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The impact of throwing arm mechanics on elbow torque: within-subject variation for professional baseball pitchers
J Shoulder Elbow Surg Volume 26, Number 5
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torque was reduced by 1.3 Nm for bullpen throwing, 5.5 Nm for long toss at 120 feet, and 8.2 Nm for long toss at 90 feet. Discussion and conclusions: To our knowledge, this represents the first report of on-field, practical, and inexpensive wearable technology that can be used to assess workload during the throwing motion. A number of key factors (type of throw, arm speed, and shoulder rotation) that influence the workload exerted on the elbow were identified and quantified. These data may be used to help identify patients at risk for elbow injuries, develop prevention programs, and better guide return to throw programs following injury in baseball.
Figure 3
Ulnar internal rotation angle.
is known that an MUCL insufficient elbow experiences an increase in valgus angle with applied valgus stress, a propensity of the ulna to go into internal rotation under the same condition has not been described. Ulnar internal rotation may elongate not only the AOL of MUCL but also adjacent tissues such as the medial portion of the anterior capsule and fan like portion of the POL. To prevent this from occurring, additional stability measures such as augmentation of adjacent tissues may be a necessary step in MUCL reconstruction in order to attain better elbow stability.
Paper #46 THE IMPACT OF THROWING ARM MECHANICS ON ELBOW TORQUE: WITHIN-SUBJECT VARIATION FOR PROFESSIONAL BASEBALL PITCHERS
Christopher L. Camp, MDa, Brittany Dowling, MSc, Travis Tubbs, MSc, Glenn S. Fleisig, PhD d , David M. Dines, MD d , David W. Altchek, MDd, Joshua S. Dines, MDd, aHospital for Special Surgery, New York, New York, USA; bSports Medicine and Shoulder Service, Department of Orthopedic Surgery, Hospital for Special Surgery, New York, New York, USA; c Research and Development, Motus Global, Massapequa, New York, USA; dAmerican Sports Medicine Institute, Birmingham, Alabama, USA Introduction: Despite numerous prevention strategies, elbow injuries are on the rise in professional baseball. This is likely do to the high level of strain exerted across the elbow during the throwing motion. In order to identify at risk athletes and guide post injury return to throw programs, a better understanding of the variables that influence elbow workload is desired. The purpose of this work is to utilize wearable technology to determine the factors that have the greatest influence on elbow torque for baseball pitchers during regular, onfield activities. Methods: A total of 88 professional pitchers performed 32,499 throws while wearing a motus Baseball sleeve (Motus Global; Massapequa, NY). These throws represented a combination of warming up, structured long toss, bull pen throwing from a mound, and live game activity. Player specific demographics such as height, weight, and handedness were documented. For each throw, the following variables were recorded: distance, pitch type, situation, arm slot, arm speed, shoulder rotation, and elbow torque. Linear mixed-effect models were utilized to determine the impact of each variable on elbow torque across all athletes and within individual athletes. Sub-group analysis for the most commonly occurring situations (game, bullpen, long toss, etc) was performed on 16,089 throws. Results: The mean height and weight (±standard deviation) of pitchers was 185.6 ± 5 cm and 93.7 ± 10 kg respectively. For all throwing situations, arm slot did not significantly affect torque (P = .10). Both arm speed (P < .001) and amount of shoulder rotation (P < .001) affected torque. Within individual athletes, elbow torque increased by 1 Nm for every 103 degrees per second increase in arm speed and/or for every 5 degree decrease in shoulder rotation. Relative to live game throws, elbow
Paper #47 DISTAL TIBIA AND GLENOID ALLOGRAFTS ARE BEST FOR RESTORATION OF OVERALL GLENOID CONGRUENCY IN SCAPULAE WITH AN ANTERIOR GLENOID RIM DEFECT
