R3 Dr. Jessica Telleria featured in Orthopaedics Today

Hip arthroscopy has emerged as a helpful diagnostic and therapeutic tool in the evaluation and treatment of a spectrum of pathological conditions in and around the hip. There is a definite learning curve to acquiring the expertise for this treatment modality, and an important consideration in this process is minimizing complications. Minimizing risk factors involves positioning and the maximum traction weight that can be used without placing the sciatic nerve at risk for dysfunction following hip arthroscopy.

I have asked Jessica J.M. Telleria, MD, to share insights she and her co-authors have gained from their study about this issue.

Douglas W. Jackson, MD
Chief Medical Editor

Douglas W. Jackson, MD: Realizing there is a learning curve for hip arthroscopy, what is the incidence of nerve injury (transient and permanent) that has been reported with use of the lateral or supine positions?

 

Jessica J.M. Telleria, MD: The complex geometry of the hip joint, constrained space, deep soft tissue envelope and specialized instrumentation present challenges to surgeons seeking to become adept in this technique. Anecdotally, it appears that it takes upwards of 50 procedures before a surgeon typically achieves proficiency, and hip arthroscopy is an integral part of many sports medicine fellowship programs. The “learning curve” for hip arthroscopy has previously been reported in the literature, and it is not surprising that there is a higher complication rate during a surgeon’s early experience.

The pudendal and sciatic nerves are the most commonly involved, and damage to the lateral femoral cutaneous nerve has been reported as well. While most are transient neuropraxias, resolving within a few weeks, permanent nerve damage has been reported with potentially devastating consequences to the patient.

Jessica J.M. Telleria

The reported rate of damage to the nerves about the hip ranges from 0% to 27%. Aggregating across 30 studies suggests that the overall reported incidence of nerve injury is 1.7% and comprises up to 52.8% of all complications during hip arthroscopy. While the authors are unaware of any study designed to directly compare differences in nerve injury between the lateral and supine positions, the ratio of pudendal to sciatic nerve injury reported in the literature is approximately 1:3 in the lateral position, and 2:1 in the supine position. Presumably damage to the pudendal nerve is most often due to direct compression from the perineal post, whereas sciatic nerve injury is related to the longitudinal pull on the limb while in skeletal traction.

Jackson: What methodology did you use to study the possible effects of the amount of traction and the duration of traction in influencing possible nerve injury?

Telleria: During 1998 to 2001, motor (MEP) and somatosensory (SSEP) evoked potentials were recorded in 76 patients undergoing routine hip arthroscopy by a single surgeon in the lateral position. Sixteen patients were excluded due to incomplete data. Changes in the posterior tibial and common peroneal nerves at the knee were evaluated to assess the effects of traction intensity and time on nerve dysfunction. Baseline values were recorded prior to the start of the procedure, and the contralateral nonoperative limb was continuously monitored to serve as a control. Nerve dysfunction was defined as a 50% reduction in amplitude of SSEPs or MEPs or a 10% increase in latency of the SSEPs, in accordance with standard neuromonitoring technique; nerve injury was defined as a clinically apparent neurologic deficit in sensory or motor function.

When the EMG indicated nerve dysfunction, the surgeon was immediately notified, followed by reevaluation of the vital signs, depth of anesthesia, patient position and technical troubleshooting. Traction time and weight were continuously monitored with a custom footplate tensiometer built into the traction device. Following data collection routine statistical analysis was performed by a dedicated statistician.

Jackson: What did you learn related to the “amount or duration” of traction using intraoperative nerve monitoring in the lateral position?

Telleria: Ultimately, this study did not support our initial hypothesis that traction time would be the greatest risk factor for nerve dysfunction. Instead, we found that the maximum traction weight is the greatest risk factor for traction-related sciatic nerve dysfunction during hip arthroscopy, with the odds of dysfunction increasing 4% with every 1-pound (0.45-kg) increase in weight. Total traction time was not a statistically significant risk factor. However, this study did not identify a discrete threshold of traction weight or traction time that put patients at a higher risk for nerve dysfunction. Additionally the supine position was not investigated and it is unknown if there are any differences in the risk profile when compared to the lateral approach.