Thomas A. Schildhauer

Open reduction and augmentation of internal fixation with an injectable skeletal Cement for the treatment of complex calcaneal fractures

OBJECTIVES To describe the surgical handling, potential complications, and remodeling of an injectable, osteoconductive calcium phosphate cement (Norian SRS) for joint depression-type calcaneal fractures in humans, and to illustrate the clinical efficacy of this cement with special reference to early postoperative full weight bearing. DESIGN Prospective cohort study. SETTING Level I trauma centers in Bochum and Leipzig, Germany. INTERVENTION Thirty-six joint depression type calcaneal fractures in thirty-two patients were augmented with the calcium phosphate cement after standard open reduction with internal fixation. Postoperative full weight bearing was allowed progressively earlier, and as the study progressed, the last patients were bearing full weight as early as three weeks postoperatively. Biopsies for histologic analysis were performed at time of hardware removal after one year (seven biopsies) or in case of infection at time of debridement (five biopsies). MAIN OUTCOME MEASURES Clinical outcome was evaluated according to a calcaneal scoring system. Data were compared and statistically analyzed between patients with postoperative full weight bearing after eight to twelve weeks and three to six weeks, respectively. Histologic findings are described. RESULTS Cement injection averaged ten cubic centimeters and could easily be performed under fluoroscopic control. Progressively earlier full weight-bearing was achieved without loss of reduction. There was no statistical difference in clinical outcome scores in patients with full weight bearing before or after six weeks postoperatively. The infection rate was 11 percent, possibly related to the skin incisions. The biopsies from clinically satisfactory cases showed nearly complete bone apposition, areas of vascular penetration, and reversal lines illustrating progressive cycles of resorption and new bone formation. Biopsy specimens from infected cases showed bone and cement surrounded by either fibrous tissue or acute inflammation without extensive bone apposition. CONCLUSIONS Calcium phosphate cement augmentation of standard open reduction with internal fixation in joint-depression type calcaneal fractures allows postoperative full weight bearing as early as three weeks postoperatively. The injectable bone cement can easily be handled surgically under fluoroscopic control and has proved to be remodelable.

Triangular osteosynthesis and iliosacral screw fixation for unstable sacral fractures: a cadaveric and biomechanical evaluation under cyclic loads.

Objective To conduct a biomechanical comparison of a new triangular osteosynthesis and the standard iliosacral screw osteosynthesis for unstable transforaminal sacral fractures in the immediate postoperative situation as well as in the early postoperative weight-bearing period. Design Twelve preserved human cadaveric lumbopelvic specimens were cyclicly tested in a single-limb-stance model. A transforaminal sacral fracture combined with ipsilateral superior and inferior pubic rami fractures were created and stabilized. Loads simulating muscle forces and body weight were applied. Fracture site displacement in three dimensions was evaluated using an electromagnetic motion sensor system. Intervention Specimens were randomly assigned to either an iliosacral and superior pubic ramus screw fixation or to a triangular osteosynthesis consisting of lumbopelvic stabilization (between L5 pedicle and posterior ilium) combined with iliosacral and superior pubic ramus screw fixation. Main Outcome Measures Peak loaded displacement at the fracture site was measured for assessment of initial stability. Macroscopic fracture behavior through 10,000 cycles of loading, simulating the early postoperative weight-bearing period, was classified into type 1 with minimal motion at the fracture site, type 2 with complete displacement of the inferior pubic ramus, or type 3 with catastrophic failure. Results The triangular osteosynthesis had a statistically significantly smaller displacement under initial peak loads (mean ± standard deviation [SD], 0.163 ± 0.073 cm) and therefore greater initial stability than specimens with the standard iliosacral screw fixation (mean ± SD, 0.611 ± 0.453 cm) (p = 0.0104), independent of specimen age or sex. All specimens with the triangular osteosynthesis demonstrated type 1 fracture behavior, whereas iliosacral screw fixation resulted in one type 1, two type 2, and three type 3 fracture behaviors before or at 10,000 cycles of loading. Conclusion Triangular osteosynthesis for unstable transforaminal sacral fractures provides significantly greater stability than iliosacral screw fixation under in vitro cyclic loading conditions. In vitro cyclic loading, as a limited simulation of early stages of patient mobilization in the postoperative period, allows for a time-dependent evaluation of any fracture fixation system.

