Surgery STAT: Limb sparing procedure is another option for dogs

Surgery STAT: Limb sparing procedure is another option for dogs

Amputation remains the standard of care to address most primary tumors of the appendicular skeleton, particularly sarcomas. As a general rule, dogs adapt well to amputation, regardless of size. However, dogs suffering from concurrent orthopedic or neurologic diseases, or those with owners opposed to amputation, may be poor candidates for this procedure. In those cases, limb sparing may be an option. As the name implies, limb sparing is a surgical procedure in which a portion of diseased bone is removed or treated while limb function is preserved.

Proper staging must be performed to ensure the procedure is in the best interest of the patient. Surgical planning to ensure appropriate margins for both soft and bony tissues is essential. Advanced imaging such as CT and MRI may facilitate this, as well as help determine whether the patient is even a candidate for limb sparing.

The techniques for limb sparing, prognosis for functional outcome and complications seen are dependent on the anatomic location of the tumor. The site most amenable to limb spare is the distal ulna. It can be removed and does not need to be replaced. Ideally, the interosseous ligament is preserved. If the styloid process must be excised with the tumor, reconstruction of the lateral collateral ligament or pancarpal arthrodesis will maintain stability of the antebrachiocarpal joint. The prognosis for limb function is usually excellent.

Photo 1: Dog undergoing limb sparing surgery using the allograft technique. The allograft is being held by the surgeon. The plate has been applied to the allograft, and it will be placed into the bony defect present from having removed the distal aspect of the radius harboring the tumor. The plate will then be applied to the proximal aspect of the remaining radius and the carpus and metacarpal bone.
The anatomic site receiving the most attention for limb sparing is the distal radius. It is one of the most common sites for osteosarcoma in dogs. Most commonly, the diseased distal radius is replaced with a cortical allograft (Photo 1). Unfortunately, the complication rate is high, with infection seen in up to 70 percent of limbs and local recurrence and implant problems in as many as 60 percent of the limbs.

This technique does require maintenance of a bone bank or purchase of a commercially available cortical allograft. A metallic endoprosthesis with specialized bone plate now is available as an alternative to cortical allograft. A study comparing the endoprosthesis and cortical allograft found no difference in complication rates.

The distal radius can be replaced with viable autograft using distraction osteogenesis or transfer of an ulnar segment. Distraction osteogenesis utilizes the principles and techniques developed by Ilizarov.