Patterns of joint damage seen on MRI in early hip osteoarthritis due to structural hip deformities.

OBJECTIVE: The aim of this study was to evaluate differences in damage patterns assessed using magnetic resonance imaging (MRI) between hips with femoroacetabular impingement (FAI) and developmental dysplasia of the hip (DDH) as well as to correlate MRI findings with delayed Gadolinium enhanced MRI of cartilage (dGEMRIC) and with patient pain. DESIGN: This retrospective study included 40 patients (mean age 28.6 ± 11.2 years) who underwent dGEMRIC and morphological MRI of the hip. Twenty-one hips with FAI and 19 with DDH were investigated. A self-developed morphological grading (MRI score) and dGEMRIC evaluation were done on seven radial reformats obtained from an isotropic 3D True-fast imaging with steady state precession (FISP) sequence and an isotropic T1-mapping sequence. The observed damage patterns were summed up into sub-scores and a total MRI score. RESULTS: Labrum damage, paralabral cysts, and acetabular rim bone cysts were more common in DDH patients than in FAI patients. No significant differences were seen in the occurrence of cartilage damage, bone cysts, or osteophytes. In DDH (but not in FAI), the dGEMRIC index demonstrated a tendency for lower values in areas next to cartilage defects. There was no association between labrum damage and dGEMRIC index. A moderate correlation was seen between Western Ontario and McMaster Universities (WOMAC) pain score and cartilage damage, paralabral cysts, and the total MRI score. CONCLUSIONS: This study confirms a higher prevalence of labrum damage but not cartilage damage in patients with DDH in comparison to patients with FAI. In addition, our data suggests an association of cartilage damage and paralabral cysts with patient reported pain.

Cartilage repair of the ankle: first results of T2 mapping at 7.0 T after microfracture and matrix associated autologous cartilage transplantation.

BACKGROUND: Both microfracture (MFX) and matrix associated autologous cartilage transplantation (MACT) are currently used to treat cartilage defects of the talus. T2 mapping of the ankle at 7 T has the potential to assess the collagen fibril network organization of the native hyaline cartilage and of the repair tissue (RT). This study provides first results regarding the properties of cartilage RT after MFX (mean follow-up: 113.8 months) and MACT (65.4 months). METHODS: A multi-echo spin-echo sequence was used at 7 T to assess T2 maps in 10 volunteer cases, and in 10 cases after MFX and MACT each. Proton weighted morphological images and clinical data were used to ensure comparable baseline criteria. RESULTS: A significant zonal variation of T2 was found in the volunteers. T2 of the superficial and the deep layer was 39.3 ± 5.9 ms and 21.1 ± 3.1 ms (zonal T2 index calculated by superficial T2/deep T2: 1.87 ± 0.2, P < 0.001). In MFX, T2 of the reference cartilage was 37.4 ± 5.0 ms and 25.3 ± 3.5 ms (1.51 ± 0.3, P < 0.001). In the RT, T2 was 43.4 ± 10.5 ms and 36.3 ± 7.7 ms (1.20 ± 0.2, P = 0.009). In MACT, T2 of the reference cartilage was 39.0 ± 9.1 ms and 27.1 ± 6.6 ms (1.45 ± 0.2, P < 0.001). In the RT, T2 was 44.6 ± 10.4 ms and 38.6 ± 7.3 ms (1.15 ± 0.1, P = 0.003). The zonal RT T2 variation differed significantly from the reference cartilage in both techniques (MFX: P = 0.004, MACT: P = 0.001). CONCLUSION: T2 mapping at 7 T allows for the quantitative assessment of the collagen network organization of the talus. MACT and MFX yielded RT with comparable T2 properties.

Assessment of articular cartilage repair tissue after matrix-associated autologous chondrocyte transplantation or the microfracture technique in the ankle joint using diffusion-weighted imaging at 3 Tesla.

