Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of 2 different LCP systems.

OBJECTIVE: This study compares the mechanical stability and surgical usability of 2 locking plate systems (Kyon ALPS-20 and Synthes PIP-LCP system) for arthrodesis of the equine proximal interphalangeal joint (PIJ). MATERIAL AND METHODS: The experimental ex vivo study included 6 pairs of cadaver distal limbs (n = 12). All specimens were derived from Warmblood horses of various ages that were euthanized for non-orthopedic reasons. Of the 12 limbs collected, 3 left and 3 right distal limb specimens were randomly assigned to each system for implantation. Two abaxial 4.5-mm cortical screws were inserted transarticularly in all cases. Both systems were implanted according to the manufacturer's instructions with the plates placed centrally between the 2 transarticular screws. The ALPS-20 systems were implanted using Kyon B-6.4-mm monocortical locking screws in all positions. The LCP systems were implanted axially using 2 Synthes 5-mm locking screws in the proximal and distal positions, with a standard 4.5-mm cortical screw inserted in the middle position. All constructs underwent CT-scans after implantation and biomechanical testing to detect implant deformation. Uniaxial mechanical loading was applied via a servo-hydraulic test system at a test speed of 50 mm/s, up to a maximum displacement of 80 mm. The resulting load-displacement curves were used to calculate yield point, stiffness, and maximum force for each construct. The measured values were evaluated for statistical significance (p < 0.05) between the 2 plate systems via one-factor ANOVA (Tukey test). The statistical power was verified for yield force, stiffness, and maximum load. RESULTS: No statistically significant differences between the 2 preparation groups were calculated across all of the measured parameters (p > 0.05). The ALPS system implants showed no signs of deformation, either in the plates or the screws. In contrast, the LCP demonstrated visible deformation, which had already occurred at the time of implantation from the tightening of the middle screw, as well as during the subsequent testing of the implants. After biomechanical testing, deformations ranging between 3.1° and 7.0° were measured in 4 LCPs. A total implant failure was observed for 2 LCPs. CONCLUSION AND CLINICAL RELEVANCE: Both systems demonstrated comparable mechanical properties in the present study's ex vivo test model for equine PIJ arthrodesis. As such, the Kyon ALPS-20 may be a good alternative to the Synthes LCP for equine PIJ arthrodesis.

Long-term outcomes after pantarsal arthrodesis with medial plate fixation without external coaptation in 30 dogs.

OBJECTIVE: To report long-term outcomes of dogs treated with pantarsal arthrodesis (PTA) with medial plate fixation without external coaptation. STUDY DESIGN: Retrospective case series. ANIMALS: Client-owned dogs (n = 30). METHODS: Medical records of dogs that had undergone a PTA with a medially applied plate without adjunctive rigid external coaptation were reviewed. Data collected included signalment, complications, and assessment of function at last physical examination. Follow-up information was obtained by phone conversations with owners. Complications were classified as minor, major II, major I, and catastrophic. RESULTS: Thirty-six PTA were performed in 30 dogs. Recorded complications included eight (22.2%) minor complications, 11 (30.6%) major II complications and 11 (30.6%) major I complications. One (2.8%) dog required amputation because of catastrophic complication. Owners provided follow-up for 26 dogs at a median duration of 1215 days (range, 325-3495) after surgery. The outcome was reported as full function in 12 dogs and acceptable function in 14 dogs, with no owners reporting unacceptable function. The owner of the dog in which amputation was required was not contacted. Incorrect contact details prevented owner follow-up in the other three dogs, but all had acceptable function at last veterinary follow up. CONCLUSION: Dogs treated with PTA by medially applied plate had a high incidence of complications requiring surgical or medical management, although full or acceptable function was achieved in 29 of 30 dogs. CLINICAL SIGNIFICANCE: Pantarsal arthrodesis offers a predictably good medium to long-term outcome in spite of a high risk of complications.

Total ankle arthroplasty versus ankle arthrodesis-a comparison of outcomes over the last decade.

