In-vivo stiffness assessment of distal femur fracture locked plating constructs

Parks, Christopher D.; McAndrew, Christopher M.; Spraggs-Hughes, Amanda; Ricci, William M.; Silva, Matthew J.; Gardner, Michael J.

doi:10.1016/j.clinbiomech.2018.05.012

Cited by 14 publications

(12 citation statements)

References 22 publications

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“…Although the ideal stiffness and motion cannot be determined, overall structural stiffness can be modified by choosing different implants, screw types, and positions of the screw or plate [ 12 , 13 ]. When the stability is too high (in other words, the strain is too low), it may result in nonunion [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Micromotion-based balanced drilling technology to increase near cortical strain

et al. 2022

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Objective A micromotion-based balanced drilling system was designed based on a locking plate (LP) and far cortical locking (FCL) concept to maintain the balance of micromotions of the cortex on both sides of a fracture region. The system was tested by axial compression test. Methods The fracture gap was set to 2 cm, and locking screws with a diameter of 5 mm and a locking plate were used to fix it. The diameters of the two sections of the stepping drill were 3.5 mm and 5.0 mm, respectively. One of the matching drilling sleeves was a standard sleeve (eccentricity, 0 mm) and the other was an eccentric sleeve (proximal eccentricity, 1 mm). A model of the fixed locking plate (AO/ASIF 33-A3) for distal femoral fractures with a gap of 2 cm was established based on data from 42 artificial femurs (SAWBONE). According to the shape of the screw holes on the cortex, the fixed fracture models were divided into a control group (standard screw hole group X126, six cases) and an experimental group (elliptical screw hole group N, 36 cases). The experimental group was further divided into six subgroups with six cases in each (N126, N136, N1256, N1356, N12356, N123456), based on the number and distribution of the screws on the proximal fracture segment. The control, N126, and N136 groups were subjected to an axial load of 500 N, and the other groups were subjected to an axial load of 1000 N. The displacements of the kinetic head, far cortex, and near cortex were measured. The integral structural stiffness of the model and the near cortical strain were calculated. The data of each group were analyzed by using a paired t-test. Results When the far cortical strains were 2%, 5%, and 10%, the near cortical strains in group N126 were 0.96%, 2.35%, and 4.62%, respectively, significantly higher than those in the control group (X126) (p < 0.05). For a different distribution of the screws, when the far cortical strains were 2%, 5%, and 10%, the near cortical strains in group N126 were significantly higher than those in group N136 (p < 0.05). However, there was no significant difference between the near cortical strains in the two groups with four screws (p > 0.05). For different numbers of screws, the near cortical strains in the three-screw groups were significantly higher than those in the four-screw groups (p < 0.05), and there was no significant difference in near cortical strains among the four-, five-, and six-screw groups (p > 0.05). Conclusion The proposed drill and matching sleeves enabled a conventional locking compression plate to be transformed into an internal fixation system to improve the balanced motion of the near and far cortices. Thus, strain on a fracture site could be controlled by adjusting the diameter of the drill and the eccentricity of the sleeve.

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Section: Introductionmentioning

confidence: 99%

Micromotion-based balanced drilling technology to increase near cortical strain

et al. 2022

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“…In retrospective analyses of in vivo factors associated with distal femoral LCP fixation failure in humans, working length was not significantly associated with implant failure or with nonunion [ 12 , 26 ]. In addition, in a retrospective analysis of locking plate fixation stiffness as a function of working length, neither fixation working length nor the ratio of working length to plate length were correlated with overall fixation stiffness or with complications such as delayed union or nonunion [ 24 ]. In the current study, working length was directly reflective of the selected plate length, and both short plate length and lower tibial coverage ratios were significantly associated with fixation failure.…”

Section: Discussionmentioning

confidence: 99%

“…Patient factors such as age, concurrent systemic disease, diabetes, a history of smoking, and obesity were consistently associated with postoperative complications including infection and reoperation, but additional plate-specific factors of plate length (total) and plate length proximal to the fracture line were significantly associated with implant failure [ 26 ]. In retrospective analysis of fracture nonunion following LCP fixation of human distal femoral fractures, plate characteristics including number of locking screws in the proximal fragment and plate material (stainless steel) were significantly associated with nonunion but the factors of plate length, working length, and total number of screws were not [ 12 , 24 , 28 , 29 ]. To our knowledge, these locking compression plate characteristics and the effect of plate position have not been assessed in vivo in a caprine segmental defect model.…”

