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CHAPTER 33/OPERATIVE TREATMENT OF ANTERIOR PROCEDURES / 333
cancellous allograft with supplemental posterior stabilization (17). One hundred percent of the one level and
93% of the two level fusion were solid radiographically
on follow-up. Allograft bone provided improved compressive strength but required more time for incorporation compared to autograft bone (18). At our institution,
stand alone allograft ALIFs are not performed without
supplemental posterior instrumentation.
Within the past decade, cages have been popularized for
performing ALIF. Cages were initially introduced by Bagb y
for the treatment of wobbler’s disease in horses in 1977.
Multiple modifications of the original cage design have
been made since 1988. The BAK cage, Ray Cage, and
Interfix Device are all cylindrical cages that are packed
with bone graft. Two cylindrical cages are inserted in the
interspace and give excellent overall stability (Fig. 33-2).
A
C
FIG. 33-2. A: Lateral X-ray of the lumbar spine illustrating a disc space narrowing at L4-5. B: Sagittal
T2-weighted magnetic resonance image of the same patient showing decreased height and disc hydration consistent with degenerative disc disease.C: Lateral X-ray findings after a anterior interbody fusion
using two cylindrical cages. D: Antero-posterior view of the cage construct seen in C.
B
D
334 /SECTION V/SPECIFIC CLINICAL ENTITIES
Tapered threaded devices are also available and have the
theoretical advantage of improved lordosis and anatomic
alignment.
Cages have been sho wn to increase the stability of ALIF.
In reviewing five types of cages, Tsantrizos concluded that
cages decreased the range of motion at the interspace by an
average of 63% in flexion and extension, 69% in lateral
bending, and 23% in axial rotation (11). Cages have other
advantages compared to other fusion methods. In a sheep
study by Sandhu et al., a lower subsidence rate was shown
with cages compared to autograft alone (19). Compared to
PLF, ALIF using cages increases the axial stiffness of the
interspace by 80% (compared to 40% seen in PLF). Moreover, higher nonunion rates have been reported with the
PLF compared with ALIF (11). The increased stability is
likely a function of increased disc space distraction seen
with cage placement versus bone grafting alone.
The design of the cage also contributes to its stability.
Cages with sharp teeth were found to exhibit higher pullout
forces (20,21). Flexible cages constructed with carbon fiber
reduce stress shielding of the bone graft. Stiffer cage constructs transmit less stress to the bone graft and the stress
shielding effect of stiff cages may have a deleterious effect
on bone graft incorporation (Fig. 33-3) (22).
The results of interbody fusion with cages have been
reported in two Food and Drug Administration studies.
Anterior lumbar interbody fusion was evaluated by Kuslich using the bar cage in 1998. Nine hundred forty-seven
patients underwent ALIF using the B AK cage in that multicenter study. Bony fusion was noted in 86% of patients
at 12 months, 91% at 24 months, and 98% at 3 years after
surgery. More than 85% of the patients reported pain
reduction and 91% had improved function by 24 months
postsurgery. Seventy-eight percent of the employable
patients were working at 24 months and 91% at 3 years
after surgery (5). In 1997, Ray reported on 236 undergoing PLIF using the Ray cage. In this prospective study,
functional improvement was excellent in 40%, good in
21%, fair in 21%, and poor in 14% of the subjects. The
complication rate was less than 1%.
Kleeman reported on the use of bone morphogenetic
protein (BMP) in laparoscopic ALIF. Using computed
tomography and X-ray evaluation at 6 and 12 months
postoperatively, he found that 100% of 22 patients were
fused (23). Furthermore, all of the subjects were satisfied
with the treatment at 12 months with relief of back pain
and improved leg symptoms.
Currently, artif icial disc replacement (ADR) is being
evaluated for the treatment of lumbar DDD. Preliminary
results in the United States and long-term results from
Europe are encouraging. The advantage of ADR is that it
allows motion at the involved level compared to fusion
surgery and decreases stress on adjacent level with a
hypothetical decrease in future adjacent level disease.
