Objective: To evaluate the effects of local triamcinolone (TAC) injection and weight bearing on healing process of the injured Achilles tendon.

Method: The right Achilles tendons in 54 rats, Sprague- Dawley (about 200 g), were each sutured after transection and allocated into three groups according to the amount of the local injection of TAC (none, 0.25 mg, and 1.25 mg respectively), and subsequently each group divided into three subgroups by the type of weight bearing {normal weight bearing (NWB), treadmill exercise (7∼8 m/min, 10 min/day) from day 7 for 7 days, and hind limb immobilization respectively}. On 15th day rats were sacrificed, and then diameters of both injured and uninjured tendon, numbers of fibroblasts on injured tissues and

the percentage of matured fibroblasts by microscopy were evaluated.

Results: The diameter of the hypertrophied neotendon in groups injected with TAC 1.25 mg was significantly decreased, but not in the others. There were no differences in numbers of fibroblast. As the amount of TAC increased in groups done with NWB and treadmill exercise, the percentages of matured fibroblasts significantly decreased.

Conclusion: The local TAC injection on acute tendon injuries had deleterious effects on healing process of tendon, and follow- up study about the types of weight bearing is needed. (J Korean Acad Rehab Med 2002; 26: 215-222)