A Cross-Sectional Study of Gender-Specific Influences of Orthopedic Subspecialty Selection.

Background: Per the American Academy of Orthopaedic Surgeons, 6.5% of practicing orthopedic surgeons are female and a majority subspecialize in pediatrics, hand, and foot and ankle surgery. The study purpose is to evaluate influences of orthopedic subspecialty selection, specifically factors such as perceived strength, lifestyle, and mentorship influence on subspecialty decisions and to identify if gender plays a role in these perceptions. Methods: An IRB approved cross-sectional study was conducted via email distribution of a REDCapTM survey to U.S. licensed orthopedic surgeons. Data regarding demographics, professional degree, training and current practice location, and perceptions regarding orthopedic surgery was obtained using Likert rating scales. Data was analyzed using descriptive statistics with two-tailed student's t-tests (α=0.05). Results: The survey yielded 282 responses (182 females and 100 males). Overall, the distribution of residents (28%), fellows (6%), and attendings (66%) correlates well with the prevalence of each respective physician category in the field of orthopedic surgery. The study demonstrated no difference in subspecialty choice based on mentorship, work-life-balance, career advancement, subspecialty culture, salary potential, family planning, or schedule. However, a statistically significant difference exists regarding stereotypes, perceived strength required, and perception of discrimination from pursuing a specific orthopedic subspecialty. 27% of females and 10% of males reported discouragement from any subspecialty (p<0.05). Adult reconstructive and oncology were most frequently discouraged. Women reported not choosing a subspecialty because of perceived physical demands more often than men (p<0.001). Women reported an increased use of adaptive strategies in the operating room (p<0.001). Women were also more likely to report feeling discouraged from pursuing a subspecialty due to their gender (p<0.001). Both men and women reported mentorship as the most influential factor in subspecialty selection. Conclusion: Women and men reported different factors were important in their decision of subspecialty. Women were more likely to be discouraged from a subspecialty and experience discrimination based on their perceived strength compared to male peers. Residents, fellows, and attending surgeons valued mentorship as the most influential in their subspeciality choice. This study suggests intrinsic and extrinsic influences that may differentially affect male and female orthopedic surgeons when they choose a subspecialty. Level of Evidence: III.

Assessing Quadriceps Muscle Contraction Using a Novel Surface Mechanomyography Sensor during Two Neuromuscular Control Screening Tasks.

Electromyography (EMG) is the clinical standard for capturing muscle activation data to gain insight into neuromuscular control, yet challenges surrounding data analysis limit its use during dynamic tasks. Surface mechanomyography (sMMG) sensors are novel wearable devices that measure the physical output of muscle excursion during contraction, which may offer potential easy application to assess neuromuscular control. This study aimed to investigate sMMG detection of the timing patterns of muscle contraction compared to EMG. Fifteen healthy participants (mean age = 31.7 ± 9.1 y; eight males and seven females) were donned with EMG and sMMG sensors on their right quadriceps for simultaneous data capture during bilateral deep squats, and a subset performed three sets of repeated unilateral partial squats. No significant difference in the total duration of contraction was detected by EMG and sMMG during bilateral (p = 0.822) and partial (p = 0.246) squats. sMMG and EMG timing did not differ significantly for eccentric (p = 0.414) and concentric (p = 0.462) phases of muscle contraction during bilateral squats. The sMMG magnitude of quadriceps excursion demonstrated excellent intra-session retest reliability for bilateral (ICC3,1 = 0.962 mm) and partial (ICC3,1 = 0.936 mm, n = 10) squats. The sMMG sensors accurately and consistently provided key quadriceps muscle performance metrics during two physical activities commonly used to assess neuromuscular control for injury prevention, rehabilitation, and exercise training.

Quantifying muscle contraction with a conductive electroactive polymer sensor: introduction to a novel surface mechanomyography device.

Clinicians seek an accurate method to assess muscle contractility during activities to better guide treatment. We investigated application of a conductive electroactive polymer sensor as a novel wearable surface mechanomyography (sMMG) sensor for quantifying muscle contractility. The radial displacement of a muscle during a contraction is detected by the physically stretched dielectric elastomer component of the sMMG sensor which quantifies the changes in capacitance. The duration of muscle activation times for quadriceps, hamstrings, and gastrocnemius muscles demonstrated strong correlation between sMMG and EMG during a parallel squat activity and isometric contractions. A moderate to strong correlation was demonstrated between the sMMG isometric muscle activation times and force output times from a dynamometer. The potential wearable application of an electroactive polymer sensor to measure muscle contraction time is supported.

