[Evaluation of the usefulness of suction drainage in the treatment of nonspecific bone infections monitored with C-reactive protein].

Introduction: Irrigation suction drainage (ISD) is an additional method in treatment of infected bones. Two liters of saline solution daily with an antibiotic is usually recommended for ISD, although some authors suggest that more fluid should be used without antibiotics, stressing the importance of the mechanical effect. Although the method is nowadays accepted as a routine procedure, the reported results of ISD are based on treatment of a limited number of patients and the only criteria for assessment have been clinical and bacteriologic findings. The aim of this prospective study is to show the importance of the mechanical effect of an increased fluid run and the optimal time necessary for cleaning of the osteomyelitic cavity by follow-up the C-reactive protein (CRP) levels as an indicator of an acute inflammation of the affected bone.

Methods: The prospective study was an open, centralized and randomized clinical investigation including over 105 patients with bone infection treated in the period 1986-1996. Two parameters with possible influence on the CRP levels were determined during investigation: 1. patients were divided in three groups depending on the duration of the irrigation suction drainage (3-6 days, 7-10 days and over 10 days) and 2. quantity of the liquid used for the irrigation suction drainage (two groups: 2000 ml per day and 6000 ml per day). Groups were similar in regard to age, sex, bacteriologic agents, duration of infection, localization and previous operations. C-reactive protein (CRP) is a nonspecific, but extremely sensitive indicator of an acute inflammatory disease. The erythrocyte sedimentation rate is not always a reliable indicator of infection. CRP as a protein of an acute phase appears and disappears quickly. Decreased values are a sign of a healing process used in this study for the estimation of the efficacy of the ISD. The CRP level was controlled semiquantitatively before operation and every third day over three weeks. If the values were below 6 mg/l, the results were classified as negative.

Results: There were not significant statistical differences in different groups as far as a preoperative average CRP values were concerned neither in the quantity of employed liquid nor in the duration of the ISD and interaction between these two groups. It was the same on the third postoperative day. The differences appear in the significantly lower average values of the CRP in patients of the second group (6000 ml/day) where the ISD lasted for seven or more days. During further follow up, (6th to 21st day) one can observe a significant statistical difference in average CRP values between the first (2000 ml/day) and second group (6000 ml/day) but there is not difference when the duration and sort of employed liquid is concerned. There is not significant difference in average statistical values of the CRP in blood for interaction of fluid quantity and time of ISD as well.

Discussion: The main disadvantage in the function of ISD is nonuniform rinsing of the osteomyelitic cavity. Prolonged ISD has no influence on the clinical result as well as on the average values of the CRP. Starting from the third postoperative day results indicate that the quantity of employed liquid has an important influence on the average level of the CRP, while the duration of ISD is not important. Prolonged ISD can not compensate for an inappropriate surgical intervention because it is only an additional method in the treatment of an osteomyelitic process.

Conclusion: By observing changes in CRP levels during treatment one can conclude that the efficacy of ISD is based mostly on mechanical rinsing and the removal of debris. This points to the importance of the quantity of fluid employed in irrigation suction drainage. Application of 6000 ml liquid per day without antibiotics during 5-7 days gives opportunity of better rinsing increasing the effect of ISD and reducing the incidence of complications.