BACKGROUND: The surgical treatment of end-stage tibiotalar arthritis continues to be a controversial topic. Advances in surgical technique and implant design have lead to improved outcomes after both ankle arthrodesis (AA) and total ankle arthroplasty (TAA), yet a clear consensus regarding the most ideal form of treatment is lacking. In this study, the outcomes and complications following AA and TAA are compared in order to improve our understanding and decision-making for care and treatment of symptomatic tibiotalar arthritis. METHODS: Studies reporting on outcomes and complications following TAA or AA were obtained for review from the PubMed database between January 2006 and July 2016. Results from studies reporting on a minimum of 200 total ankle arthroplasties or a minimum of 80 ankle arthrodesis procedures were reviewed and pooled for analysis. All studies directly comparing outcomes and complications between TAA and AA were also included for review. Only studies including modern third-generation TAA implants approved for use in the USA (HINTEGRA, STAR, Salto, INBONE) were included. RESULTS: A total of six studies reporting on outcomes following TAA and five reporting on outcomes following AA met inclusion criteria and were included for pooled data analysis. The adjusted overall complication rate was higher for AA (26.9%) compared to TAA (19.7%), with similar findings in the non-revision reoperation rate (12.9% for AA compared to 9.5% for TAA). The adjusted revision reoperation rate for TAA (7.9%) was higher than AA (5.4%). Analysis of results from ten studies directly comparing TAA to AA suggests a more symmetric gait and less impairment on uneven surfaces after TAA. CONCLUSIONS: Pooled data analysis demonstrated a higher overall complication rate after AA, but a higher reoperation rate for revision after TAA. Based on the existing literature, the decision to proceed with TAA or AA for end-stage ankle arthritis should be made on an individual patient basis.

Atenuación del artefacto metálico post cirugía de columna lumbar mediante protocolo de obtención de imagen en tomografía computarizada multicorte. Estudio de cohortes / Metal artifact reduction in post-operative spinal imaging using image acquisition protocol in multidetector computed tomography scans. Cohort study

Fundamento: Las imágenes obtenidas mediante estudios con TC pueden ser alteradas por la presencia de artefactos metálicos, induciendo en ocasiones a malinterpretación en la correcta ubicación de los tornillos pediculares en columna lumbar. El objetivo de este trabajo es desarrollar un protocolo de atenuación del artefacto metálico con el propósito de reducir el artefacto generado por los tornillos pediculares de titanio en aquellos pacientes a los que se ha requerido instrumentación lumbar, permitiendo a los cirujanos de columna realizar un diagnóstico preciso de la ubicación del tornillo pedicular instrumentado. Material y métodos: En la primera parte del trabajo se realizó un estudio observacional, analítico, longitudinal y retrospectivo en 23 pacientes (103 tornillos pediculares) a los que se requirió artrodesis lumbar por patología degenerativa. En el postoperatorio se les realizó un estudio con TC secuencial evaluando la sobredimensión generada por el artefacto del tornillo, aplicando un protocolo estándar de obtención de imágenes. En la segunda parte del estudio se diseñó un estudio observacional, analítico, longitudinal y prospectivo empleando un equipo de TCMC de 64 coronas aplicando un protocolo específico de adquisición de imagen sobre 18 pacientes (104 tornillos pediculares) intervenidos mediante artrodesis lumbar. Resultados: En la primera parte del estudio el artefacto medio a ambos lados del tornillo que se genera tras el estudio de TC es de 1,045 mm (DE: 0,45). En el grupo en el que se aplica el protocolo de atenuación del artefacto tras la TCMC la sobredimensión fue de 0,005 en la porción proximal del tornillo y de 0,025 en la parte distal del tornillo. Conclusiones: Los resultados obtenidos sugieren que tras la aplicación del protocolo de atenuación del artefacto en equipo de TCMC de 64 coronas el artefacto es reducido a unas dimensiones similares a la dimensión real del tornillo pedicular(AU)

