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 Arthroscopic versus Open MTP Arthrodesis

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002 ◽  
Author(s):  
Kenneth Hunt ◽  
Alastair Younger ◽  
Richard Fuld ◽  
Judas Kelley ◽  
Nicholas Anderson ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Matched Pair ◽  
Preparation Technique ◽  
Locked Plate ◽  
Plate Group ◽  
Low Profile ◽  
Significant Difference ◽  
Load To Failure ◽  
New Generation ◽  
Biomechanical Strength

Category: Midfoot/Forefoot Introduction/Purpose: Hallux metatarsophalangeal (MTP) arthrodesis is a common procedure for painful conditions of the great toe. Dorsal plate fixation for MTP arthrodesis using locked plates produces good clinical outcomes and superior biomechanical strength to other techniques. However, arthroscopic fusion with new generation full thread compression screws is emerging as an alternative to open fusion. This method has been utilized clinically with good outcomes, but the biomechanical strength of arthroscopic MTP fusion fixation techniques is unknown. The purpose of this study was to compare low profile contoured locked plates to new generation full thread compression screws for first MTP fusion, in a biomechanical cadaver model. We hypothesize that there will be no significant difference in plantar gapping during cyclic loading, stiffness, or load-to-failure between the two groups, Methods: The first rays of eight matched pairs of fresh frozen cadaveric feet underwent dissection and 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 one compression screw and low profile dorsal locked plate. The matched pair “screws” group was prepared through a simulated arthroscopic technique, achieving fixation with two new generation full-thread compression screws, while preserving capsular attachments. Each specimen was loaded on the proximal phalanx in a cantilever fashion to 90 N at 3 Hz for a total of 250,000 cycles. Plantar MTP gap was recorded using a calibrated extensometer; Load-to-failure testing was performed for all specimens that endured cyclical loading; and stiffness was calculated from the final load-to-failure. Data was analyzed with a Student’s T-Test, with significance set at p<.05. Pearson Correlation coefficient (r) was calculated for stiffness and load-to-failure vs. BMD. Results: The plate group demonstrated significantly more plantar gapping during cyclic loading. There was no significant difference in stiffness, 31.6 N/mm (plates) and 51.7 N/mm (screws) (p=0.24) or load-to-failure, 198.6 N (plates) and 290.1 N (screws) (p =.07). Two of 8 screws-only specimens, and 3 of 8 locked plate specimens failed during cyclic loading. These early failures, and stiffness and load-to-failure were highly correlated to BMD for plates (r=0.85 and r=0.62, respectively) and screws only (r=0.82 and r=0.94, respectively). Maximum metatarsal head width measured on lateral view was strongly correlated with load-to-failure and stiffness for both groups (r > 0.7). Conclusion: Arthroscopic hallux MTP arthrodesis utilizing full thread compression screws has similar mean stiffness and load-to- failure compared to a low-profile locking plate, with significantly less plantar gapping. These data, combined with advantages of the arthroscopic preparation technique, support an increased role of arthroscopic fusion in lieu of more invasive open plating techniques. The two preload failures of the screws-only cohort occurred in specimens with the lowest BMD, potentially indicating a clinical contraindication with this technique. BMD and metatarsal width may aid in predicting early failure such that appropriate fixation construct and more conservative post-operative protocols might improve results for these patients.

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.

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

Plantar versus Dorsomedial Locked Plating for Lapidus Arthrodesis: A Biomechanical Comparison

2011 ◽  
Vol 32 (11) ◽  
pp. 1081-1085 ◽  
Author(s):  
Kajetan Klos ◽  
Paul Simons ◽  
Anne-Sophie Hajduk ◽  
Konrad Leopold Hoffmeier ◽  
Florian Gras ◽  
...  
Keyword(s):  
Quantitative Computed Tomography ◽  
Initial Stiffness ◽  
Mineral Density ◽  
Compression Screw ◽  
Locked Plating ◽  
Static Tests ◽  
Significant Difference ◽  
Load To Failure ◽  
Angle Stable ◽  
Angle Stable Plate

