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Femoral fractures are often considered lethal for adult horses because femur osteosynthesis is still a surgical challenge. For equine femur osteosynthesis, primary stability is essential, but the detailed physiological forces occurring in the hindlimb are largely unknown. The objective of this study was to create a numerical testing environment to evaluate equine femur osteosynthesis based on physiological conditions. The study was designed as a finite element analysis (FEA) of the femur using a musculoskeletal model of the loading situation in stance. Relevant forces were determined in the musculoskeletal model via optimization. The treatment of four different fracture types with an intramedullary nail was investigated in FEA with loading conditions derived from the model. The analyzed diaphyseal fracture types were a transverse (TR) fracture, two oblique fractures in different orientations (OB-ML: medial-lateral and OB-AP: anterior-posterior) and a "gap" fracture (GAP) without contact between the fragments. For the native femur, the most relevant areas of increased stress were located distally to the femoral head and proximally to the caudal side of the condyles. For all fracture types, the highest stresses in the implant material were present in the fracture-adjacent screws. Maximum compressive (-348 MPa) and tensile stress (197 MPa) were found for the GAP fracture, but material strength was not exceeded. The mathematical model was able to predict a load distribution in the femur of the standing horse and was used to assess the performance of internal fixation devices via FEA. The analyzed intramedullary nail and screws showed sufficient stability for all fracture types., (© 2024. The Author(s).)

Background: The bone regeneration potential of erythropoietin (EPO) is not yet fully investigated, but some previous experimental studies demonstrated that its application activated the differentiation of osteoblasts and promoted bone formation., Aim: The aim of the present study was to evaluate the effects of recombinant human erythropoietin (rhEpo) on bone healing in cats with fragmented long bone fractures., Methods: Twelve cats were divided into two groups-control ( n = 6) in which physiological saline was applied at the fracture gap site and EPO ( n = 6) with the application of 1,000 IU rhEpo. The effects of EPO on blood erythrocyte counts, hemoglobin content, and hematocrit were monitored by serial complete blood cell tests, whereas bone formation was evaluated by clinical and radiographic examinations on post-operative weeks 1, 2, 3, 4, 6, and 8., Results: All tested blood parameters were within the reference range. A faster fracture healing and full limb weight-bearing were observed in the EPO group, with statistically significant differences with respect to the control group., Conclusion: The obtained results confirmed that the local application of rhEpo promoted bone healing in cats with fragmented femoral fractures and increased bone callus strength without having significant systemic effects., Competing Interests: The authors declare no conflict of interest.

Objective: Femoral fractures are often catastrophic in large animals. Radiographic diagnosis is limited by patient size and feasibility, especially in ambulatory settings. Ultrasonography is widely available and may provide an alternative to radiography for definitive diagnosis., Animals: 12 large animals (6 horses, 5 cattle, and 1 elephant)., Procedures: Retrospective analysis of large animal patients diagnosed with femoral fracture by use of femoropelvic ultrasonography (2000 to 2019)., Results: 5 of 12 cases were ≤ 1 year of age. The remaining 7 cases were 2 to 33 years of age (median, 13 years). All patients developed severe acute lameness after falling (n = 4), limb entrapment (2), dystocia (1), vehicular collision (1), ipsilateral full limb casting (1), or unknown events (3). All were non-weight-bearing or lame at the walk, including 2 recumbent cattle. Ten cases showed upper limb swelling that was variable in location, and 3 had nonspecific upper limb crepitus. Ultrasonography revealed evidence of diaphyseal (n = 6), greater trochanteric (2), capital physeal (2), and distal femoral (2) fractures. Fracture movement during limb manipulation or weight shifting was sonographically visualized in 5 animals. Radiography confirmed fractures in 3 of 8 animals: 2 bovines with distal femoral fractures detected on standing projections and 1 capital physeal fracture that required ventrodorsal projections under general anesthesia. All animals were euthanized (11) or slaughtered (1 bovine). Postmortem examination confirmed ultrasonographic findings in 10 of 10 necropsied animals., Clinical Relevance: Femoral fractures were not localized nor confirmed in any case prior to ultrasonography. Study findings supported the use of ultrasonography for rapid patient-side diagnosis, prognostication, and decision-making in suspect cases.

Animal posture, limb gait, and body weight-bearing in dogs can be evaluated by limb gait score. In this study, nine adult male dogs of local breed were used to induce a complete transverse femoral mid-shaft fracture fixed internally by intramedullary pining under general anesthesia with the aseptic technique and followed for 60 days postoperative. The data were analyzed, including five degrees that indicate the correlation among animals' posture, limbs, and body weight tolerance per day. The results demonstrated that in grade 5, the animals completely hold the affected limb during standing position 1 st -3 rd day postoperative. From the 4 th -10 th day postoperative, in grade 4, the animals supported the body weight on the affected limb in the standing position and hold it during waking. In grade 3, from 11 th -21 th day postoperative, the operated animals supported body weight on the affected limb in slow waking and hold it in speed waking and running. From the 22 nd -28 th day postoperative, in grade 2, the animals used the limb in speed walking, from the 29 th -35 th day postoperative. In grade1, the animals could use the limb in running from the 36 th -2 nd day postoperative. In grade 0, the animals used the limb normally in walking, running, and jumping until the end of experimental periods (60 th day postoperative). The results indicated that limb gait scores in dogs can be used for the evaluation of the relationships among animals' posture, limb gait, and body-weight bearing per day during bone regeneration processing of femur fracture fixed by intramedullary pining.

