An acquired plica-induced notch in the medial femoral condyle in a patient with medial patellar plica syndrome: a case report.

BACKGROUND: An inflamed and thickened medial patellar plica (MPP) caused by repeated mechanical irritation from trauma or overuse leads to impingement between the anterior medial femoral condyle and the medial articular facet of the patella and produces pain or clicking, which is known as MPP syndrome. In patients with MPP syndrome, cartilage damage may occur depending on the shape of the MPP and the duration of the impingement. CASE PRESENTATION: Preoperative magnetic resonance imaging in a 17-year-old male patient with MPP syndrome showed a hypertrophic MPP along with an abnormal notch in the articular surface of the medial femoral condyle. We considered that the impinged hypertrophic plica between the anterior medial femoral condyle and the medial articular facet of the patella resulted in cartilage damage on the articular surface of the medial femoral condyle. However, during arthroscopic surgery, we found that the cartilage of the notch, which was located beneath the MPP, was completely intact. We concluded that this abnormal notch had developed gradually in the MPP without cartilage damage. CONCLUSIONS: Surgeons should be mindful that acquired plica-induced notches in the articular surface of the medial femoral condyle can present in patients with MPP syndrome.

Chondrogenic differentiation of human ASCs by stiffness control in 3D fibrin hydrogel.

In cell-based tissue engineering, fibrin hydrogel can be utilized to produce scaffolds to treat cartilage. However, the optimal fibrin formulation for cartilage regeneration has not yet been studied. This study aimed to find the optimal fibrin formulation and determine whether fibrin optimized with human adipose-derived stem cells (hASCs) increased the in-vivo chondrogenic potential. To find the optimal formulation, fibrin constructs were divided into twelve groups with different ratios of fibrinogen (10, 20, 30, and 50 mg/mL) to thrombin (10, 50, and 100 IU/mL), following which the physical and biological properties of cell-free and cell-embedded fibrin were investigated. The results from cell-free hydrogels showed that increases in the concentrations of fibrinogen and thrombin corresponded to increases in stiffness and initial weight. Moreover, hydrogel degradation was inhibited in high-concentration formulations. In cell-embedded fibrin constructs, the variation of gel formulation did not affect cell viability. However, cell behavior depended on the gel formulation. hASCs within high-concentration fibrinogen formulation maintained a round morphology similar to natural chondrocytes. Variations in thrombin concentration had a lesser effect on cell morphology. In terms of in-vivo cartilage formation, the formulation with 30 mg/mL fibrinogen and 100 IU/mL thrombin showed the highest cartilage formation, as evidenced through collagen type II alpha 1 chain (COL2) and safranin-O, 4 weeks after implantation. The results may lead to optimally designed 3D bio-scaffolds in which we can control both cell survival and chondrogenic potential for cartilage tissue engineering. Scaffolds made with the optimal fibrin formulation can be applied to develop cell therapies with mesenchymal stem cells to treat osteoarthritis.

Morphologic difference and size mismatch in the medial and lateral tibial condyles exist with respect to gender for unicompartmental knee arthroplasty in the Korean population.

PURPOSE: The purpose of this study was to characterize the geometry of the proximal tibia in both genders in the Korean population. Anthropometric data on the medial and lateral tibial condyles of the osteoarthritic knees of 149 males and 814 females were obtained using three-dimensional magnetic resonance imaging. METHODS: In the medial and lateral proximal tibial condyles, the anteroposterior (AP) dimension, widest dimension (WD) at defined points, and condylar aspect ratio were evaluated. These measurements were compared with similar dimensions of the tibial components from five commonly used unicompartmental knee arthroplasty (UKA) designs in Korea. RESULTS: Both the AP dimension and WD in the medial and lateral tibial condyles of the male patients were significantly greater than those of the female patients (P < 0.05). In addition, the AP dimension and WD were greater in the medial than in the lateral tibial condyle (P < 0.05). There was WD overhang in three and two prostheses in the medial and lateral tibial condyles, respectively. A decrease in the condylar aspect ratio with an increasing AP dimension was found in the medial and lateral tibial condyles for both the male and female patients. CONCLUSIONS: Smaller medial and lateral tibial condylar dimensions are more frequent in Korean women than in Korean men. This study highlights the finding that conventional UKA designs lead to size mismatch in the Korean population and may indicate an important guideline on proper gender-specific UKA tibial prostheses with different WD/AP dimension aspect ratios. In addition, this study suggests that the shape of the medial tibial plateau is different to that of the lateral plateau, which can lead to a mediolateral overhang for medial UKA in an attempt to optimize the AP coverage. LEVEL OF EVIDENCE: III.

