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

surgery, and smoking history were not significantly correlated to treatment

recommendations whether for or against spinal fusion based on discogram

results. The number of discogram levels and diagnosis were significant

predictors of the treatment recommendations based. Degenerative Disc

Disease the most common diagnoses in patients recommended and not rec-

ommended for surgery. Chi-square test revealed a significant relationship

between the number of discogram levels and recommendation for surgery.

There were more 5 level discograms (8 vs 3) in patients surgery was rec-

ommended against and more 3 level discograms (61 vs 16) in patients

where surgery was recommended. Although the mean age and mean num-

ber of discogram levels did not differ significantly between the two groups

(surgery recommended vs not recommended).

CONCLUSIONS: Discography can be a useful tool to identify patients

who are not good candidates for surgery. In this series, a significant per-

centage of patients had surgery not recommended based upon the

discograms.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2009.08.022

17. The Utility of Repeated Post-Operative Radiographs Following

Lumbar Instrumented Fusion?

Takayuki Yamashita, MD1, Michael Steinmetz, MD2, Thomas Mroz, MD1;1Cleveland Clinic Foundation, Cleveland, OH, USA; 2Cleveland, OH, USA

BACKGROUND CONTEXT: Routine postoperative anteroposterior and

lateral radiographs may be an inconvenience to patients and expose them

to additional and potentially unnecessary radiation, and adds considerable

cost. No standard, however, exists to define when patients should obtain

radiographs following lumbar instrumented fusion.

PURPOSE: To determine the utility of repeated post-operative radio-

graphs following lumbar instrumented fusion and setup an algorithm to de-

termine how often and when these radiographs should be taken.

STUDY DESIGN/SETTING: Retrospective chart review.

PATIENT SAMPLE: The patients who underwent a single or multilevel

instrumented lumbar fusion (L1-S1) with at least 6 month follow-up were

investigated. All procedures were performed by 4 surgeons at the same

institution.

OUTCOME MEASURES: Plain radiographs were reviewed and abnor-

mal post operative findings were documented.

METHODS: At each time point, it was noted if the patient had plain ra-

diographs taken and if they presented with onset of new symptoms or de-

terioration of the previous symptoms. We also recorded whether the patient

underwent any therapeutic intervention based on the results of their plain

radiographs. The relation between abnormal findings and the time after

surgery, and the relation between abnormal findings and symptom were in-

vestigated. The Fisher’s exact test was used to analyze the categorical data.

RESULTS: Eighty-three (83) patients (30 males, 53 females) were identi-

fied with a mean age of 53 years (range, 20-87). The mean follow-up pe-

riod was 18 months (range, 6-59). Plain radiographs were taken at 324

visits. At 18 visits, abnormal findings on plain radiographs were found

in 14 patients, including pseudarthrosis (n59), adjacent segment disease

(1 level above fusion (n52), 2 level above fusion (n51)), and delayed

union (n52). In the patients who presented with onset of new symptoms

or deterioration of the previous symptoms, abnormal findings were found

at 11 (19%) of 57 visits. In the patients without these symptoms (asymp-

tomatic patients), abnormal findings were found at 7 (0.026%) of 267 visits

and the probability of an abnormal finding was significantly lower

(P!0.001). No treatment plan change was required in these patients. At

the 3 month follow-up or earlier, abnormal findings were found at 1

(0.007%) of 142 visits, and at 17 (0.093%) of 182 visits at the 6 month

follow-up or later. The probability of an abnormal finding was significantly

lower at the 6 month follow-up or later (P!0.001). A total of 10 patients

were diagnosed with pseudarthrosis. In 8 (80%) of them, it was detected

based on the result of plain radiographs by the 12 month follow-up.

CONCLUSIONS: The probability of abnormality detected on radiographs

was significantly low before the 6 month follow-up and in the asymptom-

atic patients. This study suggests that plain radiographs should be taken as

clinically indicated rather than routinely before the 6 month follow-up. Af-

ter the 6 month follow-up, plain radiographs would be obtained when pseu-

darthrosis is suspected in the patients. The vast majority of asymptomatic

patients do not require routine lumbar radiographs. Plain radiographs

should be taken at an appropriate time (after the 6 month follow-up) and

in symptomatic patients to avoid unnecessary radiation exposure and cost.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2009.08.023

18. Relationship Between EMG Findings and Changes in Extremity

and Axial Pain in Patients Undergoing Surgical Decompression

Procedures

Nayan Patel, MD1, Jason Marchetti, MD1, Sunita Verma-Kurvari, PhD2,

Donna D. Ohnmeiss, PhD2; 1Texas Back Institute, Plano, TX, USA; 2Texas

Back Institute Research Foundation, Plano, TX, USA

BACKGROUND CONTEXT: Decompressive surgery including discec-

tomy, decompression and/or fusion is routinely performed to relieve symp-

toms in patients with degenerative spinal conditions. In such patients, pain

may be axial or radiating into the extremities due to nerve root compression.

Electrodiagnostics, specifically electromyography (EMG), is commonly

used to investigate paraspinal and peripheral muscle activity and the condi-

tion/integrity of the neuronal connection in the assessment of extremity pain.

PURPOSE: The purpose of this study was to investigate the relationship

between EMG findings and changes in extremity and axial pain following

surgical decompression procedures.

STUDY DESIGN/SETTING: This study was based on a retrospective

chart review of patients treated at a multi-site spine-specialty clinic. Out-

come data from patients that did not have minimum one-year follow-up

were collected through a mailed questionnaire.

PATIENT SAMPLE: The study population included 55 EMG patients

who underwent EMG no more than six months prior to decompressive spi-

nal surgery. These included 16 cervical and 39 lumbar patients.

OUTCOME MEASURES: The primary clinical outcome measures used

were visual analog scales (VAS) separately assessing extremity and axial

pain, each on a zero to ten scale.

METHODS: EMGs were classified as positive (n527), negative (n520), or

equivocal (n58; due to the low number, this group was excluded from the anal-

ysis). Patients whose extremity VAS score was greater than their axial score

were considered to have primarily extremity pain. If the axial score was greater,

they were classified as having primarily axial pain. If there was less than one

point difference in the axial and extremity scores, the patient was classified

as having neither primarily axial or extremity pain. The mean percentage im-

provement from pre- to final post-operative follow-up VAS scores were calcu-

lated. These were compared in the positive and negative EMG groups.

RESULTS: Among patients with primarily extremity pain, those with

a positive EMG had 78.1% improvement at follow-up. This was signifi-

cantly greater than the 20.0% improvement noted in extremity pain pa-

tients with a negative EMG (p!0.05; t-test). Among patients classified

as primarily having axial pain, there was no significant difference in the

percentage improvement in axial pain when comparing patients with pos-

itive to those with negative EMGs (51.4% vs. 51.8%; pO0.4).

CONCLUSIONS: Results of this study found that among patients with pri-

marily extremity pain, those with a positive EMG had significantly greater

improvement in pain scores after decompressive surgery than those with neg-

ative EMGs. Further investigation into the relationship of EMG findings in

extremity and axial pain patients is warranted in larger populations.

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

any applicable devices or drugs.

doi: 10.1016/j.spinee.2009.08.024