Orthotopic forelimb transplantation in a Yucatan minipig model: Anatomic and in vivo study.

INTRODUCTION: Above elbow transplants represent 19% of the upper extremity transplants. Previous large-animal models have been too distal or heterotopic, did not use immunosuppression and had short survival. We hypothesize that an orthotopic forelimb transplant model, under standard immunosuppression, is feasible and can be used to address questions on peri-transplant ischemia reperfusion injury, and post-transplantation vascular, immunologic, infectious, and functional outcomes. MATERIALS AND METHODS: Four forelimbs were used for anatomical studies. Four mock transplants were performed to establish technique/level of muscle/tendon repairs. Four donor and four recipient female Yucatan minipigs were utilized for in-vivo transplants (endpoint 90-days). Forelimbs were amputated at the midarm and preserved through ex vivo normothermic perfusion (EVNP) utilizing an RBC-based perfusate. Hourly perfusate fluid-dynamics, gases, electrolytes were recorded. Contractility during EVNLP was graded hourly using the Medical Research Council scale. EVNP termination criteria included systolic arterial pressure ≥115 mmHg, compartment pressure ≥30 mmHg (at EVNP endpoint), oxygen saturation reduction of 20%, and weight change ≥2%. Indocyanine green (ICG) angiography was performed after revascularization. Limb rejection was evaluated clinically (rash, edema, temperature), and histologically (BANFF classification) collecting per cause and protocol biopsies (POD 1, 7, 30, 60 and endpoint). Systemic infections were assessed by blood culture and tissue histology. CT scan was used to confirm bone bridging at endpoint. RESULTS: Animals 2, 4 reached endpoint with grade 0-I rejection. Limbs 1, 3 presented grade III rejection on days 6, 61. CsA troughs averaged 461 ± 189 ng/mL. EVNLP averaged 4.3 ± 0.52 h. Perfusate lactate, PO2 , and pH were 5.6 ± 0.9 mmol/L, 557 ± 72 mmHg and 7.5 ± 0.1, respectively. Muscle contractions were 4 [1] during EVNLP. Transplants 2, 3, 4 showed bone bridging on CT. CONCLUSION: We present preliminary evidence supporting the feasibility of an orthotopic, mid-humeral forelimb allotransplantation model under standard immunosuppression regimen. Further research should validate the immunological, infectious, and functional outcomes of this model.

Ex-vivo evaluation of a percutaneous looped thread desmotomy of the accessory ligament of the deep digital flexor tendon in horses.

OBJECTIVE: To determine the ability to completely transect the equine accessory ligament of the deep digital flexor tendon (AL-DDFT) via an ultrasonographically-guided, percutaneous looped thread desmotomy using FiberWire suture as a cutting device. STUDY DESIGN: Ex-vivo study. SAMPLE POPULATION: A total of 24 normal equine distal forelimb specimens. METHODS: Under ultrasonographic guidance, a Jamshidi needle was placed between the suspensory ligament and the AL-DDFT, and between the AL-DDFT and the deep digital flexor tendon, through two stab incisions. FiberWire suture was fed through the needle and looped around the AL-DDFT. Using a sawing motion, the ligament was transected, and the suture exited through the lateral incision. Surgical sites were dissected and assessed for completeness of transection, iatrogenic injuries, and suture remnants. Descriptive statistics were reported. RESULTS: The procedure met the successful criteria in 18/24 (75%) of the limbs. The median surgical time was 11 min (range 7-25). No suture failure or suture remnants were noted in any of the specimens. Complications included iatrogenic injury to the medial and lateral neurovascular bundles in 4/24 and 1/24 specimens, respectively. CONCLUSION: Complete transection of the AL-DDFT was achieved in 22/24 (92%) of the specimens; however, the neurovascular bundles were injured in 5/24 (21%) of the specimens. CLINICAL SIGNIFICANCE: A percutaneous looped thread desmotomy of the AL-DDFT can be studied as an alternative technique for use in equine models prior to its clinical use in patients. Additional studies are required to evaluate efficacy and safety in anesthetized or standing horses.

Athletic prognosis following arthroscopic removal of osteochondral fragments of the proximal dorsal sagittal ridge of the fetlock in Thoroughbreds intended for flat racing.

