Should the meniscal height be considered for preoperative sizing in meniscal transplantation?

Could a three-dimensional contralateral meniscus segmentation for allograft or scaffold sizing be possible? A prospective study

PURPOSE

Meniscal allografts and biodegradable meniscal implants are attractive surgical options for painful subtotal or total meniscectomies. In order to get the best results, these should be as similar as possible to the original meniscus in terms of shape, structure, and volume. Three-dimensional meniscus sizing could be an approach to improve the accuracy of meniscus matching. Therefore, the aims of this study were to perform a comparative morphological and volumetric analysis of the healthy meniscus based on manual tri-planar segmentation and to demonstrate that the menisci from the contralateral knee could be used as a reference in the sizing of a meniscal graft or a scaffold.

METHODS

Three-dimensional meniscal models were created based on 120 MRIs in 60 healthy subjects (bilateral knees). The differences between the pairs of menisci concerning the widths, thicknesses, lateromedial distances, anteroposterior distances, angles of coverage, and meniscal volumes were evaluated. T-Student tests were used to compare the quantitative numerical variables of the different groups. Pearson's linear regression was used to determine if correlations existed between demographic variables (age, gender, height, weight) and anatomical parameters. Statistical significance was set at p < 0.05.

RESULTS

Comparing the 120 pairs of menisci of each subject, there was no statistically significant difference for all parameters studied for both the medial and lateral meniscus. When the measurements were stratified by gender, statistically significant differences were observed for all parameters except meniscal coverage angles. We observed that anteroposterior and lateromedial distances were positively correlated with height and body mass index both at the level of the medial meniscus (r = 0.68; r = 0.66; r = 0.65; and r = 0.63) and lateral (r = 0.68; r = 0.69; r = 0.61; and r = 0.60).

CONCLUSION

Our study demonstrated that the intra-individual 3D shapes of the left and right menisci are very similar. Therefore, the contralateral side could be used as a template for the 3D sizing of meniscal allografts or meniscal implants.

Meniscus Size Differs Between Patient and Donor Populations for Meniscus Allograft Transplantation

Purpose

To determine the extent of variability in meniscus size and anthropometric data between donors (supply) and patients (demand), to evaluate potential factors that may contribute to size discrepancies, and to determine whether the discrepancies lead to longer patient wait times.

Methods

Lateral and medial meniscal measurements, anthropometric data, and time to match a donor graft were extracted from a tissue supplier database. The frequency and distribution of meniscus size were analyzed. Body mass index (BMI), relative meniscus area, body mass to meniscus area index, and height to meniscus area index were compared between patient and donor pools via χ² tests and independent samples t-test. The effect of size on time to match was analyzed using analysis of variance and post-hoc Tukey test.

Results

The lateral meniscus patient population showed a greater frequency of larger size requirements compared to the donor population (P < .001) and the medial meniscus patient population showed a higher frequency of smaller meniscus size requirements (P < .001). The medial meniscus analysis showed significantly smaller meniscus areas (P < .001) in the patient population contributing to the observed trend of an increased body mass to meniscus area index and height to meniscus area index. The time to match a donor meniscus was affected by the patient meniscus size.

Conclusions

This analysis demonstrates variations in frequency of meniscus sizes between donor and patient populations. This variation is attributed to differences in anthropometric data between patient and donor populations. This work identifies a mismatch between demand and supply for certain patient sizes contributing to longer times to match.

Clinical Relevance

This work associated donor and patient mismatches with longer wait times. This can be useful for patient counseling as well as provide a framework to determine whether there are solutions within the current meniscus donor pool that can be used to meet this clinical need.

Variations of cross-sectional meniscal morphology between similar-sized menisci: implications on donor selection for meniscal allograft transplantation

PURPOSE

This study aimed to investigate the morphological variations in the cross-sectional anatomy of the meniscus between similar-sized matched menisci.

MATERIALS AND METHODS

Knee MRI of 329 patients with intact menisci were retrospectively reviewed, and the meniscal length (ML), meniscal width (MW), and cross-sectional dimensions (meniscal height and width) of the anterior, posterior horns, and the corpus were measured. Patients with similar-sized menisci who had less than 1 mm difference in ML and MW were matched. 330 male-to-male medial menisci (MM), 623 male-to-male lateral menisci (LM), 82 female-to-female MM, 233 female-to-female LM, 176 cross-gender MM, and 265 cross-gender LM unique combination of ideally matched pairs (total: 1709) were generated. The disparity in the cross-sectional dimensions, absolute difference, and the paired percent differences was statistically analyzed.

