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Tibial Eminence Fracture in an Adult

A Possibility With Rotational Injuries

Jeffrey R. Bytomski, DO; Richard T. Ferro, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 32 - NO. 1 - JANUARY 2004


In Brief: Twisting the knee may cause tibial eminence fractures in skeletally immature children; however, the injury is far less common in adults. A lateral radiograph usually shows the fracture, but further imaging studies are needed to determine the extent of displacement and concomitant soft-tissue damage. Minimally displaced fractures can be managed conservatively with immobilization and physical therapy, but severe displacements will require surgical fixation to preserve the anterior cruciate ligament. Physicians should include tibial eminence fracture in the differential diagnosis of adults who sustain a twisting injury, particularly if the patient may have osteoporosis or bone weakness.

Tibial eminence fractures occur when extreme tension on the anterior cruciate ligament (ACL) causes a bony avulsion instead of an acute ACL tear. Most injuries occur in skeletally immature patients who sustain either a hyperflexion or extension injury with rotation. With a similar mechanism, adults more commonly tear the ACL, but they may also experience tibial eminence fractures when subjected to significant trauma.

Knee instability and mechanical obstruction are also possible. Inappropriate treatment of tibial eminence fractures (ie, inadequate immobilization and too-aggressive rehabilitation during the immobilization period) may result in functional incompetence of the ACL with reduced range of motion that may require reconstructive surgery.1 Tibial eminence fractures should be included in the differential diagnosis of acute knee injuries in adults if appropriate history and physical exam findings are present.

Case Report

A 22-year-old woman was riding a bicycle on the street when she lost her balance near a curb and fell. She landed directly on her flexed right knee and sustained abrasions to her face and right elbow. She was unable to bear weight on the knee, and it swelled rapidly after the incident, but she did not notice any "pop" when she fell.

History. The patient had no history of hip, knee, or ankle problems. Her family history was positive for osteoporosis. Review of systems was significant for migraines and irregular menses. The rest of her history was unremarkable.

Physical exam. A superficial abrasion on the anterolateral aspect of the right knee and a large effusion were seen. Her knee was diffusely tender, and she held it in 20° to 30° of flexion for greatest comfort. Knee range-of-motion (ROM) tests demonstrated a 5° flexion contracture and 80° of flexion. The patellar apprehension test was negative, and no varus or valgus instability was noted. McMurray's, Lachman's, and drawer tests were difficult to assess because of guarding. The posterolateral corner was stable with dial testing. Her neurovascular exams appeared unremarkable.

Imaging studies. Radiographs (figure 1) revealed a minimally displaced medial tibial plateau fracture extending through the tibial eminence. Magnetic resonance imaging (MRI) was obtained to further evaluate the amount of displacement and any concomitant injuries.

Diagnosis. Based on the MRIs (figure 2), the diagnosis was a minimally displaced type 1 tibial eminence fracture, a nondepressed lateral tibial plateau fracture, and a grade 1 tear of the medial collateral ligament of the right knee.

Treatment. The patient was placed in a knee immobilizer in full extension for approximately 3 weeks. Physical therapy with ROM exercises began at week 3, and she was instructed not to flex the knee more than 90° for the first 3 to 4 weeks. She refrained from weight bearing for 5 to 6 weeks while physical therapy progressed.

At 6 weeks, she had almost full ROM and markedly decreased pain and swelling. She could perform touch-down weight bearing and aquatic physical therapy without pain.

Follow-up. The patient progressed through physical therapy, regained full ROM by 12 weeks, and began a gradual return to full activity without restriction at this time. She occasionally had pain with long-distance running but was otherwise asymptomatic. No symptoms of catching, locking, or instability of the right knee were reported. Her secondary amenorrhea was also addressed with an appropriate work-up, including a bone density study (results were normal) and lab tests, and she eventually began a regimen of oral contraceptive therapy.

