OTA 1999 Posters

Reamed Tibial Nailing and Perfusion of Intra-Articular Structures of the Knee

James Lever, MD; Sergei Aksenov, MD; Emil H. Schemitsch, MD, FRCS(C), St. Michael's Hospital, Toronto, Ontario, CANADA

Purpose: There is a relatively high incidence of knee pain associated with tibial nailing. Recent studies have examined the intraarticular risks of intramedullary nailing. Tibial nailing may place the medial meniscus at risk and may violate the footprint of the anterior cruciate ligament. The purpose of this investigation was to study the effects of reamed tibial nailing on perfusion of intra-articular structures of the knee.

Materials and Methods: Midshaft tibial osteotomies to create a 2.5-cm segment of devascularized diaphyseal bone were performed in 10 skeletally mature canines. The fractures were stabilized using 6.5-mm x 180-mm intramedullary nails with interlocking. A medial parapatellar approach to the knee joint was performed to allow access to the intra-articular structures and provide exposure of the insertion point for the tibial nail. All tibial canals were reamed from six to nine millimeters in diameter, in increments of one millimeter. Soft tissue blood flow was assessed using laser doppler flowmetry (LDF). Perfusion measurements were made at 4 locations (anterior cruciate ligament, posterior cruciate ligament, medial meniscus and lateral meniscus) and at 5 time intervals (pre-osteotomy, post-osteotomy, post-nailing, post-locking, 11 weeks post-nailing). LDF values were normalized to the pre-osteotomy levels to eliminate inter-animal variability.

Results: Following intramedullary nailing with interlocking, there was a significant decrease in overall mean anterior cruciate ligament perfusion to an average of 86% of pre-fracture values (p=0.04). At 11 weeks post-nailing, anterior cruciate ligament perfusion remained at 85% of pre-fracture values (p=0.03) and showed no recovery from values immediately post-nailing. Following intramedullary nailing with interlocking, there was a significant decrease in overall mean posterior cruciate ligament perfusion to an average of 79% of pre-fracture values (p=0.03). At 11 weeks post-nailing, posterior cruciate ligament perfusion recovered to normal. Following intramedullary nailing with interlocking, there was a significant decrease in overall mean medial meniscus perfusion to an average of 85% of pre-fracture values (p=0.02). At 11 weeks post-nailing, medial meniscus perfusion recovered to normal. Following intramedullary nailing with interlocking, there was no significant effect on overall mean lateral meniscus perfusion.

Discussion and Conclusions: Our investigation demonstrated a progressive decline in perfusion of the anterior and posterior cruciate ligaments and the medial meniscus following introduction of a reamed, locked intramedullary nail for tibial fracture stabilization, via a medial parapatellar approach. Previous studies have shown that tibial nailing places the medial meniscus at risk and may violate the anterior cruciate ligament footprint. In our investigation, there was a greater risk to those structures that were medial and close to the entry portal, resulting in a non-transient decrease in anterior cruciate ligament perfusion and a transient decrease in medial meniscus perfusion. There was a reduced risk to those structures that were away from the entry portal, resulting in a transient decrease in posterior cruciate ligament perfusion and no effect on lateral meniscus perfusion. These effects should be understood in order to reduce the impact of reamed intramedullary nailing on intra-articular structures of the knee.