Importance of radar gun inclusion during return-to-throwing rehabilitation following ulnar collateral ligament reconstruction in baseball pitchers: a simulation study.

BACKGROUND: Rehabilitation following elbow ulnar collateral ligament reconstruction in baseball pitchers relies on a progression of pitching activities to ensure protection and gradual strengthening of the reconstructed ligament. The purpose of this study was to determine the medial elbow torque associated with pitches at various effort levels and determine whether radar gun assistance improves players' abilities to accurately match partial-effort pitches with true references based on maximum pitch velocity. METHODS: Thirty-seven healthy high school and collegiate baseball pitchers were included in this study. Participants were excluded if they were injured, recovering from injury, or otherwise not currently pitching at full effort. Pitch parameters were collected using a validated wearable sensor. Participants threw 5 pitches at 50%, 75%, and 100% subjective effort. Pitchers then threw 5 pitches at 50% maximum velocity and 75% maximum velocity, as measured by a radar gun. RESULTS: Thirty-seven pitchers completed this study. Pitches thrown at 50% and 75% partial effort were significantly faster and generated higher elbow torque than did pitches thrown at 50% and 75% velocity, respectively (P < .001). A 10% decrease in percentage of maximum velocity was associated with a 13% decrease in percentage of maximum elbow torque (ß coefficient = 1.3, R2 = 0.81, P < .001). CONCLUSION: Pitchers generate higher-than-intended forces when throwing at 50% and 75% effort during a subjective partial-effort throwing protocol. Use of a radar gun to guide partial-effort throwing during throwing rehabilitation programs may protect the reconstructed elbow from excess medial torque.

Impact of ball weight on medial elbow torque in youth baseball pitchers.

HYPOTHESIS: Our hypothesis was that an increase in ball weight would result in an increase in medial elbow torque during the pitching motion. METHODS: Youth pitchers were recruited for this study and instructed to throw 5 maximum-effort fastballs from ground level using baseballs of 4 different weights: 85 g (3 oz), 113 g (4 oz), 142 g (5 oz), and 170 g (6 oz). The validated Motus sensor was used to assess medial elbow torque, arm speed, arm slot, and shoulder rotation for each pitch. Pitch velocity was measured using a radar gun. Relationships between baseball weight and pitching kinetics and/or kinematics were evaluated using linear mixed-effects analysis. An exit survey was conducted detailing the pitcher's evaluation of the ball weights used. RESULTS: A total of 19 youth baseball pitchers (average age, 11.8 ± 1.1 years; age range, 9-14 years) completed the study. For every 1-oz (28-g) increase in ball weight, ball velocity decreased 2.0 ± 0.1 mph (χ2 = 52.68, P < .001), medial elbow torque increased 0.92 ± 0.37 newton meters (χ2 = 5.36, P = .02), and arm speed decreased 8.52 ± 3.68 rpm (χ2 = 5.03, P = .02). Shoulder rotation and arm slot were not significantly impacted by ball weight (P > .05). Survey results indicated that the 85-g (3-oz) baseball was most favored (8 of 19 pitchers) and believed to result in the highest pitch velocity (15 of 19 pitchers). The 170-g (6-oz) baseball was least favored (17 of 19 pitchers) and believed to result in the slowest pitch velocity (18 of 19 pitchers). No adverse outcomes were reported with the use of any ball weight or the mobile sensor. CONCLUSION: Among youth pitchers, an increase in ball weight correlated with greater medial elbow torque, decreased pitch velocity, and decreased arm speed.

Effect of Fatigue on Medial Elbow Torque in Baseball Pitchers: A Simulated Game Analysis.

