Transient Local Bone Remodeling Effects of rhBMP-2 in an Ovine Interbody Spine Fusion Model

Background: Recombinant human bone morphogenetic protein-2 (rhBMP-2) is a powerful osteoinductive morphogen capable of stimulating the migration of mesenchymal stem cells (MSCs) to the site of implantation and inducing the proliferation and differentiation of these MSCs into osteoblasts. Vertebral end-plate and vertebral body resorption has been reported after interbody fusion with high doses of rhBMP-2. In this study, we investigated the effects of 2 rhBMP-2 doses on peri-implant bone resorption and bone remodeling at 7 time points in an end-plate-sparing ovine interbody fusion model. Methods: Twenty-one female sheep underwent an end-plate-sparing discectomy followed by interbody fusion at L2-L3 and L4-L5 using a custom polyetheretherketone (PEEK) interbody fusion device. The PEEK interbody device was filled with 1 of 2 different doses of rhBMP-2 on an absorbable collagen sponge (ACS): 0.13 mg (1·) or 0.90 mg (7·). Bone remodeling and interbody fusion were assessed via high-resolution radiography and histological analyses at 1, 2, 3, 4, 8, 12, and 20 weeks postoperatively. Results: Peri-implant bone resorption peaked between 3 and 8 weeks in both the 1· and the 7· rhBMP-2/ACS-dose group. Osteoclastic activity and corresponding peri-implant bone resorption was dose-dependent, with moderate-tomarked resorption at the 7·-dose level and less resorption at the 1·-dose level. Both dose (p \u3c 0.0007) and time (p \u3c 0.0025) affected bone resorption significantly. Transient bone-resorption areas were fully healed by 12 weeks. Osseous bridging was seen at all but 1 spinal level at 12 and at 20 weeks. Conclusions: In the ovine end-plate-sparing interbody fusion model, rhBMP-2 dose-dependent osteoclastic resorption is a transient phenomenon that peaks at 4 weeks postoperatively. Clinical Relevance: Using the U.S. Food and Drug Administration (FDA)-approved rhBMP-2 concentration and matching the volume of rhBMP-2/ACS with the volume of desired bone formation within the interbody construct may limit the occurrence of transient bone resorption

Cervical Inclination Angle: Normative Values in an Adult Multiethnic Asymptomatic Population

Objective The role of the craniocervical complex in spinal sagittal alignment has rarely been analyzed but it may play a fundamental role in postoperative mechanical complications. The aim of the study is to analyze the normative value of the cervical inclination angle (CIA) in an adult asymptomatic multiethnic population. Methods Standing full-spine EOS of adult asymptomatic volunteers from 5 different countries were analyzed. The CIA was analyzed globally and then in each decade of life. Different ethnicities were compared. Comparisons between different groups was performed using a t-test and statistical significance was considered with a p-value < 0.05. Results EOS of 468 volunteers were analyzed. The global mean CIA was 80.2° with a maximum difference of 9° between T1 and T12 (p < 0.001). The CIA remains constant until 60 years old then decreases significantly passing from a mean value before 20 years old of 82.25° to 73.65° after 70 years old. A statistically significant difference was found between the Arabics and other ethnicities with the formers having an inferior CIA: this was related to a mean older age (p < 0.05) and higher body mass index (p < 0.05) in the Arabics. Conclusion The CIA remains constant until 60 years old and then reduces slightly but never under 70°. This angle is helpful to evaluate the lever arm at the upper instrumented vertebra after an adult spinal deformity surgery and could predict the occurrence of a proximal junctional kyphosis when its value is lower than normal. Further clinical studies must confirm this theory

The Posterior Cranial Vertical Line: A Novel Radiographic Marker for Classifying Global Sagittal Alignment

Objective To define a novel radiographic measurement, the posterior cranial vertical line (PCVL), in an asymptomatic adult population to better understand global sagittal alignment. Methods We performed a multicenter retrospective review of prospectively collected radiographic data on asymptomatic volunteers aged 20–79. The PCVL is a vertical plumb line drawn from the posterior-most aspect of the occiput. The horizontal distances of the PCVL to the thoracic apex (TA), posterior sagittal vertical line (PSVL, posterosuperior endplate of S1), femoral head center, and tibial plafond were measured. Classification was either grade 1 (PCVL posterior to TA and PSVL), grade 2 (PCVL anterior to TA and posterior to PSVL), or grade 3 (PCVL anterior to TA and PSVL). Results Three hundred thirty-four asymptomatic patients were evaluated with a mean age of 41 years. Eighty-three percent of subjects were PCVL grade 1, 15% were grade 2, and 3% were grade 3. Increasing PCVL grade was associated with increased age (p < 0.001), C7–S1 sagittal vertical axis (SVA) (p < 0.001), C2–7 SVA (p < 0.001). Additionally, it was associated with decreased SS (p = 0.045), increased PT (p < 0.001), and increased knee flexion (p < 0.001). Conclusion The PCVL is a radiographic marker of global sagittal alignment that is simple to implement and interpret. Increasing PCVL grade was significantly associated with expected changes and compensatory mechanisms in the aging population. Most importantly, it incorporates cervical alignment parameters such as C2–7 SVA. The PCVL defines global sagittal alignment in adult volunteers and naturally distributes into 3 grades, with only 3% being grade 3 where the PCVL lies anterior to the TA and PSVL

