T2 Mapping of Patellar Cartilage After a Single First-Time Episode of Traumatic Lateral Patellar Dislocation.

BACKGROUND: In most cases, lateral patellar dislocation (LPD) is accompanied by chondral injury and may initiate gradual degeneration of patellar cartilage, which might be detected with a T2 mapping, a well-established method for cartilage lesions assessment. PURPOSE: To examine short-term consequences of single first-time LPD in teenagers by T2 mapping of the patellar-cartilage state. STUDY TYPE: Prospective. POPULATION: 95 patients (mean age: 15.1 ± 2.3; male/female: 46/49) with first-time, complete, traumatic LPD and 51 healthy controls (mean age: 14.7 ± 2.2, male/female: 29/22). FIELD STRENGTH/SEQUENCE: 3.0 T; axial T2 mapping acquired using a 2D turbo spin-echo sequence. ASSESSMENT: MRI examination was conducted 2-4 months after first LPD. T2 values were calculated in manually segmented cartilage area via averaging over three middle level slices in six cartilage regions: deep, intermediate, superficial layers, and medial lateral parts. STATISTICAL TESTS: ANOVA analysis with Tukey's multiple comparison test, one-vs.-rest logistic regression analysis. The threshold of significance was set at P < 0.05. RESULTS: In lateral patellar cartilage, a significant increase in T2 values was found in deep and intermediate layers in both patient groups with mild (deep: 34.7 vs. 31.3 msec, intermediate: 38.7 vs. 34.6 msec, effect size = 0.55) and severe (34.8 vs. 31.3 msec, 39.1 vs. 34.6 msec, 0.55) LPD consequences as compared to controls. In the medial facet, only severe cartilage damage showed significant prolongation of T2 times in the deep layer (34.3 vs. 30.7 msec, 0.55). No significant changes in T2 values were found in the lateral superficial layer (P = 0.99), whereas mild chondromalacia resulted in a significant decrease of T2 in the medial superficial layer (41.0 vs. 43.8 msec, 0.55). DATA CONCLUSION: The study revealed substantial difference in T2 changes after LPD between medial and lateral areas of patellar cartilage. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY STAGE: 2.

Knee landmarks detection via deep learning for automatic imaging evaluation of trochlear dysplasia and patellar height.

OBJECTIVES: To develop and validate a deep learning-based approach to automatically measure the patellofemoral instability (PFI) indices related to patellar height and trochlear dysplasia in knee magnetic resonance imaging (MRI) scans. METHODS: A total of 763 knee MRI slices from 95 patients were included in the study, and 3393 anatomical landmarks were annotated for measuring sulcus angle (SA), trochlear facet asymmetry (TFA), trochlear groove depth (TGD) and lateral trochlear inclination (LTI) to assess trochlear dysplasia, and Insall-Salvati index (ISI), modified Insall-Salvati index (MISI), Caton Deschamps index (CDI) and patellotrochlear index (PTI) to assess patellar height. A U-Net based network was implemented to predict the landmarks' locations. The successful detection rate (SDR) and the mean absolute error (MAE) evaluation metrics were used to evaluate the performance of the network. The intraclass correlation coefficient (ICC) was also used to evaluate the reliability of the proposed framework to measure the mentioned PFI indices. RESULTS: The developed models achieved good accuracy in predicting the landmarks' locations, with a maximum value for the MAE of 1.38 ± 0.76 mm. The results show that LTI, TGD, ISI, CDI and PTI can be measured with excellent reliability (ICC > 0.9), and SA, TFA and MISI can be measured with good reliability (ICC > 0.75), with the proposed framework. CONCLUSIONS: This study proposes a reliable approach with promising applicability for automatic patellar height and trochlear dysplasia assessment, assisting the radiologists in their clinical practice. CLINICAL RELEVANCE STATEMENT: The objective knee landmarks detection on MRI images provided by artificial intelligence may improve the reproducibility and reliability of the imaging evaluation of trochlear anatomy and patellar height, assisting radiologists in their clinical practice in the patellofemoral instability assessment. KEY POINTS: • Imaging evaluation of patellofemoral instability is subjective and vulnerable to substantial intra and interobserver variability. • Patellar height and trochlear dysplasia are reliably assessed in MRI by means of artificial intelligence (AI). • The developed AI framework provides an objective evaluation of patellar height and trochlear dysplasia enhancing the clinical practice of the radiologists.

The strength of the patellar and Achilles tendon reflexes is not affected in uncomplicated pregnancy.

