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. 2022 Feb 6;67(4):163–178. doi: 10.17221/111/2021-VETMED

Patellar luxation and concomitant cranial cruciate ligament rupture in dogs – A review

Mario Candela Andrade 1,*, Pavel Slunsky 2, Luise Grace Klass 3, Leo Brunnberg 4
PMCID: PMC11334444  PMID: 39170807

Abstract

A patellar luxation and concomitant cranial cruciate ligament rupture is a common pathology in dogs. Diagnosis is based on clinical evidence of a patellar luxation and stifle joint instability. However, diagnostic imaging is required to assess the number of skeletal deformities and signs of instability. Surgical options include both soft tissue and osseous techniques, although, in most cases, a combination of multiple procedures is necessary to correct the patellar luxation and restore the stifle joint stability. Complication rates are generally low, but can include reluxation and implant-associated complications. This article describes the patellar luxation and cranial cruciate ligament rupture signs in dogs, including the clinical presentation and diagnosis, and discusses current treatment options.

Keywords: canine lameness, knee surgery, stifle pathology

Introduction

Patellar luxation (PL) and cranial cruciate ligament ruptures (CCLRs) are common orthopaedic issues in dogs, which have been well described over the years (Jerram and Walker 2003; Di Dona et al. 2018). The combination of both pathologies differs significantly between small and large breed dogs. In contrast to both PL and CCLR individually, limited literature is available on the combination of both orthopaedic problems. Therefore, the purpose of this article was to review the most current veterinary literature and take a close look at the pathogenesis, diagnosis and surgical techniques available to treat the combination of these common orthopaedic pathologies.

Pathogenesis, prevalence, affected breeds and risk factors

PATHOGENESIS

Currently, two hypotheses regarding the pathological connection of PL and CCLR are under debate, although both are yet to be proven.

Theory I: Patellar luxation as a primary cause for CCLR

The quadriceps muscle group, trochlear groove, patellar ligament and the tibial tuberosity form the extensor mechanism of the stifle. A decreased angle of inclination of the femoral neck has been named as a cause of laxity of the extensor mechanism (Kowaleski et al. 2018).

Malalignment of the extensor mechanism during the growth period can lead to patellar instability as well as secondary bone changes and the absence of physiological pressure on the trochlear groove during growth, leading to a lack of width and depth commonly named trochlear hypoplasia (Petazzoni 2014). Anatomical changes observed in these patients include: distal femoral varus or valgus, external or internal torsion of the distal femur, proximal tibial varus or valgus and internal or external tibial torsion and a shallow trochlear sulcus (Wandgee et al. 2013; Yasukawa et al. 2016; Kowaleski et al. 2018).

It has been postulated that malalignment of the quadriceps mechanism, which leads to instability of the stifle joint, skeletal changes and abnormal stress on the stifle joint and the cranial cruciate ligament (CCL) can cause CCLR (DeAngelis and Lau 1970; Hayes et al. 1994; Marsolais et al. 2002). In addition to this, the progression of osteoarthrosis, joint effusion and degenerative joint disease could also contribute to CCLR in older dogs (Campbell et al. 2010).

Theory II: Cranial cruciate ligament rupture as a primary source of instability in the stifle joint

Preventing excessive internal rotation between the femur and tibia is an important function of the CCL (Arnoczky et al. 1977; Robins 1990). When the ligament ruptures, the lack of internal rotation constraints could lead to a patellar luxation or increase the grade of a pre-existing patellar luxation. This theory is supported by studies which have demonstrated that CCLR influences the Q-angle, the angle between the vector force of the quadriceps muscle, patella and patellar ligament (Kaiser et al. 2001). However, further studies are warranted to investigate the effect of a ligament rupture on the development of patellar instability.

PREVALENCE OF PL AND CONCOMITANT CCLR

While patellar luxation can be medial, lateral or bidirectional, most cases report a medial luxation and are diagnosed in small breed dogs. Lateral patellar luxation is less frequent and more commonly diagnosed in larger breeds (Roush 1993; Hayes et al. 1994; LaFond et al. 2002; L’Eplattenier and Montavon 2002; Harasen 2006; Di Dona et al. 2016; Bosio et al. 2017). Medial patellar luxation in small breed dogs is 12 times more frequent than in larger breeds (Priester 1972) and female predispositions have been identified (Priester 1972; Hayes et al. 1994; Alam et al. 2007; O’Neil et al. 2016; Bosio et al. 2017). Moreover, a connection to the neuter status has been described (O’Neil et al. 2016). Bilateral patellar luxation has been described with varying frequency (Hayes et al. 1994; Arthur and Langley-Hobbs 2006). Patellar luxation is generally graded from I to IV (Singleton 1969) (Table 1).

Table 1. Singleton classification for patellar luxation (Singleton 1969).

Patellar luxation Description Rotation of the proximal tibia in relation to distal femur
Grade I patella can be manually luxated, but returns to normal position when released no rotation
Grade II patella luxates with stifle flexion or on manual manipulation and remains luxated until stifle extension or manual replacement occurs tibial rotation up to 30° is achieved
Grade III patella continuously luxates and can be manually replaced, but will reluxate spontaneously when manual pressure is removed between 30° and 60°
Grade IV patella is permanently luxated and cannot be replaced manually between 60° and 90°
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Prevalence reports on the combination of both pathologies differ significantly. One study found that 15–20% of stifles in middle-aged and older dogs with PL had concomitant CCLR (Piermattei and Flo 1997).

Other studies in small breed dogs with PL found a 22–41% incidence of concomitant CCLR (Campbell et al. 2010; Candela Andrade et al. 2020) and only 13% in large breed dogs (Gibbons et al. 2006). Moreover, CCLR has been found in 41% of large breed dogs with a medial patellar luxation (MPL) (Brower et al. 2017).

AFFECTED BREEDS

Breeds most commonly affected by PL include the: Yorkshire Terrier, Chihuahua, Pomeranian, Poodle, French Bulldog, Lhasa Apso, Cavalier King Charles, Bichon Frise, Pug, Spaniel, Bulldog, West Highland White Terrier, Jack Russel Terrier and Shih-Tzu (Arthurs and Langley-Hobbs 2006; Alam et al. 2007; Bound et al. 2009; O’Neil et al. 2016).

Studies suggest that up to 38% of dogs diagnosed with an MPL are medium to large breed dogs (Priester 1972; Hayes et al. 1994; Gibbons et al. 2006) and commonly affected breeds include the: Chow Chow, Dutch Flat Coated Retriever, Great Pyrenees, Bulldog, Labrador, French Bulldog, English Bulldog and Staffordshire Bull Terrier (Hayes et al. 1994; LaFond et al. 2002; Gibbons et al. 2006; O’Neil et al. 2016).

