Novel CT based 2021 ARCO Classification for Osteonecrosis of the Femoral Head

Written By : Dr Supreeth D R |Medically Reviewed By : Dr. Kamal Kant Kohli Published On 2022-06-24T05:30:14+05:30 | Updated On 24 Jun 2022 11:48 AM IST

The Association Research Circulation Osseous(ARCO) has developed a novel classification for early stage (precollapse) osteonecrosis of the femoral head (ONFH).Kyung-Hoi Koo & Michael A. Mont et al. hypothesized that the novel classification is more reliable and valid when compared to previous 3 classifications: Steinberg, modified Kerboul, and Japanese Investigation Committee (JIC) classifications.

In the novel classification, necrotic lesions were classified into 3 types:

• Type 1 is a small lesion, where the lateral necrotic margin is medial to the femoral head apex;

• Type 2 is a medium-sized lesion, with the lateral necrotic margin being between the femoral head apex and the lateral acetabular edge; and

• Type 3 is a large lesion, which extends outside the lateral acetabular edge.

In a derivation cohort of 40 early-stage osteonecrotic hips based on computed tomography imaging, reliabilities were evaluated using kappa coefficients, and validities to predict future femoral head collapse by chi-squared tests and receiver operating characteristic curve analyses. The predictability for future collapse was also evaluated in a validation cohort of 104 early-stage ONFH.

In the derivation cohort, interobserver reliability (k = 0.545) and intraobserver agreement (63%- 100%) of the novel method were higher than the other 3 classifications.

The novel classification system was best able to predict future collapse (P <.05) and had the best discrimination between nonprogressors and progressors in both the derivation cohort (area under the curve = 0.692 [0.522- 0.863], P < .05) and the validation cohort (area under the curve = 0.742 [0.644-0.841], P = 2.46 x 10-15).

The authors concluded that – the 2021 ARCO classification for early stages of ONFH is more reliable and valid than Steinberg, modified Kerboul, and JIC classifications. ARCO recommends using this novel method for the categorization of early-stage ONFH. Future validating studies involving larger and different patient cohorts are warranted.

MBBS, Dip. Ortho, DNB ortho, MNAMS

Dr Supreeth D R (MBBS, Dip. Ortho, DNB ortho, MNAMS) is a practicing orthopedician with interest in medical research and publishing articles. He completed MBBS from mysore medical college, dip ortho from Trivandrum medical college and sec. DNB from Manipal Hospital, Bengaluru. He has expirence of 7years in the field of orthopedics. He has presented scientific papers & posters in various state, national and international conferences. His interest in writing articles lead the way to join medical dialogues. He can be contacted at editorial@medicaldialogues.in.

Dr. Kamal Kant Kohli

Dr Kamal Kant Kohli-MBBS, DTCD- a chest specialist with more than 30 years of practice and a flair for writing clinical articles, Dr Kamal Kant Kohli joined Medical Dialogues as a Chief Editor of Medical News. Besides writing articles, as an editor, he proofreads and verifies all the medical content published on Medical Dialogues including those coming from journals, studies,medical conferences,guidelines etc. Email: drkohli@medicaldialogues.in. Contact no. 011-43720751