Lumbar Interbody Fusion Using Bone Morphogenetic Protein Results and Fusion Assessment

J. Kenneth Burkusa, Kevin T. Foley0, Regis W. Haid, Jr.c aThe Hughston Clinic, PC, Columbus, Ga., bSemmes-murphy Clinic, Memphis, Tenn., and cDepartment of Neurosurgery, Emory University, Atlanta, Ga., USA

No uniform criteria for determining fusion have been used in the reports of radiographic outcomes of anterior lumbar interbody fusion (ALIF) surgery [1, 2]. The most commonly reported standard for establishing the presence of a successful lumbar interbody fusion is evidence of trabecular bone formation linking the adjacent vertebral bodies. A wide range of fusion rates for the ALIF procedure has been reported [3-7]. The variability in fusion rates is, in part, determined by the surgical technique, the type and quantity of bone graft used, and the presence of an interbody fusion device. With these variables, the determination of a successful arthrodesis is largely determined by the investigator's definition of fusion.

The use of metallic interbody fusion devices creates new challenges in establishing fusion criteria. These devices obscure vertebral landmarks used in the assessment of fusion and create artifacts that degrade some imaging techniques [8-10]. The intradiscal radiographic patterns of fusion after surgery with interbody fusion cages are determined by the extent of the discectomy, the end plate preparation, the reaming techniques, the interface between the cage and the host bone, and the characteristics of the bone graft materials used. Direct surgical exploration is not a viable option for determining the status of an interbody fusion [11-13]. Indirect assessment at surgery of an anterior fusion through the manipulation of the posterior spinous processes is subjective and can identify only gross patterns of instability and cannot reliably identify micromotion across an interspace.

Other than by histologic biopsy, interbody fusion can only be assessed objectively by various radiographic imaging techniques. Although the presence of a pseudarthrosis can be determined by a single finding on an isolated radiographic study, the presence of a solid fusion cannot be determined by a single radiographic finding. Failure of fusion is established by the absence of bridging trabecular bone and the presence of a radiolucent area that extends through the entire fusion mass. Pseudarthrosis can also be identified by marginal radiolucency around the implant, progressive subsidence of implants, and angular changes in the spinal motion segment.

At present, no single study or technique is definitive for establishing the presence of a fusion after anterior interbody surgery [14]. A successful arthrodesis within a spinal motion segment can be determined by using radiographic evaluation to assess a stable spinal alignment on sequential examinations, a reduction in angular and translational changes on dynamic motion studies, an absence of fibrous tissue reaction at the device-host interface, and the presence of new bone formation and bone remodeling [15].

The most comprehensive and accurate means of radiographically assessing fusion of the lumbar spine after ALIF with intradiscal implants are plain radiographs, dynamic motion radiographs, and thin-cut computerized tomography (CT) scans. Technetium bone scans and MR imaging are not effective in assessing interbody fusion [9, 16]. Plain radiographs are effective for determining changes in spinal alignment over time. Dynamic plain radiographs can accurately assess changes in implant-host bone interface and instability patterns within the spinal motion segment. CT imaging can identify new bone formation and bone remodeling within and around the spinal implants [8, 17]. By using all three imaging technologies, the physician can accurately determine a successful and clinically relevant interbody fusion [15].

Lumbar Spine Imaging Studies

Plain Radiographs

The plain radiographic studies that are used most often to assess fusion include the following: (1) standing or weight-bearing radiographs, (2) supine radiographs, (3) dynamic flexion-extension radiographs, and (4) dynamic side-bending radiographs. Standing or weight-bearing films are more valuable than supine films in assessing sagittal plane balance and alignment; a weight-bearing radiographic technique stresses the interbody fusion can help identify instability patterns. Supine anteroposterior radiographs show lucencies around metallic implants (fig. 1).

Metallic implants create artifacts that make interpretation of plain radiographs alone inaccurate in the assessment of fusion [8, 10]. Bone growth within the implants cannot be assessed on plain radiographs. The thread patterns of a

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Fig. 1. a Supine anteroposterior radiograph shows lucencies around both implants. b Thin-cut CT scan sagittal reconstruction confirms the lucencies surrounding the cages.