One artificial disc is composed of cobalt-chrome alloy
end plate elements, and an ultra–high molecular weight
polyethylene inlay element. The disc functions based on
the ball-and-socket joint principle (Fig. 33-4).
Multiple variations of the anterior approach are available for ALIF, including mini-open, endoscopic assisted,
A
FIG. 33-3. A: The growth of bone through a
cage confirming fusion. B: Histologic confirmation of bone growth across the cage.
B
A,B
CHAPTER 33/OPERATIVE TREATMENT OF ANTERIOR PROCEDURES / 335
FIG. 33-4. A: Lateral X-ray of the lumbar spine with severe degenerative disc
disease with collapse disc space at L4-
5. B: T2 sequence sagittal magnetic
resonance image confirming the degeneration of the L4-5 disc with collapse of
the interspace.C: Lateral X-ray showing
a patient with an artificial disc replacement with restoration of the disc height
and preservation of lumbar lordosis. D:
Anteroposterior view of the artificial disc
replacement confirming central placement of the device. E: Image of the artificial disc replacement.
C,D
or microsurgically assisted (24–26). The most common
surgical method is the retroperitoneal lumbar approach
for anterior discectomy with interbody fusion. The
retroperitoneal or transperitoneal approach can be used
with minimal morbidity from extensive dissection of
muscle, as seen with posterior procedures.
Multiple investigators have reported good results
with laparoscopic ALIF (23,27). Regan compared
laparoscopic with open ALIF with the BAK cage in a
multicenter study (28). The laparoscopy group had a
shorter hospital stay and reduced blood loss but
increase operative time. T en percent of the cases needed
E
to be converted to an open procedure. However, complication rates were comparable between open and
laparoscopic procedure.
The laparoscopic approach at L4-5 interval is more
challenging than at the L5-S1 level. Zdeblick compared
the mini-open and laparoscopic approach in 50 consecutive patients undergoing ALIF at L4-5. He found that the
rate of complications was significantly higher with the
laparoscopic procedure (20% versus 4%). The operative
time was 25 minutes longer for the laparoscopic group;
furthermore, 16% of the laparoscopic group had inadequate exposure for the placement of two cages.
336 /SECTION V/SPECIFIC CLINICAL ENTITIES
The anterior retroperitoneal approach can be complicated by venous injury requiring repair as well as development of subsequent thrombosis. Arterial occlusion of
the internal iliac artery has also been reported (29).
Patients that present with ongoing leg pain and weakness
in a nondermatomal distribution following ALIF should
be evaluated for iliac vessel thrombosis (30).
Complications are associated with the ALIF procedures. Bone graft collapse or extrusion and cage malposition or migration can result in poor alignment and
pseudoarthrosis. Iliac crest bone graft donor site morbidity has been reported in up to 30% of patients that may
last for years (11,16). Moreover, allograft bone has the
potential for disease transmission and immunologic reaction. The risk of HIV infection, for example, has been
estimated at less than 1/1,000,000 in properly screened
donors (31).
Retrograde ejaculation results form injury to the superior hypogastric plexus. This plexus is responsible for
bladder neck closure during ejaculation. Retrograde ejaculation has been reported in as many as 8% of patients
with ALIF (32). In a review of 4,500 patients, 0.42% of
patients experienced retrograde ejaculation (33). Regan
found an incidence of retrograde ejaculation in 2.3% of
his open versus 5.1% of his laparoscopic ALIF cases.
Fifty percent of the patients had resolution of their symptoms at follow-up. Other rare complications reported in
ALIF include pituitary apoplexy , urethral injury, and pancreatitis (29,34,35).
