Use of C reactive protein (CRP) and creatine kinase (CK) as predictors of early postoperative infection after minimally invasive transforaminal lumbar interbody fusion

Abstract

Introduction: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is increasingly used for the treatment of degenerative lumbar spine disease. Despite reduced soft‑tissue trauma, early postoperative infection remains a clinically relevant complication and may be difficult to recognize in the early phase. C‑reactive protein (CRP) and creatine kinase (CK) are routinely available laboratory markers reflecting inflammatory response and muscle injury, respectively. This study aimed to evaluate the association between postoperative CRP and CK kinetics and early postoperative infection following MIS‑TLIF.

Materials and methods: A retrospective study was conducted involving 60 patients who underwent percutaneous pedicle screw fixation and MIS‑TLIF between May and November 2022 at Thong Nhat Hospital, Ho Chi Minh City. Serum CRP and CK levels were measured preoperatively and on postoperative days (PODs) 3, 5, 7, 10, and 14. Postoperative infection was diagnosed based on Centers for Disease Control and Prevention criteria and included both surgical site and extra‑surgical site infections. Pain outcomes were evaluated using the Visual Analog Scale (VAS). Statistical comparisons were performed using paired t‑tests or Wilcoxon tests, and Mann–Whitney U tests for independent samples.

Results: Six patients (10%) developed postoperative infections, including two deep infections, one superficial infection, and three extra‑surgical site infections. In the overall cohort, CRP peaked on POD 3 and gradually declined, with 76% of patients returning to normal levels by POD 14. In infected patients, CRP showed a higher peak and a delayed decline, with a secondary elevation observed after POD 7. CRP levels differed significantly between infected and non‑infected groups on POD 10 and POD 14 (p < 0.05). In contrast, CK peaked on POD 3 and normalized in most patients by POD 10, with no significant differences between groups. VAS scores for back and leg pain improved significantly one week after surgery.

Conclusion: Serial CRP is a useful supportive marker associated with early postoperative infection when interpreted serially and in conjunction with clinical findings after MIS‑TLIF, particularly when CRP fails to decline or increases again after PODs 7–10. CK reflects postoperative muscle injury but does not provide additional diagnostic value for infection detection. CRP trends should be interpreted in conjunction with clinical findings to guide early diagnosis and management.