Background: In postoperative patients with metallic implants, CT scans can become less effective due to metal-related artifacts. The purpose of our study was to evaluate the effectiveness of a specific metal artifact reduction image protocol, in order to reduce the metal artifact caused by titanium pedicular screws in patients undergoing lumbar pathology by lumbar fusion. This enables surgeons to make an accurate diagnosis of the exact placement of inserted pedicle screws, making this the preferred image modality for assessing screw position after surgery. Methods: In the first part of the study, CT scans were performed on 23 patients (103 titanium alloy pedicle screws) undergoing a lumbar instrumented fusion for treatment for degenerative disease with a standard image acquisition protocol evaluating the possible overdimension caused by the artifact. In the second part, a prospective study was performed using 64-slice multidetector-row computed tomography (MDCT) on 18 patients (104 titanium alloy pedicle screws) undergoing a lumbar instrumented fusion using a specific image acquisition protocol. Results: Our results show that in the sequential CT scan group, mean overdimension (on each side) due to brightness was 1.045 mm (SD 0.45). In the 64-slice multichannel CT group, mean overdimension (on each side) due to brightness was 0.005 mm at the proximal part of the screw and 0.025 mm at the distal part of the screw. Conclusions: The use of a specific metal artifact reduction image protocol in MDCT produces a minimal artifact following lumbar fusion with pedicle screws (AU)

Prospective comparison of subtalar arthroereisis with lateral column lengthening for painful flatfeet.

We prospectively compared subtalar arthroereisis with lateral column calcaneal lengthening for the treatment of painful flatfeet. Twenty-four feet (mean age of patients 12.8 years) were treated. Kinematic motion analysis, pedobarometry, and radiography were performed, and the Oxford Ankle-Foot Questionnaire for Children was administered for each patient before surgery and at the 1-year follow-up. We found statistically significant improvements in both groups, with no difference in their outcomes. Both groups showed significantly improved hindfoot and midfoot motion and positioning. Hindfoot range of motion was preserved. Radiography and pedobarometry also revealed significant improvements. Subtalar arthroereisis is a valid and potentially less-invasive alternative to lateral column lengthening that merits further investigation.

El raquis no se libró de las leyes del mercado. La artrodesis con autoinjerto sigue siendo el procedimiento tipo / The spinal column is not free of market laws. Arthrodesis with an autogenous graft continues to be the procedure-type

No disponible

Artrodesis lumbar circunferencial: autoinjerto frente a injerto liofilizado / Transforaminal lumbar interbody fusion: autograft vs freeze-dried allograft

Objetivo: Analizar y comparar los resultados radiográficos y clínicos de la fusión lumbar mediante autoinjerto frente a injerto liofilizado. Material y metodología: Se realizó un estudio prospectivo cuasi-experimental, con un seguimiento mínimo de 13 meses. Se incluyeron 72 pacientes, con una edad media de 48 años, siendo el 52,8%mujeres. Todos fueron intervenidos de artrodesis lumbar circunferencial de un nivel, que se dividieron en dos grupos: en uno se utilizó autoinjerto de cresta iliaca (AU) (n=41; 57,7%) y en el otro injerto liofilizado de banco (LI) (n=30; 42,3%). Se evaluaron factores sociodemográficos, la existencia o no de fusión tras la intervención y resultados clínicos mediante la escala EVA, antes y después de la cirugía. Resultados: El dolor lumbar medio fue de 7,5 en autoinjertos y de 8 en injertos liofilizados (p=0,146); tras la intervención el dolor lumbar medio mejoró en 4 puntos o más (AU = 3; LI = 1) (p= 0,196). No encontramos diferencias en los resultados de EVA, al igual que tampoco se encontraron diferencias con respecto a la fusión obtenida en los niveles intervenidos (p= 0,112). Conclusión: El injerto liofilizado, en la artrodesis circunferencial de un nivel, nos proporciona fusiones y resultado funcional similar al autoinjerto (AU)

Objective: The purpose of this study is to analyze and compare the radiographic and clinical results of lumbar fusion using autograft versus lyophilized graft. Methods: This was a prospective study quasi-experimental, with a minimum follow-up of 13 months. It included patients undergoing circumferential lumbar fusion level. We started with a population of 96 patients, of which, we had 8 losses and 16 were excluded, so the sample size was 72 patients, 52.8% of them women, with an average age of 48 years. They were divided into two groups: one that was used in the iliac crest autograft (AU) (n = 41; 57.7%) and other bank lyophilized graft (LI) (n = 30; 42.3%). We evaluated socio-demographic factors, the existence of fusion after surgery and clinical outcomes by VAS before and after surgery. Results: Low back pain in a scale of 1 to 10 was UA: 7.5, LI: 8 (p=0.146). After surgery, back pain improved in 4 points or more, AU: 3, LI: 1, (p=0.196). Then we found no statistically significant differences in the results of the visual analog scale, and we also found no differences with respect to the levels obtained in fusion surgery (p=0.112). Conclusion: The lyophilized graft in the circumferential fusion provides fusion and functional results similar to autograft (AU)

