scholarly journals Effect of monocortical and bicortical screw numbers on the properties of a locking plate-intramedullary rod configuration

2016 ◽  
Vol 29 (06) ◽  
pp. 459-465 ◽  
Author(s):  
Kevin Parsons ◽  
Julie Etches ◽  
Katie Hamilton ◽  
Neil Burton ◽  
Elinor Field
Keyword(s):  
Locking Plate ◽  
Screw Loosening ◽  
Locking Screws ◽  
Pull Out ◽  
Physiological Load ◽  
Significant Difference ◽  
Load To Failure ◽  
Axially Loaded ◽  
Locking Screw ◽  
Bicortical Screw

SummaryObjectives: To evaluate the effect of varying the number and configuration of locking bicortical and monocortical screws on a plate-rod construct using a mid-diaphyseal femoral ostectomy model.Methods: Thirty Greyhound femurs were assigned to six groups (A-F). An intramedullary pin was placed in each bone following which a 3.5 mm locking plate was applied with six differing locking screw configurations. Groups A to C had one bicortical screw in the most proximal and distal plate holes and one to three monocortical locking screws in the proximal and distal fragments. Groups D to F had no bicortical screws placed and two to four monocortical locking screws in proximal and distal fragments. Each construct was axially loaded at 4 Hz from a preload of 10 Newtons (N) to 72 N, increasing to 144 N and 216 N, each of 6000 cycles with a further 45,000 cycles at 216 N to simulate a three to six week postoperative convalescence period. Constructs were then loaded to failure.Results: No construct suffered screw loosening or a significant change in construct stiffness during cyclic loading. There was no significant difference in load to failure of any construct (p = 0.34), however, less variation was seen with monocortical constructs. All constructs failed at greater than 2.5 times physiological load, and failure was by bending of the intramedullary pin and plate rather than screw loosening or pull-out.Clinical significance: Axially loaded locking monocortical plate-rod constructs applied to the canine femur may confer no difference biomechanically to those employing locking bicortical screws.

scholarly journals Biomechanical stability of complex coronal plane fracture fixation of the capitellum

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.

scholarly journals How Many Proximal Screws Are Needed for a Stable Proximal Humerus Fracture Fixation?

2021 ◽  
Vol 12 ◽  
pp. 215145932199274
Author(s):  
Hyojune Kim ◽  
Myung Jin Shin ◽  
Erica Kholinne ◽  
Janghyeon Seo ◽  
Duckwoo Ahn ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Proximal Humerus Fracture ◽  
Locking Plate ◽  
Proximal Humerus ◽  
Humerus Fracture ◽  
Proximal Fragment ◽  
Maximum Displacement ◽  
Significant Difference ◽  
Load To Failure ◽  
Screw Group

Purpose: This biomechanical study investigates the optimal number of proximal screws for stable fixation of a 2-part proximal humerus fracture model with a locking plate. Methods: Twenty-four proximal humerus fracture models were included in the study. An unstable 2-part fracture was created and fixed by a locking plate. Cyclic loading and load-to-failure tests were used for the following 4 groups based on the number of screws used: 4-screw, 6-screw, 7-screw, and 9-screw groups. Interfragmentary gaps were measured following cyclic loading and compared. Consequently, the load to failure, maximum displacement, stiffness, and mode of failure at failure point were compared. Results: The interfragmentary gaps for the 4-screw, 6-screw, 7-screw, and 9-screw groups were significantly reduced by 0.24 ± 0.09 mm, 0.08 ± 0.06 mm, 0.05 ± 0.01 mm, and 0.03 ± 0.01 mm following 1000 cyclic loading, respectively. The loads to failure were significantly different between the groups with the 7-screw group showing the highest load to failure. The stiffness of the 7-screw group was superior compared with the 6-screw, 9-screw, and 4-screw groups. The maximum displacement before failure showed a significant difference between the comparative groups with the 4-screw group having the lowest value. The 7-screw group had the least structural failure rate (33.3%). Conclusion: At least 7 screws would be optimal for proximal fragment fixation of proximal humerus fractures with medial comminution to minimize secondary varus collapse or fixation failure. Level of Evidence: Basic science study.

