Trapezial space height measurement after trapeziectomy: a comparison of the use of standard and stress radiographs.

PURPOSE

To assess whether the behavior of the trapezial space under stress after excision of the trapezium and insertion of a K-wire to hold the thumb metacarpal base away from the distal pole of the scaphoid for 4 weeks is improved by either palmaris longus interposition or ligament reconstruction (LRTI).

METHODS

The trapezial space height and trapezial space ratios were assessed on 50 pairs of standard and stress views obtained 1 year after trapeziectomy. Seventeen of the 50 thumbs had simple trapeziectomy, 15 had trapeziectomy plus LRTI and 18 had trapeziectomy with palmaris longus tendon interposition. The reproducibility of these measurements also was assessed.

RESULTS

The 95% limits of agreement for intra- and interobserver differences in the measurement of the trapezial space height were -1 to +1 mm and -2 to +1 mm, respectively. The mean differences between the trapezial heights on the standard and stress radiographs were 1.6 mm (SD, 2.5) for simple trapeziectomy, 1.2 mm (SD, 3.1) for trapeziectomy and LRTI, and 1.2 mm (SD, 2.4) for trapeziectomy with interposition of palmaris longus. The differences between the trapezial space height and trapezial space ratios on the standard and stress radiographs after the 3 different surgeries were not notably different.

CONCLUSIONS

Neither the creation of a suspensory ligament nor palmaris longus tendon interposition, as opposed to the isolated placement of a K-wire across the trapezial void for 4 weeks, alters the behavior of the trapezial space under stress at the 1-year follow-up examination. It is thus appropriate to use standard radiographs at the 1-year follow-up examination to assess and compare the trapezial space after these different techniques of trapeziectomy.