Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S 63S

hospital was shorter in Group 2. Blood loss, duration of analgesia, andICU stay did not differ significantly between the two groups. No complica-tions were encountered in both groups. The magnitude and flexibility of thelumbar/thoracolumbar curves did not differ significantly between the twogroups. Fusion levels were shorter in Group 1 (mean 4.1 versus 5.0, p�.01).The percentage correction of frontal alignment in Group 1 was 74% at 1week post-surgery, 70% at 6 months post-surgery, 68% at latest follow-up. The percentage correction of scoliosis in Group 2 was 71% at 1 weekpost-surgery, 67% at 6 months post-surgery, and 67% at latest follow-up.The correction was not statistically significant between the two groups atall stages. Lumbar lordosis also did not differ between the two groups at allstages. The thoracic curves in Group 1 measured 30 degrees preoperatively,18 degrees 1 week post-surgery, 19 degrees 6 months post-surgery, and 18degrees at latest follow-up. In Group 2, the curves measured 28 degreespreoperatively, 19 degrees at 1 week post-surgery, 18 degrees at 6 months post-surgery, and 17 degrees at latest follow-up. These readings were statisticallynot different between the two groups at various time frames.CONCLUSIONS: Posterior segmental pedicle screw instrumentation is aviable alternative to standard anterior instrumentation in King 1 idiopathicscoliosis. Shorter OR time and hospital stay are the potential benefits ofposterior surgery. Surgical correction of both the frontal and sagittal planedeformity are comparable to anterior instrumentation.DISCLOSURES: FDA device/drug: Moss Miami titanium monoaxial/polyaxial screws. Status: Approved for this indication.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.121

5:52120. The expression of type I, II collagen in intervertebral disc inadolescent idiopathic scoliosisYongxiong He; Nanjing University, Nanjing, Jiangsu, China

BACKGROUND CONTEXT: To quantify the expression of collagen Iand II in the intervertebral disc of adolescent idiopathic scoliosis (AIS)with the aim of determining the role of collagen metabolism in the develop-ment and progression of scoliosis.PURPOSE: To quantify the expression of collagen I and II in the interverte-bral disc of adolescent idiopathic scoliosis (AIS) with the aim of determiningthe role of collagen metabolism in the development and progression ofscoliosis.STUDY DESIGN/SETTING: To quantify the expression of collagen Iand II in intervertebral disc of adolescent idiopathic scoliosis (AIS) withthe aim of determining the role of collagen metabolism in the developmentand progression of scoliosis.PATIENT SAMPLE: There were 17 cases of idiopathic right thoracicscoliosis, including 3 males and 14 females, with the average age 14.3years (range 12–18 years). Cobb angles ranged from 40� to 70�. Twelvepatients with congenital scoliosis (9 males and 3 females, 12.8 years oldon average, range 10 to 16 years) were selected as the control.OUTCOME MEASURES: Specimens of the intervertebral disc from T8to T9 (apex of the curve) obtained during anterior surgery and total RNAwere isolated using Trizal methods. The amplification reaction productswere resolved on 1.0% agarose and analyzed after reverse transcription-polymerase chain reaction (RT-PCR).METHODS: There were 17 cases of idiopathic right thoracic scoliosisincluding 3 males and 14 females, with the average age 14.3 years (range12–18 years). Cobb angles ranged from 40� to 70�. Twelve patients withcongenital scoliosis (9 males and 3 females, 12.8 years old on average, range10 to 16 years) were selected as the control. Specimens of the intervertebraldisc from T8 to T9 (apex of the curve) obtained during anterior surgery andtotal RNA were isolated using Trizal methods. The amplification reactionproducts were resolved on 1.0% agarose and analyzed after RT-PCR.RESULTS: The expression of collagen I and II were significantly decreasedin annulus fibrosus in AIS compared with control and there was even lowerexpression on the concave side compared with that on the convex side. In

scoliotic nucleus pulposus, type II collagen also significantly decreasedwhereas type I collagen was elevated.CONCLUSIONS: The asymmetric expression of collagen I and collagenII indicated the intervertebral disc degeneration of AIS. The collagen metab-olism may have a close relationship with the development of AIS, whichmay be one of the reasons for the development of AIS and probably is animportant factor in the progression of AIS.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.122

5:58121. Adult tethered cord syndrome: review of a series of 60 patientswith analysis of predictive factors of long-term outcomesGabriel Lee, FRACS1, Guillermo Paradiso2, Charles Tator2,Fred Gentili2, Eric Massicotte, MD1, Michael Fehlings, MD, PhD,FRCS(C)3; 1University of Toronto, Toronto, Ontario, Canada; 2TorontoWestern Hospital, Ontario, Canada; 3University of Toronto, TorontoWestern Hospital, Toronto, Ontario, Canada

