Update on imaging of the discoid meniscus

Clinical efficacy and pain follow-up after arthroscopic discoid meniscoplasty of the knee: a retrospective study

BACKGROUND

To assess the viability and efficiency of performing arthroscopic meniscoplasty in treating discoid meniscus (DM) in the knee joint.

METHODS

A total of 29 patients diagnosed with symptomatic lateral DM between October 2014 and December 2019 were included in the study. Among them, 7 patients with intact DM underwent arthroscopic discoid meniscoplasty (group A), while 22 patients with torn DM received arthroscopic DM plasty along with repair and suturing (group B). Both Visual Analog Scale (VAS) score and Lysholm score assessments were conducted preoperatively and postoperatively.

RESULT

The favorable and acceptable outcome rate was 85.71% in group A and 95.45% in group B (P > 0.05). The VAS scores post-operatively at each follow-up time point were consistently lower compared to pre-operative values, while the Lysholm knee function scores showed improvement. There were no significant differences in VAS score and Lysholm score between group A and group B at different stages (P > 0.05). Both surgical techniques (discoid meniscoplasty and discoid meniscoplasty combined with repair and suture) showed significant improvement in postoperative VAS score and Lysholm score, but there was no difference in outcomes between the two groups.

CONCLUSION

Overall, the two surgical techniques studied in this study (discoid meniscoplasty and discoid meniscoplasty combined with repair and suture) produced similar results in terms of pain reduction and improved knee function.

The Role of Ultrasound in the Diagnosis and Treatment of Meniscal Injuries

PURPOSE OF REVIEW

This review evaluates the current understanding of the role of ultrasound in the diagnosis and treatment of meniscal disorders.

RECENT FINDINGS

Ultrasound (US) demonstrates similar sensitivity and specificity when compared to magnetic resonance imaging in the evaluation of meniscal injuries when compared to arthroscopy. Meniscal extrusion (ME) under US can be a reliable metric to evaluate for meniscal root tears in knees with and without osteoarthritis (OA). Sonographic ME is associated with development of OA in knees without OA. US following allograft meniscal transplant may be useful in predicting graft failure. US findings can be used to screen for discoid menisci and may demonstrate snapping of a type 3 discoid lateral meniscus. Shear wave elastography for meniscal injuries is in its infancy; however, increased meniscal stiffness may be seen with meniscal degeneration. Perimeniscal corticosteroid injections may provide short term relief from meniscal symptoms, and intrameniscal platelet-rich plasma injections appear to be safe and effective up to three years. Ultrasound-assisted meniscal surgery may increase the safety of all inside repairs near the lateral root and may assist in assessing meniscal reduction following root repair. Diagnostic US can demonstrate with high accuracy a variety of meniscal pathologies and can be considered a screening tool. Newer technologies such as shear wave elastography may allow us to evaluate characteristics of meniscal tissue that is not possible on conventional imaging. US-guided (USG) treatment of meniscal injuries is possible and may be preferable to surgery for the initial treatment of degenerative meniscal lesions. USG or US-assisted meniscal surgery is in its infancy.

Age-based comparison of meniscal dimensions between an asymptomatic complete discoid lateral meniscus and normal meniscus: MRI evaluation

INTRODUCTION

This study aimed to evaluate the meniscal size of asymptomatic discoid lateral meniscus (DLM) and compare it with that of normal lateral meniscus (LM) and to compare changes in meniscal dimensions with age among patients with asymptomatic DLM and those with normal LM using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We retrospectively reviewed the medical records, including MRI data, of patients with asymptomatic DLM (DLM group) or normal LM (control group). Width and extrusion of both DLM and normal LM and tibial length were measured and compared using mid-coronal and mid-sagittal MR images. Meniscal size and sagittal and coronal meniscal ratio according to age, as well as differences between DLM and normal menisci, were also evaluated.

RESULTS

Thirty-four knees were included in the DLM group, whereas the control group comprised of 50 patients. The DLM group showed significantly less meniscal extrusion, greater coronal width, posterior capsule distance, sagittal meniscal length, and sagittal meniscal ratio than the control group (DLM: 0.1 ± 0.3 mm, 23.3 ± 2.2 mm, 5.4 ± 2.4 mm, 25.1 ± 2.8 mm, 61 ± 6%, and control: 0.4 ± 0.4 mm, 9.5 ± 2.3 mm, 2.5 ± 1.2 mm, 30.2 ± 2.6 mm, 71 ± 4%, respectively). The coronal meniscal ratio decreased with age in both the control (p = 0.001) and DLM (p = 0.037) groups. The sagittal meniscal ratio (p = 0.001) and minimum height (p = 0.04) decreased and the anterior capsule distance (p = 0.035), posterior capsule distance (p = 0.026), and entire sagittal length (p = 0.005) increased with age in the DLM group, while the distance between the meniscal inner margins (p = 0.019) increased with age in the control group.

CONCLUSIONS

The meniscal ratio in the sagittal plane of the DLM group was significantly lower than that of the control group. The sagittal meniscal ratio of asymptomatic DLM decreased with age, indicating that the size of asymptomatic DLM does not change with age.

