Effects of visual restoration on dynamic plantar pressure features in elder individuals / 北京大学学报(医学版)

OBJECTIVE@#To analyze the effects of visual restoration after cataract surgery on plantar pressure and biomechanics of foot in elder individuals.@*METHODS@#Thirty-two patients [male/female 5/27, (70.1±5.2) years old] with age-related cataract were recruited between October 2016 and December 2019. The footscan system was employed to record the data of plantar pressure during level walking before and 1-month after the cataract surgery. Parameters of peak pressure (PP), impulse (I), pressure-time integral (PTI) and time to peak pressure (TPP) from the regions of the 1st toe (T1), 2nd to 5th toes (T2-5), 1st to 5th metatarsal heads (M1-M5), midfoot (MF), medial hindfoot (HM) and lateral hindfoot (HL) were analyzed respectively.@*RESULTS@#Post-operatively, the visual function was effectively reconstructed with improved visual acuity in both eyes (Z=-4.878, -4.801; P < 0.001). The PP (t=2.266, P=0.031) and I (t=2.152, P=0.039) values in M2 region on the dominant side (right foot) increased statistically at post-operative phase, while the changes of pressure and temporal para-meters in other regions remained stable. There was laterality in plantar pressure at pre-operative phase, manifested as greater PP values in M1, M2, MF, and HM regions on the dominant sides (t=-2.414, -2.478, -2.144, -5.269; P < 0.05), greater PP values in T1, M3, M5 and HL regions on the non-dominant sides (t=4.830, 3.155, 2.686, 3.683; P < 0.05), greater I values in M1, MF, and HM regions on the dominant sides (t=-2.380, -2.185, -5.320; P < 0.05) and greater I values in T1, M3, M5 and HL regions on the non-dominant sides (t=4.489, 2.247, 2.838, 3.992; P < 0.05). post-operatively, the pressure tended to be compatible between the two sides in regions of M3 and MF, while the magnitude of laterality in regions of M1 (ZPP△= -2.721, P=0.007; ZI△=-2.581, P=0.010), M2 (ZPP△=-2.674, P=0.007; ZI△=-2.375, P=0.018) and M5 (ZPP△=1.991, P=0.046; ZI△=2.150, P=0.032) was further increased.@*CONCLUSION@#Changes in plantar pressure after cataract surgery were characterized as increased pressure in the 2nd metatarsal head area on the dominant side. Visual restoration might intensify the laterality in the medial of forefoot on the dominant side and the lateral of forefoot on the non-dominant side.

Changes of electroencephalography power spectrum during joint position perception test after anterior cruciate ligament rupture / 北京大学学报(医学版)

OBJECTIVE@#To measure the electroencephalography (EEG) of the patients with anterior cruciate ligament (ACL) rupture when performing joint position perception movement task, to compare the differences between the ACL rupture side and the unaffected side, to identify the EEG change in the power spectrum caused by the ACL rupture, and to provide evidence for the diagnosis, treatment and rehabi-litation for ACL injury as well as knee instability.@*METHODS@#Sixteen male patients, selected from the Department of Sports Medicine, Peking University Third Hospital from November 2014 to April 2015, with only ACL rupture on one side used isokinetic muscle strength testing equipment were enrolled in the study to perform unilateral active knee joint positional movement and passive knee joint positional movement tasks. EEG was recorded to compare between the affected and unaffected limb of ACL rupture patients when doing single leg movement tasks, including passive knee joint position test and active knee joint position sensation test. The target position of the active knee joint position movement task and the passive knee joint position movement task was 30 degrees of knee flexion.@*RESULTS@#During the passive knee joint position test, there was no significant difference in EEG power spectrum of Delta[F (1, 15)=0.003, P=0.957, ηP2 =0.001], Theta[F (1, 15)=0.002, P=0.962, ηP2 < 0.001], Alpha[F (1, 15)=0.002, P=0.966, ηP2 =0.001], Beta[F (1, 15)=0.008, P=0.929, ηP2 =0.001] at Fz, Cz, and Pz between the affected and unaffected limbs in the ACL patients. During the active knee joint position movement task, the EEG power spectrum of Delta, Theta, Alpha, Beta at Fz and Cz location, on the affected side was significant higher than on the unaffected side.@*CONCLUSION@#This study compared the differences between the ACL rupture side and the unaffected side during active knee position movement task and passive knee position movement task, and identifyied the EEG changes in the power spectrum caused by the ACL rupture, It was found that the central changes caused by unilateral ACL rupture still existed during contralateral (unaffected) side movement. The EEG power spectrum of the affected side during active exercise was significantly higher than that of the unaffected side This study provides new electrophysiological evidence for the study of ACL injury.

