Cranial Closing Wedge Ostectomy (CCWO)

CCWO is a commonly performed surgical procedure to manage cranial cruciate ligament rupture. When the cranial cruciate ligament is ruptured there is instability in the knee as the shin bone (tibia) can move forward relative to the thigh bone (femur) when the dog is using the leg. This forward movement is driven by the sloped shape of the top of the shin bone (figure 1 – blue line) and is prevented when the cranial cruciate ligament is intact.

The aim of CCWO surgery is to reduce the steepness of this slope. Using the x-rays taken at the time of diagnosis the steepness of the slope is calculated and a surgery planned to remove a pre-determined angle of wedge of bone, which is cut out (ostectomy) from the top part of the shin bone (figure 1 – yellow wedge). The gap left when the wedge is removed is closed and therefore the steepness of the slope (figure 2 – blue line) is reduced to its calculated amount; the knee becomes stable, and the shin bone will no longer move forward. Once the gap is closed the bones are secured in their new position using a metal plate and screws (figures 2 & 3). This creates a strong repair and an environment where the bone will heal back to its original strength over the coming months. The important thing to remember is that the cranial cruciate ligament is neither repaired nor replaced; it is the change in the shape of the shin bone that re-establishes stability to the knee joint.

How long is the recovery?

Most dogs will start walking on the operated leg within 1-3 days of surgery with continued progress occurring over the coming weeks. Your pet will be receiving painkillers for a few weeks after surgery. The recovery period following CCWO surgery is usually around 12 weeks to the point where the patient is back to normal. Strict activity restrictions are imposed for the first month, after which controlled lead activity and freedom within the house are then progressively restored over the remainder of the recovery. Full postoperative management and activity instructions will be explained and provided by the team when you collect your per after their surgery. Initial checks on the wound and removal of any skin stitches will be undertaken by your own vet, however a follow up appointment will be arranged with your surgeon towards the end of the recovery period to ensure that your pet has made expected progress. At this follow up it is common for x-rays to be obtained under a light sedation to check bone healing and the plate and screws. If all is progressing as expected your pet will be signed off and swiftly returned to normal activity.

What is the outlook following surgery?

9/10 dogs will have an excellent outcome following CCWO surgery, with most being expected to return to normal activity without the need for ongoing pain relief. Knee osteoarthritis will slowly progress, however for most dogs this will not cause significant mobility problems moving forward.

What are the potential complications following surgery?

Our surgeons will have a thorough discussion with you ahead of surgery to make sure you are fully informed regarding possible complications. If a complication develops your pet is likely to require assessment by your surgeon. Investigations including x-rays and knee fluid collection and analysis may be required.

Thankfully with our experienced team, major complications following CCWO surgery are rare. The small risk of screw / plate breakage, screw loosening and bone fracture are minimised by following of the postoperative activity instructions. Unrestricted activity i.e. dogs doing too much too soon will increase the risk of this type of complication. Such complications are likely to require a second surgery. Other complications include such things as:

Infection – most are managed with oral antibiotic medication ideally based on the results of sample analysis.

Late shock absorber (meniscal) injury – most are managed by a short surgical procedure to remove the damaged position of the shock absorber.

Joint sprain / strain – most are managed with rest and painkillers.