Radiology Corner

Radiology Corner

Interesting finding in an elderly female patient without reported knee trauma

Tracey A. Littrell, DC, DACBR, DACO, CCSP

Published: June 2017

Journal of the Academy of Chiropractic Orthopedists

June 2017, Volume 14, Issue 2

This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The article copyright belongs to the author and the Academy of Chiropractic Orthopedists and is available at: © 2017 Litrell and the Academy of Chiropractic Orthopedists.


Figure 1: AP knee



Figure 2: Lateral knee


This 94-year-old female patient with a history of Non-Hodgkin Lymphoma in remission described long-standing low back pain and right knee pain to her chiropractor. The AP and lateral lumbopelvic radiographs revealed the expected findings of osteoporosis, advanced degenerative disk disease of the lumbar spine, posterior facet arthrosis with grade I degenerative spondylolistheses, and calcified atherosclerotic plaques within the abdominal aorta and iliac arteries. The AP and lateral knee radiographs demonstrated osteoporosis, osteoarthrosis, and an unexpected finding of a crescent-shaped osseous fragment in the intercondylar notch, representative of an avulsion of the tibial insertion of the anterior cruciate ligament. Diastasis of the fracture fragment was present.


The collagenous ACL is the primary static stabilizer of the knee, limiting extension, anterior translation, and rotation of the tibia and curbing varus and valgus movement during flexion. It crosses the knee obliquely, from the anterior tibial eminence posterolaterally to the medial aspect of the lateral femoral condyle.1

Anterior cruciate ligament injury is a pervasive injury in nearly all categories of patients, from young to old, athletic to sedentary. It is one of the most common knee ligament injuries evaluated by health care providers, with approximately 250,000 ACL tears diagnosed and 100,000 ACL surgical reconstructions performed every year in the United States.1

ACL injuries are expensive to treat with surgical reconstruction and rehabilitation and often result in lasting impediments, including cartilaginous injuries, meniscal tears, biomechanical instability, and early osteoarthrosis.1

Tibial spine avulsion fractures were first detailed in 1875 by Poncet, described erroneously as pediatric-exclusive injuries.2,3,4 While these avulsions are more commonly seen in young skeletally immature children and adolescents, their occurrence in adults is possible.3,4,5 In children, the elasticity of the ACL, the weaker bony structures, and the open epiphyses are more likely to lead to osseous avulsion of the ACL at the distal tibial attachment site than tear of the ACL. In adults, ligament disruption is more common than osseous avulsion, occurring most frequently at the tibial eminence rather than the femoral attachment.6 Bicycle falls account for more than half of tibial avulsion fractures. Rotational and/or extension injury in both contact and noncontact sports, such as soccer and skiing, make up the majority of the remaining occurrences.7

In 1959, Meyers and McKeever described three tibial spine fracture patterns: Type I as a nondisplaced fracture; Type II as a mildly displaced and elevated fracture of the anterior third but with an intact posterior hinge; and Type III as a completely raised fracture. Tibial spine fracture patterns with comminuted and rotated fragments were later termed Type IV fractures.2,5,7

Patients with tibial spine fractures typically present with knee pain and effusion, clinically mimicking ACL tears. Commonly, the knee will be held in flexion with limited range of motion possible, particularly extension. The osseous fragment may lead to joint locking. Orthopedic examination to evaluate knee stability may be difficult to perform due to pain and muscle spasm; Lachman’s test, anterior drawer test, and the pivot shift test would likely be positive.7

Well-positioned knee radiographs are essential for accurate diagnosis. Typically, the lateral view will readily demonstrate the fracture. In this case, the findings on the lateral projection are subtle and the diagnosis is clear on the suboptimally positioned AP view. A PA axial open-joint view (Camp-Coventry or Homblad methods) of the knee would have been an appropriate addition to this radiographic examination, resulting in better demonstration of the intercondylar fossa. Examination with computed tomography (CT) aids in establishing comminution of fractures, the degree of displacement, and in pre-operative planning. Due to the high likelihood of intra-articular injury, examination with magnetic resonance imaging (MRI) is an indispensable tool in the evaluation of concomitant meniscal and collateral ligament involvement.

Non-displaced fractures may be responsive to nonsurgical management, usually consisting of hemarthrosis evacuation and immobilization bracing. Arthroscopic surgical management is typically employed for displaced fractures.2,7

In this case of an adult with a tibial spine avulsion, the presence of osteoporosis most likely made her susceptible to osseous avulsion over ACL rupture. Despite her knee pain and the diagnosis of a displaced Type III tibial spine avulsion fracture, the patient declined further imaging and medical orthopedic management.


  1. Acevedo RJ, Rivera-Vega A, Miranda G, Micheo W. Anterior cruciate ligament injury: identification of risk factors and prevention strategies. Curr Sports Med Rep. 2014 May-Jun; 13(3):186-91.
  2. 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.
  3. Myer, D. M., Purnell, G. J., Caldwell, P. E., & Pearson, S. E. (2013). ORV Arthroscopic Reduction and Internal Fixation of Tibial Eminence Fractures. Arthroscopy Techniques2(4), e341–e345.
  4. Kumar M, Malgonde M, Jain P. Avulsion fracture of tibial spine: A case report and review of literature. Saudi J Sports Med 2013;13:102-4.
  5. Kose O, Ozyurek S, Guler F, Canbora K. Avulsion fracture of the anterior cruciate ligament in a 9-year-old child. BMJ Case Rep. 2013 Aug 8;2013. pii: bcr2013009426.
  6. Shah SH, Porrino JA, Twaddle BC, Richardson ML. Osseous femoral avulsion of the anterior cruciate ligament origin in an adult. Radiology Case Reports. (Online) 2015;10(2);1070. DOI: 10.2484/rcr.v10i2.1070
  7. Little RM, Milewski MD. Physeal fractures about the knee. Curr Rev Musculoskelet Med (2016) 9:478–486 DOI 10.1007/s12178-016-9370-7

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