Yi-Jung Tsai

Comparison of objective muscle strength in c5-c6 and c5-c7 brachial plexus injury patients after double nerve transfer

Purpose: The purpose of this study was to evaluate the quantitative muscle strength to distinguish the outcomes of different injury levels in upper arm type brachial plexus injury (BPI) patients with double nerve transfer. Methods: Nine patients with C5‐C6 lesions (age = 32.2 ± 13.9 year old) and nine patients with C5‐C7 lesions (age = 32.4 ± 7.9 year old) received neurotization of the spinal accessory nerve to the suprascapular nerve combined with the Oberlin procedure (fascicles of ulnar nerve transfer to the musculocutaneous nerve) were recruited. The average time interval between operation and evaluation were 27.3 ± 21.0 and 26.9 ± 20.6 months for C5‐C6 and C5‐C7, respectively. British Medical Research Council (BMRC) scores and the objective strength measured by a handheld dynamometer were evaluated in multiple muscles to compare outcomes between C5‐C6 and C5‐C7 injuries. Results: There were no significant differences in BMRC scores between the groups. C5‐C6 BPI patients had greater quantitative strength in shoulder flexor (P = 0.02), shoulder extensor (P < 0.01), elbow flexor (P = 0.04), elbow extensor (P = 0.04), wrist extensor (P = 0.04), and hand grip (P = 0.04) than C5‐C7 BPI patients. Conclusions: Upper arm type BPI patients have a good motor recovery after double nerve transfer. The different outcomes between C5‐C6 and C5‐C7 BPI patients appeared in muscles responding to hand grip, wrist extension, and sagittal movements in shoulder and elbow joints.

Evaluation of the parameters affecting bone temperature during drilling using a three-dimensional dynamic elastoplastic finite element model

A three-dimensional dynamic elastoplastic finite element model was constructed and experimentally validated and was used to investigate the parameters which influence bone temperature during drilling, including the drill speed, feeding force, drill bit diameter, and bone density. Results showed the proposed three-dimensional dynamic elastoplastic finite element model can effectively simulate the temperature elevation during bone drilling. The bone temperature rise decreased with an increase in feeding force and drill speed, however, increased with the diameter of drill bit or bone density. The temperature distribution is significantly affected by the drilling duration; a lower drilling speed reduced the exposure duration, decreases the region of the thermally affected zone. The constructed model could be applied for analyzing the influence parameters during bone drilling to reduce the risk of thermal necrosis. It may provide important information for the design of drill bits and surgical drilling powers.

Effects of implant drilling parameters for pilot and twist drills on temperature rise in bone analog and alveolar bones

This study concerns the effects of different drilling parameters of pilot drills and twist drills on the temperature rise of alveolar bones during dental implant procedures. The drilling parameters studied here include the feed rate and rotation speed of the drill. The bone temperature distribution was analyzed through experiments and numerical simulations of the drilling process. In this study, a three dimensional (3D) elasto-plastic dynamic finite element model (DFEM) was proposed to investigate the effects of drilling parameters on the bone temperature rise. In addition, the FE model is validated with drilling experiments on artificial human bones and porcine alveolar bones. The results indicate that 3D DFEM can effectively simulate the bone temperature rise during the drilling process. During the drilling process with pilot drills or twist drills, the maximum bone temperature occurred in the region of the cancellous bones close to the cortical bones. The feed rate was one of the important factors affecting the time when the maximum bone temperature occurred. Our results also demonstrate that the elevation of bone temperature was reduced as the feed rate increased and the drill speed decreased, which also effectively reduced the risk region of osteonecrosis. These findings can serve as a reference for dentists in choosing drilling parameters for dental implant surgeries.

Assessment of thermal necrosis risk regions for different bone qualities as a function of drilling parameters

BACKGROUND AND OBJECTIVE During bone drilling, the heat generated by friction depends directly on bone quality and surgical parameters. Excessive bone temperatures may cause thermal necrosis around the pilot hole, weaken the purchase of inserted screws, and in turn reduce the stability of screw fixation. A few studies have addressed the key parameters of drilling, such as the rotation speed of the drill-bit, feed force (axial force), feed rate, tool type, and tip geometry of drill-bits. Nevertheless, in the literature, information on the relationship between bone quality and thermally affected regions is still lacking. This study employed a three-dimensional dynamic elastoplastic finite element model to evaluate the influence of surgical parameters on the bone temperature elevation and assess the risk region of thermal necrosis for different bone qualities as a function of drilling parameters. METHODS To ascertain the heat generation rate and the high-risk region of thermal necrosis, the effects of bone quality, feed rate, feed force, and drill-bit diameter on the bone temperature elevation were explained using a three-dimensional dynamic elastoplastic finite element model, which was validated through experimental measurements. RESULTS The bone temperature was affected by the drilling parameters; the maximum temperature was attained at the junction of cancellous and cortical bones. The bone temperature increased with cortical bone thickness, bone density, and drill-bit diameter, and it decreased with the drilling speed and feed force. CONCLUSIONS The present model could assess the risk region of thermal necrosis by accurately analyzing the bone temperature elevation for various bone qualities, feed forces, and feed rates. The bone temperature increased with the bone mineral density and cortical bone thickness. The highest bone temperature and maximum necrosis region were found near the junction of cortical and cancellous bones. Increasing the drilling speed or feed force can minimize the bone temperature elevation and the risk range of thermal necrosis.