Clinical Orthopaedics and Related Research: July 2010 - Volume 468 - Issue 7 - p 1862–1868 doi: 10.1007/s11999-009-1086-1 BASIC RESEARCH

Leg Length and Offset Measures with a Pinless Femoral Reference Array during THA

Renkawitz, Tobias, MD1, 4, a; Schuster, Tibor2; Grifka, Joachim, MD, PhD1; Kalteis, Thomas, MD, PhD3; Sendtner, Ernst, MD1

The bony fixation of reference marker arrays used for computer-assisted navigation during total hip arthroplasty (THA) theoretically involves the risk of fracture, infection, and/or pin loosening. We asked whether intraoperative assessment of leg length (LL) and offset (OS) changes would be accurate using a novel pinless femoral reference system in conjunction with an imageless measurement algorithm based on specific realignment of the relationship between a dynamic femoral and pelvis reference array. LL/OS measurements were recorded during THA in 17 cadaver specimen hips. Preoperatively and postoperatively, specimens were scanned using CT. Linear radiographic LL/OS changes were determined by two investigators using visible fiducial landmarks and image processing software. We found a high correlation of repeated measurements within and between (both 0.95 or greater) the two examiners who did the CT assessments. Pinless LL/OS values showed mean differences less than 1 mm and correlations when compared with CT measurements.

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