Bilateral dorsal rotation of the talus with tibiotarsal, talocalcaneal, and proximal intertarsal joint subluxation in an alpaca

CASE DESCRIPTION A 14-month-old female alpaca presented with a 3-week history of acute left hind limb lameness and swelling of the left tarsal region. CLINICAL FINDINGS Radiography revealed intermittent dorsal rotation of the talus with tibiotarsal, talocalcaneal, and proximal intertarsal joint subluxation. TREATMENT AND OUTCOME In an attempt to stabilize the talus, screws were placed in the distomedial aspect of the talus and the plantaromedial aspect of the central tarsal bone, and a stainless-steel wire was placed around the screws in a figure-eight pattern. The screw head of the proximal screw broke within 4 weeks after surgery, but subluxation did not recur, and the lameness resolved. Seven months later, the same condition was diagnosed in the opposite hind limb and was treated similarly. Implants remained intact on this side, but the animal started to show signs of pain and inability to flex the tarsal joint, prompting removal of the distal screw. Subsequently, the animal became sound and produced 2 healthy crias, but was euthanatized 4 years after the second surgery because of coccidiosis. CLINICAL RELEVANCE Dorsal rotation of the talus with tibiotarsal, talocalcaneal, and proximal intertarsal joint subluxation is a sporadic condition in New World camelids. This report provides the first account of successful treatment by surgical stabilization of the medial aspect of the proximal intertarsal joint.

The risk of iatrogenic radial nerve and/or profunda brachii artery injury in anterolateral humeral plating using a 4.5 mm narrow DCP: A cadaveric study

Introduction Fixation of humeral shaft fractures with a plate and screws can endanger the neurovascular structure if proper care is not taken. No studies to our knowledge have studied the risk of iatrogenic radial nerve and/or profunda brachii artery (RNPBA) injury from each screw hole of a 4.5 mm narrow dynamic compression plate (narrow DCP). The purpose of this study is to evaluate the risk of RNPBA injury in anterolateral humeral plating with a 4.5 mm narrow DCP. Material and methods 18 humeri of 9 fresh-frozen cadavers in the supine position were exposed via the anterolateral approach with 45 degrees of arm abduction. A hypothetical fracture line was marked at the midpoint of each humerus. A precontoured ten-hole 4.5mm narrow DCP was applied to the anterolateral surface of the humerus using the fracture line to position the center of the plate. All screw holes were drilled and screws inserted. The cadaver was then turned over to the prone position with 45 degrees of arm abduction, and the RNPBA exposed. The holes through in which 100% of the screw had contact with or penetrated the RNPBA were identified as dangerous screw holes, while lesser percentages of contact were defined as risky. Results The relative distance ratios of the entire humeral length from the lateral epicondyle of the humerus to the 4th, 3rd, 2nd and 1st proximal holes were 0.64, 0.60, 0.56 and 0.52, respectively. The most dangerous screw hole was the 2nd proximal, in which all 18 screws had contacted or penetrated the nerve, followed by the risky 1st (12/18), 3rd (8/18) and 4th (2/18) holes. Conclusion In humeral shaft plating with the 4.5mm narrow DCP using the anterolateral approach, the 2nd proximal screw hole carries the highest risk of iatrogenic radial nerve and/or profunda brachii artery injury.

Triangular Fixation to Prevent Proximal Screw Pullout in Adult Spinal Deformity Surgery: A Technical Note

Background Adult spinal deformity (ASD) is caused by spinal malalignment and results in severe low back pain, neurological dysfunction, and severe deformity. Proximal screw back-out represents a difficult problem in minimally invasive ASD surgery. We describe a novel technique to prevent screw pullout in ASD. Methods A 71-year-old woman was referred to our hospital with severe low back pain and gait difficulty. Her daily life had been affected by severe lower back pain for more than 6 months. Standing radiograms indicated severe kyphoscoliosis. Two-stage minimally invasive corrective T10-to-pelvis fixation was performed. Results The first surgery was an L1–S1 C-arm-free oblique lumbar interbody fusion, with an operation time of 3 h 57 min and an estimated blood loss of 240 mL. After 1 week, the second percutaneous pedicle screw (PPS) fixation was performed and proximal screws were inserted under a transdiscal approach (T11) and with a lower angulation trajectory (T10) to enhance pullout strength. For this second surgery, operation time was 3 h 33 min, and estimated blood loss was 320 mL. No postoperative complications or neurological compromise was reported. In terms of clinical outcomes, Oswestry Disability Index improved from 56–24%, and visual analog scale score for lower back pain improved from 62 mm to 24 mm at the 1-year follow-up. Conclusions Minimally invasive circumferential surgery with triangular fixation is effective for preventing proximal screw back-out and surgical invasiveness. With this new technique, surgeons and operating room staff can avoid the risk of adverse events due to intraoperative radiation exposure.

