Repetitive reduction lead to significant elevated IL-6 and decreased IL-10 levels in femoral osteotomies: A quantitative analysis of a robot-assisted reduction process in a rat model

Biomechanical and histological analyses of the fracture healing process after direct or prolonged reduction

Background

Reduction of femoral shaft fractures remains a challenging problem in orthopaedic surgery. Robot-assisted reduction might ease reduction and fracture treatment. However, the influence of different reduction pathways on patients’ physiology is not fully known yet. Therefore, the aim of this study was to examine the biomechanics and histology of fracture healing after direct and prolonged robot-assisted reduction in an in vivo rat model.

Methods

144 male CD^® rats were randomly assigned to 12 groups. Each animal received an external fixator and an osteotomy on the left femoral shaft. On the fourth postoperative day, the 1× reduction groups received a single reduction maneuver, whereas the 10× reduction groups received the same reduction pathway with ten repetitions. The control groups did not undergo any reduction maneuvers. Animals were killed after 1, 2, 3 and 4 weeks, respectively, and the composition of the fracture gap was analyzed by µCT and non-decalcified histology. Biomechanical properties were investigated by a three-point bending test, and the bone turnover markers PINP, bCTx, OPG, sRANKL, TRACP-5b, BALP, and OT/BGP were measured.

Results

One week after the reduction maneuver, µCT analysis showed a higher cortical bone volume in the 1× reduction group compared to the 10× reduction group. Biomechanically, the control group showed higher maximum force values measured by three-point bending test compared to both reduction groups. Furthermore, less collagen I formation was examined in the 10× reduction group compared to the control group after 1 week of fracture healing. PINP concentration was decreased in 10× reduction group after 1 week compared to control group. The same trend was seen after 3 weeks.

Conclusion

A single reduction maneuver has a beneficial effect in the early phase of the fracture healing process compared to repeated reduction maneuvers. In the later phase of fracture healing, no differences were found between the groups.

Minimally invasive treatment of displaced femoral shaft fractures with a teleoperated robot-assisted surgical system

BACKGROUND

Minimally invasive surgical operation of intramedullary (IM) nailing is a standard technique for treating diaphyseal fractures. However, in addition to its advantages, there are some drawbacks such as the frequent occurrence of malalignment, physical fatigue and high radiation exposure to medical staff. The use of robotic and navigation techniques is promising treatments for femoral fractures.

MATERIALS AND METHODS

This paper presents a novel robot-assisted manipulator for femoral shaft fracture reduction with indirect contact with the femur. An alternative clinical testing model was proposed for orthopedic surgeons to practice femoral fracture reduction. This model imitates the human musculoskeletal system in shape and functional performance. The rubber tube simulate muscles providing contraction forces, and the silicone simulates passive elasticity of muscles. Two-group experiments were performed for studying feasibility of the teleoperated manipulator.

RESULTS

The average operative time was about 7min. In the first group experiments, the femur axial, antero-posterior (AP) and lateral views mean errors were 2.2mm, 0.7mm and 1.1mm, respectively, and their maximums were 3.0mm, 0.9mm and 1.5mm; the mean errors of rotation were 0.8° around x-axis, 1.6° around y-axis, 2.0° around z-axis, and their maximums were 1.1°, 2.2°, 2.9°, respectively. For the second group experiments, the femur axial, AP and lateral views mean errors were 1.8mm, 0.4mm and 0.8mm, respectively, and their maximums were 2.2mm, 0.7mm and 1.1mm; the mean errors of rotation were 1.2° around x-axis, 1.6° around y-axis, 1.9° around z-axis, and their maximums were 2.4°, 1.8°, 2.7°, respectively. Reduction for AP view displacement is easier than lateral (p<0.05) because of the tube-shaped anatomy and the muscle contraction forces. Errors around x-axis are smaller than those around y-, and z- axes (p<0.05), i.e., electro-mechanical actuator is easier to control than pneumatic.

CONCLUSION

An experimental model for simulating human femoral characteristics was proposed. Experiments conducted on the artificial lower limb model demonstrated high reduction accuracy, safety, sufficient working space, and low radiation exposure of the proposed robot-assisted system. Thus, the minimally invasive teleoperated manipulator would have greater development prospect.

Comparison of algorithms for automated femur fracture reduction

PURPOSE

We designed an experiment to determine the comparative effectiveness of computer algorithms for performing automated long bone fracture reduction.

METHODS

Automated reduction of 10 3D fracture models was performed using two computer algorithms, random sample matching (RANSAM) and Z-buffering (Z-Buffer), and one of five options of post-processing: none; iterative closest point algorithm (ICP); ICP-X1; ICP-X2; and ICP-X3. We measured the final alignment between the two fragments for each algorithm and post-processing option.

RESULTS

The RANSAM algorithm combined with postprocessing algorithm ICP-X1 or ICP-X3 resulted in the most accurate fracture reduction in the translational plane. No discernible difference was observed in the rotational plane. Automated reduction had more accurate translational displacement than telemanipulated manual reductions.

CONCLUSION

This study supports the use of the RANSAM algorithm for automated fracture reduction procedures. The use of ICP algorithms provides further optimization of the initial reduction.

Persistent injury-associated anemia: the role of the bone marrow microenvironment

BACKGROUND

The regulation of erythropoiesis involves hematopoietic progenitor cells, bone marrow stroma, and the microenvironment. Following severe injury, a hypercatecholamine state develops that is associated with increased mobilization of hematopoietic progenitor cells to peripheral blood and decreased growth of bone marrow erythroid progenitor cells that manifests clinically as a persistent injury-associated anemia. Changes within the bone marrow microenvironment influence the development of erythroid progenitor cells. Therefore, we sought to determine the effects of lung contusion, hemorrhagic shock, and chronic stress on the hematopoietic cytokine response.

MATERIALS AND METHODS

Bone marrow was obtained from male Sprague-Dawley rats (n = 6/group) killed 7 d after lung contusion followed by hemorrhagic shock (LCHS) or LCHS followed by daily chronic restraint stress (LCHS/CS). End point polymerase chain reaction was performed for interleukin-1β, interleukin-10, stem cell factor, transforming growth factor-β, high-mobility group box-1 (HMGB-1), and B-cell lymphoma-extra large.

RESULTS

Seven days following LCHS and LCHS/CS, bone marrow expression of prohematopoietic cytokines (interleukin-1β, interleukin-10, stem cell factor, and transforming growth factor-β) was significantly decreased, and bone marrow expression of HMGB-1 was significantly increased. B-cell lymphoma-extra large bone marrow expression was not affected by LCHS or LCHS/CS (naïve: 44 ± 12, LCHS: 44 ± 12, LCHS/CS: 37 ± 1, all P > 0.05).

CONCLUSIONS

The bone marrow microenvironment was significantly altered following severe trauma in a rodent model. Prohematopoietic cytokines were downregulated, and the proinflammatory cytokine HMGB-1 had increased bone marrow expression. Modulation of the bone marrow microenvironment may represent a therapeutic strategy following severe trauma to alleviate persistent injury-associated anemia.