Influence of bacteria on spinal implant-centered infection: an in vitro and in vivo experimental comparison between Staphylococcus aureus and mycobacterium tuberculosis

Implant-associated Mycobacterium tuberculosis infection (IMTI) in long-term, well-fixed implants

Background

Orthopedic device infections caused by Mycobacterium tuberculosis, including Periprosthetic joint infection (PJI), are rare and peculiar due to its poor adherence to implant surface and weak ability of biofilm formation. We present successful treatment of 2 cases of implant associated Mycobacterium tuberculosis infection (IMTI) by meticulous surgical debridement and long-term anti-tubercular chemotherapy with retention of implant.

Case descriptions

Case 1 : A case of Culture-Negative PJI, 4 years after left total hip replacement (THR) caused by M. tuberculosis. The patient presented with acute onset (<7 days) low grade fever and development of discharging sinus from the site of left surgical scar mark. Case 2: A patient with Kuntscher nailing done for open fracture right femur 22 years ago presented to clinic with complaints of discharging sinus (<7 days) from the surgical scar mark on right side. Both patients had negative cultures on presentation and underwent meticulous debridement with implant retention. Intra-operative samples were positive for M. tuberculosis on CB-NAAT and histopathology. They underwent successful treatment with 18 months of Anti Tubercular Treatment (ATT) without any relapse at 2 year-follow-up.

Conclusion

Atypical, late onset discharging sinus with negative cultures should raise suspicion of IMTI. Intra-operative deep tissue samples should be analyzed for CB-NAAT for M. tuberculosis and histopathological analysis in all these cases. Meticulous debridement with 18 months chemotherapy poses viable option for successful treatment of IMTI, allowing retention of prosthesis.

Diagnostic Role of Metagenomic Next-Generation Sequencing in Tubercular Orthopedic Implant-Associated Infection

Objective

The diagnosis of tubercular orthopedic implant-associated infection (TB-IAI) is challenging. This study evaluated the value of metagenomic next-generation sequencing (mNGS) for the diagnosis of TB-IAI and developed a standardized diagnostic procedure for TB-IAI.

Methods

The records of all patients with TB-IAI diagnosed and treated at our institution between December 2018 and September 2022 were retrospectively reviewed. Patient demographic characteristics, medical history, laboratory test, microbial culture, histopathology, and mNGS results, and time to diagnosis were recorded. The diagnostic efficiency of mNGS for TB-IAI was assessed by comparing the results and diagnostic time with that of other diagnostic modalities.

Results

Ten patients were included in the analysis, including eight with prosthetic joint infections and two with fracture-related infections. The mNGS positivity rate was 100% (10/10), which was higher than that of TB-antibody (11%, 1/9), real-time quantitative polymerase chain reaction (22%, 2/9), T-SPOT.TB (25%, 2/8), purified protein derivative (50%, 4/8), microbial culture (50%, 5/10), and histopathology (20%, 2/10). mNGS shortened the time to diagnosis of TB-IAI. A standardized diagnostic procedure for TB-IAI was developed based on the findings.

Conclusion

mNGS is useful for the diagnosis of TB-IAI. mNGS is recommended in cases where it is difficult to identify a pathogen using routine diagnostic tests. The standardized diagnostic procedure might improve TB-IAI diagnosis.

Importance

TB-IAI is a rare infection, which occurs after orthopedic surgery and hard to diagnose microbiologically. mNGS is a new detection technique not yet discussed in current literature as a means for TB-IAI diagnostics. Here we describe a cohort of patients with TB-IAI diagnosed by mNGS show high efficiency of mNGS for detection of this pathology and present a clinical algorithm supplementing conventional methods for TB-IAI assessment.

A comparison of anterior reconstruction of spinal defect using nano-hydroxyapatite/polyamide 66 cage and autologous iliac bone for thoracolumbar tuberculosis: a stepwise propensity score matching analysis

Purpose

Previous studies have confirmed the advantages and disadvantages of autogenous iliac bone and nano-hydroxyapatite/polyamide 66 (n-HA/PA66) cage. However, there is no conclusive comparison between the efficacy of the two implant materials in spinal tuberculosis bone graft fusion. The aim of this study was to analyze the mid-to long-term clinical and radiologic outcomes between n-HA/PA66 cage and autogenous iliac bone for anterior reconstruction application of spinal defect for thoracolumbar tuberculosis.

