Use of a Custom-Made Patellar Groove Replacement in an American Staffordshire Terrier Puppy with a Severe Bone Defect in the Femoral Trochlea Caused by Hematogenous Osteomyelitis.

An 8-month-old male American Staffordshire terrier was referred for a no-weightbearing lameness of the right pelvic limb, hyperthermia, lethargy and inappetence. Two months before, endocarditis was diagnosed and treated in another veterinary hospital. Orthopedic, radiographic and tomographic examinations revealed a bone sequestrum of 4 × 1.4 cm and active periosteal reaction of the caudo-lateral cortical in the metaphysis and the distal third of the right femoral diaphysis, medullary osteolysis and interruption of the cranio-medial cortical profile, with involvement of the femoral trochlea leading to a secondary medial patella luxation. Hematogenous osteomyelitis was the suspected diagnosis. Once skeletally mature, after 4 months from surgical debridement and aggressive antibiotic therapy against Klebsiella oxytoca revealed by a bacteriological exam, the patient underwent prosthetic surgery for the application of a custom-made patellar groove replacement (PGR) to fill the bone defect and restore the femoral trochlea surface. Despite the serious injury that afflicted the right pelvic limb, the surgery had satisfactory outcomes until the last 18-month postoperative follow up.

Patient-Specific 3D-Printed Osteotomy Guides and Titanium Plates for Distal Femoral Deformities in Dogs with Lateral Patellar Luxation.

The aim of this study was to describe the diagnosis and treatment of grade IV lateral patellar luxation (LPL) in two adult large breed dogs with complex femoral deformities using patient-specific three-dimensionally (3D) printed osteotomy guides and implants. Computed tomography (CT) scans were obtained for virtual surgical planning (VSP) using computer-aided design (CAD) software, which allowed for 3D reconstruction and manipulation of the femoral deformities, providing a preoperative view of the correction. Of the two patients, one was affected bilaterally and the other unilaterally, but both dogs were from the same litter. Therefore, the healthy femur of the unilaterally affected patient was used as the physiological reference for the virtual surgical correction. Three distal femoral trapezoid osteotomies (DF-TO) followed by reduction and internal fixation with plates were performed using patient-specific 3D-printed osteotomy guides and implants. This type of osteotomy permitted correction of procurvatum in all the femurs to increase knee extension, raise the dog's lumbar spine and correct the kyphosis. Preoperative, expected and postoperative femoral angles were compared to evaluate the efficacy of virtual surgical planning and the outcome of surgical correction. Radiographic follow-up, passive range of motion and functional recovery were recorded. There were no major complications requiring revision surgery. Significant clinical improvement was observed in both patients. This study suggests that the treatment used represents a viable surgical alternative to restore limb alignment in patients with complex femoral deformities.

Bidirectional Patellar Luxation in Small- or Miniature-Breed Dogs in Japan; Patient Characteristics and Radiographic Measures Compared with Medial Patellar Luxation.

Bidirectional patellar luxation (BPL) is a relatively rare form of patellar luxation, with limited information reported regarding breed predisposition and etiology. The purpose of this study was to describe the patient characteristics and radiographic measures of proximodistal patellar position associated with BPL in dogs in Japan, compared with dogs with medial patellar luxation (MPL). A retrospective medical record search of surgically corrected MPL and BPL dogs was performed, and breed, age, sex, body weight, and presence of the patella alta in the extended-stifle position were recorded. The ratio of the patellar ligament length to patella length (PLL/PL) and the ratio of the distance between the proximal pole of the patella and the femoral condyle to patella length (A/PL) were measured on stifle radiographs. A total of 35 dogs with BPL and 95 dogs with MPL were included. The BPL was most commonly present in Toy Poodles (odds ratio compared to MPL dogs: 7.05) in the present study. There were no significant differences in age, sex, or body weight between the BPL and MPL groups. Patella alta in the extended-stifle position was more common in the BPL group (23.4%) than in the MPL group (0.8%). However, there were no significant differences in PLL/PL or A/PL between the BPL and MPL groups. The study highlights BPL in different dog breeds in Japan, and suggests that the occurrence of BPL may be related to stifle extension. However, more research is needed to fully understand the etiology of BPL.

