Session IV - Femur

The Association between Supracondylar Intercondylar Distal Femoral Fractures and Hoffa Fractures

Sean E. Nork, MD; Kamran Aflatoon, DO; Daniel N. Segina, MD; Stephen K. Benirschke, MD; Milton L. Routt, MD; M. Bradford Henley, MD, Harborview Medical Center, Seattle, WA

Purpose: Isolated coronal plane fractures (Hoffa fractures) of the distal femoral condyles are uncommon and are difficult to treat. The combination of supracondylar intercondylar distal femoral fractures with ipsilateral Hoffa fractures is thought to occur rarely. The purposes of this study are to identify the frequency of the association between supracondylar intercondylar distal femoral fractures and coronal split fractures and to describe the radiographic evaluation of these injuries.

Methods: One hundred twelve patients with 117 intra-articular distal femoral fractures were surgically treated over a 5-year period at a level I trauma center. Patients with isolated unicondylar fractures (n = 26) were excluded. The records of the remaining 86 patients with 91 supracondylar intercondylar distal femoral fractures were reviewed. There were 60 male and 26 female patients ranging in age from 15 to 88 years (average 44.7 years). Mechanisms of injury were motor vehicle accident in 52, fall >from a height in 13, motorcycle accident in 7, crush injury in 4, pedestrian versus automobile accident in 3, ballistic injury in 3, and miscellaneous injuries in 4. The fractures were classified according to AO and OTA guidelines as 33C1 (n = 8), 33C2 (n = 29), and 33C3 (n = 54).

Results: Coronal split fractures were diagnosed in 37 of 91 (41%) supracondylar intercondylar distal femoral fractures (33C). In distal femur fractures with articular comminution (33C3), coronal split fractures were diagnosed in 68.5% of knees. Among patients with unicondylar Hoffa fractures, 85% involved the lateral condyle. Ten of 37 injuries (27%) involved coronal split fractures of both the medial and lateral femoral condyles. Fifty-three percent (n = 48) of these distal femur fractures were open fractures. Twenty-eight of 37 fractures (78%) with at least one Hoffa fracture were open compared to 20 of 54 (37%) of injuries without a Hoffa fracture (P = .00022). Ninety percent of injured extremities with bicondylar Hoffa fractures were open. According to the classification system of Letteneur, there were 8 Type I fractures and 39 Type III fractures. Five coronal-split fractures were segmental injuries with multiple condylar fragments. The average ISS among patients with a coronal split fracture was 20.6 (range, 9-50), compared to 16.1 (range, 9-50) for patients without a coronal split fracture (P = 0.028).

Plain radiographs identified these fractures in only 72% of patients. Computed tomography (CT) was used to make the diagnosis in an additional 15% of patients. The remaining 6 unrecognized Hoffa fractures were discovered only at the time of operative fixation of the distal femoral fracture. These included 2 patients with unrecognized coronal fractures that were discovered at the time of angled blade plate seating chisel placement, necessitating a change in implants. Of the 47 coronal split fractures, 26 were displaced while 21 were non-displaced.

Discussion: The association between Hoffa fractures and intra-articular distal femur fractures has previously received little attention. Operative treatment has been recommended for recognized injuries. Missed fractures treated nonoperatively have been associated with poor results. Identification of these injuries is often difficult on plain radiographs. CT scans may help delineate these fracture patterns. Identification of this injury pattern may help dictate the fixation of the distal femur fracture as well as the coronal split fragment.

Conclusions: Coronal split fractures occur frequently (41%) in high-energy 33C distal femoral fractures. These associated injuries are usually open in blunt trauma patients (76%). Lateral condyle Hoffa fractures occur more frequently than medial condyle Hoffa fractures. Bicondylar involvement is relatively common. CT is helpful in diagnosing these injuries and should be considered in supracondylar intercondylar distal femoral fractures, especially in those with associated open wounds.