Leprosy remains a disabling neglected tropical disease in which peripheral nerve damage turns the foot into an insensate, deformed and ulcer-prone structure. This narrative review synthesizes the evidence published between 2015 and 2024 on the mechanisms, risk factors and preventive strategies for plantar ulceration and grade 2 disability in the neuropathic foot of leprosy, organized into five thematic axes. The pooled prevalence of plantar ulcer is around 34% in people with foot anaesthesia and 7% among all people affected by leprosy, and grade 2 disability affects roughly one fifth to one third of newly detected cases depending on the setting. Sensory loss, motor paralysis of the intrinsic muscles and foot drop shift plantar pressure toward the metatarsal heads and the calcaneus. Self-care programmes, appropriate footwear, offloading and surgical resection of plantar bony prominences reduce ulceration and recurrence, although most of this evidence is observational or comes from small trials. Delayed detection and the weak integration of foot care into leprosy services sustain disability. The findings support early neurological assessment, structured self-care, footwear provision, offloading and integrated disability prevention within leprosy control programmes, together with a research agenda of comparative studies specific to the leprosy foot rather than extrapolation from the diabetic foot.
La lepra sigue siendo una enfermedad tropical desatendida e incapacitante en la que el daño nervioso periférico convierte el pie en una estructura insensible, deformada y propensa a las úlceras. Esta revisión narrativa sintetiza la evidencia publicada entre 2015 y 2024 sobre los mecanismos, factores de riesgo y estrategias de prevención de la ulceración plantar y la discapacidad de grado 2 en el pie neuropático de la lepra. La prevalencia combinada de úlcera plantar es del 34% en personas con anestesia del pie y del 7% entre todas las personas afectadas, y la discapacidad de grado 2 alcanza a una quinta o una tercera parte de los casos nuevos. La pérdida sensitiva, la parálisis de los músculos intrínsecos y el pie caído desplazan la presión plantar hacia las cabezas metatarsianas y el calcáneo. El autocuidado, el calzado adecuado, la descarga y la resección de las prominencias óseas reducen la ulceración y su recurrencia, aunque la mayor parte de esta evidencia es observacional o de ensayos pequeños. La detección tardía y la escasa integración del cuidado del pie en los servicios de lepra mantienen la discapacidad. Los hallazgos respaldan la evaluación neurológica temprana, el autocuidado estructurado, la provisión de calzado, la descarga y la prevención integrada de la discapacidad dentro de los programas de control, junto con una agenda de investigación específica del pie leproso, no extrapolada del pie diabético.
Leprosy is a chronic granulomatous infection caused by Mycobacterium leprae that principally affects the skin and the peripheral nervous system, and its capacity to injure nerves makes it a leading infectious cause of preventable disability.
The neuropathic foot of leprosy has received less integrated attention than the diabetic neuropathic foot, despite a comparable pathomechanics of sensory loss and raised plantar pressure.
The objective of this review was to synthesize the current evidence on the mechanisms, risk factors and preventive strategies for plantar ulceration and grade 2 disability in the neuropathic foot of leprosy. The review was guided by five questions that correspond to its thematic axes: which peripheral nerve and biomechanical alterations render the foot prone to ulceration; which epidemiological patterns and risk factors predict ulceration and grade 2 disability; which interventions prevent the first ulcer; which interventions prevent recurrence and progression to fixed disability; and which programmatic strategies integrate foot care into leprosy services.
A documented search was conducted in Scopus and PubMed, restricted to records published between 2015 and 2024 to match the reference window of the target volume.
Five core queries combined leprosy with terms for the foot, plantar ulceration, neuropathy, disability and grade 2, footwear, offloading, orthoses, self-care and education, using Scopus field syntax with publication-year limits. Four supporting queries covered reconstructive surgery and tendon transfer in leprosy, plantar pressure in peripheral neuropathy, the diabetic neuropathic foot, and the epidemiology of leprosy disability, without a lower year limit. Full query strings are available from the authors. The queries returned 635 candidate records, and after removal of duplicates and screening of titles and abstracts, 56 records were retained. Records were selected when they addressed the leprosy foot, plantar ulceration or leprosy-related disability directly, and primary studies, systematic reviews, clinical guidelines and book chapters were preferred over redundant reviews and case reports without plantar involvement. Works on the diabetic foot were retained only as comparators for the discussion.
Eligible records were read and organized into a matrix of five thematic axes, in which each axis lists the assertions of the synthesis and the studies that support or contradict them together with their design and limits. The five axes are reported in that order, each synthesis statement is accompanied by the number of studies that support it, and a summary matrix table condenses the axes. Because this is a narrative review, no exhaustive screening protocol or risk-of-bias instrument was applied, and the synthesis does not claim the completeness of a systematic review. Study quality was described from the design stated in each record, and conclusions were tempered where the evidence was observational, small or preclinical.
