Ulnar Ostectomy Research Articles

Distal radial osteochondroma causing expansile lysis and ulna fracture in a dog.

To describe the diagnosis, management, and outcome of a dog with a right distal radial osteochondroma that penetrated the ulna, causing expansile lysis and fracture. A 9-month-old entire female German Shorthaired Pointer. The dog had a 2-month history of weight-bearing lameness of the right forelimb and a 2-week history of a progressively enlarging, firm swelling on the distolateral antebrachium. Computed tomography was used to characterize the lesion and for surgical planning. A distal ulnar ostectomy removed the affected ulnar segment, and the radial osteochondroma was excised with rongeurs. The dog was sound at 2, 16, and 45 weeks postoperatively. Radiographs at 45 weeks showed a persistent ulnar ostectomy gap with irregular but smoothly marginated edges and focal cortical irregularity at the site of radial osteochondroma excision. There was no evidence of osteochondroma recurrence. This is a newly recognized presentation of an osteochondroma penetrating the cortex of an adjacent bone in a dog resulting in expansile lysis and cortical fracture. Computed tomography was important in diagnosis and surgical planning, and surgical treatment was successful in removing the osteochondroma and ulnar lesion. This case provides long-term radiographic and clinical follow-up after osteochondroma excision and contributes to the current knowledge on prognosis following osteochondroma excision in dogs.

Comparison of reamer irrigator aspirator (RIA) suspension versus bone marrow aspirate concentrate (BMC) for percutaneous treatment of long bone nonunions—A preclinical canine model

ObjectiveTo compare the bone healing effects of percutaneously delivered bone marrow aspirate concentrate (BMC) versus reamer irrigator aspirator (RIA) suspension in a validated preclinical canine ulnar nonunion model. We hypothesized that BMC would be superior to RIA in inducing bone formation across a nonunion site after percutaneous application. The null hypothesis was that BMC and RIA would be equivalent. MethodsA bilateral ulnar nonunion model (n= 6; 3 matched pairs) was created. Eight weeks after segmental ulnar ostectomy, RIA from the ipsilateral femur and BMC from the proximal humerus were harvested and percutaneously administered into either the left or right ulnar defect. The same volume (3 ml) of RIA suspension and BMC were applied on each side. Eight weeks after treatment, the dogs were euthanized, and the nonunions were evaluated using radiographic, biomechanical, and histologic assessments. ResultsAll dogs survived for the intended study duration, formed radiographic nonunions 8 weeks after segmental ulnar ostectomy, and underwent the assigned percutaneous treatment. Radiographic and macroscopic assessments of bone healing at the defect sites revealed superior bridging-callous formation in BMC-treated nonunions. Histologic analyses revealed greater amount of bony bridging and callous formation in the BMC group. Biomechanical testing of the treated nonunions did not reveal any significant differences. ConclusionBone marrow aspirate concentrate (BMC) had important advantages over Reamer Irrigator Aspirator (RIA) suspension for percutaneous augmentation of bone healing in a validated preclinical canine ulnar nonunion model based on clinically relevant radiographic and histologic measures of bone formation.

Bilateral ulnar retained cartilage cores causing thoracic angular limb deformities in a cat

AbstractA 6‐month‐old, female, neutered, Bengal‐cross cat presented for bilateral thoracic angular limb deformity. Radiographs and computed tomography revealed well‐defined, flame‐shaped radiolucent and hypoattenuating defects within the medullary cavity of the distal ulnar metaphyses, surrounded by a thin rim of sclerosis. Surgical correction of initially the right angular limb deformity involved radial and ulnar ostectomies, and a bone biopsy of the distal ulnar metaphysis was submitted for histopathology. The morphological diagnosis was consistent with retained cartilage core, never previously reported in a cat.

Healing of Humeral Intracondylar Fissure Following Distal Ulnar Ostectomy to Treat Concurrent Elbow Joint Incongruity in a Dog

AbstractA 22-week-old female Labrador retriever presented with intermittent bilateral forelimb lameness. Computed tomography (CT) study interpretation revealed bilateral humeral intracondylar fissures (HIF) surrounded by sclerotic epiphyseal bone. Other changes included bilateral distal ulna retained cartilage core, secondary negative radioulnar incongruity (RUI), and medial coronoid process disease. The patient underwent bilateral dynamic distal ulnar ostectomies (DUO) in an attempt to address the elbow incongruity. Follow-up CT studies were performed at 2, 4, and 10 months postoperatively, which showed a bilateral improvement of elbow congruence and complete healing of HIF on the left side. The degree of congruence correction in the right elbow was possibly suboptimal, and following an initial improvement, a transcondylar screw was placed due to HIF progression.