Fig. 1. a Supine anteroposterior radiograph shows lucencies around both implants. b Thin-cut CT scan sagittal reconstruction confirms the lucencies surrounding the cages.

interbody fusion cages create varying amounts of artifact at the implant-host bone interface. Radiographic lucencies in this area can be misinterpreted. The following findings on plain radiographs help to identify a fusion: (1) incorporation of grafts to vertebral end plates, (2) bridging trabecular bone across the interspace, (3) absence of lucencies at the graft-host interface, (4) absence of subsidence, and (5) absence of graft or implant migration. The absence of subsidence and implant migration can only be established by a review of serial radiographs.

Dynamic Plain Radiographs

Dynamic motion studies of the lumbar spine are done to identify subtle changes within the spinal motion segment after ALIF surgery. Intra- and interobserver measurement error is always a factor in the assessment of lumbar intervertebral segmental angulation and translation on serial radiographs. In their clinical studies, examiners have considered spinal motion segments to be fused despite measured differences in both angular and sagittal translation [1, 5]. Reports of measurement error range from 1 to 5°. Brantigan [18] proposed that only 1° of motion was consistent with a fusion. Zdeblick [19] proposed 2°, and Ray [7] proposed 3° of motion as support for the presence of a solid fusion. These studies contrast with the findings of Kuslich et al. [5] who reported that angular measurements of less than 5° are not accurate. Commonly, the presence of 3-5° of motion within an instrumented spinal segment and 5 mm of translation is considered fused. These differences on dynamic studies are accepted because of measurement errors. Clinicians often find these results difficult to interpret because motion should not occur within a fused spinal segment.

Amplifying the problem of intra- and interobserver measurement error on dynamic radiographs is the fact that no standard method for obtaining flexion-extension radiographs has been established. Biplanar studies are among the most reliable plain radiographic methods. Dynamic radiographs taken with the patient in the standing position are not reliable because of variable patient compliance and the technical difficulty of properly centering the x-ray beam parallel to the appropriate interspace. With standing lateral dynamic studies, the pelvis is not locked and motion may be occurring at the hip joints rather than within the lumbar spine. Supine lateral dynamic studies obtained in the lateral decubitus position are also unreliable for the same reasons - the pelvis is not locked or properly supported. Lateral radiographic images are frequently rotated unless the lumbar spine has been supported. It is technically difficult to maintain the x-ray beam parallel to the spinal motion segment during these dynamic studies.

Flexion-extension radiographs should be obtained with the pelvis fixed so that motion occurs within the lumbar spine. Dynamic studies with the patient in the seated position restrict pelvic and hip motion and enable the technician to consistently obtain radiographs centered at the appropriate disc space with minimal rotational distortion at the interspace. Restricting motion to the lumbar spine by eliminating hip and pelvic motion and consistently obtaining radiographs that are parallel to the end plate of the instrumented spinal segment sufficiently improves the accuracy of dynamic radiographic studies and demonstrates subtle changes within the spinal motion segment (fig. 1). Biplanar radiographic techniques have been introduced to reduce measurement error [20].

Thin-Cut 1-mm CTScans

Axial CT has also been used to establish fusion [8, 13, 21-23]. This cross-sectional imaging technique eliminates overlapping and rotational errors present on plain radiographs and allows direct visualization of the fusion mass. Thin-cut CT scans with sagittal and coronal reconstructions have a greater ability to detect radiolucent areas within a developing fusion mass. Using thin-cut CT scans, clinicians have identified and classified complex forms of spinal pseudarthrosis into distinct morphologic categories [1, 20]. In animal studies, thin-cut CT scans using 1-mm-thick axial sections through interbody fusion cages have been used to reliably identify new bone formation within metallic fusion cages and to identify pseudarthroses after interbody surgery [12, 24, 25]. These findings were correlated with histologic confirmation to establish the presence or absence of a fusion. In these animal studies, CT scans were used to show trabecular bone formation patterns within the disc space and identify bridging bone formation that crossed the interspace. CT scanning was also used to identify lucencies at the implant-bone interface. In our clinical experience, thin-cut CT scanning has been the most precise and accurate method of evaluating interbody fusion [26, 27].

A single CT scan may not be able to distinguish between unincorporated or necrotic bone grafts from bridging trabecular bone within a metallic fusion cage. Cunningham et al. [28] analyzed fusion through a histomorphometric assessment. They could not differentiate between residual autograft and new bone formation. However, serial CT scans can be used to identify maturation of corticocancellous grafts within fusion cages and can demonstrate incorporation of these grafts through the openings in the second-generation fusion cages [26]. CT scans can be used to accurately identify new bone formation within the disc space but outside of the interbody fusion devices [17, 26, 27].

