Sciatic nerve involvement is associated with longer return to sport in collegiate American football players with acute hamstring injuries

Objective To assess if the British Athletics Muscle Injury Classification (BAMIC) grade and sciatic nerve involvement on MRI at time of hamstring strain injury (HSI) were associated with the time to return-to-sport (RTS) in National Collegiate Athletic Association Division I American football players. Materials and methods Data were collected via a larger prospective cohort investigation of collegiate football players who sustained an HSI. MRIs at time of injury were assessed by a musculoskeletal radiologist using BAMIC. Sciatic nerve involvement was characterised by extent of adjacent oedema on MRI as no contact, partial (contacted by oedema) or complete (circumferentially surrounded by oedema). Spearman rank correlations, mixed-effects modelling and χ 2 analyses were used to determine associations between imaging characteristics, HSI severity and days missed before RTS. Results 96 unique HSI were included (100% male, mean age 20±1.58 years). Increasing BAMIC grade was associated with longer time to RTS (r=0.29, p=0.004). Sciatic nerve involvement was observed in 75/96 (78.1%) cases (35/96 (36.5%) partial, 40/96 (41.7%) complete), and no sciatic nerve involvement in 21/96 (21.9%) cases. There was a significant positive association between sciatic nerve involvement as BAMIC grade increased (p<0.001). While controlling for BAMIC grade, complete nerve involvement was associated with significantly longer time to RTS (33.7±20.0 days, p=0.01) compared with no involvement (21.5±14.8 days) and partial involvement (23.9±16.3 days, p=0.01). Partial sciatic nerve involvement (23.9±16.3 days, p=0.59) did not result in significantly longer RTS compared with no involvement. Conclusions Increasing radiologic severity, indicated by BAMIC grade and complete sciatic nerve involvement were associated with longer RTS following HSI. Sciatic nerve involvement on MRI should be considered in the assessment of acute HSI.