[Minimally Invasive Cancellous Bone Graft Harvesting in Trauma Indication - Clinical Part of the Study]. / Miniinvazivní odber spongiózních stepu v traumatologické indikaci ­ klinická cást studie.

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.

[Minimally Invasive Cancellous Bone Graft Harvesting in Trauma Indication - Experimental Part of the Study]. / Miniinvazivní odber spongiózních stepu v traumatologické indikaci ­ experimentální cást studie.

PURPOSE OF THE STUDY Our experimental study presents a set of bone grafts harvested by a minimally invasive procedure from selected deceased donors. Our objective was to compare the concentration of red bone marrow in the cancellous bone harvested in this way from selected regions with the reference harvesting from the iliac crest. Thus, the potential of grafts to heal complicated fractures or non-unions is assessed. MATERIAL AND METHODS The Hospital Department of Pathology provided 10 cadaver preparations - 7 male and 3 female for the experiment. In the process of selection, the age limit was 18-50 years, the other exclusion criteria were severe injuries and burning to death as mechanisms affecting the condition of the skeletal system, bone diseases except for osteoporosis, and malignant diseases. From each preparation, a total of 12 samples of cancellous bone tissue were harvested from pre-defined 6 harvest sites bilaterally - proximal humerus, proximal ulna, greater trochanter of proximal femur, distal femur, proximal tibia and from the reference region of the iliac wing. The grafts were harvested using a 10 mm bone cutter. In total, 120 samples of cancellous bone of the determined diameter and uniform length of 30 mm were obtained. The obtained preparations were laboratory processed, fixed, decalcified and hematoxylin-eosin stained. The samples were assessed microscopically. The share of the bone tissue and cancellous bone was expressed as a percentage. Determined as a healing potential parameter was the concentration of red bone marrow and its ratio to the yellow bone marrow was stated. The hypothesis was tested using the ANOVA analysis of variance. RESULTS The highest concentration of red bone marrow was observed in cancellous grafts harvested from the iliac wing with 34.95%, followed by greater trochanter of proximal femur with 31.7%, distal femur with 26.9% and proximal humerus with 21.9%. Its concentration was negligible in proximal tibia with 2.55% and proximal ulna with 0.15%. By ANOVA statistical method the values of reference samples from the iliac wing and greater trochanter of the femur, distal femur and proximal humerus were compared. The differences are not statistically significant - P 0.60, 0.48 and 0.34 (p < 0.05). No significant differences were found in the concentration of red bone marrow. Statistically compared were also the values of reference samples from the iliac wing and proximal tibia, proximal ulna. This difference is statistically significant - P 0.0008 and 0.0002 (p <0.05). Thus, the difference in the concentration of red bone marrow is obvious. DISCUSSION The aforementioned results suggest that the greatest potential to heal will be achieved with the use of bone grafts from the iliac wing region, followed by greater trochanter of the femur, distal femur and proximal humerus. When testing the hypothesis by the ANOVA method, the detected differences between the selected harvest regions are not statistically significant. Therefore, the iliac wing grafts can be used in practice just as the material from greater trochanter of the femur, distal femur or proximal humerus, which is of equal quality. The other regions, proximal tibia and ulna, contain only minimum concentration of red bone marrow. CONCLUSIONS The experimental study comparing the concentration of red bone marrow in grafts harvested using a minimally invasive procedure from the region of greater trochanter, distal femur and proximal humerus concluded that these samples are comparable with the grafts from the iliac wing. The grafts harvested from proximal tibia and proximal ulna show only negligible concentration of red bone marrow and their use in clinical practice is disputable. The benefits of our experimental study for treatment shall be further evaluated in a clinical study. Key words: bone marrow, stem cells, bone healing/orthobiologics, new technology assessment, autograft harvesting.