The epidemiology of patellar luxation in an insured Swedish dog population.

Patellar luxation (PL) is a common orthopaedic condition in dogs. This study aimed to evaluate the incidence and cause-specific mortality rate, age at diagnosis, and risk factors for medial PL (MPL), lateral PL (LPL), and bidirectional PL (BPL). Other diagnoses in dogs with PL were also explored. The study population included just over 600,000 dogs insured by Agria Pet Insurance in Sweden (2011-2016). There were 2726 dogs with PL. Medial patellar luxation affected 90 % of the dogs with PL, followed by LPL (5.9 %), BPL (2.4 %), and unspecified PL (1.6 %). The median age at first diagnosis during the study period was 2.8 years for MPL, 2.7 years for LPL, and 1.5 years for BPL. In total, 168 (6.2 %) of the dogs with PL had cruciate ligament rupture. There were substantial breed-specific differences in the risk of PL: almost all breeds at increased risk of MPL were small-sized, while several of the breeds at increased risk of LPL were large-sized. The breeds at high risk of BPL varied in size. Females had an increased risk of MPL (RR 1.2, 95 % CI: 1.1-1.3, p < 0.001) and a decreased risk of LPL (RR 0.72, 95 % CI: 0.51-1.0, p = 0.042) compared to males. In total, 116 dogs were euthanised due to PL and the breeds with the highest risk of PL-related euthanasia were the Pyrenean mountain dog, Dogue de Bordeaux, and German pinscher. The median age for PL-related euthanasia was 2.2 years.

The Single Intra-Articular Injection of Platelet-Rich Plasma vs. Non-Steroidal Anti-Inflammatory Drugs as Treatment Options for Canine Cruciate Ligament Rupture and Patellar Luxation.

Cranial cruciate ligament rupture (CCLR) and patellar luxation (PL) are common pathologies affecting canines. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used as a non-surgical treatment plan in these cases. Clinical usage of platelet-rich plasma (PRP) is an emerging area of interest in veterinary medicine. There is a lack of studies comparing those two different treatment methods in veterinary medicine. The main purpose of this study was to evaluate and compare the use of oral NSAIDs and single intra-articular injection of PRP on treatment outcomes in cases of canine CCLR and PL. Dogs diagnosed with CCRL (n = 12) and PL (n = 10) were subgrouped by the severity of pathologies and administered treatment: half of the CCRL and PL groups were orally administered NSAIDs and supplements for 14 days, and the other half received a single intra-articular PRP injection into affected stifle joint. We measured serum TNF-α levels and clinical outcomes (lameness scores, painfulness to manipulations, goniometry of stifle joint in flexion and extension, and muscle strength) before treatment, at day 14 and day 28 of treatment. The results of TNF-α concentration indicates a significant difference between groups of differently treated partial CCLR groups on d14 (p = 0.006). Results of group CCLR-P1 on d14 were decreased, while results of group CCLR-P2 on d14 were increased. When comparing TNF-α concentration between all CCLR cases treated with NSAIDs and treated with PRP, there was a significant difference between those groups on d14 (p = 0.001). The results of TNF-α concentration indicates a significant difference between groups of differently treated PL-III on d28 (p = 0.036). Results of group PL-III1 indicate growth of TNF-α concentration, while at the same d28, results of group PL-III2 indicate decreased levels of cytokine, comparing results between the subgroups at the same time point and within subgroups from baseline. Results indicate a significant difference in muscle strength between group CCLR-P1 and group CCLR-P2 on d28 (p = 0.007), indicating an increment in muscle strength in group CCLR-P1 up to d14 and its reduction up to d28, and muscle strength of group CCLR-P2 increasing up to d28. When comparing the muscle strength between all CCLR cases treated with NSAIDs and treated with PRP, there was a significant difference between those groups on d28 (p = 0.007). In conclusion, a single intra-articular injection of PRP has a superior effect on management of inflammatory processes, has better clinical outcomes, and longer duration of action than oral NSAIDs, in the treatment of canine CCRL or PL.

