Editorial Commentary: The Difficulties of Assessing Return to Play and Return to Performance After Ulnar Collateral Ligament Reconstruction.

Ulnar collateral ligament (UCL) tears have moved from a career-ending injury to one in which success is almost expected from reconstruction. In reality, however, success from a UCL reconstruction is not guaranteed. As we have attempted to assess the true success rate of UCL reconstructions, we have also learned the difficulties of this assessment. Rates of return to sport after UCL reconstruction vary by level of play, the primary or revision status of the repair, along with the specific surgical techniques performed, the chronicity of the tear, the rehabilitation protocols associated with the surgery, and more. Return to sport is difficult to assess, as high school, collegiate, and even professional careers can be variable and there are no standard definitions of "returning to play." These variables also affect our assessments of performance after UCL reconstruction. Decisions for UCL reconstructions and appropriate counseling of patients regarding the likelihood of success currently remain an individual process.

Editorial Commentary: The Statistical Fragility Index of Medical Trials Is Low By Design: Critical Evaluation of Confidence Intervals Is Required.

The Fragility Index (FI) provides the number of patients whose outcome would need to have changed for the results of a clinical trial to no longer be statistically significant. Although it's a well-intended and easily interpreted metric, its calculation is based on reversing a significant finding and therefore its interpretation is only relevant in the domain of statistical significance. Its interpretation is only relevant in the domain of statistical significance. A well-designed clinical trial includes an a priori sample size calculation that aims to find the bare minimum of patients needed to obtain statistical significance. Such trials are fragile by design! Examining the robustness of clinical trials requires an estimation of uncertainty, rather than a misconstrued, dichotomous focus on statistical significance. Confidence intervals (CIs) provide a range of values that are compatible with a study's data and help determine the precision of results and the compatibility of the data with different hypotheses. The width of the CI speaks to the precision of the results, and the extent to which the values contained within have potential to be clinically important. Finally, one should not assume that a large FI indicates robust findings. Poorly executed trials are prone to bias, leading to large effects, and therefore, small P values, and a large FI. Let's move our future focus from the FI toward the CI.

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.

The Association of Baseball Pitch Delivery and Kinematic Sequence on Stresses at the Shoulder and Elbow Joints.

Although there is a commonly held belief within the baseball community that delivery from the stretch confers more stress at the elbow and shoulder joints than delivery from the windup, there remains little evidence in the literature investigating this hypothesis. This study aimed to help address this gap in the literature by studying both intra-pitcher kinematic sequence variability, and intra-pitcher joint torque variability when throwing from the windup vs. the stretch. We hypothesized that 1) each pitchers' kinematic sequence would remain similar whether throwing from the windup or stretch, and 2) Kinematic sequence would influence peak arm torque more than delivery method. This cross-sectional 3D biomechanical study included 88 pitches thrown by ten (6 collegiate, 4 high school) pitchers with a mean age of 17.60 ± 2.63 years. Pitch velocity, throwing shoulder/elbow torques and the kinematic sequence of each pitch utilizing segmental peak angular velocities were captured. No statistically significant differences in ball velocity (p = 0.17), peak shoulder external rotation torque (p = 0.80), shoulder extension torque (p = 0.97), or elbow valgus torque (p = 0.83) were found between delivery approaches. Three primary kinematic sequences were identified. Shoulder external rotation torque [F(53,2) = 10.992, ɳ2 = .293, p < 0.00], shoulder extension torque [F(53,2) = 15.517, ɳ2 = .369, p < 0.00] and elbow valgus torque [F(53,2) = 9.994, ɳ2 = .274, p < 0.00] did vary significantly across these three kinematic sequence patterns. Our data suggest that the kinematic sequence influences shoulder and elbow torque more than the delivery approach. Instructing ideal kinematic sequence may be more influential for injury avoidance than delivery method.

The relationship of elbow alignment and kinematics on shoulder torque during the softball pitch: a biomechanical analysis of female softball pitchers.

