■ Review Article cme ARTICLE Earn Category 1 credits Bone Transplantation AMY WILLIAMS, MD; ROBERT M. SZABO, MD, MPH educational objectives As a result of reading this article, physicians should be able to: recent work that has delineated the 1. Define the different types of bone grafting. importance of osteoconductive scaffold- 2. Describe indications for use of autograft and allograft and the advantages ing, osteoinductive growth factors, and and drawbacks of each. osteogenic progenitor stem cells in bone graft healing. 3. Describe common complications of autograft and allograft techniques. 4. Explain the problems associated with vascularized allografts and com- AUTOGRAFT posite tissue transplantation. Autografting remains the gold stan- dard for replacing bone loss due to trau- ma, infection, tumor resection, revision fter blood, bone is the most fre- bones, or even whole limbs, can be trans- arthroplasty, and arthrodesis. Rapid quently transplanted human tis- planted from one person to another. incorporation and consolidation with the Asue. Basic science and clinical This article reviews the history of bone lack of immunologic considerations research completed in recent years sug- transplantation and current techniques, make bone harvested from the patient gests that bone autografting may eventual- and casts an eye toward the future. ideal. Autograft bone is osteoconductive ly become a thing of the past. Bone and contains osteoinductive proteins and replacement with synthetic materials and HISTORICAL PERSPECTIVE cells able to give rise to bone-forming growth factors are becoming common The first documented bone transplant cells. Although the viability of osteoin- procedures in the orthopedic operating was performed in 1668 by a Dutch sur- ductive proteins and osteogenic cells room. Tissue engineering technology is geon, Job van Meekeren, when he used decreases following autografting, it is approaching the ability to synthesize bone dog cranium (xenograft) to repair a sol- generally agreed that autograft bone for a particular patient. For now, however, dier’s skull defect. Scottish surgeon (especially cancellous bone) and its traditional bone grafting remains impor- William Macewan performed the first lower risks make it preferable to allo- tant. bone allograft in 1880 when he replaced graft.4,5 Autograft bone, however, is limit- The demarcation between traditional the infected humerus of a 4-year-old boy ed in supply, particularly in children. procedures and the use of new bone graft with a tibia graft taken from a child with Classically harvested from the patient’s substitutes and growth factors is blurring, rickets.1 In his publication in 1914, as combination or composite techniques Phemister2 noted the importance of From the University of California, Davis, Sacramento, Calif. prove safe and appear effective. This “hemostasis, asepsis, and coaptation of Drs Williams and Szabo have not declared blurring of boundaries represents a stage parts” in successful bone grafting. any industry relationships. in the progression from autologous bone Phemister2 and Albee3 elucidated the Reprint requests: Robert M. Szabo, MD, transplantation to a time when replace- important factors in bone grafting in the MPH, University of California, Davis, School of Medicine, 4860 Y St, Ste 3800, Sacramento, CA ment bones can be synthesized and early 20th century, paving the way for the 95817. 488 ORTHOPEDICS | www.orthobluejournal.com BONE TRANSPLANTATION | WILLIAMS & SZABO cme ARTICLE Earn Category 1 credits iliac crest, autograft can be taken from the VASCULARIZED AUTOGRAFT distal radius, olecranon, proximal and dis- Vascularized cortical autografts are tal tibia, and ribs. effective structural grafts that heal quick- Complications associated with autolo- ly without the revascularization process gous bone graft harvesting have been well and consequent mechanical compromise documented.6 Common complications seen in avascular cortical auto- and allo- include increased blood loss, increased grafts. Typically, Ͼ90% of osteocytes pre- operative time, persistent pain at the donor sent in these grafts survive the transplant site, donor-site infection, herniation, and and bring their own blood supply, perhaps iatrogenic fracture. making the contribution of the recipient Cancellous autograft is useful in situa- bed tissues less important in healing.9,12 In tions where the bone void does not require other words, vascularized autografts bring significant structural support, as in the fill- all components for healing with them. One ing of cavities left by bone cysts and benign of the primary indications for this type of tumors. Similarly, it can be packed into 1A bone transplant is a recipient bed with sub- metaphyseal optimal vascularity of bone