Comparison of patellofemoral contact pressure after semi-cylindrical recession trochleoplasty and trochlear block recession in feline cadavers.

Introduction: The purpose of this study was to compare the changes in the patellofemoral joint (PFJ) contact mechanisms of the normal state, trochlear hypoplasia model and after performing trochleoplasty on the hypoplasia model in feline cadavers. Methods: Twenty normal pelvic limbs were acquired from the 10 feline cadavers. First, the PFJ contact mechanisms were measured in normal state, then trochlear hypoplasia models were created using customized trochlear ridge cutting guides. After measuring PFJ contact mechanisms in the trochlear hypoplasia models, they were divided into two groups and performed semi-cylindrical recession trochleoplasty (SCRT) and trochlear block recession (TBR) were performed, respectively. After that, the PFJ contact mechanisms were measured and the values of the 4 groups (normal state, trochlear hypoplasia, SCRT, TBR) were compared. Results: The trochlear hypoplasia group showed increased contact pressure and decreased contact areas compared to the normal state group. In the groups that underwent tracheoplasty (SCRT and TBR), PFJ contact mechanisms were recovered similarly to that of the normal state group. The PFJ of the SCRP group was measured similar to that of the normal group than that of the TBR group. Discussion: Tracheoplasty can be useful in restoring PFJ contact mechanisms and SCRT can be considered as a good alternative to the conventional methods of trochleoplasty.

Short-term outcomes for surgical correction of feline medial patellar luxations via semi-cylindrical recession trochleoplasty.

Case series summary: Three cats (five stifles) were diagnosed with varying degrees of pelvic limb lameness secondary to medial patellar luxations (MPLs). Lameness did not resolve with medical management in any cat before referral for orthopedic evaluation. All cats underwent semi-cylindrical recession trochleoplasty (SCRT), medial fascial release and lateral imbrication for surgical repair of MPLs. All cats were re-evaluated at 3 and 8 weeks postoperatively and two cats were also evaluated at 16 weeks postoperatively. At the final rechecks, all cats had resolution of lameness of the operated limb(s) and no evidence of recurrence of patellar luxation. Relevance and novel information: This case series demonstrated SCRT with soft tissue reconstruction as an acceptable option for surgical correction in three cats with MPLs. Short-term outcomes revealed minor complications and all patellae remained centralized.

Stifle Joint Arthrodesis for Treating Chronic-Osteoarthritis-Affected Dogs.

A two-year-old male Pomeranian dog was presented to a veterinary hospital due to the side effects of a surgical correction for patellar luxation. Stifle joint arthrodesis (SJA) was performed on the patient's right leg using autologous bone-grafting techniques. The right femur and tibial joint were angled 120-130°, and an SJA plate was fixed on the front of the two bones. After performing joint fusion of the right limb, medial-patellar-luxation-(MPL)-corrective surgery was performed to cut the tibial tuberosity on the left leg, and the fixing force was increased using the figure-of-eight-tension-band-wiring technique. Results were recorded regarding the dog's ability to walk and trot in the right hind limb; these results were evaluated for 27 days after surgery. It was difficult for the patient to walk because weight-bearing had not been carried out for 3 days after the surgery; short strides and partial weight bearing were possible 5 to 7 days after surgery. After 10 days, the patient was able to move while bearing weight with a slight disruption. With regard to trotting, the patient showed intermittent normal steps 5 to 7 days after surgery, but the disruption continued. After 14 days, trotting was possible, and it was observed that movement could be maintained during everyday activities.

Evaluation of proximodistal patellar alignment in small breed dogs with or without patellar luxation using the Insall-Salvati, Caton-Deschamps, and Blackburne-Peel indices.

