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A Randomized, Controlled, Prospective Study Evaluating the Effect of Patellar Eversion on Functional Outcomes in Primary Total Knee Arthroplasty

Jenkins, Derek MD1; Rodriguez, Jose MD1; Ranawat, Amar MD1; Alexiades, Michael MD1; Deshmukh, Ajit MD1; Fukunaga, Takumi DPT, ATC1; Greiz, Michelle RPT1; Rathod, Parthiv MD1; McHugh, Malachy PhD1

Journal of Bone & Joint Surgery - American Volume: 21 May 2014 - Volume 96 - Issue 10 - p 851–858
doi: 10.2106/JBJS.L.01513
Scientific Articles
Supplementary Content

Background: Patellar mobilization technique during total knee arthroplasty has been debated, with some suggesting that lateral retraction, rather than eversion, of the patella may be beneficial. We hypothesized that patients with knees surgically exposed using patellar lateral retraction would have comparable outcomes with patients with knees surgically exposed using patellar eversion.

Methods: After an a priori power analysis, 120 patients with degenerative arthrosis were prospectively enrolled and were randomized to one of two patellar exposure techniques during the primary total knee arthroplasty: lateral retraction or eversion. The primary outcome measure was one-year, dynamometer-measured quadriceps strength. The secondary outcome measures evaluated during hospital stay included the ability to straight-leg raise, visual analog scale in pain, walking distance, and length of stay. The secondary outcome measures that were evaluated preoperatively and through a one-year follow-up included the Short Form-36 Physical Component Summary and Mental Component Summary scores, range of motion, quadriceps strength, and radiographic rate of patella baja and tilt.

Results: A mixed-model analysis of variance showed no significant differences between the two groups in the one-year outcome measures. At one year postoperatively, quadriceps strength was not different between groups (p = 0.77), and the range of motion significantly improved (p < 0.01) from preoperative values by a mean value (and standard deviation) of 6° ± 17°, with no significant difference (p = 0.60) between groups. The Short Form-36 Physical Component Summary score and Mental Component Summary score significantly improved (p < 0.01) for both study groups from preoperatively to one year postoperatively with no significantly different effects between groups (time × group, p = 0.85 for the Physical Component Summary score and p = 0.71 for the Mental Component Summary score), and the scores were not different at one year after surgery. There were no significant differences between groups in the change in frequency of the radiographic patella baja (p = 0.99) or the radiographic patellar tilt (p = 0.77) from before surgery to one year after surgery.

Conclusions: Lateral retraction of the patella did not lead to superior postoperative results compared with eversion of the patella during total knee arthroplasty as evaluated using our primary outcome measure of one-year, dynamometer-measured quadriceps strength or our secondary outcome measures.

Level of-Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

1Department of Orthopaedic Surgery, Lenox Hill Hospital, Black Hall, 11th Floor, 130 East 77th Street, New York, NY 10075-1851. E-mail address for D. Jenkins:

Investigation performed at the Department of Orthopaedic Surgery, Lenox Hill Hospital, New York, NY

Copyright 2014 by The Journal of Bone and Joint Surgery, Incorporated
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