The effect of plate design, bridging span, and fracture healing on the performance of high tibial osteotomy plates (original) (raw)
Related papers
Journal of Experimental Orthopaedics, 2015
Background: As several new tibial osteotomy plates recently appeared on the market, the aim of the present study was to compare mechanical static and fatigue strength of three newly designed plates with gold standard plates for the treatment of medial knee joint osteoarthritis. Methods: Sixteen fourth-generation tibial bone composites underwent a medial open-wedge high tibial osteotomy (HTO) according to standard techniques, using five TomoFix standard plates, five PEEKPower plates and six iBalance implants. Static compression load to failure and load-controlled cyclic fatigue failure tests were performed. Forces, horizontal and vertical displacements were measured; rotational permanent plastic deformations, maximal displacement ranges in the hysteresis loops of the cyclic loading responses and dynamic stiffness were determined. Results: Static compression load to failure tests revealed that all plates showed sufficient stability up to 2400 N without any signs of opposite cortex fracture, which occurred above this load in all constructs at different load levels. During the fatigue failure tests, screw breakage in the iBalance group and opposite cortex fractures in all constructs occurred only under physiological loading conditions (<2400 N). The highest fatigue strength in terms of maximal load and number of cycles performed prior to failure was observed for the ContourLock group followed by the iBalance implants, the TomoFix standard (std) and small stature (sm) plates. The PEEKPower group showed the lowest fatigue strength. Conclusions: All plates showed sufficient stability under static loading. Compared to the TomoFix and the PEEKPower plates, the ContourLock plate and iBalance implant showed a higher mechanical fatigue strength during cyclic fatigue testing. These data suggest that both mechanical static and fatigue strength increase with a wider proximal T-shaped plate design together with diverging proximal screws as used in the ContourLock plate or a closed-wedge construction as in the iBalance design. Mechanical strength of the bone-implant constructs decreases with a narrow T-shaped proximal end design and converging proximal screws (TomoFix) or a short vertical plate design (PEEKPower Plate). Whenever high mechanical strength is required, a ContourLock or iBalance plate should be selected.
Biomechanical evaluation of different fixation plates in medial opening upper tibial osteotomy
The Knee, 2007
In this biomechanical study, 25 in vitro calf tibial models were used in order to compare the stability of the plates under axial compression loading. A 10-mm medial opening gap was stabilized in each of the five calf tibial models either with four or two-holed rectangular shaped plates with wedges, with four-holed reversed L-shaped plates with wedges, with the combination of these two types of plates, or with sixholed anatomical T-plates. The compression behavior of the model was tested by using a universal mechanical testing system. The specimens fixed with the combination of plates with the four-holed reversed L-shaped and with two-holed rectangular shaped; or with six-holed anatomical T-plates, showed significantly better stability than those of others. Four different kinds of failure (slippage of wedge, lateral cortex fracture, damage and/or loosening of screws, and bending of plates) were observed on the models. When the average value of force loading on the plates that were designed by the first author was considered, the plates were stable and the average force values at these points were higher than the loading force on a knee during the normal paced walking or running conditions.
Comparative Study of Medial Opening-Wedge High Tibial Osteotomy Using 2 Different Implants
Arthroscopy: The Journal of Arthroscopic & Related Surgery, 2013
The purpose of this study was to perform a retrospective clinical and radiographic evaluation after openingwedge high tibial osteotomy (HTO) using a short spacer plate (Aescula; B. Braun Korea, Seoul, South Korea) and rigid long plate (TomoFix plate; Mathys, Bettlach, Switzerland) at follow-up 2 years postoperatively. Methods: We performed 94 opening-wedge HTOs with the Aescula plate (group I) and 92 HTOs with the TomoFix plate (group II). Patients underwent clinical and radiographic evaluations preoperatively and at 2 years postoperatively. Clinical evaluations were performed with Knee Society scores. Radiographic analysis included the mechanical tibiofemoral angle (mTFA) and the slope of the tibia angle with preoperative and postoperative full weightebearing anteroposterior whole-leg views, as well as anteroposterior, lateral, and Merchant views of the knee. We measured the mTFA. In addition, we evaluated the complications in each group. The follow-up period was 2 years. Results: At follow-up 2 years postoperatively, we observed an overall complication rate of 38% in group I and 26% in group II (P ¼ .083). We found plate-related complication rates of 20% in group I and 9% in group II (P ¼ .039). Plate-related complications included loss of correction, fracture of the tibial plateau, screw failure, malunion, and fracture of the lateral cortical bone. The mean mTFA was À6.0 AE 3.2 in group I and À4.6 AE 2.8 in group II preoperatively (P ¼ .262). The mean mTFA was 1.0 AE 3.1 in group I and 1.5 AE 2.3 in group II at the latest follow-up (P ¼ .034). In group I, the mean Knee Society knee score and function score were 60.0 AE 12.9 and 57.9 AE 26.8, respectively, preoperatively. They improved to 92.1 AE 8.1 and 89.0 AE 15.1, respectively, at follow-up (P ¼ .001 and P ¼ .001, respectively). In group II, the mean Knee Society knee score and function score were 57.5 AE 14.8 and 57.4 AE 22.1, respectively, preoperatively. They improved to 95.5 AE 5.4 and 95.0 AE 7.6, respectively, at follow-up (P ¼ .001 and P ¼ .001, respectively). In addition, the mean postoperative knee score and function score in group II were higher than those in group I (P ¼ .001 and P ¼ .001, respectively). Conclusions: We have shown a high plate-related complication rate and a significant loss of correction during a short-term follow-up period (2 years) after opening-wedge HTO using the new short spacer HTO plate compared with the rigid long plate. Level of Evidence: Level IV, therapeutic case series.
