- Open Access
Biomechanical properties of five different currently used implants for open-wedge high tibial osteotomy
© Diffo Kaze et al. 2015
- Received: 9 March 2015
- Accepted: 11 June 2015
- Published: 18 June 2015
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.
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.
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.
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.
- High tibial osteotomy (HTO)
- Mechanical test
- Cyclic and static loading
- Valgus malrotation
High tibial osteotomy (HTO) is a well-established method for the treatment of unicompartmental varus gonarthrosis. Both lateral closing and medial opening techniques exist to produce a valgus alignment (Staubli 2008; Staubli and Jacob 2010). The latter is becoming increasingly popular when performed in a biplanar fashion. Since the introduction of long and rigid-angle stable plates, the frequency of non-unions after an open-wedge HTO has declined significantly (Staubli and Jacob 2010). Apart from a good vascularization of the bone, solid plate fixation is mandatory for rapid bone healing (Staubli 2008; Staubli and Jacob 2010). Although clinical results after HTO often are encouraging some factors associated with a poor long-term outcome such as imprecise osteotomy or loss of the primary correction angle due to poor primary fixation stability of the implant (Spahn et al. 2006; Pornrattanamaneewong et al. 2012).
There are many different implants from different manufacturers available. Biomechanical (Luo et al. 2013; Spahn and Wittig 2002; Stoffel et al. 2004; Zhim et al. 2005; Agneskirchner et al. 2006; Maas et al. 2013; Watanabe et al. 2014) and clinical (Pape et al. 2011; Saeed and Rae 2009; Valkering et al. 2009; Cotic et al. 2014; Woon-Hwa et al. 2013) comparative studies are often performed to help surgeons choose the most appropriate fixation device for the osteotomy.
TomoFix, the long and rigid T-shaped titanium internal fixator with uniaxial locking system (Synthes GmbH, Oberdorf, Switzerland), is currently the gold standard. It combines biomechanical properties that are held accountable for fast bone healing: (1) high primary fixation stability; (2) a compliant bone-implant construct which allows residual micromotion within the osteotomy gap to promote a “callus massage”. TomoFix plates exist in two versions, such as the small stature (sm) version designed for lighter patients and the standard (std) version without weight restriction. Both plates have a narrow proximal design which allows for a biplanar osteotomy, thus enlarging the surface for rapid contact healing (Pape et al. 2010, 2011).
PEEKPower (carbon-fiber reinforced polyetheretherketone (PEEK)) and iBalance (non-absorbable polyetheretherketone)–two implants also indicated for a biplanar osteotomy–were recently designed by Arthrex, a company based in Munich (Germany). The PEEKPower plate is T-shaped, shorter than the TomoFix but coming with a multidirectional locking system. The iBalance implant, a PEEK spacer, is inserted into the osteotomy gap in a uniplanar and closed-wedge-like technique with immediate close contact between the PEEK material and the proximal and distal cortical and spongious bone surface (Pape et al. 2012).
Except for the iBalance system thermoplastic (PEEK), screws were used whereas all other fixation plates used metal screws (titanium alloy or stainless steel).
Sixteen large-size fourth-generation composite analogue tibia bone models (Sawbones, Pacific Research Laboratories, Inc., Vashon Island, Washington, USA) were used in this study since these composite bones have mechanical properties similar to human bones (Chong et al. 2007; Gardner et al. 2010; Heiner 2008). Using artificial composite bones has the advantage of minimizing biomechanical variability between the specimens, which can arise when using cadaveric bones.
Mechanical testing system
The failure types used and their defining criteria
Medial or lateral displacements of the tibial head in relation to the tibial shaft greater than 2 mm. This criterion can only be checked in the unloaded condition.
Visible collapse of the lateral cortex. Small hairline cracks are not considered as failure.
Maximal displacement range greater than 0.5 mm within one hysteresis loop in the case of cyclic testing only.
Cracks of the screws greater than 1 mm
Specimen grouping and assignment, depending on the implants used and the tests performed
Group 1; n = 5 Specimens
Group 2; n = 5 Specimens
Group 3; n = 6 Specimens
Group 4; n = 5 Specimens
Group 5; n = 5 Specimens
Static: Single loading to failure test
TomoFix sm 1
TomoFix sm 2
Dynamic: cyclic fatigue failure test
TomoFix sm 3
TomoFix sm 4
TomoFix sm 5
Type and definition of failure
Defining the failure criteria is decisive since the specimens were never completely damaged. The failure criteria that were used in this biomechanical study are summarized in Table 1 and were already used by Pape et al. (Pape et al., 2010). With type 3 failure the wobble degree or the stability of the sample during the cyclic testing was quantified. This was checked by plotting the force versus the displacement; for nonlinear cases this plot is ideally an elliptical curve with a slope proportional to the stiffness and an enclosed area proportional to the damping of the structure tested. If the specimen becomes unstable and starts to wobble, e. g. after a failure, the width of this curve representing the maximal displacement range increases.
