Medial Open-wedge Tibial Osteotomy Research Articles

High tibial lateral closing wedge and opening wedge valgus osteotomy produce different effects on posterior tibial slope and patellar height.

To compare the clinical outcomes of performing a closed tibial high osteotomy with an open osteotomy and the changes in posterior tibia slope and patellar height. Methods were collected from three hundred and forty patients (440 knees) with high tibial osteotomy performed from January 2019 to January 2020. Forty patients (50 knees) had a lateral closed wedge tibial osteotomy (LCWHTO), and 300 patients (390 knees) had a medial open wedge tibial osteotomy (MOWHTO). The follow-up periods were 20.5 months and 19.9 months, respectively. At the final follow-up visit, both groups evaluated the Lysholm score and joint range of motion (ROM). Changes in preoperative and postoperative mechanical axis deviation (MAD), proximal medial tibial angle (MPTA), posterior tibial slope (PTS), and M-K index were compared between the two groups of patients. Lysholm scores were 79.6 ± 15.6 preoperatively and 96.0 ± 5.0 postoperatively in the LCWHTO group (p < 0.01); 83.7 ± 16.0 preoperatively and 94.3 ± 9.1 postoperatively in the MOWHTO group (p < 0.01). ROM was 136.0° ± 8.4° preoperatively and 133.2° ± 10.1° postoperatively in the LCWHTO group (p > 0.05); 136.5° ± 8.4° preoperatively and 135.7° ± 9.3° postoperatively in the MOWHTO group (p > 0.05). the MAD was (26.5 ± 4.1) mm preoperatively and 0.3 ± 2.9 mm postoperatively in the LCWHTO group (p < 0.01); 21.8 ± 6.5 mm preoperatively and -0.3 ± 2.6 mm postoperatively in the MOWHTO group (p < 0.01). The MPTA in the LCWHTO group was 75.3° ± 3.2° preoperatively and 89.5° ± 2.4° postoperatively (p < 0.01). 77.1° ± 3.0° preoperatively and 90.6° ± 2.7° postoperatively in the MOWHTO group (p < 0.01). M-K index was 0.78 ± 0.08 preoperatively and 0.79 ± 0.07 postoperatively in the LCWHTO group (p > 0.05). 0.78 ± 0.05 before and 0.75 ± 0.05 after surgery in the MOWHTO. 10.8° ± 3.0° PTS before and 8.1° ± 3.4° after surgery in the LCWHTO group (p < 0.05); 10.2° ± 3.1° preoperatively and 10.9° ± 4.0° postoperatively (p > 0.05). LCWHTO decreases the PTS and has no effect on patellar height; MOWHTO does not affect the PTS but decreases patellar height. The patient should individualize the choice of the osteotomy.

The benefits of a percutaneous supplemental screw to reinforce the hinge of a medial open wedge tibial osteotomy.

Our earlier studies reported that an additional lag screw placed from the opposite side increases the stability of the fixation construct in medial open wedge high tibia osteotomy (MOWHTO). The aim of the study was to evaluate the clinical relevance of the use of a supplemental screw with immediate post-operative full weight-bearing and its benefits in terms of functional outcome, radiographic outcome and complications. A retrospective study was performed comparing the historical cohort (MOWHTO without opposite screw) (group A) with the current cohort (MOWHTO with opposite screw) (group B). The patients underwent clinical and radiological assessments. We evaluated the WOMAC (The Western Ontario and McMaster Universities) score, IKDC (International Knee Documentation Committee) scores, and Lysholm knee score. Patients' return to sports and work were also recorded. We included 123 knees receiving MOWHTO alone (group A) with 114 knees (group B) receiving MOWHTO with an opposite screw. A shorter bone union time (18.3 ± 2.1weeks v.s. 11.5 ± 2.6weeks, p < 0.001), earlier return to sports (6.1months vs. 4.6months, p < 0.001) and return to works (3.2months vs. 2.3months, p < 0.001) and better 6-month functional outcomes were found in group B (p < 0.001). The complications were similar in both groups. One patient experienced irritation at the site of the screw entrance and the screw was removed after union. The current study evaluated the clinical efficacy of a supplemental lag screw placed from the opposite side in MOWHTO. Comparing to the plate alone, the additional opposite screw improved the implant and fixation stability under immediate weight-bearing without causing complications. A shorter time for returning to sports and work was noted, and a better functional outcome at 6-month follow-up was registered.

