Development and use of an animal model to study post‐traumatic stiffness and contracture of the elbow

Abstract

Post-traumatic joint stiffness (PTJS) of the elbow is a debilitating condition that poses unique treatment challenges. While previous research has implicated capsular tissue in PTJS, much regarding the development and progression of this condition remains unknown. The objective of this study was to develop an animal model of post-traumatic elbow contracture and evaluate its potential for studying the etiology of PTJS. The Long-Evans rat was identified as the most appropriate species/breed for development due to anatomical and functional similarities to the human elbow joint. Two surgical protocols of varying severity were utilized to replicate soft tissue damage seen in elbow subluxation/dislocation injuries, including anterior capsulotomy and lateral collateral ligament transection, followed by 6 weeks of unilateral joint immobilization. Following sacrifice, flexion-extension mechanical joint testing demonstrated decreased range-of-motion and increased stiffness for injured-immobilized limbs compared to control and sham animals, where functional impact correlated with severity of injury. Histological evaluation showed increased cellularity, adhesion, and thickness of capsule tissue in injured limbs, consistent with clinical evidence. To our knowledge, this is the first animal model capable of examining challenges unique to the anatomically and biomechanically complex elbow joint. Future studies will use this animal model to investigate mechanisms responsible for PTJS. ß

Persistent motion loss after free joint mobilization in a rat model of post-traumatic elbow contracture

“…Long-Evans rats (Charles River Laboratories International, Wilmington, MA) were selected and used based on criteria previously described 10 . Briefly, these animals were evaluated based on their (1) anatomical similarities, (2) functional ROM of the joint and (3) use of their upper extremities.…”

“…The study utilized forty rats initially; after excluding four samples because of dissection and testing abnormalities, a total of thirty-six rats were included ( n = 7–10/group). Clinically relevant elbow injuries were surgically created to replicate varying degrees of soft-tissue injury seen in elbow subluxation/dislocation, as described previously 10 . Briefly, the animals in each surgical group were anesthetized and surgery was performed under sterile conditions on the left limb: Sham (superficial lateral incision without violation of joint structures), Injury I (anterior capsulotomy) and Injury II (anterior capsulotomy combined with lateral collateral ligament transection).…”

“…As described previously 10 , the injured limbs were immobilized using tubular elastic netting (Nich Marketers Inc., Gulf Breeze, FL) and self-adhering Vetrap bandaging (3M™, St. Paul, MN). An access hole was cut to leave the CL limb unconstrained.…”

“…During the six-week immobilization period, animals were evaluated 5X/week to ensure the injured limb was constrained and to identify any pain or distress. Clean wraps were applied weekly and additional details regarding animal care and observation during the immobilization period were provided previously 10 . Any time an animal was rewrapped, any sores or cuts caused by scratching or rubbing of the wrap were treated topically with antibiotic powder/cream (nitrofurazone (Neogen Corporation, Lexington, KY), silver sulfadiazine (Dr. Reddy’s Laboratories Louisiana, Shreveport, LA)) and/or chafing cream (Prestige Brands, Tarrytown, NY).…”

“…Previously, our group developed an animal model of elbow PTJC 10 . We demonstrated that elbow contracture could be induced in Long-Evans rats by surgically creating a soft tissue injury followed by six-weeks of immobilization.…”