Frequency, risk factors, and treatment of distal adjacent segment pathology after long thoracolumbar fusion: a systematic review

Should the level of the posterior instrumentation combined with the intermediate screw be a short segment or a long segment in thoracolumbar fractures with fusion to the fractured segment?

PURPOSE

It was aimed to compare the results of long segment posterior instrumentation with intermediate pedicular screw + fusion at the level of the fractured segment including one vertebra above and one below the fractured vertebra (LSPI) and short segment posterior instrumentation with intermediate pedicular screw + fusion at the level of the fractured segment including one vertebra above and one below the fractured vertebra (SSPI) in the surgical treatment of thoracolumbar vertebral fractures.

METHODS

Ninety patients with thoracolumbar vertebral (T11-L2) fractures operated between March 2015 and February 2022 were included in this retrospective study. The patients were divided into two groups as those who underwent LSPI (n, 54; age, 40.3) and those who underwent SSPI (n, 36; age, 39.7). Radiological evaluations like vertebral compression angle (VCA), vertebral corpus heights (VCH), intraoperative parameters, and complications were compared between the groups.

RESULTS

Correction in early postoperative VCA was statistically significantly better in LSPI (p = 0.003). At 1-year follow-up, postoperative VCA correction was significantly more successful in LSPI (p = 0.001). There was no difference between the two groups in terms of correction loss in VCA measured at 1-year follow-up. There was no statistically significant difference between the two groups in terms of postoperative VCH, VCH at 1-year follow-up, and correction loss in VCH.

CONCLUSION

LSPI provides better postoperative kyphosis correction of the fractured vertebra than SSPI. Regarding the segment level of posterior instrumentation, there was no difference between the two groups in terms of the loss of achieved correction of VCA, ABH, and PBH at 1-year follow-up. Operating a thoracolumbar fracture with LSPI will lengthen the operation and increase the number of intraoperative fluoroscopies compared to SSPI.

Percutaneous microchannel unilateral approach bilateral micro decompression for adjacent segmental degeneration after lumbar fusion at 10 years: a case report and review of literature

Background

Adjacent segmental degeneration after lumbar fusion is one of the common long-term complications after lumbar fusion. With the continuous development of adjacent segmental degeneration, patients who fail conservative treatment often need reoperation to relieve symptoms. In recent years, the technique of bilateral microdecompression through unilateral approach under microchannel has been widely used in the treatment of lumbar degenerative diseases. However, the efficacy of this procedure for adjacent-segment degeneration after lumbar fusion has not been established. Here, we report a case of bilateral microscopic decompression via a unilateral approach through a microchannel in a patient with adjacent segmental degeneration after lumbar fusion.

Case report

A 70-year-old male patient was admitted to hospital because of lumbago accompanied by left lower extremity pain, numbness and weakness for 2 years, which aggravated for 2 months. Ten years ago, he underwent PLIF for lumbar spinal stenosis, and recovered well after the operation. According to imaging data and physical examination, the diagnosis was adjacent segmental degeneration after lumbar fusion. Bilateral microdecompression was performed through a unilateral approach under a microchannel. Good clinical outcomes was observed through 1-year postoperative follow-up.

Conclusions

This report reports the successful treatment of a patient with ASD 10 years after lumbar fusion. Bilateral microdecompression via a unilateral approach under a microchannel is a safe and effective method for the treatment of ASD after lumbar fusion with good surgical outcomes.

An investigation of range of motion preservation in fusionless anterior double screw and cord constructs for scoliosis correction

PURPOSE

To evaluate the motion-preserving properties of vertebral body tethering with varying cord/screw constructs and cord thicknesses in cadaveric thoracolumbar spines.

METHODS

In vitro flexibility tests were performed on six fresh-frozen human cadaveric spines (T1-L5) (2 M, 4F) with a median age of 63 (59-to-80). An ± 8 Nm load was applied to determine range of motion (ROM) in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in the thoracic and lumbar spine. Specimens were tested with screws (T5-L4) and without cords. Single (4.0 mm and 5.0 mm) and double (4.0 mm) cord constructs were sequentially tensioned to 100 N and tested: (1) Single 4.0 mm and (2) 5.0 mm cords (T5-T12); (3) Double 4.0 mm cords (T5-12); (4) Single 4.0 mm and (5) 5.0 mm cord (T12-L4); (6) Double 4.0 mm cords (T12-L4).