INTRODUCTION: Research on healthy pregnant women's reflexes is almost unheard of, even if an estimation of reflexes is a conventional part of the physical examination of preeclamptic patients, and hyperreflexia is generally considered to be a warning sign of eclampsia. The aim of the present study was to investigate the possible impact of gestation on tendon reflexes and the Babinski response, as examined in a clinical bed-side manner. MATERIAL AND METHODS: A prospective, single-blind, cross-sectional study. Three study groups comprised non-pregnant (n = 20), 14-18 weeks (n = 16), and 34-38 weeks (n = 15) healthy pregnant women respectively. Two experienced neurologists examined separately each participant's patellar reflexes, Achilles reflexes, and Babinski response and rated them on two different scales, National Institute of Neurological Disorders and Stroke (NINDS) scale and Mayo Clinic Scale for Tendon Reflex Assessment. Inter-observer estimations between the patient groups and the neurologists were made by mixed effect model methodology. RESULTS: The patellar and Achilles reflexes´ strengths were rated similarly in all three groups (p > 0.05). The inter-observer difference was non-significant between the neurologists´ estimations (p > 0.05). The neurologists estimated the Babinski response in a few cases as neutral (0), otherwise down (normal). CONCLUSIONS: The patellar and Achilles reflex strengths are not affected in uncomplicated pregnancy. There is good concordance between neurologists´ estimations of tendon reflex strengths rated on the NINDS and Mayo scales.

The Functional Organization of Corticomotor Neurons Within the Motor Cortex Differs Among Basketball and Volleyball Athletes With Patellar Tendinopathy Compared to Asymptomatic Controls.

Patellar tendinopathy (PT) typically affects jumping-sport athletes with functional impairments frequently observed. Alterations to the functional organization of corticomotor neurons within the motor cortex that project to working muscles are evident in some musculoskeletal conditions and linked to functional impairments. We aimed to determine if functional organization of corticomotor neuron projections differs between athletes with PT and asymptomatic controls, and if organization is associated with neuromuscular control. We used a cross-sectional design, and the setting was Monash Biomedical Imaging. Basketball and volleyball athletes with (n = 8) and without PT (n = 8) completed knee extension and ankle dorsiflexion force matching tasks while undergoing fMRI. We determined functional organization via identification of the location of peak corticomotor neuron activation during respective tasks (expressed in X, Y, and Z coordinates) and calculated force matching accuracy for both tasks to quantify neuromuscular control. We observed significant interactions between group and coordinate plane for functional organization of corticomotor projections to knee extensors (p < 0.001) and ankle dorsiflexors (p = 0.016). Compared to controls, PT group peak corticomotor activation during the knee extension task was 9.6 mm medial (p < 0.001) and 5.2 mm posterior (p = 0.036), and during the ankle dorsiflexion task 8.2 mm inferior (p = 0.024). In the PT group, more posterior Y coordinate peak activation location during the knee extension task was associated with greater task accuracy (r = 0.749, p = 0.034). Functional organization of corticomotor neurons differed in jumping athletes with PT compared to controls. Links between functional organization and neuromuscular control in the PT group suggest organizational differences may be relevant to knee extension neuromuscular control preservation.

Determining intracortical, corticospinal and alpha motoneurone excitability in athletes with patellar tendinopathy compared to asymptomatic controls.

BACKGROUND: Lower capacity to generate knee extension maximal voluntary force (MVF) has been observed in individuals affected with patellar tendinopathy (PT) compared to asymptomatic controls. This MVF deficit is hypothesized to emanate from alterations in corticospinal excitability (CSE). The modulation of CSE is intricately linked to the excitability levels at multiple sites, encompassing neurones within the corticospinal tract (CST), intracortical neurones within the primary motor cortex (M1), and the alpha motoneurone. The aim of this investigation was to examine the excitability of intracortical neurones, CST neurones, and the alpha motoneurone, and compare these between volleyball and basketball athletes with PT and matched asymptomatic controls. METHOD: Nineteen athletes with PT and 18 asymptomatic controls participated in this cross-sectional study. Transcranial magnetic stimulation was utilized to assess CST excitability, corticospinal inhibition (silent period, and short-interval cortical inhibition). Peripheral nerve stimulation was used to evaluate lumbar spine and alpha motoneurone excitability, including the evocation of lumbar-evoked potentials and maximal compound muscle action potential (MMAX ), and CSE with central activation ratio (CAR). Knee extension MVF was also assessed. RESULTS: Athletes with PT exhibited longer silent period duration and greater electrical stimulator output for MMAX , as well as lower MVF, compared to asymptomatic controls (p < 0.05). CONCLUSION: These findings indicate volleyball and basketball athletes with PT exhibit reduced excitability of the alpha motoneurone or the neuromuscular junction, which may be linked to lower MVF. Subtle alterations at specific sites may represent compensatory changes to excitability aiming to maintain efferent drive to the knee extensors.

