Early Clinical Benefits of Robot-Assisted vs Manual Total Knee Arthroplasty (RATKA-EARLY)

NCT ID: NCT07078149

Last Updated: 2025-07-22

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 68 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2022-03-28
• Study Completion Date: 2024-12-16

Brief Summary

This study, called the RATKA-EARLY trial, was designed to compare two surgical techniques used in total knee replacement (also known as total knee arthroplasty or TKA). The aim was to determine whether the use of a robotic surgical system (ROSA® Knee System) offers short-term clinical advantages over the traditional manual technique.

A total of 68 adult patients with advanced knee osteoarthritis scheduled for TKA were enrolled. Participants were randomly assigned to one of two groups: 34 patients underwent robot-assisted TKA (RATKA), and 34 underwent conventional manual TKA (mTKA). All surgeries were performed by the same experienced surgical team, using the same type of implant.

Researchers assessed intraoperative and perioperative variables (such as surgical duration and blood loss), and evaluated early clinical outcomes at 3 months postoperatively by comparing pain levels, implant alignment, knee function, mobility, and overall patient satisfaction with baseline values.

The study was conducted at Hospital Universitario Santa Cristina in Madrid, Spain. It was approved by the local ethics committee and carried out in accordance with the Declaration of Helsinki and international research guidelines.

By comparing these two surgical approaches, the study aims to help patients and healthcare professionals make informed decisions regarding total knee replacement options.

Detailed Description

This was a prospective, randomized, controlled clinical trial including patients with knee osteoarthritis requiring total knee arthroplasty (TKA). Patients were randomized in a 1:1 ratio using a single-blind, parallel-group design based on a dice roll: even numbers assigned patients to the robot-assisted TKA (RATKA) group, and odd numbers assigned them to the conventional manual TKA (mTKA) group.

Inclusion criteria comprised symptomatic knee osteoarthritis with surgical indication for TKA and a correctable varus or valgus deformity of less than 18 degrees. Exclusion criteria included prior surgery on the index knee; prior arthroplasty in the same limb; neurological disorders affecting knee function; tumor involvement; ipsilateral hip pathology limiting range of motion (ROM); active periarticular infection; body mass index (BMI) > 35; dependency or institutionalization (e.g., nursing home residents); and severe anatomical deformity, instability, or malalignment requiring alternative surgical strategies.

Surgical procedures (RATKA using the ROSA® Knee System and mTKA) were performed as previously described in the literature. All surgeries were carried out by the same senior surgeon, who had previously completed the ROSA learning curve. A medial parapatellar approach and standard surgical exposure were used in all cases. The same posterior-stabilized implant design (Persona® PS; Zimmer Biomet, Warsaw, IN, USA) was implanted with patellar resurfacing and cement fixation (PALACOS® R+G, Heraeus). A tourniquet was placed but not inflated; no limb ischemia was induced. Tranexamic acid was administered intravenously unless contraindicated. Preoperative planning was based on full-length standing radiographs of the lower limbs (Tele-rx), and full-scale anteroposterior and lateral knee radiographs (AP/L-rx). Femoral and tibial osteotomies were calculated from mechanical axis measurements, and implant sizes were selected using AP/L-rx data. In the RATKA group, intraoperative registration was performed manually after arthrotomy, without the use of preoperative 3D imaging, in compliance with the Spanish Data Protection Act (Organic Law 3/2018). The ROSA® Knee System (software version 1.2; Zimmer Biomet) was used according to manufacturer guidelines.

The following data were collected. Baseline: demographic and clinical data (comorbidities, BMI, osteoarthritis severity using the Kellgren-Lawrence classification); hemoglobin and hematocrit values; radiographic studies (Tele-rx of the limb and AP/L knee views); and patient-reported outcome measures (PROMs) using the Visual Analog Scale (VAS) for pain, the Knee injury and Osteoarthritis Outcome Score (KOOS), and the 36-Item Short Form Health Survey (SF-36). Intraoperatively: operative time and intraoperative complications. Postoperative Day 3: hemoglobin and hematocrit values; radiographic studies (Tele-rx and AP/L views); functional recovery measured by range of motion (flexion and extension in degrees) using a goniometer; and mechanical limb alignment assessed on digital Tele-rx. Three months postoperatively: PROMs (VAS, KOOS, and SF-36); range of motion; radiographic studies (Tele-rx and AP/L views); and mechanical limb alignment measured again on digital Tele-rx.

