Sagittal Tibial Slope Research Articles

Radiographic Investigation of Coronal Plane and Patellar Height and Changes Following Tibial Deflection Osteotomy for Correction of Tibial Slope in Combination With ACL Reconstruction

Background: A tibial deflexion osteotomy (TDO) is performed to decrease the sagittal tibial slope to reduce the relative risk of anterior cruciate ligament (ACL) reconstruction (ACLR) graft failure. Given that coronal plane osteotomies can cause consequential changes in the sagittal plane to patellar height and tibial slope, potential changes to coronal plane alignment and patellar height can result after a sagittal plane osteotomy. Purpose: To compare preoperative and postoperative coronal plane alignment after TDO, as well as to analyze the effect of the osteotomy on patellar height. Study Design: Case series; Level of evidence, 4. Methods: This study was conducted on a consecutive series of patients with primary and revision ACLR with concomitant TDO between 2011 and 2022. Inclusion criteria were 1-stage autograft ACLR combined with supratubercular TDO with pre- and 3 months postoperative radiographs of sufficient quality. Indications for TDO were anterior instability requiring ACL revision surgery and a posterior tibial slope (PTS) >9° or a PTS >14° in the primary ACL surgery patients. Anteroposterior and lateral knee radiographs were reviewed, and the medial proximal tibial angle (MPTA), PTS, Caton-Deschamps index (CDI), and modified Insall-Salvati ratio were measured directly from the radiographs by 2 independent reviewers. Results: A total of 68 patients were included in this study. Pre- and postoperative radiographs were performed 1 month before and 3 months after surgery, respectively. There was a significant increase in the mean MPTA of 0.95° varus (SD, 2.1°; range, increase of 4.23° valgus to increase of 7.74° varus; P < .01), a decreased PTS of 8.86° (SD, 3.03°; P < .01), and an increased CDI of 0.08 (range, decrease of 0.27 to increase of 0.64) (P < .01; SD, 0.17) in patients undergoing TDO. Insall-Salvati ratio measurements showed no difference. There was good intra- and interobserver reliability, with intraclass correlation coefficients of 0.97 and 0.91 for MPTA, 0.97 and 0.87 for PTS, 0.87 and 0.93 for CDI, and 0.88 and 0.76 the Insall-Salvati ratio. Conclusion: This study, the largest series on TDO for ACLR, demonstrates that the TDO can be performed safely without large changes to coronal alignment or patellar height. The tibial slope was reduced by a mean of 8.86° (range, 2.3°-11.5°; P < .01). The TDO produces a small statistically significant change to coronal alignment, inducing a mean increased varus of <1° and an increased patellar height of 0.1 CDI. Therefore, TDO can be performed safely without dramatic changes to coronal alignment or patellar height, this study highlights technical aspects to minimize iatrogenic varus.

Excessive Sagittal Slope of the Tibia Component during Kinematic Alignment-Safety and Functionality at a Minimum 2-Year Follow-Up.

The aim of this study was to assess the safety and functional outcomes of excessive sagittal alignment in the unrestricted kinematic alignment technique for total knee arthroplasty (TKA). A retrospective, single-center study was conducted between 2018 and 2020, including patients undergoing primary TKA with a minimum 2-year follow-up. EOS imaging conducted before and after surgery was reviewed for overall alignment, and a number of measurements were taken, including sagittal tibial slope and other tibia and femur component positioning. Patients were interviewed and asked to fill out several questionnaires including a visual analog scale, the Oxford Knee Score, and the Knee Injury and Osteoarthritis Outcome Score. Overall, 225 patients (66.7%) had a sagittal tibial slope angle above 5° (excessive) and 112 (33.3%) patients had an angle under 5° (moderate). A significant improvement in pain and function scores was observed in both groups following the surgery (p < 0.001). There were no significant differences between the moderate and excessive groups in the average VAS, OKS or the various subtypes of the KOOS score. However, there was a slight but significant difference in the number of patients achieving MCID in KOOS symptoms. There were no cases of early failure or loosening. Unrestricted KA and the excessive sagittal alignment of the tibial component seem to be reliable and safe in terms of restoring daily function and alleviating pain after a minimum of 2 years following the surgery.

