Arthroscopic-assisted hip toggle stabilization in cats: An ex vivo feasibility study.

OBJECTIVE: To describe arthroscopic-assisted hip toggle stabilization (AA-HTS) in cats, evaluate its feasibility and associated rate of iatrogenic injury, and assess deviations from planned surgical technique. STUDY DESIGN: Ex vivo study. ANIMALS: Skeletally mature cat cadavers (n = 7). METHODS: Preoperative pelvic computed tomography (CT) was performed for surgical planning and to identify the ideal femoral bone tunnel projection. Ultrasound-guided transection of ligament of head of femur was performed. Following exploratory arthroscopy, AA-HTS was performed using a commercially available aiming device. Surgical time, intraoperative complications, and feasibility of technique were recorded. Iatrogenic injury and technique deviations were assessed by postoperative CT and gross dissection. RESULTS: Diagnostic arthroscopy and AA-HTS were successfully performed in all 14 joints. Median (range) surgical time was 46.5 (29-144) min, including 7 (3-12) min for diagnostic arthroscopy and 40 (26-134) min for AA-HTS. Intraoperative complications occurred in 5 hips, related to bone tunnel creation (4) and toggle dislodgment (1). Toggle passage through the femoral tunnel was the most challenging component of technique, recorded as mildly difficult in 6 joints. No damage to periarticular/intrapelvic structures was identified. Minor articular cartilage damage (<10% total cartilage area) was identified in 10 joints. Thirteen deviations (8 major, 5 minor) in surgical technique from preoperative planning were identified in 7 joints. CONCLUSION: In feline cadavers AA-HTS was feasible but was associated with a high rate of minor cartilage injury, intraoperative complications, and technique deviations. CLINICAL SIGNIFICANCE: Hip toggle stabilization using an arthroscopic-assisted approach may be an effective technique for management of coxofemoral luxation in cats.

Outcomes and complications reported from a multiuser canine hip replacement registry over a 10-year period.

OBJECTIVE: To report outcomes and complications associated with total hip replacements (THR) using a multiuser canine hip registry (CHR) and owner-administered questionnaire. STUDY DESIGN: Prospective longitudinal clinical study. ANIMALS: Dogs (n = 1852). METHODS: Total hip replacement cases submitted to a CHR were reviewed. An online questionnaire including an adapted "Liverpool Osteoarthritis in Dogs" (LOAD) score was e-mailed to owners. Data were analyzed to determine associations between clinical variables and the agreement by veterinary surgeons and owners for complications. RESULTS: A group of 1329 (72%) dogs had unilateral THRs and another group of 523 (28%) dogs had bilateral THRs, resulting in 2375 THRs. Indications included hip dysplasia and osteoarthritis (n = 2028/2375, 85%). Implants were manufactured by Kyon (n = 1087, 46%), BioMedtrix CFX (n = 514, 22%), BioMedtrix hybrid (n = 264, 11%), BioMedtrix BFX (n = 221, 9%), and Helica (n = 107, 4.5%). Median veterinary surgeon and owner follow up were 1328 and 900 days respectively. Postoperative LOAD scores (21 ± 9) reported by 461 owners improved compared to preoperative scores (11 ± 9) (P < .001). Veterinary surgeons reported complications in 201/2375 (8.5%) THRs and owners in 107/461 (23%) THRs, with moderate agreement (weighted kappa = 0.44). No associations were identified between complications and weight, age, sex, or breed. BioMedtrix BFX and Helica implants were associated with increased complications (P = .031) when used for revisions of femoral head and neck excisions. CONCLUSION: Excellent outcomes, including improved canine mobility, were reported after THRs. Complications were underreported by veterinary surgeons compared to owners in this first multiuser CHR. CLINICAL SIGNIFICANCE: Canine THRs are safe, effective procedures but THR implants should be carefully selected when revising femoral head and neck excisions.

Complications and outcomes of cats with coxofemoral luxation treated with hip toggle stabilization using ultrahigh-molecular-weight-polyethylene or nylon (2009-2018): 48 cats.

