Rheumatoid Foot

Introduction

Rheumatoid arthritis (RA) is a complex multisystem disease characterized by a symmetrical polyarthropathy, predominantly affecting small joints. However, varying patterns of arthritis may occur. It occurs in 0.5-1% of the adult population and is 2-3 times commoner in women.

Patients with RA demonstrate auto-immunity; the most characteristic being anti-citrullinated protein antibodies (ACPA), which are more specific for RA than rheumatoid factor (an antibody to the Fc component of IgG. Other antibodies have also been described. Citrullination is a post-transcriptional protein modification in which arginine is deimination to citrulline – this is promoted by smoking, which accounts for the relation between smoking and RA.

 

Pathology

Patients with RA have synovitis infiltrated by B lymphocytes, monocytes and macrophages. Macrophages produce proinflammatory cytokines, especially TNF-α, IL-6 and IL-17. Rheumatoid fibroblast-like synoviocytes also elaborate inflammatory cytokines. In particular, osteoclast precursors are activated through receptor activator of NF-κB (RANK) ligand, producing joint erosions and the formation of inflammatory pannus over the damaged joint surface.

 

Genetics

RA has a strong genetic element. Monozygotic twins have an incidence of 12-15%. Patients with RA commonly share an amino-acid sequence in the major histocompatibility complex, the "shared epitope". This is coded for by the HLA-DRB1 gene, at the HLA-DRw4 locus. The shared epitope is common in ACPA-positive but not ACPA-negative disease. Over 20 other genetic factors have been described, some of which are associated with ACPA-negative disease (HLA-DR3), or are protective against RA (different alleles at HLA-DRB1). There is some evidence that the shared epitope binds citrulline but not arginine and thus can present citrullinated proteins as antigens to T-cells.

 

Systemic Effects

The inflammatory process may also affect extra-articular sites (Turesson 1999). 40% of patients will suffer extra-articular manifestations of RA, of which the commonest are rheumatoid nodules (30%) and keratoconjunctivitis sicca (10%). 1/100 patient-years will suffer a severe extra-articular manifestation such as vasculitis. The presence of extra-articular rheumatoid disease increases mortality by five times.

Rheumatoid nodules are present mainly in seropositive RA and occur mainly over extensor surfaces. They often improve with treatment of the RA, except that methotrexate may make them worse.

Many patients with RA have a normochromic normocytic anaemia of chronic disease with depressed erythropoietin levels and low responsiveness to erythropoietin. More serious is Felty’s syndrome (leukopenia with splenic and sometimes liver enlargement), which predisposes to severe infection. Patients with RA have a higher than average risk of lymphoid malignancies.

Patients with RA have a higher than normal rate of cardiovascular disease and cardiac death. More rarely they may have a small vessel vasculitis with digital infarcts. RA itself can cause pulmonary fibrosis and it is also a side-effect of methotrexate. Nodules may occur in the lungs; solitary nodules may be difficult to distinguish from lung carcinoma.

Peripheral neuropathy is relatively common (Wilson 2006) but rarely causes neuropathic ulceration (Firth 2008).

Other extra-articular manifestations include skin atrophy, episcleritis, amyloidosis and renal disease.

The complex nature of the condition requires a multidisciplinary team approach, including

  • Rheumatologist
  • Physiotherapist
  • Podiatrist
  • Orthotist
  • Nurse
  • Orthopaedic specialists in other sites such as hip, knee and upper limb
  • Radiologist
  • Patient

 

Clinical Assessment

Physical examination of the rheumatoid foot and ankle should include a thorough assessment of the entire patient and observation of gait. Medical complications and management, especially the use of anti-TNF and other biological medications, should be noted. Identify disease at other sites which may affect anaesthesia (eg atlanto-axial instability) or rehabilitation (such as upper limb disease which may make it difficult to use crutches or limit weight bearing post-operatively.

Focal examination of the foot and ankle requires a systematic review of the skin, neurovascular status, range of motion, strength, overall alignment and assessment of deformities. Peripheral pulses must be carefully examined to assure adequate perfusion in potential surgical candidates. A vascular consultation should be obtained if there are any signs of arterial insufficiency which may affect surgical intervention.

Assessment of a patient with rheumatoid forefoot problems should always include a review of other joints, the overall limb alignment and examination of the joints and alignment of the ankle and hindfoot. Patients with hindfoot valgus do less well after forefoot reconstruction than those with normal hindfeet (Stockley 1990).

