Risk factors for ventral luxation in canine total hip replacement

Objective— To identify risk factors associated with ventral luxation (VL) of canine total hip replacement (THR), and outcome.
Study Design— Retrospective study.
Animals— Dogs (n=602) that had THR (563 cemented, 35 cementless, 4 hybrid).
Methods— Dogs (1999–2004) with VL after THR were compared with dogs with uncomplicated THR. Data included signalment, body weight, diagnosis, implant size, acetabular cup orientation, and femoral displacement ratio (FDR).
Results— VL was diagnosed in 11 (1.8%) dogs after primary THR. Including 2 other dogs that had VL after the study period, 10 (77%) of 13 dogs had VL within 7 days of surgery. Risk factors for VL included Saint Bernard-type dogs ( P =.0001), short neck extension ( P =.0005), and high angle of lateral opening in other breeds ( P =.018). There were trends toward higher risk of VL with lower FDR in Saint Bernardtypes ( P =.060), and with cementless implants ( P =.061). Twelve dogs had revision arthroplasty that was successful in all cementless and 2 cemented VL cases. Five dogs had recurrent VL and a poor outcome.
Conclusion— VL is generally an early complication of THR, with no single common risk factor identified.
Clinical Relevance— Saint Bernard types and short neck extensions are associated with increased risk of VL. Poor cup orientation is a determining factor for VL in some dogs, but a protective orientation of the acetabular cup was not found. Revision is successful in most dogs, but recurrent VL merits a guarded prognosis.     

Evaluation of Functional Outcome After BFX® Total Hip Replacement Using a Pressure Sensitive Walkway

Objective— To evaluate stance phase limb use after cementless (BFX^®) total hip replacement (THR) in dogs and to relate postoperative radiographic variables to static bodyweight distribution after surgery.
Study Design— Prospective clinical study.
Animals— Dogs (n=35) that had THR.
Methods— THR was performed using the BFX^® THR technique. Postoperative pain management regimens were similar for all dogs. Standing bodyweight distribution (%BW_distrib) was measured using a pressure sensitive walkway and radiographs made before surgery and at 3, 6, and 12 months after surgery. Repeated measures models (with backwards-stepping to obtain the final model) were used for statistical analysis.
Results— Temporally, %BW_distrib to the operated limb increased ( P <.0001; normal by 3 months) and decreased to the unoperated limb ( P =.0001) and also increased to the pelvic limbs and decreased to the thoracic limbs. %BW_distrib to the unoperated limb was significantly less than the operated limb at 3, 6, and 12 months after surgery. Postoperative canal fill and femur flare were significantly negatively correlated with change in %BW_distrib (estimate=−0.24, P =.0413).
Conclusion— BFX^® THR results in normal %BW_distrib to the operated limb by 3 months after surgery. A greater fill of the proximal femur may be associated with a suboptimal outcome.
Clinical Relevance— BFX^® THR normalizes standing bodyweight distribution dogs with hip osteoarthritis. Objective evaluation of THR outcome and radiographic features may reveal factors that could be improved through changes in prosthesis design or surgical technique.     

Iatrogenic sciatic nerve injury in eighteen dogs and nine cats (1997-2006)

Objective— To report clinical features associated with iatrogenic peripheral nerve injury in dogs and cats admitted (1997–2006) to a referral teaching hospital.
Study Design— Retrospective study.
Animals— Dogs (n=18), 9 cats.
Methods— Patients had acute signs of monoparesis attributable to sciatic nerve dysfunction that developed after treatment. Neurologic examination and electrodiagnostic testing were performed. Surgical therapy was used for nerve entrapment and delayed reconstructive surgery used in other cases.
Results— Of 27 nerve injuries, 25 resulted from surgery (18 with treatment of pelvic injuries). Iliosacral luxation repair resulted in tibial (4 cats) and peroneal (3 dogs) nerve dysfunction. Other causes were intramedullary pinning of femoral fractures (3), other orthopedic surgery (cemented hip prosthesis [2] and tibial plateau-leveling osteotomy [1]), and perineal herniorrhaphy [1]. Nerve injury occurred after intramuscular injection (1 cat, 1 dog). Immediate surgical treatment was removal of intramedullary nails, extruded cement, or entrapping suture. Delayed nerve transplantation was performed in 2 dogs. Within 1 year, 13 patients recovered completely, clinical improvement occurred in 7, and there was no improvement in 7. Five of the 7 dogs that did not recover had acetabular or ilium fracture.
Conclusion— Iatrogenic sciatic nerve injury occurred most commonly during treatment of pelvic orthopedic diseases and had a poor prognosis. Clinical variation in sciatic nerve dysfunction in dogs and cats can be explained by species anatomic differences.
Clinical Relevance— Iatrogenic sciatic nerve injury leads to severely debilitating locomotor dysfunction with an uncertain prognosis for full-functional recovery.     

