A comparison of standard and high-flexion knees: are we getting what we expected?
Some patients have been less than satisfied with flexion after total knee arthroplasty (TKA). As early designs provided limited flexion, companies have developed high-flexion designs. We conducted a study to compare flexion between 2 standard and 3 high-flexion designs and to compare clinical and radiographic postoperative flexion. Clinical and radiographic measurements were obtained by 3 independent orthopedists. Clinical flexion, with the patient maximally bending his or her knee as far as possible, was measured with a goniometer, recorded, and compared with measurements from lateral radiographs of the knee in the same position. A total of 144 knees (108 patients) were included in the study. Mean preoperative flexion was 110° for both groups, and mean postoperative flexion was 111° clinically and 109° radiographically for the standard designs, and 114° clinically and 117° radiographically for the high-flexion designs (P<.05). The groups had similar preoperative and postoperative Knee Society knee and function scores. Measurements obtained by the 3 independent examiners were highly correlated. Compared with the standard designs, the highflexion designs demonstrated statistically significantly more flexion, though the clinical increase in flexion was relatively small (3º).
Orthopaedic Surgeon, Hanford Orthopaedics, California. colwell@scripps.edu.
Kenny T
KT
Mai
Christopher A
CA
Verioti
Kace A
KA
Ezzet
Steven N
SN
Copp
Clifford W
CW
Colwell
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D011184:Postoperative Period; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D016896:Treatment Outcome