Partial ulnar ostectomy, stereotactic body radiation therapy, and palliative radiation therapy as local limb sparing treatment modalities for ulnar tumors in dogs.

Information on dogs that undergo limb preserving local treatment for ulnar tumors is currently limited. To describe the clinical characteristics and outcomes in dogs that underwent partial ulnectomy or radiation therapy (RT) for ulnar bone tumors, and to evaluate potential risk factors for outcomes as well as pre-treatment factors for association with treatment modality selected. Forty client-owned dogs that underwent partial ulnectomy or RT for an ulnar tumor from July 2006 to July 2021. The medical records database from a single institution were retrospectively reviewed, and data were recorded and analyzed. Radiation therapy was performed in 24 dogs, with 12 stereotactic body RT (SBRT) and 12 palliative RT (PRT) plans, and partial ulnectomy was performed in 16 dogs. Biomechanical complications occurred in 6/12 (50%) dogs that underwent SBRT, 6/12 (50%) dogs that underwent PRT, and 3/16 (18.8%) dogs that underwent ulnectomy. The majority of dogs had a good functional outcome following partial ulnectomy, and no dogs required surgical stabilization of the carpus even with lateral styloid process excision. Pathologic fracture occurred in 4/12 (33.3%) dogs following SBRT and 5/12 (41.7%) dogs following PRT. Local progression or recurrence was documented in 5/12 (41.7%) dogs that underwent SBRT, 2/12 (16.7%) dogs that underwent PRT, and 2/16 (12.5%) dogs that underwent ulnectomy. The overall median survival time was 198 days, and factors that were significantly associated with improved survival time included adjuvant chemotherapy administration and partial ulnectomy as local treatment method for dogs that received chemotherapy. Both RT and ulnectomy were effective and well tolerated local treatment modalities for dogs with ulnar tumors.

Short term outcomes and complications of distal ulnar ostectomy in 23 juvenile dogs with carpal valgus secondary to discordant radial-ulnar physeal growth.

ObjectiveThe goal of this study was to report short term clinical and radiographic outcomes after distal ulnar ostectomy in dogs with carpal valgus due to discordant radial-ulnar growth.Study designRetrospective case study.Sample groupClient owned dogs under 1 year of age with carpal valgus and open distal radial physes pre-operatively.MethodsMedical records from four veterinary referral centers were searched from January 1, 2015 to January 1, 2022 for juvenile dogs that had been treated with distal ulnar ostectomy for carpal valgus due to premature closure of the distal ulnar physis. Patients were excluded if they were skeletally mature at the time of ostectomy; medical records were incomplete; radial physis was closed at surgery; or definitive corrective osteotomy was performed. Radiographs were evaluated pre-operatively and for short term follow up at ~8 weeks. Complications and short term clinical outcomes were evaluated also.Results31 limbs from 23 dogs were evaluated. Patients ranged from 4 to 10.8 months of age. All dogs presented for visible carpal valgus and varying degrees of thoracic limb lameness. Sixty-four percent of patients showed resolution of lameness while an additional 13% showed an improvement in clinical lameness without complete resolution. Complications were seen in 32% of patients with 70% percent of those being minor, bandage related complications. Radiographically, 38% of limbs showed bridging callus formation of the ostectomy at an average of 7.5 weeks post operatively and 75% percent of patients with elbow incongruity improved radiographically. There was no significant difference in radial joint angles pre-operatively and at the time of follow up.ConclusionDistal ulnar ostectomy ameliorates lameness in juvenile dogs with premature distal ulnar physeal closure and shows lack of progression of distal carpal valgus deformity, but does not improve joint angulation.Clinical significanceDistal ulnar ostectomy is associated with mild bandage-related complications and halting of progressive limb deformity within the time frame evaluated, and should therefore be considered a treatment for premature closure of the distal ulnar physis. It does not lead to deformity correction at 8 weeks following surgery but is associated with improved elbow congruity.

Clinical and Radiographic Evaluation of Short- and Long-Term Outcomes of Different Treatments Adopted for Elbow Medial Compartment Disease in Dogs.

