Toe Fusion Alternatives Gaining a Firm Market Foothold

Earlier this fall, Arthrosurface debuted its new BOSS Toe Fixation System, a product that improves stabilization in a first metatarsal with a distal bone void. The U.S. Food and Drug Administration-cleared system was developed to fill the current void of available treatments for failed synthetic implants, and provide an alternative to toe fusion.

The incidence of first metatarsalphalangeal joint (MTPJ) osteoarthritis has prompted the development of long-term solutions that relieve pain and preserve the foot’s natural motion. The BOSS Toe Fixation System, used in conjunction with Arthrosurface’s existing line of HemiCAP DF implants and ToeMotion systems, offers immediate rigid fixation in cases with metaphyseal bone loss and is designed to stabilize the joint while also maintaining the toe’s length and mechanical axis.

Carl T. Hasselman, M.D., co-designer of the Arthrosurface ToeMotion Arthroplasty System, spoke to ODT about motion-preserving, non-fusion alternatives for MTPJ osteoarthritis and other toe conditions.

Michael Barbella: What are some current alternatives to toe fusion?
Dr. Carl T. Hasselman: Current alternatives to fusion include interpositional arthroplasty, where a piece of tendon is placed between the metatarsal head and proximal phalanyx to act as a cushion. This often can alleviate some of the pain from arthritis but does not always improve motion. The use of silastic implants has been discouraged by most, as the function of the toe is diminished and push-off strength is compromised. The HemiCAP and ToeMotion implants have become popular for restoration of motion and elimination of pain in many people with early and advanced arthritis.

Barbella: Why are the alternatives chosen more often than toe fusion?
Dr. Hasselman: Fusion of the first metatarsal-phalangeal joint (MTPJ) results in complete loss of motion of the joint. Many people who run, do yoga, or are active do not like a fusion, as they notice the stiffness of the big toe with these activities. Women who wish to wear more stylish shoes or high heels find the fusion does not allow for comfortable shoe wear with these products. Many patients who do get a fusion are not even aware of alternative options as their surgeon does not discuss them with their patients. There is not much marketing for joint sparing techniques and so they choose the fusion not knowing there are alternatives. Although fusion is a good option in men who do heavy manual labor and others with certain medical conditions, it is not always the best option for all people.

Barbella: Who are the best candidates for reverse toe fusion (unfusion)? In whom is fusion the better option?
Dr. Hasselman: The ideal candidate for unfusion is the patient who is unhappy with their fusion because the stiffness has limited their ability to wear the styles of shoes they like or their stiffness limits the type of activities they want to do. They usually complain of pain at the next joint in the great toe or have pain in the metatarsal due to increased stress placed on this region from the fusion. Their sesamoids cannot be involved with the fusion so they can have increased range of motion after the unfusion technique. The unfusion person cannot have certain medical conditions such as rheumatoid arthritis or gout and must understand the procedure can increase their motion but never return it to normal. The ideal patient for a fusion is a male who performs heavy manual labor and does not like to run or play sports that require running. Typically, shoe wear for men has a wider toe box with a stiffer sole, which compensates for the lack of motion of the great toe. Also, persons with rheumatoid arthritis or gout typically require fusion to prevent continued arthritic flares of the joint.

Barbella: What challenges are involved with the unfusion technique?
Dr. Hasselman: The biggest challenge is to free the soft tissues around the joint that have become stiff over the time the joint has been fused. These tissues must change to become more mobile again. The second challenge is to free the sesamoids from the bottom of the joint. Often, they are “stuck” under the joint and must be freed. The joint line that was originally there prior to the fusion must be restored when putting in the new joint so the patient still puts pressure on the great toe and has the push off strength they are used to having.

Barbella: Why have toe fusions fallen out of favor with patients and surgeons?
Dr. Hasselman: Less than 10 years ago, ankle fusions were still considered the standard of care as ankle replacement technology had not provided lasting good outcomes when compared to knee and hip replacements. However, with the advent of better technology, ankle replacements are considered equal or superior to ankle fusions. Ankle fusions can severely limit patient’s function and as the newer technology has shown good outcomes and function with ankle replacement, the market has moved toward this idea. The same is true for fusion of the first MTP joint. As newer technology has shown good outcomes, the idea of avoiding fusion has become more popular. The area of toe replacement has been around for quite some time but the outcomes with this technology has not been as good as it has with fusion. With the concepts of the HemiCAP and ToeMotion implants, the technology is finally catching up so that outcomes with these implants may be as good as toe fusion. Just as one can go from fusion to an implant, one can go from implant to fusion.