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.

STUDY DESIGN: Prospective, randomized clinical trial from a single surgeon's patient population. OBJECTIVE: 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. SUMMARY OF BACKGROUND DATA: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

The NSLS 100 element solid state array detector.

X-ray absorption studies of dilute samples require fluorescence detection techniques. Since signal-to-noise ratios are governed by the ratio of fluorescent to scattered photons counted by a detector, solid state detectors which can discriminate between fluorescence and scattered photons have become the instruments of choice for trace element measurements. Commercially available 13 element Ge array detectors permitting total count rates < 500000 counts per second are now in routine use. Since X-ray absorption beamlines at high brightness synchrotron sources can already illuminate most dilute samples with enough flux to saturate the current generation of solid state detectors, the development of next-generation instruments with significantly higher total count rates is essential. We present the design and current status of the 100 element Si array detector being developed in a collaboration between the NSLS and the Instrumentation Division at Brookhaven National Laboratory. The detecting array consists of a 10×10 matrix of 4 mm×4 mm elements laid out on a single piece of ultrahigh purity silicon mounted at the front end of a liquid nitrogen dewar assembly. A matrix of charge sensitive integrating preamplifiers feed signals to an array of shaping amplifiers, single channel analyzers, and scalers. An electronic switch, delay amplifier, linear gate, digital scope, peak sensing A/D converter, and histogramining memory module provide for complete diagnostics and channel calibration. The entire instrument is controlled by a LabView 2 application on a MacII ci; the software also provides full control over beamline hardware and performs the data collection.