sciatic nerve palsy after THR

A 64-year-old male with ankylosing spondylitis and history of prostate cancer undergoes THR for osteoarthritis (Fig. 7–13). He has a history of atrial fibrillation and is on Coumadin. His immediate postoperative course is uneventful, and he is discharged from hospital on postoperative day 3. He resumed anticoagulation the evening after his surgery and has been on a Coumadin sliding scale. Ten days following surgery he returns with flank pain, dizziness, hypotension, and a foot drop that has been present for 24 hours. His INR is 4.3 and hematocrit is 20.

 

 

 

Figure 7–13

 

What is the LEAST likely cause of his symptoms?

1. Sciatic nerve injury during posterior approach

2. Retroperitoneal hematoma

3. Hip joint hematoma

4. Anemia

 

Discussion

The correct answer is (A). Given that the sciatic nerve palsy was not present immediately postoperatively but presented more than 1 week following surgery suggests that direct nerve injury at the time of surgery is unlikely. This patient has a supratherapeutic INR and likely has a hip hematoma that is causing a mass effect and irritation of the sciatic nerve. He has a concomitant retroperitoneal hematoma that can account for his flank pain.

What is the best course of action in this patient?

1. Reverse INR with FFP

2. Urgent evacuation of the hip hematoma

3. Observation of the retroperitoneal hematoma

4. All of the above

 

Discussion

The correct answer is (D). Sciatic nerve palsy as a result of an expanding hematoma is a rare complication following total joint replacement. It has been shown to occur in patients that have had thrombolysis and full dose therapeutic anticoagulation for

VTE following total hip arthroplasty. Although rare, it is important that this complication is recognized without delay so that emergent decompression can be performed to improve potential return of nerve function.

Six months following THR the patient’s nerve function has returned and he presents with lateral-sided hip pain. Figure 7–14 reveals current films. What is the diagnosis?

1. Dermatomyositis

2. Soft tissue sarcoma

3. Heterotopic ossification

4. Metastatic disease

 

 

 

Figure 7–14

 

Discussion

The correct answer is (C). This x-ray reveals nonbridging heterotopic ossification.

 

What conditions are NOT associated with the formation of heterotopic

ossification?

1. Ankylosing spondylitis

2. Diffuse idiopathic hyperostosis

3. Traumatic brain injury

4. Paget’s disease of bone

5. Chronic Coumadin use

 

Discussion

The correct answer is (E). Heterotopic ossification occurs rarely following total hip replacement. The pathophysiology involves an unknown trigger that causes mesenchymal cells to differentiate into osteoprogenitor cells. Patients at risk of developing HO following THR include those with hypertrophic osteoarthritis, diffuse idiopathic hypertrophy, ankylosing spondylitis, and prior HO formation of the hip following THR. This condition is more common in men than in women following THR. Other causes of HO that forms in the body include Paget’s disease and traumatic brain injury.

Given the patient has ankylosing spondylitis, what would have been an appropriate modality of prophylaxis for HO in this patient?

1. Indomethacin

2. External beam radiation

3. Bisphosphonates

4. Calcitonin

 

Discussion

The correct answer is (B). NSAIDs such as indomethacin and external beam radiation are the current prophylactic methods of preventing HO formation in patients that have high risk for developing HO following THR. However, this patient is chronically anticoagulated and therefore indomethacin would be contraindicated. The best modality in this patient would be external beam radiation. Ethylhydroxydiphosphonate is another agent that has been used and resulted in a delay of mineralization of osteoid, but clinical trials have shown that HO formation was not decreased, and the delay in mineralization did not significantly improve the range of motion of involved hips.

 

Objectives: Did you learn...?

 

The causes of sciatic nerve palsy after THR?

 

 

Diagnosis of hip joint hematoma? Treatment of hip joint hematoma?

 

The risk factors for heterotopic ossification after THR?