Immediate and long-term results of unsintered hydroxyapatite and poly L-lactide composite sheets for orbital wall fracture reconstruction

Bone defect reconstruction in orbital wall fractures with absorbable alloplastic such as the unsintered hydroxyapatite and poly L-lactide composite (u-HA/PLLA) system is gaining popularity. The u-HA/PLLA material has osteoconductive and osteosynthetic properties. However, quantitative, long-term outcome data after the use of u-HA/PLLA for orbital wall fractures are lacking. We retrospectively analyzed 115 patients who underwent surgical repair of orbital wall fractures with a u-HA/PLLA sheet from 2011 to 2016. A chart review was performed, and the time-dependent changes at fracture sites were assessed by imaging. The immediate postoperative and the latest follow-up bony orbital volumes of the affected side were compared. Seventy patients were eligible for this study (mean age, 44.6 ± 22.1 years; 48 men and 22 women; mean follow-up period, 29.7 ± 12.8 months). Except for one case of hematoma, there were no postoperative wound complications. Of the 70 patients, 10 had postoperative diplopia and 2 had enophthalmos; these conditions were presumably caused by the extension and severity of the fracture. Satisfactory reduction in the entire orbital wall, without pathological changes, was demonstrated. There were no significant differences in the mean bony orbital volumes of the affected side immediately after surgery (24.774 ± 3.092 cm3) and at the latest follow-up (24.749 ± 3.205 cm3) (p = 0.756). The u-HA/PLLA sheet is useful for orbital wall fracture reconstruction because of its desirable handling characteristics, initial mechanical strength, long-term maintenance of structural stability, radiopacity, and few associated complications. Future randomized controlled trials need to be performed to compare u-HA/PLLA with other conventional materials.