Relationship between meniscal integrity and risk factors for cartilage degeneration

Degradation of Proteoglycans and Collagen in Equine Meniscal Tissues

Investigate meniscal extracellular matrix degradation. Equine menisci (n = 34 from 17 horses) were studied. Site-matched sections were cut and scored from three regions (ROIs; n = 102) and stained for histology, proteoglycan (safranin O and fast green), aggrecan, and collagen cleavage (NITEGE, DIPEN, and C1,2C antibodies, respectively). Picrosirius red and second harmonic generation microscopy were performed to investigate collagen ultrastructure. A total of 42 ROIs met the inclusion criteria and were included in the final analysis. The median (range) ROI histological score was 3 (0-9), providing a large spectrum of pathology. The median (range) proteoglycan score was 1 (0-3), representing superficial and central meniscal loss. The median (range) of DIPEN, NITEGE, and C1,2C scores was 1 (0-3), revealing immunostaining of the femoral and tibial surfaces. The proteoglycan scores exhibited significant positive associations with both histologic evaluation (p = 0.03) and DIPEN scores (p = 0.02). Additionally, a robust positive association (p = 0.007) was observed between the two aggrecanolysis indicators, NITEGE and DIPEN scores. A negative association (p = 0.008) was identified between NITEGE and histological scores. The C1,2C scores were not associated with any other scores. Picrosirius red and second harmonic generation microscopy (SHGM) illustrated the loss of the collagen matrix and structure centrally. Proteoglycan and collagen degradation commonly occur superficially in menisci and less frequently centrally. The identification of central meniscal proteoglycan and collagen degradation provides novel insight into central meniscal degeneration. However, further research is needed to elucidate the etiology and sequence of degradative events.

No differences in knee joint loading between individuals who had a medial or lateral meniscectomy: An ancillary study

BACKGROUND

Arthroscopic partial meniscectomy is a frequently undertaken procedure for traumatic meniscal injuries. The location of knee joint degeneration and long-term prognosis differs between knees who have had a medial or lateral meniscectomy. However, there is no evidence comparing knee loading following a medial or lateral meniscectomy during sporting tasks. This study compared knee loading during walking and running between individuals who either had a medial or lateral meniscectomy.

METHODS

Knee kinematic and kinetic data were collected during walking and running in individuals three to twelve months post-surgery. Participants were grouped according to the location of surgery (medial, n = 12, and lateral, n = 16). An independent t-test compared knee biomechanics between the groups and Hedge's g effects sizes were also conducted.

RESULTS

External knee adduction and knee flexion moments were similar between groups for walking and running with negligible to small effect sizes (effect size, 0.08-0.30). Kinematic (effect size, 0.03-0.22) and spatiotemporal (effect size, 0.02-0.59) outcomes were also similar between the groups.

CONCLUSIONS

The lack of differences in surrogate knee loading variables between medial and lateral meniscectomy groups was unexpected. These findings suggest that combining groups in the short-term period following surgery is applicable. However, the data presented in this study cannot explain the differences in long-term prognosis between medial and lateral meniscectomies.

Histological Findings and T2 Relaxation Time in Canine Menisci of Elderly Dogs—An Ex Vivo Study in Stifle Joints

Osteoarthritis is a chronic disease that often affects the canine stifle joint. Due to their biomechanical function, the menisci in the canine stifle play an important role in osteoarthritis. They compensate for the incongruence in the joint and distribute and minimize compressive loads, protecting the hyaline articular cartilage from damage. Meniscal degeneration favors the development and progression of stifle joint osteoarthritis. Qualitative magnetic resonance imaging (MRI) is the current golden standard for detecting meniscal changes, but it has limitations in detecting early signs of meniscal degeneration. A quantitative MRI offers new options for detecting early structural changes. T2 mapping can especially visualize structural changes such as altered collagen structures and water content, as well as deviations in proteoglycan content. This study evaluated T2 mapping and performed a histological scoring of menisci in elderly dogs that had no or only low radiographic osteoarthritis grades. A total of 16 stifles from 8 older dogs of different sex and breed underwent ex vivo magnet resonance imaging, including a T2 mapping pulse sequence with multiple echoes. A histological analysis of corresponding menisci was performed using a modified scoring system. The mean T2 relaxation time was 18.2 ms and the mean histological score was 4.25. Descriptive statistics did not reveal a correlation between T2 relaxation time and histological score. Ex vivo T2 mapping of canine menisci did not demonstrate histological changes, suggesting that early meniscal degeneration can be present in the absence of radiological signs of osteoarthritis, including no significant changes in T2 relaxation time.

