Medial openwedgehightibialosteotomy (MOWHTO) is an effective surgical procedure for the treatment of medial compartment osteoarthritis of the knee as well as for the correction of lower extremity malalignment [1–3]. With fa- vorable clinical outcomes and improved surgical tech- niques, MOWHTO has become increasingly popular [4–6]. Although numerous advantages of MOWHTO have been addressed, it has been reported that MOWHTO would ad- versely affect the patellofemoral joint. Several studies state that MOWHTO leads to patella baja, subsequently causing increased patellofemoral contact pressure [7–9]. Varus- valgus alignment was also reported to affect the progression of patellofemoral osteoarthritis in a compartment-specific manner . Recently, several studies investigating the ef- fect of MOWHTO on the patellofemoral joint using an arthroscopic assessment also reported overall deterioration of the articular cartilage of the patellofemoral joint over time as a result of MOWHTO [11–14].
Unicompartmental osteoarthritis with varus deformity constitutes a great chal- lenge for orthopedic surgeons. The resultant limb malalignment allows more load to be distributed over the medial compartment. Many authors considered hightibialosteotomy as temporary surgery particularly in active patients who are not candidates for salvage arthroplasty . Coventry (1965)  modified the procedures by making the osteotomy proximal to tibial tubercle so that the cancellous bone could heal rapidly, and early weight-bearing could be ensured. In recent years, a lot of articles concerned with openwedgehightibialosteotomy OWHTO have been published. However, optimization of surgical procedure is still a controversial issue. In a study involving 93 patients treated with medial OWHTO; the authors concluded that this technique was a suitable procedure for medial compartment gonarthrosis provided precise correction of malalignment achieved with the biologic healing of the osteotomy. None of the patients had symptoms of progression of the disease after 10 years . The technique avoids several shortcomings associated with lateral closing wedge and dome osteoto- mies, including severence of tibiofibular joint, peroneal nerve injury, limb shortening, patella infera, and bone loss . Nakamura et al. ,  compared 28 closing wedge osteotomies versus 40 dome osteotomies, with average varus alignment for each was 5.67˚ and 1.45˚, respectively recorded subjective satisfac- tion scores where 42.9% patients were unhappy with the closing wedge osteoto- my compared with 57.5% with the dome osteotomy With the advent of biplanar technique in OWHTO Certain issues concerned including enhancement of os- teotomy healing, sagittal inclination of tibial plateau, preservation of patellar height together with secondary alteration of the normal knee kinematics   Particular concern in our present study directed toward the tibial plateau sagital inclination (posterior tibial slope PTS) which was maintained unchanged in 40 cases (83.3%) while it increased in 8 cases (16.7%) by less than 5˚ and this was due to technical issue. To adequately maintain the posterior tibial slope, the opening ratio of the anterior to posterior gap should be 1 to 2. Change of tibial slope would reduce translational forces and improve antero-posterior knee sta- bility . In a previous study by Hee-S. et al. , they concluded that PTSA changes of <5˚ were not clinically significant. Many biomechanical studies showed that increasing posterior slope aids in decreasing stress on the posterior cruciate ligament while decreasing the posterior slope decreases stress on the anterior cruciate ligament . Also; patello-femoral arthritis is not a contrain- dication to HTO if modification of the technique done through coronal tibial correction combined with tibial tuberosity anteriorisation .
Medial openwedgehightibialosteotomy (OWHTO) was first described by Debeyre and Artigou in 1951 . More recently in 1987, Hernigou et al. reported their find- ings from a long-term follow-up of spontaneous osteone- crosis of the knee (SONK) patients who had undergone OWHTO . There are different methodologies and implants that can be used in OWHTO and Koshino et al. have described the use of hydroxyapatite wedges in the osteotomy gap . The principal advantages of OWHTO include maintenance of the bone stock, correction of the deformity close to its origin, and no requirement for a fib- ular osteotomy [6,9]. We have reported previously that with an early and active rehabilitation program, OA patients can walk with full weight bearing at two weeks after their OWHTO procedure [10,11]. The surgical pro- cedures used for our patient cohort were performed using TomoFix™ as the implant (Synthes Inc., Bettlach, Switzer- land), in combination with artificial bone or bone substi- tute, in the osteotomy gap. We have found that an optimal postoperative rehabilitation program following OWHTO in elderly cases enables these patients to walk without any support and with a full weight bearing load more quickly after their procedures.
