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Intraoperative Use of External Fixator Attachments for Reduction of Lower Extremity Fractures and Dislocations

The American Journal of Orthopedics. 2017 November;46(6):E454-E457
December 21, 2017|The American Journal of Orthopedics
Charles F. Land, MD;William J. Rosenblum, MD;Justin Kennon, MD
Author and Disclosure Information

Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article. 

The mainstay of complex open lower extremity fractures and dislocations is the temporizing external fixator.  We propose the use of external fixator attachments that allow for the reduction of fractures and dislocations intraoperatively. By using external fixator carbon fiber rods, the surgeon is able to create a capital “T” (sweet T) shaped attachment and connect this to a Schanz pin. Simultaneously, the external fixator carbon fiber rods can be configured into the shape of a capital Greek letter pi (Cherry II) and applied to an external fixator pin. When both of these configurations are used, multi-directional forces can be applied across the fracture fragments with the added benefit of using extrinsic hand muscle power for force generation and manipulation of fracture fragments to facilitate reduction.

Take-Home Points

  • External fixator attachments are fast and easy to assemble with existing external fixator equipment.
  • They allow for multi-directional force application and use of extrinsic power grip.
  • They limit radiation exposure and provides unobstructred line of sight to zone of injury.
  • The attachments can then be removed once reduction is achieved.

External fixation has a long history both for initial open or closed management of fractures and for definitive management.1 After the introduction of internal fixation constructs using nails or plates, external fixation largely transitioned from a means of definitive management to a temporizing measure taken before definitive internal fixation.

The Delta Frame external fixator (DePuy Synthes), which is used for significantly swollen ankle and pilon fractures, features anteromedially placed tibial shaft pins and a transcalcaneal pin. For distal tibia fractures that are not amenable to urgent internal fixation because of the degree of swelling or soft-tissue injury, it provides ligamentotaxis and traction for reduction of fracture fragments and stabilization.2

Numerous other external fixator configurations, such as knee-spanning or tibia-spanning external fixators, can be used for similar purposes. These stabilization methods are all minimally invasive and thus cause little trauma to the zone of injury3 and give soft-tissue injuries time to heal before definitive internal fixation.

Several different external fixator configurations can be used for a variety of fracture patterns and locations, but we propose using the external fixator as a starting point and adding proximal and distal attachments. These attachments have the potential to create more reduction force, and they provide more control of proximal and distal fracture fragments, continue to be minimally invasive, offer extrinsic grip power, are easily assembled and disassembled for intraoperative fracture reduction, and reduce the surgeon’s radiation exposure.

Materials and Methods

Our institution employs an external fixator system that is often used for high-energy lower extremity pathology. This system facilitates assembly of a Sweet T–Cherry II configuration. For periarticular ankle injuries, a Delta Frame external fixator is applied as described in the AO (Arbeitsgemeinschaft für Osteosynthesefragen) surgical reference. Two diaphyseal Schanz pins are inserted into the tibia anterior to posterior based on the pin-placement guide and confirmed with fluoroscopy. These pins must be positioned close enough to the fracture site to provide stability, but not so close as to enter the zone of injury. A Denham pin is placed in the calcaneus medial to lateral. Care is taken to avoid the posterior tibial neurovascular bundle. Then, with use of pin-carbon fiber rod connectors, rods are attached so the Schanz pins connect with the Denham pin. In Sweet T–Cherry II assembly, a different rod configuration is used; rods are attached to the proximal-most Schanz pin and the Denham pin. In Sweet T assembly, a rod-rod connector is used to attach 2 carbon fiber rods to each other.

Figure 1.
These rods are orthogonally connected in a T shape. A pin-rod connector is then used to attach the assembled apparatus to the proximal-most Schanz pin. Figure 1 shows the assembled Sweet T.

Next, in Cherry II assembly, 2 carbon fiber rods are attached to and locked to the Denham pin, one medial and the other lateral in an orientation orthogonal to the Denham pin extending distally. The Cherry II apparatus is completed with a third rod and is placed parallel to the Denham pin and orthogonal to the first 2 rods.

Figure 2.
Figure 3.
Figure 2 shows the assembled Cherry II, and Figure 3 shows the fully assembled Sweet T–Cherry II external fixator configuration. After the fully assembled external fixator is fitted with the Sweet T and Cherry II attachments, the attachments are used to manually reduce the fracture, the reduction is confirmed with fluoroscopy, and the external fixator connectors are locked to maintain the reduction.

For knee-spanning external fixators, 2 Sweet T assemblies can be attached to the 2 Schanz pins. Furthermore, if 2 transverse pins are used for tibial external fixation, 2 Cherry II attachments can be used for multidirectional traction. An added benefit is extrinsic grip power, vs the intrinsic grip power provided with use of only the Schanz and Denham pins.

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