RESULTS

The ML and MW in all groups were statistically similar, with a predefined absolute difference of 1 mm both for ML and MW (paired percent difference < 5%). The cross-sectional segmental meniscal dimensions were similar within all groups, but the paired percent differences showed high variations between a mean of 12.1-21.5% and up to 150.9%. The paired percent difference of MM in each segmental dimension was similar among different gender combinations. However, segmental paired percent differences of LM showed statistical differences in anterior horn width (AHW) (p: 0.001) and posterior horn width (PHW) (p: 0.001). In subgroup comparisons, the paired percent difference of AHW was higher in the female-to-female group compared to cross-gender (p: 0.023) and male-to-male groups (p: 0.001). The paired percent difference of PHW was smaller in the male-to-male group compared to female-to-female and cross-gender groups (p: 0.001 for both).

CONCLUSIONS

Segmental cross-sectional anatomy showed wide variations despite strict matching in ML and MW. These variations were present in all gender combinations. The meniscal 3D shape is unique, but acceptable limits of similarity need further research.

LEVEL OF EVIDENCE

Retrospective study, Level III.

Avaliação das propriedades histológicas de enxertos meniscais humanos armazenados em banco de tecido

Objectives  The present paper aims to evaluate and compare the histological features of fresh and frozen menisci stored in a tissue bank for 1 month and for 5 years.

Methods  The meniscal grafts were subjected to a histological study. A total of 10 menisci were evaluated; 2 were frozen for 5 years, 4 were frozen for 1 month, and 4 were fresh, recently harvested specimens. Histological properties were evaluated in sections stained with hematoxylin and eosin and Masson trichrome methods.

Results  The menisci frozen for 1 month showed partially preserved collagen fiber structure and no significant hydropic tissue degeneration. The menisci frozen for 5 years presented an evident dissociation of collagen fibers and multiple foci of hydropic degeneration.

Discussion  Degeneration was much more significant in menisci stored for 5 years, indicating that a long freezing period results in substantial progression of tissue deterioration. This may suggest that the 5-year period, considered the maximum time for graft storage before transplant, is too long.

Conclusion  Grafts stored for 1 month showed a slight degenerative change in collagen fibers, whereas menisci frozen for 5 years presented significant tissue degeneration.

Morphological Analysis of Normal Meniscus on Magnetic Resonance Imaging (MRI)-Based Three-Dimensional Reconstruction Models in Healthy Chinese Adults

Background

The purpose of this cross-sectional observational study was to determine the morphological meniscus characteristics in a normal Chinese population and assess possible relationships between demographic data and meniscal morphological parameters.

Material/Methods

We examined 116 menisci (58 lateral and 58 medial) from 29 healthy Chinese volunteers (10 men, 19 women, mean age 26 years [range, 20–33 years]) with MRI and three-dimensional reconstruction using Mimics software. The width, thickness, anteroposterior distance (APD), lateral-medial distance (LMD), and covering angle (CA) were measured on reconstructed models. Univariate analysis was used to evaluate the differences of morphological parameters between the medial and lateral menisci, between sides, and between males and females. Pearson correlation analysis was used to evaluate the correlation between meniscal morphological parameters and body height, weight, and body mass index (BMI).

Results

Univariate analysis demonstrated that the width, thickness, APD, LMD, and CA were significantly different between lateral and medial menisci. The LMD and APD of menisci in men were significantly larger than in women. There was no significant difference in meniscal thickness and CA between males and females. The lateral meniscus dimensions were slightly larger in the right knee. According to Pearson correlation analysis, the APDs of both lateral and medial menisci were strongly correlated with height and weight (lateral: r=0.596, r=0.500; medial: r=0.684, r=0.680).

Conclusions

The morphologies of medial and lateral menisci were different and were not significantly correlation with each other. The meniscal width and diameter were correlated with demographic data, but the thickness and CA did not significantly differ by sex, height, or BMI.

Meniscal Injury Does Not Significantly Affect the Dimensions of the Intact Meniscus in the Opposite Compartment of the Knee

Background:

Meniscal allograft transplant requires precise matching of the size of the allograft with the dimensions of the recipient knee. Estimation of contralateral meniscal size on magnetic resonance imaging (MRI) has been considered the ideal method to measure menisci before transplant. We questioned whether a contralateral intact meniscus with meniscal injury in the opposite compartment could be used as a reference to determine allograft size. Our question was derived from knowledge of meniscal injury influencing structures of the opposite compartment of the knee, including the meniscus.

