Study on roles of gap junctional intercellular communication in low dose parat hyroid hormones-induced bone anabolism in vitro

AIM:To investigate mediating and regulatory effects of osteoblastic gap juncti onal intercellular communication(GJIC) on low-dose parathyroid hormones(PTH)-s timulated bone formation activities in vitro.METHODS:Rat calvarial osteoblasts ( ROBs) in cultures were divided into three groups according to the different mode of exposure.Group A: vehicle (sodium acetate, SA)-treated group; Group B:1×10-8 mol/L hPTH(1-34) intermittent exposure group;Group C:1×10-8 mol/L hPTH(1-34) +1×10-7mol/L TPA exposure group.48 h incubation cycles in three groups were repeated for eight times.GJIC and mineralized bone nodules formation in thr ee groups were detected using Lucifer Yellow (LY) scrape loading dye transfer (S LDT) and mineralized nodule staining together with nodule index,respectively. RE SULTS:At various measuring time points of SA×6 h in group A,PTH×6 h in group B ,PTH×6 h+1 h in group B and PTH×6 h+TPA×1 h in group C,LY(+) cell numbers were 6.8±2.5,19.5±6.5,14.0±3.6 and 5.7±2.4,respectively.Diffusion and transf er of LY fluorescent probe was much more noticeably discerned in group B than in group A and C(P< 0.01).Mineralized bone nodule indices were 45.2±12.5, 88.0±1 5.3 and 38.5±17.9 in group A,B and C respectively.Bone formation activity was m uch better revealed in group B than in group A and C (P< 0.01),whereas no statis tically significant difference of bone formation activities were found in group A compared with group C(P=0.465).CONCLUSION:Mediations and regulations of the co ordinating signals in osteoblastic network via GJIC essentially contribute to PT H-stimulated bone anabolism.However,disruption of GJIC not only hinders osteobl astic intercellular coordination but also frustrates PTH-induced bone formation activities in vitro.Therefore,GJIC may evidently play important roles in regula tions on low-dose PTH-induced bone formation.

Multilevel cervical spondylotic myelopathy treated by anterior cervical decompression in subsection and autograft fusion

Objective：To investigate a novel surgical method for multilevel cervical spondylotic myelopathy （CSM）. Methods： Totally 21 patients with multilevel CSM undergoing a novel surgical procedure from April 2001 to January 2004 were analyzed retrospectively. All patients experienced anterior cervical decompression surgery in subsection, autograft fusion and internal fixation. Preoperative, immediate postoperative and follow-up image data, X-rays and semi-quantitative Japanese orthopaedics association （JOA） scores were used to evaluate the restoration of lordosis （Cobb＇s angle）, intervertebral heights, the stability of the cervical spine and the improvement of neurological impairment. Results： Preoperative symptoms were markedly alleviated or disappeared in most of the patients. According to the JOA scores, the ratio of improvement in neurological function was 72. 2%, including excellent in 9 cases （42.9%）, good in 7 cases （33.3%）, fair in 3 cases （14.3%） and poor in 2 cases （9.5%）. Immediate postoperative X-rays showed obvious improvements in lordosis and in the intervertebral height of the cervical spine （P〈0. 01）. There is no evidence of instrument failure during the mean follow-up period of 14. 2 months （9-24 months, P〉0. 01）. Conclusion：Anterior cervical decompression in subsection, autograft fusion and internal fixation is a rational effective method for the surgical treatment of multilevel CSM.

Histological comparison of fate of ligamentous insertion after reconstruction of anterior cruciate ligament: autograft vs allograft

