Longitudinal Anterior Knee Laxity Related to Substantial Tibial Tunnel Enlargement After Anterior Cruciate Ligament Revision

Allograft and bioabsorbable screw use in anterior cruciate ligament (ACL) revision surgery is common. However, both allograft and bioabsorbable screws have been associated with immunologic reactions that lead to tunnel enlargement. Long-term studies examining tibial tunnel enlargement in this population are currently not available. We report a case of severe tibial and femoral tunnel enlargement 6.5 years after ACL revision surgery with anterior tibialis and semitendinosus allograft and bioabsorbable screw fixation. Longitudinal knee arthrometer data, knee examination with the patient under anesthesia, and arthroscopic inspection of the graft showed minimal effects of severe tunnel enlargement on anterior knee laxity and graft integrity. To our knowledge, this is the first case report of a longitudinal assessment of anterior knee laxity associated with severe tunnel enlargement. Surgeons should be aware of this condition and the clinical consequences that may accompany bone tunnel enlargement after ACL surgery.