A post-operative spinal infection is an infection that develops after spine surgery. It may involve only the skin and incision, or it may extend deeper into the muscles, bone, disc spaces, spinal canal, or implanted hardware.
Post-operative infections can occur after surgery on the cervical, thoracic, lumbar, or sacral spine. Some infections become obvious within days or weeks after surgery, while others may not become apparent until months later.
Most spinal infections can be treated successfully, but early recognition is important. Deeper infections may require antibiotics, surgical debridement, drainage, or additional spine surgery.
What Causes a Post-Operative Spinal Infection?
Most infections are caused by bacteria that enter the surgical area.
Possible sources include:
- Bacteria from the skin
- Contamination of the surgical wound
- Bloodstream infection
- Wound breakdown
- Persistent drainage
- Infection around spinal implants
- Infection involving a bone graft or surgical space
The risk of infection varies depending on the type and complexity of surgery.
Larger operations, revision procedures, long fusion constructs, and surgeries involving extensive instrumentation may carry a higher infection risk than smaller procedures.
Superficial Versus Deep Spinal Infection
Post-operative infections are often divided into superficial and deep infections.
Superficial Infection
A superficial infection involves the skin or tissues immediately beneath the incision.
Symptoms may include:
- Redness
- Tenderness
- Swelling
- Warmth
- Drainage
These infections may sometimes be treated with local wound care and antibiotics.
Deep Infection
A deep spinal infection extends beneath the superficial tissues and may involve:
- Fascia
- Muscle
- Bone
- Disc space
- Spinal implants
- Epidural space
- Bone graft
Deep infections usually require more aggressive treatment.
Symptoms of a Post-Operative Spinal Infection
Symptoms vary depending on the depth and location of the infection.
Possible signs include:
- Increasing neck or back pain
- Pain that worsens after initially improving
- Persistent wound drainage
- Redness around the incision
- Swelling
- Fever
- Chills
- Wound separation
- Foul-smelling drainage
- Increasing arm or leg pain
- Weakness or numbness
Importantly, not every patient with a spinal infection develops a fever.
In some cases, the main sign is persistent pain or drainage from the incision.
Is Drainage From the Incision Always an Infection?
No.
A small amount of drainage during the early healing period does not always indicate infection.
However, persistent drainage, increasing drainage, cloudy drainage, or drainage associated with redness, pain, fever, or wound separation should be evaluated.
Persistent wound drainage can also increase the risk of a deeper infection developing.
Early Versus Delayed Infection
Early Infection
Early post-operative infections usually occur within the first several weeks after surgery.
They may present with:
- Drainage
- Redness
- Fever
- Increasing pain
- Wound breakdown
Delayed Infection
Delayed infections may develop months or even years after surgery.
Symptoms can be more subtle and may include:
- Chronic back or neck pain
- Hardware loosening
- Failure of spinal fusion
- Persistent inflammation
- Intermittent drainage
- Recurrent wound problems
Delayed infections may involve slower-growing organisms and can sometimes be difficult to diagnose.
Infection Around Spinal Hardware
Spinal implants such as:
- Screws
- Rods
- Plates
- Cages
- Artificial discs
can become involved in a deep infection.
Bacteria can form a protective layer called a biofilm on the surface of an implant. Biofilm can make infection more difficult to eliminate with antibiotics alone.
However, infected spinal hardware does not always have to be removed.
If the implants are necessary to maintain spinal stability, they may often be retained while the infection is treated.
Does Spinal Hardware Have to Be Removed?
Not necessarily.
The decision depends on:
- Timing of the infection
- Stability of the spine
- Whether the fusion has healed
- Type of organism
- Degree of hardware loosening
- Response to treatment
In early infections, hardware is often retained if it remains stable.
In delayed infections, hardware removal may be considered if:
- The fusion is solid
- The implants are loose
- Infection persists despite treatment
- Biofilm-related infection is suspected
- Hardware is no longer mechanically necessary
Removing necessary instrumentation from an unstable spine can create a more serious problem than leaving it in place.
How Is a Post-Operative Spinal Infection Diagnosed?
Diagnosis usually involves a combination of:
- Physical examination
- Wound evaluation
- Blood tests
- Imaging
- Cultures
Blood Tests
Laboratory testing may include:
- Complete blood count
- C-reactive protein (CRP)
- Erythrocyte sedimentation rate (ESR)
- Blood cultures
CRP is often particularly useful after surgery because it normally rises after an operation and then gradually falls.
A persistently elevated or second rise in CRP may raise concern for infection.
MRI
MRI with contrast may help identify:
- Deep soft-tissue infection
- Epidural abscess
- Discitis
- Osteomyelitis
- Fluid collections
- Nerve or spinal cord compression
Interpreting MRI shortly after surgery can be difficult because normal post-operative changes can resemble infection.
CT Scan
CT may help evaluate:
- Hardware position
- Bone destruction
- Fusion status
- Hardware loosening
- Fluid collections
- Spinal stability
CT can also be used to guide aspiration or biopsy.
Cultures
Whenever possible, identifying the organism responsible for the infection is important.
Cultures may be obtained from:
- Blood
- Wound drainage
- Fluid aspiration
- Tissue collected during surgery
Deep tissue cultures obtained during surgical debridement are often more reliable than superficial wound cultures.
The culture results help determine which antibiotics are most appropriate.
Antibiotic Treatment
Antibiotics are an important part of treatment.
The type and duration depend on:
- Responsible organism
- Depth of infection
- Presence of spinal hardware
- Bone involvement
- Bloodstream infection
- Response to treatment
Deep spinal infections often require several weeks of antibiotics.
