Currently Available Large Language Models Do Not Provide Musculoskeletal Treatment Recommendations That Are Concordant With Evidence-Based Clinical Practice Guidelines.

PURPOSE: To determine whether several leading, commercially available large language models (LLMs) provide treatment recommendations concordant with evidence-based clinical practice guidelines (CPGs) developed by the American Academy of Orthopaedic Surgeons (AAOS). METHODS: All CPGs concerning the management of rotator cuff tears (n = 33) and anterior cruciate ligament injuries (n = 15) were extracted from the AAOS. Treatment recommendations from Chat-Generative Pretrained Transformer version 4 (ChatGPT-4), Gemini, Mistral-7B, and Claude-3 were graded by 2 blinded physicians as being concordant, discordant, or indeterminate (i.e., neutral response without definitive recommendation) with respect to AAOS CPGs. The overall concordance between LLM and AAOS recommendations was quantified, and the comparative overall concordance of recommendations among the 4 LLMs was evaluated through the Fisher exact test. RESULTS: Overall, 135 responses (70.3%) were concordant, 43 (22.4%) were indeterminate, and 14 (7.3%) were discordant. Inter-rater reliability for concordance classification was excellent (κ = 0.92). Concordance with AAOS CPGs was most frequently observed with ChatGPT-4 (n = 38, 79.2%) and least frequently observed with Mistral-7B (n = 28, 58.3%). Indeterminate recommendations were most frequently observed with Mistral-7B (n = 17, 35.4%) and least frequently observed with Claude-3 (n = 8, 6.7%). Discordant recommendations were most frequently observed with Gemini (n = 6, 12.5%) and least frequently observed with ChatGPT-4 (n = 1, 2.1%). Overall, no statistically significant difference in concordant recommendations was observed across LLMs (P = .12). Of all recommendations, only 20 (10.4%) were transparent and provided references with full bibliographic details or links to specific peer-reviewed content to support recommendations. CONCLUSIONS: Among leading commercially available LLMs, more than 1-in-4 recommendations concerning the evaluation and management of rotator cuff and anterior cruciate ligament injuries do not reflect current evidence-based CPGs. Although ChatGPT-4 showed the highest performance, clinically significant rates of recommendations without concordance or supporting evidence were observed. Only 10% of responses by LLMs were transparent, precluding users from fully interpreting the sources from which recommendations were provided. CLINICAL RELEVANCE: Although leading LLMs generally provide recommendations concordant with CPGs, a substantial error rate exists, and the proportion of recommendations that do not align with these CPGs suggests that LLMs are not trustworthy clinical support tools at this time. Each off-the-shelf, closed-source LLM has strengths and weaknesses. Future research should evaluate and compare multiple LLMs to avoid bias associated with narrow evaluation of few models as observed in the current literature.

ChatGPT-4 Performs Clinical Information Retrieval Tasks Using Consistently More Trustworthy Resources Than Does Google Search for Queries Concerning the Latarjet Procedure.

PURPOSE: To assess the ability of ChatGPT-4, an automated Chatbot powered by artificial intelligence, to answer common patient questions concerning the Latarjet procedure for patients with anterior shoulder instability and compare this performance with Google Search Engine. METHODS: Using previously validated methods, a Google search was first performed using the query "Latarjet." Subsequently, the top 10 frequently asked questions (FAQs) and associated sources were extracted. ChatGPT-4 was then prompted to provide the top 10 FAQs and answers concerning the procedure. This process was repeated to identify additional FAQs requiring discrete-numeric answers to allow for a comparison between ChatGPT-4 and Google. Discrete, numeric answers were subsequently assessed for accuracy on the basis of the clinical judgment of 2 fellowship-trained sports medicine surgeons who were blinded to search platform. RESULTS: Mean (± standard deviation) accuracy to numeric-based answers was 2.9 ± 0.9 for ChatGPT-4 versus 2.5 ± 1.4 for Google (P = .65). ChatGPT-4 derived information for answers only from academic sources, which was significantly different from Google Search Engine (P = .003), which used only 30% academic sources and websites from individual surgeons (50%) and larger medical practices (20%). For general FAQs, 40% of FAQs were found to be identical when comparing ChatGPT-4 and Google Search Engine. In terms of sources used to answer these questions, ChatGPT-4 again used 100% academic resources, whereas Google Search Engine used 60% academic resources, 20% surgeon personal websites, and 20% medical practices (P = .087). CONCLUSIONS: ChatGPT-4 demonstrated the ability to provide accurate and reliable information about the Latarjet procedure in response to patient queries, using multiple academic sources in all cases. This was in contrast to Google Search Engine, which more frequently used single-surgeon and large medical practice websites. Despite differences in the resources accessed to perform information retrieval tasks, the clinical relevance and accuracy of information provided did not significantly differ between ChatGPT-4 and Google Search Engine. CLINICAL RELEVANCE: Commercially available large language models (LLMs), such as ChatGPT-4, can perform diverse information retrieval tasks on-demand. An important medical information retrieval application for LLMs consists of the ability to provide comprehensive, relevant, and accurate information for various use cases such as investigation about a recently diagnosed medical condition or procedure. Understanding the performance and abilities of LLMs for use cases has important implications for deployment within health care settings.

