In 1958, a group of Swiss orthopaedic surgeons formed the AO foundation, also known as the Association for the Study of Internal Fixation (ASIF). They established principles for fracture management that helped standardize fracture treatment protocols for the human and veterinary community. Initially, the AO recommend-ed precise anatomic fracture reconstruc-tion (known as direct reduction) be performed prior to internal fixation for all fracture configurations. However, in highly comminuted fractures, which are common in veterinary patients, anatomic reconstruction requires extensive surgi-cal exposure, manipulation of fracture fragments, and additional injury to the supporting soft tissue envelope. Anatomic reconstruction must be accomplished by placement of interfragmentary cerclage wires or lag screws, followed by placement of a precisely-contoured bone plate.

Recent advances in fracture manage-ment in humans have focused on mini-mally invasive fracture stabilization tech-niques. Previous work has shown the

invasive approaches necessary for ana-tomic fracture reconstruction and direct reduction disrupt the fracture hematoma and the extraosseus blood supply, each of which slow bone healing. Based on these findings, the AO has adopted principles of biological osteosynthesis which maxi-mize healing by protecting the patients biology while at the same time accomplish biomechanical fracture fixation goals.

The principles of biological osteosyn-thesis are:

1) Minimize iatrogenic soft tissue dis-ruption.

2) Utilize indirect reduction techniques (align the two major or parent fracture fragments in a functional position with-out anatomically reconstructing individu-al fracture fragments).

3) Provide stable fixation.

4) Promote the early return to limb function.

NOTESsurgeryVol. 1, No. 4 ~ Summer 2011a quarterly publication of the small animal surgery service atthe Texas A&M University Veterinary Medical Teaching Hospital

Did you know?There are currently a number of locking plate systems available to veterinary sur-

geons. At Texas A&M, we utilize the LCP (Synthes Vet, West Chester, PA), SOP (Or-thomed North America, Vero Beach, FL), and FIXIN systems (TraumaVet, Rivoli, Italy) when selecting a locking system for fracture repair. Only the FIXIN system contains a novel bushing-insert locking mechanism and is composed of both stainless steel and titanium components to more closely mimic the material properties of bone.

MIPO factoids...

MIPO was developed as an internal fixation technique for achieving biological osteosynthesis

During MIPO, the fracture frag-ments are typically not exposed or visualized; instead, a plate is insert-ed through small incisions known as portals and tunneled along the fracture

MIPO results in an early return to function, a low incidence of complications, and rapid fracture healing

Updates in fracture repair:

Minimally Invasive Plate Osteosynthesis (MIPO)

Figure 1: (Left) Immediate pre-op and post-op lateral radiographs of a fracture treated with MIPO. A FIXIN plate was used to stabilize this fracture.(Right) Intra-operative photo of a MIPO portal. The plate is placed from one portal, along the fractured bone, and out the other portal.

Texas A&Ms Veterinary Medical Teaching Hospital continues its fixed price program for common surgical diseases.

Uncomplicated appendicular fractures - $2000

Surgical eligibility requirements:

1) Single, appendicular fractures with a maximum duration of 7-10 days prior to admission. Radius/ulna and tibia/fibula are considered single frac-tures.

2) Systemically stable patient with no signs of head, thoracic, abdominal, or spinal injury.

3) Closed fracture, or at most a grade I open fracture of less than 24 hours duration prior to presentation to the CVM.

Services include physical examina-tion, pre-operative bloodwork and uri-nalysis, pre and post-operative radio-graphs, fracture repair, hospitalization, medications, and early rehabilitation.

By respecting the soft tissue envelope and using indirect reduc-tion techniques, biological osteosynthesis techniques have led to accelerated fracture healing, improved patient comfort and limb use, reduced surgical time, and a lower incidence of post-operative complications such as infections, delayed unions, and implant failures.

Many veterinary fractures are excellent candidates for indirect reduction using biological osteosynthesis techniques. Other frac-tures, such as two-piece, transverse mid-diaphyseal fractures con-tinue to be excellent candidates for direct reduction. It is impor-tant to remember that even if direct reduction is selected for a particu-lar fracture, many of the principles of biolog-ical osteosynthesis may still be followed.

Application of a cast or an external fixator to a fracture using closed reduc-tion techniques ac-complishes the goals of biological osteo-synthesis. When used in appropriate cases, external skel-etal fixation (ESF) is a highly successful and versatile system for fracture repair (Figure 2, 4), and we continue to use ESF regularly at Texas A&M. Unfortunate-ly, many patients are not candidates for external skeletal fixation due to fracture con-figuration, patient temperament, or client compliance. Minimal-ly Invasive Plate Osteosynthesis (MIPO) was developed as an in-ternal fixation technique in order to both adhere to the goals of biological osteosynthesis and provide a minimally-invasive alter-native to ESF. With MIPO, two small incisions, or portals, are cre-ated along the proximal and distal aspects of the injured bone, remote to the fracture fragments. The parent fracture fragments are grasped through the portals, and the fracture is aligned us-

ing indirect reduction techniques. Next, an epiperiosteal tun-nel is made connecting the two portals, followed by insertion of the plate through one of the portals, through the tunnel, and into the other portal (Figure 1). Screws are then used to secure the plate proximally and distally. Although MIPO is readily per-formed for fractures in which there is little soft tissue coverage (tibia, radius/ulna), it can also be performed successfully in the humerus and femur. Because most of the fracture fragments are not directly exposed or visualized, the MIPO technique can be technically challenging, and it is not suitable for every fracture.

