Bone Grafts and Implants in Spine Surgery

CHAPTER 39

BONE GRAFTS AND IMPLANTS IN SPINE SURGERY

Ken Hsu James F. Zucherman Arthur H. White

Recent advances in both fusion tech of scaffolds, bridges, spacers, fillers of J • niques and instrumentation have defects, and replacements of bone lost. markedly facilitated the treatment of Immobilization of multiple motion seg spinaldisorders. Yet asignificantnumber ments is frequently necessary in the spine; of patients exist who continue to have great demands arc made on bone grafts. pseudarthroses. Despite the surgical ad In the lumbosacral spine, body weight vances the essentials ofa successful spinal and muscular forcesimpart loads equal to fusion still appear to be the effective ap three or four times body weight. It is plication of sound bone grafting princi not surprising that the highest rate of ples. These principles, along with the bone graft failure is seen in the lumbo techniques, problems, and complications sacral spine. Hence, the following is a associated with bone grafting, arc re discussion of technical problems, bio- viewed in this chapter. mechanical and physiologic character The loss ofbone in the spine often pre istics of bone grafts, and implants. sents serious difficulties not seen in other areas. The most favorable replacement THE AUTOGRAFT would still be a bone graft that fills the Autograft, or bone graft transplanted defect and becomes incorporated into the from one site to another in the same indi spine. However, the availability of ap vidual, is considered to be the most bio propriate bone to replace the loss is a logically suitable. Its advantages include: significant problem. Alternatives to bone 1. Has superior osteogenic capacity grafts, including a number of implants a. Contributes cells capable ofim used to stabilize the spine, are also sur mediate bone formation veyed. b. Allows for bone induction by i Bone grafts have often played the roles recipient bed where nonosseous

'-.-f Dotw Grnfts and JnipfaiUs in Spine Surgery 435

tissue is influenced to change its for example, high speed burring cellular function and become and inadequate irrigation retard osteogenic healing*'"' 2. Lack of histoconipatibility differ 6. Position the canccllous surface ences or ininiunologic problems a. On opposing cancellous surtace 3. Ease of incorporation b. On surrounding soft tissue with 4. No disease transmission ' good blood supply The disadvantages include; c. So that total mass ofgraft is not 1. Additional incision or wider ex too thick to prevent nutrient posure, prolonged operative time, diffusion from recipient bed and increased blood loss 7. Always avoid 2. Increased postoperative morbidity a. Dead space 3. Sacrifice of normal structure and b. Hematoma weakening of donor bone c. Interposition ofnccrotic tissue 4. Risks of significant complications 8. To minimize risk, be aware of 5. Limitations in size, shape, quantity, a. Anatomy and quality b. Potential complications For optimal results harvest autogenous The iliac crest is the most versatile bone canccllous bone in the following manner. graft reserve. It isrelatively subcutaneous 1. In thin strips and easy to harvest in prone, supine, lat a. Not exceeding 5 mm in thick- eral, or other positions. It is expendable, and it has a large reserve of cortical b. To provide maximal exposure and canccllous bone. In addition, it al of superficial cells lows carpentering of different shapes and c. To allow rapid vascularization 2. Graft wrapped in a gauze soaked in patient's blood Anterior Iliac Crest Grafts a. To avoid exposure to high in Anterior iliaccrest bone grafts are used tensity lights for anterior interbody fusion ofthe cervi b. Kept in temperature less than cal, thoracic, or lumbosacral spine. The 42° C^' subcutaneous anterior superior iliac spine c. Not stored in saline or antibiotic and iliac crest and easily palpable. The solution^-'"'' iliac tubercle is the widest portion where d. Without the use of chemical a large quantity ofcorticocancellous bone sterilization'"" is found. (See Fig. 39-8.) 3. Transfer the graft to the recipient A skin incision is made parallel to or in bed as soon as possible to line with the iliac crest. It is advantageous a. Avoid exposure to air for more to center the incision over the iliac tuber than 30 minutes'"'' cle. The incision is carried down to the b. Protect the viability of the sur bone of the crest, and the muscles arc face cells elevated subperiostcally to expose the 4. Place the graft wing of the ilium. a. In wcll-vascularized bone bed The tensor fascia latac, glutens medius, b. In well-decorticated bone sur and glutens minimus originate from the face (cancellous site is superior) lateralaspectof the ilium. They are inner vated by the superior gluteal nerve. The c. With healthy soft tissue cover- { age abdominal muscles are also attached to 5. Minimize surgical trauma because, the iliac crest and arc scgmentally inner-

• •

• -i.. • .r; • • 1 i:; 436 Spine Surgery: An AnihoIogY

vatcd. The incision over the crest is there close to the anterior superior iliac spine, fore "internervous" and safe. fracture may occur. (See Fig. 39-6.) An appropriate osteotome or chisel Avulsion of the anterior superior iliac may be used to outline a cortical window spine may occur by the action of the at in the lateral iliac surface from which to tached muscles, such as the tensor fascia procure the bone graft. Longitudinal lata or sartorius. parallel cuts may be made (Fig. 39-1). Bone may be removed in the form of Strips of cancellous bone may be re block, dowel, strips, and by way ofcorti moved with a curved gauge. Care must cal window or "trap door" (Figs. 39-1 to be taken not to violate the inner table of 39-4). The iliac crest contour can be pre the iliac wing where hernia is a significant served by removing the bone deep to the potential complication. crest, or by temporarily detaching and Bone graft may be obtained from the repositioning it later (Fig. 39-5). The inner table of the iliac wing. However, anterior superior iliac spine should be left there are risks of peritoneal perforation intact to maintain normal appearance. and significant bleeding with formation The region ofthe iliac spine should not be ofhematoma in the retroperitoncal space. weakened by removing bone adjacent to It is important not to carry the incision it. Fracture and displacement of the to or anterior to the anterior superior iliac inguinal ligament may result (Fig. 39-6). spine. Injury to the lateral femoral cuta The wound should be closed properly. neous nerve or the inguinal ligament The muscles and fascia must be sutured to must be avoided. Detachment of the in their original anatomic positions and the guinal ligament may result in inguinal defects closed; an effective drain should hernia. If bicortical bone is taken too be used.

/ •• ' (/'((//' / \/ /

l< Mcu.

Fig. 39-1 Corticocanccllous bonegrnftisobtainedfromlateral iliac surface usinglongitudinal parallel cuts with an osteotome or chisel.

»•.«) , •> / • 1 ' Bone Grafts and Implants in Spine Surgery 437

Fig. 39-2 Hor.scshoc-sliapcd corticocanccllous bone graft is obtained froin iliac crest using ostco- tontcs positioned parallel to each other.

Fig. 39-3 Dowel-cutting instrument is used to obtain iliac graft with two tooled cancellous sur faces and cortical faces on three sides for anterior spinal intcrbody fusion.

Fig. 39-4 Cortical "trap door" is used to gain access to iliac cancellous bone.

