Bones, Plates, and Screws – How do Veterinarians Repair Broken Bones?

Over time, veterinary care has seen significant advancements. Many conditions that were once difficult to treat can now receive routine treatment, including orthopedic surgeries. Nonetheless, orthopedics is still considered a specialized field in veterinary medicine, and many pet owners are not fully informed about its intricacies. Thus, let’s delve deeper into veterinary orthopedics for clearer understanding.

What is Orthopedics?

The term “orthopedics” was invented by a French surgeon and comes from the Greek words “ortho-“, meaning straight or correct, and “-paidion”, meaning child. This is because orthopedics initially dealt primarily with correcting skeletal deformities in children, such as scoliosis and bow legs. However, practices recognizable as orthopedics have been performed at least since the middle ages (and possibly as far back as Ancient Egypt – there is evidence of bamboo splints found on mummies), particularly during times of war, when soldiers would attempt to fix fractures with splints.

Modern orthopedics is a broad field that deals with all diseases related to the musculoskeletal system. This includes any issues with a person’s (or animal’s) bones, muscles, and joints. In human medicine, common orthopedic procedures include fracture repair, hip replacements, and arthroscopy (using a camera to look inside a joint).

As advances are made in human medicine, veterinary medicine usually follows suit (and sometimes even leads the way!). For hundreds of years, veterinary medicine was primarily concerned with working animals, particularly horses, as their long legs are prone to injury. It wasn’t until the Victorian era that the practice of keeping pets became popular, hence, increasing the demand for treatment of animal injuries. With the invention of X-ray and fluoroscopic technology, along with safer anesthetics, veterinarians began to be able to fix pet fractures. From this time, with the wide use of new scientific technology, sterile surgeries, antibiotics, and metallic implants, veterinary orthopedics have evolved into what it is today, even though the field continues to progress annually.

What Tools do Orthopedic Veterinarians Use?

Orthopedic surgery is not a simple process of sticking things together. Most surgeries require specialized equipment and techniques, which can make understanding what your pet is going through more complex. Now, let’s introduce some of the tools commonly used in orthopedic surgeries. Keep in mind that every surgery, especially those for traumatic injuries, will vary considerably based on the patient, the veterinarian, and other factors.

There are several important principles that every orthopedic surgeon must consider during each operation. These principles will affect the use of the surgery and equipment. These principles include ensuring a rapid return to normal function for the animal, minimizing further damage to tissues, understanding how weight-bearing forces work on bones and joints, and how to repair damage. Most of the time, this will first require an imaging exam, usually radiography or CT scan.

Intramedullary pins are long metallic rods that are usually inserted longitudinally into the center (medulla) of a bone and are commonly used to treat fractures in areas such as the tibia, ulna, and femur. These pins primarily function to align the fragments of the fracture. Their main advantages lie in preventing bending or sideways movement of the fracture site, and they can be placed without requiring extensive surgical incision. However, intramedullary pins do not provide strong resistance against rotation or compression of the fracture site. Hence, they are often used in combination with metal plates or cerclage wires to combat these forces. At times, intramedullary pins may also slide out from the bone, protruding through the skin, causing pain and difficulty in movement.

Cerclage wires are flexible, thread-like materials with high malleability, capable of being bent into various shapes, thereby serving a wide range of uses. Typically, cerclage wires are wrapped around the bone to prevent sideways movement of the bone, making them effective in conjunction with intramedullary pins. When used in conjunction with K-wires, cerclage wires can push or pull the bone in a particular direction. However, their main disadvantages lie in the need for more extensive bone exposure for operation and the potential for them to slide, delaying fracture healing.

K-wires, or Kirschner wires, are thin, needle-like devices that can be pushed into the bone. For young animals with joint fractures, ensuring perfect alignment of the fracture is crucial to prevent ongoing joint issues, and K-wires are commonly used in these cases. They can also be used to reattach bone fragments that are pulled off by tendons or ligaments. They are typically used in conjunction with cerclage wires to form a tension band. After injury repair, K-wires can be removed, whereas many other orthopedic implants cannot be.

Orthopedic screws may resemble the screws you commonly use in furniture but on a much finer scale. Though they are made of stainless steel or titanium alloys and sterilized, the functionality of orthopedic screws extends far beyond what you see on the surface. Screws can be used simply to hold two bones together and distribute pressure (neutralization/positioning screws); or they can be used to compress fracture fragments tightly together (lag/compression screws). Some screws are designed to fit precisely into orthopedic metal plates, but many can be used independently. Some screws require pre-drilling into the bone; others can drill their own hole upon insertion. Orthopedic screws come in various sizes and shapes, depending on the surgical requirement.

Bone plates

Metal bone plates are designed to be used with screws to fixate fractures, resist the pressure of weight-bearing on the fracture site, ensure stability, and promote healing. A properly used bone plate can realign the broken bones, facilitating swift healing and functional recovery. There are many types of plates, each with different sizes to cater to various skeletal features. Often, an orthopedic surgeon will need to moderately bend the plate during surgery to fine-tune its shape.

Typically, plates are applied laterally to the fracture, with each bone piece affixed via plate-mounted screws. Some plates are designed to draw bones closer together, while others resist forces acting on the bone, as other implants (such as intramedullary pins) hold the bone in place. Metal bone plates require coverage and fixation of a large fracture area; therefore, the installation of bone plates requires a longer surgical time and larger surgical incision for the surgeon to correctly position and fixate the plate on the bone.

