Nonoperative management of functional hallux limitus in a patient with rheumatoid arthritis.

Functional hallux limitus (FHL) is a relatively unknown condition that clinicians may overlook when examining people who have foot and ankle impairments. This condition is a limitation of extension range of motion (ROM) of the first metatarsophalangeal (MTP) joint during the terminal stance phase of gait. (1-3) It is also characterized by normal first MTP joint extension ROM during non-weight-bearing examination. (1-3) Functional hallux limitus, therefore, is a loss of otherwise available first MTP joint extension ROM during terminal stance. Radiographs of the first MTP joint may be normal, but osteoarthritic joint changes can develop over time. (2-4) Functional hallux limitus may be a precursor for the development of hallux limitus and hallux rigidus. (3-5)

During ambulation, compensations for FHL are numerous and may include any strategy that reduces the need for first MTP joint extension ROM during terminal stance. People may laterally (externally) rotate the limb at any segment to place the foot in a toes-out position. Some people reduce contralateral step length or ipsilateral heel-rise at terminal stance by increasing ipsilateral ankle dorsiflexion. Alternatively, people may supinate the foot throughout the entire stance phase to push off from the lateral aspect of the foot and avoid or reduce weight bearing through the hallux. Some people may simply lift the foot off the ground to avoid push off entirely.

If people do not compensate when walking, they may develop a first MTP joint dorsal exostosis, hallux interphalangeal (IP) joint hyperextension, and a painful callus under the hallux IP joint (not the metatarsal head). (2,3) If FHL occurs in a person with RA, the hallux IP joint plantar callus may be mistaken for a rheumatoid nodule. If the person has surgery to excise the nodule without addressing the cause of the problem, the callus and pain likely will return.

The cause of FHL has not been clearly established. Clayton and Ries observed FHL, which they called "functional hallux rigidus," in patients with RA and suggested that the cause of the condition was "spasm of the great toe intrinsic muscles in an effort to unweight painful lesser metatarsal heads related to synovitis." (2(p233)) Functional hallux limitus, however, does not occur exclusively in people with RA. The windlass mechanism has been implicated in playing a role in the development of FHL. (6-8) Hicks first described the windlass mechanism as "a toe extending arch raising effect" (6(p28)) after performing cadaveric studies. He observed that "as the 1st MTP joint is extended, the medial longitudinal arch ... raises via tightening of the plantar aponeurosis." (6(p28)) He concluded that "during gait, arch raising is not necessarily the result of muscular action but is a movement that must inevitably occur in every foot, even dead or paralytic, every time the toes are extended." (6(p29)) Through radiographic examination, he demonstrated that the windlass mechanism causes approximation of the metatarsal heads toward the calcaneus through metatarsal plantar flexion and supination of the naviculo-cuneiform and cuneo-metatarsal joints. The windlass mechanism has since been widely recognized as a desirable effect that contributes to the resupination of the foot during terminal stance and leads to increased stability of the foot during propulsion.

It is important to note, however, that when Hicks (6) first described the windlass mechanism, he showed that the mechanism also works in reverse. That is, when the medial longitudinal arch lowered, the first ray (metatarsal and cuneiform) underwent dorsiflexion and the medial longitudinal arch elongated. This led to an increase in the distance between the origin and insertion of the medial slip of the plantar aponeurosis, resulting in tension on the plantar aponeurosis, which "unwinds the windlass" (6(p30)) and created automatic flexion (or loss of extension) of the first MTP joint (Fig. 1). (6,7,9,10) After the plantar aponeurosis was transected, this automatic MTP flexion phenomenon was no longer observed. (6)

[FIGURE 1 OMITTED]

In some people with RA of 5 to 10 years' duration, the subtalar and midtarsal joints become unstable and undergo excessive pronation. (11,12) During weight bearing, the calcaneus moves into a position of valgus (eversion), and the medial longitudinal arch flattens. (11,12) These motions, accompanied by first ray dorsiflexion, lead to increased plantar aponeurosis tension, as described by Hicks. (6) When these joint motions are abnormally high, the tension applied to the plantar aponeurosis will be high. (8) First MTP extension ROM can become blocked by the tight plantar aponeurosis via its insertion on the base of the proximal phalanx (Fig. 1). (6-8) The timing of this abnormal joint motion, subsequent plantar aponeurosis tension, and temporary restriction of hallux MTP joint extension are important during ambulation. If the subtalar and midtarsal joints remain excessively pronated during terminal stance as the foot attempts to rotate about the fixed hallux, first MTP joint extension will be blocked. The dorsal surfaces of the proximal phalanx and the first metatarsal head may abut against one another, which can lead to pain and a subchondral defect of both articular surfaces over time. (2,4,8) These pathomechanical sequelae, referred to as the "reverse" windlass effect, (6,7,9) represent a plausible explanation for the cause of FHL.