BACKGROUND: Female softball pitchers commonly throw more pitches per game and season than their baseball counterparts. The greatest stress to the shoulder during a softball windmill pitch is at ball release (BR). This study investigated shoulder torques at BR among female softball pitchers and identified relationships to the kinematics of the elbow and forearm and alignment of the elbow (carrying angle and elbow extension). METHODS: High-speed 3-dimensional biomechanical analyses were performed in 33 pitchers (25 high school, 8 collegiate). Elbow and shoulder biomechanics at BR during fastball pitches and goniometric measures of carrying angle and elbow extension were collected and analyzed. RESULTS: Carrying angle correlated positively with shoulder extension torque at BR (rs = 0.371, P = .048) and forearm pronation at BR (rs = 0.370, P = .048). During the windmill pitch, the greater the elbow flexion, the greater shoulder adduction torque at BR (rs = -0.522, P = .007). Multiple regression analysis revealed that the carrying angle, passive elbow extension, and elbow flexion/extension angle at BR predicted shoulder flexion/extension torque at BR (F3,24 = 3.463, R2 = .302, P = .032.) CONCLUSIONS: Our findings demonstrate that shoulder torques during the softball fastpitch are influenced by the carrying angle and the kinematic elbow flexion angle at BR. Sports medicine clinicians and coaches should consider the role that the elbow carrying angle plays in creating shoulder stress when treating and training fastpitch softball players.

A Wide-Range, Wireless Wearable Inertial Motion Sensing System for Capturing Fast Athletic Biomechanics in Overhead Pitching.

The standard technology used to capture motion for biomechanical analysis in sports has employed marker-based optical systems. While these systems are excellent at providing positional information, they suffer from a limited ability to accurately provide fundamental quantities such as velocity and acceleration (hence forces and torques) during high-speed motion typical of many sports. Conventional optical systems require considerable setup time, can exhibit sensitivity to extraneous light, and generally sample too slowly to accurately capture extreme bursts of athletic activity. In recent years, wireless wearable sensors have begun to penetrate devices used in sports performance assessment, offering potential solutions to these limitations. This article, after determining pressing problems in sports that such sensors could solve and surveying the state-of-the-art in wearable motion capture for sports, presents a wearable dual-range inertial and magnetic sensor platform that we developed to enable an end-to-end investigation of high-level, very wide dynamic-range biomechanical parameters. We tested our system on collegiate and elite baseball pitchers, and have derived and measured metrics to glean insight into performance-relevant motion. As this was, we believe, the first ultra-wide-range wireless multipoint and multimodal inertial and magnetic sensor array to be used on elite baseball pitchers, we trace its development, present some of our results, and discuss limitations in accuracy from factors such as soft-tissue artifacts encountered with extreme motion. In addition, we discuss new metric opportunities brought by our systems that may be relevant for the assessment of micro-trauma in baseball.

Hemoglobin A1c Levels >6.6% Are Associated With Higher Postoperative Complications After Anterior Cruciate Ligament Reconstruction.

Purpose: To investigate the relation between hemoglobin A1c (HbA1c) levels and postoperative complications after primary anterior cruciate ligament reconstruction (ACLR). Methods: A retrospective review was performed of consecutive patients with an isolated anterior cruciate ligament tear, preoperative diagnosis of diabetes, and documented HbA1c within 90 days of primary ACLR between 2000 and 2019. Data collected included demographic and surgical characteristics, 90-day medical complications, and subsequent surgeries on the ipsilateral knee. A receiver operating curve was constructed for each HbA1c level in relation to postoperative complications and the optimal cutoff identified via Youden's J statistic. Multivariable logistic regression was performed to assess the relation between postoperative complications and age, sex, graft type, diabetes subtype, and HbA1c. Results: Nineteen patients (7 females, 12 males) fulfilled inclusion criteria with preoperative HbA1c ranging from 5.5 to 10. Complications included septic knee (n = 1) and cyclops lesions requiring arthroscopic lysis (n = 3). Patients with HbA1c of 6.7% or higher were 25 times more likely to experience any postoperative complication (P = .04) and 16 times more likely to require lysis of adhesions (P = .08). On multivariable regression, HbA1c remained significantly associated with any complication (P = .005) and developing arthrofibrosis (P = .02) independent of age, sex, graft type, and diabetes subtype. Conclusions: Diabetic patients undergoing primary ACLR with a preoperative HbA1c of 6.7% or higher were 25 times more likely to require repeat surgical intervention for a postoperative complication. These complications included arthrofibrosis and infection. Strict glycemic control may help minimize the risk of postoperative complications after ACLR. Level of Evidence: Level III, retrospective cohort study.

