The influence of lumbar endplate morphology on the clinical and radiographic outcomes of lumbar disc arthroplasty has not been evaluated to the best of our knowledge.
Study Design and Objective
In this observational study of 80 patients, the objective was to formulate a reproducible and valid lumbar endplate classification system to be used in evaluating lumbar total disc replacement patients.
Methods
A novel vertebral endplate morphology classification system was formulated after review of data related to 80 patients enrolled in a prospective, randomized clinical trial in conjunction with an application for a US Food and Drug Administration investigational device exemption. Intraobserver and interobserver analyses of the classification system were performed on the same 80 patients utilizing the classification system.
Results
The initial review of the radiographs revealed 5 types of endplates: Type I (n = 82) flat endplates; Type II (n = 26) posterior lip; Type III (n = 5) central concavity; Type IV (n = 4) anterior sloping endplate; and Type V (n = 2) combination of Types I—IV. The intraobserver kappa was 0.66 and the interobserver kappa was 0.51. These kappa values indicate “substantial” to “moderate” reproducibility, respectively.
Conclusions
In this study, we propose a lumbar endplate classification system to be used in the preoperative assessment of patients undergoing lumbar disc arthroplasty. The classification can function as a basis for comparison and discussion among arthroplasty clinicians, and serve as a possible exclusionary screening tool for disc arthroplasty. Special consideration should be given to Type II endplates to optimize proper positioning and functioning of a total disc replacement (TDR) implant. Further outcome studies are warranted to assess the clinical significance of this classification system. The key points of our study are: (1) We present a novel lumbar vertebral endplate classification system; (2) Five types of endplates were identified and classified; (3) Intraobserver and interobserver reliability were classified as substantial and moderate, respectively; and (4) The classification system used may assist in the preoperative evaluation of patients for total disc replacement.
A prospective study of 22 patients with single-level cervical spondylosis.To quantify the changes in the biomechanics of the cervical spine after the insertion of a ProDisc-C (Synthes Spine, Paoli, PA) artificial disc.Cervical arthroplasty is designed to maintain cervical motion of the functional spinal unit (FSU) after cervical discectomy. The impact of the ProDisc-C on in vivo kinematics and sagittal alignment requires further assessment.Flexion/extension lateral radiographs of the cervical spine were prospectively collected and reviewed in 22 patients preoperatively and after the placement of ProDisc-C. Disc height (DH), FSU angle, range of motion (ROM), and center of rotation (COR) were calculated at each time point using validated, computer-assisted methods. Preoperative values were compared with the postoperative values using paired student t tests.Mean follow-up time was 11.0 months (SD, 2.4 mo). At the surgical level, the ProDisc-C produced increased segmental ROM (P = 0.03), an anterior shift of 1.1 mm in COR X (P = 0.004), and increased DH both anteriorly (P < 0.0001) and posteriorly (P < 0.0001). At the inferior adjacent level, anterior DH decreased (P < 0.05) and posterior DH increased (P = 0.02) after surgery. The FSU angle at the surgical level increased (P < 0.0001), but the inferior adjacent-level FSU angle decreased (P = 0.002). No significant changes were observed at the superior adjacent level.The ProDisc-C increased segmental ROM and shifted the COR anteriorly at the surgical level. DH increased at the surgical level. The surgical level became more lordotic, whereas the inferior adjacent level became more kyphotic after ProDisc-C implantation.
Photon-deficient areas in 99mTc/111 in white blood cell (WBC) images for diagnosing vertebral osteomyelitis have been published often. This study retrospectively evaluated whether the use of 99mTc-labeled monoclonal antigranulocyte antibodies (BW 250/183) is superior to WBC and whether it offers higher specificity.The study included 81 patients (46 men, 35 women; mean age 55 +/- 2 yr; from 1989 to 1995) with clinically suspected vertebral osteomyelitis who underwent scintigraphic imaging after intravenous injection of 555 MBq 99mTc-labeled monoclonal antigranulocyte antibodies. Forty patients suffered from osteomyelitis (20 men, 20 women; mean age 56 +/- 6 yr), 6 patients had metastases, 28 patients had spondylosis and disk herniation and 5 patients vertebral compression fractures. Diagnosis was not histologically verified in 2 patients. Planar imaging was performed at 4 and 24 hr postinjection. Histology of osteomyelitis was available in 30 patients, clinical follow-up in 10 patients. Visual uptake scores and quantitative uptake scores of the suspected areas were calculated. The results were compared to a semiquantitative histological score (high, medium, low grade) as well as to the scintigraphic scores.Scintigraphy showed photopenia in all patients with histologically proven vertebral osteomyelitis, independent of the grade of infection. A quantitative evaluation of 4 and 24 hr postinjection demonstrated a 58% increase of the uptake score in cases of histologically proven high-grade infections. This increase was seen predominantly in the thoracic spine but not in lumbar spine. All nonosseous paravertebral abscesses (n = 2) showed positive images and an increasing uptake over 24 hr.Paravertebral soft tissue infections can be differentiated excellently, whereas vertebral osteomyelitis, vertebral tumors or fractures can be localized, but no differentiation is possible.