Check skin integrity and look for neuropathy and vasculitis.

Look under the forefoot for exposed metatarsal heads. Check the reducibility of toe deformities. If the MTP joint is reducible, how unstable is it? Are the tender areas or calluses over the PIP joints dorsally or at the tips of plantar-flexed toes? If toe deformity is mild and most of the pain comes from the MTP joints, feel for synovitis – if in doubt an ultrasound can be helpful.

 

Disease Scoring

RA has traditionally been diagnosed using the American Rheumatology Association’s criteria (McGregor 1995). Recently the ARA and the European League Against Rheumatism (EULAR) agreed revised criteria (Aletaha 2010), which uses number of joints involved, rheumatoid factor/ACPA serology, acute phase protein levels and disease duration to drive a classification algorithm. Disease activity is monitored by the degree of inflammation in index joints, acute phase protein levels and other clinical features as summarized in scores such as the DAS28, SDAI and ACR/EULAR criteria (Felson 2011). However, several of these scores do not assess disease activity in the foot and ankle and there is some evidence that patients who appear to be in remission at other sites still have active foot arthritis (van der Leeden 2010, Wechalekar 2011).

Although MRI and ultrasound offer additional information about disease activity and joint damage, plain radiography is still probably the most used imaging method, and are used in the previous, 1987, grading system for RA (Arnett 1988). Standing radiographs of the foot and ankle can be supplemented by an oblique foot view (not a substitute for a standing lateral) and a standing hindfoot alignment view (Saltzman 1994) to assess the alignment of the ankle and subtalar joint.

Typical abnormalities on plain radiographs include:

  • periarticular erosions
  • geodes (areas of osteopenia in the subarticular bone)
  • joint space narrowing
  • deformity

There are a number of common scoring systems for plain radiographs. Two of the most popular are the Sharp score, focusing on joint space narrowing in the hand and wrist (subsequently modified by van der Heijde (1999) to include the foot), and the Larsen (1995) score, which includes the hand, wrist and foot and focuses on erosions. Boini (2001) reviewed the evidence on plain radiographic scoring. The Sharp and Sharp/van der Heijde methods were more reproducible than the Larsen method, but took longer to score. Most scores showed similar sensitivity to change in disease.

However, the sensitivity of plain radiography is much lower than MRI, especially in early disease (Nissila 1983). The specificity of all investigations is about 90%, but while the sensitivity of plain radiography is 77% in established disease (Arnett 1988) it falls to 10-20% in early disease (Nissila 1983), compared with over 60% for MRI (Cohen 2011). Combining MRI with serology increases sensitivity to over 80% (Tan 2011). However, not all studies have reported such high sensitivity (Suter 2010). Tan’s review also noted that MRI has been a useful monitor of disease activity in some drug trials.

MRI can demonstrate

  • erosions
  • geodes
  • bone oedema
  • synovitis
  • tenosynovitis

Ultrasound can also detect

  • synovial hypertrophy and (especially with the use of colour Doppler) synovitis
  • tenosynovitis
  • erosions

(Tan 2011). Grey scale ultrasound is more sensitive than plain radiography in detecting erosions (Wakefield 2000) but less sensitive than MRI (Wakefield 2007). Ultrasound can also be useful in evaluating early arthritis, monitoring treatment and detecting risk of early relapse (summarized in Tan 2011).

 

Treatment

Goals in RA include:

  • Control of synovitis and pain
  • Maintenance of joint function
  • Prevention of deformities

A multidisciplinary approach is essential, involving pharmacotherapy, physiotherapy and occasionally surgery. Pharmacotherapy is the cornerstone of treatment in RA and has significantly reduced the number of patients requiring surgery in the past decade. The main changes in treatment have been the use of disease-modifying anti-rheumaric drugs (DMARDs) at an earlier stage in the disease, and the introduction of new “biologic” drugs that are antibodies which directly interfere with the disease process.

DMARDs

The most commonly used DMARD is methotrexate (Jurgens 2011), and this is usually considered the “anchor drug” for combination drug regimes. Other DMARDs include:

  • leflunomide
  • sulphasalazine
  • hydroxychloroquine
  • cyclosporin
  • prednisolone

Gold, penicillamine and azathioprine are now less commonly used as they are less effective and/or more toxic. Methotrexate is now started early in treatment. Combination with leflunomide or sulphasalazine + hydroxychloroquine may improve disease control, especially in patients with high disease activity (Jurgens 2011).

