Rheumatoid Arthritis of the Forefoot

Edited by Chris DiGiovanni, MD

 

Summary

One of the most common ways that Rheumatoid Arthritis (RA) is initially diagnosed is when it presents as a problem in the foot. Although rheumatoid arthritis can affect any part of the foot or ankle, including the hindoot and midfoot, the forefoot represents one of the most common sites affected by this disease process. Forefoot deformity and disease from rheumatoid arthritis can present in many different ways and with varying severity and chronicity. Despite this large spectrum of pathology, however, there is often a classic forefoot deformity present that affects all five digits (rays), and will be described below. There are many new pharmaceutical therapies evolving as treatment possibilities to control RA today. Some of these hold great promise in improving quality of life—but even when the disease is brought under control, patients may still face ongoing difficulties associated with any residual arthritis and resultant deformity.

Clinical Presentation

Numerous deformities are associated with RA, which is a disease of joints and can therefore, affect any articulation of the forefoot. These joints include the metatarsophalangeal (MP) articulations (joints at the base of the toes) of rays 1-5 (big toe-little toe), as well as the interphalangeal (IP) joints within the toes themselves. The deformities occur as a result of a build-up of cellular and inflammatory mediators that are a byproduct of the RA disease process inside and around each of these joints. While RA cannot always be predicted to affect any particular joint or joints in any one patient’s case, it usually affects multiple joints at one time. When it involves the forefoot, RA typically causes gradual destruction, arthritis, and capsular attenuation of the MP joints of all five toes. This arthritic and erosive process can deteriorate both the bone and soft tissues surrounding these joints, and deformity can therefore, occur in any plane due to the resultant instability and irregularity that occurs. The classic presentation includes slowly progressive swelling in the forefoot, discomfort across all of these joints, and deformity. Deformities often include:

• A bunion (hallux valgus) deformity with arthritis of the first MTP joint,
• Clawing (contracture) of all the lesser toes, and
• Subluxation or dislocation of the lesser MTP joints. This can lead to the involved toes being retracted and pulled up off the ground, causing them to no longer contact the sole of the shoe and instead rub along the top of the shoe.

Patients with clawed toes that result in dislocation often complain of feeling like they are “walking on a pebble” because of the retracted padding beneath these toes. This retracted padding causes the bony metatarsal heads to be prominent on the sole of the foot. The toes frequently not only retract upward, but also malrotate and thereby cross over one another. This rubbing can be very irritating and can also lead to skin ulceration or infection if not carefully monitored and treated. Such deformities and their associated pain are usually obvious upon physical examination. Associated nail deformities are also common, and the disease process is frequently bilateral.

Imaging Studies

Although a diagnosis of RA can often be made clinically, x-rays are helpful to confirm the extent of the pathology. The radiographic findings are relatively unique when the disease process has progressed. Classic RA causes the bones to be less dense (osteopenia). In addition, there is a symmetric loss of bone where the joint capsule attaches (periarticular erosions) in the MP joints in the forefoot. Loss of joint space on x-ray can be mild in nature, but there can be remarkable destruction of the entire metatarsal heads in more severe cases. Both sides of the MP joints are usually affected. The disease can also deform the other joints of the toes (IP joints).

Treatment

Non-Operative Treatment

The goal of non-operative management is to render the deformed and/or diseased portion of the forefoot as comfortable and “shoe-able” as possible, as well as to minimize any chance of ulceration or infection. Non-operative treatments of RA of the forefoot may include:

• Comfort shoes. Shoes characterized by a wide toe box can be extremely helpful in managing the pain (frictional irritation and rubbing) associated with RA.
• Orthotic inserts that are bought over the counter or custom-made can be similarly used to help offload any area of bony prominence.
• Corn pads, silicone caps, or basic padding. These can also be used to protect bony prominences. There are also devices available to help improve claw toe position.
• Activity modification can also be helpful in managing pain due to RA in the forefoot.
• Physical Therapy. In some instances, physical therapy or a stretching program may be recommended in order to help maintain joint mobility.
• Optimizing medical management of the RA. Obviously optimizing disease control with various drug trials through one’s primary care physician can go a long way towards maintaining a level of comfort and disease control, that also avoids any need for surgical intervention for these joints. It is critical that the RA itself be managed systemically with the help of one’s rheumatologist and/or primary care doctor, to minimize the possibility of disease progression that could lead to further damage and deformation.

