The effect of surgeon-controlled variables on construct stiffness in lateral locked plating of distal femoral fractures

Abstract Background Nonunion following treatment of supracondylar femur fractures with lateral locked plates (LLP) has been reported to be as high as 21 %. Implant related and surgeon-controlled variables have been postulated to contribute to nonunion by modulating fracture-fixation construct stiffness. The purpose of this study is to evaluate the effect of surgeon-controlled factors on stiffness when treating supracondylar femur fractures with LLPs: Does plate length affect construct stiffness given the same plate material, fracture working length and type of screws? Does screw type (bicortical locking versus bicortical nonlocking or unicortical locking) and number of screws affect construct stiffness given the same material, fracture working length, and plate length? Does fracture working length affect construct stiffness given the same plate material, length and type of screws? Does plate material (titanium versus stainless steel) affect construct stiffness given the same fracture working length, plate length, type and number of screws? Methods Mechanical study of simulated supracondylar femur fractures treated with LLPs of varying lengths, screw types, fractureworking lenghts, and plate/screw material. Overall construct stiffness was evaluated using an Instron hydraulic testing apparatus. Results Stiffness was 15 % higher comparing 13-hole to the 5-hole plates (995 N/mm849N vs. /mm, p = 0.003). The use of bicortical nonlocking screws decreased overall construct stiffness by 18 % compared to bicortical locking screws (808 N/mm vs. 995 N/mm, p = 0.0001). The type of screw (unicortical locking vs. bicortical locking) and the number of screws in the diaphysis (3 vs. 10) did not appear to significantly influence construct stiffness (p = 0.76, p = 0.24). Similarly, fracture working length (5.4 cm vs. 9.4 cm, p = 0.24), and implant type (titanium vs. stainless steel, p = 0.12) did also not appear to effect stiffness. Discussion Using shorter plates and using bicortical nonlocking screws (vs. bicortical locking screws) reduced overall construct stiffness. Using more screws, using unicortical locking screws, increasing fracture working length and varying plate material (titanium vs. stainless steel) does not appear to significantly alter construct stiffness. Surgeons can adjust plate length and screw types to affect overall fracture-fixation construct stiffness; however, the optimal stiffness to promote healing remains unknown.

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Effect of semi-rigid locking screws on the stiffness of a fracture-fixation construct: A conceptual finite-element study

Advances in Mechanical Engineering ◽

10.1177/1687814019854577 ◽

2019 ◽

Vol 11 (6) ◽

pp. 168781401985457

Author(s):

Xiao-Hua Pan ◽

Wen-Chuan Chen ◽

Kun-Jhih Lin ◽

Kang-Ping Lin ◽

Cheng-Lung Tsai ◽

...

Keyword(s):

Compressive Load ◽

Skin Incision ◽

Delayed Union ◽

Bone Plate ◽

Long Bone ◽

Structural Stiffness ◽

Locking Screws ◽

Plate Length ◽

Working Length ◽

Locking Screw

Strong stiffness provided by locking-plate system has resulted in nonunion and delayed union for long bone fracture. Longer bone plate can lengthen the working length to reduce the structural stiffness of the fixation device but will enlarge skin incision. Using the semi-rigid locking screw may be helpful but the efficacy was unclear. In simulated fracture model, four rigid locking screws were continually inserted beneath the fracture gap. The other four rigid/semi-rigid locking screws were equally distributed or concentrated at screw holes superior to the fracture gap. Axial compressive load was exerted to compare the biomechanical performance under various screw configurations and plate working length. Results revealed that using the semi-rigid locking screws, the structural stiffness of the fixation structure were lowered by 29.5%–45.1% comparing to the model with the same screw configuration using rigid locking screws. Semi-rigid screw models with shorter working length represented comparable flexibility of the fixation structure to the rigid locking screw model with longer working length. Compared to rigid locking screw, semi-rigid locking screw may provide similar flexibility with shorter bone plate, which may be beneficial to reduce the required plate length so that the skin incision may be minimized for fracture reduction.

