Histological differences in iliac and tibial bone graft

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Histology

Background:

• Cancellous bone graft is essential in orthopedic procedures.
• The iliac crest is a traditional donor site, with the proximal tibia as an alternative, particularly for foot and ankle surgeries.
• Histologic differences between iliac crest and tibial bone grafts are not well-established.

Purpose of the Study:

• To compare the histologic composition of cancellous bone grafts from the iliac crest and proximal tibia.
• To evaluate the cellular content, specifically active hematopoietic marrow versus fatty marrow, in bone grafts from these two sites.
• To determine if the histologic characteristics of iliac and tibial bone grafts differ significantly.

Main Methods:

• Histologic examination of bone specimens from the iliac crest (n=10) and proximal tibia (n=10).
• Samples were harvested from the anterior iliac crest and Gerdy's tubercle region of the tibia.
• Grafts were graded based on the percentage of bone surfaces opposing active hematopoietic marrow (Grade I to VI).

Main Results:

• Both iliac crest and tibial bone grafts exhibited trabecular fragments with osteocytes.
• All iliac crest grafts contained abundant active hematopoietic marrow.
• Tibial grafts predominantly contained fatty marrow with minimal hematopoietic activity, receiving low histological grades (I or II) compared to iliac grafts (V or VI).

Conclusions:

• Iliac bone grafts are characterized by active hematopoietic marrow, while tibial bone grafts are primarily composed of quiescent medullary fat.
• These distinct cellular compositions suggest varying contributions to bone healing, questioning the equivalence of different bone graft sources.
• Findings highlight the importance of donor site selection based on graft cellularity for optimal orthopedic outcomes.