Medial Tibial Articular Surfaces Research Articles

Customized-individually-made origin® implants in total knee arthroplasty allow a reliable solution for accurate reproduction of planned implant positioning.

To evaluate the accuracy and reproducibility of a patient-specific, customized individually made (CIM) total knee replacement (TKR) using the ORIGIN® prosthesis. This was a prospective study conducted at a University Hospital from January 15, 2019, to April 30, 2021. The study included patients planned for an ORIGIN® CIM TKR procedure. Exclusion criteria included revision surgery, severe deformity, stiffness, or laxity. Evaluations were carried out using computed tomography scans performed 8 weeks preoperatively and 6 weeks postoperatively. The primary outcome measurements were the preoperative, planned, and postoperative CT scan alignment measurements including the Hip-Knee-Ankle (HKA) angle, mechanical Medial Distal Femoral articular surface Angle (mMDFA, distal alpha angle), Posterior Distal femoral articular surface angle (PDFA, posterior alpha angle), mechanical Medial Proximal Tibial articular surface Angle (mMPTA, beta angle) and posterior proximal tibial angle (PPTA). Secondary outcomes included the accuracy of implant positioning with percentage of outliers at 2° and 3° RESULTS: The study encompassed 51 knees from 50 patients with mean age of 68.1 (SD = 8.89). The overall HKA angle deviated by -0.93° [95% CI: -1.45; -0.43], and the PDFA angle by -0.61° [95% CI: -1.07; -0.15], while the mMPTA exceeded planned values by 1.00° [95% CI: 0.57; 1.43]. The 3° outliers rate ranged from 3.9% for the mMPTA to 7.8% for the HKA alignment, with no outliers in mMDFA and PPTA. Similarly, the 2° outliers rate ranged from 15.7% for both the PDFA angle and mMPTA to 19.6% for the HKA alignment. The Bland-Altman plots further emphasized the precision of planned and post-operative angles across all measurements. The CIM TKR showed high accuracy and reproducibility, closely matching preoperative planning. The weakest accuracy at 3°-outliers is in the reproduction of the HKA alignment at 92.2% (range for all angle: 92.2-100%). Similarly, the weakest accuracy at 2°-outliers is in the reproduction of the HKA alignment at 80.4% (range for all angles: 80.4-92.2%).

Total knee arthroplasty: posterior tibial slope influences the size but not the rotational alignment of the tibial component.

The reasons leading to rotational tibial malalignment in total knee arthroplasties (TKAs) remain unclear. A previous cadaver study has shown an increase in internal rotation of the anatomical tibial axis (ATA) after the tibial cut. This study investigates the influence of tibial slope on the ATA and the size of the resected tibial surface. CT scans of 20 cadaver knees were orientated in a standardized coordinate system and used to determine the position of the centres of rotation of the medial and lateral tibial articular surfaces and, hence, of the ATA, after a virtual resection of 6mm with 0°, 3.5°, 7° and 10° slope, respectively. Furthermore, at each slope, the radii of the medial and lateral tibial articular surfaces after resection were calculated. Compared to resection of 6mm with 0° slope, a slope of 3.5° resulted in a mean external rotation of the ATA of 0.9° (SD, 1.5°; P = 0.025). A slope of 7° resulted in a mean external rotation of the ATA of 1.0° (SD 2.0°; P = 0.030) and a slope of 10° had no influence on the rotation of the ATA. The radii of the medial and lateral articular surfaces of the cut tibiae were larger than those of the uncut tibia (P < 0.001). Differences in the posterior tibial slope should not contribute to a rotational malalignment when using the ATA to align the prosthetic tibial plateau. Although statistically significant, the change in ATA with increasing slope was negligible.

Meniscal Replacement With a Silk Fibroin Scaffold Reduces Contact Stresses in the Human Knee.

