Sagittal Cervical Alignment After Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion

Department of Orthopaedic Surgery, The University of Pennsylvania, Philadelphia, USA.
Spine (Impact Factor: 2.3). 09/2009; 34(19):2001-7. DOI: 10.1097/BRS.0b013e3181b03fe6
Source: PubMed


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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    • "Often , the primary aim of cervical surgery is to lessen or correct the deformities [13] [14] [15] [16] [17]. Following cervical fusion , patients have been shown to have areas of either increased or decreased cervical lordosis, therefore assessing cervical posture has been advocated for a standard pre-and post-surgical assessment [13] [14] [15]. "
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    ABSTRACT: Objective: The purposes of this study were to determine the reliability and validity of two clinical measurements of cervical lordosis and to compare these measurements of individuals with cervical spine symptoms to those of asymptomatic individuals. Methods: Fifty-seven participants were recruited for the study: 18 following cervical fusion, 20 with neck pain and no surgery, and 19 with no neck pain. Cervical lordosis was measured using a flexible ruler (flexirule) and a modified bubble inclinometer. Intertester and intratester reliability were calculated for both methods. Validity was assessed by correlating measurements taken using both methods to Cobb angles between C2 and C7 on lateral view radiography of the participants in the cervical fusion and the neck pain groups. Results: Intraclass correlation coefficients (ICCs) revealed good intratester reliability for both methods. Intertester reliability was fair for the flexirule method but good for the inclinometer method. Pearson correlations with radiographic angles were poor for both methods. ANOVAs showed no significant difference in cervical lordosis measurements between asymptomatic and symptomatic groups. Conclusion: Although both the flexirule and inclinometer methods are reliable, neither method correlated with the Cobb angle on the radiography, suggesting these methods may measure different aspects of cervical spine alignment.
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    • "The absence of such bridges or the presence of an anterior–posterior discontinuation was classified as nonfusion [37]. Cervical spine alignment was evaluated by sagittal segmental alignment (SSA) and sagittal alignment of the cervical spine (SACS) on lateral radiographs, preoperatively, 6 months postoperatively, and at the last follow-up (Fig. 1) [1, 15, 16]. "
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