New paper in VCOT Journal: Fluoroscopic Categorization of Cementless Acetabular Component Positioning

A new study that was presented by Peter M Sadowitz, (Tufts University, United States) at the online AO VET Clinical Research Symposium in December 2021 has been published in the February 2023 issue of the Veterinary and Comparative Orthopaedics and Traumatology (VCOT) journal.

Sadowitz was an intern when he started the research and today is a resident in small animal surgery at Tufts University’s Cummings School of Veterinary Medicine. He is mentored by AO VET members William M Karlin and Michael P Kowaleski, who are members of the vet school’s faculty.

Read Simon Roe's summary of the study:

Fluoroscopic assessment of BFX cup position

In total hip replacement, luxation of the prosthetic joint is one of the more common complications and incorrect cup positioning; in particular, angle of lateral opening (AOL), may be a contributing factor. Visual intraoperative assessment of cup position is the usual approach but may not be accurate if the patient’s pelvis is not truly “square.” Sadowitz et al hypothesized that a plus or minus 10-degree AOL malposition of a BFX cup could be assessed by observation of the shape of the circular recess at the apex of the metal shell of the cup using simulated intraoperative fluoroscopic images. Reference images for 35, 45, and 55 degrees of AOL, with standard version and inclination, were created. These were used to categorize 30 randomized images in blinded fashion. An untrained, inexperienced investigator was able to identify all images with 100 percent accuracy. Applying this approach in a clinical patient increases surgeon confidence that the cup is accurately positioned. This will be particularly helpful when normal acetabular anatomy is lost due to extensive wear or obscured by peri- and intraarticular osteophyte development. The image intensifier is adjusted to ensure that the beam is oriented perfectly lateral (hemi-pelvis superimposition), thus allowing a confident assessment of AOL. For most surgeons, malpositioning by 10 degrees would be considered excessive, and an adjustment to a more optimal AOL would be performed.