A PROSPECTIVE STUDY OF THE INCIDENCE OF CRANIAL EMBOLI IN HIP RESURFACING SURGERY. EFFECT OF CEMENTING AND VENTING OF PROXIMAL FEMUR

Abstract

Paradoxical cerebral embolism is seen in 50–60% of patients following hip and knee arthroplasty surgery. It is responsible for post-operative symptoms like confusion and cerebral ischemic episodes. Embolism is less common with the use of uncemented implants. No study has looked into incidence of cerebral emboli in hip resurfacing.

We undertook a prospective randomised study to look at the incidence of cranial emboli in hip resurfacing. Patients were randomized to receive either uncemented or cemented femoral component. An arm of the study included evaluation of the effects of femoral venting by randomising patients to ‘venting’ or ‘no venting’ of proximal femur intra-operatively. The operations were performed by a single surgeon using a uniform surgical technique. Transcranial Doppler device was used to quantify the occurrence and distribution of cerebral microemboli. Emboli counts were recorded continuously and were correlated any major procedural event.

Eight patients (5 vented, 3 unvented) underwent cemented resurfacing and 7 patients (4 vented, 3 unvented) had cementless resurfacing. There was no difference between the two groups for age, gender, weight, or ASA status. Peri-operatively both groups were similar for vital observations (heart rate, temperature, blood pressure), haemoglobin change, mini – mental score at day 1 and 2, and oxygen saturation at day 1 and 3.

The mean number of significant emboli in the cemented group was 8.1 and in the cementless group was 1.7 (significant, p=0.009). Venting did not influence rate of emboli however, venting was independently associated with significantly higher drainage (mean 604mls compared to 335mls without venting, p=0.018). There was no significant difference in post-operative haemoglobin or number of units transfused.

Cranial emboli occur commonly after hip resurfacing. Their incidence is significantly reduced by the use of uncemented femoral component, however venting of proximal femur doesnot appear to make any difference.