A Feasibility Study on an Advanced Rehabilitative Prototype of KNEE-LOCOBOT on Knee Osteoarthritis Patients

Total knee replacement (TKR) has proven to be an effective treatment modality for end-stage kneeosteoarthritis (OA), relieving pain and improving patients' functional abilities. With an ageing and increasingly obese population, the number of people with end-stage osteoarthritis requiring TKR is expected to rise. In North America for example, conservative estimates suggest that the incidence rate of TKR is expected to increaseby 429 procedures/100,000 to 725/100,000 by 2050, a 143% projected increase in TKR volume. In 2019, more than 2,000 TKR surgeries were performed in Singapore General Hospital, and over800 TKR surgeries in Tan Tock Seng Hospital. With population aging and increasingly affluent lifestyle trends,these numbers expected to rise. Post-surgical rehabilitation contributes significantly to successful outcomes following knee replacement surgery. A systematic review reported patients receiving physiotherapy exercises had improved physical function and pain up to 6 months.

Current post-operative TKR care in TTSH includes a 4-day inpatient hospitalization stay with daily rehabilitation including early mobilization surgery day itself. Patients undergoing immediate inpatient post-TKR rehabilitation in TTSH had shorter inpatient stays and a higher discharge rate home. However, rehabilitation is far from complete, as immediate post-TKR rehabilitation phase has to be followed up by post-discharge exercises. Currently, TTSH outpatient TKR patients undergo 5 outpatient physiotherapy sessions over a 3 month period and machines include inpatient Continuous Passive Motion (CPM) and outpatient Motomed. As yet, no robotic aided devices have been employed for this population of patients. The transition from hospital to home has given rise to rehabilitation service gap whereby patients are mostly doing unsupervised self-directed exercises at home setting. Patient progress, exercises intensity and technique will be not supervised and corrected until they consult physiotherapist at outpatient clinic with could take up to 2-3 weeks later. Our local experience shows that there is a high level of poor post-operative exercise compliance, predisposing patients to complications of weakness, knee stiffness, scarring and pain, resulting in reduced long term function post-TKR. In fact, it has been demonstrated that 25% of patients fail to achieve minimum clinically important improvement in function for 6 or more months after TKR and 20% of them still report moderate to severe activity limitations 2 years after TKR. Several rehabilitation methods and modalities are available for patients received TKR, however optimal rehabilitation strategy and protocols have yet to be determined. Studies had demonstrated that continuous passive motion (CPM) and inpatient rehabilitation programme may not provide additional benefit to the patient or healthcare system. Rather, early rehabilitation, telerehabilitation, outpatient therapy and consistent, high intensity, high velocity exercise, maybe the vital components for successful rehabilitation for patient with TKR. For example, telerehabilitation has been reported to result in a statistically significant improvement in pain in addition to probable gains of functional mobility improvement in people following.

Our project aims to achieve early return in function to as near as normal, for patients within 1 month of knee OA through the deployment of robot-aided prototype device. This device will provide early self-paced intensive rehabilitation exercises on these group of patients at home with the long-term aim of minimizing future disability and better quality of life. Other secondary objectives of our study include improving exercise compliance, and rehabilitation cost saving among knee OA patients.

Inclusion criteria

• Adults aged 21-80 years old,
• Diagnosed to have knee osteoarthritis by clinician
• Ability to understand and give consent
• Premorbid Functional Ambulation Category of 6
• Knee flexion ROM of at least 100 degrees
• Ability to sit continuously for 60 minutes

Exclusion criteria

• Presence of co-existing neurological impairments causing lower limb weakness (e.g. stroke)
• Medical conditions incompatible with research participation: uncontrolled medical illnesses (hypertension or diabetes, ischaemic heart disease, congestive heart failure, bronchial asthma, severe /untreated depression, agitation, end stage renal/liver/heart/lung failure, unresolved cancers.
• Anticipated life expectancy of < 6 months
• Local factors potentially worsened by intensive robot-aided arm therapy and computer-based training: recent limb fracture, knee pain VAS >4/10, fixed knee flexion contracture >10-degree, keen flexion range of motion <100 degree
• Any musculoskeletal condition that may limit continuous exercise duration of 30minutes
• Pregnant women
• Recent knee operation within past 3 month