Veterinary Surgery, 2009
Objective-To compare the axial compression stiffness of osteotomized canine tibiae stabilized with Slocum, Securos, or Synthes plates after a tibial plateau leveling osteotomy (TPLO) procedure. Study Design-In vitro, paired comparison of cadaveric tibial constructs subjected to mechanical testing under an axial load. Sample Population-Canine tibiae (n ¼ 16 pairs) from skeletally mature male and female dogs of various breeds (18-55 kg). Methods-Tibial pairs (n ¼ 16) were randomly assigned to 1 of 2 study cohorts (n ¼ 8 pairs/cohort): cohort 1, tibial osteotomy stabilization with a Slocum or a Securos plate, or cohort 2, tibial osteotomy stabilization with a Slocum or a Synthes plate. One tibia from each pair was stabilized with 1 of each plate design assigned to the cohort after TPLO. A 3.2 mm osteotomy gap was maintained during plate application in all constructs. Load and axial displacement were recorded while constructs were loaded to 2000 N in axial compression. Failure loads were not reported because no distinct yield point or failure point was evident within the load range for many specimens. Failure modes were recorded for each construct, and photographs of typical failures were obtained. Stiffness (N/mm) was calculated from load-displacement curves. Paired comparisons of mean stiffness were performed within study groups using a paired t-test. Significance was set at Po.05. Results-The mean construct stiffnesses for the Slocum (383 AE 183 N/mm) and Securos (258 AE 64.1 N/mm) constructs were not significantly different (P ¼ .164; power ¼ 0.566). The mean construct stiffness for the Synthes constructs (486 AE 91.0 N/mm) was significantly greater than that of the Slocum constructs (400 AE 117 N/mm); P ¼ .0468. Modes of failure for the Slocum (16/16) and Securos (8/8) constructs included plastic deformation of the implant with valgus deformity combined with fibular luxation (2/16 Slocum; 1/8 Securos) or fibular fracture (2/16 Slocum; 4/8 Securos). Most Synthes constructs underwent elastic deformation (7/8). One Synthes construct fractured in the saggital plane through the tibial plateau depression at the point of load application. Conclusions-The Slocum and Securos plate/tibia construct have similar stiffness, whereas the Synthes/tibia constructs are significantly stiffer than the Slocum/tibia constructs. Modes of fixation failure observed in this model were consistent with TPLO fixation failures observed clinically. Clinical relevance-Construct stiffness in axial load varies with implant type. Implants that confer higher stiffness to the construct may result in greater fixation stability in tibial metaphyseal osteotomies.
Finite element analysis of Puddu and Tomofix plate fixation for open wedge high tibial osteotomy
The use of open wedge high tibial osteotomy (HTO) to correct varus deformity of the knee is well established. However, the stability of the various implants used in this procedure has not been previously demonstrated. In this study, the two most common types of plates were analysed (1) the Puddu plates that use the dynamic compression plate (DCP) concept, and (2) the Tomofix plate that uses the locking compression plate (LCP) concept. Three dimensional model of the tibia was reconstructed from computed tomography images obtained from the Medical Implant Technology Group datasets. Osteotomy and fixation models were simulated through computational processing. Simulated loading was applied at 60:40 ratios on the medial:lateral aspect during single limb stance. The model was fixed distally in all degrees of freedom. Simulated data generated from the micromotions, displacement and, implant stress were captured. At the prescribed loads, a higher displacement of 3.25 mm was observed for the Puddu plate model (p < 0.001). Coincidentally the amount of stresses subjected to this plate, 24.7 MPa, was also significantly lower (p < 0.001). There was significant negative correlation (p < 0.001) between implant stresses to that of the amount of fracture displacement which signifies a less stable fixation using Puddu plates. In conclusion, this study demonstrates that the Tomofix plate produces superior stability for bony fixation in HTO procedures.