OBJECTIVE: To establish racing prognosis in Thoroughbred yearlings with proximal sagittal ridge osteochondral lesions and compare them to dorsoproximal and palmar/plantar first phalanx osteochondral lesions. ANIMALS: A total of 47 horses had proximal sagittal ridge lesions, 34 had palmar/plantar first phalanx lesions, and 115 had dorsoproximal first phalanx lesions. STUDY DESIGN: Retrospective case series. METHODS: Medical records of Thoroughbred yearling racing prospects treated arthroscopically for fetlock osteochondral lesions were reviewed. Data were collected from a public database, including the ability to train and race, earnings, starts, wins, and placed races. Racing prognosis was analyzed and compared between three lesion locations. RESULTS: Of the proximal sagittal ridge group, 76.6% raced, 65.71% of the palmar/plantar first phalanx group, and 74.58% of the dorsoproximal first phalanx group. Career length was similar for all lesions. A lower number of "starts" in the group "five years old and older" was found for the dorsoproximal first phalanx group compared to the cohort with proximal sagittal ridge lesions. Mares had more "earnings" at two years old but fewer "starts" at "five years old" compared to colts and geldings. Forelimb lesions were predictive for fewer total career starts. CONCLUSION: Proximal sagittal ridge lesions had similar prognoses to dorsoproximal and palmar/plantar first phalanx lesions. In older horses, there was an increase in the number of starts for the proximal sagittal ridge group compared to the dorsoproximal first phalanx group. Mares and forelimb lesions were associated with decreased racing starts. CLINICAL SIGNIFICANCE: These findings aid in prognostication for Thoroughbreds with osteochondral lesions removed arthroscopically in the fetlock joint.

Comparison of three-dimensional printed patient-specific guides versus freehand approach for radial osteotomies in normal dogs: Ex vivo model.

OBJECTIVE: To compare the accuracy of three-dimensional (3D) printed patient-specific guide (PSG) with a freehand (FH) approach for radial osteotomies in ex vivo normal dogs. STUDY DESIGN: Experimental study. ANIMALS: Twenty four ex vivo thoracic limb pairs from normal beagle dogs. METHODS: Computed tomography (CT) images were collected preoperatively and postoperatively. Three osteotomies tested (n = 8/group) were: (1) uniplanar 30° frontal plane wedge ostectomy, (2) oblique plane (30° frontal, 15° sagittal) wedge ostectomy, and (3) single oblique plane osteotomy (SOO, 30° frontal, 15° sagittal, and 30° external). Limb pairs were randomized to a 3D PSG or FH approach. The resultant osteotomies were compared with virtual target osteotomies by surface shape-matching postoperative to the preoperative radii. RESULTS: The mean ± standard deviation osteotomy angle deviation for all 3D PSG osteotomies (2.8 ± 2.8°, range 0.11-14.1°) was less than for the FH osteotomies (6.4 ± 6.0°, range 0.03-29.7°). No differences were found for osteotomy location in any group. In total, 84% of 3D PSG osteotomies were within 5° deviance from the target compared to 50% of freehand osteotomies. CONCLUSION: Three-dimensional PSG improved FH accuracy of osteotomy angle in select planes and the most complex osteotomy orientation in a normal ex vivo radial model. CLINICAL SIGNIFICANCE: Three-dimensional PSGs provided more consistent accuracy, which was most notable in complex radial osteotomies. Future work is needed to investigate guided osteotomies in dogs with antebrachial bone deformities.

A novel transcoronal surgical technique for the treatment of cystic lesions of the distal phalanx: A cadaveric study.

OBJECTIVE: To assess the feasibility of a novel transcoronal approach for the treatment of axial type 3 cysts of the palmar/plantar aspect of the distal phalanx (P3). STUDY DESIGN: Ex vivo, experimental study. SAMPLE POPULATION: Ten cadaveric specimens, four forelimbs and six hindlimbs. METHODS: All cadaveric specimens underwent radiographically guided drilling, followed by cortical screw placement. The cartilage was macroscopically assessed after disarticulation of the distal interphalangeal joint. The entry point and trajectory were evaluated with computed tomography. Results were categorized as: axial, near-axial and abaxial. The minimal distance from the outer margin of the drill hole and the proximal border of the subchondral bone plate was measured using frontal computed tomographic slices. RESULTS: Eight of the 10 screws were in an axial to near-axial position and nine followed the desired axial to near-axial trajectory. One screw was inserted axially but continued in an abaxial trajectory. Iatrogenic damage to the joint cartilage, flexor cortex and solar canal of P3 was not observed. All cortical screws were placed close to the proximal subchondral bone-plate of P3. CONCLUSION: The desired axial/near-axial drilling and screw placement, under radiographic guidance, was achieved in nine out of 10 specimens. CLINICAL SIGNIFICANCE: This novel technique seems promising for the treatment of inaccessible P3 cysts. Additional studies are required to investigate its feasibility in clinical cases, and the long-term outcome following transcystic screw placement of type 3 P3 cysts.

The use of lateral arthroscopy portals for the management of a fragmented lateral coronoid process in an English Bulldog.