Osteotomy close to the knee joint in adults

Osteotomy close to the knee joint in cases of axial deformities or in the context of corrective interventions is still an elementary component of the spectrum of orthopedic surgery. The precise localization and analysis of the pathology are crucial in order to restore approximate physiological loading conditions by means of asuitable osteotomy procedure. Thus, above all, the medial open-wedge tibial osteotomy has become established as astandard procedure for the treatment of knee osteoarthritis caused by extra-articular tibial varus deformity. Furthermore, corrective osteotomy of the sagittal axis of the tibia and of the distal femur also show good long-term results when the indications are correctly interpreted. The osteotomies described in this article are corrections that should be performed after careful consideration of the biological and mechanical aspects. Correct planning, attention to risk factors and the surgical technique are the main factors that determine the long-term success of the procedure.

Combined posterior cruciate ligament and chronic posterolateral corner deficiency in varus knee, two-stage reconstruction

Background Conservative management of chronic posterolateral corner (PLC) knee injuries had a bad repetition and often followed by poor outcomes. In patients who had associated posterior cruciate ligament [PCL] and chronic PLC knee injuries with varus knee deformity, failure to correct the mechanical axis by correcting varus was usually followed by failure of the posterolateral knee repair or reconstruction. Aim of the study To assess prospectively the results of treatment of associated PCL and chronic PLC injury in the varus knee, with a two-stage procedure. Initial high tibial medial opening wedge osteotomy was followed by PCL reconstruction. Methods This study included 10 patients who had associated PCL and chronic PLC deficiency in varus knee who were treated by two-stage surgical technique, first stage was high tibial medial opening wedge osteotomy to align the mechanical axis and correct varus deformity, then PCL ligament reconstruction in the second stage. Results According to the International Knee Documentation Committee, the 10 patients included in the study [100%] were graded as grade C (abnormal) or D (sever abnormal) preoperatively, while 8 of the 10 patients [80%] were graded as grade A (normal) or B (nearly normal), and 2 patients [20%] were rated as abnormal grade C at final follow-up scoring. Statistically significant improvement was achieved. Radiologically, the average mechanical axis that preoperatively passed within the medial tibial plateau with varus deformity ranged between 10 and 15° in our cases, while the mechanical axis postoperatively passed through the mid of tibial plateau or slightly within the lateral tibial plateau with full correction of the deformity with valgus angle ranged from 5 to 10°. The preoperative posterior tibial sagittal slope angle was average 7.8°, which became 10.5° in the last follow-up visit. Conclusion Two-stage reconstruction of the knee in cases who had PLC injuries associated with varus knee, starting by proximal tibial medial opening wedge osteotomy followed by reconstruction of PCL, is a valuable technique and had good results.

Patella height following biplanar medial open-wedge high tibial osteotomy and its relevance for Clinical Outcome

