1st Metatarsal Phalangeal (MTP) Joint Replacement

(Great Toe Joint Replacement, Great Toe Arthroplasty)

Background

Normal walking puts a great deal of stress on the main joint of the great toe – the 1st metatarsophalangeal (1st MTP joint). Kneeling, crouching, running, wearing high-heel shoes, and other activities put even more stress upon it. Arthritis of the great toe joint (1st MTP joint) is fairly common, and can be painful and quite limiting. Hallux Rigidus is by far the most common arthritic condition affecting the great toe; this is a form of degenerative (osteoarthritis) that leads the great toe to become stiff, swollen, and painful. It is fair to say that the “gold standard” surgical treatment for 1st MTP arthritis is fusion of the joint. Great toe fusion converts a stiff painful joint into a stiff, relatively painless joint. Therefore great toe fusion surgery provides consistent pain relief, and most patients undergoing a great toe fusion are very satisfied — but it does not restore motion. This can be limiting, especially if a person wants to wear high (2+”) heels.

Procedure

Joint replacement of the great toe is an interesting alternative to fusion. In large joints, such as the hip or knee, joint replacement with metal and plastic components has been very successful for decades. Joint replacement of the great toe joint has not been as successful. The traditional implants used in 1^st MTP joint replacements have not been as predictable at getting rid of pain. Furthermore, the relatively high forces going through the great toe with each step means that these joint replacements often do not last as long as the implants for hips or knees.

Currently, there are different kinds of 1^st toe implants.

A cap applied just to the metatarsal head (hemiarthroplasty) -essentially a “half a joint replacement”.
A resurfacing of both the metatarsal and the phalanx (toe) sides of the joint -a full joint replacement.
An implant which acts as a thick rubber cushion or bumper in the joint. This “rubber” spacer is made out of a material that is similar to what contact lens are made from (a synthetic hydrogel polymer comprised of polyvinyl alcohol and saline).

Recovery

Different implant types require different recovery timelines, which each patient should discuss with their surgeon prior to having the surgery. The skin site is usually healed in 2-4 weeks after surgery. Each surgeon will have a different amount of time when the patient needs to limit the weight put through the foot (i.e. period of non-weight-bearing). Typically, a 6-week period of rest from normal activities, with elevation of the leg is recommended.

Physical therapy can be helpful during the recovery period to work to improve great toe motion and prevent stiffness, help with walking, and increase strength. Patients can see improvements for up to 6 months or more after their surgery.

Potential General Complications

Potential Specific Complications

Failure of the implant over time

Implant failure can occur at any point, but the risk increases with time. The implants can wear out and fail. The human body does not have a way to heal or change them since they are made of metal, plastic or other synthetics. Replacements involving the great toe can, and often do, fail over time because the joint is subject to a large amount of pressure with each step. Unfortunately, failure can be difficult to treat with surgery due to loss of bone once the implant is removed. Options for surgeons to treat failed implants are a challenge and usually are treated with bone grafting and fusion of the joint.

Deep infection of the implant

Infection can develop with these implants any time after surgery. Infection usually requires implant removal making treatment options difficult but similar to the options for a failed implant. The signs of infection are fevers, chills, redness at the surgical site, drainage from the surgical site, and/or an increase in pain in the foot.

Patient dissatisfaction

Patients usually select an implant surgery if they wish to have a combination of pain relief and have some motion at the joint. A patient may still have a stiff joint despite the implant surgery and can still have pain despite a well-placed implant. The range of motion despite physical therapy can be similar to before surgery. Some patients just have persistent pain, even though things seem to have healed well.

Edited September 12th, 2023

(Previously Edited by Justin Greisberg, MD, Gregory Waryasz, MD, and Sam Dellenbaugh, MD)

sp/09.12.23