This case report describes a patient with RA who we believe had an FHL related to excessive and prolonged rear-foot and midfoot pronation. The Guide to Physical Therapist Practice (13) served as an outline to present examination, evaluation, diagnosis, prognosis, intervention, and outcome data.

Case Description

Examination

History

General demographics. The patient was a 55-year-old woman with a 10-year history of seropositive RA. She was divorced and lived in a 2-story home with 1 of her 2 adult children. She was referred for outpatient physical therapy at a tertiary care hospital for examination and management of bilateral foot pain.

Employment/work. At the time of the diagnosis of RA, she was employed as an elementary school teacher. Within 1 year of her diagnosis, she changed careers to telecommunications, which allowed her to be more sedentary with less stress on her joints. She had continued to work 40 hours per week.

Current conditions/chief complaints. The patient reported having foot, hand, and wrist pain since being diagnosed with RA. Her foot pain had intensified during the 5 months prior to referral for physical therapy, which interfered with her ability to walk and work. She reported having continuous pain under the balls of her feet while standing and reported "the worst pain occurs under both of my big toes during walking, especially on the left." She had never been referred for physical therapy. When asked what she hoped to gain from physical therapy, she replied, "I would like to know if anything can help me walk better so I can continue working."

Functional status and activity level. The patient enjoyed a healthy, active lifestyle that included skiing, running, and working full time prior to her diagnosis of RA. Currently, she had difficulty and pain with activities of daily living (ADL), especially using stairs, walking, and lifting objects such as her briefcase and food and beverage containers. She was able to stand and walk on level surfaces independently for up to 30 minutes on a "good day" before foot pain forced her to sit. She felt unsteady when walking on uneven surfaces and had avoided this for the past year. She had been using the elevator at work instead of stairs. She recently joined a fitness center to attend a water aerobics class, but dropped out after she found the first 2 sessions to be "too challenging," leaving her exhausted afterward. She had stopped all previous routine exercise and social activities for the past year. She was discouraged by her increase in foot pain and loss of function. She had recently acquired a temporary "disabled" parking pass and an application for social security disability.

Chart Review

Medical/surgical history. Five years after being diagnosed with RA, the patient underwent bilateral hallux IP joint fusions with removal of nodules located directly under the hallux IP joints in an attempt to reduce pain. Both IP joints failed to fuse, pain continued, and the patient reported that the nodule returned within a few months after surgery. She had received more than 15 corticosteroid joint injections in the feet, ankles, knees, hands, wrists, and shoulders during the previous 6 years. Four years before referral for physical therapy, at age 51 years, she was diagnosed with severe osteoporosis, presumably related to prolonged steroid use.

Medications. Past medical management of her RA included trials of 6 nonsteroidal anti-inflammatory medications, 7 disease-modifying antirheumatic drugs, and 2 experimental medications. Her current medications, with dosages provided when available, included prednisone (Deltasone, * 20 mg daily), azathioprine (Imuran, ([dagger]) 150 mg daily), estrogens and progestins (Prempro, ([double dagger]) 0.625 mg daily), alendronate (Fosamax, ([section]) 5 mg daily), calcitonins (Calcitonin nasal spray ([parallel]), vitamins C and E, and calcium.

Status of RA. The patient's rheumatologist provided current measures of joint inflammation. She had 3 to 4 hours of morning stiffness, an erythrocyte sedimentation rate (ESR) of 66 mm/h (upper limit of normal range = [age+10]/2 for women, or 33 for this patient). Grip strength was 6.8 kg (15 lb) bilaterally. The tender joint count was 14, and the swollen joint count was 29. (14) Blood tests had ruled out a diagnosis of gout.

Systems Review

At the time of initial examination, a brief systems review was conducted to examine cardiopulmonary, integumentary, and neuromuscular system status. The patient exhibited a resting blood pressure of 100/64, a resting heart rate of 88 beats per minute, a respiration rate of 12 per minute, and a body mass index of 23. Skin color and integrity was normal in appearance. Deep tendon reflexes at the Achilles and patellar tendons were brisk and symmetrical. Semmes-Weinstein monofilament testing of both plantar foot surfaces was normal for the 1-g monofilament. (15) The patient was articulate and well educated at a master's degree level, and we did not identify any barriers to learning.

Tests and Measures

The data for reliability of tests and measures reported in this case report are provided when available. We did not assess intrarater reliability for the physical therapist performing the measurements, but the same physical therapist did perform the measurements at the initial visit and all follow-up visits.