Background: Patellar luxation in dogs is thought to be related to proximally (patella alta) or distally (patella baja) positioned patella in the femoral trochlea. Aim: The aim of the present study was to calculate and compare the values of Insall-Salvati (ISI), Caton-Deschamps (CDI), and Blackburne-Peel indices (BPI) in orthopedically healthy dogs and dogs with various grades of medial patellar luxation (MPL) from small breeds on mediolateral radiographs. Methods: The study included 87 dogs (138 stifles) from four breeds (Mini-Pinschers, Pomeranians, Chihuahuas, and Yorkshire terriers). Seventy joints (53 dogs) were diagnosed with various grades of MPL and another 68 joints from 34 dogs, free of orthopedic or neurological disorders, were used as controls. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic value of the three indices. Results: The CDI and BPI showed no significant difference between healthy and MPL joints. The ROC analysis showed that all three studied indices of proximodistal patellar position had poor diagnostic values with low sensitivity and specificity of respective cutoff values. Conclusion: In dogs from the studied four small breeds, the proximodistal ISI, CDI, and BPI patellar indices could not discriminate reliably between healthy stifle joints and joints with MPL.

Umbilical cord mesenchymal stem cells promote the repair of trochlear groove reconstruction in dogs.

Trochlear groove reconstruction (TGR) is a common treatment for patellar luxation (PL) in dogs. Nevertheless, the prognosis of TGR is poor due to the cartilage damage and secondary inflammation. To study the repair effect of canine umbilical cord mesenchymal stem cells (UC-MSCs) after TGR, 10 experimental dogs were given TGR surgery and then randomized into two groups: Treatment group (1 ml suspension allogeneic UC-MSCs (106 cells/kg) was injected into the cavum articulare on days 0, 7, and 14 after TGR); and the Model group (injected with 1 ml of physiological saline as negative control). The therapeutic effect of UC-MSCs was studied by blood routine examination, inflammatory factor index detection, double-blind knee score, histopathology, and computed tomography (CT) scans. The results showed that the total number of white blood cells and neutrophils in the model group were significantly higher than those in the treatment group on both 7 days and 21 days, postoperatively (P < 0.05); there were no significant changes in the levels of IL-6, MMP-13, and TGF-ß1 between the model group and the treatment group throughout the days of testing. The double-blind knee scores of the treatment group were significantly lower than the model group on 1st, 4th, and 5th days postoperatively (P < 0.05). The treatment group showed low-pain sensation, stable gait, and fast recovery of muscle strength in the knee score, and the wound healing of the treatment group returned to normal on the 5th day after surgery; CT scans and gross observation showed that the cartilage growth in the treatment group was faster than that in the model group. Histological observation of cases showed that fibro chondrocytes were predominantly found in the treatment group, and the distribution of chondrocytes was uneven, while the model group showed a large number of fibrous tissue hyperplasia, fissures, and unequal matrix staining. Intra-articular injection of UC-MSCs after TGR has the effect of relieving pain and promoting the repair of bone defects, making the operative limb recover function earlier, making up for the deficiency of TGR, and improving the effect of PL treatment. Future studies should furthermore explore the dose and frequency of therapy based on the multiple advantages of UC-MSCs and the mechanism of cartilage repair in dogs.

Positive outcomes after surgical correction of grade IV medial patellar luxation in small breed dogs.

