Slope In Total Knee Arthroplasty Research Articles

CHANGES OF TIBIAL SLOPE AFTER CRUCIATE RETAINING–TOTAL KNEE REPLACEMENT AND THEIR FUNCTIONAL EFFECT OUTCOME

Background 
 Total knee arthroplasty has been regarded as the primary surgical procedure for relieving severe pain in the last stage of degenerative arthritis and experiencing better functional outcomes. many previous studies have been described the effect of posterior tibial slope on functional outcome, but many debates exist.
 Objectives 
 To find changes of posterior tibial slope in total knee arthroplasty.
 Patients and Methods
 Our study includes 50 patients (50 knees) who underwent Cruciate Retaining-Total knee Replacement (CR-TKR) from 10 January 2018 to Nov2019. Posterior tibial slope (PTS) was measured on lateral x-ray. According to the oxford knee score, the functional outcome and the posterior tibial slope were measured preoperatively and postoperatively for each patient.
 Results
 Fifty patients underwent CR-TKR. Preoperative PTS and oxford knee scores were 11.7 and 11.72, respectively. Postoperative PTS and oxford knee scores were 9.3 and 39.64, respectively. We divided into Group A: PTS up to 9(24 cases) and Group B PTS more than 9 (26). We analyzed the relationship between PTS and functional outcome according to the oxford knee score. 
 Conclusion
 Clinical improvements were noticed in both patient groups after CR-TKR.

Posterior Tibial Slope in Computer-Navigated Total Knee Arthroplasty: The Transmalleolar Sagittal Axis Underestimates Slope Compared to Traditional Intramedullary Axis.

Tibial slope in total knee arthroplasty (TKA) impacts knee flexion, balance, and ligament strain. Implants were initially designed with tibial slope recommendations based on the intramedullary axis. However, technology-assisted TKA, such as robotics or navigation, determines slope from the ankle-knee axis connecting the center of the transmalleolar line to the proximal exit point of the tibial shaft axis. We sought to quantify the difference in tibial slope between the traditional intramedullary and transmalleolar sagittal tibial axes. We retrospectively identified 40 TKAs with preoperative computed tomography scans. We reconstructed the 3-dimensional geometry of the tibia and fibula and determined the intramedullary axis as the best fit cylinder to the tibial shaft. We defined the transmalleolar axis according to accepted industry standards. We measured the angular difference between both axes in the sagittal plane. The transmalleolar axis was radiographically posterior to the intramedullary axis in 39 knees. Utilizing the transmalleolar axis to set posterior tibial slope would reduce the posterior tibial slope by a mean of 1.9° ± 1.3° compared to the intramedullary axis. Furthermore, the posterior slope would be reduced between 0° and 2° in 24 knees (60%), between 2° and 4° in 10 knees (25%), and more than 4° in 5 knees (13%). Tibial components implanted with technology assistance referencing the transmalleolar axis to set posterior slope will show an average of 1.9° less posterior slope when measured in sagittal plain radiographs, potentially concerning for knee kinematics.

A sagittal reference line using the preoperative radiograph in total knee arthroplasty.

We evaluated the accuracy of a sagittal alignment of tibial component in total knee arthroplasty (TKA) with the sagittal reference line using the preoperative radiograph. We evaluated 151 patients who underwent primary TKA with posterior cruciate substituting type implant. For 75 patients, the sagittal reference line using preoperative radiograph (group A) was used, while for 76 patients the sagittal reference using intraoperative fibular shaft line (group B) was used. The parallel line (line S) to the anatomical axis of the tibia in the lateral plain radiograph was used as the sagittal reference. The distance from line S to proximal tibia cutting area and to skin surface 20 cm distal to the cutting area was measured in preoperative radiographs. Next, the distance to the extramedullary guide rod was applied intraoperatively, reflecting the results. The intraoperative fibular shaft line was determined using the connecting line between the tip of fibular head and the lateral malleolus. The postoperative tibial component slope angle and the difference to the target slope angle were compared. The difference to the target angle was 1.8 ± 1.3° in group A, whereas the difference was 2.5 ± 1.4° in group B (p = 0.04). The patients with difference within 3° to the target angle were 78.7% in group A and 61.8% in group B (p = 0.024). The sagittal reference line using the preoperative lateral radiograph was helpful as a reference guide for the tibial slope in TKA.