Methods

We retrospectively reviewed all patients who underwent anterior debridement and strut graft with n-HA/PA66 cage or iliac bone combined with anterior instrumentations between June 2009 and June 2014. One-to-one nearest-neighbor propensity score matching (PSM) was used to match patients who underwent n-HA/PA66 cage to those who underwent iliac bone. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) and visual analogue score (VAS). Radiographic evaluations included cage subsidence and segmental angle.

Results

At the end of the PSM analysis, 16 patients from n-HA/PA66 cage group were matched to 16 patients in Iliac bone group. The C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) values in the n-HA/PA66 group decreased significantly from 33.19 ± 10.89 and 46.63 ± 15.65 preoperatively, to 6.56 ± 2.48 and 9.31 ± 3.34 at the final follow-up, respectively (p < 0.001). There were no significant differences in the CRP and ESR values between the two groups at the final follow-up. The VAS and JOA scores in the iliac bone and n-HA/PA66 group were significantly improved at the 3-month follow-up postoperatively (both p < 0.001). Then, improvements of VAS and JOA scores continue long at final follow-up. However, there were no significant differences in the VAS and JOA scores at any time point between the two groups (p > 0.05). Although the segmental angle (SA) significantly increased after surgery in both groups, there was no significant difference at any time point after surgery (p > 0.05). There were no significant differences in the cage subsidence and fusion time between the two groups.

Conclusion

Overall, our data suggest that the n-HA/PA66 cage outcomes are comparable to those in the autogenous iliac bone, with a similar high fusion rate as autogenous iliac bone.

A case of prosthetic joint infection caused by Mycobacterium tuberculosis complicated secondary bacterial infection after knee joint replacement surgery

Mycobacterium tuberculosis (M. tuberculosis) is a rare cause of prosthetic joint infection (PJI). Previous studies have reported that many cases of PJI caused by M. tuberculosis have no medical history of active tuberculosis (TB) or other localization, which contributes to diagnostic difficulties. Furthermore, owing to the limited number of studies on treatment, appropriate treatment strategies, such as the duration of anti-tuberculosis (anti-TB) drugs and surgical indications, remain unclear. We report a case of PJI caused by M. tuberculosis and secondary pyogenic arthritis caused by Staphylococcus aureus and Streptococcus dysgalactiae in a 67-year-old man after knee joint replacement surgery in Japan, which was a moderately endemic country until 2020 and a low endemic country since 2021. Although he had no past medical history or close contact with TB, he was diagnosed with PJI caused by M. tuberculosis, following the culture of a synovectomy specimen. He underwent two-stage surgery and was treated with anti-TB drugs for a total of 12 months and recovered without recurrence. Based on our case and previous studies, there are three points of clinical significance for PJI caused by M. tuberculosis. First, about one year of anti-TB drugs with two staged joint revision resulted in a good course of treatment. Second, surgical treatment might be considered in cases complicated by secondary bacterial infection. Third, because the diagnosis of PJI caused by M. tuberculosis is difficult, TB should be considered in the differential diagnosis of routine bacterial culture-negative PJI, especially in endemic areas.

Comparison between single anterior and single posterior approaches of debridement interbody fusion and fixation for the treatment of mono-segment lumbar spine tuberculosis

PURPOSE

To compare the efficacy of single anterior and single posterior approach of debridement, interbody fusion, and fixation for the treatment of mono-segment lumbar spine tuberculosis (TB) patients.

METHODS

Eighty-seven patients with mono-segment lumbar TB who underwent debridement, interbody fusion, and fixation through either single anterior (Group A) or single posterior approach (Group B) from January 2007 to January 2017 were enrolled in this study. The duration of the operation, blood loss, complication rate, visual analog scale (VAS), Oswestry disability index (ODI), Frankel scale, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), kyphosis angle, correction rate, correction loss, and time taken for bone graft fusion were compared between the groups.

