Opening wedge high tibial osteotomy for symptomatic hyperextension-varus thrust

BACKGROUND: The purpose of this study was to assess the functional outcome of opening wedge high tibial osteotomy (HTO) in a young, active group of patients with instability rather than osteoarthritis. METHODS: The results of 17 opening wedge HTOs in 16 patients with a symptomatic hyperextension-varus thrust were evaluated. Functional results were evaluated according to the activity scoring system of Tegner and Lysholm and using a 5-point visual analogue scale to assess change in knee stability and satisfaction. Radiographs were analyzed to determine changes in femorotibial and mechanical axis alignment, tibial slope, and patellar height. RESULTS: Patients were followed for a mean of 56 months. All patients had an increase in their activity score postoperatively. Nine patients rated their symptoms as significantly better and seven as somewhat better. All but one were satisfied with the surgery. Femorotibial axis alignment was changed to a mean of 6 degrees valgus, mechanical axis alignment was corrected to a mean of 46% toward the lateral compartment, posterior tibial slope was increased a mean of 8 degrees, and the ratio of patellar height was decreased a mean of 0.17. CONCLUSION: Opening wedge HTO can produce good functional and radiographic results in selected patients with a symptomatic thrust.     

Opening wedge high tibial osteotomy: plate position and biomechanics of the medial tibial plateau

Purpose

To ascertain whether changing position and size of the spacer may modify the load and displacement of the tibial plateau when performing an opening wedge high tibial osteotomy.

Methods

Fifteen sawbones tibia models were used. In the axial plane, the anterior, medial, and posterior thirds of the tibial plateau were marked, and the medial and posterior thirds were called “point 1” and “point 2”, respectively. A 7.5-mm-stainless steel indenter was used to apply the load over these two points: the load applied to point 1 simulated the load to that site when the knee was extended, and the load to point 2 simulated the load to the same area when the knee was flexed. Maximum load (N) and displacement (mm) were calculated.

Results

The system was shown to withstand higher loads with less displacement when the plate was posterior than it could do with the plate in the middle position. Significant differences were also found when comparing the anterior and middle position of the plate with the greatest displacement when the plate was anterior. The differences were increased when comparing the anterior and posterior positions of the plate. No statistical differences (n.s.) were found when using different spacers. The maximum stiffness was achieved if the plate was posterior and in point 1 indenter position, in which the force vector stands on the points of the lateral and medial supports (Fμ = 198.8 ± 61.5 N). The lowest stiffness was observed when the plate was anterior, and the force was applied to point 2 (Fμ = 29.7 ± 5.1 N).

Conclusions

Application of the plate in a more posterior position provides greater stability.     

Opening wedge high tibial osteotomy affects both the lateral patellar tilt and patellar height

In the current study, we evaluated changes in the patellofemoral joint indices in 49 knees from 39 patients (11 men and 28 women with a median age of 64 years; range 53–79) who had undergone an opening wedge high tibial osteotomy (OWHTO). Osteoarthritis had been diagnosed in 39 knees and osteonecrosis in the other 10 knees in this patient cohort. Radiographs showing anteroposterior and true lateral views of the knee joints while standing, and also skyline views while standing with a 30° flexion, were taken both pre- and postoperatively. Radiographic assessments were then performed using the following five parameters: femorotibial angle (FTA), modified Blackburne-Peel ratio (mBP), tibial slope (TS), lateral patellar tilt (LPT), and lateral patellar shift (LPS). The average LPT decreased significantly from 7.4° ± 3.7° to 5.2° ± 3.6° (P < 0.01). Patients treated with a greater than 15° correction showed a significantly bigger change in their LPT than those with corrections of 15° or less. No statistical differences were found between the preoperative (10.2 ± 4.5%) and postoperative (10.2 ± 4.7%) LPS measurements. Changes in the radiographic parameters were also observed in the patellofemoral joint after OWHTO. It is unclear to what extent the postoperative patellar shift and tilt affects the long-term clinical outcomes but our current results suggest that OWHTO negatively affects the congruency of the patellofemoral joint and should not exceed a correction of 15°.     