In studies including dogs with PL and concomitant CCLR, Yorkshire Terriers, Chihuahuas, Labrador Retrievers, Golden Retrievers, Staffordshire Bull Terriers and American Staffordshire Terriers have been named as the most common breeds (Campbell et al. 2010; Langenbach and Marcellin-Little 2010; Yeadon et al. 2011; Leonard et al. 2016). Moreover, a breed predisposition for Maltese dogs was found (Candela Andrade et al. 2020).

RISK FACTORS

The aetiopathogenesis is believed to be multifactorial. Risk factors include malalignment of the quadriceps mechanism, which leads to instability of the stifle joint (DeAngelis and Lau 1970; Marsolais et al. 2002), anatomical changes like proximal tibial deformities of the frontal plane (varus or valgus angulations) or an excessive tibial plateau angle (Talaat et al. 2006; Duerr et al. 2007).

Additionally, high grades of patellar luxation and degeneration of the ligament have been described as risk factors (Vasseur et al. 1985; Campbell et al. 2010). Patients with PL and CCLR are generally older (7–8 years) than those with PL only (3–5.2 years) (Campbell et al. 2010; Candela Andrade et al. 2020). Maltese dogs have been found to be a predisposed breed and being overweight has been shown to be a predisposing factor for the development of a concomitant CCLR (Candela Andrade et al. 2020).

Diagnosis and clinical presentation of patellar luxation and concomitant cranial cruciate ligament rupture

DIAGNOSING PL

Clinical signs for patellar luxation can vary between patients. They usually include stiffness of the stifle joint, permanent flexion or incapability of complete stretching (Matis 2005). Depending on the degree and duration of the luxation, PL patients may also show intermittent or consistent hind limb lameness (Roush 1993). The PL grading can be performed according to Singleton’s (1969) classification (Table 1).

Radiographic views of the stifle help to confirm permanent luxation and assess degenerative changes or skeletal abnormalities like valgus or varus deformities. Lateral projections help to assess the correct positioning of the patella in the trochlear groove. Accurate positioning is essential to assess deformities and avoid false interpretations (Marino and Loughin 2010; Kowaleski et al. 2018). Anatomic and mechanical joint angles can be assessed and calculated in preparation for surgical corrections on both radiological and computed tomography (CT) studies (Kaiser et al. 2001; Sarierler 2004; Dudley et al. 2006; Dismukes et al. 2007). However, 3D reconstruction CT scans are an essential diagnostic tool, as they enable the precise assessment of the anatomical changes in the patient.

DIAGNOSING CCLR

Cranial cruciate ligament rupture signs include refusing to sit on the affected limb (Matis 2005), avoiding flexion or extension as well as acute inflammation and hemarthrosis of the stifle joint. These symptoms result in acute lameness, which, depending on the degree of the injury, may result in intermittent or persistent and weight or non-weight bearing lameness (Sandman and Harari 2001). Other signs to be assessed include thigh muscle atrophy, asymmetry in the hind legs, joint effusion, periarticular swelling, pain during flexion or extension and cranial displacement of the tibial crest (Paatsama 1952; Johnson and Johnson 1993). A positive cranial drawer test and a positive tibial compression test are pathognomonic for CCLR (Brunnberg 1989). To confirm and eliminate the differential diagnoses, mediolateral and cranio-caudal radiographs of the stifle should be taken (Jerram and Walker 2003). Radiological findings may include effacement loss in the infrapatellar pad shadow through soft tissue opacity, caudal displacement of the fat density located caudal to the joint capsule and osteophyte formation (Kowaleski et al. 2018).

Arthroscopy has proven useful due to its diagnostic sensitivity, particularly in cases of partial ruptures of the ligament and the added benefit of combining diagnostic and treatment procedures, such as a partial meniscectomy (Pozzi et al. 2008; Ertelt and Fehr 2009; Kowaleski et al. 2018). In dogs with chronic patellar luxation and acute lameness, a concomitant CCLR should be considered as a differential diagnosis.

While non-invasive imagining techniques of the stifle such as magnetic resonance imaging (MRI) or an ultrasound can assist the diagnosis, they require special equipment, practice and technical skills, which makes their reliability operator-dependent. Therefore, arthroscopic visualisation and palpation are the most reliable diagnostic methods for the vast majority of suspected CCLR or meniscal pathology cases (Kowaleski et al. 2018).

Treatment for PL and CCLR

CONSERVATIVE THERAPY FOR PL AND CONCOMITANT CCLR

Medical management consists of the restriction of activities, weight reduction and anti-inflammatory drugs (NSAIDs) in combination or without additional analgesics (Jerram and Walker et al. 2003). Weight control and physical rehabilitation, to improve the quadriceps extensor mechanism, are additional measures included in the conservative treatment of these pathologies (Mlacnik et al. 2006; Ramirez et al. 2015). However, the vast majority of authors reject conservative treatment.

SURGICAL TREATMENT

Surgical treatment for PL

For didactic reasons, we present a brief overview of the methods used to treat PL and CCLR. The majority of these techniques can be combined with each other, but evidence of suitability or superiority only exist for a few combinations of techniques and these will be explained below.

Surgical treatment options for patellar luxation include soft tissue techniques, deepening of the trochlear groove, tibial tuberosity transposition and corrective osteotomies for cases of distal femur or proximal tibial malalignment. The combination is chosen according to the severity of the patellar luxation and the anatomical changes.

Soft tissue techniques include medial desmotomy, lateral imbrication, antirotational sutures and release of the medial musculature. Their common goal is to release tight tissues and tighten loose tissues, in order to position the patella in the trochlear groove. These techniques are generally combined with other osseous procedures, as they are generally not able to correct the patellar luxation itself (Roush 1993; Hulse 1995; Di Dona et al. 2018).

Sulcoplasty techniques are used to change the shape and deepen the trochlear groove to optimise the fitting of the patella on it (Di Dona et al. 2018). The common goal of these techniques is to embed 50% of the patella above the trochlear ridges (DeCamp et al. 2015). Trochlear wedge and block recession osteotomies are performed to deepen the trochlear groove. An osteochondral autograft, either triangular (wedge) or rectangular in cross-section, is taken from the femur. Next, the femoral defect site is deepened and finally, the autograft is put back into place (Figure 1A, B). No fixation is needed, as patellar pressure and congruence between the surfaces create sufficient stability (Boone et al. 1983; Slocum and Devine 1985; Johnson et al. 2001) (Figure 1A, B). Variations of these methods have been described in recent years. The “K-shield-shaped wedge recession” is a trochlear wedge shape, which uses half a wedge distally and half a block proximally (Katayama et al. 2016).