Medial compartment disease is a common occurrence in dogs affected by elbow dysplasia. Despite many treatments suggested in the literature, only few studies reported comparative outcomes in the short and long term. The aim of this study is to report and compare short- and long-term clinical and radiographic outcomes of dogs treated for medial compartment disease (MCD) by distal dynamic ulnar ostectomy (DUO), bi-oblique dynamic proximal ulnar osteotomy (BODPUO) and conservative management (CM). From 2016 to 2018, all medium to large dogs, aged between 5 and 12 months, affected by uni/bilateral MCD and treated by DUO, BODPUO or CM, were enrolled in this study and followed up for 24 months. Orthopedic and radiographic examinations were performed at T0, T2, T12 and T24 months after treatment. Lameness score, elbow arthralgia, elbow range of motion (ROM), osteoarthritis (OA) score and percentage of ulnar subtrochlear sclerosis (%STS) were evaluated at each time point. According to the treatment performed, dogs were divided into three groups: DUO, BODPUO and CM. Forty-five elbows from twenty-six dogs, treated with DUO (n = 17), BODPUO (n = 17) or CM (n = 11), were prospectively enrolled in the study. The patients enrolled in the CM group were older and showed more severe radiographic signs of OA, compared to those enrolled in the other two groups. Lameness and arthralgia scores (p < 10−4) were significantly decreased in patients that underwent surgical treatment and increased in patients managed conservatively (lameness p < 10−4, arthralgia p = 0.3068), at T12 and T24. OA score (p < 0.0040) and ROM (DUO, CM p < 10−4; BODPUO p = 0.0740) worsened in every study group, but %STS decreased in DUO (p = 0.0108), increased in the CM group (p = 0.0025) and remained unchanged in the BODPUO group (p = 0.2740). This study supports the clinical efficacy of DUO and BODPUO in reducing lameness, arthralgia and progression of %STS. Early diagnosis and surgical attention in patients affected by MCD can improve the short- and long-term outcome and reduce the progression of secondary changes.

Treatment of Radius Curvus in a Young Dog with Association of Radial Physeal Stapling, Ulnar Ostectomy and Transarticular Dynamic External Fixator Techniques

Background: Radius curvus is a clinical manifestation of the premature closure of the distal ulnar physis and the most common physeal disease in dogs, representing 63% of all physeal injuries. There are few reports indicating the technique of stapling for treatment of radius curvus in squeletically immature dogs. The aim of this study is to report a case of radius curvus in a young dog successfully treated with a combination of 3 surgical tecniques: 1- Stapling the medial and cranial portions of the distal radial physis; 2- Oblique osteotomy of the proximal ulna and ostectomy of the distal ulna, and 3- Dynamic external skeletal fixation in the elbow joint.Case: A 5-month-old female dog was referred to the University Veterinary Hospital with a history of left thoracic limb deformity for 2 weeks. There was a history of possible traumatic event on the front limb, in addition to providing nutritional supplements daily. In the radiographic evaluation the changes were identified in the left thoracic limb: shortening of the ulna, procurvatum and medial angulation of the distal radius, increased joint space and articular incongruity of the elbow joint. The dog was subjected to surgical treatment by the combination of three main surgical techniques. For the stapling of the distal radial physis the surgical approach on the cranial-medial surface of the distal radius was made. Two surgical staples were positioned in the distal radial physis. Thereafter a caudal approach was made to the distal region of the ulnar diaphysis for the distal ostectomy of the ulna. A bone segment of 1 cm in length of the distal ulnar diaphysis was removed. Another caudal approach was made to the proximal region of the ulnar diaphysis and a proximal oblique osteotomy of the ulna was performed. For the dynamic external skeletal fixation in the elbow joint two Steinmann pins were inserted. The first pin was proximal to the supracondilar foramen of the humerus and the second pin was caudal to the trochlear notch of the ulna, both parallel to the joint surface. To create a dynamic system, the pin tips were connected with elastic rubber bands on the medial and lateral sides of the elbow joint. Clinical and radiographic revaluation were made at 15, 30 and 60 days after surgery. Total correction of the limb deviation was achieved at 60 days postoperative. Two years after the surgical procedure, the owner was contacted and reported that the dog was very well and with no change in the operated limb.Discussion: The most common cause of premature closure of the distal ulnar physis is trauma. Due to the proper conical shape of the distal ulnar physis, there is more predisposition to the compression of the germinative cells in traumatic events, leading to radius curvus disease. Another cause of the radius curvus is the nutritional disbalances. In the reported case the patient had both predisponent factors, although unilateral limb involvement suggested trauma with primary causative agent. The treatment included the interruption of the supplementation of the diet associated with surgical techniques. The stapling of the distal radial physis is usually indicated for mild angular valgus deviation. In the current case the technique was applied with success regardless of the higher grade of radial deviation. Generally, the ulnar ostectomy is preferred to the osteotomy, since it reduces the rate of ulnar osteosynthesis, ensuring that the restrictive effect of the ulna upon the radial growth does not restart. In the reported case the ulnar ostectomy was associated with ulnar osteotomy to achieve a more effective result. Furthermore, the proximal ulnar osteotomy is usually indicated when elbow subluxation is present. In the current case the joint congruence was improved with the use of the dynamic external skeletal fixator.