scholarly journals Biomechanical Analysis of the Efficacy of Locking Plates during Cyclic Loading in Metacarpal Fractures

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Stefanie Doht ◽  
Rainer H. Meffert ◽  
Michael J. Raschke ◽  
Torsten Blunk ◽  
Sabine Ochman
Keyword(s):  
Cyclic Loading ◽  
Locking Plate ◽  
Screw Fixation ◽  
Maximum Load ◽  
Biomechanical Analysis ◽  
Locking Plates ◽  
Functional Rehabilitation ◽  
Metacarpal Bones ◽  
Load To Failure ◽  
Bicortical Screw

Purpose.To analyse the biomechanical characteristics of locking plates under cyclic loading compared to a nonlocking plate in a diaphyseal metacarpal fracture.Methods.Oblique diaphyseal shaft fractures in porcine metacarpal bones were created in a biomechanical fracture model. An anatomical reduction and stabilization with a nonlocking and a comparable locking plate in mono- or bicortical screw fixation followed. Under cyclic loading, the displacement, and in subsequent load-to-failure tests, the maximum load and stiffness were measured.Results.For the monocortical screw fixation of the locking plate, a similar displacement, maximum load, and stiffness could be demonstrated compared to the bicortical screw fixation of the nonlocking plate.Conclusions.Locking plates in monocortical configuration may function as a useful alternative to the currently common treatment with bicortical fixations. Thereby, irritation of the flexor tendons would be avoided without compromising the stability, thus enabling the necessary early functional rehabilitation.

scholarly journals The effect of the combination of locking screws and non-locking screws on the torsional properties of a locking-plate construct

2010 ◽  
Vol 23 (01) ◽  
pp. 7-13 ◽  
Author(s):  
N. M. M. Moens ◽  
J. Runciman ◽  
G. Monteith ◽  
S. Gordon
Keyword(s):  
Plastic Deformation ◽  
Locking Plate ◽  
Combination Group ◽  
Clinical Value ◽  
Locking Screws ◽  
Torsional Loads ◽  
Failure Point ◽  
Locking Screw ◽  
Torsional Properties ◽  
Torque Angle

SummaryLittle is known about the torsional properties of bone-plate constructs when a combination of locking and non-locking screws have been used. Sixty cadaveric canine femurs were divided into three groups. In the first group, the plate was affixed using three non-locking screws. In the second group, only locking screws were used while a combination of one locking and two non-locking screws were used in the third group. All constructs were subjected to torsion until failure. Torque, angle of torsion, and work were all calculated at the maximum failure point, as well as at five degrees of plastic deformation, which was thought to be more representative of clinical failure. At the maximum failure point, the locking group had significantly higher torque, angle, and work values than the non-locking group. The combination group was intermediate to the two other groups, and significantly differed from the non-locking group in torque, and from the locking group in work. At five degrees of plastic deformation, the locking group required significantly higher torque and work than the non-locking group. The combination group required a significantly higher torque than the non-locking group. This study suggests that a construct composed of all locking screws will fail at a greater torque value, and sustain greater work to failure in torsion compared to a construct composed of all non-locking screws. The addition of a single locking screw to an otherwise non-locking construct will increase the torque at the offset failure point and may be of clinical value in constructs subjected to high torsional loads.

Comparison of Locking Plate with Interfragmentary Screw Versus Plantarly Applied Anatomic Locking Plate for Lapidus Arthrodesis: A Biomechanical Cadaveric Study

2016 ◽  
Vol 10 (3) ◽  
pp. 227-231 ◽  
Author(s):  
James M. Cottom ◽  
Joseph S. Baker
Keyword(s):  
Ultimate Load ◽  
Locking Plate ◽  
Statistical Significance ◽  
Biomechanical Study ◽  
Clinical Settings ◽  
First Metatarsal ◽  
Low Profile ◽  
Significant Difference ◽  
Load To Failure ◽  
Anatomic Locking Plate

