Preliminary investigation of debridement of plantar callosities in rheumatoid arthritis

J. Woodburn, Z. Stableford1 and P. S. Helliwell

Rheumatology and Rehabilitation Research Unit, University of Leeds, 36 Clarendon Road, Leeds LS2 9NZ and
1 Department of Podiatry, St Mary's Hospital, Greenhill Road, Leeds LS12 3QE, UK


    Abstract
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 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Objective. To determine the effect of expert debridement of foot callosities on forefoot pain and plantar pressure distribution in rheumatoid arthritis (RA).

Methods. Plantar callosities on 14 feet of eight RA patients were debrided by a single podiatrist. Measurements of subjective pain severity in the forefoot and global arthritis pain were undertaken using a visual analogue scale, repeated at 7-day intervals to the next treatment (28 days). Plantar pressures were recorded at the lesion sites using an in-shoe flexible transducer insole before and after lesion debridement.

Results. Following debridement, all patients reported symptomatic relief with an average change in pain score of 48% (P = 0.01) but the treatment effect was lost by 7 days. Immediately following scalpel debridement, peak pressures were elevated in 10 of 14 feet, whilst contact time was reduced and peak force increased. None, however, reached statistical significance.

Conclusion. Scalpel debridement of forefoot plantar callosities reduces forefoot pain for about 7 days, but pressure distribution is not significantly altered.

KEY WORDS: Plantar callosities, Foot, Plantar pressure measurement, Subjective pain severity, Rheumatoid arthritis.


    Introduction
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
In rheumatoid arthritis (RA) metatarsal heads, prominent in the presence of severe forefoot deformity, are subject to excessive shear and compressive forces during gait. These stresses stimulate the stratum corneum to produce well-circumscribed painful lesions, known as callosities [1, 2]. In the well-studied diabetic foot, plantar callosities are highly predictive for ulceration yet regular debridement has been shown to reduce peak pressure, prevent ulceration and facilitate wound healing [3, 4]. Little is known about the efficacy of this treatment for the purposes of pain relief in RA. Therefore, the aim of this preliminary study was to investigate the effect of callus debridement on painful foot symptoms and any alteration to the plantar pressure distribution in the forefoot.


    Patients and methods
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Patients
This study was undertaken with local research ethics committee approval. Eight patients with RA fulfilling the 1987 American College of Rheumatology criteria set were studied; all gave informed consent. Patients were included if they presented with one or more callus overlying the plantar metatarsal head region. A callus was defined as a diffuse area of hyperkeratosis of relatively even thickness without a central core (or corn). Patients were excluded where a lesion was accompanied by active bursitis (n = 1), or if immediately following debridement ulceration was found beneath the hyperkeratotic tissue (n = 2).

Intervention
The hyperkeratotic tissue was debrided using a sterile scalpel blade; all procedures were undertaken by the same experienced podiatrist. There was no alteration to the patients' footwear or orthosis use over the duration of the study.

Pain assessment
A 100 mm visual analogue scale (VAS) was used to record pain in the forefoot, separately for left and right feet, and global arthritis pain. Foot pain was recorded following an 8 m walking exercise before and after callus debridement. Patients were asked to repeat the pain measurements at 7-day intervals until the next treatment (28 days).

Plantar pressure measurements
Plantar pressure measurement was conducted prior to and immediately after callus debridement using a flexible 2 mm thick in-shoe insole constructed from a matrix array of 99 capacitance transducers (EMED Pedar, Novel GmbH, Munich, Germany). From the lesion sites, peak pressure (kPa), peak force (N), and contact time (ms) were calculated.

Statistical analysis
Statistical analysis involved the Wilcoxon signed rank test for forefoot and global arthritis pain over the six time points and Student's t-test for pre- and post-treatment pressure variables. Data were expressed as median (interquartile range) or mean (S.D.) whilst P values of <0.05 were considered statistically significant.


