BACKGROUND:The asymmetrical biomechanical environment of adolescent idiopathic scoliosis can lead to further wedge deformation of the vertebral body,which may affect cardiopulmonary function and compress nerves in severe cases.Adolescent idiopathic scoliosis with different degrees of scoliosis should be treated with exercise,bracing,and surgery.However,the mechanical mechanism of selecting an orthopedic approach remains unclear due to the individual variability of patients.OBJECTIVE:To investigate the biomechanical mechanism of different orthopedic modalities for the treatment of adolescent idiopathic scoliosis to provide a basis for clinical selection of treatment modalities based on the spine model of adolescent idiopathic scoliosis patients.METHODS:Based on the CT images of an adolescent idiopathic scoliosis patient,a scoliosis model(C7-L5)was reconstructed in Mimics software in three dimensions,and lateral thrust force was applied at the T8/T9 thorax and vertical distraction force was applied over the C7 vertebra with the magnitude of 20,40,60,80,100,and 120 N.The intervertebral disc stress and vertebral displacement in concave and convex sides,and Cobb angle of the spine were analyzed under two orthopedic modalities.RESULTS AND CONCLUSION:(1)With lateral thrust,there was no significant change in the C7T1-T7T8 intervertebral disc.The concave and convex stress of T7T8-L4L5 segment decreased first and then increased with the increase of lateral thrust force.The correction effect of lateral thrust on the segment near T8T9 was obvious and weakened with the extension of the segment to the cephalic and caudal ends.At 120 N of lateral thrust,the thoracic Cobb angle changed from 53.2° to 32.5° and the lumbar Cobb angle changed from 50.2° to 43.9°.(2)With the vertical distraction,the thoracic intervertebral disc stresses first decreased and then increased,and all the lumbar disc stresses decreased.The C7 displacement was the most obvious,and the correction effect gradually diminished with the segment extended to the caudal end.At a vertical distraction force of 120 N,the thoracic Cobb angle changed from 53.2° to 39.4° and the lumbar Cobb angle changed from 50.2° to 47.6°.(3)It is concluded that both orthopedic modalities provide improvement in the degree of scoliosis,with the thoracic correction being greater than the lumbar correction.Also,the asymmetric stress distribution on the concave and convex sides is improved,which contributes to normal bone growth.A vertical distraction approach is appropriate for larger Cobb angles,and a lateral thrust approach is appropriate for smaller Cobb angles.The results of this study help to understand the mechanism of spinal orthosis and provide a theoretical basis for the choice of orthopedic approach.

Objective:To compare the effectiveness of TightRope system and plate-screw internal fixation in the treatment of avulsion fractures of the posterior calcaneal tuberosity of Beavis type Ⅱ.Methods:A retrospective study was conducted to analyze the clinical data of the 42 patients with avulsion fracture of the posterior calcaneal tuberosity of Beavis type Ⅱ who had undergone surgical treatment at Foot-ankle Surgery Center, The Fourth Hospital of Wuhan from January 2019 to January 2024. There were 25 males and 17 females, with an age of (64.4±10.1) years. The left side was affected in 23 cases and the right side in 19 cases. The patients were divided into 2 groups according to their different ways of internal fixation: a TR group of 22 cases subjected to open reduction and internal fixation with TightRope system and a PS group of 20 cases subjected to open reduction and plate-screw internal fixation. The operation time, bone healing time, complications, and American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, MOS item short form health survey (SF-36) score and visual analogue scale (VAS) at 12 months after operation were compared between the 2 groups.Results:There were no significant differences in the preoperative clinical baseline data between the 2 groups, indicating comparability ( P>0.05). All patients were followed up for (19.9±3.1) months. In the TR group, the operation time [(59.3±7.1) min] was significantly shorter than that in the PS Group [(72.1±10.7) min], the incidence of complications [4.5% (1/22)] significantly lower than that in the PS group [35.0% (7/20)], and the AOFAS ankle-hindfoot score [(83.5±8.2) points] and SF-36 scale score [(88.2±5.3) points] were significantly higher than those in the PS Group [(64.4±10.8) points and (78.6±11.2) points] (all P<0.05). There was no significant difference in the bone healing time or VAS pain score at 12 months after operation between the 2 groups ( P<0.05). Conclusions:In the treatment of avulsion fractures of the posterior calcaneal tuberosity of Beavis type Ⅱ, compared with the plate-screw internal fixation, the TightRope system can shorten operation time, improve functional recovery, and reduce complications.