Background: Lapidus arthrodesis with a plate and a compression screw is an established procedure in hallux valgus surgery. The present study was performed to investigate the potential benefit of a compression screw combined with a plantarly applied angle-stable, anatomically precontoured plate or a dorsomedially applied angle-stable plate. Methods: In six pairs of human cadaver specimens, one specimen each was randomized to receive a dorsomedial H-shaped plate, while the other received a plantar plate. Bone mineral density was measured with peripheral quantitative computed tomography. The specimens were loaded quasi-statically, followed by cyclic loading. Finally, they were loaded to failure. In the static tests, stiffness and range of motion (ROM) data were obtained. In the cyclic tests, the constructs' displacement was studied. In the load-to-failure test, stiffness and maximum load to failure were measured. Results: The two groups did not differ significantly with regard to BMD (p = 0.25). Any significant differences observed were in favor of the plantar constructs, which had greater initial stiffness (p = 0.028) and final stiffness (p = 0.042), a smaller ROM (p = 0.028), and a greater load to failure (p = 0.043). There was no significant difference regarding displacement (p = 0.14). Conclusion: In the static tests, the plantar angle-stable plate construct was superior to the dorsomedial angle-stable plate construct. Clinical Relevance: Plantar plating appears to offer biomechanical benefit. Clinical studies will be required to show whether this translates into earlier resumption of weightbearing and into lower rates of nonunion.

Single Versus Dual Headless Compression Screw Fixation of Scaphoid Nonunions: A Biomechanical Comparison

Hand ◽  
2021 ◽  
pp. 155894472097411
Author(s):  
Luke T. Nicholson ◽  
Kristen M. Sochol ◽  
Ali Azad ◽  
Ram Kiran Alluri ◽  
J. Ryan Hill ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Qualitative Assessment ◽  
Secondary Outcome ◽  
Scaphoid Nonunion ◽  
Compression Screw ◽  
Single Screw ◽  
Headless Compression Screw ◽  
Significant Difference ◽  
Load To Failure ◽  
Headless Compression Screws

Background: Management of scaphoid nonunions with bone loss varies substantially. Commonly, internal fixation consists of a single headless compression screw. Recently, some authors have reported on the theoretical benefits of dual-screw fixation. We hypothesized that using 2 headless compression screws would impart improved stiffness over a single-screw construct. Methods: Using a cadaveric model, we compared biomechanical characteristics of a single tapered 3.5- to 3.6-mm headless compression screw with 2 tapered 2.5- to 2.8-mm headless compression screws in a scaphoid waist nonunion model. The primary outcome measurement was construct stiffness. Secondary outcome measurements included load at 1 and 2 mm of displacement, load to failure for each specimen, and qualitative assessment of mode of failure. Results: Stiffness during load to failure was not significantly different between single- and double-screw configurations ( P = .8). Load to failure demonstrated no statistically significant difference between single- and double-screw configurations. Using a qualitative assessment, the double-screw construct maintained rotational stability more than the single-screw construct ( P = .029). Conclusions: Single- and double-screw fixation constructs in a cadaveric scaphoid nonunion model demonstrate similar construct stiffness, load to failure, and load to 1- and 2-mm displacement. Modes of failure may differ between constructs and represent an area for further study. The theoretical benefit of dual-screw fixation should be weighed against the morphologic limitations to placing 2 screws in a scaphoid nonunion.

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 Comparison of Bioabsorbable Magnesium versus Titanium Screw Fixation for Modified Distal Chevron Osteotomy in Hallux Valgus

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Baver Acar ◽  
Ozkan Kose ◽  
Adil Turan ◽  
Melih Unal ◽  
Yusuf Alper Kati ◽  
...  
Keyword(s):  
Hallux Valgus ◽  
Screw Fixation ◽  
Clinical Results ◽  
Significant Loss ◽  
Compression Screw ◽  
Titanium Screw ◽  
Chevron Osteotomy ◽  
Valgus Angle ◽  
Significant Difference ◽  
Screw Group

