Do cartilage repair procedures prevent degenerative meniscus changes?: longitudinal t1ρ and morphological evaluation with 3.0-T MRI

Knorpelersatzverfahren und Regeneration am Knie- und Hüftgelenk

Die operative Therapie von Knorpelschäden am Kniegelenk hat sich in den letzten Jahren von vorsichtigen Anfängen mit innovativen Therapieansätzen zu einem festen und etablierten Baustein der gelenkerhaltenden Therapie entwickelt. Hingegen hat sich am Hüftgelenk erst in den letzten 10 Jahren, basierend auf einem erweiterten Verständnis grundlegender mechanischer Pathomechanismen, die gelenkerhaltende Hüftchirurgie und insbesondere die Knorpeltherapie etabliert. Der Beitrag stellt die zur Verfügung stehenden Techniken vor.

Synovial mesenchymal stem cells promote the meniscus repair in a novel pig meniscus injury model

Stem cell therapy has potential for the treatment of degenerative meniscus injuries; however, an optimal animal model has not been established. Basic and clinical research show that synovial mesenchymal stem cells (MSCs) promote meniscus repair. The purposes of this study were to create a novel meniscus injury model in microminipigs and to investigate the effectiveness of synovial MSCs on meniscus healing in this model. The posterior portion of the medial meniscus in microminipigs was punctuated 200 times with a 23G needle. Allogenic synovial MSC suspension was placed on the injury site for 10 min for transplantation. The meniscus was evaluated histologically and via sagittal magnetic resonance imaging (MRI), radial MRI reconstructed in three dimensional, and T2 mapping at 1 and 8 weeks. Proteoglycan content stained with safranin-o disappeared 1 week after treatment in both the MSC and control groups but increased at 8 weeks only in the MSC group. Histological scores at 8 weeks were significantly higher in the MSC group than in the control group (n = 6). At 8 weeks, the T2 values of the MSC group were significantly closer to those of a normal meniscus than were those of the control group. High signal intensity areas of the MRIs and positive areas stained with picrosirius red coincided with meniscal lesions. In conclusion, we created a novel meniscus injury model in microminipigs. Evaluation via histology, MRIs, and polarized microscopy showed that transplantation of synovial MSCs improved meniscus healing.

Degeneration in ACL Injured Knees with and without Reconstruction in Relation to Muscle Size and Fat Content-Data from the Osteoarthritis Initiative

Background

Anterior cruciate ligaments (ACL) injuries represent a major risk factor for early osteoarthritis (OA).

Purpose

To evaluate the prevalence and 4-year progression of knee OA measured with 3T MR-imaging in individuals with ruptured, reconstructed or normal ACL and to assess the impact of thigh muscle characteristics.

Methods

A total of 54 knees (23/54 male, 31/54 female) were recruited from the Osteoarthritis Initiative (OAI). At baseline, 15/54 subjects had prevalent ACL ruptures and 15/54 subjects had prevalent ACL reconstruction (24/54 normal ACL). Western Ontario and McMasters Universities Arthritis Index (WOMAC) scores, Physical Activity Scores of the Elderly (PASE) and thigh muscle characteristics including strength, fat infiltration (Goutallier score) and thigh muscle cross-sectional area (CSA) MR measurements were obtained at baseline. Whole-organ MR-imaging Scores (WORMS) were obtained at baseline and at a 4-year follow-up time-point. Multivariate regression models, adjusting for covariates (age, gender, body mass index), were used for statistical analysis.

Results

At baseline, subjects with prevalent ACL ruptures had worse WORMS total scores (mean±SEM, 44.1±3.5) than subjects with ACL reconstruction (30.8±4.0; P = 0.015) and worse than subjects with normal ACL (21.3±3.0; P<0.001). Cartilage scores were worse in both femorotibial compartments in ACL injured knees than in knees with normal ACL (P<0.05). Knees with ACL reconstruction showed an increased degeneration of the medial meniscus (P = 0.036), cartilage degeneration at the medial femoral condyle (P = 0.011). In a multivariate regression model, including both ACL groups and total muscle characteristics as influence parameters, high thigh muscle CSA, high muscle/ fat ratio and low Goutallier scores were associated with less degenerative changes at the knee, independent of ACL status. Knees with ACL reconstruction showed an increased progression of cartilage degeneration at the medial tibia compared to the normal ACL group (P = 0.027).

