Characterizing the Magnitude of and Risk Factors for Functional Limb Lengthening in Patients Undergoing Primary Total Knee Arthroplasty

Authors

Brian P. Chalmers
Mark LaGreca, Philadelphia College of Osteopathic Medicine
Jacqueline Addona
Peter K. Sculco
Steve B. Haas
David J. Mayman

Document Type

Article

Publication Date

5-2021

Abstract

Background: There is little data on the magnitude and factors for functional leg lengthening after primary total knee arthroplasty (TKA). Questions/Purpose: We sought to determine the incidence of and risk factors for functional leg lengthening after primary TKA. Methods: We retrospectively reviewed consecutive unilateral primary TKAs at a single institution from 2015 to 2018. Of the 782 TKAs included, 430 (55%) were performed in women; the mean age was 66 years, and the mean body mass index was 29 kg/m². Preoperatively, 541 (69%) knees were varus deformities and 223 (29%) were valgus deformities. Hip to ankle biplanar radiographs were obtained preoperatively and 6 weeks postoperatively for all patients. Two independent researchers measured leg length, coronal plane deformity, lateral knee flexion angle, and overall mechanical alignment on all preoperative and postoperative radiographs. Results: The mean overall ipsilateral functional leg lengthening was 7.0 mm. Seven hundred knees (90%) were overall functionally lengthened, including 462 (59%) knees lengthened >5 mm and 250 (31%) knees lengthened 10 mm or more. A valgus deformity and coronal plane deformity of 10° or more were significant risk factors for increased functional lengthening. Patients with severe valgus deformities (>10°) had the largest amount of functional lengthening, at a mean of 13.5 mm. Conclusion: After primary TKA, 90% of limbs are functionally lengthened, including roughly one-third over a centimeter. Valgus knee deformities and severe deformities (>10°) were significant risk factors for increased limb lengthening.

Comments

This article was published in HSS Journal.

The published version is available at https://doi.org/10.1177%2F15563316211009140.

Copyright © 2021 The Author(s).

Publication Title

HSS Journal: The Musculoskeletal Journal of Hospital for Special Surgery

Recommended Citation

Chalmers, Brian P.; LaGreca, Mark; Addona, Jacqueline; Sculco, Peter K.; Haas, Steve B.; and Mayman, David J., "Characterizing the Magnitude of and Risk Factors for Functional Limb Lengthening in Patients Undergoing Primary Total Knee Arthroplasty" (2021). Orthopedic Surgery Resident Research. 52.
https://digitalcommons.pcom.edu/orthopedic_surgery_residents/52