Laurent B. Willemot, MDa, Mohsen A. Shandiza, Kristin D. Zhaoa, Joaquin Sanchez-Sotelo, MD, PhDa, Olivier Verborgt, MD, PhDb, a Mayo Clinic, Rochester, Minnesota, USA; bAZ Monica, Antwerp, Belgium Introduction: Bone augmentation procedures have become the surgical technique of choice for patients with recurrent anterior glenohumeral instability in the presence of substantial anterior glenoid bone loss. Graft surface geometry is vital in the accurate reconstruction of glenoid congruity and constraint. (Gupta et al. 2013) This study aims to compare the accuracy of bone and soft tissue restoration of the anterior glenoid rim using various grafting techniques. Methods: Computed tomography scans of the potted scapulae of 8 male cadaveric shoulders were acquired in the intact condition, after creating a 25% width anterior glenoid defect, and after reconstruction of the defect using the following techniques: classic Latarjet (Mizuno et al. 2014), congruent arc Latarjet (Burkhart et al. 2007), tricortical iliac crest (inner and outer table) (Lunn et al. 2008), distal tibia (Provencher et al. 2009) and glenoid allograft (Skendzel et al. 2011). Grafts were placed flush with the articular surface in all conditions. Surface area, axial and coronal radius of curvature, as well as depth restoration were extracted from three dimensional models in bone and softtissue windows. Reconstruction methods were compared to the intact condition in a matched pair-wise manner. Results are given as a percentage of the mean intact parameter. Results: In bone models without soft tissues, surface area was most accurately restored by glenoid allografts (101.4%), whereas the iliac outer crest performed the worst (110.7%, P < .05). The smallest mean difference in antero-posterior curvature was observed with the glenoid allograft (99.5%), the largest difference was seen with the classic Latarjet (166.9%, P < .05). The smallest difference in supero-inferior curvature was seen with the tibial allograft (116.1%), the largest difference was seen with the congruent arc Latarjet (195.1%, P < .05). In models including both bone and soft-tissue, surface area was optimally reconstructed by the glenoid allograft (100.0%), whereas classic latarjet performed the worst (66.9%, P < .05). The smallest mean difference in antero-posterior curvature was observed with the glenoid allograft (99.8%), the largest difference was seen with the congruent arc Latarjet (72.8%, P < .05). The smallest mean difference in supero-inferior curvature was seen with the tibial allograft (112.6%), the largest difference was seen with the congruent arc Latarjet (167.7%, P < .05). Conclusion: Overall, glenoid allografts most closely restored glenoid geometry to the intact condition in both bone and soft-tissue windows. However, tibial allografts matched the coronal curvature of the glenoid even closer. The congruent arc Latarjet procedure produced the worst results in axial curvature for bone, and in coronal curvature for bone and soft tissue. This is in contrasts with previous publications describing the isolated morphology of the coracoid. (Noonan et al. 2014, Dehaan et al. 2013, Armitage et al. 2011. The results of our study seem to indicate that novel graft sources such as the distal tibia and glenoid may be best suited for accurate reconstruction of the overall morphology and congruency of the glenoid in shoulders with an anterior glenoid rim defect. The benefit of improved joint congruency needs to be balanced against
e165
torque was reduced by 1.3 Nm for bullpen throwing, 5.5 Nm for long toss at 120 feet, and 8.2 Nm for long toss at 90 feet. Discussion and conclusions: To our knowledge, this represents the first report of on-field, practical, and inexpensive wearable technology that can be used to assess workload during the throwing motion. A number of key factors (type of throw, arm speed, and shoulder rotation) that influence the workload exerted on the elbow were identified and quantified. These data may be used to help identify patients at risk for elbow injuries, develop prevention programs, and better guide return to throw programs following injury in baseball.
Figure 3
Ulnar internal rotation angle.
is known that an MUCL insufficient elbow experiences an increase in valgus angle with applied valgus stress, a propensity of the ulna to go into internal rotation under the same condition has not been described. Ulnar internal rotation may elongate not only the AOL of MUCL but also adjacent tissues such as the medial portion of the anterior capsule and fan like portion of the POL. To prevent this from occurring, additional stability measures such as augmentation of adjacent tissues may be a necessary step in MUCL reconstruction in order to attain better elbow stability.
