Associations of three-dimensional T1 rho MR mapping and three-dimensional T2 mapping with macroscopic and histologic grading as a biomarker for early articular degeneration of knee cartilage.

T1 rho and T2 mapping are magnetic resonance imaging (MRI) techniques to detect early degenerative changes in cartilage. Recent advancements have enabled 3D acquisition for both techniques. The objective of the present study was to examine the correlation of 3D T1 rho and 3D T2 mapping with macroscopic and histological characteristics of knee cartilage. Twenty-one patients who underwent total knee arthroplasty due to osteoarthritis with involvement of the medial compartment but with minimum involvement of the lateral compartment were enrolled. Prior to surgery, five series of MRI were acquired with a 3-T scanner. 3D T1 rho/T2 analyses were performed following determination of regions to be assessed using in-house software that incorporated three series of MRI acquisitions data (3D-MERGE, 3D-SPGR, and 3D-CUBE). During surgery, the cartilage of the lateral compartment was macroscopically assessed with the International Cartilage Research Society (ICRS) articular classification system. The extracted specimens were histologically assessed using the OARSI histology score. Three regions of interest (ROI) were assessed for each slice (two slices per knee): the central lateral femoral condyle (cLFC), the posterior portion of the lateral femoral condyle (pLFC), and the lateral tibia plateau (LTP). For each ROI, the mean T1 rho and T2 relaxation time, the ICRS grade, and the OARSI score were compared. Neither the T1 rho nor the T2 reflected the macroscopic grading. The T1 rho could discriminate between histological grades 1 and 2. However, the T2 could not. The T1 rho relaxation time was higher in the pLFC than in the cLFC even in the same grade. Compared to T2 mapping, T1 rho mapping may have an advantage in differentiating grades I and II cartilage degeneration on OARSI histological grading system.

Utility of T2 mapping and dGEMRIC for evaluation of cartilage repair after allograft chondrocyte implantation in a rabbit model.

OBJECTIVE: To investigate the effectiveness of quantitative Magnetic resonance imaging (MRI) for evaluating the quality of cartilage repair over time following allograft chondrocyte implantation using a three-dimensional scaffold for osteochondral lesions. DESIGN: Thirty knees from 15 rabbits were analyzed. An osteochondral defect (diameter, 4 mm; depth, 1 mm) was created on the patellar groove of the femur in both legs. The defects were filled with a chondrocyte-seeded scaffold in the right knee and an empty scaffold in the left knee. Five rabbits each were euthanized at 4, 8, and 12 weeks and their knees were examined via macroscopic inspection, histological and biochemical analysis, and quantitative MRI (T2 mapping and dGEMRIC) to assess the state of tissue repair following allograft chondrocyte implantation with a three-dimensional scaffold for osteochondral lesions. RESULTS: Comparatively good regenerative cartilage was observed both macroscopically and histologically. In both chondrocyte-seeded and control knees, the T2 values of repair tissues were highest at 4 weeks and showed a tendency to decrease with time. ΔR1 values of dGEMRIC also tended to decrease with time in both groups, and the mean ΔR1 was significantly lower in the CS-scaffold group than in the control group at all time points. ΔR1 = 1/r (R1post - R1pre), where r is the relaxivity of Gd-DTPA(2-), R1 = 1/T1 (longitudinal relaxation time). CONCLUSION: T2 mapping and dGEMRIC were both effective for evaluating tissue repair after allograft chondrocyte implantation. ΔR1 values of dGEMRIC represented good correlation with histologically and biochemically even at early stages after the implantation.

Hidden osteophyte formation on plain X-ray is the predictive factor for development of knee osteoarthritis after 48 months--data from the Osteoarthritis Initiative.

OBJECTIVE: To examine whether the detection of osteophytes anywhere in the knee could serve as a pre-radiographic biomarker for osteoarthritis (OA) development. METHODS: Baseline magnetic resonance imaging (MRIs) of 132 participants in the Osteoarthritis Initiative (OAI) were studied. Based on radiographs, 66 knees were assessed as osteoarthritis-free (no-osteoarthritis [NOA], or Kellgren/Lawrence [K/L] severity grade 0/1 both at baseline and 48 months), and another 66 knees were assessed as having radiographic OA changes (pre-radiographic osteoarthritis [PROA], or with K/L grade 0/1 at baseline and grade ≥ 2 at 48 months). Using baseline MRI data, we examined eight sites of osteophyte formation: the medial and lateral femoral condyle (MFC and LFC, respectively); medial and lateral tibial plateau (MTP and LTP, respectively); medial and lateral facets of the patellofemoral joint (PM and PL, respectively); tibial spine (TS); and femoral intercondylar notch (IC). Knee joint osteophyte size was assessed via the 8-point marginal osteophytes item of the whole-organ magnetic resonance imaging score (WORMS). The frequencies and distributions of osteophytes were compared between groups. RESULTS: Mild-size osteophytes (defined as score ≥ 2) were observed more frequently at the MFC (P = 0.00278), MTP (P = 0.0046), TS (P = 0.0146), PM (P < 0.0001), PL (P = 0.0012), and IC (P < 0.0001) in PROA knees than in NOA knees. Moderate-size osteophytes (defined as score ≥ 4) were more frequently observed in PROA knees than in NOA knees only at the IC (P < 0.0001). CONCLUSION: Knees with osteophyte formation at the IC, even those of K/L severity grade 0/1, are at risk for the development of radiographic OA by 48 months.

Preventive effects of hyaluronan from deterioration of gait parameters in surgically induced mice osteoarthritic knee model.

OBJECTIVE: Osteoarthritis (OA) leads to pain and loss of function in affected joints. Gait disturbance results from these symptoms of OA, and gait analysis can be important to evaluate the progression of OA. The purpose of this study was to analyze gait pattern in a rodent model of OA and to assess the effects of intra-articular injection of hyaluronan (IAI-HA) by gait analysis, along with histological evaluation. DESIGN: OA was induced by destabilization of the medial meniscus (DMM) of C57BL/6 mice. IAI-HA started 3 weeks after DMM surgery. Mice were allocated to three groups and were given either 800-kDa HA (800-HA), 6000-kDa HA (6000-HA) or saline. We compared these three groups with a sham group by gait analysis using CatWalk. Histological evaluation was performed to assess articular cartilage changes in the knee joints. RESULTS: Mice injected with 800-HA or 6000-HA showed gait patterns similar to that of the sham mice, while the saline-injected group showed gait disturbances 12 and 16 weeks after DMM surgery. Histological changes in articular cartilage were similar among the 800-HA, 6000-HA and saline-treated groups, demonstrating OA progression throughout the experimental time points. Positive gait-related effects of IAI-HA might occur by its pain relieving effect and/or by preventing contracture. CONCLUSION: IAI-HA prevented gait disturbances in the DMM model, but did not prevent histological changes associated with OA progression.