Mako Functionally Aligned Total Knee Arthroplasty vs Mako Mechanically Aligned Total Knee Arthroplasty

A Prospective Randomised Control Trial Comparing Mako Robotic-arm Assisted Functionally Aligned Total Knee Arthroplasty Versus Mako Robotic-arm Assisted Mechanically Aligned Total Knee Arthroplasty

This study evaluates outcomes of robotic-arm assisted mechanically aligned total knee arthroplasty [MA TKA] versus robotic-arm assisted functionally aligned total knee arthroplasty [FA TKA]. Half the study will receive MA TKA and half will receive FA TKA.

Study Overview

• Status: Completed
• Conditions: Osteoarthritis; Osteo Arthritis Knee; Surgery
• Intervention / Treatment: Device: Total knee arthroplasy

Detailed Description

Total knee arthroplasty [TKA] is an estabilshed treatment for symptomatic end-stage knee osteoarthritis, but there is a higher disatisfaction rate when compared to total hip arthroplasty. The exact aetiology of this is not clear but recent studies have shown one possible reason to be conventional TKA with mechanical alignment [MA] may force the knee into an unnatural position. This may lead to altered knee anatomy and kinematics that may compromise patient satisfaction.

Total knee arthroplasty using functional alignment [FA] aims to restore the patient's prearthritic knee anatomy and native joint kinematics. Early clinical and functional outcome studies have reported promising outcomes in TKA with FA but results of longer term studies have not yet been published.

There are very few prospective studies exploring clinical and radiological outcomes in MA versus FA for TKA. It is possible to improve on previous studies by recording a more comprehensive range of clinical and functional outcome measures, blinding patients and observers recording outcomes of interest, and using longer follow-up times.

Robotic-arm assistance can be used to improve the accuracy of implant positioning. Clinical and functional outcomes should also be correlated to longer-term outcomes to better establish the "safe zone" for functional alignment. The findings of this study will enable an improved understanding of the clinical and functional benefits of FA compared to MA. These outcomes will improve our understanding of the optimal TKA alignment with possible improved outcomes; improved cost-effectiveness by reduced revisions and better patient satisfaction and function; and improved long-term implant survival.

100 patients will be enrolled in a 1:1 ratio between the two treatment groups. Trial patient will be allocated to either the MA TKA ['Control group'] or to the FA TKA ['Investigation group']. Outcomes will be recorded at specific milestones.

• Study Type: Interventional
• Enrollment (Actual): 100
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom, NW1 2PG
    • University College London Hospital NHS Foundation Trust

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patient has symptomatic knee osteoarthritis requiring primary TKA
• Patient and surgeon are in agreement that TKA is the most appropriate treatment
• Patient is fit for surgical intervention following review by surgeon and anaesthetist
• Patient is between 18-80 years of age at time of surgery
• Gender: male and female
• Patient must be capable of giving informed consent and agree to comply with the postoperative review program
• Patient must be a permanent resident in an area accessible to the study site
• Patient must have sufficient postoperative mobility to attend follow-up clinics and allow for radiographs to be taken

Exclusion Criteria:

• Patient is not suitable for routine primary TKA e.g. patient has ligament deficiency that requires a constrained prosthesis
• Patient has bone loss that requires augmentation
• Patient is not medically fit for surgical intervention
• Patient requires revision surgery following previously failed correctional osteotomy or ipsilateral TKA
• Patient is immobile or has another neurological condition affecting musculoskeletal function
• Patient is less than 18 years of age or greater than 80 years of age
• Patient is already enrolled on another concurrent clinical trial
• Patient is unable or unwilling to sign the informed consent form specific to this study
• Patient is unable to attend the follow-up programme
• Patient is non-resident in local area or expected to leave the catchment area postoperatively

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Mechanically aligned; Neutral limb alignment irrespective of the patient's native knee anatomy and joint mechanics	Device: Total knee arthroplasy; Surgical implantation of prosthetic knee using robotic-arm assist
Experimental: Functionally aligned; Restore the patient's own pre-arthritic knee anatomy	Device: Total knee arthroplasy; Surgical implantation of prosthetic knee using robotic-arm assist

