High Risk/Low Prevalence: Traumatic Arthrotomy with Brit Long

Traumatic arthrotomy is an easily missed open-joint injury where delayed recognition can end in septic arthritis, washout, and permanent loss of function. Knee wounds are the classic presentation, but normal x-rays do not exclude the diagnosis and imaging performance varies sharply by joint.

Recognizing Traumatic Arthrotomy

• Open joint definition: Traumatic arthrotomy is capsule violation with contamination of the intra-articular space, a small wound with outsized consequences once bacteria reach the joint.
• High-stakes complications: Missed cases can progress to septic arthritis, with roughly 15% mortality and irreversible functional loss in many survivors when debridement and washout are delayed.
• Typical risk patterns: The knee accounts for most cases, often after gunshot wounds or other penetrating trauma in younger adults, but any periarticular laceration deserves suspicion.
• Suggestive wound findings: Synovial fluid, visible capsule disruption, or bubbles and fat droplets from the wound all raise concern, while bedside gestalt alone performs poorly for ruling it out.
• Ortho-first mindset: High-risk periarticular wounds warrant early orthopedic discussion even before the diagnosis is nailed down, and we get into the practical threshold for that call in the episode.

Imaging And Saline Load Testing

• Plain film limitation: Free intra-articular air on x-ray is highly suggestive, but plain radiographs miss many cases; a normal film should not reassure you away from traumatic arthrotomy.
• CT joint dependence: CT looks strongest for the knee, where tiny volumes of intra-articular air can be detected and management changes are common, but performance falls off in smaller joints.
• Ultrasound caution: Ultrasound has been studied but remains too unreliable for routine diagnosis, with cadaver data showing only modest sensitivity and specificity.
• Saline load role: The saline load test remains the reference bedside test because it checks capsule integrity directly by looking for saline extravasation from the wound.
• Volume matters most: Saline load sensitivity depends heavily on injecting enough volume, and the needed amount varies by joint. We lay out the joint-specific numbers in the chapter.
• Common test failures: False negatives often come from missing the joint space, underfilling the capsule, or stopping early when the patient cannot tolerate the procedure; dynamic range of motion can help.

Emergency Department Management

• Early antibiotics for all: Any suspected traumatic arthrotomy should receive antibiotics promptly, with a first-generation cephalosporin as the default starting point for smaller uncomplicated wounds.
• Coverage for contamination: Extensive soft-tissue injury, MRSA risk, or seawater exposure should broaden therapy, including Vibrio coverage when marine contamination is in play.
• Initial ED priorities: Analgesia, fracture reduction, irrigation of gross contamination, splinting, and tetanus prophylaxis are core early steps while definitive operative planning is underway.
• Procedural tolerance planning: If the saline load test is needed and the patient cannot tolerate it, procedural sedation may be the difference between a diagnostic exam and an aborted one.

References:

1. Colmer HG 4th, et al. High risk and low prevalence diseases: Traumatic arthrotomy. Am J Emerg Med. 2022 Jan 21;54:41-45. PMID: 35121477.
2. Voit GA, et al. Saline load test for penetration of periarticular lacerations. J Bone Joint Surg Br. 1996 Sep;78(5):732-3. PMID: 8836059.
3. B. Sleasman, et al. Utility of conventional radiographs in the detection of traumatic knee arthrotomies: a retrospective cohort review. Curr Orthop Pract, 31 (5) (2020 Sept), pp. 479-482. Link. 
4. Konda SR, et al. The role of computed tomography in the assessment of open periarticular fractures associated with deep knee wounds. J Orthop Trauma. 2013 Sep;27(9):509-14. PMID: 23412508.
5. Kongkatong M, et al. Can Ultrasound Identify Traumatic Knee Arthrotomy in a Cadaveric Model? J Emerg Med. 2019 Sep;57(3):362-366. PMID: 31375371.
6. Kupchick TD, et al. Detection of traumatic elbow arthrotomies: computed tomography scan vs. saline load test. J Shoulder Elbow Surg. 2020 Sep;29(9):1869-1875. PMID: 32444316.
7. Keese GR, et al. The accuracy of the saline load test in the diagnosis of traumatic knee arthrotomies. J Orthop Trauma. 2007 Aug;21(7):442-3. PMID: 17762473.
8. Tornetta P 3rd, et al. How effective is a saline arthrogram for wounds around the knee? Clin Orthop Relat Res. 2008 Feb;466(2):432-5. PMID: 18196428.
9. Feathers T, et al. Effectiveness of the saline load test in diagnosis of traumatic elbow arthrotomies. J Trauma. 2011 Nov;71(5):E110-3. PMID: 21768902.
10. Gittings DJ, et alL. The Saline Load Test is Effective at Diagnosing Traumatic Arthrotomies of the Wrist. Tech Hand Up Extrem Surg. 2019 Jun;23(2):59-61.PMID: 30676429.
11. Bohl DD, et al. Sensitivity of the Saline Load Test for Traumatic Arthrotomy of the Ankle With Ankle Arthroscopy Simulation. Foot Ankle Int. 2018 Jun;39(6):736-740. PMID: 29457483.
12. Bohl DD, et al. Sensitivity of the Saline Load Test for Traumatic Arthrotomy of the Ankle With Ankle Arthroscopy Simulation. Foot Ankle Int. 2018 Jun;39(6):736-740. PMID: 29457483.