Return of Scapulohumeral Rhythm in Patients After Reverse Shoulder Arthroplasty: A Midterm Stereoradiographic Imaging Analysis.

Background: Reverse shoulder arthroplasty (RSA) is associated with high rates of midterm complications including scapular notching, implant wear, and mechanical impingement. Scapulo-humeral rhythm (SHR), described by Codman in the 1920's, is defined as the ratio of glenohumeral motion to scapulothoracic motion. SHR is used as an indicator of shoulder dysfunction, as alterations in SHR can have profound implications on shoulder biomechanics. The determination of SHR can be hindered by soft-tissue motion artifacts and high radiation burdens associated with traditional surface marker or fluoroscopic analysis. EOS low dose stereoradiographic imaging analysis utilizing 3D model construction from a 2D X-ray series may offer an alternative modality for characterizing SHR following RSA. Methods: Patients (n=10) underwent an EOS imaging analysis to determine SHR at six and twelve months post-RSA. Leveraging 3D models of the implants, 2D/3D image registration methods were used to calculate relative glenohumeral and scapulothoracic positioning at 60, 90 and 120° of shoulder elevation. Subject-specific SHR curves were assessed and midterm changes in post-RSA SHR associated with follow-up time and motion phase were evaluated. Pearson correlations assessed associations between patient-specific factors and post-RSA SHR. Results: Mean post-RSA SHR was 0.81:1 across subjects during the entire midterm postoperative period. As a cohort, post-RSA SHR was more variable for 60-90° of shoulder motion. SHR for 90-120° of motion decreased (0.43:1) at twelve months post-RSA. Post-RSA SHR could be categorized using three relative motion curve patterns, and was not strongly associated with demographic factors such as BMI. 50% of subjects demonstrated a different SHR relative motion curve shape at twelve months post-RSA, and SHR during the 90120° of motion was found to generally decrease at twelve months. Conclusion: Midterm post-RSA SHR was successfully evaluated using EOS technology, revealing lower SHR values (i.e., greater scapulothoracic motion) compared to normal values reported in the literature. SHR continued to change for some subjects during the midterm post-RSA period, with the greatest change during 90-120° of shoulder motion. Study findings suggest that future post RSA rehabilitation efforts to address elevated scapulothoracic motion may benefit from being patient-specific in nature and targeting scapular stabilization during 90-120° of shoulder motion. Level of Evidence: IV.

Biological augmentation of meniscal repair: a systematic review.

PURPOSE: Orthopedic literature remains divided on the utility of biologic augmentation to optimize outcomes after isolated meniscal repair. The aim of this systematic review is to analyze the clinical outcomes and re-operation rates of biologically augmented meniscal repairs. METHODS: PubMed, CINAHL, Cochrane, and EMBASE databases were queried in October 2020 for published literature on isolated meniscal repair with biological augmentation. Studies were assessed for quality and risk of bias by two appraisal tools. Patient demographics, meniscal tear characteristics, surgical procedure, augmentation type, post-operative rehabilitation, patient reported outcome measures, and length of follow-up were recorded, reviewed, and analyzed by two independent reviewers. RESULTS: Of 3794 articles, 18 met inclusion criteria and yielded 537 patients who underwent biologic augmentation of meniscal repair. The biologically augmented repair rates were 5.8-27.0% with PRP augmentation, 0.0-28.5% with fibrin clot augmentation, 0.0-12.9% with marrow stimulation, and 0.0% with stem cell augmentation. One of seven studies showed lower revision rates with augmented meniscal repair compared to standard repair techniques, whereas five of seven found no benefit. Three of ten studies found significant functional improvement of biologically augmented repair versus standard repair techniques and six of ten studies found no difference. There was significant heterogeneity in methods for biologic preparation, delivery, and post-operative rehabilitation protocols. CONCLUSION: Patients reported significant improvements in functional outcomes scores after repair with biological augmentation, though the benefit over standard repair controls is questionable. Revision rates after biologically augmented meniscal repair also appear similar to standard repair techniques. Clinicians should bear this in mind when considering biologic augmentation in the setting of meniscal repair. LEVEL OF EVIDENCE: IV.

Comparison of Kinematic Sequences During Curveball and Fastball Baseball Pitches.

