The ultimate treatment goal in fractures of distal radius is a wrist that has sufficient pain-free motion and stability to permit vocational and avocational activities without the propensity for future degenerative changes.
There are certain radiological parameters that would help to achieve these goals.
Intra -articular Incongruity
Congruity of radiocarpal joint remains the most significant radiological parameter for both functional outcome and future degenerative changes.
There is no universal agreement though on how much step in articular step is acceptable because studies have documented increase in stress with step-offs as small as 1 mm. Other studies report worsening of functional outcome if the step is beyond 2mm.
The change in palmar tilt increases the tension on the palmar and dorsal radioulnar ligaments resulting in an increased load required for forearm rotation. Acceptable limit is up to neutralization of the tilt.
Studies have indicated a strong correlation between radial length and loss of strength. More than 2 mm of radial shortening has been reported to result in symptomatic loss of strength. Acceptable radial length is within 2 to 3 mm of the contralateral wrist.
A correlation between decrease in radial inclination and decreased grip strength has been documented and there is increased risk of degenerative changes.Less than 5 degrees of loss is acceptable.
This indicates ligamentous injuries. Some degree of lateral scapholunate angle widening due to palmar flexion of the scaphoid may be acceptable, it appears that a dorsiflexed lunate is associated with a worse outcome.
There is as yet no defined threshold for this angle; however, greater than 25 degrees has been correlated with a worse outcome .