BACKGROUND: The incidence of overuse injury to the elbow among baseball pitchers continues to rise, despite extensive efforts at pitch count regulations and emphasis on proper throwing mechanics. PURPOSE: To determine if the medial elbow experiences increased torque levels as a baseball pitcher fatigues through the course of a simulated game. STUDY DESIGN: Descriptive laboratory study. METHODS: High school and collegiate baseball pitchers were recruited for this simulated game study. Each pitcher completed a simulated game consisting of 6 innings and a standardized pitching scheme of fastballs, curveballs, and changeups. In total, each pitcher threw 90 pitches. Fatigue was reported per inning with a visual analog scale, and pitch velocity was captured per pitch with a radar gun. Outcome measures were assessed with a validated mobile sensor and included medial elbow torque, arm speed, arm rotation, and arm slot. Linear and quadratic regression modeling was used to evaluate the relationship between pitcher fatigue and pitching kinematics. RESULTS: A total of 11 pitchers (mean age, 17.6 years; range, 15-20 years) completed the study. Visual analog scale fatigue scores increased 0.72 points per inning pitched ( P < .01, effect size = 0.64). Medial elbow torque also increased beyond inning 3, with an increase of 0.84 N·m each inning ( P < .01, effect size = 0.08), while pitch velocity decreased (0.28 mph per inning, P < .01, effect size = 0.27). Fastballs generated the greatest amount of medial elbow torque (49.3 ± 1.4 N·m, P < .01, effect size = 0.24). There were no differences in arm rotation ( P = .42) or arm speed ( P = .80) as the game progressed. However, arm slot decreased with each successive inning (0.73° on average per inning, P = .03, effect size = 0.12). No adverse outcomes were noted with use of the mobile sensor. CONCLUSION: In this simulated game analysis, pitchers experienced increased fatigue after each successive inning. While the average pitch velocity declined with each successive inning, the torque on the medial elbow increased after inning 3. These findings signify a possible relationship between fatigue and injury risk.

Three-dimensional printing improves osteochondral allograft placement in complex cases.

The use of three-dimensional (3D) printing has seen a vast expansion over recent years, with an increased application for its use in orthopaedics. This report details the use of 3D printing technology to aid in the treatment of a medial femoral condyle osteochondral defect in a 26-year-old female who had previously undergone a failed autograft procedure. A preoperative computed tomography scan of the knee and chondral defect was used to generate a 3D printed, one-to-one scale replica of the distal femur. This replica was then used to size a patient-specific allograft plug for the osteochondral transplantation procedure. The patient recovered well, and 1 year postoperatively the allograft was well incorporated into the medial femoral condyle and healed. This report illustrates the advantages of using a 3D printed model to allow for tactile feedback and improved visualization that will allow for improved understanding of complex surgical procedures.Level of evidence V.

Preoperative Tibial Subchondral Bone Marrow Lesion Patterns and Associations With Outcomes After Isolated Meniscus Allograft Transplantation.

BACKGROUND: The association between preoperative tibial subchondral bone marrow lesion (BML) patterns and outcomes after isolated meniscus allograft transplantation (MAT) are unknown. PURPOSE: To determine (1) if a superior classification means exists (ie, high interrater reliability [IRR]) for grading tibial subchondral BML before isolated MAT and (2) whether quality and/or severity of preoperative tibial subchondral BML patterns was associated with clinical outcomes and/or failure rates after isolated MAT. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: All patients who underwent isolated MAT with a single surgeon between October 2006 and February 2017 were identified. Three means were evaluated to quantify the degree of subchondral BML in the affected tibial-sided compartment: Welsch et al, based on maximum diameter of the lesion; Costa-Paz et al, based on appearance and location of the lesion; and Filardo et al, based on severity of findings. IRR was generated and compared among the 3 classifications. The preoperative magnetic resonance imaging (MRI) subchondral BML grading scheme with the highest IRR was then used to assess for associations with postoperative outcomes for those patients with >2-year follow-up, per a Spearman correlation matrix with each reviewer's grades. RESULTS: In total, 60 MRI scans were available for subchondral BML grading. Grader 1 identified the presence of subchondral BML in the tibia of the affected compartment in 40 (66.7%) of the available MRI scans, as compared with 38 (63.3%) for grader 2. The calculated IRRs with the Welsch et al and Costa-Paz et al classifications were rated "strong/almost perfect" agreement. A significant correlation was demonstrated between grader 1 with the Welsch et al grading scheme and outcome measures of KOOS pain (Knee injury and Osteoarthritis Outcome Score; negative correlation, P = .05), WOMAC pain (Western Ontario and McMaster Universities Osteoarthritis Index; positive correlation, P = .026), and Marx Activity Rating Scale (negative correlation, P = .019). A significant correlation was demonstrated between grader 2 with the Costa-Paz et al grading scheme and postoperative satisfaction (positive correlation, P = .018). There were no significant differences in survivorship based on gradings. CONCLUSION: Nearly two-thirds of patients who undergo isolated MAT have subchondral BML on preoperative MRI. Our findings suggest that increasing BML size (Welsch et al) is correlated with worse postoperative pain measures (KOOS pain, WOMAC pain) and worse activity ratings (Marx Activity Rating Scale). Additionally, increasing disruption or depression of the normal contour of the cortical surface, with or without lesion contiguity with the subjacent articular surface (Costa-Paz et al), is correlated with greater postoperative satisfaction.