Operative Treatment

Operative treatment for the rheumatoid forefoot must be directed towards the patient’s chief complaint, as well as any at-risk area in the forefoot. Operative treatment options include:

• Clawtoe corrections. For mild to moderate deformity, procedures to straighten claw toes and restore toe competence with the ground can be very rewarding. If a joint is not yet dislocated and has reasonably well-preserved cartilage, it is preferable to preserve the MTP joints by reducing the subluxed joint and correcting the claw toes.

For moderate to severe forefoot deformities, however, the surgical options vary and become somewhat more complicated. Typically in these cases fusion surgery, when possible, is desired and may include:

• Great toe fusion For a bunion deformity of the great (1st) toe, it is common for the great toe MP joint to be straightened and fused—as opposed to simply being realigned as it might be in a much more mild MP condition. This procedure greatly reduces the pain in the great toe, and is quite durable and well tolerated. Various forms of 1st MP joint replacement exist, but these implants have not withstood the test of time, and have not proven as durable or reliable as fusion of the great toe in more severely involved cases.
• Lesser Toe procedures. The various lesser toe deformities caused by RA in the forefoot can also be addressed in different ways. When the disease process is quite early and there is little deformity or arthritic change, consideration can be given to simply re-aligning the MP and IP joints via open reductions of the MP joints; possible shortening osteotomies of the metatarsals; and hammertoe repairs. This operation can be quite functional for the patient as long as the joints themselves start and remain in good condition.
• Clayton-Hoffman Procedure. In severe RA, the MP joint at the base of the toes may be too arthritic or displaced to be preserved. In this situation, it may be necessary to perform a standard Clayton-Hoffmann procedure, which involves a resection of all four lesser (rays 2-5) metatarsal heads, along with an associated correction of the claw toes themselves. This can be very effective for pain relief of a moderate to severely deformed/arthritic forefoot. While this lessens the pain, however, it does not address the dysfunction of the foot and it should, therefore, be considered an effective but nonetheless salvage procedure. With this operation, the toes will no longer be able to articulate, which will limit the patient’s activity. The toes are much stiffer and straighter, and patients will state they “just float in space there”. They can also describe a much decreased push-off strength in this foot, even though the pain is remarkably improved as compared to pre-operatively. Despite these limitations, however, almost all of these patients, if bad enough to justify the procedure in the first place, will state they would have the procedure again if such a choice had to be re-made.

Treatment of each foot and each toe in all cases must be individualized for the patient, keeping in mind his or her chief complaint, relative co-morbidities, and the potential/presumed natural progression of the disease. Because of the symmetric and diffuse nature of RA, forefoot surgery typically involves addressing all five rays at once. This is the rule rather than the exception for most patients.

Recovery

Although specific recovery directions will accompany each procedure, in most cases weight-bearing will be avoided for the first few weeks after surgery, enabling adequate soft tissue healing and then restricted but progressed thereafter once skin sutures can be removed. Following the initial six weeks, a gradual increase of activity is permitted in conjunction with a progressive physical therapy program. Usually, once the initial splint/immobilization is removed a few weeks post-operatively, the patient is placed into another form of immobilization that is comprised of a special shoe, walker boot, or splint variety to protect the repair while it heals. As swelling and discomfort subside, the function usually improves. Although healing after these cases usually takes between 6-12 weeks, depending on the nature of the surgery, it can often take one full year for a complete (maximal) recovery. In the absence of any complications, transition to regular shoewear typically occurs between 8-16 weeks post-operatively. Fortunately, despite the complexity of this surgery and the length of its recovery, the overwhelming majority of patients are very pleased with their outcomes. Pain relief and alignment are usually much improved, “shoe-ability” is often much improved, and patients therefore tolerate the other unavoidable limitations of such surgery on the foot.

Complications

Common surgical complications after rheumatoid forefoot surgery are similar to other areas of orthopaedic surgery, and include:

• Wound healing problems  Skin and soft tissue incisional healing issues are more common in RA patients
• Infection
• Deep Vein Thrombosis (DVT)
• Pulmonary Embolism
• Nonunion
• Malunion
• Vascular injury. Vascular embarrassment of one or more toes is uncommon, but can happen
• Nerve injuries may lead to numbness of one or more of the toes.
• Recurrent deformities

It is important to remember that certain RA medications must be stopped 2-6 weeks prior to any surgical procedure, and this should be discussed with the patient’s caregivers. Some of these medications are known to increase the chances of infection and wound healing problems. Again, fortunately in experienced hands and with compliant patients who are otherwise reasonably healthy, such complications are fairly rare.

 

Edited on August 28, 2017

mf/ 5.15.18