Limb and component alignment after total knee arthroplasty comparing 28 consecutive iAssist and 28 conventional TKAs: A prospective study

BackgroundThe objective of this study was to assess limb and component alignment after total knee arthroplasty (TKA) on long leg X-rays and to compare the use of iAssist, an accelerometric based computer-assisted device (CAD), with conventional jigs. MethodsWe prospectively recruited 56 consecutive patients undergoing primary unilateral TKA by a single surgeon into this study. In the first 28 patients iAssist navigation system was utilized and in the following 28 conventional jigs were used. The groups were comparable with regard to age, sex distribution, body mass index and preoperative hip–knee–ankle (HKA) angle. Our aim was to restore neutral coronal alignment and a five degree tibial slope. ResultsThe mean postoperative mechanical axis was 179.4° in the CAD group and 180.1° in the conventional group (P = 0.187). There were five TKAs deviating more than three degrees from neutral (18.5%) in the conventional group and none in the CAD group (P = 0.051). The mean femoral mechanical-condyles-angle was significantly closer (P < 0.001) to our target of 90° in the conventional group but contained more outliers (P = 0.67). The sagittal tibial slope was closer (P = 0.047) to our target of 85° in CAD-navigated TKAs with fewer outliers (P < 0.0001). The Oxford Knee Score showed comparable (P = 0.271) and good clinical outcome in both groups. The mean operation time was significantly longer in the CAD group (P < 0.001). ConclusionsThis study shows that the use of iAssist accelerometric CAD facilitates comparable good leg alignment after TKA in the frontal plane and more accurate tibial slope with fewer outliers in the sagittal plane compared with a conventional technique. Our operation time was longer with CAD.

Tibiofemoral Kinematics During Compressive Loading of the ACL-Intact and ACL-Sectioned Knee: Roles of Tibial Slope, Medial Eminence Volume, and Anterior Laxity.

Tibial geometry and knee laxity have been identified as risk factors for both noncontact anterior cruciate ligament (ACL) rupture and instability in the setting of ACL insufficiency via clinical studies; yet, their biomechanical relationships with tibiofemoral kinematics during compressive loading are less well understood. The purpose of this study was to identify the relative contributions of sagittal tibial slope, medial tibial eminence volume, and anterior knee laxity to tibiofemoral kinematics with axial compression in both ACL-intact and ACL-sectioned cadaveric knees. Computed tomography (CT) data were collected from 13 human cadaveric knees (mean donor age, 45 ± 11 years; 8 male). Validated algorithms were used to calculate the sagittal slope of the medial and of the lateral tibial plateau as well as volume of the medial tibial eminence. Specimens were then mounted to a robotic manipulator. For both intact and ACL-sectioned conditions, the robot compressed the knee from 10 to 300 N at 15° of flexion; the net anterior tibial translation of the medial and lateral compartments and internal tibial rotation were recorded. Simple and multiple linear regressions were performed to identify correlations between kinematic outcomes and (1) osseous geometric parameters and (2) anterior laxity during a simulated Lachman test. In ACL-intact knees, anterior tibial translation of each compartment was positively correlated with the corresponding sagittal slope, and internal tibial rotation was positively correlated with the lateral sagittal slope and the sagittal slope differential (p ≤ 0.044). In ACL-sectioned knees, anterior tibial translation of the medial compartment was positively associated with medial sagittal slope as well as a combination of medial tibial eminence volume and anterior laxity; internal tibial rotation was inversely correlated with anterior knee laxity (p < 0.05). Under compressive loading, sagittal slope of the medial and of the lateral tibial plateau was predictive of kinematics with the ACL intact, while medial tibial eminence volume and anterior laxity were predictive of kinematics with the ACL sectioned. The relationships between tibial osseous morphology, anterior laxity, and knee kinematics under compression may help explain heightened risk of ACL injury and might predict knee instability after ACL rupture.

Handheld Navigation Device and Patient-Specific Cutting Guides Result in Similar Coronal Alignment for Primary Total Knee Arthroplasty: a Retrospective Matched Cohort Study.

