Vascular Limitations of the Transmetatarsal Amputation with Consideration of the Deep Plantar Perforating Branch of the Dorsalis Pedis Artery

Corine L. Creech, DPMa, Priscilla Zinyemba, DPMa, and Andrew J. Meyr, DPM FACFASb

aResident, Temple University Hospital Podiatric Surgical Residency Program, Philadelphia, PennsylvaniabAssociate Professor, Department of Podiatric Surgery, Temple University School of Podiatric Medicine, Philadelphia, Pennsylvania (AJMeyr@gmail.com)*

*Please don’t hesitate to contact AJM with any questions/concerns. He’s happy to provide you with a .pdf of this poster if you email him.

[1] Capobianco CM, Stapleton JJ, Zgonis T. Surgical management of diabetic foot and ankle infections. Foot Ankle Spec. 2010 Oct; 3(5): 223-30.[2] DeRubertis BG. The elusive serach for predictors of healing following transmetatarsal amputation. Arch Surg. 2011 Sep; 146(9): 1009-10.[3] Steinberg JS, Meyr AJ, Attinger CE. Vascular anatomy and its surgical implications. In: Dockery GD, Crawford ME, editors. Lower Extremity Soft Tissue and Cutaneous Plastic Surgery. Second edition; 2012. p. 13-22.[4] Attinger CE, Meyr AJ, Fitzgerald S, Steinberg JS. Preoperative Doppler assessment for transmetatarsal amputation. J Foot Ankle Surg. 2010 Jan-Feb; 49(1): 101-5.[5] Basile P, Cook EA, Cook JJ. Immediate weight bearing following modified lapidus arthrodesis. J Foot Ankle Surg. 2010 Sep-Oct; 49(5): 459-64.[6] Davies MS, Saxby TS. Intercuneiform instability and the “gap” sign. Foot Ankle Int. 1999 Sep; 20(9): 606-9.

ConclusionResults

References

MethodsStatement of Purpose and Literature Review The importance of an adequate arterial vascular supply in the role of successful partial foot amputation has been well documented within both the podiatric and vascular literature [1,2]. The lower extremity is unique as a peninsular end-organ in that there is the potential benefit for a redundant and overlapping anastomotic vascular supply via the terminal branches of the popliteal artery: the anterior tibial artery, the posterior tibial artery and the peroneal artery [3]. When specifically considering the transmetatarsal amputation, surgeons should ensure that there is dual antegrade flow through both the dorsal and plantar flaps of the amputation, or that there is an intact “vascular arch” in the proximal first intermetatarsal space via the deep plantar perforating artery [4]. This vascular arch provides a direct point of anastomosis between the anterior tibial and posterior tibial arteries (Yellow arrow; Figure 1A). Interruption of this arterial communication may result in amputation failure in the setting of infrapopliteal peripheral arterial disease if the anterior tibial or posterior tibial arteries are not both supplying antegrade flow to the forefoot (Figures 1B-D). Even with an appreciation of this anatomy, however, the specific level of partial foot amputation is often dictated by the amount of remaining viable soft tissue. Ischemic or infected soft tissue and bone may necessitate proximal resection of the metatarsals dangerously close to interrupting this potentially vital interarterial connection (Figure 2). This area may also be of importance when considering reconstructive foot surgery, specifically when considering the arthrodesis of the first metatarsal-medial cuneiform joint and remainder of the tarsometatarsal joint complex (Figure 3). The use of intermetatarsal fixation has recently been advocated, particularly as a secondary point of fixation or in the presence of associated intercuneiform instability [5,6]. The objective of this investigation was to determine the length of remaining first metatarsal required in order to safely preserve this anastomotic connection and vascular arch.

Preliminary analysis involved dissection of 37 preserved cadaveric limbs (19 left). The most distal extent of the DPPA was found at a mean ± standard deviation of 1.58 ± 0.32cm (range 0.6-2.2cm) from the first metatarsal-medial cuneiform articulation. Thirty-six (97.3%) of the arteries were found within 2.0cm of the articulation.

This investigation involved dissection of preserved cadaveric lower limbs for exposure of the deep plantar perforating artery (DPPA). Anatomic landmarks identified during dissection were the DPPA in the proximal first interspace and the dorsal aspect of the first metatarsal-medial cuneiform articulation (Figure 4). The physical distance of the most distal aspect of the artery from the articulation was measured and recorded.

Transmetatarsal amputations can be a reliable and durable procedure if performed correctly and with an appreciation of the vascular implications of healing potential. In order to best predict and optimize the survival rates of these amputations, consideration must be given to the unique vascular supply of the foot. In the absence of dual antegrade flow from the anterior and posterior tibial arteries, preservation of the anastamosis in the proximal first interspace may be particularly essential. Based on the results of this investigation, we conclude that at least 2cm of remnant first metatarsal is required in order to maintain the vascular arch of the foot. This may represent a vascular definition and limitation of how “short” a transmetatarsal amputation can be safely performed. This anatomy may also play a role with respect to intermetatarsal fixation if used for arthrodesis of the first metatarsal-cuneiform joint and medial column.

Figures 4: Measurement of the primary outcome measure

This investigation involved dissection of embalmed cadaveric specimens for the dorsal aspect of the first metatarsal-cuneiform joint (blue pin) and the most distal aspect of the deep plantar perforating artery (indicated by scissors). The physical distance between the two was measured with a mean ± standard deviation of 1.58 ± 0.32cm (range 0.6-2.2cm) observed.

Figure 1: Vascular anatomy of the transmetatarsal amputation Successful healing of a transmetatarsal amputation involves, in part, dual antegrade flow to the dorsal and plantar amputation flaps from both the anterior tibial artery and posterior tibial artery (Figure 1A; blue arrows). The deep plantar perforating artery (orange arrows) represents an important anastomotic connection between the dorsal and plantar arterial flow. In a situation of compromised arterial inflow (Figure 1B and 1C), one artery (blue arrow) may supply both the dorsal and plantar flaps through the DPPA anastomotic connection. Figure 1B demonstrates antegrade flow through the plantar flap and minimal retrograde flow to the dorsal flap. Figure 1C demonstrates antegrade flow through the dorsal flap and retrograde flow to the plantar flap. If this connection is interrupted during surgery, it may result in differential flap failure to the flap supplied in a retrograde manner (Figure 1D demonstrates failure of the plantar flap).

A B

C DFigure 2: Tissue loss and the transmetatarsal amputation Even with a detailed knowledge of the arterial inflow to a foot requiring transmetatarsal amputation, sometimes pre-existing tissue loss necessitates proximal resection. This set of figures demonstrate a patient who had only antegrade flow through the dorsalis pedis artery with retrograde flow to the plantar foot through the DPPA. However, the degree of tissue loss required full resection of the first metatarsal. An attempt was made to preserve the DPPA by keeping this soft tissue intact during the debridement and closure. Intra-operative Doppler was utilized to verify patency in the artery throughout the procedure, and one can visualize the calcified vessel is preserved on the post-operative radiograph (orange arrows).

Figure 3: Forefoot reconstructions involving the proximal first interspace.

Anatomic knowledge of the location of the this artery may also be of benefit when considering arthrodesis of the first metatarsal-medial cuneiform joint, particularly when intermetatarsal fixation is considered. (Second figure from: Basile P, Cook EA, Cook JJ. Immediate weight bearing following modified lapidus arthrodesis. J Foot Ankle Surg. 2010 Sep-Oct; 49(5): 459-64)