Effect of Number of Lymph Nodes Examined on Colon Cancer Staging and Survival in the De- Partment of Defense Automated Central Tumor Registry

NERVE TRANSFERS FOR TIBIALIS ANTERIOR MUSCLE PARALYSIS (FOOT DROP) A HUMAN CADAVER-BASED FEASIBILITY STUDY The following abstract was presented at William Beaumont Army Medical Center’s Research Day in May 2008. Purpose: This study explored the anatomic feasibility of using an interosseous nerve transfer to restore motor function to the tibialis anterior muscle following injury to the common peroneal nerve (resulting in foot drop). Potential nerve donors, including the nerve branches to the medial gastrocnemius, the lateral gastrocnemius, and to the soleus, were compared for the number of axons, the cross-sectional area, and the proximity of the nerve repair to the tibialis anterior muscle. Method: Eight fresh frozen cadaveric lower extremities were studied. Two fibular osteotomies to mobilize a fibular segment (referred to as a fibular window) facilitated the exposure and identification of the nerve branch to the tibialis anterior muscle and the development of an interosseous pathway for the nerve transfer. Each of the respective donor nerves were dissected out and then aligned with the nerve branch to the tibialis anterior to simulate a nerve repair. The distance from the nerve repair to the tibialis anterior muscle was measured for each respective donor nerve. Histological specimens were collected from each nerve for comparison of axonal counts and measurement of the cross sectional areas. Conclusion: All nerve transfers were accomplished using a direct interosseous route and a direct repair (one medial gastrocnemius transfer did require interpositional grafting). Compared to the nerve branch to the tibialis anterior, the medial and lateral gastrocnemius nerve branches had significantly smaller axonal counts (p=0.0050, p=0.0011 respectively) and cross-sectional areas (p=0.0011, p<0.0001 respectively). The nerve to the soleus, however, was not significantly different from the nerve branch to the tibialis anterior for axonal count (p=0.9356) or for cross-sectional area (p=0.9996). The nerve repair site for the nerve to the soleus was statistically closer than either the lateral (p=0.0122) or the medial (p=0.0010) gastrocnemius nerve branches. Of the three donor nerves considered, the nerve branch to the soleus was found to be the best donor nerve with respect to axonal count, cross-sectional area and proximity of nerve repair. A two incision surgical approach and interosseous routing, with the utility of a fibular window to facilitate the transfer, is proposed as a practical method for transferring donor nerves to the tibialis anterior muscle. CPT Uel Hansen, Orthopaedics Residency, William Beaumont Army Medical Center, El Paso, Texas.