Fellow Efficiency During Anterior Cruciate Ligament Reconstruction Improves Over Time, Yet Is Less Than Experienced Physician Assistant But With No Significant Difference in Patient-Reported Outcomes.

Purpose: To evaluate the intraoperative efficiency and patient outcomes of anterior cruciate ligament reconstruction (ACLR) assisted by a sports medicine fellow over the course of the academic year compared with an experienced physician assistant (PA). Methods: A single-surgeon cohort of primary ACLRs with either bone-tendon-bone autograft or bone-tendon-bone allograft (without any other significant time-consuming procedures such as meniscectomy/repair) were evaluated using a patient registry system over 2 years assisted by an experienced PA compared with an orthopaedic surgery sports medicine fellow. There were 264 primary ACLRs included in this study. Outcomes included evaluation of surgical time, tourniquet time, and patient-reported outcome measures. Results: The surgical efficiency of the fellow (as measured by surgical time and tourniquet time) improved over each academic quarter. Patient-reported outcomes between the 2 first-assist groups showed no significant difference over 2 years with both ACL graft groups combined. ACLRs assisted by the PA showed shorter tourniquet times by 22.1% and shorter total surgical times by 11.9% compared with the sports medicine fellows when both grafts were combined (P < .001). The surgical and tourniquet times (minutes) for the fellow (standard deviation of surgical time 19.5-25.0 and tourniquet time 19.5-25.0) did not average out to be more efficient in any of the 4 quarters of the year compared with the PA-assisted group (standard deviation of surgical time 14.4-14.8 and tourniquet time 14.8-22.4). Autografts showed more efficient tourniquet (18.7%) and skin-to-skin surgical times (11.1%) in the PA group compared with the fellow group (P < .001). Allografts showed more efficient tourniquet (37.7%) and skin-to-skin surgical times (12.8%) in the PA group compared with the fellow group (P < .001). Conclusions: The surgical efficiency of the fellow during primary ACLRs improves over the academic year. Patient-reported outcomes are similar in cases assisted by the fellow compared with an experienced physician assistant. Cases assisted by the PA were performed more efficiently compared with the sports medicine fellow. Clinical Relevance: The intraoperative efficiency of a sports medicine fellow objectively improves over the academic year for primary ACLRs but may not be as efficient as an experienced advanced practice provider; however, there appears to be no significant differences in patient-reported outcome measures between the 2 groups. This helps quantify the time commitment for attendings and academic medical institutions as the "cost of education" of trainees such as fellows.

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.

In Vivo Length Changes Between the Attachments of the Medial Patellofemoral Complex Fibers in Knees With Anatomic Risk Factors for Patellar Instability.

BACKGROUND: Medial patellofemoral complex (MPFC) reconstruction plays an important role in the surgical treatment of patellar instability. Anatomic reconstruction is critical in re-creating the native function of the ligament, which includes minimizing length changes that occur in early flexion. Anatomic risk factors for patellar instability such as trochlear dysplasia, patella alta, and increased tibial tuberosity to trochlear groove (TT-TG) distance have been shown to influence the function of the MPFC graft in cadaveric studies, but the native length change patterns of the MPFC fibers in knees with anatomic risk factors have not been described. PURPOSE: To describe the in vivo length changes of the MPFC fibers in knees with anatomic risk factors for patellar instability and identify the optimal attachment sites for MPFC reconstruction. STUDY DESIGN: Controlled laboratory study. METHODS: Dynamic computed tomography imaging was performed on the asymptomatic knee in patients with contralateral patellar instability. Three-dimensional digital knee models were created to assess knees between 0° and 50° of flexion in 10° increments. MPFC fiber lengths were calculated at each flexion angle between known anatomic attachment points on the extensor mechanism (quadriceps tendon, MPFC midpoint [M], and patella) and femur (1, 2, and 3, representing the proximal to distal femoral footprint). Changes in MPFC fiber length were compared for each condition and assessed for their relationships to morphologic risk factors (trochlear depth, Caton Deschamps Index [CDI], and TT-TG distance). RESULTS: In 22 knees, native MPFC fibers were found to be longer at 0° than at 20° to 50° of flexion. Length changes observed between 0° and 50° increased with the number of risk factors present. In the central fibers of the MPFC (M-2), 1.7% ± 3.1% length change was noted in knees with no anatomic risk factors, which increased to 5.6% ± 4.6%, 17.0% ± 6.4%, and 26.7% ± 6.8% in the setting of 1, 2, and 3 risk factors, respectively. Nonanatomic patella-based attachments were more likely to demonstrate unfavorable length change patterns, in which length was greater at 50° than 0°. In patellar attachments, an independent relationship was found between increasing length changes and TT-TG distance, while in quadriceps tendon attachments, a trend toward a negative relationship between length changes and CDI was noted. All configurations demonstrated a strong relationship between percentage change in length and number of morphologic risk factors present, with the greatest influence found in patella-based attachments. CONCLUSION: The MPFC fibers demonstrated increased length changes in knees when a greater number of morphological risk factors for patellar instability were present, which worsened in the setting of nonanatomic configurations. This suggests that the function of the intact MPFC in patients with anatomic risk factors may not reflect previously described findings in anatomically normal knees. Further studies are needed to understand the pathoanatomy related to these changes, as well as the implications for graft placement and assessment of length changes during MPFC reconstruction techniques. CLINICAL RELEVANCE: MPFC length change patterns vary based on the number of morphologic risk factors for patellar instability present and should be considered during reconstructive procedures.

