First Metatarsophalangeal (MTP) Joint Arthritis
Arthritis of the 1st toe metatarsophalangeal (MTP) joint is the second most common pathology of this joint following hallux valgus, or bunion deformity. First MTP joint arthritis is a progressive degenerative condition, which results in decreased motion of the joint. The exact cause of 1st MTP joint arthritis is unknown; predisposing factors that precipitate this condition include acute injury, such as forced plantarflexion or dorsiflexion (turf toe), stubbing the toe, repetitive microtrauma, fractures into the joint or a crush injury. Congenital deformities of the first MTP joint may also predispose an individual to develop arthritis; these include a short or long first metatarsal, flattened first metatarsal head or an elevated first metatarsal.
Onset of symptoms is usually insidious, but may occur after an acute injury. Stiffness of the first MTP joint, as well as pain and swelling of this joint are common presenting symptoms. Pain is often increased with activity. Positions such as squatting, which cause the joint to hyperextend, will also cause pain. For women, high-heeled shoes often cause increase discomfort due to hyperextension and increased jamming of the joint. Pain is often relieved with rest. Patients’ may also complain of pain on the lateral aspect of their foot as they may compensate and weight bear more laterally to decrease the stress on the first MTP joint.
After taking an accurate history from the patient, physical examination of the patient’s feet is the next step to make a correct diagnosis. In mild cases of arthritis, physical exam may only reveal tenderness or synovial thickening of the joint space. The joint may appear erythematous (red) due to inflammation. Bony hypertrophy and osteophyte formation is often palpable if not visible on exam. There is often limited or no motion of the joint. Patients often experience increased pain with passive range of motion of the joint; this may be due to inflammation of the synovial tissue, the capsule surrounding the joint, stretching of tendons crossing the joint or impingement of soft tissue between osteophytes. Patients may also complain of tingling or increased sensitivity as a result of nerve compression due to the osteophytes. With the patient standing, it may be noted that the patient weight bears on the lateral aspect of their foot to decrease the stress on the first MTP joint.
An accurate history and physical examination can lead to the correct diagnosis the majority of the time. X-rays of the foot are taken to confirm the diagnosis and rule out any other causes of the patient’s pain. Findings on x-ray may include narrowing of the joint space, flattened/widening of the first metatarsal head, bone spur formation, cyst formation in the bone or an osteochondritis dessican lesion.
Conservative treatment of arthritis of the 1st MTP joint is aimed at slowing the progression of the disease and relieving pain. Anti-inflammatories, such as Motrin or Ibuprofen, are used to decrease the inflammation of the joint. A steroid injection into the joint is another option to decrease the inflammation; although this may only temporarily relieve the pain. Complications of steroid injections include further degeneration of the joint cartilage, infection and nerve damage that can result in numbness/tingling. Orthotics (custom molded inserts) and stiff soled shoes are used to decrease the stress on the joint. With bone spurs located on the dorsal/top aspect of the joint, shoes with an increased depth in the toe box will decrease the pressure placed on the top of the joint. Shoe wear with lower heels will also decrease the stress of the joint.
Surgical treatment options are dependent upon the severity of the arthritis, patient age and activity level. Surgery options include debridement/cheilectomy, joint replacement (arthroplasty) and joint fusion (arthrodesis). Debridement of the first MTP joint involves removal of the bone spurs and bony formation that is causing pain and restricting motion of the joint. Debridement preserves joint motion. Patients are able to walk on their foot the day of surgery in a rigid postoperative shoe, but are asked to limit their activities. When the patient returns to the office for their first postoperative appointment, he/she is taught how to perform range of motion exercises of the joint to prevent recurrent stiffness. Joint replacement, or arthroplasty, may also preserve motion of the joint. In this procedure a portion of the first metatarsal and/or proximal phalanx are resected to allow implantation of the joint replacement. Although the joint is salvaged with arthroplasty, there are many inevitable complications associated. Patients lose push off ability of their first toe while walking, as tendon attachments need to be resected in order to place the implant. Patients often get pain in other parts of their foot, which could lead to fractures, as the weight bearing stresses are altered, and often patients develop great toe deformities. Arthrodesis is reserved for end-stage arthritis of the joint or revision of previous failed procedures. With joint fusion, the first metatarsal and proximal phalanx of the first toe are fused together, which inhibits movement of this joint. The joint is fused together using plates and screws in a position for walking. Post-operatively patients are in a cast for three months. Weight bearing on the operative foot is usually allowed at one month. Three months after surgery the patient usually goes to physical therapy and may progress to regular activity as tolerated. Casting may be extended if healing is slow. Fusion allows for normal push off with the great toe , which is needed for normal walking. With first metatarsophalangeal joint fusions, running is limited and heels greater than one inch cannot be worn.
Some complications of surgery include infection, incisions not healing, bones not healing, pain in other areas of the foot and numbness/tingling and deep venous thrombosis(blood clot). Swelling after any procedure to the foot may last up to 6 months post-operatively.
Coughlin, M. J., & Mann, R.A. (1999). Surgery of the foot and ankle, 7th edition, volume 1. St. Louis: Mosby, Inc.