Change In Tibial Slope Research Articles

Posterior Tibial Slope in Medial Opening-wedge High Tibial Osteotomy: 2-D Versus 3-D Navigation

Although opening-wedge high tibial osteotomy (HTO) is used to correct deformities, it can simultaneously alter tibial slope in the sagittal plane because of the triangular configuration of the proximal tibia, and this undesired change in tibial slope can influence knee kinematics, stability, and joint contact pressure. Therefore, medial opening-wedge HTO is a technically demanding procedure despite the use of 2-dimensional (2-D) navigation. The authors evaluated the posterior tibial slope pre- and postoperatively in patients who underwent navigation-assisted opening-wedge HTO and compared posterior slope changes for 2-D and 3-dimensional (3-D) navigation versions. Patients were randomly divided into 2 groups based on the navigation system used: group A (2-D guidance for coronal alignment; 17 patients) and group B (3-D guidance for coronal and sagittal alignments; 17 patients). Postoperatively, the mechanical axis was corrected to a mean valgus of 2.81° (range, 1°-5.4°) in group A and 3.15° (range, 1.5°-5.6°) in group B. A significant intergroup difference existed for the amount of posterior tibial slope change (Δ slope) pre- and postoperatively (P=.04).Opening-wedge HTO using navigation offers accurate alignment of the lower limb. In particular, the use of 3-D navigation results in significantly less change in the posterior tibial slope postoperatively than does the use of 2-D navigation. Accordingly, the authors recommend the use of 3-D navigation systems because they provide real-time intraoperative information about coronal, sagittal, and transverse axes and guide the maintenance of the native posterior tibial slope.

Paper 144: Effect of Opening-wedge High Tibial Osteotomy on Three-dimensional Knee Kinematics

Medial opening-wedge high tibial osteotomy (HTO) is a treatment for medial tibiofemoral osteoarthritis caused by varus malalignment. This malalignment shifts the line of action of the ground reaction force relative to the centre of the knee, which increases load in the medial compartment. This increased load is widely believed to be the cause of medial tibiofemoral (TF) OA. HTO restores the line of action to a neutral or slightly lateral position. Consensus has emerged on an optimal range of varus/valgus angular correction, however achieving this correction does not guarantee good clinical results. A key limitation of current assessment that may explain this is that the current standard for assessing tibiofemoral alignment, a standing radiograph, provides a poor assessment of the mechanics of the joint. Three-dimensional measurements of tibiofemoral and patellofemoral kinematics in vivo have recently become available but the effect of opening-wedge high tibial osteotomy on knee kinematics is not clear. Our research question was: how does opening-wedge HTO affect 3D tibiofemoral and patellofemoral kinematics? Three-dimensional tibiofemoral and patellofemoral kinematics were assessed in four subjects before HTO surgery and at 6 months follow-up using a validated MR imaging method (1Fellows R.A. et al.J Biomech. Aug 2005; 38: 1643-1652Abstract Full Text Full Text PDF PubMed Scopus (57) Google Scholar, 2Fellows R.A. et al.J Magn Reson Imaging. 2005; 22: 145-153Crossref PubMed Scopus (34) Google Scholar). Ethics board approval was granted and informed consent was obtained from all subjects for this study. Titanium surgical hardware was used for minimum artifact in the images. For each assessment, the subject lay supine in the MR scanner. A high-resolution T1-weighted mulitslice scan of the knee was performed in a relaxed position. Low resolution images of the knee were then obtained at six flexion angles (10°–60°) while the subject loaded his/her knee using a specially designed loading rig. Bone was segmented from the MR images using Analyze. Surfaces (high-res) and contours (low-res) were then imported into MATLAB. The high-resolution models were shapematched to the low-resolution data sets using an iterative closest points algorithm. Anatomical axes were assigned to each bone using anatomical landmarks. Kinematic parameters (rotations and translations) with respect to femur for both tibia and patella were output. Linear best fits were calculated for each parameter with respect to tibial flexion. Slope and intercept were examined using a paired t-test. HTO significantly shifted the tibia anteriorly through the range of flexion (p<0.05). The average change at 30 degrees was 6.5 mm. Correlation coefficients for the linear fits were r^2 = 0.73-0.98. HTO significantly shifted the patella distally through the range of flexion (p<0.05). The average change at 30 degrees was 1.9 mm. Correlation coefficients for the linear fits were r^2 = 0.92-0.99. Other kinematic parameters were changed following surgery, but the changes were not statistically significant in this small group: tibial adduction, patellar spin, patellar tilt, tibial proximal translation, and patellar flexion. Changes were evident in the patellar parameters spin and tilt, however the r^2 values for the linear fits were low. If there is a consistent pattern in these kinematic parameters, it may be best represented by a higher-order polynomial fit. HTO decreased tibiofemoral adduction (up to 10 degrees) in three subjects, while it remained similar in one subject. Tibial anterior translation with surgery is clinically important because it suggests that the contact centers in the tibiofemoral joint may have shifted posteriorly, an outcome thought to be related to changes in tibial slope (3Rodner C.M. et al.52nd ORS. 2006; (Paper No. 0250)Google Scholar). Anterior translation in this case is not due to a major change in tibial slope: for three subjects direct confirmation was obtained showing tibial slope change was less than 3 degrees.