Practical Relevance: The femur is the most commonly fractured bone in cats. Femoral fractures usually result from high-velocity trauma such as a road traffic accident or fall from a height and, as such, are associated with a wide variety of concurrent injuries. The initial focus of treatment should always be on assessment and stabilisation of the major body systems. Once any concurrent injuries have been addressed, all femoral fractures need surgical stabilisation, with the notable exception of greenstick fractures in very young cats, which can heal with cage rest alone. A number of different surgical options are available depending on the fracture type, location, equipment, surgeon experience and owner finances., Clinical Challenges: Femoral fractures can vary hugely in complexity and the small size of feline bones can limit the choice of implants. Furthermore, cats can present unique challenges in the postoperative period due to their active nature and the limited means to control their exercise level., Audience: This review is aimed at general and feline-specific practitioners who have some experience of feline orthopaedics, as well as those simply wishing to expand their knowledge., Aims: The aim of this review is to help clinicians assess, plan and manage feline femoral fractures. It provides an overview of diagnostic imaging and a discussion of a range of suitable surgical options, including the principles of different types of fixation. It also highlights cat-specific issues, approaches and implants pertinent to the management of these cases., Evidence Base: A number of original articles and textbook chapters covering many aspects of femoral fractures in cats and dogs have been published. Where possible, this review draws on information from key feline research and, where necessary, extrapolates from relevant canine literature. The authors also offer practical guidance based on their own clinical experience.

The cross-pin technique for the treatment of distal femoral physis fractures (specifically, Salter-Harris Type I fractures) was investigated using femurs collected from beagle cadavers. The pin was inserted from the medial surface of the femur at an inclination of approximately 30 to 45° relative to the long axis of the femur in the anteroposterior direction; the pin exit was set proximal to the origin of the long digital extensor tendon. Digital and radiographic images of the femur in the anteroposterior and lateral directions were obtained. In both types of images, the insertion angle of the pin relative to the long axis was measured. Results suggest that when inserting a pin proximal to the fracture line, the ideal position can be achieved by inclining the pin approximately 20° cranially relative to the long axis of the lateral direction of the femur, in addition to the previously described criteria., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

The use of lag screws to treat femoral condyle fractures is common, and their placement in surgery is technically demanding. Intra-articular screw impingement is a serious complication that may occur during surgical treatment of femoral condyle fractures. Here, we describe the case of a 3-year-old 40-kg dog which experienced recurrent lameness 6 mo after successful surgical treatment of a comminuted medial femoral condyle fracture due to an intra-articular non-loosening screw causing joint impingement. Removal of the conflicting screw was performed arthroscopically, based on its ability to offer minimally invasive access to the stifle joint. Six months after removal of the screw, the dog had full recovery without limitations to range of motion or stifle pain. To our knowledge, this is the first report on the use of arthroscopy to remove an intra-articular screw causing joint impingement after distal femoral fracture repair in a dog., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

Background: Fractures of the distal femoral physis are the most common physeal fracture sustained by skeletally immature dogs. Reduction and stabilization of these fractures can sometimes be achieved through closed reduction, primarily in fractures that are nominally displaced. Circular external fixator constructs have been used to assist in indirect, closed reduction of fractures at other anatomic locations in dogs and this report describes application of this method to reduce a displaced Salter-Harris type II fracture of the distal femur in a 1-year-old dog., Case Description: A 1-year-old female spayed Akita was referred for treatment of a Salter-Harris type II fracture of the right distal femur. The epiphyseal segment was laterally and slightly caudally displaced. Multiple attempts to manually reduce the fracture during surgery were unsuccessful, so a two-ring circular external fixator construct was applied to facilitate distraction and reduction. The construct was applied by placing a medial-to-lateral Kirschner wire in both the mid-femoral diaphysis and in the distal femoral epiphysis. Distraction of the construct provided sufficient separation of the fracture segments to facilitate near anatomic reduction. The fracture was stabilized with two percutaneously placed Steinmann pins placed in Rush fashion. Radiographic union was confirmed 5 weeks after surgery. The dog was not lame and was bearing more weight on the right pelvic limb, as assessed using force plate analysis, 9 months following surgery. Goniometric measurements of stifle range of motion and thigh muscle circumference were similar between the pelvic limbs., Conclusion: Application of a two-ring circular construct would appear to be useful to facilitate closed reduction and percutaneous stabilization of distal femoral physeal fractures., Competing Interests: The corresponding author teaches continuing education courses for IMEX Veterinary Inc. The other authors have no conflict of interest to declare relative to the work presented here.

