Abstract
Background:
Septic arthritis following intra-capsular penetration of the knee by external fixation devices is a complication of traction/fixation devices. This study aimed to demonstrate the capsular attachments and reflections of the distal femur to determine safe placements of wires.
Methods:
The attachments of the capsule to the distal femur were measured in cadaveric knees. Medially and laterally measurements were expressed as percentages related to the maximal AP diameter of the distal femur.
Results:
Mean distance of the anterior attachment was 79.5mm (Range 48.1–120.7mm). The medial capsular reflections were attached an average of 57% back from the anterior edge (Range 41–74%). Laterally the capsular reflections were attached an average of 48% from the anterior reference point (Range 33–57%).
Discussion:
Capsular reflections varied. Medially the capsule attachment was up to 74% of diameter of distal femur at the level of the adductor tubercle. Therefore, the insertion of distal femoral traction pins or similar should be placed proximal to the adductor tubercle and no further than 25% of the distance to the anterior cortex. Care is needed to ensure pins do not travel to exit too anteriorly on the lateral side as capsular attachments were found to be up to a distance 48% of the diameter of the femur from anterior reference point.
