Knee Arthroplasty Surgery: Short-Term Effect of the ROSA Surgical Robot
Phase: NA
Conditions: Knee Osteoarthritis (Knee OA), Total Knee Arthroplasty
Sponsor: Hospital Universitario Santa Cristina

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Patient Information Sheet and Informed Consent 
 
Official Title of the Study: 
Knee Arthroplasty Surgery: Short-Term Effects of Robotic Assistance (ROSA). 
Randomized Study. 
 
Version: 3.0. 
 
Date: March 20th, 2022 
 
Principal Investigator: Inmaculada Neira, M.D. 
 
Site: Hospital Universitario Santa Cristina.  Madrid, Spain. 
 
 

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Introduction 
Total knee arthroplasty (TKA) is a common orthopedic surgical procedure. The survival 
rate of total knee prostheses is approximately 95% at 10 years and 90% at 15 years. 
Overall patient satisfaction is estimated at around 80%. 
TKA failure is multifactorial, involving patient-related factors, implant design factors, 
and surgical technique. While patient-related risk factors and infection prevention 
protocols help reduce complications, current implant materials and designs are not a 
major cause of failure. Recent clinical series show that instability and malalignment are 
among the leading causes of early failure, which are primarily surgeon-dependent. 
Inadequate implant positioning, improper bone resection, or excessive or insufficient 
soft tissue release can be mitigated by improvements in surgical technique. 
The goal of robotic assistance is to eliminate surgical inaccuracies and help execute 
the preoperative plan with precision. The robot positions and holds the cutting guide in 
place, assists with distal femoral cuts, determines prosthetic component sizes, and 
facilitates alignment and soft tissue balancing. The surgeon remains in full control of 
the saw and performs all bone cuts. 
Robotic systems also enable intraoperative assessment of soft tissues, allowing the 
surgeon to implant the prosthesis in an anatomically adapted position, optimizing 
alignment and function. This increased precision may enhance early postoperative 
functional recovery compared to conventional TKA. 
The ROSA surgical robot has been approved and commercially available since 2019. 
At Hospital Universitario Santa Cristina, the ROSA system has been used for TKA 
procedures since January 2021. 
Objectives 
Primary Objective: 
To compare early functional recovery in patients undergoing TKA with robotic 
assistance versus conventional manual technique over the first three months after 
surgery. 
Secondary Objectives: 
• 
To analyze length of hospital stay, laboratory parameters, joint range of motion 
(ROM), and pain in both groups. 

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• 
To evaluate mechanical recovery following robotic and manual TKA. 
• 
To compare postoperative long-leg standing radiographs in both groups. 
Materials and Methods 
Study Design: 
Prospective, randomized, controlled study involving two groups of patients undergoing 
TKA, all operated on by the same experienced surgeon skilled in both conventional 
and robotic-assisted techniques. 
Patients will be selected from those on the hospital surgical waiting list who meet 
inclusion criteria. Selection is blind and conducted by the hospital’s administrative 
service, independent of the principal investigator. Randomization will follow a parallel 
1:1 model, using dice rolls. 
Each group will include a minimum of 30 patients, enabling the use of parametric tests 
supported by the Central Limit Theorem. 
Inclusion Criteria 
• 
Patients with primary osteoarthritis indicated for TKA who provide informed 
consent. 
• 
All patients will receive the same prosthesis model: Persona® (Zimmer Biomet), 
a posterior-stabilized primary knee prosthesis with patellar resurfacing, 
approved through public procurement. 
Exclusion Criteria 
• 
Previous surgery on the affected knee. 
• 
Presence of other prostheses in the same limb. 
• 
Hip pathology on the same side (e.g., dysplasia, avascular necrosis, 
arthrodesis, flexion contractures) that limits bone mass or mobility. 
• 
Active infections near the affected knee joint. 
• 
Obesity (BMI > 30). 
• 
Dependent patients. 
• 
Residents of long-term care facilities. 
• 
Anatomical abnormalities, ligament instability, or severe femoral-tibial 
misalignment requiring alternative prosthesis models. 
Surgical Protocol and Randomization 

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All patients will receive the same implant model: Persona® (Zimmer Biomet, Warsaw, 
Indiana, USA). Robotic-assisted surgeries will be performed with the ROSA® system 
(Zimmer Biomet, Warsaw, Indiana, USA). 
After preoperative assessment, patients will be added to the surgical schedule. 
Scheduling occurs 15 days in advance and is managed by the department head. Once 
scheduled, randomization is performed using dice rolls: 
• 
Even number: Robotic TKA (Group 1) 
• 
Odd number: Manual TKA (Group 2) 
Follow-up Schedule 
All TKA patients at Hospital Universitario Santa Cristina are followed up weekly in 
outpatient clinics. First follow-up occurs at 2–3 weeks post-op; subsequent visits are at 
2, 3, 6, 9, and 12 months. Annual visits continue for 5 years, then every two years until 
10 years. 
In this study, patients follow the same clinical follow-up schedule, although the study 
itself concludes at 3 months. 
Variables 
Demographic  
Age, sex, and comorbidities (diabetes mellitus, hypertension, rheumatoid arthritis, 
ischemic heart disease, anticoagulation). 
Laboratory Parameters 
Hemoglobin, hematocrit, ESR, CRP, and D-dimer levels will be recorded 
preoperatively, on the day of surgery (before and after the procedure), and at hospital 
discharge. Drain output (mL) during the first 24 hours post-op will also be recorded. 
Surgical Parameters 
Surgery duration (minutes), intraoperative complications (fracture, ligament or vascular 
injury), surgeon-performed bone cut corrections, and the difference (mm) between 
planned and robot-measured resections. 
Pain 
Assessed daily using a visual analog scale (VAS) during clinical rounds and recorded 
in the hospital's electronic medical record (HP-HCIS). 

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Length of Hospital Stay 
Number of days from hospital admission for surgery to discharge, obtained from HP-
HCIS. 
Functional Recovery 
Assessed using KOOS and SF-36 questionnaires preoperatively and at 2 and 3 
months after surgery. 
Joint Range of Motion 
Measured daily with a goniometer and recorded in degrees of flexion and extension in 
the HP-HCIS. 
Mechanical Recovery 
Evaluated via surface electromyography (EMG) performed before surgery and at 3 
months post-op using the Myomed 932 EMG device. Electrodes are placed over target 
muscle bellies, and both isometric (5-second contractions and rest, 1 minute) and 
isotonic (5 quick contractions and 5-second rest, 1 minute) protocols are performed. 
Peak and mean muscle strength are recorded. 
Radiology 
Preoperative AP/lateral X-rays and long-leg standing radiographs will be performed. 
Radiologic evaluation includes mechanical and anatomical axis, tibial slope, and 
osteoarthritis grade (Kellgren-Lawrence). Postoperative AP/lateral X-rays will be taken 
immediately post-op, at discharge, and at 2 and 3 months. 
Data Management and Statistical Analysis 
Data will be recorded in a coded database without personal identifiers. A separate 
confidential file linking study codes to patient identities (name, clinical ID, and national 
ID) will be kept by the principal investigator. 
Patient outcomes will be analyzed over the 3-month period, comparing the evolution of 
each variable between groups. Descriptive statistics will be used, and group 
comparisons will be performed using Chi-square tests for binary variables. The 
CONSORT 2010 guidelines were followed in the preparation of the Methods section. 
Ethical Considerations 

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All potential participants will be informed about the study during the preoperative 
consultation. An information sheet will be provided, and informed consent will be 
obtained prior to enrollment.