Search Results (65)

Background/Objectives: Lateral patellar dislocation (LPD) is a common pathology of the adolescent knee and a major predisposing factor for patellofemoral instability (PFI). The pathogenesis of PFI involves a combination of anatomical and biomechanical contributors, with increasing evidence pointing to sex-specific differences in knee morphology. Despite this, the developmental course of these parameters and their variation between sexes remain insufficiently characterized. This study aims to investigate sex-related differences in patellofemoral joint geometry among skeletally immature patients with a history of PFI, focusing on how these anatomical variations evolve with increasing knee size, as represented by femoral condylar width. Methods: A total of 315 knee MRIs from patients under 18 years with documented PFI were retrospectively analyzed. Trochlear morphology, patellar tilt, axial positioning, and sagittal alignment were assessed using established MRI-based parameters. All measurements were normalized to bicondylar width to account for individual knee size. Sex-specific comparisons were performed using independent t-tests and linear regression analysis. Results: Females exhibited significantly smaller femoral widths, shallower trochlear depth (TD), shorter tibial tubercle–posterior cruciate ligament (TTPCL) distances, and lower patellar trochlear index (PTI) values compared to males (p < 0.05). In males, increasing femoral width was associated with progressive normalization of patellar tilt and sagittal alignment parameters. In contrast, these alignment parameters in females remained largely unchanged or worsened across different femoral sizes. Additionally, patellar inclination angle and PTI were significantly influenced by knee size in males (p < 0.05), whereas no such relationship was identified in females. Conclusions: Sex-specific morphological differences in patellofemoral geometry are evident early in development and evolve distinctly with growth. These differences may contribute to the higher prevalence of PFI in females and underscore the importance of considering sex and knee size in anatomical assessments. Full article

Background: The knee joint performs a vital function in human movement, supporting significant loads and ensuring stability during daily activities. Methods: The objective of this study was to develop and validate a subject-specific framework to model knee flexion–extension by integrating 3D gait data with individualized musculoskeletal (MS) and finite element (FE) models. In this proof of concept, gait data were collected from a 52-year-old woman using Xsens inertial sensors. The MS model was based on the same subject to define realistic loading, while the 3D knee FE model, built from another individual’s MRI, included all major anatomical structures, as subject-specific morphing was not possible due to unavailable scans. Results: The FE simulation showed principal stresses from –28.67 to +44.95 MPa, with compressive stresses between 2 and 8 MPa predominating in the tibial plateaus, consistent with normal gait. In the ACL, peak stress of 1.45 MPa occurred near the femoral insertion, decreasing non-uniformly with a compressive dip around –3.0 MPa. Displacement reached 0.99 mm in the distal tibia and decreased proximally. ACL displacement ranged from 0.45 to 0.80 mm, following a non-linear pattern likely due to ligament geometry and local constraints. Conclusions: These results support the model’s ability to replicate realistic, patient-specific joint mechanics. Full article

Background/Objectives: This is the first study to examine age-related patterns of meniscal/chondral lesions in women undergoing first-time knee arthroscopy. Methods: We analyzed meniscal tear type/location and evaluated cartilage damage in femoral condyles and the tibial plateau in a medium-sized Romanian cohort (n = 241). Results: Age was associated significantly (p ≤ 0.004) with medial meniscal damage (O.R. = 1.04, 95% CI: 1.01–1.06), medial femoral condyle chondropathy (O.R. = 1.06, 95% CI: 1.03–1.10), and medial tibial plateau chondropathy (O.R. = 1.07, 95% CI: 1.02–1.12). Medial meniscus tear patterns differed significantly between age groups (p < 0.001, Cramér’s V = 0.32). Bucket-handle tears—the most common tear type—peaked in middle age (p < 0.001, Cramér’s V = 0.30). The two menisci showed different distributions of tear patterns in women aged ≥40 years (p ≤ 0.023, Cramér’s V ≤ 0.41). Meniscal tears most commonly involved the posterior third. The distribution of tear sites in menisci (medial vs. lateral) varied significantly in women aged 40–59 years (p = 0.020, Cramér’s V = 0.28). The medial femoral condyle and medial tibial plateau showed significant intergroup differences in ICRS scores (p ≤ 0.024, Cramér’s V ≤ 0.34). The frequency of ICRS grade 4 cartilage lesions increased markedly in the 40–59 age group at both sites, continuing to rise in older patients for the medial tibial plateau. Conclusions: Knee pathology in women worsens with age, especially in the medial compartment. Early screening (intervention) in middle-aged women may help prevent advanced joint damage. Full article