Femoral trochlear morphology is associated with anterior cruciate ligament injury in skeletally immature patients.

PURPOSE: Knee joint morphology is a known contributor to anterior cruciate ligament (ACL) injury, and the shape of the distal femur condyle is one of the associated factors. However, the relationship between femoral trochlear morphology and ACL injury is unclear, especially in pediatric patients. Therefore, the present study aimed to evaluate the effect of femoral trochlear morphology on ACL injury in pediatric patients and investigate the possibility of gender differences. METHODS: In total, 116 skeletally immature children aged 3-18 years with primary ACL injuries were matched with a control group of 116 skeletally immature children. Lateral trochlear inclination, trochlear facet asymmetry, trochlear depth, and sulcus angle were evaluated using magnetic resonance imaging (MRI). Differences between patient groups and gender were investigated. Receiver-operating characteristic (ROC) curves were constructed to obtain the sensitivity and specificity of all parameters. RESULTS: A significant difference was observed in the sulcus angle and trochlear inclination between the ACL injury and control groups (p < 0.05). No significant difference was observed between the ACL injury and control groups with respect to the anatomic patellar instability risk factors. All parameters showed an area under the curve of 0.6 in the ROC analysis, indicative of failure of the diagnostic test. CONCLUSIONS: There was a significant association between femoral trochlear morphology and increased risk of ACL injury in pediatric patients. No gender difference was found except in the trochlear depth. It was showed that the difference in trochlear morphology should be considered between normal children and pediatric patients with ACL injury to increase the awareness regarding ACL injuries. LEVEL OF EVIDENCE: III.

Gender differences exist in rotational anatomy of the distal femur in osteoarthritic knees using MRI.

PURPOSE: Optimal rotational alignment of the femoral component is essential for total knee arthroplasty (TKA). The femoral transepicondylar axis (TEA), Whiteside's line (WSL), and posterior condylar axis (PCA) are various intra-operative references that can be used to determine femoral rotation, and each has advantages and disadvantages. This study aimed to define the rotational anatomy of the distal femur and investigate its relationship with gender in osteoarthritic knees. METHODS: Magnetic resonance imaging (MRI) was obtained from 1522 patients (1298 females and 224 males) with end-stage knee osteoarthritis prior to TKA. MRI was constructed into three-dimensional models. The angles between the TEA and WSL, WSL and PCA, and TEA and PCA were calculated for each patient. In addition, gender differences in femoral rotation were evaluated. RESULTS: The PCA was 2.2° ± 1.0° internally rotated relative to the TEA. WSL was 1.2° ± 2.8° externally rotated relative to the TEA. The WSL to TEA relationship exhibited greater variability than the PCA to TEA relationship. PCA was more internally rotated and WSL was more externally rotated relative to TEA in female group than male group. Based on the standard reference rules of 3° external rotation from the PCA that has been conventionally used, 15.7% of patients showed external rotation lower 1° or greater than 5° external rotation from the PCA. In the mean external rotation of the TEA from the PCA (2.2°) from this population; however, the percentage of patients showing ± 2° from their TEA dropped to 5.1% of patients. CONCLUSION: Gender difference and variability exist in distal femoral rotational anatomy. These data can be useful in consideration of femoral anatomy variability and gender difference. The same cutting angle may lead to malrotation of the femoral component. LEVEL OF EVIDENCE: Consecutive patients, level III.

Implantation of mesenchymal stem cells in combination with allogenic cartilage improves cartilage regeneration and clinical outcomes in patients with concomitant high tibial osteotomy.