Medial opening wedge high tibial osteotomy: how i do it

Opening wedge high tibial osteotomy allows correction of alignment deformities in all planes, particularly in planned alterations to the tibial slope in the sagittal direction. In addition, corrections of 5° or less are easier to achieve than with closing wedge osteotomy. This technique has been previously described with favorable results. Throughout the procedure, attention to detail is essential for minimizing the potential for complications.     

胫骨高位截骨术:闭合与开放楔形截骨对比

目的比较胫骨高位截骨术中闭合楔形截骨法(闭合楔)与开放楔形截骨法(开放楔)的临床结果及影像学特点。方法选取2013年7月至2014年6月北京积水潭医院矫形骨科收治的因膝内翻畸形施行的29例(44膝)胫骨高位截骨术患者。其中16例(24膝)采用闭合楔形截骨术,13例(20膝)采用开放楔形截骨术,均采用Tomofix系列钢板进行固定,随访时间分别为平均18.3个月(18~24个月)和16.6个月(18~25个月)。于末次评价两组患者Lysholm评分的变化、关节活动度变化及并发症发生情况。影像学方面,对比两组患者力线矫正的准确性、矫正角度及,术前、术后髌骨高度的变化及胫骨平台后倾角的变化。结果闭合楔组患者Lysholm评分从术前的(96.8±6.3)分增加至术后的(98.2±3.3)分(P=0.828);开放楔组患者从术前的(95.4±8.3)分增加至术后的(98.1±3.4)分(P=0.656)。闭合楔组关节活动度术前为(137.7°±14.2°),术后为(133.5°±15.0°)(P=0.146);开放楔组术前为(138.5°±15.6°),术后为(134.3°±17.3°)(P=0.207)。闭合楔组有1例(1膝,4.2%)出现腓神经损伤症状,半年后恢复;另有1例(1膝,4.2%)出现截骨延迟愈合,术后6个月复查时截骨愈合。闭合楔组与开放楔组畸形矫正满意率分别为87.5%和90%(P=1.000)。闭合楔组矫正胫骨内翻的角度为(10.3°±4.3°);开放楔组为(9.4°±5.3°)(P=0.289)。在髌骨高度方面,术后闭合楔组Caton Deschamps指数(CDI)从(1.09±0.17)增大至(1.11±0.18)(P=0.761);开放楔组从(1.16±0.25)减小至(0.99±0.23)(P=0.034)。闭合楔组胫骨后倾角从(13.4°±5.1°)减小至(9.4°±5.3°)(P=0.010);开放楔组从(12.0°±4.1°)增大至14.9°±5.1°(P=0.050)。结论闭合楔与开放楔两种截骨技术都能获得满意的临床结果。开放楔可能减小髌骨高度,故对于术前即存在髌骨低位的患者,应避免采用开放楔,或者采用开放楔时冠状面截骨斜向前下方,将胫骨结节保留在近端截骨块,以避免进一步加重髌骨低位,影响关节活动。由于闭合楔可能减小胫骨平台后倾而开放楔可能增加后倾,故应按照实际需要个体化地选择截骨方式。     

The effect of closed wedge high tibial osteotomy on tibial slope: a radiographic study

In recent years there has been a renewed interest in high tibial osteotomies (HTOs). The development of new instruments and better fixation devices has significantly simplified the surgical procedure. This technique is frequently used to correct alignment in the frontal plane. However, changes in the sagittal plane following closed wedge HTO have not been appropriately investigated. Hence, the purpose of this study was to investigate any possible alteration of the tibial slope introduced by closed wedge HTO. In addition, we also investigated whether there is a correlation between changes of the frontal plane and alteration of the tibial slope in the sagittal plane. In a retrospective study, radiographs of 67 patients (41 males, mean age 36.6 and 26 females, mean age 39.4 years) who underwent a closed wedge HTOs or removal of hardware for a previous HTO were reviewed.The frontal plane was corrected by a mean of 7.9° (6–14°). The mean posterior tibial slope on the preoperative images averaged 6.1° (0–12°). The postoperative radiographs demonstrated a significant (P=0.0001) decrease of the posterior tibial slope to a mean of 1.2°. The magnitude of HTO in the frontal plane had no significant effect (P=0.739) on the postsurgical posterior tibial slope in the sagittal plane.     