Micro Total Hip Replacement for Dogs and Cats: Surgical Technique and Outcomes

Objective: To describe the surgical technique for the micro total hip replacement (Micro THR) system and report clinical outcomes. Study Design: Prospective study. Animals: Dogs (n=49) and cats (n=8) with coxofemoral arthropathy. Methods: Small breed dogs and cats with coxofemoral arthritis were enrolled for Micro THR. Patient data were recorded. Implant positioning and cement mantle quality were evaluated radiographically. Orthopedic examinations and client interviews were used to assess outcome. Results: Micro THR was performed unilaterally (40 dogs, 8 cats) and staged bilaterally (9 dogs) to resolve pain associated with osteoarthritis or trauma. Mean body weight was 7.2 kg. Postoperative complications included prosthesis luxation (9), cup aseptic loosening (1), and sciatic neurapraxia (1). Mean radiographic follow up was 96.1 weeks; 10 joints were followed for ≥3.0 years. Sixty of the 66 (91%) Micro THRs had excellent outcomes. Two dogs (<2.75 kg) were too small for the prosthesis and 4 dogs with unmanageable luxation had explantation. Conclusions: Micro THR is considered a satisfactory procedure for management of small breed dogs and cats with coxofemoral disease unresponsive to medical management. Clinical Relevance: Micro THR is a viable option to treat disabling disorders of the hip. More than 170 cat and small dog breeds, and many mixed breeds, could benefit from Micro THR surgery.     

Proximodistal alignment of the canine patella: radiographic evaluation and association with medial and lateral patellar luxation

Objectives— To evaluate the contribution of proximodistal alignment of the patella to patellar luxation, and to evaluate the structures contributing to proximodistal alignment of the patella relative to the femoral trochlea.
Study Design— Retrospective study using a convenience sample.
Animals— Medium to giant breed dogs (n=106).
Methods— Medical records and stifle radiographs of 106 dogs were reviewed. Radiographic measurements evaluated the proximodistal alignment of the patella with respect to the femoral trochlea, distal aspect of the femur, and proximal aspect of the tibia. Measurements were compared between dogs with clinically normal stifles (controls; n=51 dogs, 66 stifles), and dogs with a clinical diagnosis of medial patellar luxation (MPL, n=46 dogs, 65 stifles) or lateral patellar luxation (LPL, n=9 dogs, 11 stifles) using ANOVA.
Results— In dogs with MPL, the ratio of patellar ligament length (PLL) to patellar length (PL) was increased, as was the ratio of the distance from the proximal aspect of the patella to the femoral condyle (A) to PL ( P <.0001). Dogs with LPL had a decreased A:PL ( P =.003) and an increased ratio of the proximal tibial length (PTL) to distal tibial width (DTW; P =.009).
Conclusions— MPL is associated with a relatively long patellar ligament and patella alta in medium to giant breed dogs. LPL is associated with a relatively long proximal tibia and patella baja. Values for PLL:PL>2.06 and A:PL>2.03 are suggestive of the presence of patella alta, whereas a value for A:PL<1.92 is suggestive of patella baja.
Clinical Relevance— Measurements of both PLL:PL and A:PL are recommended in dogs with patellar luxation, and surgical correction should be considered in those with abnormal values.     

