Recent advances: Infections of the spine

Imaging of Spondylodiscitis: A Comprehensive Updated Review-Multimodality Imaging Findings, Differential Diagnosis, and Specific Microorganisms Detection

Spondylodiscitis is defined by infectious conditions involving the vertebral column. The incidence of the disease has constantly increased over the last decades. Imaging plays a key role in each phase of the disease. Indeed, radiological tools are fundamental in (i) the initial diagnostic recognition of spondylodiscitis, (ii) the differentiation against inflammatory, degenerative, or calcific etiologies, (iii) the disease staging, as well as (iv) to provide clues to orient towards the microorganisms involved. This latter aim can be achieved with a mini-invasive procedure (e.g., CT-guided biopsy) or can be non-invasively supposed by the analysis of the CT, positron emission tomography (PET) CT, or MRI features displayed. Hence, this comprehensive review aims to summarize all the multimodality imaging features of spondylodiscitis. This, with the goal of serving as a reference for Physicians (infectious disease specialists, spine surgeons, radiologists) involved in the care of these patients. Nonetheless, this review article may offer starting points for future research articles.

CT fluoroscopy-guided percutaneous intervertebral drain insertion for cervical pyogenic spondylodiscitis

A 79-year-old man was admitted to our hospital with C6-C7 pyogenic spondylodiscitis with an epidural abscess. Since the cervical intervertebral space is narrower than the thoracolumbar intervertebral space, drain insertion into the cervical intervertebral space requires a more accurate procedure. Moreover, the specific anatomy of cervical vertebrae, which includes the transverse foramen through which the vertebral artery passes and the uncinate process on the side edges of the top surface of the bodies, makes it impossible to perform computed tomography (CT)-guided percutaneous intervertebral drain insertion through the posterolateral approach. Therefore, CT fluoroscopy-guided percutaneous cervical intervertebral drain insertion using a lateral approach, in which the needle is advanced between the carotid sheath and scalene muscle, and simultaneous intravenous contrast enhancement might be a safe and useful technique. There have been no papers on CT fluoroscopy-guided percutaneous intervertebral drain insertion for cervical pyogenic spondylodiscitis, while successful CT fluoroscopy-guided percutaneous intervertebral drain insertion for thoracolumbar pyogenic spondylodiscitis has been reported. Here, we successfully performed CT fluoroscopy-guided percutaneous intervertebral drain insertion for cervical pyogenic spondylodiscitis.

Clinical experience of extreme lateral interbody fusion in the treatment of lumbar spondylodiscitis

Introduction

Up to now, there were few studies on extreme lateral interbody fusion (XLIF) surgery for lumbar spondylodiscitis. This study was aimed to evaluate clinical effectiveness and provide more information for XLIF in the treatment of lumbar spondylodiscitis.

Methods

We retrospectively collected cases of XLIF for the treatment of lumbar spondylodiscitis from September 2017 to February 2020. There were 8 cases of non-specific infection of lumbar spine, 4 cases of lumbar tuberculosis, and 1 case of lumbar brucellosis. Basic information, antibiotic application, and inflammatory index were collected before and after surgery. Clinical effectiveness was evaluated at baseline and in 3, 6, and 12 months after the surgery with visual analog scale (VAS) and Oswestry disability index (ODI). The comparison of the indicators before and after the operation was performed by repeated measures analysis of variance.

Results

The average intraoperative blood loss and operation time was 70mL and 99.23 min, respectively. The study consisted of 13 cases with single segment operation. The average follow-up time was 16.54 months. No sign of recurrence of spondylodiscitis occurred at last follow-up. Postoperative VAS and ODI were significantly decreased after the operation. No major blood vessels, nerves, or organ damage occurred during the perioperative period.

Conclusion

XLIF has shown good clinical effectiveness in the treatment of lumbar spondylodiscitis with advantages of less bleeding and less tissue damage in the present study. More multi-center prospective comparative studies are needed to further verify the clinical effectiveness of this procedure in lumbar spondylodiscitis.

