Objective To investigate the influencing factors and imaging characteristics of medial meniscus posterior horn root tear with displacement caused by military training.Methods The clinical data and magnetic resonance imaging(MRI)characteristics of 102 patients with root tears of the posterior horn of the medial meniscus confirmed by arthroscopy in Hebei Provincial Armed Police Corps Hospital from July 2020 to June 2022 were retrospectively analyzed.There were 84 males and 18 females with a mean age of(33.06±5.72)years(21-45 years).According to the displacement after tear,the patients were divided into displacement group(n=35)and non-displacement group(n=67).The clinical data and imaging characteristics were compared between groups.Multivariate regression analysis was used to analyze the risk factors of medial meniscus posterior horn root tear combined with displacement caused by military training.The diagnostic efficacy of MRI for the root tear of medial meniscus posterior horn with displacement was evaluated.Results The absolute amount of meniscus prolapse,the relative rate of meniscus prolapse and the proportion of patients with grade Ⅲ/Ⅳ cartilage degeneration of medial tibial plateau in the displacement group were significantly higher than those in the non-displacement group(P<0.05).Multivariate regression analysis showed that the absolute amount of meniscus prolapse(OR=2.971,95%CI:1.142-8.733),the relative rate of meniscus prolapse(OR=3.177,95%CI:1.227-9.261),and grade Ⅲ/Ⅳ cartilage degeneration of the medial tibial plateau(OR=2.930,95%CI:1.125-7.632)were related to medial meniscus posterior horn root tear with displacement caused by military training(P<0.05).Receiver operating characteristic curve analysis showed that the sensitivity,specificity and area of the curve(AUC)of MRI in the diagnosis of medial meniscus posterior horn root tear with displacement were 85.71%(95%CI:68.96%-94.62%),91.04%(95%CI:80.88%-96.31%)and 0.884(95%CI:0.805-0.939),respectively.Conclusion Medial meniscus posterior horn root tear with displacement caused by military training is related to MRI imaging parameters such as absolute amount of meniscus prolapse,relative of meniscus prolapse rate,and cartilage degeneration of medial tibial plateau.MRI has a high diagnostic efficiency for medial meniscus posterior horn root tear with displacement.

Objective:To explore the technique and clinical effects of free medial plantar flap on reconstruction of the severe defect of thumb caused by electric burn.Methods:Surgical techniques and clinical effects were explored in reconstruction with free medial plantar flap for treatment of severe electric burns of thumbs. From July 2016 to July 2021, 18 patients suffered from severe electric burns of thumbs were admitted in the Department of Burn, Zhengzhou First People's Hospital. All the wounds were the entrance of electric burns. After thorough debridement, the arteries, nerves, tendons, phalanges and interphalangeal joints were exposed to various degrees. Damaged digital proper palmar arteries were ligated and defected proper palmar digital nerves were marked and further anastomosed with the nerves carried by the flap. Palmaris longus tendon grafts were employed to reconstruct the defects of flexor pollicis longus tendon. Wounds were closed by transfer of free medial plantar flaps, and the flap donor sites were closed by inguinal skin grafts. Survival of the flap was observed 1 week after surgery, and the survival of the skin graft in the foot donor site 12 days after surgery. Outpatient follow-up including observation of the appearance and texture of the flap, evaluation of sensory function, thumb alignment and finger flexion according to the Evaluation Trial Standards of Upper Limb Partial Functional of Hand Surgery of Chinese Medical Association. Evaluate the scar hyperplasia in the foot donor site and the standing and walking functions of the donor foot.Results:All flaps survived,at 1 week after surgery. On the 12th day after surgery, all 16 foot flap survived, and 2 patients had local necrosis, and the necrosis healed completely after dressing change for 10 days, the wound healed completely. Among them, 3 patients without tendon transfer experienced a rupture of the flexor pollicis longus tendon at 2 months after surgery, and underwent another palmaris longus tendon transfer. After the surgery, functional exercise was performed with the palm and flexor fingers. After 6-12 months of follow-up, the blood supply, appearance, and texture of the flap were good and similar to that of the palmar skin of the thumb, with varying degrees of recovery in sensation. The TPD was 6-11 mm, and the thumb was restored to varying degrees. According to the Evaluation Trial Standards of Upper Limb Partial Functional of Hand Surgery of Chinese Medical Association, 13 cases in excellent and 5 cases in good. Mild scar hyperplasia remains in the flap site of donor feet, which does not affect the standing and walking functions of the donor foot.Conclusion:The texture of medial plantar skin is similar to that of palmar skin, with good wear resistance and good sensation. Furthermore, it causes a little damage to the donor site and without obvious complication. The medial plantar flap is ideal for reconstruction of a severe wound caused by electric burn in thumb.

Magnetic resonance based electrical properties tomography (MREPT) is a different method from proton density imaging, Bloch-Siegert shift (BSS) is used in this paper to reconstruct the radiofrequency (RF) field amplitude and calculate the distribution of the permittivity constant. The phase of the RF field is approximated by the phase component of the magnetization intensity, and the conductivity distribution is calculated. In the experiment, Bruker 7.0 T magnetic resonance device was used to image two water models and in vivo Balb/c mice to obtain the image of electrical characteristics. Experimental results show that the Bloch-siegert B₁⁺ image is significantly more efficient than the double-angle B₁⁺ image. The study can provide a reference for selecting appropriate B₁ mapping technology for B₁ field imaging of electrical characteristics organizations, and provide basic research support for promoting the practical application of magnetic resonance characteristics.
Algorithms ; Animals ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; Mice ; Phantoms, Imaging ; Tomography