Figure 1. Postoperative radiological views of the stifle joint.

Figure 1

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(A and B) Mediolateral and caudocranial postoperative radiological views of the left stifle joint of a 4-year-old spayed female Pekinese (5.5 kg) with a medial patellar luxation grade III. The pathology was surgically corrected using a wedge recession osteotomy in combination with a tibial tuberosity transposition, medial desmotomy and lateral fascial and capsular imbrication

The “extended proximal trochleoplasty” is another alternative that has been proposed for the treatment of bidirectional patellar luxation in dogs (Wangdee et al. 2015).

It offers the advantage of maintaining a periosteal attachment of the wedge, which leads to a diminished periosteal formation post-surgery. Furthermore, the “ridge stop technique” (www.orthomed.co.uk/eu/category/ridgestop/), which uses a polyethylene rim on the trochlear ridge to prevent patellar luxation, can also be used.

The goal of a tibial tuberosity transposition is to correct the malalignment of the patella and its insertion through the patellar ligament in the tibial tuberosity of the tibia. The tibial crest, where the patellar ligament is attached, is cut and fixed to a more correct position, either laterally or medially, depending on the direction of the luxation, in order to relocate the patella within the trochlear groove (Singleton 1969) (Figure 1A, B). The “rapid luxation” technique (leibinger.vet/patella-luxation/patella-luxation-in-dogs-and-cats/) is a modern variation of this technique, which consists of the use of an implant (tibial tappet) to transpose and fix the tibial tuberosity into a new position for the patellar ligament realignment.

Corrective osteotomies are needed to correct bone deformities in case of malformations of the distal femur or proximal tibia, as well as to realign the quadriceps muscle group and re-establish its functionality. Techniques like a closing lateral wedge osteotomy or a medial opening osteotomy can be used to treat valgus or varus malformations. Derotational osteotomies are performed in case of torsional deformities of long bones like the proximal tibia (Petazzoni 2014; Brower et al. 2017; Kowaleski et al. 2018) (Figure 2). For all these procedures, pre-operative CT scans are recommended to calculate the grade of the deviation and plan its correction (Dudley et al. 2006).

Figure 2. X-ray of the hip and hind limbs.

Figure 2

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(A) Ventrodorsal X-ray of the hip and hind limbs of a 7-year-old intact mixed-breed dog with medial bilateral patellar luxation grade IV. (B) Ventrodorsal X-ray of the hip and hind limbs of the same patient after a bilateral trochlear wedge recession osteotomy, a bilateral medial femoral opening osteotomy to correct a valgus angulation of the distal femur and a bilateral derotational osteotomy of the proximal tibial for realignment

Outcomes after surgical correction for PL depend heavily on the patellar luxation grade. While all cases of PL grade II had an excellent outcome, reluxation after surgery occurred in 11% of PL cases with a grade III luxation. The success rates for cases with PL grade IV vary between 64–93% and have a higher risk for complications and additional surgery, such as corrective osteotomies (Wandgee et al. 2013; Dunlap et al. 2016).

Surgical treatment for CCLR

Numerous techniques have been described over the years. The surgical treatment options for CCLR can be divided into three technical categories (Jerram and Walker et al. 2003).

Intra-articular techniques

Intra-articular techniques replace the CCL through an autograft, allograft or synthetic material to substitute the torn CCL and mimic its function (Figure 3A).

Figure 3. Illustration of different techniques to treat CCLR.

Figure 3

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(A) Intra-articular method: “Modified fascia over the top” technique (Brunnberg et al. 1992). (B) Extra-articular method: “Capsular fascial imbrication” technique (Allgoewer et al. 2000). (C and D) Remodelling osteotomies. (C) Mediolateral views of a “tibial plateau levelling osteotomy” (Slocum and Slocum 1993) in an 8-year-old intact male Entlebucher mountain dog with a CCLR. (D) Mediolateral views of a “tibial tuberosity advancement 2” technique in a 10-year-old mixed-breed neutered male dog (30 kg) with a CCLR. Courtesy of Dr. Diane Meiler

CCLR = cranial cruciate ligament ruptures

Autografts can either be obtained from the patient’s patellar ligament or fascia lata and are applied during the “fascia over the top” technique and its modifications (Arnoczky et al. 1979; Brunnberg et al. 1992). If the patient is not a suitable donor, allografts of the patellar ligament or fascia lata can be taken from another dog.

However, due to the difficulties of finding a suitable donor, this option is rarely used to treat CCLR in dogs. Synthetic grafts from Dacron, silk or ligament augmentation devices can be implanted to simulate the ligaments functional properties. A recent bioengineering approach has investigated a new graft, based on a matrix scaffold cultivated with progenitor ligament cells (Kowaleski et al. 2018).

Extracapsular techniques

Essentially, extracapsular techniques rely on the post-surgical formation of periarticular fibrosis, after the initial stability provided by the use of extraarticular devices has faded (Kowaleski et al. 2018). These techniques are generally easier and quicker to perform and do not require special equipment.

Techniques include the “capsular fascial imbrication” technique (Allgoewer et al. 2000) (Figure 3B), the “lateral retinacular imbrication” technique (DeAngelis and Lau 1970) and its later modification, the “fabellotibial suture” (Flo 1975), which combines the suture material and surgical knots or metallic crimp tubes, and the “tight rope” technique, in which a high molecular-weight-polyethylene polyester is used (Cook 2008).

Tibial osteotomy techniques

Tibial osteotomy techniques are currently viewed as the superior choice for CCLR repairs, since the development of postoperative arthrosis progresses slower than in other techniques (Lazar et al. 2005). The goal of these techniques is to neutralise the cranial tibial thrust by remodelling the proximal portion of the tibia.

The “cranial tibial closing wedge osteotomy” (CTWO) was the first procedure created to eliminate the cranial tibial thrust by modifying the tibial plateau angle by removing a cranial wedge of bone from the proximal tibia (Slocum and Devine 1984). Based on the same principle, years later, the “tibial plateau levelling osteotomy” (TPLO) was created by the same author, during which the tibial plateau is cut to adjust the angle (Slocum and Slocum 1993) (Figure 3C). A TPLO can be combined with a “cranial closing wedge ostectomy” to treat an excessive tibial plateau angle, a proximal tibial varus or valgus angulation or a tibial torsion.

The “tibial tuberosity advancement” (TTA) technique was introduced by Montavon et al. (2002). The stifle joint is stabilised by neutralising the cranial tibial thrust force by advancing the tibial tuberosity, changing the angle of the patellar ligament and neutralising the tibiofemoral shear force during weight bearing.

