Loss of knee-extension strength is related to knee swelling after total knee arthroplasty.
OBJECTIVE
To examine whether changes in knee-extension strength and functional performance are related to knee swelling after total knee arthroplasty (TKA).


METHODS
Prospective, descriptive, hypothesis-generating study.


METHODS
A fast-track orthopedic arthroplasty unit at a university hospital.


METHODS
Patients (N=24; mean age, 66y; 13 women) scheduled for primary unilateral TKA were investigated 1 week before surgery and on the day of hospital discharge 2.4 days postsurgery.


METHODS
Not applicable.


METHODS
We assessed all patients for knee-joint circumference, knee-extension strength, and functional performance using the Timed Up & Go, 30-second Chair Stand, and 10-m fast speed walking tests, together with knee pain during all active test procedures.


RESULTS
All investigated variables changed significantly from pre- to postsurgery independent of knee pain. Importantly, knee circumference increased (knee swelling) and correlated significantly with the decrease in knee-extension strength (r=-.51; P=.01). Reduced fast-speed walking correlated significantly with decreased knee-extension strength (r=.59; P=.003) and decreased knee flexion (r=.52; P=.011). Multiple linear regression showed that knee swelling (P=.023), adjusted for age and sex, could explain 27% of the decrease in knee-extension strength. Another model showed that changes in knee-extension strength (P=.009) and knee flexion (P=.018) were associated independently with decreased performance in fast-speed walking, explaining 57% of the variation in fast-speed walking.


CONCLUSIONS
Our results indicate that the well-known finding of decreased knee-extension strength, which decreases functional performance shortly after TKA, is caused in part by postoperative knee swelling. Future studies may look at specific interventions aimed at decreasing knee swelling postsurgery to preserve knee-extension strength and facilitate physical rehabilitation after TKA.
The Lundbeck Center for Fast-Track Hip- and Knee Arthroplasty, Copenhagen University Hospital at Hvidovre, Denmark. bente.holm@hvh.regionh.dk
Bente
B
Holm
Morten T
MT
Kristensen
Jesper
J
Bencke
Henrik
H
Husted
Henrik
H
Kehlet
Thomas
T
Bandholm
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D004487:Edema / Q000150:complications / Q000503:physiopathology* / Q000534:rehabilitation; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D053581:Muscle Strength Dynamometer; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000502:physiology*; D016896:Treatment Outcome; D016138:Walking / Q000502:physiology*