External fixation in the treatment of displaced supracondylar femoral fracture in children: A retrospective case series

Abstract

Objective:

The aim of this study was to evaluate the clinical and radiological outcomes and complications of external fixation use in the treatment of children with displaced supracondylar femoral fractures..

Methods:

In this retrospective study, 14 children (6 boys, 8 girls; mean age = 7.3 years; age range = 3.9 – 10.3 years) who underwent external fixation for the treatment of a displaced supracondylar femoral fracture from 2010 to 2017 were included. Their medical records were reviewed for general information and surgery details. Postoperative information, such as time to radiographic union, time to regain walking ability, Knee Society Scores (KSS) postoperative score, and KSS functional score were collected. Radiographic images were examined for the measurement of leg length discrepancy and valgus deformity.

Results:

The mean follow up was 34 (range = 24–50) months. The mean time to radiographic union was 12.3 (range = 10–16) weeks, and the mean time to regain walking ability was 11.8 (range = 11–13) weeks. Leg length discrepancies were all less than 0.8 cm, and valgus deformity was all limited in 10°. The mean KSS postoperative score was 97.5 (range = 93–100), and the mean KSS functional score was 97.1 (range = 90–100). None of the patients exhibited functional deficiency. Neither deep infection nor refracture was detected postoperatively.

Conclusion:

External fixation seems to be an acceptable alternative modality for treatingdisplaced supracondylar femoral fractures in children, with favorable clinical and radiological outcomes as well as a low complication rate.

Level of Evidence:

Level IV, Therapeutic Study

Highlights

• Fourteen patients with supracondylar fracture of the femur were treated with AO external fixator and followed up for 2 years.

• Time to the radiographic union, time to regain walking ability, the postoperative Knee Society Scores (KSS) and KSS functional score were collected.

Introduction

Supracondylar Fracture of the Femur (SFF) is uncommon in children; however, it is usually associated with complications, such as limb length discrepancy and severe angular deformity.¹,² Smith et al. reported that supracondylar femoral fracture accounts for 12% of femur fracture in children, and half of them are displaced.² Treatment of undisplaced SFF is not complex.³ However, there is still no consensus regarding the management of displaced SFF in children.⁴ Some unique characteristics make this type of fracture unstable.¹-⁴ Nonsurgical treatment was considered the standard treatment method for pediatric fractures traditionally, but the excellent bone remodeling even in children does not always correct residual deformity. The short distal metaphyseal fragment and continuous pull of the fragments by the gastrocnemius and adductor muscles make the fragment displaced, making nonsurgical treatment failure. Surgical techniques, including plate fixation, percutaneous pinning, and elastic nailing, are described in the literature. But, they have limitations such as injuring physis, insufficient stability for obese children, and complex procedure requiring experienced surgeons.⁵-¹⁰ External fixation is a widely used treatment for femoral fracture in adult.¹¹ The advantages of external fixation lie in a relatively easy procedure and short learning curves.¹² It is also practical for older children with higher weight,¹⁰,¹² but there was no consensus on the utilization of external fixation for SFF in children. This retrospective study aims to figure out the surgical outcomes, including union rates, complication incidence, recovery score, limb length discrepancy, and deformity degree of external fixation in the treatment of supracondylar fracture of the femur in children.

Materials and Methods

From June 2010 to August 2017, pediatric patients with supracondylar femoral fractures treated in the authors’ institution were reviewed in this study. The inclusion criteria were: 1) supracondylar femoral fracture confirmed on AP and lateral radiographic images, 2) treated with external fixation, and 3) followed up for 2 years or more. Supracondylar femoral fracture is defined as the fracture located at the square area where side length equals the widest part of the distal physis, extending from the epiphysis to proximal metaphysis.¹³ The exclusion criteria were: 1) patients with congenital diseases, 2) pathological fracture, 3) incomplete medical records, and 4) follow-up of less than 2 years.

We applied the AO hybrid frame biplanar external fixators in all the patients. All the surgeries were performed under general anesthesia and muscle relaxation without the use of a pneumatic tourniquet. The patient was positioned in the supine position, and the surgical site was painted and draped. Fractures were reduced by manual traction under the guidance of an image intensifier. Posteriorly displaced fracture was reduced by extension, and anteriorly displaced fracture was reduced by flexion. Shortening was reduced first, followed by angular and lateral displacements, and rotation was corrected at last. In case of open fractures, thorough debridement was performed initially.

Under fluoroscopy guidance, Schanz pins (3.5-5.0 mm) were applied from the anterolateral aspect of the femur along the safe zone, avoiding injury to the neurovascular structure. The first proximal-inferior pin was inserted 2-3 cm proximal to the fracture line, while the second proximal-superior pin was inserted to the shaft of the femur proximally along the same plane. The distal-proximal pin was inserted close to the fracture fragment, while the distal-inferior pin was inserted about 2-3 cm to the epiphysis. Insertion of the pins too posterolaterally or too proximally should be avoided. After the insertion of the pins, a rod was held with the clamp when the fracture was acceptably reduced without affecting knee Range of Motion (ROM).

