Jessica M. Deneweth

Heterogeneity of tibial plateau cartilage in response to a physiological compressive strain rate.

Knowledge of the extent to which tibial plateau cartilage displays non‐uniform mechanical topography under physiologically relevant loading conditions is critical to evaluating the role of biomechanics in knee osteoarthritis. Cartilage explants from 21 tibial plateau sites of eight non‐osteoarthritic female cadaveric knees (age: 41–54; BMI: 14–20) were tested in unconfined compression at 100% strain/s. The elastic tangent modulus at 10% strain (E10%) was calculated for each site and averaged over four geographic regions: not covered by meniscus (I); covered by meniscus—anterior (II); covered by meniscus—exterior (III); and covered by meniscus—posterior (IV). A repeated‐measures mixed model analysis of variance was used to test for effects of plateau, region, and their interaction on E10%. Effect sizes were calculated for each region pair. E10% was significantly different (p < 0.05) for all regional comparisons, except I–II and III–IV. The regional pattern of variation was consistent across individuals. Moderate to strong effect sizes were evident for regional comparisons other than I–II on the lateral side and III–IV on both sides. Healthy tibial cartilage exhibits significant mechanical heterogeneity that manifests in a common regional pattern across individuals. These findings provide a foundation for evaluating the biomechanical mechanisms of knee osteoarthritis.

Grading the Functional Movement Screen : a Comparison of Manual (Real-Time) and Objective Methods

Abstract Whiteside, D, Deneweth, JM, Pohorence, MA, Sandoval, B, Russell, JR, McLean, SG, Zernicke, RF, and Goulet, GC. Grading the Functional Movement Screen: a comparison of manual (real-time) and objective methods. J Strength Cond Res 30(4): 924–933, 2016—Although intertester and intratester reliability have been common themes in Functional Movement Screen (FMS) research, the criterion validity of manual grading is yet to be comprehensively examined. This study compared the FMS scores assigned by a certified FMS tester to those measured by an objective inertial-based (IMU) motion capture system. Eleven female division I collegiate athletes performed 6 FMS exercises and were manually graded by a certified tester. Explicit kinematic thresholds were formulated to correspond to each of the grading criteria for each FMS exercise and then used to grade athletes objectively using the IMU data. The levels of agreement between the 2 grading methods were poor in all 6 FMS exercises and implies that manual grading of the FMS may be confounded by vague grading criteria. Evidently, more explicit grading guidelines are needed to improve the uniformity and accuracy of manual FMS grading and also facilitate the use of objective measurement systems in the grading process. Contrary to the approach that has been adopted in several previous studies, the potential for subjective and/or inaccurate FMS grading intimates that it may be inappropriate to assume that manual FMS grading provides a valid measurement tool. Consequently, the development and criterion validation of uniform grading procedures must precede research attempting to link FMS performance and injury rates. With manual grading methods seemingly susceptible to error, the FMS should be used cautiously to direct strength and/or conditioning programs.

Femoroacetabular Impingement in Elite Ice Hockey Goaltenders Etiological Implications of On-Ice Hip Mechanics

Background: Femoroacetabular impingement (FAI) is particularly prevalent in ice hockey. The butterfly goalie technique is thought to involve extreme ranges of hip motion that may predispose goaltenders to FAI. Purpose: To quantify hip mechanics during 3 common goaltender movements and interpret their relevance to the development of FAI. Study Design: Descriptive laboratory study. Methods: Fourteen collegiate and professional goaltenders performed skating, butterfly save, and recovery movements on the ice. Hip mechanics were compared across the 3 movements. Results: The butterfly did not exhibit the greatest range of hip motion in any of the 3 planes. Internal rotation was the only hip motion that appeared close to terminal in this study. When subjects decelerated during skating—shaving the blade of their skate across the surface of the ice—the magnitude of peak hip internal rotation was 54% greater than in the butterfly and 265% greater than in the recovery. No movement involved levels of concomitant flexion, adduction, and internal rotation that resembled the traditional impingement (FADIR) test. Conclusion: The magnitude of internal rotation was the most extreme planar hip motion (relative to end-range) recorded in this study (namely during decelerating) and appeared to differentiate this cohort from other athletic populations. Consequently, repetitive end-range hip internal rotation may be the primary precursor to symptomatic FAI in hockey goaltenders and provides the most plausible account for the high incidence of FAI in these athletes. Resection techniques should, therefore, focus on enhancing internal rotation in goaltenders, compared with flexion and adduction. While the butterfly posture can require significant levels of hip motion, recovering from a save and, in particular, decelerating during skating are also demanding on goaltenders’ hip joints. Therefore, it appears critical to consider and accommodate a variety of sport-specific hip postures to comprehensively diagnose, treat, and rehabilitate FAI.

