When Dog ACL Surgery Goes Wrong. How to Handle Complications


A cruciate ligament injury in dogs refers to damage to the cranial cruciate ligament (CCL), which is similar to the anterior cruciate ligament (ACL) in humans. The CCL is an important ligament that stabilizes and supports the knee joint. Tears or ruptures of this ligament are a common orthopedic injury in dogs.

A partial or complete CCL tear will cause the knee joint to become unstable, leading to pain, inflammation, and lameness in the affected leg. Dogs may exhibit decreased activity levels, difficulty standing up or jumping, limping, or holding the leg up. Severe CCL damage can also lead to secondary knee issues like cartilage damage or osteoarthritis over time.

There are both surgical and non-surgical treatment options for CCL tears. Common surgical techniques include stabilization procedures like tibial plateau leveling osteotomy (TPLO) or tibial tuberosity advancement (TTA). Non-surgical options involve rest, anti-inflammatory medications, weight management, physical therapy, and knee braces. Treatment is aimed at restoring stability to the joint and preventing progression of arthritis.


The canine stifle joint, also known as the knee joint, is a complex structure composed of bones, muscles, tendons, ligaments, and cartilage. The major bones that make up the stifle joint are the femur, tibia, patella, and fibula. The joint allows for flexion and extension of the hindlimb as well as some internal and external rotation.

Two cruciate ligaments, named for the cross-shaped pattern they form inside the joint, provide stability and prevent excessive motion between the femur and tibia. The cranial cruciate ligament prevents the tibia from sliding forward in relation to the femur, while the caudal cruciate ligament limits hyperextension and inward twisting of the joint (Source).

Tears or ruptures of the cranial cruciate ligament are a common source of hindlimb lameness in dogs. This injury prevents the tibia from properly articulating with the femur and leads to instability, inflammation, and deterioration of the stifle joint over time.


A ruptured cruciate ligament is often caused by a combination of factors. Some of the most common causes include:

Obesity – Carrying excess weight puts increased stress on the knee joint and cruciate ligaments, making them more prone to tears and ruptures (VCA Hospitals). Keeping your dog at a healthy weight reduces this risk.

an overweight dog with a knee brace on

Trauma or injury – Sudden motions like jumping or sharp turns can partially or fully rupture the cruciate ligament (CSU Veterinary Teaching Hospital). This is known as an acute rupture.

Genetics – Some breeds like Labrador Retrievers are genetically predisposed to cruciate ligament issues. Weak collagen or improper development can increase the risk of tears (Brisbane Pet Surgery).


The most common symptoms of a cruciate ligament injury in dogs are lameness and difficulty bearing weight on the affected hind leg. Dogs will often avoid putting weight on the leg or limp when walking. There may be instability in the stifle joint and hind leg that causes the knee to buckle or give out, especially when turning or going up stairs. According to Embrace Pet Insurance, cruciate ligament injuries can range from mild to severe, but even partial tears will cause noticeable lameness.

Other symptoms reported on Paws and More Vet include lethargy, stiffness, swelling around the knee joint, muscle atrophy, and lack of extension on the affected limb. Owners may also notice the dog vocalizing from pain when moving around or hesitating to jump up onto furniture. As the condition worsens, dogs will increasingly shift their weight onto the good hind leg to minimize pain and discomfort on the injured one.


To diagnose a torn CCL, the veterinarian will start with a physical exam of the dog’s leg. They will check for instability in the knee by flexing and extending the joint and feeling for abnormal motion. The veterinarian may also perform drawer and tibial thrust tests where they attempt to push the tibia forward while feeling for laxity in the knee joint. A positive test indicatescomplete or partial tearing of the CCL (https://vetmedbiosci.colostate.edu/vth/services/orthopedic-medicine/canine-cruciate-ligament-injury/).

Imaging such as X-rays and MRI are often used to confirm the diagnosis and check for any related issues. X-rays allow the veterinarian to evaluate the knee joint for bone changes like arthritis that may have developed secondary to the CCL tear. They can also look for any bone fractures. MRI provides detailed imaging of the soft tissues like ligaments and tendons and will clearly show a torn or partially torn CCL. However, it does require anesthesia and is more expensive than X-rays (https://vcahospitals.com/know-your-pet/cruciate-ligament-rupture-in-dogs).

Non-Surgical Treatments

There are several non-surgical treatment options for dogs with cruciate ligament tears or ruptures. The main goals are to control pain and inflammation while improving joint stability. According to The Rehab Vet, the key elements of non-surgical treatment include:

Rest – Restricting activity and exercise is important, especially high-impact activities that put strain on the knee. Short, leashed walks are recommended to avoid further injury. Confinement or crating may be needed initially.

Anti-inflammatories – Non-steroidal anti-inflammatory drugs (NSAIDs) like Rimadyl or meloxicam help control pain and inflammation. Joint supplements like glucosamine may also be beneficial.