Whole-leg radiographs (WLRs) are widely used to assess coronal alignment before total knee arthroplasty (TKA), but may be inaccurate in patients with atypical morphotypes or malrotation. This study evaluated the discrepancy between WLR and 3D computed tomography (CT) scans across coronal plane alignment of the knee (CPAK) morphotypes and introduced a novel projection index—the femoral notch projection ratio (FNPR). In CPAK III knees, 19% of cases exceeded a clinically relevant threshold (>3° difference), prompting investigation of underlying projection factors. In 187 knees, coronal angles—including the medial distal femoral angle (MDFA°), medial proximal tibial angle (MPTA°), femoral mechanical angle (FMA°), and arithmetic hip–knee–ankle angle (aHKA°)—were measured using WLR and CT. Rotational positioning on WLR was assessed using FNPR and the patellar projection ratio (PPR). CPAK classification was applied. WLR systematically underestimated alignment, with the greatest bias in CPAK III (MDFA° + 1.5° ± 2.0°, p < 0.001). FNPR was significantly higher in CPAK III and VI (+1.9° vs. −0.3°, p < 0.001), indicating a tendency toward internally rotated limb positioning during imaging. The PPR–FNPR mismatch peaked in CPAK III (4.1°, p < 0.001), suggesting patellar-based centering may mask rotational malprojection. Projection artifacts from anterior osteophytes contributed to outlier measurements but were correctable. Valgus morphotypes with oblique joint lines (CPAK III) were especially prone to projection error. FNPR more accurately reflected rotational malposition than PPR in morphotypes prone to patellar subluxation. A 3D method (e.g., CT) or repeated imaging may be considered in CPAK III to improve surgical planning. Full article

Background: Osteotomies around the knee aim to correct varus or valgus malalignment and improve biomechanics. However, little is known about their effect on knee phenotypes, as defined by the Coronal-Plane-Alignment-of-the-Knee (CPAK) and Hirschmann’s functional classification. This study evaluated pre- and postoperative phenotypes in patients undergoing high-tibial-osteotomy (HTO) or distal-femoral-osteotomy (DFO). Methods: We retrospectively analysed 214 osteotomies around the knee (HTO: 145; DFO: 69) of 188 patients from our institutional registry. Radiographic parameters were measured using a validated artificial intelligence software, with phenotypes classified by CPAK and Hirschmann classification. Preoperative osteotomy planning was compared to postoperative alignment. Regression was used to assess the influence of demographic and radiographic factors. Results: CPAK types changed in 95.3% of cases. Medial opening HTOs most frequently shifted from CPAK type I (73.8%) to VI (42.3%), while medial closing DFOs transitioned from type III (81.5%) to V (24.1%). Concordance between planned and achieved CPAK types was highest for types III, IV, and V. Postoperative angles were generally smaller than planned for joint-line-obliquity (JLO), lateral-distal-femur-angle, and medial-proximal-tibial-angle (p < 0.001). Neutral JLO was restored in only 48.1%. Preoperative phenotypes NEUmLDFA0° (40.1%) and VARmMPTA3° (32.3%) were most common, while postoperative phenotypes included VALmLDFA3° (52.4%) and VALmMPTA3° (37.7%). Age, sex, and BMI significantly influenced alignment outcomes. Conclusions: Postoperative CPAK classifications shifted significantly across all osteotomy types, with minimal retention of preoperative types. Although most procedures achieved correction within the target HKA range, restoration of a neutral JLO was observed in only half of the cases, emphasizing the importance of phenotype-specific planning and highlight potential limitations of CPAK classification. Full article

