2015 ISAKOS Biennial Congress ePoster #1114
Patterns of Medial Tibial Articular Cartilage Loss in Varus Osteoarthritic Knees with Torn Posterior Horn of the Medial Meniscus
Makoto Enokida, MD, Yonago JAPAN
Ikuta Hayashi, MD, PhD, Yonago, Tottori JAPAN
Takahiro Yamashita, Yonago City, Tottori Prefecture JAPAN
Hideki Nagashima, MD, PhD, Prof., Yonago JAPAN
Department of Orthopedic Surgery Faculty of Medicine, Tottori University, Yonago, Tottori, JAPAN
FDA Status Not Applicable
Summary: Posterior horn damage of medial meniscus could be an individual risk factor for end-stage knee osteoarthritis.
The posterior horn tear of the medial meniscus causes abnormal medial movement, and, as a result, increases load stress to the joint cartilage. This phenomenon is defined as medial radial displacement (MRD) of the medial meniscus and is regarded as a risk factor for knee osteoarthritis (OA) progression. In this study, we investigated the patterns of medial tibial articular cartilage loss in varus OA knees complicated by torn posterior horn of the medial meniscus.
MATERIALS & METHODS
The pattern of articular cartilage loss at the tibial plateau, status of the cruciate ligaments, and meniscus damage were determined by a single observer at the time of surgery in 82 consecutive patients with varus osteoarthritis (16 male and 66 female; average age, 76 years [range, 60–91]). All patients underwent total knee arthroplasty for primary OA from October 2009 to March 2014. The patients were preoperatively evaluated using the Japanese Orthopedic Association score. To determine the Kellgren/Lawrence radiographic grade, anteroposterior full-extension weight-bearing knee radiographs with fluoroscopic control were obtained from all patients at baseline. The structural and functional assessment of the cruciate ligaments was done intraoperatively. The resected medial tibial plateau was then divided into four equal zones to identify the location of wear. In addition, the depth of eburnation at its deepest point was recorded. The medial meniscus was divided into 3 equal zones (anterior, mid, and posterior segment) to evaluate the location of the tear and deformity. Furthermore, whether the tears were in the posterior and anterior horns of the medial meniscus was assessed.
All the knees had varus deformity of KL grade (3–4). There were 56 (68%) knees with posterior horn tears and 22 (27%) knees with ACL deficiency. In the knees with posterior horn tears, 44 knees had widespread cartilage loss (>3 zones) (p=0.05). In the 16 knees (73%) of the ACL deficiency group, the deepest point of cartilage loss on the medial plateau was predominantly in the posterior zone ( p=0.0007). In addition, 20 knees with posterior horn tear and ACL deficiency had predominantly posterior cartilage loss in contrast to the ACL intact group (p=0.01). In knees with posterior horn tears of the medial meniscus, 28 knees did not have both severe damage of medial meniscal body and ACL deficiency. The comparison between the above mentioned 28 knees and those that had the posterior horn tears with severe damage in the meniscal body did not show statistically significant difference in patterns of articular cartilage loss.
In ACL deficiency knees, 91% had a posterior horn tear of the medial meniscus. Subsequently, those knees had a significantly larger loss of cartilage. Furthermore, cartilage loss was extensive in the 28 (34%) knees with posterior horn tears without both medial meniscus body damage and ACL deficiency but similar to knees with other types of severe meniscus damage. Therefore, it might be proved that posterior horn damage could be an individual risk factor for end-stage knee osteoarthritis.