Radial Endoprosthesis for Bone Cancer (Osteosarcoma)
What is an osteosarcoma?
An osteosarcoma is an aggressive malignant tumour affecting the bone. It can affect any dog, however strong breed predispositions are seen. The cause of bone cancer is not known, although several theories have been postulated. Osteosarcomas occur most often in the long bones, particularly within the proximal humerus and distal radius in the forelimb and the proximal femur and distal tibia in the hindlimb. Early signs of osteosarcoma include lameness and painful swellings of the limb.
How is an osteosarcoma diagnosed?
Following initial consultation your dog will be admitted to the hospital to allow radiographs of the affected limb under sedation or general anaesthesia. if there is a high suspicion of a bone tumour from the radiographs it is likley we will carry out further imaging to see if the bone cancer has spread else where in the patients body. Your dog may also require advanced diagnostic imaging such as ultrasound, CT or MRI which will be performed by our advanced diagnostic imaging team. This allows the clinician to evaluate if your dogs bone tumour has metastasised, or spread, to other regions the body. Your dog will receive one-to-one nursing care throughout this process by one of our nurses from the prep nursing team who are all highly trained and experienced in anaesthesia and sedation. Once the clinician has identified the extent of your dogs disease they will be able to discuss treatment options and advise the best course of action for your dog. This will include surgical options such as limb-sparing surgery, amputation and chemotherapy. Fitzpatrick Referrals takes a multi-disciplinary approach to the management of osteosarcoma and it is likely you will meet with orthopaedic clinicians and oncology clinicians to discuss the best option for your pet.
What should I expect if my dog has been diagnosed with a bone tumour?
Sadly, bone tumours are quite common in dogs. They most frequently affect older large and giant breed dogs, although middle-aged dogs can also be affected. Tumours are also diagnosed infrequently in young dogs. Limping can vary from being mild and progressive, to being sudden in onset and severe. Some dogs experience sudden pathological fracture of a bone when they have been exercising vigorously. The most common tumour affecting canine bones is Osteosarcoma (OSA). Although bone tumours can involve the fore limbs or hind limbs, certain sites may predominate. The fore limbs (distal radius; just above the canine equivalent of our wrist) is commonly affected by OSA. Sometimes, swelling of the bone above the wrist is evident before lameness is noticed. Opacity, seen as grey mottling, is evident in this radiograph just above the wrist in this dog;
What is limb-sparing surgery?
As the name suggests, limb-sparing surgery is an approach taken to prevent the loss of a limb due to a disease process. The most common disease process limb-sparing surgery is used for is bone cancer, or more specifically an osteosarcoma (OSA). An endoprosthesis is used to replace the diseased section of the limb allowing the patient to retain near full function of the limb after surgery. This surgery can be an excellent option for large and giant breeds or dogs whose lifestyle would be severely impaired by amputation. Dogs with concurrent orthopaedic or neurological problems affecting their other limbs are also considerable candidates.
What is a Radial Endoprosthesis?
In dogs with bone tumours of the forelimb, the most common site affected is the bottom of the radius (more clinically known as the distal radius). The surgical procedure involves replacing the affected bone with a specially designed complex network of interlocking implants making one unit, an endoprosthesis. The endoprosthesis completely replaces the section of bone that needs to be removed and bridges the gap between the top and bottom of the dog’s leg to allow normal weight bearing. We utilize special manufacturing techniques to allow the patients own bone to become incorporated into the implant. We have used this technology for the management of bone cancer in dogs with great success over several years. Early comfortable use of the limb is typical with patients returning to near normal exercise routines after the recovery period.
Immediately post-surgery radiograph of radial endoprosthesis in the left forelimb:
3 Years following surgery. The patients own bone has entwined with the radial endoprosthesis
What is the typical recovery time after limb sparing surgery?
Careful rehabilitation after limb sparing surgery is the key to success and it is vital that patients that undergo this surgery are managed diligently for the first 5-6 weeks after surgery to prevent damage to the implant. During the first 12 weeks the bone grows into the endoprosthesis and the metal becomes part of the patient’s skeleton. After the initial 10 days patients are placed on a carefully managed exercise program that gradually brings them back to normal off-lead exercise by 12 weeks after surgery.
During your dogs hospitalised period they will be cared for by a dedicated team of ward nurses and ward auxiliaries who work alongside your dogs clinician, a team of veterinary surgeons and chartered physiotherapists ensuring all your dogs clinical and emotional needs are met. Because your dog is hospitalised for a number of weeks following surgery the patient care team make sure your dog feels at home and treat them just as if your dog belonged to them with the love and affection they desire and deserve.
What are the risks of limb-sparing surgery?
The main risks associated with limb-sparing surgery are implant failure, infection and local or distant reoccurrence of the cancer. Careful post-operative management will reduce the risk of early implant failure and with new generation implants in the longer term, implant breakage is rare. We aim to prevent infection by adhering to strict post-operative management protocols during the recovery phase. To help prevent reoccurrence of cancer we use post-operative chemotherapy to increase post-operative survival times.
Can my dog enjoy a normal lifestyle after radial endoprosthesis surgery?
The majority of dogs can return to normal exercise activities following the recovery period and enjoy the lifestyle they had before surgery. Your dog will require regular rechecks so we can make sure they continue to do well and will have to complete their course of chemotherapy prescribed by your oncology clinician.
Are there reasons why my pet should not have limb-sparing surgery?
We will not carry out limb-sparing surgery if there is any evidence of metastatic disease (tumour spread) affecting the lungs or other bones, as mean survival time is not considered sufficient at this advanced stage to justify surgical intervention in our view. Full limb amputation may still be considered in certain circumstances. There are also situations where we may consider that full limb amputation is advisable in preference to a limb-sparing surgery and every patient is assessed on a completely individual basis. Our goal is to always act in the best interests of each and every patient to provide optimal pain-free functional quality of life.
Is the bionic leg implant (PerFiTS) used for the treatment of bone cancers?
Animals with bone cancer may be suitable candidates for treatment using the PerFiTS device. This innovative technique has been used to treat animals where the foot is obliterated either by cancer (bone cancer or soft-tissue cancer), or by severe trauma to bones, muscles, nerves and/or blood vessels. This is a kind of limb-sparing surgery, but when the PerFiTS device is used, the entire distal part of the limb is replaced with an internal implant that passes through the skin and attaches to an external artificial foot (the exoprosthesis). By contrast, the endoprostheses we have described here are used for limb-sparing surgery when tumours affect the upper or lower parts of the limb, with the foot remaining unaffected by disease and can therefore be saved.
What should I do if I think my pet has a condition that would benefit from a limb-sparing procedure?
If you think your pet needs a limb-sparing procedure we recommend asking your primary care vet to contact us for further advice. We are more than happy to talk to your vet about what is involved with the surgery and ascertain if limb-sparing surgery could help your pet.