The effects of two-team and single-team simultaneous bilateral total knee arthroplasty (SBA) on peri- and postoperative complications are not clear. The investigators hypothesized that two-team SBA has lower early postoperative complication rates than single-surgeon SBA. Therefore, this prospective study compared minor and major complications for 90 days postoperatively between two-surgeon and single-surgeon SBA.

Study Design:

This prospective randomized study was approved by our institution's Clinical Research Ethics Committee (08.11.2017-71306642-050.01.04). The protocol conforms to CONSORT guidelines for parallel-group randomized trials and the protocol is designed to conform to the principles of the Declaration of Helsinki.

Participant :

The investigators will enroll 246 patients with primary bilateral symptomatic knee osteoarthritis that was refractory to conservative treatment who underwent bilateral TKA (total knee arthroplasty) under single anaesthesia between 2017 and 2018. An informed consent form will be obtained from all patients.

The schedule for randomization was randomly generated using a computer before the initiation of the trial. Patients were randomly assigned in a 1:1 ratio. A blind medical staff member will organize the days of the surgeries of randomized patients for the two-surgeon (TS) or single-surgeon (SS) groups. Neither patients nor assessors will know about randomization results. The outcome assessor will be blinded to group allocation and will no involve in providing the interventions. The statistician performing the statistical analyses will be blinded to group allocation.

Surgical procedures:

All surgeries will be performed by two high-volume surgeons under regional or general anaesthesia. Both surgeons always will operate on the same side. Each of patients will receive a total knee prostheses-Vanguard (Zimmer Biomet,Inc, Warsaw, IN) - using a standard medial parapatellar approach without the use of a tourniquet. All patients will be given 2 g cefazolin for infection prophylaxis and 1 g tranexamic acid for blood loss prophylaxis intravenously 30 min before the incision. In the TS group, the two surgeons will start the incisions at the same time using two different instrumentation sets and with their own scrub nurses. In the SS group, the surgeon will operate on both knees consecutively. No Hemovac drains will be used in either group. After closing the joint capsule, 1 g tranexamic acid will be injected into the joint in both groups.

All patients will start a standard physiotherapy program with the same blinded therapist. All patients will be started walking on the first postoperative day, using two crutches or a walker. Antibiotic prophylaxis will be continued for 24 h with 1 g intravenous cefazolin every 6 h. Venous thromboembolism prophylaxis will be administered using low-molecular-weight heparin for 4 weeks postoperatively. The investigators will check the estimated blood loss (EBL) on the first postoperative day. All patients will be asked to visit our outpatient clinic at 2 and 6 weeks and 3 months postoperatively. For functional outcomes and pain will be used the Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and a visual analog scale (VAS) preoperatively and 90 days postoperatively.

Primary Outcome:

The prespecified primary outcome was the between-group difference according to the rate of major complications.The investigators will assess major complications in all patients until 90 days postoperatively.

Secondary Outcomes:

The investigators also will assess the estimated blood loss (EBL), minor complications, operation time and functional results among the groups. The EBL will be calculated using the Gross formula and compared between the groups.

Statistical methods:

Categorical variables will be analyzed using the chi-square test and continuous variables will be tested using the Mann-Whitney U-test. The statistical analyses will be performed using IBM SPSS Statistics for Windows, ver. 22.0. (IBM, Armonk, NY). Significance was set at α < 0.05.

Inclusion Criteria:

• Primary bilateral knee osteoarthritis with refractory to conservative treatment
• Patients who accept participation in the research and the randomization

Exclusion Criteria:

• no history of malignancy
• less than 75 years old
• without severe extra-articular deformities
• severe cardiac insufficiency and morbid obesity
• without systemic inflammatory diseases