Artrodesis del raquis. Ciencia básica / Spinal arthrodesis. Basic science

Una artrodesis vertebral consiste en la combinación de un sistema de estabilización mecánica de 2 o más segmentos vertebrales con una sustancia biológica que promueva la osteogénesis, con el objetivo de conseguir la fusión permanente entre zonas más o menos extensas de dichos segmentos. En una artrodesis vertebral, el aporte biológico por excelencia es el autoinjerto; sin embargo, su obtención genera una alta incidencia de morbilidad y, en casos de artrodesis de más de un espacio intervertebral, la cantidad disponible suele ser insuficiente. El tiempo de extracción e implantación prolonga la intervención quirúrgica, aumentando la exposición y riesgo a sangrado e infección. Por ello, actualmente hay una búsqueda de sustancias que posean las propiedades del autoinjerto evitando la morbilidad y tiempo de cirugía añadido que genera extraer el autoinjerto. En este trabajo se estudia la interacción biomecánica-biología en la artrodesis vertebral (AU)

Spinal arthrodesis consists of a combination of a system of mechanical stabilisation of one or more vertebral segments with a biological substance that promotes osteoneogenesis, with aim of achieving the permanent fusion between areas more or less the same size of these segments. In spinal arthrodesis, the biological support par excellence is the autograft. However, obtaining this involves a high incidence of morbidity and, in cases of arthrodesis of more than one intervertebral space, the quantity available is usually insufficient. The extraction and implantation time prolongs the surgery, increasing the exposure to and risk of bleeding and infection. For these reasons, there is a search for substances that possess the properties of the autograft, avoiding the morbidity and added surgical time required to extract the autograft. The biomechanical-biological interaction in vertebral arthrodesis has been studied in this article (AU)

"The chisel test"--a useful operative, technique for determining adequate, compression during arthrodesis.

Healing of an arthrodesis occurs optimally when the prepared joint surfaces are held rigidly under compression [1]. We routinely use the "Chisel test" intra-operatively to determine whether we have achieved adequate compression and rigidity after fixation of our foot and ankle fusions. This previously un-reported technique uses tools already on hand when performing an arthrodesis and takes seconds to perform.

Knee arthrodesis with the Ilizarov external fixator as treatment for septic failure of knee arthroplasty.

BACKGROUND: The authors report the results of femoral-tibial fusion with an Ilizarov circular external fixator following septic loosening of knee prosthesis. MATERIALS AND METHODS: The series included 17 patients with a mean age of 62.9 years, treated from 1990 to 2007 with femoral-tibial fusion. The Cierny-Mader classification was used for clinical and anatomopathological evaluation; the Engh classification was used to assess the bone defect. Surgical treatment differed according to these criteria. RESULTS: Healing was achieved in 13 out of 17 patients at the first surgical attempt in a mean time of 9.3 months. Mean follow-up was 30 months. Of the four complications, two patients had an intolerance to the external fixator that led to its early removal, and the other two had a septic intraarticular nonunion. CONCLUSIONS: The Ilizarov circular external fixator is a very reliable fixation system due to its low cost, versatility, stability under load, and low risk of septic dissemination. Nevertheless, an appropriate patient selection and a good surgeon's experience are necessary.

Primary open reduction and fixation compared with delayed corrective arthrodesis in the treatment of tarsometatarsal (Lisfranc) fracture dislocation.

