Ankle Joint Pressure in Supination-External Rotation Injuries: A Biomechanical Study in an Unrestrained Cadaver Model.

BACKGROUND: Previous biomechanical studies simulating supination-external rotation (SER) IV injuries revealed different alterations in contact area and peak pressure. We investigated joint reaction forces and radiographic parameters in an unrestrained, more physiological setup. METHODS: Twelve lower leg specimens were destabilized stepwise by osteotomy of the fibula (SER II) and transection of the superficial (SER IVa) and the deep deltoid ligament (SER IVb) according to the Lauge-Hansen classification. Sensors in the ankle joint recorded tibio-talar pressure changes with axial loading at 700 N in neutral position, 10° of dorsiflexion, and 20° of plantarflexion. Radiographs were taken for each step. RESULTS: Three of 12 specimen collapsed during SER IVb. In the neutral position, the peak pressure and contact area changed insignificantly from 2.6 ± 0.5 mPa (baseline) to 3.0 ± 1.4 mPa (SER IVb) (P = .35) and from 810 ± 42 mm2 to 735 ± 27 mm2 (P = .08), respectively. The corresponding medial clear space (MCS) increased significantly from 2.5 ± 0.4 mm (baseline) to 3.9 ± 1.1 mm (SER IVb) (P = .028).The position of the ankle joint had a decisive effect on contact area (P = .00), center of force (P = .00) and MCS (P = .01). CONCLUSION: Simulated SER IVb injuries demonstrated radiological, but no biomechanical changes. This should be considered for surgical decision making based on MCS width on weightbearing radiographs. LEVELS OF EVIDENCE: Not applicable. Biomechanical study.

Biomechanical Analysis of a Novel Syndesmotic Plate Compared With Traditional Screw and Suture Button Fixation.

Many lateral malleolus fractures have been found to have syndesmosis injuries after anatomic reduction. The main methods for the treatment of syndesmosis injuries are screw fixation and suture-button flexible fixations. In pursuit of innovation, we have designed a novel syndesmotic plate (NSP) for simultaneous fixation of lateral malleolus fractures and distal tibiofibular syndesmosis injuries. The purpose of this study is to compare the biomechanical characteristics of the NSP to syndesmotic screw and suture-button fixations. Twelve adult cadaveric specimens were used in this experiment. Axial loading as well as rotation torque were applied in 3 different ankle positions: neutral, dorsiflexion, and plantarflexion. After the initial specimens were tested, they were made into a pronation-abduction III fracture model as described by Lauge-Hansen. Subsequently, the specimens were fixed sequentially using a distal fibular anatomic locking plate (DFALP) combined with syndesmotic screws, DFALP combined with suture button, and NSP. Then the above tests were repeated. The syndesmotic displacement and the strain of the tibia and fibula were recorded during the experiment. In most cases, the displacements and strains of the NSP group and the screw group were smaller than the suture button groups and the native (SBGAN) (p < .05), and the displacements and strains of the NSP group were also slightly smaller than the screw group in most cases, and there was no significant difference between the 2 groups. The NSP we developed has a fixed strength no less than the traditional syndesmotic screw fixation. This provides us a new idea for the treatment of distal tibiofibular syndesmosis injuries.

Diagnostic capability of dynamic ultrasound evaluation of supination-external rotation ankle injuries: a cadaveric study.

BACKGROUND: Ankle syndesmosis injuries are common and range in severity from subclinical to grossly unstable. Definitive diagnosis of these injuries can be made with plain film radiographs, but are often missed when severity or image quality is low. Computed tomography (CT) and magnetic resonance imaging (MRI) can provide definitive diagnosis, but are costly and introduce the patient to radiation when CT is used. Ultrasonography may circumvent many of these disadvantages by being inexpensive, efficient, and able to detect injuries without radiation exposure. The purpose of this study was to evaluate the ability of ultrasonography to detect early stage supination-external rotation (SER) ankle syndesmosis injuries with a dynamic external rotational stress test. METHODS: Nine, all male, fresh frozen specimens were secured to an ankle rig and stress tested to 10 Nm of external rotational torque with ultrasonography at the tibiofibular clear space. The ankles were subjected to syndesmosis ligament sectioning and repeat stress measurements of the tibiofibular clear space at peak torque. Stress tests and measurements were repeated three times and averaged and analyzed using a repeated one-way analysis of variance (ANOVA). There were six ankle injury states examined including: Intact State, 75% of AITFL Cut, 100% of AITFL Cut, Fibula FX - Cut 8 cm proximal, 75% PITFL Cut, and 100% PITFL Cut. RESULTS: Dynamic external rotation stress evaluation using ultrasonography was able to detect a significant difference between the uninjured ankle with a tibiofibular clear space of 4.5 mm and the stage 1 complete injured ankle with a clear space of 6.0 mm (P < .02). Additionally, this method was able to detect significant differences between the uninjured ankle and the stage 2-4 injury states. CONCLUSION: Dynamic external rotational stress evaluation using ultrasonography was able to detect stage 1 Lauge-Hansen SER injuries with statistical significance and corroborates criteria for diagnosing a syndesmosis injury at ≥6.0 mm of tibiofibular clear space widening.

