Three-dimensional photography for the evaluation of facial profiles in obstructive sleep apnoea.

BACKGROUND AND OBJECTIVE: Craniofacial structure is an important determinant of obstructive sleep apnoea (OSA) syndrome risk. Three-dimensional stereo-photogrammetry (3dMD) is a novel technique which allows quantification of the craniofacial profile. This study compares the facial images of OSA patients captured by 3dMD to three-dimensional computed tomography (3-D CT) and two-dimensional (2-D) digital photogrammetry. Measurements were correlated with indices of OSA severity. METHODS: Thirty-eight patients diagnosed with OSA were included, and digital photogrammetry, 3dMD and 3-D CT were performed. Distances, areas, angles and volumes from the images captured by three methods were analysed. RESULTS: Almost all measurements captured by 3dMD showed strong agreement with 3-D CT measurements. Results from 2-D digital photogrammetry showed poor agreement with 3-D CT. Mandibular width, neck perimeter size and maxillary volume measurements correlated well with the severity of OSA using all three imaging methods. Mandibular length, facial width, binocular width, neck width, cranial base triangle area, cranial base area 1 and middle cranial fossa volume correlated well with OSA severity using 3dMD and 3-D CT, but not with 2-D digital photogrammetry. CONCLUSION: 3dMD provided accurate craniofacial measurements of OSA patients, which were highly concordant with those obtained by CT, while avoiding the radiation associated with CT.

Feasibility study of using viscoplastic bone cement for vertebroplasty: an in vivo clinical trial and in vitro cadaveric biomechanical examination.

STUDY DESIGN: An in vivo clinical trial, and an in vitro cadaveric biomechanical and micromorphologic analysis. OBJECTIVE: To find the feasibility of using viscoplastic bone cement for vertebroplasty. SUMMARY OF BACKGROUND DATA: Vertebroplasty involved in bone cement reinforcement of fractured vertebra has shown promising clinical results. The most frequently observed complication of vertebroplasty is the cement leakage during surgery. Many methods were proposed and were successful at reducing the risk of leakage, such as creating a void within vertebra to reduce the injection pressure, increasing the cement viscosity to reduce the cement infiltration, etc. Nevertheless, a more cost-effective and safer surgery method is still the goal for many spine surgeons and researchers. METHODS: To deliver the viscoplastic bone cement into the vertebra, a unipedicular tract and a void in the vertebra was created using a curette. The viscoplastic bone cement was then delivered into the void piece by piece and tamped for compactness with a blunt end tool. For the in vitro biomechanical test, 7 thoracic vertebrae were used. The intact specimens were compressed to lose 25% of its intact height, and then augmented with viscoplastic bone cement. Postaugmentation CT scanning was taken to examine the cement distribution, leakage path, and cement filling ratio within the vertebra. Postaugmentation compression test was conducted to examine the vertebral strength and stiffness, and then compared with the intact ones. Finally, the vertebrae were cut into slices for micromorphologic analysis. RESULTS: The 6 in vivo clinical trials were all successfully operated with significant pain relief and showed no leakage during and after the surgery. The in vitro biomechanical test showed the cement augmentation significantly increased the vertebral strength (pre 3164 (229) N vs. post 3905 (484) N, P < 0.003), but tentatively decreased the vertebral stiffness (pre 1074 (74) N/mm vs. post 801 (370) N/mm, P = 0.081). The postaugmentation CT scanning showed the cement was well confined within the vertebra and the cement filling ratio was 21% (ranged from 15% to 29%). The depth that the viscoplastic bone cement infiltrated into the cancellous bone was 3.5 (0.6) mm, which is less than the depth [8.3 (2.2) mm, P < 0.001] of standard viscous bone cement vertebroplasty. CONCLUSION: Vertebroplasty using viscoplastic bone cement is clinically feasible and can effectively improve the vertebral strength and reduce the cement infiltration depth. The risk of cement leakage can also be decreased by using viscoplastic bone cement.