Supplemental Material - Characteristics of Spinal Morphology According to the “Current” and “Theoretical” Roussouly Classification Systems in a Diverse, Asymptomatic Cohort: Multi-Ethnic Alignment Normative Study (MEANS)

Supplemental Material for Characteristics of Spinal Morphology According to the “Current” and “Theoretical” Roussouly Classification Systems in a Diverse, Asymptomatic Cohort: Multi-Ethnic Alignment Normative Study (MEANS) by Yong Shen, BA, Zeeshan M. Sardar, MD, MSc, Matan Malka, BA, Prerana Katiyar, BS, Gabriella Greisberg, BS, Fthimnir Hassan, MPH, Justin L. Reyes, MS, Jean-Charles Le Huec, MD, Stephane Bourret, PhD, Kazuhiro Hasegawa, MD, PhD, Hee Kit Wong, MBBS, Gabriel Liu, MBBCh, Hwee Weng Dennis Hey, MBBS, Hend Riahi, MD, Michael Kelly, MD, Joseph M. Lombardi, MD, Lawrence G. Lenke, MD, and Multi-Ethnic Alignment Normative Study Group in Global Spine Journal.</p

Best Practice Guidelines for Assessment and Management of Osteoporosis in Adult Patients Undergoing Elective Spinal Reconstruction.

STUDY DESIGN: Expert consensus study. OBJECTIVE: This expert panel was created to establish best practice guidelines to identify and treat patients with poor bone health prior to elective spinal reconstruction. SUMMARY OF BACKGROUND DATA: Currently, no guidelines exist for the management of osteoporosis and osteopenia in patients undergoing spinal reconstructive surgery. Untreated osteoporosis in spine reconstruction surgery is associated with higher complications and worse outcomes. METHODS: A multidisciplinary panel with 18 experts was assembled including orthopedic and neurological surgeons, endocrinologists, and rheumatologists. Surveys and discussions regarding the current literature were held according to Delphi method until a final set of guidelines was created with over 70% consensus. RESULTS: Panelists agreed that bone health should be considered in every patient prior to elective spinal reconstruction. All patients above 65 and those under 65 with particular risk factors (chronic glucocorticoid use, high fracture risk or previous fracture, limited mobility, and eight other key factors) should have a formal bone health evaluation prior to undergoing surgery. DXA scans of the hip are preferable due to their wide availability. Opportunistic CT Hounsfield Units of the vertebrae can be useful in identifying poor bone health. In the absence of contraindications, anabolic agents are considered first line therapy due to their bone building properties as compared with antiresorptive medications. Medications should be administered preoperatively for at least 2 months and postoperatively for minimum 8 months. CONCLUSION: Based on the consensus of a multidisciplinary panel of experts, we propose best practice guidelines for assessment and treatment of poor bone health prior to elective spinal reconstructive surgery. Patients above age 65 and those with particular risk factors under 65 should undergo formal bone health evaluation. We also established guidelines on perioperative optimization, utility of various diagnostic modalities, and the optimal medical management of bone health in this population.Level of Evidence: 5

Best Practice Guidelines for Assessment and Management of Osteoporosis in Adult Patients Undergoing Elective Spinal Reconstruction

STUDY DESIGN: Expert consensus study. OBJECTIVE: This expert panel was created to establish best practice guidelines to identify and treat patients with poor bone health prior to elective spinal reconstruction. SUMMARY OF BACKGROUND DATA: Currently, no guidelines exist for the management of osteoporosis and osteopenia in patients undergoing spinal reconstructive surgery. Untreated osteoporosis in spine reconstruction surgery is associated with higher complications and worse outcomes. METHODS: A multidisciplinary panel with 18 experts was assembled including orthopedic and neurological surgeons, endocrinologists, and rheumatologists. Surveys and discussions regarding the current literature were held according to Delphi method until a final set of guidelines was created with over 70% consensus. RESULTS: Panelists agreed that bone health should be considered in every patient prior to elective spinal reconstruction. All patients above 65 and those under 65 with particular risk factors (chronic glucocorticoid use, high fracture risk or previous fracture, limited mobility, and eight other key factors) should have a formal bone health evaluation prior to undergoing surgery. DXA scans of the hip are preferable due to their wide availability. Opportunistic CT Hounsfield Units of the vertebrae can be useful in identifying poor bone health. In the absence of contraindications, anabolic agents are considered first line therapy due to their bone building properties as compared with antiresorptive medications. Medications should be administered preoperatively for at least 2 months and postoperatively for minimum 8 months. CONCLUSION: Based on the consensus of a multidisciplinary panel of experts, we propose best practice guidelines for assessment and treatment of poor bone health prior to elective spinal reconstructive surgery. Patients above age 65 and those with particular risk factors under 65 should undergo formal bone health evaluation. We also established guidelines on perioperative optimization, utility of various diagnostic modalities, and the optimal medical management of bone health in this population.Level of Evidence: 5

Best Practice Guidelines for Assessment and Management of Osteoporosis in Adult Patients Undergoing Elective Spinal Reconstruction.