Antimicrobial prophylaxis is considered sufficient to preserve an acceptable surgical site infection rate in clean orthopaedic and neurosurgeries in dogs

BackgroundSurgical site infections (SSI) are associated with increased morbidity and mortality. To lower the incidence of SSI, antimicrobial prophylaxis is given 30–60 min before certain types of surgeries in both human and veterinary patients. However, due to the increasing concern of antimicrobial resistance, the benefit of antimicrobial prophylaxis in clean orthopaedic and neurosurgeries warrants investigation. The aims of this retrospective cross-sectional study were to review the rate of SSI and evaluate the compliance with antimicrobial guidelines in dogs at a veterinary teaching hospital in 2012–2016. In addition, possible risk factors for SSI were assessed.ResultsNearly all dogs (377/406; 92.9%) received antimicrobial prophylaxis. Twenty-nine dogs (7.1%) did not receive any antimicrobials and only four (1.1%) received postoperative antimicrobials. The compliance with in-house and national protocols was excellent regarding the choice of prophylactic antimicrobial (cefazolin), but there was room for improvement in the timing of prophylaxis administration. Follow-up data was available for 89.4% (363/406) of the dogs. Mean follow-up time was 464 days (range: 3–2600 days). The overall SSI rate was 6.3%: in orthopaedic surgeries it was 6.7%, and in neurosurgeries it was 4.2%. The lowest SSI rates (0%) were seen in extracapsular repair of cranial cruciate ligament rupture, ulnar ostectomy, femoral head and neck excision, arthrotomy and coxofemoral luxation repair. The highest SSI rate (25.0%) was seen in arthrodesis. Omission of antimicrobials did not increase the risk for SSI (P = 0.56; OR 1.7; CI95% 0.4–5.0). Several risk factors for SSI were identified, including methicillin-resistant Staphylococcus pseudintermedius carriage (P = 0.02; OR 9.0; CI95% 1.4–57.9) and higher body temperature (P = 0.03; OR 1.69; CI95% 1.0–2.7; mean difference + 0.4 °C compared to dogs without SSI).ConclusionsAntimicrobial prophylaxis without postoperative antimicrobials is sufficient to maintain the overall rate of SSI at a level similar to published data in canine clean orthopedic and neurosurgeries.

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

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. 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. 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. Lateral radial head subluxation is a potentially severe postoperative complication following PUOO or PUOE.

3505 Fracture Targeted Parathyroid Hormone Agonist As An Effective Pharmaceutical For Bone Repair in Mouse and Canine Models