Micro-computed tomography assessment of osteochondral microstructural properties of the distal femur and proximal tibia was comprehensively conducted to compare adult patients with knee rheumatoid arthritis (RA) and primary knee osteoarthritis (KOA), with special focus on the effects of knee malalignment. This study encompassed 402 bone samples divided into three groups: the RA group [patients who were subjected to total knee arthroplasty (TKA) due to RA, n = 23, age: 61 ± 10 years], the KOA group [individuals subjected to TKA due to KOA, n = 24, age: 71 ± 9 years] and the control group [sex-matched cadavers without degenerative knee diseases, n = 20, age: 67 ± 11 years]. Our data revealed that the RA, KOA, and control groups differ significantly in osteochondral microstructural properties depending on the knee alignment. Specifically, increasing femoral and tibial cortical porosity, coupled with thinner articular cartilage, were noted in the RA and KOA groups, compared to the controls. Furthermore, larger femoral and tibial cortical pores, lower tibial and femoral subchondral trabecular bone fraction, and thinner tibial articular cartilage were noted in the RA group in comparison to the KOA group, implying that the medial-to-lateral load distribution in the knee joint could be most affected in these patients. Our data illustrated that the thinnest cartilage, a thicker and less porous cortex, along with lower trabecular bone volume, were present in the lateral femoral and tibial condyles of RA individuals with valgus knee alignment. Observed subchondral trabecular microarchitectural alterations could be morphological factors contributing to different effects of surgical treatment and variable implant stability in individuals with RA, warranting further research. Full article

Background: Variations in femoral version are increasingly recognized as contributing factors to the development of symptomatic femoroacetabular impingement (FAI) and ischiofemoral impingement (IFI). Despite having implications for both hip arthroplasty and hip preservation surgery, functional femoral version (FFV) and overall limb torsion (OLT) are understudied. This study was conducted with the primary aim of defining and measuring FFV as a function of OLT. Methods: A cohort of 106 patients scheduled for primary hip arthroplasty underwent detailed retrospective assessment through CT and EOS imaging. Femoral torsion, transmalleolar axis, tibial torsion, trochanteric station and limb torsion were measured. The trochanteric station distance was also defined on both CT as well as on the lateral standing EOS. Statistical analyses examined the relationships between FFV, OLT, and other measurements. Results: Findings indicate a strong correlation between OLT and FFV. Agreement between CT and EOS imaging for trochanteric station was 0.88. Conclusions: The study reveals that OLT offers a more comprehensive assessment of impingement risk than anatomical femoral version alone. As OLT correlates with FFV, it highlights the role of axial limb alignment in hip joint biomechanics. Understanding the interplay between FFV and OLT can guide more individualized surgical techniques, potentially improving patient outcomes. Full article

Background/Objectives: Medial open wedge high tibial osteotomy (MOWHTO) has led to favorable clinical results since the introduction of locking plates. Surgical indications, techniques, and postoperative alignment are crucial for achieving favorable clinical outcomes. This study analyzed the clinical outcomes of patients after >5 years of post-MOWHTO follow-up to identify the influential factors. Methods: Thirty-nine patients (48 knees) underwent MOWHTO for medial compartment knee osteoarthritis or -necrosis and were followed up for >5 years. The targeted postoperative % mechanical axis (%MA) was 62.5% (Fujisawa point). The Japanese Orthopaedic Association (JOA) Knee Disease Outcome Criteria score; Kellgren–Lawrence classification; hip-knee-ankle, medial proximal tibial, mechanical lateral distal femoral, and joint line convergence angles (JLCA); and %MA were evaluated preoperatively, at implant removal, and at the final follow-up. Total knee arthroplasty (TKA) was the survival endpoint. Uni- and multivariate analyses were performed to identify the factors influencing survival rates. Results: The mean JOA score improved from preoperative to implant removal and was sustained at 102 months. Four of the 48 knees required TKA, resulting in a 10-year survival rate of 82%. Body mass index, preoperative JLCA, and Δ%MA influenced the post-MOWHTO survival rate. The Δ%MA was significantly greater in the group with a %MA < 62.5% at implant removal. Conclusions: MOWHTO with a target %MA of 62.5% yielded favorable long-term outcomes. Additionally, preoperative obesity and high joint instability negatively influenced post-MOWHTO survival. Furthermore, a postoperative %MA of < 62.5% is associated with difficulty maintaining stable alignment and an increased risk of conversion to TKA. Full article

