Prevalence and a correlation analysis of discoid meniscus and femoral trochlear dysplasia

BACKGROUND

Discoid meniscus (DM) and femoral trochlear dysplasia (FTD) are common knee disorders. Both as congenital malformation, whether there is a connection between them is unclear and the research on their prevalence in the general population is inadequate. This study aimed to investigate the prevalence of FTD and DM in the general population through a large sample size, and to explore the relationship between them.

STUDY DESIGN

Retrospective study.

METHODS

Patients undergoing knee magnetic resonance imaging (MRI) examinations at our outpatient clinic were screened and 1003 patients were enrolled in DM group with 989 patients in non-DM (NDM) group. The type of DM and FTD was classified with Watanabe classification and Dejour's classification, respectively. The prevalence of FTD and DM in the general population and the relationship between them were evaluated.

RESULTS

The prevalence of DM and FTD was 10.0% and 14.5%, respectively. The overall percentage of FTD was higher in DM group (P < 0.001). The DM group has a higher percentage of all types of FTD except type D (P < 0.05), and a higher percentage of both low- and high-grade FTD (P < 0.001). There were 633 cases of type I DM and 370 cases of type II DM. The overall percentage of FTD was not significantly different between the two types (P = 0.106). No significant difference was detected for all types of FTD except type B (P < 0.05). The Type I DM group has a significant higher percentage of high-grade FTD than Type II group (P < 0.05).

CONCLUSION

Patients with a DM are more likely to have FTD regardless of the type of DM, while those with a type I DM are more prone to have a high grade FTD.

Deep learning-assisted diagnosis of femoral trochlear dysplasia based on magnetic resonance imaging measurements

BACKGROUND

Femoral trochlear dysplasia (FTD) is an important risk factor for patellar instability. Dejour classification is widely used at present and relies on standard lateral X-rays, which are not common in clinical work. Therefore, magnetic resonance imaging (MRI) has become the first choice for the diagnosis of FTD. However, manually measuring is tedious, time-consuming, and easily produces great variability.

AIM

To use artificial intelligence (AI) to assist diagnosing FTD on MRI images and to evaluate its reliability.

METHODS

We searched 464 knee MRI cases between January 2019 and December 2020, including FTD (n = 202) and normal trochlea (n = 252). This paper adopts the heatmap regression method to detect the key points network. For the final evaluation, several metrics (accuracy, sensitivity, specificity, etc.) were calculated.

RESULTS

The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of the AI model ranged from 0.74-0.96. All values were superior to junior doctors and intermediate doctors, similar to senior doctors. However, diagnostic time was much lower than that of junior doctors and intermediate doctors.

CONCLUSION

The diagnosis of FTD on knee MRI can be aided by AI and can be achieved with a high level of accuracy.

Abnormal patellar loading may lead to femoral trochlear dysplasia: an experimental study of patellar hypermobility and patellar dislocation in growing rats

BACKGROUND

This animal study aimed to explore the effects of patellar hypermobility and patellar dislocation on the developing femoral trochlea.

METHODS

Seventy-two 3-week-old Wistar rats were randomly divided into three groups. The sham group (SG) underwent simple incision and suture of the skin and subcutaneous tissue; the patellar hypermobility group (PHG) underwent medial and lateral retinacular release and pie-crusting technique for the patellar ligament; the patellar dislocation group (PDG) underwent plication of the medial patellofemoral retinaculum. Twelve rats in each group were euthanized at 3 and 6 weeks postoperatively, respectively, and specimens were collected. The bony sulcus angle (BSA), cartilaginous sulcus angle (CSA), trochlear sulcus depth (TSD), and thickness of the cartilage on the lateral facet (CTL), medial facet (CTM), and center (CTC) of the trochlea were measured on hematoxylin and eosin-stained sections.