The patella and tibial condyle position after combined and after closing wedge high tibial osteotomy

High tibial osteotomy changes the patella and tibial condyle position, which makes the subsequent total knee replacement technically demanding. From 1 January 1993 to 31 December 2000, combined osteotomy [After the first osteotomy made 2 cm distally to the joint line, a bone wedge is removed based laterally. Its tip ends at the center of the tibial condyle (half bone wedge). The distal part of the tibia is placed into the valgus position and the half bone wedge is placed into the gap opened medially.] was performed on 103 knees and closing wedge osteotomy was performed on 47 consecutive knees. Eighty combined (group A) and 41 closing wedge (group B) osteotomy were studied. All knees were assessed radiologically before surgery, in the 10th postoperative week, in the 12th postoperative month and at the time of the final follow-up (in group A—66.15 months, in group B—66.61 months). We examined the change of the femorotibial angle, of the patellar height according to the method of Insall and Salvati, of the tibial slope angle according to the method of Bonnin, of the tibial condylar offset according to the method of Yoshida and of the distance between the lateral tibial plateau and the top of the fibular head. In group A and B, the recurrence of the varus deformity was not noted and valgus alignment did not increase in any case. In group-A, the Insall–Salvati ratio remained unchanged in 65% of knees. The tibial slope angle decreased in both groups. There was correlation between the change of the tibial condylar offset and the angle of the correction in both groups. There was correlation between the change of the distance between the lateral tibial plateau and the top of the fibular head. After combined osteotomy, the transposition of the tibial condyle and the decrease of the distance between the lateral tibial plateau and the top of the fibular head was less than after closing wedge osteotomy, although the average angle of correction was more after combined osteotomy (11.835°), than after closing wedge osteotomy (9.465°). Theoretically, the recurrence of the varus deformity, the increase of the valgus alignment and (in majority of cases) the shortening of the patellar tendon do not compromise the likelihood of successful conversion to the subsequent total knee replacement, either after combined or after closing wedge osteotomy. The combined osteotomy does not lead to considerable transposition of the tibial condyle and to considerable lateral tibial bone loss; therefore, theoretically, the combined osteotomy does not impair the subsequent total knee replacement.     

Modification of tibial slope after medial opening wedge high tibial osteotomy: clinical study and mathematical modelling

A prospective non-randomized non-comparative study involved 30 patients who underwent a medial opening wedge high tibial osteotomy for medial knee osteoarthritis using a specific surgical procedure. The tibial slope was calculated pre-operatively and at a mean follow-up of 14 months. A mathematical model of the surgical procedure was developed in order to plan the height of the medial opening wedge and to predict tibial slope changes. Tibial-slope measurements accuracy was good (0.04° ± 0.92°). There was no significant difference for the mean tibial slope before and after surgery (9.2° ± 5.6° vs. 9.1° ± 5.6°, P = 0.47). There was a perfect agreement between the model and the real values for the HKA angle (0.85) and the tibial slope (0.98). The surgical technique used did not modify the tibial slope. Our mathematical model for pre-operative planning was validated with very good accuracy.     