Outcomes after débridement, antibiotics, and implant retention for prosthetic joint infection in shoulder arthroplasty.

BACKGROUND: Patients who undergo total shoulder arthroplasty usually have excellent long-term outcomes. However, a subset of patients is diagnosed with a prosthetic joint infection (PJI) requiring revision procedures and prolonged recovery. The purpose of this study was to evaluate rates of recurrent shoulder PJI in patients undergoing débridement, antibiotics, and implant retention (DAIR), single-stage revision, and 2-stage revision. We also sought to compare outcomes and complications across procedures. METHODS: Retrospective chart review was conducted for patients diagnosed with PJI after primary shoulder arthroplasty between January 2010 and August 2021. Patients were included if they underwent treatment with DAIR, single-stage revision, or 2-stage revision. Demographic information, surgical details, complications, laboratory data, postoperative antibiotic regimen, and infectious pathogen were collected. Postoperative patient-reported outcomes were collected: American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, Single Assessment Numeric Evaluation, Shoulder Activity Scale, and PROMIS Upper Extremity. Chi-square, t test, and 1-way analysis of variance were used as appropriate to evaluate each factor. RESULTS: Sixty-five patients were included in the study, 26% treated with DAIR, 9% treated with single-stage revision, and 65% treated with 2-stage revision. There were no significant differences in patient comorbidities. Patients undergoing DAIR were diagnosed significantly earlier than those undergoing single- and 2-stage revision procedures (12.6 ± 22.9 months vs. 49.6 ± 48.4 vs. 25.0 ± 26.6, P = .010). Recurrent PJI was noted in 23.1% of patients: 29.4% of DAIR patients, no single-stage patients, and 23.8% of 2-stage patients (P = .330). Patients undergoing 2-stage revision with treatment failure had a significantly higher Elixhauser Comorbidity Index (0.2 ± 3.7 vs. 3.7 ± 3.9, P = .027). There was no significant difference in patient-reported outcomes across groups. CONCLUSION: Patients undergoing treatment of shoulder PJI with DAIR did not have an increased rate of reinfection compared with single-stage and 2-stage revision procedures. Patients treated with DAIR were diagnosed with PJI significantly earlier than those undergoing single-stage and 2-stage revision procedures. There was no difference in complication rates between groups. This information adds to the body of work detailing outcomes after DAIR for shoulder PJI and provides encouraging data for use in this patient population. Future studies with a larger sample size may be conducted to further investigate specific pathogens, infection timelines, and antibiotic regimens that reduce the risk of treatment failure.

Increasing pitch count is associated with increasing elbow flexion angle at ball release in youth baseball pitchers.

BACKGROUND: Baseball is one of the most popular sports among youth athletes in the United States, and among these players, pitchers are at a particularly high risk of sustaining an injury. Overuse of the arm from repetitive pitching is a common mechanism for injury. Despite the attention that overuse injury has received, little is known regarding the mechanism that leads to elbow injury. This study aims to determine the effect of increasing pitch count on elbow flexion at ball release in a youth pitching cohort. The authors hypothesize that elbow flexion would increase as pitch count increases. METHODS: Study subjects included volunteers from youth baseball players from local teams and public advertisements. Retroreflective markers attached to bony landmarks were placed on the players according to International Shoulder Group recommendations. Pitchers threw an indoor simulated game. Three-dimensional marker trajectories were collected using a 12-camera optical motion capture system, and ball velocity was captured using a radar gun. Voluntary maximal isometric strength of the internal and external rotators was evaluated before and after pitching. Paired 2-tailed t tests were performed to determine if a significant change occurred between the fresh and fatigued sets. RESULTS: Twelve adolescent male pitchers were recruited. Eleven of 12 pitchers completed the prescribed 6 sets of 15 pitches, culminating in a 90-pitch simulated game. The ball speed in the second set was found to be the highest in all pitchers and was considered the "peak set" (P = .021), whereas ball speed was the slowest in the sixth set of pitches and was therefore considered the "fatigue set" (P = .001). There was a moderate but statistically significant inverse correlation between elbow flexion at ball release and maximum internal rotation velocity (P = .005). Elbow flexion at ball release was also significantly positively correlated with shoulder abduction at ball release (P = .004). Elbow flexion at ball release was not significantly correlated with ball velocity (P = .108). CONCLUSIONS: In a simulated game laboratory setting, increasing pitch count was associated with increasing elbow flexion angle at ball release in youth baseball pitchers. These findings demonstrate that pitching with fatigue may cause biomechanical changes that have been associated with increased rates of elbow injury in the adult throwing population. Further investigation on the association between elbow flexion angle and elbow injury in the youth baseball population is needed.

Inconsistencies in Measuring Glenoid Version in Shoulder Arthroplasty: A Systematic Review.

