Position in reverse shoulder arthroplasty

The purpose of this study was to determine the optimal position of the baseplate on the small glenoid of female Japanese. Two sets of 3D scapular models were made according to the CT data of 7 female cadavers. We set two scenarios of the baseplate placement : A and B. In scenario A, the baseplate was placed on the glenoid face centrally in the anteroposterior direction. In scenario B, the baseplate was implanted at the point where the baseplate post was contained within the glenoid vault. Whether or not the baseplate post perforated the scapular neck was recorded. In scenario A, the central post penetrated the scapular neck posteriorly in 5 scapulae. In scenario B, the average distances from the guide pin position to the anterior glenoid rim was 9.7 ± 1.7 mm and the optimal position of the guide pin was 1.9 ± 1.7 mm anterior from the glenoid center. The central post was contained within the scapula without breakage of the cortex. This study demonstrated that shifting the center of the baseplate slightly anterior to the anatomic center is necessary to avoid perforation of the scapular neck in small female Japanese

Early changes in muscle atrophy and muscle fiber type conversion after spinal cord transection and peripheral nerve transection in rats

BACKGROUND: Spinal cord transection and peripheral nerve transection cause muscle atrophy and muscle fiber type conversion. It is still unknown how spinal cord transection and peripheral nerve transection each affect the differentiation of muscle fiber type conversion mechanism and muscle atrophy. The aim of our study was to evaluate the difference of muscle weight change, muscle fiber type conversion, and Peroxisome proliferator-activated receptor-γ coactivatior-1α (PGC-1α) expression brought about by spinal cord transection and by peripheral nerve transection. METHODS: Twenty-four Wistar rats underwent surgery, the control rats underwent a laminectomy; the spinal cord injury group underwent a spinal cord transection; the denervation group underwent a sciatic nerve transection. The rats were harvested of the soleus muscle and the TA muscle at 0 week, 1 week and 2 weeks after surgery. Histological examination was assessed using hematoxylin and eosin (H&E) staining and immunofluorescent staing. Western blot was performed with 3 groups. RESULTS: Both sciatic nerve transection and spinal cord transection caused muscle atrophy with the effect being more severe after sciatic nerve transection. Spinal cord transection caused a reduction in the expression of both sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection produced an increase in expression of sMHC protein and PGC-1α protein in the soleus muscle. The results of the expression of PGC-1α were expected in other words muscle atrophy after sciatic nerve transection is less than after spinal cord transection, however muscle atrophy after sciatic nerve transection was more severe than after spinal cord transection. CONCLUSION: In the conclusion, spinal cord transection diminished the expression of sMHC protein and PGC-1α protein in the soleus muscle. On the other hand, sciatic nerve transection enhanced the expression of sMHC protein and PGC-1α protein in the soleus muscle

Direct measurement of radiation exposure dose to individual organs during diagnostic computed tomography examination

Ionizing radiation from Computed tomography (CT) examinations and the associated health risks are growing concerns. The purpose of this study was to directly measure individual organ doses during routine clinical CT scanning protocols and to evaluate how these measurements vary with scanning conditions. Optically stimulated luminescence (OSL) dosimeters were surgically implanted into individual organs of fresh non-embalmed whole-body cadavers. Whole-body, head, chest, and abdomen CT scans were taken of 6 cadavers by simulating common clinical methods. The dosimeters were extracted and the radiation exposure doses for each organ were calculated. Average values were used for analysis. Measured individual organ doses for whole-body routine CT protocol were less than 20 mGy for all organs. The measured doses of surface/shallow organs were higher than those of deep organs under the same irradiation conditions. At the same tube voltage and tube current, all internal organ doses were significantly higher for whole-body scans compared with abdominal scans. This study could provide valuable information on individual organ doses and their trends under various scanning conditions. These data could be referenced and used when considering CT examination in daily clinical situations

