Diagnostic Modeling for Pedal Fat Pad Atrophy

Human feet must bear the entire weight of the body. Feet have fat pads on their plantar
surface that act as shock absorbers between the skin and bone. However, repetitive mechanical
stress throughout a person's lifetime leads to gradual atrophy of these fat pads. In addition
to this age-related degeneration, fat pad atrophy can be caused by other mechanisms such as
abnormal foot mechanics, steroid use, and collagen vascular disease. Regardless of the cause,
many patients with plantar fat pad atrophy experience considerable pain and loss of function.

Previous studies have negatively correlated plantar soft tissue thickness with plantar
pressure, with the loss of plantar fat being a fundamental mechanism associated with
pressure-related foot disorders. Increased pressure from fat pad atrophy is commonly managed
with padded socks, insoles, and shoe modification. However, these extrinsic strategies are
totally dependent on patient compliance, and devices must be replaced as soon as they begin
to break down. Another treatment option includes silicone injections into the plantar aspect
of the foot. In one study, patients receiving silicone treatment experienced increased
plantar tissue thickness and decreased plantar pressure, but these cushioning properties
decreased over time and the need for additional booster injections was ultimately suggested.
Furthermore, silicone has been known to migrate away from the injection site and has been
found in the inguinal lymph nodes of patients.

A different strategy that is gaining momentum is autologous fat grafting to the foot. Taking
a patient's own tissue, often from the abdomen or thigh, and transplanting it to areas of
plantar fat pad atrophy may reduce pressure in a more natural and permanent manner. Only one
study to date has been published on autologous fat grafting to the foot, but the patients
were receiving concurrent surgical procedures with their fat grafting and the results were
reported subjectively by the patients.

In this study, the investigators hypothesize that there is a difference in plantar tissue
thickness, plantar pressure, and pain score in patients diagnosed with plantar fat pad
atrophy compared to healthy, foot-type matched controls. Results will be measured objectively
using ultrasound for tissue thickness, optical pedobarograph for plantar pressure, and
Manchester foot pain and disability index (MFPDI) for pain score. Furthermore, the
investigators predict that these results will help establish criteria for fad pad atrophy
diagnosis in the clinic as well as determine which patients would receive greatest benefit
from fat grafting to the foot.

Inclusion Criteria:

1. Aged 18 years or older

2. Patients without foot pain at the plantar surface of the foot near the head of the
metatarsals

3. 6 months post any surgical intervention to the foot

4. Subjects must be determined by the PI or a Co-Investigator to not suffer from pedal
pad atrophy

Exclusion Criteria:

1. Age less than 18 years

2. Inability to provide informed consent

3. Feet with open ulcerations or osteomyelitis

4. Diabetics: Type I and II

5. Active infection anywhere in the body

6. Diagnosed with cancer within the last 12 months and /or presently receiving
chemotherapy or radiation treatment

7. Pregnancy

8. Tobacco use: Last use within 1 year per patient report