Traumatic spinal injury patterns of on vs. off-road motorcycle crashes.

OBJECTIVE: Two wheel motorized vehicles used in both street transportation and recreation are a common cause of severe injury in the United States (US). To date, there has been limited data describing the spinal injury patterns among these motorcycle injury patients in the US. The goal of this study is to characterize and compare differences in specific injury patterns of patients sustaining traumatic spinal injuries after motocross (off-road) and street bike (on-road) collisions in the southwestern US at a Level I Trauma Center. METHODS: Trauma registry data was queried for patients sustaining a spinal injury after motorcycle collision from 2010 to 2019 at a single Level I Trauma Center. Computed tomography (CT) scan and magnetic imaging resonance imaging (MRI) reports from initial trauma evaluation were reviewed and data was manually obtained regarding injury morphology and location. RESULTS: A total of 1798 injuries were identified in 549 patients who sustained a motorcycle collision, specifically 67 off-road and 482 on-road motorcycle patients. Off-road motorcycle patients were found to be significantly younger (34.75 vs. 42.66, p = 0.00015). A total of 46.2% of the off-road injuries were determined to be from compression mechanisms, compared to 32.9% in the on-road cohort (p = 0.0027). The on-road cohort was more likely to have an injury classified as insignificant, such as transverse and spinous process fractures (60.1% vs. 42.5%, p = 00.25). There was no significant difference in regards to junctional, mobile, and semirigid spine segments between the two cohorts. CONCLUSIONS: Different fracture patterns were seen between the off-road and on-road motorcycle cohorts. Off road motorcyclists experienced significantly more compression and translational injuries, while on road motorcyclists experienced more frequent insignificant injury patterns. Data on the different fracture patterns may help professionals develop safety equipment for motorcyclists.

Minority Resident Physicians' Perspectives on the Role of Race/Ethnicity, Culture, and Gender in Their Surgical Training Experiences.

BACKGROUND: Female and racial/ethnic minority representation in surgical programs continues to trail behind other medical specialties. Various structural and perceived obstacles which contribute to a difficult path for underrepresented minority (URM) trainees have been identified, and efforts to reduce these hurdles are underway. Gaining perspective and insight from current surgical minority trainees may add valuable insight to aid with improving and innovating strategies to recruit and retain URM surgeons. OBJECTIVE: To characterize how race/ethnicity, cultural background, and gender affect the surgical training experience of URM surgical residents in all areas of surgery a focus on the field of Orthopedic Surgery, given its particularly poor rates of diversity. METHODS: Authors conducted semi-structured video interviews on current surgical residents or fellows who were members of underrepresented populations including Female, African-American/Black, Latino, Asian, Native American, and First or Second-generation immigrant status. Recruitment was achieved through a combination of voluntary, convenience, and snowball sampling procedures. Interview transcripts were then coded using conventional thematic analysis. Themes were iteratively expanded into subthemes and subsequently categorized utilizing a pile-sorting methodology. RESULTS: Among 23 surgical trainees 12 self-identified as Black (60.9%), 5 as Asian (17.4%), 1 as Hispanic (4.4%), and 5 as Caucasian (17.4%). Twelve residents identified as male (52%) and 11 as female (48%). Six surgical specialties were represented with the majority of participants (83%) being trainees in surgical subspecialties, among those orthopedic surgery was most strongly represented (57%). Analysis of their responses revealed 4 major themes: positive experiences, problems related to minority status, coping strategies, and participant suggested interventions. Themes were distilled further to sub-themes. Positive experiences' sub-themes included finding a supportive community, pride in minority status, and being able to better relate to patients. Negative experiences related to minority status' subthemes included perceived microaggressions and additional pressures, such as greater scrutiny and harsher punishments relative to their nonminority counterparts, which negatively impacted their surgical training. Most respondents did not feel there were dedicated resources to help alleviate these additional burdens, so some sought help outside of their training programs while others tried to assimilate, and others felt isolated. Recommended proposed interventions included validating the URM resident experience, providing education/training, and creating opportunities for mentorship. IMPLICATIONS/CONCLUSIONS: URM surgical trainees face numerous challenges related to their minority status. Recruitment and retention of URM in medicine would benefit from individual early and longitudinal mentorship, mitigating imposter syndrome, acknowledging the challenges faced by residents, and seeking feedback from both past and current residents.

Impact of implant metal type and vancomycin prophylaxis on postoperative spine infection: an in-vivo study.