Interbody Fusion Assessment

The assessment of fusion in a patient who has an interbody fusion device includes four key elements: (1) spinal alignment, (2) segmental spinal stabilization, (3) device-host bone interface, and (4) new bone formation and bone remodeling. Spinal alignment must be maintained over time. Similarly, with an intact fusion, no significant angular or translational change should occur on dynamic motion studies. The contact points between the device and the host cortical bone and cancellous bone must also be assessed. For an intervertebral body fusion to be considered intact and complete, there should be no radiolucent areas surrounding the devices at the interface with the host bone. Identification of new trabecular bone formation within the disc space and remodeling of the grafts within and around the interbody devices must also be assessed and is the most important aspect of the fusion criteria [17, 29], but the sentinel sign [30, 31] of the progressive anterior bone formation alone is not helpful in determining fusion.

Spinal Alignment

ALIF using stand-alone implants often improve the frontal and sagittal plain contours of the lumbar spine. Immediate postoperative improvements in frontal and sagittal plane contours are not maintained over time in all patients [32-34]. Stand-alone implants are susceptible to subsidence into the vertebral end plates. Subsidence of the implants, which occurs over the course of several years after surgery, often leads to segmental spinal instability, loss of lordosis, angular frontal plain deformities, and sagittal plain translation. It is evidence of a delayed fusion or frank pseudarthrosis (fig. 2). The ability of an implant to resist subsidence is, in part, related to its design [35]. Subsidence, loss of disc space height, and angular deformity are also related to the position of the implants within the disc space [17, 31].

Interbody fusion can only be determined to be complete if there is no change in the alignment of the spine at the instrumented fusion site for a minimum of

Fig. 2. a Standing lateral radiograph at 6 weeks after surgery. Segmental lordosis at L4-L5 measures 14° and the implant rests on the cortical margin of the adjacent vertebral end plate. b At 18 months after surgery, the segmental lordosis is reduced to 9° and the implant has subsided through the vertebral end plate. Anterior radial osteophytes have formed.

Fig. 2. a Standing lateral radiograph at 6 weeks after surgery. Segmental lordosis at L4-L5 measures 14° and the implant rests on the cortical margin of the adjacent vertebral end plate. b At 18 months after surgery, the segmental lordosis is reduced to 9° and the implant has subsided through the vertebral end plate. Anterior radial osteophytes have formed.

Fig. 3. a Standing anteroposterior radiographs at 3 months after surgery show no significant frontal plane deformity. b Standing anteroposterior radiograph at 1 year after surgery shows a 7° angular deformity across the instrumented interspace.

6 months. Standing anteroposterior and lateral radiographic views must show no significant change in segmental lordosis (^3°), sagittal translation (<5mm), or frontal plane angulation (^3°) on sequential radiographs taken at least 6 months apart. Interbody fusion cannot be considered intact if there are progressive changes in any frontal or sagittal plane angular or translational measurements (fig. 3).

Segmental Spinal Stabilization

Subtle changes in the lumbar contours can be identified on dynamic lateral radiographs; changes in segmental lordosis and sagittal plane translation can be identified on these studies. Incorporating known measurement error, criteria for fusion on dynamic radiographic studies include angular motion of 3° or less and reduction in sagittal plane or frontal plane translation of 5 mm or less. The documentation of persistent motion across a fused motion segment has led some clinicians and researchers to conclude that the error in measuring dynamic plane radiographs often precludes an accurate determination of fusion.

Device-Bone Interface

The host bone reaction to an interbody fusion device helps to ascertain fusion. Although the composition and shape of the implant influence the region around the device, the host bone reaction to the implant remains an important aspect of determining fusion. The presence of sclerosis or cystic radiolucencies on the margins of the implant within the subchondral bone can result from bony reabsorption and fibrosis tissue reaction secondary micromotion in the presence of a pseudarthrosis. Radiolucency surrounding the implants represents the interposition of fibrous tissue at the host bone-implant interface. It is commonly agreed that this is also a sign of micromotion and instability. End plate sclerosis that extends through the subchondral bone and alters the trabecular pattern of the vertebral body is also consistent with micromotion and pseudarthrosis. Plain radiographs, dynamic extension radiographs, and thin-cut CT scans are helpful in assessing the device-bone interface. These changes can be seen on plain radiographs but are best detailed on thin-cut CT scans.

