Joseph J. Crisco

Quantitative kinematic tracking of in vivo skeletal structures efficiently and with high temporal resolution is important to a wide range of questions in b

Non-wood baseball bats are widely used in college as they are generally considered to outperform wood baseball bats. However, the field performance of non-wood baseball bats has not been previously reported. The aim of this study was to determine the field performance of non-wood baseball bats. Non-wood bat performance was then compared to previous studies of wood bat performance. During the 2024 season, 3164 hits at a Division I baseball field were analyzed. Pitched ball speed, batted ball speed, bat impact location, and bat speed were computed. Mean bat speed was 64 mph (29 m/s). Mean impact location was 4.3 inches (0.11 m) from the tip of the bat. These bat swings resulted in a mean batted ball speed of 83.5 mph (37.3 m/s). At a bat speed of 63.6 ± 2.5 mph (28.4 ± 1.1 m/s), the top 2% batted ball speeds were 102.1 mph (45.6 m/s), as compared to 92.9 mph (41.5 m/s) with wood baseball bats. The sweet spot for non-wood bats was located 2″ to 10.5″ (0.05–0.27 m) from the bat tip. This width for non-wood bats was substantially greater than the sweet spot for wood bats, which was located from 3″ to 7.5″ (0.08–0.19 m) from the bat tip. This field study found that modern non-wood bats used at the collegiate level substantially outperformed wood baseball bats in terms of batted ball speeds at a given bat speed and the width of the sweet spot.

Biplanar videoradiography (BVR) is a gold-standard technique for quantifying in vivo bone motion, yet the influence of x-ray image resolution on pose estimation accuracy remains unexplored. This study investigates how downsampling x-ray images impacts model-based pose estimation, using high-speed BVR data from a participant with implanted tantalum beads. Images were downsampled from 2048 × 2048 to 512 × 512 using bicubic and nearest-neighbour interpolation. Across multiple bones and varying perturbation levels, downsampling significantly reduced rotational and translational errors when compared to full-resolution images for both interpolation results. Bicubic interpolation led to slightly improved pose accuracy for certain bones, demonstrating enhanced edge clarity that benefits the optimisation algorithm. Pose estimates for full-resolution images exhibited more outliers and greater variability for all the bones investigated. These findings highlight that downsampling images improves pose estimation accuracy even for challenging anatomical areas such as the ankle. We recommend bicubic downsampling to 512 × 512 pixels as a best practice for BVR tracking of the ankle complex, when using both automated optimisation and manual workflows.

Hemiarthroplasty addresses joint damage confined to one side, preserving native cartilage and bone, but accelerated degeneration of the opposing cartilage can compromise outcomes. This systematic review should clarify whether coefficient of friction (COF) reliably predicts cartilage wear when evaluating hemiarthroplasty bearing materials (HBMs). Thirty in vitro studies reporting both outcomes were identified. Data were extracted on COF, wear, and testing parameters, and wear was standardized using a 0–4 rubric to enable cross-study comparison. Three analytical approaches were applied: linear model fits, Pearson’s correlations, and predictive modeling. Reported COFs increased significantly with testing time, while contact stress and sliding velocity showed variable associations with COF. Predictive models for cobalt–chromium (CoCr), the most studied HBM, showed moderate fit, suggesting that mechanical parameters explain only part of COF variability. For wear, linear models showed poor fit with COF, but correlations indicated positive associations with contact stress. Inconsistent effects of velocity and distance were found. Predictive models explained little variability. Together, these findings suggest that outcomes are strongly influenced by testing conditions, lubricants, and HBM selection, and COF alone is an unreliable predictor of cartilage wear in an experimental setting.