Aims and Objectives:The medial medial open-wedge tibial osteotomy (OW HTO) has become increasingly important in the treatment of cartilage damage in the medial compartment with accompanying varus deformity in recent years. The technique of the biplanar, proximally initiated OW-HTO leads to a reduction of the patellar height. Relationships with functional outcome, and thus the clinical relevance of this observation, has not been investigated adequately so far. The aim of this study was to evaluate the influence of altered patellofemoral geometry on the functional outcome after OW HTO.Materials and Methods:In 205 patients (age 44.46 ± 10.43 years MW) with cartilage damage in the medial compartment and existing varus deformity biplanar, proximally directed OW HTO (TomoFix, Synthes, Solothurn, Switzerland) was perfermed between January 2005 and December 2013. Insall-Salvati index and Caton-Deschamps index were determined rom pre- and postoperative lateral radiographs of these patients. The evaluation of the patients was performed using standardized measuring instruments (preoperatively: visual analogue scale (VAS) and Lysholm score after surgery: VAS, Lysholm, KOOS and KOOS4). In the event of a radiological patella baja (Insall-Salvati index> 1.2; Caton-Dechamp less then 0,6 correlation of patellar height and the functional scores was performed using SPSS 21.0 (IBM Corp., Armonk, United States). A p-value of 0.05 was considered statistically significant.Results:At an average follow-up of 68.65 (SD ± 30.26) months, a defect size of 4.32 MW (SD ± 3.01) cm2, a varus deformity of MW 6.04 (SD ± 2.83) ° and postoperative leg axis of MW 2.26 ± 1.74 ° valgus data analysis resulted in significant postoperative changes in the patellar indices (Insall-Salvati index preoperatively 0.94 ± 0.17 vs. 0.91 ± 0.20 postoperatively; Caton- Dechamp index preoperatively 1.03 ± 0.1,69 vs. 0.89 ± 0.17 postoperatively, p = 0.00). The carried out correlation analysis revealed significant correlations for KOOS symptoms and KOOS4 (p = 0.034 and 0.01).Conclusion:The proximally directed biplanar medial open-wedge osteotomy leads to significant changes in the patellofemoral joint section in the sense of patella baja. These kinematic changes correlate with poorer postoperative functional results, so that in patients with preexisting pathological patellar height a modification of the classical osteotomy technique such as a to leave the tibial tuberosity attached tot he proximal tibia should be discussed.

Total Ankle Replacement with a Staged Correction of a 20 Degree Post Traumatic Ankle Valgus and Medial Ankle Instability

Total ankle replacement can be a challenging surgery especially when pre-operative deformity exists. Most authors advocate the indication for total ankle replacement should be narrowed to patients with less than 10 to 15 degrees of pre-operative varus or valgus. When greater than 10-15 degrees of coronal plane malalignment is found, ancillary procedures must be performed. We report a case of a 56 year old male with 20 degrees of pre-operative ankle valgus after a pronation-external rotation injury that was malreduced at an outside institution. In addition to the valgus, the patient presented with medial ankle instability, distal lateral tibial osteonecrosis and a shortened, posteriorly rotated fibula. Staged procedures were employed to successfully realign the patient’s ankle joint. The patient was first brought to the operating room and stressed under c-arm fluoroscopy. He was found to have instability of the deltoid complex. He subsequently underwent an ankle arthrotomy, synevectomy and deltoid imbrication to re-establish medial ankle stability. Second, the patient underwent a fibular lengthening and derotation, syndesmotic fusion and medial opening wedge tibial osteotomy. Once consolidation was confirmed by CAT scan, the patient had a gastrocnemius lengthening total ankle arthroplasty with a Zimmer trabecular metal implant (Zimmer Inc®, Warsaw, IN) and debridement and grafting of the distal lateral tibial osteonecrosis. The patient is now greater than 24 months post operatively and able to ambulate pain free without assistive devices.

