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1068.e2 Bone Grafting

Bone Grafting
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sites from which cancellous bone grafts are col-
Difficulty level: ♦♦
lected in companion animals are the proximal ○ Iliac crest: a hole can be made on its dorsal
surface, or a small section of dorsal crest
Synonyms humerus, iliac crest (especially in cats), and cortex can be removed with rongeurs to
Cancellous autografts, corticocancellous grafts, proximal tibia, although the femoral condyle expose cancellous bone.
allografts can also be used. • Use a small Steinmann pin to make a hole
through just one cortex at the selected
Overview and Goal Indications site. This hole should be kept small (see
Bone grafting is done to stimulate healing of • Fractures in older animals and others with Complications).
fractures, osteotomies, and areas of bone loss, diminished healing capacity • Scoop cancellous bone out of the metaphysis
especially when conditions are unfavorable for • Fractures with gaps through the approach hole and collect it in
union. • Limb-sparing and bone replacement a blood-soaked sponge.
Bone grafts work through a combination procedures • The approach hole can be plugged with a
of strategies: • Delayed unions and nonunions piece of foam gelatin or a small bit of muscle
• Osteogenesis: transfer of bone-forming cells if it is bleeding.
into the defect Contraindications • Donor site closure is routine.
• Osteoinduction: provision of growth factors Grafting is generally unnecessary in young • Pack the graft into gaps and defects of the
and cytokines to call mesenchymal stem cells animals and in bones with a good blood supply fracture rather than around the cortex.
and progeny into the area and then stimulate and a high proportion of cancellous bone, such
them to become bone-forming cells as the ilium or scapula. Postprocedure
• Osteoconduction: provision of a matrix to • Seromas may be seen at the donor site.
guide vascular ingrowth and provide surfaces Equipment, Anesthesia • A periosteal bump may become palpable over
on which bone-forming cells can proliferate • General anesthesia iliac donor sites.
and lay down the components of bone • Jacobs chuck and Steinmann pins • Radiograph: to look for fracture if acute
• Early support: bone grafts that include solid • Small (00 and smaller) bone curettes; House lameness occurs in a donor-site limb
sections of cortex or strong bone substitute curette
also contribute to physical stability of the • Sterile Petri dish or small bowl in which to Alternatives and Their Relative
bone during the early healing phase. store the graft Merits
Bone grafts come in a number of different • Injection of bone marrow may stimulate
forms: Anticipated Time bone healing in delayed unions.
• Cancellous or corticocancellous grafts are 15-20 minutes • Autogenous cancellous grafts may be
the most commonly used grafts in veterinary extended by mixing them with blood,
medicine. They are typically harvested from Preparation: Important allograft, or bone substitute material.
another bone in the same patient at the time Checkpoints • Bone growth factors contained in a matrix
of fracture repair surgery, although preserved Instruments and gloves should be kept separate can be used but remain expensive.
cancellous allografts are commercially avail- between the fracture and donor sites to prevent
able. Cancellous autografts provide living bacteria (or neoplastic cells) from being trans- Pearls
cells, growth factors, and bony trabeculae to ferred to the donor site. • It is helpful to use a synthetic sponge for
serve as matrices for bone formation. They do temporary storage because graft material can
not provide physical support for the fracture Possible Complications and get lost in the weave of gauze sponges.
repair. Common Errors to Avoid • Use blood to keep the graft moist because
• Cortical or corticocancellous grafts can • Bone graft is typically collected into a saline solution is mildly acidic and can
provide mechanical support and transfer blood-moistened sterile sponge. This sponge promote osteoclast death.
some growth factors, but they provide should be marked and separated from the
fewer bone-forming cells (none if preserved instruments to avoid having it thrown away SUGGESTED READING
allografts are being used). Ribs and sections inadvertently. Kraus KH, et al: Bone grafts and substitutes. In
of the iliac crest are the most common • The donor hole should be placed in the Johnston SA, et al, editors: Veterinary surgery small
sources of corticocancellous autografts, metaphysis and should not be more than animal, ed 2, St. Louis, 2018, Elsevier, pp 783-792.
although occasionally, a section of ulna or 20% of the diameter of the bone at that
fibula is used. location; otherwise, iatrogenic fracture may ADDITIONAL SUGGESTED
• A variety of bone substitutes are available for occur. READINGS
use, including tricalcium phosphate, coral, Verboket R, et al: Autologous cell-based therapy
bioglass, and other scaffolds; growth factors Procedure for treatment of large bone defects: from bench
such as bone morphogenetic proteins may • Make a small approach to the donor site to bedside. Eur J Trauma Emerg Surg 2018.
be added. and expose 1-2 cm of the bone surface. https://link.springer.com/article/10.1007/s00068
Because autogenous cancellous bone grafting ○ Humerus: craniolateral surface of the -018-0906-y#Bib1/.
is the most commonly used technique in small greater tubercle AUTHOR: Kathleen Linn, DVM, MS, DACVS
animals, the guideline that follows describes ○ Tibia: medial metaphysis just caudal to EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
its harvest and placement. The most common the tibial tubercle Thompson, DVM, DABVP

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