Cueing Dancers to "Externally Rotate From the Hips" Improves Potentially Injurious Ankle Joint Angles and Contact Forces During a Demipointe Ballet Position.

Introduction: The demipointe dance position puts the ankle at high risk of overuse injury and posteromedial ankle pain due to increased ankle valgus forces. Previous work has shown that creating lower limb external rotation intrinsic to demipointe with hip external rotation reduces foot pronation that causes ankle valgus stress. Therefore, the purpose of this work was to examine long axis rotation kinematics of the hip, knee, and ankle as well as the ankle joint contact forces in demipointe to better understand the biomechanical impact(s) of the specific cue to increase hip external rotation in this position. Methods: Three-dimensional motion capture and force plate data were collected from 23 contemporary or ballet pre-professional dancers (age: 19.94 ± 1.34 years) who each performed 3 dancer-selected (DS) demipointe positions and 3 demipointes with the cue to "externally rotate from the hips." Results: The cue to increase hip external rotation resulted in significantly increased hip external rotation angle [DS: 37.5; 9.42° (median; interquartile range), Cued: 39.9; 10.8°, P < .0001)] and significantly reduced ankle eversion angle (DS: 8.13; 11.4°, Cued: 7.77; 10.3°, P = .023). However, total turnout angle was also significantly decreased (DS: 75.8; 7.91°, Cued: 75.4; 7.73°, P < .0001), which is undesirable for proper esthetic performance of demipointe. Total ankle joint force remained unchanged, but ankle eversion force was significantly reduced (DS: 15.3; 4.18 %bodyweight (BW), Cued: 14.7; 4.99 %BW, P < .0001) with use of the cue. Discussion/Conclusion: Utilization of a cue to increase hip external rotation was successful in increasing hip contribution to turnout angle and reducing injurious ankle eversion force. Further coaching using this cue may allow dancers to produce these advantageous mechanics while maintaining turnout angle.

Effects of Ball Size and Weight on Throwing Kinematics and Kinetics in Youth Baseball Athletes.

BACKGROUND: In baseball, youth athletes play on smaller fields with shorter distances between bases, shorter pitching distances, and smaller mounds. Despite this, youth athletes use baseballs weighing the same amount as those used at the professional level, possibly predisposing youth baseball players to injuries. PURPOSE: (1) To determine the effects of throwing a smaller, lighter, and both smaller and lighter baseball on throwing arm stress in youth athletes and (2) to also investigate how changing the ball size and weight would affect elbow varus torque, shoulder distraction force, and throwing arm internal rotation velocity during the throwing motion. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: This cross-sectional cohort study analyzed the kinematics and kinetics of 38 youth baseball players (mean age, 8.3 ± 0.8 years) throwing a baseball modified in size and weight. Three-dimensional motion data were collected using a retroreflective marker set and a 12-camera motion analysis system. Full-body kinematics and kinetics were calculated using commercial software. Participants threw 5 different types of baseballs 3 times each, in random order, with full effort from a pitching mound to a target 14 m away. The balls used were a 5-oz regular baseball, 5-oz (0.142-kg) baseball with a 5% reduced circumference, 4-oz (0.113-kg) baseball, 4-oz baseball with a 5% reduced circumference, and 3-oz (0.085-kg) baseball. Analysis of variance was used to determine statistical differences in elbow varus torque, shoulder distraction force, and throwing arm internal rotation velocity among baseball types. The Tukey post hoc test was used to further investigate differences between the ball groups, considering P < .05 to be significant. RESULTS: Analysis of variance detected a significant difference in elbow varus torque among ball groups (P = .024). The Tukey post hoc test revealed a moderate difference in elbow varus torque between the 5-oz baseball (4.73 ± 1.06 percentage body weight × height [%BW × H]) and 3-oz baseball (4.06 ± 0.83 %BW × H) (P = .017; d = 0.677 [95% CI, 0.08-1.27]). No significant differences were found in shoulder distraction force or throwing arm internal rotation velocity among ball groups. CONCLUSION: Compared with a 5-oz baseball, throwing a 3-oz baseball resulted in decreased elbow varus torque with a moderate effect size.

Up Front and Open? Shrouded in Secrecy? Or Somewhere in Between? A Meta-Research Systematic Review of Open Science Practices in Sport Medicine Research.