OBJECTIVE: To report overall rate and type of complications and outcomes of cats with coxofemoral luxation managed with hip toggle stabilization (HTS), to compare rate of postoperative complications and outcomes of cats treated with ultrahigh-molecular-weight-polyethylene (UHMWPE) or nylon, and to identify risk factors for reluxation and non-excellent outcomes. STUDY DESIGN: Multi-institutional retrospective cohort study. SAMPLE POPULATION: Forty-eight client-owned cats. METHODS: Medical records of cats that underwent HTS from 2008-2018 using UHMWPE or nylon were reviewed. Univariable and multivariable logistic regression was performed to assess for factors associated with reluxation and non-excellent outcome. Final outcome was obtained from owner questionnaire. RESULTS: Intraoperative and postoperative complications were recorded in two (4.2%) and 11 (24.4%) cats, respectively. The most common postoperative complication was reluxation (n = 5 [11.1%]). Outcome was classified as excellent in 81.1% and good in 16.2% of cats after a median of 445.5 days (range, 53-3720). No difference in rate of complications or outcomes was identified between UHMWPE and nylon. Performance of additional orthopedic procedures, occurrence of intraoperative complications, and non-performance of capsulorrhaphy were associated with reluxation. Performance of additional non-hip procedures (orthopedic/nonorthopedic) was associated with non-excellent outcome. CONCLUSION: Hip toggle stabilization was associated with a low rate of intraoperative complications and reluxation and excellent long-term outcomes in most cats. No difference in rate of postoperative complications or outcomes of cats treated using UHMWPE or nylon was identified. Cats that underwent additional orthopedic procedures had greater risk of reluxation. CLINICAL SIGNIFICANCE: Hip toggle stabilization is an effective technique for management of coxofemoral luxation in cats. Comparable results are expected using UHMWPE or nylon.

Effect of stifle flexion on the position of the cranial tibial artery relative to the proximal tibia in dogs.

OBJECTIVE: To determine the effect of stifle flexion on the proximity of the cranial tibial artery to the proximal tibia in canine stifles with an intact or transected cranial cruciate ligament (CCL). STUDY DESIGN: Ex vivo randomized blinded computed tomographic angiographic study. SAMPLE POPULATION: Fifteen pelvic limbs from eight greyhound cadavers. METHODS: The femoral artery and vein were cannulated and injected with 10 mL of iohexol. Each limb was placed in lateral recumbency on an acrylic sheet with predrawn femoral and tibial lines representing angles of stifle extension. Computed tomography was performed before (limbs 1-15) and after (limbs 10-15) CCL transection. The shortest distance between the cranial tibial artery and proximal tibia (dCrTA-PT) was measured at a distance of one patellar length from medial intercondylar tubercle. RESULTS: Median dCrTA-PT in intact specimens at 70°, 90°, 110°, and 135° was 2.04, 2.05, 2.28, and 2.51 mm, respectively (P = .008). Pairwise comparisons identified a difference between 70° and 135° (P = .007). Mean dCrTA-PT in transected specimens at 70°, 90°, 110°, and 135° was 2.60, 2.57, 2.90, and 2.79 mm, respectively (P = .208). Median overall dCrTA-PT was 2.24 mm in intact specimens (limbs 1-15, all four angles of extension combined) and 2.76 mm in transected specimens (limbs 10-15, all angles combined; P = .01). CONCLUSION: Flexion of the stifle resulted in a negligible decrease in dCrTA-PT in intact specimens but had no effect in CCL transected stifles. CLINICAL SIGNIFICANCE: The angle of stifle extension does not appear to have any clinically significant effect on the proximity of cranial tibial artery to the proximal tibia.

Computed Tomographic Assessment of Block Recession Trochleoplasty and Partial Parasagittal Patellectomy in Cats.