The synthesis is organized in five thematic axes that move from the mechanisms that render the foot vulnerable, through the epidemiology and risk factors of ulceration and disability, to the interventions that prevent the first ulcer, those that prevent recurrence and fixed deformity, and finally the health service arrangements that deliver them. A summary matrix precedes the narrative (Table 1).
Table 1. Synthesis matrix of the evidence on the neuropathic foot in leprosy by thematic axis.
Thematic axis | Key findings | Studies (n) | Predominant evidence |
|---|---|---|---|
Neuropathy and biomechanical alterations | Sensory and motor nerve damage shift plantar pressure toward the metatarsal heads and the calcaneus | 15 | Cross-sectional and biomechanical studies, case series |
Epidemiology and risk factors of ulceration and disability | Pooled plantar ulcer prevalence of 34% with foot anaesthesia and 7% overall; G2D in 20-30% of new cases | 13 | Systematic reviews, registry and cross-sectional studies |
Prevention of the first ulcer | Self-care, footwear and orthoses are the mainstay, with modest direct evidence | 10 | Reviews, comparative studies, technical reports |
Prevention of recurrence and fixed disability | Offloading, biological adjuvants and bony prominence resection heal ulcers; recurrence depends on footwear use | 18 | Small randomized trials, retrospective cohorts, case series |
Programmatic and health service strategies | Integrated foot care and early detection reduce disability; delayed detection sustains it | 10 | Policy documents, systematic and cross-sectional studies |
Note: G2D = grade 2 disability. Study counts refer to the records cited within each axis of this review. Source: Elaboration of the authors from the 56 records included in the narrative synthesis.
Fifteen studies describe the sequence by which nerve injury turns the leprosy foot into a mechanically dangerous structure. Of these, the disease primers and clinical reviews agree that the predilection of M. leprae for Schwann cells produces a multifocal neuropathy whose clinical expression in the foot combines loss of protective sensation, paralysis of the intrinsic muscles and autonomic failure of sweating and skin lubrication.
Instrumented studies quantify the biomechanical consequence of this neuropathy. Among them, a baropodometric and posturographic comparison of 22 patients with multibacillary leprosy and 17 controls showed altered plantar pressure distribution and postural control in the affected group, and argued that instrumented assessment anticipates damage better than the monofilament alone.
Surgical reconstruction addresses the two extremes of this cascade. Three studies report that tendon transfer, with the tibialis posterior as the donor muscle, restores active dorsiflexion in foot drop and improves the mechanics of gait, and one of them links the correction to measurable gains in quality of life.
Thirteen studies quantify the burden of ulceration and disability and identify its predictors. The single meta-analysis of this literature pooled 15 studies and estimated a plantar ulcer prevalence of 34% among people with foot anaesthesia and of 7% among all people affected by leprosy, with the inability to feel a 10 g monofilament, a pronated foot and a high peak plantar pressure reported as the leading risk factors.
Grade 2 disability shows a wide but consistently elevated range across settings. A population-based analysis of 10,758 newly detected cases in Yunnan classified 20.2% as grade 2 and 10.6% as grade 1.
The longitudinal and childhood data close the picture. One multicentre longitudinal study from India documented that the risk of developing leprosy-related disability accumulates over long-term follow-up.(25) A retrospective cohort of 200 patients observed that new deformities continued to appear during seven years of follow-up, with the feet affected in 39.8% of deformities.(26) A study of discharged patients with plantar lesions in a dermatology referral unit found that the disabilities caused by those lesions persist long after treatment, which links ulceration to the stigma of advanced disease.(27) Grade 2 disability is not limited to adults, since a record-based analysis of children and adolescents in India found the same risk gradient with delayed detection.(28) Taken together, these studies support the conclusion that ulceration and disability are late markers of a detection and nerve protection gap rather than unavoidable consequences of infection.
Ten studies inform the prevention of the first ulcer, and the evidence concentrates on three levers: self-care, footwear and pressure management. Of these, a scoping review of self-care programmes for people living with leprosy mapped the characteristics and reported outcomes of these programmes.(29) In one of them, a qualitative account described the experience of receiving and practicing self-care and the sense of control it conferred on people affected by leprosy.(30) A practical guide chapter on the prevention of disability and ulcer care consolidates the routine into a structured sequence of inspection, skin care and footwear use.(31) The convergence of these three sources indicates that self-care is a behavioural intervention with a coherent rationale even though its effect has not been isolated in a controlled design.
