Factors Responsible for Redisplacement of Pediatric Forearm Fractures Treated by Closed Reduction and Cast: Role of casting indices and three point index

Abstract

Background: Pediatric forearm fractures are still considered an enigma in view of their propensity to redisplace in cast. The redisplacement may be a potential cause for malalignment. We prospectively analyzed the role of risk factors and above casting indices in predicting significant redisplacement of pediatric forearm fractures treated by closed reduction and cast.

Materials and methods: 113 patients of age range 2-13 years with displaced forearm fractures, treated by closed reduction and cast were included in this prospective study. Prereduction and postreduction angulation, translation, and shortening were noted. In addition, for distal metaphyseal fractures, obliquity angle was noted. In postreduction X-ray, apart from fracture variables, casting indices were also noted (cast index [CI] for all patients with three-point index [TPI] and second metacarpal radius angle in addition for distal metaphyseal fractures). In 2^nd week, X-rays were again obtained to check for significant redisplacement. These patients were managed with remanipulation and casting or were operated if remanipulation failed. Comparison of various risk factors was made between patients with significant redisplacement and those which were acceptably reduced. A subgroup analysis of patients with distal metaphyseal fractures was done.

Results: Thirteen (11.5%) patients had significant redisplacement; all of them required remanipulation. No association with respect to age, sex, level of fracture, side of injury, surgeon's experience, number of bones fractured, and injury to definitive cast interval was seen. The presence of complete displacement in any of the plane in either of the bones was seen to be highly significant predictor of redisplacement (P < 0.001). Postreduction angulation more than 10° in any plane in either of the bone and fracture obliquity angle in distal metaphyseal fracture also had a highly significant association with redisplacement. There was a significant difference in the mean values of all three casting indices assessed. TPI was the most sensitive casting index (87.5%).

Conclusions: Conservative management with aim of anatomical reduction, especially in patients with complete displacement, should be the approach of choice in closed pediatric forearm fractures. Casting indices are good markers of quality of cast.

Keywords: Cast index; Pediatrics; bone; casting indices; closed reduction and cast; forearm; fracture; pediatric forearm fractures; plaster cast; redisplacement; second metacarpal radius angle; three-point index.

Figure 1

Diagrammatic representation of fracture obliquity angle was calculated by maximum fracture-line angle in either the transverse or the sagittal plane - i.e., the lines between the fractured medial and lateral cortices on anteroposterior view (a) and those between the fractured dorsal and volar cortices on the lateral view (b) and the larger angle was selected as the fracture obliquity angle

Figure 2

Clinical photographs showing the technique of traction and casting. (a) Traction technique using two assistants. Note that fifth finger has been left free. (b) Uniform cotton wool padding applied. Note extra padding over wrist and olecranon to avoid pressure sore. (c) Application of below-elbow component of the cast with interosseous molding. (d) Extension of the cast to above elbow level with posterior humeral molding. (e) Well molded above elbow cast with 90° flexion at elbow in midprone position

Figure 3

A line diagram showing that the CI is inner diameter of cast on lateral view (at fracture site)/inner diameter of cast on AP view (at fracture site). It is determined by dividing the sagittal cast width (x) by the coronal cast width (y) at the fracture site (CI = x/y). Cut off value <0.81. CI = Cast index, AP = Anteroposterior

Figure 4

Diagrammatic representation of TPI. It is TPI = ([a + b + c]/d) + ([e + f + g]/h). Cut off value <0.8. TPI = Three point index, AP = Anteroposterior

Figure 5

Diagrammatic representation of SMRA. It is angle between second metacarpal and long axis of the radius in AP view. Cut off value >0°. SMRA = Second metacarpal radius angle, AP = Anteroposterior

Figure 6

Flowchart showing the management protocol of the study, A/E= Above elbow, POP= Plaster of Paris, GA= General anaesthesia

Figure 7

X-ray of both bones forearm of a twelve year old boy, anteroposterior and lateral views showing (a) diaphyseal fracture of both bones Prereduction, (b) postreduction CI = 0.79, (c) at second week, fracture was acceptably reduced, (d) at 6^th week post injury shows bony union. CI=Cast index