After cutting into the tibial tuberosity, a special titanium cage is placed to advance it. Stabilisation is achieved through placement of a Kyon plate on the tibial crest and the proximal tibia (Kowaleski et al. 2018) (Figure 3D). Later modifications eliminated the use of the plate and rely solely on the cage both for the advancement and stabilisation of the advanced tibial tuberosity. Techniques include the “modified Maquet procedure” as well as the “TTA Rapid” and “TTA-2” techniques (Etchepareborde et al. 2011; Kyon Pharma 2012; Samoy et al. 2014). The main advantages of using these techniques are the reduced surgical time and reduced volume of foreign material implanted into the patient (Marques et al. 2017).

The “triple tibial osteotomy” aims to reduce the patellar tendon angle to 90 degrees when the stifle joint is at a weight-bearing angle. To achieve this, a small horizontal wedge of bone is removed halfway along a vertical osteotomy in the tibial tuberosity. After removing the bone wedge, the tibial plateau is levelled. Once this is performed, the horizontal defect created by removing the wedge is closed down, thereby advancing the tibial tuberosity (Kowaleski et al. 2018).

Both TPLO (Slocum and Slocum 1993) and TTA (Montavon et al. 2002) have been found to achieve good to very good results (Lazar et al. 2005; Au et al. 2010) and are considered superior to the extracapsular techniques for CCLR treatments (Lazar et al. 2005; Gordon-Evans et al. 2013; Berger et al. 2015; Di Dona et al. 2015). However, their superiority has been called into question (Conzemius et al. 2005). The need of special equipment and technical skills as well as the high cost limit the availability of these techniques.

Surgical treatment of PL and concomitant CCLR

Until now, treatment combinations for the combination of pathologies have been based on the surgeon’s technical preferences and skills. In the following sections, evidence-based evaluations of the techniques for treatment of PL and concomitant CCLR are described and discussed. Due to the differences in the study designs, especially regarding the follow-up time points and methods of examination, the comparison is limited. The data is shown in Table 2.

Table 2. Summary of the different features of the studies and techniques used for the treatment of patellar luxation and cranial cruciate ligament ruptures in dogs.
Author Study nature Surgical method Surgical efficiency Sample Method of follow up By who Time of follow up post-surgery Complications Breed’s size
Candela Andrade et al. (2020) Retrospective and prospective wedge R.O. + TTT + capsular fascial imbrication or fascia over the top 86.63% 30 stifles physical examination and lameness scoring (0–5) in-hospital re-evaluation and referring vet 6 months 3.33 % minor, 6.67% major, 6.67% catastrophic small and toy breed dogs
Flesher et al. (2019) retrospective modified TPLO 81.60% 76 stifles physical examination and radiological evaluation in hospital re-evaluations 6–8 weeks 7.8% minor, 10.5% major small and medium breed dogs < 15 kg
Langenbach and Marcellin-Little (2010) prospective modified TPLO 84.62% 13 stifles lameness scoring (0–5) and radiological evaluation in hospital re-evaluations and referring vet > 6 months 15.38% major large breed dogs > 30 kg dogs
Leonard et al. (2016) retrospective study TPLO-TTT 100% 13 stifles physical examination, limb function and radiological follow up in hospital re-evaluations 8–10 weeks 0% complication medium and large breed dogs
Yeadon et al. (2011) retrospective study TTTA 71.80% 39 stifles physical examination, lameness scoring (0–5) and radiological follow up treating surgeon and in hospital re-evaluation from 6 up to 20 months 10.25% minor, 17.94% major small, medium and large breed dogs (mean: 22.3 kg)
Fauron et al. (2017) retrospective ECS + TTT 53.90% 32 stifles physical examination, lameness scoring (0–5) in hospital re-evaluation from 6 weeks 31.25% minor, 15.62% major small, medium and large breed dogs (mean: 23.4 kg)
Fauron et al. (2017) retrospective TTTA 82.50% 40 stifles physical examination and lameness scoring (0–5) in hospital re-evaluation from 6 weeks 17.50% minor small, medium and large breed dogs (mean: 23.4 kg)
Leibinger (2021) TTTA rapid not available literature – – – – – – – –
NGD (2021) Offset TPLO not available literature – – – – – – – –
Livet et al. (2019) retrospective modified triple tibial osteotomy 77.80% 9 stifles physical examination, radiographic follow up and lameness scoring (0–5) evaluation in-hospital re-evaluation and owner questionnaires from 6–14 weeks for radiological controls to 48 months (owner’s questionnaires) 33.3% minor, 11.11% major toy, small and large breed dogs
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In most studies, complications that did not require additional surgical treatment were considered minor (e.g., wound infections, seromas), while any additional surgical treatment (meniscal lesions, broken plates, patellar reluxation) was considered a major complication. Complications that resulted in limb amputation or euthanasia of the patient were considered catastrophic. In the case of Livet et al. (2019) and Leonard et al. (2016), all complications that required additional medical or surgical treatment were considered major complications

ECS = extracapsular stabilisation; R.O. = recession osteotomy; TPLO = tibial plateau levelling osteotomy; TTT = tibial tuberosity transposition; TTTA = tibial tuberosity transposition advancement

Traditional combination of techniques

The combination of a “wedge recession osteotomy” (WR) (Slocum and Devine 1985) and a “tibial tuberosity transposition” (TTT) (Singleton 1969) with the intra-articular “modified fascia over the top” technique (Brunnberg et al. 1992) or the extra-capsular “capsular and fascial imbrication” technique (Allgoewer et al. 2000) are able to create sufficient stability of the knee joint in cases of patellar luxation and concomitant CCLR in small breed dogs. No significant differences were observed between the different combinations. Furthermore, they have the added advantage of not requiring special equipment or surgical skills, which makes them inexpensive and more practical compared to other techniques (Candela Andrade et al. 2020).

Remodelling osteotomies

The treatment of both pathologies together has changed over the past few decades and traditional methods have been substituted for new remodelling osteotomies (Candela Andrade et al. 2020). These techniques alter the proximal tibial anatomy to neutralise the cranial tibial thrust as well as any varus or valgus angulations.

In the “modified TPLO” (Figure 4A, B), the tibial plateau is rotated so that its slope is changed from the horizontal plane, thereby neutralising the cranial tibial thrust and simultaneously levelling the tibial plateau.

Figure 4. Mediolateral and caudocranial radiographs after a modified TPLO.

