Metabolic activity in disrupted human anterior cruciate ligament. Evaluation of procollagen mRNA expression in 29 patients

Abstract

Background. Although the anterior cruciate ligament heals poorly, recent reports demonstrated that this ligament has a rather active metabolic activity after disruption. The details of such activity are, however, not well known. Objective. To determine the localization of metabolic activity and its influential factors in the human disrupted anterior cruciate ligament. Patients and methods. The tibial remnants of completely disrupted anterior cruciate ligaments were obtained en bloc from 29 patients 2 to 94 days after injury. The expression of pro α1(I) and pro α1(III) collagen mRNA in the ligament substance was evaluated by non-radioactive in situ hybridization. The relationship was studied between the mRNA expression and the patient’s age, time after injury, presence of associated injury, or the condition of the ligament stump, respectively. Results. The expression of procollagen mRNA was observed in 72% of the cases, most often at the torn end but less frequently around the tibial insertion. The expression of type III procollagen mRNA was always observed within the area of type I expression. While the other factors had no significant relation with the expression, the extent of synovium coverage over the ligament stumps had a positive correlation with procollagen mRNA expression at the torn ends. Conclusion. The metabolic activity in a disrupted human anterior cruciate ligament shows considerable disparity among the cases in its localization. The pattern of ligament disruption could have a significant correlation with such activity at the torn ends.