'' 1 I !-•! v'Nr ^ f 438 Spine Surgery: An Anthofogy

m Temporary detachment The iliac contour S r of the iliac crest Is preserved intact ^"5 ] i

The defect is filled to avoid hernia (Bonecement may be used) Fig. 39-5 Large iliac graft isobtained with preservation of tlie iliac contour.

t, Anterior superior iliac spineL \ Inguinal ligament

Fig. 39-6 Illustration ofattachment ofinguinal ligament to anterior superior iliac spine. Detachment ofingiiinal ligament may lead to inguinal hernia. Injury to lateral femoral cuta neous nerve should also be avoided. Bofic Crafts aitd Implants in Spine Surgery 439

Posterior Iliac Crest Grafts bone that forms the notch. This can pro The posterior iliac crest provides a duce instability ofthe pelvis. It is impor largequantity of cortical cancelious bone tant to stay cephalad to the sciatic notch graft. The posterior superior iliac crest is and remove bone only from the false pel palpable under the skin dimple in the vis. For a landmark, an imaginary line superior medial aspect of the gluteal re dropped anteriorly from the posterior gion. The iliac crest curves cephalad and superior iliac spine with the patientin the laterally from the posterior superior iliac prone position can be used as the caudal spine. limit of bone removal (see Fig. 39-15, A An oblique, curved or vertical incision and B). Care must be taken not to enter may be made over the posterior iliaccrest the sacroiliacjoint, which may become a or in line with it. The cluneal nerves cross source of persistent pain and instability the iliac crest 7 to 12 cm anterolateral to when injured. the posterior superior iliac spine (see dis A sharp surgical instrument (that is, cussion under Complications) and must an osteotonie or tip of Taylor retractor) be protected (sec Fig. 39-13). may injure the sciatic nerve deep to the A midline spine incision may be ex sciatic notch. Laceration of the superior tended distally and the posterior iliac gluteal vessels is a significant danger in crest approached laterally under the skin this region. The vessels leave the pelvis and subcutaneous fat. This avoids the use via the sciatic notch. A divided vessel can of a second skin incision. easily retract into the pelvis and presentsa The incision is carried down to the very alarming complication (sec discus bone of the crest, and the muscles arc sion under Complications) (sec Fig. 39- elevated subperiosteally from the poste 14)- rior lateral surface of the ilium. This ap Nutrient vessels supplying the ilium proach docs not denervate the muscles. found in the mid portion of the anterior The gluteus maximus, medius, and mini gluteal line may present troublesome mus originate from the lateral surface of bleeding and should be controlled with the ilium. The superior gluteal nerve in Gelfoam, Surgicel, bone wax, or electro- nervates the gluteus medius and mini coagulation. mus, and the inferior gluteal nerve inner A relatively painless bone graft donor site vates the gluteus maximus. The para- for lumbar spine fusion is possible by spinal musculature innervated seg- applying the following technique. A mcntally originates from the iliac crest. separate incision over the iliac crest is It is very important to remember the not made through the skin. The fascia following rules. through the wound of the lumbar sur kr 1. Stay on bone and work subperios gery isgrasped with Kochers clamps and teally. pulled medially. The subcutaneous tissue 2. Avoid the sciatic notch and protect is carefully elevated off the fascia laterally the sciatic nerve. and cautinlly until the fascia immediately 3. Protect the superior gluteal vessels above the posterior iliac crest and poste •-t- (see discussion under Complica rior superior iliac spine isreached. ATay tions) and protect the pelvic stabil- lor retractor is placed in the subcutaneous ity. tissue lateral to the crest over the ilium 4. Avoid the sacroiliac joint. posteriorly. The periosteum is not dis 5. Protect the posterior sacroiliac liga sected from the ilium except from the ments. superior-most crest. The fascia is incised The removal of bone in the vicinity of over the crest, and an elevator is used to the sciatic notch can weaken the thick scrape the superior crest free of perios- 440 Spine Surgery: An Anlliology

Fig. 39-7 A gouge is used to remove posterior "roof of ilium aJid the cancellous bone between cortical layers.

Iliac tubercle

P.S.I.S.

A.S.I.S.

Fig. 39-8 Cancellous bone is removed from iliac tubercle, anterior or posterior iliac spine region throughsmall cortical opening.

tcum to bare bone. Gouges arc used to terior aspect ofthe iliac crest, followed by remove the "roof" of the ilium and the the iliac tubercle and anterior superior cancellous bone between the cortical lay iliac spine areas. I ers, leaving the cortices intact laterally A "trap door" cut in theanterioror pos and medially with theirsoft tissue attach terior outer table ofthe ilium and hinged ments (Fig. 39-7). This technique mini on muscles can be opened to allow access mizes postoperative donor site pain and to cancellous bone. The trap door is prevents uncomfortable scar tissue from closed at the end. Postoperative pain ap forming over the ilium, as when the lat pears to be less with this technique. Cos eral cortices are removed. metic deformity is minimal (sec Fig. When limited quantity of cancellous 39-4). bone is required, the following methods Wolfe andKawamoto'^® reportedatech may be advantageous: nique of obtaining full thickness bone Cimcdage allows harvest of cancellous graft from the anterior ilium. Incision is graft with least morbidity through a made through the iliac crest. The outer small round cortical window using a ridges of the iliac crest are split obliquely sharp curette as shown in Fig. 39-8. Can with the muscular and pcriosteal attach cellous bone is most abundant in the pos ments remaining. All the iliac bone be-

^ '5 ; fh olfc and Kawamoto's technique of thickness bone graft from the ante- sharp ostcotome is used to make Its shown above and in Fig. 39-10.

I m-M

A large full-thickness bone graft can

c muscu ar a as shown, using Wolfe and Kawa- lod.

i s 442 Spine Surgery: An Anthology

Fig. 39-12 Wolfe and Kawamoto's technique of rcapproxiinating the two fragments of die crest, using wires or sutures. Figure eight wire or suture may be passed through the bone witli an awl and fixed to adjacent bone.

ncath tliis can then be removed. The Cockin^'' reviewed 118 cases of iliac edges of the crest may be reapproxi- crest bone graft procedures and found mated, thus minimizing cosmetic de major complications in 3.4% and minor formity, hernia, hcmatoina, and post complaints in 6%. There were two cases I i operative morbidity (Figs. 39-9 to 39- of meralgia parcsthctica, one of hernia, li 12). and one ofhip subluxation after extensive removal of the iliac crest. The minor COMPLICATIONS complaints included wound pain, hyper- Complications involving the iliac bone sensitivity, and buttock anesthesia. "I graft donor site arc not uncommon. Al though some of these complications may Nerve Injuries not be serious, they add to the patient's Possible nerve injuries include the fol discomfort and prolong the convales lowing. cence. The complications that arc due to 1. Lateral femoral cutaneous graft removal from the ilium include: nervc2'^-"« 1. Major blood loss 2. lliohypogastric (lateral cutaneous if 2. Hcmatoina. branch) nerve 3. Nerve injury (neuroma forma 3. Superior cluneal nerve (cutaneous (vv tion) branches of dorsal rami LI, L2, 1 4. Severe pain (chronic pain) L3)2r>.3r, 5. Hernia 4. Middle cluneal nerve (cutaneous 6. Cosmetic deformity branches ofdorsal rami SI, S2, S3) 7. Fracture 5. Sciatic nerve 8. Sacroiliac joint injury 6. Ilio-inguinal nerve'® 9. Pelvic instability 7. Femoral nerve 10. Hip subluxation 8. Superior glutcal nerve 11. Gait disturbance Superior cluneal nerves are lateral 12. Peritoneal injury branches of the posterior primary divi 13. Uretcral injury sion ofthe upper three lumbar nerves that 14. Hcterotopic bone formation run posteriorly through the lumbosacral 'S 15. Infection fascia at the lateral origin ofsacrospinatus •hS

^ I *4 ' f " 'i ^ Bone Grafts and Implants in Spine Surgery 443

Superior cluneal nerves dorsal rami LI 2 L liiohypograstrlc nerve lateral cutaneous branch Lateral cutaneous branch Posterior superior \ VV ofsubcostal nerve (T12) iliac spine' Middle cluneal nerves LjJIMi cutaneous branches Anterior superior dorsal ramI iliac spine 2