Fracture-dislocations of the tarsometatarsal (Lisfranc) joints are frequently overlooked or misdiagnosed at initial presentation. This is a comparative cohort study over a period of five years comparing primary open reduction and internal fixation in 22 patients (23 feet) with secondary corrective arthrodesis in 22 patients (22 feet) who presented with painful malunion at a mean of 22 months (1.5 to 45) after injury. In the first group primary treatment by open reduction and internal fixation for eight weeks with Kirschner-wires or screws was undertaken, in the second group treatment was by secondary corrective arthrodesis. There was one deep infection in the first group. In the delayed group there was one complete and one partial nonunion. In each group 20 patients were available for follow-up at a mean of 36 months (24 to 89) after operation. The mean American Orthopaedic Foot and Ankle Society midfoot score was 81.4 (62 to 100) after primary treatment and 71.8 (35 to 88) after corrective arthrodesis (t-test; p = 0.031). We conclude that primary treatment by open reduction and internal fixation of tarsometatarsal fracture-dislocations leads to improved functional results, earlier return to work and greater patient satisfaction than secondary corrective arthrodesis, which remains a useful salvage procedure providing significant relief of pain and improvement in function.

An in vitro comparison of a 2.7/3.5 mm hybrid plate alone and combined with crossed K-wires for canine pancarpal arthrodesis.

Several techniques have been described for canine pancarpal arthrodesis (PCA) with dorsal plating becoming the most accepted method for ease of placement despite the proposed biomechanical disadvantages. The aim of this study was to compare the biomechanical effects of the addition of crossed K-wires to a standard 2.7/3.5 mm hybrid PCA plate. A 2.7/3.5 mm hybrid PCA plate, alone and combined with crossed K-wires were tested. Six pairs of cadaver forelimbs were collected from medium-sized dogs with an average weight of 24 kg by elbow disarticulation. The limbs were potted and fixed in an Instron load cell (Instron, High Wycombe, UK) and axially loaded to failure. Load displacement data and mode of failure were recorded and stiffness, yield load and ultimate load at failure were calculated. The yield load (kN) of the plate and K-wire construct (1.278+/-0.11) was significantly higher than for the plate construct alone (1.002+/-0.07) (p=0.00056). However, the differences between the two constructs in stiffness and failure loads were not significant.

Residual motion on flexion-extension radiographs after simulated lumbar arthrodesis in human cadavers.

Flexion-extension radiographs are commonly used to assess lumbar fusion. Recommended criteria for solid fusion have varied from 1 to 5 degrees of angular motion between vertebrae. Notwithstanding this wide variation, the validity of these criteria have never been biomechanically tested. As a preliminary and initial step, it was the authors' purpose to quantify measurable angular motion after simulating solid lumbar fusion in human cadaver spines. Seven cadaveric spines (L1 to L4) were tested in a radiolucent jig fixed to a servohydraulic testing apparatus. Flexion and extension moments of 10 Nm were applied. Fusion was simulated using metallic implants spanning the L2-L3 motion segment. These included transverse process plates, a spinous process plate, pedicle screw construct, or an anterior vertebral body plate to simulate an intertransverse, interspinous process, facet, and interbody fusions, respectively. Angular movements were measured on lateral radiographs and statistically compared using a repeated measures analysis of variance. Simulated intertransverse fusion resulted in 13+/-4 degrees of motion; interspinous fusion, 9+/-4 degrees; posterior facet fusion, 5+/-3 degrees; and interbody fusion with plate, 3+/-2 degrees. Compared with the intact, only posterior facet fusion and interbody fusion with plate had statistically significantly less motion (P=0.006 and 0.0001, respectively). The amount of radiographically detectable flexion-extension motion with simulated fusions varies widely and seems to be influenced by fusion type. This study documents a range of measurable motion on flexion-extension radiographs after several types of simulated lumbar fusion. However, as the degrees of motion seemed to be high, future studies should use a fusion simulation other than metallic implants that more closely resembles bony arthrodesis.

Computer Assisted Surgery (CAS) guided arthrodesis of the foot and ankle: an analysis of accuracy in 100 cases.

