Post-operative C-reactive protein and white blood cells changes pattern following spinal deformity surgery and its clinical correlation

Post-operative infection is a feared complication especially in spine deformity surgery; hence, early detection is of paramount importance. Post-operative infections could manifest itself with different symptoms including local pain, swelling, wound inflammation, and general symptoms as fever. Nevertheless, all these symptoms cannot accurately diagnose infection [1].

Usually, the catastrophic picture of acute infection, e.g., wound dehiscence, exposed implants, and septicemia, does not appear rapidly. On the contrary, there is a gradual increase in severity of symptoms and signs [6].

CRP and WBC are the most common laboratory parameters used in detecting and following up infections as they are more sensitive compared to different radiological modalities. Inflammatory process increases the production of a group of proteins known as acute-phase reactants such as CRP [2]. The CRP level is known to double in approximately 8 h in response to different stimuli [7].

To be able to use a specific laboratory marker in detecting early post-operative infection, there is a need to know its normal pattern of change in the physiological post-operative period as the operative stress normally raises them above normal. Moreover, that would clear out the confusion due to misinterpretation of normal changes in marker levels during the post-operative period as those changes are related to an unspecific tissue reaction [8]. Kang and coauthors [9] stated that CRP reaches its peak around the 3rd post-operative day and returns to normal level by the 9th day. Also, based on their findings, the WBCs reached their peak around the 2nd day and returned to normal levels around the 4th day in both primary and revision spinal fusion surgeries [9].

Another study by Khan and colleagues [10] reported that CRP levels reach their maximum in the 2nd post-operative day (POD) which is followed by a rapid decline around the 7th post-operative day. Additionally, Choi and coauthors [11] reported on a series of 20 spinal fusion surgeries that WBCs count elevated rapidly on POD 1 and the normalized after POD 3. In their study, Kraft and coworkers [12] outlined that if the expected decline in CPR levels at the POD 7 is interrupted, then a possible infection should be anticipated as they reported that WBCs levels were normalized around POD 2 or 3 in both spinal fusion and simple discectomy surgeries. On the other hand, CRP levels returned to normal around POD 14 in both surgeries.

This study aimed to determine the changing pattern of post-operative CRP and WBC counts in the spinal deformity surgeries and investigate the effects of different variables such as blood transfusions, age, fusion levels, and operative time on the CRP and WBC counts.

Our results showed that by POD 3, 86% of cases showed normal WBCs count while by POD 7, 94% of cases showed normal WBCs count (Fig. 1). All cases showed high CRP by the 2nd day which decreased significantly but not reaching normal levels even by the 7th day post-operative.

WBCs count in POD 2 showed significant positive correlation with fusion levels (Fig. 2), and there was also a positive correlation between operative time and WBCs at POD 7. However, there was no correlation between WBCs and blood transfusion or age. Moreover, there was no significant correlation between CRP and the above-mentioned variables.

Deirmengian and coauthors studied the rise of WBC count after arthroplasty in the lower limb, and they found similar findings [13]. Their data showed that the post-operative leukocytosis was present as a normal physiological response to surgery until the POD 4.

On the other hand, Gerven and coworkers stated that in cases of proven spondylodiscitis, the changes in the CRP level are more predictable than the changes in the serial WBC count [14] but their main focus was evaluating the treatment modality rather than diagnosing the infection itself.

Additionally, several studies have documented the sensitivity of serial CRP levels in monitoring SSI following fracture fixation [4, 15, 16] as well as in lumbar spine surgery [17] but none of them have correlated the CRP and WBCs count in patients without infections.

Apart from the different limitations of any retrospective study, the main limitations were the small sample group, heterogenous patients underlying pathology, and wide age range. However, we believe that it serves as an additional piece of information that could help the early detection of a catastrophic complication as SSI in spinal deformity surgery.

This post was last modified on December 15, 2024 4:01 am