Lateral and vertical stiffness were defined by considering the lateral and the vertical displacements registered by the lateral (LS) and the vertical (VS) sensors respectively. Medial stiffness depends on the implants’ stiffness and is thus not considered.
For the static loading to failure test static stiffness was defined as the ratio of the measured force to the measured displacement at a given time.
Permanent plastic deformation of the specimen
The permanent plastic valgus malrotation of the tibial head, which corresponds to the permanent plastic deflection angle of the tibial plateau at a given time, was defined as the resulting permanent plastic displacements on the medial and the lateral sides in the specimens’ frontal plane.
that is if αp > 0.024 rad or 1.4°, with the index “p” meaning permanent plastic.
The displacements in the direction of the loading (e.g. the vertical descending direction) were considered as to be positive and negative in the opposite direction.
Static loading to failure tests
While considering the vertical descending displacements as positive, the medial displacement (MS) was negative in the cases of the TomoFix std 1 (Fig. 10), TomoFix std 2, PeekPower 1 and iBalance 2. The lateral displacement (LS) was always positive and its absolute value remained greater than the medial displacement. The same applies when the latter was positive for PEEKPower 2 (Fig. 11) and iBalance 1, meaning that the tibial plateau of all specimens rotated during the static loading.
Static tests summary: displacements, valgus malrotation of the tibial head and their corresponding cracks and ultimate loads, including mean values and standard deviations (SD)
Crack / ultimate load [kN]
Medial displ. at crack / ultimate load [mm]
Lateral displ. at crack / ultimate load [mm]
Valgus malrotation of the tibial head at crack / ultimate load (°)
Lateral stiffness at crack / ultimate load [kN/mm]
TomoFix std 1
4.1 / 5.4
0.6 / 1.2
3.1 / 5.0
1.8 / 2.9
1.3 / 1.1
1 and 2
TomoFix std 2
5.1 / 5.2
1.0 / 1.1
4.2 / 4.4
2.5 / 2.6
1.2 / 1.2
1 and 2
4.6 / 5.3
0.8 / 1.2
3.7 / 4.7
2.1 / 2.8
1.3 / 1.1
0.7 / 0.1
0.3 / 0.1
0.8 / 0.4
0.5 / 0.2
0.1 / 0.1
1 and 2
4.2 / 5.1
0.1 / 0.1
2.7 / 3.3
1.3 / 1.5
1.6 / 1.5
1 and 2
TomoFix sm 1
3.1 / 3.2
0.6 / 0.9
1.3 / 1.8
0.9 / 1.3
2.4 / 1.8
TomoFix sm 2
3.2 / 3.6
0.4 / 0.6
1.6 / 2.3
0.9 / 1.4
2.0 / 1.6
3.2 / 3.4
0.5 / 0.8
1.5 / 2.1
0.9 / 1.4
2.2 / 1.7
0.1 / 0.3
0.1 / 0.2
0.2 / 0.4
0 / 0.1
0.3 / 0.1
2.4 / 3.2
0.6 / 0.5
2.5 / 3.9
1.5 / 2.1
1.0 / 0.8
1 and 2
1 and 2
The PEEKPower 2, ContourLock 1, TomoFix std 1 & 2 and ContourLock 2 specimens showed the largest lateral displacements at collapse time. The average displacement on the medial compared to the lateral side was always smaller for all implant types. The determined valgus malrotation of the tibial head was greater or equal to the fixed limit of 1.4° of the permanent deflection angle for all implants, except for the iBalance specimen which showed a mean value of 0.9° (Table 3). The iBalance specimens were the stiffest bone-implant constructs for the performed static loading to failure tests with an average lateral stiffness of 3.1 kN/mm at ultimate load.
