Advertisement

Surgical and Radiologic Anatomy

, Volume 35, Issue 2, pp 131–135 | Cite as

Radiological landmarks for the safe extra-capsular placement of supra-acetabular half pins for external fixation

  • Surjit Lidder
  • Nima HeidariEmail author
  • Axel Gänsslen
  • Wolfgang Grechenig
Anatomic Bases of Medical, Radiological and Surgical Techniques

Abstract

Purpose

Low anterior external fixators are constructed by placing half pins in the dense bone tunnel of the supra-acetabular region in an anterior to posterior direction. Although the placement of these pins is extra-articular, they may still breach the hip capsule on the anterior inferior iliac spine and thus be intra-capsular. We aim to provide radiological markers for the most superior fibres of the capsule to allow safe extra-capsular pin placement within the supra-acetabular bone tunnel.

Methods

Thirteen cadaveric pelves were used for this study. The supra-acetabular bone tunnel was visualised with an image intensifier. The proximal most fibres of the hip joint capsule were marked with a K-wire so that their relation to the bone tunnel could be clearly seen on the images. Once all images were acquired they were calibrated and analysed to estimate the dimensions of the supra-acetabular bone tunnel and the reflection of the hip capsule.

Results

The median height of the bone tunnel was 23.6 mm (18.9–33.2) and maximum width was 11.4 mm (7.6–16.3). The inferior margin of the bone tunnel was 6.7 mm (1.1–14.5) superior to the acetabular dome, and the most proximal fibres of the capsule were 9.3 mm (4.7–6.1) superior to the acetabular dome. The inferior portion of the tunnel was 3.7 mm (0.3–8.9) within the joint.

Conclusion

Half pins for the construction of a pelvic external fixator should be placed in the upper half of the supra-acetabular bone corridor to minimise the risk of intra-capsular placement.

Keywords

Supra-acetabular External fixator Low anterior Pelvis fracture Radiological landmarks 

Notes

Conflict of interest

The authors declare that they have no conflict of interest.

References

  1. 1.
    Brown S, Lasrado I, Donnan L (2007) Peri-acetabular external fixation for hip disease: an anatomical study. Strateg Trauma Limb Reconstr 2:69–75CrossRefGoogle Scholar
  2. 2.
    Haidukewych GJ, Kumar S, Prpa B (2003) Placement of half-pins for supra-acetabular external fixation: an anatomic study. Clin Orthop Relat Res 411:269–273PubMedCrossRefGoogle Scholar
  3. 3.
    Judd KT, McKinley TO (2009) Septic arthritis of the hip associated with supra-acetabular external fixation of unstable pelvic ring: a case report. Iowa Orthop J 29:124–126PubMedGoogle Scholar
  4. 4.
    Kim WY, Hearn TC, Seleem O, Mahalingam E, Stephen D, Tile M (1999) Effect of pin location on stability of pelvic external fixation. Clin Orthop Relat Res 361:237–244PubMedCrossRefGoogle Scholar
  5. 5.
    Mason WT, Khan SN, James CL, Chesser TJ, Ward AJ (2005) Complications of temporary and definitive external fixation of pelvic ring injuries. Injury 36:599–604PubMedCrossRefGoogle Scholar
  6. 6.
    Palmer S, Fairbank AC, Bircher M (1997) Surgical complications and implications of external fixation of pelvic fractures. Injury 28:649–653PubMedCrossRefGoogle Scholar
  7. 7.
    Schildhauer TA, McCulloch P, Chapman JR, Mann FA (2002) Anatomic and radiographic considerations for placement of transiliac screws in lumbopelvic fixations. J Spinal Disord Tech 15:199–205PubMedCrossRefGoogle Scholar
  8. 8.
    Thiel W (1992) The preservation of the whole corpse with natural color. Ann Anat 174:185–195PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Surjit Lidder
    • 1
  • Nima Heidari
    • 2
    Email author
  • Axel Gänsslen
    • 3
  • Wolfgang Grechenig
    • 4
  1. 1.Eastbourne District General HospitalEast SussexUK
  2. 2.Limb Reconstruction UnitBristol Royal InfirmaryBristolUK
  3. 3.Klinik für Unfallchirurgie, Orthopädie Und HandchirurgieKlinikum Der Stadt WolfsburgWolfsburgGermany
  4. 4.Department of TraumatologyMedical University of GrazGrazAustria

Personalised recommendations