RESULTS

In the thoracic spine (T5-T12), 4.0-5.0 mm single-cord constructs showed slight reductions in FE and 27-33% reductions in LB compared to intact, while double-cord constructs showed reductions of 24% and 40%, respectively. In the lumbar spine (T12-L4), double-cord constructs had greater reductions in FE (24%), LB (74%), and AR (25%) compared to intact, while single-cord constructs exhibited reductions of 2-4%, 68-69%, and 19-20%, respectively.

CONCLUSIONS

The present biomechanical study found similar motion for 4.0-5.0 mm single-cord constructs and the least motion for double-cord constructs in the thoracic and lumbar spine suggesting that larger diameter 5.0 mm cords may be a more promising motion-preserving option, due to their increased durability compared to smaller cords. Future clinical studies are necessary to determine the impact of these findings on patient outcomes.

Current Evidence on where to End a Fusion within the Thoracolumbar Junction Most Preferably - A Systematic Literature Review

Proximal junctional kyphosis (PJK) is one main complication in the surgical treatment of adult spinal deformities. Ending within the thoracolumbar junction (TLJ) should but cannot always be avoided to reduce the risk for PJK. With this systematic review we sought to define the most preferable vertebra within the TLJ to minimize the risk for PJK and establish recommendations based on our findings. We conducted a systematic literature review by scanning the MEDLINE database in accordance with the PRISMA criteria. All articles addressing primary long-distance dorsal thoracolumbar fusion of at least three segments to treat adult spinal deformities were included. 1385 articles were identified and three were included to this review. The first study showed significantly higher rates of PJK in patients where the construct was extended to T7 or higher when compared to an ending at T11 to L1. The second article stated that an expansion to the TLJ resulted in significantly less surgical revisions due to PJK reduction. On the other hand, the third article found that a fusion of the whole thoracic spine reduces the PJK incidence postoperatively. Even though the most favorable vertebra within the TLJ to avoid PJK best could not yet be determined, our study identifies several principles that represent the current state of evidence for surgical treatment of adult scoliosis. Proper preoperative decision making based on thorough analysis and interpretation of the patient's sagittal alignment parameters can improve the individual outcome critically.

Microendoscopic Decompression for Lumbar Spinal Stenosis Associated with Adjacent Segment Disease following Lumbar Fusion Surgery: 5-year Follow-up of a Retrospective Case Series

BACKGROUND AND STUDY AIMS

 Surgical treatment options for lumbar spinal stenosis (LSS) based on adjacent segment disease (ASD) after spinal fusion typically involve decompression, with or without fusion, of the adjacent segment. The clinical benefits of microendoscopic decompression for LSS based on ASD have not yet been fully elucidated. We aimed to investigate the clinical results of microendoscopic spinal decompression surgery for LSS based on ASD.

PATIENTS AND METHODS

 From 2011 to 2014, consecutive patients who underwent microendoscopic spinal decompression without fusion for LSS based on ASD were enrolled. Data of 32 patients (17 men and 15 women, with a mean age of 70.5 years) were reviewed. Japanese Orthopaedic Association score and low back pain/leg pain visual analog scale score were utilized to measure neurologic and axial pain outcomes, respectively. Additionally, after the surgeries, we analyzed the magnetic resonance imaging (MRI), computed tomography (CT) scans, or radiographs to identify any new instabilities of the decompressed segments or progression of ASD adjacent to the decompressed segments.

RESULTS

 The Japanese Orthopaedic Association recovery rate at the 5-year postoperative visit was 49.2%. The visual analog scale scores for low back pain and leg pain were significantly improved. The minimum clinically important difference for leg pain (decrease by ≥24 mm) and clinically important difference for low back pain (decrease by ≥38 mm) were achieved in 84% (27/32) and 72% (23/32) of cases, respectively. Regarding new instability after microendoscopic decompression, no cases had apparent spinal instability at the decompression segment and adjacent segment to the decompressed segment.