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Biomechanical characteristics of allogeneic cortical bone pins designed for fracture fixation

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.3415/vcot-07-03-0026 ◽

2008 ◽

Vol 21 (02) ◽

pp. 140-146

Author(s):

M. R. Edwards ◽

S. P. James ◽

W. S. Dernell ◽

R. J. Scott ◽

A. M. Bachand ◽

...

Keyword(s):

Stainless Steel ◽

Cortical Bone ◽

Fracture Fixation ◽

Impact Testing ◽

Left Tibia ◽

Four Point Bending ◽

And Gender ◽

The Right ◽

Biomechanical Comparison ◽

Better Than

SummaryThe biomechanical characteristics of 1.2 mm diameter allogeneic cortical bone pins harvested from the canine tibia were evaluated and compared to 1.1 mm diameter stainless steel pins and 1.3 mm diameter polydioxanone (PDS) pins using impact testing and four-point bending. The biomechanical performance of allogeneic cortical bone pins using impact testing was uniform with no significant differences between sites, side, and gender. In four-point bending, cortical bone pins harvested from the left tibia (204.8 ± 77.4 N/mm) were significantly stiffer than the right tibia (123.7 ± 54.4 N/mm, P=0.0001). The site of bone pin harvest also had a significant effect on stiffness, but this was dependent on interactions with gender and side. Site C in male dogs had the highest mean stiffness in the left tibia (224.4 ± 40.4 N/mm), but lowest stiffness in the right tibia (84.9 ± 24.2 N/mm). Site A in female dogs had the highest mean stiffness in the left tibia (344.9 ± 117.4 N/mm), but lowest stiffness in the right tibia (60.8 ± 3.7 N/mm). The raw and adjusted bending properties of 1.2 mm cortical bone pins were significantly better than 1.3 mm PDS pins, but significantly worse than 1.1 mm stainless steel pins (P<0.0001). In conclusion, cortical bone pins may be suitable as an implant for fracture fixation based on initial biomechanical comparison to stainless steel and PDS pins used in clinical practice.

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Long Segment Blocking Screws Increase the Stability of Retrograde Nail Fixation in Geriatric Supracondylar Femur Fractures

Journal of Orthopaedic Trauma ◽

10.1097/bot.0000000000001284 ◽

2018 ◽

Vol 32 (11) ◽

pp. 559-564 ◽

Cited By ~ 4

Author(s):

Darryl Auston ◽

David Donohue ◽

Kyle Stoops ◽

Jacob Cox ◽

Miguel Diaz ◽

...

Keyword(s):

Femur Fractures ◽

Retrograde Nail ◽

The Stability ◽

Supracondylar Femur Fractures

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Management of ipsilateral supracondylar femur fractures following total knee arthroplasty

The Journal of Arthroplasty ◽

10.1016/0883-5403(94)90099-x ◽

1994 ◽

Vol 9 (5) ◽

pp. 521-526 ◽

Cited By ~ 128

Author(s):

Frank Chen ◽

Michael A Mont ◽

Robert S Bachner

Keyword(s):

Total Knee Arthroplasty ◽

Knee Arthroplasty ◽

Femur Fractures ◽

Total Knee ◽

Supracondylar Femur Fractures

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Comparison of outcomes of supracondylar femur fractures treated with locking compression plate vs supracondylar nail

Surgical Update: International Journal of Surgery and Orthopedics ◽

10.17511/ijoso.2017.i04.05 ◽

2017 ◽

Vol 3 (4) ◽

pp. 120-126

Author(s):

Dr. Abhijeet Sudhir Shroff ◽

◽

Dr. Dhammapal Sahebrao Bhamare ◽

Dr. Prafulla Herode ◽

Dr. Mohan Hansraj Sadaria ◽

...

