Quantitative Analysis of Cervical Flexion-Extension Radiographs in Rheumatoid Arthritis Patients.

STUDY DESIGN: Diagnostic retrospective case series. OBJECTIVE: To evaluate cervical intersegmental motion in rheumatoid arthritis patients using specialized tracking software (QMA) and compare the findings with a previously published cohort of "normal" subjects. SUMMARY OF BACKGROUND DATA: Rheumatoid arthritis follows 3 patterns of cervical involvement, atlantoaxial subluxation, atlantoaxial impaction, and subaxial subluxation. Deformities present are sometimes considered "unstable" to the point where surgery can be recommended based on the interpretation of cervical radiographs. METHODS: Cervical flexion-extension radiographs of 99 subjects with rheumatoid arthritis were evaluated. Angular and translational segmental motions were determined at each level using specialized tracking software. Findings were compared with previously published normative data using the same device. RESULTS: Relative to controls, patients with rheumatoid arthritis demonstrated significantly less overall sagittal motion. Segmental analysis at C1-C2 demonstrated a 10% prevalence of dynamic motion outside the 95% confidence interval for "normal" patients. In contrast, segmental analysis at C2-C7 demonstrated no intersegmental motion outside the 95% confidence interval for "normal" subjects. CONCLUSIONS: In patients with rheumatoid arthritis, abnormal motion at C1-C2 was consistent with truly dynamic deformity and should be closely evaluated. Conversely, subaxial subluxations, although frequently present, were relatively fixed deformities and in most cases, may not represent an unstable condition.

Long-Term Postoperative Total Knee Arthroplasty Flexion Scores in Relation to Body Mass Index.

Knee range of motion (ROM) is an important postoperative measure of total knee arthroplasty (TKA). There is conflicting literature whether patients who are obese have worse absolute ROM outcomes than patients who are not obese. This study analyzed whether preoperative body mass index (BMI) influences knee ROM after patients' primary TKA. A retrospective investigation was performed on patients, who underwent primary TKA at an academic institution, by one of three fellowship-trained adult reconstruction surgeons. Patients were stratified according to their preoperative BMI into nonobese (BMI < 30.0 kg/m2) and obese (BMI ≥ 30.0 kg/m2) classifications. Passive ROM was assessed preoperatively as well as postoperatively at patients' most recent follow-up visit that was greater than 2 years. Mann-Whitney U tests were performed to determine statistical significance at p-value <0.05 for ROM outcomes. No statistically significant differences were observed when ROM in the nonobese group was compared with ROM in the obese group both preoperatively (105.73 ± 11.58 vs. 104.14 ± 13.58 degrees, p-value = 0.417) and postoperatively (105.83 ± 14.19 vs. 104.49 ± 13.52 degrees, p-value = 0.777). Mean follow-up time for all patients was 4.49 ± 1.92 years. In conclusion, long-term postoperative ROM outcomes were similar between patients who were nonobese and patients who were obese.

Cell-based gene therapy for repair of critical size defects in the rat fibula.

More than a decade has passed since the first experiments using adenovirus-transduced cells expressing bone morphogenetic protein 2 were performed for the synthesis of bone. Since this time, the field of bone gene therapy has tackled many issues surrounding safety and efficacy of this type of strategy. We present studies examining the parameters of the timing of bone healing, and remodeling when heterotopic ossification (HO) is used for bone fracture repair using an adenovirus gene therapy approach. We use a rat fibula defect, which surprisingly does not heal even when a simple fracture is introduced. In this model, the bone quickly resorbs most likely due to the non-weight bearing nature of this bone in rodents. Using our gene therapy system robust HO can be introduced at the targeted location of the defect resulting in bone repair. The HO and resultant bone healing appeared to be dose dependent, based on the number of AdBMP2-transduced cells delivered. Interestingly, the HO undergoes substantial remodeling, and assumes the size and shape of the missing segment of bone. However, in some instances we observed some additional bone associated with the repair, signifying that perhaps the forces on the newly forming bone are inadequate to dictate shape. In all cases, the HO appeared to fuse into the adjacent long bone. The data collectively indicates that the use of BMP2 gene therapy strategies may vary depending on the location and nature of the defect. Therefore, additional parameters should be considered when implementing such strategies.

Assessing mechanical integrity of spinal fusion by in situ endochondral osteoinduction in the murine model.

BACKGROUND: Historically, radiographs, micro-computed tomography (micro-CT) exams, palpation and histology have been used to assess fusions in a mouse spine. The objective of this study was to develop a faster, cheaper, reproducible test to directly quantify the mechanical integrity of spinal fusions in mice. METHODS: Fusions were induced in ten mice spine using a previously described technique of in situ endochondral ossification, harvested with soft tissue, and cast in radiolucent alginate material for handling. Using a validated software package and a customized mechanical apparatus that flexed and extended the spinal column, the amount of intervertebral motion between adjacent vertebral discs was determined with static flexed and extended lateral spine radiographs. Micro-CT images of the same were also blindly reviewed for fusion. RESULTS: Mean intervertebral motion between control, non-fused, spinal vertebral discs was 6.1 +/- 0.2 degrees during spine flexion/extension. In fusion samples, adjacent vertebrae with less than 3.5 degrees intervertebral motion had fusions documented by micro-CT inspection. CONCLUSIONS: Measuring the amount of intervertebral rotation between vertebrae during spine flexion/extension is a relatively simple, cheap (<$100), clinically relevant, and fast test for assessing the mechanical success of spinal fusion in mice that compared favorably to the standard, micro-CT.