Sciatic nerve injury associated with acetabular fracture is most likely to occur with dislocation of the hip joint. Letournal and Judet found traumatic sciatic nerve palsy in 75% of patients with posterior dislocation of the hip but in only 22% of those with central dislocation [19]. Fassler et al. reported that the traumatic sciatic nerve injury rate associated with a displaced acetabular fracture was approximately 20% [12]. Natasha et al. found that the incidence of nerve injury with acetabular fracture was 3.3%, that 75% of the nerve injuries were caused by trauma, and that 23 of 24 traumatic nerve injuries were associated with posterior dislocation of the hip [5]. Our findings are similar to those of previous studies. However, a meta-analysis published in 2022 found that the incidence of post-traumatic sciatic nerve injury was 5.1% irrespective of type of fracture [17].
Letournel and Judet noted that the highest incidence of sciatic nerve palsy occurred in association with a posterior fracture dislocation of the hip joint [19]. Helfet and Schmeling found that all patients with post-traumatic sciatic nerve injury had a fracture pattern that included the posterior wall or column. The impact of these injuries may result in blunt contusion to the sciatic nerve, laceration, or stretching of the nerve over the dislocated femoral head [20]. Reports on surgical indications for traumatic sciatic nerve injury are rare. Recovery of nerve injury is closely related to the integrity of the nerve in patients who are treated surgically. The likelihood of recovery with good nerve integrity is highest after surgical release, intermediate after suturing, and less likely but possible after graft repair [9]. The success of surgical decompression for nerve damage depends on several preoperative factors, including the severity of the initial injury, and the intraoperative findings. There is some controversy regarding the timing of surgery according to whether the initial injury was traumatic or iatrogenic and management of late complications [20]. Unlike the other two types of nerve injury, sciatic nerve injury in a patient with an acetabular fracture often involves the posterior wall, posterior column, or posterior dislocation of the hip joint. Therefore, posterior surgery (mostly using the Kocher-Langenbeck approach) is required to reconstruct the acetabulum and femoral head and allows nerve exploration during open reduction or internal fixation of an acetabular fracture. There have been some rare reports on the appearance of the sciatic nerve at the time of surgery. In a study by Fasslers et al., the sciatic nerve was in continuity in all 14 patients, definite contusions were seen in 9, the nerve appeared to be normal in 3, and 2 nerves were visualized but the appearance was not mentioned in the operation report [12]. In the present study, intraoperative observation confirmed that all patients had full continuity of the nerve and that 3 sides were compressed by bone fragments, 2 were stretched, 2 were contused, and 11 had no obvious abnormality.
Recovery after a peripheral nerve injury has long been a difficult issue in clinical orthopedics, and the poor prognosis has caused considerable inconvenience. Studies on the natural history of sciatic nerve injury have yielded conflicting results. Letournel and Judet reported that 60% of sciatic nerve injuries showed significant recovery [21]. However, Tile noted that 75% of post-traumatic injuries and all iatrogenic injuries recovered either completely or partially [22]. In a recent study by Natasha et al., 50% of patients experienced partial nerve recovery and 22% had complete recovery [23]. A meta-analysis published in 2022 reviewed 20 studies that included 651 patients with 44 post-traumatic sciatic nerve injuries and reported complete recovery from nerve injury in 64.7% of cases [17]. In the present study, recovery of neurological function was very good and significantly improved at follow-up when compared with preoperative function. There were no cases in which there was no recovery; 52.6% had complete recovery and 47.4% had partial recovery. Two patients still required an ankle–foot orthosis at the last follow-up.
There is limited literature on the time required for an injured sciatic nerve to recover, and the few reports that are available are based on very small sample sizes. The time needed for complete sciatic nerve recovery in the literature varies from 1.5 months to 24 months [24,25,26,27]. In the study by Natasha et al., the median recovery time was relatively longer for patients with partial nerve recovery than for those with complete nerve recovery (27 months vs. 17 months) [5]. In our study, the mean recovery time was 10 months (range, 3–23) and was significantly longer in patients with partial recovery (13.78 months; range, 6–2) than in those with complete recovery (6.70 months; range, 3–12).
Fassler et al. reported on 7 patients with sciatic nerve injury involving both the tibial and peroneal divisions who had complete or nearly complete motor and sensory recovery of the tibial component but did not have satisfactory recovery of the peroneal component [12]. They attributed this finding to the degree of injury in the peroneal nerve division. The better recovery of the tibial division may reflect various factors, including anatomical location, blood supply, and the surrounding soft tissue [28]. In our present study, both the tibial and common peroneal nerve divisions were significantly improved after surgery. However, the extent of recovery of the common peroneal nerve division was not better than that of the tibial nerve division. Although the mean LSUHSC peripheral nerve score was lower for the common peroneal division than for the tibial division, the difference was not statistically significant.
The mean time taken for partial nerve recovery was longer than that required for complete recovery. However, there was no relationship between degree of recovery after sciatic nerve injury and sex, age, cause of injury, type of fracture, hip dislocation, and femoral head injury. The degree of nerve recovery is related to whether there is any abnormality in the nerve at the time of exploration. Neurological recovery was very good in our study, possible because none of the patients had severe neurological damage and follow-up was adequate. In view of the clinical characteristics of acetabular fractures combined with sciatic nerve injury, the sciatic nerve should be explored routinely during surgical treatment and measures taken that are conducive to correct determination of the prognosis and neurological recovery according to the type and degree of injury.
This study had several limitations. First, it had a retrospective design. Therefore, the possibility that the incidence of sciatic nerve injury in association with acetabular fracture was underrecognized cannot be excluded. Second, the study was performed at a single center and included a small sample, which is to be expected considering the relative rarity of such cases. Multicenter studies in larger populations are needed. Third, the peripheral nerve scoring system used in this study does not fully represent sensory and motor function, especially the sensory aspects, which are highly subjective and complex and may have affected physicians’ judgment. Fourth, as this is a retrospective study, MRI (magnetic resonance imaging), ultrasonography and EMG (electromyography) have not been used in these cases, which could be included in future study. Finally, our follow-up protocol did not fully cover factors such as rehabilitation exercises and physiotherapy, which may impact on the results.