Pain. To define how she perceived her pain was affecting her functional level, we asked the patient to complete a Brief Pain Inventory (BPI) assessment (16) at baseline and at a 2-month follow-up (Tab. 1). Daut et al (17) reported that test-retest reliability for various items of the BPI (0-10 scale, with 0-"no pain" and 10 ="worst pain imaginable") ranged from r=.59 to r=.93. Specifically with respect to the pain under her hallux IP joints during walking, she rated the left side 7/10 and the right side 4/10. The pain at both joints intensified the longer she attempted to stand or walk.

Palpation. All palpation findings were present bilaterally. Tenderness to palpation was noted at the plantar hallux IP joints. Metatarsophalangeal joints 2 to 5 felt warm during palpation and were swollen. A lateral compression test (18) (examiner squeezes all metatarsal heads together from lateral fifth metatarsal head toward medial first metatarsal head) and palpation of the plantar aspect of metatarsal heads 2 to 5 were painful. Palpation of the anterior ankle joint, Achilles tendon, central plantar heel, tibialis posterior tendon, origin of the plantar fascia, and navicular tuberosity detected no tenderness. Notably absent on palpation were elevated temperatures and swelling at the sinus tarsi, midfoot joints, and anterior ankle joints.

Posture/alignment. Resting calcaneal standing position is defined as the angle between the vertical bisection of the calcaneus and the floor with the patient standing erect and relaxed with a normal angle of gait and base of support. In this position, the calcanei were in valgus, greater on the left side than on the right side (Fig. 2). A talar bulge sign was present bilaterally (Fig. 3). (19,20) A navicular drop test was performed to assess the magnitude of midfoot pronation. (21) This test measures the difference in height of the navicular bone from the floor while the patient is positioned in 2 different foot postures. First, the patient stands with minimal weight bearing on the side to be measured. The subtalar joint is placed in a neutral position via palpation of" the talar head, and the navicular tuberosity height is measured. Then the patient is asked to stand in a resting calcaneal standing position, with equal weight distribution on both feet, and the measurement is repeated. The right navicular dropped from 43 mm to 24 mm (19 mm), and the left navicular dropped from 48 mm to 24 mm (24 mm). Good intratester reliability for navicular drop measurement has been reported, with intraclass correlation coefficients (ICCs) of .95 for the resting measure and .92 for the neutral measure. (22) The medial longitudinal arch was observed to flatten bilaterally during weight bearing (Fig. 3). All toes, including the hallux, remained in an adducted position during standing and walking, which is uncommon for people with RA. (12)

[FIGURE 2-3 OMITTED]

Range of motion. Passive ROM of first MTP joint extension from a resting calcaneal standing position was assessed, (23) and no motion was available, despite the finding of 55 degrees of passive first MTP extension from a non-weight-bearing position. During this measurement, the distal end of the proximal phalanx was palpated and felt to be forcibly pressing into the floor. The IP joint could be extended 45 degrees bilaterally. Other ROM measurements are summarized in Table 2. Elveru et al (24) reported intratester reliability ranging from ICC=.74 to ICC=.90 for ankle and subtalar joint ROM measurements. All measurements were made with a standard goniometer according to the procedures outlined by Norkin and White, (25) except for non-weight-bearing subtalar joint neutral estimates, which are based on clinical experience. Measurements of these subtalar joint neutral relationships have questionable reliability. (26) See the following section for further explanation regarding forefoot to rear foot relationship (eg, forefoot supinatus).

Inspection/foot deformities. Calluses were present under each hallux IP joint consistent with the patient's localization of pain. Several other foot deformities were identified, including hammertoe of the left 3rd and 4th toes; claw toes with MTP subluxation of the right 3rd, 4th, and 5th toes; and bilateral hallux varus deformities measuring 10 degrees on the left and 20 degrees on the right. Forefoot supinatus deformities were present bilaterally (Fig. 4). Measurement of this deformity was not made due to perceived poor reliability (26); however, we contend that although the deformity is difficult to measure, the presence or absence of the deformity is important to note and, in this case, was not in question due to the large magnitude of the deformity. The important relationship of a forefoot supinatus deformity and excessive rear-foot and midfoot pronation has been well described. (20) A forefoot supinatus deformity has been associated with more than 20 lower-extremity pathologic conditions. (27)

[FIGURE 4 OMITTED]

While stabilizing the patient's metatarsal heads 2 to 5, the dorsal surface of the first metatarsal head could be dorsiflexed manually approximately 1.5 cm past the dorsal surface of the 2nd metatarsal head. (10,20) Plantar flexion mobility was approximately 1.0 cm bilaterally using the same technique; however, a recent study (28) has raised concerns regarding the validity of manual testing of first ray mobility.