Introduction: Recently, new plates with locking screws have been developed and used for medial open-wedgehightibialosteotomy (HTO). The purpose of this study was to evaluate and compare biomechanical properties of different internal fixations in open-wedge HTO using the two cur- rently available locking plates. Methods: Eight paired fresh-frozen cadaveric lower extremities were vertically embedded in steel boxes. The axial compression load was applied to the legs using the mechanical testing machine. The axial compression load test from 0 N to 550 N and the failure test were performed before and after HTO. One side of the leg of a specimen was fixed with the Puddu locking plate and the other side was fixed with the TomoFix plate to compare the two plates using the same specimen. A mode of failure and vertical displacement of the medial and lateral parts of the tibia at the osteotomy gap was recorded using a video camera in the failure test. The load–displacement data were analyzed to calculate stiffness, failure load, and displacement at failure. Results: The mean failure load was 1471.4 N and 1692.3 N and total vertical displacement at failure was 3.1 mm and 2.9 mm with the Puddu and TomoFix plates, respectively. During axial compression loading, displacements mainly occurred at the lateral osteotomy gap, while the me- dial gap was well preserved. No significant differences were observed in the failure load, dis- placement, or mode of failure between the two plates. Conclusions: The Puddu and TomoFix plates had similar biomechanical properties in open-wedge HTO. The results indicated reliable stability after open-wedge HTO without fibular osteotomy.
Openwedgehightibialosteotomy (openwedge HTO) is a widely used treatment option for patients with medial compartment osteoarthritis and varus malalignment. In the past, several studies have described a significant clin- ical and radiological improvement by using this estab- lished method [1, 2]. In most of the presented studies, well-known clinical scores, such as the KOOS (Knee In- jury and Osteoarthritis Outcome Score), the International Knee Documentation Score (IKDC) or the Oxford Knee Score were used to describe the postoperative outcome [3–5]. Health-related quality of life (HRQL) became a popular tool to measure the clinical outcome after opera- tive procedures in the field of orthopedic surgery as well [6–8]. In patients with full thickness rotator cuff tears, it could actually be demonstrated that the mental health of HRQL has a stronger association with patient-reported shoulder pain and function than tear size . The SF-36 Questionnaire is an established and widely used tool for describing HRQL in various medical fields [10, 11]. In pa- tients suffering from osteoarthritis of the knee joint, HRQL is significantly reduced, especially due to pain on the basis of cartilage damage .
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 iBa- lance 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 con- structs with a higher mechanical strength have higher bone healing rates with an equal amount of intraoperative safe- ness than the TomoFix plate, the current golden standard.
