Bone Grafting in Fracture Management ARTICLE by GARY J

Bone Grafting in Fracture Management ARTICLE BY GARY J. ALLEN, CST

his paper is every application, however, the pri- combined with a concurrent growth intended as an mary goal of graft incorporation in knowledge pertaining to bone overview of current remains the same: to promote bone growth to create a new awareness in bone grafting appli- healing in order to realize certain hacture management. cations, with special orthopedic benefits, such as the Bone grafting is one of the oldest attention given to restoration of mechanical function. known types of organ transplanta- fracture manage- tion; the first successful bone graft is ment, and as such assumes a certain History said to have been implanted in knowledge by the reader of Prior to the dawn of the modem 1688.31n1907. G. Axhausen anatomy and medical terminology. "metallurgic age" of orthopedics, performed a series of bone Fracture management is one of the the basic concepts of bone grafting transplants and through them deter- oldest medical concerns and was the had long been established. Ortho- mined that the periosteum played a precursor of many modern orthope- pedics itself reflects the early med- significant role in graft ~urvival.~ dic procedures. Improper fracture ical practice of treating crippled This was considered a crucial point, management can affect one's liveli- children with a regimen of rest, since most bone grafts prior to this hood and overall health. braces, and exercise, its name being time were taken without regard for The text of this article will derived from the Greek words ortho the periosteal covering. However, in encompass a brief history of fracture (straight) and pais (child)? In this 1914, D. B. Phemister put forth the management and bone grafting, regard, fracture management could "creeping substitution" theory to basic anatomy of bone, types of frac- be called one of the field's nourish- describe the apparent phenomenon tures, types of bone grafts, indica- ing roots. of the graft replacement by newly tions for and complications of bone The earliest records concerning formed bone? The acceptance of this grafts, the healing processes of bone, fracture management date to Egypt theory as fact led to a new direction and alternatives to bone grafting. in 2500 BC, where drawings depict for bone grafting. Bone grafting is a frequent part of people walking with a form of arti- In the 1950s, Sir John Charnley, orthopedic procedures especially ficial support (eg, a cane), and famous for the development of joint those involving traumatic injury. mummies are found with intact prostheses, was the first to use pro- Pain relief is also frequently reme- splints of wood and glue-impreg- phylactic bone grafts, applying such died, though in a radical manner, by nated linen2Hippocrates wrote practice to the management of tibia1 bone graft incorporation in extensively on fracture fractures4Shortly thereafter, P. R. arthrodesis. In this light, surgical management in his book On Frac- Harrington introduced his instru- technologists will benefit from an tures, which described traction and mentation for holding the spine understanding of the role that bone countertraction techniques, splint- rigid during fusion. Their individual grafts play in these pursuits. ing, joint immobilization, and treat- successes supported bone grafting's ment of compound fractures? new place in fracture management: Introduction Unfortunately, much of his work that of a temporary and porous Bone graft augmentation is used in was either ignored or forgotten for agent of osteogenesis, requiring many surgical applications, includ- centuries. rigid fixation to accomplish its task. ing interarticular fusion, total joint It was not until a renewed inter- In the 1960s, C. S. Venable and arthroplasty, and especially fracture est in crippling diseases of the eigh- W. G. Stuck performed a series of management. Bone grafting tech- teenth century that modern ortho- tests that confirmed this thought, niques have been used with increas- pedics began to evolve and, with and it was they who are credited for ing frequency since the turn of the the discovery of x-rays in 1895 by advancing the idea of fixation for century, with an estimated 250,000 Wilhelm Conrad Roentgen, the the sole purpose of promoting graft procedures performed each visualization of bone became possi- osteogenesis? This new understand- year in the United States alone.' In ble. This latter development was ing in fracture management altered

THE SURGICAL TECHNOLOGIST AUGUST 1994 the approach of many techniques and stands today as the basis for all bone graft incorporation.

