Reliability and Validity of Inline Dynamometry Study for Measuring Knee Extensor Torque

A Prospective Cross-sectional Study to Determine the Reliability and Validity of Inline 'Pull' Dynamometry for Measuring Peak Knee Extensor Torque in Patients Following Anterior Cruciate Ligament (ACL) Reconstruction: HRA & HCRW Approval Issued.

This study will investigate the reliability and validity of an inline 'pull-type' dynamometer for measuring peak knee extensor torque. For the reliability study, healthy volunteers will be assessed by two assessors (inter-rater) at the index testing session, with testing repeated by one assessor one week later (test-retest). Validity will be investigated against isometric electromechanical dynamometry (gold standard) in patients following anterior cruciate ligament (ACL) reconstruction.

This is a prospective, cross sectional study using a within-participant, repeated measures design. The inter-rater and test-retest reliability of the KForce Link (pull-type dynamometer) will be determine using 50 healthy subjects. The validity of the KForce Link will be determined using 52 post-operative ACL reconstruction patients against the gold standard of isometric electromechanical dynamometry (Cybex). All testing will be performed isometrically with the knee positioned at 60 degrees knee flexion. Assessors and participants will be blinded to the scores until testing is complete.

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the study.
• Male or Female, aged 18 years or above.
• No contraindications to maximal force testing (see exclusion criteria).
• For the ACL reconstruction participant cohort: diagnosed with ACL injury that was managed with ACL reconstruction surgery, with or without additional meniscal surgery. If medicated, stable dose of current regular medication for at least 4 weeks prior to study entry.
• For the healthy control participant cohort: no current or previous history of significant lower limb injury, or a history of previous minor injury that is symptomatic at the time of recruitment. No previous lower limb surgery. No course of medication, whether prescribed or over the counter, other than vitamins and mineral supplements or, for females, oral contraceptives.

Exclusion Criteria:

• Unable to provide written consent to study participation, or there are contraindications to maximal force testing, including the following:

  • History of chronic disease or disorder that may put the participants at risk because of participation in the study including non-united fractures, epilepsy, cardiac insufficiency, severe peripheral vascular disease, aneurysms, anticoagulant therapy, recent (<3 months) radiotherapy or chemotherapy, long term steroid use (>3 months), pregnancy, neurological disorders (e.g., Parkinson's disease), skin conditions at point of force testing, severe osteoporosis, malignancy, rheumatoid arthritis.

• Conditions or symptoms that may influence the result of the study, or the participant's ability to participate in the study including pain, limited range of motion, knee effusion, or anaemia.