This project will be a descriptive, hypothesis-generating study. The aim is to identify risk factors for poor response to rehabilitation programs after TJR and use these to identify patients who are most susceptible to poor outcomes in order to optimise appropriate rehabilitations strategies and rationalising the distribution of health care resources.

Fast-track surgery for total knee and hip arthroplasty has improved markedly in recent years with decreased hospitalization and postoperative complications. In 2014 there were performed over 9000 total hip arthroplasty (THA) and over 8500 total knee arthroplasty operations (TKA) in Denmark. During the same year Bornholm's regional hospital performed 85 THA's and 47 TKA's of these operations.

Even though the initial surgical procedure being technical and radiological satisfactory, there are a big proportion of patients who endure dissatisfaction and disability after total joint replacement (TJR) (between 20-40%). The strongest predictor for dissatisfaction after a TKA were found to be preoperative expectation not met postoperatively (10.7x greater risk). To date, there is no criterion standard for assessing the outcome of neither expectations nor satisfaction for patients undergoing TJR.

Patient's expectations are of a particular significance because they are linked to requests for elective and often costly treatments. Several studies have investigated the fulfillment of patient' expectations, however the focus has been primarily assessed by expectations regarding pain, but may also be influenced by several other factors. Patient's expectations are also strongly related to patient's assessments of outcome.

It is well established that there is a correlation between satisfaction of surgery and objective improvements in pain, function and general health-related quality of life, but just as patient' expectations the postoperative satisfaction may also incorporate multiple and varies factors that affect the overall outcome. One of these factors can be "ability to forget the artificial joint" in everyday life and can therefore be regarded as the ultimate possible goal for patient satisfaction.

Additionally, many patients undergoing TJR experience continued disability, which is largely caused by persistent pain postoperatively. Studies have shown that a high level of pain catastrophizing is a predictor of high levels of acute and persistent pain after various surgeries, and further investigation of pain catastrophizing as a predictor of outcome after TJR is warranted.

Many of the patients who experience dissatisfaction and disability after TJR do not undergo revision and present a burden for the community health clinicians and health services to continue to remedy their dissatisfaction. The rehabilitation after the initial surgery has been proven to produce short-term benefits, but these benefits does not seem to persist. As many patients' experiences limited clinical improvements postoperatively and no national consensus on the rehabilitation for this group, an optimal rehabilitation protocol for this group of patients is still warranted.

Several other associations between patient characteristics and the chance to achieve clinically importance improvements to TJR surgery have been identified as age, gender, body mass index, ethnicity, psychological distress, co-morbidity-profile and radiographic osteoarthritis severity. It can be speculated that while fast-track surgery aid to early recovery, the number of falls within the population of patients undergoing total lower limb arthroplasty will increase as a result from increased, early activities. Jørgensen & Kehlet found the overall incidence of falls postoperatively in hip and knee replacements to be low, the inclusion of fall history may be important to optimize the rehabilitation protocol and reduce future risk of falls in this group of patients.

Patients undergoing lower TJR wish to return to pre-pathological physical status, but there has been found a limited interest in actually undertaking greater efforts in physical therapy to fully achieve this either for pleasure or health gains. Individual beliefs and perceptions presents a big factor influencing physical activity postoperatively and it is therefore important to examine this further when developing management plans aimed to optimize rehabilitation in this group of patients.

There is a dearth of literature examining the impact on actual response rates in rehabilitation after TJR surgery taken fall history, patient expectations, subjective as well as objective measurements into account. It is therefore important to clarify the relationship between these characteristics and responsiveness to postoperative rehabilitation. The available data suggest that identifying and addressing the mechanism for reduced activity and identification of the group of patients who may or may not benefit from a rehabilitation programme may be the approach needed. This data can be used to allocate already sparse resources more beneficially, and to optimise criteria for the rehabilitation intervention. An expert consensus on the best practice has already identified the need for preoperative screening to identify patients most in need for rehabilitation for patients undergoing total hip arthroplasty.

Aim:

This project will be a descriptive, hypothesis-generating study. The aim is to identify risk factors for poor response to rehabilitation programs after TJR and use these to identify patients who are most susceptible to poor outcomes in order to optimise appropriate rehabilitations strategies and rationalising the distribution of health care resources.

Material and methods:

This project will be of a prospective cohort design where all patients who are scheduled to undergo a total joint replacement (total knee arthroplasty or total hip arthroplasty) at Bornholms regional hospital will be invited to participate. Due to the minimal effort and time required filling out the questionnaires and performing the 30sec chair stand test a minimal number of patients are expected to decline participation. Based on clinical experience the annual number of patients to undergo lower extremity TJR at Bornholm's regional hospital is expected to be around 160 patients.

During study enrolment basic, demographic data (e.g. age, gender, co-morbidities, BMI) will be collected on each participant.

Preoperative assessments (prior to surgery) and postoperative assessments (follow up at 3 months after surgery) will include:

Preoperative assessments:

• Use of joint specific analgesics and other medication
• Fall history
• Patient expectation questionnaire
• Pain catastrophizing questionnaire
• KOOS / HOOS questionnaire
• 30 second chair stand test

Postoperative assessments:

• Use of joint specific analgesics and other medication
• Fall history
• KOOS / HOOS questionnaire
• Pain catastrophizing questionnaire
• 30 second chair stand test
• The Forgotten Joint Score
• Patient satisfaction questionnaire

Approvals:

This cohort study has to obtain approval from the Danish Datatilsynet (J.nr. 2016-41-4783). This study will not change the pre or postoperative treatment of the included patients, and therefore no other formal approval is required.

Postoperative rehabilitation:

All patients are given a rehabilitation plan from the hospital to engage in a 4-12 weeks rehabilitation program in one of two rehabilitations centres located on Bornholm. The rehabilitation starts with a individual consultation with an experienced physiotherapist within 3 weeks of surgery where appropriate home-exercises are revised and instructed, and shortly after the consultation the patient is enrolled in a out-patient, group-based physical therapy program, twice weekly sessions for 4-12 weeks, where the length of the program depends on the patients objective response to the physical therapy. The patients are encouraged to continue their home-based exercises parallel to the physical therapy sessions and after the culmination of the physical therapy program. At the end of the supervised physical therapy program, the involved physiotherapist will subjectively assess each patient's compliance in regards to their exercise adherence to the rehabilitation the patients have undertaken.

Evaluation of the surgery and rehabilitation intervention is performed at the hospital 3 months after the surgery by the assigned orthopaedic surgeon, where the postoperatively outcome measurements will be recorded.

Statistical analysis:

The statistical analysis will compare preoperative and postoperative scores in terms of the use of analgesics, fall history, patient expectations / satisfaction, KOOS / HOOS, pain catastrophizing, the forgotten joint score and 30sec chair stand test. Significance will be set to <0.05. A Chi-square test will be used to investigate whether distributions of categorical variables differ from one another. Multivariable linear regression will be performed to examine the association between patient characteristics and the response rate to TKA and THA individually and TKA/THA combined.

Inclusion Criteria:

• patients undergoing total knee arthroplasty or total hip arthroplasty
• must be able to participate in postoperative rehabilitation
• must be able to talk and understand Danish or English

Exclusion Criteria:

• None

All patients who are scheduled to undergo a total joint replacement (total knee arthroplasty or total hip arthroplasty) at Bornholms regional hospital will be invited to participate.