Biomechanical Principles of Intramedullary Nails in Veterinary and Human Medicine.

Intramedullary nails are specialized metal rods inserted into the medullary cavity of a fractured bone and secured to reduce load on the fracture site, provide stability, and permit healing. The purpose of this review is to highlight the biomechanics of orthopaedic intramedullary nailing, as well as discuss the biomechanical considerations that have shaped implant design and fixation technique in veterinary and human medicine. Relevant studies were included from the PubMed database and Google Scholar for discussion on the basic science and nail design of intramedullary nails. Implant design and implementation continues to progress, with new innovative designs currently under investigation. A lack of consensus remains on the superior implant material. Recent studies, particularly in human populations, have supported the use of reaming based on reoperation rates, nonunion rates, and dynamization. Design modifications, such as the expandable intramedullary nails and angle-stable interlocking designs, have been investigated as methods of improving cortical contact and resisting torsional stress. Intramedullary nailing is a valuable stabilization technique for long bone fractures across a variety of species. The technology continues to undergo design improvements in both veterinary and human medicine.

Evaluation of Canine Shoulder Arthroscopy for Anatomical and Safety Considerations.

INTRODUCTION: Arthroscopy is a well-established diagnostic modality for various orthopaedic conditions in veterinary medicine. The aim of this study was to describe the relationship of canine shoulder arthroscopy portals to major muscular, ligamentous, and neurovascular structures for anatomical and safety considerations. MATERIALS AND METHODS: Arthroscopic exploration of 20 adult canine cadaver shoulders was performed. Each shoulder region was dissected layer by layer to the level of the joint. Musculotendinous, ligamentous, and cartilaginous lesions were documented. The distance was measured from each portal to neurovascular structures encountered. RESULTS: Muscular lesions included the deltoideus, cleidobrachialis, omotransversarius, supraspinatus, infraspinatus, and teres minor muscles. The neurovascular structures identified were the omobrachial vein, the caudal circumflex humeral artery, axillobrachial vein, and branches of the axillary nerve. Lesions to the lateral glenohumeral ligament were noted from the caudal instrument portal and the middle arthroscope portal. Iatrogenic articular cartilage injuries were identified on the caudal humeral head and the glenoid. CONCLUSION: This study supports the safety of lateral shoulder arthroscopy in dogs. Most local neurovascular structures are unaffected with traditional scope portal positions. Musculotendinous lesions are unavoidable due to the extensive muscling surrounding the shoulder but are unlikely to cause severe complications postoperatively.

Bending properties of additively manufactured commercially pure titanium (CPTi) limited contact dynamic compression plate (LC-DCP) constructs: Effect of surface treatment.

Additive manufacturing of metallic materials, a layer-wise manufacturing method, is currently gaining attention in the biomedical industry because of its capability to fabricate complex geometries including customized parts fitting to patient requirements. However, one of the major challenges hindering the full implementation of additively manufactured parts in safety-critical applications is their poor mechanical performance under cyclic loading. This study investigated both quasi-static bending properties (bending stiffness, bending structural stiffness, and bending strength) and bending fatigue properties of additively manufactured (AM) commercially pure titanium (CPTi) limited contact dynamic compression plate (LC-DCP) constructs based on ASTM International standard for metallic bone plates (ASTM F382). In addition, the effect of post surface treatment methods including single shot-peened (SP), dual shot-peened (DP), and chemically assisted surface enhancement (CASE) on bending fatigue performance was also evaluated. Results indicated that bending stiffness and bending structural stiffness of AM CPTi LC-DCPs are comparable to conventionally manufactured (CM) counterparts; however, the bending strength of AM CPTi LC-DCPs is lower than CM counterparts. While the fatigue strength of as-built AM CPTi LC-DCPs is lower compared to the CM counterparts, AM CPTi LC-DCPs after post surface treatments (SP, DP, and CASE) exhibit statistically comparable fatigue strength to the CM CPTi LC-DCPs.

Dexamethasone eluting 3D printed metal devices for bone injuries.

Aim: Additively manufactured (3D printed), stainless steel implants were coated with dexamethasone using gelatin, chondroitin sulfate for use in bone graft surgeries. Materials & methods: The drug and polymers were deposited on the implants with a rough surface using a high precision air brush. The gelatin-chondroitin sulfate layers were cross-linked using glutaraldehyde. Results: The drug content uniformity was within 100 ± 5%, and the thickness of the polymer layer was 410 ± 5.2 µm. The in vitro release studies showed a biphasic pattern with an initial burst release followed by slow release up to 3 days. Conclusion: These results are very promising as the slow release implants can be further tested in vivo in large animals, such as cattle and horses to prevent the inflammatory cascade following surgeries.