Finite element analysis of the graft stresses after anterior cruciate ligament reconstruction / 北京大学学报(医学版)

OBJECTIVE@#To explore the stress distribution characteristics of the graft after anterior cruciate ligament (ACL) reconstruction, so as to provide theoretical reference for the surgical plan of ACL reconstruction.@*METHODS@#Based on 3D MRI and CT images, finite element models of the uninjured knee joint and knee joint after ACL reconstruction were established in this study. The uninjured knee model included femur, tibia, fibula, medial collateral ligament, lateral collateral ligament, ACL and posterior cruciate ligament. The ACL reconstruction knee model included femur, tibia, fibula, medial collateral ligament, lateral collateral ligament, ACL graft and posterior cruciate ligament. Linear elastic material properties were used for both the uninjured and ACL reconstruction models. The elastic modulus of bone tissue was set as 17 GPa and Poisson' s ratio was 0.36. The material properties of ligament tissue and graft were set as elastic modulus 390 MPa and Poisson's ratio 0.4. The femur was fixed as the boundary condition, and the tibia anterior tension of 134 N was applied as the loading condition. The stress states of the ACL of the intact joint and the ACL graft after reconstruction were solved and analyzed, including tension, pressure, shear force and von Mises stress.@*RESULTS@#The maximum compressive stress (6.34 MPa), von Mises stress (5.9 MPa) and shear stress (1.83 MPa) of the reconstructed ACL graft were all at the anterior femoral end. It was consistent with the position of maximum compressive stress (8.77 MPa), von Mises stress (8.88 MPa) and shear stress (3.44 MPa) in the ACL of the intact knee joint. The maximum tensile stress of the graft also appeared at the femoral end, but at the posterior side, which was consistent with the position of the maximum tensile stress of ACL of the uninjured knee joint. More-over, the maximum tensile stress of the graft was only 0.88 MPa, which was less than 2.56 MPa of ACL of the uninjured knee joint.@*CONCLUSION@#The maximum compressive stress, von Mises stress and shear stress of the ACL graft are located in the anterior femoral end, and the maximum tensile stress is located in the posterior femoral end, which is consistent with the position of the maximum tensile stress of the ACL of the uninjured knee joint. The anterior part of ACL and the graft bore higher stresses than the posterior part, which is consistent with the biomechanical characteristics of ACL.

Characteristics and related factors of plantar pressure in the chronic ankle instability individuals / 北京大学学报(医学版)

OBJECTIVE@#To analyze characteristics and related factors of the plantar pressure during the level walking and single leg standing in the chronic ankle instability (CAI) individuals.@*METHODS@#From April 2019, 75 CAI individuals and 40 healthy individuals were enrolled in this study. Both of the static and dynamic plantar pressure were measured during six times level walking and three times single leg standing testing. The data including peak force, time to peak force in various foot contact areas and the time to boundary (TTB) and velocity of center of pressure (COP) were measured and compared between the affected side and the unaffected side and between the CAI cases and the healthy individuals. The correlations between the plantar pressure and the gender, Beighton score, affected side and body mass index (BMI) were analyzed.@*RESULTS@#The characteristics of plantar pressure distribution in the CAI individuals included: (1) During the level walking, the affected side showed the similar pressure contribution as the unaffected side (P>0.05). While compared with healthy individuals, there was a significantly higher peak force in the 5th metatarsal area (t=-3.86, P=0.03) of the affected side, lower peak force in the 1st (t=2.99, P=0.02), 2nd metatarsal head areas (t=2.09, P=0.01) of the affected side, medial hindfoot areas of both sides (affected, t=2.33, P=0.01; unaffected, t=3.74, P=0.02) and toes areass of both sides (affected, t=2.23, P=0.01; unaffected, t=3.28, P=0.02) and a delay to peak force in the 4th metatarsal head area (t=3.33, P=0.01) of the affected side. (2) During the single leg standing, the CAI individuals showed significantly worse balance control in the anterior/posterior direction (P < 0.05) and lateral/medial direction (P < 0.05) compared with the healthy controls, and the affected side had more severe balance control deficit in the lateral/medial direction (P < 0.05). (3) The women (P < 0.05) and the individuals with higher Beighton scores (P < 0.05) showed worse balance control deficit in the lateral/medial direction.@*CONCLUSION@#CAI individuals showed significantly a more lateral shifted plantar distribution during the level walking compared with the healthy individuals and the tendency was worse on the affected sides, and showed worse balance control in the anterior/posterior direction and lateral/medial direction during the single leg standing. The women and those with generalized ligament laxity showed significantly worse balance control.