PURPOSE: This study aimed to compare the clinical, radiological, and second-look arthroscopic outcomes of implanting mesenchymal stem cells (MSCs) alone and together with allogenic cartilage in patients treated with concomitant high tibial oteotomy (HTO) for varus knee osteoarthritis. METHODS: Eighty patients treated with cartilage repair procedures and concomitant HTO were prospectively randomized into two groups: MSC implantation (MSC group), and MSC implantation with allogenic cartilage (MSC-AC group). Clinical outcomes were evaluated using the Lysholm Score and the Knee Injury and Osteoarthritis Outcome Score (KOOS) at preoperative and every follow-up visit. Radiological outcomes were evaluated by measuring the femorotibial angle and posterior tibial slope. During second-look arthroscopy, cartilage regeneration was evaluated according to the Kanamiya grade. RESULTS: Clinical outcomes at the second-look arthroscopy (mean 12.5 months [MSC group] and 12.4 months [MSC-AC group]) improved significantly in both groups (P < 0.001 for all). Clinical outcomes from the second-look arthroscopy to the final follow-up (mean 27.3 months [MSC group] and 27.8 months [MSC-AC group]) improved further only in the MSC-AC group (P < 0.05 for all). Overall, the Kanamiya grades, which were significantly correlated with clinical outcomes, were significantly higher in the MSC-AC group than in the MSC group. Radiological outcomes at final follow-up revealed improved knee joint alignments relative to preoperative conditions but without significant correlation between clinical outcomes and Kanamiya grade in either group (n.s. for all). CONCLUSION: Implantation of MSCs with allogenic cartilage is superior to implantation of MSCs alone in cartilage regeneration accompanied with better clinical outcomes. LEVEL OF EVIDENCE: Therapeutic study, level II.

Anatomy-mimetic design preserves natural kinematics of knee joint in patient-specific mobile-bearing unicompartmental knee arthroplasty.

PURPOSE: This study aims to evaluate whether different tibial-femoral conformities for patient-specific mobile-bearing unicompartmental knee arthroplasties (UKAs) preserve natural knee kinematics, using computational simulations. METHODS: Different designs for patient-specific mobile-bearing UKAs were evaluated using finite element analysis. Three designs for the identical femoral component were considered: flat (non-conforming design), anatomy-mimetic, and conforming for the tibial insert. RESULTS: The conforming design for the patient-specific mobile-bearing UKAs exhibited a 1.2 mm and 0.7° decrease in the translation and rotation, respectively, in the swing phase compared with those of the natural knee. In addition, the femoral rollback and internal rotation were 2.6 mm and 1.2° lower, respectively, than those of the natural knee, for the conforming design under the deep-knee-bend condition. The flat design for the patient-specific mobile-bearing UKAs exhibited a 2.2 mm and 1.4° increase in the femoral rollback and rotation compared with the natural knee under the deep-knee-bend condition. The anatomy-mimetic patient-specific mobile-bearing UKAs best preserved the natural knee kinematics under the gait and deep-knee-bend loading conditions. CONCLUSIONS: The kinematics of the loading conditions in patient-specific mobile-bearing UKAs was determined to closely resemble those of a native knee. In additional, by replacing the anatomy-mimetic design with a mobile-bearing, natural knee kinematics during gait and deep-knee-bend motions is preserved. These results confirm the importance of tibiofemoral conformity in preserving native knee kinematics in patient-specific mobile-bearing UKA.

Gender difference exists in sagittal curvature of the distal femoral condyle morphology for osteoarthritic population.

