Introduction

Post-open reduction and internal fixation (ORIF) infection and post-arthroplasty infection are serious healthcare-associated musculoskeletal infections that occur following orthopaedic implant surgery. These infections involve bacterial colonization of implants, surrounding soft tissues, and bone, often resulting in biofilm formation that makes eradication difficult. If left untreated, they may lead to implant loosening, fracture non-union, chronic osteomyelitis, prosthesis failure, sepsis, limb loss, and death.

These infections are broadly classified as early or late according to the time of onset after surgery and require prompt diagnosis, microbiological confirmation, prolonged antimicrobial therapy, and appropriate surgical management.

Epidemiology

• Periprosthetic joint infection (PJI) occurs in approximately 1–2% of primary hip and knee arthroplasties.

• Infection following fracture fixation occurs in approximately 1–5% of closed fractures and up to 30% of severe open fractures.

• Incidence is increasing due to an ageing population and increasing numbers of joint replacement procedures.

• One of the leading causes of early revision arthroplasty worldwide.

Classification

according to time of inset

Early infection

• Occurs within 4 weeks after surgery.

• Usually caused by highly virulent organisms.

Late infection

• Occurs more than 4 weeks after surgery.

• Often associated with biofilm formation and low-virulence organisms.

According to type of surgery

• Post-arthroplasty infection (Periprosthetic Joint Infection)

• Fracture-related infection following ORIF

Etiology

Most infections are caused by bacterial contamination during surgery or by hematogenous spread after implantation.

Common organisms

• Staphylococcus aureus

• Coagulase-negative staphylococci (Staphylococcus epidermidis)

• Streptococcus species

• Enterococcus species

• Gram-negative bacilli

• Pseudomonas aeruginosa

• Anaerobic bacteria (less common)

Pathophysiology

1. Bacteria contaminate the surgical wound or implant.

2. Organisms adhere to implant surfaces.

3. Biofilm develops on metal implants or prostheses.

4. Biofilm protects bacteria from antibiotics and host immune responses.

5. Persistent inflammation causes bone destruction and implant loosening.

6. Chronic infection may progress to osteomyelitis and sinus tract formation.

Risk Factors

Patient-related factors

• Diabetes mellitus

• Obesity

• Malnutrition

• Smoking

• Rheumatoid arthritis

• Immunosuppression

• Chronic kidney disease

• Peripheral vascular disease

• Advanced age

Surgery-related factors

• Prolonged operative time

• Open fractures

• Revision surgery

• Poor soft tissue coverage

• Previous infection

• Hematoma formation

• Wound complications

Clinical Presentation

General Features

• Persistent pain

• Swelling

• Local warmth

• Reduced range of motion

• Delayed wound healing

• Persistent wound drainage

• Fever (may be absent)

Clinical Features of Post-Arthroplasty Infection

• Pain around the prosthetic joint

• Progressive loss of joint function

• Reduced range of motion

• Swelling

• Local warmth

• Joint effusion

• Wound erythema

• Persistent wound discharge

• Sinus tract communicating with the prosthesis

• Prosthetic instability (late disease)

Clinical Features of infection following ORIF

• Persistent fracture-site pain

• Delayed fracture healing

• Non-union

• Persistent wound drainage

• Implant exposure

• Local tenderness

• Erythema

• Swelling

• Sinus formation

• Fever in severe infection

Diagnostic Criteria

Diagnosis is based on clinical, laboratory, microbiological, and radiological findings.

Major criteria

• Sinus tract communicating with the implant or prosthesis

• Two or more cultures yielding the same pathogen from synovial fluid, bone, or periprosthetic tissue

Minor criteria

• Persistent wound drainage

• Elevated CRP

• Elevated ESR

• Elevated white blood cell count

• Purulent joint aspirate

• Positive synovial fluid culture

• Positive histopathology

• Imaging suggestive of implant infection

• Intraoperative evidence of infection

Investigations

Laboratory Investigations

• Complete blood count with differential

• Erythrocyte sedimentation rate (ESR)

• C-reactive protein (CRP)

• Blood cultures when systemic infection is suspected

• Aspirated pus for culture and sensitivity

• Synovial fluid culture and sensitivity

• Bone biopsy or periprosthetic tissue biopsy for culture and sensitivity

Imaging

Plain X-ray

May demonstrate:

• Periosteal reaction

• Implant loosening

• Osteolysis

• Subchondral bone resorption

• Non-union

• Bone destruction

Bone Scan (Technetium-99)

Useful in early infection when radiographs are inconclusive.

