Plate Fixation for Unstable Displaced Distal Radius Fractures in Children

Abstract

Background  Distal radius fractures in children are normally treated by plaster immobilization. For displaced unstable distal radius fractures, closed reduction and Kirschner wire (k-wire) fixation can be performed. Disadvantages of k-wire fixation are the need for postoperative plaster treatment for several weeks, which may induce stiffness, and the risks of complications such as tendon irritation and pin-track infections. More invasive volar plate fixation is less popular, although this allows for direct mobilization and enhances anatomical reduction.

Purpose  To present the functional outcomes of pediatric patients treated with volar plate fixation for unstable displaced distal radius fractures.

Patients and Methods  A retrospective cohort study of all consecutive pediatric patients between September 2010 and July 2017 was performed. A total of 26 patients with a median age of 12.5 years were included. The primary objective was functional outcome determined by the Patient-Rated Wrist Evaluation (PRWE) questionnaire. Secondary objectives were range of motion, grip strength, radiological parameters, complications, and incidence of plate removal.

Results  Median PRWE score was 3 after a median follow-up of 29 months. Range of motion and grip strength did not differ significantly between the injured and uninjured wrists. No wound infections were found. Plate removal was performed in 15 patients (58%).

Conclusion  Volar plate fixation for unstable displaced distal radius fractures in children provides good functional and radiological outcomes with minor complications.

Level of evidence  This is a Level IV cohort study.

Fractures of the wrist account for 25 to 36% of all pediatric fractures. ^{1 2 3 4 5} Displaced distal radius fractures are treated by closed reduction and a plaster cast or splint with satisfying results. ⁶ However, redisplacement requiring further intervention is described in up to 39% of pediatric patients treated with closed reduction and casting. ^{7 8}

Although pediatric patients have remodeling potential, ⁹ unstable fractures and fractures with a rotational deformity require reduction and fixation. Kirschner wire (k-wire) fixation is frequently used for distal radius fractures, and elastic stable intramedullary nailing (ESIN) is mostly used for distal forearm fractures. ^{10 11 12 13} A disadvantage of k-wire fixation is the need for postoperative plaster treatment resulting in stiffness of the hand and wrist. Moreover, complications such as pin track infection, tendon irritation, and migration of k-wires are found in up to 38% of cases. ^{8 11}

More invasive volar plate fixation is less popular in pediatric patients. However, volar plate fixation enhances anatomical reduction and allows for functional postoperative treatment. This may lead to less redisplacement, malunions, and improved functional outcome. To the best of our knowledge, only one case study is available that describes volar plate fixation for a displaced distal radius fracture in a 13-year-old child. ¹⁴

The purpose of this study is to present a cohort of pediatric patients treated by volar plate fixation for unstable displaced distal radius fractures. Primary objective was patient-related outcome determined by the Patient-Rated Wrist Evaluation (PRWE) after at least 12 months of follow-up. Secondary objectives were range of motion and grip strength compared to the uninjured wrist, postoperative radiological parameters, complications, and incidence of plate removal.

Patients and Methods

This retrospective observational study was conducted according to the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement guidelines. The setting was a level 2 trauma center specialized in hand and wrist fractures. Data collection was performed after approval from the institutional review board. Through a database search, all consecutive pediatric patients surgically treated for a distal radius fracture (type AO 23r-M/3.1 and 3.2) between September 2010 and July 2017 were screened for inclusion. Pediatric patients were defined as patients between 4 and 17 years of age. The indication for surgery was redisplacement following closed reduction, complete cortical displacement, or the inability to reach an acceptable closed reduction. An acceptable closed reduction was defined as follows: for children younger than 12 years, acceptable angles were volar or dorsal tilt < 25 degrees and ulnar or radial angulation < 10 degrees. For children older than 12 years, acceptable angles were volar or dorsal tilt < 10 degrees and ulnar or radial angulation < 10 degrees. Patients treated with ESIN, k-wire, and closed reduction were excluded, and only patients treated with volar plate fixation were included. Some patients were scheduled for k-wire fixation, but when an acceptable closed reduction could not be reached, open reduction and volar plate fixation was performed. These patients were also included in the study. Medical records were screened for complications.

