Urine desmosine as a marker of lung injury following total knee arthroplasty. A pilot study.

Lung injury following total knee arthroplasty (TKA) may occur secondary to embolization of bone debris, fat, and cement. Clinically relevant respiratory failure is rare and is therefore difficult to study. To facilitate future investigations on this subject, we evaluated the utility of the elastin breakdown product desmosine as a potential marker of lung injury during TKA surgery. The goals of this study were to answer (1) if desmosine levels would increase in response to the perioperative insults in patients undergoing TKA and (2) if this increase would differ among unilateral and bilateral TKA procedures. Twenty consecutive patients (ten unilateral and ten bilateral TKAs) were enrolled. Urine samples were collected before surgery and at 1 and 3 days postoperatively and analyzed for levels of desmosine using a validated radioimmunoassay. Baseline desmosine/creatinine ratios were higher in the unilateral as compared to the bilateral TKA group (p = 0.003). Tourniquet times, intraoperative estimated blood loss, and transfusion requirements among bilateral TKA patients were significantly higher than those of unilateral TKA recipients. Desmosine levels increased in both groups, but the rise was significant only in the bilateral group. We detected a significant increase in urine desmosine levels associated with bilateral but not unilateral TKA surgery. In the context of previous studies, our findings suggest that desmosine may be a marker of postoperative lung injury. Further research is warranted for validation and correlation of desmosine levels to clinical markers and various degrees of lung injury.