CONCLUSIONS

 Microendoscopic spinal decompression is an effective treatment alternative for patients with LSS caused by ASD. The ability to perform neural decompression while maintaining key stabilizing structures minimizes subsequent clinical instability. The substantial clinical and economic benefits of this approach may make it a favorable alternative to performing concurrent fusion in many patients.

Can L5 Be Trusted During Proximal Extension of Fusion? A Case Series and a Review of the Literature

Background

Debate on whether to stop fusion at L5 or to extend fusion to S1 in a long spinal construct has been a controversial topic in spine surgery. Fewer data are available to support whether to include a prior solid fusion at L4-L5 or to extend to S1 during a proximal extension of fusion to T10. The purpose of this review is to report and discuss 2 cases of L5 vertebra fracture after proximal extension of solid L4-L5 fusion to T10 and to provide a guideline to surgeons based on the available literature.

Methods

Case report and literature review.

Results

Literature review identified multiple publications with levels of evidence from level 2 to level 4. Advanced L5-S1 degeneration with long-segment fusion to L5 is reported to be greater than 60% with a new rate of symptom development approaching 20%-25%. There is no prior literature specific to L5 fracture development after thoracic lumbar fusion with the lowest instrumented level at a fused L4-L5 segment. Reoperation rate is not consistently affected by the lowest instrumented vertebral level L5 versus sacrum/ilium.

Conclusions

Literature review is inconclusive as to the need to include the lumbosacral junction when performing a proximal extension of fusion from L5 to the thoracic spine, especially during a revision adult deformity surgery. Stress of the long lever arm of a long-segment thoracolumbar fusion above a prior solid L4-L5 fusion could cause the L5 vertebra to split in the coronal plane, resulting in vertebral body fracture even with a mildly degenerated disc at L5-S1 prior to surgery.

Level of Evidence

4.

Adult revision surgery of prior hook-and-rod wire instrumentation for idiopathic scoliosis

Adolescent idiopathic scoliosis patients treated with spinal fusion may develop adjacent segment disease and curve progression into adulthood. Revision operations can be challenging, especially for adult patients treated with outdated instrumentation such as sublaminar hooks and/or wires. The authors demonstrate revision lumbar spine surgery in a 38-year-old female with scoliosis progression from junctional degeneration below a prior T5–L3 posterior instrumented arthrodesis with a hook-and-rod wire system. They also demonstrate safe application of an ultrasonic bone scalpel for completion of a Smith-Petersen osteotomy. The patient provided written, informed consent for all material presented in this case demonstration.

The video can be found here: https://youtu.be/3PmaFtNcqKc.

Comparison of long fusion terminating at L5 versus the sacrum in treating adult spinal deformity: a meta-analysis

Purpose

Choosing an optimal distal fusion level for adult spinal deformity (ASD) is still controversial. To compare the radiographic and clinical outcomes of distal fusion to L5 versus the sacrum in ASD, we conducted a meta-analysis.

Methods

Relevant studies on long fusion terminating at L5 or the sacrum in ASD were retrieved from the PubMed, Embase, Cochrane, and Google Scholar databases. Then, studies were manually selected for inclusion based on predefined criteria. The meta-analysis was performed by RevMan 5.3.

Results

Eleven retrospective studies with 1211 patients were included in meta-analysis. No significant difference was found in overall complication rate (95% CI 0.60 to 1.30) and revision rate (95% CI 0.59 to 1.99) between fusion to L5 group (L group) and fusion to the sacrum group (S group). Significant lower rate of pseudarthrosis and implant-related complications (95% CI 0.29 to 0.64) as well as proximal adjacent segment disease (95% CI 0.35 to 0.92) was found in L group. Patients in S group obtained a better correction of lumbar lordosis (95% CI − 7.85 to − 0.38) and less loss of sagittal balance (95% CI − 1.80 to − 0.50).

