We developed a three-dimensional finite element model of the shoulder glenohumeral joint after shoulder arthroplasty including humerus shaft, scapular, scapular cartilage and eight muscles, while each of the muscles was simulated with 50 spring elements. To reduce the element number and improve the analytical precision, we used mixed tetrahedral and hexahedral elements in the model. We then used the model to calculate the biomechanics of the shoulder glenohumeral joint after hemiarthroplasty during humeral external rotation. Results showed that the maximum joint reaction force was 374.72 N and the maximum contact stress was 6.573 MPa together with the contact areas at 40° external rotation. These might be one of the reasons for prosthetic disarticulation, and would provide theoretical bases to prosthetic design.
ObjectiveTo evaluate the biomechanical characteristics and effectiveness of repairing anteroinferior tibiofibular ligament and fixing the posterior malleolar fracture in reconstructing syndesmotic stability after ankle fracture of pronation-external rotation type (PER) stage IV. MethodsTwenty-four normal lower extremity cadaver specimens were collected and made into intact ankle specimens. A MTS Bionix 858 test system was used to measure the maximum rotation of the foot under a static axial load of 150 N, internal rotation torque to the tibia at a rate of 1°/second and 4 N·m torque. Then a fracture of PER stage IV model was established in each specimen. Internal fixation of lower tibiofibular ligament union was performed by screws in group A, fixation of posterior malleolar fractures in group B, fixing posterior malleolar fracture combined with repairing anteroinferior tibiofibular ligament in group C (8 specimens each group). Then the maximum rotation of the foot was measured under the same condition, and the syndesmotic stability was calculated. Between July 2009 and September 2012, 32 patients with ankle fracture of PER stage IV were treated. There were 19 males and 13 females with an average age of 35 years (range, 20-63 years). The locations were the left ankle in 14 cases and the right ankle in 18 cases. The time from injury to admission was 3.5 hours on average (range, 1-72 hours). Open reduction and plate compression internal fixation were performed in fibula, and medial malleolus was fixed by conpression screws, then anteroinferior tibiofibular ligament was mended and posterior malleolar fracture was fixed by screws. ResultsThe preservation rates of syndesmotic stability after repair were 46.2%±12.3%, 62.6%±10.7%,and 66.5%±12.6% in groups A, B,and C, respectively; groups B and C were significantly superior to group A (P<0.05),but no significant difference was found between groups B and C (P>0.05). All patients achieved wound healing by first intention, and were followed up 12-24 months (mean,15 months). All fractures healed,with an average healing time of 11.2 weeks (range, 10-14 weeks) on the X-ray films. No seperation of inferior tibiofibular syndesmosis was observed during the follow-up period. American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score was 88.4 on average (range, 61-98) at last follow-up; the results were excellent in 13 cases,good in 15 cases, and fair in 4 cases, with an excellent and good rate of 87.5%. ConclusionIn patients with ankle fracture of PER stage IV, a combination of fixing the posterior malleolar fracture and repairing anteroinferior tibiofibular ligament can reconstruct syndesmotic stability effectively.
ObjectiveTo evaluate the difference between using and not using syndesmotic screw to treat pronation external rotation (PER) ankle fracture combined with separation of distal tibiofibular syndesmosis. MethodsBetween April 2011 and October 2014, 46 cases of PER ankle fracture combined with separation of distal tibiofibular syndesmosis were treated, and syndesmotic screw was used in 24 cases (fixation group) and syndesmotic screw was not used in 22 cases (non-fixation group). There was no significant difference in gender, age, weight, cause of injury, side, injury to operation time, and fracture type between 2 groups (P > 0.05). The time for full weight-bearing, fracture healing time, and complications were recorded after operation. Anteroposterior and lateral X-ray films were taken to measure the tibiofibular overlap (TBOL) and tibiofibular clear space (TBCS). Baird-Jackson score was used to evaluate functional recovery of the ankle. ResultsAll incision healed by first intention without complications. The cases were followed up 13-18 months (mean, 15.2 months) in 2 groups. The time for full weight-bearing was 8-12 weeks (median, 11 weeks) in fixation group, which was significantly later than that in non-fixation group (range, 6-10 weeks; median, 8 weeks) (Z=-5.049, P=0.000). X-ray examination showed reduction of separation of distal tibiofibular syndesmosis. All fractures healed. The fracture healing time was (13.83±1.37) weeks in fixation group, and was (13.91±1.31) weeks in non-fixation group, showing no significant difference (t=-0.191, P=0.945). No separation of distal tibiofibular syndesmosis, delayed union, nonunion, loosening, or breakage of fixation devices was observed in 2 groups. There was no significant difference in TBOL, TBCS, Baird-Jackson score and the excellent and good rate between 2 groups (P > 0.05). ConclusionIf the medial, lateral, and posterior structures of the ankle could be repaired according to injury, no significant influence on functional outcome of ankle or radiologic findings could be detected whether syndesmotic fixation is given or not in treating PER ankle fracture (exclude Maisonneuve fracture) combined with separation of distal tibiofibular syndesmosis.