Spondylodiscitis: A Retrospective Analysis of Clinical, Etiological, and Radiological Diagnosis

Background

Spondylodiscitis is an uncommon disease, and due to its indolent nature, it is often a late diagnosis. Great stress is put on the etiologic diagnosis, but blood cultures do not always yield positive results. Magnetic resonance imaging (MRI), despite being the diagnostic method of choice, is not always available. Our aim was to characterize the clinical presentation and to identify and check the efficacy of the etiologic and radiological methods of diagnosis of spondylodiscitis used at our hospital.

Methods

A retrospective study was conducted in which spontaneous spondylodiscitis cases were identified. The clinical presentation and the results of etiologic and radiological methods of diagnosis were analyzed.

Results

Over a period of 5 years, 34 patients fulfilled the inclusion criteria of the study. Regarding days of complaints, we identified a median of 9.5 days (1-547 days), with back pain being the predominant symptom. Fever was present in half the patients. Blood cultures were positive in 16 patients (48.5%). Nineteen patients underwent a computed tomography (CT)-guided biopsy (positive in 7 patients [36.8%]), and 10 patients underwent a surgical biopsy (positive in half of them). Overall, 27 patients (79.4%) had an etiologic diagnosis. The diagnostic work-up consisted mostly of an initial CT scan followed by a confirmatory MRI. Of note, in 5 patients the CT scan did not reveal changes that were later confirmed by MRI. A total of 29 patients (85.3%) underwent an MRI, with 28 being diagnostic.

Conclusions

Spondylodiscitis remain a difficult diagnosis. Blood cultures should always be obtained before antibiotic administration and a CT-guided or surgical biopsy should be done if needed. Our results confirm the importance of MRI as the imaging modality of choice and highlight the possibility of false-negative CT scans and the inability of CT to allow for a definitive diagnosis.

Transport of Vancomycin and Cefepime Into Human Intervertebral Discs: Quantitative Analyses

STUDY DESIGN

Simulation of antibiotics transport into human intervertebral disc with intravenous infusion.

OBJECTIVE

The objective of this study was to quantitatively investigate antibiotic concentrations in the disc.

SUMMARY OF BACKGROUND DATA

Intravenous infusion of antibiotics is typically used to treat intervertebral disc infection in clinics. However, it is difficult to evaluate the drug concentrations within discs in vivo.

METHODS

A computational model was used in this study. The variation of drug charge with pH was considered in the model. Thirty-minute infusions of two commonly used antibiotics in clinic-vancomycin and cefepime-were numerically investigated. Spatial and temporal concentration distributions of these drugs in both nondegenerated and moderately degenerated discs were calculated.

RESULTS

For intravenous infusion of 1 g vancomycin and 2 g cefepime in 30 minutes repeated every 12 hours, it was predicted that vancomycin concentration in the disc fluctuated between 17.0 and 31.0 times of its minimum inhibitory concentration (1 ug/mL) and cefepime concentration fluctuated between 1.1 and 4.2 times of its minimum inhibitory concentration (i.e., 8 ug/mL) in about 2 days. It was also found that vancomycin concentration in moderately degenerated disc was lower than that in the nondegenerated disc.

CONCLUSION

This study provides quantitative guidance on selecting proper dosage for treating disc infection. The method used in this study could be used to provide quantitative information on transport of other antibiotics and drugs in discs as well.

LEVEL OF EVIDENCE

N/A.

A unilateral less invasive posterolateral approach for disc debridement and titanium cage insertion supplemented by contralateral transfascial screw fixation for high-morbidity patients suffering from septic thoracolumbosacral spondylodiscitis

PURPOSE

This case series reports on the efficacy and safety of a less invasive posterolateral approach for septic thoracolumbosacral spondylodiscitis in high-morbidity patients.

METHODS

Twenty consecutive severe sick (ASA > III) patients (14 men and 6 women), with an average age of 64 ± 14 years, suffering from septic subacute and chronic thoracolumbosacral spondylodiscitis were selected to undergo a one-stage less invasive unilateral posterolateral disc space debridement, supplemented by an ipsilateral titanium cage implantation and pedicle screw fixation plus a contralateral transfascial pedicle screw fixation.