Signalment, clinical features, fixation techniques, complications, and outcome for dogs presenting with distal diaphyseal and supracondylar femoral fractures were retrospectively reviewed. A total of 45 dogs with unilateral femoral fractures were included. Supracondylar femoral plates were the most popular method of fixation. However, various fixation techniques resulted in favorable outcomes in most dogs with 19/45 cases achieving full function and 22/45 achieving acceptable function. Degree of fracture comminution did not appear to affect complication rate or be a surrogate for worse clinical outcome., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

This report describes comminuted fractures in 2 cats repaired by stabilization with cortical bone allografts that had been preserved in honey. Both cats exhibited appropriate post-operative weight-bearing. Preservation of bone in honey is a simple and widely available alternative for bone banking. This is the first report of a bone defect in cats repaired with bone preserved in honey.

OBJECTIVE To compare stiffness and resistance to cyclic fatigue of two 3.5-mm locking system plate-rod constructs applied to an experimentally created fracture gap in femurs of canine cadavers. SAMPLE 20 femurs from cadavers of 10 mixed-breed adult dogs. PROCEDURES 1 femur from each cadaver was stabilized with a conical coupling plating system-rod construct, and the contralateral femur was stabilized with a locking compression plate (LCP)-rod construct. An intramedullary Steinmann pin was inserted in each femur. A 40-mm gap then was created; the gap was centered beneath the central portion of each plate. Cyclic axial loading with increasing loads was performed. Specimens that did not fail during cyclic loading were subjected to an acute load to failure. RESULTS During cyclic loading, significantly more LCP constructs failed (6/10), compared with the number of conical coupling plating system constructs that failed (1/10). Mode of failure of the constructs included fracture of the medial or caudal aspect of the cortex of the proximal segment with bending of the plate and pin, bending of the plate and pin without fracture, and screw pullout. Mean stiffness, yield load, and load to failure were not significantly different between the 2 methods of stabilization. CONCLUSIONS AND CLINICAL RELEVANCE Both constructs had similar biomechanical properties, but the conical coupling plating system was less likely to fail than was the LCP system when subjected to cyclic loading. These results should be interpreted with caution because testing was limited to a single loading mode.

The objective was to review surgical techniques and postoperative complications of surgical correction for patellar luxation (PL) in cats. A retrospective study evaluating 85 surgeries in 71 cats was performed. The records from four referral centres were searched for cats with surgical management of PL. Signalment, history, PL grade and direction, corrective surgical techniques and outcome were retrieved. Binary logistic regression analysis was used to interrogate relationships between case features, surgical correction methods and outcomes. The outcomes were classified as minor and major complications (requiring revision surgery), including continued PL (reluxation). Postoperative complications occurred in 26% of cases; 20% had major complications, including 5% patellar reluxation, and 6% had minor complications. Cats with previous ipsilateral femoral fracture were significantly more likely to suffer complications, including minor (P = 0.02, odds ratio = 12.67), major (P = 0.03, OR = 7.2) and patellar reluxation (P = 0.01, OR = 19.25). Minor complications were significantly more likely with grade 4 PL (P = 0.03, OR = 8.5). Major complications were significantly more likely with tibial tuberosity transposition (TTT; P = 0.03, OR = 5.57). Patellar reluxation was significantly more likely if stifle surgery had been performed previously (P = 0.05, OR = 8.00). The presence of bilateral PL, hip dysplasia, grade 1, 2 or 3 PL, corrective surgery using an anti-rotational suture or femoral sulcoplasty did not influence complications. Complications were more likely for grade 4 PL, previous ipsilateral femoral fracture, if TTT was performed and for cases with previous stifle surgery. This information allows consideration of risks and complicating factors., (© ISFM and AAFP 2014.)

Objective: To evaluate the postoperative analgesic effects of epidural administration of morphine and neostigmine, either alone or in combination, in dogs., Animals: 30 dogs undergoing orthopedic surgery on a pelvic limb., Procedures: Anesthetic protocols were standardized. At the end of surgery, 10 dogs each received 1 of 3 epidural treatments: morphine (0.1 mg/kg), neostigmine (5 μg/kg), or morphine plus neostigmine (0.1 mg/kg and 5 μg/kg, respectively). Postoperative pain scores and the need for rescue analgesia were evaluated for 24 hours., Results: Pain scores were higher in the neostigmine group, compared with scores for the morphine-neostigmine group, at 2 and 24 hours after surgery and higher in the morphine group than in the morphine-neostigmine group at 2 and 4 hours. During 24 hours, rescue analgesia was provided for 4, 7, and 2 of 10 dogs each in the morphine, neostigmine, and morphine-neostigmine groups, respectively. The number of dogs given rescue analgesia was significantly different among groups at 2, 3, 4, and 6 hours after surgery. Dogs in the morphine and morphine-neostigmine groups had a lower probability of receiving rescue analgesia within 24 hours than did dogs in the neostigmine group., Conclusions and Clinical Relevance: When administered epidurally, morphine alone or in combination with neostigmine provided effective postoperative analgesia in most dogs after orthopedic surgery, whereas neostigmine alone did not. Findings for this study suggested a potential role for neostigmine as an adjuvant for epidural analgesia in dogs undergoing orthopedic surgeries on the pelvic limbs.