The correlation of correction magnitude and tibial slope changes following open wedge high tibial osteotomy

We investigated whether there is a correlation between coronal plane correction magnitude and tibial slope in patients treated with medial open wedge high tibial osteotomy (OWHTO) and also measured changes in patellar height. Thirty-four knees treated with for varus deformities were retrospectively reviewed and the follow-up period of the patients was averaged 24.1 months. Preoperative and postoperative measurements of the Hospital for Special Surgery (HSS) score, Insall–Salvati index, posterior tibial slope angle, mechanical axis deviation, proximal medial tibial angle (PMTA) was used to determine. All patients had a significant increase in their HSS score postoperatively (P < 0.0001). There was no significant correlation between the differences in patellar heights (P = 0.368). The mechanical axis deviation was altered by a mean of 25.5 ± 10.9 mm and the difference was statistically significant (P < 0.05). The mean posterior tibial slope angle on preoperative radiographs was 9.0 ± 5.1°; on postoperative radiographs it was 11.7 ± 5.7° and the difference was statistically significant (P < 0.007). Seventeen knees (50%) demonstrated postoperative posterior tibial slope angle increases; 7 knees (21%) had a decrease in this angle, while 10 knees (29%) showed no change. Statistical analyses revealed that the mechanical axis deviation was not correlated with change in tibial slope (P = 0.837). Although we could not find a correlation between tibial slope change and the amount of coronal correction, 50% of our patients demonstrated increased tibial slope.     

Gait analysis of walking before and after medial opening wedge high tibial osteotomy

Introduction

Medial opening wedge high tibial osteotomy (HTO) is used to treat medial compartment osteoarthritis (OA) of the knee. HTO shifts the weight-bearing line from the medial compartment into the lateral compartment. The aim of this study was to investigate the functional biomechanical consequences of this alteration in alignment.

Methods

Eleven male patients with medial compartment osteoarthritis underwent three-dimensional gait analysis during level walking before 12 months and after medial opening wedge HTO. Nine male control subjects of a similar age were also tested using the same protocol. Sagittal and coronal angles and moments in both operated and non-operated knees were compared. Pre and postoperative radiographic coronal plane alignment was also measured.

Results

Walking speed increased significantly postoperatively (P = 0.0001) and was not different from controls. Preoperatively, maximum knee flexion in stance was reduced compared to control (P = 0.02). Postoperatively, maximum knee flexion increased significantly (P = 0.005) and was the same as the controls. Similar changes were observed for the maximum knee flexion moment. The mean maximum varus angle during stance was reduced from 13.5° preoperatively to 5.4° postoperatively (P = 0.0001) compared to (6.8°) in controls. The mean maximum adduction moment also reduced from 3.9 to 2.7 (% Bw/ht, P = 0.02), compared to 3.6 in control subjects. Interestingly, the adduction moments in the non-operated knee increased postoperatively from 3.3 to 4.1 (% Bw/ht, P = 0.02). The mean radiological mechanical alignment was changed from 172 degrees preoperatively to 180 degrees postoperatively (P < 0.001).

Conclusion

HTO resulted in normalisation of several dynamic knee function parameters such as walking speed, knee flexion and external knee flexion moment. As anticipated, HTO reduced the varus angle and adduction moments of the operated knee. An increased adduction moment in the non-operated knee over the first postoperative year was found.

Level of evidence

Prospective case–control clinical laboratory study, Level III.     

Wedge volume and osteotomy surface depend on surgical technique for high tibial osteotomy

Purpose

Biplanar open-wedge high tibial osteotomy (HTO) is thought to promote rapid bone healing due to the increased cancellous bone surface compared to other HTO techniques. However, precise data on the bone surface area and wedge volume resulting from both open- and closed-wedge HTO techniques remain unknown. We hypothesized that biplanar rather than uniplanar HTO better reflects the ideal geometrical requirements for bone healing, representing a large cancellous bone surface combined with a small wedge volume.

Methods

Tibial saw bones were assigned to 4 different groups of valgisation high tibial osteotomies: group 1: open-wedge uniplanar HTO; group 2: open-wedge biplanar HTO with ascending frontal cut; group 3: open-wedge biplanar HTO with descending frontal cut (retrotubercule osteotomy technique), and group 4: closed-wedge uniplanar HTO. Bone surface areas of all osteotomy planes were quantified. Wedge volumes were determined using a prism-based algorithm, applying standardized wedge heights of 5, 10, and 15 mm.

