gms | German Medical Science

Objectives: Sciatic nerve injury is a rare but potentially extremely disabling complication of dislocated total hip arthroplasty (THA). Closed reduction is the initial management and it has a low complication rate.

We describe a case of sciatic nerve entrapment following closed reduction and stability testing of a hip prothesis. Because of the disabling pain following the suspected entrapment we performed a iatrogenic dislocation of the hip and did an open reduction with release of the nerve. In our institution early exploration and open reduction is performed in case of difficult closed reduction of THA. We now recommend to avoid stability testing of THA following a dislocation.

Methods: A 79 years old woman was referred to the emergency department because of pain in the left groin following an attempt to stand up from a sitting position. She had undergone a total hip replacement 13 years earlier and a partial revision 3 years ago. She suffered two dislocations of the THA 16 and 6 months ago. The indication of primary hip replacement was osteoarthritis and had been performed through a posterior approach. The same approach was used for the revision.

She presented with a shortened, flexed and internally rotated left leg. There was no neurological impairment on initial examination. Routine x-rays showed a postero-superior dislocated left THA. The hip was initially easily reduced under general anesthesia but after testing for stability the second reduction was harder to perform. Radiologic controls revealed a reduced prosthesis.

After the reduction the patient endured severe radiating posterior left lower limb pain with hyperflexion of the foot. Neurologic examination was difficult because of the high disconfort but a complete sciatic nerve deficiency seemed present. We performed a iatrogenic dislocation of the THA under anesthesia with alegation of the pain but no recovery from neurologic symptoms. An open reduction was performed secondarily with release of the sciatic nerve. The sciatic nerve was entraped around the neck of the prothesis.

Results and Conclusion: Sciatic nerve entrapment is a rare but described complication of closed reduction of THA dislocation. Signs of sciatic nerve entrapment include rest pain, complete or partial loss of motor and sensory function. Repeated attempts to reduce a THA dislocation come with a higher risk of complications. Presence of those symptoms after a closed reduction of THA dislocation suggests a sciatic nerve lesion. Early exploration of the nerve and open reduction is recommended if a sciatic nerve lesion is suspected.

Early closed reduction under general anesthesia is the treatment of choice of THA dislocation. Stability testing after closed reduction should be done with restriction as accurate measurement of the articular range-of-motion to the limit of stability has a low impact on the modalities of treatment. This case changed the recommendation in our institution about stability testing which should not be performed anymore.