BACKGROUND:The asymmetrical biomechanical environment of adolescent idiopathic scoliosis can lead to further wedge deformation of the vertebral body,which may affect cardiopulmonary function and compress nerves in severe cases.Adolescent idiopathic scoliosis with different degrees of scoliosis should be treated with exercise,bracing,and surgery.However,the mechanical mechanism of selecting an orthopedic approach remains unclear due to the individual variability of patients.OBJECTIVE:To investigate the biomechanical mechanism of different orthopedic modalities for the treatment of adolescent idiopathic scoliosis to provide a basis for clinical selection of treatment modalities based on the spine model of adolescent idiopathic scoliosis patients.METHODS:Based on the CT images of an adolescent idiopathic scoliosis patient,a scoliosis model(C7-L5)was reconstructed in Mimics software in three dimensions,and lateral thrust force was applied at the T8/T9 thorax and vertical distraction force was applied over the C7 vertebra with the magnitude of 20,40,60,80,100,and 120 N.The intervertebral disc stress and vertebral displacement in concave and convex sides,and Cobb angle of the spine were analyzed under two orthopedic modalities.RESULTS AND CONCLUSION:(1)With lateral thrust,there was no significant change in the C7T1-T7T8 intervertebral disc.The concave and convex stress of T7T8-L4L5 segment decreased first and then increased with the increase of lateral thrust force.The correction effect of lateral thrust on the segment near T8T9 was obvious and weakened with the extension of the segment to the cephalic and caudal ends.At 120 N of lateral thrust,the thoracic Cobb angle changed from 53.2° to 32.5° and the lumbar Cobb angle changed from 50.2° to 43.9°.(2)With the vertical distraction,the thoracic intervertebral disc stresses first decreased and then increased,and all the lumbar disc stresses decreased.The C7 displacement was the most obvious,and the correction effect gradually diminished with the segment extended to the caudal end.At a vertical distraction force of 120 N,the thoracic Cobb angle changed from 53.2° to 39.4° and the lumbar Cobb angle changed from 50.2° to 47.6°.(3)It is concluded that both orthopedic modalities provide improvement in the degree of scoliosis,with the thoracic correction being greater than the lumbar correction.Also,the asymmetric stress distribution on the concave and convex sides is improved,which contributes to normal bone growth.A vertical distraction approach is appropriate for larger Cobb angles,and a lateral thrust approach is appropriate for smaller Cobb angles.The results of this study help to understand the mechanism of spinal orthosis and provide a theoretical basis for the choice of orthopedic approach.

Objective:To compare the effectiveness of TightRope system and plate-screw internal fixation in the treatment of avulsion fractures of the posterior calcaneal tuberosity of Beavis type Ⅱ.Methods:A retrospective study was conducted to analyze the clinical data of the 42 patients with avulsion fracture of the posterior calcaneal tuberosity of Beavis type Ⅱ who had undergone surgical treatment at Foot-ankle Surgery Center, The Fourth Hospital of Wuhan from January 2019 to January 2024. There were 25 males and 17 females, with an age of (64.4±10.1) years. The left side was affected in 23 cases and the right side in 19 cases. The patients were divided into 2 groups according to their different ways of internal fixation: a TR group of 22 cases subjected to open reduction and internal fixation with TightRope system and a PS group of 20 cases subjected to open reduction and plate-screw internal fixation. The operation time, bone healing time, complications, and American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, MOS item short form health survey (SF-36) score and visual analogue scale (VAS) at 12 months after operation were compared between the 2 groups.Results:There were no significant differences in the preoperative clinical baseline data between the 2 groups, indicating comparability ( P>0.05). All patients were followed up for (19.9±3.1) months. In the TR group, the operation time [(59.3±7.1) min] was significantly shorter than that in the PS Group [(72.1±10.7) min], the incidence of complications [4.5% (1/22)] significantly lower than that in the PS group [35.0% (7/20)], and the AOFAS ankle-hindfoot score [(83.5±8.2) points] and SF-36 scale score [(88.2±5.3) points] were significantly higher than those in the PS Group [(64.4±10.8) points and (78.6±11.2) points] (all P<0.05). There was no significant difference in the bone healing time or VAS pain score at 12 months after operation between the 2 groups ( P<0.05). Conclusions:In the treatment of avulsion fractures of the posterior calcaneal tuberosity of Beavis type Ⅱ, compared with the plate-screw internal fixation, the TightRope system can shorten operation time, improve functional recovery, and reduce complications.