Tibial Eminence Fractures and Skeletal Maturity

Knee injuries in children and adults differ. Children tend to injure skeletally immature bones and physes.2 Skeletally mature adults are more likely to injure ligaments during twisting trauma. Most tibial eminence fractures occur with a mechanism of hyperflexion or extension coupled with a twisting force, such as a fall from a bicycle.3,4 Tibial eminence fractures have been well described in the pediatric orthopedic literature, but the incidence is limited in adults. Associated injuries often occur, especially to either the medial collateral ligament or medial meniscus. The meniscus may become trapped at the fracture site, thus preventing reduction.3

Exam notes. Patients often report diffuse pain, swelling, and decreased knee ROM. Limited motion can be attributed to hemarthrosis, a displaced fracture fragment or meniscus, muscle guarding, or a combination of these. Tenderness to palpation should be specific to the joint line, medial and lateral femoral condyles, and the tibial plateau. Patellar tenderness and apprehension should also be noted.

Valgus and varus stress testing should be performed for collateral ligament integrity. ACL and posterior cruciate ligament testing and posterolateral corner testing may provide clues. If guarding makes testing difficult, increasing patient comfort with an intra-articular injection of 1% lidocaine hydrochloride may improve diagnostic acumen. Assessing neurovascular status is also an important part of the exam.

Imaging. The history and physical exam may suggest an ACL tear rather than a tibial eminence fracture. Radiographs, MRI, or computed tomography (CT) are needed to confirm the diagnosis, further classify a fracture, and evaluate any related injuries. Initial radiographs should include anteroposterior, lateral, Merchant's, and tunnel views. Sometimes a tibial eminence fracture can be seen only on the lateral view.5

As more advanced imaging and arthroscopic techniques become available, concomitant injuries associated with tibial avulsion fractures have been diagnosed with increased frequency. MRI is becoming more widely used to evaluate associated injuries in adults.6 MRI can reveal the amount of displacement, whether open or closed surgical fixation is needed, or if concomitant injuries, such as a trapped medial meniscus, are present. Displacement can be evaluated and classification determined with more certainty by using CT or MRI rather than plain radiographs alone. CT may also help to better evaluate reduction after the leg is immobilized.

Treatment. Minimally displaced fractures may be managed conservatively (usually with immobilization followed by physical therapy), but grossly displaced fractures need surgical repair to preserve ACL function. Treatment of tibial eminence fractures varies depending on the type of fracture and associated injuries. The possibility of persistent ACL laxity and pain exists with all tibial eminence fractures; therefore, patients should be considered for orthopedic consultation whenever possible.

Most studies for treatment and long-term outcomes involve children. Willis et al1 studied 50 children with tibial eminence fractures who reported no instability at 4 years (average) of follow-up, but there were clinical signs of anterior instability in 64% and objective laxity (measured with KT1000 Knee Ligament Arthrometer, MEDmetric Corp, San Diego) in 74% of patients. Only 10% of patients reported pain. No correlation between outcome and method of treatment was found. The study warns that the long-term prognosis remains guarded about persistent ACL laxity. Wiley and Baxter7 studied 45 children with 3- to 10-year follow-up and found that none complained of subjective instability, yet the average anterior translation was 3 to 4 mm. These findings could suggest proprioceptive fibers healing within the ACL, even though clinically measurable laxity persists in children.

Ahmad et al8 compared tibial eminence fractures in skeletally mature patients to ACL-reconstructed knees and ACL-deficient knees. They concluded that appropriate treatment of tibial eminence fractures restored stability and proprioception to the knee.

