Boundary Lubrication between the Tendon and the Pulley in the Finger*

The lubrication mechanism between the human flexor digitorum profundus tendon and the A2 pulley was investigated in vitro. The gliding resistance at the interface between the tendon and the pulley increased significantly after the tendon had been treated with a hyaluronidase solution. Alcian-blue staining of the surface of the tendon before and after it was treated with hyaluronidase suggested the presence of hyaluronate complex. Alcian blue-positive and hyaluronidase-sensitive materials, such as hyaluronate or proteoglycan, in the synovial membrane and the matrix of the tendon, may act as a boundary lubricant, facilitating the gliding and reducing the resistance between the tendon and the pulley.CLINICAL RELEVANCE: The use of intrasynovial tendon donor grafts, which appear to possess a boundary lubricant on their surface, may result in improved gliding of the tendon postoperatively, compared with more traditional grafts, such as the palmaris longus tendon, taken from extrasynovial sources.