Anatomic Feasibility of Distal Fibula Bicortical Screw Fixation With Lateral Neutralization Plating for Rotational Ankle Fractures.

A common technique for fixation of rotational fibular fractures is to use an interfragmentary compression screw with a laterally positioned neutralization plate. The objective of the present investigation was to examine the anatomic feasibility of distal fibula bicortical fixation within this plating technique. A specific screw insertion technique was performed through a laterally positioned one-third tubular plate on a consecutive series of 81 intact cadaveric ankle mortises. The most distal plate hole was drilled, aimed 10° posterior to the midline of the fibula. The second-most distal plate hole was drilled, aimed 25° superiorly. The specimens were then dissected, and the screw termini were physically examined for whether they had penetrated the articular cartilage of the ankle mortise. The length of the most distal bicortical screw measured a mean ± standard deviation of 20.44 ± 2.49 (range 14 to 26) mm, with an extra-articular terminus in 95.06% of specimens. The length of the second-most distal bicortical screw measured a mean ± standard deviation of 19.68 ± 3.02 (range 12 to 28) mm, with an extra-articular terminus in 100% of the specimens. The results of the present study provide evidence that bicortical distal fibular fixation in accordance with basic fixation principles is anatomically possible and feasible with a one-third tubular plate. This could potentially obviate the need for more expensive fixation options (i.e., locked plates or anatomically contoured plates) and fixation options that are biomechanically stable but potentially anatomically impeding (i.e., posterior antiglide plating).

A cadaver study revisiting the original methodology of Lauge-Hansen and a commentary on modern usage.

BACKGROUND: The study by Lauge-Hansen published in the Archives of Surgery in 1950 still stands as the seminal work for our understanding of the pathomechanics of ankle fractures. The purpose of the present study was to recreate Lauge-Hansen's experiments for the supination-external rotation (SER) fracture mechanism and to determine whether the predicted sequence of osseous and soft-tissue injury is reproducible on the basis of his originally described methodology. METHODS: Ten fresh-frozen cadaver specimens amputated above the knee were utilized. The foot was axially loaded in a position of neutral dorsiflexion and supination. External rotation was applied manually in accordance with Lauge-Hansen's description until osseous and/or soft-tissue injury occurred. Fluoroscopic images were made and anatomic dissection was performed. RESULTS: Although several specimens exhibited findings consistent with certain stages of the SER injury pattern, no specimen demonstrated the complete sequence of predicted osseous and soft-tissue injury. CONCLUSIONS: Loading cadaver specimens with an SER mechanism utilizing a methodology similar to that in the original experiments by Lauge-Hansen does not reliably produce the sequence of osseous and soft-tissue injury predicted by Lauge-Hansen.

Comparison of radiographic stress tests for syndesmotic instability of supination-external rotation ankle fractures: a cadaveric study.

OBJECTIVE: According to the classification of Lauge-Hansen, supination-external rotation IV (OTA 44-B) injuries should not have syndesmotic instability; yet, several studies have suggested disruption is present in up to 40% of these injuries based on stress tests. In this study, we examine various stress radiographic parameters in a cadaver model of supination-external rotation IV equivalent injury. We hypothesize that external rotation stress testing and widening of the medial clear space do not always represent syndesmotic instability. Rather, the better predictor of syndesmotic instability will be an increased tibia-fibula clear space with the lateral stress test. METHODS: Eleven fresh frozen human lower limbs were each secured into a custom frame. External rotation stress test was performed by applying an external moment of 7.5 Nm, and lateral stress test was performed by applying 100 N lateral pull at the distal fibula. True mortise radiographs were taken of intact ankles and while performing external rotation and lateral stress tests at each stage of sequentially sectioning the ankle ligaments. The deltoid ligament was sectioned first, then anterior-inferior tibiofibular ligament, posterior-inferior tibiofibular ligament, and interosseous membrane. Tibiofibular clear space and medial clear space were measured on each radiograph. RESULTS: External rotation stress test produced significant medial clear space widening when the deltoid ligaments were sectioned (P < 0.05). Lateral stress test produced no significant widening of the tibiofibular clear space until interosseous membranes were sectioned (P < 0.05). CONCLUSIONS: Lateral stress test with widening of the tibiofibular clear space is the preferred indicator of syndesmotic instability. The external rotation stress is a poor indicator of syndesmotic injury in the setting of deltoid ligament injury.

