By Jessica McCarthy, BVSc

Orthopedic surgeons are often known for their love of "toys," from intraoperative C-arm fluoroscopy units to goniometers; if a piece of equipment can be engineered to assist in the task, then we want it.

Indeed, I have detailed some of the equipment I have used most often and find the most useful for clinical assessment and treatment of both first opinion and referral orthopedic cases. Although there is a wide variety of tools and equipment available, often the simple tools are the ones we reach for the most frequently.

Patient assessment equipment

Goniometer. For patients with osteoarthritis or other orthopedic disease with limited joint range of motion, the goniometer can provide a numerical value for monitoring the patient's response to therapy. If you are implementing any sort of physiotherapy plan, even if it is at home physiotherapy exercises the owners are performing, then this piece of equipment is an absolute must have.

There is a degree of subjectivity due to the limitations of positioning a goniometer in an awake patient; however, if the same observer is repeating the measurement each time, it can provide a way to help measure the success of your and/or the owner's physiotherapy. This works best for patients who can be readily examined in lateral recumbency and becomes more challenging as the muscle mass increases more proximally in the limbs (i.e. the hips and shoulder are the most challenging to assess with goniometry).

Slow motion video capture. The addition of a slow motion camera to smart phones provides one of the most commonly used tools in our orthopedic clinic. When taking slow motion video, use a well-lit area with an even surface and minimize distractions for the patient by closing nearby doors. Symmetrical gaits, such as the walk and trot, are the easiest to interpret.

Take the video as close to the level of the patient as possible (Figure 1). Slow motion helps identify the lame limb, can allow for a subjective assessment of range of motion of the joints during gait, allows identification of circumduction, abduction or adduction of a limb, and can be used to demonstrate a lameness to owners.

Capturing a video also provides documentation of the lameness to reference at a later date for monitoring of progress, which is particularly useful if the patient sees a different veterinary surgeon for the follow up appointments. Local laws and guidelines should be followed regarding owner consent and storage of all videos.

Equipment to simplify the surgical approach

Electrocautery. For those who have access to electrocautery, this is probably a no brainer. Using electrocautery allows for a near bloodless field during the surgical approach, which makes the identification of tissue plains and important landmarks much easier. Monopolar cautery has been associated with patient burns,¹ therefore, it is important to ensure good patient contact with the grounding mat.

Personally, I prefer bipolar cautery as it completely avoids the risk of patient burns and does not require the grounding mat. Bipolar cautery requires a pedal for operation, and most units can be switched between bipolar and monopolar, depending on which hand piece is attached.

Another advantage of bipolar is it can cauterize even if a small amount of fluid is present, whereas monopolar cautery requires no surrounding moisture for best results.

The bipolar can take a bit of getting used to as you have to carefully position the tips so they are either side of the vessel you are cauterizing, allowing the current to run between them. If you clench too tight and the tips touch each other, the current will not contact the vessel; therefore, cauterization will not occur.

Periosteal elevator. A periosteal elevator is primarily used to reflect muscles, tendons, and other soft tissues away from bone.² It is also commonly (and perhaps some would say inappropriately) used as a makeshift retractor, a guard for soft tissues against drill bits, saws and other sharp objects, and sometimes to gently lever bone into position.

The most commonly used are the Freer, Sayre, and AO periosteal elevators (Figure 2). I like to have all three varieties on hand, but the Freer and AO are the most commonly used.

The Freer is useful for finer elevation, particularly in close proximity to joints or ligaments. I find it very useful for elevating soft tissues and periosteum to allow visualization and marking of the bone prior to an osteotomy. The AO periosteal elevator can be useful for creating epi periosteal tunnels along the diaphysis of larger bones, such as the femur and tibia, whilst the Sayre sits right in the middle between these two. Regular maintenance is essential to keep the ends sharp.

Retractors. Self-retaining retractors can revolutionize the view you have in your surgical field. Self-retaining stifle retractors (Figure 3), for example, can greatly enhance the working space in the joint and allow for thorough probing of the menisci during an arthrotomy. They must be placed with extreme caution to reduce damage to articular cartilage, with the proximal tip in the intercondylar notch and the distal cranial to the intermeniscal ligament, avoiding the articular portion of the tibia.

Gelpi retractors are very helpful for enhanced visibility, and we frequently use several pairs to maximize visibility when there are multiple layers of muscle between the surgeon and area of interest, such as with femoral head and neck excision (FHO). Of course, care for local anatomy, particularly nerves, must be taken when placing any retractor.

Wish list equipment

Force plates and pressure mats. For generating truly objective data on patient lameness and outcomes following surgery, a pair of force plates is usually considered the gold standard. These require installation into a walkway system. The results take time to interpret fully, but can provide valuable insights into the effects of instituted treatments and procedures.

Other than the large initial investment, the space required (usually a minimum of 50 ft) and the time it takes to gather good quality data prevent their widespread use. A more accessible gait analysis tool is a pressure-sensitive walkway or even a simple standing pressure mat as both of these can be stored and then easily rolled out on any even surface in the clinic.

The results tend to be provided in a user-friendly format (system dependent) and showing owners these results can greatly enhance their engagement in the treatment process of their pets.

Intraoperative fluoroscopy. Often at the top of many orthopedic surgeons' wish list is a C-arm fluoroscopy unit for the operating room. The "mini" C-arm allows for great maneuverability and is extremely useful when performing fracture repairs close to articular surfaces or physes, or when using minimally invasive techniques. Radiation safety is of paramount importance and there is a space requirement in the operating room to allow the units to be maneuvered into and out of position as required.

In the absence of a fluoroscopy unit, I have utilized a much less costly mobile radiography unit, similar to the ones our large animal colleagues use out in the field. This can be useful if a single image is all that is required intraoperatively, although some pre planning is required to allow cassette insertion and removal without compromising sterility.

Jessica McCarthy, BVSc, currently works at Auburn University as Assistant Professor of Small Animal Orthopedics. She has recently become a diplomate of the European College of Veterinary Surgeons. Dr. McCarthy attended Bristol University for her veterinary degree and spent two years in general practice in England after graduating. On her path to specialization, she completed a small animal rotating internship at the University of Cambridge, an orthopedic internship at Liverpool University and her residency at the University of Edinburgh. She has a particular interest in elbow disease both developmental and traumatic. McCarthy is passionate about ensuring everyone in the veterinary profession can work in a diverse and inclusive atmosphere.

References

1. Gomes C, Radke H. Monopolar burns as a complication of electrosurgery: a case series. InBSAVA Congress Proceedings. 2017; Apr 1; pp. 544-545. BSAVA Library.
2. MA Nieves, SD Wagner: Surgical instruments. D Slatter Textbook of small animal surgery, third edition. 2003 Saunders Philadelphia 185