Figure 4

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(A and B) Mediolateral and caudocranial radiographs after a modified TPLO and a trochlear block recession in a 10-year-old neutered male mixed breed dog (6 kg) with medial patellar luxation grade III and concomitant cranial cruciate ligament rupture. Courtesy of Dr. Karol Bayer. (C and D) Mediolateral and caudocranial radiographs of a “tibial tuberosity transposition advancement” for treatment of a medial PL and concomitant CCLR in a 10-year-old neutered male Jack Russel Terrier (12 kg). Courtesy of Dr. Diane Meiler

CCLR = cranial cruciate ligament ruptures; TPLO = tibial plateau levelling osteotomy

In addition, this procedure realigns the quadriceps mechanism through medial translation or rotation of the proximal tibial segment (Kowaleski et al. 2018; Flesher et al. 2019).

For application of the modified TPLO osteotomy, a straight TPLO plate is contoured to allow proximal tibial segment medialisation (Flesher et al. 2019). Special plates such as the “offset TPLO plate” (www.ngdvet.com) have been developed to achieve a mediolateral translation of the tibial plateau segment during TPLO.

In 2016, the combination of TPLO with a tibial tuberosity transposition (TTT) was first described (Leonard et al. 2016). The combination consists of a TPLO to neutralise the CCLR and a TTT to realign the quadriceps muscle group to treat the patellar luxation.

The “tibial tuberosity transposition advancement” (TTTA) (Figure 4C, D) is another treatment possibility. It combines a tibial tuberosity advancement (TTA), used to neutralise the cranial tibial thrust, and a tibial tuberosity transposition to treat the patellar luxation. The TTT is performed by bending a fork or plate into place to achieve a corrective transposition (Kowaleski et al. 2018). Other studies have demonstrated the superiority of this technique against the combination of “extracapsular stabilisation” (ECS) and a “tibial tuberosity transposition”, which had 2.7 times more complications (Fauron et al. 2017).

The “TTA Rapid” technique is a more recent variation of the TTTA. Cages have been designed as alternatives to plates, to not only advance, but also transpose the tibial tuberosity into a more lateral or medial position, depending on the direction of the patellar luxation (Figure 5).

Figure 5. Radiographs after a TTA-rapid surgery.

Figure 5

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Mediolateral (A) and caudocranial radiographs (B) after a TTA-rapid surgery in a 5-year-old neutered male Boxer (28 kg) with a CCLR. Courtesy of Dr. Diane Meiler

CCLR = cranial cruciate ligament ruptures; TTA = tibial tuberosity advancement

The most recently published technique is a “modified triple tibial osteotomy” (Livet et al. 2019). This includes the combination of a mediolateral closing wedge osteotomy, a rotation of the distal tibial fragment to correct tibial abnormal deviations, and a tibial tuberosity transposition for the PL. Finally, the fragments are stabilised with a TPLO plate and Kirschner wires.

Conclusions

Patellar luxation and concomitant cranial cruciate ligament rupture are common orthopaedic problems in small animal practice. Between 22–41% of small breed dogs and 13% of large breed dogs with patellar luxation develop a concomitant cranial cruciate ligament rupture. The pathogenesis appears to be multifactorial, including anatomical changes of the distal femur and proximal tibial segments, excessive tibial plateau angle, being overweight, older age, breed predispositions, degeneration of the ligament and severity of the patellar luxation.

The superiority of remodelling osteotomies against traditional methods for the treatment of patellar luxation and concomitant cranial cruciate ligament rupture is still under debate, at least in small breed dogs. However, the need for special equipment, special skills and substantial costs limit its use. Since the inclusion criteria, follow-up time and clinical assessment of patients after surgery varied considerably in the studies that evaluated the outcomes of the different treatment techniques, the superiority of any technique over another one remains controversial. Comparability to previous research should be a consideration in planning future studies, to improve the understanding of the multitude of surgical techniques and aid surgeons in choosing the appropriate surgical approach for their patient.

Conflict of interest

The authors declare no conflict of interest.

