fracture, and 6 congenital anomalies) and the remaining 206 were retro-

spectively reviewed.

OUTCOME MEASURES: Using a digital imaging system, degeneration,

listhesis, and alignment were assessed. Degeneration was graded on a mod-

ified Kelgren scale (0–4 point scale with 0 being no signs of degeneration

and 4 being severe narrowing, sclerosis, and osteophyte formation). Listhe-

sis was measured in millimeters. Alignment was measured as the angle

subtended by the lines parallel to the inferior end plate of C2 and the

superior end plate of C7. Dynamic radiographs were evaluated for any

change in listhesis greater than or equal to 2 mm.

METHODS: A-priori analysis determined the intra-observer reliability

in measurement of 1) degeneration and 2) flexion–extension angle for

the three observers. Radiographs were examined concurrently by a spine

surgeon, musculoskeletal radiologist, and orthopedics chief resident.

RESULTS: The intra-observer reliability of degeneration measurement

was good to excellent (ICC 0.67 to 0.95). Intra-observer reliability of flex-

ion–extension angle measurement was excellent (ICC 0.97). Degenerative

changes were most advanced at C5/C6 (average modified Kelgren,

mK51.7) followed by C6/C7 (mK51.3), C4/C5 (mK51.0), C3/C4

(mK50.5), C2/C3 (mK50.2). The mean flexion–extension arc of motion

was 42� (range 9� to 95�, standard deviation 15�). Two patients (1%)

had spondylolisthesis on flexion or extension radiographs not visualized

on neutral lateral radiographs. These were extension retrolistheses (2, 3

mm) with normal alignment on neutral lateral radiographs. Additionally,

6 patients (3%) with listhesis on the neutral lateral view were found to have

changes between flexion and extension (2–4 mm). A subsequent review of

these patients’ charts revealed no change in conservative management and

no decision to go to surgery based solely on information of the flexion-ex-

tension radiographs.

CONCLUSIONS: Given that the flexion-extension radiographs revealed

a small percentage of abnormalities and did not change management, their

utility was low in our patient population. This data, in conjunction with the

extra cost and radiation exposure associated with additional views, leads

us to no longer regard dynamic radiographs as a useful part of the initial

imaging for the patient with degenerative cervical conditions.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2006.06.385

5:20

31. Evaluation of the Utility of Dynamic Radiographs in the

Evaluation of the Degenerative Lumbar Spine

Qusai Hammori, MD1, Ahmad Alqaqa, MD2, Andrew Haims, MD1,

Jonathan Grauer, MD1; 1Yale University, New Haven, CT, USA;2University of Jordan, Amman, Jordan

BACKGROUND CONTEXT: Most physicians obtain standing antero-

posterior (AP) and lateral radiographs as base studies in the evaluation

of patients presenting with lumbar complaints. The potential role of

dynamic films in this population has not been established.

PURPOSE: To assess the utility of dynamic radiographs in the evaluation

of the degenerative lumbar spine.

STUDY DESIGN/SETTING: It has been the senior surgeon authors’

practice to obtain standing AP, lateral, flexion, and extension radiographs

in the initial evaluation of patients presenting to a spine practice with lum-

bar complaints if films had not been previously obtained. In this study we

retrospectivly reviewed a series of consecutive patients who visited the

senior surgeon authors’ practice.

PATIENT SAMPLE: Three hundred and ninety consecutive patients

who visited our clinic between September 2003 and December 2004 with

lumbar axial or radicular complaints.

OUTCOME MEASURES: The AP films were assessed for osteoarthritis

and scoliosis. The lateral films were assessed for osteoarthritis, antero- or

retrolisthesis, pars defect, and lumbarization or sacralization of vertebrae.

Flexion/extension films were then assessed. They were evaluated for any

additional information or any change in the amount of listhesis. Osteoar-

thritis was graded as per Kellgren’s classification (a 0–4 point scale that

reflects the severity of osteoarthritis).

METHODS: After assessment of the AP and lateral radiograph, flexion/

extension views were evaluated to determine if additional information

was obtained and, if so, whether this altered the path of treatment recom-

mended. Spondylolisthesis and/or change in spondylolisthesis was noted

if a change of 2 mm or more was appreciated. Fifty films were blindly

re-reviewed to assess intraobserver variability.

RESULTS: Of the 390 series of radiographs reviewed, only 2 had new

findings seen on dynamic films not appreciated on the AP and lateral films.

One of these was a L3-L4 anterolisthesis of 3 mm with flexion, and the

other was a L5-S1 retrolisthesis of 4 mm with extension. Fifteen additional

series of radiographs were noted to have a change in the amount of listhe-

sis on the dynamic films compared with the lateral films. Of these, 5 were

changes in the amount of retrolisthesis and 11 were changes in the amount

of anterolisthesis (one shared among both groups). These changes in listhe-

sis ranged from 2–5 mm. The change in anterolisthesis on flexion exten-

sion did not result in change in the Meyerding grade of any of the

anterolisthesis. A subsequent review of these patients’ charts revealed no

change in conservative management and no decision to go to surgery based

solely on information of the flexion-extension radiographs.

