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The purpose of this study was to determine if a horizontal cleavage lesion (HCL) of the posterior horn of the medial meniscus would result in changes to tibiofemoral contact mechanics, as measured by peak contact pressure and contact area, which can lead to cartilage degeneration. To study this, 10 cadaveric knees were tested in a rig where forces were applied (500 N Compression, 100 N shear, 2.5 Nm Torque) and the knee dynamically flexed from À5˚to 135˚, as peak contact pressure and contact area were recorded. After testing of the intact knee, a horizontal cleavage lesion was created arthroscopically and testing repeated. The Wilcoxon signed-rank test was used to determine if there were differences in peak contact pressure and contact area between the intact knee and that with the HCL. A statistically significant increase in peak contact pressure of 13%, on average, and a decrease in contact area of 6%, on average, was noted following the HCL. This suggests that a horizontal cleavage lesion will result in small but statistically significant changes in tibiofemoral contact mechanics which may lead to cartilage degeneration. Keywords: horizontal cleavage lesion; peak contact pressure; contact area; osteoarthritis; MRI The medial meniscus has been shown to aid in load distribution, bearing 60% of the load in the knee. [1][2][3] Several studies have shown that following a traumatic tear, such as a radial tear or posterior root tear, a decrease in contact area and an increase in peak contact pressure on the tibial cartilage can occur compared to the intact knee. [4][5][6][7] Similar to the changes in tibiofemoral contact mechanics following partial meniscectomy, these loading changes are believed to lead to the Fairbank changes that characterize osteoarthritis (OA). 8,9 However, it is not clear if degenerative tears also have such an effect on load distribution and thus contact mechanics. One type of degenerative tear is the horizontal cleavage lesion (HCL), which is a horizontal tear of the meniscus, predominantly occurring in the region of the posterior horn, separating the meniscus into a top and bottom flap. 10,11 It is believed to occur as a result of fatigue from shear forces on the meniscus, and therefore occurs predominantly in older patients. 10,12 Although originally believed to be benign and asymptomatic, the horizontal cleavage lesion has been shown to be associated with an increased incidence of osteoarthritis. 11,13 However, it is not clear if the HCL has a causal role in this relationship, resulting in changes in tibiofemoral contact mechanics which can lead to cartilage degeneration. Therefore, in this study, we sought to determine if an HCL of the posterior horn of the medial meniscus would result in changes in tibiofemoral contact mechanics, as measured by peak contact pressure and contact area, which can lead to cartilage degeneration.We hypothesized that an HCL of the posterior horn of the medial meniscus would result in an increase in peak contact pressure and a decrease in contact are...

Purpose The aim of this study was to describe the native trochlear orientation of non-arthritic knees in three planes and to quantify the relationship between trochlear and distal condylar anatomy across race and sex. Methods Computed tomography scans of 1578 femora were included in this study. The mediolateral position of the trochlear sulcus, the distal trochlear sulcus angle (DTSA) the medial sulcus angle (MSA) and the lateral sulcus angle (LSA) as well as the mechanical lateral distal femoral angle (mLDFA) were measured relative to a standard reference coordinate system. Multiple linear regression analyses were performed to account for potential confounding variables. Results The mediolateral position of the trochlear sulcus had minimal mean deviation of the sagittal femoral plane. The mean DTSA was 86.1° (SD 2.2°). Multilinear regression analysis found mLDFA, sex, and age all influence DTSA (p < 0.05), with mLDFA having by far the greatest influence (r2 = 0.55). The medial facet of the trochlear sulcus was found to be flat proximally and more prominent distally. The lateral facet was relatively uniform throughout the arc. Conclusion In non-arthritic knees, due to a strong positive correlation between the DTSA and the mLDFA, the trochlear sulcus is consistently orientated in the sagittal femoral plane regardless of distal condylar anatomy. Minor deviations from the sagittal plane occur in a lateral direction in the middle part and in a medial direction at the proximal and distal part of the trochlea. These findings have relevance regarding the biomimetic design of total knee implants.

Background: Improved understanding of the morphological characteristics of knees with osteoarthritis (OA) and various deformities can enable personalized implant positioning and balancing in total knee arthroplasty in an effort to continue improving clinical outcomes and optimizing procedural value. Therefore, the purpose of this study was to outline morphological differences in the medial and lateral distal femur and proximal tibia associated with varus and valgus deformities in knee OA.Methods: A large computed tomography (CT) database was used to identify 1,158 knees, which were divided into normal and osteoarthritic groups; the latter was further divided on the basis of deformity into neutral, varus, and valgus subgroups. Morphological measurements included the non-weight-bearing hip-knee-ankle angle (nwHKA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), rotation of the posterior condylar axis (PCA) relative to the surgical transepicondylar axis (sTEA), ratio of medial to lateral posterior condylar offset, ratio of medial to lateral condylar radius, medial posterior slope (MPS), lateral posterior slope (LPS), medial coronal slope (MCS), and lateral coronal slope (LCS).Results: Compared with the normal group, the OA group was in overall varus (nwHKA, 22.2°± 5.0°compared with 20.2°± 2.4°) and had a significantly smaller MPS (8.4°± 4.0°compared with 9.2°± 4.0°), larger LPS (9.2°± 3.6°c ompared with 7.2°± 3.3°), and smaller MCS (82.1°± 4.3°compared with 83.9°± 3.3°). Differences among the OA subgroups were also observed for the MCS and LCS. Compared with the normal group, the sTEA of the OA group was less externally rotated relative to the PCA (0.3°± 1.5°compared with 1.2°± 1.9°), and both the condylar offset ratio (1.01 ± 0.06 compared with 1.04 ± 0.07) and the condylar radius ratio (0.98 ± 0.07 compared with 1.03 ± 0.07) were smaller. Only the condylar radius ratio showed differences among the OA subgroups, with valgus deformity associated with a larger ratio.Conclusions: An analysis of CT scans of 965 healthy and 193 osteoarthritic knees revealed significant differences in PCA, condylar offset, and condylar radius as well as tibial slope in both the sagittal and coronal planes.Clinical Relevance: There is a strong need to evolve toward a more personalized treatment for osteoarthritic knees that utilizes implants and technology to help tailor total knee arthroplasty on the basis of the patient's morphologic characteristics. Over the past 2 decades, annual primary total knee arthroplasty (TKA) utilization has increased exponentially, resulting in >4 million patients with knee implants in the United States 1 . However, despite surgical and implant advancements, multiple studies demonstrate that up to 20% of patients continue to be dissatisfied following TKA [2][3][4][5][6][7][8] . Malalignment continues to influence implant failure rates and result in poorer clinical outcomes 9,10 . Substantial research continues to be dedicated to identifying the morphological factors that...

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