To Immobilize or Not to Immobilize: That is the Question
Author: Katie Dolbec, MD
Peer-reviewer: Gabby Ahlzadeh, MD
Final editor: Alex Tomesch, MD, CAQ-SM
A patient presents to the Emergency Department after sustaining a twisting knee injury while skiing. She felt a pop and was unable to bear weight afterwards secondary to pain and instability. Shortly after the injury, she noted increased swelling and pain. On examination, she has a moderate effusion and a positive Lachman test.
Image 1. Case courtesy of Mikael Häggström, M.D. - Author info - Reusing images, CC0, via Wikimedia Commons
What is your diagnosis?
Anterior cruciate ligament (ACL) rupture. The x-ray is negative for bony abnormality; the injury is a soft tissue injury, in this case an ACL sprain.
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Pearl: ACL rupture, a grade 3 sprain of the ligament [1], is a frequent injury in sports The classic mechanism is a twisting or hyperflexion motion during a fall. Patients often experience a “pop” followed by knee instability, and present with a rapid onset of effusion and increasing pain. Other concomitant knee structures, such as the meniscus and medial collateral ligament, may also be injured [3].
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Pearl: A Segond fracture, which is a bony avulsion from the lateral tibial condyle, may be seen on x-ray and is highly associated with ACL rupture.
What is your management in the ED?
ACL ruptures can be initially managed conservatively. Patients should be encouraged to bear weight as tolerated while protecting the knee. Orthopedic referral should be placed for prompt follow up (1-2 weeks). Patients should work aggressively on regaining full knee range of motion and should work to maintain hamstrings and quadriceps strength [5].
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Pearl: Atrophy, loss of strength, and stiffness can set in quickly after a knee injury [6, 7]. Patients should be encouraged to maintain strength and range of motion as much as possible immediately following an injury, as this leads to better outcomes.
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Pearl: The exercise bike is a great modality that encourages knee range of motion and quadriceps strengthening in addition to single leg raises. Patients should avoid cutting and pivoting sports and activities.
Does she need a knee immobilizer?
No, she does not. The patient may be placed in a hinged knee brace.
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Pearl: Use of a knee immobilizer will propagate weakness, atrophy, and stiffness, all of which will be harmful to the patient regardless of whether or not the patient pursues surgical reconstruction. There is also an increased chance of deep venous thrombosis with the use of a knee immobilizer [8].
What are the indications for knee immobilization from the ED?
Extensor mechanism injuries, hip and knee dislocations, and some particular fracture patterns warrant immobilization in extension.
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Patellar fracture
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Patellar dislocation (especially first-time)
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Quadriceps tendon rupture
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Patellar tendon rupture
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Knee dislocation
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Hip dislocation
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Displaced tibial plateau fracture
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Tibial spine avulsion fracture [9]
References:
[1] Anterior Cruciate Ligament (ACL) Injuries. American Academy of Orthopaedic Surgeons. https://orthoinfo.aaos.org/en/diseases--conditions/anterior-cruciate-ligament-acl-injuries/
[2] Kim S, Endres NK, Johnson RJ, Ettlinger CF, Shealy JE (2012) Snowboarding injuries. Trends over time and comparisons with alpine skiing injuries. Am J Sports Med 40(4):770–776
[3] Posch, M., Schranz, A., Lener, M. et al. In recreational alpine skiing, the ACL is predominantly injured in all knee injuries needing hospitalisation. Knee Surg Sports Traumatol Arthrosc (2020). https://doi.org/10.1007/s00167-020-06221-z
[4] Prins M. The Lachman test is the most sensitive and the pivot shift the most specific test for the diagnosis of ACL rupture. Australian Journal of Physiotherapy (2006). 52(1): 66.
[5] Biscarini A, Contemori S, Busti D, Botti FM, Pettorossi VE. Knee flexion with quadriceps cocontraction: A new therapeutic exercise for the early stage of ACL rehabilitation. J Biomech. 2016 Dec 8;49(16):3855-3860. doi: 10.1016/j.jbiomech.2016.10.026. Epub 2016 Oct 21. PMID: 28573973.
[6] Kilroe SP, Fulford J, Jackman SR, Van Loon LJC, Wall BT. Temporal Muscle-Specific Disuse Atrophy during One Week of Leg Immobilization. Medicine & Science in Sports & Exercise (2019). DOI: 10.1249/MSS.0000000000002200
[7] Lepley LK, Davi SM, Burland JP, Lepley AS. Muscle Atrophy After ACL Injury: Implications for Clinical Practice. Sports Health. 12(6): 579. DOI: 10.1177/1941738120944256.
[8] Seidenberg PH, Beutler AI. The Sports Medicine Resource Manual. Saunders Elsevier, 2008. P. 488.
[9] Dolbec KWD. Winter Wipeout: Skiing and Snowboarding Injuries. Critical Decisions in Emergency Medicine. January 2019; 33(1): p. 20.
