Issue link: http://connmed.csms.org/i/470788
volume 79, no. 3 139 Tibial Spine Avulsion Fractures: A Focus on Arthroscopic Treatment and Rehabilitation Matthew D. Milewski, MD anD Jason l. Booker, Pt, CsCs Introduction and Epidemiology t ibial spine avulsion fractures describe an injury to the proximal tibia in which the anterior cruciate ligament (aCl) attachment area is pulled off or avulsed from trauma. is can be a result of either noncontact or contact sports. e tibial spine is also referred to as the tibial eminence. while this is a fairly uncommon injury, it can have devastating effects on an adolescent athletes ability to return to sports in a timely fashion if diagnosis or treatment is delayed. Poncet first described these injuries in 1875. 1 it has been estimated that they account for 2 to 5% of knee injuries in a pediatric and adolescent population with an incidence of three per 100,000 children per year. 2-4 Classic teaching stated that aCl tears and tibial spine avulsion fractures occurred in equal proportions in skeletally immature athletes. recent reports have sug- gested that the incidence of aCl injuries has increased dramatically over the last 10 years compared to the inci- dence of these fractures. 5 e etiology of this change is unclear. tibial spine avulsions are usually seen in younger patients generally between the ages of eight and 14. 6-8 ey have been well described in adults and it has also been estimated that 14% of injuries to the aCl complex involve an avulsion of the tibial spine. 9 a high index of suspicion for other knee ligament and cartilage injuries is crucial when treating patients with these fractures. in particular the rate of meniscal injury associated with these injuries has been estimated between 3.8 to 40%. 10-13 a higher incidence of associated injuries has been noted in adults compared with children and adolescents with these injuries indicative of the higher amount of force needed to generate these injuries in adults. 9 Anatomy and Biomechanics e aCl insertion on the tibia has been well docu- mented in the literature mainly in regards to directing anatomic reconstruction. in general, the aCl insertion on the tibia involves the anterior recess between the medial and lateral intercondylar spines. e insertion area of the anteromedial bundle of the aCl is generally involved, as it is the anterior portion of the tibial spine that often displaces superiorly. 14 in skeletally immature patients, the avulsion occurs as a result of the failure of the not yet fully ossified tibial spine prior to aCl rupture. noyes et al 15 showed in a primate model that a lower rate of loading leads to an avulsion fracture pat- tern, compared to a higher rate of loading which leads to ligament failure. kocher et al 16 found that anatomi- cal differences might account for differences in injury pattern by showing that a narrower notch width index was found in patients with an aCl ligament injury compared to a tibial spine fracture. it is likely that there is a continuum of injury to both the tibial spine and to the aCl ligament itself. a stretch injury to the aCl in addition to bony fracture has been shown in a rabbit model. 17 Clinically increased aCl laxity after tibial spine fracture healing has been shown but clini- cally noted instability is rare. willis et al showed 64% of patients had clinical laxity and 74% of patients had increased kt 1000 translation at four years after tibial spine fracture but only 10% had pain and no functional instability was noted. e classic mode of injury in a young patient was thought to occur from falling off a bicycle. 4,18 however these injuries have been described in contact sports, noncontact sports (particularly skiing), along with traumatic causes such as a motor vehicle accident or a pedestrian being struck. 10,12,19-21 it has also been thought to occur from a fall with forced knee flexion with tibial internal rotation. 22 loss of tibial spine fixation can lead to loss of appropriate tension on the aCl and lead to Matthew Milewski, MD, Connecticut Children's Medical Center and assistant Professor of orthopaedic surgery, University of Connecticut school of Medicine, Farmington; Jason l. Booker, Pt, CsCs, Connecticut Children's Medical Center, Farmington; Corresponding author: Matthew Milewski, MD, firstname.lastname@example.org.