PURPOSE: To evaluate the effectiveness of vancomycin prophylaxis on spinal implant metal types. METHODS: 42 rabbits underwent posterior, single-level instrumentation at L5-L6 with stainless steel (n = 18), cobalt chrome (n = 12), or titanium (n = 12) wire. All implants were inoculated with 1 × 106 colony forming units (CFU) of methicillin-resistant S. Aureus (MRSA). In the intrawound vancomycin subgroup (n = 18, 6 from each metal type), 40 mg of vancomycin powder was placed in the wound. In the IV vancomycin subgroup (n = 6, all stainless steel), 15 mg/kg of IV vancomycin was given preoperatively. Local soft tissue and implants were harvested 1-week postoperatively and separately cultured. RESULTS: Intrawound vancomycin significantly reduced the rate of soft tissue infection (44.4% vs 100%) and implant infection (27.8% vs 100%) (p < 0.001). Within the intrawound vancomycin subgroup, cobalt chrome implants were associated with higher median soft tissue MRSA growth (130 CFU) than stainless steel (0 CFU) or titanium (0 CFU) (p = 0.02). Cobalt chrome implants were also more likely to develop soft tissue MRSA infection (83.3%) as compared to stainless steel (16.7%) or titanium (33.3%) (p = 0.04). Median soft tissue MRSA growth among stainless steel implants without prophylaxis, with IV vancomycin, and with vancomycin powder was 1.18 × 107, 195, and 0 CFU, respectively. The rate of soft tissue MRSA infection without prophylaxis, with IV vancomycin, and with vancomycin powder was 100, 66.7, and 16.7%, respectively (p = 0.015). CONCLUSION: Intrawound vancomycin is more effective than IV vancomycin and effectively reduces the risk of infection, but is less effective in cobalt chrome implants due to residual soft tissue infection.

Preoperative Maximization to Reduce Complications in Spinal Surgery.

STUDY DESIGN: Invited narrative review. OBJECTIVES: The aim of this review was to summarize current literature regarding risk factors that surgeons can optimize in the preoperative setting in the spinal surgery patient, in order to reduce complications and improve patient-reported outcomes. METHODS: Review of the relevant literature by the authors. RESULTS: Modifiable risk factors identified relative to the patient include obesity, malnutrition/nutrient deficiency, diabetes/hyperglycemia, preoperative anemia, vitamin D/DEXA (dual-energy radiograph absorptiometry), nicotine use/smoking, and opioid use/psychosocial factors. CONCLUSION: By maximizing a patient's physiological and psychological status prior to elective spine surgery, we may move closer to achieving the goals of value-based care: improving patient-reported outcomes while decreasing the cost of care.

Headless Compression Screw Fixation of Vertical Medial Malleolus Fractures is Superior to Unicortical Screw Fixation.

This study is the first biomechanical research of headless compression screws for fixation of vertical shear fractures of the medial malleolus, a promising alternative that potentially offers several advantages for fixation. Vertical shear fractures were simulated by osteotomies in 20 synthetic distal tibiae. Models were randomly assigned to fixation with either 2 parallel cancellous screws or 2 parallel Acutrak 2 headless compression screws (Acumed). Specimens were subjected to offset axial loading to simulate supination-adduction loading and tracked using high-resolution video. The headless compression screw construct was significantly stiffer (P < .0001) (360 ± 131 N/mm) than the partially threaded cancellous screws (180 ± 48 N/mm) and demonstrated a significantly increased (P < .0001) mean load to clinical failure (719 ± 91 N vs 343 ± 83 N). When specimens were displaced to 6 mm and allowed to relax, the headless compression screw constructs demonstrated an elastic recoil and were reduced to the pretesting fragment alignment, whereas the parallel cancellous screw constructs remained displaced. Along with the headless design that may decrease soft tissue irritation, the increased stiffness and elastic recoil of the headless compression screw construct offers improved fixation of medial malleolus vertical shear fractures over the traditional methods.

Antiglide plating of vertical medial malleolus fractures provides stiffer initial fixation than bicortical or unicortical screw fixation.

BACKGROUND: Vertical shear fractures of the medial malleolus (44-A2 ankle fractures) occur through a supination-adduction mechanism. There are numerous methods of internal fixation for this fracture pattern. METHODS: Vertical medial malleolus osteotomies were created in synthetic distal tibiae. The models were divided into four fixation groups: two parallel unicortical cancellous screws, two divergent unicortical cancellous screws, two parallel bicortical cortical screws, or an antiglide plate construct. Specimens were subjected to offset axial loading and tracked using high-resolution video. FINDINGS: The antiglide plate construct was stiffer (P<0.05) than each of the other three constructs, and the bicortical screw construct was stiffer (P<0.05) than both unicortical screw constructs. The mean stiffness (standard deviation) was 111 (SD 35) N/mm for the parallel unicortical screw construct, 173 (SD 57) N/mm for the divergent unicortical screw construct, 279 (SD 30) N/mm for the bicortical screw construct, and 463 (SD 91) N/mm for the antiglide plate construct. The antiglide plate construct resisted displacement better (P<0.05) than each of the other three constructs. The mean force for 2mm of articular displacement was 284 (SD 51) N for the parallel unicortical screw construct, 339 (SD 46) N for the divergent unicortical screw construct, 429 (SD 112) N for the bicortical construct, and 922 (SD 297) N for the antiglide plate construct. INTERPRETATION: An antiglide plate construct provides the stiffest initial fixation while withstanding higher load to failure for vertical medial malleolus fractures when compared to unicortical and bicortical screw fixation.