A case series of lateral opening wedge high tibial osteotomy for valgus malalignment

Lateral opening wedge high tibial osteotomy is a rarely employed surgical technique used for the treatment of lateral knee pain and degeneration in the setting of genu valgum. There exists little evidence of the suitability of this procedure for patients requiring osteotomies with a small correction. A case series of 23 patients (24 knees) undergoing lateral opening wedge high tibial osteotomy with a minimum follow-up of 2 years was performed between 2002 and 2008. A surgical technique avoiding the need for fibular osteotomy is described. Adverse events, patient-reported outcomes and radiographic measures of alignment were assessed at baseline, at 6 months postoperatively, and at time of final follow-up. A subgroup of 12 patients also underwent 3D gait analysis at the same time points. The mean follow-up was 52 months (±20.4). Statistically and clinically significant improvements were identified in the lower extremity functional scale [mean change (95%CI) = 10 (2.4, 17.6)], and in the knee injury and osteoarthritis outcome score [mean change (95%CI) = 10.9 (0.5, 21.4)]. Mechanical axis changed from 2.4 ± 2.4° valgus to 0 ± 2.6° varus (p<0.001), anatomical axis from 6.9 ± 2.8° to 4.7 ± 2.5° valgus (p < 0.001), with weight-bearing line offset changing from 60.2 ± 11.4% to 49.5 ± 12.4% (p < 0.001). Change in lateral tibial slope, from 6.5 ± 2.2° to 7.5 ± 2.3°, was very small and not statistically significant (n.s.). The peak knee adduction moment during gait significantly increased [mean change (95%CI) = 0.72%BW*Ht (0.42, 1.02), suggesting a medial shift in dynamic knee joint load. Two patients underwent total knee arthroplasty during the study period. Lateral opening wedge high tibial osteotomy is a viable surgical option for patients with lateral knee pain and valgus malalignment requiring small degrees of correction. IV.

The Effect of Tibial Posterior Slope on Contact Force and Ligaments Stresses in Posterior-Stabilized Total Knee Arthroplasty-Explicit Finite Element Analysis

PurposeThe purpose of this study is to evaluate the effect of change in tibial posterior slope on contact force and ligament stress using finite element analysis.Materials and MethodsA 3-dimensional finite element model for total knee arthroplasty was developed by using a computed tomography scan. For validation, the tibial translations were compared with previous studies. The finite element analysis was conducted under the standard gait cycle, and contact force on ultra-high molecular weight polyethylene (UHMWPE) and stresses on lateral and medial collateral ligaments were evaluated.ResultsThe tibial translations showed similarity with previous studies. As the tibial posterior slope angle increases, the contact stress area increased and was well distributed, and the contact force on UHMWPE decreased overall. However, the maximum contact force in the case for 10° case was greater than those for others. The stresses on ligaments were the greatest and smallest in 0° and 10° cases, respectively.ConclusionsThe higher tibial posterior slope angle leads to the lower contact stress and more extensive stress distribution overall in posterior-stabilized total knee arthroscopy. However, it does not absolutely mean the smallest contact force. The stresses on ligaments increased with respect to the smaller tibial posterior slope angle.