Arthrodesis of the first metatarsal cuneiform joint, or Lapidus procedure, is a widely accepted treatment for hallux valgus. Recent studies have focused on comparing various constructs for this procedure both in the laboratory and clinical settings. The current study compared in a cadaveric model the strength of 2 constructs. The first construct utilized a medially applied low-profile locking plate and an interfragmentary screw directed from plantar-distal to dorsal-proximal. The second construct consisted of a plantarly applied plate with a compression screw placed through the plate from plantar-distal to dorsal-proximal. The ultimate load to failure for the 2 groups tested was 255.38 ± 155.38 N and 197.48 ± 108.61 N, respectively (P = .402). There was no significant difference found between the 2 groups with respect to ultimate load to failure, stiffness of the construct, or moment at time of failure. In conclusion, the medially applied plate with plantar interfragmentary screw appears to be stronger than the plantar Lapidus plate tested for first metatarsal cuneiform arthrodesis, though this difference did not reach statistical significance. Levels of Evidence: Level V: Biomechanical Study

Locking Screw Migration to the Palm Four Years Following Surgical Implantation of Distal Radius Locking Plate

2017 ◽  
Vol 22 (03) ◽  
pp. 363-365
Author(s):  
Yousef Marwan ◽  
Asim M. Makhdom ◽  
Gregory Berry
Keyword(s):  
Distal Radius ◽  
Locking Plate ◽  
Rare Complication ◽  
Volar Locking Plate ◽  
Screw Loosening ◽  
Radius Fractures ◽  
Non Union ◽  
Surgical Implantation ◽  
And Migration ◽  
Locking Screw

Hardware-related complications are rare in patients with distal radius fractures who were surgically fixed with volar-locking plates. In this report, we present a case of locking screw loosening and migration to the palm four years following the treatment of type 23-C1 distal radius fracture with a volar locking-plate. This complication occurred without evidence of trauma, infection, non-union or plate breakage. Orthopaedic surgeons should be aware of such rare complication and add it to the list of potential postoperative complications when counseling their patients preoperatively.

scholarly journals Temporal Changes in Reverse Torque of Locking-Head Screws Used in the Locking Plate in Segmental Tibial Defect in Goat Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Remigiusz M. Grzeskowiak ◽  
Rebecca E. Rifkin ◽  
Elizabeth G. Croy ◽  
Richard C. Steiner ◽  
Reza Seddighi ◽  
...  
Keyword(s):  
Locking Plate ◽  
Segmental Bone Defect ◽  
Stable Fixation ◽  
Plate Removal ◽  
Locking Screws ◽  
Reverse Torque ◽  
Segmental Bone ◽  
Locking Screw ◽  
With Screws ◽  
Over Time

The objective of this study was to evaluate changes in peak reverse torque (PRT) of the locking head screws that occur over time. A locking plate construct, consisting of an 8-hole locking plate and 8 locking screws, was used to stabilize a tibia segmental bone defect in a goat model. PRT was measured after periods of 3, 6, 9, and 12 months of ambulation. PRT for each screw was determined during plate removal. Statistical analysis revealed that after 6 months of loading, locking screws placed in position no. 4 had significantly less PRT as compared with screws placed in position no. 5 (p < 0.05). There were no statistically significant differences in PRT between groups as a factor of time (p > 0.05). Intracortical fractures occurred during the placement of 151 out of 664 screws (22.7%) and were significantly more common in the screw positions closest to the osteotomy (positions 4 and 5, p < 0.05). Periosteal and endosteal bone reactions and locking screw backout occurred significantly more often in the proximal bone segments (p < 0.05). Screw backout significantly, negatively influenced the PRT of the screws placed in positions no. 3, 4, and 5 (p < 0.05). The locking plate-screw constructs provided stable fixation of 2.5-cm segmental tibia defects in a goat animal model for up to 12 months.

scholarly journals Biomechanical comparison of two locking plate constructs under cyclic torsional loading in a fracture gap model