REFERENCES

  1. Alam MR, Lee JI, Kang HS, Kim IS, Park SY, Lee KC, Kim NS. Frequency and distribution of patellar luxation in dogs. 134 cases (2000 to 2005). Vet Comp Orthop Traumatol. 2007;20(1):59-64. [PubMed] [Google Scholar]
  2. Allgoewer I, Richter A, Gruenig G, Meutstege F, Waibl H, Brunnberg L. Zwei intraextraartikulare Stabilisationsmethoden zur Therapie der Ruptur des Ligamentum cruciatum craniale im Vergleich: Methode (mod.) nach FLO und Methode nach MEUTSTEGE [Two intra-and extra-articular stabilization methods for the treatment of cranial cruciate ligament rupture in comparison to the FLO (mod.) and MEUSTEGE methods]. Kleintierprax. 2000;45:95-103. German. [Google Scholar]
  3. Arnoczky SP, Tarvin GB, Marshall JL. The over-the-top procedure: A technique for anterior cruciate ligament substitution in the dog. J Am Anim Hosp Assoc. 1979;15:283-90. [Google Scholar]
  4. Arnoczky SP, Torzilli PA, Marschall JL. Biomechanical evaluation of anterior cruciate ligament repair in the dog: An analysis of the instant centre of motion. J Am Anim Hosp Assoc. 1977 Jan 1;13(5):553-8. [Google Scholar]
  5. Arthurs GI, Langley-Hobbs SJ. Complications associated with corrective surgery for patellar luxation in 109 dogs. Vet Surg. 2006 Aug;35(6):559-66. [DOI] [PubMed] [Google Scholar]
  6. Au KK, Gordon-Evans WJ, Dunning D, O’Dell-Anderson K, Knap K, Griffon D, Johnson A. Comparison of short- and long-term function and radiographic osteoarthritis in dogs after postoperative physical rehabilitation and tibial plateau leveling osteotomy or lateral fabellar suture stabilization. Vet Surg. 2010 Feb;39(2):173-80. [DOI] [PubMed] [Google Scholar]
  7. Berger B, Knebel J, Steigmeier-Raith S, Reese S, Meyer-Lindenberg A. Long-term outcome after surgical treatment of cranial cruciate ligament rupture in small breed dogs. Comparison of tibial plateau leveling osteotomy and extra-articular stifle stabilization. Tierarztl Prax Ausg K Kleintiere Heimtiere. 2015;43(6):373-80. English, German. [DOI] [PubMed] [Google Scholar]
  8. Boone EG, Hohn RB, Weisbrode SE. Trochlear recession wedge technique for patellar luxation: An experimental study. J Am Anim Hosp Assoc. 1983 Sep-Oct;19:735-42. [Google Scholar]
  9. Bosio F, Bufalari A, Peirone B, Petazzoni M, Vezzoni A. Prevalence, treatment and outcome of patellar luxation in dogs in Italy. A retrospective multicentric study (2009–2014). Vet Comp Orthop Traumatol. 2017 Sep 12;30(5):364-70. [DOI] [PubMed] [Google Scholar]
  10. Bound N, Zakai D, Butterworth SJ, Pead M. The prevalence of canine patellar luxation in three centres. Clinical features and radiographic evidence of limb deviation. Vet Comp Orthop Traumatol. 2009;22(1):32-7. [PubMed] [Google Scholar]
  11. Brower BE, Kowaleski MP, Peruski AM, Pozzi A, Dyce J, Johnson KA, Boudrieau JR. Distal femoral lateral closing wedge osteotomy as a component of comprehensive treatment of medial patellar luxation and distal femoral varus in dogs. Vet Comp Orthop Traumatol. 2017 Jan 16;30(1):20-7. [DOI] [PubMed] [Google Scholar]
  12. Brunnberg L. Klinische Untersuchung zur Atiologie und Pathogenese der Ruptur des Ligamemtum cruciatum craniale beim Hund. 1. Mittleilung: Zur Atiologie und Diagnose der Ruptur des Ligamentums cruciatum craniale beim Hund [Clinical examination, etiology and pathogenesis of the cranial cruciate ligament rupture in dogs. 1st part: Etiology and diagnostic of the cranial cruciate ligament rupture in dogs]. Kleintierprax. 1989;34(3):111-4. German. [Google Scholar]
  13. Brunnberg L, Rieger I, Hesse EM. Sieben Jahre Erfahrung mit einer modifizierten „Over-the-Top“ – Kreuzbandplastik beim Hund [7 years of experience with a modified „Over the top“ – Cruciate ligament replacement in dogs]. Kleintierprax. 1992;37:735-46. German. [Google Scholar]
  14. Campbell CA, Horstman CL, Mason DR, Evans RB. Severity of patellar luxation and frequency of concomitant cranial cruciate ligament rupture in dogs: 162 cases (2004–2007). J Am Vet Med Assoc. 2010 Apr 15;236(8):887-91. [DOI] [PubMed] [Google Scholar]
  15. Candela Andrade M, Slunsky P, Klass LG, Brunnberg L. Risk factors and long-term surgical outcome of patellar luxation and concomitant cranial cruciate ligament rupture in small breed dogs. Vet Med-Czech. 2020;65(4):159-67. [Google Scholar]
  16. Conzemius MG, Evans RB, Besancon MF, Gordon WJ, Horstman CL, Hoefle WD, Nieves M, Wagner SD. Effect of surgical technique on limb function after surgery for rupture of the cranial cruciate ligament in dogs. J Am Vet Med Assoc. 2005 Jan 15;226(2):232-6. [DOI] [PubMed] [Google Scholar]
  17. Cook JL. Multicenter outcomes study for evaluation of tightrope CCL for treatment of cranial cruciate deficiency in dogs: The first 1 000 cases. Proceedings of the 37th Annual Conference of the Veterinary Orthopedic Society; Breckenridge, CO, Feb 20-27; 2008. [Google Scholar]
  18. DeAngelis M, Lau RE. A lateral retinacular imbrication technique for the surgical correction of anterior cruciate ligament rupture in the dog. J Am Vet Med Assoc. 1970 Jul 1;157(1):79-84. [PubMed] [Google Scholar]
  19. DeCamp CE, Johnson SA, Dejardin LM, Schaefer SL. The stifle joint. In: DeCamp CE, editor. Brinker, Piermattei and Flo’s handbook of small animal orthopedics and fracture repair. et al. th ed. St. Louis, MO, USA: Elsevier; 2015. p. 597-669. [Google Scholar]
  20. Di Dona F, Della Valle G, Balestriere C, Lamagna B, Meomartino L, Napoleone G, Lamagna F, Fatone G. Lateral patellar luxation in nine small breed dogs. Open Vet J. 2016;6(3):255-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Di Dona F, Della Valle G, Lamagna F, Balestriere C, Del Priete C, Fatone G. Force plate analysis for comparison of lateral fabellar suture and maquet modified procedure tibial tuberosity advancement techniques for treatment of dogs with cranial cruciate ligament disease. Joint meeting, LXIX Convegno SISVet, XV Convegno SICV, XIII Convegno SIRA, XII Convegno AIPVet, XI Convegno SoFiVet, II Convegno RNIV; 2015 Jun 15-17; Perugia, Italy; 2015. [Google Scholar]
  22. Di Dona F, Della Valle G, Fatone G. Patellar luxation in dogs. Vet Med (Auckl). 2018 May 31;9:23-32. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Dismukes DI, Tomlinson JL, Fox DB, Cook JL, Song KJ. Radiographic measurement of the proximal and distal mechanical joint angles in the canine tibia. Vet Surg. 2007 Oct;36(7):699-704. [DOI] [PubMed] [Google Scholar]