Addressing muscle-tendon imbalances in adult male athletes with personalized exercise prescription based on tendon strain.

PURPOSE: Imbalances of muscle strength and tendon stiffness can increase the operating strain of tendons and risk of injury. Here, we used a new approach to identify muscle-tendon imbalances and personalize exercise prescription based on tendon strain during maximum voluntary contractions (εmax) to mitigate musculotendinous imbalances in male adult volleyball athletes. METHODS: Four times over a season, we measured knee extensor strength and patellar tendon mechanical properties using dynamometry and ultrasonography. Tendon micromorphology was evaluated through an ultrasound peak spatial frequency (PSF) analysis. While a control group (n = 12) continued their regular training, an intervention group (n = 10) performed exercises (3 × /week) with personalized loads to elicit tendon strains that promote tendon adaptation (i.e., 4.5-6.5%). RESULTS: Based on a linear mixed model, εmax increased significantly in the control group over the 9 months of observation (pCon = 0.010), while there was no systematic change in the intervention group (pInt = 0.575). The model residuals of εmax, as a measure of imbalances in muscle-tendon adaptation, demonstrated a significant reduction over time exclusively in the intervention group (pInt = 0.007). While knee extensor muscle strength increased in both groups by ~ 8% (pCon < 0.001, pInt = 0.064), only the intervention group showed a trend toward increased normalized tendon stiffness (pCon = 0.824, pInt = 0.051). PSF values did not change significantly in either group (p > 0.05). CONCLUSION: These results suggest that personalized exercise prescription can reduce muscle-tendon imbalances in athletes and could provide new opportunities for tendon injury prevention.

Structure and function of Achilles and patellar tendons following moderate slow resistance training in young and old men.

The aim of this study was to investigate the effect of aging and resistance training with a moderate load on the size and mechanical properties of the patellar (PT) and Achilles tendon (AT) and their associated aponeuroses; medial gastrocnemius (MG) and vastus lateralis (VL). Young (Y55; 24.8 ± 3.8 yrs, n = 11) and old men (O55; 70.0 ± 4.6 yrs, n = 13) were assigned to undergo a training program (12 weeks; 3 times/week) of moderate slow resistance training [55% of one repetition maximum (RM)] of the triceps surae and quadriceps muscles. Tendon dimensions were assessed using 1.5 T magnetic resonance imaging before and after 12 weeks. AT and PT cross sectional area (CSA) were determined every 10% of tendon length. Mechanical properties of the free AT, MG aponeurosis, PT, and VL aponeurosis were assessed using ultrasonography (deformation) and tendon force measurements. CSA of the AT but not PT was greater in O55 compared with Y55. At baseline, mechanical properties were generally lower in O55 than Y55 for AT, MG aponeurosis and VL aponeurosis (Young's modulus) but not for PT. CSA of the AT and PT increased equally in both groups following training. Further, for a given force, stiffness and Young's modulus also increased equally for VL aponeurosis and AT, for boths groups. The present study highlights that except for the PT, older men have lower tendon (AT, MG aponeurosis, and VL aponeurosis) mechanical properties than young men and 12-weeks of moderate slow resistance training appears sufficient to improve tendon size and mechanical adaptations in both young and older men. New and Noteworthy: These novel findings suggest that short-term moderate slow resistance training induces equal improvements in tendon size and mechanics regardless of age.

The relationship of proximal lateral collateral ligament hyperintensity with knee joint ligament and meniscus pathologies.

BACKGROUND: Hyperintensity in the proximal lateral collateral ligament (LCL) is often confusing. This appearance may be alone or accompany other pathologies. PURPOSE: To investigate the relationship between the signal intensity (SI) change in the proximal LCL and the knee joint pathologies. MATERIAL AND METHODS: The knee MRI scans taken between 2020 and 2022 were queried retrospectively. Patients with acute trauma, instability, knee surgery, or high-grade osteoarthritis were excluded. Included patients were divided into two groups as normal SI and increased SI according to proximal LCL. The difference in ligamentous and meniscal pathologies between the two groups was analyzed using a chi-square test. Inter-observer agreement analysis was performed on 50 randomly selected patients. RESULTS: A total of 351 patients (139 men [39.6%], 212 women [60.4%]; median age = 37 years; interquartile range = 67 years) were included. There were 114 (32.5%) LCLs with normal SI and 237 (67.5%) LCLs with increased SI. Normal SI and increased SI groups had a significant difference in terms of joint side, median age, patellar tendon SI, anterior cruciate ligament SI, and medial collateral ligament SI (P = 0.004, P = 0.004, P = 0.001, P = 0.011, P = 0.004, respectively). A significant difference between the results of two separate LCL examinations in coronal + axial and coronal-only planes (P <0.001). Inter-observer agreement was found to be good to excellent. CONCLUSION: Hyperintensity in the proximal LCL was more common on the right joint side, in older patients, and patients with hyperintensity in the proximal patellar tendon, anterior cruciate ligament, and medial collateral ligament. Evaluating the LCL only in the coronal plane overestimates the hyperintensity.