Evaluation of risk factors for luxation after total hip replacement in dogs

OBJECTIVE: To identify risk factors for luxation after canine total hip replacement (THR). STUDY DESIGN: Retrospective study. SAMPLE POPULATION: 256 client-owned dogs that underwent THR. METHODS: Patient data surveyed included signalment, body weight, diagnosis, prior hip surgery, implant size, intraoperative complications, and angle of lateral opening of the acetabular component. RESULTS: Postoperative complications were recorded in 20 cases (7.8%). The most common complication was dorsal luxation which occurred in 12 dogs (4.7%). The interval between joint replacement and luxation ranged from 1 to 116 days (mean, 44 days). In 1 case, luxation was attributable to failure of the repair of an intraoperative fracture of the greater trochanter. Excluding this case, the mean angle of lateral opening in those dogs that sustained luxation was 62 degrees (range, 46 degrees - 75 degrees). The mean angle of lateral opening overall was 48 degrees (range, 18 degrees - 76 degrees). The angle of lateral opening was the only factor that had a statistically significant effect on whether luxation occurred (P = .035). Acetabular revision, performed primarily to reduce the angle of lateral opening, was performed in 8 dogs and successfully prevented subsequent luxation. CONCLUSION: Luxation of the prosthesis is substantially under the control of the surgeon. It is recommended that the acetabular cup be inserted at an angle of lateral opening of 35 degrees to 45 degrees. In those cases of THR luxation in which an inappropriate angle of lateral opening is identified, acetabular revision arthroplasty generally results in a good clinical outcome.     

Risk factors for tibial tuberosity fracture after tibial plateau leveling osteotomy in dogs

Objective— To evaluate factors that predispose to tibial tuberosity (TT) fracture after tibial plateau leveling osteotomy (TPLO) in dogs.
Study Design— Retrospective study.
Animals— Dogs (n=182) with cranial cruciate ligament (CCL) rupture undergoing 213 TPLO surgeries.
Methods— Medical records and radiographs of 2 groups of dogs that had TPLO surgery (2000–2001, 2004–2005) were evaluated to determine the effect of operative technique and surgeon experience on TT fracture.
Results— TT fracture was diagnosed in 8 dogs (9 TPLO, 4.2% of surgical procedures). Four fractures occurred after unilateral TPLO in 167 dogs (2.4%), 4 fractures occurred after simultaneous bilateral TPLO in 5 dogs (40%), and 1 fracture occurred after staged bilateral TPLO in 36 dogs (2.8%). Simultaneous bilateral TPLO resulted in a 12.4 times higher odds of TT fracture versus unilateral TPLO ( P =.046). The mean absolute thickness of the TT after TPLO was less in dogs sustaining TT fractures (7.2 ± 2.2 mm) than those that did not (10.8 ± 2.7 mm, P <.0001). The odds of fracture decreased by 37% when the absolute TT width postosteotomy increased by 1 mm ( P <.0001). An increase in tibial plateau angle at follow-up versus immediately postoperative was associated with TT fracture ( P =.025). Surgeon experience was not associated with TT fracture.
Conclusion— A combination of surgical decision-making and surgical technique play a role in the occurrence of TT fracture after TPLO. Simultaneous bilateral TPLO was associated with a high percentage of TT fracture.
Clinical Relevance— Careful planning of osteotomy positioning is advised while performing TPLO surgery.     

Cementless Total Hip Replacement in an Alpaca

Objective— To report management of a chronic slipped capital femoral epiphysis (SCFE) in an alpaca using cementless total hip replacement (THR).
Study Design— Case report.
Animal— An 18-month-old, 47 kg alpaca male.
Methods— Cementless THR was performed in an alpaca with a chronic, right SCFE, and secondary osteoarthritis. Force plate gait analysis was performed before and 8 weeks after surgery. Outcome was determined through clinical evaluation, radiography, and force plate gait analysis.
Results— Cementless THR resulted in marked improvement in the alpaca's comfort level, degree of lameness, and range of motion. On preoperative force plate gait analysis there was decreased contact time ( P =.01) and vertical impulse ( P <.01) of the affected limb, whereas at 8 weeks postoperatively significant differences in gait analysis between pelvic limbs were not apparent.
Conclusion— THR using a BioMedtrix^® canine cementless modular prosthesis restored hip function in an alpaca with coxofemoral osteoarthritis from chronic SCFE.
Clinical Relevance— THR may be an appropriate treatment for selected traumatic and degenerative conditions of the coxofemoral joint in alpacas.     

Does the Degree of Preoperative Subluxation or Soft Tissue Tension Affect the Incidence of Postoperative Luxation in Dogs after Total Hip Replacement?

