Marín-Peña, OliverAyeni, Olufemi R.Tey Pons, MarcosMas-Martinez, JesúsDantas, PedroKhanduja, Vikas2022-03-212022-03-212021Marín-Pena O, Ayeni OR, Tey-Pons M, Mas-Martinez J, Dantas P, Khanduja V. The case of 'A Rhino Horn': case report and proposal for modification to the Hetsroni and Kelly classification. J Hip Preserv Surg. 2021 Jun 23;8(Suppl 1):i51-i59. DOI: 10.1093/jhps/hnab0202054-8397http://hdl.handle.net/10230/52724Subspine impingement syndrome by definition involves a prominent antero-inferior iliac spine (AIIS) which can lead to impingement on the femoral neck thereby causing symptoms. We present the case of a 22-year-old semi-professional athlete who presented with a Type III AIIS morphology leading to subspine impingement syndrome and was managed via a mini open anterior approach. Radiological examination revealed a fairly prominent left AIIS resembling the 'horn of a rhino' extending to the trochanteric region anteriorly. A mini-anterior surgical approach was utilized for the resection of the 'rhino horn' and the rectus femoris was reattached. The patient remained asymptomatic at the one-year follow-up and had resumed weightlifting. Following this case, we propose a new classification of the type III AIIS morphology in view of the clinical presentation. The AIIS type III-Standard represents an extension from the acetabular rim to less than 1 cm (type III-S) and type III-Large, with an extension from the acetabular rim beyond 1 cm (type III-L). The type III-L will further be divided into two groups based on its relation to the ilium, type III-Lr ('rib shape') and type III-Lrh ('rhino horn').application/pdfeng© The Author(s) 2021. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.cominfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1093/jhps/hnab020Magnetic resonance imagingNeck of femurFollow-upHip regionHip jointHornsIliumReconstructive surgical proceduresSurgical proceduresOperativeRectus femoris muscleAthleteAcetabular rimIliac spineinfo:eu-repo/semantics/openAccess