Braces – Custom orthopedic braces or splints can restrict and stabilize knee motion while healing. They must be worn consistently to be effective.

Rehabilitation – Physical therapy focuses on gradual joint mobilization and strengthening of the leg muscles to improve function. Exercises should be done daily. Additional modalities like cold laser therapy, massage, and acupuncture can also help recovery.

a dog doing physical therapy after knee surgery

According to Dogs Naturally Magazine, non-surgical options allow dogs time to heal while avoiding risks of surgery. However, they require 4-6 months of strict rest and rehab for the best results.

Surgical Options

There are several different surgical techniques used to treat cranial cruciate ligament injuries in dogs, with the main options being TPLO (Tibial Plateau Leveling Osteotomy), TTA (Tibial Tuberosity Advancement), and lateral suture techniques.

TPLO surgery aims to eliminate the need for the cranial cruciate ligament by changing the angle of the top of the shin bone (tibial plateau) to prevent the femur from sliding forward on the tibia (source: VCA Hospitals). This is one of the most common and successful surgeries for cruciate ligament injuries in dogs.

TTA surgery also works to neutralize the sliding force on the knee by advancing the tibial tuberosity, resulting in a more neutral angle of the patellar tendon (source: Colorado State University). This method has a high success rate as well.

Lateral suture techniques use strong suture material placed around the outside of the stifle joint to mimic the function of the torn cranial cruciate ligament (source: VCA Hospitals). While generally less expensive, this method may have a higher risk of complications.


The recovery period after ACL surgery is crucial for proper healing. During this time, post-operative care and physical therapy are essential to ensure the best outcome. The typical recovery timeline after surgery is 8-12 weeks [1].

In the first 2 weeks after surgery, the dog should be confined and only allowed short leash walks for 10-15 minutes 2-3 times per day [2]. Activity should be restricted during this time to allow proper healing and prevent re-injury of the surgical site. The dog should not run, jump, or play, and stairs should be avoided if possible.

Beginning at 2 weeks post-op, formal physical therapy can begin. This typically includes range of motion, stretching, massage, and other exercises. Hydrotherapy may also be incorporated. Physical therapy helps rebuild muscle strength and range of motion. Therapy sessions are done 2-3 times per week for 6-8 weeks. Activity can be gradually increased during this time, but running and jumping should still be avoided [3].

At 6-8 weeks post-op, leash walks can be extended to 30 minutes. By 10-12 weeks, the dog can start controlled off-leash activity. However, running and jumping should be avoided for a full 12 weeks to allow the bone and ligament to fully heal. Complete recovery takes about 12-16 weeks.


While most dogs recover well from cruciate ligament surgery, complications can occur. Some of the most common complications include:

Infection – There is always a risk of infection with any surgery. Signs of a surgical site infection include swelling, redness, drainage, and fever. According to one source, infection rates range from 1-4% after TPLO surgery (https://backmountainvet.com/complications-cruciate-surgery/). Infections are treated with antibiotics and sometimes additional surgery to clean the infected area.

a dog's bandaged leg after surgery

Continued instability – In some cases, the dog’s knee remains unstable after surgery. This is often due to improper surgical technique or failure of the implants/grafts to heal properly. Dogs with continued instability will limp and have difficulty standing. Revision surgery may be necessary to stabilize the joint.

Arthritis – Cruciate tears ultimately lead to arthritis in the knee. While surgery aims to stabilize the joint and slow arthritis progression, some dogs still develop significant arthritis. This is characterized by stiffness, limping, and difficulty standing up. Medications, injections, physiotherapy, and dietary supplements can help manage arthritis pain.


There are several ways to help prevent cruciate ligament injuries in dogs, including maintaining an ideal body weight, providing joint supplements, and ensuring proper exercise.

Keeping your dog at a healthy weight is crucial, as excess weight puts more strain on the joints and ligaments. According to one source, “obese dogs are more than twice as likely to suffer from cruciate ligament rupture” (https://www.physio-vet.co.uk/blog/how-to-prevent-cruciate-ligament-injury-in-dogs/). Follow your veterinarian’s recommendations for diet and weight management.

a dog doing plank exercise

Joint supplements containing glucosamine, chondroitin, and omega-3 fatty acids can also help strengthen connective tissue and prevent injury. Talk to your vet about supplement options suited for your dog.

Providing proper exercise is also key. Low-impact activities like swimming and walking help maintain joint health without overstressing the ligaments. Additionally, core-strengthening exercises like “planking” can increase stability and prevent tears. According to one study, “Our research shows a correlation between practice of core strengthening exercises and decreased risk of cruciate ligament rupture in agility dogs” (https://www.aaha.org/publications/newstat/articles/2022-02/planking-for-dogs-core-strength-could-help-them-avoid-cruciate-ligament-ruptures/). Consult your vet on designing an exercise program for your dog.

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