ABSTRACTThe aim of the current study was to verify if a previously developed silk fibroin scaffold for meniscal replacement is able to restore the physiological distribution of contact pressure (CP) over the articulating surfaces in the human knee joint, thereby reducing peak loads occurring after partial meniscectomy. The pressure distribution on the medial tibial articular surface of seven human cadaveric knee joints was analysed under continuous flexion–extension movements and under physiological loads up to 2,500 N at different flexion angles. Contact area (CA), maximum tibiofemoral CP, maximum pressure under the meniscus and the pressure distribution were analysed for the intact meniscus, after partial meniscectomy as well as after partial medial meniscal replacement using the silk fibroin scaffold. Implantation of the silk fibroin scaffold considerably improved tibiofemoral contact mechanics after partial medial meniscectomy. While the reduced CA after meniscectomy was not fully restored by the silk fibroin scaffold, clinically relevant peak pressures on the articular cartilage surface occurring after partial meniscectomy were significantly reduced. Nevertheless, at high flexion angles static testing demonstrated that normal pressure distribution comparable to the intact meniscus could not be fully achieved. The current study demonstrates that the silk fibroin implant possesses attributes that significantly improve tibiofemoral CPs within the knee joint following partial meniscectomy. However, the failure to fully recapitulate the CAs and pressures observed in the intact meniscus, particularly at high flexion angles, indicates that the implant's biomechanical properties may require further improvement to completely restore tibiofemoral contact mechanics. © 2019 The Authors. Journal of Orthopaedic Research ® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2583–2592, 2019

Native rotational knee kinematics is restored after lateral UKA but not after medial UKA.

The aim of this study was to compare the intraoperative kinematics of medial and lateral unicompartmental knee arthroplasty (UKA) with those of the native knee using a navigation system. Six fresh-frozen cadaveric knees were included in the study. Medial UKA was performed in all right knees and lateral UKA was performed in all left knees. All UKA procedures were performed with a computerised navigation system. The tibial internal rotation angle and coronal alignment of the mechanical axis during passive knee flexion were assessed as rotational and varus/valgus kinematics before and after surgery using the navigation system. The rotation angles of the tibia in the early flexion phase of medial UKA were significantly larger than those of native knees (p = 0.008at minimum knee flexion, p = 0.008at 0° knee flexion). The rotational kinematics of lateral UKA was similar to those of the native knees throughout knee flexion. There were no significant differences in varus/valgus kinematics between native and UKA knees. The rotational kinematics of the native knee was not restored after medial UKA but was preserved after lateral UKA. There were no significant differences in the varus/valgus kinematics after either medial or lateral UKA when compared with those of the native knees. Thus, the geometry of the medial tibial articular surface is a determinant of the ability to restore the rotational kinematics of the native knee. Surgeons and implant designers should be aware that the anatomical medial articular geometry is an important factor in restoration of the native knee kinematics after knee arthroplasty.

What Preoperative Radiographic Parameters Are Associated With Increased Medial Release in Total Knee Arthroplasty?

BackgroundPreoperative varus deformity of the knee is a common malalignment in patients undergoing primary total knee arthroplasty (TKA). We are unaware of any studies that have correlated how various preoperative radiographic parameters can predict the amount of medial releases performed to achieve optimal coronal alignment and ligamentous balance. MethodsA retrospective review was performed on 67 patients who required at least a medial tibial reduction osteotomy (MTRO) during primary TKA to achieve coronal balance. This patient population was matched 1:1 to another cohort of TKA patients by age, gender, and body mass index who did not require an MTRO. A radiographic evaluation was used to compare the 2 cohorts. ResultsPreoperatively, the MTRO cohort was noted to have significantly increased varus tibiofemoral (86.12° vs 93.43°), tibial articular surface (85.79° vs 87.54°), and medial tibial articular surface angles (75.22° vs 85.34°) compared to the control cohort. The MTRO cohort had 3.13 mm of medial tibial offset and 9.06 mm of lateral joint space opening and the control cohort had 0.09 mm and 4.07 mm, respectively. The medial tibial articular surface angle and lateral joint space widening were statistically associated with the MTRO cohort. The final tibiofemoral angle in the MTRO cohort was 92.43° and was 93.40° in the control cohort. ConclusionThe MTRO cohort was noted to have several preoperative radiographic parameters that were significantly different than the control cohort. However, the medial tibial articular surface angle and lateral joint space widening were the only radiographic parameters that were statistically associated with requiring an MTRO.

