114S Proceedings of the NASS 22nd Annual Meeting / The Spine Journal 7 (2007) 1S–163S

STUDY DESIGN/SETTING: Prospective study.

PATIENT SAMPLE: Fourteen consecutive patients with back pain which

originated from pars defects confirmed by oblique radiographs and lido-

caine block as well.

OUTCOME MEASURES: Back pain and functional recovery were as-

sessed by use of the Visual Analog Score (VAS) and Oswestry Disability

Index (ODI), respectively.

METHODS: Between February 2004 and August 2005, 14 consecutive

patients with single level lumbar spondylolysis were treated with pedicle

screw-laminar hook fixation with bone graft. Radiological indications in-

cluded 1) no spondylolisthesis, 2) no instability on dynamic X-ray, 3) hy-

perintensity within the intervertebral disc on sagittal T2-weighted images,

4) no other abnormal findings on MR images. Clinical indications included

1) no improvement in back pain after 6 months of conservative treatment,

2) aggravation of back pain during dynamic motion, 3) early morning back

pain. Before surgery, spondylolysis block was performed with lidocaine.

After posterior midline incision, the spondylolytic defect was exposed

and the granulation tissue was removed. A pilot hole was made through

the pedicle using a microdrill, and a pedicle screw was inserted into the

pedicle. Allograft bone was then placed at the pars interarticularis. A lam-

inar hook was placed in the lower margin of the lamina of the involved ver-

tebra, and connected with a rod to the pedicle screw. Same procedures

were done on the contralateral side. Radiologic fusion of the defects was

confirmed by bridging of bone across the pars on oblique views and

heeling of the pars defect on CT scan.

RESULTS: The patients consisted of 11 males and 3 females, with a mean

age of 26.3 years (range, 20–45 years). The site of pars defects was L5 in

all cases. After surgery, all patients were experienced significant pain re-

lief. During the follow-up period, the mean VAS score decreased from

7.1 to 2.7 (62% decrease), and the mean ODI reduced from 43.1% to

20.3% (53% reduction). There were no complications or instrumentation

failure. Radiographic fusion was achieved in all patients except one (no

required revision arthrodesis).

CONCLUSIONS: Segmental pedicle screw-laminar hook fixation with

bone graft is a simple and safe procedure to repair pars defect in the lumbar

spine. These indications will contribute to the proper patient selection for

surgical repair of symptomatic lumbar spondylolysis.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2007.07.273

P68. Thoracic Pedicle Subtraction Osteotomy for Fixed Sagittal

Deformity: Clinical and Radiographic Outcomes

O’Shaughnessy Brian1, Tim Kuklo, MD, JD2, Benson Yang, MD3,

Tyler Koski, MD3, Stephen Ondra, MD4; 1Northwestern University,

Chicago, IL, USA; 2MO, USA; 3IL, USA; 4Chicago, IL, USA

BACKGROUND CONTEXT: The surgical treatment of fixed sagittal de-

formity in the thoracic spine is a complex problem. We have applied the

recognized technique of pedicle subtraction osteotomy (PSO) in the tho-

racic spine for correction of severe kyphotic deformities.

PURPOSE: The purpose of this study is to analyze our clinical and radio-

graphic results in performing thoracic PSO for the treatment of fixed

sagittal deformity.

STUDY DESIGN/SETTING: Retrospective clinical study.

PATIENT SAMPLE: Fifteen patients (9 males, 6 females) with a mean

age of 55 years (range, 36–81 years) underwent a total of 25 thoracic PSOs.

Mean follow-up was 3.5 years. Etiologies of sagittal deformity were: junc-

tional kyphosis (n55), ankylosing spondylitis (n53), post-traumatic

kyphosis (n52), post-laminectomy kyphosis (n51), degenerative kypho-

scoliosis (n51), and idiopathic kyphoscoliosis (n53).

OUTCOME MEASURES: Radiographic: Fusion, Sagittal Deformity

Correction Clinical: SRS-22 Instrument.

METHODS: All thoracic PSOs were evaluated postoperatively with thin-

cut CT scans. Measurements on 14�36-inch radiographs were performed

preoperatively, immediately postoperatively, and at final follow-up. Func-

tional outcome was ascertained with the SRS-22 instrument.