Objective. The purpose of this retrospective study was to compare the clinical and radiological results of magnesium versus titanium screw fixation for modified distal chevron osteotomy in hallux valgus (HV). Materials and Methods. A total of 31 patients who underwent modified distal chevron osteotomy for HV deformity between 2014 and 2017 were reviewed retrospectively. Headless magnesium (Mg) compression screw fixation was applied in 16 patients (17 feet) and headless titanium (Ti) compression screw in 15 patients (17 feet). Patients were followed up for at least 12 months with a mean of 19.0 ± 6.8 months in the Mg screw group and 16.2 ± 6.19 in the Ti screw group, respectively (p: 0.234). Clinical results were evaluated using the American Orthopedic Foot and Ankle Society Hallux metatarsophalangeal-interphalangeal (AOFAS-MTP-IP) scale and a visual analogue scale (VAS). The hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured before and after surgery. Time to osteotomy union and any complications were recorded and compared between the groups. Results. An improvement in the AOFAS-MTP-IP scale and VAS points were recorded in both groups with no statistically significant difference between the groups (p: 0.764 and 0.535, resp.). At the final follow-up examination, HVA and IMA were similar (p: 0.226 and 0.712, resp.). There was no significant loss of correction between the early and final radiographs in respect of HVA and IMA in both groups (p: 0.321 and p: 0.067). Full union of the osteotomy was obtained in all patients. Prolonged (1.5 months) swelling and mild hyperemia around the surgical incision were observed in 1 patient in the Mg group but there was a good response to physical and medical therapy, and the complaints were completely resolved. There were no other significant complications in either group. Conclusion. The results of this study showed that bioabsorbable Mg compression screw fixation has similar therapeutic efficacy to Ti screw fixation in respect of functional and radiological outcomes. Bioabsorbable Mg screw is an alternative fixation material that can be safely used for modified distal chevron osteotomy in HV surgery.

Low-Profile Dual Small Plate Fixation Is Biomechanically Similar to Larger Superior or Anteroinferior Single Plate Fixation of Midshaft Clavicle Fractures

2019 ◽  
Vol 47 (11) ◽  
pp. 2678-2685 ◽  
Author(s):  
Connor G. Ziegler ◽  
Zachary S. Aman ◽  
Hunter W. Storaci ◽  
Hannah Finch ◽  
Grant J. Dornan ◽  
...  
Keyword(s):  
Plate Fixation ◽  
Bending Stiffness ◽  
Torsional Stiffness ◽  
Single Plate ◽  
Low Profile ◽  
Significant Difference ◽  
Dual Plating ◽  
Load To Failure ◽  
Clavicle Fractures ◽  
Cadaveric Model

Background: Limited biomechanical data exist for dual small plate fixation of midshaft clavicle fractures, and no prior study has concurrently compared dual small plating to larger superior or anteroinferior single plate and screw constructs. Purpose: To biomechanically compare dual small orthogonal plating, superior plating, and anteroinferior plating of midshaft clavicle fractures by use of a cadaveric model. Study Design: Descriptive laboratory study. Methods: The study used 18 cadaveric clavicle specimens (9 pairs total), and 3 plating techniques were studied: anteroinferior, superior, and dual. The dual plating technique used smaller diameter plates and screws (1.6-mm thickness) than the other, single plate techniques (3.3-mm thickness). Each of the 9 clavicle pairs was randomly assigned a combination of 2 plating techniques, and randomization was used to determine which techniques were used for the right and left specimens. Clavicles were plated and then osteotomized to create an inferior butterfly fracture model, which was then fixed with a single interfragmentary screw. Clavicle specimens were then potted for mechanical testing. Initial bending, axial, and torsional stiffness of each construct was determined through use of a randomized nondestructive cyclic testing protocol followed by load to failure. Results: No significant differences were found in cyclical axial ( P = .667) or torsional ( P = .526) stiffness between plating groups. Anteroinferior plating demonstrated significantly higher cyclical bending stiffness than superior plating ( P = .005). No significant difference was found in bending stiffness between dual plating and either anteroinferior ( P = .129) or superior plating ( P = .067). No significant difference was noted in load to failure among plating methods ( P = .353). Conclusion: Dual plating with a smaller plate-screw construct is biomechanically similar to superior and anteroinferior single plate fixation that uses larger plate-screw constructs. No significant differences were found between dual plating and either superior or anteroinferior single plating in axial, bending, or torsional stiffness or in bending load to failure. Dual small plating is a viable option for fixing midshaft clavicle fractures and may be a useful low-profile technique that avoids a larger and more prominent plate-screw construct. Clinical Relevance: Plate prominence and hardware irritation are commonly reported complaints and reasons for revision surgery after plate fixation of midshaft clavicle fractures. Dual small plate fixation has been used to improve cosmetic acceptability, minimize hardware irritation, and decrease reoperation rate. Biomechanically, dual small plate fixation performed similarly to larger single plate fixation in this cadaveric model of butterfly fracture.