Evaluating the reliability of the lateral femoral condyle measuring methods by different modalities for patients with lateral patellar dislocation.

BACKGROUND: A variety of measurement methods and imaging modalities are in use to quantify the morphology of lateral femoral condyle (LFC), but the most reliable method remains elusive in patients with lateral patellar dislocation (LPD). The purpose of this study was to determine the intra- and inter-observer reliability of different measurement methods for evaluating the morphology of LFC on different imaging modalities in patients with LPD. METHODS: Seventy-three patients with LPD were included. Four parameters for quantifying the morphology of LFC were retrospectively measured by three observers on MRI, sagittal CT image, conventional radiograph (CR), and three-dimensional CT (3D-CT). The intra-class correlation coefficient was calculated to determine the intra- and inter-observer reliability. Bland-Altman analysis was conducted to identify the bias between observers. RESULTS: The lateral femoral condyle index (LFCI) showed better intra- and inter-observer reliability on MRI and 3D-CT than on CR and sagittal CT images. The mean difference in the LFCI between observers was lowest on 3D-CT (0.047), higher on MRI (0.053), and highest on sagittal CT images (0.062). The LFCI was associated with the lateral femoral condyle ratio (ρ = 0.422, P = 0.022), lateral condyle index (r = 0.413, P = 0.037), and lateral femoral condyle distance (r = 0.459, P = 0.014). The LFCI could be reliably measured by MRI and 3D-CT. CONCLUSION: The LFCI could be reliably measured by MRI and 3D-CT. The LFCI was associated with both the height and length of LFC and could serve as a comprehensive parameter for quantifying the morphology of LFC in patients with LPD.

Patellar osteochondritis dissecans: maturation-dependent patellofemoral joint characteristics.

BACKGROUND: The likelihood of healing of osteochondritis dissecans decreases with skeletal maturity and there are theories that abnormal biomechanical forces contribute to the development and progression of these lesions. OBJECTIVE: To characterize, according to regional skeletal maturity, the morphology and alignment indices of the patellofemoral joint on MRI in patients with patellar osteochondritis dissecans. MATERIALS AND METHODS: MRI examinations of patients with patellar osteochondritis dissecans obtained between January 2008 and May 2023 were retrospectively reviewed to determine regional skeletal maturity, osteochondritis dissecans lesion size and location, patellar and trochlear morphology (Wiberg/Dejour classifications), and to calculate trochlear sulcus angles, trochlear depth index, lateral trochlear inclination, Insall-Salvati index, Caton-Deschamps index, patellar tendon-lateral trochlear ridge, and tibial tubercle-trochlear groove distances. Values were compared between skeletally immature and mature groups. RESULTS: Sixty-eight children (22 girls, 46 boys, age: 14.0 ± 1.7 years) yielded 74 knees with patellar osteochondritis dissecans lesions, 14 (19%) of which were skeletally mature. The most common anatomic location was over the central patella [median ridge (34/74 - 46%) on the axial images and over the middle third (45/74 - 61%) on the sagittal images]. Overall, mean trochlear sulcus angle (high, 151 ± 11°), trochlear depth index (low, 2.8 ± 1.4 mm), and Insall-Salvati index (borderline, 1.3 ± 0.1) were abnormal for the entire sample. Skeletally mature knees were significantly more likely to have higher (more dysplastic) Dejour types when compared to skeletally immature knees (p < 0.01). Knees in the mature group, compared to immature, had significantly more abnormal mean lateral trochlear inclination (15 ± 8° vs. 19 ± 6°, p = 0.03) and patellar tendon-lateral trochlear ridge distance (5.55 ± 4.31 mm vs. 2.89 ± 4.69 mm, p = 0.04). Half of the knees had ≥ 4 abnormal features that predispose to patellofemoral maltracking; mature knees were significantly (p = 0.02) more likely to have a higher number of abnormal features (> 6 features, 7/14, 50.0%) versus immature knees (0-3 features, 33/60, 55.0%). CONCLUSION: In children with patellar osteochondritis dissecans, abnormal patellofemoral morphology and alignment indices were common in all patients and more severe in mature knees.

