[Minimally Invasive Cancellous Bone Graft Harvesting in Trauma Indication - Clinical Part of the Study].

PURPOSE OF THE STUDY The clinical prospective study presents the results of minimally invasive harvesting of cancellous bone tissue in trauma indications. We focused on evaluating the clinical outcomes of this technique, particularly on the amount of cancellous bone harvested, the effectiveness of its use and complications. The pain in the bone graft harvest site is evaluated and compared with the pain after a standard harvest from the iliac crest. MATERIAL AND METHODS All the patients aged 18-90 years, in whom cancellous bone was harvested by minimally invasive technique using a bone cutter were included prospectively in the study. It was used to fill the defect in treating a fracture or in surgical treatment of non-union. The patients, in whom the grafts harvested in this manner were combined with another substitute, were not included in the study. Thus, 57 adult patients (40 men, 17 women) were included in the group in the period from March 2012 to March 2016. 37 patients, i.e. 65% of the total number of 57 patients, arrived for the evaluation of the clinical outcome. The minimally invasive graft harvesting was performed using the Aesculap® cutters. The graft was harvested either from the skeleton directly in the area of surgical wound or by a mini incision above the harvest site in the area under surgical drapes. The diameter of the cutter was selected based on the planned necessary number of grafts and with account taken of the harvest site. There were 6 harvest sites selected - proximal humerus, proximal ulna, iliac crest, greater trochanter of femur, distal femur and proximal tibia. The age and gender of patients, harvest site, type of the used cutter and the total number of harvested grafts were recorded in the study. The patients underwent a clinical follow-up at 6 weeks, 3 months, 6 months and 1 year postoperatively. The healing of the fracture or non-union was assessed on radiographs and in case of any doubt a CT scan was indicated. The pain at the graft harvest site was quantified with the use of the VAS score. A possible correlation between the age and the harvest site pain was explored by means of the Pearson s correlation coefficient. RESULTS In surgical management of fractures, 10.98 cm³ of bone marrow (σ 5.32) was harvested on average, in non-unions it was 10.85 cm³ (σ 5.52). With the above described technique, the mean healing time of lower extremity fractures was 26 weeks, in upper extremity it was 22 weeks. The non-unions of lower extremity and upper extremity healed after 28 weeks and 19 weeks, respectively. The average pain at the harvest site was 4.08 (σ 2.21, p ˂ 0.001). By calculating the Pearson's correlation coefficient it was confirmed that there is no correlation between the age and pain VAS score at the harvest site (r = -0.05). No early complications at the graft harvest site were observed in our group of patients. DISCUSSION On average, 10.98 cm³ of bone marrow was harvested in treated fractures, which in comparison to standard harvests from the iliac crest offers sufficient amount of tissue to treat complicated fractures and non-unions. Technically, the standard harvest site of cancellous bone tissue from the iliac crest is replaceable. The harvesting technique offers an interesting alternative also in terms of the duration of surgery and material. CONCLUSIONS Our study confirmed that by the minimally invasive technique of bone graft harvesting adequate amount of tissue to treat defect fractures and non-unions can be harvested. Spongioplasty using grafts harvested in this manner is effective, with a minimum percentage of non-unions. The advantage of this technique is the proximity of the harvest site and the operative field and low level of pain. The minimally invasive graft harvesting represents a technique with a low risk of postoperative and late complications. Key words: bone graft, autografts, minimally invasive surgery, ilium, pain.