Section: Introductionmentioning

confidence: 99%

In vitro analysis and in vivo assessment of fracture complications associated with use of locking plate constructs for stabilization of caprine tibial segmental defects

et al. 2023

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Purpose Locking plate fixation of caprine tibial segmental defects is widely utilized for translational modeling of human osteopathology, and it is a useful research model in tissue engineering and orthopedic biomaterials research due to its inherent stability while maintaining unobstructed visualization of the gap defect and associated healing. However, research regarding surgical technique and long-term complications associated with this fixation method are lacking. The goal of this study was to assess the effects of surgeon-selected factors including locking plate length, plate positioning, and relative extent of tibial coverage on fixation failure, in the form of postoperative fracture. Methods In vitro, the effect of plate length was evaluated using single cycle compressive load to failure mechanical testing of locking plate fixations of caprine tibial gap defects. In vivo, effects of plate length, positioning, and relative tibial coverage were evaluated using data from a population of goats enrolled in ongoing orthopedic research which utilized locking plate fixation of 2 cm tibial diaphyseal segmental defects to evaluate bone healing over 3, 6, 9, and 12 months. Results In vitro, no significant differences in maximum compressive load or total strain were noted between fixations using 14 cm locking plates and 18 cm locking plates. In vivo, both plate length and tibial coverage ratio were significantly associated with postoperative fixation failure. The incidence of any cortical fracture in goats stabilized with a 14 cm plate was 57%, as compared with 3% in goats stabilized with an 18 cm plate. Craniocaudal and mediolateral angular positioning variables were not significantly associated with fixation failure. Decreasing distance between the gap defect and the proximal screw of the distal bone segment was associated with increased incidence of fracture, suggesting an effect on proximodistal positioning on overall fixation stability. Conclusions This study emphasizes the differences between in vitro modeling and in vivo application of surgical fixation methods, and, based on the in vivo results, maximization of plate-to-tibia coverage is recommended when using locking plate fixation of the goat tibial segmental defect as a model in orthopedic research.

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“…Improvements in outcomes have been reported, probably due to "biologic approaches" and implant developments with nonunion rates of 6% [32]. Among the factors that lead to nonunion are metaphyseal comminution, especially medially, malalignment, poor bone quality, and comorbidities that reduce the adequate vascular supply of the bone, such as smoking, diabetes or vascular disease, and inadequate fixation with devices that are too rigid or plates that are too short [31,33,34]. Cases of non-septic nonunions in patients with good bone stock should be treated by revision of the implant and bone grafting.…”

Section: Complicationsmentioning

confidence: 99%

Distal Femoral Fractures

Reyes¹,

González-Alonso²,

Amhaz-Escanlar³

et al. 2023

Topics in Trauma Surgery

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Distal femur fractures are increasing injuries in our environment, due to their close relationship with the aging of the population. The diagnosis and treatment of these injuries have evolved in recent years, and the availability of new tools allows us to improve the results of our patients. Techniques such as dual nail-plate or plate-plate fixation emerge as an option in complications and complex fractures, and augmentation with PMMA may be an option in very low-density bones. To use these new techniques, anatomical knowledge, especially of the medial aspect of the femur, is essential. Many recent publications have studied the use of minimally invasive techniques with safe pathways. Throughout the following pages, we give a glimpse of the novelties in the treatment of these fractures, and we review the classic concepts.

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In-vivo stiffness assessment of distal femur fracture locked plating constructs

Cited by 14 publications

References 22 publications

Micromotion-based balanced drilling technology to increase near cortical strain

Micromotion-based balanced drilling technology to increase near cortical strain

In vitro analysis and in vivo assessment of fracture complications associated with use of locking plate constructs for stabilization of caprine tibial segmental defects

Distal Femoral Fractures

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