Atypical Tibial Tuberosity Fracture in an Adolescent

Case Report

A 13-year-old boy presented with sudden onset of right knee pain and inability to bear weight on that leg, after jumping while playing basketball. There was no history of pre-existing skeletal disease.

Physical examination revealed swelling, pain, and tenderness directly over the tibial tuberosity and posterior aspect of the proximal tibia. The patient was unable to actively extend the knee. Standard anteroposterior (AP) and lateral radiographs revealed an Ogden type IIIA fracture of the tibial tuberosity with an extension posteriorly into the proximal tibial physis (Figure ).

Figure 2:. Preoperative AP (A) and Lateral (B) Radiographs Showing a Combination of Ogden IIIA Fracture of the Tibial Tuberosity and Salter-Harris IV Fracture of Posterior Tibial Physis.

Computed tomography revealed a Salter Harris type IV fracture extending posteriorly (Figures , ). Due to the coronal and sagittal elements of the fracture, it was difficult to classify the fracture based on the revised AO/OTA fracture and dislocation classification compendium from 2007. We believe that the fracture sustained by our patient fit most closely with 41C1, as it was complete articular with minimal displacement.

Figure 3:. Preoperative Sagittal CT Scan of the Knee Confirming the Combination of the 2 Fractures (ogden IIIA with Salter-Harris IV).

Figure 4:. Preoperative Axial CT Scan Showing Extension of the Fracture Posteriorly into the Proximal Tibial Physis.

The fracture was anatomically reduced via an anterolateral approach and stabilized with a partially threaded transepiphyseal cannulated screw and a metaphyseal screw under fluoroscopic guidance (Figure ). The avulsed periosteum was also repaired.

Figure 5:. Intraoperative Lateral Radiograph Demonstrating Anatomical Reduction of the Fracture with Transepiphyseal and Metaphyseal Partially Threaded Cannulated Screws.

The patient was monitored perioperatively for compartment syndrome. The knee was immobilized in an above-the-knee back slab for 2 weeks followed by a hinged knee brace locked in extension for 2 weeks. At 4 weeks, the brace was unlocked allowing full range of motion and weight bearing.

Postoperatively, the patient was followed up to 15 months. The fracture had healed clinically and radiologically at 4 weeks, with full range of motion of the knee at 8 weeks (Figure ). At 15-month follow-up, although there was some lucency at the tip of the metaphyseal screw (Figure ), the patient was completely asymptomatic and was actively involved in playing football, with no growth plate asymmetry.

Figure 6:. Postoperative AP Radiograph at 20-Week Follow-Up, Showing Union and No Growth Plate Asymmetry.

Figure 7:. Postoperative Lateral (A) and AP (B) Radiographs at 15-Month Follow-Up, Demonstrating Union. Lucency Around the Tip of the Screw Is Noted on the Lateral Radiograph.

Discussion

A combination of avulsion fracture of the tibial tuberosity and simultaneous posterior proximal tibial physeal fracture is rare and reported only once in the published literature. ⁹ The developmental anatomy of the tibial tuberosity and the changes surrounding its normal physiologic epiphysiodesis makes it susceptible to acute avulsion fracture. ⁸ Associated injuries include patellar or quadriceps avulsion, collateral or cruciate ligament ruptures, and meniscal injuries. ^2,9–11

Beaty and Kumar ¹² described the importance of histogenesis of the tibial tuberosity during adolescence. Tibial tuberosity develops as a structural modification of the anterior portion of the tibial epiphysis and it is mainly made up fibrocartilage that can withstand tensile forces. This fibrocartilage is replaced by hypertrophic physeal cartilage in a proximal to distal direction, allowing angular avulsion.

Tibial tuberosity avulsion differs from Osgood-Schlatter disease, as in the latter there is avulsion of anterior ossicle of the tuberosity unlike involvement of physis in the former. In Osgood-Schlatter disease, the germinal cartilage of the physis is still attached to the tuberosity. Ogden et al ⁶ suggested a relationship between the tibial tuberosity avulsion and Osgood-Schlatter disease but this has not been conclusively proven.

