1 Introduction

Hoffa fractures are named after Albert Hoffa, who, in 1904, described a rare subtype of supracondylar distal femoral fractures in the coronal plane. The estimated incidence of isolated femoral condylar fractures, either lateral or medial, is 0,65 % of all femoral fractures.^1,2

Lateral condylar and bilateral condylar fractures are more common than isolated medial condylar fractures. Isolated medial Hoffa fracture present a even rarer injury with sparse reports being found in literature.

Letenneur et al. provided a classification for Hoffa fractures, dividing them in three types according to the orientation of the fracture line.³ Type I is a vertical fracture parallel to the posterior femoral cortex, Type II a horizontal fracture and Type III a fracture oblique to the femur.³

Although the exact mechanism of this injuries remains unclear, they are usually associated with high energy traumas. Axial load exerted in a flexed knee, as occur in motor vehicle crashes, is believed to be the most frequent mechanism involved.¹ It has also been proposed that medial Hoffa fractures might result from a medial impact on the medial femoral condyle while the affected knee is in a flexed position with an element of adduction and internal rotation.⁴

Diagnosing this fracture might be challenging and a high clinical suspicion is required as standard radiographs may seem apparently normal.¹

Computed tomography (CT) is often necessary both for diagnosis and preoperative planning.

Conservative treatment of Hoffa fractures had been associated with poor outcomes. Being intra-articular fractures with significant risk of displacement, anatomical reduction with a stable osteosynthesis is required to allow proper rehabilitation of the patient.⁵

Arthroscopic management of this type of fractures not only provides optimal control of the reduction but also enables the diagnosis and treatment of concomitant lesions.²

Although fully arthroscopic approaches are not frequently reported for the treatment of Hoffa fractures, this is a less invasive method associated with minimal soft tissue damage, blood loss and infection rates^2,6

2 Case report

The authors present a case of a 38 year-old male patient, with no past medical history, who presented at an orthopaedic emergency department after being involved in a motor vehicle accident. He sustained an axial compression trauma on his right knee.

3 Clinical findings

At examination, the knee was swollen and painful. Functional impairment was noticed and the patient could not tolerate weightbearing. No neurovascular compromise was identified after careful neurovascular examination.

The patient sustained no additional lesions.

4 Diagnostic assessment

Anteroposterior X-ray of the knee was apparently normal but the lateral view revealed a Hoffa fracture of the medial femoral condyle (Fig. 1).

Close

Fig. 1 X-ray at admission.

Export to PPT

CT scan confirmed the diagnosis and revealed the presence small fragments in the trochlear area (Figs. 2 and 3). The patient was planned for an arthroscopic-assisted fixation of his fracture.

Close

Fig. 2 CT at admission demonstrating a medial condyle fracture.

Export to PPT

Close

Fig. 3 CT at admission, axial view.

Export to PPT

5 Differential diagnosis (if any)

When evaluating this patient at the emergency department complaining of knee pain, edema and functional impairment after a traumatic event, some of the diagnostic possibilities that should be taken into account include fractures of the distal femur or proximal tibia, meniscal tears and ligamental injuries.

The initial physical examination do not have a high accuracy as meniscal and ligamental tests are difficult to perform due to the edema and pain felt by the patient after a traumatic event.

The mechanism described by the patient made it less likely for meniscal or ligamental injuries. Even though these lesions might be present in some fractures around the knee, they tend to occur more frequently with torsional or rotational movements.

The definitive diagnosis can only be assumed after careful image evaluations are performed.

6 Therapeutic intervention

In the operating room, the patient was positioned supine and a tourniquet was applied to his upper thigh.

Arthroscopy was initially performed through the standard anteromedial and anterolateral portals. A comminutive fracture of the medial femoral condyle was identified with two main fragments and small intra-articular fragments being found. Those small fragments were arthroscopically removed. No other intra-articular lesion was diagnosed and the menisci and cruciate ligaments were found intact.

In order to achieve optimal reduction, a posteromedial portal was necessary, as it provided better access to the main fragments.

With the knee flexed to 120°, a bone clamp was used to reduce the fracture. Maintaining the knee in hyperflexion relaxes the posterior capsule and gastrocnemius while the tibial plateau forces the fragments into their place.

Two guide-wires were inserted in an anteroposterior direction in order to achieve provisional reduction of the main fragments. The length and position of the Kirschner wires were verified by intraoperative fluoroscopy.

After that, the fracture was fixed with three 4.0mm screws inserted from anterior to posterior (Figs. 4 and 5).

Close

Fig. 4 Anteroposterior post-operative X-ray.

Export to PPT

Close

Fig. 5 Lateral post-operative X-ray.

Export to PPT

7 Follow-up and outcomes

The patient was put in an extension brace and instructed to stay non-weight bearing for six weeks. After that, partial weight bearing was allowed and the patient enrolled a rehabilitation protocol. Full weight bearing was allowed at 8 weeks.

Four months after surgery, the patient regained full active range of motion of the affected knee and described that episodes of pain were gradually decreasing its frequency and intensity.

At the sixth month follow-up, the patient presented with no complaints of pain or functional impairment. He claimed to be satisfied with the outcomes achieved as he returned to his previous daily activities with no limitations found.

8 Discussion

Ethical statement

The authors declare that the article entitulated “Arthroscopic reduction and fixation of an Hoffa fracture of the medial femoral condyle: case report” received approval from the Ethical Committee of Centro Hospitalar da Póvoa de Varzim/Vila do Conde.

Financial support and sponsorship

This study did not receive any financial support.

The authors declare that a full consent was obtained for the patient to publish the present article entitulated “Arthroscopic reduction and fixation of an Hoffa fracture of the medial femoral condyle: case report”.

The authors declare that the article entitulated “Arthroscopic reduction and fixation of an Hoffa fracture of the medial femoral condyle: case report” received approval from the Ethical Committee of Centro Hospitalar da Póvoa de Varzim/Vila do Conde.

Patient consent

The authors declare that a full consent was obtained for the patient to publish the present article entitulated “Arthroscopic reduction and fixation of an Hoffa fracture of the medial femoral condyle: case report”.

CRediT authorship contribution statement

Catarina Silva Souto: Each author personally and significantly contributed towards the development of this article. Diana Bicas Machado: Data collection, survey of the medical records. Nuno Rodrigues: Data collection and participated in the reviewing process. Nuno Tavares: conceived and planned the activities that led to this report, including literature review, wrote the paper, participated in the reviewing process, approved the final version.