Gluteus maximus- ♦ ' ^llio-tibial tract Fig. 39-13 Illustration ofthe nerves that may be injured during the procedure to remove bone graft from the iliac crest. muscle. They crossover the dorsalaspect (see Figs. 39-14 and 39-15). of the posterior iliac crest and provide The ilioinguinal nerve may be injured sensation to the skin of the buttocks. when the abdominal wall is retracted Theyarc found? to 12 cmantcrolateral to medially from the anterior iliac crest. The i. the posterior superior iliac spine in the nerve may be compressed beneath the 'Sf adult. 'When incision is made across or retractor on the inner part of the wall of parallel to the posterior iliac crest, the the ilium. It occurs when the inner cortex S cluneal nerves may be injured (Fig. 39- of the anterior ilium is exposed for re 13). moval of bone grafts. Ilioinguinal neuro Painful neuritis of the buttocks has logic injury is characterized by pain radi been reported.That these nervesare a ating from the iliaca toward the inguinal cause of disability can be demonstrated and genital areas. This complication is by relief of symptoms after they have well discussed by Smith and associates. been infiltrated with local anesthetics. The iliohypograstric nerve(lateal cuta Permanent relief can be obtained by re neous branch, LI ventral rami) is found section of the nerves with the transected over the midlateral aspect os the iliac ends allowed to retract into the soft tis- crest. It shouldbe protectedwhen work m- ing in this region (sec Fig. 39-13). Thc sciatic nerve may be injured when Vascular Injuries the dissection is extended down to the sciatic notch. A surgical instrument such Vascular injuries may include the su as an osteotomc may be passed deep to perior gluteal artery (and vein),""'" the the sciatic notch to cause this injury. The deep circumflex iliac artery, the iliolum- bony rim of the notch should bepalpated bar artery, and the fourth lumbar artery. before the dissection is carried to this The superior gluteal artery is a branch area. An imaginary plumb line dropped of the internal iliac artery that curves from the posterior superior iliac spine around the rim of the sciatic notch as it with the patient in the prone position will leaves the pelvis. It may beinjured when pass tlirough the bony rim of the sciatic dissection is carried close to the sciatic notch. This serious complication can be notch. An osteotomcor thesharp point of avoided if you stay cephalad to this line a Taylor retractor may enter the notch

1 ij'^ T i [-«- igKswei's A. A 444 Spine Surgery: An Anthology

Poslerior superior iliac spine

Superior giuteal artery

•' .i / .,1

Piriformis

Sciatic nerve

Fig. 39-14 Illustration of the superior glutca! artery, curving around the rim of the sciatic i :j notch as it leaves the pelvis.

and pose similar danger to the artery. through the bony rim ofthe sciaticnotch. This complication can become alarming, It is important to stay cephalad to this since the divided vessel easily retracts into line. the pelvis (Fig. 39-14). Escalas and DeWald''" reported a case If the superior gliiteal vessel is lacer of combined traumatic superior giuteal ated, it can be compressed locally and arteriovenous fistula and ureteral injury exposed for ligation or clipping. A finger complicating removal ofbone graft from may be used to apply direct pressure to the posterior ilium. The tip of a Taylor the vessel against the bone. Kahir^' dis retractor accidentally dislodged and cussed the use ofa Raney-modified Ker- penetrated into the sciatic notch to cause rison rongeur to remove the upper mar this unusual injury. gin of the sciatic notch to expose the The deep circuinjlcx iliac artery, the bleeding vessel. If the bleeding vessel is iliolwnbarartery, or thefourth lumbarartery still not accessible, the patient may be may cause troublesome bleeding when positioned for a retroperitoneal or trans- working on the inner table of the ilium. peritoneal exposure ofthe vessel. Arterial Occasionally, peritoneal perforation ac occlusion by cmbolization or using a companies the arterial injury. The ana Fogerty catheter is another option. tomic position of the arteries are il i Injury to the superior giuteal vessels lustrated in Figs. 39-16 and 39-17. It is can be prevented if the surgeon is well very important to stay subperiosteally aware ofthe anatomy in this region. The and carefully elevate the abdominal wall ,1 bony origin of the glutens maximus or muscles offthe crest and the iliacus mus the roughened area anterior to the pos cles off the inner table of the ilium (Fig. terior superior iliac spine is a good land 39-18). mark and can be used as the caudal limit A hernia through the iliac bone graft of bone removal (Fig. 39-15, A and B). donor site may occur after the removal of An imaginary plumb line dropped from full thickness bone from that site. It may the posterior superior iliac spine with the appear as an iliacswelling, sometimes as patient in the prone position will pass sociated with pain or symptoms ofbow-

•ti -

/ Bone Grafts and Implants in Spine Surgery 445

Superior cluneal Posterior superior Iliac spi nerves

Superior gluteal artery % \

Fig. 39-15 A, The bony origin ofthe glutcus maxtinus or the roughened area anterior to the posterior superior iliac crest is agood landmark and can be used as the caudal limit of bone removal. An imaginary plumb line dropped from the P.S.I.S. with tiie patient in the prone position will pass through the bony rim of the sciatic notch. The superior gluteal artery is adjacent to the bony rim. B, Alarge amount ofbone graft can be removed safely ifthe surgeon stays ccphalad to the RS.l.S., the sciatic notch and the imaginary line joining them.

Fourth lumar artery

lliolumbar artery Fig. 39-16 Illustration oftheanatomic positions of the arteries that may cause troublesome bleed i ing when working onthe inner table ofthe ilium.

Deep circumflex iliac artery

J ..-VVv ,;i I f Boiic Grafts and Iniplaiits in Spine Surgery 447 m

bloif'" first reported such complications alter a bone grafting procedure in which the posterior sacroiliac ligaments were postulated to be interrupted. The ensuing instability transferred the stress forces to the pelvic ring, causing fractures of the superior and inferior pubic rami. Cov entry and Tapper^" reported six cases of pelvic instability following removal of bone graft from the ilium. The patients with such instability often developed symptoms indistinguishable from other spinal disorders. History of clicking or thudding, as well as pain in the thigh and gluteal region, is characteristic. Fig. 39-21 The iliac wall is reconstructed with Sacroiliac stability is maintained by bone cement. formation of the sacrum as a keystone with interlocking eminences and depres sions, plus ligamentous support mostly in the posterior and superior aspect.'" Multiparous women with lax ligaments cl obstruction.Strangulated and anatomic variations in the sacroiliac hernia and valvulac arc very rare occur joints are more prone to develop such rences.^' Syniptoins were reported to pelvic instability. Radiologic examina have occurred from 24 days^' to 15 tion ofthe entire pelvic ring is important. years'""' after the formation of the iliac Changes in the sacroiliac joint, the pubic defect. rami, and the symphysis pubis should be Treatment requires the reduction of looked for. the hernia and repairing the defect by: a 1. Using soft tissue'-^'advance The Tibia ment, imbrication, flaps, or fascial Thc/i7;/V7 provides strong full thickness flaps cortical graft and is occasionally used in 2. Using a prosthesis"" (tantalum or spine fusion. The subcutaneous antero- Marlex mesh) medial aspect of the tibia is a convenient 3. Using methylmcthacrylatc cement donor site. The periosteum should be left to reconstruct the iliac wall"" (Figs. intact and sutured over the defect. The 39-19 to 39-21) condyles also supply cancellous bone. 4. The Bosworth technique:''" re However, there are significant risks to moving the remaining wings ofthe the use of the tibia as a donor site. Bio- ilium on cither side of the defect mechanically, it is changed from a closed followed by layered soft tissue clo- section to an open one when bone graft is obtained from the tibia. It is markedly weakened and much less able to resist Pclvic Instability torsional and bending loads. Removal of a large quantity of bone Frankel and Burstein''^ discussed the graft from the posterior ilium may dis effect of cortical graft removal from the rupt the mechanical keystone effect ofthe tibia. They described the torque and sacroiliac joint and the posterior sacro- angular deformation to failure ofthe tibia iliac ligament, causing instability. Licht- to be reduced to 30% of normal and

