title: How human gait responds to muscle impairment in total knee arthroplasty patients: Muscular compensations and articular perturbations.
abstract: Post-surgical muscle weakness is prevalent among patients who undergo total knee arthroplasty (TKA). We conducted a probabilistic multi-body dynamics (MBD) to determine whether and to what extent habitual gait patterns of TKA patients may accommodate strength deficits in lower extremity muscles. We analyzed muscular and articular compensations in response to various muscle impairments, and the minimum muscle strength requirements needed to preserve TKA gait patterns in its habitual status. Muscle weakness was simulated by reducing the strength parameter of muscle models in MBD analysis. Using impaired models, muscle and joint forces were calculated and compared versus those from baseline gait i.e. TKA habitual gait before simulating muscle weakness. Comparisons were conducted using a relatively new statistical approach for the evaluation of gait waveforms, i.e. Spatial Parameter Mapping (SPM). Principal component analysis was then conducted on the MBD results to quantify the sensitivity of every joint force component to individual muscle impairment. The results of this study contain clinically important, although preliminary, suggestions. Our findings suggested that: (1) hip flexor and ankle plantar flexor muscles compensated for hip extensor weakness; (2) hip extensor, hip adductor and ankle plantar flexor muscles compensated for hip flexor weakness; (3) hip and knee flexor muscles responded to hip abductor weakness; (4) knee flexor and hip abductor balanced hip adductor impairment; and (5) knee extensor and knee flexor weakness were compensated by hip extensor and hip flexor muscles. Future clinical studies are required to validate the results of this computational study.
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center,1611 W. Harrison St., Suite 204, Chicago, IL 60612,USA; State Key Laboratory for Manufacturing System Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China. Electronic address: mostafavizadeh@yahoo.com.
authors.forename: Marzieh M
authors.initials: MM
authors.lastname: Ardestani
authors.affiliation: Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
authors.forename: Mehran
authors.initials: M
authors.lastname: Moazen
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D005260:Female; D005684:Gait; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018908:Muscle Weakness / Q000209:etiology* / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology*
keywords: Human gait; Joint force; Multi-body dynamics; Muscle weakness; Rehabilitation; Total knee arthroplasty