Trochlear Dysplasia as Shown by Increased Sulcus Angle Is Associated With Osteochondral Damage in Patients With Patellar Instability

Pediatric osteochondral fractures: clinical insights associate early diagnosis to early rehabilitation via arthroscopy

PURPOSE

This retrospective observational cohort analysis aims to address diagnostic and therapeutic challenges in managing osteochondral fractures (OCFs) resulting from acute patella dislocation and ankle sprains in children.

METHODS

The study includes 15 children treated for OCFs between January 2020 and July 2022. Data were obtained from medical records and analyzed using logistic regression.

RESULTS

The diagnostic and treatment algorithm involves detailed history, clinical examination, and imaging, with MRI guiding therapeutic decisions. Arthroscopic or mini open fixation led to successful rehabilitation, with 93% achieving full mobility at 9 months. Age was identified as a slight risk factor for free fragments in MRI, and arthroscopic management correlated with faster recovery at 3 months.

CONCLUSION

This study underscores the importance of immediate diagnosis and minimally invasive intervention for OCFs in children. Timely treatment, guided by a diagnostic algorithm, facilitates joint restoration and prevents degenerative consequences, ensuring a return to regular activities within a year postoperatively.

LEVEL OF EVIDENCE

IV.

Patellar Lateralization, Absence of Joint Hypermobility, and the Mechanism of Injury Are Associated With Osteochondral Fracture After First-time Acute Lateral Patellar Dislocation in Adolescents: An MRI-based Evaluation

BACKGROUND

Although the risk factors for patellofemoral dislocation are clearly defined, risk factors for osteochondral fracture (OCF) after patellar dislocation are not as well defined. The aim of this study was to investigate the risk factors for OCF by evaluating patients with and without OCF after first-time acute patellar dislocation.

METHODS

This multicenter study was conducted as a retrospective examination of the radiologic measurements on the magnetic resonance imaging of 306 patients. The patients were divided into the OCF group and non-OCF group, and OCFs were grouped according to whether the fracture was in the patella or femur. Patellar height, patellar lateralization, trochlear morphology, patellofemoral matching, and patella types were evaluated on patient magnetic resonance imaging. The presence of joint hypermobility in the patients was determined according to the Beighton scale score. The injury mechanisms of the patients were grouped as sports-related injuries, injuries resulting from simple falls, and injuries during daily activities.

RESULTS

A total of 120 OCFs were detected in 108 (35.2%) patients, of which 96 (80%) were in the patella and 24 (20%) in the femur. The rate of OCF after sports-related injuries was found to be significantly higher than in other injury mechanisms ( P =0.001). More joint hypermobility was detected in patients without OCF ( P =0.041). The measurements of tibial tubercle-trochlear groove, tibial tubercle-posterior cruciate ligament distance and lateral patellar displacement were statistically higher in cases with OCF ( P =0.001). In patients with normal joint mobility, the rate of OCF localization in the patella was significantly higher ( P =0.035). No correlation was found between any other parameters and OCF ( P >0.05). The absence of joint hypermobility and the measurements of tibial tubercle-trochlear groove distance, tibial tubercle-posterior cruciate ligament distance, and lateral patellar displacement were independent risk factors for the incidence of OCF according to the logistic regression analysis.

CONCLUSIONS

The absence of joint hypermobility and patellar lateralization are independent risk factors for the occurrence of OCF after first-time patellar dislocation. Sports-related injury is a nonindependent risk factor for the presence of OCF. In patients with normal joint mobility, the incidence of OCF in the patella is higher than in the femur. These important factors should be considered when evaluating patients and starting their treatment.

LEVEL OF EVIDENCE

Level III-retrospective cohort study.

Magnetic Resonance Image Findings and Potential Anatomic Risk Factors for Chodromalacia in Children and Adolescents Suffering from Non-Overload Atraumatic Knee Pain in the Ambulant Setting

PURPOSE

To evaluate magnetic resonance image (MRI) findings in children and adolescents suffering from knee pain without traumatic or physical overload history and to identify potential anatomic risk factors.

MATERIAL AND METHODS

A total of 507 MRIs of 6- to 20-year-old patients (251 males; 256 females) were evaluated with regard to detectable pathologies of the knee. The results were compared to a control group without pain (n = 73; 34 males; 39 females). A binary logistic regression model and t-tests for paired and unpaired samples were used to identify possible risk factors and significant anatomic differences of the study population.