The potential effect of anatomic relationship between the femur and the tibia on medial meniscus tears

The anatomic and the kinematical relationships between the femur and the tibia have been previously examined in both normal and diseased knees. However, less attention has been directed to the effect of these relationships on the meniscal diseases. Therefore, we aimed to investigate the impact of femorotibial incongruence on both lateral and medial meniscal tears. A total of 100 images obtained from MRI of 100 patients (39 males and 61 females) were included in the study. Diameters of the medial and the lateral femoral condyles, thicknesses of the menisci, and diameters of the medial and the lateral tibial articular surfaces were measured. The medial meniscus tear was detected in 40 (40%) patients. However, no lateral meniscus tear was found. Significant relationships were found between the diameters of the posterior medial femoral condyle and the medial tibial superior articular surface and between the diameters of the posterior lateral femoral condyle and the lateral tibial superior articular surface. The mean values for the diameter of the medial condyle of the femur, the lateral condyle of the femur, the medial superior articular surface of the tibia, and the lateral superior articular surface of the tibia were found to be significantly higher in cases with meniscus tear compared to cases without meniscus tear. However, no significant difference was present regarding the thicknesses of the medial and the lateral menisci. A positive relationship between the diameter of the posterior medial femoral condyle and the tibial medial superior articular surface was found in cases with (n=40) (r (2)=0.208, p=0.003) and without tear (n=60) (r (2)=0.182, p=0.001). In addition, a significant positive relationship was found between the diameter of the posterior medial femoral condyle and the medial tibial superior articular surface in cases with and without tear. The impact of femorotibial incongruence on the medial meniscus tear is important for the understanding of the lesions.

Increasing lateral tibial slope: is there an association with articular cartilage changes in the knee?

The geometry of the lateral tibial slope (LTS) plays an important role in the overall biomechanics of the knee. Through this study, we aim to assess the impact of LTS on cartilage degeneration in the knee. A retrospective analysis of 93 knee MRI scans (1.5 T or 3 T) for patients aged 20-45 years with no history of trauma or knee surgery, and absence of internal derangement. The LTS was calculated using the circle method. Chondropathy was graded from 0 (normal) to 3 (severe). Linear regression analysis was used for statistical analysis (p < 0.05). In our cohort of patients, a statistically significant association was seen between increasing LTS and worsening cartilage degenerative changes in the medial patellar articular surface and the lateral tibial articular surface (p < 0.05). There was no statistically significant association between increasing LTS and worsening chondropathy of the lateral patellar, medial trochlea, lateral trochlea, medial femoral, lateral femoral, and medial tibial articular surfaces. Our results show a statistically significant association between increasing LTS and worsening cartilage degenerative changes in the medial patella and the lateral tibial plateau. We speculate that increased LTS may result in increased femoral glide over the lateral tibial plateau with subsequent increased external rotation of the femur predisposing to patellofemoral articular changes. Future arthroscopic studies are needed to further confirm our findings.

Topographic Analysis of the Glenoid and Proximal Medial Tibial Articular Surfaces – A Search for the Ideal Match for Glenohumeral Resurfacing

This study describes a novel topographic computational model to quantify the topographic match between the medial tibial and glenoid articular surfaces, the findings of which suggest that the medial tibial articular surface provides near anatomic match to the glenoid for the Purposes of glenoid resurfacing in young patients with end-stage arthritis.