Conclusion

Our meta-analysis suggested that long fusion terminating at L5 or the sacrum was similar in scoliosis correction, overall complication rate, revision rate, and improvement in pain and disability. However, fusion to L5 had advantages in lower rate of pseudarthrosis, implant-related complications, and proximal adjacent segment disease, while fusion to the sacrum had advantages in the restoration of lumbar lordosis, maintenance of sagittal balance, and absence of distal adjacent segment disease.

Graphic abstract

These slides can be retrieved under Electronic Supplementary Material.

Stopping at Sacrum Versus Nonsacral Vertebra in Long Fusion Surgery for Adult Spinal Deformity: Meta-Analysis of Revision with Minimum 2-Year Follow-Up

OBJECTIVE

A pooled comparison was conducted on a revision to the sacrum (S) versus a nonsacral (NS) surgical strategy in adult spinal deformity (ASD).

METHODS

Strictly following the PRISMA 2009 guidelines, the MEDLINE, EMBASE, and Cochrane Library databases were used to search for studies published in English up to March 2018 that addressed the S versus NS surgical approach for a long fusion to treat ASD. Data on total revisions and revision reasons were extracted from the included studies and were pooled analyzed.

RESULTS

Eight retrospective studies with a total of 1846 ASD patients (528 S and 1318 NS) were included. The total revision rate was 11.38% (S: 17.80% and NS: 8.80%), and implant failure, pseudarthrosis, adjacent segment degeneration, and proximal junctional kyphosis (PJK) were common reasons for revision. The pooled results indicated that the NS group had decreased incident rates of total revision (95% confidence interval [CI] 1.20-2.32, P = 0.002; I2 = 0%) and pseudarthrosis (95% CI 2.16-15.44, P = 0.0005; I2 = 0%) compared with the S group. No significant differences were observed in implant failure (95% CI 0.86-3.90, P = 0.12; I2 = 0%), adjacent segment degeneration (95% CI 0.08-1.25, P = 0.10; I2 = 0%), and PJK (95% CI 0.54-6.88, P = 0.35; I2 = 0%) between the 2 groups.

CONCLUSIONS

Revision in ASD patients is a serious problem with a total rate of 11.38%, and implant failure, pseudarthrosis, adjacent segment degeneration, and PJK are common reasons for revision. Stopping at the sacrum vertebra in long fusion surgery on ASD patients seems to increase the incidence rates of total revision and pseudarthrosis.

Anatomical Study of a Novel Iliosacral Screw Placement for Sacrum-Pelvis in Adult Via Computed Tomography Reconstruction

STUDY DESIGN

This is a cross-sectional study.

OBJECTIVE

To investigate the feasibility and safety of a novel iliosacral screw placement for sacrum-pelvis in adult pelvis by computed tomography (CT) reconstruction.

SUMMARY OF BACKGROUND DATA

The optimal technique of spino-pelvic fixation is still being developed and redefined. However, neither the relevant anatomic parameters nor the potential spinal canal involvement for a novel iliosacral screw placement have been clearly analyzed.

METHODS

A total of 60 adults with normal pelvis, with the age ranging from 24 to 79 years old, were included in this study. Based on three-dimensional (3D) CT reconstruction of each pelvis, virtual iliosacral screw channel was identified bilaterally, the trajectory of which was characterized with the optimal width and length from the ilium to the sacrum. The virtual iliosacral screw channel that holding the greatest width and length of osseous channel was measured by rotating the 3D pelvis. Measurements of the determined channel on either side included iliosacral-screw-related and connector-related parameters.

RESULTS

There was a virtual iliosacral screw channel passing through the ilium, the iliosacral joint and then into the sacrum on either side of each pelvis. The caudal angle, convergent angle, and maximal length were 16.3 ± 3.0°, 61.3 ± 5.9°, 97.0 ± 5.6 mm in male, respectively. In female, they were 16.4 ± 3.9°, 63.0 ± 5.5° and 96.2 ± 6.0 mm, respectively. The ideal direction of the connector was from posteromedial to anterolateral. The cephalad angle, divergent angle, and embedding depth of the connector were 28.0 ± 5.7°, 28.7 ± 5.9° and 19.0 ± 2.9 mm in male, respectively. In female, they were 26.7 ± 6.1°, 27.0 ± 5.5° and 16.4 ± 2.6 mm, respectively.

