Keywords
tibial fractures - fractures, avulsion - knee injuries
Introduction
Even though the knees of adolescents are commonly exposed to violent trauma, avulsion fractures of the proximal tibial epiphysis are infrequent, with an incidence ranging from 0.3% to 2.7% of all physical injuries.[1]
[2]
[3] Trauma mechanisms include eccentric contraction of the quadriceps at the beginning of a jump or during landing,[4] in addition to torsion traumas.[5] These injuries are more frequent in males aged between 14 and 16 years.[1] The classification of these fractures was described by Watson-Jones[6] in 1955, and modified by Ogden, Tross and Murphy[7] and, later, by Ryu and Debenham.[8]
The present article is a report of the case of an adolescent with an atypical avulsion fracture of the tibial tuberosity and proximal epiphysis, with a one year of follow-up. The use of the data was approved by the institutional Ethics in Research Committee.
Case Report
A 14-year-old male patient sprained his left knee during a soccer match. He was first cared for at the emergency department of a secondary hospital. He had local pain in the left knee, 2 +/4+ edema, and inability to walk and to perform flexion-extension the knee, but had no neurovascular changes or signs of compartment syndrome. A radiographic series revealed a physical fracture in the left proximal tibia ([Fig. 1]), classified as type IV by Ogden, Tross and Murphy,[7] with a modification, by Ryu and Debenham, and later classified as type IV-B by Aerts et al.[5]
Fig. 1 Anteroposterior and lateral radiographs of the left knee showing avulsion fracture of the tibial tuberosity.
Immobilization was initially performed with a plaster cast from the inguinal to malleolar regions, followed by analgesia. The patient was operated on the next day, when open reduction and internal fixation using 4.5-mm cannulated screws were performed ([Figs. 2A] and [2B]). The patient was discharged one day after surgery, with plaster cast immobilization and load restriction for four weeks. Then, partial load with crutches was allowed for two weeks, gradually progressing to full load with physical therapy to regain the range of motion of the knee. Bone consolidation was radiologically confirmed three months after the procedure ([Figs. 2C] and [2D]), when the patient was allowed to resume sports activities. During the one-year follow-up, the patient evolved with no length discrepancy in the lower limbs nor the development of genu recurvatum, maintaining a range of motion similar to that of the contralateral limb ([Figs. 3] and [4]).
Fig. 2 Anteroposterior and lateral radiographs at the immediate postoperative period (A,B); anteroposterior and lateral radiographs three months after surgery (C,D).
Fig. 3 Radiographs one year after surgery.
Fig. 4 Clinical images one year after surgery.
Discussion
The physis, which is not as stiff as the remaining bone tissue, is an area of the immature skeleton highly susceptible to injury. Since excessive physical activity increases the physeal load, adolescent athletes present a higher risk of suffering proximal tibial injuries. The predisposing factors include low patella, shortened hamstrings, preexisting Osgood-Schlatter disease, and physeal abnormalities.[9]
The growth plate consists of four layers. Mechanically, the hypertrophic cell zone is the weakest region, and a common site for physical injury. The proximal tibial epiphysis is the second largest bone epiphysis of the body, following the distal epiphysis of the femur. It is fragile because of the dorsal cartilage of the apophysis (tibial tuberosity), which is influenced by traction forces throughout the ossification and fusion phases.[5] This fusion is not uniform, as the posterior region closes before the anterior region.[2] Since the anterior region is more vulnerable to traction forces because of the patellar tendon attachment, an avulsion fracture at a closed posterior region causes a posterior metaphyseal fracture (Salter-Harris type II),[5] as observed in the case herein reported. This lesion is believed to be rare because of the small ligament attachment at the tibial proximal epiphysis, making this bone free from varus and valgus strains to the knee.[3]
In 1995, Watson-Jones[6] classified proximal tibial physis injuries into 3 types. Type I is defined as an avulsion of the distal part of the tuberosity, distal to the proximal tibial physis. In type II, the injury extends across the entire physis, but does not reach the knee joint. Type III is an avulsion extending proximally to the knee physis.[6] This division was modified by Ogden, Tross and Murphy,[7] who created two groups to define fragment deviation (subtype A) and comminution (subtype B). Later, Ryu and Debenham[8] defined type IV, describing it as a fracture that extends through the physis and causes an avulsion of the entire proximal epiphysis. Aerts et al.[5] proposed the subdivision of type IV into type IV-A, in which there is avulsion of the entire epiphysis alone (Salter Harris I), and type IV-B, in which, in addition to a complete physeal lesion, the posterior part of the metaphysis is involved, highlighting the well-known Thurston-Holland fragment (Salter Harris II), as in the case herein described ([Fig. 5]).
Fig. 5 Ryu and Debenham[8] classification of type IV, modified by Aerts et al.[5] to IV-B.
The treatment of these lesions presents some difficulty regarding reduction due to the constant force acting on the quadriceps. As most patients are in the final stage of physical growth, few growth changes are noticed.[10] In this case, there were no changes in the range of motion of the joint and in the length of the limb. An accepted treatment protocol is preconized by Frey et al.,[4] which defines the conservative therapy with immobilization in extension for four to six weeks in type-IA, -IB and -IIA fractures. The remaining types are treated with osteosynthesis with open reduction and internal fixation followed by immobilization for four to six weeks, as in the case herein described. Early diagnosis and treatment improve functional outcomes and return to activities.[10]
The complications include compartment syndrome, lesion to the cruciate ligaments or the meniscus, quadriceps rupture, quadriceps hypotrophy, hypertrophy or fracture of the tibial tuberosity, calcification of the patellar tendon, limb discrepancy, genu recurvatum, pseudoarthrosis, and low patella.[8] None occurred in the case herein reported.
Conclusion
Avulsion fracture of the tibial tuberosity, although infrequent and potentially serious due to the important physeal involvement, presents good outcomes with the usual surgical treatment strategies. We describe a rare case of a type-IV-B fracture as classified by Aerts et al.[5] The clinical and functional outcomes were good, similar to those described in the literature.