Descriptive statistics were reported as frequencies for categorical variables and as means with standard deviations (SD) for continuous variables. Between-group comparisons were conducted using Student's t-tests or Mann-Whitney U tests for continuous variables, and chi-square or Fisher's exact tests for categorical variables. Pre- and postoperative clinical and radiographic outcomes were compared using paired t-tests or Wilcoxon signed-rank tests within groups, and unpaired t-tests or Mann-Whitney U tests between groups. Univariable and multivariable linear regression models were used to analyze VAS, KOOS, and SF-36 outcomes at 3 months. Multivariable models were adjusted for sex, age, BMI, and discharge values. All statistical analyses were performed using STATA 15 (StataCorp, College Station, TX, USA), with p-values < 0.05 considered statistically significant.

The study was approved by the Institutional Review Board of Hospital Universitario de La Princesa (Registry No. 4748; approval date: March 24, 2022). All procedures complied with the Declaration of Helsinki (2013 revision) and applicable Spanish regulations. Written informed consent was obtained from all participants.

Conditions

Knee Osteoarthritis (Knee OA); Total Knee Arthroplasty

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: SINGLE

Study Groups

Manual TKA (mTKA)

mTKA was performed using the conventional manual surgical technique, without robotic or navigation assistance. All bone cuts and implant positioning were carried out manually by the surgeon, based on preoperative planning and intraoperative anatomical landmarks. This approach represents the standard total knee arthroplasty technique widely used in routine clinical practice.

Group Type: ACTIVE_COMPARATOR

Conventional manual TKA (mTKA)

Intervention Type: PROCEDURE

mTKA was performed without robot assistance.

Robot-assisted TKA (RATKA)

RATKA was performed using the ROSA® Knee System, a robotic-assisted surgical platform approved for total knee arthroplasty. The procedure was carried out by the surgeon with continuous manual control, while the robotic system provided intraoperative assistance to enhance the precision and reproducibility of bone resections and implant positioning.

Group Type: EXPERIMENTAL

Robotic-assisted TKA (RATKA).

Intervention Type: DEVICE

RATKA was performed using the ROSA® Knee System.

Interventions

Robotic-assisted TKA (RATKA).

RATKA was performed using the ROSA® Knee System.

Intervention Type: DEVICE

Conventional manual TKA (mTKA)

mTKA was performed without robot assistance.

Intervention Type: PROCEDURE

Other Intervention Names

ROSA® Knee System

Eligibility Criteria

Inclusion Criteria

• Symptomatic knee osteoarthritis with surgical indication for total knee arthroplasty (TKA)
• Correctable varus or valgus deformity of less than 18 degrees

Exclusion Criteria

• Prior surgery on the index knee
• Prior arthroplasty in the same limb
• Neurological disorders affecting knee function
• Tumor involvement of the knee
• Ipsilateral hip pathology limiting range of motion (ROM)
• Active periarticular infection
• Body mass index (BMI) > 35
• Dependency or institutionalization (e.g., nursing home residents)
• Severe anatomical deformity, instability, or malalignment requiring alternative surgical strategies

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Hospital Universitario Santa Cristina

OTHER

Sponsor Role: lead

Responsible Party

Inmaculada Neira

Orthopaedic surgeon

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Inmaculada Neira, M.D.

Role: PRINCIPAL_INVESTIGATOR

Hospital Universitario Santa Cristina

Locations

Hospital Universitario Santa Cristina

Madrid, , Spain

Countries

Spain

Provided Documents

Document Type: Study Protocol and Statistical Analysis Plan

View Document

Document Type: Informed Consent Form

View Document

Other Identifiers

SantaCristinaH

Identifier Type: -

Identifier Source: org_study_id