CONCLUSION

It is safe and feasible to place the iliosacral screw when performing this novel instrumentation. Preoperative CT imaging and 3D reconstructions may help to determine the correct entry point and the trajectory of iliosacral screw.

LEVEL OF EVIDENCE

5.

Management of Pediatric Posttraumatic Thoracolumbar Vertebral Body Burst Fractures by Use of Single-Stage Posterior Transpedicular Approach

PURPOSE

The posterior transpedicular approach (PTA) is a posterior approach that has the advantage of achieving circumferential arthrodesis by a single posterior-only approach. The purpose of this study was to analyze our experience with PTA in the management of pediatric traumatic thoracolumbar burst fractures (TTLBFs).

METHODS

Consecutive pediatric patients (age ≤18 years) with TTLBFs treated with PTA for 6 years were included in this retrospective study. Correction of kyphotic deformity and change in neurologic status were analyzed to assess outcome. The Cobb angle and American Spinal Injury Association (ASIA) grade were used for this purpose.

RESULTS

There were 6 male and 8 female patients. Five patients had complete injury (ASIA-A), and 9 had incomplete injury. The mean Thoracolumbar Injury Classification and Severity score was 6.71. The mean preoperative Cobb angle was 14.71° and improved to -3.35° postoperatively (mean kyphosis correction -18.05°). Two of the patients experienced iatrogenic nerve root injury. There was 1 postoperative mortality due to complications unrelated to the surgery. The mean Cobb angle was -0.07° at the 32.2-month follow-up visit. Six patients experienced cage subsidence, but none required revision surgery. Postoperatively, 11 (78.5%) patients showed neurologic improvement, and none experienced deterioration. The average ASIA score improved from 2.5 to 3.78. A fusion rate of 100% (n = 12) was observed at the last follow-up visit.

CONCLUSIONS

The present study demonstrates that PTA is a feasible approach in selected pediatric patients with unstable traumatic thoracolumbar burst fractures, with results comparable with those in the adult population. This study demonstrates in detail the procedure, along with the neurologic and radiologic outcomes of this approach in the pediatric population.

Temporary Percutaneous Pedicle Screw Stabilization Without Fusion of Adolescent Thoracolumbar Spine Fractures

BACKGROUND

Pediatric spine trauma often results from high-energy mechanisms. Despite differences in healing potential, comorbidities, and length of remaining life, treatment is frequently based on adult criteria; ligamentous injuries are fused and bony injuries are treated accordingly. In this study, we present short-term results of a select group of adolescent patients treated using percutaneous pedicle screw instrumentation without fusion.

METHODS

An IRB-approved retrospective review was performed at a level 1 pediatric trauma center for thoracolumbar spine fractures treated by percutaneous pedicle screw instrumentation. Patients were excluded if arthrodesis was performed or if instrumentation was not removed. Demographics, injury mechanism, associated injuries, fracture classification, surgical data, radiographic measures, and complications were collected. Radiographs were analyzed for sagittal and coronal wedge angles and vertebral body height ratio and statistical comparisons performed on preoperative and postoperative values.

RESULTS

Between 2005 and 2013, 46 patients were treated surgically. Fourteen patients (5 male, 9 female) met inclusion criteria. Injury mechanisms included 8 motor vehicle collisions, 4 falls, and 2 all-terrain vehicle/motorcycle collisions. There were 8 Magerl type A injuries, 4 type B injuries, and 2 type C injuries. There was 1 incomplete spinal cord injury. Implants were removed between 5 and 12 months in 12 patients and after 12 months in 2 patients. Statistical analysis revealed significant postoperative improvement in all radiographic measures (P<0.05). There were no neurological complications, 1 superficial wound dehiscence, and 2 instrumentation failures (treated with standard removal). At last follow-up, 11 patients returned to unrestricted activities including sports. Average follow-up was 9 months after implant removal and 19.3 months after index procedure.