RESULTS

Two high-risk patients with severe comorbidities (ASA stage IV and V, respectively) died on days 1 and 8 postoperatively because of non-surgical complications such as massive lung embolism and acute myocardial infract, respectively. Three patients with incomplete paraplegia (ASIA C) preoperatively were improved after the surgery to ASIA D (two patients) and E (one patient), respectively, while there was no neurological deterioration in any patient postoperatively. From the 18 patients that survived, ten patients were available for the final follow-up 8.8 ± 2.7 years postoperatively. In two patients with spondylodiscitis caused by gram(-) bacteria, the posterior instrumentation was finally removed because of asymptomatic fistula emerging from posterior instrumentation solely, 15 and 19 months after surgery. The survivals at 2.5 and 10 years with revision as end point was 87.4% (95% CI 58.1-96.7); while in the "worst case scenario" the survivals at 2.5 and 10 years were: 66.7% (95% CI 40.4-83.4%); 47.7% (95% CI 23.2-68.8%) and 47.7% (95% CI 23.2-68.8%), respectively.

CONCLUSIONS

The less invasive posterolateral approach for disc debridement and titanium cage insertion seems to be an alternative surgery for severe sick adult immunosuppressed patients with septic thoracolumbosacral spondylodiscitis that cannot tolerate traditional open transthoracic, thoracolumbar, retroperitoneal or combined approaches. The study has been registered in the Public Registry ClinicalTrials.gov PRS with the ID: NCT03472131.

Effects of diurnal loading on the transport of charged antibiotics into intervertebral discs

The objective of this study was to quantitatively analyze the effect of diurnal loading on the transport of various charged antibiotics into negatively charged human intervertebral disc (IVD). Transport of charged antibiotics into a human lumbar disc was analyzed using a 3D finite element model. The valence (z) of the electrical charge of antibiotics varied from z = +2 (positively charged) to z = -2 (negatively charged). An uncharged antibiotic (z = 0) was used as a control. Cases with transient antibiotic concentration at disc boundaries [to mimic intravenous (IV) infusion] were simulated. Our results showed that diurnal compression increased the concentrations in the nucleus pulposus (NP) region, but degreased the concentrations in the annulus fibrosus (AF) region for all charged or non-charged drugs. The overall concentration (averaged over disc) increased with diurnal compression. The diurnal compression had more effects on negatively charged antibiotics than positively charged ones. For example, at day 5 with diurnal compression, the diurnal compression increased the concentration of negatively charged drug (z = -1) in NP by 18.3%, but only by 6.6% for positively charged one (z = +1). In AF, diurnal compression decreased the concentration by 13.2% for negatively charged drug (z = -1) versus 1.2% for positively charged one (z = +1). Note these percentages are the averaged values over day 5. This study provides quantitative information on understanding the mechanisms of charged drug transport in human IVDs.

Diagnosis and management of spinal infections

The number of spinal infections has been increasing due to aging populations and larger numbers of immunocompromised hosts and intravenous drug users. Magnetic resonance imaging is a useful tool for the early diagnosis of spinal infections, and can yield positive findings just 3-5 days after disease onset. Before antibiotic administration, cultures must be initiated from blood and from specimens collected from the locus of infection. Based on the pathogens identified by culture, appropriate antibiotics should be selected with careful consideration of antimicrobial susceptibility and spinal tissue penetration. Antibiotic treatment of spinal infections should be continued for longer than for most other types of infections, although the optimal duration remains unknown. The indications for surgical treatment include progressive neurologic deficits, progressive deformity, spinal instability, persistent or recurrent infection, and unbearable pain. In most patients with spinal infection, the gold standard surgical treatment is anterior radical debridement followed by autologous strut bone grafting. The addition of posterior instrumentation has recently become popular. This procedure may be performed alone as an alternative surgical option in patients in poor condition, and if it dramatically reduces pain, subsequent observation may be reasonable. If progressive deformity is observed or pain relief is inadequate after posterior instrumentation, additional anterior debridement and bone grafting should be scheduled.

CT Fluoroscopy-Guided Transsacral Intervertebral Drainage for Pyogenic Spondylodiscitis at the Lumbosacral Junction

PURPOSE

To retrospectively describe the feasibility and efficacy of CT fluoroscopy-guided transsacral intervertebral drainage for pyogenic spondylodiscitis at the lumbosacral junction with a combination of two interventional radiological techniques-CT-guided bone biopsy and abscess drainage.

