It has been shown that a cognitive function (CF) loss can occur after hip or knee arthroplasty procedures, with an incidence of 40 to 70%. The pathogenesis remains unclear but studies suggest some form of brain emboli; although both trans-cranial doppler and trans-oesophageal doppler have both shown emboli per-operatively a correlation has never been shown with CF loss post-operatively. In contrast, in the cardiothoracic literature an embolic cause is widely accepted for detectable post-operative CF drop. The purpose of this study was to ascertain whether MRI could show evidence of embolic phenomena in patients undergoing hip or knee arthroplasty. Twenty-five patients presenting for hip or knee arthroplasty procedures were consented for this study. Brain MRI scans and MR angiograms were performed 1 week pre-operatively and within 1 week post-operatively using a Phillips 1.5Tesla MRI unit. All scans recorded were independently reviewed by 2 radiologists. A series of tests to examine several modes of cognitive function were carried out by a clinical psychologist pre-operatively, and at 1 week post-operatively. The CF tests showed a clinically significant drop following surgery in 64% of cases – this is in keeping with other recently published data. None of the post-operative scans or angiograms showed overt evidence of new lesions. Three Scans had equivocal tiny brainstem hypodensities on a single slice with no correlating abnormality on diffusion images to support the presence of new ischaemia. We conclude that either the aetiology of post-operative CF drop following arthroplasty is not embolic in nature, or that with current technology MRI brain scans even with angiograms are not sensitive enough to show the corresponding abnormality. With currently available equipment there appears to be no benefit from using MRI as a tool to evaluate post-operative CF loss in this group of patients.
Ankle arthrodesis is an accepted method of treatment for severe ankle pathology but no single method is universally successful. Compression is usually applied across the ankle joint and maintained with either internal or external fixation; both are associated with complications like infection, non-union, and pain.
We present our results and describe the surgical technique in managing 21 difficult cases using fine wire external frames in the salvage of severe ankle pathology. Nine cases were non-unions following internal fixation of distal tibial intra-articular fractures, seven were patients in whom two or three previous attempts at arthrodesis had been unsuccessful, and five patients had severe degenerative osteo-arthritis of the ankle joint.
A sound arthrodesis was achieved in 19 out of 21 cases giving a union rate of 90.4%. The median period of fixation was 21 weeks, followed by a mean period of cast immobilisation of eight weeks. All except three developed pin site inflammation. Using Mazur’s functional ankle score there were twelve good results, five fair, two poor and two failures.
A fusion rate of 90.4% was achieved using this method. We recommend it for the salvage of failed arthrodesis or severe fracture non-union, particularly in the presence of infection.