OBJECTIVE: To investigate open science practices in research published in the top 5 sports medicine journals from May 1, 2022, and October 1, 2022. DESIGN: A meta-research systematic review. LITERATURE SEARCH: Open science practices were searched in MEDLINE. STUDY SELECTION CRITERIA: We included original scientific research published in one of the identified top 5 sports medicine journals in 2022 as ranked by Clarivate: (1) British Journal of Sports Medicine, (2) Journal of Sport and Health Science, (3) American Journal of Sports Medicine, (4) Medicine and Science in Sports and Exercise, and (5) Sports Medicine-Open. Studies were excluded if they were systematic reviews, qualitative research, gray literature, or animal or cadaver models. DATA SYNTHESIS: Open science practices were extracted in accordance with the Transparency and Openness Promotion guidelines and patient and public involvement. RESULTS: Two hundred forty-three studies were included. The median number of open science practices in each study was 2, out of a maximum of 12 (range: 0-8; interquartile range: 2). Two hundred thirty-four studies (96%, 95% confidence interval [CI]: 94%-99%) provided an author conflict-of-interest statement and 163 (67%, 95% CI: 62%-73%) reported funding. Twenty-one studies (9%, 95% CI: 5%-12%) provided open-access data. Fifty-four studies (22%, 95% CI: 17%-27%) included a data availability statement and 3 (1%, 95% CI: 0%-3%) made code available. Seventy-six studies (32%, 95% CI: 25%-37%) had transparent materials and 30 (12%, 95% CI: 8%-16%) used a reporting guideline. Twenty-eight studies (12%, 95% CI: 8%-16%) were preregistered. Six studies (3%, 95% CI: 1%-4%) published a protocol. Four studies (2%, 95% CI: 0%-3%) reported an analysis plan a priori. Seven studies (3%, 95% CI: 1%-5%) reported patient and public involvement. CONCLUSION: Open science practices in the sports medicine field are extremely limited. The least followed practices were sharing code, data, and analysis plans. J Orthop Sports Phys Ther 2023;53(12):1-13. Epub 20 October 2023. doi:10.2519/jospt.2023.12016.

Barriers and facilitators to implementation of musculoskeletal injury mitigation programmes for military service members around the world: a scoping review.

INTRODUCTION: Musculoskeletal injury (MSK-I) mitigation and prevention programmes (MSK-IMPPs) have been developed and implemented across militaries worldwide. Although programme efficacy is often reported, development and implementation details are often overlooked, limiting their scalability, sustainability and effectiveness. This scoping review aimed to identify the following in military populations: (1) barriers and facilitators to implementing and scaling MSK-IMPPs; (2) gaps in MSK-IMPP research and (3) future research priorities. METHODS: A scoping review assessed literature from inception to April 2022 that included studies on MSK-IMPP implementation and/or effectiveness in military populations. Barriers and facilitators to implementing these programmes were identified. RESULTS: From 132 articles, most were primary research studies (90; 68.2%); the remainder were review papers (42; 31.8%). Among primary studies, 3 (3.3%) investigated only women, 62 (69%) only men and 25 (27.8%) both. Barriers included limited resources, lack of stakeholder engagement, competing military priorities and equipment-related factors. Facilitators included strong stakeholder engagement, targeted programme design, involvement/proximity of MSK-I experts, providing MSK-I mitigation education, low burden on resources and emphasising end-user acceptability. Research gaps included variability in reported MSK-I outcomes and no consensus on relevant surveillance metrics and definitions. CONCLUSION: Despite a robust body of literature, there is a dearth of information about programme implementation; specifically, barriers or facilitators to success. Additionally, variability in outcomes and lack of consensus on MSK-I definitions may affect the development, implementation evaluation and comparison of MSK-IMPPs. There is a need for international consensus on definitions and optimal data reporting elements when conducting injury risk mitigation research in the military.

Kinematic and kinetic comparison between preprofessional pitchers from the Dominican Republic and the United States.

Introduction: Pitching biomechanical efficiency is defined as the association between pitch velocity and arm kinetics. Pitching mechanics inefficiency, an increase in arm kinetics without the resultant increase in pitch velocity, can lead to increased arm strain, increasing arm injury risk. The purpose of this study was to compare arm kinetics, elbow varus torque and shoulder force, in preprofessional United States (US) and Dominican Republic (DR) pitchers. Kinematics that are known to influence elbow varus torque and shoulder force as well as a representative of pitch velocity (hand velocity) were also compared. Methods: A retrospective review was performed on baseball pitchers from the DR and US who participated in biomechanical evaluations conducted by the University biomechanics laboratory personnel. Three-dimensional biomechanical analyses were performed on US (n = 37) and DR (n = 37) baseball pitchers. Potential differences between US and DR pitchers were assessed through analysis of covariance with 95% confidence intervals [95% confidence Interval (CI)]. Results: Preprofessional DR pitchers experienced increased elbow varus torque compared with their US counterparts [DR: 7.5 (1.1); US: 5.9 (1.1) %BWxH; Beta: -2.0 (95% CI: -2.7, -1.2) %BWxH], despite throwing fastballs with slower hand velocity [DR: 3,967.1 (939.4); US: 5,109.1 (613.8) °/s; Beta: 1,129.5 (95% CI: 677.5, 1,581.4) °/s]. DR and US pitchers demonstrated similar shoulder force [DR: 136.8 (23.8); US: 155.0 (25.7); Beta: 0.4 (95% CI: -1.2, 19.7) %BW]. Discussion: Increased elbow varus torque although decreased hand velocity suggests inefficient pitching mechanics among DR pitchers. Inefficient pitching mechanics and increased elbow torque should be considered when developing training programs and pitching plans for professional pitchers from the Dominican Republic.

