A prospective study of 50 consecutive patients undergoing total hip arthroplasty, to establish whether there greater incidence of injury to the superior gluteal nerve associated with a particular approach (modified direct lateral approach). The patients will be assessed clinically and electrophysiologically before and after the operation through one year.

Neurological complications following total hip arthroplasty are uncommon, and their impact ranges from transient and trivial to permanent and devastating.

In general, the prevalence rate of neurologic injury after primary hip arthroplasty is estimated as 0.7-3.5% , whereas it may increase up to 7.6% after revision hip arthroplasty.

Direct or indirect injuries of nerves may occur during operative exposure and subsequent procedures. Injuries to the peripheral nerves can come about in several ways: laceration, ischemia, mechanical deformation from compression or distraction, or a combination of these causes.

Peripheral nerve injuries can involve either distant sites or nerves in the immediate vicinity of the hip joint. Sciatic nerve injury is the most common nerve to be injured following total hip arthroplasty. Femoral nerve injury is much less common and is associated with an anterior approach. Its diagnosis is often delayed, but the prognosis is generally better than with sciatic nerve injury.

The direct lateral approach to the hip was described by Hardinge and is based on the observation that the gluteus medius and vastus lateralis are in functional continuity through the thick tendinous periosteum covering the greater trochanter.

This approach involves splitting the gluteus medius and retracting a portion of the muscle anteriorly in continuity with part of the vastus lateralis. It avoids trochanteric osteotomy, but the neurovascular supply of gluteus medius and tensor fascia lata is vulnerable.

The superior gluteal nerve may be compromised during total hip arthroplasty done through the direct lateral approach of Hardinge which puts this nerve at risk when the gluteus medius is split and retracted anteriorly.

The function of the abductors may be impaired after operation if there is damage to the superior gluteal nerve or if the muscle flap is reattached inadequately to the trochanter.

Inclusion Criteria:

• Age: adults
• Sex: both males and female
• Operation: unilateral primary total hip replacement

Exclusion Criteria:

• Patient refusal
• Patients with pre-existing neuromuscular abnormality
• Preoperative immobility
• patient with bilateral total hip arthroplasty or hip pathology
• Revision hip arthroplasty

• Age: adults
• Sex: both males and female
• Operation: unilateral primary total hip replacement.