Measure Twice, Cut Once? Depends on the Software!

Software has become the boon or boondoggle for orthopedic surgeons. For the first time, in our experience, we found a head-to head-study pitting one commonly used software program with another. (If there are others, please make sure you send them to us).

In this case, a Canadian research team compared Clinical Graphics software with Hip²Norm and did so by using both to measure the percentage of femoral head coverage (%FHC) which is a measurement that is used to help classify a patient’s morphology and, therefore, offer a sense of how outcomes might go after hip preservation surgery.

The study, “Comparison of Acetabular Measurements Between 2 Validated Software Programs Used in Hip Preservation Surgery,” was published online on July 22, 2022 in The American Journal of Sports Medicine.

The research team also wanted to determine which parameters influence the correlation or differences between software outputs and measurements.

Data was collected from 69 patients who had been treated with periacetabular osteotomy. The research team used both software programs, Clinical Graphics and Hip²Norm, to measure lateral center-edge angle, acetabular index and %FHC.

They then segmented images of 18 pelvises and measured spinopelvic parameters and subtended acetabular angles. They also defined the differences in the outputs of the two programs as delta (Δ). Finally, the team tested radiographic parameters to assess whether they were responsible for differences in %FHC between software programs.

The research group found strong correlations between LCEA (p = 0.862) and AI (p = 0.825) measurements with both software programs. They however also found a weak correlation was seen in the estimate of %FHC (p = 0.358).

The team wrote, “Hip²Norm consistently produced lower anterior, posterior, and total %FHC values than Clinical Graphics. The %FHC determined by Clinical Graphics, but not Hip²Norm, correlated with acetabular subtended angles (p < .05).”

“Pelvic tilt measured on CT did not correlate with pelvic tilt estimated by Hip²Norm (p = .56), and ΔPelvicTilt strongly correlated with the difference in %FHC by the two software programs (ρ = 0.63; p = .005), pelvic incidence (ρ = 0.73; p < .001), and pelvic tilt (ρ = −0.91; p < .001) as per CT.”

“The %FHC determined by Clinical Graphics strongly correlated with the segmented acetabular subtended angles and thus more likely reflected true values. Hip preservation surgeons should be aware of these measurement differences because %FHC is important in the diagnosis and prognosis of acetabular dysplasia.”

The study authors include Pierre Laboudie, M.D., Cochin Hospital, Paris, France and The Ottawa Hospital, Ottawa, Ontario, Canada; Daniel Fischman, M.D., Hospital Militar, Santiago, Chile; Andrew D. Speirs, Ph.D., Carleton University, Ottawa, Ontario, Canada; Saif Salih, M.A., M.D., Northern General Hospital, Sheffield, United Kingdom; Fernando Holc, M.D. Italian Hospital of Buenos Aires, Buenos Aires, Argentina; Paul E. Beaule, M.D., The Ottawa Hospital, Ottawa, Ontario, Canada; Johan D. Witt, M.D., University College London Hospitals, London, United Kingdom; and George Grammatopoulos, MBBS, DPhil., The Ottawa Hospital, Ottawa, Ontario, Canada.