The dawn of computer-assisted robotic osteotomy with ytterbium-doped fiber laser

Currently, laser radiation is used routinely in medical applications. For infrared lasers, bone ablation and the healing process have been reported, but no laser systems are established and applied in clinical bone surgery. Furthermore, industrial laser applications utilize computer and robot assistance; medical laser radiations are still mostly conducted manually nowadays. The purpose of this study was to compare the histological appearance of bone ablation and healing response in rabbit radial bone osteotomy created by surgical saw and ytterbium-doped fiber laser controlled by a computer with use of nitrogen surface cooling spray. An Ytterbium (Yb)-doped fiber laser at a wavelength of 1,070 nm was guided by a computer-aided robotic system, with a spot size of 100 μm at a distance of approximately 80 mm from the surface. The output power of the laser was 60 W at the scanning speed of 20 mm/s scan using continuous wave system with nitrogen spray level 0.5 MPa (energy density, 3.8?×?10⁴ W/cm²). Rabbits radial bone osteotomy was performed by an Yb-doped fiber laser and a surgical saw. Additionally, histological analyses of the osteotomy site were performed on day 0 and day 21. Yb-doped fiber laser osteotomy revealed a remarkable cutting efficiency. There were little signs of tissue damage to the muscle. Lased specimens have shown no delayed healing compared with the saw osteotomies. Computer-assisted robotic osteotomy with Yb-doped fiber laser was able to perform. In rabbit model, laser-induced osteotomy defects, compared to those by surgical saw, exhibited no delayed healing response.     

Upregulation of prolactin receptor in proximal tubular cells was induced in cardiac dysfunction model mice

Background

In order to clarify the interaction between cardiac dysfunction and sodium homeostasis in the kidney, we used a murine model of cardiac dysfunction and investigated the effect on sodium transporters in renal tubular cells.

Methods

Cardiac function was deteriorated by abdominal aortic banding, and the gene expression of sodium transporters in the kidneys was evaluated by real-time RT-PCR and compared with that in the kidneys of control mice.

Results

Gene expression of all three variants of the murine prolactin receptor was enhanced by aortic banding. Upregulated prolactin receptor was distributed in the proximal tubular cells of the pars recta in the deep inner cortex and the outer stripe of the outer medulla. Prolactin has been reported to be a natriuretic hormone that inhibits proximal tubular Na⁺/K⁺-ATPase activity, resulting in reduced sodium reabsorption and the acceleration of natriuresis. Inhibition of endogenous prolactin secretion by bromocriptine administration decreased the urine sodium excretion in both aortic banding and control mice. On the other hand, excess exogenous prolactin administration enhanced urine potassium excretion in aortic banding mice. Furthermore, a high-sodium diet accelerated urinary sodium excretion, which was also significantly decreased by inhibition of endogenous prolactin secretion in aortic banding mice.

Conclusion

We reported that the prolactin receptor was upregulated by aortic banding treatment. Prolactin-prolactin receptor interaction in the proximal tubular cells of the pars recta should involve a different mechanism of kaliuresis other than inhibition of Na⁺/K⁺-ATPase.     

Kinematic and Kinetic Profiles of Trunk and Lower Limbs during Baseball Pitching in Collegiate Pitchers

The purpose of this study was to clarify differences in the kinematic and kinetic profiles of the trunk and lower extremities during baseball pitching in collegiate baseball pitchers, in relation to differences in the pitched ball velocity. The subjects were 30 collegiate baseball pitchers aged 18 to 22 yrs, who were assigned to high- (HG, 37.4 ± 0.8 m·s^-1) and low-pitched-ball-velocity groups (LG, 33.3 ± 0.8 m·s^-1). Three-dimensional motion analysis with a comprehensive lower-extremity model was used to evaluate kinematic and kinetic parameters during baseball pitching. The ground-reaction forces (GRF) of the pivot and stride legs during pitching were determined using two multicomponent force plates. The joint torques of hip, knee, and ankle were calculated using inverse-dynamics computation of a musculoskeletal human model. To eliminate any effect of variation in body size, kinetic and GRF data were normalized by dividing them by body mass. The maxima and minima of GRF (Fy, Fz, and resultant forces) on the pivot and stride leg were significantly greater in the HG than in the LG (p < 0.05). Furthermore, Fy, Fz, and resultant forces on the stride leg at maximum shoulder external rotation and ball release were significantly greater in the HG than in the LG (p < 0.05). The hip abduction, hip internal rotation and knee extension torques of the pivot leg and the hip adduction torque of the stride leg when it contacted the ground were significantly greater in the HG than in the LG (p < 0.05). These results indicate that, compared with low-ball-velocity pitchers, high-ball-velocity pitchers can generate greater momentum of the lower limbs during baseball pitching.