CONCLUSIONS: We did not appreciate significant utility of obtaining

dynamic radiographs in addition to standing AP and lateral lumbar images

in the initial evaluation of patients presenting with lumbar complaints. Al-

though there may certainly be a role for this imaging in the preoperative

setting, we did not see changes in initial management of this population.

In addition to cost, there is additional radiation associated with obtaining

these extra images. After review of this data, we have stopped obtaining

dynamic radiographs during the initial evaluation of patients presenting

with degenerative lumbar conditions.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2006.06.384

Wednesday, September 27, 20065:44–6:44 PM

Special Interest Poster Presentation 1: LumbarSpine TDR: The Charite Experience

5:44

32. Revision and Explantation Strategies Involving the Charite

Artificial Disc Replacement

John Regan, MD1, Scott Leary, MD2, Willis Wagner, MD3, Todd Lanman,

MD3; 1West Coast Spine Institute, Beverly Hills, CA, USA; 2The Spine

Center at Century City Doctors Hospital, Los Angeles, CA, USA;3Cedars-Sinai Medical Center, Los Angeles, CA, USA

BACKGROUND CONTEXT: The FDA has recently approved total disc

replacement in the lumbar spine with the Charite Artificial Disc. Although

the majority of procedures result in a satisfactory result, a small percentage

of cases are unsuccessful and require revision. We analyzed 15 consecutive

cases referred to the first author for revision surgery.

PURPOSE: The purpose of this study was to characterize the etiology and

strategies utilized when a revision or explantation procedure is necessary

after a failure of lumbar total disc replacement with the Charite Artificial

Disc.

STUDY DESIGN/SETTING: Retrospective chart review.

PATIENT SAMPLE: 15 consecutive lumbar arthroplasty patients requir-

ing revision over a 4-year period.

OUTCOME MEASURES: N/A.

15SProceedings of the NASS 21st Annual Meeting / The Spine Journal 6 (2006) 1S–161S

METHODS: A retrospective analysis of 15 consecutive cases over a 4-

year period was performed. Each case was a primary revision or explanta-

tion procedure involving a Charite intervertebral prosthesis. Evaluation of

the original indications and technical aspects of the initial implantation

were analyzed as well as surgical technique and results of implant revision

procedures.

RESULTS: Seven of 15 initial cases were single-level implants

(L5-S155, L4-552) and 8 cases were performed at two levels (L4-5,

L5-S1). Twelve (12) of 15 cases required removal of the implant and con-

version to a 360 degree fusion. In the remaining three cases, primary revi-

sion of the implant was performed with 2 converted to smaller implants

and in 1 case, repositioning after a fall 6 weeks after the original surgery.

Early revision was performed in 7 cases (7–10 days), all as a result of im-

plant displacement. Eight late revisions were performed from 6 weeks to 2

years. Technical errors during initial implant surgery were felt to be the

cause of implant dislocation or failure in 10 cases with 9 resulting from

use of an implant too large or anterior malposition of the implant. In 4

cases the artificial disc procedure was contraindicated on the basis of

end stage facet disease or spondylolisthesis. Implant revision strategies

were determined by the length of time from the original surgery and the

location of the implant. All early revisions from 7 to 10 days were man-

aged using the original retroperitoneal incision. Late revisions required

a variety of approaches including right paramedian retroperitoneal (3),

transperitoneal (2), and extreme far lateral transpsoas (3). Stenting of the

ureter was utilized for the L4-5 approaches. Preoperative vascular studies

were performed in cases of late dislocation. There were no vascular, ureter,

or neurologic injuries and no blood transfusions were required.

CONCLUSIONS: Factors that contribute to unsuccessful total disc

replacement are primarily performing the procedure in contraindicated

patients and technical errors of original implantation, mostly an implant

positioned too anterior or using an implant that is too large. In a series

of 15 patients requiring Charite Artificial Disc removal or revision, surgery

was successful in all cases without serious complications of vascular, ure-

ter, or neurologic injury. As the number of total disc replacement proce-

dures increases, surgeons will need to be familiar with the issues

resulting in implant failure and the technical strategies needed to safely

revise artificial disc implants.

FDA DEVICE/DRUG STATUS: Charite Artificial Disc (one-level):

Approved for this indication; Charite Artificial Disc (two-level): Not

approved for this indication.