Complications Associated With Surgical Stabilization of High-Grade Sacral Fracture Dislocations With Spino-Pelvic Instability

Study Design. Retrospective evaluation of 19 consecutive patients with sacral fracture dislocations and cauda equina syndrome. Objective. To review the safety and patient impact of early surgical decompression, and rigid segmental stabilization in patients with high-grade sacral fracture dislocations. Summary of Background Data. The ideal treatment for patients presenting with fracture dislocations of the sacrum resulting from high-energy mechanisms remains unknown. Previous studies consisted of multicenter case reviews that showed satisfactory outcomes with either nonoperative or a variety of surgical methods. However, over the last 20 years, no consistent treatment algorithm for these severe injuries has emerged. The advent of rigid, low-profile segmental fixation of the lumbar spine to the pelvic ring has offered a solution to many of the surgical challenges. This study evaluates the rate of complications of this method. It is intended to serve as a foundation for further evaluation and development of this treatment strategy, and as a basis for future comparison studies. Methods. Patients were treated with a formally established algorithm, including resuscitation, and clinical assessment with detailed neurologic assessment and radiographic workup with pelvic computerized tomography and reformatted views. Electrophysiologic testing was conducted to confirm the presence of sacral plexus injuries in patients who were unable to be examined. Patients received neural element decompression and open reduction with segmental internal fixation through a midline posterior approach by connecting lower lumbar pedicle screws to long iliac screws when the patient’s general medical condition allowed for surgical intervention. A formal sacroiliac arthrodesis was not performed. For the purposes of this study, patients were assessed specifically for the following adverse events: (1) infection, (2) wound healing, (3) neurologic deterioration following surgical treatment, (4) postoperative loss of sacral fracture reduction, (5) instrumentation failure, (6) axial lumbopelvic pain requiring further treatment, and (7) unplanned secondary surgery. Results. There were 19 patients with an average age of 32 years treated according to this algorithm. Fracture reduction was successfully maintained in all patients. During the index surgical intervention, 14/19 patients (74%) had had either a traumatic dural tear or nerve root avulsion. Major complications involved fracture of the connecting rods in 6/19 patients (31%) and wound healing disturbances in 5/19 (26%). There were no lasting complications such as chronic osteomyelitis noted. In patients followed over a 1-year period, the visual analog score, referable to the sacral injury, averaged 5.5 on a scale of 0–10. Conclusions. Rigid segmental lumbopelvic stabilization allowed for reliable fracture reduction of the lumbosacral spine and posterior pelvic ring, permitting early mobilization without external immobilizaton and neurologic improvement in a large number of patients. Complications were primarily related to infection, wound healing, and asymptomatic rod breakage, and were without long-term sequelae.

Intramedullary nailing of proximal quarter tibial fractures.

Objective: To report the results of intramedullary nailing of proximal quarter tibial fractures with special emphasis on techniques of reduction. Design: Retrospective clinical study. Setting: Level 1 trauma center. Patients: During a 36-month period, 456 patients with fractures of the tibial shaft (OTA type 42) or proximal tibial metaphysis (OTA type 41A2, 41A3, and 41C2) were treated operatively at a level 1 trauma center. Thirty-five patients with 37 fractures were treated primarily with intramedullary nailing of their proximal quarter tibial fractures and formed the study group. Thirteen fractures (35.1%) were open and 22 fractures (59.5%) had segmental comminution. Three fractures had proximal intraarticular extensions. Main Outcome Measurements: Alignment and reduction postoperatively and at healing. An angular malreduction was defined as greater than 5 degrees in any plane. Results: Fractures extended proximally to an average of 17% of the tibial length (range, 4% to 25%). The average distance from the proximal articular surface to the fracture was 67.8 mm (range, 17 mm to 102 mm, not corrected for distance magnification, included for preoperative planning purposes only). Postoperative angulation was satisfactory (average coronal and sagittal plane deformity of less than 1 degree) as was the final angulation. Acceptable alignment was obtained in 34 of 37 fractures (91.9%). Two patients had 5-degree coronal plane deformities (one varus and one valgus), and 1 patient had a 7-degree varus deformity. Two patients with open fractures with associated bone loss underwent a planned, staged iliac crest autograft procedure postoperatively. Four patients were lost to follow-up. In the remaining 31 patients with 33 fractures, the proximal tibial fractures united without additional procedures. No patient had any change in alignment at final radiographic evaluation. Secondary procedures to obtain union at the distal fracture in segmental injuries included dynamizations (n = 3) and exchange nailing (n = 1). Complications included deep infections in 2 patients that were successfully treated. Conclusions: Multiple techniques were required to obtain and maintain reduction prior to nailing and included attention to the proper starting point, the use of unicortical plates, and the use of a femoral distractor applied to the tibia. Simple articular fractures and extensions were not a contraindication to intramedullary fixation. The proximal tibial fracture healed despite open manipulations. Short plate fixations to maintain this difficult reduction, either temporary or permanent, were effective.

