Effect of impaction energy on dynamic bone strains, fixation strength, and seating of cementless acetabular cups

Endo-D-galacturonanase of Aspergillus sp. was irreversibly adsorbed on polyethyleneterephthalate in an acetate 0.1 mol l-1 buffer solution of pH 4.2. Immobilization of the enzyme resulted in lowering of its activity, the measure of which depended on the amount of the enzyme fixed on the carrier. The highest relative activity (42.4%) had the preparation containing 5.25 mg of the enzyme per 1 g of the carrier. The velocity and intensity of the sorption of the enzyme depended on the ionic strength of the medium, whilst pH, on the other hand, was of no influence. Endo-D-galacturonanase immobilized in a 0.1 mol l-1 buffer was characteristic a) of its fixation strength in salt solutions of various ionic strength and pH, in a 3 mol l-1 guanidine solution, and also in sodium pectate and pectin solutions, b) of its high stability during a long-lasting storage at 4 °C, c) of its operational stability. The immobilization led to a partial change of the action pattern onto the high-molecular substrate, manifested in lowering the decrease of viscosity to degradation degree ratio.

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Stacked Biocomposite Screws in a Single-Stage Revision Anterior Cruciate Ligament Reconstruction Has Acceptable Fixation Strength in a Porcine Cadaveric Model

The American Journal of Sports Medicine ◽

10.1177/03635465211015192 ◽

2021 ◽

pp. 036354652110151

Author(s):

Hasan Baydoun ◽

Ian D. Engler ◽

Ali Hosseini ◽

Lance LeClere ◽

Joeri Zoon ◽

...

Keyword(s):

Bone Loss ◽

Acl Reconstruction ◽

Cruciate Ligament ◽

Interference Screw ◽

Single Stage ◽

Fixation Strength ◽

Revision Acl Reconstruction ◽

Group 2 ◽

Bone Tunnels ◽

Primary Acl Reconstruction

Background: Stacked screws is a commonly used technique in single-stage revision anterior cruciate ligament (ACL) reconstruction in the setting of bone loss, but there are limited data to support its use. Hypothesis: Two configurations of a biocomposite stacked screws construct have similar fixation strength and linear stiffness as a primary ACL reconstruction construct in a biomechanical model. Study Design: Controlled laboratory study. Methods: A total of 30 porcine legs were divided into 3 groups. Group 1 underwent primary ACL reconstruction with a patellar tendon graft fixed into the femur, with an 8-mm biocomposite interference screw of beta-tricalcium phosphate and poly lactide-co-glycolide. For a revision ACL reconstruction model, groups 2 and 3 had bone tunnels created and subsequently filled with 12-mm biocomposite screws. New bone tunnels were drilled through the filler screw and the surrounding bone, and the patellar bone plug was inserted. Group 2 was fixed with 8-mm biocomposite screws on the side of the graft opposite the filler screw, while group 3 had the interference screw interposed between the graft and the filler screw. The construct was loaded at 1.5 mm/s in line with the tunnel until failure. Load to failure, linear stiffness, and mode of failure were recorded. Results: The mean pullout strength for groups 1, 2, and 3 was 626 ± 145 N, 653 ± 152 N, and 720 ± 125 N, respectively ( P = .328). The mean linear stiffness of the construct in groups 1, 2, and 3 was 71.4 ± 9.9 N/mm, 84.1 ± 11.1 N/mm, and 82.0 ± 10.8 N/mm, respectively. Group 2 was significantly stiffer than group 1 ( P = .037). Conclusion: Two configurations of a biocomposite stacked screws construct for a single-stage revision ACL reconstruction in the setting of bone loss show a similar fixation strength and linear stiffness to a primary ACL reconstruction at time zero in a porcine model. Clinical Relevance: In the setting of bone loss from tunnel malpositioning, a single-stage revision ACL reconstruction using a stacked screws construct may provide adequate fixation strength and linear stiffness.

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Assessment of glenoid baseplate initial micromotion and fixation strength in reverse total shoulder arthroplasty designs using a direct shear force methodology

Shoulder & Elbow ◽

10.1177/17585732211032945 ◽

2021 ◽

pp. 175857322110329

Author(s):

Therese E Parr ◽

Jennifer K Anderson ◽

Alan M. Marionneaux ◽

John M Tokish ◽

Stefan J Tolan ◽

...

