2017 ISAKOS Biennial Congress Paper #124


Cut-Off Value for Medial Meniscal Extrusion for Knee Pain

Hiroaki Kijima, MD, PhD, Akita JAPAN
Naohisa Miyakoshi, MD, PhD, Akita JAPAN
Yuji Kasukawa, MD, PhD, Akita JAPAN
Yoshinori Ishikawa, MD, PhD, Akita JAPAN
Hayato Kinoshita, MD, PhD, Akita JAPAN
Kentaro Ohuchi, MD, PhD, Yokote JAPAN
Masazumi Suzuki, MD, PhD, Akita JAPAN
Nozomi Kaga, MD, PhD, Akita JAPAN
Chie Sato, MD, PhD, Odate, Akita JAPAN
Shuichi Chida, MD, PhD, Akita JAPAN
Yoichi Shimada, MD, PhD, Prof., Akita, Akita JAPAN

Akita University, Akita, JAPAN

FDA Status Cleared


Sensitivity and specificity of medial meniscal extrusion for knee pain were very high when the cut-off value for medial meniscal extrusion was set at 4.3 mm.


Purposes: In recent years, various facilities have reported that medial meniscal extrusion (MME) as measured on ultrasonography is related to knee pain. MME has attracted attention as an index associated with clinical symptoms, as opposed to the diagnosis of knee osteoarthritis on X-ray, which does not necessarily relate to the degree of pain. However, the level of MME required to create pain in the knee has not been clarified. We therefore investigated the cut-off level of MME for pain in the knee.


This study examined 318 knees in 159 individuals (77 men, 82 women) who underwent medical examination in a super-advanced-aged area. First, we confirmed by interview whether knee pain was present and whether the individual had a history of knee pain. Next, we measured MME as the degree of medial meniscal displacement from the tibial medial condyle to the deep layer of the medial collateral ligament using vertical sonographic images of medial joint spaces during weight-bearing to target the lower limbs under knee extension.


The mean age of participants was 70 years. Pain was present in 71 knees (Group P) and absent in 247 knees (Group N). MME was 5.9 +/- 1.8 mm in Group P and 2.9 +/- 1.5 mm in Group N. MME was thus significantly larger in Group P than in Group N (Student’s t test, P<0.0001). From analysis of the receiver operating characteristic (ROC) curve, the cut-off MME value for knee pain was 4.3 mm, offering 0.8451 sensitivity and 0.8502 specificity, respectively. In addition, 64% of knees without present pain in which MME exceeded this cut-off had a history of knee pain. This percentage was significantly larger than that of knees without present pain and for which MME did not exceed the cut-off.


Sensitivity and specificity of MME for knee pain were very high when the cut-off value for MME was set at 4.3 mm. In other words, this study clarified that epidemiological investigations of the knee might be easily achieved using ultrasonography. This study suggested not only the possibility that knee pain may develop due to large MME, but also that knee pain resolves after a certain period of time. This study may be connected to the development of new methods for treating knee osteoarthritis based on elucidation of the mechanisms underlying spontaneous relief of pain in knee osteoarthritis.