Using Imageless Optical Navigation to Identify the New Hip Center in Crowe IV Dysplasia

In total hip arthroplasty for patients with acetabular dysplasia, cup placement in the native acetabulum is preferred to placement in the pseudoacetabulum. Identifying the true acetabulum may prove challenging. In a patient with Crowe IV dysplasia, 3-dimensional mini-optical navigation was used to match the new hip center to the preoperative radiographic plan, which was identified to be 34 mm inferior to the pseudoacetabulum. This allowed titration of femoral shortening to 20 mm, to arrive at final limb lengthening of 14 mm. Although the use of other enabling technologies in hip dysplasia has been reported, to the authors' knowledge, this is the first reported case demonstrating the use of imageless optical navigation in this setting. It is a navigational tool with a small spatial footprint, does not mandate preoperative axial studies, and does not require multipoint bone surface registration. Imageless navigation may be a useful option for cup positioning and subsequent titration of femoral shortening in the reconstruction of Crowe IV dysplastic hips with degenerative joint disease. [Orthopedics. 2020; 43(2):e119-e122.].