Numerical evaluation of internal femur osteosynthesis based on a biomechanical model of the loading in the proximal equine hindlimb.

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.

Repair of femoral fractures in calves via external skeletal fixator with intramedullary pin tie-in.

OBJECTIVE: To describe the success rate and associated complications of external skeletal fixator/intramedullary pin tie-in for calf femoral fracture fixation. STUDY DESIGN: Clinical retrospective. ANIMALS: Ten calves, less than 30 days old, with diaphyseal/metaphyseal femoral fractures. METHODS: Medical records were reviewed from the University of Wisconsin from 2000 to 2020. Fractures were repaired using open reduction and fixation. An intramedullary Steinman pin was placed, exiting near the greater trochanter, and utilized for fracture reduction. Bicortical transfixation pins were placed distal and proximal to the fracture site. Poly(methyl methacrylate) (PMMA)-filled tubing connected the transfixation pins and proximal intramedullary pin, creating a Type 1a external skeletal fixator (ESF) tie-in. Follow up was obtained via medical records and phone interviews. RESULTS: Short-term survival rate was 7/10 (70%). Postanesthetic death occurred once. Postoperative complications occurred in all remaining cases. The most common findings were transfixation pin tract lucency and lameness (6/9 cases), implant dysfunction (5/9 cases), and infection (4/9 cases). Three of five cases with long-term follow up survived; all went on to productive careers. CONCLUSION: Although patients were prone to postoperative complications, short-term survival was comparable to previous reports. CLINICAL SIGNIFICANCE: The external skeletal fixator/intramedullary (ESF/IM) pin tie-in is less expensive and offers comparable success rates to other methods, providing a lower cost option for calf femoral fracture repair.

Minimally invasive plate osteosynthesis of femoral fractures with 3D-printed bone models and custom surgical guides: A cadaveric study in dogs.

OBJECTIVE: Assess the accuracy and efficiency of reduction provided by application of plates precontoured to 3-dimensional (3D)-printed femoral bone models using a custom fracture reduction system (FRS) or intramedullary pin (IMP) to facilitate femoral minimally invasive plate osteosynthesis (MIPO) in dogs. STUDY DESIGN: Experimental cadaveric study. SAMPLE POPULATION: Seven dog cadavers. METHODS: Virtual 3D femoral models were created using computed tomographic images. Simulated, virtual mid-diaphyseal femoral fractures were created and reduced. Reduced femoral models were 3D-printed and a plate was contoured. Custom drill guides for plate screw placement were designed and 3D-printed for the FRS. Mid-diaphyseal simulated comminuted fractures were created in cadavers, and fractures were aligned using FRS or IMP and stabilized with the precontoured plates. Number of fluoroscopic images acquired per procedure and surgical duration were recorded. Computed tomographic scans were repeated to assess femoral length and alignment. RESULTS: Compared to the preoperative virtual plan, median change in femoral length and frontal, sagittal, and axial alignment was less than 3 mm, 2°, 3°, and 3° postoperatively, respectively, in both reduction groups. There was no difference in length or alignment between reduction groups (P > .05). During FRS, fewer fluoroscopic images were taken (P = .001), however, surgical duration was longer than IMP procedures (P = .011). CONCLUSION: Femoral alignment was accurate when using plates precontoured to 3D printed models, regardless of reduction method. CLINICAL SIGNIFICANCE: Accurate plate contouring using anatomically accurate models may improve fracture reduction accuracy during MIPO applications. Custom surgical guides may reduce fluoroscopy use associated with MIPO.

Closed reduction and fluoroscopic-guided percutaneous pinning of femoral capital physeal or neck fractures: Thirteen fractures in 11 dogs.

OBJECTIVES: To report the short-term clinical outcome and complications in dogs that underwent surgical repair of femoral capital physeal or neck fractures via fluoroscopic-guided percutaneous pinning (FGPP). STUDY DESIGN: Retrospective case series. ANIMALS: Client owned dogs (n = 11) with femoral capital physeal or neck fractures (n = 13). METHODS: Records (July 2018-July 2021) of dogs that underwent surgery for femoral capital physeal or neck fracture repair with FGPP from two hospitals were reviewed. Data collected included signalment, age, weight, preoperative lameness severity, fracture factors (etiology, Salter-Harris classification, time from injury to surgery, radiographic displacement), surgical factors (surgery time, number/size of implants, reduction quality) and outcome (follow-up examination findings, radiographic findings, complications). RESULTS: Most fractures (11/13) occurred secondary to trauma. The median time from injury to surgery was 5.5 days. There was mild radiographic displacement preoperatively in 10/13 fractures. Satisfactory fracture healing and limb function was achieved in 10/13 femurs. Complications occurred in 5/11 cases and included intra-articular implants, implant failure/nonunion, implant migration (2), and malunion. Of these five complications, two resolved with implant removal, and a salvage procedure was recommended in the remaining cases. Of the three cases requiring salvage procedures, two originally presented with radiographic evidence of fracture chronicity. CONCLUSIONS: FGPP can be used to successfully treat femoral head and neck fractures with appropriate case selection and precise surgical technique.