Objective: To investigate whether preexisting coxofemoral subluxation/luxation predisposes to postoperative total hip replacement (THR) luxation. Study Design: Case series. Animals: Dogs (n=100) that had cemented THR (n=109); 23 normal controls. Methods: A preliminary study was performed to validate our methods of assessing luxation and laxity by comparing dogs with severe hip dysplasia with a control population of normal dogs. For the main study, the records and radiographs of all dogs that had primary THR were reviewed. Measurements taken from preoperative radiographs to quantify hip subluxation/laxity included the Norberg angle, subluxation index, and 2 new measures: acetabular depth ratio (ADR) and dorsal acetabular rim ratio (DARR). Differences between groups that had luxation within 8 weeks and those that did not were investigated. Results: Postoperative luxation occurred in 13 dogs (12%) within 8 weeks of surgery. Luxation was significantly associated with various measurements (including Norberg angle, ADR, DARR) thought to reflect degree of subluxation/soft tissue tension. Conclusion: Luxation after canine THR is a multifactorial problem but preexisting subluxation/soft tissue laxity is a significant risk factor for this complication.     

Total Hip Replacement in an Alpaca Using a Cementless Implant

Objective— To report use of a cementless total hip prosthesis in an alpaca.
Study Design— Case report.
Animals— Alpaca (n=1) with chronic craniodorsal coxofemoral luxation.
Methods— A 2.5-year-old Suri alpaca, 3 months pregnant, was admitted for evaluation of acute onset severe left hind limb lameness (grade 4/5) of 6 weeks duration. After diagnosis of craniodorsal luxation of the left femoral head, total hip replacement (THR) using a cementless implant was performed because of the poor prognosis for reduction of a chronic luxation.
Results— A press-fit prosthesis was used and the alpaca delivered a live cria 8 months later. Persistent mild mechanical lameness remained after surgery, with moderate reduction in mobility of the coxofemoral joint. The prosthesis was stable and correctly positioned at 7 weeks and at 9 months. There was mild exostosis surrounding the proximal aspect of the femur at 9 months, and Steinmann pins used to repair the trochanteric osteotomy were removed because of migration. At 1 year, the alpaca has a slight gait abnormality, remains with the herd on pasture and has been re-bred.
Conclusion— Chronic coxofemoral luxation in an alpaca can be managed by THR.
Clinical Relevance— THR is a viable treatment option in alpacas with severe coxofemoral disease.     

Complications associated with corrective surgery for patellar luxation in 109 dogs

OBJECTIVE: To review surgical techniques and postoperative complications associated with correction of patellar luxation in dogs. STUDY DESIGN: Retrospective study. ANIMALS: Dogs (n = 109) with patellar luxation (n = 131). METHODS: Medical records of dogs that had corrective surgery for patellar luxation were reviewed. Signalment, history, grade and direction of patellar luxation, operative technique and clinical outcomes were retrieved. RESULTS: Overall frequency of postoperative complications was 18%. Frequency of major (requiring revision surgery) complications was 13%. Frequency of patellar reluxation was 8%. Frequency of overall, major, and patellar reluxation complications was higher for dogs weighing > or =20 kg compared with those <20 kg. Frequency of overall and major complications was higher for dogs with higher grades of patellar luxation. Femoral trochlear sulcoplasty resulted in lower frequency of patellar reluxation. Tibial tuberosity transposition (TTT) resulted in lower frequency of major complications and patellar reluxation. Retinacular/capsular release resulted in higher frequency of major complications. Patient age, gender, medial versus lateral patellar luxation, left versus right hindlimb, capsular/retinacular imbrication, use of anti-rotational sutures, and whether stifle surgery had been performed previously did not significantly influence frequency of complications. CONCLUSION: TTT and femoral trochlear sulcoplasty minimize the risk of postoperative patellar reluxation and major complications. CLINICAL RELEVANCE: Information derived from this study can be used to estimate the likelihood of postoperative complications for canine patients undergoing corrective surgery for patellar luxation.     