Background: Medial patellar luxation (MPL) is a common orthopedic condition in dogs. After surgical correction, the recurrent rates appear to be higher and outcomes worse in grade IV than in lower grade MPL. Aim: To describe the outcomes of surgical correction of canine grade IV MPL. Methods: This retrospective study analyzed the medical records of 16 dogs (11 females, 5 males; mean age = 5.05 years) with 22 stifle joints (8 left and 14 right) that underwent MPL surgery at Rakuno Gakuen University between May 2015 and October 2020. The procedures included capsulorrhaphy, trochlear block recession, tibial tuberosity transposition, medial retinacular release, and lateral fabellotibial suturing. The types of postsurgical complications, including a recurrence of MPL, were recorded. Results: Twelve of the 16 (75 %) dogs had concurrent contralateral MPL, and 2 dogs (12.5%) had concurrent cranial cruciate ligament rupture. The mean follow-up was 12.1 months. No lameness was observed. The outcomes of surgery for grade IV MPL were not associated with bilateral surgery, age, sex, body weight, or the preoperative quadriceps angle. Although none of the dogs showed any major or catastrophic complications following surgery, postoperative minor and major complications were observed in 8 of the 22 stifle joints (36.4%). Conclusion: Grade IV MPL is a complex orthopedic disease in dogs, which requires surgical patellar realignment to improve limb function. The surgical techniques used in this study were associated with a good prognosis without a surgical revision.

Inter- and Intra-Observer Variations in Radiographic Evaluation of Pelvic Limbs in Yorkshire Terriers with Cranial Cruciate Ligament Rupture and Patellar Luxation.

The main aims of the study were to describe bone alignment differences in Yorkshire Terriers (YT) with cranial cruciate ligament rupture (CCLR), patellar luxation (PL), or with a combination of both (CCLR + PL); to verify the theory of increased strain on cranial cruciate ligament (CrCL) due to PL as a predisposing factor; and to evaluate intra- and inter-observer variability of the protocols developed for measurement of femoral and tibial alignment in Yorkshire Terriers. Fifty-five hindlimbs of YT were divided into four groups: Control, CCLR, PL, and CCLR + PL. Thirty parameters were radiographically evaluated including hip joint, femoral, tibial, and intercondylar fossa (ICF) parameters. Three observers evaluated all parameters on two separate occasions with a twelve-week interval between measurements. Significant differences in conjunction with CCLR and PL theories between groups were noticed in: Norberg angle (NA), quadriceps angle (Qa), anatomic lateral distal femoral angle (aLDFA), femoral varus (FVA), mechanical cranial proximal tibial angle (mCrPTA), mechanical caudal proximal tibial angle (mCdPTA), tibial plateau angle (TPA), distal tibial axis/proximal tibial axis angle (DPA). Some interesting findings are the similarity of values between Control and CCLR vs. CCLR + PL and PL groups in Na, Qa, aLDFA; between CCLR + PL and PL in FVA and a significantly lower age of dogs in CCLR + PL compared to CCLR group. Based on our results, we can conclude that YT with different clinical findings have differing bone morphology. Moreover, these findings may support PL as a predisposing factor for CCLR in small breeds. Measurements in which excellent inter- observer agreement was achieved may be used for surgical planning or for further discussions.

Modified medial patellofemoral ligament reconstruction for severe bilateral congenital patellar luxation in a dog.

Background: Lateral patellar luxation (LPL) is commonly diagnosed in large or giant breed dogs. In the surgical outcome for canine LPL, approximately half of the patients had complications, including reoperation and relaxation. Medial patellofemoral ligament (MPFL) reconstruction has been widely used for human repetitive patellar luxation. This case report describes that modified MPFL reconstruction with other surgical techniques might be effective for severe canine LPL repair. Case Description: An 11-month-old intact male Siberian Husky was referred to us with the main complication reported as bilateral hind lameness and LPL, diagnosed by a family doctor. Physiological examination showed bilateral patellar luxation (grade 4). We performed general surgical techniques with modified MPFL. The patient showed good prognosis. Conclusion: This report suggests that modified MPFL with general surgical techniques for LPL might be an effective surgical technique in dogs.

Determining the Variation in the Tibial Tuberosity Transposition Distance That Is Required to Correct the Quadriceps Angle With the Severity of Medial Patellar Luxation of the Canine Stifle Joint.