MATERIALS AND METHODS

Three patients with pyogenic spondylodiscitis at the lumbosacral junction were enrolled in this study between July 2013 and December 2015. The procedure of CT fluoroscopy-guided transsacral intervertebral drainage for pyogenic spondylodiscitis at the lumbosacral junction was as follows: the sacrum at S1 pedicle was penetrated with an 11-gauge (G) bone biopsy needle to create a path for an 8-French (F) pigtail drainage catheter. The bone biopsy needle was withdrawn, and an 18-G needle was inserted into the intervertebral space of the lumbosacral junction. Then, a 0.038-inch guidewire was inserted into the intervertebral space. Finally, the 8-F pigtail drainage catheter was inserted over the guidewire until its tip reached the intervertebral space. All patients received six-week antibiotics treatment.

RESULTS

Successful placement of the drainage catheter was achieved for each patient without procedural complications. The duration of drainage was 17-33 days. For two patients, specific organisms were isolated; thus, definitive medical therapy was possible. All patients responded well to the treatment.

CONCLUSIONS

CT fluoroscopy-guided transsacral intervertebral drainage for pyogenic spondylodiscitis at the lumbosacral junction is feasible and can be effective with a combination of two interventional techniques-CT fluoroscopy-guided bone biopsy and abscess drainage.

Does Pathogen Identification Influence the Clinical Outcomes in Patients With Pyogenic Spinal Infections?

STUDY DESIGN

Retrospective study.

OBJECTIVE

To study the clinical outcomes of patients suffering from pyogenic spinal infections (PSI), by comparing the outcomes of patients with an identified microbiological agent with those of patients without an identified pathogen.

SUMMARY OF BACKGROUND DATA

PSI is associated with significant risks for morbidity and mortality. Specific antibiotic treatment has been considered a key to successful medical treatment; however, clinicians frequently treat patients with PSI without an identified agent. A paucity of data is available comparing the clinical outcomes of patients with or without an identified pathogen.

MATERIALS AND METHODS

The records of 97 consecutive patients discharged from a University Hospital with the diagnosis of PSI during a 14-year period were retrospectively reviewed. Patients' demographics, etiological agent, comorbidities, site of infection, white blood cell count, erythrocyte sedimentation rate, C-reactive protein at the time of presentation, neurological impairment, length of hospital stay, and mortality were registered to compare the clinical outcomes of patients with an identified pathogen with those of patients without an identified agent.

RESULTS

The causative organism was identified in 74 patients (76.3%). Patients with microbiological diagnosis were younger, and a larger percentage of them exhibited elevated C-reactive protein value; however, they were not different from those without an identified agent in terms of sex, site of infection, comorbidities, and the presence of a concomitant infection. Our study could not demonstrate different neurological outcomes, length of stay, or mortality rates among the 2 groups.

CONCLUSIONS

In a large series of patients with PSI, we did not demonstrate differences in clinical outcomes using empirical antibiotics in patients without an identified pathogen compared with patients with an identified microbiological agent receiving specific antibiotics. Future prospective multicenter studies should be conducted to obtain an answer to this important clinical question.

Management of adult spontaneous spondylodiscitis and its rising incidence

INTRODUCTION

Spondylodiscitis refers to the infection of the intervertebral disc and osteomyelitis of the adjacent endplates, and it is uncommon in the developed world. Broad consensus indicates its incidence is on the rise.

METHODS

The aim of this retrospective study was twofold. First, we sought to give an up-to-date incidence estimate by comparing case presentation over two time periods (1995-1999 and 2008-2011). Data from the England and Wales census in 2001 and 2011 were used for incidence estimation. The second part of this study aimed to generate management guidance from data from medical and radiographic records of the 2008-2011 patient cohort.

