First Metatarsophalangeal Joint Space Area Decreases Within 1 Month After Implantation of a Polyvinyl Alcohol Hydrogel Implant: A Retrospective Radiographic Case Series.

In 2016, the U.S. Food and Drug Administration approved the first and only polyvinyl alcohol hydrogel implant for the treatment of hallux rigidus. The implant functions as a bumper to maintain first metatarsophalangeal joint space to prevent contact of the phalangeal base with the first metatarsal head. Short-term and intermediate outcomes with this implant have reported positive outcomes with no radiographic outcomes of implant wear or subsidence. We performed a retrospective radiographic review of 27 consecutive patients who received the implant and measured preoperative and postoperative joint space area (JSA). We found a significant improvement in JSA (p < .001) between the preoperative JSA and JSA at the first postoperative visit at 1 to 2 weeks. We also found a significant decrease in JSA (p < .001) between the first postoperative visit and the second postoperative visit at 5 to 12 weeks. This information could have further implications for implant design as well as how we can better achieve functional improvements in the first metatarsophalangeal joint in patients with hallux rigidus.