Proper alignment of total knee arthroplasty (TKA) is essential for TKA function and may reduce the risk of aseptic failure. Technologies that prevent malalignment may reduce the risk of revision surgery. The purpose of this study was to compare two competing TKA systems that purport improved alignment: patient-specific instrumentation (PSI), and a handheld portable navigation device (NAV). After IRB approval, 49 consecutive PSI TKAs (40 patients) were matched based on preoperative characteristics to 49 NAV TKAs (40 patients) performed by a single surgeon. A blinded observer measured alignment on digital radiographs. Operating room records were reviewed for procedure times. Two-tailed paired sample t tests and McNemar's test were used as appropriate. Alpha level was 0.05 for all tests. Preoperative cohort characteristics were not different. Mean postoperative long-leg mechanical alignment was within ±1° of neutral for both groups, although statistically different (p = 0.026). There were no other significant differences in coronal alignment. PSI exhibited significantly greater posterior tibial slope (4.4°) compared to NAV (2.7°) (p = 0.004); PSI resulted in significantly more outliers (>6°; p = 0.004). Procedure time for unilateral TKAs was lower for PSI (74.4min) compared to that for NAV (80.6min; p = 0.023). NAV and PSI technologies provided excellent coronal plane alignment. NAV was better for sagittal tibial slope, while PSI procedure times were shorter for unilateral TKA. The impact of these technologies on patient-reported outcomes and TKA survivorship is controversial and should be the focus of future research.

An Evaluation of the Association Between Radiographic Intercondylar Notch Narrowing and Anterior Cruciate Ligament Injury in Men: The Notch Angle Is a Better Parameter Than Notch Width

To evaluate the association of anterior cruciate ligament (ACL) injuries with the intercondylar notch angle and notch width in male patients. The secondary purpose was to evaluate the association of these injuries with other novel morphologic parameters. Male patients undergoing primary ACL reconstruction between 2010 and 2013 for injury through noncontact mechanisms with preoperative magnetic resonance imaging were compared with an age-matched control group of male patients (patients who underwent knee operations other than ACL reconstruction) regarding the following magnetic resonance imaging-assessed parameters: intercondylar notch angle, width, and depth; condylar width; medial/lateral condylar widths; medial/lateral posterior tibial plateau slopes; anterior sagittal tibial slope (corresponding to the level of the tibial ACL footprint); coronal tibial slope; and angle between the Blumensaat line and anterior tibial slope. In both the coronal and axial planes, patients with ACL injury had a significantly lower intercondylar notch angle (P < .001 and P= .008, respectively) than the control group, but there were no significant between-group differences for intercondylar notch width (P= .9 and P= .97, respectively). In the sagittal plane, patients with ACL injury had significantly higher medial (P < .001) and lateral (P= .02) posterior tibial slopes, a significantly lower anterior tibial slope (P= .01), and a significantly higher angle between the Blumensaat line and anterior tibial slope (P= .02) than the control group. Narrowing of the intercondylar notch may be associated with ACL injury in male patients. However, the intercondylar notch angle may be a better parameter to evaluate notch narrowing and its potential association with ACL injuries compared with the notch width. The association between the angle formed by the Blumensaat line and anterior tibial slope and ACL injuries in male patients needs more investigation. This study further suggests that increased posterior tibial slope may be associated with ACL injury in male patients. Level III, case-control study.

Does Open Wedge Proximal Tibial Osteotomy Really Affect Tibial Slope and Patellar Height?