Anatomy A typical long bone (eg, femur) is not only a supportive structure and a producer of blood cells, it is also the framework of movement. Fracture management is primarily concerned with the structural importance of bone, which ultimately reflects upon its other functions. Bone also serves as a depository for mineral salts, par- ticularly calcium carbonate and cal- cium phosphate (known as hydrox- yapatite). The presence of these salts not only accounts for bone's hard- ness, but ultimately defines its differ- ence to other connective tissue^.^ Figure 1. Cross section of typical long bone. A, Periosteum; B, Cortical zone; C, Bone consists primarily of two Cancellous matrix; and D, Intermedullary canal. components: cortical, or the hard, dense outer support structure, and cancellous, the soft, spongy matrix God heals. In the case of bone, the within the hematoma (Figure 2). inside the bone that provides nour- body offers a considerable amount Granulation tissue now invades ishment and has the ability to manu- of aid. so much so that bone healing the clot making it more fibrous. This facture blood (Figure 1).Without the has become more properly termedu lends temporary support and pro- nourishing cancellous matrix, the bone regeneration. vides the foundation for further cortical structure would not have the Soft tissues heal by the perma- regeneration. After several days, supply of nutrients to grow. Like- nent fibrous scarring together of the cartilaginous deposits begin to wise, without the cortical rigidity, opposing edges, but the fractured appear within the granulation tissue the cancellous matrix would be bone works immediately and dili- and a fibrocartilage (soft callus) unable to provide sufficient strength gently to repair, replace, and forms about the fracture site. This to function. Consequently, both com- reshape itself. Several models of this stage will develop over 2 to 3 ponents are needed for proper bone activity have been set forth, most months, and may be reflected in a integrity. notably by J. Hunter in the 1830s, modicum of clinical stability (see who described four essential stages Figure 2). Types of Fractures of bone regeneration (inflammation, Callus (hard callus) formation Fractures may be described by the soft callus, hard callus, and remod- occurs as the cartilage and fibrous angle and extent of the break in the eling) in his paper titled "Bone tissue are replaced by calcium from bone's continuity (eg, transverse, Repair.04Later models expanded to the mineral salt deposits (ossifica- longitudinal, comminuted, five stages (hematoma, granulation, tion). This is in effect true bone impacted), by the effect upon other callus, consolidation, and remodel- replacement, which can be tissues (as with "open" fractures), ing), which will be discussed here, confirmed by x-ray film (see Figure and by the underlying cause (eg, and more recently a sixth stage was 2). traumatic, path~logic).~Initial reduc- named (which adds the stress upon Consolidation of the calcium tion bone grafting is considered the bone at the moment of fracture deposits occurs both within and when there is enough bone loss to in the theory that the force itself ini- around the fracture site as the inhibit proper reunion of the frag- tiates bone reeeneration14V remaining cartilage is replaced and ments, as is often seen with gunshot Hematoma, in this instance, is the hard callus grows more dense. injuries. Grafts supply the tissue clot formation around the fracture This persists for several months needed to span the void while site, the rapidity and extent (inflam- until a bony bridge fuses the frac- encouraging the healing process by mation) of which is dependent upon tured ends. At this point, the bone providing a porous path for vascular the vascularity of the bone involved. will not only demonstrate signifi- ingrowth and pressure contact Blood seeping from the ends of the cant clinical stability, it will also between the two fracture ends. broken bone into the surrounding appear as a solid unit on soft tissues provides a nutrient base roentgenograms (see Figure 2). Bone Healing that supports the ensuing stage. The Remodeling of the callus to Many surgeons have humbly admit- clot remains for several days as vas- resemble the original shape of the ted that a doctor can resect, remove, cular ingrowths establish bone is the final phase, during and repair, but only the body and themselves around the fracture and which dead bone fragments are also

