Anatomy of a human knee. Credit: Rasi Bhadramani/iStock/Getty Images Plus

Analysis of knee joints from adult human cadavers provides new insights into the functions of a ligament that helps connect parts of the thigh and shin bones1.

The ligament, called the anterolateral ligament (ALL), has puzzled anatomists since its description by Paul Segond in 1879.

The ALL, together with another ligament, shares proximal attachments to the lateral epicondyle of the femur, the thigh bone. This observation contradicts earlier studies that describe the ALL as separate, says a research team at the All India Institute of Medical Sciences Patna in Bihar.

The scientists, led by Ashutosh Kumar, dissected the knee joints of 83 human cadavers donated by medical institutions. They found that the ligament was absent in approximately 20% of the joints. In the rest, it appeared to originate as an oblique band from the lateral collateral ligament (LCL) due to sharing the proximal fibres.

This study strongly indicates that the LCL–ALL complex is a composite ligamentous structure with shared proximal and divergent distal segments that resemble an inverted letter ‘Y’. It is dominant in the knees of Indians from the north and east of the country. This may change medical understanding of the biomechanical functions of the shared ligaments, injury mechanisms and surgical strategies.

The findings show that the ALL anatomy has ethnic variations. The researchers say that if this knowledge is not considered before ligament reconstruction surgery it may lead to post-operative complications.