OBJECTIVE: The objective was to compare patients after matrix-associated autologous chondrocyte transplantation (MACT) and microfracture therapy (MFX) of the talus using diffusion-weighted imaging (DWI), with morphological and clinical scoring. MATERIALS AND METHODS: Twenty patients treated with MACT or MFX (10 per group) were examined using 3 T magnetic resonance imaging (MRI) at 48 ± 21.5 and 59.6 ± 23 months after surgery, respectively. For comparability, patients from each group were matched by age, body mass index, and follow-up. American Orthopaedic Foot and Ankle Society (AOFAS) score served as clinical assessment tool pre- and postoperatively. DWI was obtained using a partially balanced, steady-state gradient echo pulse sequence, as well as the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, based on a 2D proton density-weighted turbo spin-echo sequence and a 3D isotropic true fast imaging with steady-state precession sequence. Semi-quantitative diffusion quotients were calculated after region of interest analysis of repair tissue (RT) and healthy control cartilage, and compared among both groups. RESULTS: The mean AOFAS score improved significantly (P = 0.001) for both groups (MACT: 48.8 ± 20.4-83.6 ± 9.7; MFX: 44.3 ± 16.5-77.6 ± 13.2). No differences in the AOFAS (P = 0.327) and MOCART (P = 0.720) score were observed between MACT and MFX postoperatively. DWI distinguished between healthy cartilage and cartilage RT in the MFX group (P = 0.016), but not after MACT treatment (P = 0.105). Significant correlations were found between MOCART score and DWI index after MFX (Pearson: -0.648; P = 0.043), and between the diffusivity and longer follow-up interval in MACT group (Pearson: -0.647, P = 0.043). CONCLUSION: Whereas conventional scores reveal a similar outcome after MACT or MFX treatment in the ankle joint, DWI was able to distinguish between different RT qualities, as reported histologically for these diverse surgical procedures.

Evaluation of native hyaline cartilage and repair tissue after two cartilage repair surgery techniques with 23Na MR imaging at 7 T: initial experience.

OBJECTIVE: To compare the sodium normalized mean signal intensity (NMSI) values between patients after bone marrow stimulation (BMS) and matrix-associated autologous chondrocyte transplantation (MACT) cartilage repair procedures. METHODS: Nine BMS and nine MACT patients were included. Each BMS patient was matched with one MACT patient according to age [BMS 36.7 ± 10.7 (mean ± standard deviation) years; MACT 36.9 ± 10.0 years], postoperative interval (BMS 33.5 ± 25.3 months; MACT 33.2 ± 25.7 months), and defect location. All magnetic resonance imaging (MRI) measurements were performed on a 7 T system. Proton images served for morphological evaluation of repair tissue using the magnetic resonance observation of cartilage repair tissue (MOCART) scoring system. Sodium NMSI values in the repair area and morphologically normal cartilage were calculated. Clinical outcome was assessed right after MRI. Analysis of covariance, t-tests, and Pearson correlation coefficients were evaluated. RESULTS: Sodium NMSI was significantly lower in BMS (P = 0.004) and MACT (P = 0.006) repair tissue, compared to reference cartilage. Sodium NMSI was not different between the reference cartilage in MACT and BMS patients (P = 0.664), however it was significantly higher in MACT than in BMS repair tissue (P = 0.028). Better clinical outcome was observed in BMS than in MACT patients. There was no difference between MOCART scores for MACT and BMS patients (P = 0.915). We did not observe any significant correlation between MOCART score and sodium repair tissue NMSI (r = -0.001; P = 0.996). CONCLUSIONS: Our results suggest higher glycosaminoglycan (GAG) content, and therefore, repair tissue of better quality in MACT than in BMS patients. Sodium imaging might be beneficial in non-invasive evaluation of cartilage repair surgery efficacy.

Bernese periacetabular osteotomy in males: is there an increased risk of femoroacetabular impingement (FAI) after Bernese periacetabular osteotomy?

BACKGROUND: The Bernese periacetabular osteotomy (PAO) is a popular option for treating symptomatic acetabular dysplasia. We noted symptomatic impingement after PAO in several male patients. QUESTIONS/PURPOSES: We therefore determined (1) the incidence of clinical signs of FAI after PAO in the male population; and (2) whether any factors were associated with the positive impingement signs after PAO in males. PATIENTS AND METHODS: We retrospectively reviewed 38 males who underwent 46 periacetabular osteotomies (PAO) between 2000 and 2007. Clinical and radiographic data were analyzed with the focus on pre- and postoperative incidence of femoroacetabular impingement. Minimum followup was 12 months (average, 43 months; range, 12-90 months). RESULTS: We found a positive impingement sign in 19 of the 46 hips during the preoperative examination compared to 22 (47.8%) hips postoperatively. The ROM (flexion and internal rotation) decreased postoperatively compared to preoperatively. Radiographic parameters of coverage LCE-, ACE- and Tönnis angle improved into the normal range. Twenty hips had postoperative heterotopic ossification to varying degrees, mostly minor. WOMAC scores improved in the function and pain domains postoperatively. CONCLUSIONS: Despite normalization of coverage we found a high postoperative rate of clinical signs of FAI after PAO in males. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Radial dGEMRIC in developmental dysplasia of the hip and in femoroacetabular impingement: preliminary results.