The anatomic characteristics of the graft and tunnel, i.e., the tunnel position, angle, length, and the graft bending angle, influence knee joint stability and postoperative functional recovery. The purpose of this study was to evaluate the tunnel position, length and angle, as well as graft bending angle after ACL reconstruction assisted by a surgical robot. A total of 70 patients were randomized into two groups: the surgical robot group (robot group, n = 35) and the traditional handheld locator group (control group, n = 35). Postoperative computed tomography (CT) was employed to assess the positions and lengths of the tunnels, as well as the tunnel angle and the graft bending angle. Additionally, the posterior wall distance was measured by determining the minimum vertical distance from the long axis of the tunnel to the posterior wall region. There were no significant differences between the two groups in the mean position or length of the femoral and tibial tunnel (p > 0.05). However, the femoral tunnel angle was significantly larger in the robot group compared to the handheld locator group (p = 0.012). The graft bending angle was significantly less acute in the robot group than in the control group (p = 0.008). Additionally, the posterior wall distance was significantly greater in the robot group compared to the control group (p < 0.001). The results suggest that surgical robot-assisted ACL reconstruction enhances safety in the inclination of the tunnel and graft, helping to avoid potential biomechanical issues such as the wiper effect and the bungee effect, which may lead to tunnel widening and surgical failure. Full article

Background: The coronal plane alignment of the knee (CPAK) classification categorises nine phenotypes based on constitutional limb alignment and joint line obliquity and can be used in healthy and arthritic knees. In total knee arthroplasty surgery, some morphological variables in planes other than the coronal plane are particularly interesting. One example is the distal femoral rotation. Our study aimed to search for relationships between phenotypes based on CPAK classification and distal femoral rotation. Methods: Data from 622 cases in 535 osteoarthritic patients who underwent primary total knee arthroplasty were retrospectively analysed. Computed tomography imaging was employed to ascertain the mechanical lateral distal femoral angle, the mechanical medial proximal tibial angle, and the distal femoral rotation (quantified using the condylar twist angle). Results: The variables were perfectly uncorrelated according to the regression equations, with a Coefficient of Determination of 0.0608 for the condylar twist angle. Upon visualising the condylar twist angle function using a contour map or surface curves with low interpolation, it became evident that the data did not follow any discernible pattern. Employing ANOVA, we found some statistically significant differences between the distributions of the CPAK groups for the condylar twist angle (F = 5.81; p < 0.001). Conclusions: Our study found no relevant relationships between coronal plane alignment, according to the CPAK classification, and the distal femoral rotation in the sample population studied. Perhaps the stratification of the CPAK groups (i.e., a purely arithmetical aspect) hides possible relationships between the coronal and the axial planes. Full article