Objective ：To analyze the histological results and the biological remodeling of ligamentous insertion after the reconstruction of anterior cruciate ligament （ ACL ） with autograft or allograft tendon. Methods： Extensor digitorum tendon was harvested from hind limb as graft material and transplanted to reconstruct the resected ACL in 12 mongrel dogs. Each free tendon end was secured by holding sutures and then the sutures were tied to the post screw at the femoral and tibial bony tunnel outlet after transplantation respectively. Autograft was randomly performed on one side of knee while allograft on the other side of knee. After transplantation, the histological analysis was undertaken at the 6th, 12th weeks and the 6th month using hematoxylineosin （HE） stain under light microscope. Results： The insertion structure of normal ACL typically consisted of four layers, i. e. , dense connective tissue, fibrocartilage, mineralized fibrocartilage and bone. There was a distinct regular tidemark line between fibrocartilage and mineralized fibrocartilage. At the 6th week postoperatively, loose connective tissue presented in the interspace between graft and bony tunnel wall in both autograft and allograft groups. At the 12th week postoperatively, the collagenons fibers between autograft and tunnel wall became well organized and the four layers of insertion with discontinuous tidemark line were demonstrated indistinctly in autograft group but not in allograft group. At the 6th month postoperatively, both of a clear and continuous tidemark line and distinct four layers could be seen in autograft group. In allograft group, only a waved discontinuous tidemark line was shown and either the anatomic morphology or the maturity of insertion was inferior to that of autograft group. Conclusions： At the 6th month postoperatively, although the ligament-eartilage insertion is primarily formed after ACL reconstruction with autograft or allograft tendon, the histological morphology and the maturation of insertion of autograft tendon are better than those of allograft group, which suggests that postoperative rehabilitation should be paid more attention and could be safer if little delayed during ACL reconstruction with allograft tendon.

A quantitative biomechanical study of positive buttress techniques for femoral neck fractures:a finite element analysis

Background:Refractory femoral neck fractures cannot be anatomically reduced by closed traction reduction which may affect fracture healing.We evaluated the biomechanical effects of positive,negative,and anatomic reduction of various degrees of displacement in Pauwels I femoral neck fractures by a finite element analysis.Methods:Five reduction models of Pauwels type I femoral neck fracture were established using the Mimics 17.0(Materialize,Leuven,Belgia)and Hypermesh 12.0(Altair Engineering,Troy,MI,USA).According to the degree of fracture displacement,there were three models of positive support,an anatomic reduction model,and a negative 2mm reduction model.Finite element analysis was conducted using the ABAQUS 6.9 software(Simulia,Suresnes,France).The von Mises stress distribution and the stress peak of internal fixation in different models,the displacement between fracture blocks,and the principal strain of the femoral neck cancellous bone model were recorded under the axial stress of 2100 N.Results:The peak von Mises stress on screw of each model was located at the thread of the screw tip.The peak von Mises stress was the lowest at the tip of the anatomic reduction model screw(261.2 MPa).In the positive 4mm model,the von Mises stress peak was the highest(916.1 MPa).The anatomic reduction model showed the minimum displacement(0.388 mm)between fracture blocks.The maximum displacement was noted in the positive 4mm model(0.838 mm).The displacement in the positive 3mm model(0.721 mm)was smaller than that in the negative 2mm model(0.786 mm).Among the five models,the strain area of the femoral neck cancellous bone was mainly concentrated around the screw hole,and the area around the screw hole could be easily cut.Conclusions:Compared with negative buttress for femoral neck fracture,positive buttress can provide better biomechanical stability.In Pauwel type I fracture of femoral neck,the range of positive buttress should be controlled below 3mm as far as possible.

Etiology, classification and clinical evaluation of partial-thickness tears of rotator cuff

MRI can provide clinically useful information in detecting and characterizingpartial-thickness tears in a non-invasive fashion with low accuracy, sensitivity and specificity.Compared with MRI assessment, ultrasonography is cheaper than MRI and arthrography and moreadvantageous with respect to the possibility of a dynamic exploration of the rotator cuff withenhanced visualization of the tendons during internal and external rotation. MRA image isparticularly well suited to the diagnosis of partial-thickness tears, but is invasive and moreexpensive. Others, such as clinical examination, arthrography, contrast computerized tomographicarthrography and radiograph, are good methods to evaluate the partial-thickness tears.

The biomechanics of point contact-dynamic compression plate and its effects on bone perfusion