The aim of this study was to evaluate the transposition distance in in vitro canine medial patellar luxation (MPL) models of different severity grades using a single radiograph of the stifle joint. Each MPL grade model was generated with manipulation and evaluated by palpating the stability of the patella. An anterior-posterior radiograph of the entire hind limb with extended hip and stifle joints, including the iliopubic eminence, was used for all measurements. The quadriceps angles and the percentage of the transposition distance to the maximum width of the proximal tibia were measured. Our results demonstrated that when the tibial tuberosity transposition procedure is performed in a clinical setting, the required distance to correct the abnormal direction of the extensor mechanism in the canine stifle joint was greater in severe grade MPL than in mild grade MPL.

Tibial tuberosity transposition advancement for treatment of concomitant cranial cruciate ligament rupture and medial patellar luxation in four feline stifles.

CASE SERIES SUMMARY: Three cats (four stifles) were diagnosed with varying grades of medial patellar luxation and stifle instability in cranial tibial thrust. Radiographs showed periarticular osteophytosis, intra-articular mineralization and opacification encroachment of the infrapatellar fat pad. Stifle exploration revealed either partial (n = 2) or complete (n = 2) cranial cruciate ligament tear and medial meniscal injury in all cases. Medial meniscectomy, partial parasagittal patellectomy, femoral trochleoplasty and tibial tuberosity transposition advancement using a 6 mm cage, two-fork plate and 4 mm spacer were performed in four stifles. Screws (2.0 mm) and washers were used in the cranial cage ears rather than conventional 2.4 mm screws. By the 2-week recheck, lameness was minimal and stifles were stable. Radiographic follow-up at 8 weeks showed appropriate progression of osseous union in all cases. One cat experienced a major complication, suffering tibial fracture following a lapse in exercise restriction, and revision surgery was performed successfully with subsequent osseus union of the osteotomy site. At the mid-term follow-up, all cats had a return to previous level of function, as assessed by both owner questionnaire and clinical evaluation. RELEVANCE AND NOVEL INFORMATION: Tibial tuberosity transposition and advancement has been shown to be successful in dogs for the treatment of concomitant medial patellar luxation and cranial cruciate ligament rupture. To date, there have been no reports of tibial tuberosity transposition and advancement in cats. A benefit of this approach is concomitant alignment of the extensor mechanism and neutralization of the femorotibial shear force. Our case series describes successful use of tibial tuberosity transposition advancement in cats.

Patellar luxation in Hejazi goats.

Background: Patellar luxation (PL) is a common orthopedic affection among farm and pet animals with mostly congenital (environmental and/or genetic) background. Aim: We report here the first observation of lateral PL in Hejazi goats bred in Libya. Methods: Five Hejazi goats aged between 4 months and 2 years with severe hind limb lameness were admitted to Al-Sorouh veterinary clinic in Tripoli during the period from 2016 to 2018. The goats were thoroughly examined clinically and radiographically. Two goats were surgically treated, and the other three cases were not because of either the cost limitation or expected poor prognosis. The surgical intervention involved femoral trochlear sulcoplasty, medial joint capsule imbrication, and tibial tuberosity transposition. Results: The clinical examination showed grade III-IV lateral PL. Radiologically, there were unilateral or bilateral, ventrocaudal, and dorsal PLs. Two cases were referred to surgical correction. One case almost restored the normal movement of stifle joint together with a good general status 1 year postsurgery. However, the surgical treatment was not effective in correcting the luxated patella in the second case. Conclusion: Lateral PL is common among orthopedic affections in Hejazi goats in Libya, and its surgical treatment provided a quite convenient approach. An association between inbreeding and the PL was suggested in those cases.

Post-operative radiographic measures of pelvic limb alignment in dogs with medial patellar luxation after trochlear wedge recession versus trochlear block recession surgery.