is an important predictor of osteoarthritis progression. Although the mechanisms by which increased mechan- ical loading adversely affects cartilage are unclear, they may involve chondrocyte death, disruption of the extra- cellular matrix, and microfracture within the subchon- dral cortical endplate. Knee adduction moment is a surrogate measure of dynamic mechanical load on the knee joint and increases in proportion to knee varus deformity. The success of medial openwedge HTO depends not only on alignment correction but also on decreasing the adduction moment, thereby reducing the mechanical load on the medial compartment of the knee. Determining the magnitude of adduction moment loss and its clinical relevance after medial openwedge HTO is therefore important. This meta-analysis showed that medial openwedge HTO reduced preoperative adduction moment by about 40%. One recent study reported that a 1% increase in adduction moment in- creased the risk of progression of knee osteoarthritis 6-fold. These findings suggest that a 40% reduction in adduction moment would delay the progression of med- ial osteoarthritis. Another recent study found that the load on the medial compartment while walking increases 5% for every 1° change towards varus . Our study found that the magnitude of alignment correction was not significantly related to the reduction in adduction moment. Nevertheless, because the mean amount of correction following medial openwedge HTO in the studies included in this meta-analysis was approximately 8°, the 40% reduction in adduction moment compared with the preoperative level may be explained by the
Over-correction of coronal valgus alignment was important to obtain satisfactory result after HTO [3,13]. Hernigou et al reported that the best results were obtained in 20 cases of open-wedge HTO that had mechanical hip-knee-ankle angle of 183° to 186° . There was no pain and no progression of the arthrosis in either the medial or the lateral tibiofemoral compart- ment. Aglietti et al reported the results of 91 closing- wedge HTO . An anatomical valgus alignment at consolidation between 8° and 15° was significantly corre- lated with the best result. In the current study, the for- mer recommendation was followed because it was more stringent and open-wedge HTO was performed. In this way, the Knee Society knee score was also modified because the target range in HTO was different from that in TKA. The mechanical coronal alignment was sig- nificantly corrected from varus 10.5° to valgus 4.4°. At consolidation of bone graft, it was maintained at valgus 3.9°. The varus recurrence was minimal and not signifi- cant. Six out of nine knees could achieve the target alignment. One knee had varus 1° and the patient had minimal knee pain and his knee score was 86 at 24 month follow-up. Two knees had valgus 7° and the patients had no knee pain. One of their knee scores was 98 at 36 month follow-up and the other was 87 at 27 month follow-up. In order to achieve the target align- ment, a few points were important, including accurate preoperative planning, careful prevention of lateral tibial translation on opening up the osteotomy and measure- ment of bone graft size, harvesting graft larger than measured size to allow down-trimming and rigid inter- nal fixation.
Openwedge (OW) hightibialosteotomy (HTO) is an ef- fective surgical treatment for patients with medial compart- mental osteoarthritis combined with varus alignment [1–4]. The correction of the varus alignment by OW HTO pro- vides change of the load distribution in the knee joint and improved functionality in patients with medial compart- ment osteoarthritic knees [5, 6]. Additionally, reduced load on the medial compartment due to lateral shift of the axial load has been shown to lead to biological regeneration of the articular cartilage after OW HTO [7–9]. However, lat- eral and patellofemoral compartments could be affected and changes of the cartilage status of these compartments are also questionable.
cruciate ligament (PCL) insertion to the medial one- third of the tibial tuberosity using SolidWorks 2014 (Dassault Systemes, Waltham, Massachusetts, USA) (Fig. 3). Morphologic analysis of the proximal tibia was performed using the following parameters (Y.O.S. and K.J.W., experience of more than 5 years): (1) radii in axial plane, 2) radii in coronal plane, and 3) angle and horizontal distance (Distance X) between the proximal and distal fragments. The parameters were measured at 3 borders because the contours were underwent changes in the proximal fragment (head), gap (neck), and distal fragment (shaft). The radii in the axial plane were mea- sured at the head and neck positions. The measurements of the radii showed that the radii increased with the increase in the flatness of the surface and the radii decreased with the increase in the surface curvature. The radii of the head in axial plane were measured at 3 positions (Head_Top: top of the implant head part, Head_Mid: middle of the implant head part, and Head_- Bot: bottom of the implant head part) and those of the radii of the neck, at 2 positions (Neck_Top: top of the
Using an experimental setup, three-dimensional patient- specific cutting guides were reported to be more accurate than free-hand technique to perform an osteotomy cut and drill in a synthetic bone . The use of patient-spe- cific cutting guides for OWHTO was also reported recently in three studies realized on small series of patients [25, 26, 28]. All three clinical studies reported good accuracy and reliability of the procedure. Planning procedures for OWHTO were carried out either on 2D long-leg radiographs  or from a 3D model [25, 26]. Pérez-Mañanes et al. used CT images to obtain the 3D tib- ial surface and to position two K-wires to lead the cut, and the correction was planned using two additional wedges.