BACKGROUND: Glenoid version is a critical anatomic parameter relied upon by many surgeons to inform preoperative planning for shoulder arthroplasty. Advancements in imaging technology have prompted measurements of glenoid version on various imaging modalities with different techniques. However, discrepancies in how glenoid version is measured within the literature have not been well characterized. METHODS: A literature search was performed by querying PubMed, EMBASE, CINAHL, and Cochrane computerized databases from their inception through December 2023 to identify studies that assessed the relationship between preoperative glenoid version and at least one clinical or radiologic outcome following shoulder arthroplasty. Study quality was assessed via the Methodological Index for Non-Randomized Studies criteria. Imaging modalities and techniques for measuring glenoid version, along with their association with clinical outcomes, were aggregated. RESULTS: Among 61 studies encompassing 17,070 shoulder arthroplasties, 27 studies (44.3%) described explicitly how glenoid version was measured. The most common imaging modality to assess preoperative glenoid version was computed tomography (CT) (63.9%), followed by radiography (23%); 11.5% of studies used a combination of imaging modalities within their study cohort. Among the studies using CT, 56.5% utilized two-dimensional (2D) CT, 41.3% utilized three-dimensional (3D) CT, and 2.2% used a combination of 2D and 3D CT. The use of 3D CT increased from 12.5% of studies in 2012-2014 to 25% of studies in 2018-2020 to 52% of studies in 2021-2023 (ptrend=0.02). Forty-three (70.5%) studies measured postoperative version, most commonly on axillary radiograph (22 [51.2%]); 34.9% of these studies used different imaging modalities to assess pre- and postoperative version. CONCLUSIONS: This systematic review revealed marked discrepancies in how glenoid version was measured and reported in studies pertaining to shoulder arthroplasty. A temporal trend of increased utilization of 3D CT scans and commercial preoperative planning software was identified. Improved standardization of the imaging modality and technique for measuring glenoid version will enable more rigorous evaluation of its impact on clinical outcomes.

Swinging injuries in competitive baseball players.

Injuries are common in competitive baseball players and can occur in all facets of the game. The majority of the existing literature on injuries in baseball players has focused on injuries secondary to the overhead throw with very little attention given to injuries sustained while batting. The baseball swing is a complex, often violent, motion that predisposes batters to a variety of injuries affecting the spine, trunk, pelvis, and extremities. Knowledge of injury patterns that commonly occur during the baseball swing and radiologic findings important to the treating physician can help radiologists provide accurate imaging interpretations that appropriately guide patient management.

A Number of Modifiable and Nonmodifiable Factors Increase the Risk for Elbow Medial Ulnar Collateral Ligament Injury in Baseball Players: A Systematic Review.

PURPOSE: To analyze the current literature regarding risk factors associated with medial ulnar collateral ligament (MUCL) injury in baseball players and to serve as a robust source for identifying modifiable risk factors that once optimized, have the potential to reduce injury risk. METHODS: Comprehensive search of the available literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Studies were included if they evaluated risk factors for MUCL injuries in the elbow of baseball players. Risk of bias assessment was performed via Methodological Index for Non-randomized Studies (MINORS) scoring system. The Oxford Centre for Evidence-Based Medicine was used to determine level of evidence. Variables of interest; player age, position, shoulder motion, humeral retrotorsion, joint laxity, strength, balance, geography, velocity, pitch count, pitch types, throwing volumes, and throwing mechanics were recorded. RESULTS: Twenty-one studies were included in this systematic review. MINORS scores ranged from 75 to 87%, and variables demonstrated significant heterogeneity. Performance-based risk factors for MUCL injury included: increased pitch count (both annual and per game), higher percentage of fastballs thrown, smaller pitch repertoire, and/or a loss of pitching velocity. Biomechanical studies demonstrated the relationship between decreased shoulder range of motion (total ROM, ER, IR, and abduction), increased humeral retrotorsion, increased elbow valgus opening in the throwing arm, lower Y-Balance score, and increased lateral release position to increased MUCL injury. CONCLUSIONS: Risk factors for MUCL injury can generally be categorized into 4 primary groups: 1) various player demographics and characteristics, 2) throwing too hard (high velocity), 3) throwing too much (pitch count/volume), and 4) throwing with poor mechanics. In this systematic review, the most significant nonmodifiable risk factors for MUCL injuries included: increased glenohumeral retrotorsion and elbow valgus opening. The most consistent modifiable risk factors included: total shoulder range of motion, pitch count, pitch selection, Y balance score, and lateral release position. Pitch velocity was inconsistent in literature, but most studies found this as a risk for injury. These risk factors may serve as appropriate targets for future evidence-based injury mitigation strategies. LEVEL OF EVIDENCE: Level IV, systematic review of Level II-IV studies.

Increased Pitch Velocity Is Associated With Throwing Arm Kinetics, Injury Risk, and Ulnar Collateral Ligament Reconstruction in Adolescent, Collegiate, and Professional Baseball Pitchers: A Qualitative Systematic Review.