Clinical outcomes of canine total hip replacement utilizing a BFX lateral bolt femoral stem: 195 consecutive cases (2013-2019).

OBJECTIVE: To evaluate the clinical outcomes of total hip replacements (THR) utilizing a BFX lateral bolt stem in dogs with coxofemoral joint disease. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: A total of 149 dogs representing 195 THR. METHODS: Consecutive THRs utilizing a BFX lateral bolt stem were studied. Preoperative, immediate postoperative, 1-, 2-, 3-, 4-, and 12-month postoperative radiographs were performed. All major and minor complications, revisions, outcomes, subsidence, canal flare index (CFI) were recorded. RESULTS: An intraoperative complication rate of 11.8% was observed. The postoperative complication rate was 13.6%, with 9.2% major and 4.4% minor complications. Complications included: postoperative femur fractures (3.6%), coxofemoral luxation (3.6%), stem failure (0.5%), septic loosening (0.5%), aseptic loosening (0.5%), and acetabular fracture (0.5%). Three dogs underwent prophylactic plating after subjective assessment of cortical thickness. Five of 195 (2.6%) cases underwent explant of their prostheses (median = 3 months). Mean stem subsidence at 1 month postoperatively was 1.22 ± 0.16 mm. An increased CFI was associated with postoperative femur fractures (p < .05). A total of 190 of 195 (97.4%) cases returned to normal function in the long-term follow-up period. CONCLUSION: Use of the BFX lateral bolt stem resulted in minimal postoperative subsidence, a low femoral stem complication rate, and a high rate of achieving normal limb function. CLINICAL SIGNIFICANCE: The BFX lateral bolt stem should be considered in canine THR as the femoral failure rate is low and the long-term success rate is high.

Outcome of canine cementless collared stem total hip replacement with proximal femoral periprosthetic cerclage application: 184 consecutive cases.

OBJECTIVE: To report outcomes of cementless collared stem total hip replacement (THR) with proximal femoral periprosthetic cerclage application in dogs. STUDY DESIGN: Retrospective case series. ANIMALS: Client-owned dogs (n = 150) with THR (n = 184). METHODS: Serial postoperative radiographs and medical records of dogs that underwent consecutive index cementless THR, with a single full cerclage wire placed distal to the femoral neck osteotomy line and proximal to the lesser trochanter, were reviewed for intraoperative and postoperative complications. RESULTS: No proximal femoral fractures occurred. No complications associated with the use of the cerclage wire were encountered. A fissure (n = 1) or fractures (n = 2) occurred near the tip of the femoral stem in three cases postoperatively. All three cases required plate and screw fixation. All dogs returned to subjectively normal function at home and all owners were satisfied with the outcome. CONCLUSION: A single full cerclage wire may minimize the risk of a proximal femur fracture following cementless collared stem total hip replacement in dogs. No complications were encountered with the cerclage wire. CLINICAL SIGNIFICANCE: Application of a cerclage wire is a simple and economically feasible procedure that requires minimal additional instrumentation, takes little time, and may decrease the risk of proximal femur fractures after cementless press-fit THR.

Clinical application of the small I-Loc interlocking nail in 30 feline fractures: A prospective study.

