Wubing He

Kinematic analysis of the relationship between sagittal alignment and disc degeneration in the cervical spine.

Study Design. Retrospective analysis using kinetic magnetic resonance images (MRIs). Objective. To investigate the relationship of changes in the sagittal alignment of the cervical spine on the kinematics of the functional motion unit and disc degeneration. Summary of Background Data. Normal lordotic alignment is one of the most important factors contributing to effective motion and function of the cervical spine. Loss of normal lordotic alignment may induce pathologic changes in the kinematics and accelerate degeneration of the functional motion unit. However, the relationship of altered alignment on kinematics and degeneration has not been evaluated. Methods. Kinetic MRIs in flexion, neutral, and extension were performed. Study participants were classified into 5 groups based on the C1–C7 Cobb angle of sagittal alignment—Group A: Kyphosis (n = 19), Group B: Straight (n = 29), Group C: Hypolordosis (n = 38), Group D: Normal (n = 63), and Group E: Hyperlordosis (n = 52). Intervertebral disc degeneration was graded (Grades 1–5), and the kinematics of the functional spinal unit were obtained. Results. When the alignment shifted from normal to less lordotic, the translational motion and angular variation tended to decrease at all levels. The contribution of the C1–C2, C2–C3, and C3–C4 levels to total angular mobility tended to be higher in Group C than Group D. However, the contribution of the C4–C5, C5–C6, and C6–C7 levels tended to be lower in Group C than in Group D. The grade of disc degeneration associated with loss of lordosis tended to be higher than that associated with normal alignment at the C2–C3 and C3–C4 levels. Conclusion. The present study demonstrated that the changes in sagittal alignment of the cervical spine affect the kinematics. Consequently, it may cause changes in the segment subjected to maximum load for overall motion and accelerate its degeneration.

Lumbar Segmental Mobility According to the Grade of the Disc, the Facet Joint, the Muscle, and the Ligament Pathology by Using Kinetic Magnetic Resonance Imaging

Study Design. The kinematic study of human lumbar spinal movements. Objective. To investigate how disc degeneration and the degeneration of facet joint, ligaments, and paraspinal muscles are associated with lumbar segmental mobility. Summary of Background Data. Previous studies revealed relationship between spinal motion and osteoarthritic changes of facet joint as well as disc degeneration; however, little is known about the association of disc, facet joint, ligament, and muscle degeneration with lumbar segmental motion characteristics. Methods. The 1580 lumbar motion segments from 316 patients (200 male, 116 female) underwent Kinetic magnetic resonance imaging, which were used to assess disc degeneration (grade I–V) and facet joint degeneration (grade 1–4), interspinous ligament (ISL) degeneration (grade 1–4), ligamentum flavum hypertrophy (LFH), and fatty degeneration of muscles. Segmental translational and angular motion in the flexion, extension, and neutral postures were digitally automatically measured by MR analyzer. Results. Grade II (46.77%) disc, grade 1 (48.35%) facet joint degeneration, and grade 1 (64.1%) ISL were most common. LFH was most common in L4–L5 (49/330, 14.8%). In younger age (<35), grade I disc and grade 1 facet joint were predominant compared with the older age (35≤ and <45) in which grade III, IV, and V disc and grade 2 facet joint were predominant (P < 0.05). Translational motion increased significantly in high grade of disc and facet joint (except grade V disc and grade 4 facet joint) and with LFH in L1–L5 (P < 0.05). Angular motion significantly decreased in grade V disc, grade 4 ISL, and without LFH in L1–L5 (P < 0.05). According to muscle fatty degeneration, translational and angular motions were not significantly changed. Conclusion. Our results support that facet joint degeneration is followed by disc degeneration according to age. Increased translational movements of the lumbar segments occurred in severe disc degeneration accompanied by facet joint degeneration or the presence of LFH even if the movements were stabilized in the advanced status. Therefore, the current status of the intervertebral discs, facet joints, and ligamentum flavum should be taken into consideration when evaluating stability within the lumbar spine.