PURPOSE: The aim of this study was to investigate gender-related differences in the sagittal curvature of the distal femoral condyle in the Korean osteoarthritic population METHODS: The sagittal curvatures of the distal femoral condyle of 1979 Korean patients (1680 female and 299 male) were evaluated using magnetic resonance imaging (MRI). MRI scans were obtained before total knee arthroplasty (TKA) in consecutive patients with end-stage osteoarthritis. The sagittal curvature of the distal medial and lateral femoral condyles was characterized with respect to the anterior, distal, and posterior circles. The diameter of each circle was measured. This study included 1873 varus and 106 valgus knees. RESULTS: The anterior, distal, and posterior diameters were significantly greater in the male patients than in the female patients (P < 0.05). In the male patients, the lateral diameter was significantly greater than the medial diameter in the anterior and posterior circles (P < 0.05). However, in the female patients, the lateral diameter was significantly greater only in the anterior circle. In both genders, the medial diameter was significantly greater than the lateral diameter of the distal circle (P < 0.05). For both the varus and valgus knees, the lateral diameter was greater than the medial diameter in the anterior circle. CONCLUSIONS: It has been concluded that the sagittal curvature of the femoral condyles in females is significantly different to their male counterparts. This study provides a reliable evaluation of the sagittal curvature of the femoral condyle in the Korean population. These gender-related differences in the sagittal curvature of the femoral condyle may require further investigation to determine surgical implications such as in TKA, and the existence of gender-related dimorphism in specific knee injuries and pathologies, such as ligament injuries and tibiofemoral problems. LEVEL OF EVIDENCE: III.

Ganglioside GM3 Up-Regulate Chondrogenic Differentiation by Transform Growth Factor Receptors.

Mesenchymal stem cells, also known as multipotent stromal progenitor cells, can differentiate into cells of mesodermal lineage. Gangliosides are sialic acid-conjugated glycosphingolipids that are believed to regulate cell differentiation and several signaling molecules. These molecules are localized in glycosphingolipid-enriched microdomains on the cell surface and are regulated by glycosphingolipid composition. Transforming growth factor-beta (TGF-ß) signaling plays a critical role in chondrogenic differentiation. However, the role of gangliosides in chondrogenesis is not understood. In this study, the relationship between the ganglioside GM3 and TGF-ß activation, during chondrogenic differentiation, was investigated using an aggregate culture of human synovial membrane-derived mesenchymal stem cells. We showed that the gangliosides GM3 and GD3 were expressed after the chondrogenic differentiation of hSMSC aggregates. To test whether GM3 affected the chondrogenic differentiation of hSMSC aggregates, we used GM3 treatment during chondrogenic differentiation. The results showed that the group treated with 5 µM GM3 had higher expression of chondrogenic specific markers, increased toluidine blue, and safranin O staining, and increased accumulation of glycosaminoglycans compared with the untreated group. Furthermore, GM3 treatment enhanced TGF-ß signaling via SMAD 2/3 during the chondrogenic differentiation of hSMSC aggregates. Taken together, our results suggested that GM3 may be useful in developing therapeutic agents for cell-based articular cartilage regeneration in articular cartilage disease.

Difference in coronal curvature of the medial and lateral femoral condyle morphology by gender in implant design for total knee arthroplasty.

PURPOSE: The purpose of this study was to investigate the morphometric data obtained from the three-dimensional magnetic resonance images of ethnic Korean knee osteoarthritis, and to evaluate the morphological differences between the coronal curvature of the female and male femoral condyles. METHODS: The differences in coronal curvature of the femoral condyle morphology of 1990 patients (1689 females and 301 males) were evaluated in three dimensions. A close-fit diameter was, respectively, generated on the medial and lateral femoral condyle articular surfaces, and these diameters reflect the coronal diameter of the femoral condyle curvature. These measurements were compared with those of the femoral design of five different commonly used total knee arthroplasty (TKA) implant designs. RESULTS: The average diameter of the curvature of the medial condyles was significantly larger than that of the lateral condyles (P < 0.05). This trend was found in the male and female groups. In addition, the average diameter of the curvature of the femoral condyles was found to significantly differ between males and females (P < 0.05). For four TKA implant designs, the average diameter of the coronal curvature of femoral condyle was smaller than that obtained via our measurements, whereas one TKA implant design yielded a smaller average diameter. Furthermore, the medial and lateral coronal curvatures of the femoral condyle were symmetric in all TKA implant designs. CONCLUSION: The study provided a reliable and consistent evaluation of the coronal curvature of femoral condyles in the Korean population. These results showed that a gender-specific or asymmetric femoral component design is required to regenerate the coronal curvature of the femoral condyles for ethnically Korean males and females.

