• Thomas J Wilson, B Matthew Howe, Robert J Spinner, and Aaron J Krych.
• Department of Neurosurgery, Stanford University, Stanford, California.
• Neurosurgery. 2018 Nov 1; 83 (5): 931-939.

BackgroundRepair of proximal hamstring avulsions requires mobilization of the sciatic nerve away from the tendon stump, which can be achieved with varying difficulty depending on the degree of scar formation and adherence. Predicting when a scarred, adherent, difficult-to-mobilize nerve will be encountered has been difficult.ObjectiveTo identify clinical and/or radiological factors predictive of a difficult intraoperative dissection of the sciatic nerve during proximal hamstring repair.MethodsWe retrospectively reviewed the medical records and preoperative magnetic resonance imaging of consecutive patients undergoing proximal hamstring repair. We compared the groups with and without a difficult sciatic nerve dissection.ResultsThe total cohort consisted of 67 patients. Factors found to increase the likelihood of a difficult sciatic nerve dissection included complete conjoint tendon avulsion, higher maximal amount of tendon retraction, higher degree of imaging abnormality in the sciatic nerve, and higher degree of circumferential relationship of hematoma to the sciatic nerve. At a threshold of 23 for the Sciatic Nerve Dissection Score, the positive and negative predictive values were 53% and 88%, respectively. For the decision tree, the positive and negative predictive values were 75% and 87%, respectively.ConclusionWe have identified imaging factors associated with a scarred, adherent sciatic nerve that predict a difficult dissection during proximal hamstring repair. We have developed 2 novel methods-the Sciatic Nerve Dissection Score and a decision tree-that can be applied to predict the probability of a difficult sciatic nerve dissection at the time of surgical repair.

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