OBJECTIVE: To report a case of unilateral lateral coronoid process fragmentation in a dog treated via lateral elbow arthroscopy portals. ANIMAL: A 9-month old male intact English Bulldog. STUDY DESIGN: Case report. METHODS: The dog presented with a history of intermittent right thoracic limb lameness. Orthopedic examination on presentation was unremarkable. Computed tomography of the right thoracic limb was pursued and revealed a mineralized focus along the lateral margin of the lateral coronoid process as well as sclerosis of the medial coronoid process and subtrochlear region of the ulna. Elbow arthroscopy was performed via a lateral approach and revealed chondromalacia of the entire lateral coronoid process. Abrasion arthroplasty of the lateral coronoid process was performed. RESULTS: Complete resolution of the lameness was achieved within two weeks of surgery. At 6 weeks postoperatively, the dog remained sound and a gradual return to normal activity was recommended. At the final follow up assessment, 5 months after surgery, no abnormalities were found on orthopedic examination and the owners reported excellent limb function with no observable lameness. CONCLUSION: Lateral coronoid disease can occur as a rare component of elbow dysplasia in dogs. Abrasion arthroplasty via lateral arthroscopic portals may have resulted in a successful outcome in this case and may form an effective treatment option for lateral coronoid disease in dogs.

Dorsal-to-palmar branch neuroanastomosis in horses undergoing palmar digital neurectomy does not reduce neuroma formation or improve outcome.

OBJECTIVE: Chronic foot pain, a common cause of forelimb lameness, can be treated by palmar digital neurectomy (PDN). Complications include neuroma formation and lameness recurrence. In humans, neuroanastomoses are performed to prevent neuroma formation. The aim of the study was to evaluate the outcome of horses undergoing dorsal-to-palmar branch neuroanastomosis following PDN. STUDY DESIGN: Retrospective case series. ANIMALS: Eighty-five horses with PDN and dorsal-to-palmar branch neuroanastomosis. METHODS: Medical records for horses undergoing this procedure at two hospitals between 2015 and 2020 were reviewed. Palmar and dorsal nerve branches of the PDN were transected and end-to-end neuroanastomosis was performed by apposition of the perineurium. Follow-up was obtained from medical records and telephone interviews. Success was defined as resolution of lameness for at least one year. RESULTS: Lameness resolved following surgery in 81/85 (95%) horses with 57/84 (68%) sound at one year. Postoperative complications occurred in 19/85 (22%) cases. The main limitations of the study were an incomplete data set, inaccurate owner recall, and variations in procedure. CONCLUSION: Compared to previous studies, this technique resulted in similar numbers of horses sound immediately after surgery, a comparable rate of postoperative neuroma formation but a higher recurrence of lameness rate at 1 year postoperatively. CLINICAL SIGNIFICANCE: End-to-end neuroanastomosis of the dorsal and palmar branches of the PDN does not reduce the rate of neuroma formation in horses. Long-term outcome was less favorable compared to previously reported PDN techniques.

Ulnocarpal arthrodesis as a new treatment for ectrodactyly in a dog and a cat.

CASE HISTORY: A 4-month-old male Shih Tzu dog (Case 1) and an 11-month-old female Devon Rex cat (Case 2) were referred to specialist veterinary hospitals for evaluation of right thoracic lameness and growth abnormality in the distal aspect of the forelimb. CLINICAL FINDINGS: Non-weight-bearing lameness and decreased range of motion were noted in the affected limbs of both cases. Case 1 had a plantigrade stance, and a cleft separation between the first and second digits extending upwards to the distal third of the antebrachium. There was no pain on palpation, and the affected limb was shorter than the contralateral. Radiographic examination revealed cleft separation between metacarpal bones I and II, and carpal bone fusion (I, II, III), and the distal radius ended freely and was attached to the first metacarpal bone.Case 2 had a small cleft medial to metacarpal III. The limb was consistently held in abduction and had marked carpal varus. The limb had never been used for weight bearing. Radiographic examination showed agenesis of metacarpal bone II and separation of metacarpals I and III. The radius and ulna were separated and the radial head did not articulate normally at the elbow, leading to marked elbow incongruity. DIAGNOSIS: Ectrodactyly in both cases. TREATMENT AND OUTCOME: Amputation of the radius followed by ulnocarpal arthrodesis were performed in both cases. Follow-up evaluations up to 1 year (Case 1) and 10 weeks (Case 2) after surgery indicated satisfactory arthrodesis fusion, owner satisfaction, and a good clinical outcome. CLINICAL RELEVANCE: Ectrodactyly is a rare congenital deformity of the forelimb with a heterogeneous character, requiring an individualised treatment plan. These are the first cases reported in the literature of ectrodactyly in small animals that were treated successfully with ulnocarpal arthrodesis. This case series therefore provides evidence in support of this treatment option for this heterogeneous congenital deformity.

