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Background: Pedal forefoot fat pad atrophy is associated with pain, decreased tissue thickness, and increased foot pressures. To date, no objective studies investigating the use of fat grafting to the forefoot have been performed. We hypothesize that autologous fat injections into the forefoot can reduce pain, increase tissue thickness, and decrease pedal pressures in patients with fat pad atrophy.
Methods: A randomized cross-over study of 30 patients was performed to assess tissue thickness, pain and foot pressures. Tissue thickness was assessed by ultrasound and pedal pressures were assessed by pedobarograph. Pain scores were measured using the validated Manchester Foot Pain and Disability Index. The intervention group (Group 1) underwent fat grafting immediately, followed by evaluation at 2 weeks, 4 weeks, 2 months, 6 months, 12 months, 18 months, and 24 months. The standard of care group (Group 2) underwent conservative management for 1 year, and then crossed over into the active group with 1 year of follow-up. An interim analysis was performed with significance set at p<0.05.
Results: 17 patients (3 male, 14 female) comprised Group 1 and 13 patients (3 male, 10 female) comprised Group 2. Mean age was 59±7.9 years in Group 1 and 63.2±14.1 years in Group 2 (p=0.04). Mean BMI was 26.8±4.8 kg/m2 in Group 1 and 25.1±4.6 kg/m2 in Group 2. Etiologies for fat pad atrophy included failed neuroma surgery, prior foot surgery, steroid injections, and overuse. 11 patients in Group 1 underwent bilateral injections with a mean volume of 4.7cc per foot and 2 patients underwent bilateral injections in Group 2 with a mean volume of 4.6 cc per foot. Mean follow-up time for Group 1 was 4.2±3.7 months and mean follow-up time for Group 2 was 8.0±4.0 months. At 6 months after fat injection, Group 1 demonstrated improved foot function (p=0.01), improved foot appearance (p=0.019), improved pain (p=0.004), and improved work/leisure activities (p=0.006). Group 2 demonstrated no significant changes in foot pain or disability over 6 months of standard of care. Mean tissue thickness over the metatarsals increased significantly in both feet immediately after fat injections (p0.004), and at 2 months (p<0.02); however by 6 months, only the right foot maintained an increase in tissue thickness (p=0.05). There was no significant difference in tissue thickness in Group 2 at 6 months of standard of care. At 6 months, Group 1 had significant decreases in standing foot pressure and force (p<0.04), while in Group 2, there were significant increases in foot pressure and force with both walking and standing (p<0.02). Multivariate regressions did not reveal any significant relationships between BMI, tissue thickness, or volume of fat injected with pain scores or pedobarographic data.
Conclusion: Despite decreasing tissue thickness over time, fat grafting for forefoot fat pad atrophy significantly improves pain and disability outcomes, decreases foot pressures and forces, and prevents against worsening foot pressures and forces. Pedal fat grafting is a safe, minimally invasive approach to treat fat pad atrophy with minimal downtime. Future analysis will reveal whether fat grafting has lasting efficacy.