title: Muscle strength loss in the lower limb after total knee arthroplasty.
abstract: OBJECTIVE
  This study aimed to examine functional mobility and strength loss in the ankle plantarflexors and dorsiflexors and knee extensors and flexors after total knee arthroplasty.
  
  
  METHODS
  This was a prospective, longitudinal cohort study. Maximal voluntary isometric contractions and gait speed assessments were performed before and after total knee arthroplasty.
  
  
  RESULTS
  Twenty patients undergoing primary total knee arthroplasty were followed. Repeated-measures analysis of variance results indicated an effect of time on muscle strength, with all muscle groups being significantly weaker (knee extensors, P < 0.001; knee flexors, P < 0.001, ankle plantarflexors, P = 0.004; ankle dorsiflexors, P < 0.001) 1 mo postoperatively. Knee extensors were 42% weaker than preoperative levels, and knee flexors were 34% weaker, whereas the ankle plantarflexors were 17% weaker, and the dorsiflexors were 18% weaker. Three and 6 mos after surgery, strength in all muscle groups was similar to preoperative levels (P > 0.05 for all muscle groups). Patient function followed a similar trend, with patients walking slower 1 mo postoperatively (P < 0.001) and recovering to preoperative levels by 3 and 6 mos after surgery (P > 0.05).
  
  
  CONCLUSIONS
  Patients may benefit from early postoperative rehabilitation, including strengthening of the plantarflexors and dorsiflexors, although strengthening of the quadriceps and hamstrings muscles should continue to be a priority.
authors.affiliation: Physical Therapy Program, Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, USA.
authors.forename: Dana L
authors.initials: DL
authors.lastname: Judd
authors.forename: Donald G
authors.initials: DG
authors.lastname: Eckhoff
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Stevens-Lapsley
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008137:Longitudinal Studies; D035002:Lower Extremity / Q000503:physiopathology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D020370:Osteoarthritis, Knee / Q000601:surgery; D011446:Prospective Studies