Fatigue loading to failure tests
Summary of fatigue failure tests (groups 1, 2 & 3): max. load, vertical & lateral stiffness, number of cycles (all values prior to failure) and failure types
Maximal load [N]
Vertical stiffness KV [N/mm]
Lateral stiffness KL [N/mm]
Number of cycles
TomoFix std 3
TomoFix std 4
TomoFix std 5
Summary of fatigue to failure tests (groups 4 & 5): max. load, vertical & lateral stiffness, number of cycles (all values prior to failure) and failure types
Maximal load [N]
Vertical stiffness KV [N/mm]
Lateral stiffness KL [N/mm]
Number of cycles
TomoFix sm 3
TomoFix sm 4
TomoFix sm 5
Average mean values, including the standard deviations (SD) per group of the cyclic fatigue to failure tests (all decimal values rounded to the 1st decimal)
Maximal load [kN]
Vertical stiffness KV [N/mm]
Lateral stiffness KL [N/mm]
Number of cycles prior to failure
In this study three implants were investigated and compared to our previous study using the same experimental setup and protocol, thus comparing the static and fatigue fixation stability provided by the following five different medial open-wedge HTO plates: the TomoFix std plate, the PEEK Power plate, the iBalance implant, the Contour Lock HTO plate and the TomoFix sm plate. The key findings of the present study were the following: (1) the stiffest bone-implant construct was found to be the iBalance implant followed by the Contour Lock plate. (2) The Contour Lock plate provided highest fatigue strength under cyclic loading conditions. (3) Static loading until failure tests revealed superior strength for the iBalance implant followed by the TomoFix std, the PEEK Power plate, the Contour Lock and the TomoFix sm plates. (4) All implants withstood the maximal physiological vertical tibiofemoral contact force while slow walking. This force corresponds to about three times the body weight (Heinlein et al. 2009; Taylor et al. 2004), e.g. 2400 N for a patient weighing 80 kg.
The principal failure mode of all bone-implant-constructs tested was the collapse of the opposite cortex, which generally occurred quickly after the initial opposite cortex crack. This behavior was observed regardless whether a static or cyclic failure test was applied. This finding correlates with previous studies with the lateral cortex being a medial HTO’s weakest point (Spahn and Wittig 2002; Stoffel et al. 2004; Zhim et al. 2005; Agneskirchner et al. 2006; Maas et al. 2013; Watanabe et al. 2014). The displacements of the lateral side of the osteotomy were more pronounced than the medial displacement, which explains the valgus rotation in the frontal plane of the tibial head during the static and the cyclic loading tests.
The mean ultimate forces were 5.5 kN, 5.3 kN, 4.4 kN, 3.6 kN and 3.4 kN for the iBalance, the TomoFix std, the PEEK Power, the Contour Lock and the TomoFix sm group respectively. Hence, the iBalance and the TomoFix std are superior regarding static performance. The iBalance implant showed however the smallest mean lateral displacement (1.9 mm) at the time of opposite cortex fracture indicating a certain superiority compared to the TomoFix std plates, which failed at the largest mean lateral displacement of 4.7 mm and the largest valgus malrotation of the tibial head of 2.8° thus exceeding the limit of 1.4°, which corresponds to the occurrence of type 1 failure.
Static loading simulates only the standing of a patient. After medial HTO however, patients are also supposed to perform calm activities. The repetitive loadings of the knee are better simulated by fatigue tests. The maximal loads at failure observed during the fatigue tests were all smaller than the threshold value of 2.4 kN (Table 6). Full loading of the knee directly after an osteotomy should therefore be avoided. When considering these maximum loads at failure and the number of cycles carried out, the ContourLock plate performed best with 2.2 kN and 173000 cycles and the PEEKPower plate worst with 1.4 kN and 73000 cycles. Based on these two parameters a ranking for the dynamic analysis would place the iBalance in the second position after the ContourLock, followed by the TomoFix std and the TomoFix sm.
The maintenance of the primary correction is decisive for a positive outcome of the osteotomy. When considering the deformation mode of the specimens during the cyclic loading, a permanent plastic valgus malrotation of the tibial head occurred which caused a valgus deformation of the knee, consequently altering the localization of the mechanical axis and the primary performed correction. The valgus malrotation of the tibial head can be considered as an overcorrection. There was no permanent plastic valgus malrotation of the tibial head observed before the collapse of the specimens, just for the iBalance 6 specimen after failure (Fig. 16). As shown in Fig. 17 retrieved from (Maas et al. 2013), permanent plastic valgus malrotation after failure was observed in the TomoFix sm (group 4) and ContourLock (group 5) groups. As a result we can assume that the TomoFix std and the PEEKPower plates conserve correction better. Therefore the number of load steps performed before failure needs also be taken into account. However this observation is only valid if there was no bone healing prior to the fatigue failure, which is not a realistic scenario.
