A LOWER ENERGY MECHANISM FOR DISTAL FEMORAL GROWTH PLATE INJURIES IN DEVELOPING COUNTRIES: A PROSPECTIVE STUDY

Abstract

Distal femoral growth plate (DFGP) fractures were originally described as the ‘wagon wheel’ fractures, because they were noted to occur in the young boys who ran alongside wagons passing at speed and got their leg caught between the spokes. The resultant high energy injury was a forceful hyperextension and twisting of the knee. There was a significant incidence of severe complications with these injuries. In our setting, in a developing country, we noted that DFGP injuries appeared more common and tended to occur with a lower energy mechanism of injury.

To investigate if this were a real phenomena, we designed a prospective study looking at DFGP injuries with the primary outcome measure being the mechanism of injury and the secondary outcome measures including method of fixation and functional outcome.

The inclusion criteria for the study were all patients that presented with a DFGP fracture over a period of one year. There were no exclusion criteria. All data was collected prospectively on a standard proforma. Patients were treated according to a standard treatment regimen: where the fracture could be reduced closed and was stable, plaster cast only. Where a fracture could be reduced closed and was unstable, percutaneous pin fixation, where a fracture could not be reduced closed, open reduction and internal fixation.

Forty-three patients were included in the study. 39/43 (91%) of the patients were boys, and the average age was 15.5 years (standard deviation, SD, 3.2 years). Thirty-three (77%) of the injuries resulted from low energy trauma, with the majority (28/33) resulting from sporting injuries, predominately football, with others having simple falls (3/33) or falling off bicycles (2/33). The 10 high energy injuries resulted from pedestrians (3/10) or cyclists (1/10) hit by cars and falling from a height (6/10). Some significant differences were seen in the mean ages of the high and low energy groups. The low energy group were significantly older, with a mean age of 16.3 years (SD 2.8 years) compared to 13.1 years (SD 3.1 years) for the higher energy group (Student’s t-test, p=0.004). When comparing the type of fracture, according to the Salter Harris classification, significantly more Salter Harris IV and V fractures were seen in the high energy group (Chi Squared test, p=0.039) compared to the low. Open fractures were 1/10 (10%) of the high energy group, but there were no open fractures in the low energy group. Complications including infection and amputation, only occurred in the high energy group.

This is the first study to show, that in some countries, the DFGP injury may be more commonly due to a low energy mechanism of injury. The reasons for this may include delayed physeal closure, that has been previously shown in this group.