Our patient was an adolescent and sustained the injury while playing basketball. This is in keeping with the previous published reports demonstrating the proclivity of tibial tuberosity avulsions to young athletic males. ^{1,2,6,8,9,13,14} We believe that the patient sustained the tibial tuberosity avulsion during the take-off phase of the jump due to sudden violent contraction of the quadriceps as the knee was extending. This was then followed by the posterior Salter Harris type IV fracture of proximal tibial physis as he landed on his leg with enormous forces passing through the knee. This combination of fractures could also result in significant vascular and ligamentous injuries.

Compartment syndrome has been recognized as a complication associated with tibial tuberosity avulsions. ^4,15–17 Curtis ⁹ found complete avulsion of the periosteum and medial collateral ligament in his patient who had a combination of 2 fractures similar to our patient. This patient required a 4-compartment fasciotomy due to elevated compartmental pressures. Our patient had no evidence of compartment syndrome or ligamentous instability.

Anterior cruciate ligament, collateral ligament, and meniscal injuries are likely to be missed as tibial tuberosity avulsions may look innocuous on plain radiographs. These concomitant soft tissue injuries should be excluded by further imaging and taken into consideration in the management of the patients. Our case stresses the importance of thorough clinical examination and further radiological investigations in the form of CT or MRI in diagnosing and planning appropriate surgical management of such complex fracture patterns.

As in any intra-articular fracture, it is vital to restore the congruity of the articular surface by achieving anatomical reduction. There is no dispute that type III and type IV fractures require open reduction and internal fixation. There are varying recommendations for the management of type II fractures.

Mckoy and Stanitkski ⁸ recommended open reduction and internal fixation for all Type IIB fractures. Chow et al ¹ suggested conservative treatment in a cast for type IIB fractures only if they could be reduced adequately. In a report of 20 tibial tuberosity fractures, Frey et ⁴ al treated all their patients operatively but recommended initial attempt at closed reduction and cast for type IIA fractures and to consider open reduction and internal fixation if reduction was not maintained.

As our patient had a combination of Ogden IIIA and Salter Harris type IV fracture, both the fractures have to be addressed during surgical fixation. Intraoperatively, accurate reduction and stabilization was achieved by capturing both, the anterior and the posterior fragments with the partially threaded cannulated screws under image intensifier control. Postoperative protection in a plaster cast for 4 weeks usually suffices and should also be judged by radiological evidence of union.

The need for removal of implants in children remains controversial. ^18,19 Raney et al, ²⁰ in their recent evidence-based analysis concluded that there was no published evidence to support or refute the practice of routine removal of orthopedic implants in children. An overall complication rate of 12.5% after removal of implants in children was reported by David et al, ¹⁹ with 11.4% occurring after elective implant removal.

Several factors dictate the decision to remove implants in the pediatric population. ¹⁸ These include location of the implant, with proximal femoral and physeal location being favorable to removal and pelvic and femoral diaphyseal implants favored toward retention. It is preferred to remove implants in younger children. Less experienced orthopedic surgeons favor retaining the implants as compared to more experienced pediatric and general orthopedic surgeons. ¹⁸

Conclusion

To our knowledge, this is only the second reported case of a combination Ogden type IIIA tibial tuberosity fracture and Salter Harris IV fracture of posterior proximal tibial physis, and the first case with these fracture configurations to recover completely without complications. We recommend vigilance and a high index of suspicion for coexisting fractures or soft tissue injuries when treating avulsion fractures of the tibial tuberosity. A CT scan is justified in such patients to recognize complex fracture configurations, and surgical treatment should be directed appropriately to both the fractures, followed by early rehabilitation. Patients with such injuries warrant close monitoring for compartment syndrome during the perioperative period.