Objective To summarize the short-term effectiveness of the surgical treatment for grade III pronation-external rotation ankle fractures. Methods Between October 2011 and May 2015, 36 patients with pronation-external rotation ankle fractures (grade III) were treated with internal fixation and repair of the anterior lower tibiofibular ligament, including 21 males and 15 females with an average age of 45.2 years (range, 21-72 years). Injury was caused by sprain in 19 cases, by traffic accident in 6 cases, and by falling from height in 11 cases. All patients had closed fractures, with no blood vessel and nerve injury. The locations were the left ankle in 13 cases and the right ankle in 23 cases. The time from injury to operation was 3 to 10 days (mean, 6.5 days). At last follow-up, ankle function was evaluated by American Orthopaedic Foot and Ankle Society (AOFAS) ankle-foot score, and the improvement of pain was evaluated by visual analogue scale (VAS). Results Primary healing of incision was obtained in all patients, no incision infection and skin necrosis occurred. Twenty-eight patients were followed up 12-36 months (mean, 17.5 months). X-ray films showed bone union was achieved within 2.6-5 months (mean, 3.2 months). No fracture of internal fixation and disruption of tibiofibular diastasis occurred. At last follow-up, according to AOFAS score for ankle function evaluation, the pain score was 36.3±2.9, the function score was 44.3±3.2, the ligament condition score was 9.2±0.5, and the total score was 89.8±6.6; the results were excellent in 11 cases, good in 15 cases, and fair in 2 cases. VAS score was 1.6±0.5. The range of motion of the ankle was (13±5)° in dorsiflexion and (38±9)° in planteroflexion. Conclusion Repair of anterior tibial ligament is an effective method to treat tibiofibular diastasis injury in the surgical treatment of grade III pronation-external rotation ankle fractures, with convenient operation, and satisfactory short-term effectiveness.
ObjectiveTo investigate the safety, feasibility, and efficacy of full repair strategy under small incision in the treatment of closed Lauge-Hansen pronation-external rotation type Ⅳ ankle fracture.MethodsThe clinical data of 57 patients with closed Lauge-Hansen pronation-external rotation type Ⅳ ankle fracture treated by full repair strategy (fracture, ligament, and cartilage repair) under small incision between January 2012 and January 2017 were retrospectively analyzed. There were 31 males and 26 females, with an average age of 41.1 years (range, 21-65 years). The causes of injury included traffic accident injury in 33 cases and falling injury in 24 cases. All of them were closed fractures, including 20 cases of medial malleolus fracture, 37 cases of complete medial malleolus but deep and shallow rupture of deltoid ligament. The average time from injury to admission was 9.6 hours (range, 3-34 hours). The quality of reduction of distal tibial articular surface (based on Ketz-Sanders standard), the reduction of tibiofibular syndesmosis (the anterior and posterior distances of distal tibiofibular syndesmosis and the lateral ankle twist angle measured by CT scan at 10 mm above the ankle joint line), and the fracture healing were evaluated. The medial clear space (MCS), tibiofibular clear space (TFCS), and distal fibular tip to lateral process of talus (DFTL) were measured on the X-ray films of ankle points. Before and after operation, the pain and functional improvement of ankle joint were evaluated by visual analogue scale (VAS) score and American Orthopedic Foot and Ankle Association (AOFAS) score, and the activities of ankle dorsiflexion and plantar flexion were measured.ResultsThree cases with osteochondral lesions of the talus were found during operation and all were treated with microfracture techniques. Tournament paralysis occurred in 2 cases after anesthesia. The surgical incisions healed by first intention in all patients. All the 57 patients were followed up 24-84 months, with an average of 38.6 months. All patients achieved bone healing without bone nonunion and malunion at 12 months after operation. The reduction quality of distal tibial articular surface was excellent in 56 cases and good in 1 case at 3 months after operation, the excellent and good rate was 100%. There was no significant difference in the MCS, TFCS, DFTL, anterior distance of distal tibiofibular syndesmosis, posterior distance of distal tibiofibular syndesmosis, and lateral ankle twist angle between the affected and healthy sides at 12 months after operation (P>0.05). At last follow-up, the VAS score, AOFAS score, ankle dorsiflexion and plantar flexion activities of the affected side were significantly improved when compared with preoperative ones (P<0.05). Compared with the healthy side, there was no significant difference in ankle dorsiflexion and plantar flexion activities (P>0.05).ConclusionFull-repair strategy under small incisions for the treatment of Lauge-Hansen pronation-external rotation type Ⅳ ankle fracture is effective and safe. It can not only reduce wound complications, but also improve the quality of joint reduction of the ankle joint and distal tibiofibular syndesmosis. Full repair of ligaments and cartilage can improve the internal fixation strength and joint stability of the ankle joint.