Shoulder Instability in Children: Muscle Activity and Movement

Shoulder Instability in Children: Understanding Muscle Activity and Movement Pattern Differences

The aim of this study is to identify factors responsible for recurrent shoulder instability in children. Shoulder instability, i.e. complete or partial dislocation of the shoulder joint, is common in children, resulting in pain and disability. Recurrent instability can damage the shoulder joint resulting in the premature development of arthritis.

Rehabilitation approaches are preferred over surgical methods for the growing child e.g. physiotherapy to restore movement and prevent further instability. Existing rehabilitation procedures are based on addressing factors assumed to be responsible for instability e.g. physiotherapists may try to increase shoulder stability by building up the shoulder muscles to compensate for the damaged ligaments. It is evident however that the mechanisms of shoulder instability are not well understood, as failure rates for physiotherapy are high, with 70% - 90% of children continuing to suffer recurrent instability. This is an observational, cross-sectional study of children (aged 8 to 18) presenting with shoulder instability of any origin, traumatic or atraumatic (n=15) and an age-matched sample (n=15) with no history of shoulder problems. Muscle activity and movement pattern differences will be measured using non-invasive 3D motion capture and surface electromyography, to identify factors responsible for instability. Only a single visit to the site will be required (The Orthotic Research & Locomotor Assessment Unit (ORLAU) based at The Robert Jones & Agnes Hunt Orthopaedic Hospital NHS Foundation Trust in Oswestry.).

If investigators better understand the mechanisms associated with instability, physiotherapy interventions to reduce dislocations and disability can be better targeted. If specific patterns of activity associated with instability are identified, these could be addressed through personalised and improved exercise prescription and rehabilitation. Additionally, causes of instability for which physiotherapy may not be appropriate may be identified, therefore ensuring patients are referred to the correct service in a timely manner, improving patient outcomes and allocating physiotherapy resources more appropriately. Participants will be recruited from musculoskeletal/orthopaedic outpatient clinics. This study is funded by the Private Physiotherapy Education Foundation.

Inclusion Criteria:

Shoulder instability participants

• Children aged between 8 to 18 years of age
• Subjective reports of instability with additionally symptomatic instability in the clinical assessment criteria below
• Symptomatic instability on clinical assessment in at least one direction, confirmed by a positive clinical finding (apprehension, guarding, laxity) during the sulcus, apprehension or anterior and posterior shift load tests.
• All forms of instability including multidirectional instability, atraumatic and traumatic subluxations and dislocations.
• Children presenting with an initial or recurrent episode of instability
• Children undergoing current management or rehabilitation for their shoulder at the time of the study
• Patients with surgically managed shoulder instability who have since had a further episode of shoulder instability

Age matched controls

- Children aged between 8 to 18 years of age

Exclusion Criteria:

Shoulder instability participants

• Children with co-existing neurological pathologies or deficits
• Surgically managed patients who have not had episodes of instability following the intervention

Age matched controls

• Any previous presentation to a health care professional with a diagnosis of shoulder instability
• Children with a previous shoulder injury within the last 3 months on the arm being assessed that has not resolved
• Children with co-existing neurological pathologies or deficits
• Children who have had a previous surgical intervention on the arm being assessed
• Children currently undergoing or awaiting medical management, diagnostic investigations or rehabilitation on the arm being assessed