AN ANATOMICAL STUDY OF THE THORACIC LIMB OF THE GIANT ANTEATER (MYRMECOPHAGA TRIDACTYLA) COMPARED WITH THE DOMESTIC DOG TO GUIDE SURGICAL APPROACHES TO THE HUMERUS AND RADIUS.

The giant anteater (Myrmecophaga tridactyla) is a neotropical mammal considered to be vulnerable to extinction. Recent increased interest in veterinary care in the giant anteater has prompted renewed interest in anatomical descriptions in this species. The terrestrial habits and slow movements of the giant anteater contribute to its susceptibility to vehicular trauma on highways, which is a significant cause of mortality in the species. This study describes the muscular anatomy of the thoracic limb and variations of the long bones with emphasis on the structures surrounding the humerus and radius. It also describes the possible surgical approaches for the management of fractures of humerus and radius, comparing these with the surgical approaches described in dogs (Canis lupus familiaris). Three giant anteater and three domestic dog cadavers, from deaths not related to this project, were used. The medial approach to the humeral diaphysis of the giant anteater resulted in the least tissue trauma, and provided access to the flattest surface for implant attachment. The lateral approach to the radius proved challenging, requiring total detachment of the extensor carpi radialis muscle and incision of the very robust abductor digitorum longus muscle to access the distal diaphysis. Although the giant anteater shares many similarities of the thoracic limb anatomy with the domestic dog, important differences exist. This comparative knowledge will allow veterinary practitioners to directly apply the principles of fracture repair in these species. Safe access to these bones for possible osteosynthesis is essential to allow implant placement and minimize postoperative complications in this species.

Ex vivo evaluation of a percutaneous thread-transecting technique for desmotomy of normal palmar/plantar annular ligaments in horses.

OBJECTIVE: To develop and describe a minimally invasive, ultrasound-guided, percutaneous technique for the desmotomy of equine palmar/plantar annular ligaments (PALs) using a transecting thread. STUDY DESIGN: Ex vivo study. SAMPLE POPULATION: Twenty-one normal equine distal limb specimens. METHODS: Under ultrasonographic guidance, a surgical thread was percutaneously placed around the PAL through 2 skin punctures (proximal and distal) using a 18 gauge spinal needle in equine limbs (11 forelimbs, 10 hindlimbs) with normal PALs. The ligament was transected by a back-and-forth motion of the thread until the loop emerged from the proximal skin puncture site. Each specimen was dissected and assessed for completeness of transection and iatrogenic damage under direct visualization. Descriptive statistics were reported. RESULTS: The PAL was completely transected in 17/21 limbs. The mean duration of the procedure was 16 minutes. Superficial needle puncture or subtle abrasion of the superficial digital flexor tendon was noticed in 4 limbs. No iatrogenic injury to other intrathecal structures was identified. After PAL division, the needle entry and exit points had a mean diameter of 1.2 and 1 mm, respectively. CONCLUSION: Desmotomy of normal PALs in equine limb specimens was performed effectively using the percutaneous thread-transecting technique with minimal iatrogenic damage to adjacent structures. CLINICAL SIGNIFICANCE: Information from this study will allow refinement of the technique for use in equine clinical cases either in standing or anesthetized horses.

The use of subchondral bone topography to approximate the center of rotation of the elbow joint in dogs.

OBJECTIVES: The aim of this study was to compare the approximate center of rotation in normal and diseased elbows in dogs. STUDY DESIGN: Cross-sectional study SAMPLE POPULATION: Computer tomography scans of nine dogs with unilateral fragmented medial coronoid process (FMCP). METHODS: A board certified radiologist confirmed that each dog had unilateral FMCP, and a normal contralateral elbow. Digital 3D models of all elbow joints were uploaded into a surgical planning software package. Four axes approximating the center of rotation (COR) of elbow joints were generated using five geometric shapes based on subchondral topography of the humeral condyle radius and ulna. Images showing the locations where axes exited the medial and lateral cortex of the humeral condyle were captured and imported into a second software package, for measurement of distances between exit points and the origin of a system of axes. RESULTS: In normal joints 20/27 (74%) axes exited the medial cortex, and 25/27 (93%) axes exited the lateral cortex cranial and distal to the medial and lateral epicondyles, respectively. In diseased joints 22/27 (81%) axes exited medial cortex and 19/27 (70%) axes exited the lateral cortex, caudal and distal to the medial and lateral epicondyles, respectively. CONCLUSION: Based on CT- derived geometry, the COR of elbow affected with FMCP was generally more caudal than normal. CLINICAL SIGNIFICANCE: External landmarks approximating the location of the elbow COR are provided, and while not validated, may assist in planning, creation, and assessment of procedures for FMCP.

