Investigating Clinical Assessment of Muscle Strength Parameters in Femoroacetabular Impingement Syndrome

McNabb, Katherine Jane (2025) Investigating Clinical Assessment of Muscle Strength Parameters in Femoroacetabular Impingement Syndrome. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Background: Femoroacetabular impingement (FAI) syndrome, affecting young and middle-aged adults, leads to hip pain, reduced function, and limits daily activities and sports. Muscle strength assessment is recommended for individuals with FAI syndrome to guide rehabilitation and monitor recovery, before and after arthroscopic hip surgery. The rate of torque development (RTD) for hip movements, measures how quickly hip muscles generate force and is a key parameter in the performance of dynamic movements yet remains underexplored in the context of FAI syndrome. The handheld dynamometer (HHD) offers a clinically feasible tool for measuring RTD and peak torque (PT) in hip movements, though its validity and reliability for hip assessments requires further investigation. Aim: This PhD project primarily aimed to investigate the impact of FAI syndrome on muscle strength parameters, specifically RTD and PT, both preoperatively and postoperative arthroscopic surgical intervention, to better understand the condition’s effect on muscle performance. The secondary aim was to evaluate the handheld dynamometer (HHD) as a clinical tool for measuring RTD and PT, contributing to the refinement of hip strength assessment in physiotherapy practice. Methodology: This PhD project comprised of three studies: In the first study, a novel methodology using the HHD to measure RTD and PT across six hip movements in healthy individuals was developed and validated. It established the reliability of the HHD, assessed its validity against the isokinetic dynamometer (IKD), and explored correlations between RTD and PT. In the second study, the HHD was used to measure RTD and PT in individuals with FAI syndrome both preoperatively and six months postoperatively following arthroscopic surgery, examining the relationship between these measures, patient-reported outcomes, and activity levels. Lastly, an online survey of UK musculoskeletal physiotherapists explored strength assessment methods employed in clinical practice, with a focus on the awareness and usage of HHDs, as well as identifying barriers and facilitators to their adoption. Findings: This research found firstly, the HHD is a feasible tool for measuring RTD in all hip movements, with late-phase RTD showing better consistency and stronger agreement with the IKD. Secondly, it found that while PT and RTD were correlated in healthy individuals, this was not seen postoperatively in FAI syndrome patients, where PT increased across all movements, but RTD improved only in hip flexion and extension postoperatively. Finally, the research discovered that UK physiotherapists have widespread awareness of HHDs, but manual muscle testing remained the most frequently used strength assessment method. Training and practical application were key factors influencing the use of HHDs in clinical practice. Conclusions: This PhD programme of research highlights hip joint RTD as a valuable parameter for assessing hip function in FAI syndrome, particularly postoperatively. The HHD offers a practical and reliable method for measuring RTD, though clinicians should consider its limitations, especially for early-phase RTD. Manual muscle testing is the most commonly used strength assessment method among UK musculoskeletal physiotherapists, with increased training needed for HHDs to be more widely adopted in clinical practice.