Introduction

Patients with childhood hip disorders (CHDs) and developmental dysplasia of the hip (DDH), particularly those with high-riding hip dislocations, often present with bone defects in both the acetabulum and proximal femur [1,2]. In Crowe type IV DDH, the acetabulum is characterized by a small, shallow cavity with deficient superolateral acetabular bone stock [3], making it difficult to achieve adequate coverage and stability with standard hemispherical cups [4]. Although acetabular bone defects can be managed using several reconstruction techniques [5], total hip arthroplasty (THA) in severe dysplastic hips remains technically challenging and is often associated with unsatisfactory outcomes. In extremely severe cases, THA may not be feasible [6,7]. Recent studies indicate good surgical outcomes after the use of customized acetabular cups in patients with DDH with acetabular bone defects [8,9]. However, most of these implants are either custom augments or cups with iliac flanges aimed at improving acetabular cup fixation rather than reconstructing the underlying acetabular bone defect [10-12].

The proximal femur in CHD and DDH often exhibits severe anatomical deformation, making standard off-the-shelf stems difficult to use [13]. Surgical techniques such as subtrochanteric osteotomy can sometimes facilitate conventional stem use but carry an increased risk of intraoperative and postoperative fractures [14,15]. In extreme cases, femoral splitting may be required [16].

Literature on THA using custom-made femoral stems in severely deformed proximal femurs remains scarce [17-19]. To our knowledge, no study has specifically reported the use of a custom stem in cases where the femoral canal was too narrow and the femur too slender to accommodate any standard implant, regardless of stem geometry or offset options. This represents a distinct clinical scenario, as narrow femoral canals pose unique challenges related to stem sizing and fit.

No part of this work has been previously presented at any conference, meeting, or symposia, nor has it been published as an abstract or poster.