Scapular bone grafting with allograft pin fixation for repair of bony Bankart lesions: A biomechanical study

BACKGROUND Severe bony Bankart lesions are a difficult challenge in clinical treatment and research.The current treatment methods consist mostly of Latarjet-Bristow surgery and its modified procedures.While good results have been achieved,there are also complications such as coracoid fracture,bone graft displacement,and vascular and nerve injury.AIM To analyze the techniques and biomechanical properties of transversely fixing a bone block from the scapular spine using bone allograft pins with suture threads to repair bony Bankart lesions.METHODS Fresh human shoulder joint specimens and a cadaver specimen model for scapular bone grafting with allograft pin fixation for repair of bony Bankart lesions were used.When the humeral rotation angles were 0°,30°,60°and 90°,and the axial loads were 30 N,40 N,and 50 N,the humerus displacement was studied by biomechanical experiments.RESULTS When the angle of external rotation of the humerus was 0°,30°,60°,and 90°,with axial loads of 30 N,40 N,and 50 N,the data of the normal control group,allograft pin repair group,and titanium alloy hollow screw repair group were compared with each other by the q-test,which showed that there were no statistically differences among the three groups(P>0.05).CONCLUSION The joints repaired with bone block from the scapular spine transversely fixed with allograft bony pins to repair bony Bankart lesions show good mechanical stability.The bone block has similar properties to normal glenohumeral joints in terms of biomechanical stability.

Revision of Outcomes and Complications Following Open Reduction, and Zigzag Osteotomy Combined with Fibular Allograft for Developmental Dysplasia of the Hip in Children

Background: Reports of the efficacy of open reduction and Zigzag Osteotomy combined Fibular Allograft (ZOFA) for developmental dysplasia of the hip. The purposes of this study were to evaluate the long-term outcomes and complications after surgery. Methods: We performed a retrospective match-controlled study in which 158 patients had 181 hips with developmental dysplasia of the hip. Radiographs were found of acetabular index, height of dislocation, Tönnis grade, abduction angle in the spica cast, and Severin grade. At final follow-up, deformity of femoral head or neck or acetabulum was evaluated according to the Severin. Avascular necrosis was rated according to Kalamchi. Clinical evaluation was made according to modified McKay criteria. Results: Between 2009 and 2012, 133 girls (84.2%) and 25 boys (15.8%) with developmental dysplasia of the hip underwent open reduction and ZOFA;135 (85.4%) were unilateral, and 23 (14.6%) were bilateral. Patients were divided into 2 groups: group 1 included 54 patients (62 hips) aged 12 months - ≤18 months and group 2 included 84 patients (119 hips), aged >18 months - ≤36 months. According to Tönnis system: type 3 appeared in 127 hips (70.2%), and Type 4 in 54 hip (29.8%). The anterior approach was used to expose inner table of the ilium and ZOFA in all cases. Acetabular index was improved;preoperation was 42.95°, and latest follow-up 17.26°. The Kirschner Wires (KW) were not used to fix the fibular allograft at the pelvic osteotomy site. All of the fibular allografts were completely incorporated in mean time of 14 weeks (range, 12 weeks - 17 weeks) post-surgery. Clinical evaluation according to modified McKay criteria: satisfactory result (excellent and good) was achieved in 141 hips (77.9%). Avascular Necrosis (AVN) happened in 61 hips (33.7%), redislocation in 18 hips (9.9%), coxa vara in 4 hips (2.2%), trendelenburg gait in 4 hips (2.2%), and supracondylar femoral fractures in 2 hips (1.1%). Conclusions: On the basis of this study, ZOFA was strength and graft was not resorption, graft problems;without medial displacement of the distal fragment. Acetabular index was improved, without KW problem. Surgical technique with ZOFA did not expose outer table of the illium, limiting abductor muscle injury with negative trendelenburg gait;on the other hand, the blood loss from this procedure is acceptable. Some complications have been seen in this study: AVN, redislocation, coxa magna, coxa vara, trendelenburg gait, and distal femoral fracture.

A histomorphometric and molecular study on stress adaptability of freeze-dried bone allograft

Objective To Investigate stress adaptability of freeze-dried bone allograft.Methods Cortical and cancellous allograft were transplanted to each side of the midshaft diaphyseal ulna in two groups of 28 animals.The left transplanted allograft was free from fixation and bore a normal physiological lcad,while the right transplanted allograft was protected from loading by a simple external fixator and bore less load.Animals were sacrificed at the 2nd,4th,8th,16th week after transplantation and specimens were taken out for bone histomorphometry studies and analysis of collagen gene expression by in situ Cdna-Mrna hybridization.Results Labeled surface(LS)and bone mineral apposition rate(MAR)of the normally loaded graft-host bone interface were significantly higher than that of the less loaded side at the 4th,8th,16th week after transplantation.Parameters reflecting the internal repair process of the allograft,such as LS in cortical and cancellous bone or MAR in cortical bone of the normally loaded side were significantly higher than those of the less loaded side at the 16th week after transplantation.The result of in situ hybridization indicated that more osteoblast-like cells expressing the type Ⅰ collagen gene were found in the interface or interior of normally loaded grafts.Conclusion The stimulus of physiologic load can accelerate the early union of allograft-host bone interface and later new bone creep substitution to the necrotic allograft.

Magnesium cationic cue enriched interfacial tissue microenvironment nurtures the osseointegration of gamma-irradiated allograft bone

Regardless of the advancement of synthetic bone substitutes,allograft-derived bone substitutes still dominate in the orthopaedic circle in the treatments of bone diseases.Nevertheless,the stringent devitalization process jeopardizes their osseointegration with host bone and therefore prone to long-term failure.Hence,improving osseointegration and transplantation efficiency remains important.The alteration of bone tissue microenvironment(TME)to facilitate osseointegration has been generally recognized.However,the concept of exerting metal ionic cue in bone TME without compromising the mechanical properties of bone allograft is challenging.To address this concern,an interfacial tissue microenvironment with magnesium cationc cue was tailored onto the gamma-irradiated allograft bone using a customized magnesium-plasma surface treatment.The formation of the Mg cationic cue enriched interfacial tissue microenvironment on allograft bone was verified by the scanning ion-selective electrode technique.The cellular activities of human TERT-immortalized mesenchymal stem cells on the Mg-enriched grafts were notably upregulated.In the animal test,superior osseointegration between Mg-enriched graft and host bone was found,whereas poor integration was observed in the gamma-irradiated controls at 28 days post-operation.Furthermore,the bony in-growth appeared on magnesium-enriched allograft bone was significant higher.The mechanism possibly correlates to the up-regulation of integrin receptors in mesenchymal stem cells under modified bone TME that directly orchestrate the initial cell attachment and osteogenic differentiation of mesenchymal stem cells.Lastly,our findings demonstrate the significance of magnesium cation modified bone allograft that can potentially translate to various orthopaedic procedures requiring bone augmentation.