New Opportunities in Assessing Return to Performance in the Elite Athlete: Unifying Sports Medicine, Data Analytics, and Sports Science.

Sports medicine literature has historically reported return to sport rates, but recent interest has shifted to return to previous performance. However, the measurement and understanding of performance in the elite athlete population has continued to evolve. Recent advancements in sport analytics, wearable technology, and player-tracking systems have improved our understanding of performance in the elite athlete. Sports medicine researchers should collaborate with sports science teams to continue investigating the validity and reliability of emerging technology, assist in interpretation of big data, and remain accountable to the goals of our athletic population. Future studies in sports medicine should consider using these detailed, granular assessments to address the demands of the elite athlete population.

Selecting the Next Class: The "Virtual Orthopaedic Rotation".

INTRODUCTION: When the COVID-19 pandemic forced the cancellation of visiting subinternships, we pivoted to create a virtual orthopaedic rotation (VOR). The purpose of this study was to assess the effect of the VOR on the residency selection process and determine the role of such a rotation in the future. METHODS: A committee was convened to create a VOR to replace visiting orthopaedic rotations for medical students who are interested in pursuing a career in orthopaedic surgery. The VOR was reviewed and sanctioned by our medical school, but no academic credit was granted. We conducted three 3-week VOR sessions. During each session, virtual rotators participated in regularly scheduled educational conferences and attended an invitation-only daily conference in the evenings that was designed for a medical student audience. In addition, students were paired with faculty and resident mentors in a structured mentorship program. Students' orthopaedic knowledge was assessed using prerotation and postrotation tests. RESULTS: From July to September 2020, 61 students from 37 distinct medical schools participated in the VOR. Notable improvements were observed in prerotation and postrotation orthopaedic knowledge test scores. In postrotation surveys, both students and faculty expressed high satisfaction with the curriculum but less certainty about how well they got to know each other. In the subsequent residency application cycle, 27.9% of the students who participated in the VOR were selected to interview, compared with 8.7% of the total application pool. DISCUSSION: The VOR was a valuable substitute for in-person clinical rotations during the COVID-19 pandemic. Although not likely to be a replacement for conventional away rotations, the VOR is a possible adjunct to in-person clinical rotations in the future.

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.

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.

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.

Telemedicine in the Era of COVID-19: The Virtual Orthopaedic Examination.

With the onset of the COVID-19 pandemic, the shifting of clinical care to telemedicine visits has been hastened. Because of current limitations in resources, many elective surgeons have been forced to venture into utilizing telemedicine, in which the standards for orthopaedic examinations have not previously been fully developed. We report our experience with protocols and methods to standardize these visits to maximize the benefit and efficiency of the virtual orthopaedic examination. At the time of scheduling, patients are asked to prepare for their virtual visit and are given a checklist. In addition to confirming audiovisual capabilities prior to the visit, patients are given specific instructions on camera positioning, body positioning, setting, and attire to improve the efficiency of the visit. During the examination, digital tools can be utilized as needed. In the setting of outpatient injury evaluations, a systematic virtual examination can aid in triaging and managing common musculoskeletal conditions. With the rapid incorporation of telehealth visits, as well as the unknown future with regard to the pandemic, the utilization and capabilities of telemedicine will continue to expand. Future directions include the development of validated, modified examination techniques and new technology that will allow for improved interactive physical examinations, as we rapidly move forward into the realm of telemedicine due to unexpected necessity.