BACKGROUND AND AIM: Anatomical and mechanical femoral angles are quite different among dog breeds. Most published data are about large dog breeds, however, medial luxation of patella is more common in small breeds. Measures of pelvic limb alignment are important for outcome of patellar luxation surgery. Therefore, the aim of the present study was to compare the values of anatomical and mechanical femoral and tibial angles in dogs before, immediately after, and 1 month after surgery for correction of medial patellar luxation (MPL). MATERIALS AND METHODS: The study was conducted with 54 dogs (67 stifle joints) from four small breeds that underwent surgery by either trochlear block recession (36 stifle joints) or trochlear wedge recession (31 stifle joints) techniques. RESULTS: In both trochleoplasty techniques, statistically significant differences in the values of the anatomical medial proximal femoral angle (aMPFA), anatomical lateral distal femoral angle (aLDFA), and femoral varus angle (in MPL Grade II) and of aMPFA and Q-angle (in MPL Grade III) were found out. CONCLUSION: After block recession surgery, more angles were positively influenced and this effect was more pronounced in patients with MPL Grade II.

Three-dimensional motion of the patella in French bulldogs with and without medial patellar luxation.

BACKGROUND: French bulldogs exhibit significantly larger femoral external rotation and abduction than other breeds. We were curious as to whether this peculiar leg kinematic affects patellar motion and/or might induce medial patellar subluxation (MPSL) or medial patellar permanent luxation (MPPL). We hypothesized that the more abducted leg posture during stance causes an unusual medial pull direction of the rectus femoris muscle during stance, and that this may facilitate the occurrence of MPSL or even MPPL during locomotion. To test our hypothesis, we analyzed existing stifle-joint X-ray-sequences collected during the treadmill walk and trot of seven adult female French bulldogs. We estimated 3D-patellar kinematics using Scientific Rotoscoping. RESULTS: The three-dimensional motion of the patella comprises rotations and translations. From the seven dogs analyzed, three exhibited MPSL and one MPPL during the gait cycle. Medial patellar luxation (MPL) occurred mostly around toe-off in both gaits studied. Patellar position was generally not gait-related at the analyzed timepoints. In dogs with MPL, the patella was placed significantly more distally (p = 0.037) at touch-down (TD) and at midswing (p = 0.024), and significantly more medial at midswing (p = 0.045) compared to dogs without MPL. CONCLUSIONS: Medial patellar luxation seems to be the consequence of the far from parasagittal position of the stifle joint during stance due to a broad trunk, and a wide pelvis. This peculiar leg orientation leads to a medial sideway pull caused by the rectus femoris muscle and the quadriceps femoris and may initiate plastic deformation of the growing femur and tibia. Thus, a way to avoid MPL could be to control breeding by selecting dogs with lean bodies and narrow pelvis. Actual breeding control programs based on the orthopedic examination are susceptible to errors. Systematic errors arise from the fact that the grading system is highly dependent on the dog's condition and the veterinarians' ability to perform the palpation on the stifle. Based on our results, the position of the patella at TD, or even perhaps during stand might offer a possibility of an objective radioscopic diagnostic of the MPL.

Canine cruciate ligament ruptures: Implications for financial costs and human health.

The cranial cruciate ligament (CCL) in dogs is homologous to the anterior cruciate ligament (ACL) in humans. Factors that place an individual at-risk for noncontact ruptures are not clearly defined in humans or dogs. Cyclic variation in human females as well as early spay/neuter in canines has frequently implicated hormonal variation, however these factors do not fully explain the human dimorphic or canine breed rupture rates. The present study examined dogs as a proxy model for humans to better understand the covariance. A random clinical data sample from the Oklahoma State University Veterinary Hospital was obtained on (n = 29) CCL surgical cases and nonsurgical (n = 28) controls. A statistical test for association of spay/neuter with CCL rupture was significant (chi-square = 21.7, p < .01). Sex balance between the groups was not significantly (p > .01) different. Data on other variables related to morphometric variability such as the tibial plateau angle was not available on the nonsurgical sample and comparisons could only be made to values from the literature. Though there may have been sample bias, this preliminary study found that more large than small dogs were represented in the surgical sample. Our results also support the claim that spayed/neutered dogs are more likely to rupture their CCL than intact dogs. Given the high costs of surgical repair, both for canines and humans, we argue for multivariate studies that investigate the interaction of variables in a larger subject sample which can provide comparable data on all parameters.