OBJECTIVE: To describe medium-term functional outcome after nail osteosynthesis in feline traumatology and report clinically relevant recommendations for I-Loc angle-stable interlocking nail use in cats. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Client-owned cats (n = 29). METHODS: Consecutive cases with femoral, tibial, or humeral fractures were included. Outcome measures included fracture and surgical procedure description, limb alignment, nail size vs body weight (BW), percentage of nail medullary canal (MC) fill, time to limb function at clinical union (CU), and complications. Descriptive statistics were reported and compared with historical data. RESULTS: Bone distribution was 53.3% femora, 30% tibiae, and 16.7% humeri. There were six epimetaphyseal and 24 diaphyseal fractures. Overall, 67% of fractures were comminuted. Open reduction and minimally invasive techniques were used in 73% and 27% of cases, respectively. Seventeen I-Loc 3 (cat mean BW 4.4 ± 2.2 kg) and 13 I-Loc 4 (cat mean BW 5.2 ± 1.2 kg) nails were placed with mean MC fill of ≤50%. Average time to CU was 7.2 weeks. At CU, lameness had resolved or was mild in every cat, and all cats ultimately regained full limb function. No major complications were encountered. CONCLUSION: Because of improved CU times, excellent functional outcomes, and low complication rate, our results provide evidence that I-Loc nails are safe and effective for feline traumatology. CLINICAL SIGNIFICANCE: The I-Loc may be advantageous for fixation of epimetaphyseal fractures. Because of feline bone specific dimensional constraints, I-Loc 3 is likely appropriate for all feline humeri and most tibiae, while I-Loc 4 is well sized for feline femora.

Zürich cementless total hip arthroplasty as a treatment option for capital physeal fractures in dogs: Outcome in 53 cases.

OBJECTIVE: To review the outcome of dogs that underwent Zürich cementless total hip arthroplasty (Z-THA) for the repair of acute and chronic capital physeal fractures (CPF) and document the CPF-related hip remodeling. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Fifty-three Z-THA in 53 dogs. METHODS: Medical records of dogs (2006-2019) that underwent Z-THA for CPF management were reviewed. Dogs were divided into two groups on the basis of the days elapsed between CPF diagnosis and Z-THA, acute (≤30 days) and chronic (>30 days). Hip remodeling variables were determined from preoperative radiographs or intraoperatively. Descriptive statistics were performed, and the complication rates, outcome, and coxofemoral remodeling were recorded. Comparisons of remodeling variables and rates between groups were performed by using Fisher's exact test. RESULTS: In total, 23 of 53 (43.4%) cases were acute, and 30 of 53 (56.6%) cases were chronic. There was no difference in the femoral remodeling rates between the acute and chronic groups (P = .184), whereas acetabular remodeling was more prevalent in the chronic group (P < .001). Intraoperative complications occurred in four of 53 (7.5% [1/23 acute, 3/30 chronic]) cases, and postoperative complications occurred in six of 53 (11.3% [2/23 acute, 4/30 chronic]) cases. Good clinical outcomes were achieved in 51 of 53 (96.2% [21 acute, 30 chronic]) cases. CONCLUSION: Complication rates of Z-THA for CPF repair were similar to the complication rates reported for Z-THA of dysplastic hips. Hip remodeling was common regardless of CPF chronicity. CLINICAL SIGNIFICANCE: Zürich cementless total hip arthroplasty is viable for surgical management of CPF. There is a high likelihood that hip remodeling will be encountered, even in fractures treated within 30 days of presenting for hind limb lameness.

Arthroscopic removal of an intra-articular screw causing joint impingement after distal femoral fracture repair in a dog.

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.

Retrait par arthroscopie d'une vis causant un empiètement intra-articulaire après une ostéosynthèse du fémur distal chez un chien. Les fractures fémorales condyliennes sont communément stabilisées au moyen de vis de traction dont le placement peut s'avérer techniquement difficile. L'empiètement intra-articulaire induit par une vis est une complication sérieuse du traitement des fractures fémorales condyliennes. Nous décrivons dans le présent article le cas d'un chien de 3 ans et de 40 kg présenté pour une boiterie récidivante, 6 mois après le traitement d'une fracture comminutive du condyle fémoral médial, due à une vis causant un empiètement intraarticulaire. Le retrait de la vis est effectuée par arthroscopie étant donné que cela permettait un accès minimalement invasif au grasset. Six mois après l'arthroscopie, le chien présente une récupération orthopédique pleine sans douleur ni diminution de l'amplitude articulaire du grasset. Il s'agit du premier cas de retrait par arthroscopie d'une vis causant un empiètement intra-articulaire après une ostéosynthèse d'une fracture fémorale distale chez un chien.(Traduit par l'auteur).

A RETROSPECTIVE STUDY OF FEMORAL FRACTURES IN WILD BIRDS OF PREY: 119 CASES.