  24. Dudley RM, Kowaleski MP, Drost WT, Dyce J. Radiographic and computed tomographic determination of femoral varus and torsion in the dog. Vet Radiol Ultrasound. 2006 Oct-Nov;47(6):546-52. [DOI] [PubMed] [Google Scholar]
  25. Duerr FM, Duncan CG, Savicky RS, Park RD, Egger EL, Palmer RH. Risk factors for excessive tibial plateau angle in large-breed dogs with cranial cruciate ligament disease. J Am Vet Med Assoc. 2007 Dec 1;231(11):1688-91. [DOI] [PubMed] [Google Scholar]
  26. Dunlap AE, Kim SE, Lewis DD, Christopher SA, Pozzi A. Outcomes and complications following surgical correction of grade IV medial patellar luxation in dogs: 24 cases (2008–2014). J Am Vet Med Assoc. 2016 Jul;249(2):208-13. [DOI] [PubMed] [Google Scholar]
  27. Ertelt J, Fehr M. Cranial cruciate ligament repair in dogs with and without meniscal lesions treated by different minimally invasive methods. Vet Comp Orthop Traumatol. 2009;22(1):21-6. [DOI] [PubMed] [Google Scholar]
  28. Etchepareborde S, Brunel L, Bollen G, Balligand M. Preliminary experience of a modified Maquet technique for repair of cranial cruciate ligament rupture in dogs. Vet Comp Orthop Traumatol. 2011;24(3):223-7. [DOI] [PubMed] [Google Scholar]
  29. Fauron AH, Bruce M, James DR, Owen MA, Perry KL. Surgical stabilization of concomitant canine medial patellar luxation and cranial cruciate ligament disease. Effect of fixation method on postoperative complication rate and clinical outcome. Vet Comp Orthop Traumatol. 2017 May 22;30(3):209-18. [DOI] [PubMed] [Google Scholar]
  30. Flesher K, Beale BS, Hudson CC. Technique and outcome of a modified tibial plateau levelling osteotomy for treatment of concurrent medial patellar luxation and cranial cruciate ligament rupture in 76 stifles. Vet Comp Orthop Traumatol. 2019 Jan;32(1):26-32. [DOI] [PubMed] [Google Scholar]
  31. Flo GL. Modification of the lateral retinaculum imbrication technique for stabilizing cruciate ligament injuries. J Am Anim Hosp Assoc. 1975;11:570-3. [Google Scholar]
  32. Gibbons SE, Macias C, Tonzing MA, Pinchbeck GL, McKee WM. Patellar luxation in 70 large breed dogs. J Small Anim Pract. 2006 Jan;47(1):3-9. [DOI] [PubMed] [Google Scholar]
  33. Gordon-Evans WJ, Griffon DJ, Bubb C, Knap KM, Sullivan M, Evans RB. Comparison of lateral fabellar suture and tibial plateau leveling osteotomy techniques for treatment of dogs with cranial cruciate ligament disease. J Am Vet Med Assoc. 2013 Sep 1;243(5):675-80. Erratum in: J Am Vet Med Assoc. 2013 Nov 1;243(9): 1297. [DOI] [PubMed] [Google Scholar]
  34. Harasen G. Patellar luxation: Pathogenesis and surgical correction. Can Vet J. 2006 Oct;47(10):1037-9. [PMC free article] [PubMed] [Google Scholar]
  35. Hayes AG, Boudrieau RJ, Hungerford LL. Frequency and distribution of medial and lateral patellar luxation in dogs: 124 cases (1982–1992). J Am Vet Med Assoc. 1994 Sep 1;205(5):716-20. [PubMed] [Google Scholar]
  36. Hulse DA. The stifle joint. In: Olmstead ML, editor. Small animal orthopedics. St. Louis, MO, USA: Mosby; 1995. p. 395-404. [Google Scholar]
  37. Jerram RM, Walker AM. Cranial cruciate ligament injury in the dog: Pathophysiology, diagnosis and treatment. N Z Vet J. 2003 Aug;51(4):149-58. [DOI] [PubMed] [Google Scholar]
  38. Johnson AL, Probst CW, Decamp CE, Rosenstein DS, Hauptman JG, Weaver BT, Kern TL. Comparison of trochlear block recession and trochlear wedge recession for canine patellar luxation using a cadaver model. Vet Surg. 2001 Mar-Apr;30(2):140-50. [DOI] [PubMed] [Google Scholar]
  39. Johnson JM, Johnson AL. Cranial cruciate ligament rupture. Pathogenesis, diagnosis, and postoperative rehabilitation. Vet Clin North Am Small Anim Pract. 1993;23(4):717-33. [DOI] [PubMed] [Google Scholar]
  40. Kaiser S, Cornely D, Golder W, Garner MT, Wolf KJ, Waibl H, Brunnberg L. The correlation of canine patellar luxation and the anteversion angle as measured using magnetic resonance images. Vet Radiol Ultrasound. 2001 Mar-Apr;42(2):113-8. [DOI] [PubMed] [Google Scholar]
  41. Katayama M, Ogaya H, Shunsuke S, Uzuka Y. Kite shield-shaped wedge recession for treatment of medial patellar luxation in seven small-breed dogs. Vet Surg. 2016 Jan; 45(1):66-70. [DOI] [PubMed] [Google Scholar]
  42. Kowaleski MP, Boudrieau RJ, Pozzi A. Stifle joint. In: Tobias KM, Johnston SA, editors. Veterinary surgery: Small animal. Volume II. et al. nd ed. St. Louis, MO: Elsevier; 2018. p. 1071-168. [Google Scholar]
  43. Kyon Pharma. TTA – Tibial tuberosity advancement [Internet]. 2012. [cited 2021 Aug 10]. Available from https://www.kyon.ch/current-products/tibial-tuberosity-advancement-tta.
  44. L’Eplattenier HF, Montavon P. Patellar luxation in dogs and cats: Management and prevention. Comp Cont Edu Pract Vet. 2002;24(4):292-300. [Google Scholar]
  45. LaFond E, Breur GJ, Austin CC. Breed susceptibility for developmental orthopedic diseases in dogs. J Am Anim Hosp Assoc. 2002 Sep-Oct;38(5):467-77. [DOI] [PubMed] [Google Scholar]
  46. Langenbach A, Marcellin-Little DJ. Management of concurrent patellar luxation and cranial cruciate ligament rupture using modified tibial plateau levelling. J Small Anim Pract. 2010 Feb;51(2):97-103. [DOI] [PubMed] [Google Scholar]
  47. Lazar TP, Berry CR, deHaan JJ, Peck JN, Correa M. Long-term radiographic comparison of tibial plateau leveling osteotomy versus extracapsular stabilization for cranial cruciate ligament rupture in the dog. Vet Surg. 2005 Mar-Apr;34(2):133-41. [DOI] [PubMed] [Google Scholar]
  48. Leibinger R. Patella luxation and TTA (TTTA) [Internet]. 2021. [cited 2021 Aug 8]. Available from: https://leibinger.vet/tta-rapid/patella-luxation-and-tta-ttta/.
  49. Leonard KC, Kowaleski MP, Saunders WB, McCarthy RJ, Boudrieau RJ. Combined tibial plateau levelling osteotomy and tibial tuberosity transposition for treatment of cranial cruciate ligament insufficiency with concomitant medial patellar luxation. Vet Comp Orthop Traumatol. 2016 Nov 23;29(6):536-40. [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Livet V, Taroni M, Ferrand FX, Carozzo C, Viguier E, Cachon T. Modified triple tibial osteotomy for combined cranial cruciate ligament rupture, tibial deformities, or patellar luxation. J Am Anim Hosp Assoc. 2019 Nov-Dec;55(6):291-300. [DOI] [PubMed] [Google Scholar]