Keyword(s):

Shoulder Arthroplasty ◽

Shear Force ◽

Total Shoulder Arthroplasty ◽

Reverse Total Shoulder Arthroplasty ◽

Fixation Strength ◽

Shoulder Prosthesis ◽

Direct Shear ◽

Device Failure ◽

Glenoid Baseplate ◽

Reverse Total Shoulder

Background In a reverse total shoulder arthroplasty, the altered glenohumeral joint center of rotation subjects the glenoid baseplate to increased shear forces and potential loosening. Methods This study examined glenoid baseplate micromotion and initial fixation strength with the application of direct shear force in a Sawbone model. The reverse total shoulder arthroplasty systems examined were the DJO Reverse® Shoulder Prosthesis, the Exactech Equinoxe® Reverse System, and the Tornier AequalisTM Reverse Shoulder Prosthesis. Specimens were cyclically tested with increasing shear loads until 150 µm of displacement between the implant and glenoid was achieved, and subsequently until failure, classified as either 1 cm of implant/glenoid displacement or fracture. Results The average load withstood for the 150 µm threshold for DJO, Tornier, and Exactech was 460 ± 88 N, 525 ± 100 N, and 585 ± 160 N, respectively. The average total load at device failure for DJO, Tornier, and Exactech was 980 ± 260 N, 1260 ± 120 N, and 1350 ± 230 N, respectively. Discussion The Exactech implant design trended toward requiring more load to induce micromotion at each threshold and to induce device failure, most commonly seen as inferior screw pull out. This study proposes design features that may enhance fixation and suggests little risk of initial micromotion or failure during initial post-operative recovery.

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Biomechanical stability of complex coronal plane fracture fixation of the capitellum

Archives of Orthopaedic and Trauma Surgery ◽

10.1007/s00402-021-04126-1 ◽

2021 ◽

Author(s):

Paul Borbas ◽

Rafael Loucas ◽

Marios Loucas ◽

Maximilian Vetter ◽

Simon Hofstede ◽

...

Keyword(s):

Fracture Fixation ◽

Ultimate Load ◽

Locking Plate ◽

Distal Humerus ◽

Coronal Plane ◽

Fixation Strength ◽

Biomechanical Stability ◽

Significant Difference ◽

Load To Failure ◽

Headless Compression Screws

Abstract Introduction Coronal plane fractures of the distal humerus are relatively rare and can be challenging to treat due to their complexity and intra-articular nature. There is no gold standard for surgical management of these complex fractures. The purpose of this study was to compare the biomechanical stability and strength of two different internal fixation techniques for complex coronal plane fractures of the capitellum with posterior comminution. Materials and methods Fourteen fresh frozen, age- and gender-matched cadaveric elbows were 3D-navigated osteotomized simulating a Dubberley type IIB fracture. Specimens were randomized into one of two treatment groups and stabilized with an anterior antiglide plate with additional anteroposterior cannulated headless compression screws (group antiGP + HCS) or a posterolateral distal humerus locking plate with lateral extension (group PLP). Cyclic testing was performed with 75 N over 2000 cycles and ultimately until construct failure. Data were analyzed for displacement, construct stiffness, and ultimate load to failure. Results There was no significant difference in displacement during 2000 cycles (p = 0.291), stiffness (310 vs. 347 N/mm; p = 0.612) or ultimate load to failure (649 ± 351 vs. 887 ± 187 N; p = 0.140) between the two groups. Conclusions Posterolateral distal humerus locking plate achieves equal biomechanical fixation strength as an anterior antiglide plate with additional anteroposterior cannulated headless compression screws for fracture fixation of complex coronal plane fractures of the capitellum. These results support the use of a posterolateral distal humerus locking plate considering the clinical advantages of less invasive surgery and extraarticular metalware. Level of evidence Biomechanical study.

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Augmented cerclage wire improves the fixation strength of a two-screw construct for humerus split type greater tuberosity fracture: a biomechanical study

BMC Musculoskeletal Disorders ◽

10.1186/s12891-021-04215-7 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Chao-Jui Chang ◽

Wei-Ren Su ◽

Kai-Lan Hsu ◽

Chih-Kai Hong ◽

Fa-Chuan Kuan ◽

...

