Ankle arthroplasty and ankle arthrodesis: gait analysis compared with normal controls.

BACKGROUND: This study compared patients with isolated end-stage ankle osteoarthritis, after undergoing either total ankle arthroplasty or arthrodesis, using gait analysis and patient-reported outcome measures to elucidate differences between the two treatment options, as compared with a healthy control group. METHODS: Gait analyses were performed on patients with isolated ankle arthritis more than one year after undergoing either total ankle arthroplasty or arthrodesis during a ten-year period. Validated outcome questionnaire data were obtained. Seventeen patients undergoing total ankle arthroplasty, seventeen patients undergoing arthrodesis, and ten matched control subjects were included for comparison. RESULTS: Patients who had undergone arthroplasty, when compared with patients who had undergone arthrodesis, demonstrated greater postoperative total sagittal plane motion (18.1° versus 13.7°; p < 0.05), dorsiflexion (11.9° versus 6.8°; p < 0.05), and range of tibial tilt (23.1° versus 19.1°; p < 0.05). Plantar flexion motion was not equivalent to normal in either group. Ankle moments and power in both treatment groups remained significantly lower compared with the control group (p < 0.05 between each treatment group and the control group for both variables). Gait patterns in both treatment groups were not completely normalized. Improvements in patient-reported Ankle Osteoarthritis Scale and Short Form-36 scores were similar for both treatment groups. CONCLUSIONS: The gait patterns of patients following three-component, mobile-bearing total ankle arthroplasty more closely resembled normal gait when compared with the gait patterns of patients following arthrodesis. Dorsal motion in the sagittal plane was primarily responsible for the differences. Improvement in self-reported clinical outcome scores was similar for both groups. Further investigation is needed to determine why patients who have undergone total ankle arthroplasty do not use the plantar flexion motion in the terminal-stance phase and to explain the limited increase in power generation at toe-off after arthroplasty. Results obtained from this study may be used for future modifications of ankle prostheses and may add to clinicians' ability to inform patients of predicted functional outcomes prior to the treatment of end-stage ankle osteoarthritis.

Assessment of two 3-D fluoroscopic systems for articular fracture reduction: a cadaver study.

OBJECTIVE: The most commonly used imaging device for assessment of fracture reduction is the two-dimensional X-ray fluoroscope. Two recently introduced 3D fluoroscopic devices, the Siremobil ISO-C3D (Siemens) and the C-InSight (Mazor Surgical Technologies), enable the surgeon to obtain spatial information for the assessment of articular reduction and hardware placement. The purpose of this study was to assess the reliability and accuracy of these two 3D fluoroscopic systems in measuring articular reduction in a cadaveric tibial plateau fracture. METHODS: Six cadaveric knee specimens were osteotomized at the lateral tibial plateau and fixed with a maximal articular step-off of 0, 1, 2.5, 5 and 7.5 mm. Each specimen was scanned 10 times with two 3D fluoroscopes, the Siremobil ISO-C3D and the C-InSight. The resulting images were reformatted and interpreted for articular displacements at four different locations at the plateau level and were compared with high-resolution CT scans by an independent observer. RESULTS: For the non-displaced fracture, no displacement (mean < 0.1 mm) was observed in either modality. The mean scanning time for the ISO-C3D was 2 min, while each C-InSight scan took 20 s. The readings at four different points along the malreduced fractures were similar for most measurements with either of the two modalities. The C-InSight readings were less accurate than those of the ISO-C3D, relative to the CT scan, but most errors were within clinically acceptable limits (< 2 mm) and used less radiation. CONCLUSIONS: Intraoperative 3D fluoroscopes can detect clinically significant intra-articular step-off with acceptable measurement errors, using newer devices that enable the use of a conventional C-arm and reduced radiation.

A technique of anterior screw removal through a posterior costotransversectomy approach for posterior-based osteotomies.

STUDY DESIGN: Case report. OBJECTIVE: To describe a novel technique to remove anterior instrumentation from a posterior approach while performing posterior-based osteotomies for spinal deformities. SUMMARY OF BACKGROUND DATA: Posterior-based osteotomies such as pedicle subtraction osteotomies (PSOs) and vertebral column resections are performed to restore sagittal alignment. The removal of previously placed anterior implants at the desired osteotomy level can often be challenging. We propose a technique for the removal of anterior instrumentation through a posterior approach to facilitate osteotomy closure and deformity correction, while avoiding the need for an anterior incision. METHODS: A 34-year-old woman presented with a residual deformity after several anterior and posterior procedures. The residual coronal Cobb angle measured 60 degrees between T7 and L2, with a 46 degrees thoracolumbar kyphosis between T10 and L2. The screw head at the desired osteotomy level was in close proximity to the liver after the previous right-sided thoracoabdominal approach. Therefore, the T11 anterior screw was accessed through a posterior costotransversectomy approach and disconnected from the rod proximally and distally with a high-speed side-cutting burr. A portion of the right lateral vertebral body of T11 was removed to expose the neck of the screw, which was separated from the shaft with the same burr. A PSO was performed at T11 and the remaining screw shank was removed with the posterior-based osteotomy. RESULTS: No major complications were encountered during the procedure. The anterior screw at T11 was removed from posteriorly, and the PSO was completed successfully. Postoperative recovery was without incident, and the patient was very satisfied with her results. CONCLUSION: This technique describes a novel, safe, and effective method to deal with anterior instrumentation from the posterior approach while performing posterior-based osteotomies for rigid spinal deformities.