RESULTS

In 348 patients (68.6%), at least one pathology was detected. The most commonly detected finding was chondromalacia of the patellofemoral (PF) joint (n = 205; 40.4%). Chondral lesions of the PF joint occurred significantly more often in knee pain patients than in the control group (40% vs. 11.0%; p = 0.001), especially in cases of a patella tilt angle > 5° (p ≤ 0.001), a bony sulcus angle > 150° (p = 0.002), a cartilaginous sulcus angle > 150° (p = 0.012), a lateral trochlear inclination < 11° (p ≤ 0.001), a lateralised patella (p = 0.023) and a Wiberg type II or III patella shape (p = 0.019). Moreover, a larger patella tilt angle (p = 0.021), a greater bony sulcus angle (p = 0.042), a larger cartilaginous sulcus angle (p = 0.038) and a lower value of the lateral trochlear inclination (p = 0.014) were detected in knee pain patients compared to the reference group.

CONCLUSION

Chondromalacia of the PF joint is frequently observed in children and adolescents suffering from non-overload atraumatic knee pain, whereby a patella tilt angle > 5°, a bony sulcus angle > 150°, a cartilaginous sulcus angle > 150°, a lateral trochlear inclination < 11°, a lateralised patella and a Wiberg type II or III patella shape seem to represent anatomic risk factors.

Comparison of Bone Bruise Pattern Epidemiology between Anterior Cruciate Ligament Rupture and Patellar Dislocation Patients-Implications of Injury Mechanism

Different bone bruise patterns observed using magnetic resonance imaging (MRI) after non-contact anterior cruciate ligament (ACL) rupture and lateral patellar dislocation may indicate different knee injury mechanisms. In this study, 77 ACL ruptures and 77 patellar dislocations in knee MR images taken from patients with bone bruises at our institution between August 2020 and March 2022 were selected and analyzed. In order to determine typical bone bruising patterns following by ACL rupture and patellar dislocation, sagittal- and transverse-plane images were used to determine bone bruise locations in the directions of medial-lateral and superior-inferior with MR images. The presence, intensity, and location of the bone bruises in specific areas of the femur and tibial after ACL rupture and patellar dislocation were recorded. Relative bone bruise patterns after ACL rupture and patellar dislocation were classified. The results showed that there were four kinds of bone bruise patterns (1-, 2-, 3-, and 4- bone bruises) after ACL rupture. The most common two patterns after ACL rupture were 3- bone bruises (including the lateral femoral condyle and both the lateral-medial tibial plateau, LF + BT; both the lateral-medial femoral condyle and the lateral tibial plateau, BF + LT; and the medial femoral condyle and both the medial and lateral tibial plateau, MF + BT) followed by 4- bone bruises (both the lateral-medial femoral condyle and the tibial plateau, BF + BT), 2- bone bruises (the lateral femoral condyle and tibial plateau, LF + LT; the medial femoral condyle and the lateral tibial plateau, MF + LT; the lateral femoral condyle and the medial tibial plateau, LF + MT; the medial femoral condyle and the tibial plateau, MF + MT; both the lateral-medial tibial plateau, 0 + BT), and 1- bone bruise (only the lateral tibial plateau, 0 + LT). There was only a 1- bone bruise (the latera femoral condyle and medial patella bone bruise) for patellar dislocation, and the most common pattern of patellar dislocation was in the inferior medial patella and the lateral anterior inferior femur. The results suggested that bone bruise patterns after ACL rupture and patellar dislocation are completely different. There were four kinds of bone bruise patterns after non-contact ACL rupture, while there was only one kind of bone bruise pattern after patellar dislocation in patients, which was in the inferior medial patella and lateral anterior inferior femur.

Medial condyle hypoplasia in adolescent and young adult patients with trochlear dysplasia: a retrospective study

Objective

To determine the association between medial femoral condyle hypoplasia and trochlear dysplasia by analyzing the knee magnetic resonance imaging scans of young patients with or without trochlear dysplasia.

