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To M.1, Alexander C.1,2
1Imperial College Healthcare NHS Trust, Department of Therapies, London, United Kingdom, 2Imperial College London, Department of Surgery and Cancer, London, United Kingdom
Background: Joint Hypermobility Syndrome (JHS) is characterised by excessive flexibility and multiple joint pains, with the knee being the most common site of pain. This differs to the more common generalised joint hypermobility (GJH), which is characterised by excessive flexibility without multiple joint pains. It is not fully understood why some people with hypermobility have problems and others do not. However, people with JHS are weak and it is suspected that this weakness contributes to the pain and instability. Furthermore, clinicians suspect that people with JHS are slower to strengthen. This suspicion is important to clarify because it affects the ability to set informed and achievable goals and influences expectations, satisfaction and adherence to exercise.
Purpose: To assess change of muscle strength over time in people with JHS and patellofemoral pain (PFP) and compare this to people with PFP who have a) GJH and b) average flexibility.
Methods: With ethical approval and informed consent, adults were recruited into 3 groups; subjects with JHS (positive Brighton criteria with PFP), subjects with GJH (positive Beighton, negative Brighton with PFP) and subjects without hypermobility with PFP. To achieve a power of 80% (5% significance) 20 subjects per group were required. Appointments were scheduled fortnightly for 16 weeks. During each appointment, exercises were tailored to the individuals goal, strength and pain, and were progressed and practiced. In addition, an isokinetic leg press measured concentric and eccentric peak torques. Analysis was intention to treat. Regression analyses were used to explore relationships within groups. Data were assessed for normality and within-group and between-group differences in peak torque were assessed using appropriate tests.
Results: 102 subjects were recruited as we predicted a high dropout rate particularly in the JHS group (n=47 JHS, n=29 GJH, n=26 control). Of these, 30, 20 and 21 subjects in each group respectively completed the
16 week study.
Concentric and eccentric torque were positively correlated with time (concentric R2=0.12; 0.11, 0.10 respectively; eccentric R2=0.12, 0.06, 0.08; all p 0.001). Mean concentric and eccentric torque increased in the JHS group by 36.4Nm and 40.2Nm, in the GJH group by 37.5Nm and 47.9Nm and in the control group by 39.5Nm and 47.2Nm respectively (p 0.001) however, there was a difference in strength between the cohorts (p 0.001). The JHS group were weaker than the other two groups throughout the study (p 0.001). Interestingly the GJH group were stronger than the control group (p 0.001). Importantly, the JHS group required an extra 11 weeks of concentric training and 16 weeks of eccentric training to reach the baseline strength of the GJH group.
Conclusion(s): It is encouraging to see that subjects with JHS are able to strengthen both concentrically and eccentrically. However, the JHS group are weaker, and stayed weaker throughout the study. Indeed, it took them three to four months to reach the starting strength of the other two groups.
Implications: Despite the fact that people with JHS are weaker, when given appropriate, tailored and increasingly difficult exercises over a long period, they are able to increase their muscle strength.
Funding acknowledgements: MT is supported by an Imperial College Healthcare Charity Award. CMA is supported by the National Institute of Health Research.
Topic: Rheumatology
Ethics approval: Approved by London-Harrow research ethics committee, UK.
All authors, affiliations and abstracts have been published as submitted.
