The influence of ligament biomechanics on proximal junctional kyphosis and failure in patients with adult spinal deformity.

Purpose: It is unknown whether the biomechanics of the posterior ligamentous complex (PLC) are impaired in individuals undergoing surgery for adult spinal deformity (ASD). Characterizing these properties may improve our understanding of proximal junctional kyphosis (PJK; defined as proximal junctional angle [PJA] of >10 deg from UIV-1 to UIV + 2), as well as proximal junctional failure (PJF; symptomatic PJK requiring revision). The purpose of this prospective observational study is to compare biomechanical properties of the PLC in individuals with ASD who do, and do not develop PJK or PJF within 1 year of spinal fusion surgery. Methods: Intraoperative biopsies of PLC were obtained from 32 consecutive patients undergoing spinal fusions for ASD (>4 levels). Ligament peak force, tensile stress, tensile strain, and elastic modulus (EM) were measured with a materials testing system. Biomechanical properties and tissue dimensions were correlated with age, gender, BMI, vitamin D level, osteoporosis, sagittal alignment, PJA and change in PJA preoperatively, within 3 months, and at 1 year postoperatively. Results: Longer ligaments were associated with greater PJA change at 3 months (p = 0.04), and thinner ligaments were associated with greater PJA change at 1 year (r = 0.57, p = 0.01). Greater EM was associated with greater PJA at both 3 months and 1 year (p = 0.03). Five participants had a change in PJA of >10 1 year postoperatively, and three participants demonstrated PJF. EM was significantly higher in individuals who required revision surgery (p = 0.003), and ligament length was greater (p = 0.03). Preoperative sagittal alignment was not related to incidence of revision surgery (p > 0.10). Conclusions: The biomechanical properties of the PLC may be associated with higher risk for proximal failure. Ligaments that are longer, thinner, and less elastic are associated with higher postoperative PJA. Furthermore stiffer EM of the ligament is associated with the need for revision surgery.

Establishing objective volume-outcome measures for anterior and posterior cervical spine fusion.

OBJECTIVES: There is a growing literature on the relationship between provider volume and patient outcomes, specifically within joint arthroplasty and lumbar spine surgery. Such benchmarks have yet to be established for many other spinal procedures, including cervical fusion. We sought to determine whether outcomes-based volume measures for both surgeons and hospitals can be established for cervical spine fusion procedures. PATIENTS AND METHODS: This was a retrospective review of patient data in the Florida Statewide Inpatient Dataset (SID; 2011-14). Patients identified in the Florida SID who underwent either anterior or posterior cervical fusion were identified along with the operative surgeons and the hospitals where the procedures were performed. Socio-demographic data, as well as medical and surgical characteristics were obtained, as were the development of complications and readmissions up to 90days following hospital discharge. Surgeon and hospital volume were plotted separately against the number of complications and readmissions in an adjusted spline analysis. Multivariable logistic regression analysis was subsequently performed to assess the effect of surgeon and hospital volume on post-operative complications and readmissions. RESULTS: There were 8960 patients with posterior cervical fusion and 57,108 anterior cervical fusions (total=66,068) identified for inclusion in the analysis. The patients of low-volume surgeons were found to have an increased (OR 1.83; 95% CI 1.65, 2.02) likelihood of complications following anterior and posterior (OR 1.45; 95% CI 1.24, 1.69) cervical fusion. Low-volume surgeons demonstrated increased likelihood of readmission, irrespective of anterior (OR 1.37; 95% CI 1.29, 1.47) or posterior (OR 1.31; 95% CI 1.16, 1.48) approach. No clinically meaningful differences in the likelihood of complications or readmissions were detected between high- and low-volume hospitals. CONCLUSIONS: This study demonstrates objective volume-outcome measures for surgeons who perform anterior and posterior cervical fusions. Our results have immediate applicability to clinical practice and may be used to benchmark procedural volume. Findings with respect to hospitals speak against the need for healthcare regionalization in this specific clinical context.

Overtightening of the syndesmosis revisited and the effect of syndesmotic malreduction on ankle dorsiflexion.