Pullout Strength of Pedicle Screws

Study Design: A cadaveric biomechanical study designed to test the pullout strength of pedicle screws. Objective: To evaluate the pullout strength of redirected pedicle screws with a larger diameter following lateral wall breach, redirected pedicle screws of the same diameter following medial wall breach, and redirected pedicle screws with a larger diameter following medial wall breach. Summary of Background Data: Screw malposition is one of the main pitfalls of inserting pedicle screws. Intraoperatively a malpositioned screw is re-directed and inserted along the correct axis. Methods: Forty-seven vertebrae (T9–L5) were harvested from 8 fresh cadaveric spines. The 18 pedicle screws that breached the lateral wall were then removed and redirected using a pedicle screw of 1 mm larger in diameter. The 16 pedicle screws that had breached the medial wall were then removed and redirected using a pedicle screw of the same diameter. The other 13 pedicle screws that had breached the medial wall were then removed and redirected using a pedicle screw of 1 mm larger in diameter. The pullout strength was measured. Results: Following lateral wall breach, mean pullout strength for the larger redirected screws was 46.9% greater than that of the correctly aligned screws. Following medial wall breach, mean pullout strength for the redirected screws of the same diameter was 20.6% less than that of the correctly aligned screws. Mean pullout strength for the larger pedicle screws following medial wall breach was 27.3% more than that of the correctly aligned screws. Conclusion: Redirected pedicle screws of larger diameter after a lateral or medial pedicle breach show recovery of pullout strength. However, the pullout strength of redirected pedicle screws of the same diameter after a medial pedicle breach is significantly less than that of correctly aligned screws.Redirected pedicle screws of larger diameter after a lateral or medial pedicle breach show the recovery of pullout strength. However, the pullout strength of redirected pedicle screws of the same diameter after a medial pedicle breach is significantly less than that of correctly aligned screws

Vacuum phenomenon of sacroiliac joint

Study Design: A radiologic study of sacropelvic morphology and vacuum phenomenon of sacroiliac joint in subjects unrelated to low back pain. Purpose: The aim of this study is to describe the relationship between sacropelvic morphology and vacuum phenomenon of the sacroiliac joint. Overview of Literature: Lumbopelvic alignment and sacropelvic morphology are associated with the pathomechanisms of various spinal disorders. The vacuum phenomena of the sacroiliac joint (SJVP) are often observed in clinical practice, but the relationships between these phenomena and sacropelvic morphology have not been investigated. This study examined the prevalence of SJVP in computed tomography (CT) images and the relationship between sacropelvic morphology and SJVP. Methods: We analyzed multiplanar CT images of 93 subjects (59 men, 34 women). Pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and lumbar lordosis (LL) were measured using the three-dimensional reconstruction method. The prevalence of SJVP in multiplanar CT images were reviewed. Roland-Morris Disability Questionnaire (RDQ) scores and the modified Japanese Orthopedic Association (JOA) score, which focuses on subjective symptoms and restriction of activities of daily living, were also obtained from all the subjects. Results: Thirty-six of the 93 subjects had SJVP (39%), with marked female predominance (91% women, 8.5% men). Men with SJVP had significantly lower PI than men without SJVP (35.1° vs. 46.3°, p<0.05). There was no correlation between SJVP and the modified JOA or RDQ scores. Conclusions: These data suggest that differences in sacropelvic morphology can influence the biomechanical environment and contribute to SJVP in men. Presence of SJVP did not affect JOA or RDQ scores

Myelopathy due to C2 Spondylolysis

We report a case with compression myelopathy due to proliferative changes around the C2 pars defects without instability. A 69-year-old man presented with progressive clumsy hands and spastic gait. Plain radiographs showed bilateral spondylolysis (pars defects) at C2 and fusion between C2 and C3 spinous processes. Dynamic views revealed mobility through the pars defects, but there was no apparent instability. Computed tomography showed proliferative changes at the pars defects, which protruded into spinal canal. On magnetic resonance imaging, the spinal cord was compressed and intramedullary high signal change was found. A diagnosis of compression myelopathy due to proliferative changes around the C2 pars defects was made. We performed posterior decompression. Postoperatively, symptoms have been alleviated and images revealed sufficient decompression and no apparent instability. In patients with the cervical spondylolysis, myelopathy caused by instability or slippage have been periodically reported. The present case involving C2 spondylolysis is extremely rare