CONFLICT OF INTEREST: Author (JR) Consultant: DePuy Spine.

doi: 10.1016/j.spinee.2006.06.048

5:50

33. Lumbar Arthroplasty versus Anterior Interbody Fusion at

One-Level: Clinical Results at 5-Year Follow-Up From the IDE

Study of the Charite Artificial Disc

Richard D. Guyer, MD1, Robert J. Banco, MD2, Fabien D. Bitan, MD3,

Scott L. Blumenthal, MD1, Andrew Cappucino, MD4, Fred H. Geisler, MD,

PhD5, Stephen Hochschuler, MD1, Richard T. Holt, MD6, Louis G. Jenis,

MD2, Mohammed E. Majd, MD6, Paul C. McAfee, MD7, Bradford

B. Mullin, MD8, John J. Regan, MD9, Noam Stadlan, MD10, Scott

G. Tromanhauser, MD2, Douglas Wong, MD11; 1Texas Back Institute,

Plano, TX, USA; 2Boston Spine Group, Boston, MA, USA; 3Lenox Hill

Hospital, New York, NY, USA; 4Northtown Orthopedics, Lockport, NY,

USA; 5Illinois Neuro-Spine Center, Aurora, IL, USA; 6Spine Surgery PSC,

Louisville, KY, USA; 7St. Joseph Hospital, Towson, MD, USA; 8Central

Ohio Neurological Surgeons, Columbus, OH, USA; 9West Coast Spine

Institute, Beverly Hills, CA, USA; 10Chicago Institute of Neurosurgery and

Neuroresearch, Chicago, IL, USA; 11Panorama Orthopedics, P.C., Golden,

CO, USA

BACKGROUND CONTEXT: Previous presenters and authors have de-

scribed follow-up of various lengths for patients having had lumbar

arthroplasty for the treatment of degenerative disc disease. Follow-up in

these patients has been reported from 6 months to 17 years. Though

long-term follow-up of large single-center patient cohorts is important, on-

ly long-term follow-up of patients enrolled in prospective, randomized,

controlled studies represents Level I data. The IDE study of the Charite Ar-

tificial Disc was the first prospective, randomized, controlled trial studying

lumbar arthroplasty at one level from L4 to S1 compared with fusion. Be-

cause of this, longer-term data from this clinical trial should always be

available ahead of long-term data from other IDE studies. We report the

early 5-year data from this study.

PURPOSE: To determine clinical outcomes in patients with a lumbar total

disc replacement (TDR) vs. patients with lumbar fusion, at one level, with

follow-up to 5 years.

STUDY DESIGN/SETTING: Prospective, multi-center, randomized,

controlled clinical trial.

PATIENT SAMPLE: Patients enrolled in the IDE study of the Charite

Artificial Disc eligible for follow-up post 2 years.

OUTCOME MEASURES: Oswestry Disability Index (ODI), Visual

Analog Scale (VAS) for pain, and Patient Satisfaction.

METHODS: Patients enrolled in the IDE study of the Charite Artificial

Disc were assessed under protocol for clinical outcome using ODI and

VAS clinical outcome measures, and patient satisfaction. Inclusion/Exclu-

sion criteria and all study methodology were previously described by

Blumenthal et al. (Spine 2005). At the time of this writing, there were

35 patients reviewed, though this number is expected to increase signifi-

cantly at the time of presentation. There were 24 patients in the treatment

(TDR) group and 11 in the control group (ALIF with BAK cages and au-

tograft). Assessments were performed at either the 3-year (2), 4-year (14),

or 5-year (19) follow-up interval.

RESULTS: In this cohort of 35 patients, there was no significant differ-

ence between the groups in change in mean ODI scores or VAS scores,

compared with baseline, at the latest follow-up (pO.10). For ODI scores,

there was no significant difference between the groups with respect to

the percentage of patients achieving at least a 25% improvement at all time

points through the latest follow-up vs. baseline. For VAS scores, there was

no significant difference between the groups with respect to the percentage

of patients achieving at least a 20-point improvement at all time points

through the latest follow-up compared with baseline scores (pO.10). There

was no significant difference with respect to patient satisfaction or neuro-

logical status for this specific cohort at the latest follow-up (pO.10).

CONCLUSIONS: Longer-term Level I data are necessary for the contin-

ued evaluation of lumbar arthroplasty, and the authors are committed to

presenting new data as it becomes available. This initial review of the

post-2-year data from the IDE study of the Charite Artificial Disc demon-

strates no statistical difference in key clinical outcome measures for

patients with a total disc replacement vs. fusion.

FDA DEVICE/DRUG STATUS: Charite Artificial Disc: Approved for

this indication; BAK Cage: Approved for this indication.

CONFLICT OF INTEREST: Authors (RDG, RJB, FDB, SLB, AC, RTH,

LGJ, JJR, SGT, DW) Consultant: DePuy Spine.

doi: 10.1016/j.spinee.2006.06.049

5:56

34. A Long-Term Multi-Center Retrospective Study of 226 Patients

With the Charite Artificial Disc: Minimum 10-Year Follow-Up

Thierry David, MD1, Jean-Phillipe Lemaire, MD2, Pierre Moreno, MD3,

Fabien Bitan, MD4; 1Spine Surgey Unit. Polyclinique de Bois-Bernard,

Bois-Bernard, France; 2Point Medical, Dijon, France; 3Polyclinique du

Parc Chirurgie Vertebrale, Toulouse, France; 4Lenox Hill Hospital, New

York, NY, USA

BACKGROUND CONTEXT: The best indications for lumbar total disc

replacement are: in balance with fusion, and in young and active patients

with severe discogenic low back pain. Duration of life and possibilities for

16S Proceedings of the NASS 21st Annual Meeting / The Spine Journal 6 (2006) 1S–161S