Evaluation of a small-bore needle arthroscope for diagnosis and treatment of medial coronoid disease in dogs: a pilot study with short-term assessment.

CASE HISTORY: Dogs (n = 15) that were presented to a single veterinary teaching hospital with elbow dysplasia-associated lameness between September 2021 and May 2022, and were determined to require arthroscopy based on imaging results, were prospectively recruited into the study. The median duration of lameness was 4 (min 1, max 24) months. CLINICAL FINDINGS: Various breeds were represented with a median body weight of 31.6 (min 15, max 46.4) kg and median age at presentation of 14 (min 8, max 83) months. Results of imaging modalities (CT) were consistent with medial coronoid disease with fissured or fragmented medial coronoid process in all dogs. ARTHROSCOPIC FINDINGS: Feasibility of the needle arthroscopy (NA) procedure was firstly assessed in a preliminary cadaveric study in forelimbs (n = 10) collected from 10 adult dogs euthanised for reasons unrelated to the study. Elbow exploration was performed through a medial approach beginning with NA (1.9 mm 0° angle scope) followed by standard arthroscopy (SA; 2.4 mm 30° angle scope). The quality and extent of visualisation (scored through the number of anatomical structures visualised) were recorded and statistically compared. As the cadaver study indicated that NA allowed safe inspection of all structures in medial/caudal compartments, this procedure was then used in the dogs requiring treatment. In the clinical setting, elbow exploration was successful in all dogs and the treatment (removal of osteochondral fragments) was performed without requiring conversion into SA. One month after surgery, all dogs had an improvement in their lameness score (0-5) and 12/15 dogs were no longer lame. There was a reduction in Canine Orthopaedic Index scores measured a median of 99 (min 47, max 180) days after surgery (24 (IQR 19.5-31.5)) compared to the pre-operative period (49 (IQR 46.5-57); p < 0.001). CLINICAL RELEVANCE: Needle arthroscopy-assisted removal of osteochondral fragments was performed in all dogs with satisfactory short-term clinical outcome. NA is a feasible technique for diagnosis and lesion assessment in dogs with a fissured or fragmented coronoid process. Larger clinical studies with longer follow-up are necessary to validate the NanoScope operative arthroscopy system as an alternative strategy to SA for video-assisted treatment of medial coronoid disease.

Bilateral non-traumatic elbow luxation in a Yorkshire terrier puppy.

A 10-week-old Yorkshire terrier had lameness of the right forelimb with complete lateral radioulnar luxation at the humerus, consistent with Type III congenital elbow luxation; this is rarely treated in the presence of multiple skeletal deformities. Lateral subluxation of the radial head at the left elbow was diagnosed as Type I congenital elbow luxation. Procurvatum, distal valgus, and external torsion were present in both antebrachiae. Surgical stabilization of the right elbow was performed with temporary transarticular pins in the humeroulnar and radioulnar joints. A custom-made orthosis was applied to support the surgical reduction for 20 wk. Recurrent luxation was not observed. After complete right-sided function was established, the left forelimb showed noticeable instability in the antebrachium, and the puppy frequently fell while running. The lateral collateral ligament of the left elbow was augmented using screws and synthetic ligaments 22 wk after the right-side surgery. Congruity of the left elbow joint improved, and the puppy could bear full weight on the left forelimb, although slight deficits in movement and falling were observed. We demonstrate the effectiveness of combining a temporary transarticular pin and custom-made orthosis while treating Type III congenital elbow luxation and the inadequacy of collateral ligament augmentation alone for treating Type I congenital elbow luxation with antebrachium deformities. Key clinical message: Herein, we observed that a combination of a temporary transarticular pin and a custom-made orthosis was effective for the treatment of Type III congenital elbow luxations.