Background and Objectives: In-toeing and out-toeing gait are rotational deformities commonly observed in children with neuromuscular conditions. These gait abnormalities often result from internal tibial torsion, increased femoral anteversion, and metatarsus adductus. This study was conducted to create a comprehensive evaluation of the effectiveness of lower extremity orthotics as a non-operative treatment option, given their regular use in clinical settings. The aim of this literature review was to understand the efficacy of various orthotic devices in correcting rotational deformities in the transverse plane, thereby improving ambulation stability and 3D joint motion. Materials and Methods: Literature published after 1 January 1990 was reviewed, utilizing databases such as CENTRAL (Wiley), CINAHL (EBSCO), Medline (OVID), Scopus (Elsevier), and Web of Science (Clarivate). In totality, 13 studies were included, evaluating 365 participants with neuromuscular conditions using various orthotic devices. Results: Among these studies, two were randomized control trials (Level 1), nine were quasi-experimental studies (Level 2), and two were case studies (Level 4). Quality assessment determined that 69% of the included studies had a low risk of bias, while 31% demonstrated a moderate risk. Compression garments and rotational systems showcased the greatest change in proximal lower extremity rotation at 19.73° ± 1.57 and 24.13° ± 8.49, respectively. The most significant difference in foot progression angle is through the use of rotational systems, 19° ± 26.87. Conclusions: In a short-term treatment, children with neuromuscular disorders exhibiting in-toeing or out-toeing gait may benefit from different types of orthoses. Compression garments may aid joint alignment and enhance proprioception, rotational systems correct alignment with precise adjustability, AFOs that achieve effective stabilization can deliver benefits in the transverse plane, and foot orthotics may be appropriate for mild gait abnormality management. Full article

This study presents a comprehensive three-dimensional finite element (FE) model inspired by the biomechanics of the human knee, specifically the tibiofemoral joint during the gait cycle. Drawing from natural biological systems, the model integrates bio-inspired elements, including transversely isotropic materials, to replicate the anisotropic properties of ligaments and cartilage, along with anatomically realistic bone and meniscus structures. This dual-material approach ensures a physiologically accurate representation of knee mechanics under varying conditions. The model effectively captures key biomechanical parameters, including a maximum medial tibial cartilage contact pressure of 16.75 MPa at 25% of the stance phase and a maximum femoral cartilage pressure of 10.57 MPa at 75% of the stance phase. Furthermore, its strong correlation with in vivo and in vitro data highlights its potential for clinical applications in orthopedics, such as pre-surgical planning and post-operative assessments. By bridging the gap between biomechanics and bioinspired design, this research contributes significantly to the field of biomimetics and offers a robust simulation tool for enhancing joint protection strategies and optimizing implant designs. Full article

Background/Objectives: Total knee arthroplasty (TKA) is the gold-standard treatment for advanced knee arthritis, offering pain relief and improved joint function. However, tibial component malalignment, malrotation, and improper biomechanical loading remain critical factors contributing to implant failure, instability, and revision surgeries. This review systematically examines the impact of biomechanical loading on the tibial insert following primary TKA, with a focus on alignment, posterior tibial slope (PTS), and load distribution. Methods: A systematic literature search was conducted across the PubMed, Google Scholar, and Web of Science databases following the PRISMA guidelines. Studies investigating the effects of tibial component alignment, varus/valgus deviations, PTS, and load distribution on tibial inserts post-TKA were included. Seven studies meeting the inclusion criteria were analyzed and described narratively. Results: The reviewed studies highlighted that varus and valgus malalignment significantly alter tibiofemoral contact pressures and ligament strains, increasing the risk of aseptic loosening and implant failure. Excessive PTS was associated with posterior femoral translation, altered ligament tension, and increased contact stresses on polyethylene (PE) inserts. Kinematically aligned TKA demonstrated reduced tibial force imbalances and improved functional outcomes compared to mechanically aligned TKA. Computational and cadaveric studies revealed that even minor malalignments (e.g., 3° varus or valgus) can cause significant biomechanical changes. Conclusions: Biomechanical loading on tibial inserts after primary TKA is highly sensitive to the alignment and PTS. Optimal alignment and controlled biomechanical forces are essential. Kinematically aligned TKA has shown promising effects, preventing aseptic loosening and ensuring long-term implant survival. Further in vivo studies are needed to validate these findings and optimize surgical techniques. Full article

