Mueller Michael J, Lott Donovan J, Hastings Mary K, Commean Paul K, Smith Kirk E, Pilgram Thomas K
Program in Physical Therapy, Washington University School of Medicine, 4444 Forest Park Blvd, Box 8502, St Louis, MO 63110, USA.
Phys Ther. 2006 Jun;86(6):833-42.
Total-contact inserts (TCIs) and metatarsal pads (MPs) frequently are prescribed to reduce excessive plantar stresses to help prevent skin breakdown in people with diabetes mellitus (DM) and peripheral neuropathy. The first purpose of this study was to determine the effect of a TCI and an MP on metatarsal head peak plantar pressures (PPP) and pressure-time integrals (PTI). The second purpose of this study was to determine a possible mechanism of pressure reduction by measuring contact area and loaded soft-tissue thickness (STT) under the metatarsal heads and second metatarsal shaft.
Twenty subjects (12 men and 8 women; age [mean+/-SD]=57+/-9 years) with DM (duration [mean+/-SD]=16+/-11 years), peripheral neuropathy, and a history of plantar ulcers participated.
A repeated-measures research design was used, and outcome measures are reported for 3 footwear conditions: shoe, shoe with TCI, and shoe with TCI and MP. In-shoe plantar pressures were collected during walking and during spiral x-ray computed tomography (SXCT). The STT and identification of the pressure sensor and location of the MP in relationship to the metatarsal heads were determined by use of SXCT.
The PPP and the PTI were 16% to 24% lower at the metatarsal heads in the TCI condition than in the shoe condition. The PPP and the PTI decreased an additional 15% to 28% (for a total reduction of 29% to 47%) with the addition of the MP. The contact area increased 27% with the TCI but not with the MP. The STT did not increase under the metatarsal heads in the TCI condition (compared with the shoe condition) but did increase 8% to 22% at metatarsal heads 2 to 5 with the addition of the MP. The PPP increased substantially (308%) and the STT decreased 14% under the shaft of the second metatarsal with the addition of the MP to the TCI-plus-shoe condition.
The TCI and the MP caused substantial and additive reductions of pressures under the metatarsal heads. The TCI reduces excessive pressures at the metatarsal heads by increasing the contact area of weight-bearing forces. Conversely, the MP acts by compressing the soft tissues proximal to the metatarsal heads and relieving compression at the metatarsal heads. These findings can assist in the design of effective orthotic devices to relieve excessive plantar stresses that contribute to skin breakdown and subsequent amputation in people with DM and peripheral neuropathy.
全接触鞋垫（TCI）和跖骨垫（MP）常用于减轻足底过度压力，以帮助预防糖尿病（DM）和周围神经病变患者发生皮肤破损。本研究的首要目的是确定TCI和MP对跖骨头峰值足底压力（PPP）和压力-时间积分（PTI）的影响。本研究的第二个目的是通过测量跖骨头和第二跖骨干下方的接触面积和加载软组织厚度（STT）来确定压力降低的可能机制。
20名患有DM（病程[均值±标准差]=16±11年）、周围神经病变且有足底溃疡病史的受试者（12名男性和8名女性；年龄[均值±标准差]=57±9岁）参与研究。
采用重复测量研究设计，报告了3种鞋类条件下的结局指标：鞋子、带有TCI的鞋子以及带有TCI和MP的鞋子。在步行和螺旋X线计算机断层扫描（SXCT）过程中收集鞋内足底压力。通过SXCT确定STT以及压力传感器的识别和MP相对于跖骨头的位置。
与穿鞋子的情况相比，在TCI条件下，跖骨头处的PPP和PTI降低了16%至24%。添加MP后，PPP和PTI又额外降低了15%至28%（总共降低29%至47%）。TCI使接触面积增加了27%，而MP未使接触面积增加。在TCI条件下，跖骨头下方的STT与穿鞋子的情况相比没有增加，但添加MP后，第2至5跖骨头处的STT增加了8%至22%。在TCI加鞋子的条件下添加MP后，第二跖骨干下方的PPP大幅增加（308%），STT降低了14%。
TCI和MP可显著且叠加地降低跖骨头下方的压力。TCI通过增加承重力量的接触面积来降低跖骨头处的过大压力。相反，MP的作用是压缩跖骨头近端的软组织并减轻跖骨头处的压力。这些发现有助于设计有效的矫形器械，以减轻导致DM和周围神经病变患者皮肤破损及后续截肢的过度足底压力。