Results

The open-wedge biplanar osteotomy with a descending frontal cut (group 3) created significantly larger bone surfaces compared to the “classic” biplanar technique with an ascending frontal cut (group 2) and compared to all uniplanar techniques. Bone surfaces after the classic open-wedge technique (group 2) were slightly larger compared to all uniplanar techniques (group 1 and 4). No significant differences of wedge volumes were found between the retrotubercle (group 3) and classic open-wedge techniques (group 2). Wedge volumes were significantly higher in the uniplanar open-wedge technique (group 1) compared to the biplanar open-wedge techniques (group 2 and 3).

Conclusion

Bone geometry following HTO suggests that the biplanar open-wedge techniques simultaneously create smaller wedge volumes and larger bone surface areas compared to the uniplanar open-wedge techniques. The relatively neglected closed-wedge technique still offers in theory the best healing potential, characterized by an almost absent wedge volume and a large bone-to-bone contact area. Although this idealized geometric view on bony geometry excludes all biologic factors that influence bone healing, the current data suggest a general rule for the applied standard osteotomy techniques and all of their surgical modifications: reducing the amount of slow gap healing and simultaneously increasing the area of faster contact healing may be beneficial for osteotomy healing. Thus, a biplanar rather than a uniplanar osteotomy may be performed for high tibial osteotomy in clinical practice.     

Open wedge high tibial osteotomy using fractioned drill osteotomy: a surgical modification that lowers the complication rate

We investigated retrospectively 132 cases of open wedge high tibial osteotomy using an external fixation device, concentrating on the rate of neurological complications. One group of patients underwent surgery according to the conventional technique (n=89). The rate of transient neurological complications was 15.7%; 7 months after surgery the rate of persistent deficits was 12.4%. For the second group (n=43) a modified surgical technique was used that lowered the complication rate significantly (transient deficits 14%, persistent deficits 4.7%). In the modified technique the osteotomy is not performed in the conventional way using an oscillating saw but through consecutive drill holes of increasing diameter followed by osteoclasis. The lower complication rate in the second group is mainly due to the less extensive approach that leads to a smaller number of postoperative tibialis anterior syndromes (type B lesion). No differences were found with type C lesions (extension deficit of D1). No complete peroneal nerve palsy (type A) occurred in either group. We conclude that the reduction of neurological complications in group 2 is related to the less extensive approach of the proposed technique.     

Avoiding intraoperative complications in open-wedge high tibial valgus osteotomy: technical advancement

Open-wedge high tibial osteotomy for varus osteoarthritis of the knee is a successful treatment option, but is associated with potential intraoperative complications, jeopardizing outcome. We describe four technical hints avoiding complications as tibia plateau fracture, lateral hinge dislocation, over- and undercorrection, and unwanted increase of the posterior tibial slope and axial malrotation. The technique, which is primarily based on placing five Kirschner-wires (one for the osteotomy direction, two for the external fixator, and two for rotational and slope control) is simple, reproducible, inexpensive, and readily available.     

Accuracy of high tibial osteotomy: comparison between open- and closed-wedge technique

High tibial osteotomy is an established technique for the treatment of varus malaligned knees. This study analyses the difference between the amount of correction in the preoperative planning and the postoperative result. Furthermore, it compares the difference of the accuracy between open-wedge osteotomy and closed-wedge osteotomy. About 61 patients were either treated with open-wedge or closed-wedge high tibial osteotomy. Preoperative planning and postoperative analysis were performed with a special planning software. The influence of operative technique, aetiology, age, number of previous surgeries, amount of correction and accuracy of the correction compared to the preoperative planning were analysed. The overall postoperative mechanical axis differed form preoperative planning by 2.1° ± 1.7°. The accuracy in the open-wedge group (1.7° ± 1.6°) was significantly higher than in the closed-wedge group (2.6° ± 1.8°; P = 0.038). In patients with congenital varus deformity, the accuracy of the correction was significantly higher than in patients with post-traumatic deformity. The authors recommend open-wedge technique in combination with fixed-angle plates for high tibial osteotomy.     

