Barrett Matthew O, Wade Allison M, Della Rocca Gregory J, Crist Brett D, Anglen Jeffrey O
Anderson Orthopaedic Research Institute, 2501 Parkers Lane, Alexandria, VA 22306, USA.
J Bone Joint Surg Am. 2008 Mar;90(3):560-4. doi: 10.2106/JBJS.G.00743.
External fixation is widely used for trauma and reconstruction of the lower extremity. External fixator devices spanning the ankle or portions of the foot often utilize pins placed across the metatarsal bases. While this forefoot fixation is occasionally necessary to achieve reduction and alignment, it is also useful to prevent an equinus contracture. We undertook an anatomical study to evaluate the safety of pins placed across the bases of the first and second metatarsals, spanning the first intermetarsal space.
Under fluoroscopy, a single 4.0-mm Schanz pin was advanced percutaneously from medial to lateral across the bases of the first and second metatarsals in ten cadaver feet. This was accomplished in a fashion identical to the application of typical forefoot external fixation as described in the literature. Specimens were then dissected. Injury to the deep plantar branch of the dorsalis pedis artery, when present, was recorded. When injury was not present, the distance from the pin to the deep plantar branch was recorded.
In five of the ten feet, the deep plantar branch of the dorsalis pedis artery was lacerated by the transmetatarsal pin. In four feet, the pin contacted the artery but did not visibly damage it. In the remaining foot, the pin was noted to be only 4 mm from the artery. Any pin with a starting point within 18 mm of the first metatarsocuneiform joint placed the artery at risk.
Placement of external fixation pins through the proximal bases of the first and second metatarsals, within 2 cm of the first tarsometatarsal joint, consistently places the deep plantar branch of the dorsalis pedis artery at risk. Given the clinical importance of this artery, transmetatarsal pinning in this fashion is not advised. Other methods of obtaining forefoot or midfoot external fixation are recommended in order to avoid vascular injury.
外固定广泛应用于下肢创伤及重建。跨越踝关节或足部部分区域的外固定器装置常使用穿过跖骨基底的钢针。虽然这种前足固定对于实现复位和对线偶尔是必要的，但对于预防马蹄足挛缩也很有用。我们进行了一项解剖学研究，以评估穿过第一和第二跖骨基底、跨越第一跖骨间隙的钢针的安全性。
在荧光透视引导下，在十具尸体足部中，从内侧向外侧经皮将一根4.0毫米的斯氏针穿过第一和第二跖骨基底。这一操作方式与文献中描述的典型前足外固定应用相同。然后对标本进行解剖。记录是否存在足背动脉足底深支损伤。若未出现损伤，则记录钢针与足底深支的距离。
在十只足部中的五只，足背动脉足底深支被经跖骨的钢针划破。在四只足部中，钢针接触到了动脉但未造成明显损伤。在其余一只足部中，发现钢针距动脉仅4毫米。任何起始点位于距第一跖楔关节18毫米以内的钢针都会使动脉处于危险之中。
在距第一跗跖关节2厘米范围内，通过第一和第二跖骨近端基底置入外固定钢针，会持续使足背动脉足底深支处于危险之中。鉴于该动脉的临床重要性，不建议以这种方式进行经跖骨穿针固定。建议采用其他获得前足或中足外固定的方法，以避免血管损伤。