Patients or patient’s caregivers were taught about pin care. Physiotherapy, including quadriceps strengthening exercise, started the next day, and knee ROM was started after 3-5 days postoperatively. Patients were encouraged to stand without extra aid at 6-8 weeks. When radiographic evidence of union was observed, and patients could walk by themselves without any pain, the external fixators would be removed. After the removal of external fixators, children were encouraged to go to school.

The general information of the patients, including age, gender, height, weight, injured limb, Arbeitsgemeinschaft für Osteosynthesefragen (AO)/Orthopaedic Trauma Association (OTA) classification,¹³ fracture type (transverse, oblique, comminution), time to union, limb length discrepancy and valgus deformity, were collected through the medical record system of authors’ institution. Radiographic union was symbolized by the disappearance of fracture line and bone callus formation. Limb length discrepancy and valgus deformity were measured on radiographic images. Knee Society Score (KSS) postoperative score and KSS functional score were evaluated at the last followup.¹⁴ This retrospective research was approved by the author’s IRB institution (IORG No: IORG0003571). Each patient’s parents were informed about the treatment protocol and signed consents.

Results

Fourteen patients diagnosed with supracondylar femoral fractures and treated with external fixators, including 6 males and 8 females, were included in the study. Their general information is shown in Table 1. The age of the patients ranged from 3.9 to 10.3 years (average 7.3). There were 7 fractures in the left limb and the other 7 in the right. Five of them had open and 9 had closed fractures. The causes of injury included motor vehicle accidents for 7, falls from elevated height for 6 and other reasons for 1. According to AO/OTA classification of fracture type, 7 patients had type 33A1, 3 patients had type 33A2, 4 patients had type 33A3.¹³

Table 1.

Characteristics of pediatric patients with supracondylar femoral fracture treated by external fixators

No.	Gender	Age, y	Side	AO/OTA Classification	Fracture type Open	fracture	Other fractures	Cause
1	Female	4.7	L	33A3	Comminuted	+	−	Vehicle accident
2	Female	3.9	L	33A1	Transverse	−	−	Vehicle accident
3	Female	5.8	R	33A1	Transverse	−	−	Vehicle accident
4	Female	7.1	L	33A3	Comminuted	+	−	Others
5	Male	7.3	R	33A1	Transverse	−	Opposite femur	Vehicle accident
6	Female	9.4	R	33A3	Comminuted	+	−	Fall
7	Female	9.4	L	33A3	Comminuted	+	−	Fall
8	Female	4.0	L	33A1	Transverse	−	−	Vehicle accident
9	Male	10.3	L	33A2	Oblique/spiral	−	−	Fall
10	Male	6.8	R	33A2	Oblique/spiral	−	−	Vehicle accident
11	Male	7.4	L	33A1	Transverse	−	−	Fall
12	Male	8.5	R	33A1	Transverse	−	−	Fall
13	Male	9.1	R	33A2	Oblique/spiral	+	−	Vehicle accident
14	Female	8.7	R	33A1	Transverse	−	−	Fall

The average operation duration was 48.9 minutes. Average intraoperative blood loss was 17.9 mL on average, most having less than 30 mL and none of them needed open reduction. However, one patient with an open fracture caused by a motor vehicle accident lost 90 mL of blood (Table 2). The average hospital stay was 9.9 days due to many complex comminuted open fractures. None of the patients had neurovascular injury neither had deep infection postoperatively. However, 2 patients had a pin site infection but entirely resolved with oral antibiotics and regular dressing change.

Table 2.

Surgery related information and postoperative information

No.	Operating time (min)	Intraoperative blood loss (mL)	Stay in hospital (day)	Time to radiographic union (week)	Time to regain walking ability (week)	KSS* postoperative Score	KSS* functional score	Leg length discrepancy (cm)	Valgus deformity degree
1	115	90	25	16	12	93	90	0.7	2-10°
2	32	10	5	10	11	100	100	0.5	<2°
3	38	15	5	11	11	99	100	0.6	<2°
4	68	30	12	12	12	98	100	0.5	<2°
5	37	10	7	10	12	98	100	0.7	2-10°
6	36	15	10	12	13	94	90	0.5	2-10°
7	41	15	10	12	13	93	90	0.3	2-10°
8	34	10	18	11	11	99	100	0.4	<2°
9	40	10	7	11	12	99	100	0.3	2-10°
10	48	5	6	13	11	100	100	0.7	<2°
11	45	10	8	13	11	100	100	0.5	<2°
12	50	15	8	15	12	100	100	0.3	<2°
13	49	10	12	13	12	98	100	0.4	<2°
14	51	5	6	13	12	94	90	0.3	<2°
*KSS is the abbreviation of Knee Society Score.