Performance of a sequential proximal-to-distal transfer of segmental angular velocity (or Kinematic Sequence) is reported to reduce stress on musculoskeletal structures and thus the probability of injury while also maximizing ball velocity. However, there is limited investigation regarding the Kinematic Sequence of the five body segments (Pelvis, Trunk, Arm, Forearm, and Hand) among baseball pitchers. Some biomechanical and epidemiology studies have reported an association of the curveball with increased risk for elbow injury among youth pitchers. Kinematic Sequences with altered distal upper extremity (forearm and hand) sequences have been associated with greater elbow valgus and shoulder external rotation torques compared to other Kinematic Sequences. Identifying Kinematic Sequence patterns during curveball pitches may lead to improved understanding of injury susceptibility. This study investigated the Kinematic Sequence patterns (and their variability) during curveball pitching and compared them to the sequences identified during fastball pitches. Using 3D motion analyses, 14 baseball pitchers (four high school, eight college, and two professional) performed 5-6 curveball pitches and 12 pitchers also threw fastball pitches in a simulated bullpen session. Eleven different curveball Kinematic Sequences were identified and 8 fastball Kinematic Sequences. There was no significant variability in the number of Kinematic Sequences performed between the two pitch types, (Z = -0.431, p = 0.67). The median number of KSs performed by each group was 2.5. The most frequently used Kinematic Sequences for both pitch types were due to alteration in the sequence of the distal segments. The total percentage of Kinematic Sequences with altered distal segment sequencing for the curveball pitches was 49% and 43% for fastball pitches. Identifying the frequency of Kinematic Sequences with altered timing of hand and forearm peak velocities across pitch types may lead to a better understanding of the stresses that individual pitchers incur.

Influence of subscapularis stiffness with glenosphere lateralization on physiological external rotation limits after reverse shoulder arthroplasty.

BACKGROUND: Repair of the subscapularis following reverse shoulder arthroplasty (RSA) remains a controversial topic among surgeons. Poor rotator cuff muscle quality is associated with increased musculotendinous stiffness, and the subsequent effect of compromised tissue repair on RSA functional outcomes remains unclear. The objective was to investigate the influence of subscapularis stiffness together with glenoid component lateralization on pre- and postimpingement joint mechanics during external rotation after RSA. METHODS: A validated finite element model incorporating the Zimmer Trabecular Metal reverse system was used. The deltoid and subscapularis tendon were tensioned and wrapped around the joint prior to controlled shoulder external rotation. Baseline subscapularis stiffness, determined from cadaveric testing, was varied to 80%, 120% and 140% of baseline, to simulate a range of pliability associated with fatty infiltration and fibrosis. We evaluated the effects of varying subscapularis stiffness and the corresponding variation in joint tension with varying glenosphere lateralization (2, 4, and 10 mm) on the torque required to externally rotate the shoulder and the impingement/subluxation risk. RESULTS: Prior to any impingement, the torques required to externally rotate the shoulder ranged from 22-47 Nm across the range of parameters studied, with the greatest torques required for the 10-mm glenosphere lateralization. The impact of increasing subscapularis stiffness on torque requirements was most pronounced at the 10-mm lateralization, as well. A 20% increase in subscapularis stiffness necessitated a 7%-14% increase in preimpingement torque, whereas a 40% stiffness increase was associated with a 12%-27% increase in torque. Torque was proportional to lateralization. When lateralization was increased from 2 to 4 mm, the preimpingement torque increased by 10%-13%, whereas a 10-mm lateralization necessitated a 35%-62% torque increase relative to 2 mm of lateralization. Increased subscapularis stiffness did not limit impingement-free range of motion or substantially decrease postimpingement subluxation in this model. DISCUSSION: Mechanical gains achieved through lateralization may be hindered by increased torque demands, especially when a stiffer subscapularis is repaired. As lateralization increases subscapularis tension, greater torque is required to externally rotate the shoulder. The torque required for external rotation has been reported between 15-50 Nm. Subscapularis repair with the simulated increases in stiffness requires relative increases in torque that the reconstructed shoulder may not be able to physically produce to rotate the glenohumeral joint, particularly at 10-mm lateralization. These results suggest that subscapularis repair may not be indicated in cases where a lateralized glenoid component is used and the subscapularis is compromised.

Rehabilitation variability after rotator cuff repair.