Currently five antagonists of TNF-α are available (Ferraccioli 2011, Thalayasingam 2011):

  • etanercept
  • infliximab
  • adalimumab
  • golimumab
  • certolizumab

There are no RCTs comparing these agents directly. Adalimumab appears to have the highest disease suppression rate, while etanercept appears to be best tolerated. Combination therapy using etanercept and methotrexate has a higher remission rate and patients on this regime are more likely to continue therapy. Rituximab inhibits B cells and abatacept T cells.

Effect on disease progression

Early treatment with DMARDs appears to reduce the rate of joint damage. A trial comparing sulphasalazine with methotrexate-sulphasalazine-hydroxychloroquine (Rantalaiho 2010) reported joint erosions in 13% of patients in combined therapy at 11 years, compared with 28% of the monotherapy group. There was no placebo control, but historical controls had an equivalent level of joint damage after 3 years. Bosello (2011) reported a study of aggressive treatment of early RA, in which patients started methotrexate at diagnosis and might have steroids or biologics added. After 12 months, patients who were treated within 12 weeks of disease onset were least likely to have developed new erosions.

There has been a reduction in some presentations for surgery over the last few decades. Rates of knee, hip and ankle surgery in California peaked in the 1990s in patients under 60y and have fallen by 20-40% since; however, rates in patients over 60y increased in line with those in a degenerative population (Louie 2010). Similar results have been reported from Sweden (Weiss 2006). However, rates of surgery were stable in Japan from 1998-2008, and some procedures, including forefoot arthroplasty, increased slightly. Anecdotally, there is a tendency for patients to present now with better-preserved joints, raising the possibility of successful joint-preserving surgery; however, there is not yet much data on the long-term durability of such procedures (see below).

DMARDs, medical management and infection

Biologic agents increase the risk of infection, occasionally catastrophically. Galloway (2011) found an increase in serious infection from 32/100,000 patient years to 42/100,000. Da Cunha (2012) reported a systematic review of the perioperative infection risk in orthopaedic surgery. The best evidence is a large retrospective study (den Broeder 2007) which found no significant difference in infection rates between patients who used anti-TNF drugs and those who had never used them (although the 95% confidence intervals of the odds ratio were 0.98 to 3.44); however, there was an increase in wound healing problems in the patients who had used anti-TNF drugs (OR 11.2, 95% CI 1.4-90). No difference in either event was found in patients who continued drugs through the perioperative period versus those who stopped, but the numbers were small. Kubota (2012) found no difference in either infection or wound problems in 550 patients, including about 100 foot and ankle patients, but all patients stopped biologics prior to surgery. There is also an increase in TB reactivation and other opportunistic infections. The current recommendation is to stop biologics 5 half-lives prior to surgery (15 days for etanercept, although Veetil (2012) felt this led to excess disease flares and recommended withholding for one dose cycle (4-7 days for etanercept).

On the other hand, Grennan (2001) reported an RCT showing that continuing methotrexate in the perioperative period reduced the rate of infection and other wound problems compared with stopping, and prevented rheumatoid flare-ups. Veetil (2012) confirmed that observational studies support continuing methotrexate at the time of surgery.

The foot is a common site of problems in RA. It is not assessed by several of the disease activity activity scales, and foot disease may be less responsive to treatment than other sites (see above).

Vainio (1956) described foot disease in nearly 90% of rheumatology inpatients (848 of 955 feet). In a systematic review, Jaakola and Mann (2004) found foot and ankle symptoms in 90% of patients with RA. Unlike most studies, Michelson (1994) found that hindfoot and ankle disease was commoner than forefoot disease but less likely to be treated. Grondal (2008) surveyed 100 patients attending Swedish rheumatology clinics. When their disease began, 45% had had foot problems and 17% ankle and hindfoot problems. At the time of the study, 86% had problems with the foot (comparable to 83% with problems in the hand), 52% in the ankle or hindfoot, and 45% in both. In the Early Rheumatoid Arthritis Study (Backhouse 2011), 10% had erosions in foot joints at trial entry within 2 years of disease onset. Otter found that quality of life was reduced in 93% of RA patients by foot problems: difficulties included walking, shoe choice, loss of mobility and independence. Turner (2008) found that patients with hindfoot disease (either alone or in combination with forefoot problems) had higher levels of disability and more abnormal gait than patients with forefoot disease alone.