Bent or broken: analysis of set screw fracture in the TFNa implant

Objectives To evaluate set screw fracture in the Trochanteric Femoral Nail Advanced implant (TFNa, Synthes, West Chester, PA) and to identify additional mechanisms of set screw failure in the TFNa. Materials and methods Patients who had experienced failure after open reduction and internal fixation (ORIF) with the TFNa were identified. TFNa implants were explanted and inspected following revision surgery. Medical device reports (MDRs) and manufacturer’s inspection reports describing similar failures for the TFNa in the United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database were also reviewed. Results Four set screw fractures that occurred at a level II trauma center were observed. Sixty-seven reported failures were identified in the MAUDE database for review. Twenty-eight failed implants were returned to the manufacturer for inspection with a published inspection report available for analysis. Set screw fractures can occur in the TFNa when the set screw is deployed prematurely into the proximal screw aperture prior to blade/screw insertion. The set screw can also bend and deform if it is advanced against a helical blade/lag screw that is not fully seated into position, thereby potentially compromising its function. Conclusion The TFNa set screw allows for potential fracture during implant insertion leading to uncontrolled collapse, early excessive proximal femoral shortening, and rotational instability of the helical blade/lag screw. Similar failures in the TFNa can be prevented by having the surgeon inspect the proximal screw aperture after attachment of the proximal aiming aim to ensure the set screw has not been deployed prematurely. Level of evidence Therapeutic Level III.

Treatment of fractures of the proximal end and humeral shaft by locked intramedullary nailing in adults: Case series and literature review

Introduction: Intramedullary nailing is a good indication for stabilizing displaced fractures of the proximal end and shaft of the humerus in adults. Methods: This was a prospective series of 24 patient, over a period of 9 months. The aim of this study is to report the epidemiological and clinical aspects of patients treated with a locked humeral nail and to show the medium-term interest, of this therapeutic method, thus discussing the complications. Results: All patients had received intramedullary nailing of the humerus. The average age was 77.08 years. The female sex was more represented with 66.66% and the right side was frequently fractured with 83.33%. We distinguished 50% of cases involving the proximal end of the humerus, 45.87% of cases of the humeral shaft and one case of concomitant fracture of the proximal end and that of the humeral shaft. The postoperative infection rate is zero in our series and we reported 1 case of distal locking screw breakage, 1 case of iterative fracture on short Telegraph nail, 1 case of proximal screw retraction on long Telegraph nail and 1 case of perforation of the humeral head with a proximal locking screw. Conclusion: humeral intramedullary nailing is a good alternative in fixing proximal end and humeral shaft fractures without considerable complications or damages for the rotator cuff muscles.

Influence of the proximal screws of buttress plates on the stability of vertical femoral neck fractures: a finite element analysis

Background The treatment of vertical femoral neck fractures (vFNFs) in young patients remains challenging, with a high complication rate by using traditional techniques. The use of cannulated screws (CSs) combined with a buttress plate represents an alternative approach for treating vFNFs. However, the biomechanical influence of the use or non-use of the proximal screws of buttress plates on vFNFs stability remains unclear. This study aims to analyse the biomechanics of buttress plate fixation with or without the use of proximal screws through finite element analysis (FEA) to further understand this approach. Methods We built five vFNFs (Pauwels angle 70°) finite element models treated using three cannulated screws (CS group) or three cannulated screws plus a locking buttress plate (buttress group). In the buttress group, use or non-use of proximal screws was carried out on two types of plates (4-hole & 6-hole). The following seven parameters were analysed to compare biomechanical properties of the five models: the stiffness; the maximal stress of the plate system (plate and screws), CSs and bone (MPS, MCS, MBS); the maximal displacement of internal fixations (plate system & CSs) and bone (MIFD, MBD); and the maximal relative displacement of interfragments (MID). Results Compared with CS model, the buttress models exhibited improved biomechanical properties, with increased stiffness and decreased MCS, MBS, MIFD, MBD and MID. The models fixed using buttress plates combined with a proximal screw showed greater stiffness (+ 3.75% & + 8.31% vs + 0.98% & + 4.57%) and MPS (795.6 & 947.2 MPa vs 294.9 & 556.2 MPa) values, and smaller MCS, MBS, MIFD, MBD and MID (− 3.41% to − 15.35% vs − 0.07% to − 4.32%) values than those using the same length plates without a proximal screw. Conclusions Based on the FEA results, buttress plates can improve construct mechanics, help to resist shear force and prevent varus collapse; under the modelling conditions, the use of a proximal screw on buttress plate may be a key technical feature in improving anti-shearing ability; additionally, this screw may be essential to reduce stress and prevent re-displacement of cannulated screws and fracture fragments.

