Morphometric Parameters and MRI Morphological Changes of the Knee and Patella in Physically Active Adolescents

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.

Morphological analysis of patellofemoral joint in haemophilic arthropathy: A case-control study

INTRODUCTION

Knees affected by haemophilic arthropathy exhibit distinct differences in both bone morphology and soft tissue behaviour. This study aims to analyse the morphological characteristics of the distal femur and patellofemoral joint in patients with haemophilia in comparison to normal healthy population.

MATERIAL AND METHODS

Study was conducted as pair-matched case-control study with 43 individuals in both the haemophilia group and the control group. Patellar luxation, patellar tilt (PT), length of the patella in both axis (pAP, pML), depth and angle of trochlear sulcus (SD, SA), lateral trochlear inclination (LTI), medial and lateral femoral facet length (mFL, LFL), intercondylar depth (ID), transepicondylar axis (TEA) and lateral condyle length (LCL) were assessed on knee MRI. Correlation between Pettersson score and measured variables were also analysed.

RESULTS

PT was medial sided in 10 (23.2%) cases in haemophilic group. Mean values of pAP, pML, PT were significantly lower in haemophilia group (p < .001, p: .007, p = .001 respectively). There were no significant changes in SA (p = .628), SD (p = .340), LTI (p = .685), LFL (p = .241) and MFC-LFC (p = .770) whilst mFL was significantly longer in haemophilia group (p = .009). ID (p < .001), TEA (p = .007) and LCL (p = .001) were all shorter in haemophilia group. Pettersson score was inversely correlated with pAP, pML, ID, TEA, LCL, pML/SA and ID/LCL.

CONCLUSION

Morphological changes in haemophilic arthropathy involve a smaller and medially-tilted patella, narrowed lateral condyle and transepicondylar axis, combined with reduced intercondylar depth. These alterations must keep in mind especially in pre- and intraoperative assessments for arthroplasty procedures.

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.

Association between the most superior point of patella-entrance of femoral trochlea distance ratio (SP-ET index) and chondromalacia patella: an investigation via magnetic resonance imaging

PURPOSE

In this study, the effect of the most superior point of patella-entrance of femoral trochlea distance ratio (SP-ET index) on chondromalacia patella (CP) was investigated with 2 reviewers.

MATERIAL AND METHODS

A total of 348 knees of 308 patients were analysed retrospectively with magnetic resonance imaging (MRI). Patients with or without CP constituted the study and the control groups in this cross-sectional investigation. Two reviewers interpreted the dataset regarding the SP-ET index. This ratio was calculated as the distance between the most superior point of patella and the entrance of femoral trochlea (β) divided by the patellar articular surface length (α). The relationship between the SP-ET index and CP was presented using independent samples T-tests, and the intraclass correlation coefficient (ICC) was calculated to reveal the interobserver differences.

RESULTS

There was excellent agreement between the reviewers regarding α, β, and SP-ET values (ICC was 0.971, 0.964, and 0.943, respectively). Higher SP-ET values were obtained for patients with CP, in comparison with patients without any chondral lesion (p < 0.001). A significant, positive, and moderate level of correlation was revealed between SP-ET measurements and CP grades for the total study population.

CONCLUSIONS

SP-ET index showed high interobserver agreement and indicated a significant difference between patients with and without CP. Both reviewers' results indicated positive and significant correlation between the measured SP-ET values and different grades of CP for females, males, and the total study population.

Difference in quantitative MRI measurements of cartilage between Wiberg type III patella and stable patella based on a 3.0-T synthetic MRI sequence

Purpose

The purpose of this study was to investigate the difference between the quantitative MRI values of Wiberg type III and stable patellar cartilage, and to improve the accuracy of MRI quantification in early patellar cartilage damage.

Methods

The knee joints of 94 healthy volunteers were scanned by a GE Signa Pioneer 3.0-T synthetic MRI machine. According to the Wiberg classification, the patella was divided into types I-III. Types I-II made up the stable patella group, and type III made up the unstable patella group. Two radiologists independently measured patellar cartilage thickness and quantitative synthetic MRI values (T1, T2, PD) in both groups. Interobserver agreement for quantitative variables was assessed using the Bland-Altman method. A third radiologist assessed differences in measurements.

Results

The medial T2 and T1 value of Wiberg III patella did not show a normal distribution (all P > 0.05). Compared with the stable group, the Wiberg type III group had thinner cartilage of the medial surface of the patella (P < 0.05), lower cartilage T2 and PD values (P < 0.05), but a similar cartilage T1 value (P > 0.05). There was no significant difference in the cartilage thickness, T1, T2, or PD value of the lateral patella between the Wiberg type III and the stable group (P > 0.05).

Conclusion

There were certain differences in the cartilage thickness of the medial surface of the patella and the quantitative value of synthetic MRI in Wiberg type III patellas. Quantitative studies of patellar cartilage MRI measurements need to consider the influence of patellar morphology.