Materials and Methods

This was a retrospective analysis of magnetic resonance imaging scans of the knees of young individuals (16-35 years of age): 30 patients with trochlear dysplasia and 30 individuals with no signs of patellofemoral instability. The ratios between the depth, width, and height of the medial and lateral femoral condyles (dLC/dMC, wLC/wMC, and hLC/hMC, respectively) were calculated, as was the ratio between the width of the medial condyle and the total width of the femur (wMC/FW). All of the values were determined in consensus by two radiologists.

Results

We evaluated 60 patients: 30 with trochlear dysplasia and 30 without. The mean dLC/dMC, wLC/wMC, and hLC/hMC ratios were higher in the patients than in the controls (p < 0.05), whereas the mean wMC/FW ratio was lower in the patients (p < 0.05). The optimal cutoff values, obtained by calculating the areas under the receiver operating characteristic curves, were 1.0465 for the dLC/dMC ratio (76% sensitivity and 63.3% specificity), 0.958 for the wLC/wMC ratio (80% sensitivity and 73.3% specificity), and 1.080 for the hLC/hMC ratio (93.3% sensitivity and 93.3% specificity).

Conclusion

Our findings confirm our hypothesis that trochlear dysplasia is associated with medial condyle hypoplasia.

Factors associated with an increased risk of osteochondral injuries after patellar dislocations: a systematic review

PURPOSE

The purpose of the study was to summarize the available evidence and identify risk factors for osteochondral injuries (OCIs) after patellar dislocations.

METHODS

A systematic literature review was conducted in PubMed, Embase, Web of Science, Cochrane Library, and China national knowledge infrastructure from inception to December 22, 2022, according to the preferred reporting items for systematic reviews and meta-analyses guidelines. Studies regarding risk factors for OCIs after patellar dislocations were included. Literature search, data extraction, and quality assessment were performed independently by two authors.

RESULTS

A total of 16 studies with 1945 patients were included. The risk factors for OCIs after patellar dislocation were categorized into four main categories, including demographic characteristics, patellar depth and position, femoral trochlear morphology, and other risk factors in this study. Five and three studies supported the idea that male sex and skeletal maturation may be risk factors, respectively. Normal femoral trochlea (two studies) and complete medial patellofemoral ligament (MPFL) injuries (two studies) may be associated with the development of OCIs. Three studies show that ligamentous laxity or joint hypermobility may prevent OCIs. Patellar depth and position (eight studies) may not be associated with the development of OCIs.

CONCLUSIONS

Based on the available evidence, an increased risk of OCIs following patellar dislocation may be associated with male sex and skeletal maturation. Furthermore, normal femoral trochlea and complete MPFL injuries may increase the risk of OCIs, while factors such as ligamentous laxity or joint hypermobility may reduce the risk.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II and IV studies.

Three-Dimensional Reproductions for Surgical Decision-Making in the Treatment of Recurrent Patella Dislocation

Patellofemoral instability may be attributed to a variety of soft tissue and osseous factors, of which dysplasia of the femoral trochlea significantly predisposes patients to recurrent instability events. Surgical planning and decision-making remain wholly predicated upon two-dimensional imaging-derived measurements and classification systems, although aberrant patellar tracking in the setting of trochlea dysplasia is a three-dimensional (3-D) complexity. 3-D reconstructions of the patellofemoral joint (PFJ) may be considered to better comprehend the complex anatomy of patients with recurrent patella dislocation and/or trochlea dysplasia. We describe a classification and integrated interpretation system by which these 3-D reproductions of the PFJ may be analyzed to enhance surgical decision making in the treatment of this condition to achieve optimal joint stability and long-term preservation.

A More Posterior Tibial Tubercle (Decreased Sagittal Tibial Tubercle-Trochlear Groove Distance) Is Significantly Associated With Patellofemoral Joint Degenerative Cartilage Change: A Deep Learning Analysis

PURPOSE

To perform patellofemoral joint (PFJ) geometric measurements on knee magnetic resonance imaging scans and determine their relations with chondral lesions in a multicenter cohort using deep learning.

METHODS

The sagittal tibial tubercle-trochlear groove (sTTTG) distance, tibial tubercle-trochlear groove distance, trochlear sulcus angle, trochlear depth, Caton-Deschamps Index (CDI), and flexion angle were measured by use of deep learning-generated segmentations on a subset of the Osteoarthritis Initiative study with radiologist-graded PFJ cartilage grades (n = 2,461). Kruskal-Wallis H tests were performed to compare differences in PFJ morphology between subjects without PFJ osteoarthritis (OA) and those with PFJ OA. PFJ morphology was correlated with secondary outcomes of mean patellar cartilage thickness and mean patellar cartilage T2 relaxation time using linear regression models controlling for age, sex, and body mass index.