Monoplanar versus biplanar medial open-wedge proximal tibial osteotomy for varus gonarthrosis: a comparison of clinical and radiological outcomes

We compared clinical and radiological results of two proximal tibial osteotomy (PTO) techniques: monoplanar medial open-wedge osteotomy and biplanar retrotubercle medial open-wedge osteotomy, stabilised by a wedged plate. We evaluated 88 knees in 78 patients. Monoplanar medial open-wedge PTO was performed on 56 knees in 50 patients with a mean age of 55 ± 9 years. Biplanar retrotubercle medial open-wedge PTO was performed on 32 knees in 28 patients with a mean age of 57 ± 7 years. Mean follow-up periods were 40.6 ± 7 months for the monoplanar PTO group and 38 ± 5 months for the biplanar retrotubercle PTO group. Clinical outcome was evaluated using the hospital for special surgery scoring system, and radiological outcome was evaluated by the measurements of femorotibial angle (FTA), patellar height and tibial slope changes. In both groups, post-operative HSS scores increased significantly. No significant difference was found between groups in FTA alteration, but the FTA decreased significantly in both groups. Patellar index ratios decreased significantly in the monoplanar PTO group (Insall-Salvati Index by 0.07, Blackburne-Peel Index by 0.07), but not in the biplanar retrotubercle PTO group. Tibial slopes were increased significantly in the monoplanar PTO group, but not in the retrotubercle PTO group. Biplanar retrotubercle medial open-wedge osteotomy and monoplanar medial open-wedge osteotomy are both clinically effective for the treatment for varus gonarthrosis. Retrotubercle osteotomy also prevents patella infera and tibial slope changes radiologically.

The Effect of Proximal Tibial Slope on Dynamic Stability Testing of the Posterior Cruciate Ligament– and Posterolateral Corner–Deficient Knee

Background: Proximal tibial slope has been shown to influence anteroposterior translation and tibial resting point in the posterior cruciate ligament (PCL)–deficient knee. The effect of proximal tibial slope on rotational stability of the knee is unknown. Hypothesis: Change in proximal tibial slope produced via osteotomy can influence both static translation and dynamic rotational kinematics in the PCL/posterolateral corner (PLC)–deficient knee. Study Design: Controlled laboratory study. Methods: Posterior drawer, dial, and mechanized reverse pivot-shift (RPS) tests were performed on hip-to-toe specimens and translation of the lateral and medial compartments measured utilizing navigation (n = 10). The PCL and structures of the PLC were then sectioned. Stability testing was repeated, and compartmental translation was recorded. A proximal tibial osteotomy in the sagittal plane was then performed achieving either +5° or −5° of tibial slope variation, after which stability testing was repeated (n = 10). Analysis was performed using 1-way analysis of variance (ANOVA; α = .05). Results: Combined sectioning of the PCL and PLC structures resulted in a 10.5-mm increase in the posterior drawer, 15.5-mm increase in the dial test at 30°, 14.5-mm increase in the dial test at 90°, and 17.9-mm increase in the RPS (vs intact; P < .05). Increasing the posterior slope (high tibial osteotomy [HTO] +5°) in the PCL/PLC-deficient knee reduced medial compartment translation by 3.3 mm during posterior drawer (vs deficient; P < .05) but had no significant effect on the dial test at 30°, dial test at 90°, or RPS. Conversely, reversing the slope (HTO −5°) caused a 4.8-mm increase in medial compartment translation (vs deficient state; P < .05) during posterior drawer and an 8.6-mm increase in lateral compartment translation and 9.0-mm increase in medial compartment translation during RPS (vs deficient state; P < .05). Conclusion: Increasing posterior tibial slope diminished static posterior instability of the PCL/PLC-deficient knee as measured by the posterior drawer test but had little effect on rotational or dynamic multiplanar stability as assessed by the dial and RPS tests, respectively. Conversely, decreasing posterior slope resulted in increased posterior instability and a significant increase in the magnitude of the RPS. Clinical Relevance: These results suggest that increasing posterior tibial slope may improve sagittal stability in the PCL/PLC-deficient knee. Moreover, a knee with diminished posterior tibial slope may demonstrate greater multiplanar instability in this setting. Consequently, proximal tibial slope should be considered when treating combined PCL/PLC injuries of the knee.