Cadaveric limb analysis of tendon length discrepancy of posterior tibial tendon transfer through the interosseous membrane.

The posterior tibial tendon transfer through the interosseous membrane, as popularized by Watkins in 1954, is a procedure for treating reducible eversion and dorsiflexory paresis used by lower extremity foot and ankle surgeons. The posterior tibial tendon has been transferred to various locations on the midfoot for equinus and equinovarus deformities. Dorsiflexory paresis is a common symptom in equinovarus deformity, clubfoot deformity, Charcot-Marie-Tooth disease, leprosy, mononeuropathy, trauma to the common peroneal nerve, cerebrovascular accident, and Duchenne's muscular dystrophy. The main difficulty with this procedure, often discussed by surgeons, is inadequate tendon length, making anchoring to the cuneiforms or cuboid difficult. The goal of our cadaveric study was threefold. First, we sought to determine whether the tendon length is sufficient when transferring the posterior tibial tendon to the dorsum of the foot through the interosseous membrane for a dynamic or a static transfer. Second, we wished to describe the surgical technique designed to obtain the maximal length. Finally, we sought to discuss the strategies used when the tendon length for transfer is insufficient.

A contoured locking plate for distal fibular fractures in osteoporotic bone: a biomechanical cadaver study.

OBJECTIVE: Fixation of ankle fractures in elderly patients is associated with reduced stability conditioned by osteoporotic bone. Therefore, fixation with implants providing improved biomechanical features could allow a more functional treatment, diminish implant failure and avoid consequences of immobilisation. MATERIALS AND METHODS: In the actual study, we evaluated a lateral conventional contoured plate with a locking contoured plate stabilising experimentally induced distal fibular fractures in human cadavers from elderly. Ankle fractures were induced by the supination-external rotation mechanism according to Lauge-Hansen. Stage II fractures (AO 44-B1) were fixed with the 2 contoured plates and a torque to failure test was performed. Bone mineral density (BMD) was measured by quantitative computed tomography to correlate the parameters of the biomechanical experiments with bone quality. RESULTS: The locking plate showed a higher torque to failure, angle at failure, and maximal torque compared to the conventional plate. In contrast to the nonlocking system, fixation with the locking plate was independent of BMD. CONCLUSION: Fixation of distal fibular fractures in osteoporotic bone with the contoured locking plate may be advantageous as compared to the nonlocking contoured plate. The locking plate with improved biomechanical attributes may allow a more functional treatment, reduce complications and consequences of immobilisation.

Minimally invasive video-assisted cervical ventral slot in dogs. A cadaveric study and report of 10 clinical cases.

OBJECTIVES: To investigate the feasibility of a minimally invasive video-assisted (MIVA) cervical ventral slot (VS) in dogs without the use of fluoroscopy, and to report our initial clinical experiences in dogs. METHODS: Two surgical approaches to an intervertebral disk space (IVDS) were performed in eight intact canine cadavers to determine the feasibility of MIVA-VS using the Destandau Endospine™ Devicea (DED) without fluoroscopic guidance. In a subsequent clinical study, 10 client-owned dogs admitted for a Hansen type 1 disk extrusion underwent a MIVA-VS. Recorded data in both studies included: incision lengths, correct targeting of the IVDS, technical problems encountered during the procedure, and potential damage to major anatomical structures. In the 10 clinical cases, duration of the procedure and clinical outcome at five and 12 days, and after a minimum of three months were also recorded. RESULTS: Correct exposure of the targeted IVDS was achieved in all cases. There was no major iatrogenic damage. Mean skin incision length was 39 mm and mean surgery time was 52 minutes. The technique provided increased illumination and magnification of the surgical field. Recovery was uneventful in all cases. CLINICAL RELEVANCE: The present study provided evidence that MIVA-VS using the DED was feasible and a relatively fast and safe procedure for the treatment of cervical disk herniation. Advantages of the technique seemed to include shorter incisions, less dissection and improved visibility.

Avaliação anatômica do túnel do tarso – estudo das estruturas nervosas e suas correlações em dissecção de cadáveres / Anatomical assessment of the tarsal tunnel - study of the nervous structures and their correlation in dissecting corpses

Apresenta-se estudo anatômico do túnel do tarso em 38 pés de cadáveres com avaliação do retináculo dos flexores, das estruturas do túnel do tarso e das relações entre suas estruturas e o nervo tibial. Estabeleceu-se a linha “AB”, definida do centro do maléolo medial a um ponto localizado a 1cm distalmente à tuberosidade póstero-superior do calcâneo, utilizada como ponto de referência para mensurações do nervo tibial e seus ramos. Encontrou-se o retináculo com aspecto delga-do em 73,68% e adiposo em 26,31%. A divisão do nervo tibial em nervo plantar medial e lateral ocorreu em 31,57% dos pés proximalmente ao túnel do tarso, em 2,63% à entrada desse e 65,78% no interior do túnel. O nervo calcâneo medial apresentou origem em 50% dos pés proximalmente à linha “AB”, em 36,84% distalmente a ela e, em 13,15%, tanto proximal como distalmente.

