Proceedings of the NASS 19th Annual Meeting / The Spine Journal 4 (2004) 3S–119S 97S

P3. The incidence of heterotopic ossification in total diskreplacements: a prospective randomized FDA study in 257consecutive patientsPaul Tortolani, MD1, Bryan Cunningham2, Paul McAfee, Sr.3, KarenAdams, BS4, Gwen Hosapple, BS4; 1Orthopaedic Associates, Baltimore,MD, USA; 2Union Memorial Hospital, Baltimore, MD, USA; 3Spine andScoliosis Center, Towson, MD, USA; 4Union Memorial Hospital, MD,USA

BACKGROUND CONTEXT: Despite good early clinical outcomes forpatients undergoing lumbar or cervical disk replacements, varying degreesof heterotopic bone has been observed in the tissues surrounding theseimplants. The cause, significance, or incidence of heterotopic ossification(HO) after artificial disk replacement remains unknown.PURPOSE: 1) Determine the incidence of heterotopic bone formationfollowing total disk replacement in consecutive series of patients. 2) Investi-gate whether the presence of heterotopic ossification correlates with factorssuch as excessive disk space distraction, loss of motion, or clinical outcome.STUDY DESIGN/SETTING: This is a prospective analysis of the inci-dence of heterotopic bone formation following single level lumbar diskreplacement.PATIENT SAMPLE: 257 consecutive patients entered in an FDA prospec-tive, randomized trial comparing Charite artifical disk replacement withanterior interbody BAK instrumentation and fusion.OUTCOME MEASURES: The presence of heterotopic bone (HO) wasevaluated using a validated, 5-point radiographic classification system.Change in disk height, Oswestry disability index, and visual analog painscores were correlated with the presence or absence of HO.METHODS: In an effort to better investigate HO, we analyzed all pre-operative and post-operative radiographs including flexion and extensionviews from the recently completed, prospective, randomized, FDA, trialcomparing the Charite artificial disk replacement with anterior interbodyBAK instrumentation and fusion. Over 6900 radiographs were digitized ina central core laboratory and corrected for magnification factors. Using thevalidated, 5-point radiographic classification system, the degree of HO wascategorized for every patient undergoing lumbar disk replacement surgeryboth preoperatively and at 6-week, 3-month, 6-month, 12-month, 1-year,and 2-year follow-up. The change is disk height (in millimeters) from pre-op to 2 years post-op was calculated from lateral radiographs and correlatedwith the presence or absence of HO. Similarly, the Oswestry disabilityindex (ODI) and visual analog scores (VAS) measured at 2 years werecorrelated with presence or absence of HO.RESULTS: The overall incidence of HO in the 257 consecutive patientsundergoing Charite lumbar disk replacement was 4.6% (12/257). Therewere 4 cases of Class I (islands of bone within the soft tissue but notinfluencing the range of motion. Bone is not between the planes formedby the two vertebral endplates). There were 8 cases of Class II (HOpresent between the two planes formed by the vertebral endplates but notblocking or articulating between adjacent vertebral endplates). In 5 of the12 cases (42%), heterotopic bone was visible as early as 6 weeks post-op,and by 3-months post-op, 11 of the 12 cases (92%) had evidence of HO.There were no cases in which the post-operative range of motion didnot exceed the pre-operative range of motion. No statistically significantcorrelation existed between the amount of disc distraction and the presenceor absence of HO (p�0.05). No statistically significant correlation existedbetween clinical outcome and the presence or absence of HO (p�0.05).CONCLUSIONS: The occurence of heterotopic ossification around lumbarartificial disk replacements is infrequent and does not impact motionor clinical outcome.DISCLOSURES: Device or drug: Charite artifical disc. Status: Investiga-tional/Not approved.CONFLICT OF INTEREST: No Conflicts.