Keyword(s):

Screw Fixation ◽

Biomechanical Study ◽

Fixation Strength ◽

Myotendinous Junction ◽

Steel Cable ◽

Simple Modification ◽

Greater Tuberosity ◽

Cerclage Wire ◽

Group A ◽

Group B

Abstract Background Poor functional outcome can result from humeral greater tuberosity (GT) fracture if not treated appropriately. A two-screw construct is commonly used for the surgical treatment of such injury. However, loss of reduction is still a major concern after surgery. To improve the biomechanical strength of screw fixation in GT fractures, we made a simple modification of the two-screw construct by adding a cerclage wire to the two-screw construct. The purpose of this biomechanical study was to analyze the effect of this modification for the fixation of GT fractures. Materials and methods Sixteen fresh-frozen human cadaveric shoulders were used in this study. The fracture models were arbitrarily assigned to one of two fixation methods. Group A (n = 8) was fixed with two threaded cancellous screws with washers. In group B (n = 8), all screws were set using methods identical to group A, with the addition of a cerclage wire. Horizontal traction was applied via a stainless steel cable fixed directly to the myotendinous junction of the supraspinatus muscle. Displacement of the fracture fixation under a pulling force of 100 N/200 N and loading force to construct failure were measured. Results The mean displacements under 100 N and 200 N traction force were both significantly decreased in group B than in group A. (100 N: 1.06 ± 0.12 mm vs. 2.26 ± 0.24 mm, p < 0.001; 200 N: 2.21 ± 0.25 mm vs. 4.94 ± 0.30 mm, p < 0.001) Moreover, the failure load was significantly higher in group B compared with group A. (415 ± 52 N vs.335 ± 47 N, p = 0.01), Conclusions The current biomechanical cadaveric study demonstrated that the two-screw fixation construct augmented with a cerclage wire has higher mechanical performance than the conventional two-screw configuration for the fixation of humeral GT fractures. Trial registration Retrospectively registered.

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A novel auxetic structure based bone screw design: Tensile mechanical characterization and pullout fixation strength evaluation

Materials & Design ◽

10.1016/j.matdes.2019.108424 ◽

2020 ◽

Vol 188 ◽

pp. 108424 ◽

Cited By ~ 3

Author(s):

Yan Yao ◽

Lizhen Wang ◽

Jian Li ◽

Shan Tian ◽

Ming Zhang ◽

...

Keyword(s):

Mechanical Characterization ◽

Fixation Strength ◽

Strength Evaluation ◽

Bone Screw ◽

Screw Design ◽

Pullout Fixation ◽

Auxetic Structure

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Fixation Strength in Full and Limited Fixation of Osteoporotic Distal Radius Fractures

Hand ◽

10.1177/1558944717708032 ◽

2017 ◽

Vol 13 (4) ◽

pp. 461-465 ◽

Cited By ~ 1

Author(s):

P. Kaveh Mansuripur ◽

Joseph A. Gil ◽

Dale Cassidy ◽

Patrick Kane ◽

Augusta Kluk ◽

...

Keyword(s):

Distal Radius ◽

Peak Load ◽

Distal Radius Fractures ◽

Volar Plate ◽

Fixation Strength ◽

Joint Surface ◽

Clinical Failure ◽

Radius Fractures ◽

Yield Load ◽

Load Peak

Background: The purpose of this investigation is to determine whether osteoporotic intra-articular distal radius fractures surgically treated by filling all 7 distal screws of a volar plate will have a higher load to failure than those treated by filling only 4 distal screws. Methods: Ten matched pairs of fresh frozen cadaveric forearms were randomized within each pair to be treated by using either all 7 of the distal holes of a volar plate or only 4 distal screws. The distal radius fixation was performed with unicortical screws going to but not through the dorsal cortex, and the most distal screws were placed within 4 mm of the joint surface. An AO C2 type fracture was then created. All specimens were tested cyclically, with an axial load of 60 N, at 3 Hz for 1000 cycles to simulate early postoperative motion. All specimens were subsequently tested to mechanical failure. Results: There were no failures in either group during cyclic testing. There was no difference detected between groups for mean stiffness, yield load, peak load, or load to clinical failure. In both groups, the yield load, peak load, and load to clinical failure were higher than the 60- to 100-N forces encountered during postoperative rehabilitation. Conclusions: There was no difference detected between osteoporotic intra-articular distal radius fractures treated by utilizing all 7 of the distal screws of a volar plate compared with those treated with only 4 distal screws.

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