2015 ◽  
Vol 28 (05) ◽  
pp. 323-330 ◽  
Author(s):  
A. Bilmont ◽  
S. Palierne ◽  
M. Verset ◽  
P. Swider ◽  
A. Autefage
Keyword(s):  
Locking Plate ◽  
Torsional Loading ◽  
Screw Head ◽  
The Third ◽  
Cyclic Torsion ◽  
Locking Screws ◽  
Locking Compression Plates ◽  
Number Of Cycles ◽  
Biomechanical Comparison ◽  
Locking Screw

SummaryObjectives: The number of locking screws required per fragment during bridging osteo-synthesis in the dog has not been determined. The purpose of this study was to assess the survival of two constructs, with either two or three screws per fragment, under cyclic torsion.Methods: Ten-hole 3.5 mm stainless steel locking compression plates (LCP) were fixed 1 mm away from bone surrogates with a fracture gap of 47 mm using two bicortical locking screws (10 constructs) or three bicortical locking screws (10 constructs) per fragment, placed at the extremities of each LCP. Constructs were tested in cyclic torsion (range: 0 to +0.218 rad) until failure.Results: The 3-screws constructs (29.65 ± 1.89 N.m/rad) were stiffer than the 2-screws constructs (23.73 ± 0.87 N.m/rad), and therefore, were subjected to a greater torque during cycling (6.05 ± 1.33 N.m and 4.88 ± 1.14 N.m respectively). The 3-screws constructs sustained a significantly greater number of cycles (20,700 ± 5,735 cycles) than the 2-screws constructs (15,600 ± 5,272 cycles). In most constructs, failure was due to screw damage at the junction of the shaft and head. The remaining constructs failed because of screw head unlocking, sometimes due to incomplete seating of the screw head prior to testing.Clinical significance: Omitting the third innermost locking screw during bridging osteosynthesis led to a reduction in fatigue life of 25% and construct stiffness by 20%. Fracture of the screws is believed to occur sequentially, starting with the innermost screw that initially shields the other screws.

Biomechanical Comparison of Low-Profile Contoured Locking Plate With Single Compression Screw to Fully Threaded Compression Screws for First MTP Fusion

2019 ◽  
Vol 40 (7) ◽  
pp. 836-844
Author(s):  
Richard S. Fuld ◽  
Pam Kumparatana ◽  
Judas Kelley ◽  
Nicholas Anderson ◽  
Todd Baldini ◽  
...  
Keyword(s):  
Locking Plate ◽  
Matched Pair ◽  
Mineral Density ◽  
Compression Screw ◽  
Plate Group ◽  
Low Profile ◽  
Significant Difference ◽  
Load To Failure ◽  
New Generation ◽  
Screw Group

Background: Open metatarsophalangeal (MTP) arthrodesis using locked plates produces good clinical outcomes. However, arthroscopic fusion with new-generation fully threaded compression screws is emerging as an alternative. The purpose of this study was to compare low-profile contoured locked plates with fully threaded compression screws for first MTP fusion, in a biomechanical cadaveric model. Methods: The first rays of 8 matched pairs of fresh frozen cadaveric feet underwent dissection and dual-energy x-ray absorptiometry (DEXA) scanning to measure bone mineral density (BMD). The “plate” group was prepared with cup-and-cone reamers, and fixation of the MTP joint with 1 compression screw and low-profile dorsal locked plate. The matched-pair “screws” group was prepared through a simulated arthroscopic technique, achieving fixation with 2 new-generation fully threaded compression screws. The plantar MTP gap was recorded with an extensometer during 250 000 90-N cyclic loads followed by a single load to failure. Results: The screw group demonstrated significantly greater stiffness, 31.6 N/mm (plates) and 51.7 N/mm (screws) ( P = .0045). There was no significant difference in plantar gapping or load to failure, 198.6 N (plates) and 290.1 N (screws) ( P = .2226). Stiffness and load to failure were highly correlated to BMD for the screw group, r =0.79 and r = 0.94, respectively, but less so for the plate group, r = 0.36 and r = 0.62, respectively. The maximum metatarsal head height measured on the lateral view was strongly correlated with load to failure for both the plate- and screw-only groups ( r > 0.9). Conclusion: These data demonstrate that hallux MTP arthrodesis utilizing fully threaded compression screws had similar plantar gapping and load to failure when compared with the low-profile locking plate, but with significantly more stiffness. These results support an increased role of fully threaded screws for MTP arthrodesis using either the arthroscopic or open technique. However, with decreased BMD plate fixation may remain the better fixation choice. Clinical Relevance: Our data suggest that with regard to construct stability, fully threaded headless compression screws may be just as effective as low-profile locking plates, but BMD and MTP joint fluoroscopic measurements should be considered in the decision-making process for fixation.