BACKGROUND: There has been increasing recognition of the importance for standardized postoperative rehabilitation protocols. Despite published guidelines in 2016 by the American Society of Shoulder and Elbow Therapists (ASSET), optimal postoperative rehabilitation after rotator cuff repair (RCR) remains an area of active academic debate. The goals of this study were (1) to assess the variability of RCR rehabilitation protocols published online, (2) to study the congruence between online RCR rehabilitation protocols and the ASSET consensus statement, and (3) to identify differences in online RCR rehabilitation protocols from before and after 2016. METHODS: A web-based search was conducted for publicly available RCR rehabilitation protocols from websites of all Accreditation Council for Graduate Medical Education (ACGME) academic orthopedic institutions. A supplemental 10-page Google search was also performed with the search terms "rotator cuff repair rehabilitation protocol." Collected protocols were grouped by tear size (small/medium or large/massive) and examined for information relating to the following categories: protocol demographics, adjunctive therapy use, immobilization/range of motion, and strengthening. Findings were compared to the ASSET statement's recommendations. Protocols published before and after ASSET's 2016 publication were compared for differences. RESULTS: A total of 66 online RCR rehabilitation protocols were collected. Only 16 of 187 (8.5%) ACGME institutions provided online RCR rehabilitation protocols. The collected protocols recommend more aggressive rehabilitation in comparison to ASSET, specifically regarding immobilization time, passive range of motion initiation, active assisted range of motion initiation, and strengthening initiation (P < .001). Protocols published after 2016 trended toward more conservative recommendations in comparison to protocols published before 2016. Regardless of this trend, the majority of these recommendations were still largely more aggressive than ASSET's recommendations. CONCLUSION: Despite an attempt by ASSET to provide standardization, this study highlights the marked variations that still exist regarding RCR rehabilitation. Additionally, online RCR rehabilitation protocols tend to make more aggressive recommendations than the ASSET consensus statement. Further research is needed to address these variations and to either validate, alter, or reject the ASSET recommendations.

The Relationship of Shoulder and Elbow Stresses and Upper Limb Contact Order During a Round-Off Back Handspring.

INTRODUCTION: Despite high injury incidence rates in gymnastics, there is a paucity of data characterizing upper extremity injury causation and biomechanical risk factors. This study investigated contact forces across multiple joints in both upper extremities during a round-off back handspring (ROBHS), a fundamental gymnastics tumbling maneuver. OBJECTIVE: (1) To characterize the three-dimensional (3-D) biomechanics of the sequential, asynchronous contact of each upper extremity with the ground during a ROBHS using 3-D motion capture, and (2) to evaluate potential correlations to upper extremity injury risk. DESIGN: Observational cross-sectional study. SETTING: Controlled laboratory environment. PARTICIPANTS: Fourteen competitive female gymnasts aged 10-21 years (mean age: 16.6 ± 3.1 years) (1) participating on a competitive gymnastics team; (2) capable of successfully completing a ROBHS; and (3) free of reported injury at enrollment. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Variables evaluated include joint angle, torque, compression force, ground reaction force (GRF), time to peak GRF, and limb loading rates. Variables were analyzed at the wrist, elbow, and shoulder of both limbs at ground contact. The hypothesis that these dependent variables would differ by ROBHS upper extremity contact order was formulated retrospectively after data collection. RESULTS: The first contact limb experienced significantly greater extension torque at the elbow (first: 48.89 ± 18.01 Nm, second: 22.49 ± 9.19 Nm; P = .014; CI 95% [14.83, 37.97]) and faster time to peak GRF (P < .001, CI 95% [-1.79, -0.99]). The second limb of contact experienced significantly greater abduction torque at the shoulder (P = .007; CI 95% [-21.58,-8.08]) and anterior-posterior GRF at contact (P = .007; CI 95% [-1.06,-0.26]). CONCLUSIONS: The biomechanical differences between contact limbs during the ROBHS may lead to different injury risk. Recognition of the stresses at the elbow and shoulder for both limbs also provides new insight for rehabilitation clinicians to consider when guiding patients to return to gymnastics activity after injury.

Return to Performance After Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers: A Case-Control Assessment of Advanced Analytics, Velocity, Spin Rates, and Pitch Movement.