BACKGROUND:Ankylosing spondylitis is a chronic inflammatory disease with chronic rheumatic immunity.Soft tissue ossification and fusion and spinal stiffness can cause biomechanical changes. OBJECTIVE:To reconstruct the lumbar-sacral intervertebral disc in ankylosing spondylitis patients with lumbar kyphosis by finite element analysis,and to study the range of motion of each segment of T11-S1 and the biomechanical characteristics of annulus fibrosus and nucleus pulposus. METHODS:The imaging data were obtained from an ankylosing spondylitis patient with lumbar kyphosis.The original CT image data of continuously scanned spine were imported into Mimics 21.0 in DICOM format,and T11-S1 was reconstructed respectively.The established model was imported into 3-Matic software in the format of"Stl"to reconstruct the intervertebral disc,and the fibrous intervertebral disc model was obtained.The improved model was further imported into Hypermesh software,and the vertebra,nucleus pulposus,annulus fibrosus and ligament were mesh-divided.After the material properties were given,the model was imported into ABAQUS software to observe the range of motion of each vertebral body in seven different working conditions of T11-S1,and analyze the biomechanical characteristics of each segment of annulus fibrosus and nucleus pulposus. RESULTS AND CONCLUSION:(1)The range of motion of L1 vertebrae was higher than that of other vertebrae under six different working conditions:extension,forward flexion,rotation(left and right),and lateral flexion(left and right).The maximum range of motion was 2.18° during L1 vertebral flexion,and the minimum range of motion was 0.12° during L5 vertebral extension.(2)The annular fiber flexion at L2-L3 segments was greater than the extension(P<0.05),and the annular fiber flexion at L3-L4 and L4-L5 segments was less than the extension(P<0.05).The left rotation of L1-L2 annular fibers was greater than the right rotation(P<0.05).The left flexion of the annulus was greater than the right flexion in L1-L2,L2-L3,L3-L4,L4-L5 and L5-S1 segments(P<0.05).(3)The nucleus pulposus stresses of T11-L12,L1-L2,L2-L3,L3-L4 and L4-L5 segments in forward flexion were greater than in extension(P<0.05).The left rotation of T12-L1 and L3-L4 segments was smaller than the right rotation(P<0.05),and that of T11-T12,L1-L2,and L2-L3 segments was larger than the right rotation(P<0.05).The left flexion was larger than the right flexion in the T11-S1 segment.(4)It is concluded that in ankylosing spondylitis patients with lumbar kyphosis,the minimum range of motion of the vertebral body is located at the L5 vertebral body in extension.To prevent fractures,it is recommended to avoid exercise in the extension position.During the onset of lumbar kyphosis in patients with ankylosing spondylitis,the maximum stress of the annulus fibrosus and nucleus pulposus is located in the L1-L2 segment,which is fixed and will not alter with the change of body position.The late surgical treatment and correction of deformity should focus on releasing the pressure of the annulus fibrosus and nucleus pulposus in this segment to avoid the rupture of the annulus fibrosus and the injury of the nucleus pulposus.