Background: There are several factors that can affect the fatigue life of a bone plate, including the mechanical properties of the plate and the complexity of the fracture. The position of the screws can influence construct stiffness, plate strain and cyclic fatigue of the implants. Studies have not investigated these variables in implants utilized for long bone fracture fixation in dogs and cats. The purpose of the present study was to evaluate the effect of plate working length on construct stiffness, gap motion and resistance to cyclic fatigue of dog femora with a simulated fracture gap stabilized using a 12-hole 2.4 mm locking compression plates (LCP). Femora were plated with 12-hole 2.4 mm LCP using 2 screws per fracture segment (long working length group) or with 12-hole 2.4 mm LCP using 5 screws per fracture segment (a short working length group)., Results: Construct stiffness did not differ significantly between stabilization techniques. Implant failure did not occur in any of the plated femora during cycling. Mean ± SD yield load at failure in the short plate working length group was significantly higher than in the long plate working length group., Conclusion: In a femoral fracture gap model stabilized with a 2.4 mm LCP applied in contact with the bone, plate working length had no effect on stiffness, gap motion and resistance to fatigue. The short plate working length constructs failed at higher loads; however, yield loads for both the short and long plate working length constructs were within physiologic range.

Objective: To assess the analgesic effects of 2 doses of meloxicam on the degree of postoperative orthopedic pain in pigeons., Animals: 21 domestic pigeons (Columba livia)., Procedures: In each bird, a standardized osteotomy of 1 femur was performed and the fracture was immobilized with an intramedullary pin. Birds were randomly allocated to receive saline (0.9% NaCl) solution (control) or meloxicam (0.5 mg/kg [low dose] or 2.0 mg/kg [high dose]). The first treatment was administered i.m. after surgery was completed. Subsequent treatments were administered p.o. every 12 hours for 9 days. Degree of postoperative pain was assessed for the first 4 days after surgery by use of 3 methods: an electronic perch for assessment of weight-bearing load differential of the pelvic limbs, 4 pain scales, and analysis of video-recorded partial ethograms for bird activity and posture., Results: No significant differences were observed between the control group and the low-dose meloxicam group in any tested variable. The high-dose meloxicam group had a greater degree of weight bearing on the affected limb from the second to the fourth postoperative day as well as lower pain scores for at least the first 2 postoperative days, compared with the other groups. Return to presurgical behavior was achieved faster in pigeons that received high-dose meloxicam than in the other groups. No adverse effects were observed., Conclusions and Clinical Relevance: Administration of meloxicam at 0.5 mg/kg appeared ineffective in minimizing postoperative orthopedic pain in pigeons, but the 2.0 mg/kg dose provided quantifiable analgesia that appeared safe in this species in experimental conditions.

Objective: To validate a model of postfracture pain in perching birds., Animals: 21 adult domestic pigeons (Columba livia)., Procedures: In each bird, a standardized osteotomy of 1 femur was performed and the fracture was immobilized with an intramedullary pin. Degree of postoperative pain was evaluated 6 times/d for 4 days by use of 3 methods: an electronic perch for assessment of weight-bearing load differential of the pelvic limbs, 4 numeric rating pain scales for assessment of pain (all of which involved the observer in the same room as the bird), and analysis of video-recorded (observer absent) partial ethograms for bird activity and posture. Measurements obtained were compared with data collected before the surgery to evaluate the ability of these methods to detect pain., Results: The weight-bearing load differential was a sensitive, specific, reliable, and indirect measure of fracture-associated pain in the model used. Two of 4 tested pain scales (fractured limb position and subjective evaluation of degree of pain) were sensitive and specific for detecting pain and were reliable in a research setting. Interobserver reliability of the 4 pain scales was excellent. Partial ethograms were sensitive for identifying pain-associated behavior in pigeons, particularly during the first 2 days after surgery., Conclusions and Clinical Relevance: The fracture pain model was reliable and reproducible and may be useful for experimental studies involving postsurgical pain in pigeons. Weight-bearing load differential was the most sensitive and specific means of determining degree of pain in pigeons during the first 4 days after hind limb fracture induction.

A 7-year-old male, castrated, domestic shorthair cat was presented with a plantigrade stance of the left pelvic limb. An avulsion of the lateral head of the gastrocnemius muscle was diagnosed based on clinical examination and radiographic assessment. Surgical reduction and fixation were achieved with modified locking loop sutures through bone tunnels in the supracondylar tuberosity of the distal femur. Additionally, a temporary calcaneotibial positional screw was placed in order to neutralise forces on the gastrocnemius muscle. No postoperative complications were encountered and the cat made a full recovery., (Copyright © 2011 ISFM and AAFP. Published by Elsevier Ltd. All rights reserved.)