LEVEL OF EVIDENCE

III: Retrospective comparative study.

Comparative analysis of discoid lateral meniscus size: a distinction between symptomatic and asymptomatic cases

PURPOSE

This study evaluated the differences in meniscal sizes and occupancy between symptomatic and asymptomatic patients diagnosed with discoid lateral meniscus (DLM) using magnetic resonance imaging (MRI) to understand how these variations relate to the presence of symptoms and the patients' age.

METHODS

A retrospective review of 98 patients with DLM was conducted, excluding those with meniscal displacement. Both the width and extrusion of DLM and the percentage of the meniscus to the tibia were measured using mid-coronal and mid-sagittal MRI and compared between symptomatic and asymptomatic DLM groups. The relationships among each parameter, meniscal size, and patient age were evaluated. Symptomatic cases were divided into those with and without horizontal tears on MRI to compare the differences in meniscal morphology.

RESULTS

A total of 92 knees from 74 patients were included. Sixty-one knees required surgical intervention for symptomatic DLM, while 31 were asymptomatic and included the contralateral side of symptomatic knees. The symptomatic group exhibited larger morphological variations than the asymptomatic group. Moreover, the sagittal meniscal ratio reduced with age in the asymptomatic group (r = - 0.54, p = 0.002) but remained constant in the symptomatic group. The symptomatic cases with horizontal tears demonstrated larger meniscal dimensions and smaller posterior capsule distances than those without tears.

CONCLUSION

Symptomatic patients with DLM had larger knee morphological changes than asymptomatic ones. Age affected the meniscal occupancy in the sagittal plane only in asymptomatic patients.

LEVEL OF EVIDENCE

III.

Meniscal allograft transplantation in discoid meniscus patients achieves good clinical outcomes and superior chondroprotection compared to meniscectomy in the long term

PURPOSE

To compare the long-term clinical and radiological results of meniscal allograft transplantation (MAT) for discoid lateral meniscus (DLM) patients with MAT for non-discoid lateral meniscus patients and meniscectomy (ME) for DLM patients and, thus, to determine whether DLM patients are suitable candidates for MAT.

METHODS

Eight MAT cases in DLM patients were identified (discoid MAT group), six MAT cases in non-discoid lateral meniscus patients (non-discoid MAT group) and ten total meniscectomy cases in DLM patients (discoid ME group) were matched as controls. Subjective evaluations, postoperative radiography and magnetic resonance imaging (MRI) were conducted at 5 years and 10-14 years, respectively. Joint degeneration was evaluated by the Kellgren-Lawrance (KL) grade and joint space width (JSW). MRI with T2 mapping sequences was used to quantitatively evaluate degeneration of the joint cartilage and shrinkage of the allografts. Student's t test was used to compare quantitative variables and the Mann‒Whitney U test was used to compare categorical variables.

RESULTS

There was no difference in Lysholm, IKDC, Tegner or VAS scores amongst the discoid MAT, non-discoid MAT and discoid ME groups at the final follow-up. No revision surgery was performed in any MAT patient. The JSW narrowing in the discoid MAT group was better than that in the discoid ME group (0.8 ± 0.4 mm vs. 2.1 ± 1.3 mm, p = 0.012) and worse than that in the non-discoid MAT group (0.1 ± 0.1 mm, p = 0.003). The KL progression of the discoid MAT group was less than that of the discoid ME group (1.3 ± 0.7 vs. 2.3 ± 0.9, p = 0.034). The discoid ME group had worse cartilage lesion progression than the discoid MAT and non-discoid MAT groups. The allograft width of the DLM patients shrank more than that of the non-discoid patients at the meniscus midbody (3.6 ± 0.9 mm vs. 6.2 ± 1.9 mm, p = 0.015).

CONCLUSION

Compared to meniscectomy, MAT achieved similar long-term symptom relief and superior chondroprotection in discoid meniscus patients. Despite more graft shrinkage, the outcomes of MAT in discoid meniscus patients were comparable to those in non-discoid meniscus patients. Therefore, DLM patients may be suitable candidates for MAT procedures.

LEVEL OF EVIDENCE

Level III.

Discoid medial meniscus of both knees: A case report

BACKGROUND

Discoid meniscus is a congenital anomaly that typically affects the lateral meniscus. The appearance of the discoid medial meniscus in both knees is extremely rare, with an incidence of only 0.012%.

CASE SUMMARY

Our patient was a 30-year-old female. Under no obvious predisposing causes, she began to experience pain in both knees, which worsened while walking and squatting. The pain was aggravated after exercise, and joint flexion and extension activities were accompanied by knee snapping. Apley’s test was positive on physical examination, and there was a pressing pain in the medial articular space. Plain radiographs of both knees revealed no obvious abnormalities in the bilateral knee joint space. Partial meniscectomy as well as menisci reformation were performed on both knees under arthroscopy. Under the guidance of rehabilitation, the patient’s range of motion in both knees returned to normal without pain and knee snapping.

CONCLUSION

This study showed that the clinical manifestations of the discoid medial meniscus injury are identical to those of the conventional medial meniscus injury, and arthroscopic surgery is effective.