BMC musculoskeletal disorders, 2014
Medial open wedge high tibial osteotomy is a well-established procedure for the treatment of unicompartmental osteoarthritis and symptomatic varus malalignment. We hypothesized that different fixation devices generate different fixation stability profiles for the various wedge sizes in a finite element (FE) analysis. Four types of fixation were compared: 1) first and 2) second generation Puddu plates, and 3) TomoFix plate with and 4) without bone graft. Cortical and cancellous bone was modelled and five different opening wedge sizes were studied for each model. Outcome measures included: 1) stresses in bone, 2) relative displacement of the proximal and distal tibial fragments, 3) stresses in the plates, 4) stresses on the upper and lower screw surfaces in the screw channels. The highest load for all fixation types occurred in the plate axis. For the vast majority of the wedge sizes and fixation types the shear stress (von Mises stress) was dominating in the bone independent of fixat...
2014
Background: Implants for fracture and/or osteotomy fixation are often tested according to basic mechanical test models such as open gap tests or 4-point-bending tests. These may be suitable to test and compare different implants for safety and clinical approval, but are not always representative of the post-operative situation, which is decisive when it comes to bone healing. In the current study the Knee Expert Group of the Association for the Study of Internal Fixation has compared the available open gap test results of the latest version of the TomoFix Medial Distal Femoral Plate and the antecedent plate design, with the test results of a more physiological and lifelike test model. In the open gap test model the antecedent plate design was found to have superior stiffness and fatigue strength. Methods: In the current study simulated postoperative conditions for medial closing wedge supracondylar osteotomies were used. The constructs were subjected to cyclical axial and torsional loading and were subsequently tested to failure. Results: The more lifelike tests in this study showed that the latest version was either more or equally stable and stiff than the antecedent version of the plate, in all of the tests. It is argued that the difference in results between the two loading models is due to differences in test design. Conclusions: These test results stress the importance of not only using standard open gap and 4-point-bending tests, but also to use as lifelike as possible test conditions for any form of biomechanical testing of new implants.
Acta chirurgica iugoslavica, 2013
Back ground: The sta bil ity of the open wedge high tib ial osteotomy is de pend ent on an un dam aged cor ti cal hinge and de sign of the plate. Aims: We eval u ated the pri mary sta bil ity of two in ter nal fix a tion de vices for open wedge high tib ial osteotomy. Meth ods: Five pairs of cadaveric tibia with 10 ° valgus cor rec tion were sta bi lized with a newly de signed plate with hy brid fix a tion and 10 mm spacer block and with con ven tional T plate with 10 mm spacer block. Static ax ial loads were ap plied un til ul ti mate fail ure of the con struct. Re sults: The av er age load at ini tial fail ure of the new plate construct was 4757.7 N com pared to 3022.43 N ob tained with the T plate, (p<0.01). The dif fer ence in ini tial stiff ness of both con structs was not sig nif i cant (p=0.27). The mean ul ti mate load at fail ure of the new plate con struct was 5280.6 N com pared to 3635.3N obtained with the T plate, (p=0.001). Con clu sion: The new plate with hy brid fix a tion, pro vides sub stan tial load re sis tance but sim i lar stiff ness when com pared to stan dard T plate.
Biomechanical Study of the Osteosynthesis Stiffness with Bridging Plates in Cadaveric Tibial Models
2010
Tibial diaphyseal fractures are the most frequent among long bone fractures. It is estimated that around 300,000 new fractures are treated per year in the USA, and around 50,000 in Brazil.1 The classification used most often in the evaluation of these fractures is that proposed by the AO group, where type A fractures are simple, those of type B present a wedge fracture, and those of type C are complex comminutive fractures.2 Osteosynthesis by the relative stability principle is indicated in type C fractures, whereas the implant options for obtainment of this principle are external fixation, intramedullary nail and bridging plate. The intramedullary locking nail is considered by many authors to be the method of choice in the definitive treatment of type C diaphyseal fractures of the long bones of the lower limbs. However, there are situations where the use of the nail is limited, such as in diaphyseal fractures with articular extension, fracture traces in the diaphyseal-metaphyseal t...