Hammertoe refers to a constellation of symptoms including a painful flexion deformity of the proximal interphalangeal joint with the middle and distal phalanges flexed down onto the proximal phalanges (Fig. 176.1). Hammertoe deformity almost always involves the second toe, and the condition is almost always bilateral. A plantar callus overlying the metatarsal head is usually present as is an inflamed adventitious bursa, further exacerbating the pain and cosmetic deformity (Figs. 176.2 and 176.3). Occurring more commonly in women, like hallux valgus, hammertoe is most commonly the result of wearing shoes with too tight of toe box, with the wearing of high-heeled shoes exacerbating the problem (Fig. 176.4).

The majority of patients who present with hammertoe present with the complaint of pain that is localized to the affected proximal interphalangeal joint and the inability to get shoes to fit. Walking makes the pain worse, with rest and heat providing some relief. The pain is constant and is characterized as aching and may interfere with sleep. Some patients complain of a grating or popping sensation with use of the joint, and crepitus may be present on physical examination. In addition to the just-mentioned pain, patients who suffer with hammertoes develop the characteristic hammertoe deformity, which consists of a painful flexion deformity of the proximal interphalangeal joint with the middle and distal phalanges flexed down onto the proximal phalanges.

Functional disability often accompanies the pain of the hammertoe joint. Patients will often notice increasing difficulty in performing their activities of daily living and tasks that require standing, walking, or weight bearing. If the pathologic process responsible for pain of hammertoe is not adequately treated, the patient’s functional disability may worsen and muscle wasting and ultimately a frozen interphalangeal joint may occur.

Plain radiographs are indicated in all patients who present with pain of the hammertoe (Fig. 176.5). Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging or ultrasound of the hammertoe joint is indicated if fracture, effusion, tendinopathy, crystal arthropathy, joint mice, synovitis, foreign body, bursitis, or ligamentous injury is suspected.

The interphalangeal joints of the foot are ginglymoid joints (Fig. 176.6). Each joint has its own capsule. The articular surface of these joints is covered with hyaline cartilage that is susceptible to arthritis. The toe joint capsules are lined with a synovial membrane that attaches to the articular cartilage. The deep transverse ligaments connect the joints of the five toes and provide the majority of strength to the toe joints. The muscles of the toe joint and their attaching tendons are susceptible to trauma and to wear and tear from overuse and misuse. These joints are also susceptible to overuse and misuse injuries with resultant inflammation and arthritis.

The benefits, risks, and alternative treatments are explained to the patient, and informed consent is obtained. The patient is then placed in the supine position with the knee flexed so that the plantar surface of the affected foot rests comfortably on the examination table (Fig. 176.7). With the patient in the above position, the dorsal surface of the metatarsophalangeal joint of the affected toe is identified by palpation (Fig. 176.8). A high-frequency small linear ultrasound transducer is placed in a longitudinal position over the proximal interphalangeal joint of the affected toe, and an ultrasound survey scan is taken (Figs. 176.9 and 176.10). The hypoechoic joint space is identified between the phalanges. When the joint space is identified, the skin overlying the area beneath the ultrasound transducer as well as the skin covering the lateral portion of the joint is then prepped with antiseptic solution. A sterile syringe containing 1.0 mL of 0.25% preservative-free bupivacaine and 40 mg of
methylprednisolone is attached to a 1½-inch, 25-gauge needle using strict aseptic technique. The needle is placed through the skin just below the center of the longitudinally placed transducer and is then advanced using an out-of-plane approach with the needle trajectory adjusted under real-time ultrasound guidance so that the needle tip ultimately rests within the proximal interphalangeal joint space (Fig. 176.11). When the tip of needle is thought to be in satisfactory position, after careful gentle aspiration, a small amount of local anesthetic and steroid is injected under real-time ultrasound guidance to confirm that the needle tip is in the proper position. After proper needle tip placement is confirmed, the remainder of the contents of the syringe are slowly injected. There should be minimal resistance to injection.