ECSS Paris 2023: CP-MH19
INTRODUCTION: Knee injuries such as anterior cruciate ligament (ACL) or meniscus tears are everyday challenges in sports medicine and rehabilitation and often followed by persistent quadriceps weakness (Holder-Powell & Rutherford 2001). The limb asymmetry index (LSI) is frequently used as return to activity clearance, whereby athletes should achieve strength differences of less than 10% (Zwolski et al. 2016). However, there are limited studies that examine this area years after injury and the role of body weight for the calculation is often underestimated (Holder-Powell & Rutherford 2001). METHODS: In this retrospective data analysis of n=29 patients (13 female, 16 male; age 37±12 years, mean weight 73±17 kg) with chronic (86±71 months) unilateral ACL and/or meniscus injuries, we compared strength values of the injured to the healthy leg and have also put the values into perspective relative to body weight. Strength tests were performed on an isokinetic dynamometer (BIODEX system pro, Schnaittach, Germany) with testing velocities of 60°/s, 180°/s and 240°/s for each leg separately. Strength differences between legs were analysed using the student´s t-test for independent samples using SPSS (IBM statistics, New York, USA). P-values of<.05 were set to be significant. RESULTS: Twenty-one patients had an ACL and eight a meniscus injury. There were no significant side differences for absolute maximum torque (diff. = 18±11Nm (11%); p =.117), absolute mean torque (diff. = 21±11Nm (13%), p =.061), absolute maximum work (diff. = 22±13 J (12%), p = .083), absolute mean work (diff. = 20±12J (11%), p = .107) or maximum power (diff. = 11±8W (11%), p = .145) at 60°/s. All values relative to body weight showed significant leg differences (maximum torque: diff. = 0.2±0.1Nm/kg (24%), p = .041; mean torque: diff. = 0.3±0.1Nm/kg (26%), p = .014; maximum work: diff. = 0.3±0.1J/kg (28%), p = .021; mean work: diff. = 0.3±0.1J/kg (25%), p = .037) with a weaker injured leg, except maximum power (diff. = 0.1±0.1W/kg (14%), p = .069). There were no significant and relevant differences for the other velocities. CONCLUSION: Besides limitations due to the small and heterogenous sample size, this study shows that relevant persistent strength deficits exist even years after injury, especially when accounting for body weight and tested with a velocity (60°/s) which enables maximum force production. These differences are also far above the 10% LSI border (Zwolksi et al. 2016). Return to activity decisions should therefore also rely on strength values relative to body weight.
Read CV Florian RiederECSS Paris 2023: CP-MH19
INTRODUCTION: The relationship between muscle size and strength is well established,1 but the relationship of these variables with tendon size has not been clearly elucidated. Strength training results in disproportionate increases in muscle strength (larger) compared to muscle hypertrophy (moderate), and much smaller/marginal increases in tendon cross-sectional area,2 suggesting that these variables do not scale. Thus, the relationship of tendon size with both muscle size and muscle strength requires investigation. Consequently, we aimed to investigate the relationships between patellar tendon (PT) cross-sectional area (CSA) and quadriceps femoris (QF) maximum anatomical CSA (QF ACSAmax), and PT CSA and knee extensor maximum voluntary torque. METHODS: Fifty-seven healthy, young, and recreationally active young men (age: 26 ± 5 years, body mass: 75 ± 11 kg, height: 179 ± 8 cm) were recruited for this study. Isometric maximum voluntary contractions of the knee extensors were assessed with a custom-built isometric knee extension dynamometer to determine isometric muscle strength (maximum voluntary torque) at a knee joint angle of 104°. Magnetic resonance imaging (3.0 T Discovery MR750w, GE Healthcare, Chicago, IL) of the dominant thigh and knee and subsequent manual segmentation allowed determination of quadriceps femoris anatomical cross-sectional area (axial slice thickness 5 mm; inter-slice gap 15 mm) and patellar tendon cross-sectional area (axial slice thickness 2 mm; inter-slice gap 0 mm). Relationships between PT size with both muscle size and strength were assessed by Pearson’s correlation coefficient with an α level of 0.05. RESULTS: There was a strong correlation between QF ACSAmax and isometric knee extension strength (r = 0.779, p < 0.001), as expected. However, PT CSA was only weakly correlated with QF ACSAmax (r = 0.312, p = 0.018) and isometric knee extension strength (r = 0.322, p = 0.014). The muscle/tendon area ratio (i.e. QF ACSAmax divided by patellar tendon CSA) ranged from 54.2 to 139.4 (i.e. a 2.6-fold difference between smallest and largest ratio) and had a between participant coefficient of variation of 18.0%. CONCLUSION: Despite the strong association between muscle strength and size, the association between tendon size and strength, and tendon size and muscle size appears much weaker. Whether individuals with disproportionately large muscles relative to their tendon are more likely to develop tendon pathology requires further prospective evaluation. References 1. Balshaw TG, at al. Med Sci Sports Exerc. 2021 Oct 1;53(10):2140-2151. 2. Massey GJ, et al. Acta Physiol (Oxf). 2018 Apr;222(4):e13019. 3. Szaro P, Ghali Gataa K. Sci Rep. 2021 Mar 17;11(1):6131.
Read CV Fearghal BehanECSS Paris 2023: CP-MH19
INTRODUCTION: Sleep plays a crucial role in sustaining optimal physical and cognitive performance. Despite the demanding nature of surgical practice, sleep patterns and their potential impact on performance have been poorly investigated in surgeons, particularly in orthopaedic specialists. The primary aim of this study was to characterize the habitual sleep of a cohort of orthopaedic surgeons. The secondary aim was to evaluate changes in physical and cognitive performance following an early-morning surgical procedure in which participants served as first surgeons. METHODS: Fifteen orthopaedic surgeons were recruited. Sleep was assessed under habitual conditions for a minimum of seven nights per participant, yielding a total of 186 nights. Sleep was monitored using actigraphy (MotionWatch 8, CamNTech) and sleep diaries. Pre- (T0) and post- (T1) early-morning surgery assessments included: handgrip strength test (K-grip, Kinvent), Stroop test (reaction time and accuracy), and maximal isometric knee extensor strength using a digital dynamometer (K-push, Kinvent). Subjective sleepiness and perceived exertion were evaluated using the Karolinska Sleepiness Scale and the Borg CR-10 scale. All early‑morning surgical procedures, in which participants acted as first operators, began at approximately 7:30 a.m. RESULTS: Across the 186 monitored nights, 139 nights showed short sleep duration (<7 hours), and 15 nights showed poor sleep efficiency (<85%). Eleven of the fifteen surgeons were classified as short sleepers (total sleep time < 7 hours), and one as a poor sleeper (sleep efficiency < 85%). Regarding differences between T0 and T1 assessments (mean surgery duration: 108.8 minutes), paired t-tests revealed a significant decrease in dominant upper limb isometric strength (pre: 47.16 ± 9.46 kg; post: 45.83 ± 9.04 kg; p < 0.001). No significant differences emerged in knee extensor strength, Stroop reaction time and accuracy, sleepiness and perceived exertion. CONCLUSION: Adequate sleep is essential for maintaining optimal physical and cognitive functioning. In the analysed sample, sleep duration was below recommended guidelines in 11 out of 15 orthopaedic surgeons. While a single early-morning surgical procedure did not impair cognitive reaction or decision-making performance, it was associated with a significant reduction in dominant upper limb strength. These findings highlight an important and understudied issue, underscoring the need for further research on sleep and performance in the surgeon population.
Read CV Stefano BorghiECSS Paris 2023: CP-MH19