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F. Temporiti1,2, D. De Leo1, P. Adamo1, G. Papa1, F. Traverso1, N. Maffiuletti3, R. Gatti1,2
1Humanitas Clinical and Research Center - IRCCS, Milan, Italy, 2Humanitas University, Milan, Italy, 3Schulthess Clinic, Zurich, Switzerland
Background: Total knee arthroplasty (TKA) represents an effective and definitive treatment for end-stage osteoarthritis that is able to relieve pain, improve functional level and quality of life. Rehabilitation after TKA is addressed to rapidly achieve functional independence for an early discharge and return to daily activities. However, successful execution of daily tasks requires adequate ability to modulate motor performance, which depends on both central and peripheral mechanisms that are usually impaired after joint damage or surgery.
Purpose: The aim of this study was to assess performance modulation ability during motor and functional tasks in patients after TKA.
Methods: Twenty patients undergoing TKA and twenty age-matched healthy subjects performed isokinetic knee extension (ω=60°/s) with the involved and uninvolved limbs, sit-to-stand and walking tasks at three levels of effort (maximum, 50% and 25% performed according to subject perception). Maximum performance in terms of peak torque (PT - Nm) during knee extension, overshoot (OS - N) during sit-to-stand and walking speed (m/s) were evaluated. Subsequently, relative modulation error (RME - %) between target and observed performance levels was computed for the submaximal tasks (RME50% and RME25%). Patients were evaluated the day before (T0) and 4 days after surgery (T1), whereas healthy subjects underwent a single test session.
Results: Patients’ maximum performance significantly declined after surgery for knee extension with involved limb (T0: 51±22 Nm, T1: 23±5 Nm, p<0.001), sit-to-stand (T0: 189±75 N, T1: 88±66 N, p<0.001) and walking (T0: 1.45±0.43 m/s, T1: 0.82±0.31 m/s, p<0.001), and was significantly lower in patients compared to healthy subjects (p≤0.001 for all outcome measures). Patients revealed increased RME-50% after surgery (from -0.1±0.38 to -0.79±0.32 for knee extension with the involved limb - p<0.001, and from -0.06±0.36 to -0.51±0.56 for sit to stand - p=0.004) and RME-25% (from -0.67±0.72 to -2.29±0.75 for knee extension with the involved limb - p<0.001, and from -0.72±1.02 to -1.77±1.18 for sit-to-stand - p=0.011). At T0, knee extension RME25% and walking RME50% and RME25% were higher in patients than in healthy subjects. At T1, RME50% and RME25% were higher in patients for knee extension with involved limb, sit-to-stand and walking.
Conclusion(s): Patients revealed decreased performance modulation ability after TKA, which was also lower with respect to healthy subjects both before and after surgery. Modulation impairments after TKA might derive from alterations of ascending sensory information and perception of feedforward neural signals responsible for sense of force and sense of effort. Moreover, the reduced motor and functional level in patients may also influence modulation ability.
Implications: These findings might be useful for optimizing rehabilitation of patients undergoing TKA. In fact, the execution of daily-living activities requires submaximal levels of performance and the ability to modulate motor output may play a role in the restoration of functional independence after TKA. Interventions addressed to recalibrate sense of force, sense of effort and their interaction, such as symmetry-based resistance training or sensorimotor interventions incorporating biofeedback might be proposed to improve performance modulation ability.
Funding, acknowledgements: The authors did not receive any funding.
Keywords: Total knee arthroplasty, Performance modulation, Motor recovery
Topic: Orthopaedics
Did this work require ethics approval? Yes
Institution: Humanitas Clinical and Research Center - IRCCS
Committee: Internal Ethical Committee of the Humanitas Clinical and Research Center
Ethics number: CLF18/03
All authors, affiliations and abstracts have been published as submitted.
