ObjectiveTo investigate the short-term effectiveness of unicompartmental knee arthroplasty (UKA) in the treatment of knee osteoarthritis of super-age patients over 85 years old.MethodsSenile patients with unilateral compartment osteoarthritis of the knee who received UKA between November 2013 and May 2017 and met the inclusion criteria were enrolled as the research objects. Among them, 40 patients (50 knees) were more than 85 years old (super-age group) and 44 patients (50 knees) were 52-81 years old (control group). There was significant difference in age between the two groups (t=17.33, P=0.00). There was no significant difference in body mass index, degenerative classification of medial and lateral compartments, varus deformity of knee, disease duration, complicating diseases, and preoperative hemoglobin, hematocrit (HCT), American Hospital for Special Surgery (HSS) score, range of motion (ROM) of knee, visual analogue scale (VAS) score, and femoral-tibial angle (FTA) between the two groups (P>0.05). Hospital stay, hemoglobin, and HCT of the two groups were recorded before operation and on the first day after operation. The changes of hemoglobin and HCT after operation were calculated. During follow-up period, the ROM of the knee, HSS score, and VAS score were measured; the position of the prosthesis and FTA were observed by X-ray films.ResultsThere was no significant difference in hospital stay between the two groups (t=1.05, P=0.29). Hemoglobin and HCT of the two groups on the first day after operation were significantly lower than those before operation (P<0.05). There was no significant difference in the postoperative changes of hemoglobin and HCT between the two groups (P>0.05). All the patients were followed up completely except 4 cases (5 knees) in the super-age group. The follow-up time ranged from 14 to 44 months of super-age group (mean, 29 months) and 21 to 33 months of control group (mean, 24 months). There were significant differences in HSS score, VAS score, ROM of the knee, and FTA between pre-operation and last follow-up in the two groups (P<0.05). There was significant difference in HSS score between the two groups (P<0.05), and no significant difference was found in ROM, VAS score, and FTA between the two groups (P>0.05). X-ray film showed no adverse position of the prosthesis, infection around the prosthesis, prosthesis loosening, or pathological bright lines.ConclusionUKA combined with reasonable perioperative management in the treatment of super-age patients over 85 years with knee osteoarthritis is safe and feasible, and can obtain satisfactory short-term effectiveness.