A porcine collagen-derived matrix as a carrier for recombinant human bone morphogenetic protein-2 enhances spinal fusion in rats

BACKGROUND CONTEXT Recombinant bone morphogenetic proteins (rhBMPs) have been used successfully in clinical trials. However, large doses of rhBMPs were required to induce adequate bone repair. Collagen sponges (CSs) have failed to allow a more sustained release of rhBMPs. Ongoing research aims to design carriers that allow a more controlled and sustained release of the protein. E-Matrix is a injectable scaffold matrix that may enhance rhBMP activity and stimulate bone regeneration. PURPOSE The purpose of this study was to test E-Matrix as a carrier for rhBMPs in a CS and examine its feasibility in clinical applications by using a rat spinal fusion model. PATIENT SAMPLE A total of 80 Lewis rats aged 8-16 weeks were divided into nine groups. STUDY DESIGN/SETTING Rat spinal fusion model. OUTCOME MEASURES Radiographs were obtained at 4, 6, and 8 weeks. The rats were sacrificed and their spines were explanted and assessed by manual palpation, high-resolution microcomputed tomography (micro-CT), and histologic analysis. METHODS Group I animals were implanted with CS alone (negative control); Group II animals with CS containing 10microg rhBMP-2 (positive control); Group III animals with CS containing 3microg rhBMP-2; Group IV animals with CS containing 3microg rhBMP-2 and E-Matrix; Group V animals with CS containing 1microg rhBMP-2; Group VI animals with CS containing 1microg rhBMP-2 and E-Matrix; Group VII animals with CS containing 0.5microg rhBMP-2; Group VIII animals with CS containing 0.5microg rhBMP-2 and E-Matrix; and Group IX animals with CS and E-Matrix without rhBMP-2. RESULTS Radiographic evaluation, micro-CT, and manual palpation revealed spinal fusion in all rats in the BMP-2 and E-Matrix groups (IV, VI, and VIII) and high-dose BMP-2 groups (II and III). Four spines in the 3microg rhBMP-2 group (V) fused, and one spine in the 0.5microg rhBMP-2 group (VII) exhibited fusion. No spines were fused in Groups I (CS alone) and IX (E-Matrix alone). The volume of new bone in the area between the tip of the L4 transverse process and the base of the L5 transverse process in Group IV was equivalent to the volumes observed in Group II. CONCLUSION E-matrix enhances spinal fusion as a carrier for rhBMP-2 in a rat spinal fusion model. The results of this study suggest that E-Matrix as a growth factor carrier may be applicable to spinal fusion and may improve rhBMP-2s activity at the fusion site.

Bone morphogenetic protein binding peptide mechanism and enhancement of osteogenic protein-1 induced bone healing.

Study Design. In vitro and in vivo evaluation of BBP interactions with BMP. Objective. To explore bone morphogenetic protein-binding peptide (BBP)s mechanism of action, investigate an extended repertoire for BBP applications, and evaluate the usefulness of BBP as a surgical adjuvant when used with recombinant human osteogenic protein-1 (rhOP-1). Summary of Background Data. Bone morphogenetic proteins (BMPs) are osteoinductive proteins that provide a potential alternative to autograft. Their utility is limited by cost, and potential dose-dependent risks, such as local inflammatory reactions and ectopic bone formation. BBP, a cyclized synthetic peptide, avidly binds recombinant human BMP-2(rhBMP-2) and has been shown to accelerate and enhance its osteogenic qualities. Methods. BBP binding with 4 growth factors from the transforming growth factor -beta family were assessed using surface plasmon resonance. The in vivo retention of rhBMP-2 was quantified by comparing the percentage of retained [125I]-labeled rhBMP-2 in absorbable collagen sponge implants with or without BBP at 1, 3, and 7 days postimplantation. The adjunctive effect of BBP with rhOP-1-induced bone growth was evaluated by comparing time to fusion and fusion rates in a rodent posterolateral fusion model with 2 different doses of rhOP-1 with or without BBP. Results. BBP bound all 4 growth factors with an intermediate affinity. The in vivo retention of rhBMP-2 alone ranged from about 40% on day 1 to about 30% on day 7, whereas, the retention of rhBMP-2 in the presence of BBP was about 85% on day 1 and about 55% on day 7. The addition of BBP to rhOP-1 resulted in significantly earlier and greater fusion rates than achieved with rhOP-1 alone. Conclusion. The mechanism of the BBP enhanced osteoinductive properties of BMPs involves the binding and retention of the growth factor, resulting in a prolonged exposure of BMP to the desired fusion site. The use of BBP in conjunction with BMPs may prove to provide satisfactory fusion outcomes, while reducing the costs and side effects associated with BMP use.

