Li K.M.1, Tang R.S.S.1, Chan M.C.E.2, Udipi S.1, Hairodin Z.1, Ong H.S.3
1Tan Tock Seng Hospital, Physiotherapy Department, Singapore, Singapore, 2Self-Employed, Singapore, Singapore, 3Tan Tock Seng Hospital, Department of Orthopaedic Surgery, Singapore, Singapore
Background: Motor system changes exist In lateral epicondylalgia (LE). Kinetic chain deficits may predispose or perpetuate LE symptoms. No study has quantified both rotator cuff and scapulothoracic strength in LE, using a feasible clinical protocol, in an asian population. The relationship between shoulder strength with grip strength, symptom duration, self-reported pain and function has not been investigated in persons with LE.
Purpose: This pilot study quantifies shoulder strength on LE-affected and unaffected arms of asian persons with LE using handheld dynamometry (HHD). Its secondary purpose is to examine the relationship between shoulder strength with grip strength, symptom duration, self-reported pain and function in LE.
Methods: This is a prospective cohort sample study. 13 subjects (52.7± 9.9 years old) referred for outpatient physiotherapy, with LE diagnosis, positive LE provocation tests, but without shoulder, cervical and associated neurological abnormalities were recruited. Subjects reported pain levels using Numerical Rating Scale. Self-reported function was measured with Quick-Disability of Arm, Shoulder and Hand questionnaires Activities-of-daily-living (ADL) and work-related modules. An adapted protocol combined from Day et al (2015) and Alizadehkaiyat et al (2007) tested isometric strength of
i) middle trapezius,
ii) lower trapezius (LT),
iii) serratus anterior (SA),
iv) shoulder external and internal rotation and
v) grip, bilaterally.
Each subjects LE-affected and unaffected arm strength was compared, with significance testing through paired t-test, with statistical significance, p 0.05. Shoulder strength on LE-affected and unaffected arms was expressed as a ratio. Spearman correlation was used for incidence and correlation analysis of shoulder strength ratio with grip strength ratio, symptom duration, self-reported pain and function.
Results: Results showed weakness on LE-affected arms versus unaffected arms, with SSR less than 1 in all shoulder muscles. Weakness was significant in the LT (0.88± 0.21, p=0.028) and ER (0.91±0.21, p=0.026). LE occurred on the dominant arm in 61.5% of subjects. SA strength asymmetry was less when the dominant arm was affected (p=0.009). Lesser LT strength asymmetry had strong, positive correlation with impairments in ADL (r=0.775, p=0.002) and work (r=0.701, p=0.008). SSR did not correlate significantly with grip strength, symptom duration, or pain score.
Conclusion(s): Asymmetry of scapulothoracic and rotator cuff muscle strength exists in LE. Hand dominance of the LE-affected arm may influence symmetry of shoulder strength. Differing extents of shoulder muscle weakness may be related to differing demands or deficits in upper limb function of subjects, but causation cannot be inferred from this study.
Implications: These preliminary findings show interesting relations in this Asian population of LE subjects. Subjects who had less reduction in LT strength on LE-affected arms reported significantly more functional impairments. Investigating subjects shoulder activity level, shoulder strength reassessment post-rehabilitation will enhance understanding of the implications of shoulder strength asymmetry. Further investigations of clinically feasible shoulder strength assessment methods and clinical protocols for shoulder strengthening in LE will be beneficial. The lack of significant correlation between shoulder weakness with grip strength, symptom duration and self-reported pain may be attributed to small sample size.
Funding acknowledgements: This work is not funded.
Topic: Musculoskeletal: upper limb
Ethics approval: DSRB, National Healthcare Group, Singapore. Reference: 2015/00776
All authors, affiliations and abstracts have been published as submitted.