or soft tissues defects after the or large osseous defects. Common donor depressed joint surfaces have been elevated as in fractures of the tibial plateau, plafond, and dis- tal radius. Can- cellous bone can also be added to acute fractures and delayed or non-union sites to promote union 1B 1C in defects Ͻ6 cm.7 Spinal fusions are another scenario in Figure 1: Vascularized distal radius autograft. Avascular proximal pole nonunion of the scaphoid (A). Vascularized radial bone graft being transplanted to the scaphoid (B). Vascularized scaphoid autograft in which cancellous (and corticocancellous) place with screw fixation. Radiograph shows healing 8 weeks postoperatively (C). autograft is a mainstay. Cancellous bone grafts are revascularized and incorporate quickly, and although they provide no ini- tial structural support, after 12 months their defects between 6 and 12 cm is controver- sites of vascularized autografts are the ribs, strength is equivalent to that of a cortical sial.11 Defects Ͼ12 cm have been shown iliac wing, fibula, distal radius, and scapula. graft.8,9 to have higher failure rates using nonvas- Vascularized distal radius grafts are Cortical autografts provide immediate cularized grafts compared to vascularized effective in treating osteonecrosis and structural support. Sources of nonvascu- cortical autografts.8 Nonvascularized cor- nonunions of the scaphoid,13 Kienböck’s larized cortical autografts include the iliac tical grafts may provide immediate struc- disease, and failed wrist arthrodesis14 crests, ribs, and fibula. Anterior cervical tural support but lose mechanical strength (Figure 1). The vascularized free fibula spinal fusion lends itself to the use of tri- over the first few months. This is due to graft has been used in numerous locations cortical graft from the iliac crest or dia- the revascularization process, which caus- for a variety of difficult problems.11 physeal, almost entirely cortical bone es osteoporosis and subsequent graft Potential situations in which a patient from the middle one third of the fibula. weakening. This process requires resorp- might benefit from vascularized autograft Both of these methods have generally tion of at least some graft bone to allow include osteonecrosis of the femoral resulted in higher fusion rates than allo- ingrowth of blood vessels and takes sig- head,15 reconstruction of tumor-related graft options.10 The use of nonvascular- nificantly longer in cortical bone than in defects in the proximal humerus and ized cortical autografts in segmental cancellous. lower extremity,16 treatment of congenital MAY 2004 | Volume 27 • Number 5 489 ■ Review Article cme ARTICLE Earn Category 1 credits 2A 2B 2C 2D Figure 2: Free fibular vascularized autograft. Congenital pseudarthrosis of the left tibia (A). Preoperative radiograph (B). Harvesting of the vascularized fibula from the contralateral leg (C). Radiograph immediately postoperatively (D). Radiograph (E) and clinical appearance (F) 3.5 years postoperatively. 2E tibial pseudarthrosis,17 and nonunions of tional problems; Vail and Urbaniak21 the femur,18 tibia,19 and femoral neck20 reported having to use the contralateral (Figure 2). leg on one occasion and interposition Donor-site morbidity has been a con- grafting of the peroneal artery using 2F cern with vascularized fibula auto- reverse-saphenous vein graft in another grafts.21,22 In addition to persistent pain, situation. Until recently, all of their some of the problems with autogenous investigators have found motor weakness patients underwent preoperative arterio- bone grafting. The risk of infection trans- affecting primarily extensor hallucis graphy to rule out vascular anomalies. mission from donor to host, the immuno- longus and flexor hallucis longus, sensory They ended this practice as a cost-cutting genicity of foreign tissue, and ethical con- deficits, biomechanical alterations in the measure.21 cerns are relevant with allografting—the ankle, deep venous thrombosis, and latter increasingly so with the advent of delayed wound healing associated with ALLOGRAFT vascularized allografting and limb trans- the related devascularization of overlying Transplanting bone from one human to plant. soft tissues with peroneal artery ligation. another is an idea that has been with us Although considered by some to be a Vascular anatomic anomalies pose addi- for hundreds of years and circumvents “bone graft substitute,” demineralized 490 ORTHOPEDICS | www.orthobluejournal.com BONE TRANSPLANTATION | WILLIAMS & SZABO cme ARTICLE Earn Category 1 credits bone matrix (DBM) is bone harvested rather freeze-dried and vacuum-packed— from a single donor, crushed, and dem- conditions under which it can be stored ineralized with acid. The various manu- indefinitely—and