-a, WMiMMBtaCW'Wn < 448 Spine Surgery: An Anthology

energy absorption capacity to 10% of dent on the recipientbed forsurvival, and normal. Even when the corners of the their use is advantageous in poorly vascu cutout arc rounded, open section over larizcd bed after previous .surgery, shadows any reduction in stress concen trauma, infection or irradiation. The tration gained. fibula, rib, and anterior or posterior ilium Fatigue fractures arc relatively high, may be used. However, their application and the tibia should be cast immobilized is usually limited by the small size and from 6 to 12 months after bone graft is need for time-consuming highly special obtained." Thu.s the disadvantages of ized microvascular techniques. In special autogenous tibial graft far outweigh the circumstances the use offree vascularized benefits. bone graft may be advantageous in spine fusion. The Fibula Dupuis and coworkers" used a free Although the upper two thirds of the vascularizcd fibular graft in a case ofpro gressive congenital kyphosis with suc ; 1 fibula may be removed as bone graft, the middle one tliird provides the best cyl- cess, following the work ofO'Brien and indric cortical bone graft. The fibula graft Ostrup. In a similar situation, an avascu- isstrongest in resisting comprcssivc load lar strut graft becomes weaker to the ing and can be depended on for longer point of mechanical failure as it is re periods of structural support in interbody placed by creeping substitution, which fusion. For large defects in the vertebral may take two or more years to complete. bodies, fibula struts may be used to Muscle-pedicle bone grafting proce achieve stability. Because of the small dures were reported by Hartman and as amount ofcanccllous bone in the fibula, sociates for failed lumbosacral spinal fu iliac cancellous graft should be supple sion.''® An iliac crest autograft with an mented to enhance osteogcnesis. intact quadratus lumborum muscle pedi Peroneal nerve injuries may occur cle was used in this case. when obtaining the graft from the proxi mal one third of the fibula. Valgus de ALLOGRAFTS formity ofthe ankle is a serious risk when Allografts arc the most frequently used the lower one third is violated. Signifi alternatives to autografts in spine surgery. cant donor site pain and compartment They are bones transplanted from one syndrome have also been reported. individual to another and are used to cir Ribs have been used for thoracic spine cumvent the problems encountered with fusion. However, their modest cortex autografts. and porous cancellous bone are rarely ap Allografts are readily available and propriate for lumbar spine fusion. come in a wide variety of shapes and sizes. They can provide immediate sup Free Vascularizcd Bone Grafts port and minimize the use of stabilization Free vascularizcd bone grafts may be hardware or braces. Bone allografts can used to circumvent the disadvantage of replace missing structures and become large cortical grafts, most of which be incorporated into the spine. They pro come necrotic.'®'®" Recent progress in mi- videbiologicscaffolding that isgradually crosurgical techniques is making this pos replaced with the patient's own bone. sible.'"'"® Continuing circulation and in Major problems lead to decreased ef creased viability ofthe bone grafts facili fectiveness of allografts.Immu- tate the problem to that of fracture heal nologic rejection of implanted graft,®''"® ing. Vascularized grafts are less depen delayed union, nonunion, and fractureof Bone Grafts and Implants in Spine Surgery 449

the graft have not been uncommon. In bone is difficult. This form of freezing is corporation of allografts by the host is not advisable because ice crystals grow slower. Vascular penetration is slower rapidly in this temperature range and and less dense. There is less perivascular mechanically destroy the tissue viabil new bone formation when compared to ity.^' Freezing at —76® C is achieved in autografts. Transmission ofdisease from dry ice. At -60® C to -90® C using allografts is also a serious concern. a laboratory type of mechanical deep The major weakness of the allograft is freezer and at —150® C or colder using a that it is dead and cannot contribute di refrigerator with cryogenic gases, more rectly to osteogenesis, as do fresh auto effective preservation of boneis possible. grafts. Burwell'"' found a way around this At temperature near —70® C, ice crystal problem by combining the osteogenic formation is slower." Bones frozen to potential ofautogenous marrow with al —70® C have beenstored for several years lografts. The use ofautogenous marrow and successfully applied clinically.'*® to provide superior osteogenic capability Freezingin a cryoprotcctive agent such as in allografts and xenografts, as well as glycerol at controlled cooling velocity autografts, is finding greater clinical ap may be a more effective option. plication (see further discussion on xeno- Freeze-drying is a process in which the graft and synthetic implants). The use of bone is first frozen to —70® C and then bank bone is very advantageous ifstorage sublimated in liigh vacuum. The bone is problems, ininuinologic reactions, and freeze-dried until the water content is re infection could be eliminated. duced to 5% or less. The frccze-dricd The allograft must be aseptically ob bone graft then can beshipped andstored tained soon after death or properly steril conveniently at room temperature in ized and processed early to: definitely in a vacuum container. Since 1. Minimize its antigenicity freeze-dried bone is very brittle, it must 2. Prevent degradation by protcolytic be reconstituted by immersing in normal enzymes saline before use.'® The reconstitution 3. Maintain the mechanical structure time depends on the size andshapeofthe 4. Preserve the osteogenic induction graft. Chips of bone may not require any f property rehydration, whereaslarger corticalbone r« may require up to 24 hours for reconsti 'f. Freezing and Frecze-Drying tution."*® Freezing and freeze-drying are the As for their clinical application in spi most widely used preservation methods nalfusion, Malinin and Brown" reported that allow storageof bone in a biological the union rate of freeze-dried allografts ly useful (but nonviable) state.* under compression load (interbody or Freezing of allografts is carried out as strut grafts) not to be delayed by low ,v soon as possible after procurement. Cur grade imniunologic response. This is in 7 •: rently, the length ofsafestorage for bone contrast to a high incidence ofresorption • • is not known. However, ba.scd on the with cortical graft placed under tension knowledge of autolysis retardation by posteriorly in the spine. •J;:. cold, lower temperatures arc expected to •••I extend the "shelf life" ofallografts.'*^ At Bioniechanical Properties —15® C to —30® C, using a home typeof Biomechanical properties of bone mechanical freezer, long-term storage of grafts may be changed by the techniques used for preservation, although Sedlin's ^References 11, 43, 61, 62, 70. 71. study showed that freezing and thawing 450 Spine Surgery: An Anthohi^y