External Fixators

External fixators are designed to stabilize fractures but are distinctive in that they are located outside the body. Their main advantage is that they can stabilize fractures without the need for extensive surgical incision. They work by inserting pins into the bone from the outside and fixating them in place via an external, visible rigid frame. External fixators are an ideal solution for open fractures or wounds that are too severely infected to allow for safe debridement. However, they are not able to accurately reposition bone fragments, which means they are not suited for treatment in critical areas like joint fractures. Additionally, because the pins need to be inserted into the bone directly from the outside, this puts the bone at risk of infection.

Prosthetics

Prosthetics are parts made of metal or plastic, designed to replace body parts following amputation, providing the ability to perform most normal activities. These advanced devices are typically custom-made for individual animals. Sometimes they are 3D-printed or handmade.

External prosthetics are secured to the animal with straps and can be easily removed. Another type is transdermal prosthetics, which are surgically fixated directly to the bone, permanently replacing the lost limb. These prosthetics have gained notoriety due to exposure on some veterinary TV shows but also raise serious drawbacks and controversy. However, if successful, they may offer animals a quality of life closer to normal. It should be noted that many animals lead normal lives following amputation with only three limbs, provided the remaining limbs are healthy.

External Fixation

External fixation refers to all non-surgical methods of fracture stabilization. Splints, casts, heavy bandages, and slings all fall under external fixation methods. Their main advantage is that they can be applied under sedation or general anesthesia without surgery. These methods are particularly suited to simple fractures with limited mobility, especially in young animals. However, external fixation is not suitable for complex fractures and can result in limb swelling, inaccurate alignment of bones during fracture healing, slippage of splints, pressure sores, and muscle atrophy, among other issues.

So, how do veterinary orthopedic surgeons fix broken bones?

Let’s imagine a simple scenario – your pet dog has managed to wriggle out of its leash and has been hit by a car, and you suspect it has broken a leg. Fortunately, the driver is kind (and following the law) and stops and takes you to a nearby veterinary clinic. What might happen in such a situation from the perspective of a veterinary orthopedic expert?

First of all, any veterinarian, whether an orthopedic expert or not, will begin with a basic clinical examination. A broken leg is certainly painful, but as long as there is no massive bleeding, it may not be the most life-threatening injury. There might be brain trauma, internal bleeding, lung damage, or other more serious issues. The vet will need to check your dog’s breathing, heart rate, pulse, body temperature, state of consciousness, and more. Further diagnostics might quickly involve radiographs or an ultrasound of the chest and abdomen to rule out bleeding, as well as blood tests to assess the extent of fluid loss. Pain relief and sedation should be offered immediately as first aid measures. If any life-threatening injuries exist, those must be prioritized – the broken leg can be temporarily stabilized with a bandage.

Once the dog’s situation is slightly more stable, further examination of lesser issues can begin – such as the leg. Radiographs will be taken to reveal the extent of the injury, showing, for example, a fracture of the tibia (lower leg bone). It’s a single fracture, diagonally through the middle of the bone, with no bones poking out through the skin (technically, it’s a simple oblique closed fracture of the tibial shaft). The fibula (the other bone in the lower leg) is also fractured in a similar way. The vet will need to take at least two radiographs from different angles for a comprehensive assessment of the injury. If the conditions permit, a CT scan may also be done.

Having diagnosed a tibial fracture, the vet recommends orthopedic repair to get your dog back to normal as soon as possible. Depending on the type of fracture, the vet might need to order special equipment, so the operation might be delayed a few days. In the meantime, your dog would need strict rest and pain management to prevent further injury.

The Day of Surgery Arrives

The vet will explain the procedure and list some of the equipment that will be used. The dog will be given pre-medication to provide further pain relief and keep it calm, then anesthetized to put it under. The leg will have the hair clipped and be surgically cleaned. Local anesthesia may also be administered.

The vet uses a bone plate and screws to fix the tibial fracture

This process will expose a lot of bone, which means the surgeon will first need to separate the skin and muscles from the leg. The surgeon will select and measure an appropriate bone plate to the size of his tibia and might bend it slightly for it to conform fully to his tibia. Then, the bone plate is directly placed on the fracture and holes for screws are drilled. Afterwards, screws are mounted onto the bone plate, one of which is a lag screw that fixes the two bone pieces together. The injured fibula is a non-weight-bearing small bone that can heal naturally without orthopedic intervention. Afterwards, the surgeon will use sutures to close up the muscles and skin. Once finished, two final x-rays are taken to ensure the correct positioning of the bone plate and screws.

The Post-Op Days and Check-Ups

It’s ensured that the external wound is healing. During this time, the dog will need to continue taking painkillers and be kept on strict rest. Regular check-ups over the next weeks are needed and depending on how things go, the leg is gradually mobilized. About a month later, the vet will take another x-ray of the leg to ensure that the orthopedic implants are still in place and the bones have healed. The fracture has almost entirely healed, so the surgery is deemed successful! As long as there are no future complications, the implants are left inside the dog. After a few more weeks of rest, it’s back to normal. Many dogs benefit from physiotherapy or hydrotherapy following surgery to help restore muscle to the injured leg.

This article is owned by PurrWoof (Changzhou) Pet Medical Co., LTD. The medical education information is provided for reference and information exchange only and does not constitute medical advice or diagnosis. Furthermore, this information may be limited by the knowledge and experience of the authors or relevant professionals and may not cover up to date medical research and practice. Therefore, the user is solely at the risk of relying on the information. No medical education information can substitute for professional medical advice, diagnosis or treatment. Before taking any health-related action, users should consult a qualified medical professional or seek appropriate medical advice.