Posterior tibial slope changes after opening- and closing-wedge high tibial osteotomy: A comparative prospective multicenter study

Valgus high tibial osteotomy is considered to be an effective treatment for unicompartmental medial osteoarthritis. It is generally admitted that tibial slope increases after open-wedge high tibial osteotomy and decreases after closing-wedge high tibial osteotomy. However, the effects on posterior tibial slope of closing- or opening-wedge osteotomies remain controversial. We analyzed the modifications of tibial slope after opening- and closing-wedge high tibial osteotomies and compared the results of these two procedures. We hypothesized that there was no difference in postoperative tibial slope between opening and closing-wedge osteotomies. This prospective consecutive nonrandomized multicenter study was conducted between January 2008 and March 2009 and included 321 patients: 205 men and 116 women. A total of 224 patients underwent an opening-wedge high tibial osteotomy and 97 a closing-wedge osteotomy. The mean age was 52 years ± 9 and the mean body mass index was 28kg/m(2) ± 5. The main etiology was primary arthritis. Posterior tibial slope was measured preoperatively and at the last follow-up on a lateral radiograph in relation to the posterior tibial cortex. In the opening-wedge group, a definite 0.6° increase in tibial slope (P=0.016) was observed. In the closing-wedge group, a definite 0.7° decrease in tibial slope (P=0.02) was found. Fourteen percent of the opening-wedge osteotomies increased tibial slope by 5° or more versus only 2% of the closed-wedge osteotomies (P<0.001). Twelve percent of the closing-wedge high tibial osteotomies led to a decrease of 5° or more of the tibial slope versus 7% of the opening-wedge osteotomies (P<0.02). These results confirm what is generally reported in the literature, i.e., an increase in tibial slope in opening-wedge high tibial osteotomy and a decrease in the slope in closing-wedge osteotomies. These tibial slope changes appear to be very limited in this series, less than 1° on average. However, there was a bias since the open-wedge technique was preferred in cases with substantial varus deformity. We emphasize the importance of surgical technique to avoid alteration of the tibial slope, particularly in opening-wedge high tibial osteotomy for which we recommend a release of posterior soft tissue and a complete osteotomy of the posterior cortex of the tibia. III. Prospective consecutive nonrandomized multicenter study.

Effect of tibial slope on the stability of the anterior cruciate ligament–deficient knee

We aimed to quantify the effect of changes in tibial slope on the magnitude of anterior tibial translation (ATT) in the anterior cruciate ligament (ACL)-deficient knee during the Lachman and mechanized pivot shift tests. We hypothesized that increased posterior tibial slope would increase the amount of ATT of an ACL-deficient knee, while leveling the slope of the tibial plateau would decrease the amount of ATT. Lachman and mechanized pivot shift tests were performed on hip-to-toe cadaveric specimens, and ATT of the lateral and the medial compartments was measured using navigation (n=11). The ACL was then sectioned. Stability testing was repeated, and ATT was recorded. A proximal tibial osteotomy in the sagittal plane was then performed achieving either +5 or -5° of tibial slope variation after which stability testing was repeated (n=10). Sectioning the ACL resulted in a significant increase in ATT in both the Lachman and mechanized pivot shift tests (P<0.05). Increasing or decreasing the slope of the tibial plateau had no effect on ATT during the Lachman test (n.s.). During the mechanized pivot shift tests, a 5° increase in posterior slope resulted in a significant increase in ATT compared to the native knee (P<0.05), while a 5° decrease in slope reduced ATT to a level similar to that of the intact knee. Tibial slope changes did not affect the magnitude of translation during a Lachman test. However, large changes in tibial slope variation affected the magnitude of the pivot shift.

Effects of tibial slope changes in the stability of fixed bearing medial unicompartmental arthroplasty in anterior cruciate ligament deficient knees

Patients with anterior cruciate ligament (ACL) deficiency may have increased failure rates with UKA as a result of abnormal contact stresses and altered knee kinematics. Variations in the slope of the tibial component in UKA may alter tibiofemoral translation, and affect outcomes. This cadaveric study evaluated tibiofemoral translation during the Lachman and pivot shift tests after changing the slope of a fixed bearing unicondylar tibial component. Sectioning the ACL increased tibiofemoral translation in both the Lachman and pivot shift tests (P<0.05). Tibial slope leveling (decreasing the posterior slope) of the polyethylene insert in a UKA decreases anteroposterior tibiofemoral translation in the sagittal plane to a magnitude similar to that of the intact knee. With 8° of tibial slope leveling, anterior tibial translation during the Lachman test decreased by approximately 5mm. However, no variation in slope altered the pivot shift kinematics in the ACL deficient knees.

