An observational study in Arthrosis, sponsored by Turku University Hospital. Recruiting at 2 sites in Finland. Open to participants aged Up to 80 Years. Per ClinicalTrials.gov, last updated 2026-09-25.
Sponsored by Turku University Hospital · Observational
The goal of this observational study is to examine changes in physical activity, sleep quality, knee extension and flexion strength, knee range of motion, and patient-reported outcomes before and after same-day discharge knee arthroplasty (SDD-KA). The study will also investigate whether these changes are associated with each other and with patient satisfaction. As a prespecified secondary aim, researchers will compare these outcomes between patients undergoing medial unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA).
The main questions it aims to answer are:
Participants will:
This is a prospective observational cohort study investigating postoperative recovery in patients undergoing same-day discharge knee arthroplasty (SDD-KA) for knee osteoarthritis. The primary aim is to characterize pre- to postoperative changes in physical activity, sleep quality, knee extension and flexion strength, knee range of motion, and patient-reported outcomes, and to investigate associations among these changes and their relationship with patient satisfaction.
As a prespecified secondary aim, the study will compare these outcomes between patients undergoing medial unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). Patients are not randomized to UKA or TKA; the surgical procedure is determined by the treating clinical team according to established clinical indications. The study therefore represents an observational comparison of two patient cohorts undergoing different surgical procedures.
The study will include 120 patients undergoing primary SDD-KA at Turku University Hospital, Finland. The cohort will consist of 30 patients undergoing medial UKA and 90 undergoing TKA. Participants will be followed prospectively from the preoperative period through 12 months after surgery.
Physical activity and sleep will be assessed objectively using wearable accelerometers. Measurements will be performed during a two-week period before surgery, continuously from the time of surgery through 3 months postoperatively, and during a further two-week measurement period at 12 months postoperatively. Accelerometer data will be analysed at the UKK Institute for Health Promotion Research using validated algorithms. Clinical assessments will include isometric knee extension and flexion strength and active knee range of motion. Patient-reported outcomes will include knee-specific function, sleep quality, pain, health-related quality of life, and satisfaction with surgery. Assessments will be performed at predefined time points during the preoperative and postoperative follow-up period. The study is designed to provide an integrated assessment of recovery by combining objective wearable sensor-derived measures with standardized clinical assessments and patient-reported outcomes.
After completion of the 12-month follow-up, the data will be analysed by the study statistician. Baseline characteristics and outcome measures will be summarized descriptively. The primary analysis will evaluate the change in Oxford Knee Score (OKS) from baseline to 12 months in the whole cohort. As a secondary analysis, the change in OKS will be compared between the UKA and TKA groups.
Changes in outcomes over time will be assessed using linear mixed-effects models, where appropriate. Associations between physical activity variables, knee extension and flexion strength, range of motion and OKS will be assessed using models with a patient-level random effect for OKS, and with physical activity, strength, range of motion, time point and potential confounders as fixed effects. The patient-level random effect allows for handling the situations where some patients may have data missing at some time point, thus reducing the potential impact of dropout on the results. Potential confounders, including age, sex, body mass index, and ASA physical status classification, will be considered in the analyses. Multivariable regression analyses will also be used to examine associations between changes in the outcome measures.
As treatment allocation is based on clinical indication rather than randomisation, the UKA and TKA groups are expected to differ in baseline characteristics. Comparisons between the groups will therefore be adjusted for baseline characteristics, and residual confounding cannot be excluded. No adjustment for multiple comparisons will be made; analyses of secondary outcomes are considered exploratory and will be interpreted accordingly. Results will be presented with 95% confidence intervals. Statistical significance will be set at p\<0.05.
Data will be collected prospectively according to a predefined study protocol. Clinical assessments and questionnaires will be performed using standardized procedures, and wearable sensor data will be collected according to the predefined measurement schedule. Data quality will be monitored through review of collected study data and checks for completeness and consistency. Missing or incomplete measurements will be documented and handled according to the prespecified statistical analysis plan.
The study will increase understanding of modifiable factors associated with recovery and satisfaction after KA. The findings may inform patient selection and support the optimisation of postoperative rehabilitation, and may help identify factors influencing recovery and surgical outcomes. Furthermore, the results may provide a foundation for designing interventions aimed at increasing postoperative mobilisation and physical activity, potentially using activity monitors to support optimal recovery, and may guide the design of future comparative studies.
2,974 studies on the registry are indexed under Osteoarthritis; 438 are open to participants now.
This study's planned enrollment of 120 is above the median of 100 across 601 observational studies indexed under Osteoarthritis.
Browse Osteoarthritis studies →Turku University Hospital is the lead sponsor of 287 studies on the registry; 67 are open to participants now.
Counted across the registry records on this site, refreshed daily.
The study population consists of patients undergoing same-day discharge primary knee arthroplasty: medial UKA or TKA according to standard clinical practice at Turku University Hospital. The choice of procedure is made on clinical grounds by the treating surgeon and is not influenced by study participation. Operations are performed by experienced arthroplasty surgeons under spinal anaesthesia following the hospital's standardized same-day discharge protocol.
Inclusion Criteria:
- Primary knee osteoarthritis: medial or lateral Kellgren Lawrence grade 3-4 for TKA and antero-medial grade 3-4 for UKA.