Muscle performance. Manual muscle testing (MMT) was performed according to the methods of Kendall et al. (29) Muscles of the hips, knees, and ankles were all scored as either 9/10 or 10/10, with the exception of tibialis posterior muscles bilaterally, which were scored as 6/10 with no pain during testing. The patient was able to actively flex and extend all MTP joints, but MMT was not performed due to pain at these joints. Florence et al (30) found that MMT intrarater reliability, for individual muscles ranged from [K.sub.w]=.80 to [K.sub.w]=.99 (Cohen weighted kappa) in patients with neuromuscular impairments.

Visual gait observation. The patient exhibited all antalgic, apropulsive gait pattern and appeared to avoid weight bearing on her forefeet bilaterally. She walked with symmetrical short step lengths, but with a fast cadence. She demonstrated a normal heel contact, but then displayed excessive rear-foot and midfoot pronation during mid-stance and did not appear to resupinate at any time during terminal stance. This observation was supported by the fact that the talar bulge sign and the calcaneal valgus deformity were visualized throughout the entire stance phase bilaterally. Heel-rise was delayed, and the magnitude of heel-rise was reduced bilaterally.

Footwear inspection. She initially wore "slip-on" flat dress shoes that were deformed by the shape of her collapsed midfoot region. When she removed her shoes, erythema was present bilaterally over the bunion and bunionette (tailors' bunion, lateral fifth metatarsal head) areas, indicating that her shoes were too narrow. The shoes offered no support to the joints of the midfoot and rear foot.

Foot radiographs. Weight-bearing radiographs revealed diffuse osteoporosis throughout both feet and no evidence of fracture. Marginal erosions had occurred at metatarsal heads 2 to 5 bilaterally. The fifth metatarsal heads were both essentially nonexistent due to damage from RA erosion. The proximal phalanx of each hallux was flexed, as if the patient were actively grabbing the floor as described by Clayton and Ries (2) (Fig. 5). The patient stated, however, that she was not experiencing pain during the radiograph and said she had not attempted to reposition her foot with active toe movements.

[FIGURE 5 OMMITED]

Evaluation, Diagnosis, and Prognosis

The patient's history and examination indicated that RA pathophysiology and abnormal foot mechanics played a role in her pain and related functional limitations. She reported that her disease course had been progressive without remission. Numerous medication trials, including her current regimen, multiple steroid injections, and surgical intervention had not controlled her foot pain. Evidence of systemic inflammation included an ESR twice the normal value for her age, a high swollen joint count (n=29), 3 to 4 hours of morning stiffness (considered high for patients with RA), and a weak grip strength. (31) Synovitis was present at MTP joints 2 to 5 bilaterally, and palpation of these joints indicated swelling, increased temperature, and pain. Metatarsalgia was confirmed with plantar palpation of metatarsal heads 2 to 5 and a lateral compression test that was positive for pain. Based on these findings of active inflammation, we anticipated that information about and instruction in nonpharmacological forms of inflammation control, such as cryotherapy, elevation, compression, and joint protection, would be beneficial for this patient.

Foot pathomechanics also were evident during the examination. Palpation identified pain and callus formation at both plantar hallux IP joints, which are uncommon findings in patients with RA. Both hallux MTP joints could be passively extended 55 degrees without pain during the non-weight-bearing examination. However, when the patient stood in a resting calcaneal standing position, the hallux MTP joints could no longer be extended passively. Normal ROM at the first MTP joint during standing is 37 degrees. (23) Consistent with radiographic findings, palpation revealed that the distal end of the proximal phalanx was forcibly pressing into the floor. The hallux IP joints could be passively hyper-extended during weight bearing and non-weight bearing, indicating that flexor hallucis longus muscle contraction was not responsible for the forceful flexion at the MTP joint. Based on these findings, we concluded that the patient's primary complaint of pain was related to high plantar pressures under the hallux IP joints.

The etiology of these high pressures was unclear. In people with RA, high plantar pressures commonly occur at the metatarsal heads, (32) not the hallux IP joints, and can be caused by fixed contractures or joint dislocation; however, our examination eliminated these as contributing factors. We believed the best explanation for the increased plantar IP joint pressures was a sequence of abnormal foot pathomechanics resulting in an FHL. Examination indicated bilateral excessive calcaneal valgus and a navicular drop test between 2 and 3 times that of normal values. (21,22,33,34) Excessive navicular drop and calcaneal valgus are closely related to a flattening of the medial longitudinal arch, which creates increased tension on the plantar aponeurosis. Our patient exhibited approximately 1.5 cm of first metatarsal dorsiflexion ROM, indicating hypermobility, (10) which also contributed to increased plantar aponeurosis tension. As described earlier by Hicks, (6) lowering of the medial longitudinal arch coupled with first metatarsal dorsiflexion leads to an "automatic" flexion of the first MTP joint by virtue of the insertion of the plantar aponeurosis onto the base of the proximal phalanx. It is this "reversal" of the windlass mechanism that can lead to an FHL. This may explain why our patient had 55 degrees of first MTP extension ROM while non-weight bearing but lacked first MTP joint extension ROM during standing. Furthermore, our patient's abnormal foot pronation, and subsequent automatic first MTP flexion (lack of first MTP extension), continued late in stance, leading to high plantar pressures at both hallux IP joints during walking. The normal requirement for first MTP extension ROM during walking is between 42 degrees (23) and 65 degrees. (35)

