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.

Evaluation of the use of intra-operative radiology for open placement of lag screws for the stabilization of sacroiliac luxation in cats.

OBJECTIVES: To assess the effect of intra-operative radiology on the quality of lag screw insertion for the management of sacroiliac joint luxations in cats. METHODS: In this retrospective single-centre study, the surgical, anaesthetic and imaging records of 40 screws (32 cats) placed with lag effect for management of sacroiliac luxation were reviewed. Postoperative radiographs were assessed for sacroiliac joint reduction, screw position, and sacral width purchased by each screw. Cases were divided into two groups according to the use of (IOR) or the absence of intra-operative radiology (NIOR). RESULTS: A total of 23 lag screws were placed with the aid of intra-operative radiology and 17 without. Three of the 23 screws placed in the IOR group exited the sacrum as opposed to eight of 17 screws in the NIOR group (p = 0.03). Mean sacral width purchased by the screws in the IOR group (70.8%) was also significantly higher (p = 0.002) than in the NIOR group (54.6%). Mean general anaesthetic times for unilateral and bilateral screw placement for the IOR group and NIOR group were not significantly different. CLINICAL SIGNIFICANCE: The use of intra-operative radiology can significantly improve the quality of lag screw insertion for the stabilization of sacroiliac luxations in cats, which should lead to a reduced incidence of postoperative screw loosening.

Radiographic, Surgeon and Owner Assessment of the BioMedtrix TATE(®) Elbow Arthroplasty.

OBJECTIVE: To report the long-term radiographic and clinical outcome of the BioMedtrix TATE elbow arthroplasty system in dogs. Assessment was via radiographs, a surgeon-based questionnaire, and owner assessment of outcome using the Liverpool osteoarthritis in dogs (LOAD) and canine brief pain inventory (CBPI) questionnaires. STUDY DESIGN: Retrospective multicenter, case series. ANIMALS: Client-owned dogs undergoing TATE elbow arthroplasty. METHODS: Questionnaires were distributed to surgeons in the United Kingdom performing TATE elbow arthroplasty and to the owners of the dogs operated on. Owners completed the LOAD and CBPI questionnaires. All completed questionnaires from surgeons and owners, and radiographs of the dogs were collated and analyzed. RESULTS: Surgeon questionnaires and radiographs were obtained for 33 elbows from 32 dogs, with owner questionnaires obtained for 19 dogs. Perioperative, short-term, and mid-term complication rates were 60%, 15%, and 15%, respectively. Radiographic assessment of component alignment showed 62% of cartridges were valgus or varus malaligned and 56% of cartridges were either translated medially or laterally relative to the long axis of the ulnar. There was no significant association between component alignment and final clinical outcome. Surgeon assessment reported 24% of dogs to have full, 52% acceptable, and 24% unacceptable outcome. Owner assessment showed significant decreases in pain severity and pain interference from preoperative to final status but no change in mobility scores. CONCLUSIONS: A high complication rate and variability in component placement was recorded with TATE athroplasty. However, component malalignment did not negatively impact clinical outcome. Final clinical outcome was favorable for most cases with significant reductions in pain severity and interference scores despite no changes in mobility scores.

Teaching examples for the design of experiments: geographical sensitivity and the self-fulfilling prophecy.

Many scientists believe that small experiments, guided by scientific intuition, are simpler and more efficient than design of experiments. This belief is strong and persists even in the face of data demonstrating that it is clearly wrong. In this paper, we present two powerful teaching examples illustrating the dangers of small experiments guided by scientific intuition. We describe two, simple, two-dimensional spaces. These two spaces give rise to, and at the same time appear to generate supporting data for, scientific intuitions that are deeply flawed or wholly incorrect. We find these spaces useful in unfreezing scientific thinking and challenging the misplaced confidence in scientific intuition.

Lost in space: design of experiments and scientific exploration in a Hogarth Universe.