RESULTS

The incidence of adult spontaneous spondylodiscitis in the local region between 2008 and 2011 was 3.67/100,000 per year, representing a 150% increase from the incidence in 1995-1999. Our data demonstrate that methicillin sensitive Staphylococcus aureus remains the most common offending pathogen of spontaneous spondylodiscitis. The mean C-reactive protein (CRP) level remained at >30mg/l after a month of starting antibiotic treatment in both medically and surgically managed groups.

CONCLUSIONS

Evidence suggests that the incidence of spondylodiscitis is on the rise. A review of our case series has demonstrated the effectiveness of intravenous antibiotic therapy. While no official guidance exists for when to switch from intravenous to oral antibiotics, our study shows that CRP at 1 month is >30mg/l and we recommend 6 weeks of intravenous therapy, followed by 6 further weeks of oral therapy.

Cervical pyogenic spinal infections: are they more severe diseases than infections in other vertebral locations?

PURPOSE

Cervical spine pyogenic infections are unusual compared to other vertebral segments, but they can be associated to worse clinical outcomes. We compared all patients with cervical spine pyogenic infections to those with thoracolumbar involvement in terms of epidemiology, prognostic factors and clinical outcomes.

METHODS

We retrospectively reviewed all patients discharged from our institution with diagnosis of pyogenic spinal infections (PSI) during a 14-year period. Patients' demographics, etiologic agent, co-morbidities, site of infection, white blood cell count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) at time of presentation, neurological impairment and mortality were registered to compare clinical outcomes of patients with PSI affecting the cervical spine and other segments.

RESULTS

We studied 102 patients with PSI. Nineteen (18.6 %) had cervical involvement; 73.7 % of them were males, with a mean age of 65.22 years. 89.7 % of them presented spondylodiscitis; 12 patients (63.2 %) exhibited a one segment involvement (C5-C6 being the most common), and 11 patients presented an epidural abscess. Thirteen patients (68.4 %) exhibited neurological deficit. Seventeen patients (89.5 %) presented elevated ESR and CRP, while 12 patients (63.2 %) exhibited leukocytosis. The causative organism was identified in 17 patients (89.5 %). Despite similar baseline characteristics, compared to PSI in other locations, patients with cervical PSI presented significantly more neurological involvement (68.4 vs. 41 %; p = 0.03), they more often required surgical treatment (84.2 vs. 46.3 %; p < 0.01), and they had and increased mortality (21.1 % compared to 3.6 %; p = 0.02).

CONCLUSION

An early diagnosis and prompt treatment should be the goal treating cervical PSI, considering the potential devastating complications and increased mortality.

Diagnostic yield of fluoroscopy-guided biopsy for infectious spondylitis

BACKGROUND AND PURPOSE

CT is currently the method of choice for guiding biopsy of lesions of the spine. However, in our hospital, fluoroscopy-guided percutaneous biopsy has been preferred for several years because of equipment availability and easy craniocaudal angulation. The aim of this study was to evaluate the efficacy of fluoroscopy-guided percutaneous biopsy in a clinical setting for diagnosing infectious spondylitis.

MATERIALS AND METHODS

A retrospective study was performed to evaluate 170 fluoroscopy-guided percutaneous biopsies in 140 patients (male/female = 70:70; mean age, 65.1 years; range, 16-89 years) in a clinical setting who were suspected of having infectious spondylitis between July 2003 and March 2010. Diagnosis was based on pathologic confirmation by tissue or culture from biopsy. The percentage of adequate specimens for diagnosis, histopathologic diagnosis for infectious spondylitis, and positive cultures for causative organisms were evaluated by retrospective review of medical records.

RESULTS

Adequate specimens for diagnosis were obtained in 165 of 170 cases (97.1%). The diagnosis of infectious spondylitis resulted in 134 of 170 cases confirmed through histopathology or clinical outcome (78.8%). In 51 of 134 cases (38.1%), the causative organism was confirmed by specimens from percutaneous bone biopsy. There were no biopsy-related major complications. The most common organism isolated was Mycobacterium tuberculosis (24 cases), followed by Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus viridans.

CONCLUSIONS

Fluoroscopy-guided percutaneous biopsy is as accurate and effective as CT-guided biopsy for diagnosing infectious spondylitis.