The primary objective was the PRWE questionnaire after at least 12 months of follow-up. The PRWE score ranges from 0 to 100, with 0 indicating no pain and no functional impairment. ¹⁵ Secondary objectives were range of motion and grip strength compared to the uninjured wrist, postoperative radiological parameters, complications, and incidence of plate removal.

Patients or their parents were contacted by telephone to visit the outpatient clinic to fill out the questionnaires and for physical examination. When the patient was not reached by three separate attempts, they were considered as lost to follow-up. When patients were not able to visit the outpatient clinic, the PRWE questionnaire was sent by mail. Missing scores were due to impossibility to reach the patient or inability of the patient to visit the outpatient clinic.

Clinical Evaluation

Range of motion was measured using a goniometer. The parameters included radial and ulnar deviation, pronation and supination, and dorsal and palmar flexion. Grip strength was measured using a Baseline Hydraulic Hand dynamometer (Fabrications Enterprises Incorporated, White Plains, NY). This was performed three times, and an average of these measurements was used. Both range of motion and grip strength were measured for the injured and uninjured sides.

Radiographic Outcome

Standard radiographs were performed during emergency department visit, intraoperative by fluoroscopy and at 6 weeks postoperative follow-up. Further radiographs were performed on indication. Postoperative x-rays of the wrist were assessed independently by J. E. and C. S. for radiological outcome. A mean score was calculated for each radiological parameter. When the measured angels were in excess of 5 degrees, N. S. was contacted to assess the radiograph as well. The following radiographic parameters were determined: radial inclination, radial height, ulnar variance, carpal alignment, palmar tilt, and dorsal tilt. As the wrist was incompletely ossified, ulnar variance was measured according to that described by Hafner et al. ¹⁶ The distance between the most distal point of the ulnar metaphysis to the most distal point of the radial metaphysis was determined. Carpal alignment was determined using the perpendicular method, in which one line along the inner rim of the volar cortex of the radius and one perpendicular line to the center of the capitate. The carpus is aligned when the line along the inner rim transects the center of the capitate. ¹⁷

Operative Technique

Before surgery, informed consent was obtained from caregivers of all patients. All patients received general anesthesia and antibiotic prophylaxis with cefazolin (50 mg/kg, maximal 2 g). A tourniquet was inflated. The arm was extended in a supinated position on a fluoroscopically translucent table. The surgical approach was performed through a modified Henry approach. ^{18 19} Next, the pronator quadratus muscle was detached in an L -shaped pattern, remaining attached on the ulnar side, and released subperiosteally from the radius. Following anatomical reduction of the fracture, a locking compression distal radius plate (DePuy Synthes, Zuchwil, Switzerland) was used. When the radius had a small diameter, mostly the T - and L -shaped dorsal plates were used for volar fixation. ( Fig. 1 ) The positioning of the most distal screws proximal from the epiphysis was verified with fluoroscopy. The pronator quadratus muscle was not repaired to the radius. The skin was closed with soluble subcutaneous stitches. A pressure bandage was applied for 48 hours, and patients were allowed immediate postoperative mobilization.

Fig. 1.

X-ray of ( A ) preoperative and ( B ) postoperative volar plate fixation.

Statistical Analysis

Descriptive statistics were performed to show patient characteristics and surgical details. Normally distributed data were reported as mean and standard deviation (SD), and nonnormally distributed data were reported as median with interquartile range (IQR). Normality was analyzed by plotting the data distribution in a histogram. Categorical data were presented as absolute frequency and percentage. Paired Student's t -test was used to compare range of motion and grip strength of the injured side compared to the uninjured side.

Results

Between September 2010 and July 2017, a total of 123 pediatric patients were surgically treated for unstable distal radius fractures; 91 were treated by k-wire fixation and 6 were treated by ESIN.

A total of 26 pediatric patients were treated by volar plate fixation. Median age was 12.5 (IQR: 9–15) years at the time of surgery. Eight patients were female. Median follow-up was 29 months (IQR: 18–38). A total of 19 (73%) patients completed the PRWE questionnaire and 16 patients (62%) visited the outpatient clinic for physical examination. In total, 7 (27%) patients were lost to follow-up, and for 10 (48%) patients, no physical examination was possible.