BMP-7 and Bone Regeneration: Evaluation of Dose-Response in a Rodent Segmental Defect Model.

OBJECTIVES: To develop and validate a translatable and reproducible rodent critical-sized defect (CSD) model and to determine the optimal dose of recombinant human bone morphogenetic protein (BMP)-7 required to consistently heal the CSD in the new model. METHODS: Rats with 6-mm CSDs stabilized with a commercial radiolucent plate and screws with angular stability were randomly assigned to 4 treatment groups with varied doses of recombinant human BMP-7 (25, 50, 75, and 100 µg) on absorbable collagen sponge and a single control group (absorbable collagen sponge alone). Bone formation was evaluated by radiographs, micro-computed tomography, histology, and biomechanics. RESULTS: All the rats treated with 100 µg of BMP-7 with CSDs were united by 4 weeks and all 75- and 50-µg-group rats united by 6 weeks. None of the animals in the 25-µg BMP-7 group or the control group were healed at the time of killing. Bone volume, bone mineral density, the ratio of bone volume to total volume, stiffness, and ultimate load to failure were maximal in the 50-µg group. Total callus volume progressively increased with increasing BMP dose. Histologic analysis demonstrated increased callus width with increasing BMP-7 doses above 50 µg, but the bone seemed structurally abnormal. CONCLUSIONS: There was a 100% union rate in the 50-, 75-, and 100-µg BMP-7-treated groups. None of the control or 25-µg-dose rats united. The biomechanical data demonstrated that 50 µg of BMP-7 produced the highest mechanical strength in the bone regenerate. These data also suggest that administration of BMP-7 above 50 µg does not improve bone regeneration and actually seems to produce lower quality bone with diminished biomechanical properties.

Treatment of spine deformity in neuromuscular diseases.

Surgical management of spinal deformity in neuromuscular diseases (NMDs) often requires a multidisciplinary approach beginning in the preoperative surgical planning period, owing to concomitant restrictive lung disease and cardiomyopathy in selected NMD conditions. The need for thorough and thoughtful discussions must occur with the family and other caregivers before any scheduled surgery. The decision to proceed with spinal instrumentation may alter functional abilities in weak and marginally ambulatory NMD patients. With care and treatment involving a multidisciplinary team, proper planning, and support, patients will likely experience rewarding outcomes and improved quality of life.

Temporal and Spatial Expression of BMPs and BMP Antagonists During Posterolateral Lumbar Fusion.

STUDY DESIGN: Quantitative gene expression analysis and immunohistochemistry were used to investigate the temporal and spatial expression of bone morphogenic proteins (BMPs) and BMP antagonists in a posterolateral spine fusion model in rabbits. OBJECTIVE: To identify the expression pattern of BMPs and BMP antagonists and to determine the molecular and histologic changes of the graft and surrounding tissue during fusion. SUMMARY OF BACKGROUND DATA: There are no studies on BMP antagonists during spinal fusion. Furthermore, the reciprocal interaction between bone grafts and surrounding tissue is still unknown in fusion. METHODS: Eighteen New Zealand White rabbits underwent bilateral posterolateral spine fusion with autogenous bone graft. Rabbits were killed at 1, 2, 4, or 6 weeks after arthrodesis. The spinal fusions were analyzed by radiography. On the right side, specimens were collected from the outer zone over the transverse processes, the inner zone between the transverse processes, muscle surrounding bone grafts, and the transverse process. Gene expression of BMP-2, BMP-4, and BMP-7, noggin, chordin, Sox9, and Runx2 were measured by real-time polymerase chain reaction at each time point of each sample. On the left side, molecules of interest were evaluated by immunohistochemistry on tissue sections. RESULTS: BMP-2, BMP-4, and BMP-7, noggin, and chordin were colocalized in rimming osteoblasts, osteoclasts, and chondrocytes. The outer zone demonstrated earlier bone maturation and faster increase in BMP gene expression than the inner zone. Muscle surrounding bone grafts showed significantly higher BMP expression and Runx2 activity at the early phase. BMP-positive cells were also noted around blood vessels. CONCLUSION: The colocalization and temporal relationship of BMPs and BMP antagonists suggests that BMP activity is tightly regulated by the antagonists during fusion. In addition, not only the decorticated transverse process, but also muscle surrounding bone grafts, is actively involved in osteogenesis during fusion.