In summary, the disc may be a significant cause of
chronic low back pain in degenerative disc disease. One
surgical option for DDD is anterior lumbar interbody
fusion using bone graft or substitutes with or without
cage instrumentation. The anterior approach has multiple
advantages over posterior procedures, including the
avoidance of muscle dissection, excellent restoration of
the disc space height and neuroforaminal decompression,
and improved biomechanics. New technologies, such as
BMP and ADR, ha v e decreased the risk of iliac crest graft
site morbidity and adjacent level disease.
REFERENCES
1. Freemont AJ, Peacock TE, Goupille P, et al. Nerve ingrowth into diseased intervertebral disc in chronic back pain. Lancet 1997;350(9072):
178–181.
2. Colhoun E, McCall IW, Williams L, et al. Provocation discography as
a guide to planning operations on the spine. J Bone Joint Surg (Britain)
1988;70(2):267–271.
3. Turner JA, Ersek M, Herron L, et al. Patient outcomes after lumbar
spinal fusions. JAMA 1992;268(7):907–911.
4. Barrick WT, Schofferman JA, Reynolds JB, et al. Anterior lumbar
fusion improves disco genic pain at levels of prior posterolateral fusion.
Spine 2000;25(7):853–857.
5. Kuslich SD, Ulstrom CL, Griffith SL, et al. The Bagby and Kuslich
method of lumbar interbody fusion. History, techniques, and 2-year
follow-up results of a United States prospective, multicenter trial.
Spine 1998;23(11):1267–1278; discussion 1279.
6. Vamvanij V, Fredrickson BE, Thorpe JM, et al. Surgical treatment of
internal disc disruption: an outcome study of four fusion techniques. J
Spinal Disord 1998;11(5):375–382.
7. Cloward RB. Spondylolisthesis: treatment by laminectomy and posterior interbody fusion. Clin Orthop 1981;(154):74–82.
8. Cloward RB. Lesions of the intervertebral discs and their treatment by
interbody fusion methods. The painful disc. Clin Orthop 1963;27(51).
9. Harmon PH. Anterior excision and vertebral body fusion operation for
intervertebral disc syndromes of the lower lumbar spine. Clin Orthop
Rel Res 1963;107–127.
10. Crock HV. Anterior lumbar interbody fusion: indications for its use and
notes on surgical technique. Clin Orthop 1982;(165):157–163.
11. Tsantrizos A, Andreou A, Aebi M, et al. Biomechanical stability of five
stand-alone anterior lumbar interbody fusion constructs. Eur Spine J
2000;9(1):14–22.
12. Penta M, F raser RD. Anterior lumbar interbody fusion. A minimum 10year follow-up. Spine 1997;22(20):2429–2434.
13. Soini J. Lumbar disc space heights after external f ixation and anterior
interbody fusion: a prospective 2-year follow-up of clinical and radiographic results. J Spinal Disord 1994;7(6):487–494.
14. Kumar A, Kozak JA, Doherty BJ, et al. Interspace distraction and graft
subsidence after anterior lumbar fusion with femoral strut allograft.
Spine 1993;18(16):2393–2400.
15. Patel S, Timon S, Dawson EG, et al. Anterior lumbar discectomy and
fusion using femoral ring allografts. Presented at the American Academy of Orthopaedic Surgeons annual meeting. Februar y 13–17, 2002.
Dallas, TX, 2002.
16. Wimmer C, Krismer M, Gluch H, et al. Autogenic versus allogenic
bone grafts in anterior lumbar interbody fusion. Clin Orthop 1999;
(360):122–126.
17. Sarwat AM, O’Brien JP, Renton P, et al. The use of allo graft (and av oidance of autograft) in anterior lumbar interbody fusion: a critical analysis. Eur Spine J 2001;10(3):237–2341.
18. Aaron AD, Wiedel JD . Allograft use in orthopedic surgery. Orthopedics
1994;17(1):41–48.
19. Sandhu HS, Turner S, Kabo JM, et al. Distractive properties of a
threaded interbody fusion device. An in vivo model. Spine 1996;21
(10):1201–1210.