OBJECTIVE: To assess the pattern of cartilage damage in symptomatic cases of developmental dysplasia of the hip (DDH) and of femoroacetabular impingement (FAI) with a novel three-dimensional (3D) delayed Gadolinium enhanced magnetic resonance imaging of cartilage (dGEMRIC) technique. METHODS: After clinical diagnosis with conventional radiographs, two consecutive series of each 20 patients with DDH or FAI were assessed with 3D dGEMRIC. Radial T1 maps were reconstructed and region of interest analysis of the central and peripheral cartilage was carried out. RESULTS: The dGEMRIC index was mean 531 ± 92.7 (391-729) ms in DDH and 551 ± 95.7 (372-694) ms in FAI, respectively (P=0.507). Subgroup analysis showed higher T1 in the weight-bearing areas and significantly higher values in the central areas (DDH P<0.0001, N=11; FAI P=0.036, N=14) of the acetabulum in pre-arthritic cases (dGEMRIC index>500 ms) both in DDH and FAI. A breakdown of this distribution was found both in DDH and FAI cases with dGEMRIC index<500 ms. Pearson correlation analysis demonstrated the dGEMRIC index had a poor predictive value for the anterior-superior quadrant of the hip joint in FAI (r=0.482, P=0.031, r(2)=0.233). CONCLUSION: Radial dGEMRIC allows for the assessment of cartilage damage in the entire hip; different patterns of T1 distribution are found in DDH and FAI at progressed stages. The assessment of the anterior-superior quadrant of the acetabulum can be considered a fundamental advantage of the 3D dGEMRIC protocol.

Multimodal approach in the use of clinical scoring, morphological MRI and biochemical T2-mapping and diffusion-weighted imaging in their ability to assess differences between cartilage repair tissue after microfracture therapy and matrix-associated autologous chondrocyte transplantation: a pilot study.

OBJECTIVE: The aim of the present pilot study is to show initial results of a multimodal approach using clinical scoring, morphological magnetic resonance imaging (MRI) and biochemical T2-relaxation and diffusion-weighted imaging (DWI) in their ability to assess differences between cartilage repair tissue after microfracture therapy (MFX) and matrix-associated autologous chondrocyte transplantation (MACT). METHOD: Twenty patients were cross-sectionally evaluated at different post-operative intervals from 12 to 63 months after MFX and 12-59 months after MACT. The two groups were matched by age (MFX: 36.0+/-10.4 years; MACT: 35.1+/-7.7 years) and post-operative interval (MFX: 32.6+/-16.7 months; MACT: 31.7+/-18.3 months). After clinical evaluation using the Lysholm score, 3T-MRI was performed obtaining the MR observation of cartilage repair tissue (MOCART) score as well as T2-mapping and DWI for multi-parametric MRI. Quantitative T2-relaxation was achieved using a multi-echo spin-echo sequence; semi-quantitative diffusion-quotient (signal intensity without diffusion-weighting divided by signal intensity with diffusion weighting) was prepared by a partially balanced, steady-state gradient-echo pulse sequence. RESULTS: No differences in Lysholm (P=0.420) or MOCART (P=0.209) score were observed between MFX and MACT. T2-mapping showed lower T2 values after MFX compared to MACT (P=0.039). DWI distinguished between healthy cartilage and cartilage repair tissue in both procedures (MFX: P=0.001; MACT: P=0.007). Correlations were found between the Lysholm and the MOCART score (Pearson: 0.484; P=0.031), between the Lysholm score and DWI (Pearson:-0.557; P=0.011) and a trend between the Lysholm score and T2 (Person: 0.304; P=0.193). CONCLUSION: Using T2-mapping and DWI, additional information could be gained compared to clinical scoring or morphological MRI. In combination clinical, MR-morphological and MR-biochemical parameters can be seen as a promising multimodal tool in the follow-up of cartilage repair.

MR imaging of cartilage and its repair in the knee--a review.