Objective： To compare the mechanical properties of point contact-dynamic compression plate （PC-DCP） and its effects on cortical bone perfusion with that of dynamic compression plates （DCP） in goat tibiae. Methods： Twenty pairs of matched flesh goat tibiae were used. A transverse fracture model was established. The fractures with a 3ram interspace between the fracture ends were subject to fixations with the DCPs and the PC- DCPs respectively, then the four-points bending tests and the torsion tests were conducted to compare the mechanical properties of the PC-DCP with that of DCP. Another 13 sexually mature goats underwent fixations with the DCPs and the PC-DCPs, respectively, at the mid-shafts of the intact bilateral tibiae. Ischemic zones were observed at four time points （1 day, 2, 6, and 12 weeks after operation） using disuiphine blue staining technique. Remits： There were no significant differences in mechanical properties, such as bend- and torsionresistance, between the DCPs and the PC-DCPs. One day, 2, and 6 weeks after operation, on the side of DCP fixation, outer cortical bone ischemia under the plate persisted, and this condition did not reverse until 12 weeks after operation. However, on the side of PC-DCP fixation, cortical bone iscbemia occurred only in the periphery of the screw holes and at the contact sites of the PC NUTs 1 day after operation, and it disappeared at 2 weeks after operation. Conclusions： The PC-DCP has similar biomechanical properties of the DCP, but is less detrimental to local bone blood circulation than the conventional plates.

Biomechanical study on the suture strength of ligament in cruciate ligament reconstruction

Objective: To test the suture strength on the tendon or ligament end and evaluate the stitch in the reconstruction of cruciate ligament and its clinical application. Methods: Twenty-four specimens of patellar tendon with free ends were divided into 3 groups: Group I (3 Krackow stitches), Group II (2 Krackow stitches) and Group III (2 Krackow stitches with the first stitch passing through the tendon tissue as a modified Krackow stitch). These 3 groups were further divided into 6 subgroups according to different suture materials, No 1 Ethilon or stainless steel wire (φ= 0.4 mm). Tensile test was undertaken to find out the least stitches with efficient suture pattern. Results: Two Krackow locking stitches had stronger strength than 0.4 mm-diameter stainless steel wire. The fixation strength of 2 stitches with No 1 Ethilon was more than 80 N, superior to the failure strength of the material itself. The same strength was maintained if the first stitch was across the tendon tissue transversely. There was no statistically significant difference in the suture strength between 2 and 3 Krackow locking stitches. Conclusions: The suture strength is greater than the failure strength of the suture material. Less suture exposure can be achieved when the first stitch is across the tendon tissue while maintaining a comparable strength to other sutures. To attain higher suture strength, stronger materials or multiple strands rather than more stitches are preferred. Therefore, a rapid early rehabilitation of range of motion (ROM) is possible and reliable in practice.

RESEARCH ARTICLE Open Access Investigating clinical characteristics and prognostic factors in patients with chronic osteomyelitis of humerus

Background:Chronic osteomyelitis in the humerus,which has complex neuroanatomy and a good soft tissue envelope,represents a unique clinical challenge.However,there are relatively few related studies in the literature.This article retrospectively reviewed a large case series with the aims of sharing our management experiences and further determining factors associated with the outcomes.Methods:Twenty-eight consecutive adult patients with a mean age of 36 years were identified by reviewing the osteomyelitis database of our clinic centre.The database was used to prospectively identify all osteomyelitis cases between 2013 and 2017,and all data then was retrospectively analysed.Results:The mean follow-up period was 35 months(range 24–60).The aetiology was trauma in 43%(12)of the patients and haematogenous in 57%(16)of the patients,and Staphylococcus aureus was a solitary agent in 50%(14)of the patients.Host-type(Cierny’s classification)was IA in 8,IIIB in 11 and IVB in 9 patients.All patients required debridement followed by the placement of a temporary antibiotic-impregnated cement spacer(rod).Seventeen patients received a cement-coated plate for internal fixation after debridement,and 13 patients needed bone grafts when the spacer was staged removed.All patients attained an infection-free bone healing state at the final follow-up.The final average DASH(disabilities of the arm,shoulder and hand)score was 18.14±5.39,while 6 patients(two developed traumatic olecranarthritis,four developed radial nerve injuries)showed the lowest levels of limb function(p=0.000)and were unemployed.Three patients(type I;significant difference between type I versus type III and type IV patients,p<0.05)experienced recurrence after debridement and underwent a second revision,which was not related to the bone graft(p=0.226)or plate fixation(p=0.050).Conclusions:Humeral chronic osteomyelitis can be treated with general surgery and anti-infective therapy;medullary(type I)infection presents a challenge,and the antibiotic-coated cement plate provides favourable fixation without increasing recurrence of infections.Clinicians should be aware of potential iatrogenic nerve injuries when treating these patients with complicated cases,and an experienced surgeon may improve the outcome.