BACKGROUND:Ankylosing spondylitis is a progressive inflammation of spinal stiffness deformity caused by tissue ossification and fibrosis.The posture of ankylosing spondylitis patients is abnormal and their activities are limited that minor injuries can lead to thoracolumbar fractures.Traditional medical image observation limits doctors'preoperative decision planning and postoperative disease prevention for ankylosing spondylitis treatment. OBJECTIVE:Based on the spinal model of ankylosing spondylitis patients before and after posterior spinal cancellous ossification osteotomy("Y"osteotomy for short),to explore the biomechanical changes of"Y"osteotomy and fixation in the treatment of ankylosing spondylitis. METHODS:Based on the preoperative and postoperative CT images of an ankylosing spondylitis patient who went to the Second Affiliated Hospital of Inner Mongolia Medical University,a three-dimensional spine model(T11-S1)before and after"Y"osteotomy(L3 osteotomy)was reconstructed in Mimics 19.0 software.A 7.5 Nm torque was applied to the top of T11 vertebral body to simulate the movement of the spine under six conditions:flexion,extension,left bending,right bending,left rotation and right rotation.Finally,the range of motion of each vertebral body,the stress of each intervertebral disc,and the stress of the screw rod system were simulated. RESULTS AND CONCLUSION:(1)After"Y"type osteotomy and posterior fixation,the range of motion of all vertebrae in the spine decreased,and the loss rate of upper vertebrae was large(L1:77.95%).(2)The maximum stress of the spinal intervertebral disc before operation occurred at the L1-L2 segment(0.55 MPa),and the maximum stress of the spinal intervertebral disc after operation occurred at the T11-T12 segment(0.50 MPa),and the stress of intervertebral disc below T12 was far less than that before operation.(3)The maximum stress of the screw rod system(166.67 MPa)occurred in the upper and middle segments of the rod body and the root of the pedicle screw.(4)In conclusion,the"Y"type posterior fixation operation enhances the stability of the spine and reduces the range of motion of the spine.The vertebral body decompression of the fixed segment is great and the stress-shielding phenomenon of the lower vertebral body is significant.The stiffness of the rod body and the stress concentration area of the pedicle screw should be strengthened to avoid the fracture of the rod caused by stress fatigue.

BACKGROUND:High ankle sprain is easily missed and leads to ankle dysfunction.Arthroscopy can detect hidden high ankle sprain.Suture-button elastic fixation can restore the biomechanical stability of the distal tibiofibular syndesmosis. OBJECTIVE:To explore the clinical efficacy of Suture-button elastic fixation for high ankle sprain under ankle arthroscopy. METHODS:A retrospective analysis was performed on 40 cases of high ankle sprain patients treated with Suture-button elastic fixation under ankle arthroscopy from August 2019 to August 2021 in the Department of Foot and Ankle Surgery,Wuhan Fourth Hospital.All patients underwent Suture-button elastic fixation.The American Orthopedic Foot and Ankle Society function score,Visual Analog Scale pain score,ankle range of motion,preoperative imaging data,and arthroscopic tibiofibular syndesmosis separation degree were recorded.Meislin criteria were used to evaluate the curative effect and postoperative complications were recorded. RESULTS AND CONCLUSION:(1)40 patients were followed up for 16-48 months after operation.(2)At the last follow-up,American Orthopedic Foot and Ankle Society score was(88.95±6.64 points).Visual Analog Scale score was(1.78±1.23 points).Ankle dorsiflexion range of motion was(33.50±5.79 degrees).Ankle plantarflexion range of motion was(34.50±5.97 degrees).There were statistically significant differences before and after surgery(P<0.05).(3)There was a low positive correlation between the radiographic separation index and the degree of arthroscopic separation(r=0.612,P<0.01).(4)The curative effect was evaluated by Meislin standard,with an excellent and good rate of 95%(38/40).Postoperative ankle joint pain was relieved,and ankle joint activities were significantly improved.(5)During the follow-up period,all patients had no nerve injury or incision infection.In 1 patient,the internal fixation was removed due to skin irritation and squatting sensation after operation.(6)It is concluded that Suture-button elastic fixation for high ankle sprain is effective under ankle arthroscopy in restoring ankle function and maintaining joint stability without the need for secondary removal,and it is worth clinical application.