Opioid Consumption Patterns and Prolonged Opioid Use Among Opioid-Naïve Ankle Fracture Patients.

INTRODUCTION: Previous literature has demonstrated an association between acute opioid exposure and the risk of long-term opioid use. Here, the investigators assess immediate postoperative opioid consumption patterns as well as the incidence of prolonged opioid use among opioid-naïve patients following ankle fracture surgery. METHODS: Included patients underwent outpatient open reduction and internal fixation of an ankle or tibial plafond fracture over a 1-year period. At patients' first postoperative visit, opioid pills were counted and standardized to the equivalent number of 5-mg oxycodone pills. Prolonged use was defined as filling a prescription for a controlled substance more than 90 days after the index procedure, tracked by the New Jersey Prescription Drug Monitoring Program up to 1 year postoperatively. RESULTS: At the first postoperative visit, 173 patients consumed a median of 24 out of 40 pills prescribed. The initial utilization rate was 60%, and 2736 pills were left unused. In all, 32 (18.7%) patients required a narcotic prescription 90 days after the index procedure. Patients with a self-reported history of depression (P = .11) or diabetes (P = .07) demonstrated marginal correlation with prolonged narcotic use. CONCLUSION: Our study demonstrated that, on average, patients utilize significantly fewer opioid pills than prescribed and that many patient demographics are not significant predictors of continued long-term use following outpatient ankle fracture surgery. Large variations in consumption rates make it difficult for physicians to accurately prescribe and predict prolonged narcotic use. LEVEL OF EVIDENCE: Level III.

Thumb-Basal Joint Arthroplasty Outcomes and Metacarpal Subsidence: A Prospective Cohort Analysis of Trapeziectomy With Suture Button Suspensionplasty Versus Ligament Reconstruction With Tendon Interposition.

BACKGROUND: Thumb carpometacarpal (CMC) joint arthroplasty is a common procedure in the surgical management of symptomatic thumb basal joint arthritis. Following trapeziectomy, a number of suspensionplasty techniques are often used, but limited comparative evidence exists between these techniques. The central aim of this study was to prospectively compare the outcomes of 2 suspensionplasty techniques following trapeziectomy: suture button (TightRope) versus ligament reconstruction and tendon interposition (LRTI). METHODS: Prospective data were collected on 112 consecutive patients with Eaton stage III-IV thumb CMC arthritis who underwent open trapeziectomy and suspensionplasty. There were 53 LRTI and 59 TightRope suspensionplasty procedures. Outcomes were measured using the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) questionnaire, Visual Analogue Scale (VAS) for pain, radiographic analysis, and lateral pinch strength. Patient demographic data and complications were also recorded. RESULTS: Patients undergoing TightRope suspensionplasty had significantly higher trapeziometacarpal index and thus less subsidence than the LRTI group at 2 weeks (0.22 vs 0.17 [P < .0001]) and 3 months (0.17 vs 0.15 [P < .05]) postoperatively. TightRope suspensionplasty also had a significantly lower QuickDASH score at 2 weeks (64.7 vs 74.6 [P < .05]), 3 months (20.7 vs 32.5 [P < .05]), and 1 year postoperatively (7.57 vs 21.5 [P < .05]) compared with the LRTI group. However, there was no difference in VAS pain, lateral pinch strength, reoperation, or complications at any time point between groups. CONCLUSIONS: Thumb CMC joint arthroplasty performed with a TightRope suspensionplasty versus LRTI yielded short-term improved resistance to subsidence, long-term greater improvement in clinical outcome by QuickDASH, and no difference in pain or complication rates.

Pitching Biomechanics Normative Values and Kinetic Differences by Competition Level.