Arthroscopic medial patellofemoral ligament reconstruction with polyethylene suture combined with medial retinaculum plication for the treatment of acute patellar dislocation in young and middle-aged patients with a follow-up of at least 2 years.

PURPOSE: The purpose of this study was to propose a surgical technique for arthroscopic medial patellofemoral ligament (MPFL) reconstruction with polyethylene suture combined with medial retinaculum plication and to evaluate the efficacy of this surgical technique in the treatment of acute patellar dislocation. METHODS: Clinical data of patients with acute patellar dislocations treated with arthroscopic MPFL reconstruction with polyethylene tape (FiberTape) combined with medial support band compression were analyzed retrospectively from January 2018 to January 2021. The mean age of the patients was 25.15 ± 4.66 years; the mean follow-up time was 27.5 (24-36) months. Clinical evaluation consisted of apprehension test results, patellar extrapolation test results, Lysholm score, Kujala score, and IKDC score, the Patellar lateral shift distance and patellar tilt angle (PTA) measured by CT scan. RESULTS: All patients had no recurrent patellar dislocation or subluxation after surgery, and the apprehension test was negative. In all patients, the Kujala score (36.0 ± 9.9 vs. 98.2 ± 3.1), the IKDC score (48.6 ± 7.0 vs. 90.6 ± 4.4) and the Lysholm score (32.8 ± 10.4 vs. 96.7 ± 3.1) had improved at the 24-month follow up (P < 0.05). In addition, PTA was significantly lower at the 12-month follow-up and 24-giving-month follow-up compared to the preoperative period (P < 0.05, Table 2). The patellar lateral shift distance decreased from 14.94 ± 6.11 mm preoperatively to 3.00 ± 1.40 mm (12-month follow up) and 3.26 ± 1.37 mm (24-month follow up), respectively. CONCLUSION: Arthroscopic MPFL reconstruction with polyethylene suture combined with medial retinaculum plication is a safe and reliable surgical technique for the treatment of acute patellar dislocation in young and middle-aged patients. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Effect of a single versus serial platelet-rich plasma injection on the healing of acute patellar tendon defect: an experimental study.

BACKGROUND: There is no consensus on the frequency and timing of platelet-rich plasma (PRP) injection in tendon healing. We aimed to evaluate the effectiveness of single versus multiple PRP injections in the healing of patellar tendon defects in the experimental model, through histological and biomechanical investigation. METHODS: Forty-four male skeletally mature Dutch rabbits were randomly divided into the five study groups ( A, B,C, D,E). After creating a longitudinal acute patellar tendon defect on both knees (One-third the width of the patella tendon), the right legs of the rabbits were used as the intervention group and the left legs as the control groups. Animals in groups A, B, and C were euthanized on days 7, 14, and 28, respectively, after the first PRP injection. Animals in group D received the second PRP injection on day 10 and was euthanized on day 14. Animals in group D received the second and third PRP injections on days 10 and 20, respectively, and were euthanized on day 28. The outcomes were evaluated histologically (modification of Movin's Grading) and biomechanically. RESULTS: The inflammatory condition was exaggerated in groups D and E. Load at failure was higher in the non-injected side of groups D and E, while there was no significant difference between the right and left legs of the three groups A, B and C. In other word, groups with a single PRP injection were more resistant to the increasing load compared to the groups with multiple PRP injections. CONCLUSIONS: PRP improves tendon healing if injected early after injury, while its injection after the initial phase of injury hampers tendon healing. In addition, a single PRP injection seems to be more effective than multiple PRP injection. Therefore, in cases where PRP injection is indicated for tendon repair, such as acute tendon injury, we recommend using a single PRP injection during tendon repair surgery.

The vastus medialis oblique compensates in current patellar dislocation patients with the increased femoral anteversion.

