ObjectiveTo clarify the structure and biomechanical characteristics of the dura mater of the cervical, thoracic, and lumbar segments of sheep, in order to provide a theoretical reference for the study of artificial dura mater.MethodsFive adult male white sheep were sacrificed. The dura mater of C5, T10, and L3 planes were obtained. The histological HE staining was used to observe the internal structure and the thickness of dura mater; the inner and outer surfaces morphology of the dura was observed by scanning electron microscopy (SEM); transmission electron microscopy (TEM) was used to observe the internal structure of dura mater and to measure the diameter of collagen fibers in each part of dura mater. The dura mater of C6, C7, T11, T12, L4, and L5 planes were taken for uniaxial biomechanical test, and modulus of elasticity, tensile strength, and elongation at break were measured.ResultsHE staining showed that the thickness of the cervical, thoracic, and lumbar dura mater gradually decreased, and the thickness of the dura mater was (268.19±15.91), (198.16±27.25), (103.74±21.54) μm, respectively, and the differences were significant (P<0.05). SEM observation showed that there were more collagen fibers and fewer cells on the inner surface of the dura mater, while more cells were distributed on the outer surface, and the cells on the inner and outer surface were stretched along the longitudinal axis. TEM observation showed that the collagen fibers in the dura mater were interlaced and arranged in layers. The collagen fibers in the lamina were arranged in the same direction, and the collagen fibers between the lamina were arranged vertically. The diameters of collagen fibers in the cervical, thoracic, and lumbar dura mater were (68.04±21.00), (64.54±20.64), (60.36±19.65) nm, respectively, and the differences were not significant (P>0.05). Uniaxial biomechanical tests results showed that there was no significant difference in modulus of elasticity, tensile strength, and elongation at break between the axial and transverse dura mater of the cervical dura mater (P>0.05); the axial data of thoracic and lumbar segments were significantly larger than the transverse data (P<0.05). The axial modulus of elasticity, tensile strength, and elongation at break of the dura mater of the cervical, thoracic, and lumbar dura mater were significantly different (P<0.05) from the transverse ones, and showing a decreasing trend. Among them, the ratio of axial and transverse modulus of elasticity of cervical and thoracic dura were significantly smaller than that of lumbar segment (P<0.05), and there was no significant difference between cervical segments and thoracic segments (P>0.05).ConclusionThe thickness of dura mater in sheep decreased gradually from head to tail. There are more collagen fibers and fewer cells on the inner surface of dura mater, while the outer surface of dura mater is covered by cells. The collagen fiberboard layers in the dura mater are arranged alternately, and have obvious anisotropic biomechanical characteristics, and the anisotropic biomechanical characteristics get more significant from the head to the tail.
Objective To investigate the effectiveness of sequential plate internal fixation in the correction of Madelung deformity after ulnar osteotomy and shortening. Methods The clinical data of 13 patients with Madelung deformity admitted between September 2015 and July 2021 were retrospectively analyzed. There were 5 males and 8 females with an average age of 18.3 years ranging from 17 to 23 years. The disease duration ranged from 12 to 24 months, with an average of 17 months. Three cases had a clear history of trauma. All patients had external radial deviation deformity and limited movement of the ulnar deviation, and the ulnar impact pain was significant during ulnar deviation movement; 9 patients had limited wrist joint supination movement, and the supination movement was normal. In the first stage, ulnar osteotomy and shortening combined with external fixator were used to correct wrist deformity in 13 patients. After operation, bone transfer was performed 6 times per day, with adjustments made every 4 hours, which was 1 mm per day. After the osteotomy was in place, the ulnar plate internal fixation was performed to reconstruct the ulnar stability in the second stage. The Cooney wrist joint score was used to assess the pain, function, range of motion, flexion and extension range of motion, and grip strength of the wrist joint before operation and before the removal of internal fixator. The subjective feeling and appearance satisfaction of patients were recorded. ResultsAfter the second-stage operation, all the 13 patients were followed up 10-22 months, with an average of 15 months. The deformity of wrist joint disappeared after operation, and the flexion, extension, and ulnar deviation were basically normal. There was no complication such as ulnar impingement sign, nonunion or infection. Wrist function, pain, and range of motion were significantly improved after operation, except for 1 patient who had no significant improvement in rotation and pain. The ulnar internal fixator was removed at 10-18 months after the second-stage operation. The scores of pain, function, range of motion, flexion and extension range of motion, and grip strength in the Cooney wrist score before removal of internal fixator significantly improved when compared with those before operation (P<0.05). Subjective and appearance satisfaction of patients were excellent in 9 cases, good in 3 cases, and fair in 1 case. ConclusionUlnar osteotomy and shortening with sequential plate internal fixation for correction of Madelung deformity, with mild postoperative pain, can effectively avoid bone nonunion, improve wrist joint function, and have significant effectiveness.