Pitching kinematic and kinetic assessments require normative values to make valuable comparisons to athletic peers. The purpose of this research note was to report normative values of pitching kinematics and kinetics and to compare kinetics by competition level. A retrospective review was performed on three-dimensional baseball pitching biomechanical evaluations. Kinematics and kinetics were calculated. Pitchers were portioned into competition level groups. Kinetic group differences were assessed through analyses of variance with significance level p < 0.05. One-hundred and twenty pitchers were included. Elbow varus torque was greater in higher competition levels. Shoulder distraction force was greater in higher competition levels. All levels demonstrated similar maximum vertical push off ground reaction force (p = 0.960) and maximum vertical landing ground reaction force (p = 0.135). Higher competition level pitchers demonstrated improved pitching kinematic efficiency compared to lower-level pitchers. However, college and professional pitchers exhibited greater arm stress, which may be attributed to increased pitching velocity. These pitching biomechanical data can be used as normative comparisons when examining pitching mechanics at multiple competition levels throughout an athlete's baseball career. (Journal of Surgical Orthopaedic Advances 31(3):177-180, 2022).

Evaluation of approaches to estimate scapular kinematics during baseball pitching.

Biomechanical analyses of pitching possess limitations in accurately measuring dynamic scapular orientation and are thus unable to distinguish between glenohumeral and scapulothoracic contributions to global shoulder motion. In lieu of direct measurement, several methods to estimate scapular kinematics have been developed. This study evaluated the ability of the linear model and the double calibration acromion marker cluster (D-AMC) approaches to estimate scapular kinematics throughout a full-speed pitching motion. Each approach's estimates were compared against scapulothoracic range of motion limits established in a non-pitching biplane fluoroscopy study involving various functional arm movements that approximate physiological limits of scapular motion. Fourteen healthy collegiate pitchers participated. Motion capture measured upper extremity joint kinematics during full-speed fastball pitches. Linear model and D-AMC approaches estimated scapulothoracic kinematics during each pitch. Linear model estimates of scapulothoracic kinematics were largely within established physiological limits on each scapular axis of motion while D-AMC estimates exceeded fluoroscopy-established bounds for more subjects and by larger, less physiologically plausible amounts. These findings demonstrate that the linear model outperforms the D-AMC and suggest that it is a viable approach to estimate scapular kinematics during pitching. Finally, these results offer additional evidence to support the accepted pattern of scapular kinematics during pitching.

A Comparison of Pitching Biomechanics and Sport Specialization in High School Pitchers.

Background: The prevalence of sport specialization in high school athletes continues to rise, particularly among baseball players. Previous research has focused on the incidence of injury among specialized and non-specialized athletes but has yet to examine the level of sport specialization and pitching biomechanics. Hypotheses/Purpose: The purpose of this study was to investigate differences in pitching volume and biomechanics between low-, moderate-, and high-level specialized baseball pitchers. It was hypothesized that high-level specialized pitchers would have the most pitching volume within the current and previous years while low-level specialized pitchers would exhibit the least amount. The second hypothesis states that kinematics and kinetics commonly associated with performance and injury risk would differ between low-, moderate-, and high-level specialized pitchers. Study Design: Case-Control Study. Methods: Thirty-six high school baseball pitchers completed a custom sport specialization questionnaire before participating in a three-dimensional pitching motion analysis. Sport specialization was based off current guidelines and categorized as low-, moderate-, and high-level specialized based upon self-reported outcomes. Pitchers then threw ≈10 fastballs from a mound engineered to professional specifications. Data averaged across fastballs was used for biomechanics variables. Key pitching biomechanical and pitching volume variables were compared between low-, moderate-, and high-level specialized pitchers. Results: High-level specialized pitchers were older (p = 0.003), had larger body mass (p = 0.05) and BMI (p = 0.045), and threw faster (p = 0.01) compared to low-level specialized pitchers. Pitching volume and pitching biomechanics were similar across groups. Conclusions: Pitching biomechanics were similar across groups, although high-level specialized pitchers threw with significantly higher throwing velocity compared to low-level pitchers. The low amount of pitching volume throughout the season may be responsible for the lack of additional observed differences. Further research should examine the relationship between pitching biomechanics, upper extremity strength and flexibility, and sport specialization. Level of Evidence: Level III.

Biceps Tenodesis Has Greater Expected Value Than Repair for Isolated Type II SLAP Tears: A Meta-analysis and Expected-Value Decision Analysis.