Backhouse found that only 30% of rheumatoid patients had seen a podiatrist in the first 9y of their disease, although most had foot problems.

RA patients with foot disease are more disabled, have poorer quality of life and possibly more active general disease (Wickman 2004). Foot and ankle surgery in RA is more likely to be complicated by infection than surgery at most other sites (relative risk 3.2 - den Broeder 2007).

Although patients are tending to present with foot deformity but less joint damage, there have been no detailed reports of this change, and the series reporting joint-conserving surgery have not generally described the severity of joint damage.

 

Non-operative Management

Non-operative management of RA in the foot includes

  • Physiotherapy
    • Exercises can increase comfort and minimise disability in RA patients.
    • A meta-analysis of the effectiveness of exercise therapy (Gaudin 2008) demonstrated improvements in muscle strength and aerobic capacity.
    • Neuberger (2007) showed that the overall symptoms of fatigue, pain and depression in RA were improved by vigorous exercise
    • Munneke (2004) found significantly less radiologic damage to the joints of the foot with high intensity weightbearing exercises than routine exercises
  • Accommodative shoes (extra width/ extra depth)
  • Padding over prominences
  • Orthotics (custom made inserts or AFOs)
  • Ankle disease usually presents with pain and swelling in the ankle joint line. The joint is painful to move. Although the ligaments are eroded the ankle is not usually unstable. Some patients with severe erosion of the ankle may also have hindfoot valgus, although this is usually due to a combination of abnormal limb biomechanics, subtalar/talonavicular erosion and tibialis posterior tendonopathy (see below). The proximal limb joints, overall limb alignment and the forefoot should also be assessed.
  • It is not always easy to distinguish between pain arising in the ankle or the hindfoot joints, but this distinction may determine the extent of surgery that is required. Clinical examination, plain radiography, ultrasound or MRI, and diagnostic injections may help.
  • Plain radiographs will demonstrate joint damage, erosions and periarticular osteopenia – standing AP/lateral are standard views. MRI or ultrasound may demonstrate synovitis or erosions that are not seen on plain radiography. If there is hindfoot valgus a standing hindfoot alignment view (Saltzmann and el-Khoury 1994) helps to define the contributions of ankle and subtalar tilt.
  • Steroid injections are often helpful on an empirical basis, although there is no good evidence base for their use and in other joints they may not be much better than placebo. Rest/immobilisation and custom orthotics/bracing are often beneficial. An AFO might be required to improve alignment of the ankle and hindfoot.

 

Surgical Treatment of the Ankle

Synovectomy

  • A long-term Japanese study reported recurrent disease in only 10% of ankles at 10-20 year follow-up of open synovectomy (Akagi et al 1997). Synovectomy is beneficial in 80% across all joints, mainly elbows and knees (Chalmers 2011); about half showed radiographic progression and this was commoner after arthroscopic than open procedures. Van der Zant reported good improvement in 56% of patients who underwent rhenium-186 synovial ablation, with a median duration of action of 41months; however, disease recurred in all patients by 75m. Liepe (2011) reported a good response at 3 months in 64% but no long term follow-up.