Hemiarthroplasty is commonly used to treat damage localized to one side of a synovial joint, maximally preserving the patient's opposing healthy bone and cartilage; however, challenges remain due to accelerated wear of the cartilage articulating with the implant surface. This scoping review summarized investigations of hemiarthroplasty bearing materials (HBMs) utilizing animal models. The review focused on HBMs tested, animal models used, duration of animal survival, and outcome assessments (e.g., gait analysis, image analysis, histological staining, and cartilage scoring). The initial search was designed to broadly capture all studies evaluating HBMs articulating against articular cartilage. A total of 1798 studies were identified, which after screening yielded 72 that met the inclusion criteria. Of these, 24 were classified as in vivo and were included in this review. The HBMs evaluated included metals (63%), hard and soft polymers (33%), ceramics (17%), and synthetic carbons (17%). HBMs were predominantly studied in canines (46%), rabbits (25%), and sheep (21%), with survival durations from 2 to 104 weeks. Outcome assessment of cartilage wear varied across studies and histological staining was performed in all studies with the most common stains being Safranin‐O (58%) and Hematoxylin and Eosin (54%). Commonly used cartilage scoring systems were Mankin and Modified Mankin (38%); however, among all studies, scales and sub‐categories for scoring criteria varied drastically. While similarities were identified with respect to HBMs, animal models, and some outcome measures, the diversity of testing methodologies and lack of comparative evaluations limited the ability to identify the best practice for evaluating HBM performance.

Hemiarthroplasty is used to treat joint damage confined to one side, aiming to preserve the remaining healthy cartilage and bone while addressing conditions like femur fractures and osteonecrosis; however, challenges persist due to cartilage wear and inconsistent clinical outcomes. This scoping review evaluates in vitro studies on hemiarthroplasty bearing materials (HBM), focusing on the HBM tested, cartilage specimens, experimental setups, outcome variables, and the comparability of results. Of 1798 identified studies, 72 met the inclusion criteria, with 48 classified as in vitro. HBMs tested included metals (42%) and soft polymers (30%) and 45% of studies utilized multiple distinct HBMs. Cartilage specimens were predominantly bovine (65%), mostly from the tibial‐femoral joint (69%). The two most common experimental set ups were tribometers (75%) and simulators (25%) both using commercial and custom‐built rigs. Tribometer configurations included pin‐on‐disc and pin‐on‐plate models and simulators highlighted ball‐on‐joint set ups. Tribometer motions included linear reciprocating (62%) or multidirectional reciprocating (24%). Input parameters included contact stress (8.8 kPa to 23.3 MPa, mean 2.1 MPa), velocity (0.5‐100 mm/s, mean 16.46 mm/s), testing duration (0.03–33.8 h, mean 5.4 h), and distance (5.4 cm to 9000 m, mean 393 m). Simulators used inputs of loads ranging from 25 N to 1.5 kN, 500 to 500,000 cycles and a variety of flexion‐extension profiles together with secondary motions. Lubricants were mostly bovine calf serum (38%) and saline‐based solutions (21%). Outcome variables mainly included coefficient of friction and damage to cartilage and/or HBM, but the methods to assess these outputs varied. Methodological differences and inconsistent reporting of outcomes limited the ability to draw firm conclusions about the relative performance of HBMs.

The development of innovative small bone replacements for the human wrist has been partially limited by the lack of a suitable preclinical animal model. This study explores the feasibility of using the Yucatan minipig (YMP) as a preclinical model for small bone replacement. Implants for the radial carpal bone (RCB), homologous to the human scaphoid, were developed for a pilot in vivo animal study. RCB size (volume, bounding box dimensions) was quantified ( n = 35), and relationships between animal age, weight, and RCB volume were investigated. Bounding box dimensions were also analyzed relative to RCB volume. A mean-shaped RCB model was generated using ShapeWorks Studio and scaled to create a set of implants. These implants were evaluated in a pilot in vivo study, where the distances between the explanted bone surface and both the predicted and surgeon-selected implant surfaces were recorded for each animal. Predicted implant distances (0.8 ± 0.2 mm), were larger ( p < 0.001) than surgeon-selected implant distances (0.4 ± 0.1 mm) in three animals. In one animal, the predicted implant distances (0.3 ± 0.2 mm) were smaller ( p < 0.0001) than the surgeon-selected implant distances (0.5 ± 0.3 mm). The set of implants generated provided the surgeon with options suitable for the range of animals in the in vivo study. This study presents a novel approach to generating small bone replacements by scaling a mean-shaped bone in a porcine model and further evaluates the YMP as a preclinical model for small bone replacement in the human wrist.