Differentiating normal hyaline cartilage from post-surgical repair tissue using fast gradient echo imaging in delayed gadolinium-enhanced MRI (dGEMRIC) at 3 Tesla

T2 assessment and clinical outcome following autologous matrix-assisted chondrocyte and osteochondral autograft transplantation

OBJECTIVE

Both, matrix-assisted chondrocyte transplantation (MACT) and osteochondral autograft transplantation (OCT), are applied for treatment of articular cartilage defects. While previous clinical studies have compared the respective outcome, there is no such information investigating the ultrastructural composition using T2 mapping comparing cartilage T2 values of the repair tissue (RT).

METHODS

Eighteen patients that underwent MACT or OCT for treatment of cartilage defects at the knee joint (nine MACT, nine OCT) were matched for gender (one female, eight male pairs), age (33.8), body mass index (BMI) (28.3), defect localization, and postoperative interval (41.6 months). T2 assessment was accomplished by T2 maps, while the clinical evaluation included the Lysholm and Cincinnati knee scores, a visual analogue scale (VAS) for pain, the Tegner activity scale, and the Short Form-36.

RESULTS

Global T2 values of healthy femoral cartilage (HC) were similar among groups, while T2 values of the RT following MACT (46.8ms, SD 8.6) were significantly lower when compared to RT T2 values after OCT (55.5ms, SD 6.7) (P=0.048). MACT values were also significantly lower in comparison to HC (52.5ms, SD 7.9) within MACT patients (P=0.046), while OCT values were significantly higher compared to HC (49.9ms, SD 5.1) within OCT patients (P=0.041). The clinical outcome following MACT was consistently superior to that after OCT while only the Lysholm score reached the level of significance (MACT 77.0, OCT 66.8; P=0.04).

CONCLUSION

These findings indicate that MACT and OCT result in a different ultrastructural outcome, which is only partially represented by the clinical picture.

Treatment of full-thickness chondral defects with hyalograft C in the knee: a prospective clinical case series with 2 to 7 years' follow-up

BACKGROUND

Tissue engineering has become available for cartilage repair in clinical practice.

HYPOTHESIS

The treatment of full-thickness chondral defects in the knee with a hyaluronan-based scaffold seeded with autologous chondrocytes provides stable improvement of clinical outcome up to 7 years.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fifty-three patients with deep osteochondral defects in the knee were treated with Hyalograft C. The mean age at implantation was 32 +/- 12 years, the mean defect size was 4.4 +/- 1.9 cm(2), and the mean body mass index was 24.5 +/- 3.8 kg/m(2). Implantations were performed with miniarthrotomy or arthroscopy. The primary indications for implantation with Hyalograft C included young patients with a stable joint, normal knee alignment, and isolated chondral defects with otherwise healthy adjacent cartilage. The secondary indications were patients who did not meet the primary indication criteria or were salvage procedures. Forty-two patients with primary indications and 11 patients with secondary indications were evaluated. Outcome was evaluated with the International Cartilage Repair Society and International Knee Documentation Committee scales, the Lysholm score, the modified Cincinnati score, and with Kaplan-Meier survival analysis. Statistical analysis consisted of bivariate correlation analysis and unpaired, 2-tailed t tests.

RESULTS

A highly significant increase (P <.001) in all knee scores was found in patients treated for the primary indications. Nine of 11 secondary indication cases underwent total knee arthroplasty due to persisting pain between 2 and 5 years after implantation. Graft failure occurred in 3 of 42 patients with primary indication between 6 months and 5 years after implantation. Kaplan-Meier survival demonstrated significantly different chances for survival between primary and secondary outcome and between simple, complex, and salvage cases, respectively (P <.001).

CONCLUSION

Hyalograft C autograft provides clinical improvement in healthy young patients with single cartilage defects. Less complicated surgery and lower morbidity are considered advantages of the technique. The results of treatment with Hyalograft C as a salvage procedure or in patients with osteoarthritis are poor.

The in vivo effects of unloading and compression on T1-Gd (dGEMRIC) relaxation times in healthy articular knee cartilage at 3.0 Tesla

PURPOSE

The purpose was to investigate the in vivo effects of unloading and compression on T1-Gd relaxation times in healthy articular knee cartilage.

MATERIALS AND METHODS

Ten volunteers were enrolled, and dGEMRIC images of their right knee joints were obtained using 3.0-T MR at three timepoints: directly following exercise ("baseline"), approximately 15 min after unloading ("unloading") and during application of a compressive force (50% of the body weight) generated by a loading device via a footplate ("compression").

RESULTS

Our analysis of variance of pooled data from all cartilage zones demonstrated a significant mean T1-Gd decrease of 56.6 ms between baseline and compression (p < 0.001), and a significant mean decrease of 42.1 ms between unloading and compression (p < 0.001). No significant difference was found between baseline and unloading. Higher mean T1-Gd values were observed in the cartilage contact zone (central femoral and tibial zones; 698.3 +/- 162.2 ms) than in the non-contact zone (anterior and posterior femoral and tibial zones, and dorsal femoral zone; 662.9 +/- 149.3 ms; p < 0.01).

CONCLUSION

T1-Gd times appear to be sensitive to mechanical cartilage stress, and thus, further studies are warranted that investigate the relationship between the biochemical load response and the biomechanical properties of articular cartilage.

Assessement of rheumatic diseases with computational radiology: current status and future potential

In recent years, several computational image analysis methods to assess disease progression in rheumatic diseases were presented. This review article explains the basics of these methods as well as their potential application in rheumatic disease monitoring, it covers radiography, sonography as well as magnetic resonance imaging in quantitative analysis frameworks.

Reproducibility of imaging human knee cartilage by delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) at 1.5 Tesla

OBJECTIVE

The purpose of this study was to investigate the day-to-day reproducibility of the delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) measurement at different knee joint surfaces in healthy subjects at 1.5 Tesla (T).

METHODS

The dGEMRIC experiment was repeated for 10 asymptomatic volunteers three times with an average interval of 5 days between scans. The measurement was performed from a single sagittal slice through the center of the lateral femoral condyle and from the center of the patella in the axial plane. Cartilage was manually segmented into superficial, deep and full-thickness regions of interests (ROIs) at different topographical locations of the femur, tibia and patella. The reproducibility was evaluated separately for each ROI as well as for the entire bulk cartilage in the slice of each joint surface.

RESULTS

The reproducibility at various ROIs expressed by root-mean-square average coefficient of variation (CV(RMS)) ranged between 4.7-12.9%. Thirty out of thirty-three ROIs showed a CV(RMS) less than 10%. Intraclass correlation coefficient (ICC) ranged between 0.45 and 0.98. The CV(RMS) and ICC for bulk dGEMRIC were 4.2% and 0.95 for femur, 5.5% and 0.87 for tibia, and 4.8% and 0.97 for patella.

CONCLUSIONS

The dGEMRIC technique showed good day-to-day reproducibility, on the average 8% for small deep or superficial segments, 7% for full-thickness ROIs and 5% for bulk ROIs covering all visible cartilage in a single joint surface. We conclude that dGEMRIC imaging at field strength 1.5 T can be used as a reliable instrument for the assessment of articular cartilage when staff has been carefully trained.