| dc.description.abstract | Patellofemoral pain (PFP) is a common and persistent knee pain complaint among all age ranges, especially highly active people. Multiple approaches have been used to understand symptom persistence, including identifying a mechanism explaining intervention benefits (i.e. changes in specific deficits in groups that show symptoms’ improvement). Research has been conducted to identify the characteristics associated with PFP, but uncertainty regarding local neuromuscular characteristics remain evident. The thesis aimed to a) identify the local neuromuscular characteristics associated with PFP, b) develop an evidence informed laboratory protocol to detect those characteristics, c) establish protocol reliability and feasibility, and d) identify interventions that can target these neuromuscular characteristics. A systematic review with meta-analysis was completed to identify the neuromuscular characteristics of all muscles that cross the knee in people with PFP compared to uninjured groups. Ten deficits within three neuromuscular domains were found. Within the electromyography (EMG) domain, a delay in Vastus medialis (VM) relative to Vastus lateralis (VL) excitation onset, a high Biceps femoris (BF) mean excitation amplitude, and a lower Hoffman-reflex amplitude of VM were identified. Within the muscle performance domain, lower isometric, concentric, and eccentric extensors peak torque and total work, lower concentric flexors peak torque, and lower rate of torque development (RTD) to reach 30%, 60% and 90% of extensors peak torque were identified. Hamstring tightness was identified within muscle flexibility domain. The systematic review was published and the results used to inform testing protocol development. A second systematic review with meta-analysis was conducted to identify interventions that can target the local deficits associated with PFP. The results indicate that currently an intervention that effectively modifies EMG characteristics cannot be identified. Predominantly, exercise interventions have effects on strength and flexibility in PFP. Specifically, hip and knee targeted exercises are found to have a potential mechanism of benefit through both characteristics categories. A unique approach was introduced within the thesis to develop a deficit-detection protocol based on systematic review results. This approach provided a comprehensive analysis of the protocols from the studies that were included in the meta-analysis. A battery of tests was developed and included; a) VM-VL excitation onset timing in step-up task, b) BF mean excitation amplitude in single-leg triple-hop test, c) isometric, d) concentric and e) eccentric extensors peak torque, f) RTD to 30%, 60% and 90% of isometric peak torque, and hamstrings flexibility. Reliability testing of the deficit-detection protocol was conducted with both uninjured and participants with PFP over two phases. Phase one evaluated the original protocols adapted from the review. Phase two was performed on the EMG and RTD domains to explore the effects of signal processing parameters on reliability, such as; onset detection thresholds modification, unnormalised signals, and the addition of absolute RTD. For the PFP group: reliable results were demonstrated for concentric and eccentric extensors peak torque; RTD of the quadriceps at 25ms, 50ms and 90% of peak torque; and hamstrings flexibility. The uninjured group showed reliable results in: unnormalised BF mean excitation amplitude; all three peak torque tests; RTD to 30% of peak torque and at 150 and 175 milliseconds; and hamstrings flexibility. To establish participant recruitment rate and retention, in addition to the acceptability of the test protocol, a preliminary feasibility study of the deficit-detection protocol was conducted. A sample of 14 participants with PFP were recruited and tested at the Mile-end campus of QMUL before and after a six weeks period. Feasibility results indicate that 25.5% were willing to participate following an online screening process (n=17/55) and 82% met the eligibility criteria following face-to-face assessment (n=14/17). Recruitment rate was 0.5 participants per week and drop-out rate was 35.2% (n=11/17). The results indicate that the protocol did not meet all a-priori feasibility criteria, but the results can inform future research planning. The thesis has successfully identified local deficits associated with PFP, developed a test protocol that demonstrates reliability in evaluating these deficits and assessed the feasibility of the protocol in individuals with PFP. Interventions to cause change within these local deficits have been identified, with gap maps demonstrating where further research is required to better align the mechanisms of treatment effects with specific deficits associated with PFP. | en_US |