CT-guided percutaneous drainage within intervertebral space for pyogenic spondylodiscitis with psoas abscess

BACKGROUND

Reports on CT-guided percutaneous drainage within the intervertebral space for pyogenic spondylodiscitis with a secondary psoas abscess are limited.

PURPOSE

To evaluate CT-guided percutaneous drainage within the intervertebral space for pyogenic spondylodiscitis and a secondary psoas abscess in which the two sites appear to communicate.

MATERIAL AND METHODS

Eight patients with pyogenic spondylodiscitis and a secondary psoas abscess showing communication with the intradiscal abscess underwent CT-guided percutaneous drainage within the intervertebral space. The clinical outcome was retrospectively assessed.

RESULTS

An 8-French pigtail catheter within the intervertebral space was successfully placed in all patients. Seven patients responded well to this treatment. The one remaining patient who had developed septic shock before the procedure died on the following day. The mean duration of drainage was 32 days (13-70 days). Only one patient with persistent back pain underwent surgery for stabilization of the spine after the improvement of inflammation. Among seven patients responding well, long-term follow-up (91-801 days, mean 292 days) was conducted in six patients excluding one patient who died of asphyxiation due to aspiration unrelated to the procedure within 30 days after the procedure. In these six patients, no recurrence of either pyogenic spondylodiscitis or the psoas abscess was noted.

CONCLUSION

CT-guided percutaneous drainage within the intervertebral space can be effective for patients with pyogenic spondylodiscitis and a secondary psoas abscess if the psoas abscess communicates with the intradiscal abscess.

Penetration of linezolid into rabbit intervertebral discs and surrounding tissues

Linezolid belongs to a new class of synthetic antimicrobial agent that is effective for a variety of methicillin-resistant Staphylococcus aureus (MRSA) infections including bone and joint MRSA infections, but the effectiveness of linezolid for the treatment of MRSA spine infection remains controversial. In this study, we investigated the diffusion of linezolid or vancomycin into normal rabbit spinal tissues to determine the adequacy of linezolid for the treatment of spinal infection. The penetration efficacy of linezolid into the annulus fibrosus, nucleus pulposus, and vertebral bone (10, 8, and 10%, respectively) was lower than that of vancomycin (27, 11, and 14%, respectively). The penetration efficacy of linezolid into the bone marrow and iliopsoas muscle (88 and 84%, respectively), however, was higher than that of vancomycin (67 and 9%, respectively). These results suggest that linezolid is inadequate for the treatment of spine infection limited to the intervertebral disc, but may be effective for the treatment of infection extending into the muscle and bone marrow, such as in vertebral osteomyelitis, iliopsoas abscess, and postsurgical infection.

Evaluation of conservative treatment of non specific spondylodiscitis

The objective of this study was to analyse the presentation, aetiology, conservative management, and outcome of non-tuberculous pyogenic spinal infection in adults. We performed a retrospective review of 56 patients (35 women and 21 men) of pyogenic spinal infection presenting over a 7-year period (1999-2006) to the Department of Spinal Surgery of Hesperia Hospital. The medical records, radiologic imaging, bacteriology results, treatment, and complications of all patients were reviewed. The mean age at presentation was 47.8 years (age range 35-72 years), the mean follow-up duration was 12.5 months. The most common site of infection was lumbar spine (n: 48), followed by the thoracic spine (n: 8). Most patients were symptomatic for between 4 and 10 weeks before presenting to hospital. The frequently isolated pathogen was Staphylococcus aureus in 31 of 56 cases (57.6%). Percutaneous biopsies were diagnostic in 57% of patients; the open biopsy was indicated if closed biopsy failed and when the infection was not accessible by percutaneous technique. The patients were managed by conservative measures alone, including antibiotic therapy and spinal bracing. The mean period of antibiotic therapy was 8.5 weeks (range 6-9 weeks), followed by oral antibiotics for 6 weeks. All patients had a supportive spinal brace for mean 8 weeks (range 6-10 weeks). The duration of the administration of oral antibiotics was dependent on clinical and laboratory evidence (white cell count, erythrocyte sedimentation rate, C-reactive protein) that the infection was resolved. The follow-up MR gadolinium scans were essential to monitor the response to medical treatment. The diagnosis of pyogenic spinal infection should be considered in any patient presenting with severe localised unremitting back and neck pain, especially when accompanied with systemic features, such as fever and weight loss and in the presence of elevated inflammatory markers. The conservative management of infection with antibiotic therapy and spinal bracing was very successful.