Resultados clínicos de la osteotomía tibial valguizante de cuña abierta y cerrada para el manejo de deformidad en genu varo y gonartrosis mecánica femorotibial medial

BackgroundThere is a huge controversy regarding proximal tibial osteotomies outcomes when treating genu varum deformities and medial tibiofemoral compartment arthrosis. The aim of this study was to determine the clinical outcomes of the open and closed wedge tibial valgus osteotomy in patients with genu varus deformity and mechanical medial tibiofemoral osteoarthritis, according to Lysholm and Tegner scales. Material and methodsA descriptive, case series study was conducted on 24 patients with varus deformity of the knee and unicompartmental mechanical arthrosis of the medial tibiofemoral compartment of the knee from January 2006 to January 2011. A medial open wedge tibial osteotomy was performed in patients with medial collateral ligament laxity, while a closed wedge osteotomy was performed in those patients with strained medial collateral ligament, as observed by the valgus stress maneuvers performed during the preoperative evaluation. ResultsExcellent results were obtained in 91.7% of subjects, and 8.3% were good according to the Lysholm scale, with a mean score on the Tegner scale of 4.4%. DiscussionThe tibial valgus osteotomy offers good and excellent clinical outcomes in patients with mechanical medial tibiofemoral osteoarthritis and varus knee deformity.

Gradual correction of idiopathic genu varum deformity using the Ilizarov technique

Proximal tibial osteotomy is an effective treatment option for genu varum deformity among the many other described techniques. The purpose of this study is to evaluate the clinical and radiological outcomes and the complications in gradual correction of idiopathic genu varum deformity using Ilizarov frame. Proximal tibial medial opening wedge osteotomy was performed in 21 lower limbs of 11 patients, with whom the Ilizarov external fixator was used for gradual correction of the varus deformity. The mean age of the patients was 24.8 years (SD, 5.3). Deformity measurements of conventional mechanical axis deviation, mechanical medial proximal tibial angle, mechanical lateral distal femoral angle, posterior proximal tibial angle, joint conversion angle, tibio-femoral angle and tibial slope were compared. The mean time for removal of the Ilizarov fixator was 24.7 weeks. At the last follow-up, the mean of Hospital for Special Surgery knee score increased, and the mean mechanical medial proximal tibial angle, tibio-femoral angle and conventional mechanical axis deviation improved. The differences between preoperative and postoperative posterior proximal tibial angle, mechanical lateral distal femoral angle, joint conversion angle and tibial slope were not significant. Ten complications were observed, of which 8 were minor complications and 2 were minor complications. With a few complications, normal alignment and orientation of lower extremity can be established in patients with idiopathic genu varum deformity through gradual correction using a Ilizarov fixator. Retrospective case series, Level IV.

Failure of knee osteotomy in a case of neuropathic arthropathy of the knee

Neuropathic arthropathy (Charcot’s joint) is a degenerative process that affects peripheral or vertebral joints as a consequence of a disturbance in proprioception and pain perception. The knee is one of the most frequently affected joints, but even when the diagnosis is made at an early stage there is no consensus on the best treatment options. An early diagnosis of neurosyphilis was made in a 55-year-old woman presenting a delayed union of an asymptomatic Schatzker type IV fracture of the proximal tibia. A medial opening wedge tibial osteotomy was performed to achieve fracture healing, to correct the medial depression of the articular surface, and possibly to avoid an early arthritis typical of the disease. To our knowledge, a knee osteotomy has never been reported at an early stage of neuropathic arthropathy. Even though the clinical and radiographic evaluation performed at 4 months follow-up showed a good stage of healing of the osteotomy and no typical features of neuropathic joint degeneration, at 8 months follow-up the knee was markedly deranged.

High, open wedge tibial osteotomy: Finite element analysis of five internal fixation modalities