Gender difference in bowing of the sagittal femoral morphology measurement using magnetic resonance imaging.

The importance of femoral sagittal bowing on total knee arthroplasty (TKA) has not been actively discussed. Femoral sagittal bowing can lead to cortex damage, fractures, or femoral malalignment. Therefore, the purpose of this study was to evaluate femoral sagittal bowing at different segments of the femur in the Korean population, and to discuss the implications on total knee arthroplasty. Differences in the morphology of femoral sagittal bowing for 978 patients-829 women and 148 men-were evaluated using magnetic resonance imaging. The angle between the femoral mechanical axis and the anterior cortex line was measured for all the patients. In addition, the gender difference in femoral sagittal bowing was investigated. The angle of femoral sagittal bowing with the mechanical axis was 2.8˚ ± 2.2˚. The angles for femoral sagittal bowing were 2.9˚ ± 2.2˚ and 2.3˚ ± 2.6˚ for females and males, respectively. Thus, a gender difference was found in the femoral sagittal bowing (p < 0.05). Excessive sagittal bowing of the femur can affect the final sagittal position of the femoral component, and this has implications for implant design selection. We recommend that surgeons accurately perform pre-operative evaluation of femoral bowing to prevent potential malalignment, rotation, and abnormal stresses between the femur and implant.

Morphometric study of gender difference in osteoarthritis posterior tibial slope using three-dimensional magnetic resonance imaging.

Posterior tibial slope (PTS) is an important parameter of sagittal alignment associated with postoperative stability and kinematics after total knee arthroplasty (TKA). However, data are limited regarding the innate gender differences in PTS in Koreans. The current study separately measured the PTS of the medial and lateral tibial plateau on magnetic resonance images of 511 patients with knee joint osteoarthritis who had Kellgren and Lawrence grade 3 and 4 (430 women, 81 men) and compared the measurements between and within the genders. The tibia was then rotated to the tibial plateau with the tibial centroid axis and the PTS was evaluated from best-fit planes on the surface of the proximal tibia and individually for the medial, lateral, and overall plateaus. The average overall PTS was 10.0° ± 3.5°. The average overall PTS of the female and male patients was 10.2° ± 3.4° and 8.8° ± 4.0°, respectively. The average medial PTS was 10.4° ± 4.0°, significantly greater than the mean lateral PTS of 8.7° ± 3.9° (P < 0.05). The average medial and lateral tibial slopes for female patients were 10.7° ± 3.8° and 8.8° ± 3.8°, respectively, while the average medial and lateral tibial slopes for male patients were 8.9° ± 4.8° and 7.9° ± 4.7°, respectively. The medial and overall PTS were significantly greater in female patients than in male patients (P < 0.05). The results showed a gender difference in PTS and that medial PTS was greater than lateral PTS. These findings have clinical relevance in knee reconstructive surgery for determining ideal placement of the posterior slope tibial component. Surgeons should be aware of variability and gender differences in the tibial slope of patients undergoing TKA.

Computational analysis of customized cruciate retaining total knee arthroplasty restoration of native knee joint biomechanics.

The purpose of this study was to verify if customized prosthesis better preserves the native knee joint kinematics and provides lower contact stress on the polyethylene (PE) insert owing to the wider bone preservation than that of standard off-the-shelf prosthesis in posterior cruciate-retaining type total knee arthroplasty (TKA). Validated finite element (FE) models for were developed to evaluate the knee joint kinematics and contact stress on the PE insert after TKA with customized and standard off-the-shelf (OTS) prostheses as well as in normal healthy knee through FE analysis under dynamic loading conditions. The contact stresses on the customized prosthesis decreased by 18% and 8% under gait cycle loading conditions, and 24% and 9% under deep-knee-bend loading conditions, in the medial and lateral sides of the PE insert, respectively, compared with the standard OTS prosthesis. The anterior-posterior translation and internal-external (IE) rotation in customized TKA were more similar to native knee joint behaviors compared with standard OTS TKA under gait loading conditions. The difference from normal knee kinematics was lower for femoral rollback and IE rotation in customized TKA than in standard OTS TKA in the deep-knee-bend condition. In general, customized prostheses achieve kinematics that are close to those of the native healthy knee joint and have better contact stresses than standard OTS prostheses in gait and deep-knee-bend loading conditions.

