ObjectiveTo investigate the lower limb muscle synergy patterns during jumping in patients after anterior cruciate ligament reconstruction (ACLR). MethodsFrom March to November, 2022, 23 patients after ACLR were enrolled as observation group, and 24 healthy ones matched in height, body mass and exercise level were recruited as control group at Wuhan Sports University. Surface electromyography (sEMG) data of lower limb muscles were collected during a single-leg vertical jump task. Non-negative matrix factorization was applied for synergy analysis. The number of synergies, variance accounted for, synergy structure (muscle weight) and activation coefficient were extracted. ResultsThree types of muscle synergy patterns were identified on the affected side and contralateral side of the observation group, and the control group. For Synergy 1, the weight of biceps femoris was higher on both the affected and contralateral sides than in the control group (P < 0.01); the weight of semitendinosus was higher on the affected side than on the contralateral side (P < 0.05). For Synergy 2, the weight of lateral gastrocnemius and soleus were higher on both sides of the observation group than in the control group (P < 0.05). For Synergy 3, the weight of gluteus maximus was lower on the affected side than on the contralateral side and in the control group (P < 0.05); the weight of tibialis anterior was higher on the affected side than on the contralateral side and in the control group (P < 0.001); the weight of vastus lateralis was lower on the contralateral side than on the affected side and in the control group (P < 0.001). In the observation group, the peak activation time and stop time of Synergy 3 were delayed bilaterally (P < 0.05). ConclusionPatients after ACLR exhibit altered structural and temporal characteristics of lower limb muscle synergy during jump task. The hamstrings show increased participation during the pre-activation phase, and calf muscles undertake more stabilizing functions during the landing phase.

BACKGROUND:Due to proprioceptive deficits,athletes after anterior cruciate ligament reconstruction may use compensatory stabilization strategies to reweight sensation toward more reliable visual stimuli.However,it is unclear how interference with visual information affects lower limb biomechanics.OBJECTIVE:To investigate the effects of visual interference on the kinematic and dynamic characteristics of lower limbs during single-leg landing in athletes after anterior cruciate ligament reconstruction and healthy athletes.METHODS:Twenty athletes undergoing anterior cruciate ligament reconstruction and 20 healthy athletes were recruited and randomly subjected to two different visual conditions:eyes open and visual interference.They completed single-leg landing under the two visual conditions.Visual interference was performed using stroboscopic glasses with a frequency of 3 Hz,i.e.0.1 seconds with eyes open and 0.233 seconds with eyes closed.The kinematic parameters of the affected/dominant lower limbs were collected using an infrared high-speed motion capture system(200 Hz),and the kinetic parameters of the lower limbs were collected using a three-dimensional force platform(1 000 Hz).Two-way repeated measures analysis of variance was used to determine the effects of group and visual condition on kinematic and kinetic variables.RESULTS AND CONCLUSION:(1)Compared with the eyes-open condition,the knee valgus angle(P=0.026)and ankle varus angle(P=0.006)of athletes undergoing anterior cruciate ligament reconstruction and healthy athletes at the initial landing moment under visual interference conditions significantly increased.(2)Compared with the eyes-open condition,visual interference increased the knee valgus angle at the peak knee flexion moment in athletes after anterior cruciate ligament reconstruction(P<0.001),but it did not significantly increase the knee valgus angle in healthy athletes(P=0.527).(3)Compared with the eyes-open condition,under visual interference conditions,the hip extension moment of athletes udnergoing anterior cruciate ligament reconstruction and healthy athletes at the peak knee flexion moment was significantly increased(P=0.047),and the knee extension moment was significantly reduced(P=0.001).To conclude,visual interference increases knee valgus and ankle varus angles in athletes undergoing anterior cruciate ligament reconstruction and healthy athletes,which may increase the risks of anterior cruciate ligament injury/secondary injury and lateral ankle sprain.In addition,visual interference causes compensatory strategies of proximal load shiftin the sagittal plane in athletes.

BACKGROUND:Due to proprioceptive deficits,athletes after anterior cruciate ligament reconstruction may use compensatory stabilization strategies to reweight sensation toward more reliable visual stimuli.However,it is unclear how interference with visual information affects lower limb biomechanics.OBJECTIVE:To investigate the effects of visual interference on the kinematic and dynamic characteristics of lower limbs during single-leg landing in athletes after anterior cruciate ligament reconstruction and healthy athletes.METHODS:Twenty athletes undergoing anterior cruciate ligament reconstruction and 20 healthy athletes were recruited and randomly subjected to two different visual conditions:eyes open and visual interference.They completed single-leg landing under the two visual conditions.Visual interference was performed using stroboscopic glasses with a frequency of 3 Hz,i.e.0.1 seconds with eyes open and 0.233 seconds with eyes closed.The kinematic parameters of the affected/dominant lower limbs were collected using an infrared high-speed motion capture system(200 Hz),and the kinetic parameters of the lower limbs were collected using a three-dimensional force platform(1 000 Hz).Two-way repeated measures analysis of variance was used to determine the effects of group and visual condition on kinematic and kinetic variables.RESULTS AND CONCLUSION:(1)Compared with the eyes-open condition,the knee valgus angle(P=0.026)and ankle varus angle(P=0.006)of athletes undergoing anterior cruciate ligament reconstruction and healthy athletes at the initial landing moment under visual interference conditions significantly increased.(2)Compared with the eyes-open condition,visual interference increased the knee valgus angle at the peak knee flexion moment in athletes after anterior cruciate ligament reconstruction(P<0.001),but it did not significantly increase the knee valgus angle in healthy athletes(P=0.527).(3)Compared with the eyes-open condition,under visual interference conditions,the hip extension moment of athletes udnergoing anterior cruciate ligament reconstruction and healthy athletes at the peak knee flexion moment was significantly increased(P=0.047),and the knee extension moment was significantly reduced(P=0.001).To conclude,visual interference increases knee valgus and ankle varus angles in athletes undergoing anterior cruciate ligament reconstruction and healthy athletes,which may increase the risks of anterior cruciate ligament injury/secondary injury and lateral ankle sprain.In addition,visual interference causes compensatory strategies of proximal load shiftin the sagittal plane in athletes.

Objective To analyze the relevant factors of early warning in emergency patients with high risk of acute sores, explore the application value of transcutaneous oxygen pressure(TcPO2) and transcutaneous carbon dioxide pressure(TcPCO2)monitoring in the early warning of emergency patients with pressure ulcers. Methods This was a study of 186 consecutive emergency patients who were under care in the emergency department. The transcutaneous oxygen/carbon dioxide pressure monitor was used in monitoring the oxygen saturation of the skin of sacrococcygeal region and the chest. Meanwhile,the Braden scale was used in assessing risk factors for pressure ulcers and the receiver operating characteristic curve (ROC curve) was applied to evaluate the early prediction of pressure sore with TcPO 2/TcPCO2 monitor. Results Implementing the logistic regression model with six indicators, this research concluded that TcPO2 CV and PO2 were independent risk factors for the development of Braden scale in patients with high risk. The area under the ROC curve showed that TcPO2 CV had a excellent predictive value for the high-risk group and determined its cut-off value to be 20％. Which means patient with both a value of TcPO2CV over 20％ and a high risk of Braden scale had a larger possibility of pressure ulcers. Conclusions TcPO2 CV was an independent risk factor for patients under emergency care to develop pressure ulcers. A value of TcPO2CV over 20％indicated a high risk of pressure ulcers.