Efficacy of mesenchymal stem cell enriched grafts in an ovine posterolateral lumbar spine model.

STUDY DESIGN: Four groups of 6 animals underwent single-level noninstrumented posterolateral lumbar fusion (PLF) with one of the following grafts: 1) autograft, 2) cell-enriched beta-tricalcium phosphate (TCP), 3) TCP with whole bone marrow, and 4) TCP alone. Plain radiographs were taken after surgery and at death, 6 months after surgery. Explanted spine segments were analyzed by manual palpation, micro-CT, and histology. OBJECTIVE: A sheep spine fusion study was undertaken to evaluate the healing performance of a TCP graft enriched with osteoprogenitor cells using Selective Cell Retention technology (SCR), compared with autograft, TCP with whole bone marrow, and TCP alone. SUMMARY OF BACKGROUND DATA: Improved bone healing with previously demonstrated using grafts enriched in osteoprogenitor cells. METHODS: Cell-enriched grafts were obtained by processing 30 mL of bone marrow through 10 mL of TCP. TCP was also used either saturated with bone marrow or alone. RESULTS: At 6 months, 33% of the SCR-enriched TCP and 25% of the autograft sites were fused, compared with 8% of the TCP plus whole bone marrow and 0% of the TCP alone. Histology of fused samples showed denser bone formation in the SCR-enriched TCP grafts than in the autograft sites. CONCLUSIONS: The use of SCR-enriched TCP and autograft resulted in similar fusion rates in an ovine posterolateral noninstrumented lumbar spine fusion model.

Estrogen-dependent actions of bone morphogenetic protein-7 on spine fusion in rats.

STUDY DESIGN: Intertransverse process spinal fusion using recombinant human bone morphogenetic protein-7 (rhBMP-7) was performed in intact and ovariectomized female rats. OBJECTIVES: To examine fusion rates in intact and ovariectomized female rats using rhBMP-7 to determine if spine fusion is dependent on estrogen status. SUMMARY OF BACKGROUND DATA: Rat spinal fusion has been established as a consistent, efficient model for posterolateral intertransverse process fusion. Previous experiments have confirmed the efficacy of pellets containing the carrier, insoluble collagen bone matrix (ICBM), and rhBMP-7 to augment intertransverse process single level fusion in a rat model. Studying these implications in an osteoporosis model is of clinical value because there are many patients undergoing spinal fusion surgery that have osteoporotic bone disease, and there is a steady increase in this group of patients. METHODS: A total of 15 ovariectomized and 15 intact Sprague-Dawley female rats were randomly assigned to groups receiving 25 mg ICBM alone, 25 mg ICBM + 10 microg rhBMP-7, and 25 mg ICBM + 30 microg rhBMP-7. Spinal fusion was evaluated by manual motion testing at each lumbar segment, radiographic evaluation using the Lenke grading system, and histology. RESULTS: Ovariectomized and intact rats receiving 25 mg carrier ICBM alone did not show spinal fusion. With 25 mg ICBM + 10 microg rhBMP-7, there was not a significant difference in fusion rates between intact and ovariectomized rats (P = 0.63). Ovariectomized rats receiving 25 mg ICBM + 30 microg rhBMP-7 showed significantly lower fusion rates than intact rats (P = 0.013). CONCLUSION: These data suggest that spinal fusion using rhBMP-7 is estrogen-dependent in rats. At the dosages used, rhBMP-7 was unable to overcome the inhibitory effects of estrogen deficiency on spinal fusion.

Bone grafts and bone morphogenetic proteins in spine fusion.

Spinal fusions are being performed for various pathologies of the spine. Stabilizing vertebral segments by eliminating motion across those segments becomes critical in dealing with pathologies of the spine that lead to instability. The use of autograft has been the gold standard for spine fusion. However, due to complications such as donor site morbidity, increased operating time, and limited supply, the use of allograft as a graft extender has become an acceptable practice especially in fusions spanning multiple segments. The discovery and isolation of novel proteins (i.e., bone morphogenetic proteins, BMPs), which initiate the molecular cascade of bone formation, have experimentally been shown in numerous animal studies to be as effective as autografts. Although the use of BMPs has exciting applications in spine surgery, long-term clinical studies must be evaluated for its efficacy in various applications in humans. The use of biomimetic materials such as hydroxyapatite (HA), or tricalcium phosphate (TCP) has also been examined in several animal models as bone graft substitutes or carriers. Although these materials have shown some promise in specific site applications, more work remains in elucidating an efficacious combination of these materials and BMPs that can be as effective as autografts. This review will present the status of bone grafts, bone morphogenetic proteins, gene therapy, and work that has been done to facilitate spinal fusion and simultaneously eliminate the need for bone graft.