The standard of treatment for most fractures of distal radius remains closed reduction and immobilization. It is essential to discern which fracture patterns are more susceptible to failure so that surgical intervention can be considered when an acceptable reduction cannot be achieved or has a risk of secondary displacement. A correlation between the severity of the primary displacement, carpal malalignment & an expectant loss of reduction over a given time period when treating distal radius fractures with cast immobilization is reported. Recently, studies have attempted to classify carpal malalignments associated with displaced distal radial fractures based on Effective radio-lunate flexion (ERLF) into: midcarpal with ERLF < 25 and radio-carpal malalignment with ERLF > 25.

The aim of this study was to assess the frequency of carpal instability as a concomitant lesion to fractures of the distal radius, delineate further various factors including associated carpal malalignment based on ERLF that are predictive of instability based on a timeline of early (I week) and late failure (six weeks). Radiographic alignment parameters were compared using paired t-tests and then also analysed in a multiple logistic regression analysis. There was a significant improvement in all the parameters measured (p< 0.01) with mean correction falling within acceptable limits. Early failure group: Regression analysis showed high correlation between the severity of axial shortening before reduction and at six weeks. Age, gender, presence of dorsal comminution and ulnar styloid fracture, initial dorsal angulation and flattening of radial angle were unreliable in predicting early failure at one week. The incidence of failure was significantly correlated to radiocarpal malalignment pattern in post reduction radiographs (ERLF> 25) at one week when analysed independently or in combination(p< 0.01). In the late failure group:Radial shortening, dorsal tilt, presence of dorsal comminution & ERLF > 25 to be significant predictors of adverse radiological outcome. Age, Gender, flattening of radial angle, ulnar styloid fracture, for secondary displacement when analyzed independently or in combination were not found to be significant predictors of failure at 6-week. The incidence of failure was significantly correlated to radiocarpal malalignment pattern in post reduction radiographs (ERLF> 25) and at 6weeks when analysed independently or in combination.(p< 0.01) Our study reaffirms the need to attention to initial fracture characteristics and highlights the importance of radiocarpal instability pattern on post reduction radiographs as a predictor of late instability & anticipate the radiological outcome. This would allow the surgeon to inform the patient of chance of success with closed treatment and alternative treatment options.