Topographic Analysis of the Glenoid and Proximal Medial Tibial Articular Surfaces

Background: Current knowledge is lacking concerning the appropriate site of osteochondral allograft harvest to match glenoid shape for the purposes of glenoid resurfacing. This has led to difficulty with adequate restoration of the geometry of the glenoid with currently available techniques. Hypothesis: The medial tibial plateau will provide a suitable osteochondral harvest site because of its concavity and anatomic similarity to the glenoid. Study Design: Descriptive laboratory study. Methods: Computed tomography (CT) was performed on 4 cadaveric proximal tibias and 4 scapulae, allowing for 16 glenoid-tibial comparative combinations. Three-dimensional CT models were created and exported into point-cloud models. A local coordinate map of the glenoid and medial tibial plateau articular surfaces was created. Two zones of the medial tibial articular surface (anterior and posterior) were quantified. The glenoid articular surface was defined as a best-fit circle of the glenoid articular surface maintaining a 2-mm bony rim. This surface was virtually placed on a point on the tibial articular surface in 3D space. The tibial surface was segmented, and its 3D surface orientation was determined with respect to its surface. The 3D orientation of the glenoid surface was reoriented so that the direction of the glenoid surface matched that of the tibial surface. The least distances between the point-clouds on the glenoid and tibial surfaces were calculated. The glenoid surface was rotated 360° in 1° increments, and the mean least distance was determined at each rotating angle. Results: When the centroid of the glenoid surface was placed on the medial tibial articular surface, it covered approximately two-thirds of the anterior or posterior tibial surfaces. Overall, the mean least distance difference in articular congruity of all 16 glenoid–medial tibial surface combinations was 0.74 mm (standard deviation, ±0.13 mm). The mean least distance difference of the anterior and posterior two-thirds of the medial tibial articular surface was 0.72 mm (±0.13 mm) and 0.76 mm (±0.16 mm), respectively. There was no significant difference between the anterior and posterior two-thirds of the tibia with regard to topographic match of the glenoid (P = .187). Conclusion: The findings suggest that the medial tibial articular surface provides an appropriate anatomic match to the glenoid articular surface. Both the anterior and posterior two-thirds of the medial tibial articular surface are potential sites for osteochondral graft harvest. Clinical Relevance: This method can be applied to future studies evaluating the ideal sites of graft harvest to treat zonal glenoid bone wear and/or loss.

Topographic Analysis of the Glenoid and Proximal Medial Tibial Articular Surfaces - A Search for the Ideal Match for Glenoid Resurfacing

Objectives:Current knowledge of the appropriate site of osteochondral allograft harvest to match glenoid morphology for the purposes of glenoid resurfacing is lacking. This has led to difficulty with adequately restoring the geometry of the glenoid using current available techniques. The purpose of this study was to quantify the articular surface topography of the glenoid and medial tibial plateau via 3-dimensional (3D) modeling to determine if the medial tibial articular surface provides an anatomic topographic match to the articular surface of the glenoid. We hypothesized that the medial tibial plateau will provide a suitable osteochondral harvest site due to its concavity and anatomic similarity to the glenoid.Methods:Computed tomography (CT) was performed on four cadaveric proximal tibias and four scapulae, allowing for 16 glenoid-tibial comparative combinations. 3D CT models were created and exported into point cloud models. A local coordinate map of the glenoid and medial tibial plateau articular surfaces was created. Two zones of the medial tibial articular surface (anterior and posterior) were quantified. The glenoid articular surface was defined as a best-fit circle of the glenoid articular surface maintaining a 2mm bony rim (Figure 1). This surface was virtually placed on a point on the tibial articular surface in 3D space. The tibial surface was segmented and its 3D surface orientation was determined by an eigenvector in the direction of its surface. 3D orientation of the glenoid surface was reoriented so that an eigenvector in the direction of the glenoid surface matched that of the tibial surface (Figure 2). The least distances between the point-clouds on the glenoid and tibial surfaces were calculated. The glenoid surface was rotated 360 degrees around the eigenvector with one degree increments and the mean least distance was determined at each rotating angle. A non-parametric wilcoxon signed rank statistical analysis was performed to compare the findings between the anterior and posterior aspects of the medial tibial articular surface with respect to the glenoid.Results:When the centroid of the glenoid surface was placed on the medial tibial articular surface, it covered approximately two-thirds of the anterior or posterior tibial surfaces. Overall, the mean least distance difference in articular congruity of all 16 glenoid-medial tibial surface combinations was 0.74mm (Std. Deviation ± 0.13). The mean least distance difference of the anterior and posterior two-thirds of the medial tibial articular surface was 0.72mm (± 0.13) and 0.76mm (± 0.16), respectively. There was no significant difference between and the anterior and posterior two-thirds of the tibia with regard to topographic match of the glenoid (p=0.187).Conclusion:We describe a novel methodology to quantify the topography of the tibial and glenoid articular surfaces. The findings suggest that the medial tibial articular surface provides an appropriate anatomic match to the glenoid articular surface. To the authors knowledge, this is the first time this relationship has been quantified. Both the anterior and posterior two-thirds of the medial tibial articular surface can serve as potential sites for osteochondral graft harvest. In addition, this methodology can be applied to future studies evaluating the ideal sites of graft harvest to treat zonal glenoid bone wear and/or loss.

