The intention is to explore whether there are factors, which can help us to understand why some patient outcomes, following total knee arthroplasty are not successful and identify prediction factors for progression. Assessment of outcomes pre- and post-surgery with objective tools is a way to explore prediction tools for good/poor progression and improve patient selection and timing for surgery.

The first aim of this project is determine the psychometric properties of the Arabic Version of Oxford Knee Score, including internal consistency, reliability and validity before and post-total knee arthroplasty in both males and females in a Middle East population. The second aim is to assess the reliability of the Star Excursion Balance Test for measuring the dynamic balance. The final aim is explore outcomes post-total knee arthroplasty among Middle East patients using the Arabic Version of Oxford Knee Score, physical activity measures and performance-based measurements such as: 30 s chair-stand test, stair-climb test, timed up-and-go test and a 6 m walk test while adhering to Osteoarthritis Research Society International recommendations.

Project objectives

To gain an understanding of recovery post-TKA in a Saudi population and explore whether there are factors which can help us to understand why some patient outcomes are not successful and identify prediction factors for progression. It is a prospective study measuring outcomes six months post-TKA with the following objectives:

• Examine the internal consistency, reliability and validity of the Arabic Version of Oxford Knee Score before and after total knee arthroplasty in both male and female Middle East patients.
• Examine the test- re-test reliability of the Star Excursion Balance Test in both male and female Middle Eastern patients.
• Measure patient outcomes post-total knee arthroplasty using patient self-reporting activity measurements and the Arabic Version of Oxford Knee Score;
• Evaluate physical activity level improvements post-knee arthroplasty using objective methods and an accelerometer: ActivPAL;
• Assess functional recovery post-knee arthroplasty according to Osteoarthritis Research Society International recommendations using performance-based measurements, such as: 30 s chair-stand test, stair-climb test, timed up-and-go test and a 6 m walk test alongside functional balance.

The rationale which led to this project;

Knee osteoarthritis (OA) is a major cause of disability around the world; it is the most common chronic condition in primary care in the UK. By 2030 it is predicted to be the greatest cause of disability in the general population . An effective end-stage treatment for knee OA is knee-replacement surgery, which was first done in the 1970s and 1980s.

In England and Wales, the number of knee-replacement procedures recorded by the National Joint Registry in 2013 was 91,703, which represents an increase of 0.9 % over 2012. The data analysis by the National Joint Registry and the Office of National Statistics suggests that, by 2030, primary TKAs will increase by 117% from the 2012 level. Subsequently, TKA revision surgeries are expected to increase incrementally by 332%. There is a similar estimation of demand for revision TKA surgeries in the United States; by 2030, they are expected to rise by 601% from the 2005 level. The United States estimation of primary TKA is for growth of 673% from the 2005 level, which is similar to England and Wales's upper-limit projections.

Post-TKA, 75-85% of patients report satisfaction with surgery outcomes, while the remaining 15-25% are dissatisfied (Klit, Jacobsen, Rosenlund, Sonne-Holm, & Troelsen, 2014). Total knee arthroplasty's success has traditionally been evaluated from the surgeon's perspective, e.g. the presence of surgical complications or implant survival. This is gradually changing to involve the patient in measuring health outcomes and decision-making processes. Patient-reported outcome measures (PROMs) have evolved to explore patient perspectives by monitoring the quality of care in health organizations and conducting clinical trial outcomes.

PROM results cannot exclude the Research Participant Effect (RPE) or subjective over/underestimation due to psychosocial effects or pain from other joints, such as hips or back. Hence, objective clinical evaluation methods can minimize patients' subjective over/underestimations of outcomes, though RPE can not be excluded. Objective assessment has some advantages over PROMs, such as a lack of ceiling effects and more precision and responsiveness, and it does not require cultural and language adaptation. Performance-based Outcome Measures (PBOMs) have the advantage of being objective measures that do not overlap with pain measurement. They are sensitive to detecting change, responsive, have a minimal ceiling effect and are feasible.

PROMs and PBOM measurement tools assess different aspects of function post-TKA. PROMs mainly assess patients' functional ability beliefs and experiences, while objective functional assessment instruments and PBOM measurement tools evaluate patients' actual ability and function. Therefore, to conduct comprehensive functional assessments post-TKA, PROMs, objective functional assessment instruments and PBM measurement tools are recommended.

To the best of our knowledge, no study has explored the outcome post TKA using the PROMs, PBOMs and functional balance measurement tools in Saudi male and female population or explored possible accurate prediction factors for outcomes post-TKA. Reliable outcome prediction could, however, improve patient selection for surgery, as appropriate timing for surgery depends on patient symptoms and efficient patient preparation for surgery if it is to be cost-effective. Accurate preoperative prediction is crucial to minimize the potential for unrealistic expectations about outcomes.

This study will investigate outcomes post-total knee arthroplasty and factors that may predict good/poor progression using three categories of outcome measurements in order to minimize subjective over/ underestimation of surgical outcomes. Thus, the study seeks to explore accurate and objective prediction factors of post-total knee arthroplasty progression.

Potentially, reliable outcome predictions could improve patient selection for surgery, as appropriate timing for surgery depends on patients' symptoms and efficient patient preparation for surgery, if it is to be cost-effective. Accurate preoperative prediction is crucial to minimize the potential for unrealistic expectations about outcomes.

Inclusion Criteria:

All patients will be asked to participate during preadmission orthopedics clinic visits to King Khalid University Hospital in Riyadh if the patient;

• Scheduled for elective primary unilateral total knee arthroplasty.
• For end-stage knee osteoarthritis.
• In a stable and controlled medical condition,

Exclusion Criteria:

• Are scheduled for bilateral knee arthroplasty or unilateral knee revision surgery;
• Cannot read and understand Arabic
• Have limited function due to musculoskeletal conditions other than unilateral knee osteoarthritis.
• Have been diagnosed with uncontrolled diabetes mellitus or blood pressure.
• Have been diagnosed with any neurologic disorders, such as stroke, Parkinson's disease or multiple sclerosis.
• Are morbidly obese and have a body mass index (BMI) greater than 40.
• Have advance osteoporosis or some other unstable chronic disease.
• Have been diagnosed with a peripheral vascular or uncontrolled cardiac disease.
• Participant will further be excluded post-surgery if they develop any surgical complications, such as deep vein thrombosis, uncontrolled infection or fracture.

The present study is a prospective six and twelve month follow-up trial to explore the outcome post TKA in addition to assess the validity, reliability and responsiveness of the Arabic version of Oxford Knee Score and the Star Excursion Balance Test with total knee arthroplasty patients.

An information sheet will be given to all participants who agree to participate to clarify the objectives of the study. Before participating, patients will need to sign a consent form (Appendix 2) and they will have the right to clarify any concerns about the study with the researcher. A patient's participation or otherwise will not affect the quality of service, all patients will receive conventional orthopedic care and a standard level of physiotherapy according to hospital protocols.