do not significantly change the mechani radiation (2 to 4 mcgarads) needed for cal properties of bone.'-"' sterilization or to destroy antigens, also Briglit and Burstein,^ as well as significantly impairs the inductive repair Triantafyllou and coworkers,'"® studied capacity of the bone graft.In the biomechanical properties of freezc- creased solubility of collagen and glyco- dried and irradiated bones. Komcnder"" saniinoglycan, destruction of bone ma found that freezing to —78° C docs not trix fibrillar network'^''® and discolora alter the mechanical properties of bone. tion^' of irradiated bone have been re Pelker and associates®" also concluded ported. In cobalt-60 irradiated bone Os- that freezing allograft bone to tempera trowski®" reported free radicals of un ture as low as that of liquid nitrogen usual stability to be present, although (—196° C) docs not significantly alter the their effect on the host tissue is unclear." biomechanical properties. They showed The effect of radiation on the biome that freeze-drying docs diminish the tor- chanical properties of bone is not well sional and bending strength but not the defined at this time. The effect seems to strength in compression. The data of be minimal with low level radiation. Pelker and coworkers indicate that frozen Radiation doses exceeding 3 megarads bones arc better suited than frceze-dricd arc known to destroy bone matrix fibril bones when they are subjected to tor- lar network.'^''" There appears to be sig sional loads.®"'®" nificant drop of breaking strength of Both frozen and frceze-dricd bones are bone with more than 3 megarads. This acceptable when comprcssive forces are effect is magnified when radiation is the primary concern. It must be remem combined with freeze-drying. Ko- bered that the initial biomechanical prop mcnder noted 6 megarads of radiation erties of the bone graft will change with reduced the strength in bending, com rcsorption, incorporation, and remodel pression, and torsion."" Irradiation of ing by the host. Surgical technique, inter frecze-dried bone with only 3 megarads nal fixation, and postoperative manage markedly diminished the bending ment must therefore be planned accord strength, but not the strength in com ingly. pression or torsion. Boiled bones have been used for graft Radiation, Heat, and material since the early part of this cen Chemical Treatment of Allografts tury.''" Although some good clinical re and Xenografts sults have been reported,""'"^''boiled allo Although most of the ascptically pro grafts and xenografts have generally pro cured cadaver bones do not require steril duced undesirable consequences. Boiling ization procedures, allografts or xeno destroys all inductive capacity.'^'' Heat grafts have been sterilized by physical may be intended to destroy transplanta means such as high energy radiation, and tion antigen, but it only denatures the heat (boiling, autoclaving); and by chem antigenic proteins into another unaccept icals such as merthiolate (Thimcrosol), able material. cthylene dioxide, Propiolactone, or using Autoclaving of contaminated bone antibiotic solutions. Some of these steril may be tempting to use in the operating ization methods were used in the past and room, but this produces haversian canal are discussed for historical interest only. coagulation and denaturation of bone Radiation ofat least 2 mcgarads is re protein,which severely retard host quired to kill bacteria; 4 megarads inacti incorporation. vates some viruses.^' The same dose of Chemical processing ofbone graft may

of: ^ n' Botw Grafts and Implants in Spine Surgery 451 present significant problems such as po is characterized as glycoprotcin(s). its tential carcinogencsis and difficulty of clinical application now is being eval penetration into bone. Propiolac- uated in the form of an injectable sub tone (1% solution) has been found to be stance linked to different delivery sys more bacteriocidal than cthylenedioxide, tems."'' which is more difficult to use.'" AAA bone is a chcmosterilized, auto- Merthiolate-treated grafts have in gen digested, antigen-extracted allograft de eral produced poor results; 30% of the veloped and clinically tested by Urist and grafts failed in the study by Reynolds and coworkers. It is an allogeneic bone of coworkers.'-'^ There appears to be three high osteogenetic property and low im- times as many failures as withautografts. munogenicity prepared in five basic Reduced callus formation and osteogene- steps. Urist believes that BMP is also pre sis have been noted. When the graft frac served by these measures. tured, there was minimal healing. When 1. Lipids and cell membrane lipopro- washed before use, no significant host teins are extracted using chloro- sensitivity to Merthiolate was noted in form-mcthanol. Merthiolate-treated bone graft.'' 2. Endogenous intra- and extracellular Bcnzalkonium chloride completely de transplantation antigens are re stroys osteogenic inductive capacity of moved by neutral phosphate buffer bone, according to Urist and asso autodigestion in the presence of ciates.'" Antibiotic solutions do not sulfhydral groupenzyme inhibitors penetrate completely into bone. Their to preserve BMP. germicidal effect inbone graft is variable. 3. Acid-soluble proteins are extracted In general, antibiotics appear to inhibit and matrix demineralized by 0.6 N the osteogenic inductive ,capacity of hydrochloric acid. bone.'''" 4. The bone is frceze-dried. Residual proteins including BMP are pre Bone Morphogenetic Protein served. Urist states that allograft bone must be 5. The processed AAA bone is stored removed from the donor within 4 to 8 in sterile double plastic envelope hours after death or within the minimal and outer vacuum-sealed glass con biodegradable time.'" Radiation sterili tainer. zation with more than two megarads, Urist and Dawson"" reported 40 inter- heating over 60° C, exposure to chem transverse process fusions in 36 cases of icals such as hydrogen peroxide, beta- degenerative joint and disc disease in propriolactone, bcnzalkonium chloride, cluding spinal stenosis and spondylolis- cryolysis, immediate freeze-drying, and thcsis, aswell as4 cases of thorocolumbar prolonged storage at 0° to 30° must be fracture dislocation. A composite of avoided to preserve the inductive prop AAA cortical bone strips and local auto- erties of the bone. Urist and coworkers logous bone was used in all cases. There have extensively studied osteogenic in were over 80% excellent and good results duction and discovered a bone morpho with a nonunion rate of 12%.

genetic protein (BMP) that is capable of XENOGRAFTS inducing the differentiation of host perivascular mesenchymalcells into cartilage Xenografts, or bones transplanted and bone."'' They have separated BMP from other species, have been used in from demineralized cortical bone and spine surgery.The application of osteosarcomas of man and mouse. BMP ivory,'"'"" animal horns,^"' corals,and

vf.rntK'w.