RESULTS: A total of 25 thoracic PSOs were performed (mean 1.7 PSOs/pa-

tient, range 1–3). The osteotomies were carried out in the proximal thoracic

spine (T2-T4; n56), midthoracic spine (T5-T8; n512), and caudal thoracic

spine (T9-T12; n57). Mean segmental correction at the PSO for all levels

was 14.0 �. Stratified by region of the spine, PSO correction was: T2-T4

(9.5 �), T5-T8 (14.2 �), T9-T12 (20.6 �). Mean thoracic kyphosis (T2-T12

Cobb angle) was improved from 75.7 � to 56.3 � giving a regional correction

of 19.4 �. Global sagittal balance was less reliably restored and 6 (40%) of the

patients subsequently underwent lumbar osteotomies (SPOs n52, PSO n54)

for additional sagittal reorientation. There were no neurological complica-

tions; however there were 3 cases of implant failure (pseudarthrosis n52,

proximal junctional kyphosis n51) requiring revision surgery. Patient satis-

faction was high according to the SRS-22 instrument.

CONCLUSIONS: Thoracic PSO is a powerful technique for the regional

correction of fixed sagittal deformity in the thoracic spine. The extent of cor-

rection is smallest in the proximal thoracic spine and greatest in the caudal

thoracic spine. In patients requiring greater than a 25 � of correction at a single

thoracic level, vertebral column resection may be a better option.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2007.07.274

P69. Cervical Arthroplasty for the Treatment of Symptomatic

Cervical Spondylosis: Initial Outcomes from a Prospective,

Randomized, Multi-center Study

John Regan, MD1, Frank Phillips, MD2, Andrew Cappuccino, MD3,

John DeVine, MD4, Paul McAfee, MD5; 1Beverly Hills, CA, USA; 2Rush

University Medical Center, Chicago, IL, USA; 3Lockport, NY, USA;4Madigan Army Medical Center, Tacoma, WA, USA; 5Towson, MD, USA

BACKGROUND CONTEXT: Cervical arthroplasty is a new treatment

option for cervical radiculopathy or myelopathy resulting from a herniated

disc or spondylosis.

PURPOSE: This study reports preliminary results comparing the Porous

Coated Motion (PCM) arthroplasty to anterior cervical discectomy and

fusion (ACDF).

STUDY DESIGN/SETTING: Results are reported from patients enrolled

in a prospective and randomized study at five sites participating in the US

IDE trial of this device.

PATIENT SAMPLE: Patients between 18 and 65 years old with one-level

symptomatic cervical radiculopathy and/or myelopathy unresponsive to at

least 6 weeks of non-surgical therapy, or experiencing progressive neuro-

logical symptoms, were enrolled. Patients may have had a successful

previous single level ACDF.

OUTCOME MEASURES: Patient outcomes were measured with neck

VAS, arm VAS, and Neck Disability Index (NDI) scores. All complications

and adverse events were recorded.

METHODS: Enrolled patients were randomized to undergo anterior de-

compression and PCM arthroplasty or ACDF (control). Each site enrolled

up to four initial non-randomized ‘‘training’’ PCM cases. All control sur-

geries were performed with structural allograft and anterior plating. At the

five study sites, 15 training, 67 PCM, and 43 control patients of 183 en-

rolled have completed 6 month follow up and 14 training, 40 PCM, and

20 control patients reached 12 month follow-up.

RESULTS: No significant differences in age, height, weight or gender ra-

tio occurred between the PCM ‘‘training’’, PCM, or control groups. Sur-

gery duration differed significantly (p50.001) at 119, 88 and 73 minutes

for the PCM ‘‘training’’, PCM and control groups respectively. Clinical

outcomes for each group are described in the table below. There were

no cases of neurologic deterioration in any of the three groups. Revision

surgery was performed in 1/19, 3/96, and 2/68 patients in the ‘‘training’’,

PCM, and control groups, respectively. Implant migration occurred in 1/96

115SProceedings of the NASS 22nd Annual Meeting / The Spine Journal 7 (2007) 1S–163S

randomized PCM cases. Other complications, including dysphagia and

post operative neck or arm symptoms were comparable between groups.