Introduction: Popliteal cysts (PCs) are occasionally accompanied by knee osteoarthritis (OA) and varus malalignment. However, whether concomitant arthroscopic excision of PCs with medial open-wedge high tibial osteotomy (MOWHTO) improves the osteoarthritic environment remains unclear. Therefore, this study assessed serial changes in C-size, medial meniscus extrusion (MME), and cartilage status for up to 2 years following an MOWHTO. Methods: This study retrospectively used serial magnetic resonance imaging (MRI) evaluations to assess 26 consecutive patients who underwent MOWHTO. Of the 26 patients, six with preoperative PCs were included. Based on the arthroscopic findings at the time of the MOWHTO, concomitant meniscal and chondral lesions, and whether or not partial meniscectomy was performed, were evaluated. All patients underwent second-look arthroscopy with plate removal 2 years postoperatively. The PC size, MME, and cartilage sub-scores in the medial compartment of the whole-organ MRI score (WORMS) were assessed by serial MRI preoperatively and at 3, 6, 18, and 24 months postoperatively. The recurrence of PCs and clinical outcomes, including the Rauschning–Lindgren grade, were also evaluated when serial MRI was performed. Moreover, changes in cartilage status were assessed using two-stage arthroscopy. Results: All patients underwent concomitant partial meniscectomy for medial meniscal tears in the posterior horn. A significant decrease in the mean size of preoperative PCs (27.4 ± 22.3 mm) was noted from 3 months postoperatively (8.7 ± 7.6 mm, p = 0.018), and thereafter. The mean size of PCs further decreased with time until 2 years (1.5 ± 4.0 mm, p = 0.018) following an MOWHTO with partial meniscectomy. Moreover, significant improvements in the MME and WORMS values were noted from 3 to 24 months postoperatively. Meanwhile, no PC recurrence occurred during the follow-up period and the preoperative Rauschning–Lindgren grade improved significantly with time after MOWHTO (p = 0.026). Furthermore, the two-stage arthroscopic assessments showed significant improvements in ICRS grade in the medial femoral condyle (p = 0.038). Conclusions: After an MOWHTO with partial meniscectomy, PCs decreased with time up to 2 years postoperatively; no recurrence occurred during the follow-up period, although cyst excision was not concomitantly performed. Furthermore, the reduction in PCs corresponded with improvements in MME and chondral lesions in the knee joint following the MOWHTO. Full article

Background: Surgical accuracy in total knee replacement (TKR) may vary with the surgeon, the patient preoperative deformity, and the guiding system to perform the procedure. Navigation systems attempt to increase the intraoperative information the surgeon requires to make the appropriate decisions, sometimes associating cumbersome procedures and unclear effectiveness to place the implant more precisely than conventional instruments. Methods: We conducted a retrospective case-control study with prospective data collection of radiographic measurements (alignment, joint line and patellar height) in a sample of 100 consecutive patients receiving TKR Optetrak Logic PS, either with standard surgical technique with Trulion Instrumentation (n = 59) or with the Guided Personalized Surgery (GPS) system (n = 41). Results: The GPS group improved the alignment of the mechanical Lateral Distal Femoral Angle (mLDFA) in 1.6° compared to the control (p = 0.003), but not evident in the mechanical Medial Proximal Tibial Angle (mMPTA) (p = 0.132). The GPS system achieved a normal patellar height in 98% of cases, according to the Blackburne–Peel Index (BP), compared to 71% in the control group (p = 0.002). This was obtained in the femoral side, as measured in the Epicondylar Ratio (ER) (p = 0.004). A lower dispersion of postoperative measurements was observed in the GPS group in comparison with the control, being statistically significant in mMPTA (p = 0.000), CD-Index (p = 0.011), IS-Index (p = 0.002), mIS-Index (p = 0.008), BP-Index (p = 0.011), and ER (p = 0.004). Conclusions: Better post-surgical restoration of joint line and patellar height is observed in surgeries performed with the GPS system, as well as a tendency to more accurate mechanical alignment and lower inter-patient variability, suggesting higher reproducibility. Full article