Minimial clinically important difference values in distal metaphyseal ulnar shortening for ulnar impaction syndrome and assessment of the relationship between level of the osteotomy and bone union time.

Objective: We aimed to define minimal clinically important difference (MCID) values of patient-reported outcome measures (PROMs) for distal metaphyseal ulnar shortening and to assess the relationship between level of the osteotomy and time to bone union.

Methods: 20 patients who had distal metaphyseal ulnar shortening osteotomies due to ulnar impaction syndrome and had at least 6 months of follow-ups were included in this study. The mean follow-up period was 12.3 ± 7.01 months. The PROMs which consisted of patient-rated wrist evaluation (PRWE) and quick disabilities of arm, shoulder, and hand (QDASH) were recorded on the day before the surgery and at follow-up assessments. Grip strength and range of motion were recorded for operated and contralateral wrists at postoperative assessments. Postoperative radiological evaluations of distance of the osteotomy from the distal ulnar articular surface (osteotomy level), the union of osteotomy site; preoperative and postoperative evaluations of styloid-triquetral distance, and ulnar variance were performed using AP wrist x-rays. The MCID values for PRWE and QDASH were calculated using ROC curve analysis.

Results: Mean PRWE and QDASH scores decreased statistically significantly. The mean grip strength of contralateral wrists was higher. Mean ulnar variance decreased, whereas styloid-triquetral distance increased postoperatively. Patients with osteotomy levels of greater than 13.7 mm had a longer time from surgery to bone union. Furthermore, patients with time from surgery to bone union shorter than 7 weeks had an osteotomy closer to the ulnar articular surface. The MCID values for PRWE and QDASH were analyzed and calculated through the ROC curve as 22.25 and 20.45, respectively.

Conclusion: This study has shown us that the osteotomy level affects the time to bone union and an osteotomy closer than 13.7 mm to the ulnar articular surface seems to result in shorter union time. Furthermore, MCID values were defined for PRWE and QDASH as 22.25 and 20.45, respectively.

Level of evidence: Level IV, Therapeutic Study.