OBJECTIVES/SPECIFIC AIMS: The primary objective of this study was to evaluate the performance of a bone fracture targeted systemically administrable bone anabolic as a potential therapeutic for bone fracture repair. Currently all bone fracture repair therapeutic require local administration during surgery. However, the population that need the most assistance in repair bone fractures are not eligible for surgery. So, it was our goal to design an inject-able therapeutic to assist in bone fracture repair to reduce the invasiveness. The injectable nature of it allows for repair administration of the bone anabolic and for therapeutic effect throughout the entire bone fracture healing process. Targeting it to the bone fracture site reduces the toxicity and increases the efficacy. METHODS/STUDY POPULATION: METHODS To achieve the above objective, a bone mineral-(hydroxyapatite-) targeting oligopeptide was conjugated to the non-signaling end of an engineered parathyroid hormone related protein fragment 1-46 with substitutions at Glu22,25, Leu23,28,31, Aib29, Lys26,30 (ePTHrP). The negatively charged oligopeptide has been shown to target raw hydroxyapatite with remarkable specificity, while the attached PTHrP has been demonstrated to induce sustained and accelerated bone growth under control of endogenous morphogenic regulatory factors. The conjugate’s specificity arises from the fact that raw hydroxyapatite is only exposed whenever a bone is fractured, surgically cut, grafted, or induced to undergo accelerated remodeling. The hydroxyapatite-targeted conjugate can therefore be administered systemically (i.e. without invasive surgery or localized injection) and still accumulate on the exposed hydroxyapatite at the fracture site where it accelerates the healing process Murine in vivo experiments were conducted on female Swiss Webster mice (10 per group). Femoral fractures were induced with a 3-point bending device and stabilized. Mice were dosed with 3 nmol/kg/d of targeted-ePTHrP, non-conjugated (free) ePTHrP, or saline. Following a 4-week study, fracture callus densities were measured using microCT. Canine in vivo experiments were conducted on 1-year-old male beagles. Beagles underwent a 10 mm bilateral ulnar ostectomy. Two dogs in the treatment group and Three dogs in the control group were dosed daily with either targeted-ePTHrP 0.5nmol/kg/d or saline respectively. Dogs were x-rayed weekly for the first 6 weeks and then every other week thereafter. One tailed ANOVA followed by Dunnett’s post-hoc test was used to establish significance. All animal experiments were conducted as described in approved IACUC protocols. P&lt;0.05 was considered significant. RESULTS/ANTICIPATED RESULTS: RESULTS SECTION: In the murine studies we observed a marked increase in fracture callus size and a 2-fold increase in bone deposition was observed in the targeted-ePTHrP group over the saline group (P&lt;0.01). A significant doubling in bone density was also observed. Targeted-ePTHrP group fractured femurs were able to achieve their pre-fracture strength as early as 3 weeks compared to 9 weeks in the saline mice representing a 66% reduction in healing time. In the canine studies, we observe a significantly higher closure of the ostectomy gap than saline controls (P&lt;0.05). In addition, no significant differences in weight are observed in the treatment vs. saline controls. No significant difference between the control group and treatment groups was found in a histological investigation of the organs. DISCUSSION/SIGNIFICANCE OF IMPACT: DISCUSSION: Although attempts have been made in developing a systemically administered fracture therapeutic for fracture repair, i.e. teriparatide, to date, no such anabolics have been approved for this use. In these studies there is evidence that anabolic activity was occurring at the fracture site, but at a level that did not meet FDA required end-points.2 It is plausible that if sufficient drug were to be delivered to a fracture site then improved fracture repair would be possible. In previous studies, we demonstrated fracture specific accumulation bone anabolics can be achieved by modifying the drug with acidic oligopeptides.3 Here, by modifying a safe, clinically proven, parathyroid hormone receptor agonist with an acidic oligopeptide we observe improved bone deposition and strength in mice. Furthermore, when administered to canine critical sized defect ostectomies, a more relevant and difficult model, we observe improved ostectomy closure. CLINICAL RELEVANCE:: The ability to accelerate bone fracture repair is a fundamental need that has not been addressed by conventional methods. By targeting bone anabolic agents to bone fractures, we can deliver sufficient concentrations of anabolic agent to the fracture site to accelerate healing, thus avoiding surgery and any ectopic bone growth associated with locally-applied bone anabolic agents.

Ulnar ostectomy decreases the stability of canine cadaver carpi as assessed with stress radiography.

Distal ulnar ostectomy may be performed palliatively in patients with distal ulnar osteosarcoma. Concurrent arthrodesis of the carpus has been proposed to counteract joint instability following transection of carpal ligaments associated with removal of the distal ulna. The objective of this prospective one group pretest, posttest study was to assess stability of the carpus following distal ulnar ostectomy using pre- and postoperative stress radiographic views in a group of canine cadaver limbs. Seven thoracic limbs from six canine cadavers weighing more than 20kg were obtained. Lateral and dorsopalmar, extended lateral, medial stress, and lateral stress radiographs were made before and after distal ulnar ostectomy. Presurgical canine cadaver carpal angle measurements were as follows (mean ± standard deviation): extension 205.9° ± 5.4; medial stress 25.1° ± 5.7; and lateral stress 13.3° ± 5.2°. Cadaver limb joint angles exceeded those previously reported in live dogs. A significant increase in carpal angle was noted following ulnar ostectomy. The mean increases in carpal angle were as follows: (mean ± standard deviation (95% confidence interval)): extension 6.2° ± 4.9 (2.6-9.8) (P=0.007); medial stress 3.2° ± 3.0 (1.0-5.5) (P=0.015); lateral stress 6.2° ± 5.2 (2.4-10.1) (P=0.010). Findings from this cadaver study support the use of supplementary stabilization for clinical patients undergoing distal ulnar ostectomy. Future studies are needed in clinical patients to evaluate changes in limb positioning and gait associated with distal ulnar ostectomy.