PURPOSE: The purpose of this study was to investigate whether the vastus medialis oblique (VMO) muscle compensates in patellar dislocation (PD) patients with the increased femoral anteversion angle (FAA). METHODS: Between 2021 and 2024, we included 60 patients with recurrent PD (RPD group). Inclusion criteria were at least two episodes of PD, as well as complete CT scans of the knee and hip. Exclusion criteria included traumatic or habitual dislocation, previous knee surgery, etc. Of these patients, 30 with excessive FAA (≥ 30°) were assigned to the A group, and 30 without excessive FAA (< 30°) to the B group. A control group of 120 patients without patellofemoral disorders was also included (C group). The cross-sectional areas of the VMO and vastus lateralis muscle (VLM) were measured 20 mm above the patella on CT scans, and the VMO/VLM area ratio was calculated. The correlation between FAA and the VMO/VLM ratio was analyzed. RESULTS: The RPD group had a significantly larger FAA (15.0 ± 1.9° vs. 30.1 ± 9.6°, P = 0.040) and a smaller VMO/VLM ratio (4.2 ± 1.5 vs. 3.5 ± 1.0, P = 0.014) compared to the C group. Within the RPD group, the A group had a higher VMO/VLM ratio than the B group (4.0 ± 1.1 vs. 3.0 ± 0.7, P = 0.029). The B group's VMO/VLM ratio was lower than that of the C group (3.0 ± 0.7 vs. 4.2 ± 1.5, P = 0.004). However, there was no significant difference in the VMO/VLM ratio between the A group and the C group. The VMO/VLM ratio showed a moderate positive correlation with FAA in the RPD group, with a correlation coefficient of r = 0.4 (P = 0.012), indicating a statistically significant relationship between the two. CONCLUSION: Patients with recurrent PD showed a smaller VMO/VLM ratio compared to controls. Increased FAA was correlated with compensatory thickening of the VMO and a higher VMO/VLM ratio in PD patients. This suggests that increased FAA may drive biomechanical adaptations in the quadriceps, stabilizing the patella. Clinicians should consider changes in FAA when assessing and treating PD. LEVEL OF EVIDENCE: Level III.

Acute patellar dislocation: how skeletal maturity affects patterns of injury.

OBJECTIVE: The main objective of this study was to understand the role of skeletal maturity in the different patterns of osteochondral and ligamentous injuries after an acute lateral patellar dislocation. MATERIALS AND METHODS: Two radiologists independently reviewed MRIs of 212 knees performed after an acute lateral patellar dislocation to evaluate the presence of high-grade patellar osteochondral injury, femoral osteochondral injury, and medial patellofemoral ligament injury. The association of skeletal maturity (indicated by a closed distal femoral physis), age, sex, and first-time versus recurrent dislocation with each of these various lesions was analyzed using Chi-square or T test, and multivariable logistic regression with estimation of odds ratios (OR). RESULTS: Skeletal maturity was significantly associated with high-grade patellar osteochondral injury [OR=2.72 (95% CI 1.00, 7.36); p=0.049] and femoral-side MPFL tear [OR=2.34 (95% CI 1.05, 5.25); p=0.039]. Skeletal immaturity was significantly associated with patellar-side MPFL tear [OR=0.35 (95% CI 0.14, 0.90); p=0.029]. CONCLUSION: Patterns of injury to the patella and medial patellofemoral ligament vary notably between the skeletally immature and mature, and these variations may be explained by the inherent weakness of the patellar secondary physis.

Tendon structure, clinical tests, and pain during-loading in young female competitive gymnasts.

To examine the relationship between Achilles-tendon (AT) and patellar-tendon (PT) structure, clinical-examination and tendon pain in young gymnasts; and, to explore the associations between these factors and age, maturation, and training-load. Two hundred and seventy-four female gymnasts (aged 12.1±1.9 yrs) were assessed for anthropometric measures, pubertal-stage, and training-load. They had clinical-tests (pain-on-palpation for AT and pain-on-palpation and Royal-London Hospital-Test for PT), were asked about tendon-pain during-loading and were assessed for tendon-structure. Gymnasts with positive clinical-tests (with and without pain during-loading) presented a significantly higher prevalence of disorganized AT and PT compared to gymnasts with negative clinical-tests (with and without pain during-loading) (p<0.05). A significant pubertyXpositive clinical-test interaction was found for disorganized PT structure, whereby a disorganized structure was more prevalent among post-pubertal gymnasts with positive clinical-tests compared to pre-pubertal participants with negative clinical-tests (F(1, 263)=9.436, p=0.002). In gymnasts with positive clinical-tests, significant correlations were found between disorganized AT and PT structures and age, and training-load (p<0.05). An increased prevalence of disorganized tendon structure (regardless of pain during-loading) was seen in participants with positive clinical-tests. This disorganized tendon-structure was found to be significantly related to increased age, post-pubertal stage, and higher training hours in gymnasts with positive clinical-tests.

Application of a machine learning and optimization method to predict patellofemoral instability risk factors in children and adolescents.

