Cranial Closing Wedge Osteotomy
This is a surgical procedure that involves adjusting the tibial plateau (the surface at the top of the shin bone) by cutting out a wedge of bone from the front of the shin.
What is CCWO surgery?
Image copyright of Rebecca Jones
Image of a canine knee joint with a torn cranial cruciate ligament.
The backwards slope of the shin bone causes the thigh bone to slip backwards in relation to the shin bone (and vice versa) if the cranial cruciate ligament is unable to resist this movement. The menisci are pictured here in blue – these are cartilage structures which act as shock absorbers within the joint.
Image copyright of Rebecca Jones
Image of a canine knee joint with a torn cranial cruciate ligament following CCWO.
The angle of the tibial plateau has been adjusted to make the top of the shin bone almost flat. This reduces slipping of the thigh bone backwards in relation to the shin bone (and vice versa) when walking. The cut portions of the bone have been secured with a plate and screws.
How does CCWO surgery work?
What does CCWO surgery involve?
The procedure may vary slightly depending on your surgeon and they will be able to provide you with more specific information.
All CCWO procedures are performed under a general anaesthetic. Specialised X-rays will be performed (if not taken previously) to allow specific surgical measurements, which can vary widely between different dogs. Your dog will likely need to have a full clip of the affected leg stretching from the ankle to the hip.
Generally, surgery will start with opening the capsule surrounding the knee joint and assessing for any damage to the shock-absorbing cartilage pads which sit between the bones (menisci). If any damage is seen then these areas must be removed before the CCWO is performed. This may be done as an open approach, or keyhole – with a specialised camera.
The shin bone is exposed and marked with measurements calculated from the pre-operative X-rays. A wedge-shaped section of bone is then cut using a saw blade and the cut portion removed. The remaining two sections are closed using a special plate and screws to hold the bone together while it heals.
X-rays are taken at the end of surgery to make sure the plate and screws are in the right position and the new angle is flat enough.
What does post-operative care involve?
Medication
Your dog will require a course of pain relief and sometimes antibiotics following surgery, these are typically given orally in tablet or liquid form.
Exercise
Managed exercise is beneficial during the recovery, however, this must be strictly controlled and will be significantly reduced during the first eight weeks following surgery. In the period immediately following surgery, your dog will be required to be crate-rested or confined to a small room without access to furniture to jump on and off. Your surgeon will provide you with more detailed instructions on how to manage your dog’s exercise following surgery.
Follow up visits
Dependent on how your dog’s surgical wound has been repaired a follow-up visit to your vet is often needed around two weeks after surgery, most dogs will need to wear a buster collar until this time to prevent interference with the wound which may lead to infection or opening of the surgical site.
Post-operative X-rays are usually collected around eight weeks after surgery to check healing is progressing well.
Weight control
Unfortunately, regardless of treatment (or lack of treatment), all dogs are likely to be predisposed to the development of osteoarthritis in the affected joint following cranial cruciate ligament disease, because of this it is recommended that they maintain a slim body condition. Your vet will be able to give you more information regarding weight control plans if this is required.
Hydrotherapy/physiotherapy
Hydrotherapy/physiotherapy can be useful in the postoperative period and can be considered once the skin wound has healed. Your vet can advise you if this is appropriate for your dog.
What is the prognosis following CCWO?
All dogs with cranial cruciate ligament rupture are expected to eventually develop at least some signs of osteoarthritis in the affected joint but this is likely to be reduced or delayed in dogs who have had a surgical procedure.
Around 50% of dogs will develop cranial cruciate ligament disease in the other hind limb, in some cases this surgery and in others, it may be many years.
What are the risks of a CCWO?
Unfortunately, complications can occur with any surgical procedure. The complication rate for CCWO surgery is considered to be low, but potential complications include;
Infection
Any surgery carries a small risk of infection. Orthopaedic surgery carries a slightly higher risk because bacteria can stick to the metal implants which makes it difficult for the immune system to reach them. To reduce this risk, all dogs receive antibiotics during surgery. If your dog licks their wound after surgery, they can introduce infection.
Screw-loosening/Implant failure
In a small number of dogs, the screws that hold the bone in its new position can become loose over time. If this happens, excessive movement of the bone segments against one another can delay healing and in the worst-case scenario, the plate can break and require replacement. The risks of this happening increase substantially if exercise is not sufficiently restricted following surgery.
Delayed healing of the bone
The bone needs to heal to become strong enough to support your dog’s normal activity. All dogs heal at slightly different rates and sometimes patience is required. However, insufficient exercise restriction after surgery as well as some underlying health conditions can predispose a dog to slow healing.
Patellar Tendon Damage/Inflammation
The cut in the tibia is made very close to the point at which the tendon which attaches to the kneecap (patellar tendon) inserts onto the bone. While every effort is made to protect it, damage to the tendon is possible during the cutting of the bone. The tendon can also become inflamed or subsequently affected by the change in angle of the tibia in the months following surgery due to alteration in the forces acting across the joint.
Subsequent meniscal injury
In up to 7% of cases, the menisci appear normal at the time of surgery but are later damaged due to continued, mild degrees of joint instability. If this is the case, lameness may persist longer than expected post-surgery, or dogs may seemingly recover before suddenly becoming lame on the leg once more. If this occurs, repeat surgery will be required to inspect the meniscus for damage and cut away any torn portions.
Which dogs will benefit from a CCWO?
A large selection of equipment sizing allows for dogs of different sizes to undergo a CCWO procedure. However, your vet will discuss whether this is the appropriate procedure for your dog.
CCWO is often more expensive than other procedures and less widely offered, which may affect your decision. It also involves a much stricter period of exercise rest with greater potential for serious complications if this is not enforced compared to procedures such as the lateral suture.
Contraindications for surgery may include;
- Dogs who are receiving medication that suppresses their immune system and makes them likely to experience delayed fracture healing.
- Dogs with limb deformities that may need to be corrected by other procedures.
Contributors
Author: Dr Aaron Lutchman BVSc MRCVS
Aaron graduated from the University of Liverpool in 2016. He worked for two years in first opinion practice in both rural North Wales and London before completing both a Rotating and Orthopaedic Internship at the Royal Veterinary College. Aaron returned to Liverpool University in 2021 and is currently undertaking an Internship in Anaesthesia and Soft Tissue Surgery.
Editor: RCVS Knowledge Communications Team
Reviewer: Dr Catrina Pennington BVM&S MRCVS and Mark Morton BVSc DSAS(Orth) MRCVS
References
- Slocum, B. and Devine, T. (1984) Cranial tibial wedge osteotomy: A technique for eliminating cranial tibial thrust in cranial cruciate ligament repair. Journal of the American Veterinary Medical Association, 184 (5), pp. 564-569
- Oxley, B. et al. (2013) Comparison of complication rates and clinical outcome between tibial plateau levelling osteotomy and a modified cranial closing wedge osteotomy for treatment of cranial cruciate ligament disease in dogs. Veterinary Surgery, 42 (6), pp. 739-750. DOI: https://doi.org/10.1111/j.1532-950X.2013.12033.x
- Corr, S.A. and Brown, C. (2007) A comparison of outcomes following tibial plateau levelling osteotomy and cranial tibial wedge osteotomy procedures. Veterinary and Comparative Orthopaedics and Traumatology,20 (4), pp. 312-319. DOI: 10.1160/VCOT-07-02-0013
