Modified Z-plasty(N-plasty) was performed on patients with snapping hip syndrome arising from the iliotibial band, whose pain and clicking sensation persisted despite conservative treatment. The effectiveness of this new technique was evaluated from an analysis of the clinical results.

Among the 44 patients (58 cases), who still felt pain and reported a clicking sensation during daily life despite hospitalization for at least 2 months from January 1999 to August 2007, this study evaluated a total of 25 patients (30 cases) who underwent N-plasty and were followed up for more than 6 months. All patients were male with a mean age of 21 years. The initial symptoms developed an average of 11.5 months prior to the hospital visit (range, 1 month to 4 years). The affected side was the right side in 6 cases and the left in 10. Among 9 patients affected bilaterally, 5 patients (10 cases) underwent surgery on both sides, 1(1 case) on the right side, and 3 (3 cases) on the left side. Surgery was defined as being successful when at 6 months after surgery the patient could carry out their daily activities and exercise without a clicking sensation or pain. Failure was defined when either a clicking sensation or pain was present.

The posterior portion of the iliotibial band was thickened by an average of 8.9 mm (range, 6~14 mm). A tenotomy of the iliotibial band lengthened the band by an average of 25 mm (range, 20~35 mm) and narrowed the width of the iliotibial band anterior to posterior. Twenty-nine cases (97%) had a successful outcome after surgery. Recurrence occurred in 1 case. After additional surgery, the recurrence was found to be due to the insufficient length of the tenotomy.

N-plasty performed in external type snapping hip patients is an effective method with a high success rate.