Radiographic examination shows air in the knee joint. An open joint injury should be suspected whenever there is a laceration, puncture wound, or other wound that occurs in close proximity to a joint. Missed diagnosis of an open joint injury can lead to a septic joint and, ultimately, major morbidity.

The first step in detecting an open joint injury is to perform radiographic imaging to evaluate for possible fracture, presence of a foreign body, or intra-articular air. If the imaging shows air in the joint, no further testing is needed.  If the imaging does not show air, the typical next step is injection of saline with methylene blue to distend the joint capsule in order to identify a leak in the wound. However, the injection and procedure are quite painful and may cause a septic joint. Computed tomographic (CT) scan of the joint may be more sensitive than joint injection. Risk associated with imaging is minimal; therefore, it can be argued that CT should be the current standard of care and joint injection should be abandoned.

If there is evidence of an open joint injury on imaging, treatment should include orthopedic consultation, joint irrigation, and intravenous antibiotics. Injuries to large joints are usually irrigated in the operating room, but those involving smaller joints such as fingers can often be managed without invasive surgery.

Table. Open Joint Injury

DescriptionAny deep laceration near a joint
Diagnosis• Air in joint on radiographic or computed tomographic (CT) imaging
• Saline load test with methylene blue (less sensitive than CT)
Treatment (large joints)• Irrigation and debridement in the operating room
• Intravenous cefazolin 1 g every 8 hours for 2-3 days
Treatment (small joints)• Irrigation and intravenous cefazolin 1 g in the emergency department
• Discharge with oral cefazolin prescription and daily wound checks

Brady Pregerson, MD, is an emergency physician at Cedars-Sinai Medical Center in Los Angeles and at Tri-City Medical Center in Oceanside, California.


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Reference

Pregerson DB. Orthopedics: basics and open injuries. In: Emergency Medicine 1-Minute Consult Pocketbook. http://www.erpocketbooks.com/emergency_medicine_reference_books/quick-essentials-emergency-medicine/. 2017;5.