Fracture, Tibial Spine Avulsion

By admin On Sep 18, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Quynh Hoang

Chris Koutures

Basics

Description

Avulsion fractures occur when either the tendon-bone or ligament-bone interface is ruptured by forceful muscle contraction or undue ligament stress.
In children, the weaker, incompletely ossified bone will fail before the ligament or tendon is injured.
Thus an injury that typically would result in an anterior cruciate ligament (ACL) tear in an adult instead would cause a fracture through the anterior tibial spine via pull of the ACL.
Fracture through the posterior tibial spine (where the posterior cruciate ligament attaches) is rare and generally occurs in skeletally mature patients.
Mechanism of injury:
- Hyperextension ± valgus stress or rotation about the knee
- Fracture also can occur with a direct blow to the distal end of the femur with the knee flexed.
Synonym(s): Tibial eminence fracture; Intercondylar eminence fracture

Epidemiology

Avulsion fractures of the ACL attachment to the tibial spine are most prevalent in children 8–14 yrs of age but are seen in adults >35 yrs of age who have low bone density.
ACL avulsion from the femoral attachment is less common, as is posterior cruciate ligament avulsion from the posterior tibial eminence.
Tibial spine fractures classically have been associated with a fall from a bicycle or motorcycle on an outstretched leg (1)[B],(2)[C],(3)[C].
The injury is now also commonly seen in sporting activities (1)[B],(2)[C],(3)[C].

Risk Factors

Children <16 yrs of age
Adults >35 yrs of age who are osteopenic

Commonly Associated Conditions

In adolescents and adults, tibial spine avulsion fractures are commonly associated with a concomitant injury to the medial collateral ligament (1)[B],(2)[C].

Diagnosis

History

In children aged 8–11 yrs, often due to hyperflexion injury
Above this age, owing to either hyperextension injury or single-leg landing from a jump, both associated with a rotational or twisting stress to the knee
Audible “pop” at the time of injury
Immediate (within 1–2 hr) prominent swelling of the knee (acute hemarthrosis)
Frequently unable to bear weight after injury

Physical Exam

Signs and symptoms:
- Presence of a large, tense knee effusion (especially in a child <16 yrs of age) should raise concern for a potential ACL avulsion fracture.
- Examination findings of an ACL tear should raise suspicion.
Physical examination:
- Large, tense effusion noted with loss of full range of motion (ROM).
- ACL stress tests (Lachman, anterior drawer, and pivot shift) show more forward translation of the tibia compared with the noninjured side.
- A positive posterior drawer sign or if the tibia is displaced posteriorly relative to the femur when compared with the noninjured knee may suggest posterior cruciate ligament avulsion from the tibial spine.
- Evaluate other ligamentous and meniscal structures, particularly the medial collateral ligament, for concomitant pathology.

Diagnostic Tests & Interpretation

Imaging

Plain radiographs should include anteroposterior (AP), lateral, and tunnel views. The latter outlines the femoral notch and tibial eminence.
The lateral view is most helpful to assess fracture position and degree of displacement.
Grades of anterior tibial spine avulsion fractures are based on degree of displacement. The Meyers and McKeever classification scheme is the most widely accepted.
- Type I: Minimal displacement of the anterior eminence
- Type II: Elevation of the anterior third to half of the eminence with hinging on posterior eminence
- Type IIIA: Complete displacement and separation of fragment without rotational malalignment
- Type IIIB: Complete displacement and separation of fragment with rotational malalignment
Types II and III are of equal incidence and are more common than type I.
With negative plain radiographs, nondisplaced fracture or ligament injury still must be suspected in patients with acute hemarthrosis. MRI should be obtained in these instances to further evaluate extent of injury.

