Search Results (12)

Background/Objectives: Patella alta contributes to patellofemoral (PF) maltracking and anterior knee pain, but the agreement of patellar-height indices across imaging modalities and their clinical relevance remain uncertain. We aimed to estimate the prevalence of patella alta when using each index, quantify inter-method agreement, and quantify patella alta’s associations with Hoffa’s fat-pad impingement, patellar chondromalacia, and tibial tubercle–trochlear groove (TT–TG) distance. Methods: This retrospective cross-sectional study included 250 patients aged 18–38 years who underwent both knee radiography and MRI. Patellar height was assessed using the Insall–Salvati (IS) and modified Insall–Salvati (mIS) ratios on radiographs and MRI, and the Patellotrochlear Index (PTI) on MRI. Associations with fat-pad impingement, chondromalacia grade, and TT–TG abnormality were analyzed using the chi-square or Fisher’s exact test and as odds ratios (ORs) adjusted for age, sex, and imaged side; agreement was assessed with Cohen’s kappa (κ). Results: Patella alta prevalence was 13.2% using IS on radiographs and 10.8% using IS on MRI, but markedly lower with mIS (≤1.6%). Patella alta was more frequent in patients with Hoffa’s fat-pad impingement (31.1% vs. 5.7% on IS radiography; adjusted OR 8.83, 95% CI 3.82–20.45) and advanced chondromalacia (p = 0.025). Agreement was moderate between IS radiography and IS MRI (κ = 0.47, 95% CI 0.33–0.61) and between IS MRI and the PTI (κ = 0.43). Conclusions: The prevalence and clinical relevance of patella alta depend strongly on the measurement method. The IS ratio was the most consistent index, but radiography–MRI agreement was moderate rather than high, so the two are not interchangeable. The PTI adds information on trochlear engagement from the same MRI examination. These cross-sectional associations do not establish causation. Full article

Background/Objectives: Because patella alta frequently accompanies objective patellar instability, separating trochlear morphology from patellar height is difficult. We evaluated whether the trochlear facet asymmetry ratio was associated with instability among knees with patella alta. Methods: This retrospective case-control MRI study included 123 knees: 43 with objective patellar instability, 43 normal-height controls, and 37 patella alta-positive controls without instability identified by re-screening the eligible control pool. Nine morphologic parameters were measured. The primary analysis compared the instability group with patella alta-positive controls; a supportive analysis used the full cohort. Results: The facet asymmetry ratio showed a graded pattern across groups (instability, 42.7 ± 12.4%; patella alta-positive controls, 59.2 ± 10.7%; normal-height controls, 70.3 ± 11.4%; p < 0.001). In the primary comparison, it had the highest observed apparent area under the curve (0.855), although its confidence interval overlapped with those of quantitative trochlear depth and tibial tubercle-trochlear groove (TT-TG) distance; the Insall–Salvati ratio showed weaker discrimination (0.679). After adjustment for the Insall–Salvati ratio and age, a lower facet asymmetry ratio remained associated with instability (odds ratio per 1-percentage-point increase, 0.903; 95% confidence interval, 0.854–0.956; p < 0.001). This association was attenuated after additional adjustment for quantitative trochlear depth or for tibial tubercle-trochlear groove distance together with Wiberg type. Interobserver reliability was excellent (intraclass correlation coefficient, 0.994). Conclusions: In this selected cohort, a lower trochlear facet asymmetry ratio was associated with objective patellar instability after adjustment for patellar height and age. The internally derived 49% threshold is exploratory and requires external validation before clinical use. Full article