Ankle Arthrodesis

  • Fusion is the traditional treatment for end-stage ankle arthritis, and remains a viable option. Arthroscopic fusion results in quicker and more reliable fusion, with fewer soft-tissue complications than open fusion, and should be viewed as the standard technique unless there is severe deformity, bone loss or infection.
  • Over 15 series of arthroscopic ankle fusions have been reported. The largest series is that of Winson (2005). 118 fusions were reported, of which 105 were followed clinically for a mean of 65m. 109/118 procedures fused at a mean of 12weeks. Most non-unions happened early in the series, and subsequently the authors immobilised all patients for a minimum of 12 weeks. Smoking was twice as common in non-unions. There were three superficial and one deep infection, one malunion and two pulmonary emboli. Winson recommended arthroscopic fusion even if the ankle was in valgus or varus provided the forefoot was plantigrade.
  • Gougiolias (2007), however, carried out arthroscopic fusions even if there was mortise deformity and the foot was not plantigrade, by excising bone from the mortise arthroscopically to align the ankle. 30/78 patients had a pre-operative coronal deformity of >15deg, but none had more than 3deg post-operatively. Five patients had simultaneous arthroscopic subtalar fusion. There were 5 delayed unions and 2 non-unions; time to union was 2months extra in smokers. There was one PE, one nerve injury and 6 patients had subtalar pain.
  • Many surgeons favour ankle replacement over fusion in inflammatory arthritis to maximise function and reduce stresses on other at-risk joints. However, the available evidence suggests little difference between overall results.
  • Overall about 550 arthroscopic fusions have been reported with a total fusion rate of 93.3%. Several series have commented on the quicker rate of union in arthroscopic procedures although this can be influenced by the intervals at which radiographs are taken, and all series diagnosed union on plain radiography rather than CT. Myerson (1996) noted a mean time of fusion of 8.7 weeks in arthroscopic versus 14.5 weeks in open fusions, while Nielsen (2008) noted that 90% of arthroscopic and 57% of open fusions were united at 12 weeks. However, there are relatively few rheumatoid patients in these series.
  • Open fusion may be done using anterior, lateral or posterior approaches. Maenpaa reported a 90% failure rate in 130 rheumatoid patients, while Felix et al (1998) reported union in 96% of 26 ankles at 2-8 year follow-up, and no pain.

Ankle Replacement

  • Second-generation prostheses from the late 1980s onward introduced improved engineering, often with three components. 10-20 year results are now being published (Kofoed 2004, Buechel et al 2004), indicating success in over 90% of patients. However, these are the series of the designers of the various prostheses, and further results from the “real world” may not be quite so optimistic. The Wrightington series (Wood 2003, 2008) is a realistic and critical account with 92% survival at 5 year and 80% at 10 years. The Swedish register reported 70% 10-year survival and the Norwegian registry 76% 10-year survival. In all these series the survival was the same in RA and OA; Wood reported a higher rate of soft tissue complications in RA. Hindfoot deformity may need to be corrected separately or at the same procedure (Kim 2010).

Fusion vs. Replacement in the Rheumatoid Patient

  • As might be expected, ankle fusion affects the range of motion and kinematics more than does replacement, and certain designs are closer to normal than others (Valderrabano et al 2004a,b). Gait analysis is much closer to normal in replaced than in fused ankles (Butcher 2004, Piriou 2008). Hence it is plausible that ankle replacements would place less stress on other joints, both in the tarsus and proximally. Nevertheless, this requires clinical confirmation.
  • There are, remarkably, no RCTs comparing replacement with fusion, and only one prospective comparative trial, which excluded patients with inflammatory disease (Saltzman 2009, 2010). At 4 years, this study reported better function in the replacements, with equal pain improvement in both groups. A systematic review of the literature by Haddad et al (2007) found the overall reported results of both procedures to be similar, with about 70% satisfactory results after both procedures. The overall non-union rate for ankle fusion was 10% and the arthroplasty survival rate 77% at 10 years. There was more variation in results for arthroplasty. Younger (2010) also found similar overall results for fusion and replacement. SooHoo (2007) and Younger (2011) reported more adverse events after replacement, but SooHoo also reported more subtalar fusions after fusion. None of these series differentiated between RA and OA.
  • Many surgeons tend to favour ankle replacement for patients with polyarthritis with a view to maximizing retained function and minimizing the risk of adjacent arthritis. While this is not based on strong evidence, it is clinically plausible.

 

Surgical Treatment of the Hindfoot

Toolan and Hansen (1998) recommended functional reconstruction of the rheumatoid flatfoot, drawing on evidence from the management of the degenerative adult acquired flatfoot. However, they did not present any data, and no subsequent series of joint-sparing surgery in the hind/midfoot have appeared.

Triple Fusion

The tradition has been to fuse the subtalar, talonavicular and calcaneocuboid joints together on the grounds that this may be required for stability and unfused joints in inflammatory arthritis are likely to require subsequent fusion. Figgie et al (1993) reported 40 triple arthrodeses in RA, with 5% non-union. Eight patients united in >10deg valgus, of whom 5 had ankle pain and 3 had undergone ankle fusion. Knupp (2008) reported 24 triple fusions in 20 patients with RA. All had flatfoot deformity. There were no non-unions or malunions, but 8 patients had superficial wound infections. Arthritis had progressed in 15 midfeet and 10 ankles, but this did not affect outcome. The mean VAS pain score was 47/100, AOFAS midfoot score 70/100 and short musculoskeletal function instrument 45 for dysfunction and 38 for bother. SF-36 scores were just below normal values. Flatfoot deformity may require quite extensive joint resections and medial column shortening (Henderson et al 2002). Stabilisation with compression screws or staples produce similar reported rates of union and clinical benefit. Hindfoot fusion may be combined with ankle replacement to deal with multi-level disease (Kim 2010).

