Cognitive dysfunction has been well documented following total knee replacement. Possible causes that have been postulated include cerebral emboli, post-operative complications and pain. The aim of this study is to compare cognitive decline in patients undergoing conventional total knee replacement (TKR), navigated total knee replacement and total hip replacement (THR).

We prospectively analysed 75 patients undergoing lower limb arthroplasty. Group 1 consisted of 25 conventional TKR’s, group 2 consisted of 25 navigated TKR’s and group 3 consisted of 25 THR’s. Cognitive function was assessed by 11 validated neuropsychological tests preoperatively, at 1 week post-operatively and at 6 months post-operatively. Testing was carried out by a clinical psychologist.

At day 6 post-operatively 55% of group 1, 83% of group 2 and 61% of group 3 patients had a significant cognitive decline. Group 2 had a significantly greater cognitive decline at day 6 compared to the other 2 groups. At 6 months significant cognitive decline was found in all 3 groups to 21%, 16% and 34% respectively. Group 2 demonstrated the greatest improvement in cognition from day 6 to 6 months post-operatively

Significant cognitive decline occurs in two-thirds (66%) of all patients undergoing lower limb arthroplasty at day 6 and remains significant in a quarter (25%) of patients at 6 months. There was no significant difference in cognitive decline in patients undergoing hip and knee arthroplasty.

Retrospective review of seventeen consecutive survivors of craniocervical dissociation (CCD). Thirteen patients had delay in diagnosis, with associated neurologic deterioration in five. Diagnosis of CCD was entertained after lateral C-spine x-ray in only two patients, and after screening C-spine CT in two others. At fifteen-month average follow-up, mean ASIA motor score improved from fifty preoperatively to seventy-nine postoperatively. One patient had temporary postoperative neurologic decline. There were no pseudarthroses. The diagnosis of CCD is often missed, with potentially severe neurologic consequences. Early diagnosis and stabilization are neuroprotective. A classification that identifies minimally displaced yet unstable injuries may improve diagnostic accuracy.

To identify the timing and method of diagnosis, diagnostic reliability of screening lateral radiographs, effect of delayed diagnosis, complications of treatment, and neurologic outcome of this life-threatening condition.

Diagnosis of craniocervical dissociation (CCD) was frequently delayed, increasing the risk of neurologic decline. Early diagnosis and stabilization protected against worsening spinal cord injury.

This study highlights the importance of disciplined evaluation of the lateral cervical spine radiograph of poly-traumatized patients. Head-injured patients with cranio-facial trauma and asymmetric high cervical spinal cord injuries should heighten clinicians’ suspicion of CCD.

CCD was identified or suspected on two of seventeen (12%) initial lateral cervical spine radiographs, and on screening CT scan in only two additional patients (12%), despite an abnormal dens-basion relationship in 16/17 (94%) patients. Of the thirteen patients with (two-day average) delay in diagnosis, 5/13 (38%) had profound neurologic deterioration. One patient worsened temporarily after fixation. There were no pseudarthroses at fifteen-month average follow-up. Mean ASIA motor score of fifty improved to seventy-nine, and the number of patients with useful motor function (ASIA D or E) increased from seven (41%) preoperatively to thirteen (76%) postoperatively.

Four patients with severe craniocervical instability had < 3 mm displacement. We therefore adopted a classification based on provocative traction testing of minimally displaced injuries.(Table).

Retrospective review of seventeen consecutive CCD survivors identified between 1994–2002 through institutional databases. Radiographic and clinical results were evaluated, emphasizing timing of diagnosis, effect of delayed diagnosis, clinical or radiographic warning signs, and response to treatment.

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