Laser-Doppler Measurements of Spinal Cord Blood Flow Changes During Hemilaminectomy in Chondrodystrophic Dogs with Disk Extrusion

Objectives— (1) To assess spinal cord blood flow (SCBF) during surgical treatment of disk extrusion in dogs and (2) to investigate associations between SCBF, clinical signs, presurgical MRI images, and 24-hour surgical outcome.
Study Design— Cohort study.
Animals— Chondrodystrophic dogs with thoracolumbar disk extrusion (n=12).
Methods— Diagnosis was based on clinical signs and MRI findings, and confirmed at surgery. Regional SCBF was measured intraoperatively by laser-Doppler flowmetry before, immediately after surgical spinal cord decompression, and after 15 minutes of lavaging the lesion. Care was taken to ensure a standardized surgical procedure to minimize factors that could influence measurement readings.
Results— A significant increase in intraoperative SCBF was found in all dogs (Wilcoxon's signed-rank test; P =.05) immediately after spinal cord decompression and after 15 minutes. Changes in SCBF were not associated with duration of clinical signs; initial or 24-hour neurologic status; or degree of spinal cord compression assessed by MRI.
Conclusion— SCBF increases immediately after spinal cord decompression in dogs with disk herniation; however, increased SCBF was not associated with a diminished 24-hour neurologic status.
Clinical Relevance— An increase in SCBF does not appear to be either associated with the degree of spinal cord compression or of a magnitude sufficient to outweigh the benefit of surgical decompression by resulting in clinically relevant changes in 24-hour outcome.     

Evaluation of the success of medical management for presumptive thoracolumbar intervertebral disk herniation in dogs

Objective— To determine the success of medical management of presumptive thoracolumbar disk herniation in dogs and the variables associated with treatment outcome.
Study Design— Retrospective case series.
Animals— Dogs (n=223) with presumptive thoracolumbar disk herniation.
Methods— Medical records from 2 clinics were used to identify affected dogs, and owners were mailed a questionnaire about success of therapy, recurrence of clinical signs, and quality of life (QOL) as interpreted by the owner. Signalment, duration and degree of neurologic dysfunction, and medication administration were determined from medical records.
Results— Eighty-three percent of dogs (185/223) were ambulatory at initial evaluation. Successful treatment was reported for 54.7% of dogs, with 30.9% having recurrence of clinical signs and 14.4% classified as therapeutic failures. From bivariable logistic regression, glucocorticoid administration was negatively associated with success ( P =.008; odds ratio [OR]=.48) and QOL scores ( P =.004; OR=.48). The duration of cage rest was not significantly associated with success or QOL. Nonambulatory dogs were more likely to have lower QOL scores ( P =.01; OR=2.34).
Conclusions— Medical management can lead to an acceptable outcome in many dogs with presumptive thoracolumbar disk herniation. Cage rest duration does not seem to affect outcome and glucocorticoids may negatively impact success and QOL. The conclusions in this report should be interpreted cautiously because of the retrospective data collection and the use of client self-administered questionnaire follow-up.
Clinical Relevance— These results provide an insight into the success of medical management for presumptive thoracolumbar disk herniation in dogs and may allow for refinement of treatment protocols.     

TP53 gene mutations in canine osteosarcoma

Objective— To investigate mutations of the TP53 gene in canine osteosarcoma (OS).
Study Design— Clinical historic cohort study.
Animals— Client-owned dogs.
Methods— OS (n=59) were screened for mutations of the complete TP53 gene using polymerase chain reaction and the mutation was analyzed by single-strand conformational polymorphism. Clinical outcome of dogs with TP53-mutated OS were compared with dogs with OS without a mutation after complete surgical excision of the primary tumor.
Results— TP53 gene mutations were observed in 24 of 59 (40.7%) OS; 3 mutated OS had 2 mutations. The alterations consisted mainly of point mutations (74%). Dogs with mutated OS had a significantly shorter survival time (ST) after surgery than dogs with normal tumor TP53 gene expression ( P =.03). Other significant prognosticators for ST and disease-free interval included elevated serum alkaline phosphatase ( P <.01) and tumor grade ( P =.01).
Conclusion— TP53 genetic mutations are common in canine OS and may have a prognostic value.
Clinical Relevance— Mutations of the TP53 gene may influence survival and should be considered when evaluating canine OS.     