Luxation bilatérale non traumatique du coude chez un chiot Yorkshire terrier. Un Yorkshire terrier de 10 semaines présentait une boiterie du membre antérieur droit avec une luxation radio-ulnaire latérale complète au niveau de l'humérus, compatible avec une luxation congénitale du coude de type III; ceci est rarement traité en présence de multiples déformations squelettiques. La subluxation latérale de la tête radiale au niveau du coude gauche a été diagnostiquée comme une luxation congénitale du coude de type I. Procurvatum, valgus distal et torsion externe étaient présents dans les deux sections antébrachiales. La stabilisation chirurgicale du coude droit a été réalisée avec des broches trans-articulaires temporaires dans les articulations huméro-ulnaire et radio-ulnaire. Une orthèse sur mesure a été appliquée pour soutenir la réduction chirurgicale pendant 20 semaines. Aucune luxation récurrente n'a été observée. Une fois la fonction complète du côté droit établie, le membre antérieur gauche a montré une instabilité notable de la section antébrachiale et le chiot tombait fréquemment en courant. Le ligament collatéral latéral du coude gauche a été augmenté à l'aide de vis et de ligaments synthétiques 22 semaines après la chirurgie du côté droit. La congruence de l'articulation du coude gauche s'est améliorée et le chiot pouvait supporter tout son poids sur le membre antérieur gauche, bien que de légers déficits de mouvement et des chutes aient été observés. Nous démontrons l'efficacité de la combinaison d'une broche trans-articulaire temporaire et d'une orthèse sur mesure dans le traitement de la luxation congénitale du coude de type III et l'insuffisance de l'augmentation du ligament collatéral seule pour traiter la luxation congénitale du coude de type I avec des déformations de la section antébrachiale.Message clinique clé:Ici, nous avons observé qu'une combinaison d'une broche trans-articulaire temporaire et d'une orthèse sur mesure était efficace pour le traitement des luxations congénitales du coude de type III.(Traduit par Dr Serge Messier).

Effect of single and double hemitenotomy on equine deep digital flexor tendon length and strength in experimental load challenges.

OBJECTIVE: To evaluate a double hemitenotomy (DHT) technique as an alternative to complete deep digital flexor (DDFT) tenotomy. STUDY DESIGN: Experimental ex vivo study. SAMPLE POPULATION: Isolated DDFTs (n = 30) and cadaveric forelimbs (n = 16). METHODS: In part 1, 15 isolated DDFT pairs were used. Two hemitenotomies were created in 1 DDFT while the other served as reference. Monotonic tensile load was applied. Tendon lengthening, load reduction, and load at failure were recorded. In part 2, 16 cadaveric forelimb pairs were subjected to DHT followed by complete tenotomy (CT) under monotonic compressive load. Differences between DHT and controls were assessed with Wilcoxon signed rank tests or Friedman tests. RESULTS: In isolated tendons and cadaveric forelimbs, DHT resulted in DDFT lengthening (median, +1.9 mm and + 3.05 mm) and load reduction (median, -16.7 and -11.2 kg). Less lengthening was achieved with DHT compared to CT (P = .008). Load reduction did not occur between DHT and CT was observed during compressive testing (P = 1). Load reduction following the first hemitenotomy incision was smaller when compared to the second (P = .022). Isolated DHT tendons failed at a tensile load of 195 kg, while no intact tendons failed (P = .0001). CONCLUSION: Double hemitenotomy was comparable to CT in load reduction. It reduced tensile strength, but load at failure was similar or exceeded the estimated DDFT load at stance. CLINICAL SIGNIFICANCE: Hemitenotomy may be a useful alternative for surgical management of horses with laminitis, but in vivo studies are needed to confirm these findings.

Predicting return to racing after repair of fractures of the metacarpal/metatarsal condyles in Thoroughbred racehorses.

OBJECTIVE: To identify prognostic factors for return to racing after lag screw repair of condylar fractures and develop a predictive model for return to racing. STUDY DESIGN: Retrospective cohort study. ANIMALS: A total of 356 horses referred to a single referral hospital in the UK with a third metacarpal/metatarsal condylar fracture between January 1999 and December 2018. METHODS: Age, sex, fracture site, fracture characteristics, surgery related variables and complications were retrieved from case records. Data were divided into two sets for model training and model validation. Univariable analyses were performed, and predictors were selected in a stepwise fashion for inclusion in the multivariable logistic regression model. Sensitivity and specificity were evaluated using the second dataset. RESULTS: Older horses, fillies, fractures of forelimbs, complex, complete, displaced or propagating fractures and concurrent proximal sesamoid bone fracture were negatively associated with return to racing. Colts and geldings were 3 and 4 times more likely to race than fillies, respectively. Horses with hindlimb, incomplete or nonpropagating fractures were 4, 5 and 4 times more likely to race than those with a forelimb, complete or propagating fracture, respectively. Using a predicted probability cut-off threshold of 0.5, a predictive model was created within one dataset (sensitivity = 84%, specificity = 50.5%) and applied to another (sensitivity = 83.1%, specificity = 24.0%). CONCLUSION: Negative prognostic factors were identified and led to a predictive model with acceptable sensitivity and specificity in the tested population. CLINICAL SIGNIFICANCE: The results provide proof of concept for the model in the reported population and justify further validation in different populations of horses.

Fascial plane mapping for superficial tumor resection in dogs. Part II: Forelimb.