Purpose:

To compare meniscal dimensions between intact meniscus with meniscal injury in the opposite compartment and normal meniscus with a normal opposite compartment.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

This observational, cross-sectional study was performed between 2016 and 2017. The control group consisted of 200 knees with normal medial and lateral menisci. The medial intact group consisted of 150 cases of medial intact meniscus with injured lateral meniscus, and the lateral intact group consisted of 150 cases of lateral intact meniscus with injured medial meniscus. All patients were male. Mean age, height, and weight did not differ among groups. We investigated meniscal dimensions on MRI, including anteroposterior and mediolateral lengths, distance between the anterior and posterior horns (AHPH distance), and widths and heights of the anterior and posterior horns and midbody.

Results:

Most medial meniscal dimensions were similar between the control and medial intact groups, but the AHPH distance was smaller in the medial intact group (P < .001). Likewise, most lateral meniscal dimensions were similar between the control and lateral intact groups, but the AHPH distance was smaller in the lateral intact group (P < .001).

Conclusion:

Most dimensions of the intact meniscus with meniscal injury in the opposite compartment were similar to those of the normal meniscus with normal opposite compartment. Measuring the dimensions of the contralateral intact meniscus with meniscal injury in the opposite compartment on MRI can be an appropriate method to determine meniscal allograft size.

Use of magnetic resonance imaging to determine laterality of meniscal size in healthy volunteers

Introduction

The menisci are responsible for several functions. They are shock absorbers during dynamic loading on the knee and provide a broader surface area on which to distribute stress evenly to the tibia and femur. These functions allow for smoother movement and greater stability of the knee joint. Meniscal injury can be a great impediment to the function of the knee. Therefore, in the case of meniscal injury, our main concern is the relief of patient symptoms, followed by consequent restoration of meniscal function to the greatest of our ability.

To prevent the long terms effects of a meniscectomy, meniscal allograft transplantation (MAT) was developed. The potential of using the size of the contralateral healthy menisci, to determine the size of the menisci to be replaced, will be discussed.

Methods

Knee MRIs done on healthy patients in the past 5 years were reviewed. Magnetic Resonance Imaging was performed using a 3-T scanner. Each individual was examined with knee joints in full extension. Measurements were performed two separate times, two weeks apart. A mean of three measurements was made during each session to reduce error.

Thirty-eight normal bilateral knee joints MRIs remained (16 males, 22 females). Participants were sampled from the institutional Picture Archiving and Communication System (PACS). Age, gender, and the medial meniscal and lateral meniscal size of both knees were recorded. The laterality of the menisci was compared between both knees in each patient.

Results

A total of 38 patients were included in this study, with a mean age of 37.39 (±9.50) years. They were 16 (42.1%) men and 22 (57.9%) women. We didn’t find any significant difference in the mid-coronal section between left and right knees meniscal measurements. None of the measurements were significantly different between men and women. There was no significant difference in the medial mid-sagittal section or lateral mid-sagittal section between left and right knee meniscal measurements.

Conclusion

The results obtained in this study may support the use of MRI of the bilateral knee to obtain an appropriately sized allograft.

Discoid meniscus in children and adolescents: Correlation between morphology and meniscal tears

BACKGROUND

Some authors have suggested that the diminished vascular blood supply, peripheral stability and thickness of the discoid meniscus (DM) would make it more prone to tears. The aims of this study are two-fold: 1) To analyse morphological characteristics by magnetic resonance (MRI), and 2) To correlate the size of the meniscus with the presence of meniscal tears.

METHODS

The MRI of patients ≤18 years-old over a period of 5 years were reviewed, and patients with DM were identified. We analysed demographic data, location (medial or lateral), morphology (Watanabe), meniscal tears (Crues classification), pattern, displacement, and other associated findings. Meniscal height and thickness per width (TxW) were also calculated. The correlation between variables: morphology, height and TxW with the presence of meniscal tears were statistically analysed.

RESULTS

Six hundred and eighty-five MRI (675 patients) were analysed. Forty-three knees (38 patients, 20 males) were found to have a DM (6.3%). The average age was 12.2±3.8 years (range: 4-18 years). Sixty-three percent had some type of meniscal injury. Patients with complete MD had a higher incidence of injuries (77.3 vs. 47.6%; P=.001). Longitudinal (bucket handle) and complex tears (n ??=11) only occurred in patients with complete DM. DM with tears presented a nonsignificant tendency to have higher meniscal height and higher TxW (6.29±1.26 vs 5.75±.66mm; P=.20 and 107.5±36.02 vs. 91.54±16.5mm²; P=.162).

CONCLUSION

The results of this series support the theory that a larger meniscal size would be one of the main predisposing factors for the DM to be injured.

STUDY DESIGN

Cross-sectional study (Level of evidence: III).