VOL. 97-B, No. 10, OCTOBER 2015 1345  HIP Neurolysis for the treatment of sciatic nerve palsy associated with total hip arthroplasty G. J. Regev, M. Drexler, R. Sever, T. Dwyer, M. Khashan, Z. Lidar, K. Salame, S. Rochkind From Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel  G. J. Regev, MD, Orthopaedic spine Surgeon,  M. Drexler, MD, Orthopaedic Surgeon,  M. Khashan, MD, Orthopaedic Surgeon,  Z. Lidar, MD, Head of the spine unit,  K. Salame, MD, Neuourgeon,  S. Rochkind, MD, Head of the peripheral nerve reconstruction unit, Tel-Aviv Sourasky Medical Center Tel Aviv University, Tel-Aviv, Israel.  R. Sever, MD, Orthopaedic Surgeon Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel.  T. Dwyer, MBBS, FRCSC, Orthopaedic Surgeon University of Toronto, Toronto, Canada. Correspondence should be sent to Dr M. Drexler; e-mail: mt.drexler@gmail.com ©2015 The British Editorial Society of Bone & Joint Surgery doi:10.1302/0301-620X.97B10. 35590 $2.00 Bone Joint J 2015;97-B:1345–9. Received 4 December 2014; Accepted after revision 5 June 2015 Sciatic nerve palsy following total hip arthroplasty (THA) is a relatively rare yet potentially devastating complication. The purpose of this case series was to report the results of patients with a sciatic nerve palsy who presented between 2000 and 2010, following primary and revision THA and were treated with neurolysis. A retrospective review was made of 12 patients (eight women and four men), with sciatic nerve palsy following THA. The mean age of the patients was 62.7 years (50 to 72; standard deviation 6.9). They underwent interfascicular neurolysis for sciatic nerve palsy, after failing a trial of non- operative treatment for a minimum of six months. Following surgery, a statistically and clinically significant improvement in motor function was seen in all patients. The mean peroneal nerve score function improved from 0.42 (0 to 3) to 3 (1 to 5) (p < 0.001). The mean tibial nerve motor function score improved from 1.75 (1 to 4) to 3.92 (3 to 5) (p = 0.02).The mean improvement in sensory function was a clinically negligible 1 out of 5 in all patients. In total, 11 patients reported improvement in their pain following surgery. We conclude that neurolysis of the sciatic nerve has a favourable prognosis in patients with a sciatic nerve palsy following THA. Our findings suggest that surgery should not be delayed for > 12 months following injury. Cite this article: Bone Joint J 2015;97-B:1345–9 Sciatic nerve palsy following total hip arthro- plasty (THA) is a relatively rare but potentially devastating complication. 1 The reported rate of injury to the sciatic nerve ranges from 0.08% to 3.7% following primary THA, and from 0% to 7.6% following revision THA. 1-6 This wide variation reflects the mixture of retrospective and prospective series, primary and revision THAs and varying indications for THA and revision, in the literature. 2,7 The possible mechanisms of injury to the nerve during primary THA include intra- operative direct compression from retrac- tors, 2,8 forceful dislocation of the femoral head, and stretching the nerve from leg-length- ening. 2,7 There are also reports of thermal injury from cement leakage, nerve injury sec- ondary to haematoma 3,9-11 and entrapment of the nerve by femoral cerclage wires. 2 Should motor or sensory deficit occur fol- lowing THA, urgent radiological investigation is required. The presence of severe neuropathic pain in the distribution of the sciatic nerve is a strong indicator of acute compression, which warrants early decompression. 10,11 However, in the absence of pain and in the presence of satisfactory radiographic appearances which suggest no mechanical compression of the nerve, the management of a sciatic nerve palsy usually involves observation, in the hope that function will return over time. However, the prognosis for neurological recovery is related to the degree of nerve damage, which is unknown in the immediate post-operative period. 8,12-14 Limited data are available regarding the effi- cacy of neurolysis in the treatment of sciatic nerve palsy following THA. The purpose of this case series is to report the results of this proce- dure in these patients. We hypothesised that this procedure would result in clinical improvement. Patients and Methods A retrospective review was made of all patients undergoing neurolysis for sciatic nerve palsy at our institution between 2000 and 2010. Inclu- sion criteria consisted of patients with sciatic nerve palsy secondary to a THA, who had failed a trial of non-operative treatment includ- ing observation and physiotherapy for a mini- mum of six months. A total of 12 patients (eight women, four men) with a mean age of 62.7 years (50 to 72, standard deviation (SD) 6.9) were identified. The mean duration of neurological symptoms before surgery was 28.0 months (7 to 120, SD 32.1). All patients were operated on by the senior author (SR).