The usefulness of planning using a preoperative lateral leg image to determine accurate posterior tibial slope in total knee arthroplasty

ObjectiveSagittal alignment of the tibia following total knee arthroplasty (TKA) can affect various factors, such as durability, range of motion, stability, and even kinematics. The aim of the present study was to investigate whether taking plain preoperative lateral leg X-ray images to plan the posterior tibial slope can give an insert placement with more accurate sagittal alignment. MethodsA total of 100 patients who underwent total TKA with posterior-stabilized prostheses. were divided into a group of 50 cases in which the posterior tibial slope was determined intra-operatively with only the fibular axis as the landmark, and a group of 50 cases in which determination of the posterior tibial slope was planned preoperatively with reference to preoperative lateral leg images. For the posterior slope, tibial cutting was performed with the posterior slope built into the bone cutting guide of the insert as the target. The angle of the fibular axis and the posterior slope of the tibial insert were measured on the postoperative lateral leg X-ray image, and the difference from the target angle was examined in the two groups. ResultsIn the group in which only the fibular axis was used for reference, the mean deviation from the target was 3.96°, while in the group in which planning was carried out preoperatively using lateral leg X-ray images, the mean deviation was 1.59° (P < 0.05). ConclusionDrawing up a preoperative plan using lateral leg X-ray images gives a useful landmark at low cost for accurate determination of TKA posterior tibial slope.

Influence of Increased Posterior Tibial Slope in Total Knee Arthroplasty on Knee Joint Biomechanics: A Computational Simulation Study

BackgroundThe reconstructed posterior tibial slope (PTS) plays a significant role in restoring knee kinematics in cruciate-retaining-total knee arthroplasty (TKA). A few studies have reported the effect of the PTS on biomechanics. MethodsThis study investigates the effect of the PTS on tibiofemoral (TF) kinematics, patellofemoral (PF) contact stress, and forces at the quadriceps, posterior cruciate ligament (PCL) and collateral ligament after cruciate-retaining-TKA using computer simulations. The simulation for the validated TKA finite element model was performed under deep knee bend condition. All analyses were repeated from −3° to 15° PTS in increments of 3°. ResultsThe kinematics on the TF joint translated increasingly posteriorly when the PTS increased. Medial and lateral contact points translated in posterior direction in extension and flexion as PTS increased. The maximum contact stress on the PF joint and quadriceps, and collateral ligament force decreased when the PTS increased. An implantation of the tibial plate with increased PTS reduced the PCL load. Physiologic insert movement led to an increasingly posterior position of the femur and reduced quadriceps force especially for knee flexion angles above high flexion (120°) when compared to TKA with a decreased slope of the tibial base plate. ConclusionAn increase in the PTS increased medial and lateral movements without paradoxical motion. However, an excessive PTS indicated progressive loosening of the TF joint gap due to a reduction in collateral ligament tension during flexion.

Anterior referencing of tibial slope in total knee arthroplasty considerably influences knee kinematics: a musculoskeletal simulation study

PurposeIn total knee arthroplasty (TKA), the posterior tibial slope is not always reconstructed correctly, and the knee ligaments may become too tight in flexion. To release a tight flexion gap, surgeons can increase the posterior tibial slope using two surgical resection techniques: the anterior tibial cortex (ACR) or the centre of tibial plateau (CPR) referencing. It is not known how this choice affects the knee laxity and function during activities of daily living. The aim of this study was to investigate the effect of tibial slope on knee laxity, kinematics and forces during a squatting activity using computer simulation techniques. We hypothesised that the effects depend on the referencing technique utilised.MethodsA validated musculoskeletal model of TKA was used. Knee laxity tests were simulated in flexion and extension. Then, a squat motion was simulated to calculate: movement of the tibiofemoral joint (TFJ) contact points and patello-femoral joint (PFJ) contact force. All analyses were repeated with more anterior (−3°), neutral (0°), and more posterior tibial slope (+3°, +6°, +9°), and with two referencing techniques (ACR, CPR).ResultsKnee laxities increased dramatically with more posterior slope with the ACR technique (up to 400%), both in flexion and in extension. The CPR technique, instead, had much smaller effects (up to 42% variations). During squatting, more slope with the ACR technique resulted in larger movements of the TFJ contact point. The PFJ contact force decreased considerably with more slope with the CPR technique (12% body weight reduction every 3° more posterior slope), thanks to the preservation of the patellar height and quadriceps–femur load sharing.ConclusionACR technique alters considerably the knee laxity, both in flexion and extensions, and surgeons should be cautious about its use. More slope with CPR technique induces more favourable TFJ kinematics and loading of the knee extensor apparatus and does not substantially alter knee laxity. Preferably, the tibial slope resection should be pre-planned thoroughly and performed using CPR technique as accurately as possible. Surgeons can directly translate the results of this study into the clinical practice.