Based on these examination data and our hypothesis of abnormal foot pathomechanics, we believed our patient would benefit from custom-made semirigid foot orthoses to decrease the magnitude of excessive midfoot and rear-foot pronation. If calcaneal valgus mobility could be decreased and the medial longitudinal arch supported to prevent flattening, then the automatic first MTP flexion, via plantar aponeurosis tension, should be reduced. Orthoses were expected to improve first MTP extension ROM and decrease pressure and pain under the hallux IP joints during standing and walking. We felt that the patient's symptoms of metatarsalgia could be managed with foot orthoses, prescription footwear, and shoe modifications.

The prognosis for any patient with progressive RA, resistant to medical control, is somewhat limited because if inflammation is not well controlled, subsequent pain, joint damage, and deformity may persist. With respect to the lower extremities, our patient's disease was active only in the forefoot joints and had spared the joints at the midfoot, rear foot, ankle, knee, and hip. Although the midfoot and rear-foot articular surfaces had been preserved, alignment at these joints had been compromised. In patients with 10 to 20 years' duration of RA, ligamentous laxity and foot joint hypermobility are common. (11,12,36) Fortunately, our patient did not experience joint ankylosis in the position of excessive pronation (such as rigid pes planus), providing an opportunity to improve her rear-foot alignment via foot orthoses. We believed that much of her foot pain and limited ability to stand and walk was the direct result of mechanical foot impairments rather than painful forefoot synovitis. Based on these factors, we thought the potential for improving our patient's functional level was good.

We discussed with the patient a goal of being able to stand and walk continuously for 2 hours with minimal or no foot pain within 3 weeks of receiving foot orthoses. The importance of our patient returning to and maintaining all active ambulatory lifestyle was underscored by her diagnosis of severe osteoporosis. A long-term goal was for her to perform an enjoyable weight-bearing activity of her choice 3 times per week for 30 minutes within 3 months of the initial examination.

Intervention

The interventions are summarized in Table 3.

Patient/Client-Related Instruction

Patient education began on visit one with a brief overview of the pathophysiology of RA and how systemic inflammation may lead to mechanical foot impairments. We explained the sequence of pathomechanical events that we believed were contributing to her foot pain and dysfunction. The patient was instructed about how and when to use cryotherapy, elevation, and light compression on acutely inflamed joints, and moist heat for symptomatic relief of chronic joint pain. We emphasized the importance of regular weight-bearing exercise or activities to prevent further bone demineralization. An immediate increase in standing or walking, however, was discouraged until we could be certain that her midfoot and rear-foot joints, as well as local soft tissues, could be adequately supported and protected with orthoses and footwear. For household ambulation, the patient agreed to use supportive shoes or sandals with a contoured foot bed rather than slippers or socks. She was told about the benefits of prescription footwear, including what features to look for to meet her needs (see "Footwear prescription" section). We advised her to plan each day's activities in advance to avoid hurried or fast walking, which might lead to an increase in stride length. This would require increased first MTP joint extension ROM, which we wanted to minimize prior to treatment. She was encouraged to return to her aquatic class and sit out the difficult exercises until her endurance improved, or perform water walking independently at a comfortable slow pace in chest-high water.

Orthotic Devices

Ankle stirrup brace. Immediately following the examination, the patient was fit with standard ankle stirrup braces bilaterally and instructed to use them whenever she was standing or walking. The purpose of the ankle braces was to provide relative immobilization of the subtalar joint in the frontal plane in an attempt to reduce excessive calcaneal valgus. (37) We advised her to use the braces with her athletic footwear, and she agreed to wear them all day for 3 weeks.

