Sagittal cervical alignment after cervical disc arthroplasty and anterior cervical discectomy and fusion: results of a prospective, randomized, controlled trial.
ABSTRACT Radiographic results of a multicenter, prospective randomized study comparing 1-level cervical total disc replacement (TDR-C) with anterior cervical discectomy and fusion (ACDF).
To evaluate the effect on device-level lordosis, cranial and caudal adjacent level lordosis, and overall cervical sagittal alignment (C2-C6) after TDR-C or ACDF.
Cervical total disc replacement (TDR-C) has emerged as a promising alternative to ACDF in a select group of patients. The maintenance and/or improvement of sagittal balance is essential in preserving functionality after reconstructive spinal procedures. Recent studies have documented changes in spinal alignment after TDR-C, however, no studies have compared these changes to those noted in matched group of patients that have undergone ACDF.
Radiographic data were obtained from the randomized group of a multicenter, randomized, prospective, controlled study comparing TDR-C (ProDisc-C, Synthes Spine, West Chester, PA) with ACDF in the treatment of 1-level cervical disc disease. Complete radiographic data were available for 89 TDR-C patients (average age: 42.2 years) and 91 ACDF patients (average age: 41.7 years). Cervical lordosis at the device level, cranial and caudal adjacent levels, and total cervical lordosis (C2-C6) were independently measured before surgery and 2 years after surgery using custom image stabilization software (Quantitative Motion Analysis, Medical Metrics, Inc, Houston, TX).
C5-C6 was the most common operative level (TDR-C: 54%; ACDF: 55%). At 2 years after surgery, the TDR-C group experienced statistically significant changes in lordosis of 3.0 degrees (P < 0.001), 0.90 degrees (P = 0.006), and -1.9 degrees (P < 0.001) at the operative, cranial, and caudal adj-acent levels, respectively. ACDF experienced changes in lordosis of 4.2 degrees (P < 0.001), 1.0 degrees (P = 0.001), and -1.5 degrees (P = 0.001), respectively. The between-group differences were significant at the operative level (P = 0.03) and the caudal adjacent level (P = 0.05). Total cervical lordosis increased in both TDR-C and ACDF by 3.1 degrees and 3.8 degrees , respectively (P = 0.49).
In both TDR-C and ACDF, lordosis increased at the device-level, cranial adjacent level, and in total cervical lordosis, while lordosis decreased at the caudal adjacent level. Although ACDF facilitated a greater increase in device level lordosis (+1.25 degrees ) and less loss of lordosis at the caudal adjacent level compared with TDR-C (-0.39 degrees ), the clinical relevance of the small differences remain unknown.
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ABSTRACT: BACKGROUND:: The use of posterior instrumentation constructs is well established for subaxial cervical stabilizations/fusions. The importance of global and regional sagittal alignment has become increasingly recognized. OBJECTIVE:: Using computed tomography (CT) scans, an analysis was performed to determine the effect of posterior instrumentation on postoperative cervical sagittal alignment at long-term follow-up. METHODS:: Over a period of 6 years, 56 consecutive patients (38 males and 18 females; mean age 47 years) underwent cervical screw-rod fixation. Plain radiographs, CT scans, and MR images were analyzed preoperatively to assess sagittal alignment (C2-C7). Postoperatively, CT scans and serial radiographs were obtained in all patients. Using independent observers, changes in sagittal alignment were determined by comparing the preoperative and postoperative imaging studies. RESULTS:: In total, 390 screws were placed in the cervical spines of 56 patients. Definitive radiographic fusion was detected in all 56 (100%) patients. There were no incidences of instrumentation failures or lucencies surrounding any screws. Patients with preoperative kyphosis (N=19; mean +9.9°) improved their sagittal alignment by 6.5° (final mean: +3.4°), while patients with preoperative lordosis (N=37; mean -15.44°) maintained their lordosis (final mean: -15.3°). Mean duration of follow-up was 32.5 months. CONCLUSION:: Radiographic analysis showed lateral mass fixation to be safe and effective. Certain operative techniques allowed for substantial deformity correction and maintenance of long-term correction of deformity. Screw-rod fixation may be an effective method for maintaining lordotic cervical alignment in previously lordotic patients and for significantly correcting kyphotic deformity in patients with a preoperative kyphosis.Neurosurgery 02/2013; · 2.53 Impact Factor
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ABSTRACT: BACKGROUND CONTEXT: The evidence surrounding the topic of adjacent segment degeneration and disease has increased dramatically with an abundant amount of literature discussing the incidence of and techniques to avoid it. However, this evidence is often confusing to discern because of various definitions of both adjacent segment degeneration and disease. PURPOSE: To organize and review the recent evidence for adjacent segment degeneration and disease. RESULTS: Although multifactorial, three distinct causes of adjacent segment disease in both the lumbar and cervical spine have been discussed: the natural history of the adjacent disc; biomechanical stress on the adjacent level caused by the fusion; and disruption of the anatomy at the adjacent level with the initial surgery. The incidence of adjacent segment degeneration in the lumbar spine has been widely reported in the literature from 0% to 100%; conversely, the reported incidence in the cervical spine is less variable. Similarly, strategies at avoiding adjacent segment disease in the lumbar spine include arthroplasty, dynamic fixation, and percutaneous fixation, whereas in the cervical spine the focus has remained on arthroplasty. CONCLUSIONS: Adjacent segment disease and degeneration remain a multifactorial problem with several techniques being developed recently to minimize them. In the future, it is likely that the popularity of these techniques will be dependent on the long-term results, which are currently unavailable.The spine journal: official journal of the North American Spine Society 02/2013; · 2.90 Impact Factor
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ABSTRACT: Adjacent segment disease has become a common topic in spine surgery circles because of the significant increase in fusion surgery in recent years and the development of motion preservation technologies that theoretically should lead to a decrease in this pathology. The purpose of this review is to organize the evidence available in the current literature on this subject. FOR THIS LITERATURE REVIEW, A SEARCH WAS CONDUCTED IN PUBMED WITH THE FOLLOWING KEYWORDS: adjacent segment degeneration and disease. Selection, review, and analysis of the literature were completed according to level of evidence. The PubMed search identified 850 articles, from which 41 articles were selected and reviewed. The incidence of adjacent segment disease in the cervical spine is close to 3% without a significant statistical difference between surgical techniques (fusion vs arthroplasty). Authors report the incidence of adjacent segment disease in the lumbar spine to range from 2% to 14%. Damage to the posterior ligamentous complex and sagittal imbalances are important risk factors for both degeneration and disease. Insufficient evidence exists at this point to support the idea that total disc arthroplasty is superior to fusion procedures in minimizing the incidence of adjacent segment disease. The etiology is most likely multifactorial but it is becoming abundantly clear that adjacent segment disease is not caused by motion segment fusion alone. Fusion plus the presence of abnormal end-fusion alignment appears to be a major factor in creating end-fusion stresses that result in adjacent segment degeneration and subsequent disease. The data presented cast further doubt on previously established rationales for total disc arthroplasty, at least with regard to the effect of total disc arthroplasty on adjacent segment degeneration pathology.Ochsner Journal 01/2014; 14(1):78-83.