High tibial open wedge osteotomy below the tibial tubercle: clinical and radiographic results

Purpose

The purpose of this study was to evaluate the clinical and radiographic results of open wedge HTO below the tubercle for genu varum in relatively young patients.

Methods

Thirty-seven knees in 19 patients with genu varum treated by open wedge HTO below the tubercle between 2001 and 2008 were retrospectively studied. Median follow-up was 36 months (12–108), and median patient age at the time of surgery was 26 years (16–45). Clinical results were evaluated using Lysholm knee scores and Hospital for Special Surgery knee scores. Satisfaction with the results of surgery (0–10 points) was subjectively evaluated using operative scar (1–5 points) and leg shape (1–5 points) results at follow-up. Radiographic evaluations were made using: (1) tibiofemoral angles, (2) mechanical axis deviations, (3) varus-valgus inclinations of the tibial plateau, (4) tibial slopes, and (5) Insall-Savati and (6) Blackburne-Peel ratios.

Results

All but one patient achieved radiographic healing and union at the osteotomy site at an average of 3 months postoperatively. Average Lysholm knee score improved from 89.4 ± 8.7 preoperatively to 98.6 ± 2.5 at final follow-up (P = 0.0001), and mean HSS score improved from 91.1 ± 5.6 preoperatively to 98.5 ± 2.0 at final follow-up (P = 0.0001). Mean patient satisfaction score at final follow-up was 8.6 ± 1.0, and mean tibiofemoral angle increased from ?1.6° preoperatively to 7.7° at final follow-up (P < 0.0001). The point where the mechanical axis crosses the tibial plateau also shifted significantly from 15.0% preoperatively to 50.6% at final follow-up (P = 0.0002). However, mean posterior tibial slope did not change significantly (9.7° preoperatively and 8.7° at final follow-up; P = NS), and neither did patella heights as measured by Insall-Savati and Blackburne-Peel ratios.

Conclusion

Both functional assessment and radiographic measures indicated that HTO below the tibial tubercle leads to significant improvements in radiographic parameters and knee function without changes in patellar height or posterior tibial slope. The results obtained support the hypotheses that opening wedge HTO below the tibial tubercle should be recommended in relatively young patients with genu varum.

Level of evidence

Therapeutic study, Level IV.     

Staged medial opening wedge high tibial osteotomy for bilateral varus gonarthrosis: biomechanical and clinical outcomes

Purpose

(1) To evaluate the effect of staged bilateral medial opening wedge high tibial osteotomy (HTO) on established biomechanical risk factors for disease progression and on validated measures of pain and function and (2) To compare outcomes in patients having the second surgery staged within or beyond 12 months of the first surgery.

Methods

Thirty-seven patients with bilateral varus alignment and medial compartment osteoarthritis underwent staged bilateral medial opening wedge HTO (21 within and 16 beyond 12 months). Patients underwent full-limb standing anteroposterior radiographs to determine frontal plane alignment (mechanical axis angle) and three-dimensional gait analysis to estimate the distribution of load across the tibiofemoral compartments (external knee adduction moment). Patients also completed the Knee Injury and Osteoarthritis Outcomes Scores (KOOS), the Lower Extremity Functional Scale, the Short Form Health Survey and the six-minute walk test (6MWT). Patients (both limbs) were evaluated before and approximately 6, 12 and 24 months after each surgery.