OBJECTIVE: The aim of this study was to assess computed tomography (CT) images of cadaveric feline stifles and record the relationship between the patella and femoral trochlea in normal stifles; then to investigate the effect of block recession trochleoplasty (BRT) with and without partial parasagittal patellectomy (PPP) on patellofemoral contact, depth of patellar recession and size of trochlea and patella. MATERIALS AND METHODS: The sample population included six cat cadavers (12 stifles). Preoperative CT scans with stifles in three positions: extended (155-165°), neutral (85-95°) and flexed (35-45°). Lateral stifle arthrotomy was followed by BRT. CT scans were taken as above. PPP was performed so the width of the patella was 1 mm narrower than the BRT. CT scans were repeated and CT measurements were taken. RESULTS: The area of contact between the patella and femoral trochlea was significantly reduced after BRT and then significantly increased after PPP. The depth of patellar recession was unchanged after BRT, but then was significantly higher after PPP. The patella was wider than the trochlea preoperatively and post-BRT and narrower post-PPP. Reduction in bone volume following PPP (mean: 20%) was 50% the reduction in patella width (mean: 40%). CONCLUSION: Block recession trochleoplasty did not improve patellar recession and decreased patellofemoral contact area. Following BRT, the patella rides the trochlear ridges and loses contact with the trochlear sulcus. Block recession trochleoplasty alone should not be performed in cats. Instead, BRT should be combined with PPP.

Biological response to an experimental implant for tibial tuberosity advancement in dogs: A pre-clinical study.

In this study, we propose a novel bioresorbable bioactive implant for tibial tuberosity advancement (TTA). The implant consists of a gradually resorbing load-bearing shell which encompasses rapidly resorbing small casings loaded with silica-based bioactive glass (BG) particulates which promote bone formation and reduce the risk of infection. The shell and the casings are manufactured by 3D printing from two medical grade bioresorbable polymers (a polyglycolide/lactide based and a polydioxanone based) that have different degradation rates. The casings are expected to resorb within days after surgery to expose the BG particulates while the shell would retain the load-bearing properties of the implant for the time required by bone healing. Unlike the currently used metallic devices, the novel implant is resorbed and excreted from the body once its purpose is fulfilled. This study presents a logical progression from the in vitro characterisation of the materials and implants to the in vivo investigation of the experimental implants. This included mechanical testing of the materials, finite element analysis of a preliminary design of the novel TTA implant, assessment of the degradation behaviour of the polymers and the ion exchange of BG in simulated body fluid, and investigation of the biological response to the novel implants after implantation in rabbits. The osteointegration of the novel implants was comparable to the osteointegration of Ti6Al4V implants in the control group; the biological efficacy and safety were confirmed. The biological response was in line with the expectations. The proof of concept for the novel TTA implants was demonstrated.

Lateral Radial Head Subluxation as a Complication Following Proximal Ulnar Osteotomy or Ostectomy in Eight Dogs.

OBJECTIVES: The aim of this study was to report the complication of lateral radial head subluxation following proximal ulnar osteotomy (PUOO) or proximal ulnar ostectomy (PUOE) in eight dogs. MATERIALS AND METHODS: Case records and diagnostic imaging of dogs developing lateral radial head subluxation following PUOO (n = 7) or PUOE (n = 2) were retrospectively reviewed. Information pertaining to clinical history, signalment, presenting condition, lameness grade, diagnostic imaging and initial surgery details, postoperative complications and their management were retrieved. Outcomes were established from subsequent clinical histories or telephone interviews with referring veterinarians. Comparison was made to a single-centre cohort without lateral radial head subluxation following PUOO or PUOE. RESULTS: Eight dogs (median age: 9.5 months [range: 6 months-6 years], median weight 7.7 kg [range: 5-28 kg]) were included. Six dogs had a PUOO performed; five dogs had unilateral surgery and one had bilateral surgery. Two dogs had unilateral PUOE surgery. Median time to diagnosis of lateral radial head subluxation following surgery was 6.5 weeks (range: 2-20 weeks). Five of the eight dogs had surgical revision of lateral radial head subluxation. Resolution of lateral radial head subluxation was achieved in four dogs, with three achieving acceptable to good mobility. One dog had poor postoperative mobility. A fifth dog remained lame after revision surgery failure. Three dogs did not have revision surgery; two underwent limb amputation and one dog remained lame as revision surgery was declined. CLINICAL SIGNIFICANCE: Lateral radial head subluxation is a potentially severe postoperative complication following PUOO or PUOE.