CT Scan

Recommended for complex anatomical regions including:

• Pelvis

• Shoulder

• Spine

MRI

Useful during the acute stage where metal artefact reduction techniques are available to evaluate:

• Soft tissue abscess

• Osteomyelitis

• Extent of infection

Differential diagnosis

• Aseptic implant loosening

• Mechanical implant failure

• Crystal arthropathy

• Inflammatory arthritis

• Osteonecrosis

• Fracture non-union without infection

• Soft tissue haematoma

Management

Successful treatment requires a multidisciplinary approach involving orthopaedic surgeons, infectious disease specialists, microbiologists, physiotherapists, and rehabilitation teams.

Management includes:

• Early diagnosis

• Microbiological confirmation

• Appropriate antimicrobial therapy

• Surgical intervention

• Rehabilitation

• Correction of underlying risk factors

Pharmacological Management

General principles

• Begin empirical intravenous antibiotics after obtaining appropriate microbiological specimens whenever clinically feasible.

• Modify antimicrobial therapy according to culture and antimicrobial susceptibility results.

• Continue treatment until CRP has normalized and clinical improvement is achieved.

Recommended regimens

Vancomycin

• 1 g IV every 12 hours for 6 weeks

OR

Clindamycin

• 600 mg IV every 8 hours for 6 weeks

AND

Ceftazidime

• 2 g IV every 12 hours for 6 weeks

OR

Cefepime

• 2 g IV every 12 hours for 6 weeks

OR

Meropenem

• 500 mg to 1 g IV every 8 hours for 6 weeks

Surgical Management

Post-Arthroplasty Infection

Stage 1

• Removal of the infected prosthesis

• Thorough surgical debridement

• Placement of an antibiotic-loaded cement spacer

• Administration of antibiotics for 6 weeks

Stage 2

Performed after clinical improvement and normalization of inflammatory markers.

• Reimplantation using antibiotic-loaded cement

• Use of stemmed prosthetic components where indicated

Surgical Site Infection Following ORIF

Stage 1

• Extensive surgical debridement

• Removal of infected metal implants

• Stabilization using external fixation, traction, or orthosis where appropriate

Stage 2

• Revision internal fixation after CRP and other inflammatory markers have normalized and infection has been adequately controlled

Supportive Management

• Rest and splintage of the affected limb or joint for the first 48 hours

• Adequate nutritional support

• Correction of predisposing conditions such as diabetes and anaemia

• Physiotherapy to restore range of motion and muscle strength

• Walking aids when pathological fracture or instability is present

• Adequate hydration

• Antipyretics for fever

• Appropriate analgesia for pain control

• Venous thromboembolism prophylaxis where indicated

Monitoring and follow-up

Patients should be monitored regularly for:

• Clinical improvement

• Resolution of pain and swelling

• Wound healing

• Serial CRP and ESR

• White blood cell count

• Repeat cultures if treatment failure is suspected

• Radiographic evidence of fracture healing or implant stability

• Adverse effects of prolonged antibiotic therapy

• Functional recovery

Complications

• Chronic osteomyelitis

• Implant loosening

• Prosthesis failure

• Fracture non-union

• Delayed union

• Periprosthetic fracture

• Chronic sinus tract formation

• Joint stiffness

• Limb shortening

• Recurrent infection

• Septicemia

• Limb amputation

• Death

Prevention

• Appropriate perioperative antibiotic prophylaxis

• Strict aseptic surgical technique

• Meticulous soft tissue handling

• Careful haemostasis to reduce haematoma formation

• Optimisation of diabetes and nutritional status before surgery

• Smoking cessation before elective surgery

• Early treatment of postoperative wound complications

• Proper management of open fractures

• Surveillance for early postoperative infection

Patient education

Patients should be advised to:

• Complete the prescribed antibiotic regimen.

• Keep surgical wounds clean and dry.

• Report increasing pain, swelling, redness, wound discharge, or fever immediately.

• Attend all scheduled follow-up appointments.

• Participate fully in physiotherapy and rehabilitation.

• Maintain good glycaemic control if diabetic.

• Avoid smoking to improve wound and bone healing.

• Use walking aids as instructed until adequate healing has occurred.

Prognosis

The prognosis depends on the timing of diagnosis, causative organism, host factors, adequacy of surgical debridement, and duration of infection. Early infections treated promptly with appropriate surgery and antimicrobial therapy generally have favourable outcomes with implant retention in selected cases. Delayed or chronic infections are more likely to require implant removal, staged reconstruction, prolonged antibiotic therapy, and multiple surgical procedures. Patients with diabetes mellitus, immunosuppression, resistant organisms, or extensive bone loss have a higher risk of recurrence, implant failure, and long-term functional impairment.