A retrospective study was performed to describe patient and fracture characteristics, treatments, complications, and outcomes associated with femoral fractures in free-ranging birds of prey. Cases were identified from the electronic database and included raptors admitted with femoral fractures at the Bird of Prey Clinic of the Université de Montréal, from 1986 to 2018. In total, 119 individuals from 24 species, with 123 femoral fractures, were included in the study. Twenty-seven birds (23%) were declared dead upon arrival. Ninety-two birds (77%) were admitted alive; 80 with acute fractures and 12 with a fracture that had already healed. A conservative treatment (cage rest) was used to manage eight fractures. Surgical repair was attempted on 34 femoral fractures in 33 birds. An intramedullary pin alone was used in 28 cases (82%), and an external skeletal fixator-intramedullary pin tie-in fixator was used in 6 cases (18%). For surgically treated fractures, 19 healed (in 18 birds), 4 did not heal, and 11 birds died or were euthanized before healing could be achieved. Of the 23/34 fractures where the healing process could be assessed, healing rate for comminuted fractures (11/23) was 91% (10/11). Surgical complications occurred in 10 cases (including 7 cases of migration and loosening of the pin, and 1 case of osteomyelitis), leading to euthanasia in 4 cases. Out of the 21 birds with acute femoral fracture upon presentation that were released, 14 had received a surgical treatment and 7 had received a conservative treatment. Nine of the 21 released birds (43%) had at least one other fractured bone. The majority of deaths and euthanasia occurred within 2 wk after admission (51/59; 86%). Thirteen birds were euthanized primarily because of their femoral fracture. Thirteen birds died in treatment and 33 were deemed nonreleasable and euthanized because of a comorbidity not related to the femoral fracture.

Locking plate femur fracture repair in a juvenile Western chimpanzee (Pan troglodytes verus) in Sierra Leone.

This case reports the successful management of a traumatic diaphyseal femoral fracture in an infant Western chimpanzee (Pan troglodytes verus) from a rescue centre in Sierra Leone using a 2.4-mm intramedullary pin and two 2.7-mm String of Pearls™ locking plates. Locking plate use has not been previously described in chimpanzees.

Development of a novel fracture fragment stabilization system for minimally invasive osteosynthesis and in vitro comparison to traditional Kern bone reduction forceps.

OBJECTIVE: To develop and evaluate a novel fracture fragment stabilization system, the Sirius minimally invasive bone reduction handle system (SMH), in an artificial fracture model (FxM) simulating a canine femoral fracture repair with a minimally invasive orthopedic approach. STUDY DESIGN: In vitro experimental study. SAMPLE POPULATION: Synthetic fractured femurs with soft-tissue coverage analog (n = 8). METHODS: The developed SMH consisted of modified Kern forceps connected with existing external skeletal fixation components. Intramedullary Steinman pin placement with the SMH or traditional Kern forceps only (KO) was performed by 16 participants in randomized order. Demographics and surgical experience of participants and outcome variables (fragment movement, early/final gap formation, time of procedure, assessed practicability by visual analog scale) were recorded and statistically evaluated. RESULTS: The SMH was more difficult and took longer to assemble (P = .031 and P = .008); SMH resulted in a smaller final reduction gap (P = .008). More surgical experience resulted in faster surgery times (R2 = 0.766) but was not correlated with final fracture gap formation. CONCLUSION: The SMH was associated with reduced fragment gap formation in this simulated setting. CLINICAL SIGNIFICANCE: The SMH may be helpful for maintaining reduction of femoral fractures in dogs. Additional studies of the SMH should be conducted to fully assess the effectiveness and practicality in clinical cases.

Outcome following surgical stabilization of distal diaphyseal and supracondylar femoral fractures in dogs.

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.

Résultats de stabilisation chirurgicale de fractures fémorales diaphysaires distales et supracondylaires chez le chien. Une étude rétrospective portant sur le signalement, la présentation clinique, les techniques de réduction de fracture, les complications et les résultats de chiens atteints de fractures fémorales supracondyliennes et diaphysaires distales a été réalisée. Quarante-cinq chiens présentant une fracture fémorale unilatérale ont été inclus au total. Les plaques fémorales supracondyliennes représentaient la méthode d'ostéosynthèse la plus courante. Diverses techniques de fixation ont abouti à des résultats favorables dans la majorité des cas, avec 19/45 cas récupérant une fonction complète et 22/45 une fonction considérée acceptable. Le degré de comminution de la fracture n'apparaissait pas comme étant un facteur de risque de complication ou étant associé à des résultats défavorables.(Traduit par Emilie Fauchon et Emilie Hanot).