Evaluation of variables influencing success and complication rates in canine total hip replacement: results from the British Veterinary Orthopaedic Association Canine Hip Registry (collation of data: 2010-2012).

The objective of this study was to assess the variables associated with complications of total hip replacement (THR) and report owner-assessed outcomes. Entries into the British Veterinary Orthopaedic Association-Canine Hip Registry (BVOA-CHR) between September 2011 and December 2012 were reviewed separately and in conjunction with previous data (January 2010-August 2011). An outcomes assessment questionnaire was used to collect data from owners. Incidences of surgeon-reported and owner-reported complications were 8.2 per cent and 4.3 per cent, respectively. THR using the BioMedtrix BFX cup/stem prosthesis had a greater incidence of complications compared with THR using the BioMedtrix CFX cup/stem prosthesis (P=0.002); complications were 4.48 times more likely when using the BioMedtrix BFX cup/stem prosthesis versus the BioMedtrix CFX cup/stem prosthesis. THR using the BioMedtrix BFX cup/stem prosthesis had a higher incidence of complications compared with THR using a hybrid prosthesis (BioMedtrix BFX cup/CFX stem, BioMedtrix CFX cup/BFX stem) (P=0.046); complications were 2.85 times more likely when using the BioMedtrix BFX cup/stem prosthesis versus a hybrid prosthesis. In 95 per cent of cases, owner satisfaction with the outcome of THR was 'very good' or 'good'. Complication rates from the BVOA-CHR are similar to previous studies. The data suggest that prosthesis type is associated with complication rate, with BioMedtrix BFX (circa 2012) having a high short-term complication rate.

Can a surgeon drill accurately at a specified angle?

OBJECTIVES: To investigate whether a surgeon can drill accurately a specified angle and whether surgeon experience, task repetition, drill bit size and perceived difficulty influence drilling angle accuracy. METHODS: The sample population consisted of final-year students (n=25), non-specialist veterinarians (n=22) and board-certified orthopaedic surgeons (n=8). Each participant drilled a hole twice in a horizontal oak plank at 30°, 45°, 60°, 80°, 85° and 90° angles with either a 2.5  or a 3.5 mm drill bit. Participants then rated the perceived difficulty to drill each angle. The true angle of each hole was measured using a digital goniometer. RESULTS: Greater drilling accuracy was achieved at angles closer to 90°. An error of ≤±4° was achieved by 84.5 per cent of participants drilling a 90° angle compared with approximately 20 per cent of participants drilling a 30-45° angle. There was no effect of surgeon experience, task repetition or drill bit size on the mean error for intended versus achieved angle. Increased perception of difficulty was associated with the more acute angles and decreased accuracy, but not experience level. CLINICAL SIGNIFICANCE: This study shows that surgeon ability to drill accurately (within ±4° error) is limited, particularly at angles ≤60°. In situations where drill angle is critical, use of computer-assisted navigation or custom-made drill guides may be preferable.

Effect of fixation method on postoperative complication rates after surgical stabilization of lateral humeral condylar fractures in dogs.