Results

There were statistically and clinically significant changes in both limbs that were of similar magnitudes and that remained relatively stable over time postoperatively. Mean (95 % CI) improvements in outcomes were as follows. Mechanical axis angle: 9.4° (8.4°, 10.4°) (i.e. average change of both limbs), peak knee adduction moment: ?1.7 %BW*Ht (?2.1, ?1.4 %BW*Ht) (i.e. average change of both limbs), 6MWT: 36.7 m (19.4, 54.0 m), SF-12 Physical Component Summary: 12.0 (8.5, 15.5) and KOOS Pain: 25.4 (19.6, 31.2). Other than the shorter time period to reach maximum benefit of both surgeries, there were no remarkable differences at final assessment between patients having surgeries staged within or beyond 12 months.

Conclusions

The present findings demonstrate that patients with bilateral varus gonarthrosis experience marked improvements in established biomechanical risk factors for disease progression bilaterally (mechanical axis angles and external knee adduction moments), as well as clinically important improvements in patient-important outcomes, after staged medial opening wedge HTO. Current findings suggest no difference in outcomes for patients who have the second surgery staged within or beyond 12 months of the first surgery.

Level of evidence

IV.     

Delayed- and non-union following opening wedge high tibial osteotomy: surgeons’ results from 182 completed cases

Opening wedge high tibial osteotomy (OWHTO) is a recently described procedure for medial compartment arthritis of the knee in the active, younger population. Despite having a number of advantages over the traditional closing wedge high tibial osteotomy (CWHTO) a potential complication of OWHTO is a high rate of delayed- and non-union. This study reports the occurrence of delayed- and non-union following OWHTO for medial compartment arthritis of the knee. Questionnaires were sent to all current members of the Australian Knee Society (n=45), a special interest group of the Australian Orthopaedic Group. Surgeons were asked primarily to indicate how many OWHTOs they had performed, and how many of these had progressed to union, delayed-union and non-union. All 45 questionnaires were returned, with 21 surgeons (47%) performing OWHTOs. A total of 188 OWHTO cases were reported, of which 182 were complete. Of these complete cases 167 (91.8%) were classed as united, 12 (6.6%) delay-united and 3 (1.6%) non-united. The results of this study demonstrate that the rate of delayed- and non-union following OWHTO for medial compartment arthritis of the knee is relatively low and comparable to that reported for traditional CWHTO.     

Navigated open-wedge high tibial osteotomy: advantages and disadvantages compared to the conventional technique in a cadaver study

High tibial osteotomy (HTO) is an established therapy for the treatment of symptomatic varus malaligned knees. A main reason for disappointing clinical results after HTO is the under- and overcorrection of the mechanical axis due to insufficient intraoperative visualisation. Twenty legs of fresh human cadaver were randomly assigned to navigated open-wedge HTO (n=10) or conventional HTO using the cable method (n=10). Regardless of the pre-existing alignment, the aim of all operations was to align the mechanical axis to pass through 80% of the tibial plateau (beginning with 0% at the medial edge of the tibial plateau and ending with 100% at the lateral edge). This overcorrection was chosen to ensure a sufficient amount of correction. Thus, the medial proximal tibia angle (MPTA) increased by 9.1±2.9° (range 5.2°–12.3°) on the average after navigated HTO and by 8.9±2.9° (range 4.7°–12.6°) after conventional HTO. After stabilization with a fixed angle implant, the alignment was measured by CT. After navigated HTO, the mechanical axis passed the tibial plateau through 79.7% (range 75.5–85.8%). In contrast, after conventional HTO, the average intersection of the mechanical axis was at 72.1% (range 60.4–82.4%) (P=0.020). Additionally, the variability of the mean corrections was significantly lower in the navigated group (3.3% vs. 7.2%, P=0.012). Total fluoroscopic radiation time was significantly lower in the navigated group (P=0.038) whereas the mean dose area product was not significantly different (P=0.231). The time of the operative procedure was 23 min shorter after conventional HTO (P<0.001). Navigation systems provide intraoperative 3-dimensional real time control of the frontal, sagittal, and transverse axis and may increase the accuracy of open-wedge HTO. Future studies have to analyse the clinical effects of navigation on corrective osteotomies.