Increase in posterior tibial slope would result in correction loss in frontal plane after medial open-wedge high tibial osteotomy

The purpose of this study was to clarify the causes of the increase in the posterior tibial slope during open-wedge high tibial osteotomy (HTO) and to investigate whether its changes influenced the correction angle in frontal plane. We retrospectively reviewed 20 patients (26 knees) treated with open-wedge HTO. They were divided into the following two groups. Group A consisted of the knees whose opening gaps were fixed using a spacer plate having the trapezoidal block with a 2° posterior slope. In Group B, anterior and posterior opening gaps were fixed separately. The posterior tibial slope and the hip-knee-ankle angle were measured based on CT data. The relationship between the correction rate in frontal plane and the changes of posterior tibial slope was investigated. Increase in the posterior tibial slope was 2.1 ± 2.5° in Group A and 0.2 ± 1.2° in Group B, which showed a statistical difference (P = 0.02). The difference between the hip-knee-ankle angles before and after operation was 5.2 ± 2.3° in Group A and 5.5 ± 2.5° in Group B. The correction rate was statistically correlated with the changes of posterior tibial slope (R = -0.55, P = 0.003). To avoid increase in the posterior tibial slope, the trapezoidal block with a only 2° posterior slope in a spacer plate was not sufficient, and it was necessary to fix anterior and posterior gaps separately. The correction angle in frontal plane had a trade-off relationship with the changes in posterior tibial slope. Thus, we thought that increase in the posterior tibial slope might result in correction loss. Therapeutic study, Retrospective comparative study, Level III.

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

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. 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 36months (12-108), and median patient age at the time of surgery was 26years (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. All but one patient achieved radiographic healing and union at the osteotomy site at an average of 3months 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. 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. Therapeutic study, Level IV.

Control of Posterior Tibial Slope and Patellar Height in Open-Wedge Valgus High Tibial Osteotomy

Background: Valgus-producing open-wedge high tibial osteotomy is an established treatment for varus malalignment and medial osteoarthritis, with reproducible results in the frontal plane. However, an undesirable but often accepted increase in posterior tibial slope and decrease in patellar height are still routinely seen. Purpose: To evaluate the influence of valgus open-wedge high tibial osteotomy on posterior tibial slope and patellar height when special techniques are used to minimize unwanted changes. Study Design: Case series; Level of evidence, 4. Methods: Twenty-five patients, 3 women and 22 men (mean age, 40.2 years), underwent valgus open-wedge high tibial osteotomy. Several technical steps were taken to prevent an increase in posterior tibial slope during the osteotomy. To minimize patellar height changes, the tibial tuberosity was left on either the proximal or distal fragment, depending on the desired patellofemoral effect. The medial and lateral posterior slope was measured using the proximal posterior cortex as a reference; the patellar height was assessed with the Caton-Deschamps Index and compared on preoperative and postoperative radiographs. Results: No significant posterior tibial slope changes were observed. Patellar height increased with both types of tibial tuberosity osteotomy. With the proximal osteotomy, the Caton-Deschamps Index increased from 0.95 to 0.97; with the distal osteotomy, it increased from 0.89 to 0.95. The change was not significant with either osteotomy. The posterior tibial slope did not change on the medial side, measuring 4.2 preoperatively and postoperatively. The lateral slope decreased from 5.4 to 5.1. There was no correlation between the correction in the coronal plane and the changes in the sagittal plane. Conclusion: Open-wedge high tibial osteotomy can be performed without significant changes in patellar height or posterior tibial slope if specific intraoperative methods are used to prevent their occurrence. Analysis and control of sagittal changes in valgus open-wedge high tibial osteotomy should reduce the incidence of unwanted changes in patellar height and posterior tibial slope.