Zurich Cementless Total Hip Replacement: Retrospective Evaluation of 2nd Generation Implants in 60 Dogs

Objective— To evaluate the results of application, and identify complications, of the 2nd generation of Zurich Cementless Total Hip Replacement (ZCTHR).
Study Design— Case series.
Animals— Client-owned dogs (n=60) that had ZCTHR (n=65).
Methods— Dogs with ZCTHR (2001–2003) with a minimum follow-up ≥6 months were evaluated. Data included signalment, cup position, longest follow-up, complications, management of complications and outcome.
Results— Mean follow-up was 22.68 months. Eleven cases (17%) had postoperative complications: femoral fracture (n=1; 1.5%), prosthesis luxation (7; 11%), cup loosening (2; 3%), and implant failure (1; 1.5%); 9 cases were successfully revised. Explantation of implants was performed in 1 case because of infection, and 1 dog was euthanatized after reluxation.
Conclusions— ZCTHR can restore function in dogs affected by disabling diseases of the coxofemoral joint. The press-fit fixation of the cup allowed for corrections in cases of incorrect positioning. Cases with aseptic loosening were revised successfully by impacting larger cups. Newer stems of this generation are shot peening treated to increase their resistance to breakage. In our cases, infection is a disastrous event, leading to implant removal. After resolution of complications, a successful final outcome was achieved in 97% of THR.
Clinical Relevance— ZCTHR offers a reliable alternative for treating dogs with disabling diseases of the hip joints.     

Traumatic elbow luxation in 14 dogs and 11 cats

Objective To report the presentation and treatment of traumatic elbow luxation and to evaluate success following closed or open reduction. Design Retrospective case series conducted between April 1999 and April 2009. Methods Records of 14 dogs and 11 cats were reviewed for signalment, history, radiographic findings and treatment; 14 owners were contacted via phone questionnaire to assess for limb function following treatment. Fisher's two‐tailed P test was used to evaluate potential risk factors for lameness. Results The majority of luxations were caused by car accident and 96% of the cases luxated in a lateral direction. Closed reduction was successful in all cats and 11 dogs; 3 dogs required open reduction. Owners rated the animals' limb function as excellent (71%), good (7%), fair (22%) or poor (0%). All cats were rated excellent. An excellent result following closed reduction was achieved in 67% of canine cases. All cases of open reduction achieved fair results. All owners were satisfied with the outcome. No risk factors were significantly associated with post‐reduction lameness. Conclusions Elbow joints with good stability following closed reduction have a favourable outcome. Poor stability following closed reduction is an indication for surgery. Results suggest that cats tolerate elbow luxation better than dogs.     

Mammary tumor recurrence in bitches after regional mastectomy

Objectives— To investigate the histologic diagnosis and incidence of new mammary tumor growth in the remaining mammary chain tissue after regional mastectomy.
Study Design— Prospective clinical study.
Animals— Female dogs (n=99) that had excision of a single mammary tumor.
Methods— Female dogs that had regional mastectomy to remove a single tumor were followed for ≥1 year postoperatively. Data regarding tumor type, tumor recurrence, and development of metastasis were recorded.
Results— Fifty-seven (58%) dogs developed a new tumor in the ipsilateral mammary chain after the 1st surgery; 77% had repeat surgery. There was no significant correlation between the time to new tumor development and the histologic diagnosis for the 1st and 2nd tumor types. In 31 dogs, the histologic diagnosis for initial and subsequent tumors was identical and there was a significant correlation such that dogs with an initial malignant tumor are likely to develop another malignant tumor ( P =.0089). The histologic classification of the new tumor was likely to be malignant if it was located close to the side where the initial tumor had been removed ( P =.026).
Conclusions— Our results show that 58% of dogs developed a new tumor in the remaining mammary glands of the ipsilateral chain after regional mastectomy for removal of a single tumor.
Clinical Relevance— This should be taken into account when deciding on the surgical management (radical or regional mastectomy) in dogs with single mammary tumors.     

