Pre-drilling or Self Drilling External Fixation Pins

Background

The application of external fixation is a commonly performed emergency procedure in
orthopaedics for temporary stabilization as well as definitive treatment of fractures.
External fixation requires that metal pins be placed into the bone on either side of the
fracture. The pins are then connected to an external frame, thus stabilizing the fracture.
There is debate over the optimal technique for the insertion of these pins in regards to the
need to pre-drill a pilot hole prior to pin insertion.

The technology behind external fixation has evolved greatly over the past thirty years. The
original external fixation pins, "Shanz pins," were essentially metal rods with threads and
a trocar point. A pilot hole was needed because these pins did not have the capability to
create their own hole or path in the bone. Recent advances have lead to the creation of
self-drilling/self-tapping pins, which have decreased the number of steps necessary to place
the pins and thereby decreased operative time. The external fixators are usually placed as a
temporary measure to allow for improvement of soft tissue condition before definitive open
reduction and internal fixation. Since many external fixation devices are placed in patients
who are critically ill, decreasing operative time is very important.

While saving operative time is essential it is also important that the device serves its
purpose without leading to complications in the short term. The major complications related
to external fixation are pin site infection and pin loosening. The literature is clear that
high temperatures created during pin insertion leads to bone necrosis surrounding the pin,
increased infection, and increased rates of loosening. It is unclear if the new generation
self-drilling pins create the same amount of necrosis as the older generation of pins. Lab
studies have shown increased temperatures with direct drilling with these pins as compared
to pin insertion after drilling pilot holes with dedicated drill bits. It is unclear if this
increased temperature results in increased rate of loosening or pin site infection in
clinical practice.

A thorough literature search has revealed no randomized controlled studies to support the
use of these pins without drilling pilot holes before insertion. The current standard of
care is undefined and left to surgeon preference. Our study aims to provide guidelines for
schanz pin insertion for external fixator application, which may help to reduce the number
of pin tract infections suffered by patients and improve outcomes.

Study Design and Treatment Plan

This will be a prospective, randomized, within-subject, single-blind trial to be conducted
at Temple University Hospital. Patients who are determined to require an external fixation
procedure of the lower extremities due to fracture or dislocation will be considered for
enrollment according to the above inclusion criteria. Standard of care for treatment of
their fractures will be provided. Once patients have provided informed consent for
enrollment in the study, their pins will be randomized in a paired design according to a
computer generated randomization schedule. There will be two types of pins, pre-drilled and
non pre-drilled. A standard external fixation device requires two pins on each side of the
fracture. Each pair of pins will have one each of pre-drilled and not pre-drilled pins,
according to the randomization schedule. Therefore, each patient will have two pre-drilled
pins and two pins inserted without pre-drilling. Some surgeons may prefer three pins on each
side of the fracture/dislocation that is to be immobilized. We will have a randomization
protocol for these situations as well.

The computer generated randomization algorithm will be placed in a secure location in sealed
opaque envelopes. The operating surgeon will open the envelope prior to pin insertion and
follow the randomization schedule as prescribed in the envelope.

A standard technique will be followed. IV antibiotics will be administered within 60 minutes
of the starting skin incision. Pin insertion will be done by standard techniques. This
involves a 1 cm incision, and blunt dissection. 4.0 mm (calcaneal or metatarsal), 5.0 mm
(tibia) or 6.0 mm (femur) pins will be inserted by one of two techniques: (1) self drilling
pins are inserted with a power drill directly into the bone; (2) a standard twist drill bit
is utilized with a power drill to create a pilot hole, followed by insertion of the
self-drilling pin by power drill.

Soft tissue relaxation incisions are made according to standard technique after external
fixation assembly, as needed. The pin care protocol will consist of daily pin site cleaning
using dilute hydrogen peroxide and dry dressings. Patients with suspected pin site infection
will be treated with Keflex 500mg po q 6hr. Patients with an allergy to Keflex will receive
Clindamycin 300mg po q 6hr.

Inclusion Criteria:

1. Age 18-89

2. Fluency in spoken/ written English/ Spanish (consent form in Spanish will be needed)

3. Lower extremity fracture/ dislocation treated with an external fixator

Exclusion Criteria:

1. Prisoners

2. Patients unable to give informed consent

3. Patients who require that pins be placed without skin coverage at the pin site

4. Patients receiving Ilizarov or other circular external fixators with transfixing
wires.