Flexed femoral component improves kinematics and biomechanical effect in posterior stabilized total knee arthroplasty.

PURPOSE: The kinematics and biomechanics of the knee joint are important in ensuring patient satisfaction and functional ability after total knee arthroplasty (TKA). There has been no study on knee joint mechanics with regard to the sagittal alignment of the femoral component. The objective of this study is to determine the extent of the impact of the femoral component's sagittal alignment on kinematics and biomechanics. METHODS: A validated computational TKA model was used. The femoral component was simulated at - 3°, 0°, 5°, and 7° of flexion in the sagittal plane. This study evaluated the tibiofemoral (TF) joint kinematics, contact point, quadriceps force, and contact stress on the patellofemoral (PF) joint under a deep-knee-bend condition. RESULTS: The kinematics of the TF joint in the posterior direction increased with the flexion of the femoral component position. For all tasks, the overall posterior locations of the TF contact points were observed in the medial and lateral compartments as the femoral component flexion angle increased. The quadriceps force and contact stress on the PF joint decreased with the femoral component flexion. CONCLUSION: This study found that the femoral component sagittal position is an important factor in knee joint mechanics. In this study, the flexion of femoral component showed a stable reconstruction of the knee extensors' mechanism. Surgeons may consider neutral-to-mild flexed femoral component position, without concerns of anterior notching of the femoral cortex.

Tibiofemoral conformity variation offers changed kinematics and wear performance of customized posterior-stabilized total knee arthroplasty.

PURPOSE: Posterior-stabilized (PS)-total knee arthroplasty (TKA) can be applied in any of several variations in terms of the tibiofemoral conformity and post-cam mechanism. However, previous studies have not evaluated the effect of the condylar surface radii (tibiofemoral conformity) on wear in a customized PS-TKA. The present study involved evaluating the wear performance with respect to three different conformities of the tibiofemoral articular surface in a customized PS-TKA by means of a computational simulation. METHODS: An adaptive computational simulation method was developed that conduct wear simulation for tibial insert to predict kinematics, weight loss due to wear, and wear contours to results. Wear predictions using computational simulation were performed for 5 million gait cycles with force-controlled inputs. Customized PS-TKA designs were developed and categorized as conventional conformity (CPS-TKA), medial pivot conformity (MPS-TKA), and anatomical conformity (APS-TKA). The post-cam design in the customized PS-TKA is identical. We compared the kinematics, contact mechanics, and wear performance. RESULTS: The findings revealed that APS-TKA exhibited the highest internal tibial rotation relative to other TKA designs. Additionally, the higher contact area led to there being less contact stress although it did not directly affect the wear performance. Specifically, MPS-TKA exhibited the lowest volumetric wear. CONCLUSIONS: The results of the present study showed that tibiofemoral articular surface conformity should be considered carefully in customized PS-TKA design. Different wear performances were observed with respect to different tibiofemoral conformities. Even though APS-TKA exhibited an inferior wear performance compared to MPS-TKA, it proved to be better in terms of kinematics so its functionality may be improved through the optimization of the tibiofemoral articular surface conformity. Additionally, it should be carefully designed since any changes may affect the post-cam mechanism.

Gender-related morphological differences in sulcus angle and condylar height for the femoral trochlea using magnetic resonance imaging.

