Introduction
Cancellous autografts- The transplantation of patient-derived cancellous bone in order to promote new bone formation by providing live bone cells and growth factors. Little structural support is gained using this type of graft. Cancellous grafts are most commonly obtained from the proximal humerus.
- These grafts contain a mixture of cortical and cancellous bone and are commonly obtained from the wing of the ilium or by utilizing a resected rib.
- Used in advanced orthopedic surgery to augment fracture repair of a bone with severe cortical bone loss, or in limb-sparing procedures for neoplastic or cystic bone disease. Their primary role is structural support.
Seek specialist referral if this procedure is contemplated.
Uses
- Fracture repair especially:
- Revision surgeries because of delayed or non-union, or instability.
- Highly comminuted fractures.
- Where infection is present (osteomyelitis
). - Where rapid healing is desired, eg when external fixator implant loosening may occur after some weeks.
- Toy breeds and older patients with poor healing potential.
- Generally, all fractures will heal more quickly if they are grafted - bone healing may be accelerated by as much as 4 weeks.
Other uses
- Arthrodesis procedures .
- Filling defects left after currettage of bone cysts .
- In the support of cortical deficits, eg following resection of neoplasia during limb-sparing procedures.
Advantages
- Cancellous bone grafts speed healing by the processes of:
- Osteogenesis (up to 60% of transplanted cells may be viable and will rapidly begin production of new bone).
- Osteoinduction (osteoprogenitor cells are induced to transform into osteoblasts at the recipient site, which can then produce new bone. This process occurs more slowly then osteogenesis).
- Osteoconduction (the graft provides a scaffold for local bone invasion).
- Cortical bone grafts act mainly by providing structural/mechanical support; they have little osteoinductive properties.
- Corticocancellous grafts provide elements of both osteoinduction and osteoconduction.
Disadvantages
- Donor site morbidity and lameness.
- Hemorrhage or seroma if inadequate closure.
- Collecting a graft adds to the surgical time, and requires preparation and surgery at a remote site, with fresh instruments and drapes.
- Volume of graft available is limited.
- Iatrogenic fracture at the donor site is a rare complication.
Preparation
- 10 min.
Requirements
Materials required
Minimum equipment
- Standard surgical pack, with second smaller pack (and drapes) for graft donor site.
- Gelpi retractors.
- Jacob's chuck or electrical or air-powered drill.
- Osteotome and hammer (for ilium site).
- Intramedullary pin or drill bit appropriate for the patient's bone size and slightly larger than the size of the curette.
- Bone curette.
Ideal equipment
- Stainless steel cup/container to temporarily store the graft while the donor site is closed.
Sequelae
Complications
- Long-term complications from bone grafting are rare.
Prognosis
- Depends on the procedure which required the bone graft.
Sources
Publications
- Recent references from PubMed.
- Palmisano M P & Schroder S C (1999) Premature closure of the proximal physis of the humerus in a dog as a result of harvesting a cancellous bone graft. JAAMA 215 , 1460-1462.
- Fitch R & Kerwin S (1998) Bone autografts and allografts in dogs. Comp Cont Educ Pract Vet 19 , 558-576.
- Heiner J P, Kohles S S, Manley P A, Vanderby R Jr & Markel M D (1997) Stability of proximal femoral grafts in canine hip arthroplasty. Clin Orthop 341 , 233-240.
- Miclau T, Lindsey R W, Probe R, Rahn B A & Perren S M (1996) Autogenous cancellous bone graft incorporation in gap defect in the canine femur. J Orthop Trauma 10 (2), 108-113.
- Johnson K D, August A, Sciadini M F & Smith C (1996) Evaluation of ground cortical autograft as a bone graft material in a new canine bilateral segmental long bone defect model. J Orthop Trauma 10 (1), 28-36.
- Parker R B (1995) Bone grafting in small animal surgery. Waltham Focus 5 , 9-14.