  51. Marino DJ, Loughin CA. Diagnostic imaging of the canine stifle: A review. Vet Surg. 2010 Apr;39(3):284-95. [DOI] [PubMed] [Google Scholar]
  52. Marques DRC, Ibanez JF, Monteiro JF, Hespanha ACV, Eggert M, Becker A, Freitas IB. A report of the Maquet procedure for the management of cranial cruciate ligament rupture in a dog – A case report. Semin Cienc Agrar. 2017;38(3):321-30. [Google Scholar]
  53. Marsolais GS, Dvorak G, Conzemius MG. Effects of postoperative rehabilitation on limb function after cranial cruciate ligament repair in dogs. J Am Vet Med Assoc. 2002 May 1;220(9):1325-30. [DOI] [PubMed] [Google Scholar]
  54. Matis U. Die klinische Untersuchung des Kniegelenks [Clinical examination of the stifle joint]. Tierärzt Prax. 2005; 33(2):131-7. German. [Google Scholar]
  55. Mlacnik E, Bockstahler BA, Muller M, Tetrick MA, Nap RC, Zentek J. Effects of caloric restriction and a moderate or intense physiotherapy program for treatment of lameness in overweight dogs with osteoarthritis. J Am Vet Med Assoc. 2006 Dec 1;229(11):1756-60. [DOI] [PubMed] [Google Scholar]
  56. Montavon P, Damur D, Tepic S. Advancement of the tibial tuberosity for the treatment of cranial cruciate deficit of the canine stifle. Proceedings 1st World Orthopeadic Veterinary Congress, Munich, Germany; 2002. 152 p. [Google Scholar]
  57. NGD – New Generation Devices. Offset evolution TPLO plate™ [Internet]. c2021. [cited 2021 Aug 4]. Available from https://ngdvet.com/product_details.php?cid=117.
  58. O’Neill DG, Meeson RL, Sheridan A, Church DB, Brodbelt DC. The epidemiology of patellar luxation in dogs attending primary-care veterinary practices in England. Canine Genet Epidemiol. 2016 Jun 8;3:4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Paatsama S. Ligament injuries in the canine stifle joint: A clinical and experimental study [dissertation]. [Helsinki, Finland]: Helsinki University; 1952. [Google Scholar]
  60. Petazzoni M. Corrective osteotomies in treating patellar luxation in large breed dogs. Proceedings of the European College of Veterinary Surgeons Annual Scientific Meeting; 2014 Jul 3–5; Copenhagen, Denmark; 2014. p. 175-6. [Google Scholar]
  61. Piermattei DL, Flo GL. The stifle joint. In: Piermattei DL, Flo GL, editors. Handbook of small animal orthopaedics and fracture repair. et al. rd ed. Philadelphia, PA, USA: WB Saunders Co; 1997. p. 516-34. [Google Scholar]
  62. Pozzi A, Hildreth BE 3rd, Rajala-Schultz PJ. Comparison of arthroscopy and arthrotomy for diagnosis of medial meniscal pathology: An ex vivo study. Vet Surg. 2008 Dec;37(8):749-55. [DOI] [PubMed] [Google Scholar]
  63. Priester WA. Sex, size, and breed as risk factors in canine patellar luxation. J Am Vet Med Assoc. 1972;4(1):633-6. [PubMed] [Google Scholar]
  64. Ramirez JM, Lefebvre M, Bohme B, Laurent C, Balligand M. Preactivation of the quadriceps muscle could limit cranial tibial translation in a cranial cruciate ligament deficient canine stifle. Res Vet Sci. 2015 Feb;98:115-20. [DOI] [PubMed] [Google Scholar]
  65. Robins GM. The canine stifle joint. In: Whittick WG, editor. Canine orthopedics. Philadelphia, PA, USA: Lea and Febiger; 1990. p. 693-702. [Google Scholar]
  66. Roush JK. Canine patellar luxation. Vet Clin North Am Small Anim Pract. 1993;23(4):855-68. [DOI] [PubMed] [Google Scholar]
  67. Samoy Y, Verhoeven G, Bosmans T, Van der Vekens E, de Bakker E, Verleyen P, Van Ryssen B. TTA Rapid: Description of the technique and short term clinical trial results of the first 50 cases. Vet Surg. 2014 May;44(4):474-84. [DOI] [PubMed] [Google Scholar]
  68. Sandman KM, Harari J. Canine cranial cruciate ligament repair techniques: Is one best? Vet Med. 2001;96(11):850-8. [Google Scholar]
  69. Sarierler M. Comparison of femoral inclination angle measurements in dysplastic and nondysplastic dogs of different breeds. Acta Vet Hung. 2004;52(2):245-52. [DOI] [PubMed] [Google Scholar]
  70. Singleton WB. The surgical correction of stifle deformities in the dog. J Small Anim Pract. 1969 Feb;10(2):59-69. [DOI] [PubMed] [Google Scholar]
  71. Slocum B, Devine T. Cranial tibial wedge osteotomy: A technique for eliminating cranial tibial thrust in cranial cruciate ligament repair. J Am Vet Med Assoc. 1984 Mar 1;184(5):564-9. [PubMed] [Google Scholar]
  72. Slocum B, Devine T. Trochlear recession for correction of luxating patella in the dog. J Am Vet Med Assoc. 1985 Feb 15;186(4):365-9. [PubMed] [Google Scholar]
  73. Slocum B, Slocum TD. Tibial plateau leveling osteotomy for repair of cranial cruciate ligament rupture in the canine. Vet Clin North Am Small Anim Pract. 1993 Jul;23(4):777-95. [DOI] [PubMed] [Google Scholar]
  74. Talaat MB, Kowaleski MP, Boudrieau RJ. Combination tibial plateau leveling osteotomy and cranial closing wedge osteotomy of the tibia for the treatment of cranial cruciate ligament-deficient stifles with excessive tibial plateau angle. Vet Surg. 2006 Dec;35(8):729-39. [DOI] [PubMed] [Google Scholar]
  75. Vasseur PB, Pool RR, Arnoczky SP, Lau RE. Correlative biomechanical and histologic study of the cranial cruciate ligament in dogs. Am J Vet Res. 1985 Sep;46(9):1842-54. [PubMed] [Google Scholar]
  76. Wangdee C, Hazewinkel HA, Temwichitr J, Theyse LF. Extended proximal trochleoplasty for the correction of bidirectional patellar luxation in seven Pomeranian dogs. J Small Anim Pract. 2015 Feb;56(2):130-3. [DOI] [PubMed] [Google Scholar]
  77. Wangdee C, Theyse LF, Techakumphu M, Soontornvipart K, Hazewinkel HA. Evaluation of surgical treatment of medial patellar luxation in Pomeranian dogs. Vet Comp Orthop Traumatol. 2013;26(6):435-9. [DOI] [PubMed] [Google Scholar]
  78. Yasukawa S, Edamura K, Tanegashima K, Seki M, Teshima K, Asano K, Nakayama T, Hayashi K. Evaluation of bone deformities of the femur, tibia, and patella in Toy Poodles with medial patellar luxation using computed tomography. Vet Comp Orthop Traumatol. 2016;29(1):29-38. [DOI] [PubMed] [Google Scholar]
  79. Yeadon R, Fitzpatrick N, Kowaleski MP. Tibial tuberosity transposition-advancement for treatment of medial patellar luxation and concomitant cranial cruciate ligament disease in the dog. Surgical technique, radiographic and clinical outcomes. Vet Comp Orthop Traumatol. 2011;24(1):18-26. [DOI] [PubMed] [Google Scholar]

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