Foot orthoses. A national foot orthotic laboratory # fabricated the foot orthoses. The prescription included a semirigid metatarsal length shell with a rear-foot intrinsic varus post of 8 degrees on the left and 4 degrees on the right. (Fig. 6). An intrinsic varus post is a modification to the shell creating a wedge effect so that the medial calcaneal tubercle rests on an elevated surface compared to the lateral tubercle. The patient's medial forefoot could not reach the ground comfortably when her rear foot was placed in a subtalar joint neutral position during standing, so we decided to add a 5-degree forefoot extrinsic varus tip post bilaterally (Fig. 6). An extrinsic varus tip post is a small wedge, thicker medial than lateral, attached to the bottom of the orthotic shell; in this case, used to support the first metatarsal. We also prescribed an extra deep 12.7-mm (1/2-in) heel seat for better frontal-plane control of the calcaneus. In our experience, patients with RA notice improved comfort when soft materials are directly against the plantar surface of the foot. Therefore, a full-length dual-density top cover made of 3.2 mm (1/8 in) of open-cell polyethelene foam backed by 3.2 mm of closed cell microcellular rubber was incorporated, as well as a scaphoid pad for additional arch support (Fig. 6). We extended the top cover past the top trim line of the heel seat to further create a snug calcaneal shoe fit. (18)

[FIGURE 6 OMITTED]

Initial foot orthoses fitting. During the second visit, detailed instructions for a slow gradual break-in of the foot orthoses were provided, and the patient was requested to complete a 10-day response log. This log required the patient to record the number of hours of daily use of the foot orthoses as well as brief descriptions of activities performed and symptoms experienced during the break-in period. We recommended that she wear the orthoses 1 to 2 hours the first day and add 1 hour of use per day as tolerated.

Footwear prescription. Also during the second visit, we referred the patient to a local pedorthic facility with a prescription for a depth-inlay oxford shoe with a wide-based outsole and ample toe box space to accommodate her orthoses and toe deformities. Depth inlay shoes are standard shoes that have an additional 6.35 mm of internal depth when the shoes inlay is removed and are ideal for patients who require additional room for foot orthoses. A pedorthic facility is a specialized shoe store accredited by the Board for Certification in Pedorthics. (**,38) We requested a shoe with a firm heel counter to help stabilize the calcanei in the frontal plane and a durable polyurethane outsole that could be modified with a rocker bottom panel.

Shoe modifications. A standard rocker bottom shoe modification was added to the sole of both shoes. The apex of the rocker was placed just proximal to the location of the metatarsal heads. This intervention minimizes the need for first MTP joint extension ROM during terminal stance phase and can decrease forefoot pressures and pain. (39-42)

Foot orthosis modifications. During the third visit, the orthoses were inspected. The top covers had nearly completely compressed under the hallux IP joint, indicating continued high pressure under these joints. Based on this observation, we decided to replace the top cover with identical materials used 1 week previously and to add an additional midfoot support pad called an "extended medial to lateral scaphoid pad" (Fig. 6). This pad was placed directly under the midfoot joints. It was made of dual-density materials and 3.2-mm polyethelene foam on top of 3.2-mm microcellular rubber, was beveled thinner under the lateral midfoot than under the medial midfoot, and was beveled anteriorly and posteriorly for comfort.

Outcomes

Plantar pressure assessment. On the fourth visit, 6 weeks after the physical therapist examination, the patient reported that her left hallux pain had been reduced to 1/10. Her first MTP joint extension passive ROM increased from 0 degrees while standing barefoot in a resting calcaneal standing position to 15 degrees while standing on the foot orthoses, indicating less forced flexion at both MTP joints during standing. We observed that the compressed top cover areas seen previously under the hallux IP joints were less visible despite 2 weeks of regular use, indicating that plantar pressures likely had been reduced.

We measured in-shoe peak plantar pressures to quantitatively assess the effects of the foot orthoses on plantar pressures during ambulation. Plantar pressure was assessed with Pedar insoles ([dagger] [dagger]) that were calibrated according to manufacturer's instructions just prior to use. Reliability, reported for this device ranged from ICC=.84 to ICC=.99 depending on the plantar region analyzed. (43) The patient ambulated independently while wearing her new shoes with rocker bottom soles. Test conditions included shoes only, shoes with foot orthoses, and shoes with foot orthoses plus the medial to lateral extended scaphoid pad. Plantar pressure measurements were obtained during 4 walking trials per condition, and 3 to 5 steps per side were analyzed per trial, for a total of 15 to 18 steps per side and condition. For the analysis, the foot was divided into posterior, middle, and anterior thirds (hindfoot, midfoot, and forefoot). The average and standard deviation of both peak pressure and the pressure-time integral were obtained within each foot region for each side and condition (Fig. 7). The pressure-time integral represents the area raider the peak pressure time curve. Therefore, if peak pressure values are reduced and contact time stays the same, the pressure-time integral will also he reduced. For all 3 Conditions, pressure variables were greater under the left foot than the right foot, and usually greater under the heel than the forefoot. The exception was greater peak pressures under the left forefoot as compared with the left heel. The highest peak pressure within the forefoot region was under the hallux IP joint bilaterally.