Background: This prospective experimental study evaluated the surgical procedure and results of modular hybrid total hip arthroplasty in dogs., Methods: Ten skeletally mature healthy mongrel dogs with weights varying between 19 and 27 kg were used. Cemented modular femoral stems and uncemented porous-coated acetabular cups were employed. Clinical and radiographic evaluations were performed before surgery and at 30, 60, 90, 120, 180 and 360 days post-operation., Results: Excellent weight bearing was noticed in the operated limb in seven dogs. Dislocation followed by loosening of the prosthesis was noticed in two dogs, which were therefore properly treated with a femoral head osteotomy. Femoral fracture occurred in one dog, which was promptly treated with full implant removal and femoral osteosynthesis., Conclusions: The canine modular hybrid total hip arthroplasty provided excellent functionality of the operated limb.

A 4-mo-old, 185-kg male giraffe (Giraffa camelopardalis reticulata) was presented due to stifle effusion and lameness of 3-wk duration. Radiographs revealed a fracture of the extensor fossa of the lateral trochlear ridge of the femur at the origin of the peroneus tertius. Under anesthesia, dysfunction of the reciprocal apparatus was documented by flexing the stifle while the tarsus remained extended. An avulsion fracture of the origin of the peroneus tertius and extensor digitorum longus muscle was diagnosed. An exploratory arthroscopy of the femorotibial joint was followed by arthrotomy to excise the large bone fragment from its soft tissue attachments. Because of the fractious temperament of the animal, postoperative care was restricted to stall rest for 3 mo, and no postoperative complications arose. Only a mild residual lameness remained by 6 mo after surgery.

Objective: To describe the use of a novel intramedullary interlocking nail for femoral fracture repair in newborn calves and outcome associated with this treatment modality., Design: Retrospective case series., Animals: 25 calves., Procedures: Medical records from calves referred for femoral fracture repair between November 2008 and June 2009 were included. Signalment, clinical findings, and results of lameness examination and complete radiographic examination were recorded. Details of surgical technique, orthopedic fixation, associated complications, and outcome were also noted., Results: 25 Charolais calves were included in the study. All fractures were closed and located in the diaphysis; 18 extended to the distal metaphysis, 1 was located proximally, and 6 were midshaft fractures. Fractures were localized to the left femur in 17 calves and to the right femur in 8 calves. An interlocking nail was used as the sole means of internal fixation in 16 calves and was reinforced in 9 calves. Two calves were euthanatized for reasons related to the surgery, and 4 died of unrelated reasons. Long-term prognosis was considered excellent for 15 calves and fair for 4 calves. Age, body weight, overall musculoskeletal strength at initial evaluation, affected limb, configuration and location of the fracture, need for reinforcement of the repair, and quality of the reduction had no significant association with positive outcome of the surgery., Conclusions and Clinical Relevance: The novel intramedullary interlocking nail used in the present study was associated with a good prognosis for surgical repair of femoral fractures in newborn calves regardless of the location of the fracture.

Objective: To design and manufacture free-form biodegradable polycaprolactone (PCL) bone plates and to compare mechanical properties of femoral constructs with a distal physeal fracture repaired by use of 5 stabilization methods., Sample Population: 40 canine femoral replicas created by use of additive manufacturing and rapid tooling., Procedures: Surgery duration, mediolateral and craniocaudal bending stiffness, and torsional stiffness of femoral physeal fracture repair constructs made by use of 5 stabilization methods were assessed. The implants included 2 Kirschner wires inserted medially and 2 inserted laterally (4KW), a commercial stainless steel plate (CSP), a custom free-form titanium plate (CTP), thin (2-mm-thick) biodegradable PCL plates (TNP) placed medially and laterally, and thick (4-mm-thick) PCL plates (TKP) placed medially and laterally., Results: Surgical placement of 4KW was more rapid than placement of other implants The mean caudal cantilever bending stiffness of CTP and CSP constructs was greater than that for TNP TKP and 4KW constructs, and the mean caudal cantilever bending stiffness of TNP and TKP constructs was greater than that for 4KW constructs. The mean lateral cantilever bending stiffness of TKP constructs was greater than that for 4KW constructs. Differences among construct types were not significant in yield strength, ultimate strength, yield torque, and ultimate torque., Conclusions and Clinical Relevance: The mechanical properties of fracture repair constructs made from free-form PCL biodegradable plates compared favorably with those of constructs made from Kirschner wires. The impact of PCL plates on musculoskeletal soft tissues, bone healing, and bone growth should be evaluated before clinical use.