The distance from the extramedullary cutting guide rod to the skin surface as a reference guide for the tibial slope in total knee arthroplasty

BackgroundAlthough sagittal tibial alignment in total knee arthroplasty (TKA) is important, no landmarks exist to achieve a reproducible slope. The purpose of this study was to evaluate the clinical usefulness of the distance from the guide rod to the skin surface for the tibial slope in TKA. MethodsComputer simulation studies were performed on 100 consecutive knees scheduled for TKA. The angle between the line connecting the most anterior point of the predicted tibial cut surface and the skin surface 20cm distal to the predicted cut surface (Line S) and the mechanical axis (MA) of the tibia in the sagittal plane was measured. ResultsThe mean (±SD) absolute angle difference between the Line S and the MA was 0.9°±0.7°. The Line S was almost parallel to the MA in the sagittal plane (95% and 99% within two degrees and three degrees of deviation from MA, respectively). ConclusionThe guide rod orientation is a surrogate for the tibial cut slope because the targeted posterior slope is usually built into the cutting block and ensuring the rod is parallel to the MA in the sagittal plane is recommended. Therefore the distance between the skin surface and the rod can be a useful guide for the tibial slope. Level of evidenceII

The accuracy of two different extra-medullary tibial cutting guides for posterior tibial slope in total knee arthroplasty.

This study aims to evaluate the effectiveness of two different external tibial cutting guides with and without a spike anchoring to the intercondylar eminentia to achieve a desired posterior tibial slope. Between January 2008 and December 2011, 120 posterior cruciate ligament protecting total knee arthroplasty (TKA) surgeries of 83 patients in which two different external tibial cutting guides used were included. Fifty-nine knees were included into the spiked and 61 knees were included into the spikeless cutting guide group. Posterior tibial slope angles were measured using the postoperative X-rays. There was no significant difference between two groups in terms of age, sex, and body mass indexes (p<0.05). While the mean postoperative slope angle was 2.66°±2.001°(range 0°-7°) in spiked group, it was 2.46°±2.277° (range 0°-7°) in spikeless group. Both systems had identical accuracy, indicating a low rate. The comparison of variances of two groups showed that both cutting guides had similar precision (p=0.234). There was no effect of body mass index on the results in both groups. Although different extra-medullary tibial cutting guides with and without a spike can reproducibly impart a desired posterior tibial slope in TKA, we concluded that a spiked guide was considered user-friendly.

Clinical Results Associated with Changes of Posterior Tibial Slope in Total Knee Arthroplasty

PurposeThe purpose of this retrospective study is to investigate the effect of posterior tibial slope (PTS) on clinical results in total knee replacement arthroplasty (TKA).Materials and MethodsWe analyzed 801 knees in 768 patients who underwent TKA using a cruciate-retaining prosthesis for osteoarthritis from July 2003 to July 2009. PTS was measured on simple X-ray films and patients were divided into 5 groups, according to the change in PTS that was calculated by subtracting the preoperative from the postoperative PTS: group 1, >3°; group 2, 3° to 1°; group 3, 1° to -1°; group 4, -1° to -3°; and group 5, <-3°. We analyzed the correlations between the change in PTS and clinical results, such as Knee Society knee score, Knee Society functional score, Feller patella score, Kujala score, visual analog scale score, range of motion, and complications.ResultsThere was no statistically significant intergroup difference; however, Feller patella score and Kujala score were significantly different in groups 2 and 3. There were no complications, such as progressive loosening of implants, fractures of polyethylene inserts and wears.ConclusionsClinically meaningful improvement was observed in all patients after TKA. Groups 2 and 3 (3° to -1°) showed significant improvement compared to the other groups.

Does computer-assisted surgery improve postoperative leg alignment and implant positioning following total knee arthroplasty? A meta-analysis of randomized controlled trials?