;?r- 452 Spine Surgery: An Anlhology

other exotic materials has been explored. fusions that failed. Biopsies of the Kiel Animal horns and ivory arc very resistant bone implants showed invasion by fi- blocl to incorporation into the host bone.®'' brous tissue. There was no ossification ^row Fresh xenograft bones have been shown and no incorporation into the surround 12-y. to be unacceptable. Invariably, they pro ing bone. Such deproteinized bone could paiie iinpl duce inflammation, fever, sequestration, be invaded by host new bone whenI resorption, or other manifestations ofre placed in excellent vascular bed with po undi jection.'^ Fibrous envelopment occurs as tentially osteogenic cells. When impreg 5-ye, over a metal plate. Even when fusion nated with autogenous bone marrow were takes place, sequestration of the xeno cells, it may prove to be an excellent 70% graft is observed. Urist believes that scaffolding with good bone conduction taint xenografts should not be used in pa- property.Salama®'' and Salama and sis s tients.'" coworkers"®'"® reported good results taiiu Bovine bones have been relatively using autogenous bone marrow-Kiel twet popular because they incorporate and bone composite grafts in patients. The with remodel with less difficulty.®'' Different red marrow can be easily aspirated from impi types ofpreserved bovine bone have been the patient's own iliac crest. tried since the nineteenth century. 1. Frozen calf bone SYNTHETIC IMPLANTS 2. Frceze-dried calf bone (Boplant)®' Synthetic implants can be prepared to syntl and fit any size or shape, but they have been subsi 3. Decalcifiedox bone'''' (as well as de- traditionally considered to be subject to Nen calcified calf and sheep bone) cval- wear and not biologically incorporated impl uated experimentally and clinically, into the host bone.'^ A number of im react but found unsatisfactory plants fashioned from metals have been actio Deproteinized xenografts, including "os triedasreplacement for bonein thespinal the I purim," "anorganic bone," "Oswestry tanium vertebral replacement: "Total been tried. Vertebral Body and Pedicle Replace- nient"'"''''"^'). bone from freshly killed calf, sterilized Metal* scajfoldsJ with the shape of bone either by cthylenc dioxide or by gamma being replaced may be covered by radiation, has been commercially avail- ground autologous bone grafts of small able. Experimental studies showed that it particle size. In animal experiments in is very weakly antigcnic and does not growth of bone occurred over the total possess active bone-inducing capacity.®® surface area of fiber metal implants and Since its introduction in 1957, Kiel bone bone penetrated deep into the compo- has been used in almost every possible site.^ bone graft site, and varying success rates Titaiiiitni mesh implants have been din- were have been reported clinically. ically applied by Lcong,®^-^'' and cowork- be b In spinal fusion, Jackson'^"' noted that crs for anterior spinal fusion after discec- bone Kiel bone implantbecame surroundedby tomy in the lumbar spine. This porous to CO autogenous bone with time. For larger implantallows ingrowth of bone andap Tl- defects he recommended the use ofauto- pears to obviate the use ofbone graft. It that 1 genous and Kiel bone composite. Mc- acts as a spacer and can provide imme are i Murray'® presented clinical, radiologic, diate stability, while allowing time for bone and histologic data on the fate of Kiel the slow ingrowth ofbone and long-term conn bone implants in four anterior spinal stability. and \ Experimentally, porous titanium mesh of toxicologic liabilities."*' They are blocks with a 50'/o void allows rapid in shown to be superior to biodegradable growth of bone in canine long bone. A polymers, such as polylactic acid and 12-ycar follow up was possible in two polyclycolic acid, wliich have been con patients who are asymptomatic, and the sidered as bone substitutes.^"'"'' The im implants have remained unchanged and plants may be in dense form or porous. Lindisplaced; 10 patients had more than The minimum pore size for ingrowth of 5-year follow up. Of these, seven patients bone is shown to be 100 /Am."** Corals were asymptomatic, two had more than provide such porous structures.'"'"^ 70% symptomatic relief, and one re Holmes and coworkers'''' performed tained avery stifTback. Radiologic analy histologic and biomechanical studies in sis showed that disc height was main dogs using hydroxyapatite converted tained at 5 years with no movement be from sea coral calcite as bone substitute. tween the adjacent vertebral bodies, often The material was incorporated in bone •• with bony overgrowth anterior to the and became almost as strong as the native implant. bone. They also reported encouraging clinical application with fractures in 18 Nonmctallic Synthetic Implants patients. There is a growing number of other Another material, Replam Hydroxy- synthetic implants being used as bone apatite-Poritcs (RH AP). is aceramic with i ^ substitutes. According to Osborn and three-dimensional interconnected porous Nemcsley"''^ the chemical nature of the material of calcium hydroxyapatite from implant determines the biodynamics and the exoskeleton ofporitcs (coral). It may reaction of the recipient bed in the inter be carved by the surgeon before implant action with living bone. They considered ing. RHAP was approved for evaluation the following materials. in spinal fusion in several centers under 1. Bone cement and stainless steel as Mooney and associates. (See Chapter 41.) biotolawU, resulting in distance osteo- Bioactive and biodegradable porous genesis with a fibrous layer separat ceramics ofhydroxyapatite or tricalcium ing the implant from bone phosphate have been studied. Jarcho' 2. Alumina and carbon materials as stated that they are usually well tolerated bioincrl, resulting in contact ostco- and become chemically bonded to bone genesis by natural bone-cementing mechanisms. 3. Glass ceramic, calcium phosphate Porous hydroxyapatite ceramics have ceramics and hydroxyapatite ce been used in dog experiments for the ramicsasbioactiue, resultingin bond spinc^" and other skeletal defects. Porous ing osteogenesis ceramics and autologous marrow com Bioinert porous ceramics of alumina posites were studied by Nade and asso wore noted by Bcnum and associates to ciates." Porous alumina, calcium alum- be bound to bone by the ingrowth of inate, calcium hydroxyapatite, and trical bone 3 to 4 mm thick in regions exposed cium phosphate were placed with bone to compressive forces. marrow into intermuscular sites. Bone Thus far, evidence strongly suggests was found to adhere to the ceramics and that porous calcium phosphate ceramics to penetrate the interior if the pore size are the most biocompatible synthetic were greater than 100 ^m. The marrow bone substitute with the ability to be cells were shownto play asignificant part come chemically bonded by living bone in new bone formation into the frame and with a chemical composition devoid work. Nade and coworkers believe that

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. : I* • J 454 Spine Surgery: An Anthology

the appropriate liistocoiupatible biode lanto-axial subluxation, and cervical gradable ceramic material would act as a spondylosis. He also stabilized the lum scaffold by virtue of its porosity for re bar spine using the cement in one patient tention of bone marrow cells, and pro with disc disease. Scoville and cowork- vide mechanical strength, while bone in ers"'^ reported the use of acrylicplastic for growth is progressing. This type of bone vertebral replacement or fixation in met- substitute would also allow a wide se astatic tumor destruction of the spine. lection of sizes and shapes in sterile In recent years the clinical use of form. methylmethacrylate cement for spine sta Porous biodegradable ceramic and bilization has become more popular. BMP composites were evaluated by Harrington''" documented the use of Urist and coworkers."'^ They reported methylmethacrylate for vertebral body that an aggregate of B-tricalcium phos replacement and anterior stabilization of phate and bone morphogenetic protein the spine with metastatic tumor. His se (TCP/BMP) induced the differentiation ries included 14 patients treated by an ofcartilage in 8 days and in lamella bone terior decompression and stabilization in 21 days. The yield of new bone was using metal and the bone cement. more than 12 times greater from the The strength ofmethylmethacrylate is TCP/BMP than from the BMP alone, it about one half that ofbone.'" Attempts is possible that a porous ceramic acts as a have been made to strengthen the cement slow-release delivery system to distribute by adding fibers," but clinical data arc BMP more favorably and to potentiate its still unavailable. After polymerization, activity. methylmethacrylate becomes a rigid and Calcium phosphate-coated metallic brittle solid that can withstand significant implants showed superior bone-bonding compression. However, it fails under characteristics according to Ducheync tension or shear forces. It is reasonable to and associates.^" Such implants may solve use it in replacement of vertebral body the problem of weak mechanical strength where compression is the predominant of ceramics, particularly the porousones. force present. It is important to remem Ceramic implants by themselves are ber that when used alone the outer part of probably unsuitable for restoration that the cement mass is still subject to tension would have to withstand significant im when bending and will fail with time in a pact, or torsional or bending stresses,''" as clinical setting. The primary indication in the spinal column. for application of methylmethacrylate in Calcium phosphate-containing bone spinal stabilization is in patients with ma cements are also being developed.''"'" lignant disease and limited life expec Recently, calcium hydroxyapatite in tancy.""'^" Itshouldnot beexpected to pro powder form was used as an expander of vide long-term support of the spine."'

. ' k a patient's own cancellous bone graft. It In the spinal column, methylmeth -i has been used in spine fusion, especially acrylate cement should be used with se -j in children, when there is insufficient cure metal fixation such as the Dunn,""-""'"" autologous bone graft available.""® Harrington, Luquc, Steffee,or other instrumentation. It may be used as METHYLMETHACRYLATE reinforcement for screws and hooks in CEMENT cancellous bone. The cement docs en Knight"" was the first to report the use hance fixation of implants by increasing ofacrylic cement to fix the cervical spines the contact area, especially in osteo- with chronic fracture dislocation, at- porotic bone.

