Systematic Reviews
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. May 18, 2017; 8(5): 431-435
Published online May 18, 2017. doi: 10.5312/wjo.v8.i5.431
Effect of lengthening along the anatomical axis of the femur and its clinical impact
Khaled M Emara, Ahmed Nageeb Mahmoud, Ahmed K Emara, Mariam K Emara
Khaled M Emara, Ahmed Nageeb Mahmoud, Ahmed K Emara, Mariam K Emara, Limb Reconstruction and Deformity Correction Unit, Orthopaedic Surgery Department, Ain Shams University Hospitals, Cairo 11566, Egypt
Author contributions: Emara KM contributed to study design; Mahmoud AN contributed to literature review, research, manuscript design and writing; Emara AK contributed to writing and research; Emara MK contributed to calculation, mathematical engineering and illustrations.
Conflict-of-interest statement: The authors declare that there are no conflicts of interest related to this research.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (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: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Khaled M Emara, Professor, Limb Reconstruction and Deformity Correction Unit, Orthopaedic Surgery Department, Ain Shams University Hospitals, 13 B Kornesh EL Nile, Agha Khan, Cairo 11566, Egypt. kmemara@hotmail.com
Telephone: +20-22-2055661 Fax: +20-22-2055662
Received: November 7, 2016
Peer-review started: November 10, 2016
First decision: February 15, 2017
Revised: March 4, 2017
Accepted: March 16, 2017
Article in press: March 17, 2017
Published online: May 18, 2017
Processing time: 186 Days and 11.8 Hours
Abstract
AIM

To review and study the effect of lengthening along the anatomical axis of long bones and its relation to the mechanical axis deviation.

METHODS

We try in this review to calculate and discuss the exact clinical impact of lengthening along the anatomical axis of the femur on affecting the limb alignment. Also we used a trigonometric formula to predict the change of the femoral distal anatomical mechanical angle (AMA) after lengthening along the anatomical axis.

RESULTS

Lengthening along the anatomical axis of the femur by 10% of its original length results in reduction in the distal femoral AMA by 0.57 degrees. There is no objective experimental scientific data to prove that the Mechanical axis is passing via the center of the hip to the center of the knee. There is wide variation in normal anatomical axis for different populations. In deformity correction, surgeons try to reproduce the normal usual bone shape to regain normal function, which is mainly anatomical axis.

CONCLUSION

Lengthening of the femur along its anatomical axis results in mild reduction of the distal femoral AMA. This may partially compensate for the expected mechanical axis lateralisation and hence justify its minimal clinical impact.

Keywords: Bone lengthening; Deformity; Femoral lengthening; External fixation; Intramedullary nail; Axis deviation

Core tip: In deformity correction the aim is to reproduce the normal anatomical shape of the bone to regain normal function. There is no experimental data to prove the passage of the imaginary mechanical axis and load distribution of the body via the center of the hip to the center of the knee. Lengthening along anatomical axis of the bone is expected to cause minimal or no clinical effect on mechanical axis and load distribution on joints.