Chondral injuries are common lesions of the knee joint, and many patients could benefit from cartilage repair. Widespread cartilage repair techniques require sophisticated noninvasive follow-up using MRI. In addition to the precise morphological assessment of this area of cartilage repair, the cartilage's biochemical constitution can be determined using biochemical MRI techniques. The combination of the clinical outcome after cartilage repair together with the morphological and biochemical description of the cartilage repair tissue as well as the surrounding cartilage can lead to an optimal follow-up evaluation. The present article on MR imaging techniques of cartilage repair focuses on morphological description and scoring using techniques from conventional 2D through advanced isotropic 3D MRI sequences. Furthermore the ultrastructure of the repair tissue and the surrounding cartilage is evaluated in-vivo by biochemical T1-delayed gadolinium enhanced MRI of cartilage (dGEMRIC), T2 relaxation, and diffusion-weighted imaging techniques.

Results of chondrocyte implantation with a fibrin-hyaluronan matrix: a preliminary study.

UNLABELLED: Fibrin, a homologous polymer, is the natural scaffold of wound healing and therefore a candidate as a carrier for cell transplantation. We explored a novel matrix-based implant cartilage repair composed of both fibrin and hyaluronan in a defined ratio that takes advantage of the biological and mechanical properties of these two elements. The matrix was seeded with autologous chondrocytes expanded in the presence of a proprietary growth factor variant designed to preserve their chondrogenic potential. We prospectively followed eight patients with symptomatic-chronic cartilage defects treated with this carrier. Patients had arthroscopy to harvest autologous chondrocytes then grown in autologous serum. Chondrocytes were cultured in the presence of the FGF variant and then seeded on the fibrin-hyaluronan matrix. About 4 weeks following biopsy, the patients underwent implantation of the constructs by miniarthrotomy. Three of the eight patients had transient effusion. Clinical performance was measured by Lysholm and IKDC scores, MRI, and the need for secondary surgery. The clinical outcome of a 1-year followup demonstrated increase of clinical scores. The MRI followup showed good filling of the defect with tissue having the imaging appearance of cartilage in all patients. Apart from the transient effusion in three patients we observed no other adverse events during the followup. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Three-year clinical outcome after chondrocyte transplantation using a hyaluronan matrix for cartilage repair.

Repair of articular cartilage represents a significant clinical problem and although various new techniques - including the use of autologous chondrocytes - have been developed within the last century the clinical efficacy of these procedures is still discussed controversially. Although autologous chondrocyte transplantation (ACT) has been widely used with success, it has several inherent limitations, including its invasive nature and problems related to the use of the periosteal flap. To overcome these problems autologous chondrocytes transplantation combined with the use of biodegradable scaffolds has received wide attention. Among these, a hyaluronan-based scaffold has been found useful for inducing hyaline cartilage regeneration. In the present study, we have investigated the mid-term efficacy and safety of Hyalograft C grafts in a group of 36 patients undergoing surgery for chronic cartilage lesions of the knee. Clinical Outcome was assessed prospectively before and at 12, 24, and 36 months after surgery. No major adverse events have been reported during the 3-year follow-up. Significant improvements of the evaluated scores were observed (P < 0.02) at 1 year and a continued increase of clinical performance was evident at 2 and 3 years follow-up. Patients under 30 years of age with single lesions showed statistically significant improvements at all follow-up visits compared to those over 30 with multiple defects (P < 0.01). Hyalograft C compares favorably with classic ACT and is particularly indicated in younger patients with single lesions. The graft can be implanted through a miniarthrotomy and needs no additional fixation with sutures except optional fibrin gluing at the defect borders. These results suggest that Hyalograft C is a valid alternative to ACT.

Primary cementless total hip arthroplasty with second-generation metal-on-metal bearings: a concise follow-up, at a minimum of seventeen years, of a previous report.