PURPOSE: To assess the relationship between pitch velocity and throwing arm kinetics, injury, and ulnar collateral ligament reconstruction (UCLr) among high school, collegiate, and professional baseball pitchers. METHODS: The Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed (2008-2019), and OVID/MEDLINE (2008-2019) were queried for articles that reported on pitch velocity predicting throwing arm kinetics, injury, or UCLr. The Methodological Index for Non-randomized Studies checklist was used to evaluate the quality of all included studies. Descriptive statistics with ranges were used to quantify data where appropriate. RESULTS: A total of 24 studies examining 2,896 pitchers, with Level of Evidence II-V were included. Intergroup analysis noted pitch velocity was significantly correlated with elbow varus torque in high school (R2 = 0.36), collegiate (R2 = 0.29), and professional (R2 = 0.076) pitchers. Elbow distraction force was positively associated with ball velocity in interpitcher analyses of high school (R2 = 0.373), professional (R2 = 0.175), and mixed-cohort evaluations (R2 = 0.624). Intragroup analysis demonstrated a strong association between pitch velocity and elbow varus torque (R2 = 0.922-0.957) and elbow distraction force (R2 = 0.910) in professional pitchers. Faster ball velocity was positively associated with a history of throwing arm injury (R2 = 0.194) in nonadult pitchers. In 2 studies evaluating professionals, injured pitchers had faster pitch velocity before injury compared with uninjured controls (P = .014; P = .0354). The need for UCLr was positively correlated with pitch velocity (R2 = 0.036) in professional pitchers. The consequences of UCLr noted little to no decrease in pitch velocity. CONCLUSIONS: Professional baseball pitchers with faster pitch velocity may be at the greatest risk of elbow injury and subsequent UCLr, potentially through the mechanism of increased distractive forces on the medial elbow complex. When a pitcher ultimately undergoes UCLr, decreases in pitching performance are unlikely, but may occur, which should encourage pitchers to caution against maximizing pitch velocity. LEVEL OF EVIDENCE: Level IV, systematic review of Level II-IV studies.

No Difference in Complication or Reoperation Rates Between Arthroscopic and Open Debridement for Lateral Epicondylitis: A National Database Study.

PURPOSE: To compare complication rates and 5-year reoperation rates between open debridement (OD) and arthroscopic debridement (AD) for lateral epicondylitis. METHODS: The PearlDiver MUExtr database (2010-2019) was reviewed for patients diagnosed with lateral epicondylitis (queried by International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision [ICD-10] codes) undergoing OD or AD of the common extensor tendon without repair (queried by Current Procedural Terminology codes). Patients were stratified into 2 cohorts: those who underwent AD and those who underwent OD. Nonoperative treatment modalities were reported for both groups within 1 year before index procedure. The rates of 90-day postoperative complications were compared, and multivariate logistic regression analysis was used to identify risk factors for complications. The 5-year reoperation rates, using laterality-specific ICD-10 codes, were also compared between the 2 groups. RESULTS: In total, 19,280 patients (OD = 17,139, AD = 2,141) were analyzed in this study. The most common nonoperative treatments for patients who underwent OD or AD were corticosteroid injections (49.5% vs 43.2%), physical therapy (24.8% vs 25.7%), bracing (2.8% vs 3.2%), and platelet-rich plasma injections (1.3% vs 1.0%). There were no significant differences in radial nerve injuries, hematomas, surgical site infections, wound dehiscence, and sepsis events between the 2 procedures (P = .50). The 5-year reoperation rate was not significantly different between the AD (5.0%) and OD (3.9%) cohorts (P = .10). CONCLUSIONS: For lateral epicondylitis, both AD and OD of the extensor carpi radialis brevis (without repair) were found to have low rates of 90-day adverse events, with no significant differences between the 2 approaches. Similarly, the 5-year reoperation rate was low and not statistically different for those treated with OD or AD. LEVEL OF EVIDENCE: Level III, cross-sectional study.

Pent-up demand for total shoulder arthroplasty prior to Medicare eligibility at age 65 years: evidence from a national patient database and national survey data.

BACKGROUND: Rising utilization rates of total shoulder arthroplasty (TSA) paired with an aging US population herald increased future economic burden. Previous research has demonstrated evidence of "pent-up demand" in health care (delaying medical care until financially able) accompanying insurance status changes. The purpose of this study was to determine pent-up demand for TSA in the years leading up to Medicare coverage at age 65 years while identifying key drivers underlying this trend, including socioeconomic status. METHODS: The incidence rates of TSA were evaluated using the 2019 National Inpatient Sample database. The observed increase in incidence between the ages of 64 years (pre-Medicare group) and 65 years (post-Medicare group) was compared with the expected increase. The expected frequency of TSA was subtracted from the observed frequency of TSA to calculate pent-up demand. Excess cost was calculated by multiplying pent-up demand by the median cost of TSA. The Medicare Expenditure Panel Survey-Household Component was used to compare health care cost and patient experience between pre-Medicare patients (aged 60-64 years) and post-Medicare patients (aged 66-70 years). RESULTS: The expected and observed increases in TSA procedures from age 64 years to age 65 years were 402, for an incidence rate increase of 0.13/1000 population (12.8% increase), and 820, for an incidence rate increase of 0.24/1000 population (27% increase), respectively. The 27% increase represented a sharp jump in comparison to the 7.8% annual growth rate between age 65 years and age 77 years. This resulted in pent-up demand between age 64 years and age 65 years of 418 TSA procedures and excess cost of $7.5 million. Mean total out-of-pocket expenses were significantly higher for the pre-Medicare group than for the post-Medicare group ($1700 vs. $1510, P < .001). Compared with the post-Medicare group, the pre-Medicare group exhibited a significantly higher proportion of patients who delayed Medicare care because of cost (P < .001), could not afford medical care (P < .001), had problems paying medical bills (P < .001), and were unable to pay medical bills (P < .001). Physician-patient relationship experience scores were significantly worse in the pre-Medicare group (P < .001). These trends were even stronger for low-income patients when data were broken down by income status. CONCLUSIONS: Patients likely delay elective TSA until reaching Medicare eligibility at age 65 years, resulting in substantial added financial burden to the health care system. As US health care costs continue to rise, it will be crucial for orthopedic providers and policy makers to be aware of pent-up demand for TSA and its possible associated drivers, especially socioeconomic status.