20. Lund T, Oxland TR, Jost B, et al. Interbody cage stabilisation in the
lumbar spine: biomechanical evaluation of cage design, posterior
instrumentation and bone density. J Bone Joint Surg Br 1998;80
(2):351–359.
21. Pilliar RM, Lee JM, Maniatopoulos C. Observations on the effect of
movement on bone ingrowth into porous-surfaced implants. Clin
Orthop 1986;(208):108–113.
22. Martz EO, Goel VK, Pope MH, et al. Materials and design of spinal
implants—a review. J Biomed Mater Res 1997;38(3):267–288.
23. Kleeman TJ, Ahn UM, Talbot-Kleeman A. Laparoscopic anterior lumbar interbody fusion with rhBMP-2: a prospective study of clinical and
radiographic outcomes. Spine 2001;26(24):2751–2756.
24. Boos N, Kalberer F, Schoeb O. Retroperitoneal endoscopically assisted
minilaparotomy for anterior lumbar interbody fusion: technical feasibility and complications. Spine 2001;26(2):E1–E6.
25. Mayer HM. A new microsurgical technique for minimally invasive
anterior lumbar interbody fusion. Spine 1997;22(6):691–699; discussion 700.
26. Zdeblick TA, David SM. A prospective comparison of surgical
approach for anterior L4-L5 fusion: laparoscopic versus mini anterior
lumbar interbody fusion. Spine 2000;25(20):2682–2687.
27. Lieberman IH, Willsher PC, Litwin DE, et al. Transperitoneal laparoscopic exposure for lumbar interbody fusion. Spine 2000;25(4):
509–514; discussion 515.
28. Regan JJ, Yuan H, McAfee PC. Laparoscopic fusion of the lumbar
spine: minimally invasive spine surgery. A prospective multicenter
study evaluating open and laparoscopic lumbar fusion. Spine 1999;24
(4):402–411.
29. Rajaraman V, Vingan R, Roth P, et al. Visceral and vascular complications resulting from anterior lumbar interbody fusion. J Neurosurg
1999;91(1 suppl):60–64.
30. Hackenberg L, Liljenqvist U, Halm H, et al. Occlusion of the left common iliac artery and consecutive thromboembolism of the left popliteal
artery following anterior lumbar interbody fusion. J Spinal Disord
2001;14(4):365–368.
31. Buck BE, Malinin TI, Brown MD. Bone transplantation and human
CHAPTER 33/OPERATIVE TREATMENT OF ANTERIOR PROCEDURES / 337
immunodeficiency virus. An estimate of risk of acquired immunodeficiency syndrome (AIDS). Clin Orthop 1989;(240):129–136.
32. Christensen FB, Bunger CE. Retrograde ejaculation after retroperitoneal lower lumbar interbody fusion. Int Orthop 1997;21(3):176–180.
33. Flynn JC, Price CT. Sexual complications of anterior fusion of the lumbar spine. Spine 1984;9(5):489–492.
34. Liu JK, Nwagwu C, Pikus HJ, et al. Laparoscopic anterior lumbar
interbody fusion precipitating pituitary apoplexy. Acta Neurochir
(Wien) 2001;143(3):303–306; discussion 306–307.
35. Isiklar ZU, Lindsey RW, Coburn M. Ureteral injury after anterior
lumbar interbody fusion. A case report. Spine 1996;21(20):2379–
2382.
CHAPTER 34
Operative Treatment of Anterior and Posterior Fusion
Björn Strömqvist
PROS AND CONS
Although everybody dealing with lumbar spine fusion is
aware that selection of the right patient is more important
than selection of the surgical technique, this should not
keep us from optimizing the technical aspects of the procedures and identifying the most appropriate procedure
in each case. In spite of the fact that many patients with
degenerative disc disease (DDD) e xperience the so-called
“instability catch” (1), the lumbar spine with disc degenerative changes is inherently stable. Hypermobility has
not been demonstrated except in isthmic spondylolisthesis (2) and radiostereometric analysis (RSA) has recently
shown that patients with DDD have decreased segmental
mobility (Axelsson et al., personal communication).