Medial open wedge tibial osteotomy is one of the most widely accepted method of treatment for varus knee deformity in younger patient population. Its success depends on the quality of fixation and preservation of the outer cortex of the tibia. The aim of the study was to evaluate stress distribution in five numerically designed plate configurations which can be used in open wedge tibial osteotomy. The paper describes the 3D numerical model of the tibia with 10 degrees varus deformity correction obtained by an optical scanner ATOS. The simulation anticipated axial compressive loads of 700 N, 1 400 N and 2 100 N. We used a modification of the standard T-plate in all of the five tested models. Modalities were tested with and without a metal block, and with and without a stable angle fixation plates and screws. Software PAK was used in the analysis of stress distribution. With exception for the standard T-plate configuration without the supporting block, the loads up to 1400 N did not result in critical stresses on the outer cortex of the tibia in the remaining four models. There is an objective risk of possible failure of the outer cortex and loss of correction at a load of 2100 N in all configurations. The plate model with the angle stable fixation and the supporting metal block showed the most optimal distribution of stresses on the plate-bone composite compared to other models. The standard T-plate configuration without supporting metal block is not sufficient to stabilize the open wedge osteotomy of the tibia. Numerical models of the angle stable T-plate and the supporting metal block achieved a favorable distribution of stresses on the bone and implant which require further biomechanical testing.

Total knee arthroplasty following medial opening wedge tibial osteotomy: Technical issues early clinical radiological results

Medial opening wedge high tibial osteotomy is a popular treatment option for medial compartment osteoarthritis of the knee. One of the proposed advantages is easier conversion to a total knee replacement compared to lateral closing wedge osteotomies, although there are few studies to support this. We reviewed the technical considerations in 36 knees in which conversion of a medial opening wedge osteotomy to total knee arthroplasty was performed, and contrasted these to previously reported studies of knee arthroplasty after closing lateral wedge or dome osteotomies. The clinical results in 33 patients (34 knees) with minimum 2 year follow-up (mean 3.4 years, range 2 to 8 years) were compared to a control group of 1315 knee arthroplasties performed without prior tibial osteotomy. Total knee arthroplasty after a medial opening wedge osteotomy is relatively straightforward, although we encountered patella baja in 27% of cases, and an increased posterior tibial slope of over 15° in 21%. There was a lower Knee Society score and a lower pain score (more pain) in the study group compared to the control group. While technically straightforward in most cases, knee arthroplasty following medial opening wedge osteotomy in this study group yielded inferior clinical results compared to a group of knee arthroplasties performed without prior tibial osteotomy.

Measurement of tibial slope angle after medial opening wedge high tibial osteotomy: case series.

In the past, changes in tibial slope were not considered when planning or evaluating osteotomies, and success in high tibial osteotomy was related to the alignment and amount of femorotibial angular correction. The aim here was to measure changes in tibial slope after medial opening wedge tibial osteotomy and investigate the effect of tibial slope angle on the clinical results. Retrospective review study on a series of cases, at the Department of Orthopedics and Traumatology, Faculdade de Medicina de Marília (Famema), Marília, Brazil. Twenty-eight patients were studied, and a total of thirty-one knees. Lateral roentgenograms of the tibia were used pre and postoperatively to measure the tibial slope based on the proximal tibial anatomical axis. The clinical results were measured using the Lysholm knee score. There was an average increase in tibial slope angle after surgery of 2.38 degrees (95% confidence interval: +/- 0.73 degrees ). There was no correlation (r = -0.28) between the postoperative Lysholm knee score and the difference in tibial slope angle from before to after surgery (P = 0.13). Medial opening wedge tibial osteotomy led to a small increase in tibial slope. No significant correlation was found between increased tibial slope and short-term clinical results after high tibial osteotomy. Other clinical studies are needed in order to establish whether extension or flexion osteotomy could benefit patients with medial compartment gonarthrosis.

The Effect of a Proximal Tibial Medial Opening Wedge Osteotomy on Posterolateral Knee Instability