Quantitative Evaluation of Meniscal Healing Process of Degenerative Meniscus Lesions Treated with Hyaluronic Acid: A Clinical and MRI Study

Purpose: We aimed to evaluate clinical efficacy and healing effects of conservative management of degenerative meniscus lesions (DMLs) with a hyaluronic acid (HA) hydrogel. Methods: Patients were subjected to two HA injections two weeks apart. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Patient’s Global Assessment (PtGA) and Clinical Observer Global Assessment (CoGA) of the disease were assessed at baseline, 30, and 60 days after treatment. Short Form (36) Health Survey (SF-36) was assessed at baseline and 60 days after treatment. One year after treatment, patients were called to know whether any of them had undergone arthroscopic partial meniscectomy (APM). All patients underwent magnetic resonance imaging using a 1.5-T Magnetic Resonance Imaging (MRI) scanner (Siemens Aera), which included a T2 mapping pulse sequence with multiple echoes at baseline and 60 days after treatment. Results: 40 patients were enrolled. WOMAC score, physical function subscale, PtGA and CoGA, and SF-36 showed a statistically significant difference between baseline and follow-up. One year after treatment, only one patient had undergone APM. A decrease in the T2 measurement was detected in the posterior horn medial meniscus in 39% of cases in both the red and red–white zone, and in 60% of cases in the white zone; in the posterior horn lateral meniscus in 55% of cases in both the red and white zones, and in 65% of cases in the red–white zone. Only for the latter, there was a statistically significant difference between baseline and posttreatment T2 measurements. Conclusion: This study supports the use of HA in the conservative management of DML as it is clinically effective and enhances meniscus healing as demonstrated by T2 measurements. Moreover, it reduces the need for APM at 1-year follow-up.

[Meniscal lesion. A pre-osteoarthritic condition of the knee joint]

BACKGROUND

A close relationship between meniscal damage and articular cartilage exist. Likewise, (partial) meniscectomy may lead to the development of osteoarthritis (OA).

OBJECTIVES

With a special emphasis on therapeutic consequences for orthopaedic surgeons, the structural and functional relationship between meniscal tears/extrusion and cartilage loss, and/or the effect of meniscectomy or meniscal repair on the development of OA, are emphasized.

MATERIALS AND METHODS

A selective literature review with implementation of own research findings.

RESULTS

The close topographical and functional interplay between the menisci and the tibiofemoral cartilage is the basis for the clinically important relationship between meniscal damage and cartilage degeneration. In particular, due to its close connection to tibiofemoral OA, a degenerative meniscal lesion represents a pre-osteoarthritic condition. Meniscus extrusion is also often associated with tibiofemoral OA. Even large cartilage defects can cause meniscus lesions. Partial meniscectomy is strongly associated with the incidence and risk of progression of OA. Clinical results are particularly problematic after partial resection of the lateral meniscus. Although the use of arthroscopic partial resection for degenerative meniscal lesions has been controversially discussed, no long-term studies are available. A large number of studies emphasize the medium-term value of meniscus reconstruction compared to partial meniscus resection. Combined meniscus and cartilage damage are complex cases, and the value of a simultaneous therapy remains unclear.

CONCLUSIONS

Preserving the meniscus is the first step towards cartilage repair. Randomized and controlled studies will provide better information on the long-term outcomes of meniscal resection and repair with regard to OA development.

Meniscal body extrusion and cartilage coverage in middle-aged and elderly without radiographic knee osteoarthritis

OBJECTIVES

To determine meniscal extrusion and cartilage coverage on magnetic resonance (MR) images and factors associated with these parameters in knees of middle-aged and elderly persons free from radiographic tibiofemoral osteoarthritis (OA).

METHODS

Seven hundred eighteen persons, free of radiographic tibiofemoral OA, aged 50-90 years from Framingham, MA, USA, were included. We measured meniscal extrusion on 1.5 T MRI of both knees to evaluate both medial and lateral meniscal body extrusion and cartilage coverage. We also determined meniscal morphology and structural integrity. The multivariable association with age, body mass index (BMI), and ipsilateral meniscal damage was also evaluated.

RESULTS

The mean meniscal body extrusion medially was 2.7 mm and laterally 1.8 mm. The tibial cartilage coverage was about 30% of ipsilateral cartilage surface (both compartments). The presence of ipsilateral meniscal damage was associated with more extrusion in only the medial compartment, 1.0 mm in men and 0.6 mm in women, and less cartilage coverage proportion, -5.5% in men and -4.6% in women.