doi: 10.1016/j.spinee.2004.05.197

P4. Spinal surgery outcomes the strong influence of demographicsStephen Faust, MD1, Thomas Ducker, MD2, Lori Brady, RN3;1Orthopaedic & Sports Medicine Center, Annapolis, MD, USA;2Annapolis Neurosurgery, Annapolis, MD, USA; 3Anne Arundel MedicalCenter, Annapolis, MD, USA

BACKGROUND CONTEXT: Both our previous retrospective study andstudies by many other authors have suggested a strong influence uponthe outcome of spinal surgery by non-medical (demographic) factors. Aprospective outcomes tracking system at our institution offered the possibil-ity to gather more information on this issue.PURPOSE: To prospectively analyze the inflluence of obesity, involvementwith the legal system, education, job satisfaction, smoking history and otherdemographic factors on the outcome of spinal surgery, and to evaluate theappropriateness, effectiveness and efficacy of our spinal surgical procedures.STUDY DESIGN/SETTING: This is a prospective, blinded, cohort out-comes study. Patients underwent any spinal surgery at our institution overa one-year period were prospectively studied. Pre-operatively, multipledemographic data were obtained. All patients who underwent any spinalsurgical procedure by the seven surgeons at our hospital were entered.PATIENT SAMPLE: All patients operated upon in the calendar year 2002at our institution by 4 neuro-surgeons and 3 orthopaedic spine surgeons.OUTCOME MEASURES: Pre-operatively, Oswestry and/or Neck Dis-ability Index and VAS pain scores were recorded. Patients were tracked bythe seven DRG-related groups. Post-operatively, responses were scaled(by NINDS and Odoms criteria) to measure work (or equivalent) capabili-ties, social activities, drug (including narcotic) use, pain, numbness andweakness, self-rated outcomes, and need for additional care (includinghospitalization).METHODS: Initial patient data was recorded immediately pre-operativelyon a touch-screen computer system. Weight, height and calculated BMI weretaken from the medical record, as was DRG category. Follow-up was bymail or phone by an independent assessor not involved in the surgery andnot employed by any of the surgeons (LB) at six and twelve months post-op.RESULTS: Age groups were similar for the DRG’s except for DRG’s499 (cervical or lumbar laminectomy with co-morbidities) and 497 (cervicaland lumbar laminectomies with fusions, with co-morbidities), who averageda decade older. Technical outcomes were good to excellent, including fusionrates. There were no significant differences among the 7 surgeons. In general,72% returned to work, 75% resumed social activities, 85% rarely or neverused narcotic pain medications, and 80% rated their outcomes as excellentor good. Only 7% required further care. Relief of pain, weakness, numbnessand other symptoms occurred in only 66% of the entire group. But with anormal BMI (below 25), that number was 74%. Patients with a normalBMI who were non-smokers reported relief in 77%. Only 59% of obesepatients and 58% of the smokers reported symptom relief. Effects were addi-tive: obese smokers reported relief in only 58%, while obese litigantsreported relief in only 53%. Adding nicotine use to the last group reducedthe success rate into the 40’s. Patients who had a healthy BMI, didn’t smoke,and were non-litigators rated their relief of symptoms as excellent/goodin 80%, while patients who had all three of these risk factors had 0%excellent and 33% good.CONCLUSIONS: This study demonstrates that demographic factors suchas obesity, nicotine abuse, and litigation have a strong influence on outcomesacross the entire spectrum of ALL spinal surgical procedures regardless ofsurgeon or technical result. These results demonstrate that spinal surgeryis effective and efficacious, but that demographic factors can influence theappropriateness of surgical approaches.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: Author (SF) Speaker’s Bureau Member:member AO North America faculty; Author (SF) Grant Research Support:Research partly supported by a grant from Synthes Spine; Author (TD)Speaker’s Bureau Member: member Synthes North America faculty; Au-thors (TD, LB) Grant Research Support: research partly supported by agrant from Synthes Spine.

doi: 10.1016/j.spinee.2004.05.198