Effect of posterior tibial slope on knee biomechanics during functional activity

Treatment of medial compartment knee osteoarthritis with high tibial osteotomy can produce an unintended change in the slope of the tibial plateau in the sagittal plane. The effect of changing posterior tibial slope (PTS) on cruciate ligament forces has not been quantified for knee loading in activities of daily living. The purpose of this study was to determine how changes in PTS affect tibial shear force, anterior tibial translation (ATT), and knee-ligament loading during daily physical activity. We hypothesized that tibial shear force, ATT, and ACL force all increase as PTS increases. A previously validated computer model was used to calculate ATT, tibial shear force, and cruciate-ligament forces for the normal knee during three common load-bearing tasks: standing, squatting, and walking. The model calculations were repeated with PTS altered in 1° increments up to a maximum change in tibial slope of 10°. Tibial shear force and ATT increased as PTS was increased. For standing and walking, ACL force increased as tibial slope was increased; for squatting, PCL force decreased as tibial slope was increased. The effect of changing PTS on ACL force was greatest for walking. The true effect of changing tibial slope on knee-joint biomechanics may only be evident under physiologic loading conditions which include muscle forces.

The Effect of Plate Position and Size on Tibial Slope in High Tibial Osteotomy –A Cadaveric Study

Opening wedge high tibial osteotomies are performed for degenerative changes and varus. Opening wedge osteotomies can change proximal tibial slope in the sagittal plane, possibly imparting stability in the ACL-deficient knee. The aim of this study was to assess the effect of plate position and size on change in tibial slope. Eight cadaveric knees underwent opening wedge high tibial osteotomy with Puddu plates of each different size. Plates were placed anterior, central, and posterior for each size used. Lateral radiographs were obtained. Tibial slope was measured and compared with baseline slope. Tibial slope was affected by plate position (P < 0.05) and size (P < 0.001). Smaller, posterior plates had less effect on tibial slope. However, anterior and central plates increased tibial slope over all plate sizes (P < 0.05). This study found that tibial slope increases with opening wedge high tibial osteotomy. Larger corrections and anterior placement of the plate are associated with larger increases in slope.

Patellar Height and Posterior Tibial Slope after Open- and Closed-Wedge High Tibial Osteotomy

Background Valgus high tibial osteotomy (HTO) may be associated with changes in the patellar height and posterior tibial slope. Hypothesis Patellar height increases and posterior tibial slope decreases after closed-wedge HTO, whereas patellar height decreases and tibial slope increases after open-wedge osteotomy. Study Design Cohort study; Level of evidence, 3. Methods Lateral radiographs of 100 knees were assessed for patellar height (PH) (Insall-Salvati index [ISI], Caton-De Champ index [CDI], and Blackburne-Peel index [BPI]) as well as posterior tibial slope. Measurements were done before HTO (50 closed wedge [CW], 50 open wedge [OW]), direct postoperatively, and before removal of the hardware. Results In the CW group, all 3 PH indices were increased direct postoperatively and at removal of the hardware, with changes in CDI and BPI being significant (P < .05). The effect size (ES) for the direct postoperative PH increase was medium (ES = 0.48) according to CDI. In the OW group, all 3 indices showed a significant (P < .05) PH decrease direct postoperatively and at hardware removal. The ES for the direct postoperative PH decrease was large according to CDI (ES = 0.92) and BPI (ES = 0.80). There were no significant changes between the 2 follow-up measurements (P > .05) with a small ES each. Posterior tibial slope showed a significant (P < .05) decrease of 3.1° ± 3.4° after CW HTO and a significant (P < .05) increase of 2.1° ± 3.6° after OW HTO direct postoperatively. These changes did not change at the second follow-up. In CW HTO, the correlations between frontal plane correction and PH changes were moderate (CDI: r = .57; BPI: r = .64). In OW HTO, these correlations were weak (CDI: r = .44; BPI: r = .46). According to ISI, there was no correlation (CW: r = .11; OW: r = .16). There was no correlation between PH changes and slope changes (CDI) and no correlation between frontal plane HTO correction and slope changes in both CW and OW HTO. Conclusion The results confirm our hypothesis for PH and posterior tibial slope changes after valgus HTO. However, there is no strong correlation between PH changes and the degree of frontal plane HTO correction. The incidence of patella infera increases after OW HTO, whereas the incidence of patella alta increases after CW HTO. Therefore, we recommend performing CW HTO or OW HTO with the tuberosity left at the proximal tibia in cases of patellofemoral complaints or patella infera. Neither technique leads to patellar lowering. It should be borne in mind that PH and posterior tibial slope may have been altered before planning total knee replacement after HTO.

