Post-operative cognitive dysfunction after knee arthroplasty: a diagnostic dilemma.

Post-operative cognitive dysfunction (POCD) is common in the elderly, and significantly impacts their recovery. We present an unusual diagnostic challenge where a 65-year-old male presented 4-week post-total knee arthroplasty with acute cognitive dysfunction lasting 19 days. Curiously, there were no findings uncovering a specific cause, but during investigation underlying predisposing factors such as depression, mild memory deficits and generalized brain volume loss were identified. The impression after psychogeriatric review was that of an organic brain syndrome with overlay of depression, with a complex presentation as POCD. After escalation of behavioural disturbance, he was commenced on anti-psychotic/depressant, with immediate response. We emphasize the importance of pre-operative evaluation of cognitive function and risk factors in all geriatric patients undergoing elective surgery, and the need for further characterization of POCD, as well as experimental research elucidating the underlying mechanisms to better identify and treat this important post-surgical phenomenon.