[FIGURE 7 OMITTED]

Differences across conditions demonstrated that the addition of orthoses decreased the peak pressure under the hindfoot and forefoot by approximately 50% as compared with the modified shoe-only condition. The addition of the oversized scaphoid pad to the foot orthoses further reduced hallux IP joint peak plantar pressures without substantially increasing midfoot region peak pressure or peak pressure-time integral. The addition of the scaphoid pad, however, did increase total force under the midfoot region.

It may have been useful to have added a barefoot or self-selected shoe trial during the plantar pressure testing to evaluate the effect of the footwear with the rocker bottom sole modification. Several research studies and clinical articles (39-42,44) have shown that forefoot plantar pressures or pain can be reduced with a rocker bottom shoe, and we believe that our patient benefited from this intervention. Our primary interest, however, was in assessing peak forefoot plantar pressures with the orthoses and the midfoot support pad independent of the footwear modifications.

2-month follow-up. The patient was telephoned 2 weeks after the fourth visit to assess her response following intervention and to schedule a follow-up appointment. The patient reported that her feet were pain-free while using the foot orthoses and modified footwear and that she had been able to stand and walk for 4 hours without resting. She had begun to use the stairs at work, noted that ADL tasks were easier to perform and had engaged in 2 social events during the past weekend. A second BPI was completed via telephone, but the patient clearly stated that her pain responses were related to pain in the hands and wrists, not in her feet or ankles (Tab. 1). The patient felt confident that she would be able to return to walking for exercise with her neighborhood friends and planned to resume her aquatic exercise class. She reported excellent patient satisfaction. Based on the patient's responses, we mutually agreed that she was ready for discharge from physical therapy. Short-term goals had been achieved, and it was evident that the long-term goal of walking 3 times per week for 30 minutes should soon be reached as well.

2-year follow-up. The patient reported, via telephone, that 4 months prior to the 2-year follow-up, she began taking etanercept (Enbrel ([double dragger] [double dagger]), which led to remission of her RA. She had attempted to discontinue use of her foot orthoses shortly after this, but her forefoot pain returned, so she resumed using the orthoses. This return of forefoot pain despite remission of her RA strengthened our belief that much of her foot pain and limited ability to stand and walk had been the direct result of mechanical foot impairment rather than systemic inflammation. She could stand and walk continuously for 8 hours daily without foot pain. She reported continued use of depth-inlay footwear with rocker bottom shoe modifications for "95% of the time with the exception of going to church and certain social events." She had continued to work full time.

Discussion

This case report describes a patient who developed functional limitations and disability resulting from progressive RA, which was resistant to pharmacological control, and pathomechanical foot impairments. As her disease, foot deformity, and pain progressed, her functional abilities declined. Following our intervention (consisting of custom-made semirigid foot orthoses, prescription footwear, shoe modifications, and patient education), the patient's hallux IP joint peak pressures were reduced to a tolerable level, and she was able to resume functional and social activities and remain in the work force. We believe that hallux IP joint extension hypermobility developed to compensate for a lack of first MTP joint extension during terminal stance. This compensatory motion may explain why the previous surgery to fuse her hallux IP joints failed.

We have presented one possible cause of a relatively unknown forefoot condition: FHL. People with RA frequently develop calcaneal valgus and excessive midfoot pronation (12,36,45) and therefore may be susceptible to the development of an FHL. In contrast to Clayton and Ries' hypothesis that active contraction of foot intrinsic muscles is responsible for FHL, (2) we believe that the "reverse" windlass phenomenon was a more likely cause of FHL in our patient's case. Additional research is needed to determine the prevalence of FHL in people with and without rheumatic diseases. We believe this case study illustrates the potentially important contribution of physical therapy in the overall management of patients with RA who have foot and ankle impairments and pain. A case report, however, cannot demonstrate the effectiveness of the interventions, and caution is advised when generalizing from one clinical experience to another.

Table 1.
Brief Pain Inventory (Short Form) (16)

                                             Initial       Discharge at
                                             Examination   2 Months (a)

Pain rating between 0 and 10 during past
  week (0="no pain," 10="worst pain
  imaginable)

  At worst                                    8            3
  At best                                     3            1
  On average                                  5            3
  Now                                         8            2

How has pain interfered with the following
  activities during past week? (0="does
  not interfere," 10="completely
  interferes")

  General activity                            9            3
  Mood                                       10            4
  Walking ability                             8            2
  Normal work                                 9            4
  Relations with people                      10            4
  Sleep                                       8            2
  Enjoyment of life                           9            3

(a) Patient stated that pain rating represented pain in her hands and
wrists. No pain reported in feet.