Background: Anterior cruciate ligament reconstruction (ACLR) is a common orthopedic procedure with generally favorable outcomes, yet graft failure remains a significant challenge, particularly in young and active patients. While various anatomical and biomechanical risk factors for graft failure have been proposed, the influence of the sagittal tibial tubercle–trochlear groove (sTTTG) distance, representing anterior–posterior alignment of the tibial tubercle, has not been sufficiently explored. This study aimed to evaluate the association between sTTTG and ACL graft failure and assess contributing biomechanical variables, including tibiofemoral rotation (TFR), posterior tibial slope (PTS), and knee flexion angle. Methods: For this secondary analysis, a retrospective matched case–control study was conducted, involving 151 patients with ACL graft failure who underwent revision ACLR and 151 controls with intact grafts after a minimum 2-year follow-up period. sTTTG was measured on axial MRI as the anteroposterior distance from the trochlear groove to the tibial tubercle, perpendicular to the posterior femoral condylar axis. Secondary measurements included TT-TG, TFR, medial and lateral PTS, and knee flexion angle. Group differences as well as factors predictive of sTTTG were analyzed. Results: The ACLR failure group demonstrated a significantly lower sTTTG distance compared to controls (0.5 ± 4.6 mm vs. 2.4 ± 4.8 mm, p = 0.001). Logistic regression analysis revealed that a 1 mm increase in sTTTG was associated with an 8% reduction in revision risk (OR = 0.93 per 1 mm increase; 95% CI, 0.88–0.97; p = 0.003), although the predictive accuracy was low (AUC = 0.6). Multivariable analysis identified lateral PTS and knee flexion as significant independent predictors of sTTTG. Conclusions: A decreased sTTTG distance was significantly associated with ACL graft failure, underscoring the relevance of sagittal tibial tubercle positioning in ACL biomechanics. While not an independent clinical decision-making tool, sTTTG appears relevant to graft failure and may be considered in future risk assessment strategies. Full article

Background: Proximal lower-extremity muscle strengthening is an important conservative intervention for patellofemoral pain syndrome (PFPS), as these muscle groups play critical roles in femoral stabilization and knee valgus control. However, evidence remains limited regarding the effectiveness of muscle strengthening in improving lower-extremity axial alignment through modulation of femoral neck anteversion, femoral internal rotation, and tibial external rotation. Therefore, the present study aimed to determine whether a strengthening protocol targeting the quadriceps and hip external rotator and hip abductor muscles could improve knee alignment and reduce bone torsion in young adults with patellofemoral pain syndrome. Methods: This prospective interventional cohort study implemented a muscle strengthening protocol in ten university students with PFPS. Outcomes included femoral neck anteversion angle (FNA), tibial tubercle–trochlear groove distance (TT–TG), tibial external torsion angle (TET), and the knee Q-angle, assessed via 3D reconstruction of computed tomography (3D-CT) images. Pre- and post-intervention data were analyzed using the Shapiro-Wilk test for normality and repeated-measures ANOVA (p < 0.05; 95% confidence interval). Results: Muscle strengthening improved lower-limb axial alignment, with reductions observed across all measures post-intervention. Mean changes were 0.68 ± 1.26° for FNA (p = 0.0626); 1.51 ± 0.97 mm for TT–TG (p = 0.0001); 1.38 ± 3.36° for TET (p = 0.2231); and 1.14 ± 1.52° for the Q-angle. Statistically significant improvements were observed for TT–TG and the Q-angle. Conclusions: Proximal muscle strengthening improved knee valgus and axial lower-limb alignment, as evidenced by significant reductions in Q angle and TT–TG distance. Reductions in femoral neck anteversion (FNA) and tibial external torsion angle (TET) were observed. However, these differences were not statistically significant. These findings support muscle strengthening as a noninvasive strategy for improving lower-limb alignment in individuals with patellofemoral pain syndrome. Full article