PURPOSE: This study aimed to elucidate the primary differences in trochlear morphology between men and women utilizing three-dimensional magnetic resonance image reconstruction of the femoral trochlea. METHODS: Differences in anthropometric femoral trochlea data of 975 patients (825 women, 150 men) were evaluated. The following morphological parameters were measured at three flexion angles (15°, 30°, and 45°) of the femoral trochlea: the sulcus angle, condylar height, and the trochlear groove orientation and mediolateral groove position. RESULTS: The sulcus angle was significantly greater in women than in men at 15° and 45° flexions (P < 0.05). However, there was no gender difference found in the sulcus angle at 30° flexion. Medial and lateral condylar height values were greater in men than in women for the three flexion angles (P < 0.01). The trochlear groove orientation and mediolateral groove position showed no gender-related differences. CONCLUSIONS: Magnetic resonance image reconstruction demonstrated that measurement of trochlear morphology varied significantly between men and women. This study provides guidelines for the design of a suitable femoral component for total knee arthroplasty, considering gender-specific differences in the Korean population. Biomechanical guidelines for total knee arthroplasty in Korean individuals can be optimized using our finding, so as the risk of patellar dislocation to be decreased. Surgeons should be aware of gender differences in femoral trochlear to optimize choice of implant. LEVEL OF EVIDENCE: III.

Gender differences in morphology exist in posterior condylar offsets of the knee in Korean population.

PURPOSE: This study aimed to analyze the morphometric data from magnetic resonance images of arthritic knees in Korean adults, and to identify the existence of morphological differences of femoral posterior condylar offset (PCO) between genders. METHODS: The differences in anthropometric PCO data in 975 patients (825 female and 150 male) were evaluated. The distances from the anterior and posterior femoral shaft cortex line to the most posterior femoral condyle tangent line were defined as the anterior-posterior dimension (AP) and the PCO. The PCO ratio (PCOR) was calculated as PCO/AP. RESULTS: The medial PCO was greater than the lateral PCO (26.3 ± 2.2 vs. 24.3 ± 2.3 mm, p < 0.01). This difference was observed in both female patients (medial: 26.2 ± 2.2 mm vs. lateral: 24.2 ± 2.2 mm, p < 0.01) and male patients (medial: 26.8 ± 2.3 mm vs. lateral: 24.8 ± 2.4 mm, p < 0.01). The medial and lateral PCO values were also greater in male patients than in female ones (p < 0.01). In contrast, PCOR was greater in female patients than in male ones, both in the medial and lateral femoral condyles (p < 0.01). CONCLUSIONS: It was shown that medial and lateral PCO and PCOR were asymmetric, and that there was gender difference in Korean population in our study. In addition, our data showed that the PCOR of contemporary TKAs may be small for Asian patients that may not be sufficient to meet the needs of the Korean patient population. These results confirm that a gender-specific femoral component design is necessary to recreate the PCO for male and female Asian populations. LEVEL OF EVIDENCE: Non-consecutive patients, Level III.

Prognostic Factors Affecting Correction Angle Changes After Supramalleolar Osteotomy Using an Opening Wedge Plate for Varus Ankle Osteoarthritis.

Supramalleolar osteotomy (SMO) has been suggested as an effective salvage treatment for varus ankle osteoarthritis. To identify the prognostic factors affecting the correction angle changes after SMO, a total of 53 consecutive patients (58 ankles) were evaluated retrospectively. Clinical and radiologic outcomes were evaluated, and statistical analyses were performed to identify the prognostic factors associated with the clinical and radiologic outcomes. The mean visual analogue scale scores and the American Orthopaedic Foot and Ankle Society scores improved significantly at the final follow-up (both p <.001). The mean tibial-ankle surface (TAS), talar tilt (TT), and tibial-lateral surface angles improved significantly after surgery, compared with the preoperative assessments (all, p <.001). However, at the final follow-up, these angles had changed significantly, compared with their immediate postoperative values (all p <.001), and the changes in the TAS and TT angles significantly influenced the clinical outcomes at the final follow-up (both p <.05). Male sex, high body mass index (≥26.4 kg/m2), and the existence of the lateral cortex breakages were significantly associated with the changes in the TAS and TT angle (all p <.05). Therefore, surgeons should consider these prognostic factors before performing SMO.

Comparative Matched-Pair Analysis of Keyhole Bone-Plug Technique Versus Arthroscopic-Assisted Pullout Suture Technique for Lateral Meniscal Allograft Transplantation.

