Total hip replacement (THR) is a highly effective surgical procedure that relieves pain and restores function for people with severe hip arthritis. The surgery involves replacing the damaged hip joint with an artificial implant (prosthesis). Although THR is overwhelmingly successful, a recognized complication is irritation or injury to the sciatic nerve, leading to sciatica. Sciatica is pain that radiates along the nerve’s path, running from the lower back through the hip and down the leg. Sciatic nerve injury is a relatively rare complication of THR, occurring in approximately 0.6% to 3.7% of primary cases.
Mechanisms Linking Hip Replacement and Sciatica
Sciatic nerve issues arise because of the close anatomical relationship between the nerve and the hip joint. The sciatic nerve passes directly behind the hip socket and runs near the muscles and bone manipulated during surgery. Trauma can occur through compression, traction, or direct contact during the operation.
Nerve irritation commonly results from traction or stretching during surgical maneuvers, especially when the hip is dislocated and reduced. Excessive leg lengthening, often necessary to restore leg length, can stretch the sciatic nerve, particularly if the lengthening exceeds 2.7 to 4.4 cm. This traction injury can damage the nerve by pulling it tight over bony prominences or prosthetic components.
Component malpositioning can directly impinge upon the nerve’s pathway. For example, a poorly placed acetabular cup or an extended screw can press against the sciatic nerve, causing irritation or palsy. The surgical approach also influences risk; the posterior approach places the sciatic nerve at the highest risk of injury because it requires working directly near the nerve.
Post-operative factors can also lead to nerve compression and pain. A hematoma (a collection of blood near the surgical site) can swell and put significant pressure on the nerve. Similarly, scar tissue or fibrous material developing around the nerve during healing (neuritis) can tether and compress the nerve, causing delayed symptoms.
Distinguishing Sciatic Symptoms from General Post-Operative Pain
It is important to differentiate expected post-operative discomfort from specific sciatic nerve irritation symptoms. Typical post-operative pain is localized around the incision site and surrounding muscles, usually managed with prescription medication. This discomfort tends to improve steadily in the days and weeks following the procedure.
True sciatica presents with neuropathic pain distinct from muscular soreness. The hallmark is a burning, shooting, or electric-shock pain that radiates from the buttock down the back of the leg, following the nerve’s distribution. This pain may be accompanied by numbness, tingling, or muscle weakness in the foot or leg.
A severe sign of sciatic nerve damage is “foot drop,” the inability to lift the front part of the foot, which makes walking difficult. This symptom signals motor nerve involvement and warrants immediate medical attention. Physicians typically perform a physical examination, followed by imaging (X-rays or MRI) to check for hardware position or hematoma.
Pre-existing conditions, such as spinal stenosis or piriformis syndrome, can mimic or be exacerbated by the surgery, rather than the surgery causing a new injury. Nerve conduction studies or electromyography (EMG) may be used to confirm the location and severity of the nerve lesion, guiding the treatment plan.
Management Strategies for Post-Surgical Sciatic Nerve Issues
Initial management for most post-operative sciatic nerve irritation is conservative, as many injuries involve temporary nerve stretching that resolves spontaneously. Full nerve function returns in approximately two-thirds of cases, though recovery can take weeks to several months. Treatment begins with managing symptoms while waiting for the nerve to heal.
This conservative strategy includes anti-inflammatory medications and nerve pain-specific drugs, such as anticonvulsants, to alleviate discomfort. Physical therapy is a cornerstone of recovery, focusing on nerve gliding exercises and gentle range-of-motion activities to encourage healing and prevent scar tissue from tethering the nerve. Corticosteroid injections may also be used to reduce localized inflammation and pressure around the irritated nerve.
If imaging reveals a specific compressive cause, such as a large hematoma or a malpositioned prosthetic component, surgical revision may be necessary. Urgent surgical exploration and decompression may be considered for acute palsy combined with excessive limb lengthening or a quickly developing hematoma. While surgical intervention offers relief from pain and sensory symptoms, the restoration of motor function, such as reversing foot drop, is less predictable.