A prospective, randomized, blinded, single-site study to evaluate the clinical and radiographic differences between frozen and freeze-dried allograft when used as part of a circumferential anterior lumbar interbody fusion procedure.

Abstract

Prospective, randomized clinical trial from a single surgeon's patient population. The purpose of this study is to compare the outcomes and fusion rates of an anterior lumbar interbody fusion (ALIF) procedure when 2 different preservation methods of the femoral ring allograft (FRA) are used. FRA can be stored via freeze-drying (FD) or freezing (FZ). In a previous biomechanical PLIF model, FZ cancellous allograft failed at an average load 50% less than FD cancellous allograft. Despite this finding, there is no evidence to support which preservation method is more effective at achieving solid fusion in ALIF procedures. Fifty ALIF patients received either FZ or FD FRA. Patients were observed for a minimum of 24 months. Outcome measures included complications, fusion status, implant intactness, 1 to 10 pain scale scores, Oswestry Disability Index (ODI), and SF-36 scores. Univariate comparisons for grafting material are as follows: Average ODI-FD: 46.05 +/- 16.7, FZ: 39.24 +/- 23.65, P = 0.296. Average Physical Component Summary from SF36-FD: 33.47 +/- 10.12, FZ: 39.76 +/- 11.50, P = 0.074. Average 1 to 10 back pain with medication-FD: 3.47 +/- 2.59, FZ: 2.95 +/- 2.48, P = 0.527. ODI scores improved more than 10 points in 62.5% of patients. SF-36 Physical Component Summary scores improved more than 10 points in 27.5% of patients. Back pain with medication scores improved 2 or more points in 60.5% of patients. Seven patients required revision for psuedarthrosis (FD: 6, FZ: 1, P = 0.026). Fusion was achieved in 40 levels (71.4%). The freeze-dried graft had a higher likelihood of pseudarthrosis (P = 0.026). When the results are considered in terms of clinical outcomes, the 2 methods of graft preservation perform with few statistically significant differences. Radiographic analysis showed that the freeze-dried graft had a higher likelihood of pseudarthrosis.