RESULTS

The average period of follow-up was 34.3 ± 9.5 months (24-56 months). No significant differences were observed between patients in Group A and patients in Group B in terms of gender, age, body mass index (BMI), duration of illness and preoperative evaluative indices (P > 0.05). The mean operation time and blood loss was significantly higher in Group A (P = 0.000), along with a slightly higher rate of complications compared with Group B (P = 0.848). The VAS, ODI and Frankel scale scores showed significant improvement in both groups (P = 0.000), along with the ESR, CRP and kyphosis indices (P = 0.000), which were similar in both groups at the final follow-up.

CONCLUSION

Both single anterior and single posterior approaches of debridement, interbody fusion and fixation are effective for mono-segment lumbar TB patients, although the single posterior approach is of a shorter duration and results in less blood loss.

Animal Models for Postoperative Implant‐Related Spinal Infection

Postoperative infections following implant‐related spinal surgery are severe and disastrous complications for both orthopaedic surgeons and patients worldwide. They can cause neurological damage, disability, and death. To better understand the mechanism of these destructive complications and intervene in the process, further research is needed. Therefore, there is an urgent need for efficient, accurate, and easily available animal models to study the pathogenesis of spinal infections and develop new and effective anti‐bacterial methods. In this paper, we provide a general review of the commonly used animal models of postoperative implant‐related spinal infections, describe their advantages and disadvantages, and highlight the significance of correctly choosing the model according to the infection aspect under investigation. These models are valuable tools contributing to the better understanding of postoperative spinal infections and will continue to facilitate the invention of novel preventative and treatment strategies for patients with postoperative spinal infections. However, although they are valid and reproducible in some respects, the current animal models present certain limitations. Future ideal spinal infection animal models may assess the bacterial load of the same animal in real‐time in vivo, and better mimic the human anatomy as well as surgical techniques. Strains other than Staphylococcus aureus account for a large proportion of postoperative spinal infections, and thus, the establishment of models to evaluate other types of microbial infections is expected in the future. Furthermore, novel transgenic models established on advancements in genome editing are also likely to be developed in the future.

Early periprosthetic infection: dilution, jet dilution or local antibiotics. Which way to go? A meta-analysis on 575 patients

Objective: Periprosthetic infections (PPI) after total hip and total knee arthroplasty (THA, TKA) are subdivided into early and late infections. Early PPIs are defined as the occurrence of infection within 6 weeks following the primary surgery. Aim of therapy in early PPI is the retention of the prosthesis using dilution, jet dilution or local antibiotics. However, as of yet, no evidence is available supporting these procedures. The aim of this study was to evaluate their success rates.

Methods: We conducted a systematic literature review of studies reporting on early PPI. Clinical trials published after 1990 that reported success or failure rates as the primary outcome were included. A meta-analysis using the Scheffé-Test showed if there are any advantages of single treatment concepts.

Results: We identified 575 patients over 10 studies. Success rates were diverse: Undergoing dilution without jet lavage revealed treatment success in 49.48%, using jet dilution increased the success rate to 78.26%. Local antibiotics were successfully used in 55% of the cases. The meta-analysis compared the three interventions and showed no significant difference in using dilution, jet dilution or local antibiotics. Even combining local antibiotics and dilution/jet dilution does not provide significantly higher success rates.

Conclusion: Previous studies showed differences in methods and results, however pooling the data of these studies for our meta-analysis didn’t show significant advantages. We therefore conclude that studies conducted until thus far cannot provide any recommendation as to whether using dilution, jet dilution, local antibiotics or any combination of three is better for treating early PPI cases.