Effects of Preoperative Isokinetic Eccentric Training and Whey Protein Isolate Supplement on Quadriceps Strength and Knee Function in Patients with Anterior Cruciate Ligament Rupture / 中国医学科学院学报

Objective To explore the effect of preoperative isokinetic eccentric training with or not whey protein isolate supplement before operation on lower limb muscle strength and knee function in patients with anterior cruciate ligament (ACL) rupture. Methods A total of 22 male volunteers aged 18-40 years with ACL rupture were recruited in outpatient service. With randomized block design,subjects were randomly assigned to isokinetic eccentric training (IE) group and isokinetic eccentric training with whey protein isolate supplement (IE+WPI) group. The IE group received isokinetic eccentric training of the injured limb on an isokinetic dynamometer under the guidance of physiatrist in laboratory before operation. There were 3-4 sets per day with 8-10 repetitions for each set,twice a week,with at least one day between sessions. The IE+WPI group were supplied with whey protein isolate 22 g per day on the basis of isokinetic eccentric training,taking breakfast or 30-60 minutes after the training. The intervention lasted for 6 weeks. Isokinetic muscle strength of limbs,the function and laxity of knee,the circumferences of thigh and knee,and the body composition were measured before and after the treatment. Results Compared with baseline,the peak torque (PT) of isokinetic-eccentric contraction (IE group:41.0%,P=0.018;IE+WPI group:46.7%,P=0.008) and the concentric contraction (IE group:29.6%,P=0.018;IE+WPI group:38.9%,P=0.038) of quadriceps in the two training groups significantly increased after isokinetic eccentric training. The Lysholm score increased significantly in IE+WPI group compared with baseline (P=0.018). Conclusions Isokinetic eccentric training before operation for ACL rupture patients can increase the strength of quadriceps and improve the function of knees. Protein isolate supplement can improve such effect.

Factors affecting proprioceptive recovery after anterior cruciate ligament reconstruction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Proprioception plays an important role in knee movements. Since there are controversies surrounding the overall recovery time of proprioception following surgery, it is necessary to define the factors affecting proprioceptive recovery after anterior cruciate ligament (ACL) reconstruction and to investigate the relationship between proprioception and muscle strength.</p><p><b>METHODS</b>A total of 36 patients who had their ACL reconstructed with a semitendinosus/gracilis graft (reconstructed group: 6 months post-surgery) and 13 healthy adults without any knee injury (control group) were included in the study. Knee proprioception was evaluated with a passive reproduction test. Isokinetic strength was measured using the Biodex System. Statistical analysis was used to compare proprioception of the reconstructed group versus the control group, and to define causal factors, including sex, hamstring/quadriceps ratio, and the course of injury before reconstruction. We also investigated the correlation between the passive reproduction error and quadriceps index.</p><p><b>RESULTS</b>There was a significant difference in proprioception between the reconstructed and control groups (P < 0.05). When the course of injury before reconstruction was less than 4 months, there was a linear correlation with proprioception 6 months after the operation (r = 0.713, P < 0.05). There was a positive correlation between post-surgery proprioception and the quadriceps index at 6 months post-surgery.</p><p><b>CONCLUSIONS</b>Impaired knee proprioception is observed 6 months after ACL reconstruction. Within 4 months of injury, early undertaking of reconstruction is associated with better proprioception outcome. Patients with enhanced proprioception have a better quadriceps index.</p>

The effects of continuous passive motion on tendon-bone healing of the tendon autograft used for anterior cruciate ligament reconstruction in a rabbit model / 中华外科杂志

<p><b>OBJECTIVE</b>To study the effects of continuous passive motion on the tendon-bone healing of the semi-tendinous tendon autograft used for anterior cruciate ligament (ACL) reconstruction in rabbits.</p><p><b>METHODS</b>In 12 healthy 8-month-old male rabbits, an ACL reconstruction was performed by using double semi-tendinous tendon autograft. Postoperatively these animals were treated by either continuous passive motion (CPM) or cage activity. Specimens of the grafts were collected at 6, 12, 24 weeks postoperatively. Histological change in the tendon-bone healing was studied by haematoxylin-eosin and toluidine blue.</p><p><b>RESULTS</b>There was more new fiber tissue in the anterior half of the interface. Osteoclasts were most numerous at the tunnel aperture and in the anterior half of the interface. Cartilage in the tendon-bone interface was localized to the posterior aspect of tunnels, the area where compressive stress would be predicted. CPM group developed a denser connective tissue with less vascularity and cellularity. The bone tunnel had more areas with ingrowing denser connective tissue compared with cage activity specimens. With the growth of Sharpery's fibers and fibrocartilage into the interface, a direct ligament insertion was found. In the CPM specimens, the interface tissue was more mature and the direct insertion was broader and more structured.</p><p><b>CONCLUSIONS</b>Compressive stress promotes chondroid formation, and the tension promotes fiber formation. Tendon-bone healing may be optimized by CPM after tendon transplantation into a bone tunnel.</p>