Medial Approach

After correcting a severe flatfoot deformity by triple fusion, it may be difficult to close the lateral hindfoot wound. An alternative is to use a single medial incision (Jeng 2005, Knupp 2009, Weinraub 2010). In these patients the posterior tibial tendon, which normally obstructs the approach, is attenuated or absent. All three joints can be fused through this approach, although Sammarco (2006) showed in a mixed population that subtalar/talonavicular fusion produces satisfactory results and avoids the most challenging part of the procedure.

Isolated Joint Fusions

Popelka (2010) reported 26 isolated talonavicular fusions in patients with RA, talonavicular joint destruction and tibialis posterior insufficiency. At a mean follow-up of 4.5y, mean AOFAS midfoot score improved from 48.2 to 88.6/100. There was one non-union. Eight patients continued to have pain in the foot, two severe. Joint disease progressed in one subtalar and one calcaneocuboid joint. This series implies that isolated fusion can work even in patients with RA, although there are some uncertainties in the resporting of this series that make generalisation difficult.

 

Surgical Treatment of the Forefoot

The typical forefoot problems are hallux valgus, toe clawing and dorsal dislocation of the lesser metatarsophalangeal joints, drawing the plantar fat pad anterior to the metatarsal heads. In this position it no longer provides padding to the metatarsal heads, which become prominent so that patients complain they are “walking on pebbles”. Ulceration may occur on the bony prominences (Firth 2008) and was present in nearly 10% of Firth’s patients. Despite the occurrence of peripheral neuropathy in RA, ulceration was rarely neuropathic in another study by Firth (2008) – it was associated with steroid therapy, pre-ulcerative lesions, peripheral vascular disease and disease activity.

Some patients present with early flexible or semi-flexible deformities. However, the majority have severe clawing with fixed subluxation or dislocation of the MTP joints when referred for surgery. The toes, dislocated onto the dorsum of the metatarsal heads, no longer share load bearing in late stance phase. The plantar plate of the MTP joint is also dislocated onto the top of the head and locks it down by the “plunger effect” (Stainsby 1997). The dislocated toe and plantar plate draw the plantar fat pad forward by their connections to the plantar fascia, leaving the metatarsal heads exposed in the sole. Hence these patients often complain of a sensation of “walking on pebbles”.

There is some controversy about the relationship between the altered forefoot mechanics induced by the flatfoot deformity and the development of hallux valgus. The abnormal laxity induced in all the first ray joints, especially the 1st MTP joint, is probably most important in creating the valgus deformity.

Occasionally referral is precipitated by the development of an ulcer over a stiff deformity, usually the medial prominence of the 1st MT head, under a lesser MT head or over a PIP joint. Ulceration may be due to peripheral neuropathy.

A few patients present with stiff painful 1st MTP joints without deformity, more like hallux rigidus than valgus.

Doorn (2010) described a classification system for rheumatoid forefoot deformity, which they validated in a group of 94 patients with two observers; 61 patients also had foot pressure studies.

  • Grade 0 – no clinical changes in the MTPJs, no or mild radiographic changes
  • Grade 1 – decreased mobility of one or more joints in plantar flexion, fully reducible, adequate plantar soft tissues. Any degree of radiographic change.
  • Grade 2 – loss of plantar flexion in one or more joints, unable to reduce plantar soft tissues under MT heads, inadequate plantar soft tissues. Any degree of radiographic change.
  • Grade 3 – extension contracture of one or more MTPJ, with or without subluxation/dislocation. Any degree of radiographic change.

At grades 2-3, A represents hallux valgus >20°, B represents no hallux valgus.

It is surprising that subluxation/dislocation is not a clearly separate grade as the foot becomes more difficult to treat in the presence of dislocated MTPJs. Indeed the paper is not absolutely clear on this matter. If the classification can be validated in other settings it may be a useful tool.