RESULTS

A total of 1,626 knees did not have PFJ OA, whereas 835 knees had PFJ OA. Knees without PFJ OA had an increased (anterior) sTTTG distance (mean ± standard deviation, 11.1 ± 12.8 mm) compared with knees with PFJ OA (8.4 ± 12.7 mm) (P < .001), indicating a more posterior tibial tubercle in subjects with PFJ OA. Knees without PFJ OA had a decreased sulcus angle (127.4° ± 7.1° vs 128.0° ± 8.4°, P = .01) and increased trochlear depth (9.1 ± 1.7 mm vs 9.0 ± 2.0 mm, P = .03) compared with knees with PFJ OA. Decreased patellar cartilage thickness was associated with decreased trochlear depth (β = 0.12, P = .002) and increased CDI (β = -0.07, P < .001). Increased patellar cartilage T2 relaxation time was correlated with decreased sTTTG distance (β = -0.08, P = .01), decreased sulcus angle (β = -0.12, P = .04), and decreased CDI (β = -0.12, P < .001).

CONCLUSIONS

PFJ OA, patellar cartilage thickness, and patellar cartilage T2 relaxation time were shown to be associated with the underlying geometries within the PFJ. This large longitudinal study highlights that a decreased sTTTG distance (i.e., a more posterior tibial tubercle) is significantly associated with PFJ degenerative cartilage change.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic trial.

Patellar Instability

➢

Certain anatomic factors, such as patella alta, increased tibial tubercle-trochlear groove distance, rotational deformity, and trochlear dysplasia, are associated with an increased risk of recurrent patellar instability.

➢

The presence of a preoperative J-sign is predictive of recurrent instability after operative management.

➢

Isolated medial patellofemoral ligament reconstruction may be considered on an individualized basis, considering whether the patient has anatomic abnormalities such as valgus malalignment, trochlear dysplasia, or patella alta in addition to the patient activity level.

➢

More complex operative management (bony or cartilaginous procedures) should be considered in patients with recurrent instability, malalignment, and certain anatomic factors.

Patterns of Associated Knee Ligament and Chondral Injuries in First-Time Traumatic Patellar Dislocation: A Retrospective Magnetic Resonance Imaging (MRI) -Based Study

Introduction First-time acute traumatic patellar dislocation, when managed without a knee magnetic resonance imaging (MRI) scan, may lead to missed diagnoses of important associated knee injuries. The aim of this study was to ascertain the incidence of associated ligamentous and cartilaginous injuries in first-time traumatic patella dislocation. Methods  This was a five-year retrospective study on patients aged 16-45 who had knee MRI scans showing the characteristic bone bruise patterns seen in traumatic lateral patellar dislocation. Anonymized data from the hospital picture archiving and communication system (PACS) was obtained with each scan reviewed by a consultant radiologist, a fellowship-trained orthopaedic knee specialist, and an orthopaedic registrar or resident. Results  A total of 200 knee MRI scans were screened. 61 eligible knee MRI scans were included in the study. The patients' ages ranged from 16 to 42 years old, with a mean of 25 years. 73.8% were male. A medial patellofemoral ligament (MPFL) tear or rupture occurred in 58 of 61 knees (95%) with MPFL attenuation in three (5%) injured knees. Meniscal injuries were identified in 5 of 61 knees (8.2%), medial collateral ligament (MCL) injuries in 11 of 61 knees (18%), osteochondral injuries and loose bodies in 17 of 61 knees (27.9%), and anterior cruciate ligament (ACL) injury in one knee (1.6%). Conclusions  This single-centre MRI-based study has provided information on the incidence of associated chondral and ligamentous injuries in patients with first-time acute traumatic patellar dislocation. This information will be useful for clinicians when counselling patients and will add to the available literature on this injury. An MRI scan should be obtained in cases of suspected first-time traumatic patellar dislocations, especially in active young patients, due to the incidence of other associated traumatic knee lesions that might need surgical treatment and lead to persisting knee symptoms if neglected.