Objective: To compare an electron beam melting-processed (EBMP) low-modulus titanium alloy mesh stem with a commercial cobalt-chromium (CC) stem in a canine cadaver model., Sample Population: 9 pairs of cadaver femora., Procedures: EBMP stems of 3 sizes were placed in randomly chosen sides of femora (left or right) and CC stems in opposite sides. Stem impaction distances were recorded. Five strain gauges were attached to the femoral surface to record transverse tensile (hoop) strains in the femur during axial loading. Constructs were axially loaded 4 times to 800 N and 4 times to 1,600 N in a materials testing machine. Axial stiffness of constructs and bone surface strains were compared between EBMP and CC constructs., Results: Stems were impacted without creating femoral fissures or fractures. Stem impaction distances were larger for EBMP stems than for CC stems. Mean axial stiffness of EBMP constructs was lower than mean axial stiffness of CC constructs. Subsidence did not differ between groups. Bone strains varied among strain gauge positions and were largest at the distal aspect of the stems. At a load of 1,600 N, bones strains were higher in CC constructs than in EBMP constructs for 2 of 4 medial strain gauges., Conclusions and Clinical Relevance: EBMP stems were successfully impacted and stable and led to a focal decrease in bone strain; this may represent an acceptable option for conventional or custom joint replacement.

This study describes the expression of CD44v6 in the bone development and is the first study of its kind to the authors' best knowledge. The CD44 family is a family of transmembrane glycoproteins that acts as cell adhesion molecules binding cells to other cells as well as cells to the extracellular matrix. It has been suggested that the CD44v6, a family member of CD44, is closely related to the osteosarcoma metastasis. In general, when cancer cells metastasize, they revert to their immature forms. In the present study, therefore, we have investigated CD44v6 and the standard form of CD44 (CD44st) in two types of immature forms of bone tissues: developmentally immature stages from fetuses to adults as well as experimentally immature stages using fracture models. CD44st expression was identified in osteoblasts, osteocytes, and in the peripheral portion of the bone matrix from the fetal to young ages of rats. Many more intense reactions for CD44v6 were observed in the bone matrix than CD44st in fetal stages. In experimental fracture models, positive immunoreactions to CD44st were clearly observed in the osteoblasts and osteocytes. CD44v6-positive immunoreactivity, however, was not detected in either osteoblasts or the bone matrix. In conclusion, CD44v6 is expressed in the embryonic stages and may be involved in the bone matrix formation as a matrix-associated ectodomain during normal ontogenetic development but not involved in the process of fracture healing.

The cause of an increased number of femoral fractures in market pigs from a single producer is described. Blood chemical, bone ash, radiographic, and feed analyses revealed that the fractures were caused by insufficient calcium in the diet. Associated economic and welfare implications are discussed.

Case Description: An adult male American bullfrog (Rana catesbeiana) was evaluated by the North Carolina State University College of Veterinary Medicine's Turtle Rescue Team following vehicular trauma., Clinical Findings: A fracture of the left femur was suspected on examination and palpation of the hind limbs, but no other injuries or abnormalities were detected. While the bullfrog was sedated, whole-body radiographic views were obtained, which revealed a closed midshaft comminuted fracture of the left femur., Treatment and Outcome: The fracture was repaired by use of an internal fixation technique that included Kirschner wires, a positive-profile pin secured along the femur with encircling sutures, and polymethylmethacrylate molded around the entire apparatus. There were no major complications during the postoperative rehabilitation period. One year after surgery, radiography revealed complete fracture healing and the bullfrog was released back into the wild., Clinical Relevance: Presently, there are no widely accepted methods for fracture fixation in amphibians. Factors associated with their aquatic environment and lengthy fracture healing time must be addressed when planning fracture fixation strategies. In the bullfrog of this report, the applied internal fixation method provided effective long-term stabilization of the femur, allowed for normal movement, and enabled the bullfrog to be housed in an aquatic environment immediately after surgery.

A 4.5-month-old, male domestic shorthair was presented with bilateral femoral fractures after falling from a low height. Radiographs revealed reduced radio-opacity and thin cortices of all long bones. A presumptive diagnosis of osteodystrophy, secondary to osteogenesis imperfecta, was made on postmortem examination.

Objective: To determine outcome for dogs and cats with diaphyseal fractures in which a plate-rod construct was used for fracture repair., Design: Retrospective study., Animals: 35 dogs and 12 cats., Procedures: Medical records and radiographs were reviewed to obtain information concerning signalment, fracture severity, construct design, time to radiographic union, complications, and outcome. Clients were contacted by telephone to obtain information on complications, limb usage, and overall satisfaction with the procedure., Results: 31 femoral, 9 humeral, and 7 tibial fractures were assessed. Thirteen fractures consisted of 2 fragments, 22 consisted of 3 to 5 fragments, and 12 consisted of > 5 fragments. Forty-six of 47 (98%) fractures reached union. Mean +/- SD times to radiographic union were 7.5 +/- 2.7 weeks for the dogs and 4.8 +/- 1.3 weeks for the cats. There were 4 short-term, minor complications and 15 long-term complications (2 major and 13 minor). Owners of 21 of 30 dogs (70%) and 9 of 12 cats reported that their animals had normal limb function. Twenty-six of 28 dog owners (93%) and 12 of 12 cat owners indicated that they were satisfied with results of the procedure. As surgery time increased, time to union also increased. Time to union for fractures with > 5 fragments was significantly shorter than time to union for fractures with < or = 5 fragments., Conclusions and Clinical Relevance: Results suggest that plate-rod constructs can successfully be used for repair of diaphyseal fractures of a wide range of severity in dogs and cats.

