Teruhisa Mihata1, Masaki Akeda2, Michael Künzler3, Michelle H McGarry4, Masashi Neo5, Thay Q Lee4. 1. Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan; Orthopaedic Biomechanics Laboratory, Congress Medical Foundation, Pasadena, CA, USA; Department of Orthopedic Surgery, Katsuragi Hospital, Kishiwada, Osaka, Japan. Electronic address: tmihata@yahoo.co.jp. 2. Department of Sports Orthopaedic Center, Yokohama Minami Kyosai Hospital, Yokohama, Japan. 3. Department of Orthopaedics and Traumatology, Inselspital, University Hospital Bern, Bern, Switzerland. 4. Orthopaedic Biomechanics Laboratory, Congress Medical Foundation, Pasadena, CA, USA. 5. Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
Abstract
BACKGROUND: In throwing athletes, cubital tunnel syndrome and insufficiency of the ulnar collateral ligament (UCL) are common pathologic processes of the elbow. The objective of this study was to investigate the effect of UCL tears on ulnar nerve elongation in the simulated throwing position. METHODS: Eight fresh frozen cadaveric upper limbs were tested at the simulated late cocking to acceleration phase in the throwing motion using an elbow testing system. Elbow valgus laxity and ulnar nerve length and strain under 2 Nm of applied valgus torque (maximum torque in cadaveric elbow) were evaluated. Paired t-tests were used to compare all data between intact UCLs and UCLs after complete transection of the anterior oblique ligament. Linear regression analysis was used to investigate relationships between elbow valgus laxity and ulnar nerve strain. RESULTS: Elbow valgus laxity significantly increased after transection of the UCL. Ulnar nerve length after UCL transection was significantly greater than that in the intact condition at 60° (P = .006) and 90° of elbow flexion (P < .0001). In addition, ulnar nerve strain was positive (increased) at 60° and 90° of elbow flexion. Maximum ulnar nerve strain at 90° of elbow flexion was 3.9% ± 0.9% when the UCL was intact and 6.8% ± 0.7% after transection. UCL transection yielded significant positive correlation between elbow valgus laxity and ulnar nerve strain (P = .006; r = .4714). CONCLUSION: Increased elbow valgus laxity due to UCL insufficiency may cause elongation of the ulnar nerve and exacerbate cubital tunnel syndrome during the throwing motion.
BACKGROUND: In throwing athletes, cubital tunnel syndrome and insufficiency of the ulnar collateral ligament (UCL) are common pathologic processes of the elbow. The objective of this study was to investigate the effect of UCL tears on ulnar nerve elongation in the simulated throwing position. METHODS: Eight fresh frozen cadaveric upper limbs were tested at the simulated late cocking to acceleration phase in the throwing motion using an elbow testing system. Elbow valgus laxity and ulnar nerve length and strain under 2 Nm of applied valgus torque (maximum torque in cadaveric elbow) were evaluated. Paired t-tests were used to compare all data between intact UCLs and UCLs after complete transection of the anterior oblique ligament. Linear regression analysis was used to investigate relationships between elbow valgus laxity and ulnar nerve strain. RESULTS:Elbow valgus laxity significantly increased after transection of the UCL. Ulnar nerve length after UCL transection was significantly greater than that in the intact condition at 60° (P = .006) and 90° of elbow flexion (P < .0001). In addition, ulnar nerve strain was positive (increased) at 60° and 90° of elbow flexion. Maximum ulnar nerve strain at 90° of elbow flexion was 3.9% ± 0.9% when the UCL was intact and 6.8% ± 0.7% after transection. UCL transection yielded significant positive correlation between elbow valgus laxity and ulnar nerve strain (P = .006; r = .4714). CONCLUSION: Increased elbow valgus laxity due to UCL insufficiency may cause elongation of the ulnar nerve and exacerbate cubital tunnel syndrome during the throwing motion.
Authors: Somnath Rao; Taylor D'Amore; Donald P Willier; Richard Gawel; Robert A Jack; Steven B Cohen; Michael G Ciccotti Journal: Orthop J Sports Med Date: 2021-11-23