PURPOSE: To use an expected-value decision analysis to determine the optimal treatment decision between repair and biceps tenodesis (BT) for an isolated type II SLAP injury. METHODS: An expected-value decision analysis with sensitivity analysis was performed to systematically quantify the clinical decision. To determine outcome probabilities, a decision tree was constructed (repair vs BT) and a meta-analysis was conducted. To determine outcome utilities, we evaluated 70 patients with a chief complaint of shoulder pain regarding age, sex, Shoulder Activity Level, and visual analog scale score in terms of potential outcome preferences. Statistical fold-back analysis was performed to determine the optimal treatment. One-way sensitivity analysis determined the effect of changing the reinjury rate on the expected value of BT. RESULTS: The overall expected value was 8.66 for BT versus 7.19 for SLAP repair. One-way sensitivity analysis showed that BT was the superior choice if reinjury rates were expected to be lower than 28%. Meta-analysis of 23 studies and 908 patients revealed that the probability of a "well" outcome was significantly greater for BT (87.8%; 95% confidence interval [CI], 74.9%-94.6%; I2 = 0.0%) than for SLAP repair (62.9%; 95% CI, 55.9%-69.3%; I2 = 65.9%; P = .0023). The rate of reinjury was 1.5% for BT (95% CI, 0.05%-33.8%; I2 = 0.0%) and 6.4% for repair (95% CI, 4.2%-9.6%; I2 = 24%), which was not statistically significantly different (P = .411). A total of 50 participants (mean age, 25.4 years [standard deviation, 8.9 years]; 76% male patients; 50% overhead athletes) met the inclusion criteria. Forty-six percent of participants had a high Shoulder Activity Level score. CONCLUSIONS: Decision analysis showed that BT is preferred over repair for an isolated type II SLAP tear based on greater expected value of BT versus repair. Meta-analysis showed more frequent favorable outcomes with BT. Surgeons can use this information to tailor discussions with patients. LEVEL OF EVIDENCE: Level IV, meta-analysis of Level I-IV studies.

Just How Confident Can We Be in Predicting Sports Injuries? A Systematic Review of the Methodological Conduct and Performance of Existing Musculoskeletal Injury Prediction Models in Sport.

BACKGROUND: An increasing number of musculoskeletal injury prediction models are being developed and implemented in sports medicine. Prediction model quality needs to be evaluated so clinicians can be informed of their potential usefulness. OBJECTIVE: To evaluate the methodological conduct and completeness of reporting of musculoskeletal injury prediction models in sport. METHODS: A systematic review was performed from inception to June 2021. Studies were included if they: (1) predicted sport injury; (2) used regression, machine learning, or deep learning models; (3) were written in English; (4) were peer reviewed. RESULTS: Thirty studies (204 models) were included; 60% of studies utilized only regression methods, 13% only machine learning, and 27% both regression and machine learning approaches. All studies developed a prediction model and no studies externally validated a prediction model. Two percent of models (7% of studies) were low risk of bias and 98% of models (93% of studies) were high or unclear risk of bias. Three studies (10%) performed an a priori sample size calculation; 14 (47%) performed internal validation. Nineteen studies (63%) reported discrimination and two (7%) reported calibration. Four studies (13%) reported model equations for statistical predictions and no machine learning studies reported code or hyperparameters. CONCLUSION: Existing sport musculoskeletal injury prediction models were poorly developed and have a high risk of bias. No models could be recommended for use in practice. The majority of models were developed with small sample sizes, had inadequate assessment of model performance, and were poorly reported. To create clinically useful sports musculoskeletal injury prediction models, considerable improvements in methodology and reporting are urgently required.

The impact of preoperative neurological symptom severity on postoperative outcomes in cervical spondylotic myelopathy.

Study Design: The study design is a retrospective cohort study. Objective: To compare patient-reported outcomes between patients with mild versus moderate-to-severe myelopathy following surgery for cervical spondylotic myelopathy (CSM). Summary of Background Data: Recent studies have demonstrated that decompression for CSM leads to improved quality of life when measured by patient-reported outcomes. However, it is unknown if preoperative myelopathy classification is predictive of superior postoperative improvements. Materials and Methods: A retrospective review of patients treated surgically for CSM at a single institution from 2014 to 2015 was performed. Preoperative myelopathy severity was classified according to the modified Japanese Orthopaedic Association (mJOA) scale as either mild (≥15) or moderate-to-severe (<15). Other outcomes included neck disability index (NDI), 12-item short-form survey (SF-12), and visual analog scale (VAS) for arm and neck pain. Differences in outcomes were tested by linear mixed-effects models followed by pairwise comparisons using least square means. Multiple linear regression determined whether any baseline outcomes or demographics predicted postoperative mJOA. Results: There were 67 patients with mild and 50 patients with moderate-to-severe myelopathy. Preoperatively, patients with moderate-to-severe myelopathy reported significantly worse outcomes compared to the mild group for NDI, Physical Component Score (PCS-12), and VAS arm (P = 0.031). While both groups experienced improvements in NDI, PCS-12, VAS Arm and Neck after surgery, only the moderate-to-severe patients achieved improved mJOA (+3.1 points, P < 0.001). However, mJOA was significantly worse in the moderate-to-severe when compared to the mild group postoperatively (-1.2 points, P = 0.017). Both younger age (P = 0.017, ß-coefficient = -0.05) and higher preoperative mJOA (P < 0.001, ß-coefficient = 0.37) predicted higher postoperative mJOA. Conclusions: Although patients with moderate-to-severe myelopathy improved for all outcomes, they did not achieve normal absolute neurological function, indicating potential irreversible spinal cord changes. Early surgical intervention should be considered in patients with mild myelopathy if they seek to prevent progressive neurological decline over time.