Background/Objectives: Habitual patellar dislocation is a rare but debilitating form of patellofemoral instability in children and adolescents, frequently associated with underlying anatomical abnormalities and ligamentous laxity. Despite multiple surgical techniques, recurrence and suboptimal functional recovery remain concerns. This study aimed to identify the demographic, clinical, and imaging factors associated with postoperative recurrence and poorer functional outcomes in pediatric patients surgically treated for habitual patellar dislocation. Methods: A retrospective cohort study was conducted on pediatric patients treated between 2016 and 2024 for habitual patellar dislocation. Inclusion criteria required age ≤ 18 years, a minimum 12-month follow-up, and complete imaging documentation. Clinical evaluation included the Beighton hyperlaxity score, lower-limb alignment, and Lysholm Knee Score. Imaging parameters assessed patellar height (Caton–Deschamps Index), trochlear dysplasia, patellar tilt, patellar subluxation, genu valgum, and tibial tubercle–trochlear groove (TT–TG) distance. Surgical treatment consisted of individualized combinations of soft-tissue realignment, quadriceps lengthening, Roux–Goldthwait procedures, and MPFL reconstruction. Statistical analyses evaluated predictors of recurrence and postoperative Lysholm score. Results: Thirty-four patients (45 knees; mean age 12 years; 73.5% female) were included. Preoperative Lysholm scores improved from a mean of 73 to 94 postoperatively (p < 0.0001). Recurrence occurred in 32.35% of patients and was significantly associated with generalized hyperlaxity (p = 0.0041), trochlear dysplasia (p = 0.045), and lateral patellar subluxation (p = 0.039). Suboptimal postoperative Lysholm scores (<85) were observed in 11.76% of patients, all with recurrence, and were significantly associated with genu valgum (p = 0.0011) and patella alta (p = 0.036). No significant associations were found for rotational deformities or femoral condyle hypoplasia. Conclusions: Habitual patellar dislocation in children is multifactorial, and the likelihood of recurrence increases with cumulative risk factors such as hyperlaxity, trochlear dysplasia, lateral subluxation, patella alta, and genu valgum. Comprehensive preoperative assessment is essential to guide combined, individualized surgical strategies that optimize stability and functional recovery. No single technique is universally curative; rather, tailored multimodal approaches yield the most favorable outcomes. Full article

Background/Objectives: The aim of our study was to identify the most reliable MRI measurements associated with patellar dislocation. Methods: MRI scans from 86 knees (48 controls and 38 with a history of patellar dislocation) were retrospectively analyzed. The following parameters were measured: lateral trochlear inclination (LTI) and its modified version, sulcus angle (SA), trochlear depth (TD), tibial tubercle–trochlear groove distance (TT–TG), patellar tendon–lateral trochlear ridge distance (PT–LTR), and PT–LTR horizontal, a novel modification. Inter-rater reliability was assessed using intraclass correlation coefficients (ICCs), and diagnostic accuracy was evaluated using ROC analysis. Results: All measurements significantly differed between the groups (p < 0.05). SA and TD were highly discriminative (AUC > 0.8) but demonstrated lower inter-rater agreement. PT-LTR horizontal strongly correlated with PT-LTR and was equally sensitive and specific for patellar dislocation as PT-LTR (81.6% and 87.5%, respectively) when in line or extending more laterally than the lateral trochlear ridge (AUC = 0.896, p < 0.001). LTI demonstrated the highest diagnostic performance with a sensitivity of 89.5% and a specificity of 97.9% for a cut-off ≤12.85° (AUC = 0.981), with excellent inter-rater agreement. LTI modified also performed well (AUC = 0.937), with a sensitivity and specificity of 81.6% and 93.7%, respectively. Conclusions: LTI, PT–LTR, and their modified versions demonstrated the highest reliability and diagnostic performance among the MRI measurements evaluated. Given their reproducibility and ease of application, these parameters may be useful in the imaging assessment of patellar dislocation. Further prospective studies are recommended to confirm their clinical utility in broader populations. Full article

Background/Objectives: Patellar instability is a common orthopedic condition affecting pediatric and adolescent populations, particularly during periods of rapid growth and increased sports participation. Recurrent patellar dislocation in skeletally immature patients is frequently associated with underlying anatomical risk factors such as patella alta, trochlear dysplasia, or increased tibial tubercle–trochlear groove distance. Methods: This narrative review summarizes the current evidence on the epidemiology, diagnostic approach, and arthroscopic management of patellar instability in skeletally immature patients. Results: Arthroscopy has become an essential tool in both the diagnosis and treatment of patellar instability, allowing for minimally invasive assessment of patellofemoral alignment, chondral pathology, and ligament integrity. It also enables precise surgical interventions such as physeal-sparing medial patellofemoral ligament reconstruction, which remains the preferred stabilization technique for patients with open physes due to its safety and efficacy. Emerging innovations, including robotic-assisted tunnel placement, bioengineered scaffolds for cartilage repair, and three-dimensional modeling for surgical planning, have the potential to improve outcomes and arthroscopic surgical precision in this population. Despite these advances, major challenges such as a lack of pediatric-specific outcome measures, variability in surgical indications and rehabilitation protocols, and limited long-term follow-up data remain. Conclusions: Optimizing outcomes in pediatric and adolescent patients with patellar instability requires individualized growth-aware strategies and multidisciplinary collaborations. By integrating technological innovation with patient-centered care, clinicians can continue to refine the arthroscopic management of patellofemoral instability in young patients. Full article

