Purpose
We developed a new type of unfired hydroxyapatite/poly (L-lactic acid) (u-HA/PLLA) screw with an innovative shape and applied it clinically. This study aims to clarify the clinical outcomes of foot and ankle fractures treated with the new u-HA/PLLA screw.
Methods
Seven patients who had injured foot and ankle fractures were treated with new type u-HA/PLLA screws between June 2021 and March 2022, and all patients were followed up for at least six months. The fracture types included five ankle fractures (3 SER type, 1 PER type, and 1 PAB type in the Lauge-Hansen classification), one talus body fracture, and one fracture of the lateral process of the talus. In ankle fractures, the fibula fracture was fixed with a titanium plate. The medial and posterior malleolar fractures or syndesmosis injuries were treated with new type u-HA/PLLA screws. Clinical outcomes were evaluated using the JSSF hindfoot scale in the final survey, and the time to bone fusion was investigated from X-ray and CT after surgery. In addition, the pre-and postoperative distance between bone fragments, the presence of screw dislocation and loosening, and the presence of screw breakage were evaluated using CT after surgery to investigate the performance of the new type screw.
Results
The mean age at surgery was 64 years (range, 43-81 years), and the mean follow-up duration was 12 months (range, 7-15 months). Bone fusion was observed in all cases, and the mean duration was 14 weeks (range, 9-24 weeks). The mean JSSF hindfoot scale at the final survey was 90 points (72-100 points). The mean distance between bone fragments improved significantly (p=0.0004) from 2.0 mm to 0.3 mm postoperatively. No screw dislocation, loosening, or breakage was observed throughout the follow-up period.
Conclusion
In the short term, there were no apparent failures in the clinical use of the new u-HA/PLLA screws for foot and ankle fractures. On the other hand, medium- to long-term results and indication criteria are unknown, and continued follow-up is required.