Evaluation of indicators for distal radioulnar joint instability after a distal radius fracture in adults

DRUJ instability confirmed by physical examination (stress test or clunck test

positive) and CT-scan.

Static clinical DRUJ instability will be diagnosed with the stress test. The

test is positive if there is more anterolateral movement of the ulna, relative

to the stabilized radius than compared to uninjured wrist. Dynamic clinical

DRUJ instability will be diagnosed by the clunck test. During passive rotation

of the wrist the ulna is compressed to the radius. This test is positive if a

clunck is palpable for the subject.

DRUJ instability will be evaluated on the CT-scan of both wrist in maximal pro-

and supination as described by the subluxation ratio [46]. Two lines

perpendicular to a line connecting the volar and dorsal margins of the sigmoid

notch are drawn from the volar and dorsal margins of the sigmoid notch. The

ratio of the length of CD to that of AB is calculated. (Fig. 1). Normal values

are 0.2, 0.01 and -0,13 in maximal pronation, neutral and maximal supination

respectively.

o Wrist function

Physical examination will include determination of restricted or blocked

pronosupination, ulnar and radial deviation, dorsal and palmar flexion using a

goniometer, and grip and pinch strength using a JAMAR® Hydraulic Hand

Dynamometer and JAMAR® Hydraulic Pinch Gauge. For each patient maximal range

of motion in any direction will be tested three times and measured by a

goniometer. Both maximal grip and pinch strength, with the elbow in 90dgrs of

flexion and shoulder in neutral position will be measured three times. The

average of the three measurements will determine function. Loss of function is

defined as 10% or more decrease in arc of motion (pro- and supination,

ulnar-radial deviation and palmar-dorsal flexion) compared to the uninjured

side.

o Malunion

Malunion is defined as the difference in radial length, radial inclination and

volar tilt as confirmed on the CT, comparing the injured with the uninjured

wrist. More than 10% difference is considered malunion.

o Pain



Pain is indicated on a 100-point visual analogue score. Patients will be asked

to indicate their pain four times for each wrist; first time without

loadbearing, the second time imagining bearing a 10kg weight. Both in rest and

movement.



o Subjective health assessment



Subjective assessments of quality of life and wrist function will be obtained

using the Mayo modified wrist score [5], Gartland and Werley score [15],

Disabilities of the Arm, Shoulder and Hand (DASH) [23] and Short Form-36

(SF-36) [25]. Patients can fill them out at home or during their visit.



o Associated unknown traumatic changes

Associated unknown traumatic changes (additional ligamenteous or osseous

changes) on CT-scan are defined as traumatic changes not mentioned on the

existing investigations, nor intentionally treated during follow-up.

o Complications

Complications are defined as adverse medical responses after the treatment of

the distal radius fracture during follow-up.

o Radiocarpal and DRUJ arthrosis

Arthrosis is defined as loss of cartilage and will be scored on CT according to

the classification of Knirk and Jupiter. [32]

The kappa measure (*) and intra-class correlation coefficient will be computed

to estimate inter-observer and intra-observer agreement for CT parameters. [10,

33, 56, 61] The values will be interpreted using the guidelines proposed by

Landis and Koch [33]: values of 0.01 to 0.20 indicate slight agreement; 0.21 to

0.40, fair agreement; 0.41 to 0.60, moderate agreement; 0.61 to 0.80,

substantial agreement; and more than 0.81, almost perfect agreement. Zero

indicates no agreement beyond that expected due to chance alone, * 1.00 means

total disagreement, and + 1.00 represents perfect agreement [33, 56].