Patellar Height and Tibial Slope after Opening-Wedge Proximal Tibial Osteotomy

Background Further knee surgery after proximal tibial osteotomies has been reported to have a more difficult surgical exposure due to decreased patellar height after the osteotomy. Although a decrease in patellar height has been reported for closing-wedge proximal tibial osteotomies, it has not been widely verified among opening-wedge procedures. Hypothesis A significant decrease in patellar height would result after opening-wedge proximal tibial osteotomies and a postoperative change in tibial slope would also result, depending on the medial tibial plate position, which would affect patellar height. Study Design Case series; Level of evidence, 4. Methods Patients (n = 129) who underwent opening-wedge proximal tibial osteotomies (n = 130) were prospectively followed. Patellar height was calculated for preoperative lateral knee radiographs, and postoperatively at 2 weeks and 3 and 6 months. The Insall-Salvati, Blackburne-Peel, and Caton-Deschamps indices and a modified Miura and Kawamura index were used to calculate patellar height. Posterior tibial slope was also calculated for preoperative and 6-month postoperative knees. Results Coronal plane alignment changed significantly, from 24.6% to 55.2% of the tibial weightbearing axis. The overall decrease in patellar height for all patients was significant from preoperative assessment to the 2-week postoperative assessment and to both 3-month and 6-month follow-up with all 4 methods. The Insall-Salvati index decreased from 1.03 preoperatively to 0.99 at 2 weeks postoperatively, 0.97 at 3 months, and 0.95 at 6 months postoperatively. The Blackburne-Peel index decreased from 0.90 preoperatively to 0.75, 0.77, and 0.76, respectively, at each postoperative interval. The Caton-Deschamps index decreased from 0.98 preoperatively to 0.87, 0.86, and 0.84 at each postoperative measurement. The Miura-Kawamura index changed from 0.76 preoperatively to 0.61, 0.63, and 0.60 for each postoperative assessment. The average tibial slope significantly increased from 9.0° to 11.9° overall for all patients. In comparing the plate position, the tibial slope significantly increased from 8.8° preoperatively to 13.1° at 6 months postoperatively for anteromedially positioned plates and from 9.3° to 10.3° for posteromedially positioned plates. Conclusion Opening-wedge proximal tibial osteotomies decrease patellar height within the first 3 postoperative months. Shortening of the patellar tendon may affect future surgeries and needs to be evaluated in preoperative assessment. Moreover, a significant increase in tibial slope occurred, which may affect patellar height and future ligament reconstructions.

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 degrees +/- 0.92 degrees ). There was no significant difference for the mean tibial slope before and after surgery (9.2 degrees +/- 5.6 degrees vs. 9.1 degrees +/- 5.6 degrees , 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.

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 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 degrees ; on postoperative radiographs it was 11.7 +/- 5.7 degrees 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.

Evaluation of anatomic references for tibial sagittal alignment in total knee arthroplasty

The authors aimed to demonstrate the relationship between the sagittal mechanical axis of the tibia and other reference axes of the tibia and fibula in patients with advanced osteoarthritis of the knee joints, and then to identify a reliable landmark in order to minimize posterior tibial slope measurement errors. We evaluated 133 osteoarthritic knees with neutral or varus deformity in 64 female and 8 male patients. Axial computed tomographic images of whole tibiae including knee and ankle joints were obtained and reconstructed using 3-dimensional imaging software. Angles between the mechanical axis (MA), the tibial anatomical axis (TAA), the anterior tibial cortex (ATC) and the fibular shaft axis (FSA) were measured, and then medial and lateral tibial slope angles were measured using all axes. Mean angles between MA and the other anatomical reference lines (TAA, ATC and FSA) were 0.9, 2.2 and -2.1 degrees, respectively. The mean values of lateral tibial slopes with respect to MA, TAA, ATC and FSA were 8.7, 10, 12 and 7.3, respectively, and their intra- and inter-observer reliabilities were higher than those of medial tibial slopes. Although posterior tibial slope change markedly according to the reference axis used, the axes used in conventional TKA showed significant correlations with each other, and thus, may be used safely if differences with the mechanical axis are considered. Moreover, the lateral tibial slope might have advantages over the medial tibial slope in terms of restoration of the natural tibial slope.