T'.: Bone Grafts and Implants in Spine Sin^i^cry 455

REFERENCES 17. Burwell, R.G.: The fate of bone grafts. In Apley, A.G., editor: Recent advances in 1. Albrcktssoii, 1.: The healing of autologoiis orthopaedics, 1969, Baltimore, Williams & bone grafts after varying degrees of surgical Wilkins. traiinia.J. DoneJoint Surg. 623:403, I'JbO. 18. Burwell, G.R.: The fate of freeze-dried bone 2. Anderssoii, G.D.j., etal.: Seginental replace allografts. Transplant Broc. (Suppl. 1) 8:95, ment of the femur in baboons wiili fiber 1976. metal implants and autologoiis bonegrafts of 19. Burwell, R.G.: The function of bone mar different particle size, Acta Ortliop. Scand. row in the incorporation of a bone graft, 53:349, 1982. Clin. Orthop. 200:125, 1985. 3. Dassctt, C.A.L.:Clinical implications of cell 20. Cameron, H.U.: Evaluation of a biodegrad >« r i. - function in bone grafting, Clin. Orthop. ableceramic,J. Biomed. Mater. Res. 11:179, 87:45. 1972. 1977. 4. Denum, 1'., et al.: Porous ceramics as a bone 21. Challis, J.H., et al.: Strangulated lumbar substitute in the medial condyle of the tibia: hernia and volvulus following removal of an experimental study in sheep: long-term iliac crest bone graft, Acta Orthop. Scand. observations, Acta Orthop. Scand. 48:150, 46:230, 1975. r 1977. 22. Chalmers, J., and Rush.J.: Observations on 5. Dlakemore, M.E.: Fractures at cancellous the induction of bone in soft tissues, J. Bone bone graft donor sites, Injury 14:519, 1983. Joint Surg. 573:36, 1975. 6. Donfiglio, M., and Jetter, W.S.: Imimino- 23. Cobey, M.L.: A national bone banksurvey, logicai response to bone, Clin. Orthop. Clin. Orthop. 110:333, 1975. 87:19, 1972. 24. Cockin, J.: Autologoiis bone grafting— 7. Bosworth, D.M.: Repair of herniae through complications at thedonor site,J. Bonejoint iliac crest defects, J. Bone joint Surii. 37A: Surg. 533:153, 1971. 1069, 1955. 25. Cooper, J.W.: Cluneal nerve injury and 8. Bright, R., and Burstein, A.: Material pro chronic post-surgical neuritis, J. BoneJoint perties of preserved cortical bone. Trans. Surg. 49A:199, 1967. Orthop. Res. Soc. 3:210, 1978. 26. Coventry, M.B., and Tapper, E.M.: Pelvic 9. Brown, K.L.B., and Cruess, R.L.: Bone and instability: a consequence of removing iliac cartilage transplantation in orthopaedic sur bone for grafting, J. Bonejoint Surg. 54A:

gery, J. Bone Joint Surg. 64A:270, 1982. 83, 1972. " n 1^. 10. Brown, L.T.; The mechanics of the lumbo- 27. Cowlcy, S.P., and Anderson, L.D.: Brief sacral and sacro-iliac joints, J. Bone Joint note: hernias through donor sites for iliac- Surg. 19:770, 1937. bonc grafts, J. Bonejoint Surg. 65A:1023, 11. Brown, M.D., et al.: A rocntgenographic 1983. evaluation of frozen allografts versus auto- 28. Curtiss, P.H., et al.: Immunological factors graftsin anteriorcervical spinefusions, Clin. in homologous bonetransplantation, J. Bone Orthop. 119:231, 1976. Joint Surg. 41A:148i, 1959. 12. Burchardt, H.: The biology of bone graft 29. Dawson, E.: The fate ofbone substitution repair, Clin. Orthop. 174:28, 1983. with porous hydroxyapatite implants in the 13. Burchardt, H., et al.: Frceze-dried allogenic dog spine. Transactions of the 27th Annual segniental cortical-bonc grafts in dogs, J. Meeting, Orthopaedic Research SocietyVol. Bone Joint Surg. 60A:1082, 1978. 6, 1981. 14. Burwell, R.G.: Astudyof homologous can 30. Ducheyne, P.,et al.:Effectofhydroxyapatite cellous bone combined withautologoiis red impregnation on skeletal bonding of porous marrow after transplantation to a muscular coated implants, j. Biomed. Mater. Res. 14: site, J. Anat. 95:613, 1961. 225, 1980. 15. Burwell, R.G.: Studies in the transplantation 31. Dunn, E.J.: The role of methylmethacrylate of bone. V. The capacityoffresh and treated in the stabilization and replacement of tu homografts of bone to evoke transplantation mors of the cervical spine,Spine 2:15, 1977. immunity, J. Bone Joint Surg. 453:386, 32. Dunn, H.K.: Internal fixation ofthe spine— 1963. a new implant system: proceedings of the 16. Burwell, R.G,; .Studies in transplantation of Scolio.si.s Research Society. Orthop. Trans. ,1 ^ o bone. Vlll. 'I'reated composite hoino-auto- 3:47, 1979. grafts t)fcancellous bone, J. BoneJoint Surg. 483:532. 1966.

|4|p jiiniDmiiii'wiiitim 456 Spine Surgery: An Anthology

33. Dunn, H.K., ctal.: Coinpamtivc a.sscssinciit of spine stability acliicvcd with a new ante 49. Hartman, j.R., ctal.: Apedicle bone grafting rior spine fixation system. Trans. Orcliop. procedure for failed lumbosacral spinal Ucs. Soc. 5:192, 1980. fusion, Clin. Orthop. 178:223, 1983. 34. Dupuis. P.H., ct nl.: Anterior free vascular 50. Heiple, K.G., et al.: Acomparative study of transplant of the fibula for tiie treatment of the healing process following different types kypliosis, J. Bone Joint Surg. 64B:259, 1982. ofbone transplantation, J. Bone joint Surg 35. Drury, B.J.: Clinical evaluation ofback and 45A:1593, 1963. leg pain due to irritation of the superior 51. Heppenstall, R.B.: Fracture treatment and cluneal nerve, J. Bone joint Sure. 49A:199 healing, Philadelphia, 1980, W.B. Saunders Co. 1967. 36. Editorial. Bone harvesting and transplanta 52. Holmes, R.E.: Bone regeneration within a tion, Lancet 2:730, 1981. coraline hydroxyapatitc implant, Plast. Rc- 37. Edmoiison, A.S.. et al.: Campbell's opera constr. Surg. 63:626, 1979. tive orthopaedies, ed. 6,St. Louis. 1980, The 53. Holmes, R., ct al.: Acoralline hydroxyapa C.V. Mosby Co. titc bone graft substitute: preliminary report, 38. Eftelchar, N.S., and Thurston, C.W.: Effect Clin. Orthop. 188:252, 1984. ofirradiation on acrylic cement with special 54. Hughes, C.W.; Rate ofabsorption and callus reference to fixation of pathological frac stimulating properties ofcow horn, ivory, tures, j. Biomech. 8:53, 1975, beef bone and autogenous bone, Surg. Gync- 39. Enncking, W.F., et al.: Autogenous cortical col. Obstet. 76:665, 1943. bone grafts mthe reconstruction ofsegmen- 55. Jackson j.W.: Surgical approaches to the an terior aspect of the spinal column, Ann. R. 1 tal skeletal defects, J. Bone joint Surg. 62A: Coll. Surg. Engl. 48:83, 1971. 1039, 1980. 40. Escalas. F.. and Dewald, ll.L.: Combined 56. jarcho, M.: Calcium phosphate ceramics as traumatic arteriovenous fistula and ureteral hard trssue prosthctics, Clin. Orthop 157- 259, 1981. injury: acomplication of iliac bone-grafting, 57. Kahn, B.: Superior gluteal artery laceration: a case report, j. Bone Joint Surg. 59A:270 a complication of iliac bone graft surgery, 1977. 41. Evarts, C.M.: Surgery ofthe musculo.skele- Clin. Ortluip. 140:204, 1979. t.-il system. New York, 1983, Churchill Liv 58. KIawitter,J.J.,andHulbcrt,S.F.:Application ofporous ceramics for the attachment ofload ingstone, Inc. 42. Frankei, V.H., and Burstein, A.H.: Ortho bearing orthopaedic applications, j.Biomcd. Mater. Res. 2:161, 1971. pedic Biomechanics, Philadelphia, 1970, Lea 59. Knight, G.: Paraspinal acrylic inlays in the & Febigcr. 43. Friedlacnder, G.E.: Current concepts re treatment ofcervical and lumbar spondylosis and other conditions. Lancet 2:147, 1959. view—Bone-banking, j, Bone joint Surg. 60. Komender, A.: Influence ofpreservation on 64A:307, 1982. 44. Fnedlander, G.; Autigenicity offrecze-dricd some mechanical properties of human haversian bone. Mater. Mcd. Pol. 8:13, 1976. allografts. Transplant Proc. (Suppl 1)8-195 61. Kreuz, F.P., etal.: The preservation and clin 1976, 45. Froimson, A.I., and Cummings, A.G., jr.: ical use offreeze-dricd bone, j. Bone Joint Surg. 33A:297, 1974. lhac hernia following hip arthrodc.sis, Clin 62. Langer, F., et al.: The immuncgenicity of Orthop. 30:89, 1971. 46. Gallic, W.E,; The use of boiled bone in op fresh and frozen allogeneic bone, J. Bone Joint Surg. 57A:216, 1975. erative surgery, Am. j. Orthop. Surg 16: 63. Leong, J.C.Y., ct al.; The use ofporous tita 373, 1918. 47. Gupta, 13.,etal.:Bridging large bone defects nium mesh implant after discectomy in pa with a xenograft composited with auto- tients with deranged lumbar intervertebral logous bone marrow: an experimental study disc The five-year results ofaprospective Int. Orthop. (SICOT) 6:79, 1982. trial, (abstracts). Twelfth annual meeting 48. Harrington, K. O.: The u.sc ofmethylmeth- ofthe International Society for the Study of acrylate for vertebral btidy replacement and the Lumbar Spine, 1985. anterior stabilization ofpathological fracture 64. Leong, J.C.Y.: University ofHong Kong, Personal communication, 1984. dislocations of the spine, due to metastatic 65. Uchtblau, S.: Dislocation of the sacro-iliac disease, j. Bone Joint Surg. 63A:36, 1981. joint: a complication of bone-grafting, J. Bone Joint Surg. 44A:193, 1962. UVIIL > '

