Comparative Analysis of the Morphologic Structure of Quadriceps and Patellar Tendon: A Descriptive Laboratory Study

Purpose: The difference in ultimate strength between the quadriceps and patellar tendon could be reflected by different morphologic features. Methods: Standardized samples of quadriceps and patellar tendons were harvested from 20 cadavers and were investigated via light and electron microscopy, immunohistochemistry, and morphometry. The thickness of collagen fibrils, fibril-interstitium ratio, density of blood vessels, density of fibroblasts, and distribution of collagen fibrils were analyzed. Results: In comparison with the patellar tendon, the quadriceps tendon showed a significantly higher fibril-interstitium ratio (P = .0004) and a higher fibroblast density (P = .0011). No differences regarding the thickness of collagen fibrils, density of blood vessels, and distribution of fibrils were found. Conclusions: The quadriceps tendon graft can provide approximately 20% more collagen than the patellar tendon graft with the same thickness. This fact can play an important role in the better ultimate strength of the quadriceps tendon. Clinical Relevance: The detailed anatomic description of the quadriceps tendon and patellar tendon explains the difference in their ultimate strength.