Tibial Tubercle Avulsion

Updated: Aug 08, 2018
  • Author: Janos P Ertl, MD; Chief Editor: Thomas M DeBerardino, MD  more...
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Overview

Background

A tibial tubercle avulsion fracture is usually an injury to the knee occurring in adolescence, during the transitional phase of physeal closure just prior to completion of growth. [1] This fracture most often is an isolated injury related to pushoff or landing while jumping as the quadriceps eccentrically contracts to support the individual's weight.

The fracture tracks through the proximal tibial epiphysis and may extend into the anterior portion of the knee joint. The proximal tibial physis closes from posterior to anterior, and the fracture pattern is dependent on the amount of physeal closure present at the time of injury. Some authors consider this injury to be a variant of a Salter-Harris III fracture pattern. Open reduction with internal fixation (ORIF) is recommended, in that reduction is difficult to maintain against the pull of the quadriceps muscle.

An extended classification system was developed that includes types I, II, III, IV, and V. Types I, II, and III were described by Watson-Jones; these may be further divided into A, B, and C subtypes, with A indicating displacement, B indicating comminution, and C (added by Frankl) indicating associated patellar ligament avulsions. For classification of more extensive injury, type IV was introduced by Ryu and type V by Mckoy. [2]

The difficulty with this fracture is in maintaining a satisfactory reduction against the proximal pull of the quadriceps muscle. The patient usually is very close to the end of growth, and fixation of the fragment should not affect remaining growth. In the rare instance in which this fracture occurs in a younger individual, suturing of the periosteum and retinaculum and temporary smooth Kirschner wire (K-wire) fixation may be performed.

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Anatomy and Pathophysiology

The proximal tibia physis progressively closes from posterior to anterior. The tibial tubercle is vulnerable to injury during the transitional phase of closure.

The tibial tubercle physis is in continuity with the tibial plateau. The physis progressively fuses from posterior to anterior, making it most vulnerable to avulsion in adolescents aged 13-16 years.

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Etiology

The mechanism of injury usually is an indirect force caused by sudden contraction of the quadriceps muscle. During sudden acceleration and deceleration forces, the quadriceps mechanism forcefully contracts against the patellar tendon insertion. When the force is greater than the strength of the tibial tubercle physis, a fracture is created, leading to avulsion of the tibial tubercle. Additional predisposing factors include patella baja, tight hamstrings, preexisting Osgood-Schlatter disease, and disorders involving physeal abnormalities. [3]

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Epidemiology

Tibial tubercle avulsion fractures are commonly seen in athletic males (frequently basketball players) aged 14-16 years. [4] These fractures account for 1-3% of physeal injuries.

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Prognosis

With appropriate surgical treatment and postoperative therapy, a complete recovery without residual symptoms is expected. A return to sports may be expected once the strength of the affected lower extremity reaches 90% of that of the unaffected extremity (usually 4-6 months after injury).

In a systematic review of the English-language literature on pediatric tibial tubercle fractures from 1970 to 2013, Pretell-Mazzini et al examined treatment outcomes (functional and radiologic) and complications. [5]  Clinical outcomes were evaluated on the basis of qualitative assessment, return to preinjury activity, and range of motion (ROM) in the knee. Fracture healing, associated injuries, compartment syndrome, and complications were assessed as well.

In this study, 98% of surgical cases were treated with ORIF. [5] ​ Fracture consolidation was accomplished in 99.4% of cases, and 98% of patients, regardless of fracture type, were able to return to preinjury activity and regain knee ROM. The overall complication rate was 28.3%, with the most frequent complication being removal of an implant because of bursitis (55.8%), followed by tenderness/prominence (17.9%) and refracture (6.3%). The incidence of compartment syndrome was 3.57%. The authors noted the need for longer follow-up to determine long-term outcomes.

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