American Shoulder and Elbow Surgeons SLAP/Biceps Anchor Study Group evidence review: pathoanatomy and diagnosis in clinically significant labral injuries.

Glenoid superior biceps-labral pathology diagnosis, treatment, and outcomes are an evolving area of shoulder surgery. Historically, described as superior labrum anterior posterior (SLAP) tears, these lesions were identified as a source of pain in throwing athletes. Diagnosis and treatments applied to these SLAP lesions resulted in less than optimal outcomes in some patients and a prevailing sense of confusion. The purpose of this paper is to perform a reappraisal of the anatomy, examination, imaging, and diagnosis by the American Shoulder and Elbow Surgeons/SLAP biceps study group. We sought to capture emerging concepts and suggest a more unified approach to evaluation and identify specific needs for future research.

Factors associated with humeral stem revision in anatomic to reverse total shoulder arthroplasty revision.

BACKGROUND: Recent advances in implant technology have allowed for modular or platform humeral stem insertion during initial anatomic total shoulder arthroplasty (TSA). These systems allow for humeral stem retention during conversion to reverse TSA (RTSA). However, some patients still require humeral stem revision when undergoing revision to RTSA. The purpose of this study was to evaluate the association between patient-specific factors and radiographic parameters with humeral stem revision vs. retention during conversion from TSA to RTSA. METHODS: Retrospective chart review was conducted for patients who underwent a revision TSA to RTSA between January 2010 and May 2022 at a single institution. Patients were included if their prosthesis included a convertible humeral stem. Patient demographic information, surgical details, and postoperative outcomes and complications were collected. Radiographic parameters were measured by 2 graders on radiographs taken prior to the revision procedure. The need for humeral stem revision and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores (preoperative and 2 years) were also noted. Statistical analysis was performed using chi-square test for categorical variables and t test for continuous variables. RESULTS: One hundred seven patients were included, with 52 undergoing humeral stem revision. Patients were revised an average of 51.0 ± 54 months after primary TSA. Younger patient age (63.6 vs. 68.5 years, P = .017) and use of a lateralized glenosphere (1.6 mm vs. 0.4 mm, P < .001) were significantly associated with need for humeral stem revision. Glenoid to humeral head cut distance (28.3 mm vs. 26.3 mm, P = .076) approached significant association with the need for humeral stem revision. All other measurements were not associated with the need for humeral stem revision. Improvement of ASES scores at 2 years' follow-up was higher in the nonrevised group (increase of 33.4 points) than the revision group (23.3), but this did not reach significance (P = .149). Estimated blood loss and surgical time were significantly higher in the stem revision group than the non-revised group (P = .048 and P < .001, respectively). CONCLUSION: Younger patients and those receiving a lateralized glenosphere were more likely to undergo humeral stem revision during conversion from TSA to RTSA. Glenoid to the humeral head cut distance should be studied further as a potential indication for humeral stem revision, as it correlates with the space available for a revision implant. This information can guide surgeons with preoperative planning for a revision arthroplasty.

Artificial intelligence for automated identification of total shoulder arthroplasty implants.

BACKGROUND: Accurate and rapid identification of implant manufacturer and model is critical in the evaluation and management of patients requiring revision total shoulder arthroplasty (TSA). Failure to correctly identify implant designs in these circumstances may lead to delay in care, unexpected intraoperative challenges, increased morbidity, and excess health care costs. Deep learning (DL) permits automated image processing and holds the potential to mitigate such challenges while improving the value of care rendered. The purpose of this study was to develop an automated DL algorithm to identify shoulder arthroplasty implants from plain radiographs. METHODS: A total of 3060 postoperative images from patients who underwent TSA between 2011 and 2021 performed by 26 fellowship-trained surgeons at 2 independent tertiary academic hospitals in the Pacific Northwest and Mid-Atlantic Northeast were included. A DL algorithm was trained using transfer learning and data augmentation to classify 22 different reverse TSA and anatomic TSA prostheses from 8 implant manufacturers. Images were split into training and testing cohorts (2448 training and 612 testing images). Optimized model performance was assessed using standardized metrics including the multiclass area under the receiver operating characteristic curve (AUROC) and compared with a reference standard of implant data from operative reports. RESULTS: The algorithm classified implants at a mean speed of 0.079 seconds (±0.002 seconds) per image. The optimized model discriminated between 8 manufacturers (22 unique implants) with AUROCs of 0.994-1.000, accuracy of 97.1%, and sensitivities between 0.80 and 1.00 on the independent testing set. In the subset of single-institution implant predictions, a DL model identified 6 specific implants with AUROCs of 0.999-1.000, accuracy of 99.4%, and sensitivity >0.97 for all implants. Saliency maps revealed key differentiating features across implant manufacturers and designs recognized by the algorithm for classification. CONCLUSION: A DL model demonstrated excellent accuracy in identifying 22 unique TSA implants from 8 manufacturers. This algorithm may provide a clinically meaningful adjunct in assisting with preoperative planning for the failed TSA and allows for scalable expansion with additional radiographic data and validation efforts.

