The bone-ligament junction: a comparison between biological and artificial ACL reconstruction

Area of Science:

• Orthopedic surgery
• Biomaterials science
• Histology

Background:

• The bone-ligament junction is crucial for load distribution and preventing stress at the interface.
• Anterior cruciate ligament (ACL) reconstruction aims to restore knee function using various graft types.

Purpose of the Study:

• To histologically evaluate neoligament insertion and bone healing after ACL reconstruction using different graft materials in a sheep model.
• To compare the integration of Dacron prosthesis, Leeds-Keio scaffold, patellar tendon with LAD augmentation, and patellar tendon alone.

Main Methods:

• ACL reconstruction in 16 sheep using double-isometric bone tunnels without immobilization.
• Histological analysis (H&E, Giemsa, Masson, Mallory stains) at 2, 3, 6, and 9 months post-surgery.
• Assessment of tissue integration, fibrocartilage formation, and nerve presence.

Main Results:

• Patellar tendon (PT) grafts demonstrated fibrocartilage formation and near-physiological insertion by 3-6 months.
• Dacron prosthesis and Leeds-Keio scaffold showed fibrous tissue encapsulation without bone ingrowth.
• Patellar tendon with LAD augmentation had fibrous tissue surrounding the augmentation, including within the LAD.
• Pacinian corpuscles (nerve endings) were only observed in PT grafts.

Conclusions:

• Patellar tendon grafts provide the most favorable histological integration after ACL reconstruction.
• Artificial ligaments and scaffolds struggle to achieve a physiological bone-ligament junction, remaining separated by fibrous tissue.
• The presence of nerve endings in PT grafts suggests better functional recovery potential.