CONCLUSIONS

Mean medial meniscal body extrusion in middle-aged or older persons without radiographic tibiofemoral OA approximates the commonly used cutoff (3 mm) to denote pathological extrusion. Medial meniscal damage is a factor associated with medial meniscal body extrusion and less cartilage coverage.

KEY POINTS

• Medial meniscal extrusion in middle-aged/older persons without OA is around 3 mm. • Lateral meniscal extrusion in middle-aged/older persons without OA is around 2 mm. • Meniscal damage is associated with medial meniscal extrusion and less cartilage coverage.

T2 mapping of the meniscus is a biomarker for early osteoarthritis

Purpose

To evaluate in vivo T₂ mapping as quantitative, imaging-based biomarker for meniscal degeneration in humans, by studying the correlation between T₂ relaxation time and degree of histological degeneration as reference standard.

Methods

In this prospective validation study, 13 menisci from seven patients with radiographic knee osteoarthritis (median age 67 years, three males) were included. Menisci were obtained during total knee replacement surgery. All patients underwent pre-operative magnetic resonance imaging using a 3-T MR scanner which included a T₂ mapping pulse sequence with multiple echoes. Histological analysis of the collected menisci was performed using the Pauli score, involving surface integrity, cellularity, matrix organization, and staining intensity. Mean T₂ relaxation times were calculated in meniscal regions of interest corresponding with the areas scored histologically, using a multi-slice multi-echo postprocessing algorithm. Correlation between T₂ mapping and histology was assessed using a generalized least squares model fit by maximum likelihood.

Results

The mean T₂ relaxation time was 22.4 ± 2.7 ms (range 18.5–27). The median histological score was 10, IQR 7–11 (range 4–13). A strong correlation between T₂ relaxation time and histological score was found (r_s = 0.84, CI 95% 0.64–0.93).

Conclusion

In vivo T₂ mapping of the human meniscus correlates strongly with histological degeneration, suggesting that T₂ mapping enables the detection and quantification of early compositional changes of the meniscus in knee OA.

Key Points

• Prospective histology-based study showed that in vivo T₂mapping of the human meniscus correlates strongly with histological degeneration.

• Meniscal T₂mapping allows detection and quantifying of compositional changes, without need for contrast or special MRI hardware.

• Meniscal T₂mapping provides a biomarker for early OA, potentially allowing early treatment strategies and prevention of OA progression.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06091-1) contains supplementary material, which is available to authorized users.

Equine meniscal degeneration is associated with medial femorotibial osteoarthritis

BACKGROUND

There is limited information available concerning normal equine meniscal morphology, its degeneration and role in osteoarthritis (OA).

OBJECTIVES

To characterise normal equine meniscal morphology and lesions and to explore the relationship between equine meniscal degeneration and femorotibial OA.

STUDY DESIGN

Ex vivo cadaveric study.

METHODS

Menisci were harvested from 7 normal joints (n = 14 menisci) and 15 joints with OA (n = 30 menisci). A macroscopic femorotibial OA score (cartilage degeneration and osteophytosis) was employed to measure disease severity in each compartment. The femoral and tibial meniscal surfaces were scored for macroscopic fibrillation and tears (1-4). Histological sections (regions: cranial and caudal horn; body) were also scored for microscopic fibrillation and tears (0-3) and inner border degeneration (0-3).

RESULTS

Partial meniscal tears were present on both femoral and tibial surfaces in all 3 regions and most frequently identified on the femoral surface of the cranial horn of the medial meniscus and body of the lateral meniscus. There was a significantly positive correlation between the global medial meniscal macroscopic scores and osteophyte (r = 0.7, P = 0.002) or cartilage degeneration (r = 0.5, P = 0.03) scores within the medial femorotibial joint. The global medial meniscal macroscopic score was greater (P = 0.004) in the advanced OA joints compared with control joints.

MAIN LIMITATIONS

The menisci were principally from abattoir specimens without a known clinical history because of the challenge in obtaining a large number of specimens with a clinical diagnosis of femorotibial OA.

CONCLUSIONS

This study is the first to describe normal equine meniscal morphology and lesions. Meniscal lesions were identified in all segments and on both articular surfaces. Meniscal degeneration significantly correlated with OA severity in the equine medial femorotibial joint. The relationship between OA and meniscal pathology remains to be elucidated.