A Systematic Review of Lower-Body Kinematic and Strength Factors Associated With Pitch Velocity in Adult Baseball Pitchers.

CONTEXT: Ball velocity for baseball pitchers is influenced by a multitude of factors along the kinetic chain. While a vast amount of data currently exist exploring lower-extremity kinematic and strength factors in baseball pitchers, no previous study has systematically reviewed the available literature. OBJECTIVE: The aim of this systematic review was to perform a comprehensive assessment of the available literature investigating the association between lower-extremity kinematic and strength parameters and pitch velocity in adult pitchers. EVIDENCE ACQUISITION: Cross-sectional studies that investigated the association between lower-body kinematic and strength factors and ball velocity in adult pitchers were selected. A methodological index for nonrandomized studies checklist was used to evaluate the quality of all included studies. EVIDENCE SYNTHESIS: Seventeen studies met the inclusion criteria comprising a total of 909 pitchers (65%, professional, 33% college, and 3% recreational). The most studied elements were hip strength and stride length. The mean methodological index for nonrandomized studies score was 11.75 of 16 (range = 10-14). Pitch velocity was found to be influenced by several lower-body kinematic and strength factors including the following: (1) hip range of motion and strength of muscles around the hip and pelvis, (2) alterations in stride length, (3) alterations in lead knee flexion/extension, and (4) several pelvic and trunk spatial relationships throughout the throwing phase. CONCLUSIONS: Based on this review, we conclude that hip strength is a well-established predictor of increased pitch velocity in adult pitchers. Further studies in adult pitchers are needed to elucidate the effect of stride length on pitch velocity given mixed results across multiple studies. This study can provide a basis for trainers and coaches to consider the importance of lower-extremity muscle strengthening as a means by which adult pitchers can improve pitching performance.

Interval Throwing Programs at Distances Beyond 150 Feet Can Be Equivalent to Pitching Over Five Innings.

PURPOSE: To determine the cumulative elbow varus torque (EVT) experienced during created interval throwing programs (ITP) and derive innings pitched equivalent for each step. METHODS: High school pitchers wearing the motusBASEBALL sensor who had at least 50 throws at 90, 120, 150, and 180 ft and game pitches were included in this analysis. Means for EVT per throw and torque per minute were calculated at each distance. Three throwing programs were created using a template of 1 phase at each distance with 2 steps per phase. Programs varied only by number of throws per set (20, 25, and 30 throws for Program A, B, and C, respectively). Total EVT for each step, phase, and program were calculated using mean EVT per throw at each distance. Total EVT for each step and program were converted to a mean inning pitched equivalent (IPE) and maximum pitch count equivalent (MPE), respectively, using in-game pitching torque values and expected mean pitch counts (15 pitches/inning and maximum 105 pitches/game). RESULTS: In total, 3,447 throws were analyzed from 7 subjects (16.7 years ± 0.8 years). EVT per throw increased at each distance (range 36.9-45.5 N·m), comparable to game pitches (45.7 N·m). Mean EVT per minute was highest for 90 ft throws (193.4 N·m/min) and lowest for game pitches (125 N·m/min). Throwing Program A had the lowest range of IPE (Step 1: 2.0 and Step 8: 3.7), and Program C had the highest range (Step 1: 3.0 and Step 8: 5.6). The phases of Program A never exceeded 1MPE. Program B exceeded this threshold after Phase 1, and Program C exceeded 1MPE at every phase. Total program MPE ranged from 3.5 to 5.2 (Program A and C, respectively). CONCLUSIONS: Programs requiring 25 or more throws per set reached approximately 5 IPE per day. Increasing throwing repetitions by 10 throws resulted in a nearly 50% increase in IPE and MPE. LEVEL OF EVIDENCE: IV, retrospective cohort study.

Decreased Trunk Rotation at Foot Contact in Professional Baseball Pitchers With Prior Conservatively Managed SLAP Tears: A Propensity Score-Matched Analysis.