THE SURGICAL TECHNOLOGIST AUGUST 1994 ture area) for imvlantation in the defect. Common autogenous donor sites are the iliac crest, fibula, and proximal tibia. Autogenous bone grafts, by virtue of their origin, have a greater chance of survival. Since they are "live" bone autografts, they provide not only structural support but encourage osteogenesis on the cellular level as well.3 Homogenous grafts, also known

as alloerafts.u r are those from other people or cadavers. Cadaveric har- vests are dead bone grafts that are processed for implantation in accor- dance with the guidelines established by the American Associ- ation of Tissue bank^.^ These types of grafts add only structural sound- ness to the fracture, either by way of cortical rigidity or cancellous poros- ity. In many cases, this may be all that is required to support proper regeneration. Cadaveric allografts are commonly prepared as femoral heads, long bone shafts, tricortical Figure 2. Stages of bone regeneration. A, Hematoma formation; B, Granulation; plugs, and "croutons" (small cubes C, Callus; DlConsolidation; and ElRemodeling. (Note: Reestablishment of inter- of cancellous bone) (Figure 3). medullary canal.) (Adapted from Campbell's.) Homogenous bone grafts can also be harvested live, and are usually done so from a sibling or other close relative. The most common form of reabsorbed. Ultimately, the inter- to regenerate. Thus, a fracture may this graft is that of bone marrow. medullary canal will be heal poorly (malunion), over a sub- Percutaneous in their administra- reestablished (although usually nar- stantially prolonged period of time tion, marrow transplants target not rower than its original size) and a (delayed union), or not at all the supportive or osteogenic roles of continuity of the structural cortical (n~nunion).~In each of these bone grafts, but rather are directed bone (which is usually more broad instances, a bone graft may be at improving the bone's blood man- than it was originally) will be real- required to affect regeneration. This ufacturing ~apabilities.~ ized (see Figure 2). (Note: There is involves surgical intervention, dur- The third type of bone grafting also a direct form of bone healing ing which the fracture site is material is synthetic bone supple- that occurs- - onlvJ with fractures that debrided of soft tissue and extrane- ments. One that has recently been are anatomically reduced and stably ous callus, the fracture line is liber- developed by Zimmer and Collagen fixated [eg, plate and screws] in ally curetted to encourage vascular- Corporation is known as ~ollagraft.~ which the bone begins remodeling ity between the bone ends, and the Collagraft is not bone but rather from the onset. Although a callus graft is packed in the defects3It is at porous beads consisting of 60% may form about the metal implants this point that the periosteum plays hydroxyapatite, and 40% tricalcium as a reaction to the presence of a for- its role in bone healing. After the phosphate ceramic and fibrillar col- eign body, this direct process is an bone graft is packed in the defect, lagen.5Although it was not devel- indication of the important roles the periosteum is closed around it, oped to replace bone, and in fact is that proper alignment of the frac- thereby setting a physical limit to applied as a biologic augmentary tured ends, compression, and rigid radial callus growth. substance to bridge gaps in a frac- fixation play in bone healing.)4 ture during the regenerative The entire regenerative process Types of Bone Grafts process, its make-up has been found may take years depending upon the In fracture management, there are io actually encourage osteogenesis. age and overall health of the indi- three categories of bone grafts, each Collaeraftu is mixed with bone mar- vidual and is never assumed to be of which carries its own particular row prior to use, according to crite- complete until so verified under cautions and uses. The first ria set forth by Zimmer and Colla- radiologic examination. A number category, autogenous, refers to the gen Corporation, and its granular of factors, such as infection, poor harvesting of the patient's own bone form allows for utilization in a vari- reduction, and concurrent disease, (usually from another site but ety of grafting situations. Another 1 can undermine the bone's attempt preferably from the immediate frac- type of synthetic graft is used in I, THE SURGICAL TECHNOLOGIST Figure 3. Types of bone grafts. A, Diaphyseal shaft; B, Tricortical plug; and C,Cancellous crouton.

