Non-instrumented Posterolateral Lumbar Fusions Utilizing Combined Lamina Autograft and Beta Tricalcium Phosphate in a Predominantly Geriatric Population : An Outcome Assessment

The morbidity associated with allograft or demineralized bone matrix utilized to supplement autograft in spinal fusions has prompted the search for the ideal artificial bone volume expander. One artificial supplement, Beta Tricalcium Phosphate [Vitoss, Orthovita, Malvem. PA, USA], was prospectively utilized to supplement lamina autograft [50:50 mix] in 30 consecutive patients undergoing multilevel laminectomies [average 5.1 Ievels] and I [16 patients] or 2 [ 1 4 patients] level non-instrumented posterolateral fusions. These older patients averaged 7 1 .4 years of age, with 28 of 30 patients over 65 years old. The series included 21 females and 9 males. Major comorbidities included osteoporosis [24 patients], hypertension [20 patients], obesity [20 patients] , elevated cholesterol [12 patients], coronary artery disease [9 patients], diabetes [7 patients], and smoking [8 patients]. Seven of 30 patients had prior surgery including far lateral disc excision in 4 patients, and laminectomy for stenosis in 3 patients. Preoperatively, dynamic X-rays documented degenerative spondylolisthesis [25 patients], spondylolysis [1 patient], and instability secondary to prior surgery [4 patients]. Preoperative MR and CT studies predominantly demonstrated multilevel stenosis [30 patients] and hypertrophy/ossification of the yellow ligament [OYL] [24 patients]. Multilevel laminectomies and non-instrumented fusions resulted in both dynamic X-ray and 2D-CT documented fusion in 27 patients [average 6.5 months]. Two patients exhibited fusion on dynamic X-rays [no motion] but not on the 2D-CT studies obtained up to 1 8 months postoperatively; neither was symptomatic and no second operations were required. Only one patient exhibited symptomatic dynamic X-ray and 2D-CT documented pseudarthrosis I year following surgery, and required a second operation. Patients were followed a minimum of I postoperative year [average 20 months] , Utilizing Odom's criteria, recovery assessed I year postoperatively revealed 26 excellent, 3 good, and I fair outcome(s). SF-36 questionnaire data obtained preoperatively and 6 weeks, 3 months, 6 months, and I year postoperatively demonstrated maximal improvement by the 6th postoperative month at which time patients demonstrated moderate improvement on 2 Health Scales EGeneral Health, Social Function], and marked improvement on the remaining 6 Health Scales [Physical Function, Role Physical, Bodily Pain, Vitality, Role Emotional, Mental Health].