BACKGROUND: Second-generation, metal-on-metal bearings were introduced in 1988, to reduce wear and avoid polyethylene particle-induced osteolysis from total hip arthroplasty. In 2007, we reported the long-term results of ninety-eight patients (105 hips) who underwent primary cementless total hip arthroplasty involving the use of a prosthesis with a high-carbide-concentration, metal-on-metal articulating surface between November 1992 and May 1994. The present study gives an update on this patient cohort. METHODS: At a minimum of seventeen years postoperatively, forty-nine patients (fifty-two hips) were available for follow-up examination. We retrospectively evaluated clinical and radiographic results as well as serum metal concentration. The mean patient age at the time of the index arthroplasty was fifty-six years. RESULTS: Three cups (6% of the hips) and one stem (2% of the hips) were revised because of aseptic loosening of the implants combined with focal osteolysis. At the time of the latest follow-up evaluation, the mean Harris hip score was 88.8 points, and the mean University of California Los Angeles (UCLA) activity score was 6.7 points. The cumulative rate of implant survival, with aseptic failure as the end point, was 93.0% at 18.8 years. The median serum cobalt concentration in patients whose hip implant was the only source of cobalt was 0.70 µg/L (range, 0.4 to 5.1 µg/L), showing no increase in the value as noted at a minimum of ten years of follow-up. CONCLUSIONS: The clinical and radiographic results of our study, which, to our knowledge, represent the longest duration of follow-up for a series of cementless total hip arthroplasties with use of a 28-mm metal-on-metal bearing, continue to be comparable with the results observed for other hard-on-hard bearings.

Matrix-Associated and Autologous Chondrocyte Transplantation in the Ankle: Clinical and MRI Follow-up after 2 to 11 Years.

BACKGROUND: New matrix-associated autologous chondrocyte transplantation (MACT) techniques may facilitate the treatment of chondral defects in talar cartilage and provide good clinical outcome in the long term. The aim of this prospective case series was to monitor the clinical outcome after autologous chondrocyte transplantation (ACT) and MACT in the ankle to gain data on the mid-term efficacy of the procedure. METHODS: Seventeen cases of talar cartilage defects were assessed with the American Orthopaedic Foot and Ankle Score (AOFAS), a modified Cincinnati score, and a subjective ankle-hindfoot score (AHS) at a mean of 61 (24-135) months after surgery. Nine patients consented to an additional magnetic resonance imaging (MRI) exam, including T2 mapping at 3T. ACT was carried out with a periosteal flap (4 cases) or with a matrix-assisted ACT technique (Hyalograft C; 13 cases). RESULTS: Significant improvement was found in all cases. The AOFAS improved from 50.0 to 87.3, the AHS from 43.8 to 84.1, and the modified Cincinnati score from 2.9 to 6.9. MRI data demonstrated good defect filling, and T2 mapping results indicated that the collagen and water content of the repair tissue was comparable to adjacent cartilage. DISCUSSION: MACT and ACT in the ankle can provide good and excellent long-term outcome and resulted in repair tissue with T2 properties similar to native cartilage in the majority of cases. Matrix-assisted implantation with the hyaluronan matrix allows for a less invasive surgical procedure. LEVEL OF EVIDENCE: 4; prospective case series study.

Femoroacetabular cam-type impingement: diagnostic sensitivity and specificity of radiographic views compared to radial MRI.

PURPOSE: To retrospectively assess the diagnostic sensitivity of 45° Dunn view and cross-table lateral radiographs for the assessment of cam deformity by comparison with radial MRI. MATERIALS AND METHODS: 60 cases with radiographs (38 a-p and 45° Dunn views, 22 a-p and cross-table lateral views) and radial MRI were assessed. Alpha angle measurements were obtained both for radiographs and radial MRI. Statistics included frequency analysis, bivariate linear correlation analyses of MRI and radiograph measurements and cross-table analyses testing for the sensitivity and specificity of radiographs for the detection of an alpha angle larger than 55°. RESULTS: 53.3% had the maximum alpha angle in the superior-anterior aspect of the femoral head-neck junction. Cam deformity was found in 45/60 cases (75%) in radial MRI. Pearson correlation demonstrated the Dunn view was most accurate for the superior-anterior aspect (.772, P<.001). The cross-table lateral views were best suited for the anterior-superior aspect (.511, P<.05). The sensitivity for cam deformity in the Dunn view was 96.4% vs. 70.6% in the cross-table lateral view. CONCLUSION: The 45° Dunn view can improve the first line of impingement diagnostics. Radial MRI however remains indispensable for pre-operative planning and the evaluation of symptomatic cases without obvious deformity.

Microfracture in the Ankle: Clinical Results and MRI with T2-Mapping at 3.0 T after 1 to 8 Years.