Some patients begin with intravenous antibiotics and later transition to oral treatment.
Infectious disease specialists are often involved in managing more complicated infections.
When Is Surgery Needed?
Surgery is commonly recommended for deep post-operative infections.
Reasons may include:
- Persistent wound drainage
- Deep abscess
- Large fluid collection
- Epidural abscess
- Failure of antibiotics
- Wound breakdown
- Infected or dead tissue
- Neurologic compression
- Spinal instability
- Hardware loosening
The goal is to control the infection while preserving spinal stability.
Surgical Irrigation and Debridement
The most common operation for a deep post-operative infection is irrigation and debridement.
During the procedure, the surgeon:
- Reopens the surgical wound
- Removes infected or nonviable tissue
- Collects deep cultures
- Washes the surgical area
- Evaluates the implants
- Determines whether the wound can be closed immediately
Some patients require more than one debridement.
Can the Wound Be Closed Immediately?
Sometimes.
If the wound appears adequately cleaned and healthy tissue remains, it may be closed during the same operation.
In more severe infections, temporary wound management may be used.
Options can include:
- Negative-pressure wound therapy
- Delayed closure
- Repeat debridement
- Plastic surgery closure in selected cases
The approach depends on wound quality and the extent of infection.
Plastic Surgery and Complex Wound Closure
Large or recurrent spinal wounds sometimes require assistance from a plastic surgeon.
Muscle or soft-tissue flaps may be used to:
- Improve blood supply
- Cover exposed hardware
- Fill dead space
- Promote wound healing
This is more common after complex revision surgery or multiple previous operations.
Epidural Abscess After Spine Surgery
Infection can spread into the spinal canal and form an epidural abscess.
This can compress:
- The spinal cord
- Nerve roots
- The cauda equina
Symptoms may include:
- Increasing pain
- Weakness
- Numbness
- Difficulty walking
- Bowel or bladder dysfunction
Progressive neurologic symptoms may require urgent decompression and drainage.
Post-Operative Discitis and Osteomyelitis
Infection may also involve:
- The disc space
- Vertebral bodies
- Endplates
This is called discitis-osteomyelitis.
It can cause:
- Severe persistent pain
- Vertebral erosion
- Bone collapse
- Spinal instability
- Deformity
Treatment may include antibiotics, debridement, and sometimes reconstruction or fusion.
Can New Spinal Instrumentation Be Placed During Infection?
Yes.
If infection has caused instability or vertebral destruction, additional spinal instrumentation may be necessary.
Treatment may involve:
- Removal of infected tissue
- Decompression
- New screws or rods
- Fusion
- Vertebral reconstruction
- Long-term antibiotics
Modern spine surgery can safely use instrumentation in selected infected environments when stabilization is necessary.
Risk Factors
Factors that may increase the risk of post-operative infection include:
- Diabetes
- Obesity
- Smoking
- Poor nutrition
- Immunosuppression
- Long operations
- Revision surgery
- Multiple previous surgeries
- Large fusion constructs
- Long-term steroid use
- Cancer
- Chronic kidney disease
- Poor wound healing
Risk varies greatly from patient to patient.
Preventing Post-Operative Spinal Infection
Hospitals and surgical teams use several strategies to reduce infection risk.
These may include:
- Antibiotics before surgery
- Sterile surgical technique
- Careful skin preparation
- Blood sugar control
- Attention to nutrition
- Smoking cessation
- Careful wound closure
- Appropriate dressing and wound care
Patients can also reduce risk by following post-operative wound instructions carefully and reporting concerning changes early.
What Should Patients Watch for After Spine Surgery?
Patients should contact their surgical team if they develop:
- Persistent wound drainage
- Increasing redness
- Increasing swelling
- Fever
- Wound separation
- Increasing pain after initial improvement
- New arm or leg weakness
- New numbness
- Difficulty walking
Early evaluation can prevent a superficial or limited infection from becoming more serious.
When Is a Post-Operative Infection an Emergency?
Urgent evaluation is appropriate when infection is associated with:
- Rapidly progressive weakness
- Difficulty walking
- Paralysis
- New bowel or bladder dysfunction
- Severe spinal cord or nerve compression
- Sepsis
- Rapidly worsening wound infection
These situations may require immediate surgery.
Recovery
Recovery depends on:
- Depth of infection
- Organism involved
- Presence of hardware
- Number of debridements required
- Whether the fusion remains stable
- Overall health
Some patients recover after one debridement and a course of antibiotics.
More complicated infections may require:
- Multiple surgeries
- Prolonged antibiotic treatment
- Wound therapy
- Rehabilitation
- Revision spinal reconstruction
Outlook
Post-operative spinal infection is a serious complication, but most infections can be successfully treated.
Treatment is based on the depth of infection, responsible organism, spinal stability, neurologic function, condition of the wound, and whether spinal implants are involved.
In many cases, spinal instrumentation can be preserved while the infection is treated.
When surgery is necessary, the goals are to:
- Remove infected tissue
- Control the infection
- Protect the spinal cord and nerves
- Maintain spinal stability
- Allow the wound to heal
- Preserve the benefits of the original spine surgery
Early recognition and appropriate treatment are important for achieving the best possible outcome.
Related Topics
- Spinal Infections
- Osteomyelitis & Discitis
- Spinal Epidural Abscess
- Paraspinal Infection
- Facet Joint Infection
- Revision Spine Surgery
- Spinal Fusion
- Spinal Instrumentation