The Impact of Upper Cervical Spine Alignment on Patient-reported Outcome Measures in Anterior Cervical Decompression and Fusion.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: To determine the extent to which the upper cervical spine compensates for malalignment in the subaxial cervical spine, and how changes in upper cervical spine sagittal alignment affect patient-reported outcomes. SUMMARY OF BACKGROUND DATA: Previous research has investigated the relationship between clinical outcomes and radiographic parameters in the subaxial cervical spine following anterior cervical discectomy and fusion (ACDF). However, limited research exists regarding the upper cervical spine (occiput to C2), which accounts for up to 40% of neck movement and has been hypothesized to compensate for subaxial dysfunction. MATERIALS AND METHODS: Patients undergoing ACDF for cervical radiculopathy and/or myelopathy at a single center with minimum 1-year follow-up were included. Radiographic parameters including cervical sagittal vertical axis, C0 angle, C1 inclination angle, C2 slope, Occiput-C1 angle (Oc-C1 degrees), Oc-C2 degrees, Oc-C7 degrees, C1-C2 degrees, C1-C7 degrees, and C2-C7 degrees cervical lordosis (CL) were recorded preoperatively and postoperatively. Delta (Δ) values were calculated by subtracting preoperative values from postoperative values. Correlation analysis as well as multiple linear regression analysis was used to determine relationships between radiographic and clinical outcomes. Alpha was set at 0.05. RESULTS: A total of 264 patients were included (mean follow-up 20 mo). C2 slope significantly decreased for patients after surgery (Δ=-0.8, P =0.02), as did parameters of regional cervical lordosis (Oc-C7 degrees, C1-C7 degrees, and C2-C7 degrees; P <0.001, <0.001, and 0.01, respectively). Weak to moderate associations were observed between postoperative CL and C1 inclination ( r =-0.24, P <0.001), Oc-C1 degrees ( r =0.59, P <0.001), and C1-C2 degrees ( r =-0.23, P <0.001). Increased preoperative C1-C2 degrees and Oc-C2 degrees inversely correlated with preoperative SF-12 Mental Composite Score (MCS-12) scores ( r =-0.16, P =0.01 and r =-0.13, P =0.04). Cervical sagittal vertical axis was found to have weak but significant associations with Short Form-12 (SF-12) Physical Composite Score (PCS-12) ( r =-0.13, P =0.03) and MCS-12 ( r =0.12, P =0.05). CONCLUSION: No clinically significant relationship between upper cervical and subaxial cervical alignment was detected for patients undergoing ACDF for neurological symptoms. Upper cervical spine alignment was not found to be a significant predictor of patient-reported outcomes after ACDF. LEVEL OF EVIDENCE: Level III.

How Do Patients With Predominant Neck Pain Improve After Anterior Cervical Discectomy and Fusion for Cervical Radiculopathy?

