Comparison of Internal Fixations for Distal Clavicular Fractures Based on Loading Tests and Finite Element Analyses

It is difficult to apply strong and stable internal fixation to a fracture of the distal end of the clavicle because it is unstable, the distal clavicle fragment is small, and the fractured region is near the acromioclavicular joint. In this study, to identify a superior internal fixation method for unstable distal clavicular fracture, we compared three types of internal fixation (tension band wiring, scorpion, and LCP clavicle hook plate). Firstly, loading tests were performed, in which fixations were evaluated using bending stiffness and torsional stiffness as indices, followed by finite element analysis to evaluate fixability using the stress and strain as indices. The bending and torsional stiffness were significantly higher in the artificial clavicles fixed with the two types of plate than in that fixed by tension band wiring (P<0.05). No marked stress concentration on the clavicle was noted in the scorpion because the arm plate did not interfere with the acromioclavicular joint, suggesting that favorable shoulder joint function can be achieved. The stability of fixation with the LCP clavicle hook plate and the scorpion was similar, and plate fixations were stronger than fixation by tension band wiring

Repeated freeze–thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons

Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze–thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze–thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze–thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze–thaw cycles. In patella tendons, the ultimate stress, Young’s modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze–thaw cycles. In conclusion, we identified that cells surviving after freeze–thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze–thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity

Spinal Epidural Hematoma after Thoracolumbar Posterior Fusion Surgery without Decompression for Thoracic Vertebral Fracture

We present a rare case of spinal epidural hematoma (SEH) after thoracolumbar posterior fusion without decompression surgery for a thoracic vertebral fracture. A 42-year-old man was hospitalized for a thoracic vertebral fracture caused by being sandwiched against his back on broken concrete block. Computed tomography revealed a T12 dislocation fracture of AO type B2, multiple bilateral rib fractures, and a right hemopneumothorax. Four days after the injury, in order to promote early orthostasis and to improve respiratory status, we performed thoracolumbar posterior fusion surgery without decompression; the patient had back pain but no neurological deficits. Three hours after surgery, he complained of acute pain and severe weakness of his bilateral lower extremities; with allodynia below the level of his umbilicus, postoperative SEH was diagnosed. We performed immediate revision surgery. After removal of the hematoma, his symptoms improved gradually, and he was discharged ambulatory one month after revision surgery. Through experience of this case, we should strongly consider the possibility of preexisting SEH before surgery, even in patients with no neurological deficits. We should also consider perioperative coagulopathy in patients with multiple trauma, as in this case

Surgical treatment for suicidal jumper's fracture (unstable sacral fracture) with thoracolumbar burst fracture: a report of three cases

Introduction: Suicidal jumper's fracture (unstable sacral fracture) is characterized not only by multiple fractures including thoracolumbar fractures, but also major chest and abdominal injuries. Early stabilization of these fractures and early ambulation are required for the treatment and management of chest and abdominal injuries. We present 3 cases of suicidal jumper's fracture with thoracolumbar burst fracture, treated with minimally invasive posterior fixation surgery, which is a combination of percutaneous pedicle screws (PPS) and the mini-open Galveston technique. Case reports: Case 1. A 50-year-old woman was injured by a fall from the 5th floor of a building as the result of a suicide attempt. Computed tomography revealed an H-shaped unstable sacral fracture and thoracolumbar fractures with major chest and abdominal injuries. For early stabilization of spinopelvic instability and early ambulation, we treated the patient with PPS and the mini-open Galveston technique. Her early postoperative emergence from bedrest contributed to the improvement of her general condition. One year after surgery at the final follow-up, she was able to walk with a T-cane without any motor, bladder, or bowel dysfunction (BBD) and achieved almost complete healing of the fractures. Cases 2 and 3. A 25-year-old woman (Case 2) and a 43-year-old woman were injured in falls. They had multiple injuries including unstable sacral fractures, and thoracolumbar fractures with major chest and abdominal injuries. We treated these patients with PPS and the mini-open Galveston technique. One year after surgery, they were able to walk with a T-cane and achieved almost complete healing of thoracolumbar fractures, but delayed healing of an unstable sacral fracture in Case 2, and remaining BBD in Case 3. Conclusion: PPS and the mini-open Galveston technique is a good approach to fixation because they are minimally invasive and provide moderately rigid fixation, especially in patients with multiple trauma whose general condition is poor