66. Lloyd-Robcrts, G.C.: Experiences with 80. Oldfield, M.D.: Iliac hernia after bone graft boiled cadaveric bone, J. BoneJoint Surg. ing, Lancet 248:810, 1945. 34B;428, 1952. 81. Osborn, J.F., and Newescly, H.: Dynamic 67. Lotein, M., ct al.: Lumbar hernia at an iliac aspects ofthe implant-bone-interface. Dental bone graft donor site: A case report. Clin. Implants 111:123, 1980. Ortliop. 80:130, 1971. 82. Osborn, J.F., and Newescly, H.: The mate 68. Liibitky, J.R, and Dewald, R.L.: Methyl- rial science of calcium phosphate ceramics, inethacrylatc reconstruction of large ihac Biomaterials 1:108, 1980. crest bone defect donor site, Clin. Orthop. 83. Ostrowski, K.: Current problems of tissue 164:252. 1982. banking. Transplant. I'roc. 1:126, 1969. 683. Luque, E.R.: Personal communication, 84. Pappas, A.M.: Current methods offreezing and freeze-drying. Cryobiology 4:358,1968. 1985. 69. Magnusson, P.B.; Holding fractures with 85. Pelker, R.R., et al.: Biomechanical proper absorbable materials—ivory plates and ties ofbone allografts, Clin. Orthop. 174:54, screws, JAMA 61:1514, 1913. 1983. 70. Malinin, T.I.: University of Miami tissue 86. Pelker, R., et al.: The effects of preservation bank: collection of postmortem tissues for on allograft strength, Trans. Orthop. Res. clinical use and laboratory investigation. Soc. 7:283, 1982. Transplant. Proc. (Suppl.) 8:53, 1976. 87. Pierson, A.P., et al.: Bone grafting with 71. Malinin, T.I.: Cadaver bone allografts— Boplant: results in thirty-three cases, J. Bone bone banks. InTurek, S.L., editor: Ortho Joint Surg. 50B:364, 1968. paedics, principles and their application, 88. Pyrtek, L.J., and Kelly, C.C.: Management Philadelphia, 1984, J.B. Lippincott Co. ofherniation through large iliac bone defects, Ann. Surg. 152:998, 1960. 72. Malinin, T.I., and Brown, M.D.: Bone allograft in spinal surgery, Clin. Orthop. 154: 89. Ray, R.D.: Vascularization of bone grafts 168, 1981. and implants, Clin. Orthop. 87:43, 1972. 73. McMurray, G.N.: The evaluation of Kiel 90. Ray. R.D., and Holloway, J.A.: Bone im bone in spinal fusions, J. Bone Joint Surg. plants, J. Bone Joint Surg. 39A:1119, 1957. 64B:100, 1982. 91. Rcid, R.L.: Hernia through an iliac bone- 74. Mittelmeicr, J.H., ct al.: PMMA cement graft donor site: a case report, J. Bone Joint Surg. 50A:757, 1968. with carbon fiber reinforcement and apatite ingredients; mechanical properties and tissue 92. Reynold, C.F., ct al.: Clinical evaluation of reaction in animal tests. First World Biomat. the inerthiolate bone bank and homogenous Cong., Baden, Austria, 1980. bone grafts, J. Bone Joint Surg. 33A:873, 75. Moore, J.B., et al.: A biomechanical com 1951. parison of vascularized and conventional 93. Rhinelander, F.W.: Tibial blood supply in autogenous bone grafts, Plast. Reconstr. relation to fracture healing, Clin. Orthop. Surg. 73:382, 1984. 105:34, 1974. 76. Murray, J.A., ct al.: Irradiation of poly- 94. Salama, R.: Xcnogeneic bone grafting in inethylmethacrylate: in vitro Gamma Radia humans, Clin. Orthop. 174:113, 1983. tion Effect, J. Bone Joint Surg. S6A:311, 95. Salama. R., ct al.: Re-combined grafts of bone and marrow, J. Bone Joint Surg. 55B: 1974. 77. Nade, S.. ct al.: Osteogencsis and bonemar 402, 1973. row transplantation, the ability of ceramic 96. Salama, R., and Wcissman, S.L.: The clinical materials to sustain osteogencsisfrom trans use of combined xcnografts of bone and planted bone marrow cells: preliminary stud autologous red marrow: a preliminary re ies, Clin. Orthop. 181:255, 1983. port, J. Bone Joint Surg. 60B:111, 1978. 78. Nade, S., and Burwell, R.G.: Decalcified 97. Scoville, W.B., ctal.: The use ofacrylic plas bone as a substrate for osteogencsis: an ap tic for vertebral replacement or fixation in praisal ofthe inter-relation ofbone and mar metastatic diseaseofthe spine, J. Neurosurg. row in combined grafts, J. Bone Joint Surg. 27:274, 1967. 59B:189, 1977. 98. Scdlin, E.: A rhcologic model for cortical 79. Oikarincn, J., and Korhonen, L.K.: The bone, Acta Orthop. Scaiid. (Suppl.) 36:83, bone inductive capacity of various bone 1965. transplanting materials used for treatment of 99. Seres, J.L.: Fusion in the presence ofsevere experimental bone defects, Clin. Orthop. metastatic destruction of the cervical spine (case report), J. Neurosurg. 28:592, 1968. 140:208, 1979.

^ i i t. -miv f-Ki"-Of 458 Spific Surgety: An Anthology

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