Heel Pad Syndrome

Definition

Anatomy of the Heel Pad

• The sole is covered by subcutaneous connective tissue with a septated, chambered architecture
• Each chamber contains fibrofatty tissue enclosed by tough collagen-fiber septa
• These fibrous septa are firmly attached between the plantar aponeurosis and the plantar skin
• An extensive vascular network permeates the septa walls - the plantar sole is one of the most highly vascularized regions of the body surface
• This pressure-chamber design distributes concentrated compressive forces over a wider area, preventing pressure necrosis
• Without this construction, localized stresses during gait would lead to focal tissue damage
• General Anatomy and Musculoskeletal System (THIEME Atlas), p. 496

• Rockwood and Green's Fractures in Adults 10th ed., p. 3492

Pathophysiology

• Aging causes gradual reduction in collagen content, water content, and elastic fibrous tissue
• The result is progressive heel pad atrophy - the fat chambers lose their structural integrity and the pad becomes thinner and less resilient
• This exposes the plantar skin and calcaneal periosteum to higher localized stresses with each step
• Chronic heel pad pain can also result from direct trauma that damages the septated architecture (e.g., after calcaneal fractures or direct blows to the heel)
• The most constant pathological finding in plantar heel pain of any cause is degenerative change in the elastic adipose tissue of the heel pad
• Campbell's Operative Orthopaedics 15th ed., p. 4902
• Rockwood and Green's Fractures in Adults 10th ed., p. 3447

Risk Factors

• Campbell's Operative Orthopaedics 15th ed., p. 4906
• Textbook of Family Medicine 9e, p. 246

Clinical Features

Symptoms

• Pain directly under the heel (central heel), worse with weight-bearing
• Pain is often described as a bruised or dull aching quality (in contrast to the sharp, stabbing pain of plantar fasciitis)
• Pain is diffuse over the entire heel pad, not specifically at the medial calcaneal tubercle
• May be present throughout the day with weight-bearing (unlike plantar fasciitis, which is classically worst with the first steps in the morning)

Physical Examination

• Tenderness in the central portion of the heel pad
• The fat pad is noticeably thin or "empty" on palpation - the calcaneal bone feels close to the skin surface
• No specific tenderness at the medial calcaneal tuberosity origin of the plantar fascia (differentiates from plantar fasciitis)
• No Tinel sign along the tarsal tunnel (differentiates from tarsal tunnel syndrome)
• Miller's Review of Orthopaedics 9th ed., p. 593

Differential Diagnosis of Plantar Heel Pain

• Campbell's Operative Orthopaedics 15th ed., p. 4902, 4906

Investigations

• X-ray: Generally unremarkable; may show calcaneal spur (not diagnostic of heel pad syndrome); heel pad thickness can be measured (normal >21 mm)
• Ultrasound: Can demonstrate reduced heel pad thickness and loss of fibrous septation
• MRI: Best for excluding other causes (stress fracture, Baxter's nerve entrapment, plantar fascia tear); shows reduced fat signal and thinning
• Routine blood tests if inflammatory arthritis suspected (ESR, CRP, RF, HLA-B27)

Treatment

Non-Operative (First-Line)

1. Heel cushions / orthoses - soft, viscoelastic heel cups that mechanically replace the function of the atrophied pad; this is the primary treatment
2. Appropriate footwear - well-cushioned shoes with adequate heel support
3. Activity modification - reduced high-impact activity
4. NSAIDs - for analgesic effect; short-term use
5. Night splints - particularly if concurrent plantar fasciitis component
6. Plantar fascia stretching - if fasciopathy co-exists
7. Local corticosteroid injection is CONTRAINDICATED or used with extreme caution - carries risk of further fat pad necrosis and worsening the condition

• Rockwood and Green's Fractures in Adults 10th ed., p. 3447
• Campbell's Operative Orthopaedics 15th ed., p. 4906

Emerging / Experimental

Operative (Rarely Needed)

Key Teaching Points

• The heel pad is not simply fat - it is a specialized pressure-chamber system with fibrous septa and rich vascularity
• Atrophy results from aging-related loss of collagen, water, and elastic tissue
• Pain is central and diffuse under the heel (not at the medial tuberosity)
• Cortisone injections for plantar heel pain carry a specific risk of precipitating or worsening heel pad atrophy through fat necrosis
• Primary treatment is mechanical replacement with a heel cushion - no effective pharmacological or surgical cure exists for established atrophy
• Always consider bilateral heel pain as a red flag for systemic inflammatory arthritis