BACKGROUND: Ankle syndesmotic injuries are a significant source of morbidity and require anatomic reduction to optimize outcomes. Although a previous study concluded that maximal dorsiflexion during syndesmotic fixation was not required, methodologic weaknesses existed and several studies have demonstrated improved ankle dorsiflexion after removal of syndesmotic screws. The purposes of the current investigation are: (1) To assess the effect of compressive syndesmotic screw fixation on ankle dorsiflexion utilizing a controlled load and instrumentation allowing for precise measurement of motion. (2) To assess the effect of anterior & posterior syndesmotic malreduction after compressive syndesmotic screw fixation on ankle dorsiflexion. MATERIAL AND METHODS: Fifteen lower limb cadaveric leg specimens were utilized for the study. Ankle dorsiflexion was measured utilizing a precise micro-sensor system after application of a consistent load in the (1) intact state, (2) after compression fixation with a syndesmotic screw and (3) after anterior & (4) posterior malreduction of the syndesmosis. RESULTS: Following screw compression of the nondisplaced syndesmosis, dorsiflexion ROM was 99.7±0.87% (mean±standard error) of baseline ankle ROM. Anterior and posterior malreduction of the syndesmosis resulted in dorsiflexion ROM that was 99.1±1.75% and 98.6±1.56% of baseline ankle ROM, respectively. One-way ANOVA was performed showing no statistical significance between groups (p-value=0.88). Two-way ANOVA comparing the groups with respect to both the reduction condition (intact, anatomic reduction, anterior displacement, posterior displacement) and the displacement order (anterior first, posterior first) did not demonstrate a statistically significant effect (p-value=0.99). CONCLUSION: Maximal dorsiflexion of the ankle is not required prior to syndesmotic fixation as no loss of motion was seen with compressive fixation in our cadaver model. Anterior or posterior syndesmotic malreduction following syndesmotic screw fixation had no effect on ankle dorsiflexion. Poor patient outcomes after syndesmotic malreduction may be due to other factors and not loss of dorsiflexion motion. LEVEL OF EVIDENCE: IV.

Blurred front lines: triage and initial management of blast injuries.

Recent armed conflicts and the expanded reach of international terror groups has resulted in an increased incidence of blast-related injuries in both military and civilian populations. Mass-casualty incidents may require both on-scene and in-hospital triage to maximize survival rates and conserve limited resources. Initial evaluation should focus on the identification and control of potentially life-threatening conditions, especially life-threatening hemorrhage. Early operative priorities for musculoskeletal injuries focus on the principles of damage-control orthopaedics, with early and aggressive debridement of soft-tissue wounds, vascular shunting or grafting to restore limb perfusion, and long-bone fracture stabilization via external fixation. Special considerations such as patient transport, infection control and prevention, and amputation management are also discussed. All orthopedic surgeons, regardless of practice setting, should be familiar with the basic principles of evaluation, resuscitation, and initial management of explosive blast injuries.

Intraspinal penetrating stab injury to the middle thoracic spinal cord with no neurologic deficit.

The annual incidence of traumatic spinal cord injury worldwide is estimated to be 35 patients per million. Nonmissile penetrating spinal injuries most commonly occur in the thoracic region, and the majority has neurologic deficits on admission. The management of patients who lack neurologic deficits is controversial due to the risk of neurologic status alteration intraoperatively. However, failure to intervene increases the risk of infection, delayed onset of neurologic deficits, and worsening functional outcome.A 17-year-old boy presented with an intradural T7-T8 knife penetration injury to the spinal cord with no neurologic deficit. Rapid surgical intervention was critical because the knife was lodged between the 2 hemispheres of the spinal cord. The patient was intubated in the lateral position, transferred to the prone position on a Jackson table, and underwent surgical decompression with laminectomy 1 level above and below the injury site, removal of the knife blade in the original path of trajectory, and repair of the dural tear with a collagen matrix. The patient sustained no neurologic sequelae from the penetrating knife injury. He was able to ambulate at discharge and had no complications. To our knowledge, this is the only report of a patient with intradural spinal cord penetration by a foreign object (knife blade) presenting with a normal neurologic preoperative examination that persisted throughout the course of postoperative care.