33rd Annual Scientific Meeting proceedings

Minimally invasive fracture repair (MIFRE) in small animals has gained popularity over the last decades, mostly due to its lower invasiveness leading to potential lower morbidity, faster recovery and faster healing of the fracture by preserving the biological status of fracture site. MIFRE can be accomplished via stab or minimal skin incisions, and eventually guided by use of fluoroscopy and/or arthroscopy. Regarding MIFRE, articular fractures have been mostly treated by percutaneous reduction and k-wire/pins placement under fluoroscopic supervision. Use of arthroscopy for assistance in MIFRE is poorly described in the veterinary field and the goal of this lecture is to describe the potential advantages, disadvantages and indications of arthroscopy in this field.

Potential advantages for arthroscopy assistance in fracture repair include a superior visualization of the fracture reduction and minimal invasiveness. It provides a direct visualization of the cartilage surface with easier and safer access to narrow areas of the joint. The accuracy of the reduction can be evaluated intraoperatively before definitive stabilization and/or after implants placement. This allows the surgeon to modify and improve the reduction before going to postoperative radiographs. Improving the accuracy of the reduction can lead to a better outcome for the patient, although it is recognized that velocity of the trauma greatly influences degenerative joint disease. Other potential advantage of arthroscopy assistance is diagnosis of osteochondral damage to the articular surface during the trauma. Fragments can be removed and severe defects can be treated with micro picking based on surgeon’s preference. This can also have a direct influence on the prognosis. All those advantages have not been yet demonstrated in veterinary field and, as we will discuss later, lack also data in the human field.

All articular fractures could benefit from arthroscopy assisted reduction and internal fixation (ARIF)  in small animals. However, I believe this is especially true for the fractures that concern joints with a difficult access (hip, shoulder), fractures with a variable outcome (elbows) or fractures in which arthroscopy is easy to perform. Treatment of fractures of the cranial glenoid tubercle has been described with arthroscopy assistance for fracture reduction. Elbow arthroscopy can be used to evaluate the quality of the reduction and compression in humeral condylar fractures and fissures. Fractures of the acetabulum are tough fractures that are difficult to expose. Quality fo the reduction, especially the medial wall, is difficult to evaluate even with an arthrotomy. Use of arhroscopy during the procedure could help to control the quality fo the reduction.

In most of the fractures in small animals, quality of the reduction is evaluated with postoperative radiographs. More and more surgeons now become familiar with the use of fluoroscopy to control fracture reduction and implants placements in articular fractures. We believe that arthroscopy can be complementary to fluoroscopy to assist the surgeon in the OR and can be more precise than postoperative radiographs to evaluate the reduction. Radiographs have also shown lack of precision in articular surface reduction evaluation when it has been compared to CT scan, and quality of the reduction could be potentially improved by the use of arthroscopy intraoperatively rather than using CT in small animals. Although fluoroscopy is of great help in articular fracture management, it lacks precision when there is bone superimposition such as the distal radius or tibia, and the acetabulum. Bone superimposition can mask malreduction such as rotational malalignment or cranio-caudal translation. Lack of accuracy of postoperative radiographs and intraoperative use of fluoroscopy for wrist and ankle fractures has been described in the human literature. We believe that the se of arthroscopy may be beneficial to evaluate the quality fo the reduction in acetabular fractures, which are probably difficult to accurately evaluate on standard radiographs.

All those advantages remain « potential » as several limitations are observed concerning the use of ARIF. Although most orthopedic surgeons are familiar with scoping joints for orthopedic disease, most of us lack experience when evaluating a joint that has been traumatized. Anatomy is modified and visualization can altered by hematoma, fibrin and osteochondral fragments. It  can take some time to find anatomical landmarks and assess what could be a perfect reduction. When considering elbow fractures, which is probably the joint that is the most easy to scope in a normal joint, anatomical limitations include the size of the patients (in our clinic we mostly diagnose elbow fractures in growing small breed dogs, like a 4month-old french bulldog…), but also the fact that most fractures concern the lateral condyle while the conventional approach for elbow arthroscopy is medial, which could then necessitate to modify the position of the patient during surgery, after temporary reduction or definitive stabilization. We have already used a mini lateral arthrotomy to place a scope inside the elbow joint and evaluate the joint surface. Size of the patient can be a limit depending on the size of the scopes that are available in the practice.  Other joint such as the carpus are not commonly scoped and assessment of fracture reduction can therefore be difficult, resulting from a lack of anatomical landmarks in carpus arthroscopy. Hip arthroscopy is more commonly performed but, from our brief experience, a joint flush should be performed to correctly visualize the traumatized acetabulum and eliminate hematoma.

Another limitation in the use of ARIF is the limitation in the evaluation of the position of implants. The surgeon can evaluate absence of joint penetration or interference with joint movement, but it can not control the orientation of the implant inside the bone (which can be performed with fluoroscopy). When considering a fracture of the cranial glenoid tubercle, the fracture can be nicely reduced using a k-wire inserted in the fragment. It is more difficult to correctly place a larger implant without approaching the fragment via a cutaneous incision, or without using fluoroscopy. This leads to another limitation which is the type of implants which can be used: k-wires, pins, and cannulated screws. Articular fracture treatment necessitate anatomical reduction and compression, which can mostly be obtained via bone forceps or using manual compression with k-wires. However, in the cranial glenoid, if a cannulated screw can not be placed, a screw may be inserted beside the k-wire holding the reduction, which may not be feasible under arthroscopy guidance. In small patients, it is preferable to place a tension band which necessitates an open approach. It has been described to release the bicipital tendon to relieve the pressure form the biceps on the cranial glenoid tubercle but we believe that this should not be a primary repair option.

Another indication for arthroscopy in the management of small animal fractures is the control of implants placement when performing ARIF. This can be used during the procedure or during the follow-up if any residual lameness is observed while suspecting intra-articular implants.

Overall, surgical skills as well as time to set up the arthroscopic instrumentation are a limitation. Development of nanoscopy/needle scope could lead to increased experience in ARIF as it is much easier to set up (one cable for the camera and light source, no need for surgical pump or pressure bags, simple use of a syringe to flush the joint) and allows evaluation of small joints while using a large field of view to compensate its 0° angle view.

In human surgery, arthroscopy assisted MIFRE is becoming more used. Indications are quite broad, including all joints. However there is still a lack of evidence in most indications based on the low number of blind double placebo studies. One limitation in human surgery is the specificity of surgeons. Arthroscopists generally manage sports medicine cases but rarely trauma cases, while trauma surgeons are not commonly using arthroscopy techniques and may lack skills to practice ARIF. Some studies have shown a benefit of the use of arthroscopy regarding the quality of the reduction, such as in the ankle, especially when assessing the rotational alignment of the medial malleolus or assessing the quality of reduction of the syndesmosis. The evaluation of associated soft tissues and osteochondral lesions are recognized adamants of the use of arthroscopy in most reports. It seems also to be beneficial in distal radial fractures, restoring a better reduction and functional outcome. Multiple meta-analysis have been recently published. They seem to point out a lack of evidence of the superiority of ARIF when compared to ORIF regarding the outcome of the patients.

We will try to illustrate the use of arthroscopy in small animal fracture management through various cases to try to define the indications, technical skills required, instruments and limits of this technique.

References

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