PAPER 001: THE EFFECTS OF BASIC FIBROBLAST GROWTH FACTOR ON ACUTE ROTATOR CUFF INJURY IN A RAT SHOULDER MODEL

Abstract

Purpose: To determine if administration of recombinant bFGF in an alginate gel would increase early healing mechanical parameters in acutely injured rat rotator cuff tendon at specific time points.

Method: Sprague Dawley rats were randomly divided into 2 groups and had surgically created 1mm (half tendon width) full thickness injuries at exactly 2mm from insertion site of Infraspinatus on the humerus. 200ng of bFGF or vehicle control was administered to randomly chosen rats. Tendons were harvested at 1 week, 2 weeks and 4 weeks. In both groups, the Infraspinatus tendon was dissected, and left attached to the humerus. At the time of testing, the intact portion of the injured tendon was divided sharply across tendon fibers at the level of the injury leaving only the healing tissue callus in continuity with the remaining proximal and distal portions of the tendon and loaded to failure.

Results: At 1 week the injury group’s average load to failure was 0.60N versus 0.61N in the bFGF injury group P = 1.000. At 2 weeks the injury group’s average load to failure increased to 1.03N versus 2.08N in the bFGF injury group P = 0.440 At 4 weeks the injury group’s average load to failure increased to 3.93N versus 5.56N in the bFGF injury group P = 0.008 representing a 41% increase in ultimate load. At 4 weeks, callus size of the injury group was 0.4mm2 versus 2.7mm2 in the bFGF injury group P < 0.001. Stiffness at 4 weeks for the injury tendons was 2.15 N/mm versus 3.54 N/mm in the bFGF group P = 0.008.

Conclusion: At 4 weeks healing tissue of acutely injured rotator cuff exposed to bFGF has an increase in ultimate load to failure (41% compared to control), increase in tendon callus size and stiffness. Our findings suggest a role of bFGF or similar growth factors in accelerating the healing of injured rotator cuff tendon.