Antibiotic-impregnated polymethylmethacrylate strut graft as a treatment of spinal osteomyelitis: case series and description of novel technique

OBJECTIVE

The surgical treatment of osteomyelitis and discitis of the spine often represents a challenging clinical entity for a multitude of reasons, including progression of infection despite debridement, development of spinal deformity and instability, bony destruction, and seeding of hardware. Despite advancement in spinal hardware and implantation techniques, these aforementioned challenges not uncommonly result in treatment failure, especially in instances of heavy disease burden with enough bony endplate destruction as to not allow support of a modern titanium cage implant. While antibiotic-infused polymethylmethacrylate (aPMMA) has been used in orthopedic surgery in joints of the extremities, its use has not been extensively described in the spine literature. Herein, the authors describe for the first time a series of patients treated with a novel surgical technique for the treatment of spinal osteomyelitis and discitis using aPMMA strut grafts with posterior segmental fusion.

METHODS

Over the course of 3 years, all patients with spinal osteomyelitis and discitis at a single institution were identified and included in the retrospective cohort if they were surgically treated with spinal fusion and implantation of an aPMMA strut graft at the nidus of infection. Basic demographics, surgical techniques, levels treated, complications, and return to the operating room for removal of the aPMMA strut graft and placement of a traditional cage were examined. The surgical technique consisted of performing a discectomy and/or corpectomy at the level of osteomyelitis and discitis followed by placement of aPMMA impregnated with vancomycin and/or tobramycin into the cavity. Depending on the patient's condition during follow-up and other deciding clinical and radiographic factors, the patient may return to the operating room nonurgently for removal of the PMMA spacer and implantation of a permanent cage with allograft to ultimately promote fusion.

RESULTS

Fifteen patients were identified who were treated with an aPMMA strut graft for spinal osteomyelitis and discitis. Of these, 9 patients returned to the operating room for aPMMA strut graft removal and insertion of a cage with allograft at an average of 19 weeks following the index procedure. The most common infections were methicillin-sensitive Staphylococcus aureus (n = 6) and methicillin-resistant S. aureus (n = 5). There were 13 lumbosacral infections and 1 each of cervical and thoracic infection. Eleven patients were cured of their infection, while 2 had recurrence of their infection; 2 patients were lost to follow-up. Three patients required unplanned return trips to the operating room, two of which were for wound complications, with the third being for recurrent infection.

CONCLUSIONS

In cases of severe infection with considerable bony destruction, insertion of an aPMMA strut graft is a novel technique that should be considered in order to provide strong anterior-column support while directly delivering antibiotics to the infection bed. While the active infection is being treated medically, this structural aPMMA support bridges the time it takes for the patient to be converted from a catabolic to an anabolic state, when it is ultimately safe to perform a definitive, curative fusion surgery.

Mycobacterium bovis infection of total hip arthroplasty after intravesicular Bacillus Calmette-Guérin

Intravesicular application of Bacillus Calmette-Guérin (BCG), a live attenuated strain of Mycobacterium bovis, is effective in the treatment of bladder cancer. However, systemic dissemination and subsequent infection of implants have been reported. We present a case of M. bovis infection of a total hip arthroplasty 5 years after BCG instillation for bladder cancer. He was treated with debridement, antibiotics, irrigation, and prosthesis retention with appropriate antituberculous therapy. At 4 years after surgery and 3 years after cessation of treatment, he has had no recurrence of infection with a good functional outcome. This case highlights the need to consider Mycobacteria infection in patients who have received intravesicular BCG. Debridement and retention of well-fixed implants can be successful in combination with appropriate antituberculous therapy.

Surgical management for middle or lower thoracic spinal tuberculosis (T5-T12) in elderly patients: Posterior versus anterior approach

BACKGROUND

Spinal tuberculosis accounts for more than 50% of bone tuberculosis cases. This study compared clinical, radiological and functional outcomes between anterior and posterior approaches for treatment of middle or lower thoracic spinal tuberculosis in elderly patients.

METHODS

We retrospectively examined middle or lower thoracic spinal tuberculosis (T5-T12) in patients over 65 years. All procedures included debridement, decompression, autologous bone graft and fixation. Surgical procedure, surgical duration, estimated blood loss during surgery and laboratory results were recorded. Pleural effusion volume, thoracic cavity volume, Oswestry Disability Index score, neurological status, radiological parameters and complication rate were evaluated.