Table 2.
Passive Range of Motion (in Degrees) (a)
                                 Left                  Right

Calcaneal inversion               25                     25
Calcaneal eversion                15                     20
Ankle dorsiflexion,               22                     20
  knee extended
STJN measurements
  Lower leg/rear           [approximately         [approximately
    foot relationship         equal to] 2 varus      equal to] 2 varus
  Forefoot/rear foot       [approximately         [approximately
    foot relationship         equal to] 40 varus     equal to] 30 varus
First MTP extension RCSP           0                      0
First MTP extension NWB           55                     55
First MTP flexion NWB             20                     20
First IP hyperextension           45                     45
  NWB/WB
Tibial varum RCSP                  8                      6

(a) STJN=subtalar joint neutral, MTP=metatarsophalangeal joint,
RCSP=resting calcaneal stance posture, NWB=non-weight bearing,
WB=weight bearing, IP=interphalangeal joint.

Table 3.
Interventions

Examination              Intervention             Response to Care

Visit 1 (90 min)         Patient-/client-
                           related instruction
                         Plaster cast foot
                           molds taken with
                           patient positioned
                           prone in subtalar
                           joint neutral
                           position
                         Ankle stirrup brace

Reassessment

Visit 2 (60 min)--
  day 21
Adherence to use of      Foot orthoses, initial   Left hallux pain 3/10
  ankle braces and         fitting                  during 25 min of
  athletic shoe use      Orthoses break-in          walking
  reported                 instructions and       No midfoot discomfort
Activity level             response log             or erythema after
  unchanged due to       Therapeutic footwear       walking
  continued hallux         prescription Rocker    Observed increased
  pain rated as 7/10       bottom shoe              gait speed
                           modification             attributed to an
                           prescription             apparent increased
                         Ankle stirrup braces,      step length
                           discharged               bilaterally

Visit 3 (60 min)--
  day 28

Left hallux pain         Orthoses modifications   No foot pain during
  reduced to 4/10                                   20 min of walking
Metatarsal head pain     Checkout of modified     No midfoot discomfort
  rated as 2/10            foot orthoses and        from increased
                           modified footwear        pressure
                                                  Secondary increased
                                                    gait speed

Visit 4 (120 min)--
  day 42
Continuous walking       Plantar pressure         Patient reported high
  for 2-3 h                assessment performed     satisfaction with
Left hallux pain                                    interventions
  reduced to 1/10
Metatarsal head
  pain 0/10

* Pharmacia & Upjohn, 7000 Portage Rd, Kalamazoo, MI 49001.

([dagger]) Faro Pharmaceuticals, 10607 Haddington, Suite 150, Houston. TX 77043.

([double dagger]) Wyeth-Ayerst Laboratories, Div of American Home Products, PO Box 8299, Philadelphia, PA 19101-1245.

([section]) Merck. PO Box 4, West Point, PA 19486-0004.

([parallel]) Mallinckrodt, Div of Tyco Healthcare, 675 McDonnell Blvd, PO Box 5840. Hazelwood, MO 63134.

# The Langer Biomechanics Group Inc, 450 Commack Rd, Deer Park, NY 11729.

** Board for Certification in Pedorthics, 2517 Eastlake Ave E. Suite 200, Seattle, WA 98102.

([dagger] [dagger]) Novel GMBH, Ismaninger Strasse 51, 81675 Munich, Germany.

([double dagger] [double dragger]) Immunex Corp, 51 University St, Seattle WA 98101.

This article was received January 30, 2003, and was accepted May 15, 2003.

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JA Shrader, PT, CPed, is Senior Clinical Specialist and Foot Clinic Coordinator, Physical Therapy Section, Department of Rehabilitation Medicine, Warren Grant Magnuson Clinical Center, National Institutes of Health, Department of Health and Human Services, 10 Center Dr. Bethesda, MD 20892-1604 (USA) ([e-mail]). Address all correspondence to Mr Shrader.

KL Siegel, PT, MA, is Senior Research Physical Therapist, Physical Disabilities Branch, Department of Rehabilitation Medicine, Warren Grant Magnuson Clinical Center, National Institutes of Health, Department of Health and Human Services.

Both authors provided concept/idea/project design, writing, data collection and analysis, and project management. The authors thank Charles McGarvey, PT, MS, for reviewing the manuscript and offering constructive comments. They also thank John Crawford for taking the photographs and Don Bliss for drawing the illustration.

The opinions and information contained in this article are those of the authors and do not necessarily reflect those of the National Institutes of Health or the US Public Health Service.

This work was adapted from a presentation at the Combined Sections Meeting of the American Physical Therapy Association; February 2-6, 2000; New Orleans, La.