basically the same fashion as colla- ilium or tibia. As spongy matter, essential. Cases have been graft, but is instead derived from cancellous grafts can be easily documented in which cadaver processed sea coral. shaped and/or morselized to fill femoral shafts were used as tubular Heterogenous grafts, such as any bony defect. They are often inserts for femoral diaphysis length- porcine heart valves, have been a used in fracture management for ening; however, these results have boon to many surgical fields; unfor- this purpose, as well as in total been less successful. tunately, they have not found favor arthroplasty procedures when cysts Doweling, or the use of cylindri- in orthopedics. In repeated experi- or other articular surface defects cal plugs, was once a common graft- ments these grafts have proven exisL3Cancellous grafts are also ing technique used specifically for unsatisfactory for any purpose other used as an underlying "packing" to the promotion of osteogenesis, but it than simple splinting. Heterogenous restore depression fractures (ie, ocu- too has waned in use.4Dowels are bone grafts do not stimulate osteo- lar orbit, tibia1 plateau), or, more taken by using hollow core drills, in genesis and are frequently subject to recently, to reinforce the integrity of much the same way that bone foreign body reactions such as infec- articular surfaces as seen with chon- biopsy specimens are obtained, tion and rejection. However, porcine dromalacia of the femoral condyle. which provide a bone graft with an bones are used as a source of colla- Homogenous croutons are also intact cortical surface attached to a gen, from which other grafting used as packing in instances of bone length of cancellous matrix. products and hemostatic agents are loss or disease, but as they are prod~ced.~ freeze-dried they require some form Indications for Bone Grafting of reconstitution to soften them Primarily, bone grafts are used in Uses of Bone Grafts prior to use.3This may be instances where there is substantial Both homogenous and autogenous accomplished by soaking the cubes bone loss significant enough to bone grafts may be used in several in normal saline or, preferably, in inhibit proper union, and when a ways. Onlays are cortical bone the patient's blood. They may also reduced fracture is delayed or grafts specifically employed as be morselized and mixed with mar- blocked from its union. Generally, splints for structural support, and as row before implantation to increase bone grafting is performed at the such must be secured in place with the chance of success, but again, time of primary reduction or at either screws or cerclage wire, to be homogenous inserts are not as desir- about 6 to 12 weeks after the wound effective. Generally, a flattened sur- able as their autogenous counter- has been ~tabilized.~This later pre- face will be prepared to accept the parts. caution, long the standard for bone graft, or the natural contour of say, a Tubular grafts are usually in the grafting usage in nonunions, is femoral diaphysis, may be incorpo- form of autogenous whole fibular taken with the risk of infection rated onto that of the underlying grafts for radial or ulnar firmly in mind. In any case, restora- fractured bone. Onlays may also be ~upplementation.~In use, the shat- tion of function (as with fractures) used as prophylactic grafts in total tered bone's diaphysis is excised by and/or elimination of pain (as seen hip arthroplasty by acting as a rein- clean transection both proximal and with spinal fusion and arthrodesis) forcement onlay for the trochanteric distal to the fracture site and the are the main objectives. As a rule, region, thereby reducing the inci- fibular diaphysis is implanted. where fixation is required a cortical dence of fracture that can occur dur- Obviously, this requires substantial graft is used, and when there is a ing femoral rasping and reaming3 compression fixation and alignment need to encourage osteogenesis, Cancellous inserts are to succeed and, in this particular cancellous grafts are the choice. autologously harvested cancellous case, the salvaging and reclosure of grafts, generally taken from the the periosteum over the graft is

THE SURGICAL TECHNOLOGIST Complications of Bone Grafting from injury to operative reduction is ing the body in doing its job, bone The invasive harvesting of autoge- greater than 30 days5 regeneration will occur more readily nous bone causes a certain low, but and with a higher rate of success. significant, degree of morbidity as Other Developments in Fracture Recent advancements in biotechnol- well as contributing to interopera- Management ogy, as seen with collagraft, are tive blood loss. Harvesting can fur- Biodegradable implants have been geared to this goal also, and with ther lead to donor site fractures, her- developed with the hope that future greater numbers of applications and nias, nerve impairment, and acute removal of the implant will not be successes these supplements may pain, besides adding anesthesia and warranted, and too, that the transfer find a growing niche within which a operating time to a procedure.' of the "load" from the hardware to solution to graft harvesting, storage, Bone quality is also a factor. A the bone itself, is more gradual and and morbidity may be found. disease that may have initiated the therefore less traumatic to the fracture can be present in other patient and healing bone. Unfortu- Acknowledgement areas of the body, thereby rendering nately, the materials are not as yet The author wishes to express his ~ a proposed graft site useless. Stud- strong enough to provide the initial appreciation for the efforts of Dick