Study designExpert consensus study.ObjectiveThis expert panel was created to establish best practice guidelines to identify and treat patients with poor bone health prior to elective spinal reconstruction.Summary of background dataCurrently, no guidelines exist for the management of osteoporosis and osteopenia in patients undergoing spinal reconstructive surgery. Untreated osteoporosis in spine reconstruction surgery is associated with higher complications and worse outcomes.MethodsA multidisciplinary panel with 18 experts was assembled including orthopedic and neurological surgeons, endocrinologists, and rheumatologists. Surveys and discussions regarding the current literature were held according to Delphi method until a final set of guidelines was created with over 70% consensus.ResultsPanelists agreed that bone health should be considered in every patient prior to elective spinal reconstruction. All patients above 65 and those under 65 with particular risk factors (chronic glucocorticoid use, high fracture risk or previous fracture, limited mobility, and eight other key factors) should have a formal bone health evaluation prior to undergoing surgery. DXA scans of the hip are preferable due to their wide availability. Opportunistic CT Hounsfield Units of the vertebrae can be useful in identifying poor bone health. In the absence of contraindications, anabolic agents are considered first line therapy due to their bone building properties as compared with antiresorptive medications. Medications should be administered preoperatively for at least 2 months and postoperatively for minimum 8 months.ConclusionBased on the consensus of a multidisciplinary panel of experts, we propose best practice guidelines for assessment and treatment of poor bone health prior to elective spinal reconstructive surgery. Patients above age 65 and those with particular risk factors under 65 should undergo formal bone health evaluation. We also established guidelines on perioperative optimization, utility of various diagnostic modalities, and the optimal medical management of bone health in this population.Level of Evidence: 5

Representativeness of the American Spine Registry: a comparison of patient characteristics with the National Inpatient Sample

The American Spine Registry (ASR) is a collaborative effort between the American Academy of Orthopaedic Surgeons and the American Association of Neurological Surgeons. The goal of this study was to evaluate how representative the ASR is of the national practice with spinal procedures, as recorded in the National Inpatient Sample (NIS). The authors queried the NIS and the ASR for cervical and lumbar arthrodesis cases performed during 2017-2019. International Classification of Diseases, 10th Revision and Current Procedural Terminology codes were used to identify patients undergoing cervical and lumbar procedures. The two groups were compared for the overall proportion of cervical and lumbar procedures, age distribution, sex, surgical approach features, race, and hospital volume. Outcomes available in the ASR, such as patient-reported outcomes and reoperations, were not analyzed due to nonavailability in the NIS. The representativeness of the ASR compared to the NIS was assessed via Cohen's d effect sizes, and absolute standardized mean differences (SMDs) of 0.5 were considered moderately large. A total of 24,800 arthrodesis procedures were identified in the ASR for the period between January 1, 2017, and December 31, 2019. During the same time period, 1,305,360 cases were recorded in the NIS. Cervical fusions comprised 35.9% of the ASR cohort (8911 cases) and 36.0% of the NIS cohort (469,287 cases). The two databases presented trivial differences in terms of patient age and sex for all years of interest across both cervical and lumbar arthrodeses (SMD < 0.2). Trivial differences were also noted in the distribution of open versus percutaneous procedures of the cervical and lumbar spine (SMD < 0.2). Among lumbar cases, anterior approaches were more common in the ASR than in the NIS (32.1% vs 22.3%, SMD = 0.22), but the discrepancy among cervical cases in the two databases was trivial (SMD = 0.03). Small differences were illustrated in terms of race, with SMDs < 0.5, and a more significant discrepancy was identified in the geographic distribution of participating sites (SMDs of 0.7 and 0.74 for cervical and lumbar cases, respectively). For both of these measures, SMDs in 2019 were smaller than those in 2018 and 2017. The ASR and NIS databases presented a very high similarity in proportions of cervical and lumbar spine surgeries, as well as similar distributions of age and sex, and distribution of open versus endoscopic approach. Slight discrepancies in anterior versus posterior approach among lumbar cases and patient race, and more significant discrepancies in geographic representation were also identified, yet decreasing trends in differences suggested the improving representativeness of the ASR over the course of time and its progressive growth. These conclusions are important to underline the external validity of quality investigations and research conclusions to be drawn from analyses in which the ASR is used