PURPOSE: To compare the clinical outcomes and meniscal extrusion measured by magnetic resonance imaging (MRI) between the keyhole bone-plug technique and arthroscopic-assisted pullout suture technique in lateral meniscal allograft transplantation (MAT). METHODS: Between October 2009 and February 2015, patients who underwent lateral MAT were retrospectively reviewed. The inclusion criteria were patients with symptomatic knees that had undergone total or subtotal meniscectomy who were treated with lateral MAT with a minimum follow-up period of 2 years. We excluded 13 patients with anterior cruciate ligament injury to the ipsilateral knee and 6 patients with combined cartilage procedures. In addition, we excluded 19 patients because they did not undergo follow-up MRI and 13 patients who did not undergo more than 2 years of follow-up. Thirty-seven patients who underwent lateral MAT with the keyhole bone-plug technique were identified and assigned to group A. Forty-five patients who underwent lateral MAT with the arthroscopic-assisted pullout suture technique (group B) were then matched by age, body mass index, and time from previous meniscectomy to lateral MAT. Clinical outcome assessments included preoperative and postoperative subjective International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores and the visual analog scale (VAS) score for pain evaluation. MRI was used to assess meniscal extrusion. RESULTS: The mean follow-up period was 35.8 ± 6.5 months (range, 24-65 months) in group A and 34.6 ± 6.2 months (range, 24-55 months) in group B. Significant improvements in the VAS pain score, subjective IKDC score, Tegner score, and Lysholm score after lateral MAT were found (P < .001), and there were no significant differences between the 2 groups at final follow-up (VAS score, 1.4 ± 0.8 in group A and 1.2 ± 1.0 in group B [P = .164]; subjective IKDC score, 72.9 ± 8.1 in group A and 74.2 ± 7.3 in group B [P = .427]; Tegner activity score, 4.0 ± 0.9 in group A and 4.1 ± 0.8 in group B [P = .374]; and Lysholm score, 75.5 ± 10.6 in group A and 76.2 ± 11.8 in group B [P = .786]). On MRI, the meniscal extrusion extent was 3.1 ± 0.9 mm in group A and 2.9 ± 0.8 mm in group B (P = .223), and the relative percentages of extrusion were 27.0% ± 3.9% and 26.1% ± 4.2%, respectively (P = .273). CONCLUSIONS: Compared with the keyhole bone-plug technique, the arthroscopic-assisted pullout suture technique in lateral MAT showed comparable clinical and MRI results at short-term follow-up. LEVEL OF EVIDENCE: Level IV, case series with intragroup comparisons.

The increase in posterior tibial slope provides a positive biomechanical effect in posterior-stabilized total knee arthroplasty.

PURPOSE: This study aims to clarify the influence of the posterior tibial slope (PTS) on knee joint biomechanics after posterior-stabilized (PS) total knee arthroplasty (TKA) using a computer simulation. METHODS: A validated TKA computational model was used to evaluate and quantify the effects of an increased PTS. In order to conduct a squat simulation, models with a - 3° to 15° PTS using increments of 3° were developed. Forces on the quadriceps and collateral ligament, a tibial posterior translation, contact point on a polyethylene (PE) insert, and contact stress on the patellofemoral (PF) joint and post in a PE insert were compared. RESULTS: The maximum force on the quadriceps and the PF contact stress decreased with increases in the PTS. The kinematics on the tibiofemoral (TF) joint translated in an increasingly posterior manner, and the medial and lateral contact points on a PE insert were located in posterior regions with increases in the PTS. Additionally, increases in the PTS decreased the force on the collateral ligament and increased the contact stress on the post in a PE insert. A higher force on the quadriceps is required when the PTS decreases with an equivalent flexion angle. CONCLUSIONS: A surgeon should be prudent in terms of determining the PTS because an excessive increase in the PTS may lead to the progressive loosening of the TF joint due to a reduction in collateral ligament tension and failure of the post in a PE insert. Thus, we support a more individualized approach of optimal PTS determination given the findings of the study.