BACKGROUND: Computer Assisted Surgery (CAS) has shown the potential to increase the accuracy of surgical procedures in different fields of orthopedic surgery. The clinical experiences of 100 cases with CAS guided arthrodeses were evaluated. MATERIALS AND METHODS: Two navigation systems were used (VectorVision/Navivision, Brainlab). Patients with unilateral foot and/or ankle correction arthrodesis from January 1st, 2005 to March 31st, 2008 were included. The correction was planned on the basis of clinical findings, radiographs and computer tomography. Time spent, accuracy, and problems that occurred with CAS guidance were analyzed. The accuracy was assessed by intraoperative three-dimensional imaging with ISO-C 3D or ARCADIS-3D (Siemens). The deviation from the achieved correction in comparison with the planned correction was analyzed. RESULTS: One hundred patients were included (ankle, n = 19; subtalar, n = 23; ankle and subtalar, n = 12; midfoot/tarsometatarsal (TMT), n = 28, others, n = 18). The average time needed for preparation was 356 seconds (5 minutes, 56 seconds) (range, 4 to 30 minutes), the correction took an average of 28 (range, 12 to 140) seconds. The CAS system encountered malfunctions in 3 procedures (3%). In the remaining cases, all the achieved corrections were within a maximum deviation of 2 degrees/mm when compared to the planned correction (p < 0.05). CONCLUSION: With CAS guidance for the correction of deformities of the foot and ankle, a surgeon can achieve a high degree of accuracy with a rapid correction. The high accuracy may lead to improved clinical outcomes.

Failure mode and bending moment of canine pancarpal arthrodesis constructs stabilized with two different implant systems.

OBJECTIVE: To compare failure mode and bending moment of a canine pancarpal arthrodesis construct using either a 2.7 mm/3.5 mm hybrid dynamic compression plate (HDCP) or a 3.5 mm dynamic compression plate (DCP). STUDY DESIGN: Paired in vitro biomechanical testing of canine pancarpal arthrodesis constructs stabilized with either a 2.7/3.5 HDCP or 3.5 DCP. SAMPLE POPULATION: Paired cadaveric canine antebrachii (n=5). METHODS: Pancarpal arthrodesis constructs were loaded to failure (point of maximum load) in 4-point bending using a materials-testing machine. Using this point of failure, bending moments were calculated from system variables for each construct and the 2 plating systems compared using a paired t-test. To examine the relationship between metacarpal diameter and screw diameter failure loads, linear regression was used and Pearson' correlation coefficient was calculated. Significance was set at P<.05. RESULTS: HDCP failed at higher loads than DCP for 9 of 10 constructs. The absolute difference in failure rates between the 2 plates was 0.552+/-0.182 N m, P=.0144 (95% confidence interval: -0.58 to 1.68). This is an 8.1% mean difference in bending strength. There was a significant linear correlation r=0.74 (P-slope=.014) and 0.8 (P-slope=.006) between metacarpal diameter and failure loads for the HDCP and 3.5 DCP, respectively. CONCLUSION: There was a small but significant difference between bending moment at failure between 2.7/3.5 HDCP and 3.5 DCP constructs; however, the difference may not be clinically evident in all patients. CLINICAL RELEVANCE: The 2.7/3.5 HDCP has physical and mechanical properties making it a more desirable plate for pancarpal arthrodesis.

Arthrodesis after failed total ankle replacement.

We present a series of 16 patients treated between 1993 and 2006 who had a failed total ankle replacement converted to an arthrodesis using bone grafting with internal fixation. We used tricortical autograft from the iliac crest to preserve the height of the ankle, the malleoli and the subtalar joint. A successful arthrodesis was achieved at a mean of three months (1.5 to 4.5) in all patients except one, with rheumatoid arthritis and severe bone loss, who developed a nonunion and required further fixation with an intramedullary nail at one year after surgery, before obtaining satisfactory fusion. The post-operative American Orthopaedic Foot and Ankle Society score improved to a mean of 70 (41 to 87) with good patient satisfaction. From this series and an extensive review of the literature we have found that rates of fusion after failed total ankle replacement in patients with degenerative arthritis are high. We recommend our method of arthrodesis in this group of patients. A higher rate of nonunion is associated with rheumatoid arthritis which should be treated differently.

Biomechanical analysis of posterior fixation techniques in a 360 degrees arthrodesis model.