Bilateral Radial Agenesis in a Cat Treated with Bilateral Ulnocarpal Arthrodesis

This article describes corrective antebrachiocarpal re-alignment and arthrodesis for bilateral radial hemimelia (radial agenesis) in an 8-month-old domestic short-haired cat. Bilateral forelimb deformity of ulnocarpal varus with complete luxation and rotation of the antebrachiocarpal joint spaces, and joint contracture, was observed. Several carpal bones and metacarpal bones I and II and their associated phalanges were absent. Abnormal ambulation and weight bearing on the dorsolateral part of the manus were present. The deformities were treated by bilateral distal ulnar ostectomy and ulnocarpal arthrodesis using a 2.0-mm locking compression plate applied with hybrid fixation and allograft. Successful deformity correction was obtained with subsequent fusion of the antebrachiocarpal joints. No complications were observed. At long-term follow-up (4.75 years), there was good-to-excellent functional result, with approximately 15° internal rotation of the right forelimb manus and shortened stride with slight circumduction and lameness. All implants remained stable and continued bone remodelling was present. The cat was assessed to have good-to-excellent short- and long-term functional results with excellent owner satisfaction. Treatment of radial agenesis in the cat has previously been limited to conservative management or limb amputation. While there are several reports of corrective limb-sparing procedures used to treat dogs, this is the first report of a cat with successful salvage corrective surgery.

Effect of distal ulnar ostectomy on carpal joint stability during weight bearing in the dog.

To assess the influence of a 50% distal ulnectomy on mediolateral carpal stability in the dog. Canine cadaveric study. Seven canine thoracic limbs METHODS: Thoracic limbs were placed in a jig to mimic weight bearing with a load representing 30% of body weight. Carpal extension angle was standardized at 190° ± 5°. Frontal plane carpal angles were measured with the limb loaded on craniocaudal radiographs before and after ulnectomy. Valgus and varus stress radiographs with the limb loaded were acquired before and after ulnectomy. The limbs were palpated and were subjectively graded for valgus or varus instability by 2 investigators before and after ulnectomy. Mean (±SD) valgus angulation increased after ulnectomy (2.1° ± 1.7°; P = .017; CI95 = 0.5°-3.7°) when the limb was loaded without valgus or varus stress applied. Mean valgus angulation increased after ulnectomy (2.7° ± 2.8°; P = .032; CI95 = -0.2°-5.5°) when valgus stress was applied to the loaded limb. Varus angulation was unchanged after ulnectomy (0.6° ± 4.6°; P = .383; CI95 = -4.2°-5.3°) when varus stress was applied to the loaded limb. Palpation detected increased valgus score after ulnectomy. Distal ulnectomy with excision of the lateral styloid process induces a slight increase in valgus in canine cadaver carpi. The clinical consequences of that valgus on carpal function and health should be assessed in clinical patients.

The effect of lysophosphatidic acid using a hydrogel or collagen sponge carrier on bone healing in dogs.

The purposes of this study were to determine: 1) the efficacy of polycaprolactone-g-polyethylene glycol (PCL-g-PEG) and polylactic-co-glycolic acid (PLGA-g-PEG) hydrogels and an absorbable collagen sponge (ACS) as carriers for lysophosphatidic acid (LPA), 2) the effect of LPA on bone healing in dogs, and 3) the ideal dose of LPA to maximally stimulate bone healing. Bilateral ulnar ostectomies were performed on purpose bred dogs. Control defects were filled with a PCL-g-PEG or PLGA-g-PEG hydrogel, or a saline soaked ACS. Contralateral defects were filled with a PCL-g-PEG or PLGA-g-PEG hydrogel, or an ACS with each carrying differing concentrations of an LPA solution. Dual-energy X-ray absorptiometry (DXA) was performed. Total bone area (TBA), mineral density (BMD), and mineral content (BMC) were determined at each time point. Relationships between the effect of treatment over time on TBA, BMC and BMD were determined. Phase 1 - There was no significant difference in DXA-based TBA (p = 0.09), BMC (p = 0.33), or BMD (p = 0.74) over time between LPA treatments, or between the LPA treated and control groups TBA (p = 0.95), BMC (p = 0.99), or BMD (p = 0.46). Phase 2 - There was no significant difference over time between LPA treatments in DXA-based TBA (p = 0.33), BMC (p = 0.45), or BMD (p = 0.43), or between the LPA treated and control groups TBA (p = 0.94), BMC (p = 0.38), or BMD (p = 0.17). Phase 3 - There was no significant difference over time between LPA treatments in DXA-based TBA (p = 0.78), BMC (p = 0.88), or BMD (p = 0.35), or between the LPA treated and control groups TBA (p = 0.07), BMC (p = 0.85), or BMD (p = 0.06). There was a significant increase in TBA (p <0.0001) and BMC (p = 0.0014), but a significant decrease in BMD (p <0.0001) was noted over time when all groups were combined. Although LPA has shown promise as an osteoinductive agent in research, its performance as a bone graft substitute, as utilized in this study, is unsupported. Further studies are necessary to determine the incorporation and elution kinetics of LPA from the PLGA-g-PEG hydrogel and from an ACS. Hydrogels may have clinical applications for delaying or preventing bone formation.

