What happens to the contra-lateral foot following diabetic foot amputations?

Background

The pathomechanics of diabetic foot amputations are already documented in the literature. However, the contra-lateral changes have received less attention. Therefore, this study was aimed to investigate the changes occurring in the contra-lateral limb following a partial foot amputation (PFA).

Methods

Sixteen patients with PFA (transmeta-tarsal = 5; ray = 5; hallux = 4; hallux + toes = 2) and diabetic neuropathy (DMPN) were matched with 23 patients with DMPN for height, mass and age. Net joint moments at hip and ankle were calculated using a Kistler Force platform and a 512 Vicon Kinematic system. Plantar pressure distribution during walking (with shoe filler) was recorded using the Pedar in-shoe system. Gait characteristics and plantar pressures (co-variate = gait velocity) were compared between the 2

Findings

The patients with PFA walked with reduced gait velocity (P < 0.001) and decreased ankle moments (P < 0.001) on the amputated limb compared to the DMPN group. The PFA group showed higher pressures over the mid-foot (P < 0.05) of the amputated limb and the heel (P < 0.034) of the contra-lateral limb compared to the controls.

Within the PFA group the ankle plantar flexor moments (p < 0.001) were higher on the contra-lateral-limb than the amputated limb. Also the MPP (P < 0.05) and the PTI (P < 0.05) were

Interpretation

Deformed and shortened feet with inadequate plantar flexor lever arm on the amputated limb can explain the decreased ankle moment observed (Mueller et al., 1998). The higher plantar pressures over the mid-foot could be explained by the reduced surface area. Although not measured, the partially amputated foot may have less dynamic ankle dorsiflexion ROM during gait as seen in the patients with trans-metatarsal amputations (Garbalosa et al., 1996). Presence of neuropathy in both groups confirms