Purpose: Osteoarthritis (OA) of the knee is the joint disease that is most commonly encountered in clinical practice. Because the articular cartilage is difficult to regenerate, artificial knee replacement is often performed in patients who have end‐stage knee OA and thus have relatively severe symptoms such as pain, instability and limited range of motion. However, to reduce the economic burden on the healthcare system and on patients, it would be desirable to establish conservative therapy that could alleviate symptoms and prevent progression of OA which is increasing in aging society. As T11rho (or T1 relaxation time in rotating frame)‐weighted MRI has recently been proposed as a promising biomarker for cartilage degeneration, it should be useful for evaluating conservative treatments for OA of the knee. The purpose of this study was to determine what characteristics are associated with improvement in OA of the knee in patients who underwent T11rho mapping at different points in time while receiving conservative treatment. Methods: The subjects were 47 patients who underwent T11rho mapping before and after treatment. Thirteen were men, the mean age was 57.6 years, and the follow‐up duration ranged from 2 to 36 months with an average duration of 13.2 months. As treatment, 32 were receiving intraarticular hyaluronic acid injections, 3 were receiving oral glucosamine, and 12were receiving physical therapy. T11rho relaxation times of articular cartilage were measured using 3.0T MRI. 3D T11rho‐weighted fast field echo imaging was performed for T11rho quantification. After direct segmentation by referring to the proton density weighted (PDW) images, six regions of interest (ROI) were selected in the medial femorotibial articular cartilage in the coronal plane. Changes of 10% or greater in T11rho values in at least 4 ROI were considered notable, with a decrease of this magnitude indicating improvement and an increase of this magnitude indicating worsening of the pathological condition. No change in OA was considered if any other result was noted. The duration of symptoms, the Kellgren‐Lawrence (KL) grade on plain X‐ray images, the slope angles of the articular surface of the tibia, and tears in the posterior segment and posterior horn of the meniscus on normal MRI images were compared. Results: Of the 47 patients, 8 showed improvement, 11 worsened, and 28 showed no change. Though some cases worsened in as little as 2 months, it took at least 6 months to see improvement in all improved cases. Of the 20 patients who received intra‐articular hyaluronic acid injections continuously for at least 6 months (every 2 weeks or every 4 weeks), 7 showed improvement on T11rho mapping (88% of patients that showed improvement), 4 worsened, and 9 showed no change. Of the patients who received exercise therapy continuously for at least 6 months, 1 showed improvement, 3 worsened, and 5 showed no change. All patients that showed improvement were women with a difference of 5degree or less between the slope angles of the medial and lateral tibial plateaus. Age, duration of symptoms, KL grade, and tears in the posterior segment and posterior horn of the meniscus did not differ from patients whose condition worsened. Conclusions: This study was not a randomized controlled trial, but the results demonstrated that conservative treatment lasting at least 6 months can reduce cartilage degeneration on T11rho mapping. Though there was no significant difference, the majority of patients that showed improvement were receiving intra‐articular hyaluronic acid injections for a long time. This topic must be examined further in a prospective comparative study.
Takahashi, K., Hashimoto, S., Nakamura, H., Masaki, T., Ito, T., Mochizuki, Y., … Majima, T. (2016). T1rho relaxation mapping with MRI as a measure of the therapeutic effect of conservative treatments for osteoarthritis of the knee. Osteoarthritis and Cartilage, 24, S310. https://doi.org/10.1016/j.joca.2016.01.558