Dual Bone Fixation: A Biomechanical Comparison of 3 Implant Constructs in a Mid-Diaphyseal Fracture Model of the Feline Radius and Ulna.

To compare the biomechanical properties of dual bone fixation (DBF) constructs to radial locking compression plating (LCP) in an ex vivo feline antebrachial fracture gap model. Ex vivo study. Cadaveric feline antebrachii (n=12 pairs). Antebrachii were radiographed to confirm normal skeletal appearance and maturity. After creation of a 5 mm radial and ulnar ostectomy, each antebrachium received 1 of 3 constructs using an incomplete randomized block design (n=8 per group). All groups received a 10 hole 2.0 mm radial LCP. DBF groups received either a 1.2 mm ulnar intramedullary pin (LCP with pin) or an 8 hole 2.0 mm ulnar LCP in addition to the radial LCP. Biomechanical testing was performed in axial compression and caudocranial and mediolateral 4-point bending before destruction in axial compression. DBF constructs (LCP with pin and dual LCP) were significantly stiffer than radial LCP alone in axial compression and caudocranial bending. There were no differences between LCP with pin and dual LCP constructs in axial compression and caudocranial bending or between any constructs in mediolateral bending. Failure load was significantly greater for dual LCP than LCP with pin or LCP alone constructs. Failure loads were not different between LCP with pin and LCP alone. DBF significantly increased construct stiffness and strength. Given the high complication rate reported in cat antebrachial fractures when only the radius is stabilized, surgeons should consider DBF.

A retrospective review of antebrachial angular and rotational limb deformity correction in dogs using intraoperative alignment and type 1b external fixation

AIM: The aim of this study was to report the outcome of acute antebrachial angular and rotational limb deformity (AARLD) correction using a standard radial ostectomy, an unarticulated type 1b external skeletal fixator (ESF) and intra-operative alignment with no pre-operative planning.METHODS: A retrospective evaluation was performed of dogs with carpal valgus, radial procurvatum and rotational deformity of the forelimb. All 39 cases presented and were treated surgically at a referral hospital in Melbourne, Australia, between September 2008 and March 2012. Surgical correction involved a standard closing cuneiform radial ostectomy, distal ulnar ostectomy and application of an unarticulated type 1b ESF. The method used intra-operative limb alignment and did not use pre-operative planning. Outcome was assessed via client phone interviews in all cases. Five cases were evaluated post-operatively using centre of rotation and angulation (CORA) methodology.RESULTS: As reported by owners of the 39 cases following surgery, limb function was excellent in 26 (67%), good in 12 (31%) cases and acceptable in one (2.5%) case. Frame tolerance was reported as good in 24 (62%), acceptable in 14 (36%) cases and poor in one (2.5%) case. Limb appearance was reported as straight in 25 (64%) cases and mildly rotated in 14 (36%) cases. In five cases that were evaluated, post-operative frontal and sagittal plane alignment ranged from 0–3.1° and 9.1–12.2°, respectively, and distal CORA was corrected to <6.1°. These were within the normal reported reference ranges. Pin tract infections were reported in seven (18%) casesCONCLUSIONS AND CLINICAL RELVANCE: This study suggests that the described technique may be an effective practice for the correction of AARLD that provides good clinical results, based on client assessment. The effectiveness of this technique was further supported by the five cases that underwent objective radiographic assessment. The technique is simpler than techniques that use extensive pre-operative planning, uses a smaller inventory and is easily applicable in companion animal practice.