Objectives:Open wedge proximal tibial osteotomy has gained popularity over recent years. This technique has several advantages over lateral closed wedge osteotomy, like lack of any need for fibular osteotomy and freedom from peroneal nerve complications, easier and more precise correction, no limb shortening and easier access for an eventual total knee arthroplasty. However it was been shown that open wedge osteotomy may reduce patellar height and increase sagittal tibial slope which can cause patellofemoral problems. The aim of the study was to evaluate the alterations in the angle of posterior slope of the tibia and the degree of patellar height following medial opening wedge proximal tibial osteotomy in our patients.Methods:26 females and 7 males, with a mean age of 48, who underwent medial opening wedge proximal tibial osteotomy were included in the study. In all cases, the preoperative measured varus angle was overcorrected to between 5-8° valgus. The posterior slope of the tibia was determined by the proximal tibial anatomical axis and patellar height was measured retrospectively by the Caton index on the pre- and postoperative radiograms at the end of the second month.Results:Preoperatively, on the standing orthoroentgenograms, the mean mechanical axis deviation was 12,36° (8-20) and the mean posterior tibial slope in the sagittal view was 16,24° (10-23). The mean postoperative tibial slope was 17,85° (6-25). Using paired samples test, this increase was statistically significant (p=0.049). Preoperative mean Caton index was 1,35 (1,01-1,92) and the postoperative average was 1,73 (1,11-2,76). There was also a statistical significant increase between the pre-and postoperative values (p<0.001) with paired samples test. There was a positive correlation between preoperative mechanical axis deviation and postoperative slope angle (p=0,014) but there was no correlation between preoperative mechanical axis deviation and postoperative patellar height.Conclusion:In conclusion, tibial slope and patellar height are strongly affected by open wedge high tibial osteotomy and this might have an adverse effect on an eventual knee arthroplasty.

Correlation between posterior offset of femoral condyles and sagittal slope of the tibial plateau

The aim of this study was to address, in normal knees, the variability of posterior offset of femoral condyles and tibial slope, and the presence of any correlation between the two that might be needed to achieve an adequate joint motion in flexion. Magnetic resonance images of normal knees of 80 subjects, 45 males and 35 females, with a mean age of 38.9 years, were analysed. Measurements were performed by two independent observers using an imaging visualization software. The tibial slope averaged 8 and 7.7 °, on the medial and lateral sides, respectively (P = 0.2); the mean posterior offset of femoral condyles was 27.4 and 25.2 mm on the two sides, respectively (P = 0.0001). The variation coefficient of the condylar offset and tibial slope was 11.5 and 38%, respectively. In the medial compartment, a significant correlation was found between the femoral condylar offset and the tibial slope, while the same was not observed in the lateral compartment of the knee. Magnetic resonance imaging allows the assessment of tibial slope and femoral condylar offset in the medial and lateral side separately, taking into account any difference between the two compartments. The sagittal tibial slope exhibits a greater variability compared with the posterior offset of femoral condyles. The correlation found, in the medial compartment, between the tibial slope and femoral condylar offset suggests that the reconstitution of the proper morphology of the posterior part of the knee joint may be necessary to obtain a full range of motion in flexion after total knee replacement.

The accuracy of intramedullary tibial guide of sagittal alignment of PCL-substituting total knee arthroplasty

Experimental and clinical studies on the accuracy of the intramedullary alignment method have produced different results, and few have addressed accuracy in the sagittal plane. Reported deviations are not only attributable to the alignment method but also to radiological errors. The purpose of this study was to evaluate the accuracy of the intramedullary alignment method in the sagittal plane using computed tomography (CT) and 3-dimensional imaging software. Thirty-one TKAs were performed using an intramedullary alignment method involving the insertion of a long 8-mm diameter rod into the medullary canal to the distal metaphysis of the tibia. All alignment instruments were set to achieve an ideal varus/valgus angle of 0° in the coronal plane and a tibial slope of 0° in the sagittal plane. The accuracy of the intramedullary alignment system was assessed by measuring the coronal tibial component angle and sagittal tibial slope angles, i.e., angles between the tibial anatomical axis and the tangent to the medial and lateral tibial plateau or the cut-surface. The mean coronal tibial component angle was 88.5°±1.2° and the mean tibial component slope in the sagittal plane was 1.6°±1.2° without anterior slope. Our intramedullary tibial alignment method, which involves passing an 8-mm diameter long rod through the tibial shaft isthmus, showed good accuracy (less than 3 degrees of variation and no anterior slope) in the sagittal plane in neutral or varus knees.