RESULTS

In the PHG and PDG, the femoral condyles became blunt, the trochlear groove became shallower, and cartilage became thicker compared with the SG. Compared with the SG, the PHG and PDG had significantly larger BSA and CSA values at 3 (p < 0.05) and 6 weeks (p < 0.005), and a significantly shallower TSD (p < 0.05). At 3 weeks, all cartilage thicknesses in the PHG and the CTC and CTM in the PDG were significantly thinner than in the SG (PHG vs. SG: p = 0.009 for CTL, p < 0.001 for CTM, p = 0.003 for CTC; PDG vs. SG: p = 0.028 for CTC, p = 0.048 for CTM). At 6 weeks, the CTC was thicker in the PHG and PDG than the SG (PHG vs. SG: p = 0.044; PDG vs. SG: p = 0.027), and the CTL was thinner in the PDG than the SG (p = 0.044).

CONCLUSION

Patellar hypermobility and patellar dislocation may result in trochlear dysplasia that worsens with age. Excessive or insufficient loading leads to trochlear dysplasia.

[Quantitative evaluation of the relationship between femoral trochlear dysplasia and the degeneration of the patellofemoral cartilage by using T2mapping]

Objective: To evaluate the relationship between the femoral trochlear dysplasia(FTD) and the degeneration of the patellofemoral cartilage by using MR T2mapping technique. Methods: Sixty two subjects with FTD(aged 18-45 years) were enrolled in Tianjin First Center Hospital from January 2016 to December 2017,the controls which both age and gender were matched.T2mapping scan were aquired for each subject and control. Compare the differences of the T2mapping values for each area between subjects and controls, and compare Dejour types of femoral trochlear in different age groups, respectively. Results: The T2mapping value of subjects was significant lower than controls: the superficial-femoral-lateral layer (sFL) (P=0.000) and the superficial-patella-lateral layer (sPL) (P=0.009). In the group of age less than 30 years, the T2mapping value of subjects was significant lower than controls:sFL (P=0.001) and sPL (P=0.015). In group of age greater than 30 years, the T2mapping value of subjects was significant lower than controls: sFL (P=0.035). In difference Dejour types of FTD, the T2mapping value of type B-D was lowest in sFL(P=0.014),sPL(P=0.000), the superficial-patella-medial layer (sPM) (P=0.020) and the the T2mapping value of type B-D was highest in the deep-femoral-medial layer (dFM) (P=0.006). The difference was statistically significant, P<0.05. Conclusion: The FTD might cause the early degeneration of patellofemoral cartilage, which significantly appear in the young age; The type B-D of FTD is more likely to cause the wider range of superficial cartilage injure and involved some part of deep layer; the injure shows dehydration change in superficial cartilage and edema in deep layer.

Femoral trochlear dysplasia after patellar dislocation in rabbits

BACKGROUND

The aim of this study was to investigate the effects of patellar dislocation on the development of the trochlear groove in rabbits.

METHODS

Eighty knees from forty one-month-old white rabbits were divided into three groups (sham surgery, experimental, control). Lateral patellar dislocation was established in the experimental group and the effect on the development of the trochlear groove was compared with that in the sham surgery and control groups. Computed tomography (CT) scans were conducted to measure the angle, width and depth of the trochlear groove one month and six months after surgery. Gross specimen examination, cross-sectional anatomy and histological observation were conducted to investigate the anatomical configuration of the femoral trochlea and the changes in cartilage tissue of the trochlear groove at six months after surgery.

RESULTS

At six months after surgery, CT scans showed a significant difference between the sham surgery group and the experimental group in the angle, width and depth of the trochlear groove. There were no significant differences between the sham surgery group and the control group. Gross specimen examination and cross-sectional anatomy indicated low lateral femoral trochlea and reduced height at the trochlear groove in the experimental group. The femoral trochlea was of normal appearance in the other two groups. Histological investigations showed that there were degenerative changes in the cartilage tissue of the femoral trochlea in the experimental group.

CONCLUSIONS

Secondary femoral trochlear dysplasia may be caused by patellar dislocation in a normally developing femoral trochlea. Patellar dislocation may be one of the causes of femoral trochlear dysplasia.