A Hogarth, or 'wicked', universe is an irregular environment generating data to support erroneous beliefs. Here, we argue that development scientists often work in such a universe. We demonstrate that exploring these multidimensional spaces using small experiments guided by scientific intuition alone, gives rise to an illusion of validity and a misplaced confidence in that scientific intuition. By contrast, design of experiments (DOE) permits the efficient mapping of such complex, multidimensional spaces. We describe simulation tools that enable research scientists to explore these spaces in relative safety.

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 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.

Inverse dynamics analysis evaluation of tibial tuberosity advancement for cranial cruciate ligament failure in dogs.

OBJECTIVE: To evaluate, using inverse dynamic analysis, the biomechanical outcome from tibial tuberosity advancement (TTA) surgery in dogs affected by unilateral cranial cruciate ligament failure (CCLF). STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n = 13) 11-20 months after surgery. METHODS: Kinematic and force data were collected from 13 dogs 11-20 months after TTA and inverse dynamics analysis of the dogs' pelvic limb mechanical function performed. Angle, moment, and power were calculated for each joint. Total support moment (TSM) was calculated. RESULTS: Six dogs were affected on the right side (Raff) and 7 on the left (Laff). Peak stifle flexor moment was significantly larger for the right stifle compared with the left in Laff dogs, but similar in Raff dogs. Peak stifle extensor moment was significantly larger for the left stifle compared with the right in Raff dogs, and was also larger for the left stifle compared with the right in Laff dogs. Stifle power in early stance was larger on the left in Raff dogs and significantly larger on the right in Laff dogs. TSM was larger on the right in Raff dogs and significantly larger on the right in Laff dogs. CONCLUSIONS: Affected limbs had a reduction in power of the stifle flexors. Irrespective of the side of CCLF, TSM was larger on the right side and the stifle extensor moment in late stance was larger on the left, perhaps indicating a mechanical limb dominance effect.

Conservative versus arthroscopic management for medial coronoid process disease in dogs: a prospective gait evaluation.

OBJECTIVE: To investigate, using objective gait analysis, the long-term outcome of dogs with medial coronoid process disease (MCPD) treated with conservative management (CM) versus arthroscopic treatment (AT). STUDY DESIGN: Prospective clinical trial. ANIMALS: Dogs (n = 20) with unilaterally confirmed MCPD. METHODS: Eleven dogs were treated arthroscopically with removal of coronoid fragments and burring of any associated chondromalacic cartridge and 9 dogs were managed conservatively. All dogs were administered a 6-week course of oral tepoxalin on enrollment. Inverse dynamics gait analysis was performed at initial presentation and at 4, 8, 26, and 52 weeks. The gait variables analyzed were elbow moment (EM), elbow power (EP), total support moment (TSM), and total support moment ratio (TSMR) as a measure of forelimb asymmetry. RESULTS: Affected peak EM increased from 0.58 to 0.76 Nm/kg in the AT dogs, and from 0.66 to 0.81 Nm/kg in the CM dogs and there was no significant difference between groups. Affected peak EP increased marginally in the AT dogs, but was unchanged in the CM dogs and there was no significant difference between groups. TSM increased from 1.49 to 1.92 Nm/kg in the AT dogs and from 1.52 to 2.06 Nm/kg in the CM dogs and there was no significant difference between groups. TSMR was statistically different between treatment groups at 1 (P = .003) and 2 months (P = .048) with the AT group more asymmetric and hence more lame. TSMR at 12 months was 0.83 (AT) and 0.86 (CM) implying a failure of return to soundness by either group. CONCLUSIONS: AT dogs had increased mechanical asymmetry at 4 and 8 weeks compared to the CM group revealing surgery worsened limb function. There was no significant difference in mechanical symmetry between groups at 26 and 52 weeks.

Comparison of bone mineral density in medial coronoid processes of dogs with and without medial coronoid process fragmentation.