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Western Ontario and Mcmaster Universities Arthritis Index (WOMAC)	Patient recorded outcome questionnaire evaluating pain, stiffness and disability in affected joint	2 years post-intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
European Quality of Life questionnaire with 5 dimensions for adults (EQ-5D)	Patient recorded outcome measure with 5 domains; score -1 to 1, with 1 being best score	Pre-op; 6 weeks post-op; 6 months post-op; 1 year post-op; 2 years post-op
Lower limb alignment	Assessed using Computerised Tomography (CT) scanogram. Measurements of the hip-knee-angle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), femoral flexion angle, and posterior tibial slope will be recorded preoperatively and postoperatively	pre op and 6 weeks post op
Operating time	Operating time [minutes]	interoperative
Time to discharge	Time to discharge from admission until documented discharge from hospital (hours)	Documented when participant leaves hospital, an average of 72 -96 hours
Forgotten Joint Score (FJS)	Patient recorded outcome measure via questionnaire. Score cumulative with -100 being best score and 0 being worst score	Pre-op; 6 weeks post-op; 6 months post-op; 1 year post-op; 2 years post-op
Oxford Knee Score (OKS)	Patient recorded outcome measure via questionnaire. 48 is best score and 0 worst score	Pre-op; 6 weeks post-op; 6 months post-op; 1 year post-op; 2 years post-op
Short form health survey of 12 items (SF-12),	Patient recorded outcome measure. Questions concerning attitudes to physical and mental heath with 12 questions combined to give overall norm-based values; higher score better, lower score worse.	Pre-op; 6 weeks post-op; 6 months post-op; 1 year post-op; 2 years post-op
Knee injury and osteoarthritis outcome score (KOOS)	Patient recorded outcome measure via questionnaire. 6 separate domains including pain, stiffness, quality of life, symptoms, and function; each domain creates percentage with overall cumulative percentage achieved; best score 100%	Pre-op; 6 weeks post-op; 6 months post-op; 1 year post-op; 2 years post-op
University of California at Los Angeles knee (UCLA)	Patient recorded outcome measure via questionnaire. Patient records current level of activity; 10 best possible score, 0 worst possible score	Pre-op; 6 weeks post-op; 6 months post-op; 1 year post-op; 2 years post-op
Use of mobility aids	description of any mobility aids used to assist with ambulation; can describe wheelchair, walker, crutches, sticks or no need for any mobility aid	during inpatient admission and postoperatively at 6- weeks, 6 months, 1 year and 2 years
Mobilisation distance	Mobilisation distance (metres)	during inpatient admission and postoperatively at 6- weeks, 6 months, 1 year and 2 years
Range of movement	Range of movement (degrees) in knee joint	inpatient admission and postoperatively at 6 weeks, 6 months, 1 year and 2 years
radiosteriometric analysis (RSA)	Femoral and tibial implant early migration as assessed using RSA	postoperatively at 2 weeks, 6 weeks, 6 months, 1 year, and 2 years
Gait analysis	Walking on an instrumented treadmill with force plates	performed postoperatively at 6 months and 1 year postoperatively
Complications	Complications relating to surgery	during inpatient admission and postoperatively at 6- weeks, 6 months, 1 year and 2 years

Collaborators and Investigators

• Sponsor: University College, London
• Collaborators: Stryker Orthopaedics
• Investigators: Study Chair: Fares S Haddad, UCLH

Publications and helpful links

General Publications

• Kayani B, Konan S, Tahmassebi J, Oussedik S, Moriarty PD, Haddad FS. A prospective double-blinded randomised control trial comparing robotic arm-assisted functionally aligned total knee arthroplasty versus robotic arm-assisted mechanically aligned total knee arthroplasty. Trials. 2020 Feb 18;21(1):194. doi: 10.1186/s13063-020-4123-8.

Study record dates

Study Major Dates

• Study Start (Actual): December 28, 2018
• Primary Completion (Actual): February 6, 2025
• Study Completion (Actual): February 6, 2025

Study Registration Dates

• First Submitted: September 13, 2019
• First Submitted That Met QC Criteria: September 16, 2019
• First Posted (Actual): September 17, 2019

Study Record Updates

• Last Update Posted (Actual): July 9, 2025
• Last Update Submitted That Met QC Criteria: July 7, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: total knee replacement; total knee arthroplasty; robotic surgery; patient outcomes; mako robot; makoplasty; kinematic alignment; functional alignment
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Knee
• Other Study ID Numbers: 17/0721

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: No plan

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes