International Orthopaedics

, Volume 38, Issue 1, pp 19–25

The deviation of the mechanical leg axis correlates with an increased hip alpha angle and could be a predictor of femoroacetabular impingement

  • Matthias Lahner
  • Nadine-Lucie Jahnke
  • Sonja Zirke
  • Wolfram Teske
  • Gregor Vetter
  • Christoph von Schulze Pellengahr
  • Kiriakos Daniilidis
  • Marco Hagen
  • Lars Victor von Engelhardt
Original Paper

DOI: 10.1007/s00264-013-2085-0

Cite this article as:
Lahner, M., Jahnke, NL., Zirke, S. et al. International Orthopaedics (SICOT) (2014) 38: 19. doi:10.1007/s00264-013-2085-0

Abstract

Purpose

This study was designed to evaluate whether the mechanical axis deviation (MAD) of the leg correlates with an increased hip alpha angle as described by Nötzli, which is associated with femoroacetabular impingement (FAI).

Methods

In a retrospective analysis, standing full-length anteroposterior radiographs were analysed in patients who suffered from symptomatic leg alignment. The study included 85 radiographs of 80 patients with an average age of 43.11 years (range 18–60 years). Five patients underwent a bilateral long-leg X-ray examination. All radiographs were transferred as Digital Imaging and Communications in Medicine data files from the Picture Archiving and Communications System into the OrthoPlanner software version 2.3.2. The radiographs were measured by one orthopaedic surgeon and one independent radiologist.

Results

The mean value of the alpha angle of Nötzli was 61.43° (49.07–74.04°). A total of 57 (67 %) radiographs showed a varus deviation, 25 (29.5 %) had a valgus malalignment and three (3.5 %) a straight leg axis. Of 82 radiographs, 40 (48.8 %) had a moderate axis deviation with a MAD <15 or > − 15 mm and a mean alpha angle of 57.81°, and 42 (51.2 %) with extended axis deviation of a MAD > 15 or < − 15 mm had a mean alpha angle of 62.93°; 40 (95.2 %) of these 42 showed an alpha angle > 55°. The alpha angle was significantly increased in extended axis deviation compared to moderate axis deviation (P = 0.001).

Conclusions

This study confirmed that increased alpha angles were found significantly at higher degrees of axis deviation on the full-length radiograph. In cases of a MAD >15 or < − 15 mm and symptomatic coxalgia, diagnostic tests must be pursued for FAI.

Keywords

Alpha angle of NötzliFull-length radiographMechanical axis deviationFemoroacetabular impingementHip arthrosis

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Matthias Lahner
    • 1
  • Nadine-Lucie Jahnke
    • 2
  • Sonja Zirke
    • 3
  • Wolfram Teske
    • 3
  • Gregor Vetter
    • 3
  • Christoph von Schulze Pellengahr
    • 3
  • Kiriakos Daniilidis
    • 4
  • Marco Hagen
    • 5
  • Lars Victor von Engelhardt
    • 6
  1. 1.Department of Orthopaedic Sports Surgery, St. Josef-HospitalRuhr University BochumBochumGermany
  2. 2.Department of Diagnostic and Interventional Radiology and Nuclear Medicine, St. Josef-HospitalRuhr University BochumBochumGermany
  3. 3.Department of Orthopaedic Surgery, St. Josef-HospitalRuhr University BochumBochumGermany
  4. 4.Department of Orthopaedic SurgeryAnnastift Hannover (Medical School Hannover, MHH)HannoverGermany
  5. 5.Biomechanics Laboratory Department of Sport and Movement SciencesUniversity of Duisburg-EssenEssenGermany
  6. 6.Faculty of Health SciencesUniversity of Witten/HerdeckeWittenGermany