BACKGROUND: There are limited data on the performance or pitching metrics of Major League Baseball (MLB) pitchers who returned to play after ulnar collateral ligament reconstruction (UCLR). PURPOSE: To describe MLB pitcher performance after return from primary UCLR, compare the velocity and pitch characteristics against the preoperative season, and determine if performance analytics can predict successful return to pitching after UCLR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: This study included 63 pitchers who underwent primary UCLR between 2015 and 2019. Publicly available advanced analytics and pitch metrics from the first 2 postoperative seasons were compared with the preoperative (index) season as well as with an uninjured control group. RESULTS: Overall, 57% of the pitchers successfully returned to the MLB level. Although they threw significantly fewer pitches (P = .012) and innings (P = .022) in postoperative year 1 as compared with the index season, there were no significant differences in pitch velocity, release extension, perceived velocity, or performance as measured by advanced analytics. Also, as compared with the index season, returners demonstrated increased postoperative spin rates on curveballs (P = .001) and sliders (P = .010), and curveball horizontal movement was significantly increased (P = .007); however, horizontal movement was significantly decreased for 4-seam fastballs (P = .026), changeups (P = .005), and sinkers (P = .019). The vertical movement on 4-seam fastballs was greater (P < .001) in postoperative year 1, and the vertical movement on curveballs (P = .031) and sinkers (P = .010) was greater in postoperative year 2 when compared with the index season. Pitchers who failed to return to the MLB level had a lower preoperative strikeout percentage (P = .047), fewer strikeouts per 9 innings pitched (P = .046), fewer wins above replacement ([WAR]; P = .026), and lower player value (P = .030) than the pitchers who returned. CONCLUSION: Pitchers returning to the MLB level after UCLR demonstrated changes in pitch movement profiles and spin rates postoperatively, but there were no differences in velocity or many advanced analytics upon return. Pitchers with lower strikeout metrics, fewer WAR, and less player value before surgery may have an elevated risk of failing to return to the MLB level.

Kinematic Sequence Classification and the Relationship to Pitching Limb Torques.

PURPOSE: The kinematic sequence (KS) during a baseball pitch provides insight into an athlete's ability to efficiently transfer energy and develop segmental velocities, to assess the quality of body segment position and control. Study purposes were 1) to introduce the four-category Kinematic Sequence Classification System and 2) to compare elbow and shoulder torques and shoulder distraction force across the KS categories performed during the fastball pitch. METHODS: Thirty baseball pitchers (20.0 ± 3.1 yr) underwent 3D biomechanical pitch analyses of 249 fastball pitches. Seventeen distinct KS patterns were identified and assigned into four categories: 1) The proximal-to-distal (PDS) group includes the KS closest to theoretical ideal order of the five body segments (pelvis → trunk → arm → forearm → hand). The other categories were defined based on the segment where the first out-of-sequence peak angular velocity occurred: 2) distal upper extremity (DUE), 3) proximal upper extremity, and 4) pelvis/trunk. Throwing limb shoulder distraction force and shoulder and elbow torques were calculated. Linear mixed model analyses compared variables across KS categories. RESULTS: Average elbow valgus torques differed significantly across all categories, P = 0.023, and were greater for the DUE (73.99 ± 20.84 N·m) than the PDS (61.35 ± 16.79 N·m), P = 0.006. Shoulder external rotation torques were significantly different, P = 0.033, across categories. CONCLUSION: The PDS group demonstrated less mechanical stresses on the throwing shoulder and elbow but was observed in only 12% of pitches. The DUE group was the most common and generated the greatest elbow valgus and shoulder external rotation torques. The KS can inform coaches and sports medicine clinicians where the greatest torques are incurred by a pitcher. A KS classification system may serve as a screening tool or target pitching instruction for injury avoidance.

Neuromuscular Control of Vertical Jumps in Female Adolescents.

BACKGROUND: Poor landing mechanics are considered deficits in neuromuscular control and risk factors for lower extremity injury. The Landing Error Scoring System (LESS) has been used to assess the neuromuscular control of landing mechanics for the first landing in a drop vertical jump (DVJ) task. However, the second DVJ landing may provide different results, warranting assessment. HYPOTHESES: (1) LESS scores will differ between first and second DVJ landings across all female participants with (2) greater intraparticipant variability among the second landing compared with the first landing scores. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 4. METHODS: A total of 13 gymnasts and 31 softball players (N = 44) performed 3 DVJ trials. The mean ± SD age of 44 female athletes was 16.46 ± 2.59 years. The LESS was scored using 2-dimensional video of each trial. RESULTS: There was a significant difference between the first and second DVJ landings (P < 0.01). All participants demonstrated higher LESS scores (worse landing mechanics) during the second DVJ landing (10.10 ± 2.25) than the first landing (6.97 ± 2.72). CONCLUSION: The initial landing in a DVJ has been the focus of neuromuscular control studies using the LESS. This study found worse neuromuscular control during the second DVJ landing, which highlights the importance of evaluating landing mechanics beyond the initial landing. CLINICAL RELEVANCE: LESS analysis of both DVJ landings might improve neuromuscular control screening in female athletes and augment lower extremity and anterior cruciate ligament injury prevention programs.