Joint-preserving Surgery

Traditionally, most forefoot surgery consisted of excision arthroplasties or fusion. The improvement in disease control with modern treatment has stimulated interest in conserving joint function and structure as far as possible. Unfortunately the medical treatment received, and degree of disease control, are not clearly defined in most of the series, leaving some doubt as to which patient populations they apply to. Further studies are required to enable us to advise patients on different treatment regimes, with different degrees of disease control and established joint damage. The series will be described in some detail to give an indication of the data available.

Thordarson (2002) painted an initially gloomy picture with a report of 8 chevron osteotomies, all of which failed at a median of 24 months, due either to recurrent hallux valgus or disease progression.
Three series (Barouk 2007, Berg 2007, Bhavikatti 2012) described a shortening scarf osteotomy for the first ray with Weil osteotomies to the lesser rays (not all patients had both procedures). Barouk’s paper does not contain outcomes. 79% of Berg’s patients were satisfied with the outcome at a minimum of 6 years, although 8/20 had recurrent hallux valgus, three of whom had been revised to 1st MTPJ fusion. Bhavikatti reported 59 patients followed up for just over 4 years. The mean AOFAS forefoot score improved from 40 to 89/100, all forefoot calluses resolved and there were 3/59 recurrent hallux valgus.
Nagashima (2007) reported 47 patients who had Hohmann osteotomies to the first ray and Helal osteotomies to the lesser rays, with a median 5.6y follow-up. 79% were satisfied; the satisfied patients had continued to improve after surgery while the dissatisfied ones did not.
Takakubo (2010) performed Mann osteotomies of the 1st MT and oblique lesser metatarsal osteotomies, with mean 3.6y follow-up, in 11 patients. The mean Japanese Foot Society score improved from 44 to 72 and three patients had recurrent hallux valgus.
Niki (2010) performed Lapidus procedures with basal shortening osteotomies of metatarsals 2-4 and distal 5th metatarsal osteotomies in 39 feet, with mean 3y follow-up. The mean Japanese Foot Society score improved from 52 to 90, all calluses disappeared and there were no recurrent deformities. While the Lapidus procedure is not indicated as a routine hallux valgus treatment, it may have a rationale in the presence of severe rheumatoid flatfoot, but this was not discussed in Niki’s paper.

In addition, van der Heide (2009) described PIPJ excision and open reduction of the lesser MTP joints for rheumatoid lesser toe deformities. 31 patients also had 1st MTP fusions, their mean foot function index scores reduced from 43 to 23 and 90% were satisfied. However, in 13 patients who had no 1st MTPJ surgery the FFI reduced only from 44 to 37 and only half were satisfied. There were four recurrent toe deformities.

Most of these series report relatively short term follow-up and it is notable that the highest rate of recurrent hallux valgus (40% recurred, 15% fused) occurred in the series with the longest follow-up at a maximum of 8 years. Clearly good results can be obtained but until better-defined series on modern DMARDs and with longer follow-up are reported, it seems reasonable to offer patients joint conservation where possible but to warn that revision may be required, particularly after 5 years or so. Most of these series excluded patients with severe joint destruction, who are still seen requiring surgery and will require a salvage procedure.

 

Salvage Surgery

First Ray

For severe arthritis of the 1st MTPJ the main options are

  • Metatarsal head excision (Mayo)
  • Base of proximal phalanx excision with sort tissue repair (Keller)
  • Fusion
  • Interposition or replacement arthroplasty

Each of these may be combined with a variety of lesser ray procedures and vice versa. However, the majority of reports in the literature describe lesser metatarsal head excision with either excision of the first metatarsal head or fusion of the 1st MTP joint.

There is one RCT. Grondal (2006) randomized 31 patients to Mayo arthroplasty or fusion, with lesser metatarsal head excision. 29 patients had clinical follow-up, FFI scoring and pedobarography at a mean of 6 years. There were no differences in FFI scores or satisfaction scores between the groups. The centre of pressure was significantly medialised in the Mayo patients compared to non-rheumatoid controls but not the fusion group. The main weakness of this study is the relatively low power, but there were no obvious trends that might be more apparent in a larger study.

