Due to ongoing issues with recruitment, it was decided it was best to terminate the study and focus resources on other priorities.

This study aims to compare clinical and functional outcomes of a cohort of patients that have undergone a medial congruent TKR to a similar cohort of patients that have undergone a conventional TKR and a cohort of control participants. Our null hypothesis is that there will be no difference in the functional outcome (as assessed by gait analysis) between Attune and Persona MC TKR.

This cross sectional, post-operative comparator gait study aims to compare the functional and patient reported outcomes of patients that have undergone a MC TKR to an age, gender, BMI, pre-operative diagnosis with satisfactory clinical outcome at one year (OKS > 34) matched cohort of patients undergone a modern generation TKR which utilises a gradually reducing radius of curvature on the femoral component with conventional polyethylene (Attune) to a TKR with gradually reducing radius of curvature on the femoral component but a medial congruent (MC) TKR design (Persona).

Inclusion Criteria:

1. Aged 18 years and above*

2. Have undergone primary total knee replacement for either:

   1. Osteoarthritis
   2. avascular necrosis of the femur or tibia

3. Report an Oxford Knee Score greater than 34, obtained from usual clinical practice. OKS above 34 represents (range 0-48, high representing good outcome) a good outcome post-surgery.

4. Independent of study participation, patients received either commercially available Zimmer Biomet Persona MC bearing or DePuy Synthes Attune knee implants implanted in accordance with product labelling

5. 1-5 years post TKR surgery

6. An adequate understanding of written and verbal information in English in order to provide informed consent and answer the study questionnaires* * Control participants will meet same inclusion criteria except no primary TKR and OKS will not be required

Exclusion Criteria:

1. History of infection in the replaced joint and/or other local/systemic infection that may affect the prosthetic joint

2. Skeletal immaturity

3. Neuropathic arthropathy

4. Osteoporosis/any loss of musculature or neuromuscular disease that compromises the affected limb

5. Severe instability secondary to the absence of collateral ligament integrity

6. Pregnancy - routine clinical practice ensures that all female patients are asked whether they are pregnant and can safely receive x-rays or surgery as per standard consent forms

7. Patient is a member of a protected population (e.g., prisoner, mentally incompetent, etc.)

8. Patient has previously received partial or total knee arthroplasty for the ipsilateral knee

9. Patients who are unable to give voluntary informed consent.

10. Patients who are unable to walk unaided (post-surgery).

11. BMI > 40

    ** Control participants will meet the same exclusion criteria as TKR patients

12. Patients who suffer with cognitive impairment such as Parkinson's or Alzheimer's disease resulting in impaired mental capacity.

13. Patients who are unable to walk unaided.

14. Patients who suffer from dizzy spells or fainting episodes.

Potential patients that have undergone either a medial congruent Persona TKR or Attune TKR will be identified by the relevant orthopaedic surgeon. Control participants will be identified from an established database.

Non-identifiable data from those patients that have undergone the MC TKR surgery will be transferred to the research funder, who will combine this with data from another trial (POLAR) for analysis.

Data will be available at the end of the study and will be available for three years

Patient identifiable information will not be shared with the funder. Other relevant information will be shared after completing the study and analysing the data