Background Increased stability of posterolateral corner knee injuries has been observed clinically after proximal tibial medial opening wedge osteotomies. Hypothesis Static varus and external rotatory stability will be significantly improved in a knee with a grade 3 posterolateral knee injury after a proximal tibial medial opening wedge osteotomy. Study Design Controlled laboratory study. Methods Biomechanical testing of 10 nonpaired, cadaveric knees was performed in the intact state, after transection of the posterolateral corner (fibular collateral ligament, popliteus tendon, and popliteofibular ligament), and after a 10-mm proximal tibial medial opening wedge osteotomy. Loading conditions consisted of 12 N.m varus moments and 6 N.m external rotation torques. Six degrees of freedom motion analysis was used to assess motion changes, and a buckle transducer was used to measure the force on the superficial medial collateral ligament during applied loads. Results After transection of the posterolateral corner structures, a significant increase in varus rotation was found to applied varus moments with a mean increased opening of 5.9° to varus stress at 30° and 5.8° at 90° of knee flexion. After proximal tibial medial opening wedge osteotomy, varus rotation was increased by a mean of 1.6° at 30° and 1.7° at 90° of knee flexion compared with the intact state. There was a significant decrease in varus rotation to a varus moment after osteotomy compared with the posterolateral sectioned state at both 30° and 90°. External rotation of the knee increased by 4.7° at 30° and 4.8° at 90° after posterolateral structure sectioning compared with the intact state. After the osteotomy, there was a significant decrease in external rotation compared with the posterolateral sectioned state, and there was no significant difference in external rotation compared with the intact state. There was a significant increase in force on the superficial medial collateral ligament after the osteotomy compared with both the intact and posterolateral corner cut state for both an applied varus moment and external rotation torque at both 30° and 90°. Conclusion Our results demonstrate that a proximal tibial medial opening wedge osteotomy decreased varus and external rotation laxity for posterolateral corner–deficient knees. Concurrently, an increase in force was observed on the superficial medial collateral ligament compared with the native state. Clinical Significance The improved stability observed in some patients with grade 3 posterolateral knee injuries after a proximal tibial medial opening wedge osteotomy appears to at least in part be due to tightening of the superficial medial collateral ligament. The long-term consequences of the increased force on the superficial medial collateral ligament on the medial compartment, and whether it elongates with time, merit further investigation.

Medial Opening Wedge Tibial Osteotomy and the Sagittal Plane

Background Altering the tibial slope in an anterior cruciate ligament–deficient knee has been shown to affect anterior-posterior tibial translation. The effects on articular contact pressure of altering tibial slope during a high tibial osteotomy are unknown. Hypotheses Performing an opening wedge osteotomy anterior to the midaxial line will increase tibial slope. Increasing tibial slope with a high tibial osteotomy in an anterior cruciate ligament–deficient knee redistributes tibiofemoral joint contact pressures onto the posterior tibial plateau. Study Design Controlled laboratory study. Methods Medial opening wedge high tibial osteotomies were performed, and a plate fixation with a known diameter inset was placed along the medial tibia in an anterior position and a posterior position on 9 cadaveric knees. Medial and lateral tibiofemoral contact pressures were measured at the resulting 2 different tibial slopes in both ligament-intact and ligament-deficient states using thin electronic sensors. Results Anterior plate application resulted in an increase in posterior tibial slope by an average of 6.6°(P <.001) compared with posterior plate placement. After medial opening wedge high tibial osteotomy, the mean peak lateral tibiofemoral contact pressure (3.4 MPa) was significantly greater (P=.002) than was the mean peak medial pressure (2.6 MPa). In ligament-intact specimens, altering the tibial slope did not significantly shift peak contact pressures. However, in ligament-deficient knees, increasing tibial slope by an average of 5.5° significantly redistributed the location of peak intra-articular pressure, shifting it posteriorly by 24% (P=.003). Conclusion Increasing tibial slope in anterior cruciate ligament–deficient knees with a high tibial osteotomy redistributes pressure into the posterior tibial plateau. Clinical Relevance In knees with chronic anterior cruciate ligament deficiency, posteromedial compartment degeneration is observed. Inadvertent redistribution of contact pressure into this area may be a cause of pain and premature clinical failure after medial opening wedge tibial osteotomy.