Evaluation of hyperelastic models for the non-linear and non-uniform high strain-rate mechanics of tibial cartilage

Accurate modeling of the high strain-rate response of healthy human knee cartilage is critical to investigating the mechanism(s) of knee osteoarthritis and other cartilage disorders. Osteoarthritis has been suggested to originate from regional shifts in joint loading during walking and other high strain-rate physical activities. Tibial plateau cartilage under compression rates analogous to walking exhibits a non-linear and location-dependent mechanical response. A constitutive model of cartilage that efficiently predicts the non-linear and non-uniform high strain-rate mechanics of tibial plateau cartilage is important for computational studies of osteoarthritis development. A transversely isotropic hyperelastic statistical chain model has been developed. The models ability to simulate the 1-strain/s unconfined compression response of healthy human tibial plateau articular cartilage has been assessed, along with two other hyperelastic statistical chain models. The transversely isotropic model exhibited a superior fit to the non-linear stress-strain response of the cartilage. Furthermore, the model maintained its predictive capability after being reduced from four degrees of freedom to one. The remaining material constant of the model, which represented the local collagen density of the tissue, demonstrated a regional dependence in close agreement with physiological variations in collagen density and cartilage modulus in human knees. The transversely isotropic eight-chain network of freely jointed chains with a regionally-dependent material constant represents a novel and efficient approach for modeling the complex response of human tibial cartilage under high strain-rate compression. The anisotropy and microstructural variations of the cartilage matrix dictate the models response, rendering it directly applicable to computational modeling of the human knee.

Ball flight kinematics, release variability and in-season performance in elite baseball pitching

The purpose of this study was to quantify ball flight kinematics (ball speed, spin rate, spin axis orientation, seam orientation) and release location variability in the four most common pitch types in baseball and relate them to in‐season pitching performance. Nine NCAA Division I pitchers threw four pitching variations (fastball, changeup, curveball, and slider) while a radar gun measured ball speed and a 600‐Hz video camera recorded the ball trajectory. Marks on the ball were digitized to measure ball flight kinematics and release location. Ball speed was highest in the fastball, though spin rate was similar in the fastball and breaking pitches. Two distinct spin axis orientations were noted: one characterizing the fastball and changeup, and another, the curveball and slider. The horizontal release location was significantly more variable than the vertical release location. In‐season pitching success was not correlated to any of the measured variables. These findings are instructive for inferring appropriate hand mechanics and spin types in each of the four pitches. Coaches should also be aware that ball flight kinematics might not directly relate to pitching success at the collegiate level. Therefore, talent identification and pitching evaluations should encompass other (e.g., cognitive, psychological, and physiological) factors.

On-Ice Functional Assessment of an Elite Ice Hockey Goaltender After Treatment for Femoroacetabular Impingement

Background: Femoroacetabular impingement (FAI) is a major cause of performance inhibition in elite-level athletes. The condition is characterized by pain, osseous abnormalities such as an increased alpha angle, and decreased range of motion at the affected hip joint. Arthroscopic surgical decompression is useful in reshaping the joint to alleviate symptoms. Functional kinematic outcomes of sport-specific movements after surgery, however, are presently unknown. Hypothesis: The ability of an ice hockey goaltender to execute sport-specific movements would improve after arthroscopic surgery. Study Design: Clinical research. Level of Evidence: Level 5. Methods: An ice hockey goaltender was evaluated after arthroscopic correction of FAI on the symptomatic hip. Passive range of motion and radiographic parameters were assessed from a computed tomography–derived 3-dimensional model. An on-ice motion capture system was also used to determine peak femoral shock and concurrent hip joint postures during the butterfly and braking movements. Results: Maximum alpha angles were 47° in the surgical and 61° in the nonsurgical hip. Internal rotation range of motion was, on average, 23° greater in the surgically corrected hip compared with contralateral. Peak shock was lower in the surgical hip by 1.39 g and 0.86 g during butterfly and braking, respectively. At peak shock, the surgical hip demonstrated increased flexion, adduction, and internal rotation for both tasks (butterfly, 6.1°, 12.3°, and 30.8°; braking, 14.8°, 19.2°, and 41.4°). Conclusion: On-ice motion capture revealed performance differences between hips after arthroscopic surgery in a hockey goaltender. Range of motion and the patient’s subjective assessment of hip function were improved in the surgical hip. While presenting as asymptomatic, it was discovered that the contralateral hip displayed measurements consistent with FAI. Therefore, consideration of preemptive treatment in a presently painless hip may be deemed beneficial for young athletes seeking a long career in sport, and future work is needed to determine the costs and benefits of such an approach. Clinical Relevance: Surgical treatment of symptomatic FAI can achieve pain relief and improved kinematics of the hip joint with athletic activities. Additional studies are necessary to determine whether improved kinematics enhance the longevity of the native hip and alter the progression of osteoarthritic changes in those with asymptomatic FAI deformity.