Progressive collapse of the interspace and migration of implants are gross radiographic signs of instability, delayed union, and pseudarthrosis. Plain radiographs can also identify migration and subsidence of the implants within the disc space. Dynamic lateral extension radiographs help to identify subtle patterns of motion at the disc space and can help to identify interface lucen-cies. If a fusion is not present, hyperextension lateral radiographs can increase the gap between the implant and host bone. This gap appears as increased radiolucency surrounding the implant or may appear as a gap in the anterior fusion mass.

Thin-cut CT scans are best at detailing cystic changes within the vertebral end plates, sclerosis, and interface lucency. Heithoff et al. [10] found CT scans of little value in assessing fusion for the first-generation BAK cages. It is difficult to assess for fusion in patients with the thick-walled and square-threaded BAK cage because of the radiographic scatter inherently associated with its

Lumbar Pseudarthrosis Cage Device
Fig. 4. Axial CT scan at the device-bone interface shows lucent lines surrounding the contact points of the implant and the host bone.

design. However, end plate sclerosis and the presence of cyst formation within the end plate adjacent to the implants can be readily determined even on these first-generation implants (fig. 4). The interface between the host bone and titanium implants can be more easily assessed with second-generation cages such as the INTER FIX™ (Medtronic Sofamor Danek, Memphis, Tenn., USA) and LT-Cage™ (Medtronic Sofamor Danek). The thread patterns on these cages are self-tapping and thinner than on earlier devices. The radiographic scatter and artifact are reduced. With the second-generation cages, it is possible to assess the interface between the implant and the host bone for the development of fibrous lucency.

The assessment of interbody fusion with cortical allografts must include incorporation of the graft materials in addition to the morcellized autogenous grafts. Complete fusion of an allograft-autograft montage must include incorporation of the allograft into both vertebral end plates and trabecular bone formation across the interspace [22, 36]. With threaded cylindrical bone dowels and femoral rings, it is possible to determine incorporation of the allograft to end plates of the host vertebra. On plain radiographs and CT scans, it is common to find early trabecular bone formation crossing the interspace. In the presence of spanning trabecular bone formation around the implant, there is often incorporation of the allograft to only one vertebral end plate. The lucencies surrounding the contact points of the allograft to one end plate often resolve over time [34, 37, 38]. They are commonly present at 1 year after surgery and do not i

Fig. 5. a Coronal CT scan reconstruction immediately after interbody surgery with LT-Cage devices and autogenous grafts shows the cages are well seated within the L5-S1 disc space. There are autogenous bone grafts within the cages; no grafts were placed lateral to the cages. b Coronal CT scan reconstruction at 1 year after surgery shows maturation of grafts with the cages and new bone formation outside of the cages and within the confines of the disc space in the lateral fusion zones.

Fig. 5. a Coronal CT scan reconstruction immediately after interbody surgery with LT-Cage devices and autogenous grafts shows the cages are well seated within the L5-S1 disc space. There are autogenous bone grafts within the cages; no grafts were placed lateral to the cages. b Coronal CT scan reconstruction at 1 year after surgery shows maturation of grafts with the cages and new bone formation outside of the cages and within the confines of the disc space in the lateral fusion zones.

a resolve until 2-3 years after surgery. These unilateral lucencies on dynamic plain radiographs are not associated with poor clinical outcomes, subsidence, or instability. However, they do represent incomplete incorporation and fusion of the allograft.

New Bone Formation and Bone Remodeling

New bone formation and bone remodeling in and around interbody fusion cages can be assessed radiographically. Carbon fiber implants and cortical allografts are readily assessed radiographically. The ability to assess bone formation around titanium implants depends, in part, on the size of the implant, the configuration of the implant, and the porosity of the implant. The first-generation BAK implant is thick-walled and square-threaded. It also has two small openings that are bordered by an internal strut for driving the implant. The configuration of this thick-walled titanium implant is not conducive to radiographic visualization of bone graft within or immediately adjacent to the cage. Second generation titanium implants produce significantly less scatter and artifact on plain radiographs and CT scans. The LT-Cage, INTER FIX and Ray TFC™ (Surgical Dynamics, Norwalk, Conn., USA) fusion cages [10] are hollow, fen-estrated cylinders with no internal driving device. These cages are significantly more porous and their thread patterns are also not square and do not produce as much scatter (fig. 5).