PURPOSE: To compare kinematic and kinetic parameters between a cohort of fully recovered professional pitchers with prior shoulder injury treated conservatively and a cohort with no prior shoulder injury. METHODS: Twenty-six fully recovered professional baseball pitchers with a history of shoulder injury treated conservatively pitched 8 to 10 fastball pitches using 3-dimensional motion capture (480 Hz). All shoulder injuries occurred within a 1- to 4-year time span from biomechanical evaluation and were severe enough to prevent pitchers from playing for between 1 and 12 months. These pitchers were propensity score matched by age, height, weight, handedness, and ball velocity to pitchers with no prior injury history (control) at a ratio of 1:4. We compared 21 kinematic and 11 kinetic parameters between groups using appropriate parametric testing. Subanalysis comparisons of pitchers with prior SLAP injury as well as rotator cuff tendinitis were also performed. RESULTS: SLAP tears (n = 11, 42.3%) were the most frequently reported injury, followed by rotator cuff tendinitis and/or shoulder impingement (n = 7, 26.9%). Compared with the control group, the 26 pitchers with prior injury showed no significant differences across the kinematic and kinetic factors. However, the SLAP tear subgroup did show significantly less trunk rotation at foot contact compared with controls (34.1° ± 4.9° vs 39.2° ± 10.2°, P = .0075). CONCLUSIONS: Fully recovered professional baseball pitchers with shoulder injuries treated conservatively showed no significant differences in kinetics or kinematics compared with their propensity score-matched counterparts, suggesting that shoulder injury alone may not greatly alter pitching mechanics. However, whereas prior groups have shown a decrease in trunk rotation at foot contact after surgical repair for SLAP tears, our study suggests that this kinematic change may alternatively originate with the injury itself. CLINICAL RELEVANCE: Understanding the cause of biomechanical adaptations by pitchers after injury can better aid clinicians and coaching staff in providing individualized and specific care to the throwing athlete.

Elbow varus torque and ball velocity associations in high school and professional pitchers with increased sagittal-plane trunk tilt.

BACKGROUND: Increased sagittal-plane trunk tilt is thought to increase drive in the anterior direction toward home plate, transferring energy from the trunk to the distal upper extremity, ultimately generating greater ball velocity. Increased sagittal trunk tilt has also been implicated in the risk of upper-extremity joint loading in baseball pitchers by way of elbow varus torque (EVT), a metric previously associated with elbow injury in professional pitchers. The purposes of this study were (1) to compare sagittal trunk tilt positioning between high school and professional pitchers throughout the pitch and (2) to identify the potential associations between sagittal-plane trunk tilt, ball velocity, and EVT for both cohorts. METHODS: Professional and high school pitchers were instructed to throw fastballs while being evaluated with 3-dimensional motion capture (480 Hz). Sagittal trunk tilt motion throughout the pitching motion was compared between cohorts from maximum knee height to maximum shoulder internal rotation. To assess the effects of sagittal-plane trunk tilt on ball velocity and EVT, linear mixed-effect models were created. RESULTS: Professional pitchers (n = 100, 882 pitches) achieved greater sagittal trunk tilt than high school pitchers (n = 57, 519 pitches) during early portions of the pitching motion, including maximum positive sagittal trunk tilt (46.6° ± 8.3° vs. 43.6° ± 10.2°, P = .042). Professional pitchers also had greater sagittal trunk tilt excursion throughout the pitch motion (68.0° ± 11.4° vs. 62.5° ± 11.0°, P = .004). For every 10° increase in sagittal trunk tilt at ball release for professional pitchers, ball velocity increased by 0.36 m/s (B = 0.036 and ß = 0.194, P < .001) or 0.9% average ball velocity whereas EVT increased by 0.14% body weight × body height (B = 0.014 and ß = 0.159, P < .001) or 2.9% average normalized EVT. For every 10° increase in sagittal trunk tilt at ball release for high school pitchers, ball velocity increased by 0.34 m/s (B = 0.097 and ß = 0.025, P = .025) or 1.1% average ball velocity whereas EVT increased by 0.07% body weight × body height (B = 0.007 and ß = 0.086, P = .016) or 1.7% average normalized EVT. CONCLUSION: Increased positive sagittal-plane trunk tilt was significantly associated with greater ball velocity and increased EVT for both professional and high school pitchers. Peak EVT estimates were consistently more pronounced than ball velocity benefits for both populations, suggesting that no specific time point may provide a ball velocity benefit while concomitantly minimizing EVT. Both professional and high school pitchers should consider this trade-off, which may influence injury risk, when engaging in higher degrees of positive sagittal-plane trunk tilt.

The influence of excessive ipsilateral trunk tilt on upper-extremity throwing mechanics: a newly characterized parameter for biomechanical evaluation in high school and professional pitchers.

BACKGROUND: Although contralateral trunk tilt has been recognized, the phenomenon of excessive ipsilateral trunk tilt, often observed during earlier portions of the pitch, has not been explored as a potential correlate with throwing-arm kinetics among baseball pitchers. The purpose of this study was to evaluate kinetic and kinematic parameters among high school and professional pitchers related to excessive ipsilateral and contralateral trunk tilt. METHODS: Professional and high school pitchers were assessed with a 3-dimensional motion capture system (480 Hz) while pitching. Pitchers were grouped as follows: excessive ipsilateral tilt at foot contact (FC), neutral, or excessive contralateral tilt at ball release (BR). Trunk and shoulder kinematics as well as throwing-arm kinetics were compared between subgroups via post hoc regression analysis. RESULTS: Professional pitchers (n = 287) had significantly higher ipsilateral trunk tilt at FC (P < .001) than high school pitchers (n = 59). High school pitchers with excessive contralateral trunk tilt at BR experienced significantly higher shoulder superior force (27.0% ± 7.4% body weight [BW] vs. 17.6% ± 5.1% BW, P < .001) and shoulder anterior force (39.6% ± 8.2% BW vs. 35.7% ± 5.4% BW, P < .001) compared with the ipsilateral trunk tilt cohort but had comparable ball velocity (30.2 ± 3.2 m/s vs. 30.4 ± 2.1 m/s, P = .633). For professionals, for every 10° increase in ipsilateral trunk tilt at FC, ball velocity increased by 0.2 m/s (B = 0.02, ß = 0.07, standard error [SE] = 0.005, P = .010) whereas elbow varus torque decreased by 0.1% BW × height (B = -0.01, ß = -0.08, SE = 0.002, P < .001) and shoulder internal rotation torque decreased by 0.1% BW × height (B = -0.01, ß = -0.07, SE = 0.002, P = .005). CONCLUSION: High school and professional pitchers with excessive ipsilateral trunk tilt at FC consistently demonstrated significantly decreased throwing-arm kinetics (shoulder anterior force and shoulder superior force for high school pitchers and shoulder internal rotation torque and elbow varus torque for professional pitchers) compared with pitchers with excessive contralateral trunk tilt at BR, with equivalent ball velocity. In addition, professional pitchers appeared to engage in significantly greater ipsilateral trunk tilt during early portions of the pitch when compared with high school pitchers, which may represent a kinetically favorable method adopted by pitchers at higher playing levels to maintain adequate ball velocity while concomitantly minimizing throwing-arm kinetics.