The mean F/E range of motion at the operated level in the PCM group

was 8.2 degrees preoperatively, and 7.7 degrees at 12 months.

CONCLUSIONS: Cervical arthroplasty with the PCM device is safe and

effective in the short term for the treatment of degenerative cervical radi-

culopathy and myelopathy in patients with up to one level of previous

ACDF surgery. Complications and adverse events were comparable be-

tween treatment groups. When compared to ACDF in a prospective and

randomized fashion, PCM arthroplasty showed a trend towards more rapid

resolution of symptoms within the first 6 weeks of surgery and also to

lower neck pain scores at 12 months post-operatively. Motion of the

operated segment was maintained by the PCM prosthesis.

Table 1

Clinical Outcomes (Training/PCM/Control)

NDI Neck VAS Arm VAS

Baseline

28/28/28 68/70/76 68/72/75

6 Weeks

15/15/20 27/29/40 21/26/32

12 Weeks

14/12/16 31/25/35 22/24/34

26 Weeks

12/11/13 25/27/33 20/24/28

One Year

14/9/15 31/20/32 32/24/31

FDA DEVICE/DRUG STATUS: PCM Artificial Cervical Disc: Investiga-

tional/ Not approved.

doi: 10.1016/j.spinee.2007.07.275

P70. Radiographic Assessment of Standard vs Enhanced Dose BMP-

2 Utilized as Iliac Crest Graft Substitutes in Instrumented Single

Level Lumbar Fusions

James Hardacker, MD1, Jill Richardson, PA-C1, Philip Pryor, MD2;1Carmel, IN, USA; 2The Spine Institute, Carmel, IN, USA

BACKGROUND CONTEXT: rhBMP-2(1.5 mg/cc) has been approved

for anterior lumbar arthrodesis. However, the optimal dosing of rhBMP-

2 for lumbar posterolateral fusion is still under investigation.

PURPOSE: This pilot study was undertaken to evaluate the effectiveness

of two doses of rhBMP-2 as iliac crest graft substitutes in posterolateral

lumbar fusions.

STUDY DESIGN/SETTING: A retrospective review of a consecutive series

of surgical patients receiving two doses of rhBMP-2 placed onto a ceramic car-

rier utilized as substitutes for posterolateral iliac bone graft was conducted.

PATIENT SAMPLE: The population studied was a consecutive series of

retrospectively reviewed patients undergoing lumbar surgery for spondylo-

lithesis, stenosis or spondylosis with herniation receiving different doses of

rhBMP-2 as the primary graft material for arthrodesis.

OUTCOME MEASURES: Radiographs and fine cut CT scans with mul-

tiplanar reconstructions at 6mo, 12mo and 24mo postoperative intervals

were reviewed and graded on a 1–4 scale. Independent patient completion

of visual and analog pain scales, Oswestry disability scores, and social and

work function scores were documented.

METHODS: Single level instrumented posterolateral lumbar fusions were

conducted in a consecutive series and reviewed retrospectively comparing

two doses of rhBMP-2 as iliac crest bone graft replacements. Eighteen pa-

tients received standard dose INFUSE (1.5mg/cc) soaked on a collagen

sponge wrapped around ceramic granules creating a ‘‘fajita’’ placed along

the posterolateral lumbar spine. Local bone and ceramic granules were

added around the fajita graft to approximate the carrier bulking of the

two groups. Twenty patients received enhanced dose AMPLIFY rhBMP-2

(2.0mg/cc) applied to ceramic granules formed into a compressive resistant

matrix and placed along the posterolateral lumbar spine. No augmentation

with any additional bone was applied.We compared fusion rates and out-

come measures in this pilot study utilizing sequential radiographs and fine

cut CT scans of the fusion mass to evaluate the bone formation in the

fusion. A modified fusion grading scale was utilized.