Use of a cerclage cable-plate system to stabilize a periprosthetic femoral fracture after total hip replacement in a dog.

OBJECTIVE: To report the successful use of cerclage cables around the periprosthetic region of a femoral fracture after total hip replacement (THR) in a dog with bone stock too limited for other methods of fixation. STUDY DESIGN: Case report. ANIMAL: 6-year-old male neutered, golden retriever. METHODS: Locking plate fixation of a type-B1 diaphyseal periprosthetic femoral fracture (PFF) failed 14 days after cementless THR and 6 days after initial femoral fracture repair. Total hip replacement implants seemed unchanged on radiographs, but lateral retraction of the screw-plate construct from the proximal segment was evident. Bone stock was assessed as insufficient for adequate screw purchase, prompting revision of the fixation with cerclage cable fixation of the proximal segment; the cables were anchored to the original locking plate construct with threaded positioning pins that screwed into the locking holes. RESULTS: Acceptable union was documented on radiographs by 3 months after revision. No lameness and good range of motion of the hip were observed on clinical examination 13 months after surgery. Radiographs at 13 months documented static implant positioning and remodeling at the fracture site. CONCLUSION: Use of a cable-plate construct to stabilize a type-B1 PFF led to successful long-term outcome in this dog. CLINICAL SIGNIFICANCE: Use of a cable-plate construct may be considered to treat type-B1 PFF with limited bone stock.

Surgical management of long bone fractures in cats using cortical bone allografts preserved in honey.

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.

Gestion chirurgicale de fractures osseuses longues chez les chats à l'aide d'une allogreffe de la corticale préservée dans du miel. Ce rapport décrit deux fractures comminutives réparées par la stabilisation à l'aide de l'allogreffe de la corticale qui avait été préservée dans du miel. Les deux chats ont manifesté une mise en charge postopératoire appropriée. La préservation de l'os dans du miel est une méthode de remplacement simple et facilement disponible comme ostéothèque. Il s'agit du premier rapport d'un défaut osseux chez des chats qui a été réparé à l'aide d'un os préservé dans du miel.(Traduit par Isabelle Vallières).

Closed reduction and fluoroscopic-assisted percutaneous pinning of 42 physeal fractures in 37 dogs and 4 cats.

OBJECTIVE: To report complications and clinical outcome of dogs and cats that underwent fluoroscopic-assisted percutaneous pinning (FAPP) of physeal fractures. STUDY DESIGN: Retrospective study. ANIMALS: Client-owned dogs (n = 37) and cats (n = 4). MATERIALS AND METHODS: Records (August 2007-August 2014) of physeal fractures treated with FAPP in 3 hospitals were evaluated. Data collected included signalment, fracture characteristics (etiology, location, duration, Salter-Harris classification, preoperative and postoperative displacement), surgical information (implant size, surgical duration), and outcome assessment information (functional outcome, radiographic outcome, and complications). RESULTS: The majority of animals (92%) were classified as full functional outcome. No significant predictors of functional outcome were identified. The overall complication rate was 15% (n = 6). Elective pin removal rate was 41% (n = 17). Goniometry and limb circumference measurements of the affected and contralateral limbs were not significantly different in dogs for which measurements were obtained. Seventeen of 18 animals (16 dogs, 2 cats) measured had bone length changes on follow-up radiographs. CONCLUSION: FAPP is associated with an excellent functional outcome in a narrow selection of fracture configurations, specifically those with minimal displacement and for which anatomical alignment can be achieved with closed reduction.

Physeal Fractures in Foals.

Physeal fractures are common musculoskeletal injuries in foals and should be included as a differential diagnosis for the lame or nonweightbearing foal. Careful evaluation of the patient, including precise radiographic assessment, is paramount in determining the options for treatment. Prognosis mostly depends on the patient's age, weight, and fracture location and configuration.

Diagnosis and Treatment Considerations for Nonphyseal Long Bone Fractures in the Foal.

Many long bone fractures that are not considered repairable in the adult horse are repairable in the foal. This is largely because of reduced patient size and more rapid healing in the foal. When there is no articular communication, the long-term prognosis for athletic function can be very good. Emergency care and transport of the foal with a long bone fracture is different than the adult.