Paper #46 THE IMPACT OF THROWING ARM MECHANICS ON ELBOW TORQUE: WITHIN-SUBJECT VARIATION FOR PROFESSIONAL BASEBALL PITCHERS
Christopher L. Camp, MDa, Brittany Dowling, MSc, Travis Tubbs, MSc, Glenn S. Fleisig, PhD d , David M. Dines, MD d , David W. Altchek, MDd, Joshua S. Dines, MDd, aHospital for Special Surgery, New York, New York, USA; bSports Medicine and Shoulder Service, Department of Orthopedic Surgery, Hospital for Special Surgery, New York, New York, USA; c Research and Development, Motus Global, Massapequa, New York, USA; dAmerican Sports Medicine Institute, Birmingham, Alabama, USA Introduction: Despite numerous prevention strategies, elbow injuries are on the rise in professional baseball. This is likely do to the high level of strain exerted across the elbow during the throwing motion. In order to identify at risk athletes and guide post injury return to throw programs, a better understanding of the variables that influence elbow workload is desired. The purpose of this work is to utilize wearable technology to determine the factors that have the greatest influence on elbow torque for baseball pitchers during regular, onfield activities. Methods: A total of 88 professional pitchers performed 32,499 throws while wearing a motus Baseball sleeve (Motus Global; Massapequa, NY). These throws represented a combination of warming up, structured long toss, bull pen throwing from a mound, and live game activity. Player specific demographics such as height, weight, and handedness were documented. For each throw, the following variables were recorded: distance, pitch type, situation, arm slot, arm speed, shoulder rotation, and elbow torque. Linear mixed-effect models were utilized to determine the impact of each variable on elbow torque across all athletes and within individual athletes. Sub-group analysis for the most commonly occurring situations (game, bullpen, long toss, etc) was performed on 16,089 throws. Results: The mean height and weight (±standard deviation) of pitchers was 185.6 ± 5 cm and 93.7 ± 10 kg respectively. For all throwing situations, arm slot did not significantly affect torque (P = .10). Both arm speed (P < .001) and amount of shoulder rotation (P < .001) affected torque. Within individual athletes, elbow torque increased by 1 Nm for every 103 degrees per second increase in arm speed and/or for every 5 degree decrease in shoulder rotation. Relative to live game throws, elbow
Paper #47 DISTAL TIBIA AND GLENOID ALLOGRAFTS ARE BEST FOR RESTORATION OF OVERALL GLENOID CONGRUENCY IN SCAPULAE WITH AN ANTERIOR GLENOID RIM DEFECT
Laurent B. Willemot, MDa, Mohsen A. Shandiza, Kristin D. Zhaoa, Joaquin Sanchez-Sotelo, MD, PhDa, Olivier Verborgt, MD, PhDb, a Mayo Clinic, Rochester, Minnesota, USA; bAZ Monica, Antwerp, Belgium Introduction: Bone augmentation procedures have become the surgical technique of choice for patients with recurrent anterior glenohumeral instability in the presence of substantial anterior glenoid bone loss. Graft surface geometry is vital in the accurate reconstruction of glenoid congruity and constraint. (Gupta et al. 2013) This study aims to compare the accuracy of bone and soft tissue restoration of the anterior glenoid rim using various grafting techniques. Methods: Computed tomography scans of the potted scapulae of 8 male cadaveric shoulders were acquired in the intact condition, after creating a 25% width anterior glenoid defect, and after reconstruction of the defect using the following techniques: classic Latarjet (Mizuno et al. 2014), congruent arc Latarjet (Burkhart et al. 2007), tricortical iliac crest (inner and outer table) (Lunn et al. 2008), distal tibia (Provencher et al. 2009) and glenoid allograft (Skendzel et al. 2011). Grafts were placed flush with the articular surface in all conditions. Surface area, axial and coronal radius of curvature, as well as depth restoration were extracted from three dimensional models in bone and softtissue windows. Reconstruction methods were compared to the intact condition in a matched pair-wise manner. Results are given as a percentage of the mean intact parameter. Results: In bone models without soft tissues, surface area was most accurately restored by glenoid allografts (101.4%), whereas the iliac outer crest performed the worst (110.7%, P < .05). The smallest mean difference in antero-posterior curvature was observed with the glenoid allograft (99.5%), the largest difference was seen with the classic Latarjet (166.9%, P < .05). The smallest difference in supero-inferior curvature was seen with the tibial allograft (116.1%), the largest difference was seen with the congruent arc Latarjet (195.1%, P < .05). In models including both bone and soft-tissue, surface area was optimally reconstructed by the glenoid allograft (100.0%), whereas classic latarjet performed the worst (66.9%, P < .05). The smallest mean difference in antero-posterior curvature was observed with the glenoid allograft (99.8%), the largest difference was seen with the congruent arc Latarjet (72.8%, P < .05). The smallest mean difference in supero-inferior curvature was seen with the tibial allograft (112.6%), the largest difference was seen with the congruent arc Latarjet (167.7%, P < .05). Conclusion: Overall, glenoid allografts most closely restored glenoid geometry to the intact condition in both bone and soft-tissue windows. However, tibial allografts matched the coronal curvature of the glenoid even closer. The congruent arc Latarjet procedure produced the worst results in axial curvature for bone, and in coronal curvature for bone and soft tissue. This is in contrasts with previous publications describing the isolated morphology of the coracoid. (Noonan et al. 2014, Dehaan et al. 2013, Armitage et al. 2011. The results of our study seem to indicate that novel graft sources such as the distal tibia and glenoid may be best suited for accurate reconstruction of the overall morphology and congruency of the glenoid in shoulders with an anterior glenoid rim defect. The benefit of improved joint congruency needs to be balanced against