The Role of the Oblique Popliteal Ligament and Other Structures in Preventing Knee Hyperextension

Background Ligament restraints to terminal knee extension are poorly understood. Hypotheses (1) As with other motions of the knee, genu recurvatum is limited primarily by a named, identifiable structure. (2) As the largest static structure of the posterior knee, the oblique popliteal ligament is uniquely suited to act as a checkrein to knee hyperextension. Study Design Descriptive laboratory study. Methods Twenty fresh-frozen human knees were divided into 3 groups for a ligament sectioning study. Extension moments of 14 and 27 N·m were applied before and after sectioning of each ligament, and motion changes were recorded. In group 1, the oblique popliteal ligament was sectioned first, followed by the fabellofibular ligament, ligament of Wrisberg, anterior cruciate ligament, posterolateral structures, and posterior cruciate ligament. In group 2, the order was altered to section the anterior cruciate ligament first; no other changes were made. Similarly, the cutting order for group 3 was altered to section the posterior cruciate ligament first. The sagittal tibial slope of each specimen was documented off a lateral radiograph. Results The greatest increase in knee hyperextension was observed after sectioning the oblique popliteal ligament. This was independent of cutting order, consistent across groups, and statistically significant. In all groups, the increase in knee hyperextension after sectioning the oblique popliteal ligament approached or exceeded the increases seen after sectioning the anterior and posterior cruciate ligaments combined. Overall, less knee hyperextension was seen in knees with increased posterior tibial slope. Conclusion The oblique popliteal ligament was found to be the primary ligamentous restraint to knee hyperextension. Clinical Relevance Further studies are needed to determine if surgical repair or reconstruction of the oblique popliteal ligament can restore normal motion limits in patients with symptomatic genu recurvatum. Patients with decreased posterior tibial slope would have increased recurvatum with posterior structure injury, which increases the likelihood of increased symptoms in this population.

Open Wedge High Tibial Osteotomy: A Roentgenographic Comparison of a Horizontal and an Oblique Osteotomy on Patellar Height and Sagittal Tibial Slope (SS-62)

Medial opening wedge (OW) high tibial osteotomy (HTO) preserves bone stock while having to only perform one cut, with the advantage of intra-operative adjustment to the desired correction. However, several studies showed that conventional supratubercle horizontal OW is associated with decreasing patellar height and increasing the sagittal tibial slope; both of which can also potentially affect future conversion to a TKR. We hypothesized that performing an oblique osteotomy at the level or distal to the patella tendon insertion could decrease the osteotomy's effects on lowering the patella and increasing the sagittal tibial slope. Hence, the purpose of this study is to evaluate the radiographic effects of a horizontal osteotomy made proximal to the patellar tendon insertion versus on oblique osteotomy made at the level or distal to the patellar tendon insertion on the shift in coronal weight bearing line, sagittal tibial slope and patellar height. A retrospective review of all open wedge HTO cases done by the senior author from January 1998 to August 2005 was performed. Patients were excluded if the indication for surgery was instability or if they had simultaneous ligament repair. Two consecutive cohorts are compared in this study. Initially, the surgeon performed 22 HTO with a horizontal cut proximal to the patellar tendon insertion and a subsequent 19 knees had an HTO with a more distal oblique cut made which would cross at the level or occasionally, distal to, the patella tendon insertion.. The HTO was then fixed open with the appropriate size first generation non-locking Puddu(r) plate (Arthrex, Naples, Fl, USA) (Figure 2). In both groups, the Puudu(r) plate was placed as posteriorly as possible to minimize the increase in sagittal tibial slope. Either autogenous tri-cortical iliac crest bone graft or femoral head allograft and bone substitute were inserted in the osteotomy in all but one patient which had an opening less then 7.5 mm. The patellar height as measured by Blackburne and Peel ratio was decreased in the horizontal group from 0.85 ± 0.16 to 0.67 ± 0.12 post-operatively signifying a lowering of the patella (Table 2). The oblique group trended toward a change in patellar height as the ratio only decreased by 0.05 from a pre-operative value of 0.89 ± 0.09 to 84 ± .13 (p=0.07). The sagittal tibial slope increased following a horizontal HTO from 7.7 ± 4.6o to 10.7 ± 3.8o; this change was statistically significant (p<0.001) In the oblique group however, the slope was not significantly increased: 6.5 ± 4.0o pre-operatively to 7.0 ± 4.1o post-operatively (p=0.90). The more distal oblique osteotomy did not statistically affect the patellar height or the sagittal tibial slope while still allowing a similar coronal correction to the proximal horizontal group. Additionally, the more distal oblique osteotomy has the advantage of a technically easier exposure being distal to the periarticular capsule and allowing easier access to the posterior aspect of tibia for neurovascular protection. Caution should be exercised not to osteotomize too distally into lateral cortical bone to avoid instability and early loss of correction.