Keyword(s):

Locking Compression Plate ◽

Femur Fractures ◽

Compression Plate ◽

Supracondylar Femur Fractures

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A prospective study on surgical fixation of complex supracondylar femur fracture with distal femoral locking compression plate: our experiences at a tertiary care centre

International Journal of Research in Orthopaedics ◽

10.18203/issn.2455-4510.intjresorthop20203731 ◽

2020 ◽

Vol 6 (5) ◽

pp. 1057

Author(s):

Rajesh Kumar Sharma ◽

Anuradha Upadhyay ◽

Rahul Parmar

Keyword(s):

Prospective Study ◽

Tertiary Care ◽

Clinical Results ◽

Lateral Approach ◽

Locking Compression Plate ◽

Tertiary Care Centre ◽

Non Union ◽

Femur Fractures ◽

Compression Plate ◽

Supracondylar Femur Fractures

Background: The optimal treatment of complex supracondylar femur fractures remains always challenging and controversial. the purpose of this prospective study was to evaluate the efficacy of distal femoral locking compression plate (DF-LCP) in terms of functional outcome and union rate for highly unstable complex supracondylar femur fractures and to determine the influencing factors of an unfavourable outcome.Methods: After obtaining approval from institutional ethics committee, 45 patients with complex supracondylar femur fractures were managed by open reduction and internal fixation with DF-LCP through lateral approach and as per standard protocol. The follow-up results were analysed clinically and radiologically, using the “Schatzker and Lambert criteria” at once in a month for first three months, once in three months up to one year and once in six months thereafter up to 2 years post-operatively.Results: In the present study, average duration of radiological union was 16 (range 12-22) weeks. The average range of motion of knee joint was 105 degrees. Out of 45 patients, clinical results were excellent in 48.9%, good in 17.8%, fair in 22.2% and poor in 11.1% patients according to Schatzker and Lambert criteria. Knee stiffness (7 cases), secondary arthritis (5 cases), and non-union (4 cases) were the main complications observed in this study, which were treated accordingly.Conclusions: DF-LCP holds the metaphyseal bone strongly and prevents metaphyseal collapse and mal-rotation in complex or highly unstable supracondylar femur fractures and simultaneously, it provides stable fixation to promote fracture union and allows early rehabilitation with acceptable complications.

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Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices

Bone and Joint Research ◽

10.1302/2046-3758.71.bjr-2017-0074.r2 ◽

2018 ◽

Vol 7 (1) ◽

pp. 111-120 ◽

Cited By ~ 13

Author(s):

A. MacLeod ◽

A. H. R. W. Simpson ◽

P. Pankaj

Keyword(s):

Numerical Investigation ◽

Fracture Fixation ◽

Computational Models ◽

Locking Plate ◽

Biomechanical Testing ◽

Loading Conditions ◽

Secondary Fracture ◽

Plate Fracture ◽

Fixation Devices ◽

Working Length

ObjectivesSecondary fracture healing is strongly influenced by the stiffness of the bone-fixator system. Biomechanical tests are extensively used to investigate stiffness and strength of fixation devices. The stiffness values reported in the literature for locked plating, however, vary by three orders of magnitude. The aim of this study was to examine the influence that the method of restraint and load application has on the stiffness produced, the strain distribution within the bone, and the stresses in the implant for locking plate constructs.MethodsSynthetic composite bones were used to evaluate experimentally the influence of four different methods of loading and restraining specimens, all used in recent previous studies. Two plate types and three screw arrangements were also evaluated for each loading scenario. Computational models were also developed and validated using the experimental tests.ResultsThe method of loading was found to affect the gap stiffness strongly (by up to six times) but also the magnitude of the plate stress and the location and magnitude of strains at the bone-screw interface.ConclusionsThis study demonstrates that the method of loading is responsible for much of the difference in reported stiffness values in the literature. It also shows that previous contradictory findings, such as the influence of working length and very large differences in failure loads, can be readily explained by the choice of loading condition. Cite this article: A. MacLeod, A. H. R. W. Simpson, P. Pankaj. Experimental and numerical investigation into the influence of loading conditions in biomechanical testing of locking plate fracture fixation devices. Bone Joint Res 2018;7:111–120. DOI: 10.1302/2046-3758.71.BJR-2017-0074.R2.

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