OBJECTIVE: To detail the qualitative fascial categories and fascial intersections of the forelimb of the dog to facilitate preoperative planning for superficial cancers. STUDY DESIGN: Qualitative anatomical study. SAMPLE POPULATION: Three male and four female mixed breed canine cadavers weighing approximately 20-35 kg. METHODS: The skin and subcutaneous fat were excised. Fascial planes were incised and elevated to allow exploration of their quality and borders. Fascia was categorized as type I (discrete sheets), type II (tightly adhered to thin muscles), type III (tightly adhered to thick muscles), or type IV (associated with periosteum). Photographs of specimens were digitally modified with overlays to map tissue types. RESULTS: Differences between the cadavers used were largely based on muscle mass and sex, with minimal other subjective differences affecting fascial mapping. The fasciae of the forelimb were largely type II or type III, with type I fascia at the antebrachium and type IV fascia at the olecranon, scapular spine, and accessory carpal bone. Fascial integrity was often questionable or lacking distal to the distal quarter of the antebrachium. CONCLUSION: The fascial types and integrity of the forelimb varied with anatomic location with thin or absent fascia for surgical use at the elbow, carpus, and manus. CLINICAL SIGNIFICANCE: This study provides information for preoperative planning and excision of superficial tumors of the forelimb. Knowledge of the potential limitations of fascia to provide a deep margin may influence selection of treatment modalities.

Needle arthroscopy for exploration of the elbow joint: a case series of six dogs with preliminary cadaveric study.

CASE HISTORY: Dogs (n = 6) suffering from elbow-associated lameness for a median of 3.5 (min 2, max 12) months duration requiring arthroscopic exploration according to imaging results were prospectively included in this study. CLINICAL FINDINGS: Dogs that met the inclusion criteria were of various breeds with a median body weight of 18 (min 13.2, max 34.5) kg and median age at presentation of 11 (min 6, max 96) months. Results of imaging modalities (radiographs and/or computed tomography (CT)) were consistent with developmental elbow disease in all of the dogs. ARTHROSCOPIC FINDINGS: Feasibility of the needle arthroscopy procedure was first assessed in a preliminary cadaveric study. Disease-free cadaveric forelimbs (n = 12) were collected from adult dogs (n = 6) euthanised for reasons unrelated to the present study. Elbow exploration was performed, beginning with needle arthroscopy (1 mm, 0° angle scope) followed by standard arthroscopy (2.4 mm, 30° angle scope) through a medial approach. The ease of introduction, range of motion and the quality of visualisation were assessed subjectively and the presence of iatrogenic introduction lesions and extent of field of vision (assessed by the number of anatomical structures visualised) were scored and statistically compared. Needle arthroscopy allowed inspection of all structures at risk for medial/caudal compartment disease in all joints considering the occasional need for multiple portals. In the clinical setting, elbow exploration was found to be similar to that in cadaver joints in 4/6 dogs. The lower quality of vision provided by needle arthroscopy was a limitation of the technique, and 2/6 clinical cases required conversion to standard arthroscopy for full visualisation of the joint. No introduction lesions were noted with needle arthroscopy in either the cadaveric or clinical studies. CONCLUSIONS AND CLINICAL RELEVANCE: Needle arthroscopy allowed safe visualisation of all of the structures of the medial and caudal compartment in disease-free cadaveric elbows, suggesting that needle arthroscopy is an appropriate technique for diagnosis and assessment of lesions of developmental elbow disease. However, the low quality of vision provided by the 1 mm scope, and the small diameter of the sleeve, which limited fluid inflow, combined with fragility of the device were major drawbacks that prevented consistent full exploration of the joint and detailed lesion assessment in clinical situations. Improvement of the device is thus necessary before use of the technique in clinical practice can be recommended. ABBREVIATIONS: CCD: Caudal compartment disease; CT: Computed tomography; DED: Developmental elbow disease; DJD: Degenerative joint disease; LCL: Lateral collateral ligament; LCP: Lateral coronoid process; LHC: Lateral part of the humeral condyle; MCD: Medial compartment disease; MCL: Medial collateral ligament; MCP: Medial coronoid process; MHC: Medial part of the humeral condyle; MRI: Magnetic resonance imaging.

Ex-vivo articular cartilage removal from equine proximal interphalangeal joints using cannulated drill bits.

Objective: This report evaluates the use of 4.5- and 5.5-mm cannulated drill bits for articular cartilage removal from the proximal interphalangeal joints of equine cadaver limbs. Animals: Limbs from 8 equine cadavers, all with normal proximal interphalangeal joints. Procedure: Proximal interphalangeal joints of 32 limbs from 8 equine cadavers were drilled using either 4.5- or 5.5-mm cannulated drill bits. Pastern joints were then disarticulated, and intra-articular drilling was evaluated by visual inspection. Results: Post-drilling evaluation revealed complete intra-articular drilling occurred in all 32 joints. Conclusion: Canulated 4.5- and 5.5-mm drill bits resulted in consistent accurate intra-articular drilling in the proximal interphalangeal joint of horses. Clinical relevance: Cannulated drill bits provided an effective and consistent modality for articular cartilage removal with potential for improved accuracy of articular drilling and applications in minimally invasive proximal interphalangeal joint arthrodesis.