Effect of Ulnar Ostectomy on Intra‐Articular Pressure Mapping and Contact Mechanics of the Congruent and Incongruent Canine Elbow Ex Vivo

To determine (1) the effect of elbow incongruity on contact mechanics and (2) the effect of treatment of this incongruity with 1 of 2 ulnar ostectomies in the canine elbow. Ex vivo biomechanical study. Unpaired cadaveric canine forelimbs (n = 17). In a servohydraulic testing frame, thin-film pressure sensors were placed into the lateral and medial compartments of the elbow. Specimens were tested in 135° of elbow joint flexion at 200 N of cyclic axial force, followed by a 20 seconds hold. Intra-articular contact area (CA), mean contact pressure (mCP) and peak contact pressure (pCP) were measured in each compartment. After radial shortening, testing was repeated and limbs randomized into proximal ulnar ostectomy with IM pin (PUO) or sequential distal ulnar ostectomy (DUO), interosseous ligament release (DUO-L), and ulnar attachment of the abductor pollicis longus muscle and interosseous membrane release (DUO-ML). Paired t-tests were used to compare each treatment to baseline values. Differences between treatment groups were evaluated with a mixed model with random effect to adjust for the clustering of limbs within dog. P < .05 was considered significant. Radial shortening resulted in shift of mCP and pCP from the lateral to the medial compartment. The PUO group resulted in normalization of medial compartment mCP and decrease of pCP, whereas in the DUO group return to baseline was achieved only after DUO-ML. PUO is effective in unloading medial compartment pCP in an incongruent joint.

Cubital Subchondral Joint Space Width and CT Osteoabsorptiometry in Dogs With and Without Fragmented Medial Coronoid Process

To evaluate subchondral joint space width measurements (SJSW) and CT-osteoabsorptiometry (CTOAM) measurements in the elbow of dogs with naturally occurring fragmented medial coronoid process (FMCP) preoperatively and 6 months postoperatively, and to compare these to normal dogs. Prospective randomized clinical trial. Large breed dogs <1 year of age (n = 15). Arthroscopic FMCP debridement was performed, followed by randomization to a proximal ulnar ostectomy with IM pin (PUO). CTs were performed pre-operatively and 6 months post-operatively. CTOAM and SJSW measurements were acquired in 7 locations within the joint and compared to an age-matched normal control group. Pearson correlation was performed on SJSW and CTOAM measurements. A linear mixed model determined the effect of disease and treatment on SJSW and CTOAM measurements. Fifteen dogs (28 elbows) with FMCP participated (11 arthroscopic FMCP removal, 17 with additional PUO). Data were normally distributed. Pearson correlation between CTOAM and SJSW measurements showed moderate to strong negative correlation in the control dogs. Preoperatively, affected elbows had lower medial compartment and higher lateral coronoid process CTOAM values than normal elbows. After treatment, CTOAM values of the medial compartment increased to normal. Treatment with PUO did not affect SJSW or CTOAM. Our data agree with these previous studies suggesting lower subchondral plate mineralization in dogs affected by FMCP. Arthroscopy may result in higher CTOAM values secondary to increased loading.

BMP-2 delivered from a self-crosslinkable CaP/hydrogel construct promotes bone regeneration in a critical-size segmental defect model of non-union in dogs.

To determine whether the addition of recombinant human bone morphogenetic protein (rhBMP-2) to a self-crosslinkable cellulosic hydrogel/biphasic calcium phosphate (BCP) granules construct promotes bone healing in critical-size ulnar defects in dogs. A standardized 2 cm long ulnar ostectomy was performed bilaterally in five dogs to compare bone healing with hydrogel/BCP constructs associated with or without rhBMP-2. Cancellous-bone autografts were used as positive controls in unilateral ulnar defects in five additional dogs. Radiographically, bone healing was evaluated at four, eight, 12, 16 and 20 weeks postoperatively. Histological qualitative analysis with microCT imaging and light and scanning electron microscopy were performed 20 weeks after implantation. All rhBMP-2-loaded constructs induced the formation of well-differentiated mineralized lamellar bone surrounding the BCP granules and bridging bone/implant interfaces as early as eight weeks after surgery. Bone regeneration appeared to develop earlier with the rhBMP-2 constructs than with the cancellous-bone autografts while similar results were obtained at 20 weeks. Constructs without any rhBMP-2 showed osteoconductive properties limited to the bone junctions and a lack of osteoinduction without bone ingrowth within the implantation site. In one dog, the leakage of the hydrogel loaded with rhBMP-2 induced an extensive heterotopic bone formation. The addition of rhBMP-2 to a self-crosslinkable hydrogel/BCP construct could promote bone regeneration in a critical-size-defect model with similar performance to autologous bone grafts.