SLR - September 2016 - Byron Collier

Autologous Fat Grafting for Pedal Fat Pad Atrophy: A Prospective Randomized Clinical Trial

Reference: Gusenoff JA, Mitchell RT, Jeong K, Wukich DK, Gusenoff BR. Autologous Fat Grafting for Pedal Fat Pad Atrophy: A Prospective Randomized Clinical Trial. Plast Reconstr Surg. 2016 Jul 5. [Epub ahead of print]

Scientific Literature Review

Reviewed By: Byron Collier, DPM
Residency Program: Mount Auburn Hospital

Podiatric Relevance: The treatment of fat pad atrophy is plagued with difficulty. Age, obesity, pathologic foot mechanics (both cavus and planus foot types), poor shoe gear, iatrogenic causes (steroid injections and surgery) and certain disease states, such as diabetes and collagen diseases, may all result in fat pad atrophy. To complicate the matter, fat pad atrophy is a diagnosis of exclusion as tissue thickness guidelines have not been formally defined. Even after the diagnosis is finally determined, current nonsurgical treatment options are limited (supportive shoes, orthotics and padding), and reliable surgical options are few with mixed results. The use of an autologous graft has distinct benefits, and autologous fat grafting has shown positive outcomes in preliminary studies. However, the studies that exist have been limited. This study is the first prospective randomized study evaluating the efficacy of pedal fat pad grafting in reducing pain, increasing plantar tissue thickness and decreasing pedal pressures.  

Methods: A randomized clinical trial of patients with metatarsalgia and fat pad atrophy were treated with either autologous fat grafting (Group 1) or nonoperative measures (Group 2). Metatarsalgia and fat pad atrophy were diagnosed by a foot and ankle specialist. Patients were excluded if they had received any surgical intervention or injections in the foot within the last 6 months, wounds/ulcerations, infection, diabetes, diagnosis of cancer within the last 12 months, treatment with chemotherapy or radiation, known coagulopathy or systemic disease that would place the patient at undue risk, pregnancy or history of tobacco use. Patients in Group 1 were limited to a single pedal fat graft during the study window. This operative group was allowed protected weightbearing in an offloaded sneaker immediately postoperatively but were instructed to limit strenuous activity for 4 to 6 weeks with no barefoot walking permitted. Group 1 was then followed at 2 weeks, 4 weeks, 2 months, 6 months and 12 months. The patients in Group 2 were treated nonoperatively and were followed at 6 months and 12 months.

The primary outcome measure was plantar tissue thickness under the metatarsal heads measured using ultrasound at 6 and 12 months. Secondary outcome measures included pedobarographic data utilizing a Tekscan HR Mat and Research Foot Module to measure mean walking and standing foot pressures, standardized photos of the foot and callus patterns, foot pain and disability measured using the Manchester Foot and Disability Index. The autologous fat pad group was also assessed for procedure safety measures and for complications.

Results: Thirteen patients (2 male, 11 female) were randomized into the treatment group (Group 1) and twelve patients (4 male, 8 female) into the nontreatment group (Group 2). The patients from Group 1 and Group 2 were found to have a baseline age of 59±5.3 and 65.3±8.5 years, and baseline BMI were 27.2±5.4 and 25.6±6.1 kg/m2, respectively. Ten patients in the treatment group underwent bilateral grafting, and mean volume of graft was 4.8±0.8 mL in the right foot and 4.7±0.7 mL in the left foot. Average patient follow-up was 11.1±5.4 and 13.8±4.2 months, respectively, for Groups 1 and 2. The primary outcome measure tissue thickness was measured under each metatarsal and averaged for each foot in order to generalize data. There was no significant difference between both study groups' tissue thickness at baseline. At 6 months' follow-up, the average tissue thickness in Group 1 was found to be significantly greater in the left foot when compared to Group 2 (p = 0.005). However, at 12 months' follow-up, there was no significant difference found between mean tissue thickness.

Group 1 was found to have statistically significant improvement in pain at 6 months' follow-up (2.8±2.4 vs 5.5±2.6, p = 0.02). At 12 months' follow-up, the treatment group had significant improvement in function (p = 0.039), pain (p = 0.019) and work/leisure activities (p = 0.002). Group 1 also had statistically significant improvement in function (p = 0.013), pain (p = 0.005) and work/leisure activities (p = 0.014) from baseline at 6 months' follow-up. Group 1 continued to show improvement in these areas without significant change at 12 months' follow-up.

No significant differences were found between the groups at baseline with mean walking and standing foot pressures. Walking left foot pressures were found to be lower in Group 1 at 6 months' follow-up (p = 0.041). At 12 months' follow-up, left foot standing foot force, right foot walking foot force and left foot standing pressure were found to be lower in Group 1 (p values of 0.017, 0.013 and 0.042, respectively). A majority of patients from Group 1 had postoperative bruising at the donor site and feet. None of the treatment group received perioperative antibiotics or narcotics. There was no report of infection, hematoma, seroma or oil cysts in the treatment group.

Conclusions: Authors concluded that fat grafting to treat forefoot fat pad atrophy significantly improves pain and disability outcomes, decreases foot pressures and forces, and prevents against worsening foot pressures and forces. These findings were more pronounced at the 6-month follow-up, and most outcome measures lost statistical significance by 12 months post treatment. Although randomized, there were a number of study limitations, including a small sample size. While statistically significant, a larger population would be required for clinical significance. There were also differences in the frequency of follow-up visits between groups, and assessments were nonblinded. Further studies will be needed to explore the long-term outcomes of autologous fat grafting, but autologous fat grafting appears to be a promising treatment option for select patients who have failed nonsurgical treatment.

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