43SProceedings of the NASS 24th Annual Meeting / The Spine Journal 9 (2009) 1S-205S

segment desgeneration. Postoperative cervical kyphosis has been reported

after arthroplasty using nonconstrained cervical artificial discs.

PURPOSE: This was to investigate the time-course of radiographic changes

in the cervical ROM and sagittal alignment after C-TDR using a semicon-

strained Prodisc-C artificial disc (Synthes Spine, Paoli, PA, USA).

STUDY DESIGN/SETTING: This was a retrospective clinical study with

a follow-up of more than 2 years.

PATIENT SAMPLE: Eighteen patients with C5–6 C-TDR using the Pro-

disc-C were followed up for average 27 months. All data from ProDisc-C

arthroplasty were compared with the results from 22 patients undergoing

C5–6 interbody fusion using a Solis cage (Stryker Howmedica GmbH,

Mulheim, Germany), who were followed up for average 25 months.

OUTCOME MEASURES: Raiographic cervical ROM and sagittal align-

ment were measured using quantitative measurement analysis software in

a picture archiving and communication system workstation (Centricity 3.0,

General Electrics Medical Systems, Milwaukee, WI, USA).

METHODS: Cervical neutral and flexion–extension lateral X-ray images

were obtained before and at 1 and 3 months after surgery for ‘early phase’

observations and at the last follow-up for ‘late phase’ observation. Seg-

mental ROM values in the operated, upper and lower adjacent segments

were measured. For whole neck motion, ROM for C2–7 was also mea-

sured. The percentage contributions of ROM at functional and adjacent

segments to whole neck motion were calculated. For evaluating sagittal

alignment, Cobb angles of C2–7 and C5–6 segments were measured.

RESULTS: In the ProDisc-C group, C2–7 and C5–6 ROM values signifi-

cantly decreased at the early phase after surgery and returned to preoperative

levels at the late phase. Both upper and lower adjacent segments showed sig-

nificantly decreased ROM measures at the acute phase after surgery and re-

turned to the preoperative values at the late phase. In terms of contributions to

whole neck motion, the ROM values of the functional and adjacent segments

did not show any significant change compared with the preoperative value. In

the cage group, C2–7 ROM was also significantly decreased at the early

phase after surgery and returned to preoperative levels at the late phase. Both

upper and lower adjacent segments showed significantly increased ROM

values and percentage contributions to whole neck motion at the early and

late phases. Sagittal alignment of the whole cervical spine became signifi-

cantly more lordotic at late phase in the ProDisc-C group. The C5–6 Cobb

angle became significantly lordotic in the ProDisc-C group, whereas there

was no significant change in C5–6 Cobb angle in the cage group.

CONCLUSIONS: In the early phase after ProDisc-C replacement, the

ROM of the entire neck as well as functional and adjacent segments

decreased but, at the late phase, they returned to the preoperative state.

Contributions of functional and adjacent segments to whole neck motion

were not changed after ProDisc-C replacement. Adjacent segmental mo-

tion could be saved by ProDisc-C replacement instead of interbody fusion

using a cage. Segmental degenerative kyphosis was significantly corrected

by ProDisc-C replacement.

FDA DEVICE/DRUG STATUS: ProDisc-C: Approved for this indica-

tion; Solis Cage: Approved for this indication.

doi: 10.1016/j.spinee.2009.08.102

82. Single-Site Comparison of One and Two Level Mobi-C Cervical

Disc Replacement and Anterior Cervical Discectomy and Fusion

Control: Preliminary Outcomes of Investigational FDA Trial

Rachel Hoffman1, Gregory Hoffman, MD2; 1University of Notre Dame,

Notre Dame, IN, USA; 2Orthopaedics Northeast, Fort Wayne, IN, USA

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion is

considered to be the standard of care in treatment of patients suffering

from axial neck pain, myelopathy and radiculopathy associated with de-

generative cervical disc disease. Due to the restrictive nature of ACDF,

load transfers on discs adjacent to the operative site tend to increase

thereby potentially increasing the rate of degeneration at those levels.