OBJECTIVE: To quantify bone mineral density (BMD) in the medial coronoid process (MCP) of dogs with and without fragmented medial coronoid processes (FMCPs) by use of dualenergy x-ray absorptiometry. SAMPLE POPULATION: 50 osteochondral samples from 31 dogs that underwent subtotal coronoid ostectomy for unilateral or bilateral FMCP and 10 control osteochondral samples of the MCP collected from forelimbs of 5 cadaveric Greyhounds. PROCEDURES: Each sample was mounted in proximodistal and mediolateral orientations for BMD determinations via dual-energy x-ray absorptiometry, and area-of-interest data (0.03-cm(2) increments) were obtained. Values of BMD were compared between left and right limb control samples, between control and FMCP samples, and between axial and abaxial regions of the control or FMCP samples. RESULTS: The BMD in control and FMCP samples in both proximodistal and mediolateral orientations differed significantly. Mean BMD throughout the MCP was decreased in FMCP samples, compared with control sample findings. In both control and FMCP samples, BMD of the abaxial half of the MCP was 50% higher than that of the axial portion. CONCLUSIONS AND CLINICAL RELEVANCE: The similar pattern of BMD in osteochondral samples of the MCP in dogs with and without FMCP indicated that the MCP was eccentrically loaded during weight bearing. Topographic variation in BMD in the MCP, and hence tolerance to compressive loading, suggested that the abaxial portion of the MCP in dogs was more resistant to compressive load than was the axial edge. This difference may predispose the coronoid process to microcrack formation and fragmentation at that juxtaposition.

Regional load bearing of the canine acetabulum.

OBJECTIVE: To determine the load bearing areas of the canine acetabulum. MATERIALS AND METHODS: A kinematic study of four healthy dogs was used to determine the orientation of the femur to the pelvis at mid-stance. Femora and pelves from 10 canine cadavers were loaded with the physiological canine hip reaction force and angle being replicated. Impression material placed within the acetabulum was extruded from areas of load bearing. Digital images before and after loading were used to assess if six different regions of the acetabulum were fully, partially or non-load bearing. RESULTS: All areas of the acetabulum were partially or fully load bearing. The cranial and caudal thirds of the acetabulum were 7.9 and 13.1 times more likely to be fully load bearing than the central third, respectively. There was a significant difference in load bearing between the axial, middle and abaxial thirds of the acetabulum in all tests, with the middle and abaxial thirds 72.4 and 351 times more likely to be fully load bearing than the axial third, respectively. CONCLUSION: The cranial and caudal thirds and the middle and abaxial thirds of the canine acetabulum are fully load bearing. CLINICAL RELEVANCE: The caudal third of the canine acetabulum is loaded and therefore recommendations that fractures in this area be managed conservatively need to be reconsidered.

Distribution of power across the hind limb joints in Labrador Retrievers and Greyhounds.

OBJECTIVE: To quantify angular excursions; net joint moments; and powers across the stifle, tarsal, and metatarsophalangeal (MTP) joints in Labrador Retrievers and Greyhounds and investigate differences in joint mechanics between these 2 breeds of dogs. ANIMALS: 12 clinically normal dogs (6 Greyhounds and 6 Labrador Retrievers) with no history of hind limb lameness. PROCEDURE: Small retroreflective markers were applied to the skin over the pelvic limb joints, and a 4-camera kinematic system captured data at 200 Hz in tandem with force platform data while the dogs trotted on a runway. Breed-specific morphometric data were combined with kinematic and force data in an inverse-dynamics solution for stance-phase net joint moments and powers at the stifle, tarsal, and MTP joints. RESULTS: There were gross differences in kinematic patterns between Greyhounds and Labradors. At the stifle and tarsal joints, moment and power patterns were similar in shape, but amplitudes were larger for the Greyhounds. The MTP joint was a net absorber of energy, and this was greater in the Greyhounds. Greyhounds had a positive phase across the stifle, tarsal, and MTP joints at the end of stance for an active push-off, whereas for the Labrador Retrievers, the only positive phase was across the tarsus, and this was small, compared with values for the Greyhounds. CONCLUSIONS AND CLINICAL RELEVANCE: Gross differences in pelvic limb mechanics are evident between Greyhounds and Labrador Retrievers. Joint kinetics in specific dogs should be compared against breed-specific patterns.