Can Traditional Straight-leg Swaddling Influence Developmental Dysplasia of the Femoral Trochlea? An In Vivo Study in Rats

BACKGROUND

It has been reported that trochlear dysplasia occurs very early in development, and environmental factors like swaddling may cause developmental dysplasia of the hip, which is associated with a shallower trochlear groove. However, to our knowledge, there are no definitive studies about the relationship between trochlear dysplasia and traditional straight-leg swaddling.

QUESTIONS/PURPOSES

Using a rat model of femoral trochlear dysplasia, we asked: Does straight-leg swaddling for 1 and 2 weeks in newborn Wistar rats alter the femoral trochlea with respect to (1) gross morphology, (2) histologic appearance, as well as (3) trochlear sulcus angle, width, and depth?

METHODS

Eighty-four newborn Wistar rats (44 females and 40 males) were divided into two equal groups: 42 in the unswaddled group and 42 in the swaddled group; each group was comprised of 22 females and 20 males. In the swaddled group, the rats were wrapped in surgical tape to maintain hip and knee extension to simulate traditional human straight-leg swaddling. To determine whether longer periods of swaddling were associated with more severe trochlear dysplasia, 21 rats in each group were euthanized at 1 and 2 weeks, respectively, and the gross morphology of the femoral trochlea was observed by one observer blinded to condition. Then hematoxylin and eosin staining of the femoral trochlea was performed and the distribution and number of the chondrocytes of the trochlear groove were viewed through a microscope. The trochlear sulcus angles, depth, and width were measured by an experienced technician blinded to condition.

RESULTS

By observing the gross morphology, we found that the trochlear groove in the swaddled group became qualitatively flatter compared with the unswaddled group at 1 week, and at 2 weeks, the trochlear groove became much shallower. At 1 and 2 weeks, histologic examinations showed obvious qualitative changes in the distribution and number of chondrocytes of the trochlear groove in the swaddled than in the unswaddled groups. In the swaddled group, trochlear dysplasia was more common at 2 weeks, occurring in 62% (26 of 42 [16 of 22 females and 10 of 22 males]) versus 33% (14 of 42 [8 of 22 females and 6 of 20 males]) at 1 week. At 1 week, the swaddled group showed more trochlear dysplasia compared with the unswaddled group as measured by angle of the trochlear groove (137° ± 6° versus 132°± 3.6°, mean difference 5° [95% confidence interval 2.9° to 7.2°]; p < 0.001), depth of the trochlear grove (0.28 ± 0.04 mm versus 0.31 ± 0.02 mm, mean difference 0.03 mm [95% CI 0.01 to 0.04]; p < 0.001). At 2 weeks, the swaddled group showed more severe trochlear dysplasia than at 1 week compared with the unswaddled group as measured by the angle of the trochlear groove (135° ± 6.0° versus 128° ± 4.8°, mean difference 7° [95% CI 5.7° to 10.4°]; p < 0.001), depth of the trochlear grove (0.32 ± 0.04 mm versus 0.36 ± 0.02 mm, mean difference 0.04 mm [95% CI 0.03 to 0.06]; p < 0.001). There was no difference in the width of the trochlear sulcus between the swaddled and the unswaddled groups at 1 week (1.29 ± 0.14 mm versus 1.30 ± 0.12 mm, mean difference 0.01 mm [95% CI -0.05 to 0.07]; p = 0.73) and 2 weeks (1.55 ± 0.12 mm versus 1.56 ± 0.12 mm, mean difference 0.01 mm [95% CI -0.05 to 0.07]; p = 0.70).

CONCLUSION

Our results indicate that traditional straight-leg swaddling could induce trochlear dysplasia in this model of newborn rats. With an increased swaddling time of 2 weeks, more severe trochlear dysplasia appeared in the swaddled group.

CLINICAL RELEVANCE

Our findings suggest that traditional straight-leg swaddling may impair trochlear development in the human neonate and lead to trochlear dysplasia in infants. We believe our animal model will be useful in future work to observe and study the change of cartilage and subchondral bone in each stage of the development of trochlear dysplasia and the change of mechanotransduction-associated proteins (such as, TRPV4/ Piezo1 and CollagenⅡ) in cartilage and subchondral osteocytes. It will also be helpful to further investigate the mechanism of developmental femoral trochlea dysplasia caused by biomechanical changes.