1. Dogs are susceptible to cruciate ligament injuries

Cranial cruciate ligament disease (CCLD) is the leading cause of hindlimb lameness in the dog (Powers et al 2005).

The cranial cruciate ligament (CCL) is the canine equivalent of the human anterior cruciate ligament.

Cranial cruciate ligament disease is usually caused by chronic degenerative change. 

The CCL is the primary passive stabiliser of the canine stifle joint, its craniomedial band taut during flexion, while the caudolateral band and lateral collateral ligament relax to allow for tibial internal rotation (de Rooster et al 2006).

In addition to stifle joint stability, these ligaments provide mechanoreceptor and proprioceptive input (de Rooster et al 2006).

Injuries of the human anterior cruciate ligament typically result from acute, non-contact trauma involving deceleration or acceleration in combination with a knee valgus load (Logerstedt et al 2010).

Acute CCL rupture in dogs can result from a single high-load traumatic event; however, in most cases CCLD is the result of normal forces placed on a ligament that has undergone chronic degenerative change (Jerram & Walker 2003, Hayashi et al 2003).

This process is progressive, involving gradual degeneration of the CCL and stifle joint inflammation, and leads to partial and eventually complete ligament rupture (Hayashi et al 2003).

Secondary osteoarthritis frequently develops (de Bruin et al 2007).

2. Identifying risk factors is important in managing cruciate ligament disease

The aetiopathogenesis for CCLD is complex and not completely understood (Comerford et al 2011).

A variety of dog breeds are affected, with the highest prevalence seen in the Newfoundland, Rottweiler, Labrador Retriever, Bulldog and Boxer (Witsberger et al 2008).

A genetic basis for inheritance has been identified in Newfoundlands (Wilke et al 2006).

A number of risk factors for CCLD include:

• an increased prevalence in female dogs and in neutered over sexually intact dogs (Slauterbeck et al 2004)


• obesity, with overweight dogs demonstrating altered kinematics relative to healthy-weight dogs (Lapman et al 2003, Bray et al 2013)


• medial patella luxation, genu varum and conformational variations such as a straight stifle joint angle, narrow distal femoral intercondylar notch and steep tibial plateau angle (TPA) (Haynes et al 2015, Schwandt et al 2006, Mostafa et al 2009)


• age, given that material properties of the CCL decrease with age, increasing the risk of rupture in dogs aged more than four years, especially in ‘high risk’ breeds (Witsberger et al 2008, Duval et al 1999)


• breed variation in biomechanical properties of the CCL, with significantly lower load-to-failure properties reported in some breeds (Wingfield et al 2000a, Wingfield et al 2000b)


• immune-mediated conditions of the stifle (Doom et al 2008).

Despite the multiple risk factors for CCLD, it remains unclear which of these lead to disease initiation (Hayashi 2018).

3. Extracapsular techniques can be effective in cruciate ligament repair

Lateral fabellar stabilisation (LFS) (also known as the De Angelis procedure) is an extracapsular repair technique (De Angelis & Lau 1970).

The fabellae are small sesamoid bones, one for each tendon of the two heads of gastrocnemius (Kowaleski et al 2018).

There are a number of risk factors for cranial cruciate ligament disease, including sex, age, weight and breed. 

With LFS, the aim is to passively stabilise the stifle and prevent cranial (anterior) tibial translation with respect to the femur, which would normally be prevented by the intact CCL (Heffron & Campbell 1978).

A non-absorbable synthetic suture material is passed around the lateral fabella and back through one or two bone tunnels made in the tibial tuberosity (Casale & McCarthy 2009).

The suture is held taut by a knot or crimp clamp (Lotsikas et al 2013).

The suture material eventually stretches or breaks, but the temporary stabilisation it provides allows for the formation of organised scar tissue, ultimately leading to long-term stability (Warzee et al 2001).

The advantages of LFS are its relative technical ease and shorter surgical time; however, low tensile strength or increased creep of the suture material can lead to insufficient or excessive scar tissue formation and joint laxity (Christopher et al 2013).

4. Corrective osteotomies change biomechanics but provide long-term stability

Tibial plateau levelling osteotomy (TPLO) and tibial tuberosity advancement (TTA) are the two most common corrective osteotomy techniques performed (Conzemius et al 2005).

TPLO involves cutting a curved osteotomy through the proximal tibia and rotating the tibial plateau segment to achieve a lower TPA (Lotsikas et al 2013).

After rotation, a plate and screws are applied to stabilise the osteotomised segment (Kowaleski et al 2018).

The aim is to neutralise cranial drawer by levelling the tibial surface so it is perpendicular to the load applied during weight-bearing (Kowaleski et al 2018).

TPLO alters biomechanics by placing additional reliance on the caudal cruciate ligament and muscular stabilisers of the stifle.

TTA involves an osteotomy caudal to the tibial tuberosity and advancing of the tibial tuberosity so the patellar tendon is perpendicular to the tibial plateau.

A titanium cage and plate hold the advanced portion of bone in place (Kowaleski et al 2012).

TTA neutralises cranial drawer by altering forces through the stifle to be parallel to the patellar tendon, providing a biomechanical advantage to the quadriceps muscles (Guerrero et al 2011).

This procedure is less technically demanding but has a higher incidence of postoperative patellar tendonitis and meniscal tears compared with TPLO (Hurt et al 2011).

More recent studies have shown that TPLO and TTA are superior to extracapsular stabilisation techniques, with TPLO providing better long-term radiographic and functional outcomes than TTA (Krotscheck et al 2016, Moore et al 2020).

5. Physios play an important role in postoperative outcomes

Physiotherapy following CCL stabilisation has been reported in three studies (Marsolais et al 2002, Monk et al 2006, Jerre 2009).

Physiotherapy is important for recovery after surgical stabilisation of the cranial cruciate ligament. 

Marsolais and colleagues (2002) assessed the effectiveness of passive range of motion (PROM), massage, walking and swimming following extracapsular stifle stabilisation and found improvements in peak vertical force and vertical impulse six months after surgery.

Monk et al (2006) compared the physiotherapy modalities of cold, massage, PROM, underwater treadmill and progressive functional exercises to a home exercise program in dogs following TPLO.

At six weeks thigh circumference and stifle PROM was significantly greater in the physiotherapy group compared with controls (Monk et al 2006).

Jerre (2009) compared two groups, with the control group receiving a graduated walking program, with instructions for massage and stretching provided to the owner.

In addition, the treatment group received swimming and transcutaneous electrical nerve stimulation.

No significantly detectable differences were reported between the two groups.

It has been suggested that physiotherapy following CCL stabilisation may be more important in terms of overall patient outcome than the choice of surgical technique (Marcellin-Little & Arnoldy 2018).

Click here for an infographic poster version of this article.

>> Katrinka Geelen, APAM, works as a physiotherapist at Queensland Veterinary Specialists. She has a postgraduate diploma in veterinary physiotherapy and is currently researching canine cruciate disease as part of her master’s degree in veterinary physiotherapy.

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