Differential Diagnosis

Midsubstance ACL tear
Congenital absence or deficiency of the ACL
Midsubstance tear of the posterior cruciate ligament
Tibial plateau fracture
Patellar dislocation or subluxation
Osteochondral fracture of the femoral condyle

P.263

Treatment

Acute treatment
Analgesia:
- NSAIDs and narcotic medications are used initially for pain control.
- Frequent application of ice for 20-min periods is recommended.
Aspiration of the joint may enhance comfort and allow further knee extension. Lack of full knee extension may imply a mechanical block (ie, fracture fragment or meniscal tear).
Immobilization:
- Initial care includes complete knee immobilization with minimal knee flexion for 2–3 days until effusion begins to resolve.
- Crutch ambulation is recommended in this initial stage.

Additional Treatment

Type I fracture: After effusion resolves, type I fractures are best managed by long-leg-cast immobilization with knee flexed at ∼10–20 degrees for 4–6 wks (1)[B].
Type II and III fractures:
- Controversy still exists regarding optimal treatment for fractures with greater degrees of displacement.
- Type II tibial spine fractures can be managed by either closed reduction with the knee immobilized in full extension or surgically with arthroscopy or open reduction and internal fixation (1)[B].
- Numerous studies have shown no significant differences in outcome measures of residual ACL laxity between closed vs open reduction methods so long as fracture reduction is maintained (1)[B].
Type III fractures generally require open or arthroscopic reduction with fragment fixation (1)[B].
Special considerations:
- If requiring open reduction, better results are obtained if surgery is done within the 1st wk after injury. Prompt surgical referral is essential.
- The knee should be immobilized while awaiting surgical consultation.

Referral

All suspected ACL avulsion fractures should be referred to an orthopedic surgeon.
Patients with open growth plates would benefit from consultation with a pediatric orthopedist.

Additional Therapies

After completion of cast immobilization, focus should be on recovering full knee ROM followed by strengthening of knee extensors.
Proprioception is another key part of the rehabilitation process.

Surgery/Other Procedures

Arthroscopic or open reduction with internal fixation should be performed for displaced type II fractures if closed methods fail to obtain or maintain reduction of fracture fragment. Type III fractures generally require arthroscopic or open reduction with internal fixation.
Many authors prefer arthroscopic reduction owing to less surgical trauma and easier postoperative rehabilitation course.

Ongoing Care

Follow-Up Recommendations

In the immediate postinjury or postoperative period, follow-up radiographs are necessary to evaluate for loss of fracture reduction.

Prognosis

Tibial spine fractures generally have an excellent prognosis, even when the fracture fragment is completely displaced.
Despite true anatomic reduction, about 50% of pediatric patients may have mild objective, measurable ACL laxity owing to interstitial ligament damage that occurs before the avulsion. However, it does not result in functional instability.
Fewer data on treatment outcome are available for skeletally mature patients, with one study by Aderinto and colleagues reporting symptomatic knee instability as the main complication of nonoperative treatment of tibial spine fractures (2)[C].

Complications

Although overall prognosis is remarkably good, some complications may include

Loss of full knee extension owing to arthrofibrosis from immobilization or from mechanical block secondary to loss of reduction or malunion of fracture fragment (1)[B]
Knee stiffness, particularly in skeletally mature patients who underwent tibial spine fixation (2)[C]

References

1. Accousti WK, Willis RB. Tibial eminence fractures. Ortho Clin N Am. 2003;34:365–375.

2. Aderinto J, Walmsley P, Keating JF. Fractures of the tibial spine: epidemiology and outcome. The Knee. 2008;15:164–167.

3. Wiley JJ, Baxter MP. Tibial spine fractures in children. Clin Ortho Relat Res. 1990:54–60.

Additional Reading

Lastihenos M, Nicholas SJ. Managing ACL injuries in children. Physician Sportsmed. 1996;24:59–70.

Stanitski C, Sherman C. How I manage physeal fractures about the knee. Physician Sportsmed. 1997;25:108–121.

Codes

ICD9

823.00 Closed fracture of upper end of tibia
823.10 Open fracture of upper end of tibia