A spatial model of the knee for the preoperative planning of knee surgery.

A model on the spatial mechanical behaviour of the passive knee is presented. The femoral articular surfaces were represented by generalized, sagittally elliptical, toroidal surfaces. The medial and lateral tibial articular surfaces were represented by a dished spherical surface and the lower hemihyperbolic region of a torus respectively. Anatomical articular cartilage, knee ligaments and the posterior capsule were represented by spring-like deformable elements with non-linear load versus deflection characteristics. All the forces that act on the femur relative to the tibia were represented by three orthogonal forces and three associated moments. Spatial, articulation-dependent femorotibial kinematic constraint equations of the passive knee were formulated in an analytically explicit manner, based on the natural coordinates of the articular surfaces. The constraint equations were solved algebraically in closed form. Equations were derived that describe spatial femoro-tibial motion, ligament length, ligament strain, ligament-based elastic potential energy and the quasi-static equilibrium of the passive knee. Software was written, simulations on the motion characteristics and load versus deflection characteristics of the knee were carried out and graphical results were presented. The simulation of planar flexion/extension was almost spontaneous. The time taken to simulate spatial six-degree-of-freedom femoro-tibial motion was less than 2.5 min. The models were found to be capable of representing real-life passive knees to a high degree of satisfaction. It has been demonstrated that the models can provide knee surgeons with additional information on major aspects of the preoperative planning of knee surgery. The models can be used to enhance the preoperative planning of ligament reconstruction, articular surfaces related surgery, osteotomy and patellar tendon transfer surgery.

How three methods for fixing a medial meniscal autograft affect tibial contact mechanics.

We evaluated three methods for fixing a medial meniscal autograft to determine which method restored tibial contact mechanics closest to normal. The contact mechanics (maximum pressure, mean pressure, contact area, and location of the center of maximum pressure) of the medial tibial articular surface were determined using pressure-sensitive film while knee specimens were loaded in compression to 1000 N at 0 degree, 15 degrees, 30 degrees, and 45 degrees of flexion. Pressure was measured for the intact knee, the knee after meniscectomy, and the knee with the original meniscus removed and reimplanted as an autograft using three different fixation methods. The contact mechanics of the autograft reinserted with bone plug fixation were closest to normal; however, the maximum pressure was significantly greater than in the intact knee. Adding peripheral sutures neither improved nor worsened the contact mechanics. Fixation with sutures only did not restore normal contact mechanics. We concluded that medial meniscal transplantation requires anatomic fixation of bone plugs attached to the anterior and posterior horns to restore contact mechanics closest to normal. Fixation of the meniscal horns with sutures alone cannot be recommended.