Effect of proximal abducting ulnar osteotomy (PAUL) on frontal plane thoracic limb alignment: An ex vivo canine study.

OBJECTIVE: To determine the effect of proximal abducting ulnar osteotomy (PAUL) on frontal plane thoracic limb alignment in standing and recumbent positions. STUDY DESIGN: Ex vivo cadaveric study. SAMPLE POPULATION: Canine thoracic limbs (n = 15 limb pairs). METHODS: Limbs were acquired from healthy Labrador retrievers that had been euthanized for reasons unrelated to this study. A limb press was used to obtain standing and recumbent caudocranial radiographs before and after PAUL. Foot lateralization and rotation were directly measured in standing position. Mechanical joint angles were determined using full limb radiographic montages and the center of rotation of angulation (CORA) method for pre-PAUL (Pre), 2-mm PAUL (PAUL2), and 3-mm PAUL (PAUL3). Data are reported as mean ± SD and 95% CI. Mixed linear modeling was used to identify differences in limb alignment values and foot position, with significance established at P ≤ .004. RESULTS: There were differences in five of 12 limb alignment values pre-PAUL and post-PAUL in standing and recumbent positions. In the standing position, there was an increase in mechanical medial proximal radioulnar angle (Pre, 80.6° ± 2.5°; PAUL2, 82.6° ± 2.4°; PAUL3, 84° ± 2.4°) and a decrease in elbow compression angle (Pre, 1.4° ± 1.3°; PAUL2, 1° ± 0.9°; PAUL3, 0.8° ± 1°). There was a movement of mechanical humeral radioulnar angle (Pre, -8.9° ± 2.8°; PAUL2, -6.1° ± 2.7°; PAUL3, -5.2 ± 2.7°), mechanical thoracic humeral angle (Pre, 3.9° ± 1.7°; PAUL2, 2.4° ± 1.4°; PAUL3, 2.6° ± 1.5°), and elbow mechanical axis deviation (Pre, 1.9% ± 1.1%; PAUL2, 0.9% ± 1.1%; PAUL3, 0.4% ± 1.4%) toward a value of "0" representing coaxial alignment of the limb. The foot underwent lateralization (Pre, 1.4 ± 0.6 cm; PAUL2, 1.8 ± 0.7 cm; PAUL3, 2.3 ± 0.7 cm) and external rotation (Pre, 10.5° ± 4.7°; PAUL2, 13.7° ± 5.1°; PAUL3, 16° ± 6.6°). CONCLUSION: In the ex vivo setting, PAUL resulted in translation of the mechanical axis of the thoracic limb from a medial to lateral direction through alterations in limb alignment values associated with the elbow, humerus, and proximal radius/ulna. CLINICAL SIGNIFICANCE: Additional studies are required to determine whether PAUL alters thoracic limb alignment in client-owned dogs.

Outcome of laparoscopic ovariectomy and laparoscopic-assisted ovariohysterectomy in dogs: 278 cases (2003-2013).

OBJECTIVE To compare outcomes for laparoscopic ovariectomy (LapOVE) and laparoscopic-assisted ovariohysterectomy (LapOVH) in dogs. DESIGN Retrospective case series. ANIMALS 278 female dogs. PROCEDURES Medical records of female dogs that underwent laparoscopic sterilization between 2003 and 2013 were reviewed. History, signalment, results of physical examination, results of preoperative diagnostic testing, details of the surgical procedure, durations of anesthesia and surgery, intraoperative and immediate postoperative (ie, during hospitalization) complications, and short- (≤ 14 days after surgery) and long-term (> 14 days after surgery) outcomes were recorded. Data for patients undergoing LapOVE versus LapOVH were compared. RESULTS Intraoperative and immediate postoperative complications were infrequent, and incidence did not differ between groups. Duration of surgery for LapOVE was significantly less than that for LapOVH; however, potential confounders were not assessed. Surgical site infection was identified in 3 of 224 (1.3%) dogs. At the time of long-term follow-up, postoperative urinary incontinence was reported in 7 of 125 (5.6%) dogs that underwent LapOVE and 12 of 82 (14.6%) dogs that underwent LapOVH. None of the dogs had reportedly developed estrus or pyometra by the time of final follow-up. Overall, 205 of 207 (99%) owners were satisfied with the surgery, and 196 of 207 (95%) would consider laparoscopic sterilization for their dogs in the future. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that short- and long-term outcomes were similar for female dogs undergoing sterilization by means of LapOVE or LapOVH; however, surgery time may have been shorter for dogs that underwent LapOVE. Most owners were satisfied with the outcome of laparoscopic sterilization.