CONCLUSIONS

Adolescent thoracolumbar fractures present unique challenges and treatment opportunities different from the adult patient. We present a nonconsecutive series of 14 patients temporarily stabilized with percutaneous pedicle screw fixation for injuries including 3-column fracture dislocations and purely ligamentous injuries. Temporary fusionless instrumentation can provide successful management of select thoracolumbar spine injuries in pediatric trauma patients.

LEVEL OF EVIDENCE

Level IV-Retrospective case series.

Proximal junctional kyphosis and failure-diagnosis, prevention, and treatment

Technical advancements have enabled the spinal deformity surgeon to correct severe spinal mal-alignment. However, proximal adjacent segment pathology (ASP) remains a significant issue. Examples include proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). Agreement on the definition, classification, and pathophysiology of PJK and PJF remains incomplete, and an understanding of the risk factors, means of prevention, and treatment of this problem remains to be elucidated. In general, PJK is a relatively asymptomatic radiographic diagnosis managed with patient reassurance and monitoring. On the other hand, PJF is characterized by mechanical instability, pain, and more severe kyphosis, with potential for neurologic compromise. Patients who develop PJF more often require revision surgery than those with PJK. This chapter will review the current understanding of PJK and PJF.

Computed Tomography Findings Associated with Clinical Outcome After Dynamic Posterior Stabilization of the Lumbar Spine

OBJECTIVE

To evaluate whether preoperative multirow detector computed tomography (MDCT) findings were associated with clinical outcome 24 months after dynamic stabilization for painful degenerative lumbar spine disease.

METHODS

Preoperative MDCT examinations of 63 patients (66 ± 11.7 years; 60% women) treated with a dynamic screw rod system for painful degenerative segmental instability with/without spinal stenosis were assessed for quantitative and qualitative parameters defining degenerative changes of the thoracolumbar spine, including grades of disc herniation, degenerative spondylolisthesis, vertebral body sclerosis, cross-sectional area of the spinal canal at disc level, intervertebral disc height, ancillary bone mineral density, and anteroposterior diameter of intervertebral foramina. Clinical performance was assessed at baseline and 24 months with quantitative scales, including the Oswestry Disability Index and Short-Form 36 physical component summary. For statistical analysis classification and regression trees, linear regression and nonparametric tests were used.

RESULTS

Clinical scores improved substantially over 24 months compared with preoperative values (delta Oswestry Disability Index -32.1 ± 17.2, delta Short-Form 36 physical component summary 4.9 ± 2.3). Physical component summary improvement was significantly better in patients with lower grades of disc herniation (P < 0.001) and/or spondylolisthesis (P = 0.011), lower cross-sectional area of the spinal canal (P = 0.043), high intervertebral disc height (P = 0.006), and high grades of vertebral body sclerosis (P = 0.002). Patients with high bone mineral density and initially low diameter of intervertebral foramina showed a significantly better improvement of Oswestry Disability Index (P < 0.05).

CONCLUSIONS

Clinical improvement after dynamic stabilization was significantly associated with 7 independent baseline imaging findings. Preoperative evaluation of these MDCT parameters may improve therapy selection for patients with degenerative lumbar spine disease.

Biomechanical Analysis of Pedicle Screw Fixation for Thoracolumbar Burst Fractures

Treatment of unstable thoracolumbar burst fractures remains controversial. Long-segment pedicle screw constructs may be stiffer and impart greater forces on adjacent segments compared with short-segment constructs, which may affect clinical performance and long-term out come. The purpose of this study was to biomechanically evaluate long-segment posterior pedicle screw fixation (LSPF) vs short-segment posterior pedicle screw fixation (SSPF) for unstable burst fractures. Six unembalmed human thoracolumbar spine specimens (T10-L4) were used. Following intact testing, a simulated L1 burst fracture was created and sequentially stabilized using 5.5-mm titanium polyaxial pedicle screws and rods for 4 different constructs: SSPF (1 level above and below), SSPF+L1 (pedicle screw at fractured level), LSPF (2 levels above and below), and LSPF+L1 (pedicle screw at fractured level). Each fixation construct was tested in flexion-extension, lateral bending, and axial rotation; range of motion was also recorded. Two-way repeated-measures analysis of variance was performed to identify differences between treatment groups and functional noninstrumented spine. Short-segment posterior pedicle screw fixation did not achieve stability seen in an intact spine (P<.01), whereas LSPF constructs were significantly stiffer than SSPF constructs and demonstrated more stiffness than an intact spine (P<.01). Pedicle screws at the fracture level did not improve either SSPF or LSPF construct stability (P>.1). Long-segment posterior pedicle screw fixation constructs were not associated with increased adjacent segment motion. Al though the sample size of 6 specimens was small, this study may help guide clinical decisions regarding burst fracture stabilization. [Orthopedics. 2016; 39(3):e514-e518.].