Compared to other biomechanical studies (Agnes- kirchner et al., 2006; Diffo Kaze et al., 2015; Maas et al., 2013; Spahn & Wittig, 2002; Stoffel et al., 2004; Wata- nabe et al., 2014; Han et al., 2014) that reported fracture of the lateral cortex, the finding (5) of the present study indicates that the lateral cortex is the weakest point of the openwedge HTO. Beside smokers, patients with a fracture of the lateral cortex after HTO exhibit delayed union (Schröter et al., 2015; Takeuchi et al., 2012). This highlights the importance of using an implant that will avoid fracture of the cortical lateral hinge prior to the beginning of gap healing, which takes approximately 3 to 8 weeks (Marsell & Einhorn, 2011). In the cyclic load- ing fatigue test, the highest strength, i.e. the highest number of cycles prior to failure of the lateral cortex, was found in the Contour Lock group followed by the Activmotion group (Fig. 9). Considering the fact that a healthy active person performs 1 million loading cycles
Hightibialosteotomy (HTO) is a well-estab- lished treatment option for uni-compartmental osteoarthritis associated with coronal deformi- ty of the lower limb . Clinical indications for an HTO include varus alignment of the knee associated with medial compartment arthritis, knee instability, medial compartment overload following meniscectomy, and osteochondral lesions requiring resurfacing procedures . Many techniques have been described for HTO. The goal of the procedure is to realign the lower extremity and redistribute the joint forces applied to each compartment of the knee, thereby decreasing pain and improving overall function [1, 2]. The technique used for proximal tibia osteotomy has typically been the lateral
durability, the risk of metal allergies and patient dissatis- faction with joint range of motion (ROM), especially in young, physically active patients [8 – 10]. Moreover, con- cerns have been raised regarding complications such as deep or superficial implant-associated infections, wear of the prosthesis, and vein thromboembolism [11 – 13]. Therefore, osteotomy procedures have been recom- mended for young and physically active patients wanting to maintain wide ROM, or for individuals who participate in high-demand activities and want to avoid prosthetic arthroplasty [14, 15]. Open-wedgehightibialosteotomy (HTO), the most common osteotomy procedure for treat- ing knee OA [15, 16], is based on the concept of realign- ment to redistribute weight-bearing and mechanical stress laterally to areas with less destruction, thus relieving pain and improving function . As tibiofibular joint disrup- tion and peroneal nerve injury are potential complications associated with lateral closed-wedge HTO, the medial- approach open-wedge HTO, which avoids such
Kim et al., using an SPET/TC evaluation, have shown that an increased signal activity around the patellofe- moral joint was present after an OWHTO even when a low decrease of postoperative Blackburne-Peel ratio was found (Kim et al. 2016). Kim et al. reported that 21.9% of the patients developed patellar OA and 41.2% devel- oped a trochlear OA after OWHTO. Their findings were based on a second look arthroscopy made at 21 to 32 months of follow-up (Il et al. 2017). The prominent find- ing was that no correlation of this evolution with patellar height was found. The conclusion could be that even when the patellar height has not been changed, alter- ations in patellofemoral pressure forces happen after a OWHTO. That is also supported by a recent cadaveric biomechanical study (Kloos et al. 2018). In any case we must take into account that always a large deformity correction in medial open-wedgehightibialosteotomy may cause a degeneration of patellofemoral cartilage. (Otakara et al. 2019) in the present study an arthro- scopic second look wasn’t provide, but Kim in his study showed as well that 11.4% of the cases had postoperative anterior knee pain and among them all showed pro- gressed OA on second look arthroscopy. Postoperative anterior knee pain was related to the ICRS grade of the patellofemoral joint at the time of second-look arthros- copy. In our study no patients complained about patello- femoral pain at the last follow up, neither the patients who reported patello-femoral discomfort before surgery. Finally, in their OWHTO series, Lee et al. have shown postoperative statistically significant changes in lateral patellar tilt (Lee et al. 2016). Even if they reported that this data has no clinical impact at 2 years follow-up, this mechanical alteration could as well explain patellofe- moral cartilage subclinical alteration and patellofemoral pain at a longer term follow up. In the present study no significant alterations in postoperative lateral patellar tilt was detected at minimum 24 months follow up.
