Iatrogenic injury to the posterolateral knee during anterior cruciate ligament reconstruction with anteromedial portal technique

BACKGROUND: Femoral tunnel reaming through anteromedial portal, also known as transportal technique, allows for anatomic femoral tunnel placement in restoring anterior cruciate ligament (ACL) kinematics. This procedure may cause iatrogenic injury to the posterolateral structures of the knee. PURPOSE: This study aims to assess the risk of posterolateral structure injury in ACL reconstruction using transportal technique. METHODS: ACL reconstruction using transportal technique was performed in 20 patients. Clinical and radiological examination was performed preoperatively and 1 month postoperatively. Clinical examination included any pain or paresthesia on posterolateral area of the knee, varus alignment of the knee, abnormal gait, and specific tests for posterolateral stability. Radiological evaluation was plain radiography and stress radiography for posterolateral stability, and magnetic resonance imaging (MRI) for assessing structural damage. RESULTS: Post-operative evaluation showed pain in posterolateral area in five patients, numbness on posterolateral knee in one patient, both pain and numbness in two patients and lateral gastrocnemius muscle injury on MRI in six patients. We did not find varus knee alignment and abnormal gait. Specific tests were negative in post-operative evaluation. Post-operative radiographic imaging did not show the sign of lateral widening. CONCLUSION: Femoral tunnel drilling using transportal technique in ACL reconstruction is safe even it might risk to damage lateral gastrocnemius muscle, according to clinical and MRI findings.