A.L. Ager1,2, J.-S. Roy3,4, A. Cools2
1The CIRRIS / IRDPQ and Université Laval, Motor Control Laboratory, Quebec City, Canada, 2Ghent University, Department of Rehabilitation Sciences, Ghent, Belgium, 3Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Motor Control Laboratory, Quebec City, Canada, 4Université Laval, Department of Rehabilitation / Faculty of Medicine, Quebec City, Canada

Background: A shoulder injury is a common reason to seek physiotherapy, with up to two-thirds of adults reporting a shoulder injury over a lifetime.  It can be devastating to a person’s physical abilities, causing work absenteeism, limiting activities of daily living and is a costly health care problem.  Shoulder injuries cause pain, weakness, and a decreased sense of proprioception. Proprioception, our sense of positioning and movement, is important for motor control, learning new skills and preventing injuries. Indeed, proprioception is important to rehabilitate; however, there exists no clinical tools for measuring this sense.  Currently, proprioception is indirectly measured in a laboratory through joint repositioning, using complex equipment (Biodex or FASTRAK systems), which are not clinically accessible.  Consequently, there is an immediate need for valid and reliable shoulder proprioception clinical tools.

Purpose: To establish a user-friendly and scientifically supported method of clinically measuring shoulder proprioception. This will be achieved through the psychometric testing (validity and reliability) of a new tool: The Shoulder Proprioception Reaching Test (SPReT).

Methods: A cross-sectional clinical measurement study, with an intra-rater test-retest protocol was conducted amongst forty healthy participants (29.7 ± 8.7 years old).  A single session (120 minutes) involved two performances of the SPReT, with a 30 minute-rest between testing. Furthermore, twenty of the included participants were randomly selected to perform a fatigue protocol of the dominant shoulder, followed by a final SPReT performance. 
The SPReT is a plasticized mat, mounted on a wall with double-sided magnets for adjustability. It has four intersecting lines at 45° from each other, in a star-formation with 7 targets. Participants stand and face the mat, while reaching towards one of the targets with their index finger. They are to memorize the position of their index finger in the centre of the target for 5 seconds (memorization trial), three times. This is immediately followed by three active reproduction trials, while blindfolded. The difference between a memorization trial and a reproduction trial represents the proprioception error (PE) (in centimetres).
Descriptive statistics for each target were collected using the mean PE. Discriminant validity (paired t tests, ANOVAs), intra-rater reliability (intraclass correlation coefficients [ICC]) and absolute reliability (standard error of measurement [SEM], minimal detectable change [MDC]) were used for statistical analysis.

Results: The SPReT supports moderate (ICC = 0.45 – 0.71) to good (ICC = 0.77) intra-rater reliability with MDC95 values ranging from 3.24 to 7.84 cm and SEMs from 1.17 to 2.63 cm for all targets. The SPReT was found to have poor discriminant validity, as no fatigue effect was identified.

Conclusion(s): The SPReT has potential for clinical practice upon further methodological investigation. Testing amongst individuals with rotator cuff dysfunctions is being conducted (2019-21), to establish concurrent and discriminant validity, inter-rater reliability and responsiveness measures.

Implications: The SPReT is a novel user-friendly clinical tool, which could help quantify shoulder proprioception deficits amongst populations affected by shoulder injuries. Further testing with a pathological population will help to determine the normative data and clinically important differences, in order to establish the prognostic potential of the SPReT.

Funding, acknowledgements: No funding was awarded for this project.

Keywords: Shoulder, Proprioception, Outcome Measure

Topic: Musculoskeletal: upper limb

Did this work require ethics approval? Yes
Institution: Institut de réadaptation en déficience physique de Québec (IRDPQ)
Committee: Ethics and Research Committee of the IRDPQ
Ethics number: 2015-426, 2015-446 and 2016-426

All authors, affiliations and abstracts have been published as submitted.

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