A 2-year-old sexually intact male Paint horse weighing 427 kg (940 lb) was admitted for examination and treatment of intermittent non-weight-bearing lameness of the right hind limb of 1 week's duration. Radiography revealed a displaced Salter-Harris type-III fracture of the right femoral condyle with the sagittal component of the fracture line located in the intercondylar space and the transverse component exiting on the medial aspect of the femur. The fracture was repaired with a condylar screw plate designed for repair of femoral condylar fractures in humans. The owner reported by telephone 9 months after surgery that the horse was sound. To our knowledge, use of this particular implant system for fixation of a Salter-Harris type-III fracture on the medial side of the femur in a horse has not been described. Results in this horse suggest that this implant can be successfully used for repair of femoral condylar fractures in selected adult horses.

Microscopic and radiographic observations, as well as ash, calcium, phosphorus, copper, manganese, and zinc concentrations, were evaluated from femora of 32- to 35-wk-old male turkeys from two different farms (A and B). Turkeys from Farm A were divided into birds with femoral fracture (AF) and without femoral fracture (ANF). Turkeys from Farm B did not have femoral fractures (BNF). In the mid-diaphyseal cortex of turkeys without femoral fractures, collagen fibers were evenly distributed parallel to the transverse plane of bone surface. In contrast, collagen fibers were disorganized and the cortex was osteoporotic in turkeys with femoral fractures. Each turkey with femoral fractures also had callus on the mediocaudal region of the femoral middiaphysis. The periosteal callus was interrupted at the insertion of the puboischiofemoralis muscle. Muscle attachment to the bone might have interfered with the formation of periosteal callus. The concentration of calcium was lower in the cortex of turkeys in group AF compared to turkeys in groups ANF and BNF. The focal nature of the callus, along with the low levels of calcium, is indicative of a local repair response with alteration in cortical structure and altered concentrations of minerals in the cortex. These changes in the bone and the routine handling of the birds might have predisposed the turkeys to complete fractures of the femur.

An adult female llama with a comminuted fracture of the left femoral head was necropsied. A firm multinodular mass infiltrated skeletal muscle adjacent to the fracture. Multiple, firm, white nodules were in the pulmonary parenchyma and pleura. A single nodule was in the liver. Microscopically, transition from nonneoplastic bronchiolar epithelium to neoplastic epithelium that formed acinar structures was evident at bronchioloalveolar junctions. A diagnosis of pulmonary adenocarcinoma was made. Similar neoplastic tissue was in the liver and in the perifemoral mass. Immunohistochemically, neoplastic cells were positive for pan-cytokeratin, cytokeratin 7, and cytokeratin 5/6 antibodies and negative for vimentin and cytokeratins 8/18 and 20.

Objective: To determine the outcome of femoral fractures repaired with 4.0- and 4.7-mm interlocking intramedullary nails in cats., Design: Retrospective study., Animals: 12 cats with diaphyseal femoral fractures., Procedure: Records of all cats in which the 4.0- and 4.7-mm interlocking nail system was used for repair of diaphyseal femoral fractures at the Animal Medical Center and Florida Veterinary Specialists between 1996 and 2000 were reviewed. Information included signalment, type of fracture, size of the implant, details of the surgery, intra- and postoperative complications, fracture healing, and clinical outcome., Results: Femoral fractures in 12 cats were repaired. Eleven of the fractures were comminuted, with 2 of these being open. Clinical outcome was excellent in 7 cats, good in 3, and fair in 1. One resulted in a nonunion. Complications included screw breakage (1 cat) and fracture distal to the nail (1). Fracture distal to the nail occurred from a second trauma., Conclusion and Clinical Relevance: Use of the interlocking nail has been limited in cats because of the small diameter of the medullary canal. Use of the 4.0-mm nail will allow for greater application of this implant in small patients. Results of this study indicate that the 4.0- and 4.7-mm interlocking nails can be used to repair simple or comminuted diaphyseal femoral fractures in cats.

