Madelung's deformity: quantitative assessment of x-ray deformity.

Purpose: To evaluate 5 defined measurement techniques that are applicable to x-rays of Madelung's deformity: ulnar tilt, lunate subsidence, lunate fossa angle, palmar tilt, and palmar carpal displacement. The measurements rely on the longitudinal axis of the ulna and the carpal bones to determine drawing lines and avoid the distorted distal radius and its deformed lunate fossa. The reliability and reproducibility of the measurements is determined.

Methods: Forty-eight sets of posteroanterior and lateral x-ray views of the wrist of subjects with the clinical diagnosis of Madelung's deformity were measured by 4 raters. Each rater made the 5 defined measurements on each pair of x-rays. Pairs of raters were compared for reliability using the Pearson correlation coefficient and Lin's concordance correlation coefficient. Two raters repeated the 4 reliable measurements a minimum of 6 months after the first measurements. Each rater's results were compared for reproducibility using Lin's concordance correlation coefficient.

Results: Ulnar tilt and lunate subsidence have excellent reliability and reproducibility. Palmar carpal displacement has acceptable reliability and reproducibility. Lunate fossa angle has borderline reliability but excellent reproducibility. Palmar tilt has poor reliability.

Conclusions: Ulnar tilt, lunate subsidence, and palmar carpal displacement, as defined, are considered reliable and reproducible measurements for quantifying the severity of Madelung's deformity on x-rays. Lunate fossa angle is not sufficiently reliable for comparing preoperative and postoperative wrists but may prove useful in establishing an early diagnosis. Palmar tilt is not measured reliably on a lateral x-ray because of the superimposition of multiple structures on a lateral x-ray and the absence of the volar part of the lunate fossa in patients with severe Madelung's deformity. Advanced imaging techniques are needed to delineate the deformity of the distal radius in a lateral projection.