Thus, the basic attitude toward fusion of DDD should be
to select the least possible invasive procedure with the
least morbidity that will address the underlying pathology. Recent randomized controlled trials have not been
able to demonstrate instrumentation to improve the outcome of lumbar spine fusion (3,4). In the Swedish
National Lumbar Spine Study, posterolateral uninstrumented fusion seemed to fare equivalently to posterior
instrumented or 360° (anterior and posterior) fusion (5).
The fact that his and other prospective randomized studies show posterolateral uninstrumented fusion to give
results equal to combined techniques, however, does not
mean that posterolateral fusion is the preferred operation
in every case. Patients undergoing lumbar spine fusion
are very heterogeneous in regard to indications, demographics, personality traits, and anatomic aspects (6);
individual considerations may have to be made.
INDICATIONS
Combined anterior and posterior fusion may be con-
sidered under the following circumstances:
1. Facetectomy. If concomitant facetectomy is performed bilaterally or unilaterally, an unstable situation is present and the ability to obtain a facet fusion
is lost (7,8).
2. Inability to cope with postoperative regimen. In
patients who cannot tolerate postoperative orthotic
treatment and spine immobilization, a combined procedure may be indicated to resist the loading forces
on the stabilized segment and therefore reduce the
risk for nonunion or implant failure. This also may
apply to patients with high performance demands.
3. Revision surgery. Patients with unsuccessful prior
surgery for degenerative lumbar spine disorders are
given the diagnostic label failed back surgery syndrome. Some studies report good results with combined anterior and posterior fusion in such cases
(9,10), although no randomized studies exist.
4. Other metabolic or anatomic variants (e.g., osteopenia, insufficient bone surfaces for bony fusion, and
deficiency disorders) may indicate the need for a
combined antero-posterior fusion.
SPINAL STABILIZATION
Comparing anterior, posterolateral, and posterior fusion, Lee and Langrana (11) in a biomechanical study
concluded that the posterolateral fusion technique was
the best method of providing stabilization to the fused
segment and having the least effect on the adjacent
unfused segment. The combined anterior and posterior
fusion provides better stabilization from a biomechanical
point of view, but whether or not this has any relationship
to future adjacent segment problems is not known
(12,13). Using the RSA technique to study in vivo kinematics (14), it has been possible to demonstrate a slow
healing rate of uninstrumented posterolateral fusion,
338
CHAPTER 34/OPERATIVE TREATMENT OF ANTERIOR AND POSTERIOR FUSION / 339
which becomes stable between 6 and 12 months after
surgery. With the addition of posterior transpedicular
instrumentation, immediate stability is obtained (15).
Stand-alone interbody cages demonstrate an intermediate
time required for segmental stabilization (16). This fact
may be interpreted as obviating the need for routine use
of combined procedures in the inherently stable degenerative lumbar spine. Although increased surgery time and
more blood loss occur (5,17), many nonrandomized studies, however, report very good outcomes with combined
fusions. When combined fusions are considered, one prerequisite is that they should be performed by spine surgeons very familiar with the technique in order to minimize the complication rate. The risk of retrograde
ejaculation and for sympathetic trunk disturbance, for
example, is solely associated with anterior surgery and
may be minimized by limiting the procedure to surgeons
experienced with anterior procedures.
A major issue in surgery for axial pain is determining
the location of the pain generator. The spine, being a
three-joint complex, can have pain from the disc as well
as facet joint–related pain. This has been one argument
for including vertebral body fusion because some micromotion may remain over the disc even in the presence of
a solid posterolateral fusion (18,19). In some instances,
this micromotion produces pain.
SURGICAL OPTIONS
compression of the interbody implant is desired, anterior
disc resection and implant insertion must be done before
posterior compression is applied to the anterior implant.
