Comparison of Common Methodologies for the Determination of Knee Flexor Muscle Strength

Abstract

Background Knee flexion strength may hold important clinical implications for the determination of injury risk and readiness to return to sport following injury and orthopedic surgery. A wide array of testing methodologies and positioning options are available that require validation prior to clinical integration. The purpose of this study was to 1) investigate the validity and test-retest reliability of isometric knee flexion strength measured by a fixed handheld dynamometer (HHD) apparatus compared to a Biodex Dynamometer (BD), 2) determine the impact of body position (seated versus supine) and foot position (plantar- vs dorsiflexed) on knee flexion peak torque and 3) establish the validity and test-retest reliability of the NordBord Hamstring Dynamometer. Study Design Validity and reliability study, test-retest design. Methods Forty-four healthy participants (aged 27 ± 4.8 years) were assessed by two raters over two testing sessions separated by three to seven days. Maximal isometric knee flexion in the seated and supine position at 90 o knee flexion was measured with both a BD and an externally fixed HHD with the foot held in maximal dorsiflexion or in plantar flexion. The validity and test-retest reliability of eccentric knee flexor strength on the NordBord hamstring dynamometer was assessed and compared with isometric strength on the BD. Results Level of agreement between HHD and BD torque demonstrated low bias (bias -0.33 Nm, SD of bias 13.5 Nm; 95% LOA 26.13 Nm, -26.79 Nm). Interrater reliability of the HHD was high, varying slightly with body position (ICC range 0.9-0.97, n=44). Isometric knee flexion torque was higher in the seated versus supine position and with the foot dorsiflexed versus plantarflexed. Eccentric knee flexion torque had a high degree of correlation with isometric knee flexion torque as measured via the BD (r=0.61-0.86). The NordBord had high test-retest reliability (0.993 (95%CI 0.983-0.997, n=19) for eccentric knee flexor strength, with an MDC 95 of 26.88 N and 28.76 N for the left and right limbs respectively. Conclusion Common measures of maximal isometric knee flexion display high levels of correlation and test-retest reliability. However, values obtained by an externally fixed HHD are not interchangeable with values obtained via the BD. Foot and body position should be considered and controlled during testing. Level of Evidence 2b

Measurement properties for muscle strength tests following anterior cruciate ligament and/or meniscus injury: What tests to use and where do we need to go? A systematic review with meta-analyses for the OPTIKNEE consensus

“…There is also concern of inaccuracy when testing large muscle groups such as the knee extensors using HHD 1 88. This finding is consistent with systematic reviews on healthy and injured individuals13 and applies also for knee flexor strength tests 95…”

The Effect of Ankle Position on Peak Eccentric Force during The Nordic Hamstring Exercise

“…Previous studies have reported that isometric and concentric knee flexion torque was significantly greater with the ankle dorsiflexed position than the plantarflexed position (Ogborn et al, 2021;Marchetti et al, 2019;Miller et al, 1996;Croce et al, 2000). Since the gastrocnemius is a biarticular muscle, it is thought that ankle dorsiflexion stretches the gastrocnemius and brings it closer to its optimal length, which contributes to knee flexion strength and knee joint stability, thereby enabling greater muscle force (Miller et al, 1996;Croce et al, 2000) In NHE strength testing, it was thought that the ankle dorsiflexed position was suitable for exerting greater peak eccentric force than the plantarflexed position; but, our results differed from the hypothesis.…”

“…Hamstring strength may be affected by ankle position, as a previous study reported that isometric knee flexion torque was 14-22% greater with the ankle dorsiflexed position than the plantarflexed position (Ogborn et al, 2021;Marchetti et al, 2019). Similarly, concentric knee flexion torque (angular velocity of 60°/s) was 7-13% greater with the ankle dorsiflexed position than the plantarflexed position (Miller et al, 1996;Croce and Miller, 2000).…”

Unilateral Strength Training Imparts a Cross-Education Effect in Unilateral Knee Osteoarthritis Patients

“…Maximal voluntary isometric contraction (MVIC) of the knee extensors and knee flexors was measured pre, immediately post intervention and at 3 months follow-up, with the unaffected contralateral limb tested prior to the KOA limb at each assessment. The participants were seated with their knees flexed at 60 degrees (−30 degrees from full knee extension) and the hip joint at 85 degrees on an isokinetic dynamometer (Biodex System 4 Pro, Biodex Medical Systems, Shirley, NY, USA), which has an intraclass correlation coefficient (ICC) of 0.93 for knee extension and an ICC of 0.89 for knee flexion [ 27 ]. Knee flexion of 60 degrees was selected to ensure consistency between testing sessions and participants; 60 degrees of knee flexion results in the greatest force output following and bypassing any potential restriction in movement due to KOA.…”