Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Jan 16, 2021; 9(2): 357-371
Published online Jan 16, 2021. doi: 10.12998/wjcc.v9.i2.357
Limb length discrepancy after total knee arthroplasty: A systematic review and meta-analysis
Sujit Kumar Tripathy, Siddharth Satyakam Pradhan, Paulson Varghese, Prabhudev Prasad Purudappa, Sandeep Velagada, Tarun Goyal, Bijnya Birajita Panda, Jagadeesh Vanyambadi
Sujit Kumar Tripathy, Siddharth Satyakam Pradhan, Paulson Varghese, Sandeep Velagada, Department of Orthopaedics, All India Institute of Medical Sciences, Bhubaneswar 751019, Odisha, India
Prabhudev Prasad Purudappa, Department of Orthopedics, VA Boston Health care, Boston, Massachusetts 02130, United States
Tarun Goyal, Department of Orthopaedics, All India Institute of Medical Sciences, Bathinda 209201, India
Bijnya Birajita Panda, Department of Ophthalmology, SCB Medical College, Cuttack 751019, India
Jagadeesh Vanyambadi, Department of Orthopaedics, Salford Royal NHS Foundation Trust, Salford M6 8HD, United Kingdom
Author contributions: Tripathy SK, Pradhan SS, Varghese P and Panda BB designed the study, searched the literature and screened the articles; the assessment of the quality of the studies and the statistical analysis was performed by Tripathy SK, Panda BB, Vanyambadi J and Goyal T; Velagada S, Purudappa PP and Tripathy SK wrote the manuscript; Tripathy SK, Purudappa PP and Goyal T provided intellectual content; all authors read the manuscript and approved the final manuscript for publication.
Conflict-of-interest statement: On behalf of all authors, the corresponding author states that there is no conflict of interest.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Sujit Kumar Tripathy, DNB, MBBS, MD, Additional Professor, Department of Orthopaedics, All India Institute of Medical Sciences, Sijua, Patrapada, Bhubaneswar 751019, Odisha, India.
Received: September 16, 2020
Peer-review started: September 16, 2020
First decision: November 14, 2020
Revised: November 14, 2020
Accepted: December 11, 2020
Article in press: December 11, 2020
Published online: January 16, 2021
Research background

Limb length discrepancy (LLD) following total knee arthroplasty (TKA) has not been widely studied; however, a significant LLD has been considered as one of the important reasons for an unsatisfactory outcome.

Research motivation

There is currently no consensus about the extent of LLD that can be considered as clinically relevant following TKA. Again, few studies did not find radiographic LLD as a prognostic factor of functional outcome and stressed upon perceived LLD. Accordingly, the available studies were searched and evaluated in this systematic review and meta-analysis.

Research objectives

The objective of this systematic review was to evaluate the limb lengthening or LLD after TKA. The extent of LLD in varus and valgus deformities and in unilateral and bilateral TKA was also assessed. The impacts of radiographic and perceived LLD on the functional outcome were also evaluated.

Research methods

All randomized controlled trial and observational studies on LLD in TKA, published till 22nd June 2020, were systematically reviewed. The primary outcome was “limb lengthening or LLD after TKA”. The secondary outcomes included “assessment of LLD in varus/valgus deformity” and “impact of LLD on the functional outcome”. Data were analyzed using Review Manager (RevMan). Data were pooled and expressed as MD with 95%CI in case of continuous data. The odds ratio with 95%CI was calculated in categorical data. Inter-study heterogeneity was assessed by Cochrane's Q (χ2 P < 0.10) and quantified by I2. The random MD was calculated to address the high degree of heterogeneity.

Research results

Of 45 studies, qualitative and quantitative assessment of data was performed from eight studies and six studies, respectively. Five studies (n = 1551) reported the average limb lengthening of 5.98 mm. The LLD after TKA was ranging from 0.4 ± 10 mm to 15.3 ± 2.88 mm. The incidence of radiographic LLD after TKA was reported in 44% to 83.3% of patients. There was no difference in preoperative and postoperative LLD (MD -1.23; 95%CI: -3.72, 1.27; P = 0.34). Pooled data of two studies (n = 219) revealed significant limb lengthening in valgus deformity than varus (MD -2.69; 95%CI: -5.11, 0.27; P = 0.03). The pooled data of three studies (n = 611) showed significantly worse functional outcome in patients with LLD ≥ 10 mm compared to < 10 mm (standard MD 0.58; 95%CI: 0.06, 1.10; P = 0.03).

Research conclusions

Limb lengthening after TKA is common, and it is significantly more in valgus than varus deformity. Significant LLD (≥ 10 mm) is associated with suboptimal functional outcome. There is no correlation between radiological LLD and perceived LLD. Patients with perceived LLD are less satisfied, and they usually have a poor functional outcome.

Research perspectives

The arthroplasty surgeon should be aware of the possibility of LLD following TKA, and they should take appropriate measures to avoid significant lengthening. However, more research on perceived LLD can further evaluate its impact on the functional outcome.