This is a complex procedure, but provides the most pronounced stability to the segment immobilized. Posterior
transpedicular fixation techniques with rods or plates are
used, and are usuall y combined with bone harvesting from
the iliac crest. Anterior cortical bone grafts in the form of
either autografts or allografts may be used or metal cages
or other types of metal implants (usually titanium) (Fig.
34-2). These implants are presented elsewhere in this and
other chapters. Immediate mobilization and early rehabilitation without orthosis usually is permitted.
Posterior Lumbar Interbody Fusion
This procedure is described elsewhere in this text
(Chapter 32), and is essentially a combined anterior and
posterior procedure performed via a posterior approach
(21). Typically, transpedicular instrumentation is used,
and the cages are inserted in the axilla between the common dural sac and the exiting nerve root. This may necessitate some traction on the nerve root and also may be
associated with troublesome venous plexus bleeding;
therefore, this procedure requires experience with the
technique. Compression of the interbody graft is
achieved by the posterior construct.
Posterior Fusion plus Anterior Lumbar Interbody
Fusion
This procedure requires posterior fusion and instrumentation, either from the midline approach or via the
Wiltse approach between the longissimus and multif idus
muscles (Fig. 34-1). Anterior disc replacement is performed via the transperitoneal or retroperitoneal approach
(20). These approaches have been described previously. If
Transforaminal Lumbar Interbody Fusion
Transforaminal lumbar interbody fusion (TLIF), or
monoportal posterolateral intertransverse fusions (PLIF),
has been described by Harms and Tabasso (22). This is an
operation performed posteriorly. One of the facet joints is
resected, the disc is removed, and intercorporeal implants
are filled with cancellous bone and are inser ted. Posteriorly transpedicular instrumentation is used and compres-
FIG. 34-1. Axial image of the lumbar spine showing
(arrows) the Wiltse approach giving good access to pedicles
and transverse processes when performing posterolateral
fusion with and without instrumentation. The cleavage plane
is between the longissimus and multifidus muscles.
340 /SECTION V/SPECIFIC CLINICAL ENTITIES
FIG. 34-2. Lateral radiograph after combined fusion using
rods, pedicle screws, and autograft posteriorly and cages
anteriorly.
sion is applied as with a PLIF. This approach provides
access to the disc lateral to the nerve root, gives a wider
access to the disc, and can reduce traction to the nerve
root at the disc level.
A possible disadvantage of TLIF compared with PLIF
is that one entire facet joint must be resected, although
significant par ts of both facet joints usually are resected
with PLIF. Threaded cages are less suitable for the TLIF
procedure and smaller cages are used instead, for example, two Harms cages, which are inserted from the facet
joint resection side; the first cage is moved to the contralateral side and the second is retained on the ipsilateral
side (Fig. 34-3). Posterior compression is performed by
the transpedicular system as in the other two procedures.
To date this technique is not so well documented in the
literature but seems like an attractive alternative when
combined procedures are considered.
CONCLUSION
This chapter briefly described techniques for performing combined anterior and posterior (360°) fusions of the
lumbar spine and discussed the advantages and disadvantages of combined fusion procedures in DDD. Combined
procedures require surgical skill in the technical aspects
of the procedure in order to minimize complications.
Their indication is limited in the inherently stable degenerative spine; for example, in patients where concomitant
facetectomy must be performed or in patients unable to
tolerate the postoperative immobilization. Some studies
have shown very good results from combined anterior
and posterior procedures, especially in the failed back
surgery syndrome, but in randomized controlled trials
superiority of the technique has not been proved.
Although an increased complication rate has been
reported, this technique may be indicated in selected
cases when performed by spine surgeons familiar with
the technique. Future prospective studies may help to
determine the optimal fusion procedure, taking into
account biomechanical, biological, and psychosocial
A
FIG. 34-3. Postoperative radiograph in patient operated on with a transforaminal lumbar interbody
fusion technique. Posterior fixation is demonstrated with Diapason rod, screws, and autografting, interbody fusion with Harms cages, and autograft, both harvested from the posterior iliac crest. A: Anterior
and posterior image. B: Lateral image.