Relationship of Facet Tropism with Degeneration and Stability of Functional Spinal Unit

Purpose The authors investigated the effect of lumbar facet tropism (FT) on intervertebral disc degeneration (DD), facet joint degeneration (FJD), and segmental translational motion. Materials and Methods Using kinetic MRI (KMRI), lumbar FT, which was defined as a difference in symmetry of more than 7° between the orientations of the facet joints, was investigated in 900 functional spinal units (300 subjects) in flexion, neutral, and extension postures. Each segment at L3-L4, L4-L5, and L5-S1 was assessed based on the extent of DD (grade I-V) and FJD (grade 1-4). According to the presence of FT, they were classified into two groups; one with FT and one with facet symmetry. For each group, demographics, DD, FJD and translational segmental motion were compared. Results The incidence of FT was 34.5% at L3-L4, 35.1% at L4-L5, and 35.2% at L5-S1. Age and gender did not show any significant relationship with FT. Additionally, no correlation was observed between DD and FT. FT, however, wasfound to be associated with a higher incidence of highly degenerated facet joints at L4-L5 when compared to patients without FT (p < 0.01). Finally, FT was not observed to have any effects upon translational segmental motion. Conclusion No significant correlation was observed between lumbar FT and DD or translational segmental motion. However, FT was shown to be associated significantly with the presence of high grades of FJD at L4-L5. This suggests that at active sites of segmental motion, FT may predispose to the development of facet joint degeneration.

Enhanced effects of BMP-binding peptide combined with recombinant human BMP-2 on the healing of a rodent segmental femoral defect.

BMP‐binding peptide (BBP) enhances the osteogenic activity of recombinant human bone morphogenetic protein‐2 (rhBMP‐2), but the mechanism underlying the enhancement remains unclear. We aimed to elucidate the potential enhanced efficacy of BBP using critical‐sized segmental femoral bone defects in rats. Seventy defects in seven groups of rats were filled with various amounts (0, 2, 5, and 10 µg) of rhBMP‐2 with or without 1000 µg BBP. Radiographs were obtained after 4 and 8 weeks. The animals were euthanized at 8 weeks, and femoral specimens were assessed manually, evaluated for bone volume using microcomputed tomography, and subjected to histological or biomechanical analysis. Although 10 µg rhBMP‐2 yielded consistent results in terms of bone healing and quality of bone repair across the segmental defect, lower doses of rhBMP‐2 failed to induce satisfactory bone healing. However, the combined administration of lower doses of rhBMP‐2 and BBP induced the formation of significantly large amounts of bone. Our results suggest that the combined administration of rhBMP‐2 and BBP facilitates bone healing and has potential clinical applications.

Review article: Kinematic evaluation of the spine: a kinetic magnetic resonance imaging study

Kinetic magnetic resonance images (kMRIs) of 587 lumbar and 459 cervical spines of symptomatic patients in axially loaded, upright neutral (0°), flexion (40°), and extension (-20°) positions were evaluated. Imaging took 10 to 12 minutes to complete in each position. Cervical kinematics were significantly affected by intervertebral disc degeneration, cervical cord compression, and sagittal alignment of the cervical spine. kMRI was effective in diagnosing lumbar disc herniations that are often missed using conventional MRI. kMRI is effective for diagnosing, evaluating, and managing degenerative disease or injury within the spine.