3. External Fixation of Upper Extremity/Lower Extremity/Periarticular Fractures with Limited Resources (no X-ray)

I. Introduction

            A. External fixation may be performed in austere environment without use of fluoroscopy

            B. Ideally, pins should be placed to minimize impact on future internal fixation

II. Pin Placement

            A. Should be performed as follows (see femoral external fixation placement video)

                        1. make small vertical incision at site of pin placement

                        2. spread down to bone bluntly

                        3. load pin in drill or manual driver and place pin into incision until pin meets bone

                        4. use pin tip to feel either side of bone

                                    a. for example, lateral pin placement in femur should be performed through mid portion of shaft

                                    b. “walk” pine anteriorly and posteriorly to feel edges of bone so that mid portion may be identified

                        5. advance pin through near cortex; stop at purchase of far cortex without over-penetrating (figure 1. Avoid pin over-penetration regardless of location of pin placement. Once the external fixator pin engages the far cortex, an additional 4 or 5 turns will be required to advance the pin appropriately without over-penetrating.)

                        6. subsequent pin placement on same bone should be performed in parallel to allow pin-to-bar clamps to engage both pin elements without difficulty; clamp may be used as guide for placement

                        7. avoid pin positioning too close to fracture site (pins within fracture itself will decrease external fixator’s ability to maintain stability of fracture) (figure 2 and figure 3. The anteroposterior radiograph of this tibia suggests adequate external fixator placement, however, the lateral radiograph shows that the proximal pin of the distal pin group is within the fracture.)

                        8. external fixators may be placed to span joints if fractures extend into articular surface

            B. Femur

                        1. half pins may be inserted at any point along lateral aspect of femur with low risk to neurovascular structures; over-penetrating medial cortex may put profunda femoris artery at risk

                        2. anterior half pins may be used in midshaft; however, posterior cortex must not be violated so as not to injure sciatic nerve

                        3. transfixtion pins may be placed distally, however, assure adequate proximal distance from knee joint capsule; pins should be placed medially to laterally

                        4. see diagram 1. Safe zone pin placement for the mid shaft of the femur. The lateral pins may also be used proximally.

                        5. see diagram 2. Safe zone pin placement for the distal femur. Transfixtion may be used; however, place pins proximal enough to avoid the joint capsule (2-3 finger breadths above the patella).

                        6. see figure 4. Anteroposterior radiographs of laterally placed half pins in the proximal femur.

                        7. see figure 5. Anteroposterior radiographs of laterally placed half pins in the distal femur.

            C. Knee

                        1. lateral pins in distal femur and anteromedial pins in proximal tibia may be bridged with additional bar-to-bar clamps

                        2. see figure 6. This clinical photograph demonstrates how the distal femur and proximal tibia may be bridged in order to span the knee.

                        3. see figure 7. Anteroposterior radiograph of an intra articular fracture spanned at the knee.

            D. Tibia

                        1. half pins should be placed on anteromedial surface of bone; this is easily palpable as it is subcutaneous the entire length of the bone

                        2. see diagram 3. Safe zone pin placement in the tibia. Distally, the distal tibia and fibula may be crossed with one transfixation pin.

                        3. see figure 8. Anteroposterior radiograph of external fixator placement about a tibia fracture.

                        4. see figure 9. Biplanar control may also be achieved with half pins inserted on the anteromedial and anterolateral surfaces of the proximal tibia. Be aware of the peroneal nerve laterally.

            E. Ankle

                        1. ankle may be incorporated into lower extremity external fixators by delta-shaped construct or unilateral construct

                        2. transfixation pins may be inserted into calcaneus from medial to lateral position; ensure pin start point is posterior and distal to medial and lateral plantar nerves

                        3. proximal shaft of first metatarsal may accept pins perpendicular to long axis of metatarsal; do not enter base of metatarsal, as this may tether the tibialis anterior tendon

                        4. see figure 10. Anteroposterior radiograph of an ankle spanning external fixator with a calcaneal transfixation pin and a first metatarsal pin.

            F. Humerus

                        1. lateral half pins are used; do not over-penetrate medial cortex proximally so as not to damage neurovascular bundle

                        2. anterior half pins may also be used

                                    a. proximally, avoid palpable deltoid tendon

                                    b. at mid shaft, do not over-penetrate posterior cortex so as not to damage radial nerve

                        3. see diagram 4. Safe zone pin placement for the humerus. The epicondyles may be transfixed distally, with caution given to ulnar nerve medially.

                        4. see figure 11. Clinical photograph of humerus external fixator.

                        5. see figure 12. Radiographs of the same humerus external fixator.

            G. Elbow

                        1. half pins or transfixation pins may be placed laterally to medially; avoid anterior neurovascular structures and ulnar nerve groove posterior and medial to medial epicondyle by placing pins in plane with epicondyles, palpable on each side of elbow

                        2. see figure 13. Clinical photograph of an elbow spanning external fixator.

                        3. see figure 14. Radiograph of the same elbow spanning external fixator.

            H. Forearm

                        1. ulna is easily palpable and pins may generally be placed along any border; typically lateral entry pins are used, keeping in mind the ulnar nerve proximally

                        2. closed pin placement in proximal portion of radius is not recommended because of risk to posterior interosseous nerve; radial pins may be placed about distal portion

                        3. see figure 15. Anteroposterior radiograph of ulnar external fixator.

The view(s) expressed herein are those of the author(s) and do not reflect the official policy or position of Brooke Army Medical Center, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Army, Department of Defense or the U.S. Government.