3D model-assisted instrumentation of the pediatric spine: a technical note.

BACKGROUND: Instrumentation of the pediatric spine is challenging due to anatomical constraints and the absence of specific instrumentation, which may result in iatrogenic injury and implant failure, especially in occipito-cervical constructs. Therefore, preoperative planning and in vitro testing of instrumentation may be necessary. METHODS: In this paper, we present a technical note on the use of 1:1 scale patient-specific 3D printed spinal models for preoperative assessment of feasibility of spinal instrumentation with conventional spinal implants in pediatric spinal pathologies. RESULTS: The printed 3D models fully matched the intraoperative anatomy and allowed a preoperative confirmation of the feasibility of the planned instrumentation with conventional screws for adult patients. In addition, the possibility of intraoperative model assessment resulted in better intraoperative sense of spinal anatomy and easier freehand screw insertion, thereby reducing the potential for iatrogenic injury. All 3D models were printed at the surgical department at a very low cost, and the direct communication between the surgeon and the dedicated specialist allowed for multiple models or special spinal segments to be printed for more detailed consideration. CONCLUSIONS: Our technical note highlights the critical steps for preoperative virtual planning and in vitro testing of spinal instrumentation on patient-specific 3D printed models at 1:1 scale. The simple and affordable method helps to better visualize pediatric spinal anatomy and confirm the suitability of preplanned conventional spinal instrumentation, thereby reducing X-ray exposure and intraoperative complications in freehand screw insertion without navigation.

A 3D-Printed Model-Assisted Cervical Spine Instrumentation after Tumor Resection in a 4-Year-Old Child: A Case Report.

INTRODUCTION: In the case of tumor resection in the upper cervical spine, a multilevel laminectomy with instrumented fixation is required to prevent kyphotic deformity and myelopathy. Nevertheless, instrumentation of the cervical spine in children under the age of 8 years is challenging due to anatomical considerations and unavailability of specific instrumentation. CASE PRESENTATION: We present a case of 3D-printed model-assisted cervical spine instrumentation in a 4-year-old child with post-laminectomy kyphotic decompensation of the cervical spine and spinal cord injury 1 year after medulloblastoma metastasis resection in the upper cervical spine. Due to unavailability of specific instrumentation, 3D virtual planning was used to assess and plan posterior cervical fixation. Fixation with 3.5 mm lateral mass and isthmic screws was suggested and the feasibility of fixation was confirmed "in vitro" in a 3D-printed model preoperatively to reduce the possibility of intraoperative implant-spine mismatch. Intraoperative conditions completely resembled the preoperative plan and 3.5 mm polyaxial screws were successfully used as planned. Postoperatively the child made a complete neurological recovery and 2 years after the instrumented fusion is still disease free with no signs of spinal decompensation. DISCUSSION/CONCLUSION: Our case shows that posterior cervical fixation with the conventional screw-rod technique in a 4-year-old child is feasible, but we suggest that suitability and positioning of the chosen implants are preoperatively assessed in a printed 3D model. In addition, a printed 3D model offers the possibility to better visualize and sense spinal anatomy "in vivo," thereby helping screw placement and reducing the chance for intraoperative complications, especially in the absence of intraoperative spinal navigation.

Fractures of the acetabulum: from yesterday to tomorrow.

PURPOSE: The aim of this article is to present history, state of the art, and future trends in the treatment of acetabular fractures. METHODS: Review of recent and historical literature. RESULTS: Acetabular fractures are difficult to treat. The first descriptions of this injury already appeared in ancient Greek history, but intensive development started in the second half of the twentieth century after Judet and Letournel's seminal work. Their classification is still the gold standard today. It is actually a pre-operative planning system and is used to determine the most appropriate surgical approach. The therapy of choice for dislocated fractures is open reduction and internal fixation. Recent modern techniques based on high-tech computerized planning systems and 3D printing have been successfully integrated into orthopaedic trauma practice. CONCLUSION: There is no ideal surgical approach for acetabulum fracture treatment, so new approaches have been developed in recent decades. The best outcome series have shown good or excellent results, between 70 and 80%.

Window of opportunity for surgical decompression in patients with acute traumatic cervical spinal cord injury.

