Ultrasound-guided injection and the pie crust technique for the treatment of symptomatic bipartite patella

This study aimed to investigate the results of a new treatment procedure (ultrasound-guided injection and the "pie crust" technique for lengthening of capsular tendon structures) for symptomatic bipartite patella.

We retrospectively investigated patient outcomes following the treatment of symptomatic type III bipartite patella with our new technique. Fifteen knees in 14 boys (mean age, 13.0 ± 1.7 years) were included. The procedure involved the injection of 1% lidocaine (2 mL) and triamcinolone acetonide (5 mg) between the patella and fragment. We then punctured 10 sites from one skin puncture to extend lateral capsular tendon structures. The patients were clinically assessed using the Victorian Institute of Sports Assessment (VISA) score before and 1 week, 1 month, and 3 months after the procedure. Patients were also evaluated for complications.

The average VISA score was 45.7 ± 4.7 before treatment, 70.6 ± 7.3 at 1 week post-treatment, 84.4 ± 16.6 at 1 month post-treatment, and 88.6 ± 18.3 at 3 months post-treatment. The VISA score improvement from before the procedure to 1 week after the procedure was significant (P < 0.01). There were no complications in any of the patients, who returned to sports at a mean of 4.2 ± 2.1 weeks after the procedure. However, two patients (three knees) had poor results and could not return to action; thus, they underwent surgical treatment 4 months after the ultrasonographic procedure.

This novel method is a potential treatment option for the management of symptomatic bipartite patella in outpatient clinics.