risk of bias.

Subgroup analysis and investigation of heterogeneity

We will undertake subgroup analyses for two of the major outcomes, pain and shoulder instability, at the primary time point (end of intervention), if data are available.

1. Age (≤ 18 years or > 18 years)

Younger people may not fare as well as older people, because multidirectional instability usually improves with age (Misamore 2005). A previous study examined the recurrence rate in participants with shoulder instability under the age of 18 years, and reported that young people aged 14 to 18 years were more likely to experience recurrent instability. Considering populations with different skeletal maturity, it is expected that age will also affect treatment efficacy in multidirectional instability (Olds 2016).

2. Athletes or non‐athletes (as defined by the trial authors)

Athletes may be more prone to overuse syndromes, with an increased risk of converting generalised capsular laxity to symptomatic instability (Beasley 2000). Therefore, shoulder instability may be more severe in athletic participants with multidirectional instability.

3. Duration of exercise therapy (≤ 12 weeks or > 12 weeks)

The duration of exercise therapy is expected to affect treatment effectiveness. Positive changes in shoulder instability, pain, and muscle strength have been observed in participants with multidirectional instability who received 12 weeks of exercise therapy (Watson 2018).

4. Traumatic or non‐traumatic (as defined by the study authors)

A previous study showed that participants with traumatic multidirectional instability had a higher rate of poor exercise outcomes (Burkhead 1992).

5. Exercise adherence (≤ 80％ or > 80％)

An association between exercise adherence and improved clinical outcomes has been suggested in people with musculoskeletal diseases (Patterson 2021; Pisters 2010).

Sensitivity analysis

We will conduct sensitivity analyses to investigate the robustness of the treatment effect for two of the major outcomes, pain and shoulder instability, if data are available.

1. Risk of bias: we will remove studies that we judged at an overall risk of bias of having some concerns, or at high risk.

2. The impact of excluding studies in which we imputed values for missing data during the review process

3. The impact of excluding studies with poorly or inadequately described comparisons, classified as placebo or no treatment groups

Summary of findings and assessment of the certainty of the evidence

We will follow the guidelines in the Cochrane Handbook for Systematic Reviews of Interventions, Chapters 14 and 15 for interpreting results (Schünemann 2023a; Schünemann 2023b). We will take care to distinguish between a lack of evidence of effect and a lack of effect. We will base our conclusions only on the findings from the quantitative or narrative synthesis of the included studies. We will avoid making recommendations for practice; our implications for research will suggest priorities for future research, and outline the remaining uncertainties in the area.

We will create two summary of findings (SoF) tables at the primary time point (end of intervention); one for the main comparison, exercise versus placebo; and another for the comparison, exercise versus no treatment, waiting list, or usual care. We will create a SoF table using the following outcomes. We will use methods and recommendations described in the Cochrane Handbook for Systematic Reviews of Interventions (Schünemann 2023a).

1. Overall pain

2. Shoulder instability

3. Participant's global assessment of treatment success

4. Health‐related quality of life (HRQoL)

5. Number of participant withdrawals due to adverse events

6. Number of participants who experienced an adverse event

Two review authors (MK and TI) will independently assess the certainty of the evidence, with disagreements resolved by discussion, or by involving a third review author (TA). We will use the five GRADE considerations (study limitations (risk of bias), consistency of effect, imprecision, indirectness, and publication bias) to assess the certainty of a body of evidence as it relates to the studies that contribute data to the analyses for each outcome. We will report the certainty of evidence as high, moderate, low, or very low.

We will use GRADEpro GDT software to prepare the SoF tables (GRADEpro GDT). We will justify all decisions to downgrade the certainty of evidence for each outcome in footnotes, and we will provide comments to aid the reader's understanding of the results, when necessary.

Appendices

Appendix 1. Preliminary MEDLINE Ovid search strategy

#1 Shoulder/

#2 shoulder$.tw.

#3 Shoulder Joint/

#4 Shoulder Pain/

#5 Musculoskeletal Pain/

#6 exp Scapula/

#7 Rotator Cuff/

#8 exp Shoulder Dislocation/

#9 exp Joint Instability/

#10 multidirectional instability.tw.

#11 (shoulder$ adj3 (hypermob$ or hyperextensib$ or dislocat$ or sublux$ or recurr$ or unstab$)).tw.

#12 or/1‐11

#13 Muscle Strength/

#14 exp Exercise/

#15 Physical Exertion/

#16 exp Physical Therapy Modalities/

#17 exp Sports/

#18 exp Rehabilitation/

#19 exertion$.tw.

#20 sport$.tw.

#21 ((physical or motion) adj5 (fitness or therap$)).tw.

#22 ((muscle or strength$ or extensor or weight) adj (training or resistance)).tw.

#23 resistance training.tw.

#24 rehab$.tw.

#25 or/15‐26

#26 12 and 25

#27 randomized controlled trial.pt.

#28 controlled clinical trial.pt.

#29 randomized.ab.

#30 placebo.ab.

#31 clinical trials as topic.sh.

#32 randomly.ab.

#33 trial.ti.

#34 or/27‐33

#35 exp animals/ not humans.sh.

#36 34 not 35

#37 26 and 36

Contributions of authors

MK conceived, wrote the protocol, will conduct screenings, extract data, and complete the risk of bias assessment.
TI will contribute to the screening, extract data, and complete the risk of bias assessment.
MG revised the protocol and will provide input for writing the discussion.
JK will contribute to the screening, and provide input for writing the discussion.
TA will assess the risk of bias in cases of doubt or disagreement, and provide input for writing the discussion.
SY revised the protocol, and will perform the statistical analyses.
All authors approved of the final protocol.

Sources of support

Internal sources

• none to declare, Other

  none

External sources

• none to declare, Other

  none

Declarations of interest

MK: none known
TI: none known
MG: none known
JK: none known
TA: none known
SY: none known

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