Conclusions

High thigh muscle CSA is associated with less degenerative changes at the knee, independent of the ACL status and may potentially be advantageous in the prevention of early OA.

Role of magnetic resonance imaging in the diagnosis of the painful unicompartmental knee arthroplasty

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is a well established method for the treatment of single compartment arthritis; however, a subset of patients still present with continued pain after their procedure in the setting of a normal radiographic examination. This study investigates the effectiveness of magnetic resonance imaging (MRI) in guiding the diagnosis of the painful unicompartmental knee arthroplasty.

METHODS

An IRB-approved retrospective review identified 300 consecutive UKAs performed over a three years period with 28 cases of symptomatic UKA (nine percent) with normal radiographic images.

RESULTS

MRI examination was instrumental in finding a diagnosis that went undetected on radiographs. Based on MRI findings, 10 (36%) patients underwent surgery whilst 18 (64%) were treated conservatively.

CONCLUSION

This study supports the use of MRI as a valuable imaging modality for managing symptomatic unicompartmental knee arthroplasty.

LEVEL OF EVIDENCE

Case series.

T1rho Magnetic Resonance Imaging at 3T Detects Knee Cartilage Changes After Viscosupplementation

Viscosupplementation may affect cartilage. Changes in T1rho magnetic resonance imaging (MRI) relaxation times correlate with proteoglycan changes in cartilage. The authors hypothesized that T1rho MRI will show an improvement in proteoglycan content at 6 weeks and 3 months after viscosupplementation and that this improvement will correlate with functional outcome scores. Ten patients (mean age, 56 years; Kellgren-Lawrence grade 1 or 2) underwent T1rho MRI at baseline, 6 weeks, and 3 months after viscosupplementation. Volumetric T1rho means were calculated by depth and region. Visual analog scale (VAS), International Knee Documentation Committee (IKDC), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were obtained. Mean T1rho values decreased in the superficial patella at 6 weeks (10.3%, P=.002) and 3 months (7.9%, P=.018) and in the middle patella at 6 weeks (7.0%, P=.014) compared with baseline values. Deep patella T1rho values increased at 3 months compared with 6 weeks (9.9%, P=.033), returning to values similar to baseline. Mean T1rho values increased in the deep tibia at 6 weeks (4.7%, P=.048) and in the middle tibia (5.2%, P=.004) and deep tibia (11.2%, P=.002) at 3 months compared with baseline. At 6 weeks, improvement was seen in VAS (5.9 to 3.9, P<.01), IKDC-9 (55.3 to 63.7, P=.03), and WOMAC (43.9 to 32.8, P=.03) scores. Functional VAS (4.0, P=.02), IKDC-9 (67.8, P=.04), and WOMAC (30.0, P=.04) scores remained better at 3 months. T1rho MRI is a feasible noninvasive method of studying molecular changes in cartilage. Some segments improved after viscosupplementation, and others worsened, possibly reflecting natural history or symptom relief and subsequent increase in activity-related wear.

Association of cartilage degeneration with four year weight gain--3T MRI data from the Osteoarthritis Initiative

OBJECTIVE

To determine the effect of weight gain on progression of early knee morphologic abnormalities using magnetic resonance imaging (MRI) in a longitudinal study over 48 months.

DESIGN

We studied the right knee of 100 subjects from the Osteoarthritis Initiative (OAI), selecting subjects aged ≥ 45 with osteoarthritis (OA) risk factors who demonstrated weight gain (minimum 5% increase in body mass index, BMI, n = 50) or no change in weight (BMI change < 2%, n = 50), frequency matched for age, gender, and baseline BMI. Baseline and 48 month knee MRI studies were scored for lesions using a modified whole organ MRI score (WORMS). Logistic regression models were used to compare the differences between the two groups.

RESULTS

The odds of worsening maximum cartilage (11.3, 95%, CI 3.5-51.4) and meniscal WORMS (4.5, 95% CI 1.4-17.3) were significantly greater in the weight gain group compared to the no change group, in addition to the odds of worsening cartilage defects at the patella and average meniscal WORMS (P < 0.05). Odds of worsening average bone marrow edema pattern (BMEP) were significantly greater for the weight gain group compared to the no change cohort (P < 0.05).