Displacement

According to the classification system developed by Meyers and McKeever9,10 and modified by Iobst and Stanitski3:

  • Type 1 fractures are minimally displaced (< 3 mm);
  • Type 2 fractures have the anterior third to half of the eminence elevated and an intact posterior hinge;
  • Type 3 fractures involve complete displacement of the fragment;
  • Type 3+ fractures involve complete displacement with rotation; and
  • Type 4 fractures have complete displacement with rotation and comminution.2

Type 1 fractures may be treated conservatively. Aspiration of the hemarthrosis and injection of local anesthetic may help initially with pain and reduction to full extension. Immobilization for 3 to 4 weeks with progressive weight bearing on crutches and appropriate physical therapy is recommended.

Type 2 fractures may also be treated conservatively if appropriate reduction is maintained. If adequate reduction (< 3 mm of displacement) is not achieved with full extension, MRI evaluation should be done to check for possible meniscal entrapment. Once reduction is maintained, immobilization for 4 to 6 weeks with progressive weight bearing and weekly radiographic follow-up for the first 2 weeks is indicated. Physical therapy to regain motion begins after immobilization. If closed reduction is inadequate, surgical reduction is indicated.

Type 3 and type 4 fractures need surgical fixation to maintain anatomic reduction.9 Associated injuries are treated with arthroscopy. Complications following surgery include arthrofibrosis, extension loss, or fracture malunion or nonunion. Four to 6 weeks of postoperative immobilization is followed by a rehabilitation program similar to those used for ACL reconstructions.

Arthrofibrosis and loss of full extension are more of a concern in adults than in children. Some authors advocate a longer immobilization period for children because they may regain motion more easily than adults.

Radiographs should be repeated at regular intervals during immobilization to ensure that anatomic reduction is maintained. Most authors favor immobilization of patients in 0° of extension, but some debate whether 20° to 30° of flexion results in a better reduction. We know of no randomized clinical trials comparing the two methods.

Reestabishing Stability

Tibial eminence fractures are more commonly seen in children but should be included in the differential diagnosis of adults who have specific injury mechanisms. Most patients do well with anatomic reduction and treatment of associated injuries. Patients may have mild anterior laxity with follow-up examinations but still have functional stability.

References

  1. Willis RB, Blokker C, Stoll TM, et al: Long-term follow-up of anterior tibial eminence fractures. J Pediatr Orthop 1993;13(3):361-364
  2. Salter RB: Textbook of Disorders and Injuries of the Musculoskeletal System, ed 2. Baltimore, Williams & Wilkins, 1983, pp 427-432
  3. Iobst CA, Stanitski CL: Acute knee injuries. Clin Sports Med 2000;19(4):621-635
  4. Lastihenos M, Nicholas SJ: Managing ACL injuries in children: are kids' injuries different? Phys Sportsmed 1996;24(4):59-70
  5. Stanitski C, Sherman C: How I manage physeal fractures about the knee. Phys Sportsmed 1997;25(4):108-121
  6. Toye LR, Cummings DP, Armendariz G: Adult tibial intercondylar eminence fracture: evaluation with MR imaging. Skeletal Radiol 2002;31(1):46-48
  7. Wiley JJ, Baxter MP: Tibial spine fractures in children. Clin Orthop 1990;255(Jun):54-60
  8. Ahmad CS, Stein BE, Jeshuran W, et al: Anterior cruciate ligament function after tibial eminence fracture in skeletally mature patients. Am J Sports Med 2001;29(3):339-345
  9. Meyers MH, McKeever FM: Fracture of the intercondylar eminence of the tibia. J Bone Joint Surg Am 1959;41(2):209-222
  10. Meyers MH, McKeever FM: Fracture of the intercondylar eminence of the tibia. J Bone Joint Surg Am 1970;52(8):1677-1684


Dr Bytomski is the head medical team physician and director of the Primary Care Sports Medicine Fellowship at Duke University Medical Center in Durham, North Carolina, and Dr Ferro is a family practice sports medicine physician in Durham. Address correspondence to Jeffrey R. Bytomski, DO, Duke University Medical Center, Box 3672, Durham, NC 27710; address e-mail to [email protected].

Disclosure information: Drs Bytomski and Ferro disclose no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.


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