Femur fractures associated with canine total hip replacement

OBJECTIVE: To report femur fracture as a complication of canine total hip replacement (THR) and to report the incidence, predisposing factors, treatment options, and outcome. STUDY DESIGN: Prospective clinical study. ANIMALS: Twenty-two client-owned dogs with 24 femoral fractures occurring during or after THR. METHODS: Cemented THR (BioMedtrix, Boonton, NJ) was performed. Medical records and radiographs were used to identify dogs that had femur fracture and to identify risk factors. Follow-up was obtained until dog death or study end. RESULTS: The overall incidence of femur fracture after THR was 2.9%. Femoral fractures occurred intraoperatively, immediately postoperatively, and up to 2196 days after THR. In 17 dogs, fractures resulted from a traumatic event. Osteopathy was present at THR in 5 dogs; all developed femoral fissures during reaming. Three dogs had fractures associated with cortical thinning secondary to aseptic loosening. Fracture treatment included euthanasia (1 dog), strict confinement (3 dogs), full cerclage wires on long oblique fractures (3 dogs), or plate and screw fixation (10 with, and 7 without, cerclage wires). All fractures extended near the distal tip of the femoral stem and all aggressively treated fractures healed. CONCLUSIONS: Predisposing risk factors for femur fracture after THR include osteopathy and iatrogenic fissures created during reaming. Trauma, excessive load concentration, and increased torque can lead to mid-diaphyseal fracture near the end of the femoral stem. Fracture did not disrupt THR implants. Cement fracture exposing the tip of the femoral stem did not affect fracture healing or rehabilitation. Immediate plate and screw fixation resulted in the most favorable outcome; healing occurred in 6-10 weeks. CLINICAL RELEVANCE: Femur fractures that occur after THR should be repaired using plate and screw fixation augmented with cerclage wire when needed. Forces on fissures should be neutralized to prevent propagation and fracture. Owners of high-risk patients (old dogs with osteopathies or previous hip surgery) should be counseled before THR. The prognosis is excellent when fractures are treated correctly.     

Closed fluoroscopic-assisted spinal arch external skeletal fixation for the stabilization of vertebral column injuries in five dogs

Objective— To evaluate outcome after closed fluoroscopic-assisted application of spinal arch external skeletal fixators in dogs with vertebral column injuries.
Study Design— Retrospective case series.
Animals— Dogs with traumatic vertebral column injuries (n=5).
Methods— Medical records of dogs with vertebral column fractures and/or luxations stabilized with spinal arch external skeletal fixator frames applied using a closed fluoroscopic-assisted technique were reviewed. Owners were contacted to obtain long-term clinical outcomes.
Results— Five dogs (age range, 6–72 months; weight, 10–54 kg) had traumatic vertebral column injuries stabilized with spinal arch external skeletal fixators applied in closed fashion. Injuries involved vertebral segments of the thoracolumbar junction, lumbar spine, and lumbosacral junction. Immediately postoperatively, 4 dogs had anatomic alignment of their vertebral fracture/luxation; 1 dog had 1 mm of vertebral canal height compromise. Time to fixator removal ranged from 65 to 282 days (141±87 days). All dogs had regained satisfactory neurologic function by 3 months. At long-term follow-up (range, 282–780 days; mean 445±190 days) all dogs were judged to have good to excellent return of function by their owners.
Conclusion— Successful closed fluoroscopic-assisted application of external skeletal fixators using spinal arches provided satisfactory reduction with few complications in 5 dogs. Return to function was judged to be good to excellent in all dogs at long-term evaluation.
Clinical Relevance— Closed fluoroscopic-assisted application of ESF using spinal arches provided satisfactory reduction and effective stabilization of spinal fractures with few complications and should be considered as a treatment approach.     

Influence of Canal Preparation Depth on the Incidence of Femoral Medullary Infarction with Zurich Cementless Canine Total Hip Arthroplasty

Objective— To determine the incidence of femoral medullary infarction after modifying the depth of femoral reaming and filing when performing total hip replacement (THR) using the Zurich Cementless Total Hip Replacement system (ZCTHR).
Study Design— Case series.
Animals— Dogs (n=31) that had ZCTHR (34).
Methods— Thirty-one dogs (34 THR) had ZCTHR (May 2003–September 2006) and with >1 year radiographic (craniocaudal, mediolateral views) follow-up after THR were evaluated for the presence of femoral medullary infarcts. Incidence was compared with a previous study performed before the technique modification.
Results— Femoral medullary infarction occurred in 1 femur (2.9%; dog <18 months at THR) compared with 19.5% before the technique change, a significant decrease ( P <.001).
Conclusion— Limiting the depth of reaming and filing of the medullary canal resulted in a significant decrease in the incidence of femoral medullary infarction.
Clinical Relevance— Depth of reaming and filing the medullary canal should be limited when performing THR using the ZCTHR.