STUDY DESIGN: A biomechanical study to assess the ability of posterior fixation techniques to stabilize a functional spine unit (FSU) after insertion of an anterior load-sharing device. OBJECTIVE: The objective of this study is to compare various posterior fixation techniques in combination with an anterior load-sharing implant. SUMMARY OF BACKGROUND DATA: Pedicle screws and translaminar facet screws have been shown to improve the stiffness of an FSU in combination with an anterior load-sharing device. No published studies, to our knowledge, have compared translaminar facet screw fixation versus bilateral and unilateral pedicle screw fixation used with an anterior load-sharing device. METHODS: Ten cadaveric FSUs were potted using methylmethacrylate and attached to a spine simulator mounted to an MTS Mini-Bionix testing machine. The simulator was configured to control compressive loading, axial torque, flexion, extension, and lateral bending. Each specimen was tested in the intact state and following the application of each of four stabilization techniques: custom cage alone, cage plus translaminar facet screw fixation, cage plus unilateral pedicle screw and plate fixation, and cage plus bilateral pedicle screw and rod fixation with transverse coupling. Compressive stiffness and total range of motion (ROM) between +/-8 Nm of torque were extracted from the raw data. RESULTS: Each fixation method decreased ROM in torsion, flexion-extension, and lateral bending compared with the intact state. Unilateral pedicle fixation offered less stability than either of the other posterior fixations in all modes of testing except axial loading, where it was equivalent. Translaminar facet screw fixation was equivalent to bilateral pedicle screws in all modes tested. CONCLUSIONS: Using a load-sharing interbody implant, translaminar facet screws are equivalent to bilateral pedicle screws in resisting motion in all three planes. Translaminar facet screws and bilateral pedicle screws offer greater stabilization in all three planes compared with unilateral pedicle screws and a single plate.

First metatarsal-phalangeal joint arthrodesis: a biomechanical assessment of stability.

BACKGROUND: First metatarsal phalangeal joint (MTP) arthrodesis is a commonly performed procedure for the treatment of hallux rigidus, severe and recurrent bunion deformities, rheumatoid arthritis and other less common disorders of the joint. There are different techniques of fixation of the joint to promote arthrodesis including oblique lag screw fixation, lag screw and dorsal plate fixation, crossed Kirschner wires, dorsal plate fixation alone and various types of external fixation. Ideally the fixation method should be reproducible, lead to a high rate of fusion, and have a low incidence of complications. METHODS: In the present study, we compared the strength of fixation of five commonly utilized techniques of first MTP joint arthrodesis. These were: 1. Surface excision with machined conical reaming and fixation with a 3.5 mm cortical interfragmentary lag screw. 2. Surface excision with machined conical reaming and fixation with crossed 0.062 Kirschner wires. 3. Surface excision with machined conical reaming and fixation with a 3.5 mm cortical lag screw and a four hole dorsal miniplate secured with 3.5 mm cortical screws. 4. Surface excision with machined conical reaming and fixation with a four hole dorsal miniplate secured with 3.5 mm cortical screws and no lag screw. 5. Planar surface excision and fixation with a single oblique 3.5 mm interfragmentary cortical lag screw. Testing was done on an Instron materials testing device loading the first MTP joint in dorsiflexion. Liquid metal strain gauges were placed over the joint and micromotion was detected with varying loads and cycles. RESULTS: The most stable technique was the combination of machined conical reaming and an oblique interfragmentary lag screw and dorsal plate. This was greater than two times stronger than an oblique lag screw alone. Dorsal plate alone and Kirschner wire fixation were the weakest techniques. CONCLUSIONS: First MTP fusion is a commonly performed procedure for the treatment of a variety of disorders of the first MTP joint. The most stable technique for obtaining fusion in this study was the combination of an oblique lag screw and a dorsal plate. This should lead to higher rates of arthrodesis.

Intertarsal and tarsometatarsal arthrodesis using 2.0/2.7-mm or 2.7/3.5-mm hybrid dynamic compression plates.

Proximal intertarsal or tarsometatarsal arthrodesis was performed in four dogs using either 2.0/2.7-mm or 2.7/3.5-mm hybrid dynamic compression plates. Mean radiographic follow-up time was 30.5 weeks (range, 15 to 60 weeks). Mean owner follow-up time was 40.5 weeks (range, 27 to 60 weeks). All cases went on to form stable, healed arthrodeses. Owners reported no noticeable lameness problems long term. Complications occurred in one case and included pressure sores and fracture of the calcaneus. Implant failure did not occur in any case.