BACKGROUND CONTEXT: Adult tethered cord syndrome (TCS) con-tinues to pose a significant diagnostic and management challenge. To date,relatively few large clinical studies have been reported. These have shownthat neurosurgical intervention may be associated with highly variableclinical outcomes. Prognostic factors remain poorly understood.PURPOSE: The aim of this study was therefore to elucidate factors whichmay assist in predicting long-term clinical outcomes, in a large populationof adult TCS patients following de-tethering surgery.STUDY DESIGN/SETTING: Retropective chart review of 60 patientswas performed.PATIENT SAMPLE: Sixty patients who underwent de-tethering surgeryat the Toronto Western Hospital between August 1993 and 2004 wereincluded in this study.OUTCOME MEASURES: The electrophysiological records were re-viewed to identify patients with significant intraoperative changes. Surgicaland management complications were noted. In terms of follow-up data,patient outcomes in terms of level of pain, neurological dysfunction (motorand sensory) and bladder function were recorded.METHODS: Patients who underwent de-tethering surgery at the TorontoWestern Hospital between August 1993 and 2004 were identified. Theirclinical charts, operative records and follow-up data were reviewed. Factorspredictive of long-term outcomes were identified.RESULTS: De-tethering procedures were performed in 60 patients (agerange 17–72 years) with TCS of varying aetiologies. These were classifiedas; tight filum terminale (n�29), post-myelomeningocoele repair (n�15),lipomatous malformations (n�9), split cord malformation (SCM, n�4) andarachnoidal adhesions (n�3). Fifty-nine patients presented with progressivepain and/or neurological dysfunction. One patient underwent prophylacticsectioning of the filum terminale. Microsurgical de-tethering was performedin each case using multi-modality intra-operative neurophysiological moni-toring. The most common complications encountered were CSF leak andinfective complications. One patient who had undergone multiple previousintradural procedures experienced worsened foot weakness postoperatively.Another patient experienced temporary lower limb numbness. At a meanfollow-up period of 41.5 months, the majority of patients presenting withback (78%) and leg pain (83%) improved. Preoperative motor weakness(64%) was more likely to improve than sensory deficits (45%). Overallneurological status was improved or stabilized in 90% of patients. Nopatient with taut filum terminale or SCM worsened on follow-up. Six pati-ents (10%) had suboptimal clinical outcomes. Five patients had a historyof previous detethering surgery and extensive arachnoidal scarring waspresent intraoperatively.CONCLUSIONS: Surgery for adult TCS is effective for improving painand neurological status in majority of patients. Best clinical outcomesachieved in patients with tight filum terminale or split cord malformation.

Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S64S

or if a tear in the iliac veins occurred during surgery. Pelvic MRV is amore sensitive study for detecting DVT in this patient population thanDoppler ultrasound and should be used if available. Further studies shouldproceed to determine what other risk factors determine which patients areat greatest risk for developing DVTDISCLOSURES: No disclosures.

Previous intradural detethering procedures, particularly in the presence ofextensive arachnoidal scarring appears to be a poor prognostic factor.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.123

Thursday, September 29, 20055:40–6:40 PM

SIPP 4: Complications

5:40122. Incidence of pelvic deep venous thrombosis after anterior/posterior spinal fusion surgerySerena Hu, MD, Anubhav Sinha, Vedat Deviren, MD, Sigurd Berven,MD; University of California, San Francisco, CA, USA