Individual-specific determinants of successful adaptation to minimal and maximal running shoes

Minimalist shoes have been touted as a panacea for preventing running-related injuries, although evidence is inconclusive (Ryan, Elashi, Newsham-West, & Taunton, 2014). Maximalist shoes, with greater than normal midsole thickness, have been introduced in response, but little work has investigated their success in preventing injuries. For both maximal and minimal footwear, it is likely that the wholesale approach to prescription has limited their successful adoption. Prescription of traditional running footwear often relies on the paradigm of pronation, although this is ineffective for preventing injuries (Nielsen et al., 2014). We hypothesize that individual-specific characteristics, other than pronation, such as dynamic foot stiffness, should be considered for prescribing running footwear.

Position-Specific Hip and Knee Kinematics in NCAA Football Athletes

Background: Femoroacetabular impingement is a debilitating hip condition commonly affecting athletes playing American football. The condition is associated with reduced hip range of motion; however, little is known about the range-of-motion demands of football athletes. This knowledge is critical to effective management of this condition. Purpose: To (1) develop a normative database of game-like hip and knee kinematics used by football athletes and (2) analyze kinematic data by playing position. The hypothesis was that kinematics would be similar between running backs and defensive backs and between wide receivers and quarterbacks, and that linemen would perform the activities with the most erect lower limb posture. Study Design: Descriptive laboratory study. Methods: Forty National Collegiate Athletic Association (NCAA) football athletes, representing 5 playing positions (quarterback, defensive back, running back, wide receiver, offensive lineman), executed game-like maneuvers while lower body kinematics were recorded via optical motion capture. Passive hip range of motion at 90° of hip flexion was assessed using a goniometer. Passive range of motion, athlete physical dimensions, hip function, and hip and knee rotations were submitted to 1-way analysis of variance to test for differences between playing positions. Correlations between maximal hip and knee kinematics and maximal hip kinematics and passive range of motion were also computed. Results: Hip and knee kinematics were similar across positions. Significant differences arose with linemen, who used lower maximal knee flexion (mean ± SD, 45.04° ± 7.27°) compared with running backs (61.20° ± 6.07°; P < .001) and wide receivers (54.67° ± 6.97°; P = .048) during the cut. No significant differences were found among positions for hip passive range of motion (overall means: 102° ± 15° [flexion]; 25° ± 9° [internal rotation]; 25° ± 8° [external rotation]). Several maximal hip measures were found to negatively correlate with maximal knee kinematics. Conclusion: A normative database of hip and knee kinematics utilized by football athletes was developed. Position-specific analyses revealed that linemen use smaller joint motions when executing dynamic tasks but do not demonstrate passive range of motion deficits compared with other positions. Clinical Relevance: Knowledge of requisite game-like hip and knee ranges of motion is critical for developing goals for nonoperative or surgical recovery of hip and knee range of motion in the symptomatic athlete. These data help to identify playing positions that require remedial hip-related strength and conditioning protocols. Negative correlations between hip and knee kinematics indicated that constrained hip motion, as seen in linemen, could promote injurious motions at the knee.

HUMAN TIBIAL CARTILAGE REVEALS NON-LINEAR AND NON-UNIFORM REGIONAL TOPOGRAPHY UNDER PHYSIOLOGICAL LOADING RATES

Nearly 3% of individuals worldwide experience pain, immobility, and compromised quality of life due to knee osteoarthritis (OA)1. It has been widely accepted that joint mechanics play a critical role in the initiation and progression of knee OA2. A shift away from the normal joint motion, for example due to injury or malalignment, is believed to produce an abnormal pattern of cartilage loading that creates unusual and damaging stresses within the tissue. Accurate knowledge of cartilage’s normal mechanical response to physiological loading—and particularly the regional dependence of this response—is critical to successfully testing this theory. To our knowledge, little is known about the regionally-dependent mechanical response of healthy human tibial cartilage under physiological loading conditions. There is also a compelling need for more accurate cartilage data to be integrated into computational simulations of the knee joint. Hence, the purpose of this study was two-fold:1) to characterize the typical stress-strain response of tibial cartilage at 21 locations across the tibial plateau when subjected to loading representative of human walking, and2) to demonstrate that these 21 sites can be reduced to a small number of regions displaying significantly different average moduli.Copyright