Patient criteria for outpatient knee arthroplasty (UKA or TKA):
Exclusion Criteria:
Exclusion criteria for outpatient surgery:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients undergoing primary same-day discharge medial unicompartmental knee arthroplasty (UKA) for knee osteoarthritis. The medial UKA group will include 30 participants. The surgical procedure is determined by the treating clinical team according to established clinical indications and is not assigned by the study.
Procedure: Medial unicompartmental knee arthroplasty (UKA)
Patients undergoing primary same-day discharge total knee arthroplasty (TKA) for knee osteoarthritis. The TKA group will include 90 participants. The surgical procedure is determined by the treating clinical team according to established clinical indications and is not assigned by the study.
Procedure: Total knee arthroplasty (TKA)
Primary medial UKA performed as part of routine clinical care for knee osteoarthritis. The procedure is not assigned by the study.
Primary TKA performed as part of routine clinical care for knee osteoarthritis. The procedure is not assigned by the study.
Oxford Knee Score (OKS)
A 12-item patient-reported questionnaire assessing knee pain and function during daily activities. Each item is scored from 0 to 4, giving a total score ranging from 0 to 48. Higher scores indicate better knee function and less pain.
Time frame: The OKS will be completed by participants at baseline before surgery and at 3 and 12 months after surgery. The primary outcome is the change in OKS from baseline to 12 months after surgery.
Objectively measured physical activity (sensor)
Physical activity will be assessed objectively using a wearable accelerometer worn by participants during daily life. The accelerometer will continuously record movement during the predefined measurement periods. Physical activity will be characterized using accelerometer-derived measures of activity, including time spent at different levels of physical activity and daily activity patterns.
Time frame: Measurements will be performed during a two-week period before surgery, continuously from surgery to 3 months postoperatively, and during a further two-week period at 12 months after surgery.
Objectively measured sleep (sensor)
Sleep will be assessed objectively using a wearable accelerometer worn by participants during daily life. Sleep-related measures will be derived from accelerometer recordings during the predefined measurement periods. Sleep measures will be used to characterize changes in sleep patterns.
Time frame: Measurements will be performed during a two-week period before surgery, continuously from surgery to 3 months postoperatively, and during a further two-week period at 12 months after surgery.
Isometric knee extension and flexion strength
Isometric knee extension and flexion strength will be assessed using a standardized strength measurement procedure. Participants will perform a maximal voluntary isometric knee extension and flexion contraction, and the maximal force produced will be recorded. Higher values indicate greater knee muscle strength.
Time frame: Measurements will be performed before surgery and at 12 months after surgery.
Knee range of motion
Active knee range of motion will be assessed by measuring knee flexion and extension using a standardized clinical measurement procedure. Knee range of motion will be recorded in degrees. Greater knee flexion and less limitation in knee extension indicate better knee mobility.
Time frame: Measurements will be performed before surgery and at 12 months after surgery.
Jenkins Sleep Scale (JSS)
The Jenkins Sleep Scale (JSS) is a 4-item patient-reported questionnaire assessing the frequency of common sleep problems during the previous month. Each item is scored from 0 to 5, giving a total score ranging from 0 to 20. Higher scores indicate more frequent sleep problems and poorer sleep quality.
Time frame: The JSS will be completed at 2 weeks preoperatively and 12 months postoperatively.
Pain -visual analogue scale (VAS)
Pain intensity will be assessed using a visual analogue scale. Participants will rate their pain on a continuous scale from 0 to 100 mm, where 0 indicates no pain and 100 indicates the worst pain imaginable. Pain will be assessed both at rest and during movement. Higher scores indicate greater pain intensity.
Time frame: Measurements will be performed before surgery, 3 and 12 months after surgery.
Health-related quality of life
Health-related quality of life will be assessed using the 15D questionnaire, a standardized patient-reported measure covering 15 dimensions of health, including mobility, physical functioning, pain, sleep, and mental well-being. The 15D produces a single index score ranging from 0 to 1, where 0 represents the worst possible health state and 1 represents the best possible health state. Higher scores indicate better health-related quality of life.
Time frame: The questionnaire will be completed preoperatively, 3 and 12 months postoperatively.
Patient satisfaction
Patient satisfaction with the outcome of knee arthroplasty will be assessed using a 5-point Likert scale. Participants will rate their overall satisfaction with the result of surgery, ranging from very dissatisfied to very satisfied. Higher scores indicate greater satisfaction with the surgical outcome.
Time frame: Satisfaction will be assessed at 3 and 12 months postoperatively.
Plan to share: No — There is currently no plan to make individual participant data (IPD) available to other researchers. The study will collect individual-level clinical, patient-reported, and wearable sensor data, and any sharing of such data would be subject to applicable data protection requirements, ethical considerations, and institutional policies.
No publications or documents are linked to this record.
Started Aug 2025 (actual). Primary completion is estimated for Feb 2029, 42 months after the start.
Of 146 non-industry observational studies under Osteoarthritis, half reached primary completion within 36 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 97. This study's planned 42 months is above that.
Counting every sponsor, half of 228 studies reached it within 57 months; a quarter within 21 and three quarters within 141.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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