Outcome

Median PRWE score was 3 (IQR: 0–10). Range of motion and grip strength are presented in Table 1 . Postoperative mean radiological parameters were a radial inclination of 21 degrees (SD 4), radial height of 9 mm (SD: 2), and an ulnar variance of negative 2 mm (SD: 2). Twelve patients had palmar tilt (mean: 7 degrees; SD: 4) and fourteen patients had dorsal tilt (mean: 5 degrees; SD: 3). Carpal alignment was achieved in 22 patients, with a median of 0 mm (IQR: –1 to 0.3).

Table 1. Clinical outcome.

Range of motion	Injured side	Uninjured side	Difference	p -Value
Radial deviation	18 (5)	18 (5)	–	–
Ulnar deviation	28 (5)	32 (16)	4.3 (15)	0.3
Pronation	85 (0)	85 (0)	–	–
Supination	84 (3)	84 (2)	0 (2)	1
Dorsal flexion	79 (5)	78 (5)	0.6 (3)	0.4
Volar flexion	81 (5)	81 (4)	0.7 (2)	0.1
Grip strength (kg)	26 (9)	27 (10)	0.6 (4)	0.5

Note: All values are presented as mean (standard deviation).

Two patients had a complication involving postoperative stiffness of the wrist. Both were successfully treated with physical therapy. No wound infections were found after plate fixation and plate removal.

Plate removal was performed in 15 patients, mostly due to routine removal ( n  = 9). Routine removal was performed at the discretion of the surgeon after 6 months to prevent possible future plate-related problems. In the remaining six patients, plate removal was performed because of pain or the patient's wish for removal. Median time to plate removal was 8 months (IQR: 5–8).

Discussion

Surgical treatment of distal radius fractures in children is mostly performed by closed reduction and k-wire fixation. Disadvantages of k-wire fixation include the need for postoperative plaster treatment for several weeks, which may induce stiffness, tendon irritation, or rupture, and pin-track infections. Unfortunately, no exact rates of tendon rupture after k-wire fixation have been reported. ⁸ More invasive volar plate fixation is less popular, although this allows for direct mobilization and enhances anatomical reduction. This may lead to less redisplacement, malunion, and improved functional outcome.

This cohort of 26 pediatric patients with displaced unstable distal radius fracture treated with a volar plate fixation was analyzed for postoperative functional outcomes. A good functional outcome, determined by the PRWE, was found. Moreover, no wound infections were found. Radiological outcome was determined on postoperative radiographs, which showed good results.

A disadvantage of volar plate fixation is the possible need for hardware removal. Fifteen (58%) patients underwent plate removal. No complications occurred following removal. In 23% of the patients ( n  = 6), plate removal was performed because of plate-related complaints. Complaints were pain ( n  = 5) and stiffness ( n  = 1). All other procedures ( n  = 9) were performed on routine basis. However, there is no evidence for the need for routine plate removal, and the optimal timing for plate removal is not known. Some authors even advise not to remove plates on routine basis since the advantages of removal and interference of growth are largely theoretical. ²⁰ As concluded by Schmittenbecher, implant removal should be individually assessed since this is a more extensive procedure and there is a lack of evidence to support routine removal. ²¹

In contrast to the high complication rate of 16 to 38% for k-wire fixation (superficial infection, skin irritation, and migration of wires), only two complications of temporary stiffness ( n  = 2; 8%) were found in our cohort following volar plate fixation. ^{8 11}

Since volar plate fixation of pediatric distal radius fractures is rare, no appropriate plate is available. Therefore, we noticed variable adjustments of plates to get these to match the radius. Further development of plates may be needed when plate fixation in pediatrics is performed more frequently.

The strength of this cohort study is its relatively long median follow-up of 29 months, providing valuable data on outcome, complications, and plate removal.

However, this study also has some limitations. First, this is a retrospective cohort study with all its known and unknown forms of bias. Therefore, the registration of complications can be an underestimation. However, all medical records were extensively screened, and all patients followed a strict follow-up protocol postoperatively. Secondly, although the PRWE score is not validated for children, this score was used to determine functional outcome since no other validated pediatric score in trauma is available. We presume this outcome is accurate since the questionnaire was completed with the help of one of the parents when necessary.

In conclusion, volar plate fixation for displaced distal radius fractures in pediatric patients provides good functional and radiological outcomes with minor complications.