PURPOSE: Conservative treatment remains the standard approach for first-time patellar dislocations. While risk factors for patellofemoral instability, a common paediatric injury, are well-established in adults, data concerning the progression of paediatric recurrent patellar dislocation remain scarce. A reproducible method was developed to quantitatively assess the patellofemoral morphology and anatomic risk factors in paediatric patients using magnetic resonance imaging (MRI) and machine learning analysis. METHODS: Data were analyzed from a retrospective review (2005-2022) of paediatric patients diagnosed with acute lateral patellar dislocation (54 patients) who underwent MRI and were compared with an age-based control group (54 patients). Patellofemoral, tibial, tibiofemoral and patellar height parameters were measured. Differences between groups were analyzed with respect to MRI parameters. The potential diagnostic utility of the parameters was assessed via machine learning and genetic algorithm analyses. RESULTS: Significant differences were observed between the two groups in six patellofemoral morphological parameters. Regarding patellar height morphological parameters, all methods exhibited significant between-group differences. Among the tibia and tibiofemoral morphological parameters, only the tibial tubercle-trochlear groove distance exhibited significant differences between the two groups. No sex-related differences were present. Significant variations were observed in patellar height parameters, particularly in the Koshino-Sugimoto (KS) index, which had the highest area under the curve (AUC: 0.87). Using genetic algorithms and logistic regression, our model excelled with seven key independent variables. CONCLUSION: KS index and Wiberg index had the strongest association with lateral patellar dislocation. An optimized logistic regression model achieved an AUC of 0.934. Such performance is considered clinically relevant, indicating the model's effectiveness for the intended application. LEVEL OF EVIDENCE: Level Ⅲ.

Minimal effect of scanning parameters on ultrasound shear wave elastography variability in tendons.

PURPOSE: Ultrasound shear wave elastography has potential use in assessing tendon tissue; however, reducing measurement variability remains challenging. The primary purpose of this study was to identify the amount of variability accounted for by ultrasound parameter (frequency, harmonics and CrossXBeam) settings on shear wave speed at two testing sites. METHODS: Shear wave elastography images of the Achilles tendon were obtained from individuals with healthy tendons (n = 28) at two testing sites with standardised image acquisition/postprocessing protocols. Images were acquired at a range of frequencies (7-15 MHz) with CrossXBeam (a filtering technique) and harmonics settings toggled on and off. Variance decomposition analysis was performed to identify the amount of variability in shear wave speed accounted for by scan acquisition settings and testing sites. RESULTS: Shear wave speed variance was primarily attributed to participants (56.87% of variance; residual error: 35%). All scanning parameters, testing site and interaction terms each accounted for less than 2.5% of the variance. A statistically significant, negative relationship was observed between shear wave speed and image quality (p = 0.001) suggesting poor image quality yields higher shear wave speed estimates. CONCLUSION: The findings of this study suggest that natural variation in Achilles tendon mechanics between individuals without tendon pathology accounts for most of the shear wave speed variability. Optimising image quality, which may be observed in higher frequencies, should be considered to improve shear wave speed estimation. Clinically, this study highlights the need to take multiple images, maintain consistent ultrasound settings when tracking patient progress over time and use caution when comparing raw values from tendon scans performed in different clinics with shear wave elastography. LEVEL OF EVIDENCE: Level III.

Three different patellar fixation techniques yield similar clinical and radiological outcomes in recurrent patellar dislocation undergoing medial patellofemoral ligament reconstruction.

PURPOSE: The purpose of this study was to evaluate and compare the clinical and radiological outcomes of three different patellar fixation techniques on medial patellofemoral ligament reconstruction (MPFLR) in the treatment of patellar dislocation (PD). METHODS: Between 2015 and 2020, 130 patients with recurrent PD who underwent surgical reconstruction were eligible for this retrospective study: 48 patients were treated with the semi-tunnel bone bridge fixation technique (Group A), 42 patients were treated with the suture anchor fixation technique (Group B) and 40 patients were treated with the transpatellar tunnel fixation technique (Group C). Clinical outcomes included functional outcomes (Kujala, Lysholm and International Knee Documentation Committee scores), activity levels (Tegner activity score and return to sports), physical examinations, patellar re-dislocation rate and complications. Radiological outcomes included patellar congruence angle, patellar tilt angle, lateral patellar translation and lateral patellar angle. RESULTS: All clinical and radiological outcomes improved significantly in all groups, without any significant difference among these three groups. At the final follow-up, no re-dislocation occurred, and all groups achieved a successful return to sports. However, the semi-tunnel bone bridge and suture anchor fixation techniques showed statistically higher Tegner activity scores (p = 0.004) and shorter time from surgery to return to sports (p = 0.007) than the transpatellar tunnel fixation technique. CONCLUSION: The three MPFLR patellar fixation techniques achieved favourable and comparable clinical and radiological outcomes in the treatment of PD. Compared with the transpatellar tunnel fixation technique, the semi-tunnel bone bridge and suture anchor fixation techniques may be more effective with higher activity levels. LEVEL OF EVIDENCE: Level III.

