Shelf acetabuloplasty may inhibit range of motion: A computer simulation analysis

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Hip joint biomechanics

Background:

• Shelf acetabuloplasty is a surgical procedure for developmental dysplasia of the hip (DDH).
• Determining the optimal shelf position to avoid range of motion (ROM) loss remains a challenge.
• Iatrogenic impingement can occur if the shelf is not optimally positioned.

Purpose of the Study:

• To investigate the frequency of ROM inhibition after shelf acetabuloplasty.
• To analyze the influence of the 3D shelf position on ROM.
• To identify predictors of ROM inhibition using computer simulation.

Main Methods:

• Computed tomography (CT) data from 15 DDH patients were used.
• Three-dimensional hip joint models were created using Zed Hip® software.
• Maximal internal rotation (MIR) was measured, and virtual surgeries were performed to test different shelf positions (height, inclination, center-edge angle, anteroposterior position).

Main Results:

• A significant limitation of MIR was observed in 60% (90° flexion) and 66.7% (45° flexion) of patients in the postoperative model.
• A higher center-edge angle (CEA) and an anterior shelf position were identified as major predictors of limited MIR.
• Virtual surgery analysis confirmed that anterior position and CEA significantly contribute to ROM inhibition.

Conclusions:

• The study identified specific shelf positions that lead to iatrogenic impingement and ROM limitation.
• Findings indicate the optimal shelf location to minimize ROM loss after shelf acetabuloplasty.
• This research provides valuable insights for surgeons to improve surgical outcomes in DDH patients.