How the pemberton innominate osteotomy really works: an animal study

Area of Science:

• Orthopedic surgery
• Pediatric orthopedics
• Hip dysplasia

Background:

• The Pemberton innominate osteotomy is a common surgical procedure for hip dysplasia.
• It is believed to improve acetabular coverage by hinging at the triradiate cartilage, altering acetabular volume.
• The precise mechanism and volumetric changes remain debated.

Purpose of the Study:

• To identify the exact site of hinging at the triradiate cartilage during a Pemberton osteotomy.
• To quantify any changes in acetabular volume following the procedure.
• To clarify the mechanism by which the Pemberton osteotomy improves acetabular coverage.

Main Methods:

• Pemberton innominate osteotomies were performed on six immature pig innominate bones under fluoroscopic guidance.
• The site of hinging at the triradiate cartilage was visually identified during the surgery.
• Acetabular dimensions were measured before and after the osteotomy to assess volume changes.

Main Results:

• Hinging was consistently observed at the extra-articular portion of the ilioischial limb of the triradiate cartilage.
• No significant alteration in acetabular volume was detected after successful osteotomies.
• Femoral head coverage improved due to acetabular redirection, not shape modification.

Conclusions:

• The Pemberton osteotomy improves hip coverage by repositioning the acetabulum.
• The procedure does not alter acetabular volume; hinging occurs extra-articularly.
• Understanding the mechanism clarifies the benefits of this orthopedic procedure for hip dysplasia.