CONCLUSION

Our study demonstrated that weight gain is strongly associated with increased progression of cartilage degeneration in middle-aged individuals with risk factors for OA.

Clinical outcome of revision meniscal allograft transplantation: minimum 2-year follow-up

PURPOSE

The purpose of this study was to assess the clinical and radiographic outcomes after revision meniscal allograft transplantation (RMAT).

METHODS

Eleven patients underwent RMAT performed by the senior author (B.J.C.). These patients were studied prospectively and completed standardized outcome surveys (including International Knee Documentation Committee [IKDC], Cincinnati Knee-Rating System, Tegner score, Lysholm score, Short Form-12, Knee Injury and Osteoarthritis Outcome Score [KOOS], and overall satisfaction) preoperatively and annually thereafter for a minimum of 2 years. Radiographic analysis before surgery and at the most recent follow-up included anteroposterior, Rosenberg, lateral, and sunrise views graded by the Kellgren and Lawrence (K & L) scale. The status of the articular cartilage was graded intraoperatively using the Outerbridge classification. Two patients were lost to follow-up and one declined further participation.

RESULTS

The average time to RMAT from the index procedure was 3.45 ± 2.52 years, with a mean follow-up after RMAT of 3.83 ± 1.3 years. One patient progressed to arthroplasty during follow-up and was not included in subjective outcome score follow-up. Clinical outcome scores that demonstrated significant improvements included IKDC (43 ± 12 to 61 ± 16; P = .03) and KOOS pain score (66 ± 12 to 79 ± 11; P = .047). Along with this, the subjective symptom rate significantly improved from 5.0 ± 0.9 preoperatively to 6.7 ± 1.8 postoperatively (P = .011). Radiographic (P = .7) and Outerbridge (P = .809) grading did not show progression. Seven of 8 patients would have surgery again, and satisfaction at final follow-up was 7.6 ± 2.6.

CONCLUSIONS

In this small series with short-term follow-up, RMAT resulted in high patient satisfaction and significant symptom reduction on validated outcome scores (IKDC and KOOS pain score), proving the original hypothesis that outcomes after RMAT would be improved compared with preoperative conditions. Identifiable causes of MAT failure may help predict response to RMAT. Because arthroplasty is still not favored in young active patients, a thorough discussion with the patient is necessary to best align their goals with those of the surgery when considering revision meniscus transplantation.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

T₁ρ MRI of human musculoskeletal system

Magnetic resonance imaging (MRI) offers the direct visualization of the human musculoskeletal (MSK) system, especially all diarthrodial tissues including cartilage, bone, menisci, ligaments, tendon, hip, synovium, etc. Conventional MRI techniques based on T1 - and T2 -weighted, proton density (PD) contrast are inconclusive in quantifying early biochemically degenerative changes in MSK system in general and articular cartilage in particular. In recent years, quantitative MR parameter mapping techniques have been used to quantify the biochemical changes in articular cartilage, with a special emphasis on evaluating joint injury, cartilage degeneration, and soft tissue repair. In this article we focus on cartilage biochemical composition, basic principles of T1ρ MRI, implementation of T1ρ pulse sequences, biochemical validation, and summarize the potential applications of the T1ρ MRI technique in MSK diseases including osteoarthritis (OA), anterior cruciate ligament (ACL) injury, and knee joint repair. Finally, we also review the potential advantages, challenges, and future prospects of T1ρ MRI for widespread clinical translation.

Cartilage repair surgery: outcome evaluation by using noninvasive cartilage biomarkers based on quantitative MRI techniques?

BACKGROUND

New quantitative magnetic resonance imaging (MRI) techniques are increasingly applied as outcome measures after cartilage repair.

OBJECTIVE

To review the current literature on the use of quantitative MRI biomarkers for evaluation of cartilage repair at the knee and ankle.

METHODS

Using PubMed literature research, studies on biochemical, quantitative MR imaging of cartilage repair were identified and reviewed.