BACKGROUND: Microfracture (MFX) is frequently used to treat deep cartilage defects in the ankle; however, the data on repair tissue (RT) quality after MFX are very limited at this time. T2-mapping at 3 T has been optimized for the ankle and can be used to noninvasively evaluate cartilage collagen and water content. The aim of this study was to determine if the RT after MFX in the ankle had T2 properties similar to the adjacent reference cartilage (RC). METHODS: Fourteen cases after MFX in the ankle were assessed with morphological MRI and T2-mapping at 3 T. The American Orthopaedic Foot and Ankle Society (AOFAS) score and a modified Cinicinnati Knee Rating System rating were used to evaluate the clinical outcome. The MRI protocol included a 3-dimensional sequence and a proton-density sequence for morphological evaluation and a multiecho spin echo sequence for T2-mapping. Region of interest analyses were carried out in accordance with the morphological images to ensure complete coverage of the defect site. RESULTS: Both clinical scores demonstrated significant improvement at the time of the MR examination (P < 0.001). RT T2 was 49.3 ± 10.1 (range, 35.7-69.3) milliseconds, and RC T2 was 49.9 ± 8.2 (range, 38.4-63.7) milliseconds (P = 0.838). Relative T2 (rT2) was 1.00 ± 0.20 (range, 0.72-1.36). CONCLUSION: MFX in the ankle can provide RT with T2 properties similar to adjacent cartilage.

T2 mapping and dGEMRIC after autologous chondrocyte implantation with a fibrin-based scaffold in the knee: preliminary results.

OBJECTIVE: To assess repair tissue (RT) after the implantation of BioCartII, an autologous chondrocyte implantation (ACI) technique with a fibrin-hyaluronan polymer as scaffold. T2 mapping and delayed Gadolinium Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) were used to gain first data on the biochemical properties of BioCartII RT in vivo. METHODS: T2 mapping and dGEMRIC were performed at 3T in five patients (six knee joints) who had undergone ACI 15-27 months before. T2 maps were obtained using a pixel wise, mono-exponential non-negative least squares fit analysis. For quantitative T1 mapping a dual flip angle 3D GRE sequence was used and T1 maps were calculated pre- and post-contrast using IDL software. Subsequent region of interest analysis was carried out in comparison with morphologic MRI. RESULTS: A spatial variation of T2 values in both hyaline, normal cartilage (NC) and RT was found. Mean RT T2 values and mean NC T2 values did not differ significantly. Relative T2 values were calculated from global RT and NC T2 and showed a small range (0.84-1.07). The relative delta relaxation rates (rDeltaR1) obtained from the T1 maps had a wider range (0.77-4.91). CONCLUSION: T2 mapping and dGEMRIC provided complementary information on the biochemical properties of the repair tissue. BioCartII apparently can provide RT similar to hyaline articular cartilage and may become a less-invasive alternative to ACI with a periosteal flap.

T2 mapping in the knee after microfracture at 3.0 T: correlation of global T2 values and clinical outcome - preliminary results.

OBJECTIVE: The aim of our study was to correlate global T2 values of microfracture repair tissue (RT) with clinical outcome in the knee joint. METHODS: We assessed 24 patients treated with microfracture in the knee joint. Magnetic resonance (MR) examinations were performed on a 3T MR unit, T2 relaxation times were obtained with a multi-echo spin-echo technique. T2 maps were obtained using a pixel wise, mono-exponential non-negative least squares fit analysis. Slices covering the cartilage RT were selected and region of interest analysis was done. An individual T2 index was calculated with global mean T2 of the RT and global mean T2 of normal, hyaline cartilage. The Lysholm score and the International Knee Documentation Committee (IKDC) knee evaluation forms were used for the assessment of clinical outcome. Bivariate correlation analysis and a paired, two tailed t test were used for statistics. RESULTS: Global T2 values of the RT [mean 49.8ms, standards deviation (SD) 7.5] differed significantly (P<0.001) from global T2 values of normal, hyaline cartilage (mean 58.5ms, SD 7.0). The T2 index ranged from 61.3 to 101.5. We found the T2 index to correlate with outcome of the Lysholm score (r(s)=0.641, P<0.001) and the IKDC subjective knee evaluation form (r(s)=0.549, P=0.005), whereas there was no correlation with the IKDC knee form (r(s)=-0.284, P=0.179). CONCLUSION: These findings indicate that T2 mapping is sensitive to assess RT function and provides additional information to morphologic MRI in the monitoring of microfracture.