gms | German Medical Science

Objectives/Interrogation: Ostheosynthetic bone fixation implants made from composites of unsintered hydroxyapatite (u-HA) and Poly-L-lactide (PLLA) with bioabsorbability and osteoconductive properties are widely used in orthopaedic surgery. In oral and maxillofacial surgery, it has been reported that the plate was absorbed in about 6 years after surgery, but in our orthopaedic fields, long-term outcomes have not been reported yet. We report long-term outcomes of 8 fingers of 6 patients surgically treated metacarpal fractures using bioabsorbable plates (Super-Fixsorb®?MX40 mesh) for more than 5 years after surgery in our hospital.

Methods: This study included 8 fingers of 6 patients surgically treated metacarpal fractures with bioabsorbable plates (Super-Fixsorb® MX40 mesh) for more than 5 years after surgery in our hospital between March 2009 and September 2017. The average age at the injury was 29.5 years (16-54 years), and the average follow-up period was 6 years and 9 months (5 years and 8 months-8 years and 5 months). Open reduction was performed, and the fracture was temporarily fixed with 1.0 mm-diameter Kirschner wires. We used surgical scissors to cut the bioabsorbable mesh sheet appropriately shape for fixation of the metacarpal fracture and then bent it in hot water bath (68 degrees) to make a one-third or semi-tubular plate. It was placed on the metacarpal bone surface and was fixed with eight to sten bioabsorbable 2.0 mm-diameter cortical screws totally. Clinical endpoints were range of motion for wrist and forearm, grip strength ratio (percentage of the unaffected side), Quick-Disabilities of the Arm, Shoulder, and Hand (Q-DASH) score, bone union on plain X-ray, and resorption status on plain CT.

Results and Conclusions: In all cases, bone unions were achieved without displacement. There were no complications such as infections and aseptic swelling and necrosis in all cases. Q-DASH scores were almost good except for two cases because of the limitation of the range of motion and poor recovery of the grip strength ratio. The plate and screws still remained in 7 years and 2 months after surgery, but, in 8 years and 5 months after surgery, the plate was completely absorbed, and the screws slightly remained in the bone. This study suggests that the process of bioabsorption in metacarpal fractures may take at least about 8 years after surgery, and the absorption rates in the bone may differ from outside the bone.