OBJECTIVES: To assess the impact of stabilization method on the complication rate after lateral humeral condylar fracture (LHCF) repair. STUDY DESIGN: Retrospective multicenter clinical cohort study. ANIMALS: Dogs (n = 151) with LHCF. METHODS: Medical records (2004-2012) were reviewed for dogs that had surgical repair of LHCF. Data retrieved included signalment, cause of fracture, evidence of incomplete ossification of the humeral condyle, occurrence of postoperative complications, presence of supracondylar comminution preoperatively, and persistence of an intracondylar fissure postoperatively. Outcome was assessed based on the most recent data available and graded as excellent, good, fair, or poor. RESULTS: LHCF (n = 135) were evaluated in 132 dogs; 61 fractures were stabilized using a transcondylar screw and supracondylar K-wire, 13 using a transcondylar screw and supracondylar screw, and 61 using a transcondylar screw and lateral epicondylar plate. Major complications were significantly (P = .01) more common after stabilization using a transcondylar screw and supracondylar K-wire (28%) than in dogs where a supracondylar screw or lateral epicondylar plate were used (11%). Cases that had postoperative complications were significantly (P = .02) more likely to have a poor outcome. CONCLUSIONS: LHCF stabilized using a transcondylar screw and supracondylar K-wire are more likely to have major complications resulting in a poorer outcome than cases stabilized using a supracondylar screw or lateral epicondylar plate.

Clinical comparison of the hybrid dynamic compression plate and the castless plate for pancarpal arthrodesis in 219 dogs.

OBJECTIVE: To describe and compare a large population of dogs that had pancarpal arthrodesis (PCA) using either a hybrid dynamic compression plate (HDCP) or a CastLess Plate (CLP). STUDY DESIGN: Multicenter, retrospective, cohort study. ANIMALS: Dogs (n = 240; 261 PCA). METHODS: Medical records (2000-2012) from 12 UK orthopedic centers were reviewed for dogs that had PCA to document signalment, diagnosis, arthrodesis method, and complication rates. Follow-up data were used to compare outcome (lameness evaluation and radiographic healing) after use of HDCP and CLP plates. RESULTS: PCA was performed with HDCP in 125 cases, CLP in 105, and by other techniques in 31. Carpal hyperextension injury was the most common diagnosis in HDCP and CLP groups. Surgical site infection (18.3%) was the most common postoperative complication. There was no difference in intra- (11% HDCP, 21% CLP) or postoperative (34% HDCP, 41% CLP) complication rates. Use of external coaptation did not affect postoperative complication rates or outcome. External coaptation related complications occurred in 32% HDCP and 18% CLP (P = .02). At median follow-up, most dogs were classified as having no or mild lameness (73% HDCP, 83% CLP) and there was radiographic healing in 40% HDCP and 46% CLP (P = .8) cases. CONCLUSIONS: CLP and HDCP may both be used successfully to achieve pancarpal arthrodesis. Adjunctive external coaptation does not appear to have a measurable clinical benefit but is associated with morbidity.

Complications associated with corrective surgery for patellar luxation in 85 feline surgical cases.

The objective was to review surgical techniques and postoperative complications of surgical correction for patellar luxation (PL) in cats. A retrospective study evaluating 85 surgeries in 71 cats was performed. The records from four referral centres were searched for cats with surgical management of PL. Signalment, history, PL grade and direction, corrective surgical techniques and outcome were retrieved. Binary logistic regression analysis was used to interrogate relationships between case features, surgical correction methods and outcomes. The outcomes were classified as minor and major complications (requiring revision surgery), including continued PL (reluxation). Postoperative complications occurred in 26% of cases; 20% had major complications, including 5% patellar reluxation, and 6% had minor complications. Cats with previous ipsilateral femoral fracture were significantly more likely to suffer complications, including minor (P = 0.02, odds ratio = 12.67), major (P = 0.03, OR = 7.2) and patellar reluxation (P = 0.01, OR = 19.25). Minor complications were significantly more likely with grade 4 PL (P = 0.03, OR = 8.5). Major complications were significantly more likely with tibial tuberosity transposition (TTT; P = 0.03, OR = 5.57). Patellar reluxation was significantly more likely if stifle surgery had been performed previously (P = 0.05, OR = 8.00). The presence of bilateral PL, hip dysplasia, grade 1, 2 or 3 PL, corrective surgery using an anti-rotational suture or femoral sulcoplasty did not influence complications. Complications were more likely for grade 4 PL, previous ipsilateral femoral fracture, if TTT was performed and for cases with previous stifle surgery. This information allows consideration of risks and complicating factors.