RESULTS: At 24 months, the fusion rate was 95% for enhanced dose

rhBMP-2 patients and 100% for standard dose rhBMP-2 patients and not

statistically different. The only nonunion was in a patient that required

early postoperative irrigation and debridement for infection. Fusion scores

on radiographs and CT scans were statistically delayed at 6 months in the

standard dose versus the enhanced dose of rhBMP-2 but this effect gradu-

ally resolved at one year and completely resolved at 2 yr radiographic and

CT follow up. Outcome measures and pain scores improved in all groups.

No inflammatory reactions occurred with these doses of rhBMP-2.

CONCLUSIONS: Both doses of rhBMP-2 are effective in obtaining pos-

terolateral lumbar fusion with instrumentation at 2 yrs after surgery. How-

ever, the commercially available standard dose of rhBMP-2 used as an iliac

bone graft replacement has significantly poorer posterolateral fusion grad-

ing at 6 month postop radiographs and CT scans when compared to the

enhanced dose rhBMP-2 fusions.

FDA DEVICE/DRUG STATUS: rhBMP-2/INFUSE: Investigational/ Not

approved; rhBMP-2 /AMPLIFY: Investigational/Not approved.

doi: 10.1016/j.spinee.2007.07.276

P71. A New CT Based Classification of Pedicles in Spinal Deformity

John Czerwein, Jr., MD1, Vishal Sarwahi, MD1, Lauren Friend, MD1,

Alok Sharan, MD1, Terry Amaral, MD1, Beverly Thornhill, MD1;1Montefiore Medical Center, Bronx, NY, USA

BACKGROUND CONTEXT: Pedicle morphology can be significantly

altered in the deformed spine, presenting challenges for accurate place-

ment of pedicle screws. Lenke has previously classified pedicles by mor-

phology. Accurate assessment of pedicle morphology is important for

safe pedicle screw placement.

PURPOSE: The purpose of this paper is to 1) find the incidence of abnormal

pedicle morphology based on CT measurements, 2) determine if a correlation

exists between abnormal pedicles and curve size, and 3) determine if a higher

incidence of misplaced pedicle screws occurs in dysmorphic pedicles.

STUDY DESIGN/SETTING: The study was a retrospective, single sur-

geon study. Pedicle morphology was graded by reviewing 42 preoperative

CT scans. 21 post-operative CT scans were reviewed for placement of

screws. Cobb angles on these 21 patients were measured. A correlation

existed between pedicle morphology and screw malposition.

PATIENT SAMPLE: The patient sample used in this study consisted of

31 females and 11 males for a total of 42 patients. 37 patients had idio-

pathic scoliosis, 3 had scheuermann’s kyphosis and 2 had neuromuscular

scoliosis. The average age of the patients was 15.3 years.

OUTCOME MEASURES: 42 pre-operative CT scans were reviewed by

a bone radiologist and spine surgeon and pedicle morphology was classi-

fied using a CT guided pedicle classification. Pre-operative curve magni-

tude was measured using traditional radiographs and Cobb angle

measuring technique. Post-operative CT scan was used to assess malposi-

tion of pedicle screws and direction of cortical perforation.

METHODS: CT scans of 42 spinal deformity patients were reviewed inde-

pendently by a bone radiologist and spine surgeon and pedicle morphology

was classified as: Type A (normal pedicle) - O4 mm diameter, Type B - 2-4

mm, Type C – less than 4 mm in size with no cancellous channel, and Type

D !2 mm. There were 1109 (77.7%) Type A pedicles, Type B 210 (14.7%),

Type C 63 (4.4%), and Type D 46 (3.2%). 21 of the 42 patients pre-operative

Cobb angles were measured and averaged 52(range 45-77) degrees. 21 of the

42 patients post-operative CT scans were reviewed for malposition.

RESULTS: 21 post-operative CT scans were reviewed. There were 431

pedicle screws placed, of which 52 were misplaced (12%). Of the 52 mis-

placed screws 7 were encroached into the lateral recess, 6 breached the an-

terolaeral cortex and 39 were in the costovertebral junction. 57 pedicles

instrumented were dysmorphic or of Type B, C, or D of which 16 pedicle

screws (28%) were misplaced. Of the 16 misplaced, 4 (25%) were Grade B

pedicles, 8 (50%) were Grade C, and 4 (25%) were Grade D. There were

no screws with any neurologic, vascular, or visceral complications. Using