RESULTS

No significant difference was found in surgical duration, blood loss, kyphosis angle correction, loss of correction, thoracic cavity volume, or complication rate between the two groups (P > 0.05). Average postoperative pleural effusion volumes were 605.9 ± 209.5 mL (377-1074 mL) and 262.9 ± 228.1 mL (0-702.4 mL) in the anterior and posterior groups, respectively (P = 0.004). Average hospitalization durations were 26.4 ± 10.5 days (17-53 days) and 19.2 ± 5.0 days (14-30 days) (P = 0.04). Average postoperative serum albumin levels were 24.19 ± 3.84 g/L (19-29.5 g/L) and 28.24 ± 2.52 g/L (24.4-31.6 g/L) (P = 0.01). No relapse or reinfection was observed in either group at the final follow-up. Surgical revision was not required in either group.

CONCLUSIONS

Both anterior and posterior surgeries can be used to treat middle or lower thoracic spinal (T5-T12) tuberculosis in elderly patients. In general, the posterior approach might be superior, especially for patients with poor general health.

Single-stage anterior debridement, posterior instrumentation and global fusion in thoracic and thoracolumbar tubercular spondylodiscitis

PURPOSE

The present study evaluated the clinical and radiological outcomes in patients with tuberculosis of the thoracic and thoracolumbar spine, treated by an operative technique in which anterior debridement with posterior instrumentation and global fusion was performed through a single-stage posterior approach.

METHODS

Ninty-seven patients with spinal tuberculosis, between T1 and L1, in whom anterior debridement, bone grafting, with posterior instrumentation and fusion was performed through a single-stage posterior approach, with a minimum follow-up of 2 years, formed the basis of this study. During each follow-up, neurological recovery was assessed using modified American Spinal Injury Association grading, healing of the disease was assessed by appearance of sclerosis and interbody fusion and the degree of kyphotic deformity was analysed using the modified Konstam's angle.

RESULT

Two hundred and twenty-six lesions were found in the radiographs of 97 patients with 28.9% of them having multiple lesions. The mean ± SD preoperative, post-operative, and 2-year follow-up kyphotic angle were 49.5 ± 18.4°, 22.6 ± 7.1° and 24.5 ± 7.6°, respectively, and showed significant kyphosis correction (P < 0.01). Sclerosis was seen as early as 3 months in 82(84.5%) patients whereas interbody fusion started appearing at the end of 6 months in 38.14% of patients and peaked at 1 year. All patients recovered neurologically, with no significant loss of kyphosis correction, at final follow-up.

CONCLUSION

The surgical technique described in this study had favourable clinical and radiological outcomes. Early surgery helps in having a definitive diagnosis and detects the presence of drug-resistant strains.

Mycobacterium tuberculosis prosthetic joint infections: A case series and literature review

OBJECTIVES

We aimed to characterize diagnosis, management, and outcome of Mycobacterium tuberculosis prosthetic joint infections (PJI).

METHODS

Cases of M. tuberculosis PJI documented in 7 referral French centers were retrospectively reviewed. Data were collected from medical files on a standardized questionnaire. We performed a literature review using the keywords 'prosthetic joint', and 'tuberculosis'.

RESULTS

During years 1997-2016, 13 patients (8 males, 5 females, median age 79 years [range, 60-86]) had documented M. tuberculosis PJI, involving hip (n = 6), knee (n = 6), or shoulder (n = 1). Median time from arthroplasty to diagnosis was 9 years [0.4-20]. The diagnosis was obtained on joint aspirates (n = 9), or synovial tissue (n = 4). PCR was positive in all cases tested (5/5). Median duration of antituberculosis treatment was 14 months [6-32]). Nine patients underwent surgery: debridement (n = 4), resection arthroplasty (n = 3), and revision arthroplasty (1-stage exchange, n = 2). PJI was controlled in 12 patients. Seventeen additional cases of documented M. tuberculosis PJI have been reported, with a favorable outcome in 79% (11/14) of patients with no surgery, 85% (11/13) with debridement, 86% (19/22) with revision arthroplasty, and 81% (17/21) with resection (NS).

CONCLUSIONS

M. tuberculosis PJI can be controlled with prolonged antituberculosis treatment in most cases, with or without surgical treatment.