Assessment of Elbow Torque and Other Parameters During the Pitching Motion: Comparison of Fastball, Curveball, and Change-up.

PURPOSE: To assess the precision of a new wearable device in detecting medial elbow torque during the pitching motion in competitive baseball pitchers and to determine the differences in torque across pitch types and thrower demographic characteristics. METHODS: High school and collegiate baseball pitchers were recruited from August 1, 2016, to January 31, 2017, through direct request by athletic trainers and coaches. Body dimensions and throwing arm measurements of the participants were collected. The sensor was positioned directly over the medial elbow and pitchers were instructed to throw 8 fastballs, 8 curveballs, and 8 change-ups in a standard, randomized sequence. The sensor reported elbow torque, arm speed, arm slot, and shoulder rotation, whereas a radar gun measured peak ball velocity. Precision was calculated by measuring outlier rate, and mixed model regression analysis was performed to detect differences in throwing biomechanics among pitch types. RESULTS: In total, 37 competitive baseball pitchers were included in the study. The device had a precision of 96.9% for fastballs, 96.9% for curveballs, and 97.9% for change-ups. The device was sensitive enough to distinguish pitches according to elbow torque, arm speed, arm slot, and shoulder rotation. Fastballs caused the greatest relative torque across the medial elbow (average = 45.56 N m), compared with change-ups (43.77 N m; P = .006) and curveballs (43.83 N m; P = .01). Ball velocity contributed most to medial elbow torque (P = .003), followed by elbow circumference (P = .021), where smaller elbow circumference predicted greater medial elbow torque. CONCLUSIONS: The sensor is a precise and reproducible device for measuring torque across the medial elbow, as well as additional parameters of arm speed, arm slot, and shoulder rotation. Torque was significantly relatively higher in fastballs than curveballs and change-ups. LEVEL OF EVIDENCE: Level III, comparative study.

The Effect of Platelet-Rich Fibrin Matrix at the Time of Gluteus Medius Repair: A Retrospective Comparative Study.

PURPOSE: To evaluate the effect of platelet-rich fibrin matrix (PRFM) on outcomes after surgical repair of gluteus medius tendons. METHODS: This is a retrospective review of prospectively collected data comparing patients who underwent gluteus medius repair with PRFM and patients without PRFM. Preoperative characteristics, intraoperative characteristics, and postoperative outcomes at a minimum of 1 year were recorded. Statistical analysis was performed using a multivariate analysis of variance to test for differences in continuous demographic variables and postoperative-only scores between patient groups, χ2 tests were performed for categorical variables, and a repeated-measures analysis of variance was performed to test for the effects of PRFM. We also assessed for interobserver variation in grading adductor tendon tears. RESULTS: In total, the series of gluteus medius repairs without PRFM included 29 patients (25 women and 4 men, 15 right and 4 left) with a mean age of 63.09 ± 12.0 years. The series of gluteus medius repairs with PRFM included 18 patients (16 women and 2 men, 6 right and 12 left) with a mean age of 60.26 ± 8.8 years. There were no differences in patient preoperative variables or intraoperative characteristics. Although there was a significant effect of surgical intervention on the visual analog scale for pain, Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Specific, and modified Harris Hip Score, the use of PRFM had no significant effect on outcome. Linear models showed a significant positive effect of PRFM on only postoperative Short Form 12 Physical and International Hip Outcome Tool 12 scores. CONCLUSIONS: PRFM augmentation does not appear to have an effect on gluteus medius tendon repair in terms of pain or clinical evidence of retears but may have a role in improving subjective outcomes of overall and hip-specific physical functioning. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Patient-Reported Outcomes Measurement Information System and Legacy Patient-Reported Outcome Measures in the Field of Orthopaedics: A Systematic Review.

