164S Proceedings of the NASS 26th Annual Meeting / The Spine Journal 11 (2011) 1S–173S

P90. Is Congenital Stenosis of the Cervical Spine Associated with

Congenital Lumbar Stenosis? An Anatomic Study of 410 Human

Cadaveric Spines

Nicholas Ahn, MD1, Navkirat Bajwa2, Jason Toy, MD2; 1University

Hospital of Cleveland, Department of Orthopedic Surgery, Cleveland, OH,

USA; 2Cleveland, OH, USA

BACKGROUND CONTEXT: Congenital stenosis (CS) of the cervical

and lumbar spine occur when the bony anatomy of the spinal canal is small-

er than expected in the general population. This may predispose an individ-

ual to symptomatic neural compression. While tandem stenosis is known to

occur in 25% of individuals with symptomatic neural compression in one

region, it is not known whether this relationship is due to an increased risk

of degenerative disease in these individuals, or whether this finding is due to

the tandem presence of a congenitally small cervical and lumbar canal.

PURPOSE: To determine if the presence of congential stenosis in the cer-

vical spine is associated with congenital stenosis in the lumbar spine.

STUDY DESIGN/SETTING: A cross-sectional study of adult skeletal

specimens from the Hamann Todd Collection in the Cleveland Museum

of Natural History was performed.

PATIENT SAMPLE: 410 adult skeletal specimens from the Hamann Todd

Collection in the Cleveland Museum of Natural History were selected.

OUTCOME MEASURES: Canal area at each level was also calculated

using a formula that was verfied by computerized measurements. A stan-

dard distribution for each level was created, and values that were �2SD

below mean were considered as being congenitally stenotic for each cervi-

cal and lumbar level.

METHODS: 410 adult skeletal specimens from the Hamann Todd Collec-

tion in the Cleveland Museum of Natural History were selected. Canal area

at each level was also calculated using a formula that was verified by com-

puterized measurements. A standard distribution for each level was cre-

ated, and values that were -2SD below mean were considered as being

congenitally stenotic for each cervical and lumbar level. Linear regression

analysis was used to determine the association between the additive canal

area at all levels in the cervical spine and lumbar spine; and to determine

the association between the number of CS levels in the cervical and lumbar

spine. Logistic regression was used to calculate odds ratios for CS in one

area if CS was present in the other. All regressions were performed correct-

ing for confounding factors of age, sex, and race.

RESULTS: Apositive associationwas found between the additive area of all

cervical and lumbar levels (K50.65, p!.01). A positive association was also

found between the number of CS cervical and lumbar levels (K50.20,

p!.01). Log regression also demonstrated a significant association between

CS in the cervical and lumbar spine with an odds ratio of 0.2 (p!.05).

CONCLUSIONS: Based on our study of a large population of adult skel-

etal specimens, it appears that CS of the cervical spine is associated with

CS of the lumbar spine. Thus, the presence of tandem stenosis appears to

be, at least in part, related to the tandem presence of a congenitally small

cervical and lumbar canal.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.392

P91. Augmentation of Spinal Fusion with Intermittent PTH (1-34)

in an Ovariectomized Rat Posterolateral Spinal Fusion Model

with Iliac Crest Bone Graft

Huilin Yang, MD, PhD1, Qiu Zhijie, MD1, Molly Ebraheim, BS2,

Sohaib Hashmi, BS2, Miguel A. Linares Jr., BS2, Mustafa H. Khan, MD2,

Jiayong Liu, MD1,2; 1Department of Orthopaedic Surgery, The First

Affiliated Hospital of Suzhou University, Suzhou, China; 2Department of

Orthopaedic Surgery, University of Toledo Medical Center, Toledo, OH,

USA

BACKGROUND CONTEXT: 5% to 40% of lumbar fusions result in fail-

ure despite current technology. Parathyroid hormone (PTH) shows

All referenced figures and tables will be available at the Annual Mee

significant anabolic effects when administered intermittently. Recent stud-

ies have demonstrated that intermittent PTH enhances osteogenesis and

increases mechanical strength during fracture healing in normal rats. How-

ever, there has been little research done on intermittent PTH administration

postoperatively for spinal fusion, especially in cases of osteoporosis.

