2010
Can “high flex” be achieved and does it matter in total knee ar-
throplasty? A randomized, controlled trial.
Morten Grove Thomsen, Henrik Husted, Kristian Otte, Anders Troelsen
Dept. of Orthopedics, University Hospital of Hvidovre, Denmark
Background:
Pain free range of motion (ROM) is a cornerstone in successful
total knee arthroplasty (TKA). The achievement of a high degree of knee flex-
ion is thought to improve the activity in daily living and possibly the patient
satisfaction.
Purpose:
The purpose was to compare ROM, patient satisfaction, pain, “feel”
of the knee, and activities of daily living between a standard posterior cruciate-
retaining TKA and a “high flex” posterior-stabilized TKA.
Methods:
The study is a randomized, single-blinded, controlled trial in which
patients undergoing one-stage bilateral TKA randomly had a standard AGC
(
Biomet®) cruciate-retaining TKA in one knee and a High-flex LPS (Zim-
mer®) posterior-stabilized TKA in the contra lateral knee. At follow-up 6
weeks, 3, 6 and 12 months postoperatively, the ROM, satisfaction, pain, “feel”
of the knee, and the abilities in daily activities were assessed. The study group
consisted of 33 patients (mean age: 67.2 yrs). The knees had comparable pre-
operative ROM.
Findings:
At 1-year follow-up we found a significantly higher degree of knee
flexion of 7°, both active and passive, in the “high-flex” group (p= 0.001). The
“
high-flex” LPS TKA showed a mean active flexion of 121° (range: 105°-
140
°) and passive flexion of 127° (range: 107°-146°). In both groups the medi-
an VAS pain score was 0, the median VAS satisfaction score was 9, and the
median VAS score of the patient “feel” of the knee was 9 at 1-year follow-up.
Further, there were no significant differences between the groups in the per-
formance of daily activities.
Conclusion:
The “high-flex” TKA showed increased knee flexion, but no
significant differences in patient related outcomes were found. This suggests
little clinical relevance of the difference in knee flexion as pain free ROM and
high patient satisfaction were achieved with both TKA’s.
