Point-Counterpoint: Is Conservative Care The Best Approach For Plantar Fibromatosis?
Injection therapy would seem to be the optimal delivery method for plantar fibromatosis as it allows the intralesional administration of the desired pharmacologic agent. Detractors of injection therapy for plantar fibromatosis argue that it is more difficult and painful to inject a fibrous lesion, and the injected medication may not infiltrate sufficiently to treat the entire fibroma. Many have attempted using medications via intralesional injection for plantar fibromatoses.
Currently, the intralesional infiltration of a corticosteroid into the plantar fibromatosis appears to be the most popular injectable medication. Ketchum and Donahue conducted a four-year study with 63 patients (75 hands) suffering from Dupuytren’s palmar fibromatosis contracture of the hand, a similar but perhaps not entirely identical condition to plantar fibromatosis.2 Physicians injected triamcinolone acetonide (Kenalog, Bristol-Myers Squibb) directly into each nodule in doses ranging from 60 mg to 120 mg per injection. They repeated the injections at six-week intervals for a total of three injections. If further injections were deemed necessary, these only occurred after a six-month hiatus. The patients in their series had a mean of 3.2 total injections per fibroma.
Ninety-seven percent of the hands demonstrated 60 to 80 percent regression of the fibromas with softening and flattening of the nodules.2 Not surprisingly, 50 percent of the patients experienced a reactivation of the disease within one to three years after their last injection, necessitating one or more additional injections. Additionally, as one would expect, 50 percent of patients reported a transient depigmentation or temporary subcutaneous fat atrophy at the injection site.
Ketchum and Donahue did describe two patients who were not included in their four-year study. These patients had spontaneous flexor tendon ruptures after treatment but without the six-month respite after the third injection.2 The authors felt that the likely causes of the patients’ tendon ruptures were additional injections after the initial three that were given without waiting six months after the third injection, and possible failure to keep the medication solely within the lesion.
What About Corticosteroid Injections?
Although there are no major studies looking at the use of corticosteroid injections for plantar fibromatosis, numerous authors mention the treatment modality in their papers as a viable conservative treatment option.3-7
Pentland and Anderson described a patient with bilateral multi-nodular plantar fibromas.4 The patient received five intralesional injections of 15 mg to 30 mg of triamcinolone acetonide in each nodule. The authors used triamcinolone 40 mg/cc diluted 3:1 with 1% lidocaine for a final concentration of 30 mg/cc. They injected each nodule with 0.5 cc to 1.0 cc. Each injection occurred a month apart.They noted softening of the nodules during their injection course. Four months after their last injection, they noted the nodules were smaller.
Triamcinolone acetonide appears to be the preferred corticosteroid for the intralesional injection of a plantar fibroma. It would also appear that the intralesional injection of triamcinolone into a plantar fibroma would be most effective for a chronic fibroma in the residual (end) phase of the fibroma’s development as this is when the fibroma is primarily composed of maturing collagen.
I currently use triamcinolone acetonide for the intralesional injection of plantar fibromas. A series of three to five injections with each injection spaced three to six weeks apart appears to be most effective. While the optimal dosage for each injection has yet to be determined, I currently use 15 mg to 30 mg per nodule and this appears to be a reasonable initial dose based upon the literature available. As Pentland and Anderson found, the nodules consistently soften and shrink (although they seldom resolve entirely), and the symptomatology resolves.4