Pedro Beredjiklian - Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
Amir Kachooei - ۲ Rothman Orthopedic Institute, Adventhealth, Orlando, FL, USA ۳ University of Central Florida, Orlando, FL, USA
Greg Gallant - Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
Jack Abboudi - Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
Moody Kwok - Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
Robert Takei - Rothman Orthopedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
Robert Hotchkiss - Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY, USA

Objectives: This study examines the pattern of muscular contraction and the intensity of this contraction of the biceps and triceps following elbow surgery. Methods: We performed a prospective electromyographic study of ۱۶ patients undergoing ۱۹ surgical procedures on the elbow joint. We measured the resting EMG signal intensity of the biceps and triceps of the operated and the normal sides at ۹۰ degrees. We then calculated the peak EMG signal intensity during passive elbow flexion and extension of the operated side. Results: Seventeen of ۱۹ elbows (۸۹%) displayed a co-contraction pattern of the biceps and triceps near the end of flexion and extension during the passive range of motion. The co-contraction pattern was observed near the end of the range of motion in both flexion and extension. In addition to the observed co-contraction patterns, we detected higher contraction intensities for the biceps and triceps muscles in all patients in both flexion and extension for the elbows, which had been treated surgically. Further analysis suggests an inverse correlation between the biceps contraction intensity and the arc of motion measured at the latest follow-up. Conclusion: The co-contraction pattern and increased contraction intensity of periarticular muscle groups may result in internal splinting mechanisms, contributing to the development of elbow joint stiffness, which is frequently observed following elbow surgery. Level of evidence: III

Biceps, Co-contraction, Elbow contracture, EMG, Heterotopic ossification, Instability, Triceps