Kinematic sequence patterns in the overhead baseball pitch.

Conceptually, an efficient baseball pitch demonstrates a proximal-to-distal transfer of segmental angular velocity. Such a timing pattern (or kinematic sequence) reduces stress on musculoskeletal structures of the throwing arm and maximises ball velocity. We evaluated the variability of kinematic sequences in 208 baseball pitches. 3D biomechanical pitch analyses were performed on 8-10 fastball pitches from 22 baseball pitchers (5 high school, 11 collegiate and 6 professional). The kinematic sequence patterns - time of peak angular velocity of five body segments: pelvis, trunk, arm, forearm and hand - were measured. None of the pitches analysed demonstrated an entirely proximal-to-distal kinematic sequence. Fourteen different kinematic sequence patterns were demonstrated, with the most prevalent sequence being pelvis â†’ trunk â†’ arm â†’ hand â†’ forearm. Fewer than 10% of the pitchers performed only one kinematic sequence pattern across the sampled pitches. The variability of the kinematic sequence was similar in high-school pitchers and professionals. Previous studies report that deviation from the proximal-to-distal kinematic sequence is associated with increased injury risk. As a method of evaluating the efficient transfer of energy to the hand, the kinematic sequence may provide insight to injury risk in the future. The ideal kinematic sequence and ideal variability of the sequence when throwing have yet to be determined.

A biomechanical analysis of bone-patellar tendon-bone grafts after repeat freeze-thaw cycles in a cyclic loading model.

The purpose of this study was to examine the biomechanical effects of bone-patellar tendon-bone (BPTB) grafts subject to repeat freeze-thaw cycles in a cyclic loading model. We hypothesized that repeat freeze-thaw cycles have deleterious effects on the tensile properties of BPTB grafts. Thirty BPTB composite grafts were harvested from porcine knee specimens. Tendons were randomized into 3 groups: fresh, 1 freeze-thaw cycle (-80 degrees C), or 2 freeze-thaw cycles. The grafts were cyclically loaded to simulate the forces on the anterior cruciate ligament during walking and running, prior to single cycle load-to-failure testing. All tendon failures were mid-substance and occurred during the single cycle load-to-failure testing. There was no statistically significant difference in ultimate stress or strain between the groups. Repeat freeze-thaw cycles do not have deleterious effects on the tensile properties of BPTB grafts in a cyclic loading model. Potential influence on biologic graft healing or integration remains unknown.

Extracorporeal shock wave for chronic proximal plantar fasciitis: 225 patients with results and outcome predictors.

UNLABELLED: Plantar fasciitis can be a chronic and disabling cause of foot pain in the adult population. For refractory cases, extracorporeal shock wave therapy (ESWT) has been proposed as therapeutic option to avoid the morbidity of surgery. We hypothesized that the success of extracorporeal shock wave therapy in patients with chronic plantar fasciitis is affected by patient-related factors. A retrospective review of 225 patients (246 feet) who underwent consecutive ESWT treatment by a single physician at our institution between July 2002 and July 2004 was performed. Subjects were included only if they had plantar fasciitis for more than 6 months and failure to response to at least 5 conservative modalities. Patients were evaluated prospectively with health questionnaires, Roles and Maudsley scores, and American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot scores at regular intervals. Follow-up was 30.2 +/- 8.7 months post procedure. Multivariable analysis was performed to assess factors leading to successful outcomes. Success rates of 70.7% at 3 months and 77.2% at 12 months were noted in this population. Previous cortisone injections, body mass index, duration of symptoms, presence of bilateral symptoms, and plantar fascia thickness did not influence the outcome of ESWT. The presence of diabetes mellitus, psychological issues, and older age were found to negatively influence ESWT outcome. Whereas many factors have been implicated in the development of plantar fasciitis, only diabetes mellitus, psychological issues, and age were found to negatively influence ESWT outcome. LEVEL OF CLINICAL EVIDENCE: 2.

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.