Objective:To investigate the efficacy of arthroscopic anatomical reconstruction of the ligament with autologous semitendinosus tendon in the treatment of chronic lateral ankle instability (CLAI) complicated with multiple ligament laxity.Methods:A retrospective study was conducted to analyze the 34 patients with CLAI plus multiple ligament laxity who had been treated at Foot and Ankle Surgery Center, The Fourth Hospital of Wuhan from March 2014 to December 2021. They were 8 males and 26 females with an age of (32.2±5.6) years. The patients were divided into 2 groups based on their treatment methods. A reconstruction group of 20 cases were treated by arthroscopic reconstruction of the ligament with autologous semitendinosus tendon while a repair group of 14 cases treated by arthroscopic repair of the ligament with the modified Brostr?m procedure. The 2 groups were compared in terms of surgical time, and the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score, visual analog scale (VAS) pain score, talar tilt (TT), anterior translation of the talus (ATT), and complications at the last follow-up.Results:The 2 groups were comparable because there were no statistically significant differences in the general data, AOFAS ankle-hindfoot score, VAS pain score, TT, or ATT before surgery between the 2 groups ( P > 0.05). The surgical time for the reconstruction group [(97.5±11.4) min] was significantly longer than that for the repair group [(53.6±10.7) min] ( P < 0.05). All the 34 patients were followed up for (35.4±3.5) months. The TT, ATT, AOFAS ankle-hindfoot score, and VAS pain score at the last follow-up were all significantly improved compared with the preoperative values in both groups ( P < 0.05). The AOFAS ankle-hindfoot score [(90.6±3.6) points], TT (6.0°±1.5°), and ATT [(3.6±1.4) mm] at the last follow-up in the reconstruction group were all significantly better than those in the repair group [(84.1±11.0) points, 8.6°±4.3°, and (6.6±4.1) mm] ( P < 0.05). There was no statistically significant difference in the VAS pain score between the 2 groups at the last follow-up ( P > 0.05). All incisions healed at one stage without such complications as nerve or vascular injury. CLAI recurrence occurred in 5 cases in the repair group, significant worse than that in the reconstruction group (no recurrence) ( P=0.015). Conclusion:In the treatment of CLAI complicated with multiple ligament laxity, arthroscopic anatomical reconstruction of the ligament with autologous semitendinosus tendon can effectively improve ankle function, enhance ankle stability, and reduce recurrence of the condition.

Objective:To investigate the value of 3D CT reconstruction in diagnosis of chronic lateral ankle instability (CLAI) combined with syndesmotic diastasis (SD).Methods:A retrospective study was conducted to analyze the clinical data of 160 patients with CLAI who had been examined by arthroscopy from January 2018 to September 2022 at Department of Foot and Ankle Surgery, Wuhan Fourth Hospital. There were 64 males and 96 females with an age of (39.8±12.6) years. Eighty-one left and 79 right feet were affected; the time from injury to surgery was (27.3±11.6) months. The patients were divided into a widened interval group and a normal interval group according to the syndesmotic width measured, with 2 mm as a critical value. After preoperative 3D CT reconstruction, the differences in anterior tibiofibular distance, posterior tibiofibular distance, the narrowest tibiofibular distance, fibular translation, fibular rotation, and syndesmotic area (SA) were compared between the 2 groups. Univariate and multivariate analyses were performed successively to identify the risk factors. The receiver operating characteristic (ROC) curve was used to identify the best predictive factor and critical value. According to the findings of previous research, the above analyses were repeated to determine the best predictive factor and critical value respectively in the sex subgroup, fibular morphology subgroup and incisura feature subgroup.Results:The binary logistic regression showed that SA was a risk factor for CLAI combined with SD ( OR=1.196, 95% CI: 1.122 to 1.275, P < 0.001). The ROC curve revealed an area under curve of 0.847 and the difference critical value of 22.06 mm 2 that indicated a sensitivity of 80.4% and a specificity of 78.9%, respectively. Subgroup analyses showed that SA was suitable for male and female patients and patients with different fibular morphologies and incisura features but the difference critical values were different. Conclusion:In 3D CT reconstruction, measurement of SA may help the diagnosis of CLAI combined with SD.