34th Annual Scientific Meeting proceedings

Objectives:

High failure rates of synthetic ligaments and concerns about debris-related problems have limited their use in intra-articular cranial cruciate ligament (CrCL) replacement. Incorrect positioning, poor tissue integration and low wear resistance are recognized causes of failure. The high wear resistance of ultra-high molecular weight polyethylene (UHMW-PE) ligaments has recently led to their use in CrCL replacement. To our knowledge, there are no data on their long-term tissue integration and the potential impact of wear debris in a clinical setting. This case report addresses these issues in a dog with a ruptured ultra-UHMW PE ligament that was explanted.

Methods:

A 7-year-old, 18 kg, neutered male Staffordshire Bull Terrier with right pelvic limb lameness and a positive cranial drawer test underwent surgical revision 12 months after CrCL replacement with a UHMW-PE ligament. Ligament placement, synovial, chondral, and osseous abnormalities, and tissue ingrowth within the SL were evaluated by computed tomography (CT), needle arthroscopy, and histology.

Results:

Nonanatomic ligament placement and tibial tunnel widening were documented. A complete mid-substance rupture with heterogeneous tissue ingrowth, femoral chondral lesions, and moderate synovitis with debris and giant cells were observed. Gentle traction allowed easy removal of the SL, suggesting a weak ligament-bone interface after removal of the interference screws.

Conclusions:

Although their actual contribution to the observed lesions remains an open question in the present case, the presence of wear debris and poor bone integration of the ligament, which may lead to fixation failure, are concerns to be addressed in further studies.