scholarly journals Biomechanical Comparison of a Prepared Thick Fresh Frozen Irradiated Fascia Lata Allograft to the Native Superior Capsule (212)

2021 ◽  
Vol 9 (10_suppl5) ◽  
pp. 2325967121S0032
Author(s):  
Nicholas Debellis ◽  
John Manning ◽  
James Tibone ◽  
Michelle McGarry ◽  
Gregory Adamson ◽  
...  
Keyword(s):  
Ultimate Load ◽  
Fascia Lata ◽  
Cadaveric Specimen ◽  
Yield Load ◽  
Total Displacement ◽  
Pull Out ◽  
Significant Difference ◽  
Load To Failure ◽  
Fresh Frozen ◽  
Biomechanical Comparison

Objectives: Superior Capsule Reconstruction (SCR) has been described as treatment option for irreparable tears of the superior rotator cuff. Reported outcomes on the success of the surgery have been variable, with graft choice seeming to be one of the most important factors. Fascia Lata (FL) allograft has been proposed as a potential option as it provides adequate graft thickness while avoiding the morbidity of an autograft harvest. The purpose of this study was to compare the biomechanical characteristics of an SCR with FL allograft (FL-SCR) to a native superior capsule in a cadaveric specimen. Methods: Eight cadaver shoulder specimens were used. Each specimen was tested with a custom shoulder system twice. Initial testing was performed after the specimen was dissected of all soft tissue except for the native superior capsule. Subsequent testing was performed after FL-SCR was done. All allografts were fresh frozen and irradiated. Capsule and graft dimensions were recorded before testing. Biomechanical values recorded were cyclic and load to failure for both the native capsule and FL-SCR, and fixation displacement for the SCR-FL construct. A Paired T-test was performed to compare the biomechanical values of the native superior capsule to the FL-SCR. Results: The mean thickness of the NSC was 2.4 ± 0.6 mm and 7.4 ± 1.2mm for the FL graft. The native superior capsule had an average linear stiffness of 94.5 ± 20.4 N/mm, yield load of 386.9 ± 63.6 N, ultimate load of 444.9 ± 67.7 N and energy absorbed of 1418.4 ± 248.8 N-mm. The FL-SCR construct had an average linear stiffness of 28.0 ± 1.6 N/mm, yield load of 123.8 ± 54.3 N, ultimate load of 369.0 ± 43.4 N and energy absorbed of 5021.2 ± 755.1 N-mm. Comparing the two groups there was a statistically significant difference for stiffness (P = 0.013), yield load (P = 0.03) and energy absorbed (P = 0.003). There was no statistically significant difference between ultimate load. The total displacement of the FL-SCR fixation was 5.8 ± 0.6 mm after 1 cycle, 8.5 ± 0.7 mm after 30 cycles, 11.4 ± 1.8 mm at the yield load and 29.5 ± 1.8 mm at the ultimate load. For the failure mode, 8/8 NSC specimens failed at the mid-substance. The FL-SCR, 3/8 specimens failed at the suture tendon interface and 4/8 had medial anchor pull out. Conclusions: Performing SCR with FL allograft in a cadaver model creates a construct that is sufficiently strong enough to withstand normal physiologic loading of the shoulder, although it does not fully re-create the biomechanical characteristics of a native shoulder superior capsule.

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