As indicated in Figs. 13, 14 and 15 the hysteresis loops are growing with damage but do not reach the critical threshold of 0.5 mm (Table 1) for the specimens of the TomoFix std, PEEKPower and iBalance groups. Maas et al. (Maas et al. 2013) reported the occurrence of type 3 failure for the ContourLock group (group 5) and twice within the TomoFix sm (group 4). Thus they concluded that the ContourLock plate was superior to the TomoFix sm plate as far as this parameter is concerned. This result was correlated to the fact that the ContourLock plate is wider and that the fixation screws are more widely spaced than those of the TomoFix sm. In other words, the ContourLock plate is better anchored to the tibial head.
The high mechanical strength of the iBalance construct is most likely due to its higher stiffness compared to other specimens since it is screwed within the osteotomy gap. It thus fills a part of the gap and provides a closed-wedge design with a higher stiffness compared to all other bone-implant constructs (Table 6 and Fig. 18). However there was damage of the iBalance system’s screws observed at very high number of cycles and loading. This underlines the importance of a good positioning of the screws and their anchorage in the tibial head. Though the loading was only vertical the screws and fixation had undergone complex tridimensional loading which is surely even more pronounced in reality than it was in this simplified test. It should be repeated that the screws of the iBalance are thermoplastics (PEEK) and not metallic materials like for the other fixation systems tested.
Agneskirchner et al. (Agneskirchner et al. 2006) also performed static compression load to failure and cyclical load to failure tests using composite bones and compared the stability of four different implants: three spacer plates and a TomoFix plate. The spacer plates were shorter than the TomoFix plate. The loads were also applied vertically to the bone-implant-constructs as it was done in the present study. They reported longer resistance to failure of the specimens for the TomoFix during the static tests. Stoffel et al. (Stoffel et al. 2004) also performed axial compression load to failure tests to compare the TomoFix plate to the Puddu plate (rectangular short spacer plate) by using composite bones and also reported a better axial stability for the TomoFix. Watanabe et al. (Watanabe et al. 2014) also performed a comparative study of the TomoFix and the Puddu plates by using cadaveric bones and reported the highest failure load for the TomoFix. None of the previously cited studies included the iBalance and the PEEKPower implants, whereas we did not include the Puddu plate. The TomoFix plate fixator yielded the best fatigue strength during the cyclic load to failure tests performed by Agneskirchner et al. (Agneskirchner et al. 2006), who reported that a rigid long plate fixator with stable locking bolts provides the best results in open-wedge HTO. Maas et al. (Maas et al. 2013) reported higher fatigue strength for the ContourLock plates when compared to the TomoFix sm plates. This observation diverges somewhat with the findings of Agneskirchner et al. (Agneskirchner et al. 2006). With regard to the results of our study, it can be concluded that the ContourLock was also superior to the TomoFix std regarding the cyclic load to failure tests (Table 6 and Fig. 18). Furthermore the iBalance group showed superior stability than the TomoFix groups in the cyclic loading hence one may conclude that stability provided by a plate is not correlated only to its length, but also to the kind of fixation, which seems to be the governing feature since the plates already have sufficient stiffness and strength.
Clinical studies reported better clinical results in terms of implant-related complications, non-unions and stability (Saeed and Rae 2009; Valkering et al. 2009; Woon-Hwa et al. 2013; Cotic et al. 2014; Staubli et al. 2003) for the TomoFix plates. This high healing rate is supposedly due to the callus-massage effect of the implant, meaning no compression between plate and bone (Staubli et al. 2003), which promotes osteogenesis thanks to the elastic bone-implant construct (Staubli 2008; Staubli and Jacob 2010). This fact is in accord with the present results since the TomoFix plates did not show the highest stiffness in this study. Nevertheless the question of the correlation between the best osteotomy outcomes and the stiffness provided by the implants could be discussed.
The limited number of specimens per group should also be taken into account. The testing procedure differs from reality where muscle forces, bending moments and ligament act together in the knee biomechanics and hence alter the real charging of the plates. As already stated by (Brinkman et al. 2014), it is important to consider life-like test conditions while performing biomechanical testing of implants. The loads applied during the cyclic fatigue testing resemble the physiological loads like when slow walking. However if bone healing takes place before high cycle numbers as those in this study can be reached. Hence one should proceed with caution when applying the results of the present study to clinical settings.