The appearance of bone within an interbody fusion cage is not always indicative of a fusion after surgery using autograft. CT scanning cannot be used to distinguish between unincorporated necrotic bone present in the cage and new trabecular bone formation. Identification of new bone formation outside a

Fig. 6. a Coronal CT scan reconstruction shows two LT-Cage devices centrally placed in the L5-S1 disc space 48 h after surgery. The cages were filled with InFUSE bone graft substitute (rhBMP-2 and an absorbable collagen sponge). No autogenous grafts were placed within the disc space or cage. b At 1 year after surgery, there is new formation within both cages. There is also new bone formation outside the cages in the lateral fusion zones. All new bone formation remains confined to the disc space.

Fig. 6. a Coronal CT scan reconstruction shows two LT-Cage devices centrally placed in the L5-S1 disc space 48 h after surgery. The cages were filled with InFUSE bone graft substitute (rhBMP-2 and an absorbable collagen sponge). No autogenous grafts were placed within the disc space or cage. b At 1 year after surgery, there is new formation within both cages. There is also new bone formation outside the cages in the lateral fusion zones. All new bone formation remains confined to the disc space.

b a the cages in an area where no bone graft was placed is the most important radiographic sign indicating fusion. Similarly, identification of annular ossification and bridging osteophytes crossing a disc space are secondary signs of new bone formation after a successful interbody fusion.

Recombinant Human Bone Morphogenetic Protein-2

Assessing new bone formation after interbody surgery with InFUSE™ Bone Graft (Medtronic Sofamor Danek) substitute does not have the inherent limitations of differentiating between de novo new bone formation and residual necrotic bone. InFUSE is recombinant human bone morphogenetic protein (rhBMP-2) applied to an absorbable collagen sponge. Its use replaces the need for autogenous bone grafts and eliminates the complications associated with iliac crest graft harvesting. In animal experimental models and in all human studies, InFUSE has been used without any autogenous or autologous grafts [24-27, 39].

In a prospective human study, osteoinduction after lumbar interbody surgery was shown to occur with the use of InFUSE [25, 26]. These early findings were confirmed in a larger study involving 143 treated with InFUSE [27]. New bone formation occurred in all patients treated with the LT-Cage and InFUSE (rhBMP-2). The overall fusion rate at 24 months was greater than 94% in these patients. In a smaller sample of these rhBMP-2-treated patients, bone formation, as evidenced by progressive density on thin-cut CT scans, almost doubled within 6 months of surgery and increased almost 2.5 times by 24 months [26] (fig. 6). Similar to the bone formation within the cages, new

Fig. 7. Anterior and posterior fusion zones.

bone formation had occurred outside of the cages in the rhBMP-2 group by 6 months after surgery, and it occurred in all patients by 24 months [26, 27]. New bone formation within the cages occurred most markedly during the first 6-12 months after surgery; rates of new bone formation exceeded those of the autograft control group. All new bone formation outside of the cages occurred within the confines of the disc space. All CT scan slices and all reconstructed images were studied to evaluate new bone formation. No new bone formation extended outside of the annulus fibrosus; no bone growth was observed extending posteriorly into the spinal canal or posterolaterally into the neuro-foramina.

Fusion Zones

New bone formation in a region or zone of the interspace that is free of autogenous graft or growth factors represents osteoinduction within the soft tissue elements of the spinal motion segment. Identifying osteoinduction within the disc space is the most accurate means of determining fusion after an ALIF procedure. New bone formation only occurs in a spinal motion segment that is adequately stabilized and, therefore, represents a fused motion segment. Five fusion zones have been established for interbody fusion devices. The zones of fusion can be assessed on plain radiographs and CT scans.

The anterior zone is an area of bone formation in front of the cages along the anterior margins of the disc space (fig. 7). Bone formation in this zone is the least reliable indication of interbody fusion. The formation of radial osteophytes, which is indicative of instability, often masquerades as an early 'sentinel sign'. On the basis of anterior bone formation alone, it is impossible to tell if it is a good sign or a bad sign. For a fusion to be present, trabecular bone

Fig. 8. Lateral plain radiograph shows bone anterior to the cage within the L4-L5 disc space. There has been significant subsidence of the device through the L5 end plate. This sentinel sign does not represent a fusion.

formation in the anterior zone must be complete from end plate to end plate. Bone formation that extends past the confines of the disc space can be an early indication of a developing pseudarthrosis (fig. 8). Frequently the sentinel sign represents radial bone spur formation, not interbody fusion. The isolated sentinel sign may indicate progressive instability instead of progressive fusion.