B
CHAPTER 34/OPERATIVE TREATMENT OF ANTERIOR AND POSTERIOR FUSION / 341
aspects of an individual patient. With our current knowledge, however, it may be appropriate to conclude by reemphasizing that patient selection is more crucial than
technique selection in deciding whether or not to perform
a lumbar spine fusion for degenerative disc disorders.
REFERENCES
1. Paris SV. Physical signs of instability. Spine 1985;10:277–279.
2. Friberg O. Lumbar instability: a dynamic approach by traction-compression radiography. Spine 1987;12:119–129.
3. Thomsen K, Christensen FB, Eiskjaer SP, et al. The effect of pedicle
screw instrumentation on functional outcome and fusion rates in posterolateral lumbar spinal fusion: A prospective randomized clinical
study. Spine 1997;22:2813–2822.
4. Fischgrund JS, McKay M, Herkowitz HN, et al. Degenerative lumbar
spondylolisthesis with spinal stenosis: a prospective, randomized study
comparing decompressive laminectomy and arthrodesis with and without spinal instrumentation. Spine 1997;22:2807–2812.
5. Fritzell P, Hägg O, Wessberg P, et al. Lumbar fusion versus nonsurgical
treatment for chronic low back pain. A multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine
2001;26:2521–2534.
6. Turner JA, Ersek M, Herron L, et al. Patient outcomes after lumbar
spinal fusions. JAMA 1992;268:907–911.
7. Strömqvist B. Postlaminectomy problems with reference to spinal
fusion. Acta Orthop Scand 1993;64(suppl 251):87–89.
8. Sidhu KS, Herkowitz HN. Spinal instrumentation in the management of
degenerative disorders of the lumbar spine. Clin Orthop 1997;335:39–53.
9. O’Brien JP, Dawson MHO, Heard CW, et al. Simultaneous combined
anterior and posterior fusion. A surgical solution for failed spinal
surgery with a brief review of the first 150 patients. Clin Orthop
1986;203:191–195.
10. Leufvén C, Nordwall A. Management of chronic disabling low back
pain with 360° fusion. Spine 1999;24:2042–2045.
11. Lee CK, Langrana NA. Lumbosacral spinal fusion. A biomechanical
study. Spine 1984;9:574–581.
12. Luk KDK, Chow DHK, Evans JH, et al. Lumbar spinal mobility after
short anterior interbody fusion. Spine 1995;20:813–818.
13. Axelsson P, Johnsson R, Strömqvist B. The spondylolytic vertebra and
its adjacent segment. Mobility measured before and after posterolateral
fusion. Spine 1997;22:414–417.
14. Johnsson R, Selvik G, Strömqvist B, et al. Mobility of the lower lumbar spine after posterolateral fusion determined by roentgen stereophotogrammetric analysis. Spine 1990;15:347–350.
15. Johnsson R, Ax elsson P, Gunnarsson G, et al. Stability of lumbar fusion
with transpedicular fixation determined by roentgen stereophotogrammetric analysis. Spine 1999;24:687–690.
16. Johnsson R, Branth B, Strömqvist B, et al. Interbody stability following anterior lumbar fusion with BAK cages ev aluated by RSA. Hawaii:
ISSLS, 2000.
17. Fritzell P, Hägg O, Wessberg P, et al. 2001 Volvo Award W inner in clinical studies: Lumbar fusion versus nonsurgical treatment for chronic
low back pain. A multicenter randomized controlled trial from the
Swedish Lumbar Spine Study Group. Spine 2001;26:2521–2534.
18. Weatherley CR, Prickett CF, O’Brien JP. Discogenic pain persisting
despite solid posterior fusion. J Bone Joint Surg 1986;68B:142–143.