Cervical disc replacement seeks to decrease pain and resolve neurological

deficits while maintaining normal cervical mobility. It is expected that by

preserving natural cervical movement at the surgical site, surrounding

levels will not exhibit increased degenerative symptoms.

PURPOSE: To compare various outcome measures amongst patients who

underwent either a disc arthroplasty procedure involving the Mobi-C

prosthesis or an anterior cervical discectomy and fusion procedure.

STUDY DESIGN/SETTING: A prospective, single-site, 2-to-1 randomi-

zation clinical study of patients enrolled in the Mobi-C cervical disc pros-

thesis FDA trial.

PATIENT SAMPLE: Patients who have undergone a one or two-level

surgical procedure utilizing either the Mobi-C investigational cervical

device or an ACDF control.

OUTCOME MEASURES: Investigational aims are to compare baseline,

6 weeks, 3, 6, 12 and 18 month post-operative outcomes between the con-

trol and investigational treatment groups. Primary endpoints including neu-

rological status, NDI, device status, incidence of reoperation and major

complications as well as secondary endpoints including work status, use

of pain medication, VAS, overall patient satisfaction and incidence of dys-

phagia are to be assessed. From a surgical standpoint, overall blood loss,

duration of hospitalization and surgery length are to be evaluated.

METHODS: A total of 65 patients from one of the Mobi-C IDE sites were

included in this study. Patient information from both control ACDF (n521)

and Mobi-C (n544) participants was prospectively gathered at baseline, 6

weeks and 3, 6, 12 and 18 month follow-up points. Patient data from primary

and secondary endpoints as well as surgical details was statistically analyzed

in order to yield comparative results assessing study objectives.

RESULTS: The results of this study indicated significant differences in

NDI scores at a number of follow-up points suggesting that Mobi-C pa-

tients had significantly lower NDI scores at those times. Mobi-C patients

also showed a significant difference in motor examination scores early-

on. Significant differences were also found favoring Mobi-C patients con-

cerning appendicular and axial VAS at several post-operative time points.

Mobi-C patients had lower dysphagia scores 6 weeks through 12 months

post-operatively. An overall patient satisfaction questionnaire revealed that

Mobi-C patients were more satisfied with the outcome of their surgery. A

higher percentage of disc arthroplasty patients returned to work earlier than

fusion patients. Surgically, fusion procedures took significantly less time

than disc arthroplasty procedures.

CONCLUSIONS: The results of this study suggest that the Mobi-C cervical

disc replacement device offers comparable outcomes to those of anterior cer-

vical discectomy and fusion. Resulting data favored the Mobi-C prosthesis in

regards to severity of dysphagia, return to work status and patient satisfac-

tion. The long-term success of the Mobi-C disc arthroplasty procedure will

require further investigation and more extensive outcome studies.

FDA DEVICE/DRUG STATUS: LDR Mobi-C Cervical Disc Prosthesis:

Investigational/Not approved.

doi: 10.1016/j.spinee.2009.08.103

83. Global Variations in the Clinical Presentation of Patients with

Cervical Spondylotic Myelopathy: Initial Results of the AOSpine

International Multicenter Prospective Cohort Study

Michael Fehlings, MD, PhD, FRCS, FRCSC1, Branko Kopjar, MD, PhD2,

Paul Arnold, MD3, Helton Defino, MD4, Shashank Kale, MD5,

Mehmet Zileli, MD6, Qiang Zhou, MD7, Giuseppe Barbagallo, MD8,

Ronald Bartels, MD9; 1University of Toronto, Toronto, Ontario, Canada;2Seattle, WA, USA; 3University of Kansas, Kansas City, KS, USA;4Ribeirao Preto, Brazil; 5New Delhi, India; 6Izmir, Turkey; 7ChongQing,

China; 8Catania, Italy; 9Nijmegen, Netherlands

BACKGROUND CONTEXT: Patients with cervical spondylotic myelop-

athy (CSM) may present with different severity and clinical symptoms at

the time of surgical treatment in different regions of the world due to

variations in access to health care, differences in tolerance of symptoms,

differing models of service delivery and differences in clinical treatment

protocols. To date, there are no data that describe these variations and their

impact on surgical approaches and patient outcomes.