Preliminary clinical results of robotic-assisted unicompartmental knee arthroplasty

Abstract

Objective To investigate the accuracy of robotic-assisted UKA and its safety and short term functional outcomes. Methods The clinical data of 20 patients who received robotic-assisted UKA in Shanghai 6th People's Hospital and Chinese PLA General Hospital from September 2016 to December 2016 were retrospectively reviewed, with 10 patients in each hospital. All patients had a preoperative diagnosis of osteoarthritis. Five patients received simultaneous bilateral UKA. Of all the 20 patients, there were 3 male patients and 17 female patients, with an average age of 65 years old (range from 51 to 79 years old) and an average BMI of (26.9±3.4) kg/m2. All the procedures were performed with MAKO RIO robotic-assisted surgical system and RESTORIS MCK unicompartmental knee prosthesis (STRYKER MAKO Surgical, USA). Each patient's operation time, blood loss and post-operative pain scores were recorded. Pre-operative and post-operative knee society scores were recorded; lower limb alignment and the position of the tibial component in coronal plane were measured. Results For patients who received unilateral procedure, the mean operating time of tourniquet was (27±10) minutes. The average total blood loss on post-op day 2 was (476±290) mL, and no transfusion was needed for any patient. The mean visual analogue scale pain score at 8, 16 and 24 hours after surgery was 3.2±1.2, 1.8±0.8 and 1.1±0.3, respectively. All 20 patients (25 knees) were followed-up at a minimal time of 8 weeks (average 14.1 weeks, range from 8 to 20 weeks). On latest follow-up visit, the mean Knee Society Score was improved from a pre-operative value of 57±13 to 90±6, the mean function score was improved from a preoperative value of 48±18 to 79±12, both changes were statistically significant (t=14.941 and 10.014 respectively, all P values 0.05). No severe complications, such as surgical site infection, deep venous thrombosis or vascular and nerve injury, were observed during the follow-up period. Conclusions Robotic-assisted UKA can provide us with excellent precision and safety through a minimally invasive approach. Further long-term controlled study is required to identify the long term clinical outcomes and the role of robotic technique on the improvement of post-operative knee function warrant. Key words: Osteoarthritis, knee; Arthroplasty, replacement, knee; unicompartmental knee arthroplasty; Robotic surgical procedure