Partial parasagittal patellectomy: a novel method for augmenting surgical correction of patellar luxation in four cats.

We describe a novel surgical technique used to correct feline patellar luxation (PL) where abnormal patellar tracking persists despite conventional corrective surgery. An anatomical difference between feline and canine stifles is that the feline patella is wider relative to the trochlear sulcus. This results in less constrained patellar tracking. Therefore, patellar subluxation is common in normal cats. It was noticed that in some feline cases with clinically significant PL, PL persisted intraoperatively despite performing the standard corrective procedures. We report a novel surgical technique - partial parasagittal patellectomy - to address the wide shape of the feline patella relative to the sulcus. This technique has been successfully performed in four cats with good outcomes. However, the immediate risks and long-term effects of partial parasaggital patellectomy are not known. We reserve this technique for surgical cases where PL cannot be controlled by conventional means.

Effect of neutering and breed on femoral and tibial physeal closure times in male and female domestic cats.

The timing of physeal closure is dependent upon many factors, including gonadal steroids, and previous studies have shown that early neutering delays physeal closure. Pelvic and femoral radiographs of 808 cats were analysed and physes at the greater trochanter, proximal femur, distal femur and proximal tibia were recorded as being open or closed. Date of birth, gender, neuter status and breed of cases were recorded. Each physis was analysed individually at a specific age. The number of male entire (ME), male neutered (MN), female entire (FE), female neutered (FN), pedigree and non-pedigree cases at each of these ages was recorded. The number of cases that were open or closed at each stated age were compared between the neutered and entire, the female and male, and the pedigree and non-pedigree groups using a Fischer's exact test, with P <0.05 being considered significant. Seven hundred and eighty-three radiographs were included: 359 MN, 95 ME, 237 FN and 92 FE. Ninety-six cats were pedigree and 687 were non-pedigree. A statistically significant effect was shown with physes closing later in MN than in ME cats for the greater trochanter (P = 0.0037), distal femur (P = 0.0205) and tibial tuberosity (P = 0.0003). No effect was shown for the proximal tibial or proximal femoral physes, nor for any physis when comparing FE with FN cats. No statistically significant effect of breed or sex was noted. Physeal closure will occur later in MN cats than in ME cats for the greater trochanteric, distal femoral and tibial tuberosity physes, and the potential clinical consequences of this should be evaluated further.

A case of scapular avulsion with concomitant scapular fracture in a cat.

An 11-year-old cat was referred following vehicular trauma for evaluation and treatment of right thoracic limb lameness which was non-responsive to conservative management. Gait assessment revealed a severe weight-bearing right thoracic limb lameness, soft tissue swelling over the dorsal border of the scapula, crepitus upon direct palpation over the scapula and lateralisation of the scapula upon adduction of the distal limb allowing a diagnosis of scapular avulsion to be made. Computed tomography (CT) demonstrated a comminuted fracture of the right scapula and a tear of the serratus ventralis muscle. The scapular fractures involved the caudal scapular angle and therefore a circumcostal suture was not placed. Stabilisation was achieved through reattachment of the scapula to the serratus ventralis muscle with sutures placed through small holes in the dorsal and cranial borders of the scapula. Follow-up revealed resolution of lameness at 14 weeks postoperatively but non-union of the scapular fractures as evidenced by repeat CT. This case report details the medium-term outcome following this very unusual injury and contributes to the sparse literature regarding the progression of conservatively managed scapular fractures. It demonstrates that full return to function can occur following this injury even when radiographic union of the fracture is not achieved. To our knowledge this is the first report of this specific combination of injuries detailed with medium-term and advanced imaging follow-up.

Complications and owner assessment of canine total hip replacement: a multicenter internet based survey.