Tubercular prosthetic joint infection: two case reports and literature review

PURPOSE

Tubercular prosthetic joint infection (TB-PJI) is an uncommon complication. Lack of evidence of systemic tuberculosis and clinical suspicion could bring a delay in the time of the diagnosis. The aims of this study are to underline the importance of awareness and suspicion of mycobacterial infection in the differential diagnosis in PJI and to evaluate the appropriateness of different therapeutic options.

METHODS

Case report and literature review.

RESULTS

We report two cases of TB-PJI after total knee arthroplasty in Caucasian patients without prior history of tubercular disease or exposure. In both cases, the diagnosis was obtained years after the onset of symptoms. Despite that, both patients improved during antitubercular treatment (a four-drug regimen consisting of rifampicin, isoniazid, ethambutol, and pyrazinamide for 2 months, followed by rifampicin and isoniazid). Moreover, after an 18-month course of treatment, there was no need for surgical therapy. The result of the literature review allows us to identify 64 cases of TB-PJI. Many differences in both medical and surgical management have been found, among those reviewed cases.

CONCLUSIONS

Considering our experience and the literature review, we recommend considering a conservative approach (debridement and adequate antituberculous chemotherapy) as a suitable and safe option.

Adding Functions to Biomaterial Surfaces through Protein Incorporation

The concept of biomaterials has evolved from one of inert mechanical supports with a long-term, biologically inactive role in the body into complex matrices that exhibit selective cell binding, promote proliferation and matrix production, and may ultimately become replaced by newly generated tissues in vivo. Functionalization of material surfaces with biomolecules is critical to their ability to evade immunorecognition, interact productively with surrounding tissues and extracellular matrix, and avoid bacterial colonization. Antibody molecules and their derived fragments are commonly immobilized on materials to mediate coating with specific cell types in fields such as stent endothelialization and drug delivery. The incorporation of growth factors into biomaterials has found application in promoting and accelerating bone formation in osteogenerative and related applications. Peptides and extracellular matrix proteins can impart biomolecule- and cell-specificities to materials while antimicrobial peptides have found roles in preventing biofilm formation on devices and implants. In this progress report, we detail developments in the use of diverse proteins and peptides to modify the surfaces of hard biomaterials in vivo and in vitro. Chemical approaches to immobilizing active biomolecules are presented, as well as platform technologies for isolation or generation of natural or synthetic molecules suitable for biomaterial functionalization.

Surgical treatment for pyogenic vertebral osteomyelitis using iodine-supported spinal instruments: initial case series of 14 patients

Reports have detailed the increasing use of spinal instrumentation in the treatment of pyogenic vertebral osteomyelitis, with the aims of achieving a lower pseudoarthrosis rate and restoring spinal alignment. However, controversy remains over the use of instrumentation in the presence of active infection because of concerns about increased bacterial adherence and biofilm formation on the metallic implant surface. Fourteen consecutive patients were followed who were diagnosed as having pyogenic vertebral osteomyelitis and underwent surgery with spinal instrumentation with iodine-containing surfaces that could be directly supported to existing titanium implants. Bone-cage interfaces and implant-related complications after surgery were evaluated. The white blood cell (WBC) count and C-reactive protein (CRP) level were analyzed during the follow-up period. To confirm the influence of iodine release from the implant, thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were also examined. The infection subsided in all 14 patients. Both WBC counts and CRP levels returned to normal ranges by the final follow-up. One patient showed a lucent area around the screw and two patients showed lucencies inside the cage. However, no cage dislocations, cage migrations, or screw pull-outs were noted, and all patients' FT3, FT4, and TSH levels were within normal ranges during the follow-up period. We demonstrated the efficacy of iodine-supported titanium implants in the management of pyogenic vertebral osteomyelitis. No cytotoxicity or adverse effects were noted in this series.

Antibiofilm agents and implant-related infections in orthopaedics: where are we?