Objectif: Ce rapport évalue l'utilisation de forets canulés de 4,5 et 5,5 mm pour l'élimination du cartilage articulaire des articulations interphalangiennes proximales des membres de cadavres équins. Animaux: Membres provenant de huit cadavres équins, tous avec des articulations interphalangiennes proximales normales. Procédure: Les articulations interphalangiennes proximales de 32 membres de huit cadavres équins ont été percées à l'aide de forets canulées de 4,5 ou 5,5 mm. Les articulations du paturon ont ensuite été désarticulées et le forage intraarticulaire a été évalué par inspection visuelle. Résultats: L'évaluation post-forage a révélé qu'un forage intra-articulaire complet s'était produit dans les 32 articulations. Conclusion: Les forets canulés de 4,5 et 5,5 mm ont permis un forage intra-articulaire précis et constant dans l'articulation interphalangienne proximale des chevaux. Pertinence clinique: Les forets canulés ont fourni une modalité efficace et constante pour l'élimination du cartilage articulaire avec un potentiel d'amélioration de la précision du forage articulaire et des applications dans l'arthrodèse de l'articulation interphalangienne proximale de manière minimalement invasive.(Traduit par Dr Serge Messier).

Intrathecal Injection of GRIP-siRNA Reduces Postoperative Synaptic Abundance of Kainate Receptor GluK2 Subunits in Rat Dorsal Horns and Pain Hypersensitivity.

The mechanisms underlying postoperative pain differ from the inflammatory or neuropathic pain. Previous studies have demonstrated that intrathecal α-amino-3-hydroxy-5-methy-4-isoxazole propionate (AMPA) -kainate (KA) receptor antagonist inhibits the guarding pain behavior and mechanical hyperalgesia, indicating a critical role of spinal KA receptors in postoperative pain hypersensitivity. However, how the functional regulations of spinal KA receptor subunits are involved in the postoperative pain hypersensitivity remains elusive. Therefore, in the current study, we investigated the synaptic delivery of spinal KA receptor subunits and the interaction between KA receptor subunits and glutamate receptor-interacting protein (GRIP) during the postoperative pain. Our data indicated that plantar incision induced the synaptic delivery of GluK2, but not GluK1 or GluK3 in ipsilateral spinal cord dorsal horns. The co-immunoprecipitation showed an increased GluK2 -GRIP interaction in ipsilateral dorsal horn neurons at 6 h post-incision. Interestingly, Intrathecal pretreatment of GRIP siRNA increased the paw withdrawal thresholds to mechanical stimuli and decreased the cumulative pain scores in the paws ipsilateral to the incision at 6 h post-incision. Additionally, Intrathecal pretreatment of GRIP siRNA reduced the synaptic abundance of GluK2 in ipsilateral spinal dorsal horn at 6 h after plantar incision. In general, our data have demonstrated that the GluK2- GRIP interaction-mediated synaptic abundance of GluK2 in dorsal horn neurons plays an important role in the postoperative pain hypersensitivity. Disrupting the GluK2- GRIP interaction may provide a new approach for relieving postoperative pain.

The effect of plate fixation on supination and pronation of the feline antebrachium: a model of pancarpal arthrodesis.

BACKGROUND: Pancarpal arthrodesis is purported to limit supination and pronation of the feline antebrachium. The objective of this study was to investigate whether plate fixation of the radius to the carpus and metacarpus limits supination and pronation of the ulna relative to the radius as a model for pancarpal arthrodesis in the cat. Eight feline cadaveric forelimbs were rotated from supination to pronation in a testing jig and CT (computed tomography) was performed in the neutral, supinated and pronated positions. A locking plate was then secured dorsally to the radius, radial carpal bone and metacarpal III of each of the limbs. CT was repeated in each of the testing positions following plate application. The radius and ulna of the control specimens, and the radius, ulna and plate of the plated specimens were then segmented using software. Alignment of the bones to the radius in the control specimens, and to the plate in the plated specimens was used to compare the changes in degrees of movement of the ulna relative to the radius in dorsal, sagittal and transverse planes. RESULTS: Based on the results of the paired t test, there was no significant difference in degrees of movement, or total range of motion between control and plated specimens in supinated and pronated testing conditions. CONCLUSION: The results of this ex-vivo study indicate that under the testing conditions employed, plate fixation of the radius to the carpus and metacarpus does not limit supination and pronation of the feline antebrachium.