Essential Insights On First MPJ Implant Revision
Implants have been documented in the literature and surgeons have utilized implants over the past 50 years for the treatment of a variety of conditions including hallux rigidus, hallux valgus, osteoarthritis and rheumatoid arthritis.1,2 Total joints were originally designed to function as joint spacers to decrease pain while maintaining motion and joint alignment.1,3 Currently, a variety of products attempt to provide these characteristics. These products include silastic, polyethylene-on-metal and metal hemiarthroplasty implants. Surgeons have implanted over 2 million hinged great toe joint implants in the United States.
However, there has been minimal research published on the long-term results of these implants.2 The current literature has documented an average follow-up assessment from 24 months to 13 years and patient satisfaction rates ranging from 67 to 90.7 percent.3-10 Authors have also described revisional rates for various implants ranging from 5 to 74 percent.2-10 The trend for doing total joint replacements in foot and ankle surgery continues and with the varying degrees of success, it is inevitable that many physicians will be faced with a failure at some point during their career.
Revisional surgery including failed first metatarsophalangeal joint (MPJ) implants and other complex cases make up a large portion of the surgical cases at the Foot and Ankle Institute of Western Pennsylvania. With that being said, we hope to lend some insight on what we feel are some essential points that are necessary for the successful treatment of a failed first MPJ implant.
Understanding The Reasons For Implant Failure
Before attempting to revise a failed implant, it is imperative to understand the reasons behind the failure itself. One of the most commonly known causes of failure with silastic implants is foreign body synovitis.3,11 There have been documented reports of embedded silicone in adjacent bone and soft tissue, as well as cases of patients developing lymphadenopathy related to this silicone debris.10 In 2002, Ghalambor, et al., described this same phenomenon in identifying metal debris in affected bone and synovium from two failed titanium single stem implants.12
Lucency surrounding the implant identified on radiographs is a well documented reason for failure.6,8,10,13,14 However, one must determine the clinical correlation of implant-related lucency. In 1997, Lemon and Pupp demonstrated radiographic deterioration with various first MPJ implants but they failed to show correlation with the patient’s satisfaction.4,6,8,9,10,13 Other radiographic changes can include osteophyte production, subsidence of the implant, malalignment of implant, implant fracture, cortical fracture, lesser metatarsal fracture, cystic bone formation, osseous lucency, bone resorption and cortical thinning.4,6-8,9,15
Clinical symptoms relating to implant failure that may lead to first MPJ revision surgery include transfer lesions, chronic swelling and pain, decreased range of motion, recurrence of deformity, shortening of the first ray, instability in the first ray, hallux extensus, sesamoidal tracking and infection.3-5,12-14,16 In 1994, Papagelopoulos, et al., noted that 44 percent of all their postoperative patients had continued pain.4 These authors also related a significant correlation of age and implant failure. Researchers have found that increased activity level, younger patients and systemic diseases (including rheumatoid arthritis) all correlate with implant failure.4,6,10,14
The majority of patients with implant failure at our institution have presented with chronic pain and edema with hallux malalignment (including cock-up hallux, hallux varus, shortened first ray, and an unstable first ray), painful range of motion, and lesser metatarsalgia. Patients presenting with these symptoms have ranged from 49 to 72 years old with implants ranging from total joint metallic implants to hemi-implants. Radiographically, we have noted lucency surrounding the implant, lytic changes and subsidence or malalignment of the implant.