Biomechanical and clinical evaluation of a modified 3-loop pulley suture pattern for reattachment of canine tendons to bone.

OBJECTIVE: To describe a modified 3-loop pulley suture pattern for the reattachment of canine tendons to bone along with a biomechanical comparison with the locking-loop suture. STUDY DESIGN: In vitro biomechanical study and clinical case report. ANIMALS OR SAMPLE POPULATION: Biomechanical study: 10 paired gastrocnemius tendons and calcaneii harvested from 5 canine cadavers. CASE REPORT: a Doberman with avulsion of the gastrocnemius tendon of insertion. METHODS: Biomechanical study: paired tendons were reattached to the calcaneus with either a modified 3-loop pulley pattern or a locking-loop pattern. Tensile loading to failure was performed. A direct, non-contact, method of gap measurement, using digital video, was used to measure gap formation. Load required to initiate gap formation (defined as load at a 1 mm gap) and to produce a 3 mm gap was evaluated in addition to maximum load and gap at failure. RESULTS: Mean (+/-SEM) 1 mm gap loads were 31.0+/-4.2 and 17.2+/-2.5 N, mean 3 mm gap loads were 49.1+/-2.4 and 28.9+/-3.2 N, and mean maximum loads were 72.9+/-4.3 and 55.8+/-2.2 N for the modified 3-loop pulley suture and the locking-loop suture, respectively. These differences were statistically significant (P<.05). The gap at failure was similar for both repairs. The clinical case remained sound 7 months postoperatively. CONCLUSIONS: A modified 3-loop pulley pattern is biomechanically superior to a locking-loop pattern for reattachment of the canine gastrocnemius tendon to bone and may be suitable for clinical use. CLINICAL RELEVANCE: Tendon repairs with a gap >3 mm are reported to be at increased risk of rupture during the first 6 weeks postoperatively. A modified 3-loop pulley pattern resists gap formation better than a locking-loop pattern.

The three-loop pulley suture versus two locking-loop sutures for the repair of canine achilles tendons.

OBJECTIVE: To compare a 3-loop pulley suture pattern with 2 locking-loop sutures for the repair of components of the canine Achilles mechanism. STUDY DESIGN: In vitro biomechanical study. ANIMALS: Forty-eight paired tendons collected from 9 canine cadavers. METHODS: Paired tendons were repaired with either a 3-loop pulley suture or 2 locking-loop sutures and tensile tested to failure. To ensure accurate anastomosis gap measurement a direct, non-contact, method of gap measurement, using digital video, was devised. Load initiating gap formation (defined as load at a 1 mm gap) and load producing a 3 mm gap were evaluated in addition to maximum load, gap at failure, mode of failure, and time spent placing the sutures. RESULTS: Maximum load values were similar for both repairs. The mean 1 mm gap loads were 44.0 and 18.4 N, and the mean 3 mm gap loads were 56.3 and 34.7 N, for the 3-loop pulley pattern and the 2 locking-loops, respectively; these differences were statistically significant. The 3-loop pulley pattern was faster to place and resulted in a smaller gap at failure. All but 2 repairs failed by suture pull out. CONCLUSIONS: The 3-loop pulley pattern is more resistant to gap formation during tensile loading, and is quicker to place, than 2 locking-loop sutures. CLINICAL RELEVANCE: Gap formation can significantly delay tendon healing. Tendon repairs with a gap >3 mm are reported to be at increased risk of rupture during the first 6 weeks postoperatively.