Key points

• High-ball-velocity pitchers are characterized by greater momentum of the lower limbs during pitching motion.
• For high-pitched-ball velocity, stabilizing lower limbs during pitching plays an important role in order to increase the rotation and forward motion of the trunk.
• Computation of the lower-extremity kinetics and measurement of lower-extremity strength may help clarify the role of muscle strength in determining knee and hip function in baseball pitching.

Key words: Throwing movement, pitching ball velocity, ground-reaction force, lower limbs, pivot and stride legs     

Kinematics of the thoracic spine in trunk lateral bending: in vivo three-dimensional analysis

Background contextIn vivo three-dimensional kinematics of the thoracic spine in trunk lateral bending with an intact rib cage and soft tissues has not been well documented. There is no quantitative data in the literature for lateral bending in consecutive thoracic spinal segments, and there has not been consensus on the patterns of coupled motion with lateral bending.PurposeTo demonstrate segmental ranges of motion (ROMs) in lateral bending and coupled motions of the thoracic spine.Study designIn vivo three-dimensional biomechanics study of the thoracic spine.Patient sampleFifteen healthy male volunteers.Outcome measuresComputed analysis by using voxel-based registration.MethodsParticipants underwent computed tomography of the thoracic spine in three supine positions: neutral, right maximum lateral bending, and left maximum lateral bending. The relative motions of vertebrae were calculated by automatically superimposing an image of vertebrae in a neutral position over images in bending positions, using voxel-based registration. Mean values of lateral bending were compared among the upper (T1–T2 to T3–T4), the middle-upper (T4–T5 to T6–T7), the middle-lower (T7–T8 to T9–T10), and the lower (T10–T11 to T12–L1) parts of the spine.ResultsAt lateral bending, the mean ROM (±standard deviation) of T1 with respect to L1 was 15.6°±6.3° for lateral bending and 6.2°±4.8° for coupled axial rotation in the same direction as lateral bending. The mean lateral bending of each spinal segment with respect to the inferior adjacent vertebra was 1.4°±1.3° at T1–T2, 1.3°±1.2° at T2–T3, 1.4°±1.3° at T3–T4, 0.9°±0.9° at T4–T5, 0.8°±1.0° at T5–T6, 1.1°±1.1° at T6–T7, 1.7°±1.2° at T7–T8, 1.3°±1.2° at T8–T9, 1.6°±0.7° at T9–T10, 1.8°±0.8° at T10–T11, 2.3°±1.0° at T11–T12, and 2.2°±0.8° at T12–L1. The smallest and the largest amounts of lateral bending were observed in the middle-upper and the lower parts, respectively. There was no significant difference in lateral bending between the upper and the middle-lower parts. Coupled axial rotation of each segment was generally observed in the same direction as lateral bending. However, high variability was found at the T2–T3 to T5–T6 segments. Coupled flexion was observed at the upper and middle parts, and coupled extension was observed at the lower part.ConclusionsThis study revealed in vivo three-dimensional motions of consecutive thoracic spinal segments in trunk lateral bending. The thoracolumbar segments significantly contributed to lateral bending. Coupled axial rotation generally occurred in the same direction with lateral bending. However, more variability was observed in the direction of coupled axial rotation at T2–T3 to T5–T6 segments in the supine position. These results are useful for understanding normal kinematics of the thoracic spine.     

Indication for resection and possibility of observation for intraductal papillary mucinous neoplasm with high-risk stigmata

Background/ObjectivesAccording to the revised international intraductal papillary mucinous neoplasm (IPMN) guidelines (2017), the indication for surgery is based on risk classification. However, some IPMNs with high-risk stigmata (HRS) can be observed for long periods without resection. Hence, we need to reconsider the risk stratification, and this study aimed to propose a novel risk stratification for HRS-IPMNs.MethodsWe enrolled 328 patients diagnosed with IPMN using endoscopic ultrasound between 2012 and 2019. We compared clinicopathological features between HRS and worrisome features (WF) and evaluated outcomes of HRS-IPMN.ResultsFifty-three patients (HRS 38, WF 15) underwent resection at initial diagnosis and 275 patients were observed. Following observation for 30 months, 22 patients (17 HRS, 5 WF) underwent resection. Analysis of resected IPMNs (n = 75) revealed that HRS had dominantly pancreatobiliary mucin subtype. Pancreatobiliary-type IPMN had larger nodule sizes and lymphatic invasion and high recurrence with poor prognosis. Seventy-four patients were diagnosed with HRS, 55 underwent resection, and 19 continue to be observed. The resected group had larger nodule sizes (median 8 mm vs. 5 mm; P = 0.060), whereas the observed group had more main pancreatic duct (MPD) dilation (median 10 mm vs. 5 mm; P = 0.005). In the resected HRS group, only patients with MPD dilation ≥10 mm (n = 10) had no recurrence but had a favorable prognosis compared with those nodule size ≥5 mm (n = 45).ConclusionsLarge nodule size may be associated with pancreatobiliary subtype and poor prognosis; however, patients with MPD dilation ≥10 mm with nodule size <5 mm did not require resection.