Errores de osteosíntesis en fracturas laterales de cadera tratadas con placa/tornillo deslizante [Osteosynthesis pitfalls in lateral hip fractures treated with plate / sliding screw system].

Introducción: El uso de los sistemas placa/tornillo deslizante para fracturas intertrocantéricas ha demostrado ser un método de fijación eficaz, pero no está exento de fallas. El propósito de este estudio fue evaluar las causas de falla en los pacientes con fracturas laterales de cadera, tratados con placa/tornillo deslizante, puntualizando los defectos técnicos en la colocación.Materiales y Métodos: En nuestro centro, se trató a 177 pacientes por fractura lateral de cadera, a 151 de ellos se les practicó osteosíntesis con placa/tornillo deslizante. Se analizaron la adecuada reducción posoperatoria, la medición de la distancia punta a vértice, la posición del tornillo cefálico en la cabeza femoral y las posibles complicaciones.Resultados: La serie quedó conformada por 143 pacientes. El seguimiento promedio fue de 18 meses (rango 12-48). La tasa de fallas fue del 8,4% (n = 12): 7 (4,8%) por migración cefálica (cut-out) del tornillo proximal, 2 (1,4%) por migración medial (cut-through), 2 (1,4%) presentaron seudoartrosis y un caso (0,70%) de reducción inadecuada en varo. El porcentaje de una segunda operación fue del 7,7% (n = 11). La peor posición fue la superior/posterior con un 100% de migración (n = 4) (p <0,001, diferencia estadísticamente significativa).Conclusión: El posicionamiento superior/posterior del tornillo cefálico podría incrementar la posibilidad de migración y, en consecuencia, la tasa de falla del sistema. AbstractIntroduction: The use of Dynamic Hip/Sliding Screw (DHS) for intertrochanteric fractures has proven to be an effective fixation method, but it also has its failures.The purpose of this study was to evaluate the reason of failures in patients with lateral hip fractures that were treated with a DHS.Method:177 patients were treated in our center for lateral hip fracture. In 151 of them we used a DHS. The adequate postoperative reduction, the measurement of the tip-to-apex distance, the position of the cephalic screw in the femoral head and the possible complications were analyzed.Results: The series was made up of 143 patients. The average follow-up was 18 months (range 12-48). The failure rate was 8.4% (n = 12): 7 (4.8%) due to cephalic migration (cut-out) of the proximal screw, 2 (1.4%) due to medial migration (cut-through) , 2 (1.4%) presented pseudoarthrosis and one case (0.70%) of inadequate reduction in varus. The percentage of a second operation was 7.7% (n = 11). The worst position was the superior / posterior with 100% migration (n = 4) (p <0.001, statistically significant difference).Conclusion: The superior / posterior positioning of the head screw could increase the possibility of migration and, consequently, the failure rate of the system.

Biomechanical comparison of screw-based zones of a spatial subchondral support plate for proximal humerus fractures

Stabilisation of proximal humerus fractures remains a surgical challenge. Spatial subchondral support (S3) plate promises to overcome common complications associated with conventional proximal humerus plates. This study compared the biomechanical performance of S3 plate with a fixed-angle hybrid blade (Equinoxe Fx) plate and a conventional fixed-angle locking plate (PHILOS). The effects of removal of different S3 plate screws on the humeral stability were also investigated. A total of 20 synthetic left humeri were osteotomised transversely at the surgical neck to simulate a two-part fracture and were each treated with an S3 plate. Head screws were divided into three zones based on their distance from the fracture site. Specimens were divided into four equal groups where one group acted as a control with all screws and three groups had one of the screw zones missing. With humeral head fixed, humeral shaft was first displaced 5 mm in extension, flexion, valgus and varus direction (elastic testing) and then until 30 mm varus displacement (plastic testing). Load–displacement data were recorded to determine construct stiffness in elastic tests and assess specimens’ varus stability under plastic testing. Removal of the screw nearest to the fracture site led to a 20.71% drop in mean elastic varus bending stiffness. Removal of the two inferomedial screw above it resulted in a larger drop. The proximal screw pair had the largest contribution to extension and flexion bending stiffness. Varus stiffness of S3 plate constructs was higher than PHILOS and Fx plate constructs. Stability of humeri treated with S3 plate depends on screws’ number, orientation and location. Varus stiffness of S3 plate construct (10.54 N/mm) was higher than that of PHILOS (6.61 N/mm) and Fx (7.59 N/mm) plate constructs. We attribute this to S3 plates’ thicker cross section, the 135° inclination of its screws with respect to the humeral shaft and the availability of pegs for subchondral support.