The posterior zone is the posterior margin of the interspace (see fig. 7). Trabecular bone formation in this zone is most likely the best radiographic indication of interbody fusion. Bone formation in the posterior zone is the most reliable indication of fusion.

The lateral zone or the lateral margins of the disc space are divided into left and right regions (fig. 9). Bone formation between the lateral borders of the implants and the annulus is difficult to visualize on plain radiographs. On anteroposterior and Ferguson views at the L4-5 and L5-S1 interspace, the posterior facet joints overlie the lateral fusion zones and early bone formation in the lateral zone on these plain radiographs. CT scans are essential in visualizing early trabecular bone formation in the lateral zones (fig. 10). Only the final stages of ossification of the annulus fibrosus are apparent on plain anteropos-terior radiographs. Bone formation in these zones is also a very good predictor of fusion and typically occurs here before it does in the posterior zone. Bone formation with the two lateral zones is often asymmetric; this may be related to asymmetric cage placement.

The between zone is the area of bone formation between the implants (fig. 9, 11). Bone formation in this zone is best visualized with thin-cut CT scans and in those patients where the implants have been adequately spaced away from each other.

Fig. 9. Anteroposterior view of the lateral zones and the between zone. The interbody fusion cages are placed equidistant from the midline of the disc space. However, there is space between the cage walls and the annulus fibrosus that compromises new bone formation in the lateral zone.

Fig. 10. Drawing of an axial CT scan shows the position of the anterior, posterior, and lateral zones.

Fig. 11. Drawing of an axial CT scan highlights the within (W) and between (B) zones.

The within zone is the area of bone formation within the interbody fusion device (fig. 9, 11). It is very difficult to differentiate between living and dead bone within the cages. The size, configuration, and material of the cages also significantly influence the ability to accurately assess bone formation in this zone. Assessment of bone formation is not practical with a single CT scan. It is best assessed over time with serial CT scans.

Conclusion

Radiographic criteria have been established to reliably assess fusion after ALIF with threaded and impacted implants and for titanium, carbon fiber, and allograft devices. Determination of fusion involves the radiographic evaluation of spinal alignment, stabilization of the spinal motion segment dynamic studies, assessment of the device-host interface, and identification of new bone formation and bone remodeling. Each of the fusion criteria must be met to ensure that an arthrodesis is complete.

Changes in the sagittal or frontal plane contours over time indicate a delayed fusion. Progressive subsidence or any change in sagittal or frontal plane contours also represents a failed fusion. A fusion can be considered intact if there is no change in spinal alignment within the spinal motion segment over a 6-month period.

Dynamic radiographic studies must be obtained in a manner that applies stress to the instrumented spinal motion segment and in a manner that can be successfully replicated on serial radiographs. The pelvis must be stabilized and radiographs must be taken parallel to the vertebral end plates. A fusion is considered intact only if there is no significant motion on dynamic studies.

Changes in or the appearance of lucencies at the implant-end plate interface are indicative of a failed fusion. Second-generation cages permit a closer evaluation of the device-bone interface. The development of cystic or sclerotic changes within the subchondral bone of the vertebral end plates is suggestive of a fusion failure. If a pseudarthrosis is present, hyperextension lateral radiographs frequently highlight radiolucencies at the device-bone interface and can identify a gap within an anterior 'sentinel fusion'.

The formation of new bone adjacent to or within the intradiscal implants is the most reliable finding for establishing fusion. New bone formation occurs outside the intradiscal implants when fusion has occurred. New bone formation within the lateral and posterior zone is the most reliable radiographic indication of a fusion. Remodeling of autogenous grafts or allografts is also consistent with an intact fusion.

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J. K. Burkus, MD The Hughston Clinic

PC, 6262 Veterans Parkway, Columbus, GA 31909 (USA)

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Neuronavigational Advances

Haid RW Jr, Subach BR, Rodts GE Jr (eds): Advances in Spinal Stabilization. Prog Neurol Surg. Basel, Karger, 2003, vol 16, pp 71-83

Back Pain Revealed

Back Pain Revealed

Tired Having Back Pains All The Time, But You Choose To Ignore It? Every year millions of people see their lives and favorite activities limited by back pain. They forego activities they once loved because of it and in some cases may not even be able to perform their job as well as they once could due to back pain.

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Responses

  • antje
    Does Neuritis always subside following InFuse bone graft?
    4 years ago

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