Computer-assisted surgery has been proposed as a technique to improve implant alignment during total knee arthroplasty (TKA). However, there is still a debate over the accuracy of placing the femoral and tibial components using computer-assisted systems in TKA. The aim of this study is to establish whether computer-assisted surgery leads to superior mechanical leg axis and implant positioning than conventional technique in patients with primary TKA. Major electronic databases were systematically searched to identify relevant studies without language restriction. A meta-analysis of 41 randomized controlled trials (RCTs) or quasi-RCTs was performed in a random effects model. A subgroup analysis was conducted by type of navigation system to explore the clinical heterogeneity between these trials. The following radiographic parameters were used to compare computer-assisted surgery with conventional technique: (1) mechanical leg axis, (2) femoral component coronal alignment, (3) tibial component coronal alignment, (4) femoral component sagittal alignment, and (5) tibial component sagittal alignment. For the mechanical leg axis and coronal positioning of femoral and tibial components, there are statistically significant reductions in the number of patients with malalignment in the CAS group if the outlier cutoff value is ±3 or 2° in the coronal and sagittal planes, respectively. Subgroup analysis demonstrates that CT-free navigation systems provide better alignment than conventional techniques in the coronal and sagittal alignment of femoral components within ±3 and 2°. If the outlier cutoff value for the tibial sagittal alignment is ±2°, the outlier percentages are higher in the CT-free navigation group than in the conventional group. However, there was no significant difference in the tibial sagittal alignment at ±3°. Computer-assisted surgery does improve mechanical leg axis and component orientation in TKAs. However, high-quality RCTs are necessary to determine whether surgeons could use computer-assisted techniques to achieve a targeted tibial slope in TKA. Therapeutic study (Systematic review of Level I/II studies), Level II.

Anatomical References to Assess the Posterior Tibial Slope in Total Knee Arthroplasty: A Comparison of 5 Anatomical Axes

There has been no consensus on an ideal anatomical reference to determine the posterior slope of tibia plateau. Posterior slope of the medial tibia plateau was measured with reference to a proposed mechanical axis (MA) and 5clinically relevant anatomical references in 90 osteoarthritic knees of 66 female patients undergoing total knee arthroplasty. The MA was defined as the line connecting the midpoints of the medial tibia plateau and the tibial plafond, and 5anatomical references included the anterior cortical line of tibia, anatomical axis of proximal and central tibia, posterior cortical line of proximal tibia, and fibular shaft axis. The average posterior slope was 10.6° with reference to the MA, and the amount of posterior slope varied widely among the patients and depending on the anatomical reference used to measure. This study indicates that the anatomical reference used to measure the posterior slope should be identified in studies where posterior slope is used to evaluate the sagittal alignment of total knee arthroplasty.

The influence of tibial slope on maximal flexion after total knee arthroplasty

Many surgeons believe that increasing the tibial slope in total knee arthroplasty (TKA) is beneficial with regard to maximal postoperative flexion. Review of the clinical literature, however, does not confirm this hypothesis, neither does it give an answer to the question of how much flexion gain can be expected per degree extra tibial slope. The purpose of this study was, therefore, to evaluate and quantify the influence of tibial slope on maximal postoperative flexion in contemporary posterior cruciate ligament (PCL)-retaining TKA. Twenty-one cadaver simulations of a standard PCL-retaining TKA were studied while reproducing identical deep flexion femorotibial kinematics as documented by three-dimensional computer-aided videofluoroscopy from patients with well-functioning TKAs of the same design. In each knee the tibial component was consecutively implanted with 0 degrees posterior slope, 4 degrees posterior slope, and 7 degrees posterior slope. Maximal flexion was recorded for each configuration. Average maximal flexion at 0 degrees tibial slope was 104 degrees, and increased significantly to 112 degrees when the same knees were implanted with 4 degrees tibial slope. Increasing the slope further to 7 degrees again significantly improved average maximal flexion to 120 degrees. When postoperative radiographic tibial slope was compared to maximal flexion, an average gain of 1.7 degrees flexion for every degree extra tibial slope was noted. Increasing the tibial slope in PCL-retaining TKA does indeed improve maximal flexion before tibial insert impingement occurs against the femoral bone. The surgeon can expect an average gain of 1.7 degrees flexion for every degree extra tibial slope.