Joint and segment sequencing and its relationship to ball velocity and throwing arm kinetics in professional pitchers.

BACKGROUND: Temporal variations during the pitch have demonstrated significant impacts on the kinetic chain, and as such, have implications in injury risk. PURPOSE: To determine the effect of varying chronological orders of maximum joint and segment velocities on ball velocity and upper extremity kinetics. METHODS: Professional baseball pitchers (n = 287) were assessed with 3D-motion capture (480 Hz) while pitching. Pitches were categorized into one of the following groups dependent on the first maximum joint or segment velocity achieved out of chronological order in an inferior to superior direction: knee extension (DscK), pelvis rotation (DscP), trunk rotation (DscT), shoulder rotation (DscS), forearm pronation (DscF), and Proper (for pitchers with the correct temporal sequence), and Total Population, for all pitchers. Ten normalized throwing arm kinetic variables were compared among groups. Regression analysis was conducted on the timing of maximum velocities with ball velocity. RESULTS: The majority of pitches were in the DscK group (64.5%). The DscK group had a significantly slower maximum lead knee extension velocity compared with the Proper group (253°/s vs. 316°/s, P = .017). The Proper group had a significantly faster ball velocity compared with the Total Population (39.0 ± 1.9 m/s vs. 38.3 ± 2.1 m/s, P = .013). The DscP group had a significantly slower maximum pelvis rotation velocity compared with the Proper group (596°/s vs. 698°/s, P < .001). The Proper group had no significant difference in kinetics relative to the population. For every 1 standard deviation delay in attaining maximum lead knee extension velocity, ball velocity increased by 0.38 m/s (B = 3.5, ß = 0.18, P < .001). For every 1 standard deviation delay in timing to achieve maximum pelvis rotation velocity, maximum pelvis rotation velocity and ball velocity increased by 22.5°/s (B = 1107.0, ß = 0.23, P < .001) and 0.48 m/s (B = 23.4, ß = 0.23, P < .001), respectively. CONCLUSION: Pitchers with a discordant sequence of knee extension and pelvis rotation velocity timing had significantly slower corresponding segment/joint velocities. Conversely, pitchers with a proper sequence had the fastest ball velocity with minimal differences in throwing arm kinetics. To maximize ball velocity, professional pitchers should consider achieving maximal velocities in an inferior to superior chronological sequence, with a particular focus on the knee and pelvis.

Kinetic and kinematic comparisons in high school pitchers with low and high pitch location consistency.

BACKGROUND: Although ball velocity has often been associated with increased kinetics at the upper extremity and risk of injury in youth and adolescent pitchers, it is unclear if the performance metric pitch location consistency has any positive or negative associations with pitching kinetics. METHODS: High school pitchers (n = 59) pitched 8-12 fastballs using 3D motion capture (480 Hz). Pitchers were divided into high-consistency (HiCon) and low-consistency (LoCon) groups based on the absolute center deviation of each pitcher's pitch to the center of the pitcher's mean pitch location. Ninety-five percent confidence ellipses with major and minor radii were constructed, and kinematics and kinetics were compared between groups. RESULTS: Compared with LoCon pitchers, HiCon pitchers had decreased lead hip flexion at elbow extension (40° ± 12° vs. 52° ± 13°, respectively, P = .008), and at foot contact, decreased back hip extension (-1° ± 10° vs. -10° ± 13°, respectively, P = .038) and increased back hip internal rotation (9° ± 15° vs. -2° ± 15°, respectively, P = .043). LoCon pitchers achieved maximum lead hip flexion earlier in the pitch (61.3% ± 23.2% vs. 75.8% ± 15.1%, respectively, P = .039). A multiregression model predicted 0.49 of variance in pitch location consistency using kinematic inputs. DISCUSSSION AND CONCLUSION: Pitchers who differ in pitch location consistency outcomes do not appear to demonstrate physiologically unsafe kinematics. High school pitchers who strive for improved pitch consistency can consider adjusting parameters of hip kinematics during early portions of the pitch.