Review Question - QID 217149

Distal Femoral Physeal Fractures - Pediatric Complications Limb length discrepancy or angular deformity(most common) QID: 217149 (OBQ16.132.2)

QID 217149 (Type "217149" in App Search)

A 13-year-old male well-known to your clinic presents for follow-up. Due to the COVID-19 pandemic, the patient was lost to follow-up. Your relationship with this patient began when you originally treated an injury to his left knee, seen in Figure A, with a treatment modality similar to that demonstrated in Figure B. The patient was 11 years old at the time of his initial injury, and his hardware was appropriately removed after his fracture had fully healed. You obtain full-length radiographs of his bilateral lower extremities today, which demonstrates a 20 mm limb length inequality, left shorter than right, with no apparent angular deformity. His skeletal age, based on his hand and wrist radiographs, matches his chronological age. If he has the most common complication following his injury, which is the expected leg length discrepancy once he reaches skeletal maturity?

Type & Select Correct Answer

Type in at least one full word to see suggestions list

Approximately 2.0 centimeters, left shorter than right

48/1386

Approximately 3.5 centimeters, left shorter than right

12%

170/1386

Approximately 5.0 centimeters, left shorter than right

82%

1141/1386

Approximately 3.5 centimeters, right shorter than left

10/1386

Approximately 2.0 centimeters, right shorter than left

8/1386

Select Answer to see Preferred Response

The most common complication after distal femoral physeal injuries is physeal arrest and subsequent leg length discrepancy (LLD) can occur. This patient has an anticipated 3 years left of growth which will result in a 47 mm LLD (20 mm + (9mm/year * 3 years).

Salter-Harris (SH) fractures of the distal femoral physis most often are complicated by growth arrest. The arrest occurs secondary to injury to the zone of hypertrophy of the physis, with the fracture occurring through the zone of provisional calcification (Illustration A, Section D). This is thought to be secondary to the relative undulating anatomy of the distal femoral physis. Many patients will have a final LLD greater than 2.0 cm. LLD is most common following SH IV fractures (64%), followed by SH II fractures (58%). The distal femur contributes approximately 9mm/year to longitudinal growth, and injury to this physis can have a marked effect on final limb length at skeletal maturity.

Basener et al. performed a meta-analysis investigating distal femur physeal fractures. The authors found that 52% of distal femur physeal fractures led to growth disturbance and that 22% of patients had a final LLD greater than 1.5 cm. Rates of disturbance were found to be highest following SH IV fractures and lowest following SH I fractures.

Arkader et al. performed a retrospective review of all patients who sustained a distal femur physeal fracture. Their study included 73 patients with an average age of 10 at the time of injury. 43/73 (59%) of fractures were SH II. The authors found that the overall complication rate was 40% and that growth arrest was the most frequent complication. They found that while displaced fractures had a higher complication rate, the amount and direction of displacement did not correlate with complication rate.

Figure A is an AP radiograph of an SH II distal femur fracture. Figure B is a fluoroscopic image demonstrating fixation of a distal femur fracture using partially-threaded, cannulated screws. Illustration A is a high-powered micrograph of the physis. Zone B represents the reserve zone, zone C represents the proliferative zone, Zone D represents the hypertrophic zone and Zone E represents the primary spongiosa.

Incorrect Answers:
Answers 1 and 2: With regards to the lower limb, the proximal femur contributes 3 mm/year, the distal femur 9 mm/year, the proximal tibia 6 mm/year, and the distal tibia 5 mm/year. The patient is 13, and his skeletal age matches his chronological age. As boys stop growing around 16 years of age, given his current LLD of 20 mm, his final expected LLD is 20 mm + (3 x 9mm) or 47 mm, which is closest to 5.0 cm (Answer 3). The remaining answers are incorrect.
Answers 4 and 5: Distal femur physeal injuries are associated with growth retardation, not acceleration. The affected extremity will be shorter, not longer, than the unaffected extremity.

ILLUSTRATIONS: