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Bai D1, Ogawa M2, Tokuda M1, Okamura K2, Tanaka K2, Inagaki Y2, Tanaka Y2
1Heisei Memorial Hospital, Department of Rehabilitation, Nara, Japan, 2Nara Medical University, Department of Orthopedic Surgery, Nara, Japan
Background: Magnetic resonance imaging (MRI) developments, such as T1 rho mapping, provide information associated with cartilage matrix changes and have great potential to provide early detection of cartilage degeneration after anterior cruciate ligament reconstruction (ACLR). Many studies have evaluated the articular cartilage damage before and after ACLR using 2-dimensional (2D) T1rho mapping. However, 3-dimensional (3D) T1rho mapping can evaluate the T1rho value of more than a single-slice image and evaluate whole areas of the knee joint. Therefore, in this study, we tried to evaluate the whole area of femoral trochlea by using 3D T1 rho mapping.
Purpose: The purpose of this study was to evaluate the longitudinal changes in patellofemoral joint cartilage before and after ACLR using 3D T1rho mapping.
Methods: Twenty-eight patients (13 males and 15 females) who underwent ACLR were recruited in this study. The injured knee and the contralateral uninjured knee was imaged using a 3 Tesla MRI (Achieva 3 Tesla, Phillips Medical System, Best, The Netherlands) at 1 week before ACLR and second surgery. The contralateral uninjured knee was used as an internal control. Image analysis was conducted using the AZE virtual place software (AZE, Tokyo, Japan). The region of interest (ROI) was manually defined on the patellofemoral joint (femoral trochlea). Patients were divided into 2 groups based on the presence of a cartilage lesion on second-look arthroscopy (Early group, patellofemoral joint cartilage lesion; Intact group, intact articular cartilage). T-tests identified the demographic information (age, weight, height, period from injury to operation), Lysholm score, anterior tibial translation on KT-1000 testing (KT-1000) and the T1 rho values of femoral trochlea between Early group and Intact group.
Results: The reproducibility of the ROI setting according to the intra-rater reliability was 0.993 (95% CI, 0.983-0.997), and inter-rater reliability was 0.947 (95% CI, 0.878-0.977). There was no patellofemoral joint cartilage degeneration before surgery in any of the patients. However, 8 patients (28.5%) had cartilage degeneration of the femoral trochlea on second-look arthroscopy (ICRS classification: grade 1a: 2 patients, grade 1b: 1 patients, grade 2: 5 patients). There were no differences about the demographic information, Lysholm score and KT-1000 between 2 groups. T1 rho values of femoral trochlea with ACLR knee in Early group were significantly elevated compared with those of the control knee and the Intact group.
Conclusion(s): We applied a novel 3D T1rho MRI technique to evaluate the longitudinal change in patellofemoral joint cartilage before and after ACLR. Early cartilage degeneration was observed in 28.5% of cases in the femoral trochlea on second-look arthroscopy about 1 year after ACLR. T1 rho values of femoral trochlea with ACLR knee in Early group were significantly elevated than the control knee in the Early group and the Intact group. The surface of the femoral trochlea in the patellofemoral joint has a complex shape. Therefore, 3D T1 rho mapping might be more useful evaluation tool than 2D.
Implications: Our results suggest that 3D T1 rho mapping might serve as an imaging tool for the early cartilage degeneration of patellofemoral joint after ACLR.
Keywords: Anterior cruciate ligament injury, patellofemoral joint, 3-dimensional T1 rho mapping
Funding acknowledgements: No funding was received for this study.
Purpose: The purpose of this study was to evaluate the longitudinal changes in patellofemoral joint cartilage before and after ACLR using 3D T1rho mapping.
Methods: Twenty-eight patients (13 males and 15 females) who underwent ACLR were recruited in this study. The injured knee and the contralateral uninjured knee was imaged using a 3 Tesla MRI (Achieva 3 Tesla, Phillips Medical System, Best, The Netherlands) at 1 week before ACLR and second surgery. The contralateral uninjured knee was used as an internal control. Image analysis was conducted using the AZE virtual place software (AZE, Tokyo, Japan). The region of interest (ROI) was manually defined on the patellofemoral joint (femoral trochlea). Patients were divided into 2 groups based on the presence of a cartilage lesion on second-look arthroscopy (Early group, patellofemoral joint cartilage lesion; Intact group, intact articular cartilage). T-tests identified the demographic information (age, weight, height, period from injury to operation), Lysholm score, anterior tibial translation on KT-1000 testing (KT-1000) and the T1 rho values of femoral trochlea between Early group and Intact group.
Results: The reproducibility of the ROI setting according to the intra-rater reliability was 0.993 (95% CI, 0.983-0.997), and inter-rater reliability was 0.947 (95% CI, 0.878-0.977). There was no patellofemoral joint cartilage degeneration before surgery in any of the patients. However, 8 patients (28.5%) had cartilage degeneration of the femoral trochlea on second-look arthroscopy (ICRS classification: grade 1a: 2 patients, grade 1b: 1 patients, grade 2: 5 patients). There were no differences about the demographic information, Lysholm score and KT-1000 between 2 groups. T1 rho values of femoral trochlea with ACLR knee in Early group were significantly elevated compared with those of the control knee and the Intact group.
Conclusion(s): We applied a novel 3D T1rho MRI technique to evaluate the longitudinal change in patellofemoral joint cartilage before and after ACLR. Early cartilage degeneration was observed in 28.5% of cases in the femoral trochlea on second-look arthroscopy about 1 year after ACLR. T1 rho values of femoral trochlea with ACLR knee in Early group were significantly elevated than the control knee in the Early group and the Intact group. The surface of the femoral trochlea in the patellofemoral joint has a complex shape. Therefore, 3D T1 rho mapping might be more useful evaluation tool than 2D.
Implications: Our results suggest that 3D T1 rho mapping might serve as an imaging tool for the early cartilage degeneration of patellofemoral joint after ACLR.
Keywords: Anterior cruciate ligament injury, patellofemoral joint, 3-dimensional T1 rho mapping
Funding acknowledgements: No funding was received for this study.
Topic: Orthopaedics; Sport & sports injuries
Ethics approval required: Yes
Institution: Nara Medical University
Ethics committee: Nara Medical University
Ethics number: H25-20
All authors, affiliations and abstracts have been published as submitted.
