Objective: We graded the severity of occlusive disease in foot vessels of patients with diabetes and correlated the scoring obtained with graft patency and limb salvage.
Methods: In this retrospective review of 199 limbs studied by means of angiography in 117 patients with diabetes mellitus, 124 limbs underwent bypass grafting. Each dorsalis pedis (DP), lateral plantar (LP), and medial plantar (MP) artery was assigned a score according to the reporting standards of the Joint Vascular Societies Council (0, no stenosis > 20%; 1, 21%-49% stenosis; 2, 50%-99% stenosis; 2.5, < half the vessel length occluded; 3, > half the vessel length occluded.) A foot score (DP + MP + LP + 1) was calculated for each foot (1 to 10). The mean follow-up period was 14 months.
Results: For all 199 limbs and for the 124 limbs that underwent bypass grafting, the mean scores were similar for the DP, MP, and LP (1.8 +/- 1.0, 1.9 +/- 1.0, 1.9 +/- 1.0, respectively; P >.4). Only the MP and LP correlated with each other (r = 0.57; P <.0001). There were no scoring differences between limbs with symptoms and limbs that did not undergo bypass grafting. Bypass graft patency correlated with both the foot score and the MP score for tibial and inframalleolar grafts (P <.04). Patency correlated with the LP score only for inframalleolar bypass grafting procedures. The DP score alone did not differ between bypass grafts that remained patent and bypass grafts that failed. Bypass grafts in limbs with a foot score less than 7 and an MP score less than 2 had only a 2% failure rate. A foot score greater or equal to 7 was associated with a 30% failure rate for all bypass grafts (41% for inframalleolar grafts). Bypass grafts with low foot scores that failed did so much later than bypass grafts with high foot scores that failed (17 +/- 11 months vs 6 +/- 8 months; P <.02), possibly reflecting different etiologies for the failure. The limb salvage rate correlated with foot score (P <.05). The limbs that were saved had an average foot score of 6.4 +/- 2.0, versus 7.2 +/- 1.4 for limbs that required amputation.
Conclusion: In patients with diabetes mellitus, the foot score is a useful tool for predicting the likelihood of graft patency and limb salvage for infrapopliteal revascularization. However, the relatively high bypass success rate (70%) in the presence of a high foot score (>or= 7) does not allow its use in identifying the subgroup of patients who are unlikely to benefit from bypass grafting surgery. It cannot be used as a means of selecting patients for primary amputation.