Surgeons at Texas A&M, through the mentorship of Dr. Don Hulse, have been utilizing MIPO to treat our patients fractures for several years, and our clini-cal experience has been very encourag-ing. Most MIPO pa-tients are extremely comfortable and will walk on the op-erated limb as early as 1-2 days post-op-eratively. The inci-dence of infections, delayed unions, and implant failures ap-pears to be lower than with tradition-al fracture fixation techniques, and the fractures heal rapid-ly (similar to a frac-

ture treated by closed application of an external fixator).

The recent shift toward biological osteosynthesis using MIPO have led implant manufacturers to develop implants that func-tion more as internal fixators than traditional bone plates. These novel locking systems function in buttress mode and al-low each screw to physically lock into the plate as well as engage the bone. Locking a bone screw into a plate results in a small gap between the plate and bone, which may protect the perios-teal blood-supply and accelerate healing. Although we utilize a

Dr. Brian Saunders is a 2001 graduate of the Texas A&M University College of Veterinary Medicine & Biomedical Sciences (DVM) and a 2005 graduate of Texas A&M University Health Science Center (PhD). After completion of a small animal surgical residency, he joined the faculty as a Clinical Assistant Professor in Or-thopedic Surgery in 2009. He is a member of the American College of Veterinary Surgeons.

Dr. Saunders clinical interests include joint re-placement, arthroscopy, CORA-based correc-tion of limb deformities, and minimally inva-sive fracture repair. He has a strong research interest, and is in the process of establishing a cell biology laboratory to investigate molecular causes as well as molecular or cell-based thera-peutics for common orthopedic conditions.

Visit the VMTH Small Animal Surgery Service on the web at vetmed.tamu.edu/services/orthopedics

Dr. Brian Saunders

& Max

UpdATe: Orthopedics

fixed-price package

Eligibility...

Financially responsible clients (able to leave the 50% down pay-ment at time of admission) who will be responsible for post-op after care and who agree upon initial treat-ment to return for recheck examina-tions.

Prices do not include hospitaliza-tion/rehab longer than 7 days, or the cost of major complications or re-operations.

Faculty Spotlight: Dr. Brian Saunders

number of locking plate systems at Texas A&M, we are excited to announce that we have recently begun using the FIXIN sys-tem (TraumaVet, Rivoli, Italy). The FIXIN system is a locking system that utilizes a novel bushing-insert system to lock the bone screws into the bone plate (Figure 3). The bone plate is composed of stain-less steel, but the bushings and screws are titanium alloy, which gives the system ma-terial properties that more closely mimic normal bone. The FIXIN system is offered in various sizes and shapes, is competitive-ly priced when compared to other locking systems, and is highly amenable to MIPO techniques.

SummaryA paradigm shift has occurred in frac-

ture repair in which care for the soft tissue envelope and fracture hematoma takes precedence over anatomic fracture recon-struction using large, open approaches and direct reduction techniques. This transition has led many orthopedists to operate with the mindset of a gardener,

rather than that of a carpenter! Regard-less of whether an open approach or MIPO is selected, or whether internal or external fixation is selected, we continue to offer our fixed price package for rou-tine appendicular fractures. We hope this update has been helpful, and that you will continue considering Texas A&M when contemplating referral of your fracture patients.

References:

1. Hudson et al, 2009, Vet Comp Orthop Trau-matology. Minimally invasive plate osteosynthesis: Applications and techniques in dogs and cats.

2. Witsberger et al, 2010, Vet Comp Orthop Trau-matology. Minimally invasive application of a ra-dial plate following placement of an ularn rod in treating antebrachial fractures.

3. Guiot et al, 2011, Veterinary Surgery. Prospec-tive evaluation of minimally invasive plate osteosyn-thesis in 36 nonarticular tibial fractures in dgos and cats.

Figure 3:The FIXIN system is a new locking bone plate system that uses a novel bushing-

insert system and is composed of both stainless steel and titanium alloy. It is an ex-tremely versatile and effective system, and amenable to MIPO or open techniques.

Figure 4: Immediate post-op and 8 week post-op radiographs of a distal radius and ulna fracture treated with a hybrid external fixator from same patient as Figure 2.

Figure 2: Excellent limb use of external fixator patient 10 days post-op. (Click image to watch video.)