PURPOSE: To compare Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) with legacy patient-reported outcome measures with regard to correlations, ease of use, and quality criteria for orthopaedic conditions. METHODS: A systematic search of the PubMed/MEDLINE database was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify published articles that referenced the various PROMIS PF measures. Three authors independently reviewed selected studies. The search returned 130 studies, 44 of which underwent review. Of these, 18 were selected for inclusion. A general linear model and paired t-tests were used to assess for differences between legacy patient-reported outcome measures and PROMIS. RESULTS: The combined sample size of all articles yielded 3,047 total patients. Overall, PROMIS PF measures and legacy scores showed strong correlations (range: 0.59-0.83) when evaluating upper extremity, lower extremity, and spine patients. PROMIS questionnaires (6.04, standard error [SE] = 0.7) have significantly fewer questions than legacy forms (24.27, SE = 4.36). In lower extremity studies, the PROMIS PF (100.14 seconds, SE = 28.41) forms were completed in significantly less time (P = .03) than legacy forms (243.70 seconds, SE = 45.8). No significant difference was found between the reliabilities of the 2 types of measures. CONCLUSIONS: PROMIS PF scores correlate strongly, particularly in lower extremity patients, with some of the most commonly used legacy measures in orthopaedics. PROMIS can be administered quicker and applied to a broader patient population while remaining highly reliable. LEVEL OF EVIDENCE: Level IV, systematic review of Level I-IV evidence.

Bottom-up and trait-mediated effects of resource quality on amphibian parasitism.

Leaf litter subsidies are important resources for aquatic consumers like tadpoles and snails, causing bottom-up effects on wetland ecosystems. Recent studies have shown that variation in litter nutritional quality can be as important as litter quantity in driving these bottom-up effects. Resource subsidies likely also have indirect and trait-mediated effects on predation and parasitism, but these potential effects remain largely unexplored. We generated predictions for differential effects of litter nutrition and secondary polyphenolic compounds on tadpole (Lithobates sylvatica) exposure and susceptibility to Ribeiroia ondatrae, based on ecological stoichiometry and community-ecology theory. We predicted direct and indirect effects on key traits of the tadpole host (rates of growth, development and survival), the trematode parasite (production of the cercaria infective stages) and the parasite's snail intermediate host (growth and reproduction). To test these predictions, we conducted a large-scale mesocosm experiment using a natural gradient in the concentrations of nutrients (nitrogen) and toxic secondary compounds (polyphenolics) of nine leaf litter species. To differentiate between effects on exposure vs. susceptibility to infection, we included multiple infection experiments including one with constant per capita exposure. We found that increased litter nitrogen increased tadpole survival, and also increased cercaria production by the snail intermediate hosts, causing opposing effects on tadpole per capita exposure to trematode infection. Increased litter polyphenolics slowed tadpole development, leading to increased infection by increasing both their susceptibility to infection and the length of time they were exposed to parasites. Based on these results, recent shifts in forest composition towards more nitrogen-poor litter species should decrease trematode infection in tadpoles via density- and trait-mediated effects on the snail intermediate hosts. However, these shifts also involve increased abundance of litter species with high polyphenolic levels, which should increase trematode infection via trait-mediated effects on tadpoles. Future studies will be needed to determine the relative strength of these opposing effects in natural wetland communities. [Correction added after online publication on 5 January 2017: wording changed to 'which should increase trematode infection via trait-mediated effects on tadpoles'.].

Ontogenetic changes in sensitivity to nutrient limitation of tadpole growth.

According to ecological stoichiometry (ES), the growth of a consumer with abundant resources should increase as body and resource stoichiometry become more similar. However, for organisms with complex life cycles involving distinct changes in biology, nutrient demands might change in response to ontogenetic changes in body stoichiometry. Tadpole growth and development has been found to be largely nitrogen (N) limited, as predicted for organisms developing N-rich tissues like muscle. However, tadpole metamorphosis includes periods of rapid development of phosphorus (P)-rich bones in preparation for a terrestrial lifestyle. We hypothesized that tadpole growth and development will exhibit variable nutrient demands during different stages of ontogeny, due to predictable changes in body tissue stoichiometry. To test this, we raised tadpoles on four diets with varying N:P ratios and assessed growth and developmental rates. Specifically, we predicted that tadpoles would be sensitive to N limitation throughout ontogeny (consistent with previous studies), but also sensitive to P limitation during the process of long-bone ossification. Consistent with our prediction, tadpole growth rates and development were sensitive to N limitation throughout ontogeny. Increased dietary N led to a shorter time to metamorphosis and a larger mass at metamorphosis. Also as predicted, growth rates were sensitive to both N and P during the period of peak bone ossification, indicative of co-limitation. These results indicate that P limitation changes through tadpole ontogeny consistent with, and can be predicted by, shifts in body tissue stoichiometry. Future studies should investigate whether ontogenetic shifts in tadpole P limitation lead to seasonal shifts in wetland nutrient cycling.