The average time to radiographic union was 12.3 weeks (10-16 weeks), while time to regain walking ability ranged from 11 to 13 weeks (average 11.8 weeks). There was no case of delayed union. Most fractures (12 of 14) achieved clinical and radiographic union at 13 weeks. (Figure 1) In the average of 34 months follow-up, no physeal injury or refracture was detected. No patients developed a valgus deformity of more than 10 degrees. The leg length discrepancies of all 14 patients were less than 0.8 cm (Table 2). No patient exhibited functional deficiency. Nine of 14 patients regained full ROM. The average postoperative KSS and functional score at the latest follow up were 97.5 points and 97.1 points, respectively (Table 2).

Figure 1.

a-d. (a) X-ray AP view of knee with femur right side showing supracondylar femoral fracture in a 5.8-year-old female. (b) X-ray AP view of the same patient 2 months postoperative with external fixation. (c) X-ray AP view of the same patient 3 months postoperative, external fixation removed for one month. (d) X-ray AP view of the same patient 18 months postoperative.

Discussion

Among all the displaced femoral fractures in children, supracondylar fracture accounts for 6.9%.² Smith et al. reported that the most common cause of this type of fracture was fall.² In this study, both fall from height and motor vehicle accidents were the most common causes of pediatric SFF. Undisplaced supracondylar femoral fractures are easy to manage with the application of brace or cast immobilization, while displaced fractures have a relatively high failure rate by closed reduction and immobilization.⁶,⁸,⁹,¹²,¹³,¹⁵ So, operative treatment is indicated for the optimum outcome for such injuries. However, it is a challenging job as surgery can damage the physeal growth plate. According to literature reports, the use of external fixation in pediatric femur fractures is largely limited by its complications. Common complications include soft-tissue injury, knee stiffness, malalignment, refracture, and pin-tract fracture.¹²,¹⁶,¹⁷ Some patients refused to attend school with the external fixator and go back to society later may partly because of psychological impact, which is currently unexplored.¹⁶,¹⁷ In an average follow-up of 34 months, neither refracture nor deep infection occurred in our study, indicating that most reported complications could be avoided with careful surgery and nursing care. Muscular pull or high pressure on pins during the early healing process may lead to micro-movement of pins,¹⁸ imposing negative influence on stability and the union of the fracture. However, early postoperative exercises, including quadriceps strengthening exercise and passive knee ROM exercise, are still considered critical in preventing knee stiffness. To avoid malunion and malalignment, weight-bearing is allowed only after gaining clinical evidence of union. The clinical and radiographic union rates of 100% (14 of 14) in this study indicate that an external fixation is an alternative option for managing supracondylar femoral fractures in children. Both the postoperative KSS score and functional score showed satisfactory results. The average KSS postoperative score was 97.5 points, with a minimum of 93 points. The average KSS functional score was 97.1 points, ranging from 90 to 100 points. These results were comparable to KSS measured by other authors.¹⁴,¹⁹

Other researchers also propose some techniques, including traction, plaster cast, elastic intramedullary pinning, crossed percutaneous pinning, and locking plates. Closed reduction with percutaneous cross pinning is an optimal choice for younger children. As per our previous result, children younger than 3.6 years old could reach satisfactory outcomes through crossed Kirschner wires fixation.²⁰ When it comes to older and obese children, Kirschner wires typically could not support their weights and even might bring complications such as malunion, peroneal nerve palsy, or septic knee arthritis.⁷ Parikh et al. figured out that the strengths of elastic nailing on pediatric supracondylar femoral fractures lie in the shorter hospital stay, being minimally invasive and no need for rigid mobilization or plaster cast after surgery. However, it is challenging to choose a suitable entry point (usually quite close to physis), cross the elastic nails, and avoid injuring the growth plate simultaneously. Therefore, this surgical technique requires orthopedists with more extensive experience.⁸ Plate fixation also showed satisfactory results among adults.²¹ But it usually takes 3 to 4 screws in both sides of the fracture, making it challenging to stabilize short fragments without penetrating physis in young children.⁶,²²–²⁴ Currently reported techniques of plate fixation are only applied to children older than 12 years.⁶,²¹,²² External fixation has been used for specific femoral fractures, and some authors recommended it for the treatment of SFF in adults.¹¹,¹⁸,²⁵–²⁷ To our best knowledge, there was no previous study concerning the application of AO external fixator on SFF in children. The only relevant study was in 2005, in which authors reported the outcomes of only five cases treated with Ilizarov fixator. Therefore, this is the first study focusing on applying the AO external fixator on pediatric SFF, revealing a satisfactory result. However, the age limit for this technique is still uncertain, although the average age in this study was older than other studies treated with Kirschner wires.²⁰

There are still some limitations to this study. The small sample size limits the validity of this study. The absence of matched groups treated with other surgical techniques is another limitation. Although all the patients achieved clinical and radiographic union, follow-up durations still varied. Further studies with more patients and long-term follow-up are necessary. Despite the limitations, the result of this study reveals that external fixation provides satisfactory outcomes and may be an alternative for pediatric displaced supracondylar femoral fracture.

Funding Statement

This work was supported by the National Natural Science Foundation of China (grant number: 81470100).