Figure 1: AP and lateral radiographs of the left knee. Case courtesy Dr. Jeremy Jones, Radiopaedia.org, rID: 27372
Anterior tibial spine avulsion fracture with anterior cruciate ligament (ACL) injury.
- Pearl: The anterior tibial spine is the insertion point of the ACL. This injury occurs more commonly in pediatric patients than adults [1], likely because the pediatric ACL is more elastic as well as stronger than its incompletely ossified bony attachment [2,3].
- Pearl: Tibial spine avulsion fractures can be caused by a twisting or pivoting knee injury, hyperextension, or direct trauma, with or without concomitant ACL injury [4].
Figure 2: Annotated lateral radiograph of the left knee. Note the avulsed tibial spine (green arrow). Case courtesy Dr. Jeremy Jones, Radiopaedia.org, rID: 27372. Arrow by author.
The patient should be placed in a long leg knee immobilizer locked in full extension and referred to see orthopedics within one week.
- Pearl: In contrast to a typical ACL rupture, which can be treated with or without surgery and can wait a few weeks for follow-up, these injuries should have more urgent surgical evaluation and generally need operative repair [5-7].
Yes. A knee immobilizer prevents anterior translation of the tibia relative to the femur, a motion which pulls traction on the ACL and its avulsed bony fragment. This prevents additional displacement of the fragment and maximizes the chances for successful arthroscopic repair.
In general, immobilize extensor mechanism injuries, hip and knee dislocations, and unstable knee fracture patterns with either a splint or knee immobilizer brace placed in extension. Specific injuries include [8]:
- Patellar fracture
- Patellar dislocation (especially first-time)
- Quadriceps tendon rupture
- Patellar tendon rupture
- Knee dislocation
- Hip dislocation
- Displaced tibial plateau fracture
- Tibial spine avulsion fracture
Check out ALiEM’s Paucis Verbis cards to brush up on other can’t miss orthopedic injuries, and SplintER Series or EMrad for more knee injury cases.
References
- Wiley JJ, Baxter MP. Tibial spine fractures in children. Clin Orthop Relat Res. 1990 Jun;(255):54-60. PMID: 2347165.
- Noyes FR, DeLucas JL, Torvik PJ. Biomechanics of anterior cruciate ligament failure: an analysis of strain-rate sensitivity and mechanisms of failure in primates. J Bone Joint Surg Am. 1974 Mar;56(2):236-53. PMID: 4452684.
- Mayo MH, Mitchell JJ, Axibal DP, Chahla J, Palmer C, Vidal AF, Rhodes JT. Anterior Cruciate Ligament Injury at the Time of Anterior Tibial Spine Fracture in Young Patients: An Observational Cohort Study. J Pediatr Orthop. 2019 Oct;39(9):e668-e673. doi: 10.1097/BPO.0000000000001011. PMID: 31503222.
- Tuca M, Bernal N, Luderowski E, Green DW. Tibial spine avulsion fractures: treatment update. Curr Opin Pediatr. 2019 Feb;31(1):103-111. doi: 10.1097/MOP.0000000000000719. PMID: 30531228.
- Osti L, Buda M, Soldati F, Del Buono A, Osti R, Maffulli N. Arthroscopic treatment of tibial eminence fracture: a systematic review of different fixation methods. Br Med Bull. 2016 Jun;118(1):73-90. doi: 10.1093/bmb/ldw018. Epub 2016 May 5. PMID: 27151952; PMCID: PMC5127426.
- Monk AP, Davies LJ, Hopewell S, Harris K, Beard DJ, Price AJ. Surgical versus conservative interventions for treating anterior cruciate ligament injuries. Cochrane Database Syst Rev. 2016 Apr 3;4(4):CD011166. doi: 10.1002/14651858.CD011166.pub2. PMID: 27039329; PMCID: PMC6464826.
- Dolbec KWD. Winter Wipeout: Skiing and Snowboarding Injuries. Critical Decisions in Emergency Medicine. January 2019; 33(1): p. 20. https://www.acep.org/static/globalassets/resources/documents/cdem-documents/Ski-Snowboard-Injuries-CDEM-Article.pdf
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