ies have also shown that there is a suvvortI I that is essential while the Loftus of Zimmer, Inc., in the prepa- greater chance of graft failure when bone regenerates, so use has ration of this paper. A the bone is harvested from a site far dropped dramati~ally.~ from the fracture. This is unfortu- Electric and electromagnetic References nate, in that often the need for a stimulation to encourage bone 1. Younger EM, Chapman MW. Morbidity bone graft in fracture management regeneration for nonunions is a at bone graft donor sites. 1Orthop Trauma. 1989;3(No. 3):192-195. is precipitated by the lack of avail- technique that has been used for 2. LJ Atkinson. Introduction to Operating able tissue at the injury site. some years. Various configurations Room Technique. 7th ed. St Louis, Mo: Homogenous grafts, although of electrodes and wave forms have Mosby-Year Book; 1992. available in readily usable forms, all shown effectiveness in this 3. Crenshaw AH. Campbell's Operative have come under more scrutiny regard, with results approaching Orthopaedics. 8th ed. St Louis, Mo: recently with the advent of certain 80% in cases when applied for more Mosby-Year Book, Inc; 1992;1:12- 3 20,317,320,331,337. infectious diseases. There is a grow- than hours per day.4 4. Crenshaw AH. Campbell's Operative ing concern that viral transmission There are three avenues of cur- Orthopaedics. 8th ed. St Louis, Mo: is possible due to the organism's rent delivery via the placement of Mosby-Year Book, Inc; 1992;2:725,735- unique reproductive nat~re.~ conductive electrodes: noninvasive 736,776,1300-1301. Bone grafts in general can fail. (percutaneous implantation of elec- 5. Zimmer. Highlights of Safety and Effec- Graft failure may necessitate addi- trode ends), and invasive (which tiveness Studies for Collagraft Bone Graft Matrix. Zimmer and Collagen Corp. tional surgery to correct the prob- entails surgical implantation of the Zimmer, Inc. May 1993. lem, which may be further compli- conductive surfaces at a point under 6. Cornell C, Chapman MW, et al. Multi- cated by necrosis or sloughing of the the skin directly over the target center trial of dollagraft as a bone sub- ] overlying soft tissues. Infection is area). DesviteI the differences in stitute. Orthop Trauma. 1991;5(No. 1):l- also a concern, particularly with these approaches, results seem to be 8. autogenous donor site grafts. (It comvarable. and this form of should be further noted that the encouragement for bone regenera- treatment of open fractures carries a tion has proven to be beneficial for strong concern for infection from up to 10 years after the initial frac- debris, which can lead to graft fail- ture treatment and nonunion. It has ure. They also allow the blood that also shown effectiveness with, or normally forms the hematoma to rather ambiguity for, infection. leave the fracture site, in effect However, the prolonged immobi- GayAllen, CST, is delaying the regenerative process lization necessary to obtain good an &year member of and undermining graft effort^.^) results often proves to be counter- AST and earned his Collagraft, although not free productive to rehabilitative efforts. associate degree at Springfield Technical from the effects of resorption or Community College. malunion seen with grafts, has Conclusion He is employed at demonstrated lower infection rates Fixation and osteogenesis are the ~a~jtate'~idica1 and higher percentages of union. keys to current fracture Center in Springfield, Massachusetts, and However, collagraft has been shown management techniques aimed at specializes in orthope- to be less effective in cases involving the proper alignment and ultimate dic and thoracic pathologic fractures or bone disease, regeneration of the broken bone, surgery. Mr Allen has and is cautioned against usage and commonly it is a bone graft had several articles published in the jour- where surgical intervention is not supplement that aids in the realiza- nal. He won second warranted (ie, a simple fracture that tion of these goals. The body knows place in this year's can be satisfactorily reduced in a what to do, and as fracture manage- Writer's Award and closed manner) or when the interval ment techniques concentrate on aid- first place in the 7993 1 Writer's Award. I THE SURGICAL TECHNOLOGIST AUGUST 1994