This is a plain-English translation of the academic paper above, prepared for patients, referring clinicians, and other non-specialist readers. It preserves the structure of the original paper while removing technical jargon. For the full clinical paper, follow the PubMed or DOI links.
Background
How to place the metal pins of a pelvic external-fixator frame — used to stabilise a broken pelvis — into the dense bone above the hip socket without accidentally entering the hip joint capsule itself.
Rationale
A pin that crosses into the hip joint capsule risks introducing infection and damaging the joint surface. The bone tunnel surgeons aim for is short, narrow, and very close to the joint — so a small misjudgement can have serious consequences.
Results
Across 13 cadaveric pelvises with the pin position checked under x-ray, the safe bone tunnel above the hip socket was on average 24 mm tall and 11 mm wide. The most upper fibres of the hip joint capsule sat about 9 mm above the dome of the socket — meaning the lower part of the bone tunnel was inside the capsule. Pins placed in the upper half of that tunnel stayed outside the joint.
Implications
For a patient having an emergency pelvic frame applied, this is a small but important technical detail: the pins should be placed in the upper half of the available bone corridor, guided by clear x-ray landmarks, to keep them safely outside the hip joint and so reduce the risk of joint infection.
Source: Lidder S, Heidari N, Gänsslen A, Grechenig W. Radiological landmarks for the safe extra-capsular placement of supra-acetabular half pins for external fixation. Surgical and Radiologic Anatomy 2013;35(2):131-5. doi:10.1007/s00276-012-1016-x
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