Host and parasite thermal acclimation responses depend on the stage of infection.

Global climate change is expected to alter patterns of temperature variability, which could influence species interactions including parasitism. Species interactions can be difficult to predict in variable-temperature environments because of thermal acclimation responses, i.e. physiological changes that allow organisms to adjust to a new temperature following a temperature shift. The goal of this study was to determine how thermal acclimation influences host resistance to infection and to test for parasite acclimation responses, which might differ from host responses in important ways. We tested predictions of three, non-mutually exclusive hypotheses regarding thermal acclimation effects on infection of green frog tadpoles (Lithobates clamitans) by the trematode parasite Ribeiroia ondatrae with fully replicated controlled-temperature experiments. Trematodes or tadpoles were independently acclimated to a range of 'acclimation temperatures' prior to shifting them to new 'performance temperatures' for experimental infections. Trematodes that were acclimated to intermediate temperatures (19-22 °C) had greater encystment success across temperatures than either cold- or warm-acclimated trematodes. However, host acclimation responses varied depending on the stage of infection (encystment vs. clearance): warm- (22-28 °C) and cold-acclimated (13-19 °C) tadpoles had fewer parasites encyst at warm and cold performance temperatures, respectively, whereas intermediate-acclimated tadpoles (19-25 °C) cleared the greatest proportion of parasites in the week following exposure. These results suggest that tadpoles use different immune mechanisms to resist different stages of trematode infection, and that each set of mechanisms has unique responses to temperature variability. Our results highlight the importance of considering thermal responses of both parasites and hosts when predicting disease patterns in variable-temperature environments.

Ecological stoichiometry quantitatively predicts responses of tadpoles to a food quality gradient.

Ecological stoichiometry (ES) uses elemental ratios and mass balance to explain organismal growth, an important parameter in ecological systems. In this study, we tested quantitative predictions of the ES "minimal model" for the growth rates of two tadpole species (wood frogs, Lithobates sylvaticus and American toads, Anaxyrus americanus), by manipulating light and the quality of a leaf litter mixture in a seminatural mesocosm experiment. We predicted that wood frogs, which consume leaf litter as a resource, would respond more strongly to leaf litter quality than toads, which forage on periphyton and algae. The ES minimal model, parameterized from literature values, provided strikingly accurate quantitative predictions of nonlinear wood frog growth patterns across gradients of leaf litter quality, both in this experiment and when applied to previously published data on wood frog growth responses to various leaf litter species. In contrast, toad growth was best explained by the biomass of periphyton, which was driven primarily by light availability and only indirectly influenced by litter-derived soluble polyphenols. This study demonstrates the power of ES to predict organism growth rates, and highlights potential applications of this theory to predicting population- and community-level responses to changing forest environments.

Leaf litter resource quality induces morphological changes in wood frog (Lithobates sylvaticus) metamorphs.

For organisms that exhibit complex life cycles, resource conditions experienced by individuals before metamorphosis can strongly affect phenotypes later in life. Such resource-induced effects are known to arise from variation in resource quantity, yet little is known regarding effects stemming from variation in resource quality (e.g., chemistry). For larval anurans, we hypothesized that variation in resource quality will induce a gradient of effects on metamorph morphology. We conducted an outdoor mesocosm experiment in which we manipulated resource quality by rearing larval wood frogs (Lithobates sylvaticus) under 11 leaf litter treatments. The litter species represented plant species found in open- and closed-canopy wetlands and included many plant species of current conservation concern (e.g., green ash, common reed). Consistent with our hypothesis, we found a gradient of responses for nearly all mass-adjusted morphological dimensions. Hindlimb dimensions and gut mass were positively associated with litter nutrient content and decomposition rate. In contrast, forelimb length and head width were positively associated with concentrations of phenolic acids and dissolved organic carbon. Limb lengths and widths were positively related with the duration of larval period, and we discuss possible hormonal mechanisms underlying this relationship. There were very few, broad differences in morphological traits of metamorphs between open- and closed-canopy litter species or between litter and no-litter treatments. This suggests that the effects of litter on metamorph morphology are litter species-specific, indicating that the effects of changing plant community structure in and around wetlands will largely depend on plant species composition.