Two larger retrospective comparative studies were reported by Vandeputte (1999) and Mulcahy (2003). Vandeputte found no clinical difference between 1st MTP fusion/ lesser metatarsal head excision and Keller/1st metatarsal head excision, though the pressures under the first metatarsal were higher in the Keller group. Mulcahy, however, reported increased patient satisfaction, less forefoot pain and higher AOFAS scores as well as less abnormal pressure distribution in patients with either 1st MTP fusion or unoperated first rays, as compared with all excision arthroplasties. In a smaller series of 58 patients, Rosenbaum (2011) reported no difference in foot function index or satisfaction between 1st MTP fusion or metatarsal head excision (with lesser metatarsal head excision in both groups), although once again pedobarography studies were more normal in the fusion group.

Overall, these comparative studies do not consistently support the widely held preference for 1st MTP fusion. Foot pressures are generally more improved following fusion, but in most cases this does not result in predictably improved clinical outcomes.

A few studies have reported silastic implant arthroplasty for RA. Hanyu (2001) reported 12-year results in 39 patients with good pain relief in 79% and satisfaction in 92%. Silicone synovitis was present in 21% and recurrent hallux valgus in 19%; grommets were not used and metatarsus primus varus was not corrected by osteotomy. Two RCTs have compared 1st MTP joint replacement to fusion and found no difference in outcome, but RA was an exclusion for both these studies.

Lesser Rays

Most series describe lesser metatarsal head excision, which can be done through transverse dorsal or plantar incisions, or multiple longitudinal incisions. Provided a smooth curve is obtained with no prominent heads or spikes this generally gives satisfactory results at the cost of shortening the foot. Mulcahy’s (2003) series is the only one to offer a little comparison between different methods, but not enough to prefer one method over another. Case series such as those of Mann (1984), Coughlin (2000), Karambande (2007) give a picture of fusion – resection while Harris (1997), Scott (2005) and Reize describe resection of all the metatarsal heads.

An alternative option is to preserve the metatarsal length with an excision arthroplasty of the proximal phalanx and repositioning of the plantar plate (Stainsby procedure). Briggs (2001) reported 93% of patients pain-free at 5y follow-up after Keller procedure to the great toe and Stainsby procedures to all lesser toes, mostly for inflammatory arthritis. Valgus position of all the lesser toes occurred in 20% but was asymptomatic. In the UK the Stainsby procedure is often combined with a 1st MTP fusion but few results have been reported.

Surgical Approaches

Most older papers describe a transverse plantar approach for lesser metatarsal head excision, giving access directly to the prominent metatarsal heads. Often the 1st metatarsal head was also excised through this incision, although sometimes a medial or dorsomedial approach was used. Fowler (1959) added the excision of an ellipse of skin to draw the fat pad down, and this has been repeated by other authors eg Kates et al (1967). As Stainsby (1997) and Briggs (2001) showed, excision of a skin ellipse in unnecessary – the fat pad is controlled by its enclosing plantar fascia and will reduce with the plantar plate.

Concern about wound healing with a plantar approach, and the need to avoid early weightbearing, led to the use of dorsal approaches. A transverse dorsal approach gives excellent access to all MTP joints. Alternatively, longitudinal approaches on the first ray and 2nd and 4th intermetatarsal spaces also allow surgery on each MTPJ. For phalangectomies, incisions running into the toes are required. Briggs and Stainsby (2001) designed curved incisions in each to after studies on digital skin perfusion, and with careful soft tissue handling these heal with few problems.

In fact, plantar incisions generally heal with few problems. Barton (1973) reported 38% wound problems, but most series report 10% or fewer; indeed, van Loon (1992) had more wound healing problems (though fewer calluses) with dorsal incisions. It has been suggested that multiple dorsal incisions make it more difficult to resect metatarsal heads in a smooth arc, but Coughlin (2000) achieved a good arc in 45/47 feet. Patients who have plantar incisions are usually advised to avoid forefoot weightbearing in the early post-operative phase (eg Karambande 2007), which may interfere with rehabilitation in patients with multiple joint problems and poor balance.

 

Summary

Many rheumatoid patients have relatively low functional demands and can get useful improvements in their pain from most of the standard procedures provided these are well performed with attention to careful tissue handling, reducing the plantar fat pad and, where metatarsal heads are excised, obtaining a smooth curve. Our local preference has been a first MTPJ fusion with Stainsby procedures to the lesser rays. We generally discuss the option of a Keller procedure instead of a fusion and some less active patients prefer this as recovery is generally quicker.

 

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Jim Barrie - Last updated 2010