Cell type-specific responses of peripheral blood mononuclear cells to silver nanoparticles

Silver nanoparticles (Ag-NP) are increasingly used in biomedical applications because of their remarkable antimicrobial activity. In biomedicine, Ag-NP are coated onto or embedded in wound dressings, surgical instruments and bone substitute biomaterials, such as silver-containing calcium phosphate cements. Free Ag-NP and silver ions are released from these coatings or after the degradation of a biomaterial, and may come into close contact with blood cells. Despite the widespread use of Ag-NP as an antimicrobial agent, there is a serious lack of information on the biological effects of Ag-NP on human blood cells. In this study, the uptake of Ag-NP by peripheral monocytes and lymphocytes (T-cells) was analyzed, and the influence of nanosilver on cell biological functions (proliferation, the expression of adhesion molecules, cytokine release and the generation of reactive oxygen species) was studied. After cell culture in the presence of monodispersed Ag-NP (5-30μgml(-1) silver concentration), agglomerates of nanoparticles were detected within monocytes (CD14+) but not in T-cells (CD3+) by light microscopy, flow cytometry and combined focused ion beam/scanning electron microscopy. The uptake rate of nanoparticles was concentration dependent, and the silver agglomerates were typically found in the cytoplasm. Furthermore, a concentration-dependent activation (e.g. an increased expression of adhesion molecule CD54) of monocytes at Ag-NP concentrations of 10-15μgml(-1) was observed, and cytotoxicity of Ag-NP-treated monocytes was observed at Ag-NP levels of 25μgml(-1) and higher. However, no modulation of T-cell proliferation was observed in the presence of Ag-NP. Taken together, our results provide the first evidence for a cell-type-specific uptake of Ag-NP by peripheral blood mononuclear cells (PBMC) and the resultant cellular responses after exposure.

Anatomic and radiographic considerations for placement of transiliac screws in lumbopelvic fixations.

Lumbopelvic fixation in spinal and pelvic surgery relies on rods or screws as an iliac anchor. Secure placement of screws with maximum diameter and length for the greatest pullout strength requires knowledge of the iliac structure and of intraoperative fluoroscopic landmarks for secure placement. Therefore, the authors evaluated the intrailiac length, inner width, and cortical thickness of three different transiliac screw anchor paths aimed toward the anterior inferior iliac spine and initiated at the iliac tubercle, posterior superior iliac spine, or posterior inferior iliac spine. Measurements were made using two- and three-dimensional computed tomographic reformations in 40 consecutive trauma patients (27 measurements in 21 males, 16 to 75 years old; 28 measurements in 19 females, 16 to 78 years old). In addition, fresh and dry human cadaveric specimens were marked with metal wires at the previously determined optimal screw path to determine fluoroscopic landmarks for easiest and best controlled transiliac screw placement. The posterior superior iliac spine–anterior inferior iliac spine path had the largest bony canal lengths, with 141 mm in male and 129 mm in female patients. Two stereotypic iliac constrictions allowed placement of 8-mm implants in male and 6- to 7-mm implants in female patients. Cortical thickness at that optimal extraarticular path was 5.2 mm in the male and 4.7 mm in the female patients. Transiliac screws can be placed during operation under fluoroscopic control using standard lateral and obturator oblique–outlet views, the latter presenting a stereotypical teardrop figure above the acetabulum.

Diagnosis and Management of Thoracolumbar Spine Fractures

The lack of robust clinical studies has contributed to controversy regarding optimal treatment for patients with injuries to the thoracolumbar spine. The transitional anatomy of the thoracolumbar spine makes it vulnerable to injury resulting from high-energy motor vehicle collisions and falls; osteoporosis is an underlying factor in most of the compression fractures identified in elderly patients. The formulation of a treatment plan for patients with injuries to the thoracolumbar spine depends on the presence and extent of neurologic injury and deformity and an estimate concerning spinal stability. Both nonsurgical and surgical treatment options are available to achieve the goals of preservation of neurologic function and restoration of spinal stability.

Extensor mechanism-sparing paratricipital posterior approach to the distal humerus

Adequate exposure of the articular surface of the distal humerus and elbow joint is required for operative stabilization of bicolumnar distal humerus fractures. The transolecranon approach, which provides complete posterior visualization and access to the distal humerus, is commonly used. Nevertheless, an olecranon osteotomy and other extensor mechanism-disrupting approaches have risks and possible complications. Alternative exposures have been described primarily for total elbow arthroplasty, but these involve extensive and potentially devascularizing dissections. In extra-articular (OTA type A) and simple articular distal humeral fractures with simple or multifragmentary metaphyseal involvement (OTA type C1 and C2), extensile approaches may not be necessary. For these fracture patterns, an alternative exposure is the extensor mechanism-sparing paratricipital posterior approach to the distal humerus through a midline posterior incision. This approach avoids an osteotomy and mobilizes the triceps and anconeus muscle off the posterior humerus and the intermuscular septae and provides adequate exposure for open reduction and internal fixation.

The biocompatibility of dense and porous Nickel–Titanium produced by selective laser melting

Nickel-Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required.

Diagnosis and management of sacral spine fractures

The sacrum is the mechanical hub of the axial skeleton, serving as the base for the spinal column and keystone for the pelvic ring. Both surgical and nonsurgical options are available to treat sacral spine fractures; however, because these fractures are relatively rare and heterogeneous in nature and because there is little evidence-based literature, choosing the optimal treatment is challenging. The timing of intervention and the choice of surgical technique need to be determined on an individual basis, with the goal of producing the best outcome for the patient.