In summary all the tested plates showed sufficient strength during static loading. All specimens failed due to a fracture of the opposite cortical bone. The TomoFix std showed a higher degree of stability than the small stature version. The results of the cyclic load to failure tests show that the stability of the bone-implant constructs is correlated with the fixation design. The ContourLock plate with its wider T-shaped proximal end showed a higher lifespan prior to failure, followed by the iBalance implants due their closed-wedge design which provides higher stiffness to the bone-implants constructs. The TomoFix and the PEEKPower plates with their narrow T-shaped proximal ends showed less rigidity compared to the ContourLock and the iBalance implants. Since healing rates are reported to be high after TomoFix fixation, which is supposedly due to the callus-massage effect of the implant and the elastic bone-implant construct, it remains to be seen whether constructs with a higher mechanical strength have higher bone healing rates with an equal amount of intraoperative safeness than the TomoFix plate, the current golden standard.
Supported by the INTERREG IV Programme of the European Union, Stefan Maas and Dietrich Pape are partners in the project “Experimentelle und klinische Orthopädie der Großregion / Orthopédie Expérimentale et Clinique de la Grande Région” at the Universität der Großregion / Université de la Grande Région (UGR).
- Agneskirchner J, Freiling D, Hurschler C, Lobenhoffer P (2006) Primary stability of four different implants for opening wedge high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 14:291–300PubMedView ArticleGoogle Scholar
- Brinkman J-M, Hurschler C, Agneskirchner J, Lobenhoffer P, Castelein RM, Van Heerwaarden RJ (2014) Biomechanical testing of distal femur osteotomy plate fixation techniques: The role of simulated physiological loading. J Exp Orthop 1:1View ArticleGoogle Scholar
- Chong AC, Miller F, Buxton M, Friis EA (2007) Fracture Toughness and fatigue crack propagation rate of short fiber reinforced epoxy composites for analogue cortical bone. J Biomech Eng 129(4):487–493PubMedView ArticleGoogle Scholar
- Cotic M, Vogt S, Hinterwimmer S, Feucht MJ, Slotta-Huspenina J, Schuster T, Imhoff AB (2014) A matched-pair comparison of two different locking plates for valgus-producing medial open-wedge high tibial osteotomy: peek-carbon composite plate versus titanium plate. Knee Surgery, Sport Traumatology, Arthroscopy, doi: 10.1007/s00167-014-2914-8Google Scholar
- Fowler PJ, Tan JL, Brown GA (2000) Medial opening wedge high tibial osteotomy: how I do it. Oper Tech Sports Med 8:32–38View ArticleGoogle Scholar
- Gardner MP, Chong ACM, Pollock AG, Wooley PH (2010) Mechanical Evaluation of Large-Size Fourth-Generation Composite Femur and Tibia Models. Ann Biomed Eng 38(3):613–620PubMedView ArticleGoogle Scholar
- Heiner AD (2008) Structural properties of fourth-generation composite femurs and tibias. J Biomech 41:3282–3284PubMedView ArticleGoogle Scholar
- Heinlein B, Kutzner I, Graichen F, Bender A, Rohlmann A, Halder AM, Beier A, Bergmann G (2009) ESB clinical biomechanics award 2008: Complete data of total knee replacement loading for level walking and stair climbing measured in vivo with a follow-up of 6-101 months. Clin Biomech 24:315–326View ArticleGoogle Scholar
- ISO 7206-4 (1989) Implants for surgery: Determination of endurance properties of stemmed femoral components with application of torsionGoogle Scholar
- ISO 7206-6 (1992) Implants for surgery: Determination of endurance properties of head and neck region of stemmed femoral componentsGoogle Scholar
- ISO 7206-8 (1995) Implants for surgery: Endurance performance of stemmed femoral components with application of torsionGoogle Scholar
- Lobenhoffer P, Agneskirchner JD (2003) Improvements in surgical technique of valgus high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 3(11):132–138Google Scholar