PURPOSE: The current study was designed totest the hypothesis that in-

termittent administration of parathyroid hormone (PTH) improves spinal

fusion outcomes in the ovariectomized female Sprague-Dawley rat pos-

terolateral spinal fusion model.

STUDY DESIGN/SETTING: Randomized controlled trial.

METHODS: Ten-week-old SPF scale female Sprague-Dawley rats were

ovariectomizedand underwent a bilateral posterolateral L4-5 spine fusion

procedure by wiltse approach. After six weeks, the graft material became

a morselized auto-iliac crest bone graft.The animals were divided into 2

groups, each containing 18 animals. Starting on postoperative day 0, the

experimental group received daily subcutaneous injections of recombinant

PTH (1–34) at a dose of 30 mg/kg/day. The control group received a subcu-

taneous injection of normal saline at a dose of 30 mg/kg/day. Nine rats

from each group were killed and samples were harvested for investigation.

Four to six weeks after the samples were harvested, L4-5 vertebral seg-

ments were removed and analyzed by means of manual bending, X ray,

Micro-CT and histomorphometry. Serum bone metabolism markers (OC,

NTX) were also analyzed.

RESULTS: At four weeks time, manual palpation identified fusion in two

of the nine animals from the control group, versus five of the nine animals

in the PTH group. At six weeks, five of the nine (control) animals, versus

eight of the nine (PTH) animals were identified to have fusion by means of

manual palpation (p!.05). A radiographic scoring system of the PTH

group resulted in an average score of 2.03 and 3.66 at four and six weeks

respectively. In contrast, correspondencescores of the control group were

1.45 and 2.56 (p!.05 and p!.01). The Micro-CT showed that the contin-

uous fusion mass between the L4-5 transverse processes of the experimen-

tal group was larger than that of the controls. Additionally, the fusion area

was significantly different in both the cross section and coronal section.

The parameter of Fusion bone mass at L4-5 was also shown to be im-

proved in the PTH group by Micro-CT analysis (p!.01 or p!.05). Histo-

logical analysis of the experimental group at four weeks showed new

mature bone and trabecular bone at the fusion site as well as in the marrow

cavity. In contrast, there was less bone formed in the control group which

was mainly composed of cartilaginous and fibrosis like tissue histologi-

cally. The experimental group showed a larger fusion callus with complete

and thick cortical bone between L4-5 transverse processes; connected tra-

becular bone was seen enclosed by the marrow cavity. The trabecular and

cortical bone were thin in the control group. The histomorphology showed

a significant difference in the mineral apposition rate (MAR) between

groups at four weeks and six weeks (p!.01 and p!.05). Serum OC levels

were significantly higher in the PTH group than in the control group during

two separate times that it was analyzed (p!.05). The CTX levels in the

PTH group were higher than in the control group at four weeks (p!0.05).

CONCLUSIONS: Intermittent treatment with low dose PTH (1-34) aug-

ments posterolateral spine fusion with auto-iliac bone graft in ovariecto-

mized female Sprague-Dawley rats. PTH (1-34) administered

intermittently enhanced the quantity and quality of the fusion callus and

reduces healing time of spinal fusion bone grafts.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2011.08.393

P92. Complication Rates Utilizing rhBMP-2 for Lumbar

Posterolateral Fusions

Martin Hoffmann, MD, Clifford B. Jones, MD; Grand Rapids, MI, USA

BACKGROUND CONTEXT: rhBMP-2 (INFUSE) has been utilized off-

label for lumbar posterolateral fusions for many years. Many series have

demonstrated predictable healing rates and reoperations.

ting and will be included with the post-meeting online content.