    Results
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 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Demographics and clinical details
A total of eight patients was enrolled, six female and two male. The age of the patients ranged from 49 to 70 yr (mean 58.5 yr) and disease duration from 8 to 43 yr (mean 18.3 yr). The level of disability, as measured by the Stanford health assessment questionnaire, ranged from 1 to 3 (mean 1.75). Twenty-six plantar lesions from 14 feet were treated. The lesions were distributed over the central metatarsal heads in different configurations with the third metatarsal head involved most frequently either alone or in combination with other sites.

Foot and global arthritis pain
The VAS forefoot pain scores are shown in Fig. 1Go. A significant reduction in VAS forefoot pain was achieved for the immediate post-treatment time point only [24 mm (12, 43)] when compared with pre-treatment data [59 mm (37, 76)], P = 0.01. There was no statistically significant difference in the recorded global arthritis pain scores over the duration of the study.



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FIG. 1. Boxplot of VAS forefoot pain over duration of study. The box represents the interquartile range, the line across the box is the median and the whiskers represent the range.

 

Plantar pressures
From Table 1Go it can be seen that peak pressures were elevated immediately following scalpel debridement, whilst contact times on the painful forefoot were reduced and peak forces elevated. None, however, reached statistical significance.


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TABLE 1. Pressure, force and contact time variables pre- and post-callosity debridement

 


    Discussion
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 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Scalpel debridement has a significant immediate impact on forefoot pain. Pain in all 14 feet was improved, with an average reported change in pain score of 48%. This did not surprise us, the treatment being the equivalent of removing a troublesome object from the shoe, likened to a stone, pebble or marble by patients when describing symptoms. The treatment effect was disappointingly short. Differences in mean values between review periods reaching statistical significance for only 7 days, returning to baseline at 28 days. There was no significant change in global arthritis pain over the duration of the study.

In 10 of 14 feet, peak pressures increased on average by 17% ranging from 4 to 85% following lesion debridement, but differences did not reach statistical significance. This is in contrast to the findings of Young et al. [4] in the diabetic foot where peak pressures were reduced following debridement in 37 of 43 forefoot lesions, and elevated at six sites, all under prominent metatarsal heads. The callosities seen in this study were stiff and larger than the weight-bearing surface of the corresponding metatarsal head. When debrided, the underlying healthy tissue was more viscoelastic conforming to the geometry of the metatarsal head under load. Thus, ground reaction forces towards the propulsive stage of gait were distributed over a smaller contact area, with an increase in peak pressure. Furthermore, temporary reduction of pain with a reduction in contact time at the painful sites may have been responsible for the generation of elevated peak force following debridement.

In summary, scalpel debridement is a quick and simple intervention to perform for painful plantar callosities in RA. An immediate reduction in symptoms in most cases should be expected but the treatment effect is lost within 7 days. Whilst patients may be receptive to this form of treatment, our preliminary findings suggest it has no effect on underlying mechanical factors. Indeed, peak pressures may be increased following debridement, possibly increasing the risk of further tissue damage. A larger controlled study is proposed to address both the natural history of plantar callosities and the effect of conservative and surgical management for these painful and disabling lesions.


    Notes
 
Correspondence to: J. Woodburn, Rheumatology and Rehabilitation Research Unit, School of Medicine, University of Leeds, 36 Clarendon Road, Leeds LS2 9NZ, UK. Back


    References
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 

  1. Minns RJ, Craxford AD. Pressure under the foot in rheumatoid arthritis. Clin Orthop Rel Res1984;187:235–42.[Medline]
  2. Woodburn J, Helliwell PS. Relation between heel position and the distribution of forefoot plantar pressures and skin callosities in rheumatoid arthritis. Ann Rheum Dis1996;55:806–10.[Abstract]
  3. Murray HJ, Young MJ, Hollis S, Boulton AJ. The association between callus formation, high pressures and neuropathy in diabetic foot ulceration. Diabet Med1996;13:979–82.[ISI][Medline]
  4. Young MJ, Cavanagh PR, Thomas G, Johnson MM, Murray H, Boulton AJM. The effect of callus removal on dynamic plantar foot pressures in diabetic patients. Diabet Med1992;9:55–7.[ISI][Medline]
Submitted 17 August 1999; revised version accepted 20 December 1999.