Ryan Christian Barnett Foster MD, Presenter: Nothing to Disclose

Theodore T. Miller MD, Abstract Co-Author: Nothing to Disclose

Darius Paris Melisaratos MD, Abstract Co-Author: Nothing to Disclose

Alissa Jo Burge MD, Abstract Co-Author: Nothing to Disclose

To determine the prevalence of sciatic nerve abnormalities on MRI in the setting of acute and chronic hamstring tears.

IRB approval was obtained and informed consent was waived. We searched our PACS system for MRI of the hamstrings performed between January 2011 and November 2013, and identified 168 patients with either acute or chronic tears. We then reviewed the images of these patients and identified a cohort in which the sciatic nerve looked abnormal, and correlated these findings with clinical notes from the office visits of these patients. MRI was performed using either a 1.5 or 3T magnet (GE Healthcare) with a cardiac or body coil. The protocol included coronal and axial inversion recovery and proton density sequences. Initial image interpretation was performed by any 1 of 11 fellowship-trained musculoskeletal (MSK) radiologists. An MSK fellow then reviewed all of the MRI examinations to confirm the findings. The hamstring tears were characterized as partial or complete and acute/subacute or chronic. Partial tears were further subclassified as low, moderate or high grade. The sciatic nerve was evaluated for abnormalities in signal and morphology, and for extrinsic compression. Neither the original MSK radiologist reading the case nor the MSK fellow knew which patients had clinical findings of sciatica in all but 2 cases.

47 of the 168 cases of hamstring tear (28%) had MRI features of sciatic nerve abnormality/compression. 36/47 (77%) had acute/subacute hamstring tears and 11/47 (23%) had chronic tears. 29/47 (62%) were full thickness tears and 18/47 (38%) were partial thickness. Clinically, only 10/47 had symptoms referable to the sciatic nerve (21%), 6 of which were associated with an acute/subacute hamstring tear and the other 4 with a chronic tear. 7 of the 10 clinically symptomatic cases were associated with full thickness tears and 3 were associated with low to moderate grade partial thickness tears.

The sciatic nerve may look abnormal in almost a third of hamstring injury cases, and yet is clinically symptomatic in only one-fifth of those abnormal appearances.

The sciatic nerve may look abnormal on MR imaging of hamstring tears, but is usually not clinically symptomatic.

Foster, R, Miller, T, Melisaratos, D, Burge, A, Prevalence of Sciatic Nerve Abnormalities in the Setting of Hamstring Injuries.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007469.html