Footwear and orthoses are the most specific preventive measure in this axis. Three studies support appropriate footwear and orthoses as essential components of the management of the foot at risk, because they redistribute load away from the metatarsal heads and protect skin that no longer feels.(32-34) In one comparative study, computer-assisted customized footwear and traditional microcellular rubber footwear were compared for the prevention of ulcer recurrence in patients with sensory loss.(33) A technical report of a computer-designed orthotic device showed that offloading of an established plantar ulcer could be planned from pressure mapping rather than from clinical impression alone, which makes the prescription reproducible across practitioners and reduces the dependence on the individual skill of the prescriber.(34) The measurement that supports these prescriptions is likewise reproducible, since a short report demonstrated that a customized tactile feedback system identifies peak plantar pressure in the neuropathic foot and can guide where relief is most needed.(35) Acceptance is the main operational limit, and one short report on traditional offloading devices found that uptake and adherence among people affected by leprosy were incomplete, which tempers the effectiveness observed under controlled conditions and points to cost, comfort and stigma as barriers.(36)
The relation between pressure and sensation carries the preventive logic of this axis. The study that correlated dynamic pressure with monofilament thresholds concluded that both should be assessed before orthotic prescription, because pressure can concentrate in areas that retain partial sensation and vice versa.
Eighteen studies address the treatment of the established ulcer and the prevention of its recurrence and of fixed deformity. The clinical reviews and the Cochrane synthesis agree that the core is debridement, control of infection, relief of pressure and optimization of blood flow, and that the approach used for the diabetic foot has been transferred to leprosy without sufficient leprosy-specific trials.
Offloading is the intervention with the most direct evidence. An observer-blind randomized trial compared autologous platelet-rich plasma added to total contact casting against casting alone for trophic ulcers and reported that the combined approach improved healing, which supports pressure relief as the backbone and the biological adjunct as an accelerator.
Biological and topical adjuvants have been tested in small trials. Of these, a randomized trial of 32 patients found that adipose mesenchymal stem cell-conditioned medium reduced ulcer size and depth faster than framycetin gauze from the second and third weeks onward, without adverse reactions.
Infection complicates every one of these approaches. One microbiological study documented bacterial biofilm in leprosy plantar ulcers, and another identified Streptococcus dysgalactiae subsp. equisimilis as an emerging secondary pathogen, both of which argue for microbiologically guided rather than empirical treatment and explain why ulcers that are well offloaded can still fail to heal.(48,49) Surgery closes the loop for ulcers seated on bony prominences. The largest retrospective series, of 234 patients, resected the prominence and closed the lesion with a bipediculated local flap, achieving healing in a mean of 12 weeks, with shorter times when orthopedic shoes and insoles were used and when dressing was performed by trained staff.
Ten studies bear on the organization of care. The World Health Organization strategy for 2021 to 2030 frames disability prevention, including the foot, as a pillar of leprosy control and sets a 90% reduction in new grade 2 disability among its measurable targets.
The main health system obstacle is delayed detection. A systematic review of 20 studies identified misdiagnosis and deficiencies in referral and case-detection methods as the principal healthcare-related causes of delay, and these delays are in turn the strongest modifiable predictor of disability.
The consequences of failing to integrate foot care are measurable. A cross-sectional study of 267 Indonesian cases applied the SALSA scale and found that only 28.5% were free of activity limitation, with 43.8% mildly, 13.5% moderately and 14.3% severely or extremely limited, and with worse scores among those with higher disability grades.(51) A study of leprosy and lymphatic filariasis disability in Mozambique documented the psychosocial burden that accompanies these limitations and the exclusion that follows from visible foot deformity.(52) A Global Burden of Disease analysis for Brazil quantified the disability attributable to leprosy and its persistence over three decades, which places the foot within a lifelong rather than episodic burden of disease.(53) These studies support the argument that foot care belongs inside a broader rehabilitation and participation agenda rather than at the margin of case detection.
Across the five axes the included studies converge on three points. First, the plantar ulcer is a mechanical event: in every axis that measures it, pressure concentrates on the metatarsal heads and the calcaneus and ulceration follows the same anatomical distribution. Second, prevention is behaviourally mediated, because every intervention that works depends on daily self-care and continuous footwear use, and the studies that measured adherence found it to be the rate-limiting step. Third, the evidence base is lopsided, because the treatment of the established ulcer has attracted a series of small trials while the prevention of the first ulcer has not attracted a single randomized comparison. The main divergence concerns the role of plantar pressure in prescribing orthoses: two studies treat pressure as the primary target of the prescription, whereas two others show that pressure and sensation are only weakly correlated and that sensation must be assessed in its own right.(10,11) The clearest gap is the absence of a cohort study that follows insensate feet from first detection to first ulcer, without which the causal weight assigned to each factor remains inferential and the timing of preventive intervention remains a matter of clinical judgment.