RESULTS

Quantitative MR biomarkers detect early degeneration of articular cartilage, mainly represented by an increasing water content, collagen disruption, and proteoglycan loss. Recently, feasibility of biochemical MR imaging of cartilage repair tissue and surrounding cartilage was demonstrated. Ultrastructural properties of the tissue after different repair procedures resulted in differences in imaging characteristics. T2 mapping, T1rho mapping, delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), and diffusion weighted imaging (DWI) are applicable on most clinical 1.5 T and 3 T MR scanners. Currently, a standard of reference is difficult to define and knowledge is limited concerning correlation of clinical and MR findings. The lack of histological correlations complicates the identification of the exact tissue composition.

CONCLUSIONS

A multimodal approach combining several quantitative MRI techniques in addition to morphological and clinical evaluation might be promising. Further investigations are required to demonstrate the potential for outcome evaluation after cartilage repair.

Changes in MR relaxation times of the meniscus with acute loading: an in vivo pilot study in knee osteoarthritis

PURPOSE

To prospectively evaluate changes in T1ρ and T2 relaxation times in the meniscal body with acute loading using MRI in osteoarthritic knees and to compare these findings with those of age-matched healthy controls.

MATERIALS AND METHODS

Female subjects above 40 years of age with (N1  = 20) and without osteoarthritis (OA) (N2  = 10) were imaged on a 3 Tesla MR scanner using a custom made loading device. MR images were acquired, with the knee flexed at 20°, with and without a compressive load of 50% of the subject's bodyweight. The subjects were categorized based on the radiographic evidence of OA. Three different zones (outer, middle, and inner) of meniscus body were defined (each occupying 1/3rd the width). After adjusting for age and body mass index in the general linear regression model, repeated measures analysis of variance was used to detect significant differences in T1ρ and T2 with and without loading.

RESULTS

In the unloaded condition, the average T1ρ and T2 times were elevated in the outer and middle zones of the medial meniscus in OA subjects compared with the controls. In the loaded condition, T1ρ and T2 times of the outer zone of the medial meniscus was significantly elevated in OA subjects compared with controls. Finally the change (from unloaded to loaded) was significantly higher in controls than OA subjects (15.1% versus 8.3%; P = 0.039 for ΔT1ρ , and 11.5% versus 6.9%, P = 0.049 for ΔT2 ).

CONCLUSION

These findings suggest that while the OA process appears to affect the relaxation times of all regions within the meniscus, it may affect some regions sooner or to a greater degree. Furthermore, the differences in the change in relaxation times between unloaded and loaded conditions may reveal evidence about load transmission failure of the outer zone of the medial meniscus in subjects with knee OA. It is possible that these metrics (ΔT1ρ and ΔT2 ) may be valuable as an early biomechanical biomarker, which could be used to predict load transmission to the underlying articular cartilage.

Osteoarthritis year 2013 in review: imaging

PURPOSE

To review recent original research publications related to imaging of osteoarthritis (OA) and identify emerging trends and significant advances.

METHODS

Relevant articles were identified through a search of the PubMed database using the query terms "OA" in combination with "imaging", "radiography", "MRI", "ultrasound", "computed tomography", and "nuclear medicine"; either published or in press between March 2012 and March 2013. Abstracts were reviewed to exclude review articles, case reports, and studies not focused on imaging using routine clinical imaging measures.

RESULTS

Initial query yielded 932 references, which were reduced to 328 citations following the initial review. MRI (118 references) and radiography (129 refs) remain the primary imaging modalities in OA studies, with fewer reports using computed tomography (CT) (35 refs) and ultrasound (23 refs). MRI parametric mapping techniques remain an active research area (33 refs) with growth in T2*- and T1-rho mapping publications compared to prior years. Although the knee is the major joint studied (210 refs) there is interest in the hip (106 refs) and hand (29 refs). Imaging continues to focus on evaluation of cartilage (173 refs) and bone (119 refs).

CONCLUSION

Imaging plays a major role in OA research with publications continuing along traditional lines of investigation. Translational and clinical research application of compositional MRI techniques is becoming more common driven in part by the availability of T2 mapping data from the Osteoarthritis Initiative (OAI). New imaging techniques continue to be developed with a goal of identifying methods with greater specificity and responsiveness to changes in the joint, and novel functional neuroimaging techniques to study central pain. Publications related to imaging of OA continue to be heavily focused on quantitative and semiquantitative MRI evaluation of the knee with increasing application of compositional MRI techniques in the hip.