OBJECTIVE: To assess the variables associated with the complications of total hip replacement (THR) and report owner-assessed outcomes, through surgeon-based registration of cases via an online database, informed owner consent, and prospective outcomes assessment using a client-administered clinical metrology instrument. STUDY DESIGN: Prospective case series ANIMALS: Dogs (n = 170) METHODS: Entries into the British Veterinary Orthopaedic Association-Canine Hip Registry (BVOA-CHR) between January 2010 and August 2011 were reviewed. Variables evaluated included dog age, body weight, breed, and indication for THR and prosthesis. Associations between each variable and the incidence of complications were assessed using logistic regression. Additionally, an on-line, owner-administered outcomes assessment questionnaire (modified from the Liverpool Osteoarthritis in Dogs (LOAD) questionnaire) was used to collect data from owners. RESULTS: One hundred and seventy cases met the inclusion criteria. Surgical indications included hip dysplasia and coxofemoral osteoarthritis (n = 150), Legg-Calves-Perthes disease (7), coxofemoral luxation (6), fracture (4), slipped capital physis (2), and femoral head and neck ostectomy revision (1). Surgical implants were from 4 systems. The incidence of surgeon-reported complication was 9.4%. No significant association was identified between weight, age, sex, breed, indication for THR, surgical technique and prosthesis, and the incidence of complications. In 82% of the cases, owners described their satisfaction with the outcome of THR as "very good" and a total of 20% complication rate was reported. There was a statistically significant improvement in owner-assessed questionnaire score before and after THR (P < .001). CONCLUSIONS: The BVOA-CHR offers a novel framework for the prospective studies on THR and on a national/international scale. Initial complication rates from the BVOA-CHR are similar to previous studies.

A biomechanical evaluation of a Hybrid Dynamic Compression Plate and a CastLess Arthrodesis Plate for pancarpal arthrodesis in dogs.

OBJECTIVE: To determine mechanical differences between two plates with different requirements for supplementary casting after pancarpal arthrodesis (PCA): the Veterinary Instrumentation Hybrid Dynamic Compression Plate (HDCP), and the OrthoMed CastLess Arthrodesis Plate (CLP). STUDY DESIGN: In vitro mechanical analysis. SAMPLE POPULATION: HDCP(n = 10), CLP(10). METHODS: Single-cycle load to failure using a materials-testing machine and cyclic loading between 38 and 380 N ± 5% to simulate estimated in vivo loads until failure or 10(6) cycles. RESULTS: Single-cycle to failure: bending stiffness was significantly higher for the HDCP(2269 ± 175 N/mm) than CLP(1754 ± 88 N/mm; P < .001). Bending structural stiffness was higher for the HDCP(3.8 ± 0.3 Nm(2) ) versus CLP(2.9 ± 0.2 Nm(2) ; P= .0022). A difference between the 2 plates for bending strength was not demonstrated; HDCP= 13.9 ± 1.4 Nm, CLP13.2 ± 0.5 Nm (P= .24). Cyclic Loading: no failures occurred with either plate type when plates were cycled to 10(6) cycles. CONCLUSION: There is no mechanical advantage in bending resistance afforded by the CLPover the HDCP. Fatigue failure of either plate during the convalescent period of an estimated 150,000-250,000 cycles is unlikely. Based on the bending performance, there is no evidence to support the use of the CLPover the HDCPfor castless PCA.

Osteosarcoma of the tibia 6 years after tibial plateau leveling osteotomy.

A 7 yr old spayed female mastiff presented for examination of a left pelvic limb lameness of 3 mo duration. Six years previously, the dog had undergone tibial plateau leveling osteotomy (TPLO) surgery of the left pelvic limb for the treatment of cranial cruciate disease. On presentation, the dog had a painful and swollen proximal tibia. Following investigation, a diagnosis of osteosarcoma of the proximal left tibia at the site of the previous TPLO surgery was made. This is the first reported case of osteosarcoma following TPLO using an implant other than the Slocum plate.

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.