Recurrent patellar dislocation patients with high-grade J-sign have multiple structural bone abnormalities in the lower limbs.

PURPOSE: To explore the relationship between preoperative J-sign grading and structural bone abnormalities in patients with recurrent patellar dislocation (RPD). METHODS: A retrospective study was conducted on RPD patients over 5 years. Patients were categorised based on J-sign grade into low (J- and J1+), moderate (J2+) and high groups (J3+). Trochlear dysplasia (TD) and osseous structures (femoral anteversion angle [FAA], knee torsion, tibial tuberosity-trochlear groove [TT-TG] distance, Caton-Deschamps index) were assessed and grouped according to risk factor thresholds. The χ2 test was used to compare composition ratio differences of structural bone abnormalities among the groups. RESULTS: A total of 256 patients were included, with 206 (80.5%) females. The distribution of J-sign grade was as follows: 89 knees (34.8%) of low grade, 86 moderate (33.6%) and 81 high (31.6%). Among the five structural bone abnormalities, TD was the most common with a prevalence of 78.5%, followed by increased TT-TG at 47.4%. Excessive tibiofemoral rotation had the lowest occurrence at 28.9%. There were 173 (67.6%) patients who had two or more abnormalities, while 45 (17.6%) had four to five bony abnormalities. Among patients with any bony abnormality, the proportion of high-grade J-sign surpassed 40%. Patients with moderate and high-grade J-sign had more increased FAA and more pronounced patella alta (all p < 0.001). The proportion of excessive knee torsion and TD increased with increasing each J-sign grade, with the more notable tendency in knee torsion (high vs. moderate vs. low-grade: 61% vs. 22% vs 7%, p < 0.001). Furthermore, the higher J-sign grade was also associated with more combined bony abnormalities (p < 0.001). In the high-grade J-sign group, 90.2% of the knees had two or more bony risk factors and 40.7% had four or more, which were significantly higher than the moderate and low-grade J-sign groups (40.7% vs. 11.6% vs. 2.2%, p < 0.001). CONCLUSION: In patients with a high-grade J-sign, over 90% of the lower limbs had two or more structural bone risk factors, and more than 40% had four or more. These proportions were significantly higher compared to knees with low-grade and moderate J-sign. In clinical practice, when treating high-grade patellar mal-tracking, it is important to focus on and correct these strongly correlated abnormal bone structures. LEVEL OF EVIDENCE: Level III.

Habitual patellar dislocation exhibits less severe rotational deformities but poorer trochlear development and higher incidence of patella baja compared with recurrent patellar dislocation in skeletally mature patients.

PURPOSE: This study compared the radiological characteristics between habitual and recurrent patellar dislocation in skeletally mature patients. METHODS: From 2017 to 2019, 77 skeletally mature patients with habitual patellar dislocation were surgically treated at a single institution and reviewed retrospectively. A total of 55 knees from these patients were included in the habitual patellar dislocation group. During the same period, 55 knees with recurrent patellar dislocation were randomly selected from 242 patients and included in the recurrent patellar dislocation group. Various bony deformities were measured and compared between the two groups. Additionally, a subgroup analysis was conducted among patients with habitual patellar dislocation, comparing those with and without an 'invisible patella' observed on true lateral views with 30° of knee flexion. RESULTS: The femoral anteversion angle (21.8° vs. 26.3°, p = 0.041), tibiofemoral rotation angle (9.7° vs. 12.4°, p = 0.042) and external tibial rotation angle (24.3° vs. 29.6°, p = 0.001) in the habitual patellar dislocation group were significantly lower than those in the recurrent patellar dislocation group. 54% of knees in the habitual patellar dislocation group had a patella baja, and this was in sharp contrast to the recurrent patellar dislocation group in which none of the knees had a patella baja. 49.1% of knees in the habitual patellar dislocation group showed 'invisible patella' at 30° of knee flexion, and knees with 'invisible patella' had significantly higher tibial tubercle-trochlear groove (TT-TG) distance (30.4 vs. 19.8, p < 0.001) and tibiofemoral rotation angle (13.2° vs. 6.4°, p < 0.001) than knees with a visible patella. CONCLUSIONS: A distinct difference in bony anatomical features was observed between habitual and recurrent patellar dislocation in skeletally mature patients. Habitual patellar dislocation exhibited less severe rotational deformities of the lower extremity but showed poorer trochlear and patellar development, a larger TT-TG distance and a higher incidence of patella baja compared with recurrent patellar dislocation. LEVEL OF EVIDENCE: Level III.