BACKGROUND: The presence of predominant pain in the arm vs the neck as a predictor of postoperative outcomes after anterior cervical discectomy and fusion (ACDF) has been seldom reported; therefore, the purpose of this study was to determine whether patients with predominant neck pain improve after surgery compared to patients with predominant arm pain or those with mixed symptoms in patients undergoing ACDF for radiculopathy. METHODS: A retrospective cohort study was conducted on patients who underwent ACDF at a single center from 2016 to 2018. Patients were split into groups based on preoperative neck and arm pain scores: neck (N) pain dominant group (visual analog scale [VAS] neck ≥ VAS arm by 1.0 point); neutral group (VAS neck < VAS arm by 1.0 point); or arm (A) pain dominant group (VAS arm ≥ VAS neck by 1.0 point), using a threshold difference of 1.0 point. Subsequently, individuals were substratified into 2 groups based on the arm to neck pain ratio (ANR): non-arm pain dominant defined as ANR ≤1.0 and arm pain dominant (APD) defined as ANR >1.0. Patient-reported outcome measurements including Neck Disability Index (NDI), Physical Component Score-12, and Mental Component Score (MCS-12) were compared between groups. RESULTS: No significant differences between groups when stratifying patients using a threshold difference of 1.0 point. When stratifying patients using the ANR, those in the APD group had significantly higher postoperative MCS-12 (P = 0.008) and NDI (P = 0.011) scores. In addition, the APD group showed a greater magnitude of improvement for MCS-12 and NDI scores (P = 0.043 and P = 0.038, respectively). Multiple linear regression showed that the A and the APD groups were both independent predictors of improvement in NDI. CONCLUSION: Patients with dominant arm pain showed significantly greater improvement in terms of MCS-12 and NDI scores compared to patients with dominant neck pain. CLINICAL RELEVANCE: To compare the impact of ACDF on arm and neck pain in the context of cervical radiculopathy using patient-reported outcome measures as an objective measurement.

Patient Factors Impacting Baseline Motor Evoked Potentials (MEPs) in Patients Undergoing Cervical Spine Surgery for Myelopathy or Radiculopathy.

STUDY DESIGN: Retrospective review of 2532 adults who underwent elective surgery for cervical radiculopathy or myelopathy with intraoperative neuromonitoring (IONM) with motor evoked potentials (MEPs) between 2017 and 2019. OBJECTIVE: Evaluate attainability of monitorable MEPs across demographic, health history, and patient-reported outcomes measure (PROM) factors. SUMMARY OF BACKGROUND DATA: When baseline IONM responses cannot be obtained, the value of IONM on mitigating the risk of postoperative deficits is marginalized and a clinical decision to proceed must be made based, in part, on the differential diagnosis of the unmonitorable MEPs. Despite known associations with baseline MEPs and anesthetic regimen or preoperative motor strength, little is known regarding associations with other patient factors. METHODS: Demographics, health history, and PROM data were collected preoperatively. MEP baseline responses were reported as monitorable or unmonitorable at incision. Multivariable logistic regression estimated the odds of having at least one unmonitorable MEP from demographic and health history factors. RESULTS: Age [odds ratio (OR)=1.031, P <0.001], sex (male OR=1.572, P =0.007), a primary diagnosis of myelopathy (OR=1.493, P =0.021), peripheral vascular disease (OR=2.830, P =0.009), type II diabetes (OR=1.658, P =0.005), and hypertension (OR=1.406, P =0.040) were each associated with increased odds of unmonitorable MEPs from one or more muscles; a history of thyroid disorder was inversely related (OR=0.583, P =0.027). P atients with unmonitorable MEPs reported less neck-associated disability and pain ( P <0.036), but worse SF-12 physical health and lower extremity (LE) and upper extremity function ( P <0.016). Compared with radiculopathy, unmonitorable MEPs in myelopathy patients more often involved LE muscles. Cord function was monitorable in 99.1% of myelopathic patients with no reported LE dysfunction and no history of hypertension or diabetes. CONCLUSION: Myelopathy, hypertension, peripheral vascular disease, diabetes, and/or symptomatic LE dysfunction increased the odds of having unmonitorable baseline MEPs. Unmonitorable baseline MEPs was uncommon in patients without significant LE weakness, even in the presence of myelopathy.

Biomechanical Analysis of the Throwing Athlete and Its Impact on Return to Sport.

Throwing sports remain a popular pastime and frequent source of musculoskeletal injuries, particularly those involving the shoulder and elbow. Biomechanical analyses of throwing athletes have identified pathomechanic factors that predispose throwers to injury or poor performance. These factors, or key performance indicators, are an ongoing topic of research, with the goals of improved injury prediction, prevention, and rehabilitation. Important key performance indicators in the literature to date include shoulder and elbow torque, shoulder rotation, kinetic chain function (as measured by trunk rotation timing and hip-shoulder separation), and lower-extremity mechanics (including stride characteristics). The current gold standard for biomechanical analysis of the throwing athlete involves marker-based 3-dimensional) video motion capture. Emerging technologies such as marker-less motion capture, wearable technology, and machine learning have the potential to further refine our understanding. This review will discuss the biomechanics of throwing, with particular attention to baseball pitching, while also delineating methods of modern throwing analysis, implications for clinical orthopaedic practice, and future areas of research interest. LEVEL OF EVIDENCE: V, expert opinion.

Postoperative Glycemic Variability as a Predictor of Adverse Outcomes Following Lumbar Fusion.