Orthopaedics is currently the largest market of biomaterials worldwide and implant-related infections, although relatively rare, remain among the first reasons for joint arthroplasty and osteosynthesis failure. Bacteria start implant infection by adhering to biomaterials and producing biofilms, which represent a major reason for bacterial persistence, in spite of antibiotic treatment and host's defence. In the last two decades, a number of different antibiofilm agents have been studied and both in vitro and in vivo results appear now promising, even if their effective role in orthopaedics remains to be assessed. In this review, we introduce an original classification of antibiofilm agents, based on their mechanism of action and examine the available data concerning their possible application to orthopaedic implant-related infections. Molecules that interfere with biofilm production (biofilm prevention agents) include anti-adhesion compounds, quorum sensing inhibitors, non-steroideal anti-inflammatory drugs, and antimicrobial peptides; N-acetylcysteine and specific enzymes promise the greatest therapeutic possibilities by disrupting established biofilms (biofilm disrupting agents). The identification of antimicrobials able to bypass the biofilm barrier (biofilm bypassing agents), and antibiofilm vaccines are further strategies aimed to reduce the impact of biofilm-related infections, opening new pathways in controlling implant-related infections. However, this review shows that still insufficient knowledge is currently available as to regard the efficacy and safety of the investigated antibiofilm strategies to treat infection that involve bone tissue and biomaterials commonly implanted in orthopaedics, pointing out the need for further research in this promising field.

Bacteria detected after instrumentation surgery for pyogenic vertebral osteomyelitis in a canine model

OBJECTIVE

This study was designed to identify the presence, type and origin of bacteria adjacent to the metal implant in the infected region in a canine model of pyogenic vertebral osteomyelitis treated with single-stage anterior autogenous bone grafting and instrumentation.

METHODS

Dogs with pyogenic spondylodiscitis underwent one-stage debridement, autogenous bone grafting and titanium plate instrumentation and perioperative antibiotic therapy. The implants and adjacent vertebral bones were removed surgically at various postoperative time points (4, 8, 12 and 24 weeks) for bacteria detection. Bacteria were detected from retrieved spinal implants as well as surrounding bones by culture and/or pyrosequencing methods in 17 (85%) of all 20 animals. The positive rate for bacteria presence was 45% by culture and 80% by pyrosequencing method.

RESULTS

Radiological or macroscopic examination showed no signs for infection recurrence in any animal regardless of bacteria presence at the surgical site. However, organism identical with the causative bacterium for spinal infection was found in only two of nine culture-positive animals.

CONCLUSION

Within the confines of the study, the use of metallic implants in an infected area did not lead to a clinically relevant infection although bacteria may exist at the surgical site. The use of metallic implants in an infected area of the spine is safe. The metallic implants may not be the “culprit” for the persistence or recurrence of infection.

Surgical treatment of acute TB spondylitis: indications and outcomes

Introduction

Spinal tuberculosis represents a challenging disease to treat, not because of the technical expertise or the time required to cure it, but more so because of the decisions involved to treat it. The Medical Research Council (MRC) Working Party on Tuberculosis of the Spine designed trials to help address several questions.

Methods

A comprehensive literature search was performed using PubMed Medline, including English articles from 1934 to 1012, which pertain to spinal tuberculosis, with special effort in tracing the 13 MRC reports. The primary focus was on disease eradication, fusion rate, and a secondary focus on both short and long-term results in terms of disease recurrence and alignment. Additional searches were made on the use of spinal implants for infection cases.

Results

After reviewing MRC and non-MRC reports, it was evident that the “Hong Kong operation”, which involved radical debridement and strut grafting the lesion, produced better short-, medium- and long-term results in such aspects as fusion rate, spinal deformity and relapse of abscess/sinus. Subsequent work by others demonstrated the importance of prevention of progressive kyphosis, therefore the need to identify risk factors for these and pre-emptive measures such as kyphosis correction, careful graft selection, and instrumentation.

Conclusion

Improvement in quality of life is also accompanied by higher patient expectations. Though developing nations may lack the resources now, eventually patients will demand better functional and cosmetic results after being afflicted by this disfiguring and potentially disabling disease, and the “Hong Kong operation” represented the best outcome, provided resources were available.