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01-10-2016 | Original Paper

Morphologic and angular planning for cam resection in femoro-acetabular impingement: value of the omega angle

Authors: Paulo Renato Amaral Rego, Vasco Mascarenhas, Filipe S. Oliveira, Pedro C. Pinto, Augusto Gaspar, Joana Ovídio, Diego G. Collado

Published in: International Orthopaedics | Issue 10/2016

Abstract

Purpose

The alpha angle is used to quantify in a single plane the head–neck junction deformity of cam femoro-acetabular impingement (FAI). When the deformity overlaps the superior retinaculum, femoral head osteoplasty in this area can jeopardise intra-articular vascular structures. This study proposes a new angular measure of the linear radial extension of cam deformity as a planning tool for bone resection and compares the accuracy of femoral head osteoplasty using open and arthroscopic surgery.

Methods

Twenty-five symptomatic patients operated on for FAI were included in this study. Radial magnetic resonance imaging (MRI) was done before and after surgery. Bi-dimensional coordinates of the vascular foramina and radial extension of the deformity (omega angle) were measured. This extension was correlated with the vascular foramina location and alpha-angle value. Accuracy of resection and hip function were evaluated before and after surgery.

Results

The cam lesion frequently extended posteriorly. No relation between values of alpha and omega angles was found. Cam resection was complete in 88 % of cases; there was a significant improvement in outcome score after surgery.

Conclusions

This study showed that alpha angle, measured in one plane, was not a predictor of the radial extension of cam deformity. To achieve a full resection, it was frequently necessary to extend the femoral head osteoplasty over the retinacular area. Pre-operative determination of the omega angle and location of the vascular foramina helped improve cam resection safety and accuracy.

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Title: Morphologic and angular planning for cam resection in femoro-acetabular impingement: value of the omega angle
Authors: Paulo Renato Amaral Rego
Vasco Mascarenhas
Filipe S. Oliveira
Pedro C. Pinto
Augusto Gaspar
Joana Ovídio
Diego G. Collado
Publication date: 01-10-2016
Publisher: Springer Berlin Heidelberg
Published in: International Orthopaedics / Issue 10/2016
Print ISSN: 0341-2695
Electronic ISSN: 1432-5195
DOI: https://doi.org/10.1007/s00264-015-3053-7

At a glance: The ONWARDS insulin icodec trials

Springer Medicine

Morphologic and angular planning for cam resection in femoro-acetabular impingement: value of the omega angle

Abstract

Purpose

Methods

Results

Conclusions

At a glance: The ONWARDS insulin icodec trials

Springer Medicine

Abstract

Purpose

Methods

Results

Conclusions

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