STUDY DESIGN: A retrospective cross-sectional study. OBJECTIVE: This study aims to evaluate the effect size of postoperative glycemic variability on surgical outcomes among patients who have undergone one- to three-level lumbar fusion. SUMMARY OF BACKGROUND DATA: While numerous patient characteristics have been associated with surgical outcomes after lumbar fusion, recent studies have described the measuring of postoperative glycemic variability as another promising marker. METHODS: A total of 850 patients were stratified into tertiles (low, moderate, high) based on degree of postoperative glycemic variability defined by coefficient of variation (CV). Surgical site infections were determined via chart review based on the Centers for Disease Control and Prevention definition. Demographic factors, surgical characteristics, inpatient complications, readmissions, and reoperations were determined by chart review and telephone encounters. RESULTS: Overall, a statistically significant difference in 90-day adverse outcomes was observed when stratified by postoperative glycemic variability. In particular, patients with high CV had a higher odds ratio (OR) of readmission (OR = 2.19 [1.17, 4.09]; P = 0.01), experiencing a surgical site infection (OR = 3.22 [1.39, 7.45]; P = 0.01), and undergoing reoperations (OR = 2.65 [1.34, 5.23]; P = 0.01) compared with patients with low CV. No significant association was seen between low and moderate CV groups. Higher CV patients were more likely to experience longer hospital stays (ß: 1.03; P = 0.01). Among the three groups, high CV group experienced the highest proportion of complications. CONCLUSION: Our study establishes a significant relationship between postoperative glycemic variability and inpatient complications, length of stay, and 90-day adverse outcomes. While HbA1c has classically been used as the principal marker to assess blood glucose control, our results show CV to be a strong predictor of postoperative adverse outcomes. Future high-quality, prospective studies are necessary to explore the true effect of CV, as well as its practicality in clinical practice. Nevertheless, fluctuations in blood glucose levels during the inpatient stay should be limited to improve patient results.Level of Evidence: 4.

Machine Learning and Statistical Prediction of Pitching Arm Kinetics.

BACKGROUND: Over the past decade, research has attempted to elucidate the cause of throwing-related injuries in the baseball athlete. However, when considering the entire kinetic chain, full body mechanics, and pitching cycle sequencing, there are hundreds of variables that could influence throwing arm health, and there is a lack of quality investigations evaluating the relationship and influence of multiple variables on arm stress. PURPOSE: To identify which variables have the most influence on elbow valgus torque and shoulder distraction force using a statistical model and a machine learning approach. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A retrospective review was performed on baseball pitchers who underwent biomechanical evaluation at the university biomechanics laboratory. Regression models and 4 machine learning models were created for both elbow valgus torque and shoulder distraction force. All models utilized the same predictor variables, which included pitch velocity and 17 pitching mechanics. RESULTS: The analysis included a total of 168 high school and collegiate pitchers with a mean age of 16.7 years (SD, 3.2 years) and BMI of 24.4 (SD, 1.2). For both elbow valgus torque and shoulder distraction force, the gradient boosting machine models demonstrated the smallest root mean square errors and the most precise calibrations compared with all other models. The gradient boosting model for elbow valgus torque reported the highest influence for pitch velocity (relative influence, 28.4), with 5 mechanical variables also having significant influence. The gradient boosting model for shoulder distraction force reported the highest influence for pitch velocity (relative influence, 20.4), with 6 mechanical variables also having significant influence. CONCLUSION: The gradient boosting machine learning model demonstrated the best overall predictive performance for both elbow valgus torque and shoulder distraction force. Pitch velocity was the most influential variable in both models. However, both models also revealed that pitching mechanics, including maximum humeral rotation velocity, shoulder abduction at foot strike, and maximum shoulder external rotation, significantly influenced both elbow and shoulder stress. CLINICAL RELEVANCE: The results of this study can be used to inform players, coaches, and clinicians on specific mechanical variables that may be optimized to mitigate elbow or shoulder stress that could lead to throwing-related injury.

The Role of Family-wise Error Rate in Determining Statistical Significance.

The threshold for statistical significance is determined by the maximum allowable probability of Type I error (α). For studies that test multiple hypotheses or make multiple comparisons, the probability of at least 1 Type I error (family-wise error rate; FWER) increases as the number of hypotheses/comparisons increase. It is generally best practice to set the acceptable threshold for FWER to be less than or equal to α. Bonferroni correction and Tukey honestly significant difference test are 2 of the more common methods to control for FWER. When doing exploratory analysis or evaluating secondary outcomes of a study, it may not be necessary or desirable to control for FWER, which reduces the power of the study. However, deciding to control for FWER should be decided during the design of the study.