[Forefoot and midfoot amputations]. / Amputationen an Vor- und Mittelfuß

ABSTRACT

OBJECTIVE: Partial foot amputations are feasible regardless of the causal condition, including peripheral vascular disease with a few exceptions. Compared to higher amputation levels, a good foot stump permits full end bearing and enables the patient, even with a hindfoot stump, to walk without the need for a prosthesis. The more peripheral the amputation level selected, the greater the need for gentle tissue handling and meticulous postoperative care, but also the greater the risk of a breakdown requiring stump revision surgery. In the forefoot, partial amputation of the metatarsals preserves the length of the stump and, thus, minimizes the loss of weight-bearing surface. The resection of metatarsal and midfoot bones without removing the toes, called a "hidden" amputation, is more acceptable to the patient who does not feel as if he/she has become an amputee. In addition, no neuroma or phantom pain is experienced. Biomechanically, this amputation hardly differs from a classical amputation. INDICATIONS Amputation cannot be avoided by any conservative or operative means. CONTRAINDICATIONS Absolute rapidly progressing peripheral arterial diseases, i.e., Buerger-Winiwarter's disease. Relative renal failures requiring dialysis or kidney transplantation. SURGICAL TECHNIQUE Patient in prone position, keep foot and calf free, protect heel from pressure. Mark the skin incisions. A long plantar flap covers the bones and is sutured to the short dorsal flap at the dorsum of the foot. Begin with the dorsal incision down to the bones. After separating the bones, turn the distal part down and separate the plantar soft tissue flap. The bones are well aligned and shaped. Longitudinal amputations preserve a larger load-bearing surface and, therefore, are preferred, if possible. Another alternative is the "hidden" amputation. Except for amputations in peripheral vascular diseases, the digits and their neurovascular supplies are preserved. Only the bones are resected, from transmetatarsal to Chopart. The toes will retract within a few weeks. The patients do not feel as if she/he has become an amputee, although the biomechanics of the foot are about the same as after a total amputation. In case of infection, wound debridement, open wound treatment, and delayed primary closure are recommended. POSTOPERATIVE MANAGEMENT Full plantar weight bearing in plaster cast or walker is possible 4-6 weeks after surgery. In the case of diabetic foot, healing can require weeks. Total contact prosthesis without limiting the range of motion (ROM) of the ankle and the subtalar joint after 6 weeks. Best results are obtained with prostheses using the silicone technique. Alternative orthopedic footwear. RESULTS: It is desirable to maintain the greatest length possible; wound healing disorders are observed in over half of all cases. Operative stump corrections are justified in 20-30%; a transtibial amputation is seldom necessary.