Quantification of surgical trauma: comparison of conventional and minimally invasive surgical techniques for pertrochanteric fracture surgery based on markers of inflammation (interleukins)

BACKGROUND: Fixation of pertrochanteric fracture is undoubtedly an additional trauma after the fracture itself. In elderly patients, it might have an important impact on the whole organism. In the literature we find various techniques to perform this type of surgery. Up to now, there are no parameters validated for quantification of the invasiveness of a surgical procedure; it is therefore still not demonstrated that any method is less invasive than any other. In an effort to find a way to quantify the invasiveness of a surgical procedure, inflammatory markers were collected in patients undergoing fixation of trochanteric fracture with gliding hip screw [dynamic hip screw (DHS)] using either a conventional (DHS conv) or minimally invasive (DHS MIO) technique. METHOD: Two groups of patients were investigated prospectively; 36 of them were treated with conventional DHS technique and 32 with minimally invasive technique. Mean age was 84.7 ± 7.20 and 82.78 ± 7.71 years, respectively. Fracture type was classified according to the AO classification. Interleukin (IL)-6, IL-10, IL-8, and tumor necrosis factor (TNF)-α were measured 1 h before and 1 h after surgery. Student’s t test, chi-square test, and multivariate logistic regression were used for statistical analysis. RESULTS: Preoperative levels of interleukins showed no significant differences between the two groups. In contrast, the postoperative blood level of IL-6 in patients operated with DHS conv technique (78.41 ± 67.04 pg/ml) was on average higher than in patients operated by DHS MIO technique (39.02 ± 37.36 pg/ml), the mean difference being 39.39 pg/ml [95 % confidence interval (CI) 12.65–66.13 pg/ml; p = 0.0045]. Multivariate logistic regression (backward method with limit of significance 0.05) confirmed that patients operated by conventional technique were significantly more likely to have increased IL-6 after surgery than those operated by MIO technique. IL-8 was measured in only 36 patients (20 for DHS conv, 16 for DHS MIO). No significant differences were found between the two groups; however, there was a drastic decrease postoperatively (p < 0.0001) regardless of the type of surgery performed. IL-10 and TNF-α were tested in all subjects, but did not show significant differences between the two groups. Average length of incision was significantly different (4.61 cm, 95 % CI 3.50–5.71 cm; p < 0.001) between the two groups, being 11.65 ± 2.64 cm for DHS conv and 7.05 ± 1.77 cm for DHS MIO. Similarly, average units of red blood cells (RBCs) transfused [performed for hemoglobin (Hb) <9 g/dl and/or hematocrit (HCT) <27 %] was higher (2.22 ± 0.99) in the DHS conv group compared with the DHS MIO group (1.09 ± 1.20), with average difference of 1.13 (95 % CI 0.59–1.66; p < 0.001). CONCLUSIONS: This attempt to quantify the invasiveness of internal fixation for trochanteric fracture comparing two techniques (DHS conv versus DHS MIO) based on inflammatory markers (IL-6) has given encouraging results. Measurement of systemic inflammatory response to local tissue damage caused by osteosynthesis using IL-6 as marker seems to confirm the lower invasiveness of MIO techniques. These results for trauma cases seem in line with those published for hip prosthesis. Ongoing further studies analyzing the effect of nailing will confirm or invalidate these preliminary results.