A Biomechanical Comparison of Micromotion after Ankle Fusion Using 2 Fixation Techniques: Intramedullary Arthrodesis Nail or Ilizarov External Fixator

2008 ◽  
Vol 29 (3) ◽  
pp. 334-341 ◽  
Author(s):  
Austin T. Fragomen ◽  
Kathleen N. Meyers ◽  
Nicole Davis ◽  
Hengsheng Shu ◽  
Timmothy Wright ◽  
...  
Keyword(s):  
External Fixation ◽  
Bone Mineral ◽  
External Fixator ◽  
Mineral Density ◽  
Ilizarov External Fixator ◽  
Ankle Fusion ◽  
Wide Range ◽  
Significant Difference ◽  
Fusion Site ◽  
New Generation

Background: In difficult ankle arthrodesis situations, intramedullary (IM) arthrodesis nails and external fixation are often considered in lieu of standard fusion techniques. The purpose of this study was to compare the amount of micromotion measured across an ankle fusion site stabilized with either an IM nail or with the Ilizarov external fixator. Materials and Methods: The relative bone mineral density of 8 pairs of human cadaveric lower legs was measured by DEXA scanning. One specimen from each pair was randomly assigned to be stabilized with a new generation IM nail and the other with an Ilizarov external fixator. Specimens were tested in compression, rotation, and dorsiflexion. Optical motion capture was used to measure the direct motion occurring at the fusion site. Results: No significant difference was found between the axial displacements ( p = 0.94), torsional displacement ( p = 0.07), or the dorsiflexion angular displacement ( p = 0.28) for the IM rod group and the external fixation group. A weak correlation was found between BMD and displacement. Conclusion: Both the new generation IM nail and the Ilizarov external fixator imparted excellent stability to the fusion site despite a wide range of bone mineral densities. Medialization of the talus, the ability to compress the nail, and the addition of a posterior-to-anterior locking screw were thought to improve the performance of the nail. Clinical Relevance: Both IM nail and Ilizarov external fixation provided excellent fusion site stability. The decision of which implant to use for complex arthrodesis should be dictated by the clinical needs.

scholarly journals Comparison of Dorsal Plate Fixation Versus Intramedullary Headless Screw Fixation of Unstable Metacarpal Shaft Fractures

Hand ◽  
2016 ◽  
Vol 11 (4) ◽  
pp. 421-426 ◽  
Author(s):  
Eitan Melamed ◽  
Richard M. Hinds ◽  
Michael B. Gottschalk ◽  
Oran D. Kennedy ◽  
John T. Capo
Keyword(s):  
Locking Plate ◽  
Plate Fixation ◽  
Dorsal Plate ◽  
Locking Plates ◽  
Shaft Fractures ◽  
Plate Group ◽  
Metacarpal Shaft ◽  
Load To Failure ◽  
Group 5 ◽  
Group 2

Background: Recently, intramedullary headless screw (IMHS) has shown promise as an alternative to dorsal plate fixation of metacarpal fractures. The purpose of this study was to assess the biomechanical performance of IMHS versus plating. We hypothesized that IMHS fixation provides inferior stability to plating. Methods: Metacarpal fracture model with 3-mm of volar gapping in forty-four human cadaveric metacarpals was created. The specimens were divided into 5 groups: Group 1, 1.5-mm non-locking plate; Group 2, 1.5-mm locking plate; Group 3, 2.0-mm non-locking plate; Group 4, 2.0-mm locking plate; and Group 5, 2.4-mm short cannulated IMHS. A 4-point bending model was used to assess load-to failure (LTF) and stiffness. Results: Mean LTF was 364 ± 130 N for 1.5-mm non-locking plates, 218 ± 94 N for 1.5-mm locking plates, 421 ± 86 N for 2.0-mm non-locking plates, 351 ± 71 N for 2.0-mm locking plates, and 75 ± 20 N for IMHS. Mean stiffness was 91 ± 12 N/mm for 1.5-mm non-locking plates, 110 ± 77 N/mm for 1.5-mm locking plates, 94 ± 20 N/mm for 2.0-mm non-locking plates, 135 ± 16 N/mm for 2.0-mm locking plates, and 55 ± 15 N/mm for IMHS. IMHS demonstrated significantly lower LTF and stiffness than plates. Conclusions: IMHS fixation of unstable metacarpal shaft fractures offers less stability compared to plating when loaded in bending. The LTF and stiffness of IMHS versus plating of metacarpal shaft fractures has not been previously quantified. Our results reveal that IMHS fixation is less favorable biomechanically and should be carefully chosen in regards to fracture stability.

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