ABSTRACT
PURPOSE: To evaluate the interstitial and appositional growth of greater trochanter post-screw apophysiodesis in Legg-Calve-Perthes (LCP) disease. MATERIALS AND METHODS: A total of 17 patients, who were diagnosed with LCP and underwent greater trochanter screw apophysiodesis and metal removal between December 2003 and December 2012, and were followed-up for at least 4 years, were selected. Anterioposterior radiologic images were taken in each process of apophysiodesis, metal removal, and last follow-up. From such images, articulotrochanter tip distance (ATD), trochanter tip-screw distance (TSD), trochanter tip-trochanter lower margin distance (TLD), and screw-trochanter lower margin distance (SLD) were measured. Appositional growth and greater trochanter growth rates were compared using paired t-test, independent t-test, and correlation analysis. RESULTS: The average ATD of the affected and unaffected sides was 14.2 and 16.8 mm, respectively at apophysiodesis and 9.2 and 14.8 mm at the last follow-up, with a significantly greater decrease observed on the affected side the unaffected side (p=0.030). TLD of the affected side during the follow-up increased 11.0 mm, from an average of 30.8 to 41.8 mm, while the un-affected side increased 14.3 mm, from an average of 26.7 to 41.0 mm. The growth of greater trochanter after the operation in the affected side was 76.7% of that in unaffected side. The ratio of TLD of the affected side to the unaffected side was significantly reduced, from 1.15 to 1.02 (p=0.014) at the final follow-up. TSD was significantly increased from 4.5 to 14.4 mm at metal removal (p < 0.001) and increased to 17.0 mm at the last follow-up. Moreover, the ratio of TSD to SLD was significantly increased from 0.20 to 0.74 at metal removal (p < 0.001) and increased to 0.84 at the final follow-up. CONCLUSION: The results of this study showed that screw apophysiodesis can suppress the overall growth, but not the appositional growth of the greater trochanter. Therefore, screw apophysiodesis may not be a good procedure to inhibit the growth of greater trochanter.