OBJECTIVE: The objective of this prospective study was to determine the optimal timing for surgical decompression (SD) in patients with acute traumatic cervical spinal cord injury (tSCI) within the first 24 hours of injury. METHODS: In successive patients with fracture and/or dislocation of the subaxial cervical spine and American Spinal Injury Association Impairment Scale (AIS) grades A-C, receiver operating characteristic curve analysis was used to determine the optimal timing for SD within the first 24 hours of cervical tSCI to obtain a neurological recovery of at least two AIS grades. Multivariate logistic regression was used to model significant neurological recovery with time to SD, degree of spinal canal compromise (SCC), and severity of injury. RESULTS: In this cohort of 64 patients, the optimal timing for SD to obtain a significant neurological improvement was within 4 hours of injury (95% confidence interval 4-9 hours). Increasing the delay from injury to SD or the degree of SCC significantly reduced the likelihood of significant neurological improvement. Due to the strong correlation with SCC, the severity of injury was a marginally significant predictor of neurological recovery. CONCLUSIONS: These findings indicate that in patients with acute cervical tSCI and AIS grades A-C, the optimal timing for SD is within the first 4-9 hours of injury, depending on the degree of SCC and the severity of injury. Further studies are required to better understand the interrelationships among the timing of SD, injury severity, and degree of SCC in these patients.

Neurological Recovery after Traumatic Cervical Spinal Cord Injury Is Superior if Surgical Decompression and Instrumented Fusion Are Performed within 8 Hours versus 8 to 24 Hours after Injury: A Single Center Experience.

A prospective study was performed to evaluate the impact of surgical decompression (SD) and instrumented fusion within 8 h versus 8-24 h after injury on neurological recovery after cervical traumatic spinal cord injury (tSCI) in patients operated on in the UMC Ljubljana, Slovenia. Only patients with the American Spinal Injury Association (ASIA) Impairment Scale (AIS) grades of A through C and with MRI-confirmed spinal cord compression were enrolled. The primary outcome was the change in AIS grade at the 6-month follow-up. Of the 48 enrolled patients, 22 patients who underwent surgery within 8 h (group 8 h) and 20 patients who underwent surgery between 8 and 24 h (Group 8-24 h) after injury concluded the study. At admission, there was no statistically significant difference in AIS grade between the study groups. At the 6-month follow-up, an improvement of at least two AIS grades was found in 45.5% of patients in group 8 h and in 10% of patients in group 8-24 h (p=0.017). The median improvement in the ASIA motor score was 38.5 (10.0-61.0) motor points in group 8 h and 15.0 (8.8-34.0) motor points in group 8-24 h (p=0.0468). In a multivariate analysis, adjusted for the preoperative AIS grade and the degree of spinal canal compromise, the odds of an at least two-grade AIS improvement were at least 106% higher for patients in group 8 h than for patients in group 8-24 h (odds ratio=11.08, p=0.004). No statistically significant difference was found in the rate of perioperative complications, pneumonia, and the number of ventilator-dependent days or the mortality between the groups. Our results suggest that the patients with tSCI who undergo SD within 8 h after injury have superior neurological outcomes than patients who undergo SD 8-24 h after injury, without any increase in the rate of adverse effects.

The effect of hyperbaric oxygen treatment on early regeneration of sensory axons after nerve crush in the rat.

Abstract The effect of hyperbaric oxygen treatment (HBO) on sensory axon regeneration was examined in the rat. The sciatic nerve was crushed in both legs. In addition, the distal stump of the sural nerve on one side was made acellular and its blood perfusion was compromised by freezing and thawing. Two experimental groups received hyperbaric exposures (2.5 ATA) to either compressed air (pO2 = 0.5 ATA) or 100% oxygen (pO2 = 2.5 ATA) 90 minutes per day for 6 days. Sensory axon regeneration in the sural nerve was thereafter assessed by the nerve pinch test and immunohistochemical reaction to neurofilament. HBO treatment increased the distances reached by the fastest regenerating sensory axons by about 15% in the distal nerve segments with preserved and with compromised blood perfusion. There was no significant difference between the rats treated with different oxygen tensions. The total number of regenerated axons in the distal sural nerve segments after a simple crush injury was not affected, whereas in the nerve segments with compromised blood perfusion treated by the higher pO2, the axon number was about 30% lower than that in the control group. It is concluded that the beneficial effect of HBO on sensory axon regeneration is not dose-dependent between 0.5 and 2.5 ATA pO2. Although the exposure to 2.5 ATA of pO2 moderately enhanced early regeneration of the fastest sensory axons, it decreased the number of regenerating axons in the injured nerves with compromised blood perfusion of the distal nerve stump.