Effect of baseplate position on locking screws

Introduction : Superior screw insertion in reverse shoulder arthroplasty (RSA) carries the potential risk of suprascapular injury. The purpose of this study was to evaluate how the baseplate position affects the superior screw position and length in RSA. Methods : Three-dimensional (3D) computer simulation models of RSA were established using computed tomography data of baseplates with superior and inferior screws and 3D scapular models from 10 fresh cadavers. Superior screw position, the distance from the superior screw hole to the suprascapular notch, and the screw lengths were measured and compared among various baseplate positions with two inferior tilts (0 and 10 degrees) and three rotational patterns (11–5, 12–6, and 1–7 o’clock in the right shoulder). Results : For the 1–7 o’clock / inferior tilt 0 degrees baseplate, the superior screw located anterior to the SS notch in all shoulders, the distance to the SS notch was the longest (12.8 mm), and the inferior screw length was the shortest (23.1 mm). Conclusion : Although there is a concern of a short inferior screw length, initial fixation using a baseplate with 1–7 o’clock rotation and an inferior tilt of 0 degrees appears preferable for SS nerve injury prevention during superior screw insertion

Radiation exposure to the hand

Study Design: Prospective study. Purpose: During fluoroscopically guided spinal procedure, the hands of spinal surgeons are placed close to the field of radiation and may be exposed to ionizing radiation. This study directly measured the radiation exposure to the hand of a spinal interventionalist during fluoroscopically guided procedures. Overview of Literature: Fluoroscopically guided spinal procedures have been reported to be a cause for concern due to the radiation exposure to which their operators are exposed. Methods: This prospective study evaluated the radiation exposure of the hand of one spinal interventionalist during 52 consecutive fluoroscopic spinal procedures over a 3-month period. The interventionalist wore three real-time dosimeters secured to the right forearm, under the lead apron over the chest, and outside the lead apron over the chest. Additionally, one radiophotoluminescence glass dosimeter was placed under the lead apron over the left chest and one ring radiophotoluminescence glass dosimeter was worn on the right thumb. The duration of exposure and radiation dose were measured for each procedure. Results: The average radiation exposure dose per procedure was 14.9 µSv, 125.6 µSv, and 200.1 µSv, inside the lead apron over the chest, outside the lead apron over the chest, and on the right forearm, respectively. Over the 3-month period, the protected radiophotoluminescence glass dosimeter over the left chest recorded less than the minimum reportable dose, whereas the radiophotoluminescence glass ring dosimeter recorded 368 mSv for the thumb. Conclusions: Our findings indicated that the cumulative radiation dose measured at the dominant hand may exceed the annual dose limit specified by the International Commission on Radiological Protection. Spinal interventionalists should take special care to limit the duration of fluoroscopy and radiation exposure

Posterior-Stabilized型人工膝関節置換術において内側側副靭帯の解離が腔骨内旋運動に及ぼす影響の検討 : 未固定遺体を用いた研究

Background: Previous studies suggested that changes in kinematics in total knee arthroplasty (TKA) affected satisfaction level. The aim of this cadaveric study was to evaluate the effect of medial collateral ligament (MCL) release by multiple needle puncture on knee rotational kinematics in posterior-stabilized TKA. Methods: Six fresh, frozen cadaveric knees were included in this study. All TKA procedures were performed with an image-free navigation system using a 10-mm polyethylene insert. Tibial internal rotation was assessed to evaluate intraoperative knee kinematics. Multiple needle puncturing was performed 5,10, and 15 times for the hard portion of the MCL at 90° knee flexion. Kinematic analysis was performed after every 5 punctures. After performing 15 punctures, a 14-mm polyethylene insert was inserted, and kinematic analysis was performed. Results: The tibial internal rotation angle at maximum knee flexion without multiple needle puncturing was significantly larger (9.42°) than that after 15 punctures (3°). Negative correlation (Pearson r.＝0.715, P < .001) between tibial internal rotation angle at maximum knee flexion and frequency of puncture was observed. The tibial internal rotation angle with a 14-mm insert was significantly larger (7.25°) compared with the angle after 15 punctures. Conclusion: Tibial internal rotation during knee flexion was reduced by extensive MCL release using multiple needle puncturing and was recovered by increasing of medial tightness. From the point of view of knee kinematics, medial tightness should be allowed to maintain the internal rotation angle of the tibia during knee flexion which might lead to patient satisfaction