To investigate the short and medium term curative effect, patella bounce and causes of knee valvular osteoarthritis treated by monocondylar replacement.

Eighty-four patients (84 knees) with medial compartment osteoarthritis of the knee underwent unicondylar replacement in the First Affiliated Hospital of Zhejiang University from July 2017 to May 2019. The clinical treatment was retrospectively analyzed.Independent sample t test was used to compare the knee function of the patients before surgery and at the last follow-up (one year after surgery). Hospital for Special Surgery knee score (HSS), knee range of motion (ROM), visual analogue scale (VAS), and lower limb strength line including tibial angle (FTA) and hip-knee-ankle angle (HKA) were measured, and complications were recorded.

All the surgical incisions were healed at grade A and all the patients were followed up. Twenty-four hours after the operation, the drainage volume was (121±81) ml on average. Four patients received allogeneic transfusion, and the transfusion rate was 4.76%.VAS score of the patients in the last follow-up was lower than that before surgery (t=70.721, P<0.05), and HSS score and ROM of the patients in the last follow-up were higher than that before surgery (t=-37.6, -6.800; both P<0.05). The HKA angle in the last follow-up was higher than that before the surgery (t=-10.965, P<0.05), and the FTA angle in the last follow-up was lower than that before the surgery (t=14.022, P<0.05). Two patients had patella flapping when bending the knee, and four patients had knee valgus after the surgery. All the complications healed by themselves at the last follow-up.

The short-term efficacy of monocondylar replacement for medial compartment osteoarthritis is satisfactory, but it requires surgeons to pay attention to avoid complications during the operation.