Objective: To determine clinical and radiographic findings, treatment, and outcome for llamas with long-bone fractures., Design: Retrospective study., Animals: 6 llamas., Procedure: Medical records of llamas admitted between 1993 and 1998 because of long-bone fractures were reviewed. Data collected included age, sex, type of fracture, method of fracture repair, and postoperative complications. The Fisher exact test was used to compare age and sex of the llamas with long-bone fractures with those of the hospital population of llamas. All owners were contacted by telephone to determine perceived postoperative problems and whether the llamas were able to perform as expected., Results: Mean age was 160.8 days (range, 23 to 365 days). There was 1 male and 5 females. Fractures were more likely to occur in young llamas (< or = 1 year old) than in adults. Five of the fractures were attributed to traumatic episodes. Long bones affected included the tibia (n = 2), radius (2), femur (1), and humerus (1). Internal fixation with lag screws, plating, or both was performed on fractures of all llamas except 1; that llama was treated by use of confinement to a stall. None of the llamas had intraoperative complications, but postoperative complications were reported in 2 llamas. All fractures healed eventually, and clients were pleased with outcomes., Conclusions and Clinical Relevance: Long-bone fractures in llamas are uncommon. Several types of long bone fractures can be successfully repaired by use of internal fixation, resulting in few complications and minimal convalescent time.

Morphologic and torsional mechanical properties of femora were evaluated in three groups of turkeys to determine whether turkeys that incurred femoral fracture have different radiographic, morphologic, and torsional mechanical properties than do turkeys without femoral fracture, and if body weight was a factor differentiating affected and nonaffected turkeys. Nine turkeys with unilateral femoral fractures and nine turkeys without fractures from Farm A were compared with a group of nine age and genetically matched turkeys from Farm B. Turkeys from Farm A were 10 to 25% heavier (26.2+/-0.9 kg) and turkeys from Farm B were 10% lighter (18.2+/-0.9 kg) than expected breed standards. Femoral length, cortical thickness, medullary diameter, and diaphyseal curvature were measured from craniocaudal and lateromedial radiographs. One intact femur from each of five turkeys with a contralateral femoral fracture (Farm A), nine unaffected turkeys from Farm A, and nine turkeys from Farm B were subjected to failure in a torsion test. Geometric and mechanical results were compared. Turkeys from Farm A had a thicker cortex and a smaller medullary diameter than turkeys from Farm B. Turkeys from Farm A had significantly lower torsional stiffness and failure torque values compared with turkeys from Farm B, when differences in body weight were accounted for (analysis of covariance, P < 0.05). Mechanical failure torque calculated from geometric values suggests that organic or inorganic material arrangement and composition may be responsible, in part, for differences between groups. Femoral fractures may be associated with insufficient skeletal adaptation to heavy body weight.

Twenty-two 32-to-35-wk-old male turkeys from a commercial breeding flock were presented to the California Veterinary Diagnostic Laboratory System, Fresno Branch, with a clinical complaint of lameness and increased mortality. Necropsy findings included a unilateral, closed oblique fracture involving the femur in 12 birds. Ten complete femoral fractures had periosteal new bone adjacent to and bridging the fracture. Periosteal callus formation, in this case, suggested that preexisting lesions preceded complete fracture of the femur. Factors such as selection for heavy body weight, lack of exercise, and handling might have contributed to the development and promotion of complete fractures.

This is the first report on successful treatment of spontaneous nonunion fracture of a dog by use of recombinant human bone morphogenetic protein-2 (rhBMP-2). A 4-year-old Pomeranian dog with a 2-year history of femoral nonunion fracture was treated with implantation of rhBMP-2. The dog had received surgical correction twice prior to the admission but radiography of the affected limb revealed a typical figure of nonunion fracture. Glossly, the fractured ends were sclerotic and the area between the ends was filled with fibrous tissue. After debridement the femoral shaft was fixed by an 8-hole plate. rhBMP-2 at a total dose of 256 micrograms was implanted with a synthetic carrier into the 8-mm defect formed by the debridement. Callus formation responding to rhBMP-2 was radiographically observed at 2 weeks after implantation and the defect reached radiographic union by 8 weeks after implantation. The plate was removed at 9 months after implantation. Any complications were not observed for 5 months after removal of the plate.

We have developed an interlocking intramedullary nail method for the treatment of femoral and tibial fractures and used this method for the treatment of 7 cats and 6 dogs with these fractures. The interlocking nails, with a diameter of 4-6 mm and length of 60-140 mm, have holes at 10 mm intervals for screwing. The nail placed on the insertion device was inserted into the marrow cavity from the end of the fractured bone in the usual procedures for intramedullary fixation, then fixed by screws at the distal and proximal ends with a jig which was also attached to the insertion device. Animals were able to bear weight on the treated legs within three days, and the prognosis was excellent.

Transverse diaphyseal fractures of the femur were experimentally made in immature cats, and were fixed by an intramedullary pinning technique using an uniaxially oriented poly-L-lactide (PLLA) rod, a biodegradable polymer. The healing process was evaluated radiographically and histologically. Formation of bony callus was completed in 8 weeks, and cortical bony union followed. The remodeling process was then observed form 12 to 16 weeks. The healing process was almost the same as when a metallic implant was used. Abundant periosteal callus formation may be attributable to the lower elasticity of the PLLA rod compared with metallic implants. Since no other abnormalities such as growth deformities were detected, it was concluded that the combined use of a uniaxially oriented PLLA rod and an external splint is clinically useful for the repair of diaphyseal fractures in immature cats.