Primary stability of four different implants for opening wedge high tibial osteotomy

Since a significant number of implant failures have been reported in association with the procedure of open wedge valgus high tibial osteotomy, the initial biomechanical stability of different fixation devices was investigated in this study. Fifteen third generation Sawbones composite tibiae were used as a model. Four different plates were tested: a short spacer plate (OWO) (n = 4), a short spacer plate with multi-directional locking bolts (MSO) (n = 5), a prototype version of a long spacer plate with multi-directional locking bolts (MSOnew) (n = 2), and a long medial tibia plate fixator with locking bolts (MPF) (n = 4). All opening wedge osteotomies were performed by the same surgeon (PL) in a standardized fashion. Axial compression of the tibiae was performed using a materials testing machine under standardized alignment of the loading axis. Single load to failure tests as well as load-controlled cyclical failure tests were performed. The required force and cycles to failure were recorded. Osteotomy gap motion was measured using linear displacement transducers. Residual stability after failure of the opposite lateral cortex was analysed. Failure occurred at the lateral cortex bone-bride in all tested implants. The rigid long plate fixator (MPF) resisted the greatest amount of force (2,881 N) in the single load to failure tests. In the cyclical load-to-failure tests, the constructs with MPF resisted more than twice the amount of loading cycles when compared to the short spacer plates. The osteotomy gap motion was smallest in the MPF, with a reduction of the displacements of up to 65, 66 and 88%, when compared to OWO, MSO and MSOnew, respectively. The highest residual stability after failure of the lateral cortex was observed in MPF as well. The results suggest that the implant design strongly influences the primary stability of medial opening wedge tibial osteotomy. A rigid long plate fixator with angle-stable locking bolts yields the best results.

How plate positioning impacts the biomechanics of the open wedge tibial osteotomy; A finite element analysis

A numerical model of the medial open wedge tibial osteotomy based on the finite element method was developed. Two plate positions were tested numerically. In a configuration, (a), the plate was fixed in a medial position and (b) in an anteromedial position. The simulation took into account soft tissues preload, muscular tonus and maximal gait load. The maximal stresses observed in the four structural elements (bone, plate, wedge, screws) of an osteotomy with plate in medial position were substantially higher (1.13–2.8 times more) than those observed in osteotomy with an anteromedial plate configuration. An important increase (1.71 times more) of the relative micromotions between the wedge and the bone was also observed. In order to avoid formation of fibrous tissue at the bone wedge interface, the osteotomy should be loaded under 18.8% (∼50 kg) of the normal gait load until the osteotomy interfaces union is achieved.

Open wedge high tibial osteotomy: biomechanical investigation of the modified Arthrex Osteotomy Plate (Puddu Plate) and the TomoFix Plate

Objective. To determine the biomechanical properties of different fixation methods for high tibial medial opening wedge osteotomy in order to determine appropriate surgical and rehabilitation guidelines. Design. A biomechanical testing examined the construct stiffness and the fixation strength of two different plates. Background. Although medial opening wedge techniques for high tibial osteotomies have become popular in recent years, biomechanical data of frequently used implants is lacking. Methods. A 15-mm medial opening gap was stabilized in each of eight medium composite tibial bones either with the modified Arthrex Osteotomy Plate (Puddu Plate) or the TomoFix Plate. Results. Both constructs failed under compression and torsion at the lateral cortex and occurred at higher maximal forces by using the TomoFix Plate. After fracture of the lateral cortex the axial stiffness was reduced by 47% and the torsional rigidity by 54% for the TomoFix. For the Puddu Plate these reductions were 66% and 78%, respectively. The differences between the two groups were significant in all conducted tests ( P < 0.05). Conclusions. This study indicates that an unharmed lateral hinge largely dictates the stability after high tibial osteotomy. If the lateral cortex is injured, the TomoFix plate provides superior stability in both compression and torsion compared to the Puddu Plate. In the latter case additional fixation might be considered. Relevance These biomechanical tests helped to identify clinical situations in which the mechanical attributes of the plates would prove advantageous.