Does Acute placement of instrumentation in the treatment of vertebral osteomyelitis predispose to recurrent infection: long-term follow-up in immune-suppressed patients

STUDY DESIGN

Single institution, prospective observation study.

OBJECTIVE

To determine the long-term clinical outcomes of immune-suppressed patients with pyogenic vertebral osteomyelitis (PVO) treated with spinal instrumentation in the setting of active infection.

SUMMARY OF BACKGROUND DATA

The mainstay of treatment for PVO remains nonoperative. Surgical indications include neurologic compromise, deformity, abscess and failure of medical management. Some authors have been concerned regarding risk of local infection reoccurrence when spinal instrumentation has been placed in the setting of active infection. To our knowledge no long-term follow-up has been reported for this condition.

METHODS

Thirty-two consecutive immune compromised patients with PVO were treated with debridement and spinal instrumentation in the setting of acute infection at a single institution. Patients were observed by a set protocol and evaluated for reoccurrence of infection at regular intervals for up to 10 years.

RESULTS

The 32 patients in our study group had significant medical comorbidities and were immune compromised. All patients were treated with single stage debridement and instrumented fusion during active infection. Twenty-two patients had a full 10 years follow-up without clinical recurrence of the local infection. Four patients died during the observation period, and none had clinic or autopsy evidence of recurrence. One patient developed recurrent infection after 14 months and was successfully treated with repeat debridement and retention of the instrumentation. Although this patient had a chronically infected vascular shunt, he was disease free at final follow-up of 10 years. Four patients had their implants removed for pain, suspected nonunion or suspected recurrent infection. None of these patients had histologic or microbacteriological evidence of injection.

CONCLUSION

The use of spinal instrumentation in immune-compromised patients with PVO is associated with a low risk of long-term recurrent infection.

Long-term functional outcome in pyogenic spinal infection

STUDY DESIGN

Retrospective.

OBJECTIVE

To assess long-term adverse functional outcome following pyogenic spinal infection using standardized outcome measures, Oswestry disability index (ODI), and medical outcomes study short form-36 (SF-36).

SUMMARY OF BACKGROUND DATA

There is minimal published data regarding the long-term functional outcome in pyogenic spinal infection. Previous studies have used heterogeneous, unreliable, and nonvalidated measure instruments yielding data that is difficult to interpret.

METHODS

All cases of pyogenic spinal infection presenting to a single institution managed operatively and nonoperatively from 1994 to 2004 were retrospectively identified. Follow-up was by clinical review and standardized questionnaires. Inclusion in each case was on the basis of consistent clinical, imaging, and microbiology criteria.

RESULTS

Twenty-nine cases of pyogenic spinal infection were identified. Twenty-eight percent were managed operatively and 72% with antibiotic therapy alone. Nineteen patients (66%) had an adverse outcome at a median follow-up of 61 months, despite only 5 patients (17%) having persistent neurologic deficit. A significant difference in SF-36 physical function scores was observed between patients with adverse outcome and patients who recovered (P = 0.003). SF-36 scores of all patients, regardless of management or outcome, failed to reach those of a normative population. A strong correlation was observed between ODI and SF-36 physical function scores (rho = 0.61, P < 0.05). Seventeen percent (n = 5) of admissions resulted in acute sepsis-related death. Delay in diagnosis of spinal infection (P = 0.025) and neurologic impairment at diagnosis (P < 0.001) were significant predictors of neurologic deficit at follow-up. Previous spinal surgery was associated with adverse outcome in patients requiring readmission within 1 year of hospital discharge following first spinal infection (P = 0.018). No independent predictors of adverse outcome, persistent neurologic impairment, readmission within 1 year, or acute death were identified by logistical regression analysis.

CONCLUSION

High rates of adverse outcome detected using SF-36 and ODI suggest under-reporting of poor outcome when American Spinal Injury Association score alone is used to qualify outcome.