2015 ISAKOS Biennial Congress ePoster #1451

Radiological Assessment and Clinical Outcome of Unicompartmental Knee Arthroplasty in the Elderly

Kazuki Morizane, MD, Matsuyama-City, Ehime-Pref JAPAN
Fumihiko Konishi, MD, Matsuyama JAPAN
Yasuo Sone, MD, Niihama JAPAN
Hiroshi Kiyomatsu, MD, PhD, Toon-City, Ehime JAPAN

Ehime Seikyo Hospital, Matsuyama-c, Ehime Pref., JAPAN

FDA Status Not Applicable

Summary: In low activity, low BMI elderly, postoperative genu varum in UKA does not seem to affect the course of the surgery.




In Japan, unicompartmental knee arthroplasty (UKA) has been adapted to many elderly. These elderly patients have a relatively sedentary lifestyle, low demands and fewer expectations. Some registry data have confirmed that patients older than 65 years of age have lower rates of revision and better outcomes with regards to survival, compared to those less than 65 years of age.

Materials And Methods

We underwent UKA in the low body mass index (BMI), low activity elderly patients. 42 patients (63 knees) were enrolled under diagnosis of medial osteoarthritis (59 knees) and osteonecrosis (4 knees). The mean age at the time of operation was 76 years (66 to 91), and comprised 33 females and 9 males. The mean follow-up was 43 months (12-70). Radiological assessment was carried out pre- and post-operatively related to the tibiofemoral angle (TFA). In 31 patients (49 knees) of all, mechanical axis (MA) under weight bearing could be measured.


TFA was 182.7°, 176.8° at pre- and post-operation, and the average of valgus correction angle was 5.9°. MA passed 6.7%, 27.9% at pre- and post-operation, and moved 21.2 points laterally. MA of 41 UKAs (83.7%) passed the medial side of the knee postoperatively. There were 3 further operations related UKA, an incidence of 4.8%; 2 (3.2%) were deep infection; 1 (1.6%) was bearing dislocation. But no component was loosening.


UKA determines the alignment of postoperative ligament balance by preoperative rather than surgery to correct the bony alignment as TKA. In the cases of severe genu varum before surgery, mild varus deformity was left postoperatively. In low activity, low BMI elderly, the load is distributed by the ligament balance even if varus deformity were remaining, and the component is less likely to collapse.


With respect of UKA of the elderly, postoperative genu varum does not seem to affect the course of the surgery.