- Luo C-A, Hua S-Y, Lin S-C, Chen C-M, Tseng C-S (2013) Stress and stability comparison between different systems for high tibial osteotomies. Muscoskel Disord 14:110. doi:10.1186/1471-2474-14-110 View ArticleGoogle Scholar
- Maas S, Diffo Kaze A, Dueck K, Pape D (2013) Static and Dynamic Differences in Fixation Stability between a Spacer Plate and a Small Stature Plate Fixator Used for High Tibial Osteotomies: A Biomechanical Bone Composite Study. ISRN Orthopedics, Volume 2013. doi: 10.1155/2013/387620Google Scholar
- Pape D, Lorbach O, Schmitz C, Busch LC, Van Giffen N, Seil R, Kohn DM (2010) Effect of a biplanar osteotomy on primary stability following high tibial osteotomy: a biomechanical cadaver study. Knee Surg Sports Traumatol Arthrosc 18:204–211PubMedView ArticleGoogle Scholar
- Pape D, Kohn D, Van Giffen N, Hoffman A, Seil R, Lorbach O (2011) Differences in fixation stability between spacer plate and plate fixator following high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc, PubMed. doi: 10.1007/s00167-011-1693-8Google Scholar
- Pape D, Dueck K, Haag M, Lorbach O, Seil R, Madry H (2012) Wedge Volume and osteotomy surface depend on surgical technique for high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 21(1):127–133View ArticleGoogle Scholar
- Pornrattanamaneewong C, Harnroongroj T, Chareancholvanich K (2012) Loss of correction after medial opening wedge high tibial osteotomy: a comparison of locking plate without bone grafts and non-locking compression plates with bone grafts. J Med Assoc Thai 95(9):21–28Google Scholar
- Saeed HZ, Rae PJ (2009) High tibial valgus osteotomy using the Tomofix plate–medium-term results in young patients. Acta Orthop Belg 75(3):360–367Google Scholar
- Spahn G, Wittig R (2002) Primary stability of various implants in tibial opening wedge osteotomy: a biomechanical study. J Orthop Sci 7:683–687PubMedView ArticleGoogle Scholar
- Spahn G, Kirschbaum S, Kahl E (2006) Factors that influence high tibial osteotomy results in patients with medial gonarthritis: a score to predict the results. OsteoArthritis and Cartilage 14:190–195PubMedView ArticleGoogle Scholar
- Staubli AE (2008) Radiological examination of bone healing after open-wedge tibial osteotomy. In: Osteotomies around the knee. Thieme, AO Foundation Publishing, Stuttgart, New York, pp 131–146Google Scholar
- Staubli AE, Jacob H (2010) Evolution of open-wedge high tibial osteotomy: experience with a special angular stable device for internal fixation without interposition material. Int Orthop 34:167–172PubMed CentralPubMedView ArticleGoogle Scholar
- Staubli AE, De Simoni C, Babst R, Lobenhoffer P (2003) TomoFix: a new LCP-concept for open wedge osteotomy of the medial proximal tibia - early results in 92 cases. Injury 34:55–62View ArticleGoogle Scholar
- Stoffel K, Stachowiak G, Markus K (2004) Open wedge high tibial osteotomy: biomechanical investigation of the modified Arthrex Osteotomy Plate (Puddu Plate) and the TomoFix Plate. Clin Biomech 19:944–950View ArticleGoogle Scholar
- Taylor WR, Heller MO, Bergmann G, Duda GN (2004) Tibio-femoral loading during human gait and stair climbing. J Orthop Res 22:625–632PubMedView ArticleGoogle Scholar
- Valkering KP, Van den Bekerom MPJ, Kappelhoff FM, Albers GHR (2009) Complications after tomofix medial opening wedge high tibial osteotomy. J Knee Surg 22(3):218–225PubMedView ArticleGoogle Scholar
- Watanabe K, Kamiya T, Suzuki D, Otsubo H, Teramoto A, Suzuki T, Yamashita T (2014) Biomechanical stability of open-wedge high tibial osteotomy: comparison of two locking plates. Open J Orthoped 4:257–262View ArticleGoogle Scholar
- Woon-Hwa J, Chung-Woo C, Ji-Hoon L, Ha J-H, Ji-Hyae K, Jae-Heon J (2013) Comparative Study of Medial Opening-Wedge High Tibial Osteotomy Using 2 Different Implants. Arthroscopy: J Arthroscopic Related Surgery 29(6):1063–1071View ArticleGoogle Scholar
- Zhim F, Laflamme GY, Viens H, Saidane K, Yahia L (2005) Biomechanical stability of high tibial opening wedge osteotomy: Internal fixation versus external fixation. Clinical Biomechanics 20:871–876PubMedView ArticleGoogle Scholar
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