title: Weight-bearing flexion angle correlates significantly with severity of knee osteoarthritis.
abstract: This study evaluated flexion angles and mechanical loads at the knee during weight-bearing deep flexion in patients with knee osteoarthritis (OA). Thirty-eight knees of 26 patients (mean age, 73 years; range, 58-81 years) with medial knee OA and 16 knees of 8 healthy volunteers (mean age, 63.4 years; range, 60-65 years) were enrolled. Patients were subdivided into two groups based on Kellgren and Lawrence OA grade: moderate OA (grade 2, 17 knees) or severe OA (grade 3 or 4, 21 knees). Motion analysis was performed while rising from maximal knee flexion with one leg for each subject. Maximum knee flexion angles and net quadriceps moments in the weight-bearing motion were compared among the two OA groups and healthy subjects. Mean maximum flexion angle in patients was 91+/-9 degrees. Angles were about 30% smaller than passive range of motion (ROM). Mean angles in healthy subjects, moderate OA and severe OA were 102.7+/-5.0 degrees, 95.6+/-7.7 degrees and 86.5+/-7.2 degrees, respectively, and net quadriceps moments during motion were 5.5+/-1.2%BW*Ht, 4.5+/-1.7%BW*Ht and 3.9+/-1.3%BW*Ht, respectively. Angles and moments were significantly lower in OA patients than in healthy subjects. Maximum flexion angles during weight-bearing rising correlated significantly with HSS score (r=0.63; 95% confidence interval, 0.40-0.78) and were significantly lower in severe OA patients compared to moderate OA. This measurement may offer an important clinical index for knee OA.
authors.affiliation: Department of Orthopedic Surgery, Keio University, Tokyo, Japan. yuji-kuro@nifty.com
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kuroyanagi
authors.forename: Takeo
authors.initials: T
authors.lastname: Nagura
authors.forename: Hideo
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Toshiro
authors.initials: T
authors.lastname: Otani
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Suda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000503:physiopathology; D016059:Range of Motion, Articular; D012720:Severity of Illness Index; D016474:Weight-Bearing / Q000502:physiology