The principal finding of this synthesis is that plantar ulceration and grade 2 disability in leprosy arise from a measurable and modifiable sequence of sensory loss, muscle paralysis and pressure concentration, and that the interventions with the most consistent evidence are exactly those that interrupt this sequence through self-care, footwear, offloading and surgery. The finding is consequential for a podiatric readership because it reframes the leprosy foot from an unavoidable stigma of infection into a mechanical problem that the specialty already knows how to manage, with the same instruments and principles applied to the diabetic foot, provided that the differences between the two underlying neuropathies are respected. The review also shows that the quantity of leprosy-specific evidence is thin relative to the burden, with one meta-analysis and a small number of randomized and comparative studies carrying most of the quantitative weight.(5,38) The consequence is that much of the podiatric advice given for the leprosy foot is borrowed from the diabetic foot; the fit of that borrowing deserves scrutiny rather than assumption.
In relation to previous reviews, this synthesis extends rather than duplicates them. The plantar ulcer meta-analysis quantified prevalence but did not organize prevention by axis.
The biomechanical axis converges with the diabetic foot literature in its emphasis on the metatarsal heads and the calcaneus as the sites of peak pressure, but the analogy has limits. Pressure measurement in diabetes has matured into validated instruments and risk thresholds, whereas in leprosy the correlation between pressure and sensory loss is weak and the instruments are borrowed without equivalent validation studies.(11,37) A review of neuropathic ulcers in leprosy makes the same point directly when it argues that leprosy and diabetes differ immunologically and physiologically and that their wound management cannot simply be transferred.
The comparison with diabetes is most instructive in prevention. The most recent systematic review of ulcer prevention in diabetes reports moderate certainty that temperature monitoring, with a risk ratio of 0.51, and pressure-optimized footwear, with a risk ratio of 0.62, reduce plantar ulcer recurrence, and lower certainty for structured education and integrated care.
The surgical axis explains a finding that otherwise appears contradictory: healing after resection of bony prominences is high, yet recurrence reaches more than half of operated patients. The Brazilian series attribute recurrence to abandonment of footwear, which means that surgery removes the prominence but not the insensate skin, and that the operation is only as durable as the offloading that follows it.(40,41) This is the same principle established for the diabetic foot, where surgical correction without subsequent pressure relief fails in the same way, and where graded-stiffness insoles and footwear are used to protect the healed surface.
On the level of evidence and applicability, the findings sort into three tiers. The burden and risk-factor claims rest on the strongest tier, since they derive from registry analyses, a meta-analysis and repeated cross-sectional studies with consistent direction.
The health service axis connects the clinical findings to the structural cause of disability. Delayed detection, driven by misdiagnosis and weak referral systems, is the strongest modifiable predictor of grade 2 disability, and the risk of new disability continues after release from treatment, which argues for surveillance of the foot as a chronic condition rather than an episode of infection.
Three groups of limitations qualify these conclusions. The limitations of the review itself derive from its narrative design: the search was documented but not exhaustive, only two databases were searched, and the selection and synthesis depended on the judgment of a single reviewer without a risk-of-bias instrument, so some relevant studies may have been missed and the weighting of evidence is qualitative.
For clinicians, the synthesis supports a sequence of monofilament and pressure assessment, structured self-care education, footwear prescription and early referral of established ulcers for offloading and prominence surgery, delivered as one package rather than as isolated acts.(31,32) The clinical examination remains central, because pressure and sensation diverge and neither substitutes for the other, and because the monofilament test remains the field standard for the protective threshold that footwear is meant to compensate.(11) For programmes, it supports integrating foot care into leprosy services with continuous footwear provision and post-cure surveillance, because disability accrues before detection and after treatment, and because footwear that depends on out-of-pocket purchase fails exactly when it is most needed.
The neuropathic foot of leprosy becomes ulcer-prone through combined sensory loss, intrinsic muscle paralysis and raised plantar pressure concentrated on the metatarsal heads and the calcaneus. Plantar ulceration affects about one third of people with foot anaesthesia and grade 2 disability affects one fifth to one third of newly detected cases, with delayed detection, male sex and older age as the main predictors. Self-care programmes, appropriate footwear and offloading prevent the first ulcer and its recurrence, although their direct evidence remains modest. Offloading, biological adjuvants and resection of plantar bony prominences heal established ulcers, but recurrence depends on continuous footwear use. Integrated foot care with early detection and post-cure surveillance is the programmatic condition that converts these clinical measures into sustained prevention of disability.
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Drafting – original draft: Paloma Gargalho Nascimento.
Writing–review and editing: Paloma Gargalho Nascimento.