Open Wedge High Tibial Osteotomy

Background In patients with unicompartmental medial knee arthritis, medial opening wedge high tibial osteotomy is used to shift the mechanical weightbearing line laterally to reduce pain and improve function. There have been concerns that opening wedge high tibial osteotomy is associated with a reduction of patellar height and increase in the sagittal posterior tibial slope, both of which can adversely affect the final result. Hypothesis A more distal oblique osteotomy at the level of insertion of the patellar tendon should decrease these effects when compared with a horizontal osteotomy made proximal to the patellar tendon insertion. Study Design Cohort study; Level of evidence, 3. Methods Review of 22 horizontal and 19 oblique high tibial osteotomies with a mean follow-up of 4.2 ± 1.8 years (mean ± SD) was performed. Anatomic tibiofemoral angle, mechanical weightbearing line, medial coronal tibial plateau angle, patellar height (Blackburne and Peel ratio), and sagittal tibial slope were measured. Results In both groups, the weightbearing line was equally shifted toward the center of the plateau. In the horizontal group, the Blackburne and Peel ratio decreased from 0.85 ± 0.16 to 0.67 ± 0.12, and the sagittal tibial slope was increased from 7.7° ± 4.6° to 10.7° ± 3.8° (P < .001). In comparison, the oblique group did not show any significant postoperative changes for these 2 parameters. In the oblique group, 2 patients sustained loss of correction and early failure when the osteotomy remained below the metaphyseal flare on the lateral cortex. Conclusion The oblique osteotomy group showed more normalized postoperative sagittal tibial slope and patellar height. Caution should be exercised not to osteotomize too distally.

Opening Wedge Tibial Osteotomy: The 3-Triangle Method to Correct Axial Alignment and Tibial Slope

Background Although a change in tibial slope may occur during a medial opening wedge osteotomy, calculations have not been defined to address this problem. The authors investigated geometric factors important to correct axial alignment and tibial slope during osteotomy. Purpose To calculate, through 3-dimensional analysis of the proximal tibia, how the angle of the opening wedge along the anteromedial tibial cortex influences the tibial slope (sagittal plane) and valgus correction (coronal plane) during osteotomy, and to analyze the different radiographic methods reported in the literature to measure medial and lateral tibial slope. The authors postulated that differences in reported normal values of tibial slope in the sagittal plane were technique dependent. Study Design Descriptive laboratory study Methods The proximal anteromedial tibial cortex obliquity on magnetic resonance imaging was measured in 35 knees. Serial computed tomography images of the proximal tibia were digitized, allowing a series of virtual opening wedge osteotomies to be performed. Algebraic calculations defined the effect of an opening wedge osteotomy on the anteromedial tibial cortex opening wedge angle, sagittal tibial slope angle, and coronal valgus alignment. Results The anteromedial tibial cortex oblique angle at the medial osteotomy site was 45°± 6° and determined, along with the degrees of valgus correction, the degrees of the opening wedge angle in the oblique plane. The anterior osteotomy gap at the tibial tubercle was generally one half of the posteromedial gap to maintain the normal sagittal tibial slope. Every millimeter of gap error at the tibial tubercle resulted in approximately 2° of change in the tibial slope. The width of the buttress plate along the anteromedial tibial cortex was 2 to 3 mm less than the computed coronal valgus posteromedial osteotomy gap to achieve tibiofemoral valgus correction. Conclusions A series of measurements preoperatively and intraoperatively are required to obtain the desired correction of tibial slope and valgus alignment.