Injury to the Posterior Horn of the Lateral Meniscus from a Misplaced Tibial Tunnel for Anterior Cruciate Ligament Reconstruction: A Case Report.

BACKGROUND Posterior meniscal root avulsions can cause meniscal extrusion, joint space narrowing, and progressive knee arthritis. Iatrogenic posterior meniscal root avulsions after malpositioning of the transtibial tunnels during anterior cruciate ligament (ACL) reconstruction can account for poor long-term outcomes seen in some patients following ACL reconstruction. Therefore, correct transtibial tunnel placement during ACL reconstruction is essential to avoid iatrogenic meniscal damage. CASE REPORT A 32-year-old man presented with 1 year of right knee pain and instability following a non-contact twisting injury sustained while playing soccer. An ACL tear with no meniscal involvement was diagnosed at an outside institution. A double-bundle reconstruction was performed at that time. Three months after surgery, a medial partial meniscectomy was performed after a medial meniscal tear and failure to reduce initial symptoms during the index procedure. Advanced imaging at our institution 6 months later demonstrated an iatrogenic lateral posterior meniscal root avulsions after malpositioning of the transtibial tunnels. Given the ACL graft integrity upon arthroscopic evaluation, the root tear was repaired using a 2-tunnel transtibial pull-out technique. Advanced imaging 1 year after surgery showed a well-maintained meniscal repair with no extrusion. CONCLUSIONS Accurate transtibial tunnel placement during ACL reconstructive surgery is vital to avoid meniscal root detachment and the associated complications resulting in poor patient outcomes from this iatrogenic injury. Clinicians treating patients with a history of cruciate ligament reconstruction presenting with postoperative pain and instability should consider this pathology in their differential diagnosis.