Obviously, the capacity for maintaining bony stability in the presence of (multiple) cortex fissures can vary sig- nificantly among patients and bone stability does not allow an “all-or-nothing principle”. Nevertheless, the data of the present study indicate that a correctly placed hinge pin at the end of the horizontal and ascending tib- ial osteotomy does not prevent opposite cortex fracture in larger corrections. The data suggest that bone ductil- ity is an important factor for the crack initiation and hence integrity of opposite cortex, especially for higher corrections.
Although several meta-analyses [14, 19, 20] were performed earlier, most evaluated only postoperative outcomes. A preoperative comparative analysis is also quite important, which could make results more persua- sive and accurate. The posterior tibial slope (PTS) was measured by two different methods (measuring line: posterior tibial cortex or tibial mechanical axis) in some studies comparing OWHTO and CWHTO [16, 18, 21 – 24], but some meta-analyses [14, 19, 20] pooled the results of different methods together, which may be not completely accurate. Additionally, numerous recently published studies [23–27] have longer follow-up times or present different directions for evaluating the effects of these two surgical methods. Therefore, regarding the current dilemma, the purpose of this meta-analysis is to examine changes in radiological variables and clinical outcomes between OWHTO and CWHTO which have ongoing controversial issues in numerous quantitative clinical studies and to assist surgeons in determining the appropriate method according to the patient condition. This study hypothesizes that OWHTO is better than CWHTO in clinical outcomes, that there are no differ- ences in the function of correction between OWHTO and CWHTO, that posterior tibial slope increases after OWHTO and decreases after CWHTO, and that patellar height decreases after OWHTO and increases after CWHTO.
The results showed that posterior slope increases after open-wedge HTO and decreas- es after closed-wedge HTO. The unique ana- tomic geometry of the proximal tibia may cause the change of posterior tibial slope following HTO [36, 45, 46]. Increased tibial slope follow- ing OWO can produce an anterior translation in tibial resting position and increase the strain in the anterior cruciate ligament (ACL) [47, 48], while decreased slope following CWO can increase the strain in the posterior cruciate lig- ament (PCL) . Thus, some studies reported that CWO was a therapeutic option for those with concomitant ACL injuries or insufficiency, while OWO was an appropriate method for those with PCL deficiency [46, 47, 50]. However, the study Nha et al. found that the change in posterior tibial slope was less than 5° (approximately 2°), indicating that both open- and closed-wedge HTO may have little effect on the in situ forces in the cruciate ligaments . Three reference methods (Caton-Deschamps, Insall-Salvati or Blackburne-Peel index) were used to evaluate patellar height in these eligi- ble studies. The findings demonstrated that patellar height decreased after OWO and
Results: There were no limitations in range of motion found in any cases. Three patients showed progressive osteoarthritis on the medial compartment. The mechanical femorotibial angle was significantly corrected from varus 7.0 degrees to valgus 1.2 degrees, and the tibial posterior slope was not significantly changed. The Lysholm and Tegner activity scores were significantly improved after surgery (from 58 to 94 points on the Lysholm scale and from 4.0 to 5.3 points on the Tegner activity scale). Although the Lachman test and the pivot-shift test showed significant improvements after surgery, instability greater than Gr II was observed in three patients on the Lachman test and in four patients on the pivot-shift test. The side-to-side difference improved from 9.6 mm to 4.2 mm postoperatively as assessed using a Telos® arthrometer. There were no cases of nonunion or fixation loss. Conclusions: Simultaneous open-wedge HTO and ACL reconstruction in patients with ACL injury with medial compartmental OA showed satisfactory functional outcomes and postoperative activity level scores. However, some patients showed residual instability and progression of OA.