Morphometric Study of Anterior Cruciate Ligament and Histological Comparison with the Patellar and Hamstring Tendons and a Unique Case of Pes Anserinus Variant
Mohamed Atif Ahmed Said Ahmed
Anatomy Department, College of Medicine, Zagazig University, Egypt.
Abstract: Tendons are being used as grafts for the ACL reconstruction. Their microscopic structure has not been sufficiently studied and compared to the ACL. Aim: The present study focused on the anatomy of the anterior cruciate ligament as well as microscopic structure of patellar tendon, semitendinosus and gracilis tendons. It investigated also the crimping patterns and the tensile strength of these tendons and ligaments. Methods. length and width of ACL were measured by MRI software program for 15 patients. Twenty six lower limbs from formalin fixed cadavers were used in the present study. Measurement of tibial and femoral attachment of ACL were determined with the help of digital caliper. Samples from four different human tendons (ACL, Patellar tendon, semitendinosus and gracilis)were studied by light and scanning electron microscopy. The number, angle and length of wave crimps of the collagen fibers were analyzed by scanning electron microscopy and fibril/interstitum ratio and density of fibroblasts were also analyzed. Results. The length of the anteromedial and posterolateral bundles were 32±3.5mm and 23±3mm respectively with nearly the same width. The mean length and width of the femoral attachment of ACL were 17.3±1.7 mm and 9.3 ± 1.1 mm respectively, while, the mean length and width of the tibial attachment were 18.3 ± 2.9 mm and 12.1 ± 2.8 mm respectively. The crimp angle of the collagen fibers varied greatly between the four different tendons. Crimp top angle in ACL and PT (88 ± 8.6º and 130 ± 9.7 º respectively) was significantly lower than in semitendinosus and gracilis (148 ± 10 º and 159 ± 10.5 º respectively). Morphometric analysis confirmed that crimp number was highest in ACL and PT (6.2 ± 0.7and 5.4 ± 0.6 respectively). The crimp base length was more longer in gracilis (22 ± 4.1µm) and semitendinosus (20 ± 4.1 µm) than in ACL (15 ± 3.2 µm). The semitendinosus showed the highest number of fibroblasts, while the gracilis showed the highest fibril/interstitium ratio. No significant differences regarding the diameter of the collagen fibrils were found between all groups. The tensile strength was highest in PL (2905 ± 127 N) compared to other groups. A unique case of pes anserinus variant is reported that had implications for tendon harvesting and have an impact on the outcome of surgery. CONCLUSIONS: The present study will be useful for enhancing the knowledge of anatomy of ACL. Both semitendinous and gracilis tendons provide significantly more density of collagen fibrils and fibroblasts in comparison with patellar tendons. These findings provide a potential advantage of the hamstrings group on better remodelling and regeneration of the tissue.
[Mohamed Atif Ahmed Said Ahmed. Morphometric Study of Anterior Cruciate Ligament and Histological Comparison with the Patellar and Hamstring Tendons and a Unique Case of Pes Anserinus Variant. Life Sci J2013;10(1):1402-1411] (ISSN:1097-8135). http://www.lifesciencesite.com. 0
Keywords: anterior cruciate ligament – patellar tendon – semitendinosus – gracilis – pes anserinus variant.