Complex Variant of Paediatric Conjoint Bicondylar Hoffa Fracture: A Rare Entity

Abstract

Isolated, closed, conjoint bicondylar Hoffa fracture in a child is extremely rare with only three cases reported in literature till date. We report a complex variant of this very rare injury. An 11-year-old male child reported 2-week post-trauma with history of fall from a tree and injury to his right knee. Radiographs revealed a coronal plane fracture of the distal femur. The patient was operated using the swashbuckler approach, which revealed a sagittal split of the lateral femoral condyle along with a conjoint bicondylar Hoffa fracture. Fixation was done using multiple lag screws and fracture went on to uneventful union. Patient was followed up for 3 years and except for limb shortening of around 1.5 cm secondary to premature physeal closure as a consequence of the injury, he had excellent outcome with full range of motion at the knee, without any deformity.

Introduction

A Hoffa fracture is a coronal plane fracture of the distal femur. It is usually seen in combination with epiphyseo-metaphyseal fractures of the distal femur [1]. As these injuries are a result of high energy trauma, they are usually seen in polytrauma patients and open injuries are common. Isolated Hoffa fractures are rare in adults and much rarer in children and usually involve only one condyle, mostly the lateral condyle. Hoffa fracture involving both the condyles is extremely rare [2]. When the fracture line passes such that both the Hoffa fragments are joined by a bridge of bone, it is called as a conjoint bicondylar Hoffa. To the best of our knowledge only three cases of closed, isolated, paediatric conjoint bicondylar Hoffa fracture have been reported in English literature till date [2–4]. We are reporting a complex variant of a closed, conjoint bicondylar Hoffa fracture in a child.

Case Presentation

An 11-year-old boy sustained injury to the right knee following fall from a tree. Initially, he was taken to an osteopath and presented to us 2 weeks later with a swollen right knee and inability to bear weight on the affected lower limb. On examination, his knee was tender and any attempted movements at the knee were severely painful and restricted. There were no signs of any external wound. Distal pulsations were well felt and there was no distal neurovascular deficit. Antero-posterior and lateral radiographs revealed a coronal plane fracture of the distal femur (Fig. 1). Although a Computed Tomography (CT) scan was desirable to evaluate the fracture morphology, it could not be done for technical reasons.

Fig. 1.

Pre-operative radiographs

The patient was posted for open reduction and internal fixation. With patient in supine position on a radiolucent top simple operation table, under spinal anaesthesia and tourniquet control, the knee was exposed using the swashbuckler approach. We were expecting a coronal plane fracture of the distal femur and were surprised to find a conjoint bicondylar Hoffa fracture along with a sagittal split of the lateral condyle. The Hoffa fragment was posteriorly and proximally displaced, and since it was 2-week post injury, initially we faced some difficulty but finally managed to reduce the fragment back into place. The lateral condylar fragment was then reduced and provisionally fixed using multiple kirschner wires. The conjoint Hoffa fragment was fixed using lag screw technique with two 4 mm cancellous screws placed antero-posteriorly in the lateral condyle and one antero-posterior 4 mm cancellous screw and one Herbert screw placed postero-anteriorly in the medial condyle. The lateral condylar sagittal fragment was then fixed using two 4 mm cancellous lag screws placed in a lateral to medial direction (Fig. 2). The knee was stable post fixation and there was no evidence of any obvious ligamentous injury.

Fig. 2.

Intra-operative pictures (a, b) showing conjoint bicondylar Hoffa fracture with sagittal split of lateral condyle, c after reduction and fixation with lag screws

Post-operative radiographs revealed good reduction and fixation (Fig. 3). Knee was immobilised in an above knee plaster slab and the patient was allowed to walk non weight bearing using a walker. The surgical wound healed uneventfully and sutures were removed at end of 2 weeks following which knee range of motion was started. Partial weight bearing was started after 6th post-operative week, gradually increasing to full weight bearing by 12th week. At post-operative 3 months, patient had 10° extensor lag and flexion up to 120° (Fig. 4) which improved with rehab. At final follow-up, patient had full range of motion at right knee (Fig. 5a, b). Radiographs at the 2- and 3-year follow-up showed that the fracture had healed well; however, due to the nature of the injury, premature closure of the distal femoral physis was seen (Figs. 6, 7). Consequently, at final follow-up patient had a limb shortening of about 1.5 cm, without any obvious deformity (Fig. 8). The child needs to be observed till skeletal maturity and intervention may be needed to address the final limb length discrepancy in future. Patient consented to use of his details and images for publication.

Fig. 3.

Post-operative radiographs

Fig. 4.

Clinical picture showing range of motion at knee, 3-month post-surgery

Fig. 5.

a, b Clinical picture at final follow-up showing full knee range of motion

Fig. 6.

Two-year post-operative radiographs showing good healing but with premature physeal closure

Fig. 7.

Three-year post-operative radiographs

Fig. 8.

Clinical picture at final follow-up showing no deformity, complete knee extension and minimal limb shortening

Discussion

The Hoffa fracture which is a coronal plane fracture of the femoral condyle was first described by Friedrich Busch in 1869 and later by Albert Hoffa in 1904 [5]. Shearing force to the posterior femoral condyle as well as a direct impact and vertical shear with twisting mechanism has been proposed to cause this injury [3]. When the hyper-flexed knee is subjected to a posterior and upward directed force without any varus or valgus component, it may lead to a Hoffa fracture involving both the lateral and medial condyle as separate fragments. With the knee in slightly less flexion, it leads to a conjoint bicondylar Hoffa fracture, where the fractured fragment consists of both the lateral and medial condyle joined by a bridge of intact bone [3]. This injury pattern is rare in adults and extremely rare in children with only three cases of closed, isolated, conjoint bicondylar Hoffa fracture reported in paediatric population till date. Our patient had a complex variant of a conjoint bicondylar Hoffa with a sagittal split of the lateral femoral condyle and this type of injury has not been reported in literature till date. When the patient fell from the tree, he landed with a semiflexed knee onto the ground, with the lateral condyle striking first leading to a sagittal split of the lateral femoral condyle. The injury force continued resulting in a conjoint bicondylar Hoffa fracture.

Arthroscopic assisted fixation has been reported in minimally displaced fractures [2]. However, in displaced fractures, open reduction and internal fixation is mandatory. Adequate exposure to the posterior aspect of both the femoral condyles is difficult and few authors have advocated tibial tubercle osteotomy or dual (lateral and medial) approaches to expose bicondylar injuries. We used the swashbuckler approach which has been shown to give good access to both the condyles while causing less injury to the quadriceps mechanism, lesser fibrosis and early return of quadriceps strength and range of motion [3, 4]. Fixation was done using multiple lag screws perpendicular to the fracture plane.

To conclude, we are reporting a complex variant of a closed, conjoint bicondylar Hoffa fracture in a child who although reported 2-week post-trauma, could be managed well. Good surgical exposure by swashbuckler approach, accurate reduction, stable fixation and early mobilisation resulted in good long term result in this patient.

Abbreviations

CT

Computed tomography

mm

Millimetre

Author Contributions

Data Curation: SRR. Formal analysis and investigation: SDC. Writing-original draft preparation: SDC. Writing review and editing: SDC and SRR.

Compliance with Ethical Standards

Conflict of interest

The author(s) declare that they have no competing interests.

Ethical standard statement

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Informed consent

For this type of study informed consent is not required.