19. Johnsson R, Strömqvist B, Axelsson P, et al. Influence of spinal immobilization on consolidation of posterolateral lumbosacral fusion. A
roentgen stereophotogrammetric and radiographic analysis. Spine
1992;17:16–21.
20. Kozak JA, O’Brien JP. Simultaneous combined anterior and posterior
fusion. An independent analysis of a treatment for the disabled low
back pain patient. Spine 1990;115:322–328.
21. Steffee AD, Sitkowski DJ. Posterior lumbar interbody fusion and
plates. Clin Orthop 1988;227:99–102.
22. Harms J, Tabasso G. Instrumented spinal surgery. Principles and technique. Stuttgart: Georg Thieme V erlag, 1999.
CHAPTER 35
Degenerative Disc Disease: Fusion Cages and Dowels
Richard D. Guyer and Donna D. Ohnmeiss
The treatment of symptomatic degenerative disc disease
(DDD) is a controversial topic. Some regard disc degeneration as merely a natural process that generally does not
merit operative intervention. However, some of the acute
annular tears that may trigger the degenerative process
can be extremely painful and remain painful for a long
period, significantly decreasing the patient’s quality of
life. If one accepts the concept of surgical treatment for
symptomatic disc degeneration that is unresponsive to
nonoperative treatment, then the question remains as to
which procedure is the best treatment for this condition.
The primary purpose of interbody fusion for the treatment of disc-related pain is to remove the pain generator—the pain-producing disc tissue—and maintain or
increase disc height, which indirectly decompresses the
neuroforamen while allowing the fusion to take place.
Generally good results have been reported from interbody fusion for the treatment of disc-related pain (1–7).
On the other hand, the results of posterior fusion alone for
the treatment of disc-related pain typically have been
poor (2,8,9). These poor results may be related to the
inability to directly address the disc with a posterior
fusion alone. The pain-producing disc tissue remains in
the segment, and posterior fusion alone may not be adequate to sufficiently reduce the load on the disc, producing mechanical pain. Biomechanical studies have
reported that the disc pressure is the same in a disc
spanned by posterior fixation as in an uninstrumented
disc (10). Clinical studies report that anterior interbody
fusion has provided pain relief when performed at the
level of a solid posterior fusion for the treatment of ongoing discogenic pain (11,12). The interbody fusion allows
removal of the disc tissue and stabilizes the segment.
Traditionally, autogenous iliac crest graft was used for
lumbar interbody fusion. Because of the complications
associated with harvesting iliac crest grafts, including
pain and infection, other alternatives were sought. Use of
allograft addresses this issue and decreases the operative
time by eliminating the time needed to harvest the graft.
Allograft for interbody fusion encompasses a variety of
forms, including dowels, chips, strips, and femoral rings.
Allograft bone can be taken from a variety of donor sites,
including iliac crest, femur, and patella. Although these
materials eliminated donor site complications, there was
some concern as to whether they produced results as
good as autogenous graft. The optimal size, shape, and
composition (cortical versus cancellous bone) have been
debated. There is also a concern with potential transmission of diseases. There w as consensus that the most desirable interbody graft would be one that produced a high
fusion rate, reduced or eliminated donor site morbidity,
maintained the height of the disc space and ideal spinal
alignment, and provided rapid stabilization of the spine.
However, identifying a graft material with all these properties was and remains a challenge. Many designs and
concepts of fusion cages have emerged in the course of
seeking a solution to the problem of identifying the ideal
interbody graft. The role for fusion cages in the treatment
of symptomatic degenerative disc conditions includes
distraction of the disc space and provision of early stabilization to the operated segment while bony incorporation
of the fusion mass takes place. In this chapter, we discuss
various designs of cages that have been used for lumbar
interbody fusion.
INDICATIONS
The indications for the use of cages in the treatment of
DDD are similar to those for traditional lumbar interbody
fusion. The patient should have failed a trial of nonoper-
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