Background: Patella instability is one of the most common knee injuries in the adolescent patient. There are several pathoanatomic risk factors which should be assessed via several modalities, including X-rays, magnetic resonance imaging (MRI), or even CT scan. Objectives: We intend to review these risk factors along with the nonsurgical and surgical techniques used to prevent recurrent dislocations. Methods: We completed an extensive review of the recent literature concerning pediatric and adolescent patellar dislocation and subsequent treatment modalities. Results: We review in detail the risk factors such as patella alta, trochlear dysplasia, lateralization of the tibial tubercle or medialization of the trochlear groove (increased tibial tubercle to trochlear groove (TT–TG) distance), lower limb malalignment, excessive femoral anteversion and/or tibial torsion, and hyperlaxity. There are classification systems for dislocators, and a natural progression of instability that patients often proceed through. Only after a patient has continued to dislocate after bracing and physical therapy is surgical treatment considered. Surgical techniques vary, with the workhorse being the medial patellofemoral ligament (MPFL) reconstruction. However, there are a variety of other techniques which add onto this procedure to address other anatomic risk factors. These include the tibial tubercle osteotomy to address a large TT–TG distance or trochleoplasty to address the lack of a trochlear groove. Conclusions: Nonsurgical and surgical treatments for patella dislocators are tailored to the pathoanatomic risk factors in each patient. Full article

Background and Objectives: The immature skeleton in a pediatric population exposed to frequent physical activity might be extremely prone to injuries, with possible consequences later in adulthood. The main aim of this study is to present specific morphometric parameters and magnetic resonance imaging (MRI) morphological changes of the knee and patella in a physically active pediatric population. Additionally, we wanted to investigate the morphological risk factors for patellar instability. Materials and Methods: The study included the MRI findings of 193 physically active pediatric patients with knee pain. The participants underwent sports activities for 5 to 8 h per week. Two divisions were performed: by age and by patellar type. We evaluated three age groups: group 1 (age 11–14), group 2 (age 15–17), and group 3 (age 18–21 years). In addition, participants were divided by the patellar type (according to Wiberg) into three groups. The following morphometric parameters were calculated: lateral trochlear inclination (LTI), the tibial tubercle–trochlear groove distance (TT-TG), trochlear facet asymmetry (TFA), Insall–Salvati index, modified Insall–Salvati index, Caton–Deschamps index, articular overlap, morphology ratio and contact surface ratio. Results: We found a statistically significant association between patellar type groups in LTI (p < 0.001), TFA (p < 0.001), Insal–Salvati (p = 0.001) index, and Caton–Deschamps index (p = 0.018). According to age groups, we found statistical significance in the Caton–Deschamps index (p = 0.039). The most frequent knee injury parameter, according to Wiberg, in physically active pediatric patients was patella type 2 in boys and type 3 in girls. Conclusions: The MRI morphometric parameters observed in our study might be factors of prediction of knee injury in physically active children. In addition, it might be very useful in sports programs to improve the biomechanics of the knee in order to reduce the injury rate in sports-active children. Full article