BACKGROUND CONTEXT: Deep venous thrombosis is noted to be aconsequence of anterior spine surgery due to retraction of the iliac vessels.Previous studies have reported an incidence of pulmonary embolus up to6% in patients who had had anterior procedure, however the source of clotwas not routinely detect by clinical signs or Doppler ultrasound to diagnoselower extremity thrombi. Since anterior spinal approaches involve signifi-cant retraction of the great vessels, detection of pelvic thrombi may bemore important in this patient population. Our study used pelvic magneticresonance venography (MRV) to look for thrombi in the postoperativeperiod.PURPOSE: The purpose of our study was to use pelvic magnetic resonancevenography (MRV) prospectively to look for thrombi in the postopera-tive period.STUDY DESIGN/SETTING: Thirty-five patients have been enrolled todate and in addition, there were 4 patients who we were not able to consentprior to surgery, who required an MRV due to clinical suspicion of DVT.Three to five days after their anterior procedure, the patients underwent apelvic MRV. All patients who were studied were called three months aftertheir procedure to see if they had been diagnosed with or had symptomsof a DVT in the interim.PATIENT SAMPLE: For this study, we asked all patients who wereoperated on by our spine service between 2001–2004 for anterior spinesurgery and were over 40 years of age to participate.OUTCOME MEASURES: MRV’s were read by experienced radiologists.Presence of pelvic clots was the primary outcome measure. Secondaryoutcome measures included clinical signs or symptoms of DVT or pulmo-nary embolus.METHODS: We reviewed patient age, time of procedure, number ofanterior levels exposed, whether there was a vascular injury during surgeryand determined whethere these were risk factors for thromboembolic events.RESULTS: Of the 39 total patients who underwent MRVs, 2 had definitepelvic thrombi and one other patient had a probable thrombi. All three ofthese patients had a tear of the iliac vessel during surgery (3 tears withDVT/7 total tears�43%. Patients who had a DVT also had on average,more anterior levels fused (7.0 vs. 6.1) and longer operating times thoughthere were not statistically significant. No additional patients had beendiagnosed with a DVT on follow-up at three months after surgery.CONCLUSIONS: We determined an incidence of 7.7% (3/396) of DVTamong patients over age 40 after anterior spine surgery in the immediatepostoperative period, this is similar to previous studies. We observed anincidence of 25% in patients who had clinical suspicion of a DVT, which issignificantly higher than previously reported. In patients who have a positiveMRV, no patients received complications from either the IVC filter withlong-term anticoagulation or short-term anticoagulation to date. From thisdata we conclude that DVT is a fairly common entity in this patientpopulation and should be treated aggressively when clinically suspected

CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.124

5:46123. Complications of the lumbar anterior surgical approach forartificial disc replacement of the lumbar spineRichard Hynes, MD, F.A.C.S.1, Joseph Wasselle, MD, F.A.C.S.2,Damian Velez, MPAS-PA-C1; 1The B.A.C.K. Center, Melbourne, FL,USA; 2Osler Medical Center, Melbourne, FL, USA

BACKGROUND CONTEXT: The most common complications include15-20% potential vascular injury, 1.8% femoral nerve injury, 0.42–17.5%retrograde ejaculation, 10% urogenital, 12% infection and 4.9% muscularinjury upon literature review.PURPOSE: To evaluate the complications associated with anterior ap-proaches (transperitoneal, retroperitoneal) to the lumbar spine. Is therea higher incidence of complication with transperitoneal compared withretroperitoneal? A focus was made to evaluate retrograde ejaculation, vascu-lar injury, urogenital injury, infection, hernia, gentifemoral nerve injury.STUDY DESIGN/SETTING: A retrospective review was performed bya thorough evaluation of each patient’s medical record and patient interview.A focus was made to evaluate retrograde ejaculation, vascular injury, uro-genital injury, infection, hernia, gentifemoral nerve injury.PATIENT SAMPLE: This study represents a ten year retrospective reviewof 670 cases of anterior transabdominal and laparoscopic approaches withover 1500 levels from L1-2 to L5-S1. Of the 670 cases, 332 were maleand 338 were female.OUTCOME MEASURES: The most common complications include15–20% potential vascular injury, 1.8% femoral nerve injury, 0.42–17.5%retrograde ejaculation, 10% urogential, 12% infection and 4.9% muscularinjury upon literature review. The incidence of retrograde ejaculation iscomprable despite the approach used. A thorough understanding of anatomi-cal structures and the potential complications associated with their injurieswill allow the spinal surgeon and vascular surgeon to be prepared to adaptto changes necessary to reduce the likelyhood of injury.METHODS: After performing these cases, a patient interview, review ofthe patients operative notes for complications and review of each patientschart was performed.RESULTS: In our review of this series of patients, we identifed a 10%incidence of vascular injury, 1 case of femoral nerve injury, 2 cases ofurogenital injury, 1 case of infection, and 1.1% incidence of retrogrdeejaculation. All the vascular injuries were secondary to illiac or venacavalaceration. Thre were no cases of significant injury to the aorta or illiacartery. One case had a substantial loss of 1800cc of blood. Five of thesecases required clamping of the illiac veins and venacava for vascular repairwith significant diminution of SSEP baseline during repair. Only bluntdissection over the anterior L5-S1 disc space and along the anatomic regionof the hypogastric plexus was done for the exposure to diminish the risk ofretrograde ejaculation. Only a comparable complication rate in retrogradeejaculation was found. A lower incidence of hernia, vascular injury, andinfection was appreciated.CONCLUSIONS: Transperitoneal and retroperitoneal exposure to thelumbar spine accompanies a variety of complications. Despite the approachused comparable complications rates can be found and in some cases werefound to be less with a transperitoneal approach when compared with aretroperitoneal approach. We believe that the risk of increased retrogradeejaculation can be comparable to that of the retroperitoneal approach ifblunt dissection is utilized instead of electrocautery. The transabdominalapproach allows direct access to the L1-S1 disc spaces and facilitates