Fracture of fusion mass after hardware removal in patients with high sagittal imbalance

OBJECT

As spinal fusions become more common and more complex, so do the sequelae of these procedures, some of which remain poorly understood. The authors report on a series of patients who underwent removal of hardware after CT-proven solid fusion, confirmed by intraoperative findings. These patients later developed a spontaneous fracture of the fusion mass that was not associated with trauma. A series of such patients has not previously been described in the literature.

METHODS

An unfunded, retrospective review of the surgical logs of 3 fellowship-trained spine surgeons yielded 7 patients who suffered a fracture of a fusion mass after hardware removal. Adult patients from the West Virginia University Department of Orthopaedics who underwent hardware removal in the setting of adjacent-segment disease (ASD), and subsequently experienced fracture of the fusion mass through the uninstrumented segment, were studied. The medical records and radiological studies of these patients were examined for patient demographics and comorbidities, initial indication for surgery, total number of surgeries, timeline of fracture occurrence, risk factors for fracture, as well as sagittal imbalance.

RESULTS

All 7 patients underwent hardware removal in conjunction with an extension of fusion for ASD. All had CT-proven solid fusion of their previously fused segments, which was confirmed intraoperatively. All patients had previously undergone multiple operations for a variety of indications, 4 patients were smokers, and 3 patients had osteoporosis. Spontaneous fracture of the fusion mass occurred in all patients and was not due to trauma. These fractures occurred 4 months to 4 years after hardware removal. All patients had significant sagittal imbalance of 13-15 cm. The fracture level was L-5 in 6 of the 7 patients, which was the first uninstrumented level caudal to the newly placed hardware in all 6 of these patients. Six patients underwent surgery due to this fracture.

CONCLUSIONS

The authors present a case series of 7 patients who underwent surgery for ASD after a remote fusion. These patients later developed a fracture of the fusion mass after hardware removal from their previously successfully fused segment. All patients had a high sagittal imbalance and had previously undergone multiple spinal operations. The development of a spontaneous fracture of the fusion mass may be related to sagittal imbalance. Consideration should be given to reimplanting hardware for these patients, even across good fusions, to prevent spontaneous fracture of these areas if the sagittal imbalance is not corrected.

Compression fracture in the middle of a chronic instrumented fusion that developed into pseudarthrosis after balloon kyphoplasty

There are only 2 documented cases of vertebral compression fractures occurring within a solid lumbar fusion mass: one within the fusion mass after hardware removal and the other within the levels of the existing instrumentation 1 year postoperatively. The authors report a case of fracture occurring in a chronic (> 30 years) solid instrumented fusion mass in a patient who underwent kyphoplasty. The pain did not improve after the kyphoplasty procedure, and the patient developed a posterior cleft in the fusion mass postoperatively. The patient, a 46-year-old woman, had undergone a T4-L4 instrumented fusion with placement of a Harrington rod when she was 12 years old. Adjacent-segment breakdown developed, and her fusion was extended to the pelvis, with pedicle screws placed up to L-3 to capture the existing fusion mass. Almost 2 years after fusion extension, she fell down the stairs and suffered an L-2 compression fracture, which is when kyphoplasty was performed without pain relief, and she then developed a cleft in the posterior fusion mass that was previously intact. She refused further surgical options. This case report is meant to alert surgeons of this possibility and allow them to consider the rare occurrence of fracture within the fusion mass when planning extension of chronic spinal fusions.