Background: The tibial tubercle to trochlear groove (TT-TG) distance is currently considered as an indication for tibial tubercle osteotomy. While the influence of femoral condylar morphology on such measurement remains unclear. Methods: A total of 86 patients with patellar dislocation (PD) and 86 healthy individuals were enrolled. Femoral condylar morphology and the TT-TG distance measured by anatomical transepicondylar axis (TT-TGa), by surgical transepicondylar axis (TT-TGs), and by posterior condylar reference line (TT-TGp) were assessed by MRI. Unpaired t-test, Spearman, and Pearson correlation analysis were conducted. We determined the pathological value of the parameters and established a binary regression model. Results: The interclass correlation coefficients of all the TT-TG distances were greater than 0.75 in all types of trochlear dysplasia. The lateral/posterior femoral condyle was shorter and the medial/posterior condyle was longer in the study group (28.5 ± 3.3 and 35.2 ± 2.8, respectively) than in the control group (30.9 ± 2.7 and 33.5 ± 2.3, respectively). In the study group, the TT-TGp distance was greater than TT-TGs and TT-TGa distance (p < 0.001). The pathological value of the TT-TG distance was 13.0 mm. Each TT-TG distance revealed a significant OR with regard to PD. Conclusion: The TT-TGa, TT-TGs, and TT-TGp distance can be reliably measured by MRI even in patients with trochlear dysplasia. While the TT-TGp distance may overestimate the lateralization deformity of the tibial tubercle. Posterior femoral condylar dysplasia may be a reason for such overestimating. These findings have not been correlated to clinical outcomes and further studies are required. Full article

Patellofemoral instability (PFI) encompasses symptomatic patellar instability, patella subluxations, and frank dislocations. Previous studies have estimated the incidence of acute patellar dislocation at 43 per 100,000 children younger than age 16 years. The medial patellofemoral ligament (MPFL) complex is a static soft tissue constraint that stabilizes the patellofemoral joint serving as a checkrein to prevent lateral displacement. The causes of PFI are multifactorial and not attributed solely to anatomic features within the knee joint proper. Specific anatomic features to consider include patella alta, increased tibial tubercle–trochlear groove distance, genu valgum, external tibial torsion, femoral anteversion, and ligamentous laxity. The purpose of this paper is to provide a review of the evaluation of PFI in the pediatric and adolescent patient with a specific focus on the contributions of coronal and transverse plane deformities. Moreover, a framework will be provided for the incorporation of bony procedures to address these issues. Full article

Background: In the literature there are divergent results as to the native MPFL length change pattern. The reason for such divergent results may be the heterogeneity of design of studies analyzing MPFL isometry. The hypothesis of this review was that studies assessing MPFL length change pattern are highly heterogenous. The aim was to present a state-of-the-art review of sources of this heterogeneity. Materials and Methods: A total of 816 records were identified through the initial search of MEDLINE and Scopus databases. After eligibility assessment, 10 original articles and five reviews were included. In the included studies, the following 15 potential sources of heterogeneity were assessed: number of patients/cadavers, age, males to females ratio (demographics), identification of measured fibers, measurement method, measurement precision, quadriceps muscle activity, iliotibial band activity, hamstrings activity (study design), patellar height, trochlear or patellar dysplasia, femoral anteversion, mechanical axis of the limb, tibial tubercle–trochlear groove distance, and condylar anteroposterior dimensions (morphology). Each variable was graded in every included article with 1 point if reported precisely and not introducing bias; or with 0 points if reported not precisely, introducing bias, or not reported at all. Results: Within original articles, the highest achieved score was 10 out of 15 possible points with mean score of 6.7, SD = 2.37, and minimum score of just 3 out of 15 points. In the demographics section, mean score was 2.4, SD = 0.8 (80% of maximum possible score of 3); in the study design section it was 3.1, SD = 1.87 (52% of maximum possible score of 6); and in the morphology section it was 1.5, SD = 1.43 (25% of maximum possible score of 6). Conclusions: There is high heterogeneity and incomplete reporting of potential sources of bias in studies assessing native MPFL length change pattern. Future investigators should be aware of the presented factors and their potential impact on MPFL isometry. All methodologic factors should be meticulously reported. Detailed description of demographic data is already a standard; however, authors should more extensively report variables concerning study design and morphology of patients’ patellofemoral joint. Furthermore, future studies should try to meticulously simulate the real-life working environment of MPFL and ensure usage of proper measurement methods. Full article