What is the appropriate management of a laceration involving the knee joint region?

Management of Knee Joint Region Laceration

All lacerations near the knee joint require immediate assessment for joint capsule penetration, as traumatic arthrotomy is a surgical emergency that demands urgent irrigation and debridement to prevent devastating septic arthritis.

Initial Assessment and Diagnosis

Determine if Joint Capsule is Violated

• Obtain CT scan of the knee to assess for intra-articular air, which has 100% sensitivity and specificity for detecting traumatic arthrotomy 1
• Perform saline load test if CT is unavailable: inject 73.8-194 mL of sterile saline into the knee joint through a separate site; extravasation through the wound confirms joint penetration with 91-99% sensitivity 2, 1
• Adding methylene blue to saline does not improve diagnostic accuracy 2
• Physical examination alone is unreliable—do not rely on wound appearance or depth estimation 1

Assess for Associated Injuries

• Obtain plain radiographs (AP and lateral views) to identify periarticular fractures, which occur in 51% of open knee injuries 1, 3
• Evaluate vascular status immediately: check pulses, capillary refill, and extremity temperature to rule out popliteal artery injury 4, 5
• Test peroneal and tibial nerve function 4

Management Based on Joint Penetration

If Joint Capsule is NOT Penetrated (Superficial Laceration)

• Apply topical anesthetic (LET solution: lidocaine-epinephrine-tetracaine) for 10-20 minutes under occlusive dressing until wound edges blanch 3, 6
• Irrigate wound thoroughly with sterile saline 7
• Close with tissue adhesive (octyl cyanoacrylate) for low-tension wounds or absorbable sutures for facial/cosmetic areas to avoid painful suture removal 3, 7
• Use buffered, warmed lidocaine (with bicarbonate) injected slowly through small-gauge needle if additional anesthesia needed 3
• No antibiotics required for clean, superficial lacerations 7

If Joint Capsule IS Penetrated (Traumatic Arthrotomy)

This is a surgical emergency requiring urgent operative management 1

Immediate Actions

• Keep patient NPO and consult orthopedic surgery immediately 1
• Administer IV antibiotics within 1 hour: first-generation cephalosporin (cefazolin) or vancomycin if MRSA risk 1
• Obtain CT scan if not already done to assess full extent of injury 1
• Have vascular surgery available if any concern for popliteal artery injury 5

Surgical Management

• Perform urgent arthroscopic or open irrigation and debridement within 6-8 hours of injury 1
• Use arthroscopic I&D for small puncture wounds (e.g., gunshot wounds) 1
• Use open medial parapatellar approach for larger lacerations or when arthroscopic visualization is inadequate 1
• Obtain minimum of 3-5 intraoperative tissue cultures before administering antibiotics if not already given 3
• Perform thorough debridement of devitalized tissue and copious irrigation 1

Postoperative Antibiotic Regimen

• Continue IV antibiotics for 24-48 hours postoperatively 1
• Add oral antibiotics for 3-5 days only if wound was grossly contaminated 1
• Do not extend antibiotic course beyond this unless infection develops 1

Critical Pitfalls to Avoid

• Never close a wound over the knee without definitively ruling out joint penetration—missed arthrotomy leads to septic arthritis with devastating consequences including joint destruction and potential amputation 1
• Do not rely on wound probing with instruments, as this has poor sensitivity and may introduce infection 1
• Do not delay surgical consultation while waiting for imaging if clinical suspicion is high 1
• Avoid superficial wound swabs, which are misleading and promote unnecessarily broad antimicrobial treatment 3
• Do not use EMLA cream on open wounds—it is contraindicated for non-intact skin 6

Special Considerations

• Aspirate large hemarthrosis to minimize cartilage damage from heme breakdown products, even in non-operative cases 8
• Consider MRI after initial management to assess for occult ligamentous injuries (ACL, PCL, meniscal tears) that may require delayed reconstruction 3
• Patients with diabetes, immunosuppression, or inflammatory arthritis have higher infection risk and warrant closer monitoring 3