Detection of Mycobacterium leprae DNA from archaeological skeletal remains in Japan using whole genome amplification and polymerase chain reaction.

BACKGROUND: Identification of pathogen DNA from archaeological human remains is a powerful tool in demonstrating that the infectious disease existed in the past. However, it is very difficult to detect trace amounts of DNA remnants attached to the human skeleton, especially from those buried in a humid atmosphere with a relatively high environmental temperature such as in Asia. METHODOLOGY/PRINCIPAL FINDINGS: Here we demonstrate Mycobacterium leprae DNA from archaeological skeletal remains in Japan by polymerase chain reaction, DNA sequencing and single nucleotide polymorphism (SNP) analysis. In addition, we have established a highly sensitive method of detecting DNA using a combination of whole genome amplification and polymerase chain reaction, or WGA-PCR, which provides superior sensitivity and specificity in detecting DNA from trace amounts of skeletal materials. CONCLUSION/SIGNIFICANCE: We have detected M. leprae DNA in archaeological skeletal remains for the first time in the Far East. Its SNP genotype corresponded to type 1; the first detected case worldwide of ancient M. leprae DNA. We also developed a highly sensitive method to detect ancient DNA by utilizing whole genome amplification.

An lise da reprodutibilidade das classificações de Lauge-Hansen e Danis-Weber para fraturas de tornozelo / Analysis of Lauge-Hansen and Danis-Weber ankle fracture classification reproducibility

Foi estudada a reprodutibilidade das classificações das fraturas do tornozelo propostas por Lauge-Hansen e por Danis-Weber, atraves da an lise da concordancia entre duas leituras realizadas por oito observadores em diferentes est gios de formação. Avaliou-se a concordancia entre duas leituras de um mesmo observador (variação intra-observador) e entre as leituras de todos os observadores entre si (variação interobservador). A an lise das variaçäes foi realizada pelo método estatistico de Kappa. A classificaçäo de Danis-Weber mostrou maior concordância nas an lises intra e interobservador, não sofrendo influencia do estagio de formação do observador. Conclui-se, portanto, que a classificação de Danis-Weber pode ser considerada mais reprodutivel e mais indicada para uso em serviços de treinamento e nas salas de emergencia

Ankle fractures. The Lauge-Hansen classification revisited.

Rational treatment of ankle fractures requires knowledge of the extent of bone and soft tissue injury. Although the Lauge-Hansen classification attempts to do this by relating specific fracture patterns to injury mechanism, the experimental underpinning for this classification has not been reexamined rigorously using modern experimental methods. This study examines the hypothesis that the clinically occurring supination and external rotation injury pattern does not result from the mechanism described by Lauge-Hansen. Thirty-two anatomic specimen ankles were mounted on an MTS machine for combined axial loading with external rotation to failure testing. A foot plate supinated the foot 25 degrees. Testing was performed with the ankle at neutral, 25 degrees plantar flexed, 10 degrees to 15 degrees dorsiflexed, and in 6 degrees to 8 degrees leg valgus. Pure supination and external rotation with the ankle in neutral did not result in the Lauge-Hansen supination and external rotation type fractures. This outcome was not altered if the ankle specimens initially were placed in plantar flexion or dorsiflexion. The addition of a valgus load, which pushes the talus laterally against the fibula, resulted in the classic Lauge-Hansen supination and external rotation type fracture. All specimens had an isolated lateral injury or a lateral injury that preceded medial injury.

Motion of the ankle in a simulated supination-external rotation fracture model.

UNLABELLED: An experimental study was undertaken with use of axially loaded, unconstrained cadaver ankles to determine the motion patterns seen with progressive stages of the supination-external rotation type of fracture. As described by Lauge-Hansen, these fractures were modeled by transection of the anterior aspect of the capsule and the anterior tibiofibular ligament (stage I), followed by oblique fibular osteotomy ending at the level of the ankle joint (stage II), transection of the posterior aspect of the capsule (stage III), and sequential sectioning of the superficial and deep fibers of the deltoid ligament (stage IV). Thirteen specimens were tested on an apparatus that allowed for controlled loading while the ankle was passed through a physiological range of dorsiflexion and plantar flexion. The ankles were unconstrained about the axial (internal and external rotation) and coronal (varus and valgus angulation) axes. Measurements were made throughout the range of motion in these axes in order to define the kinematic behavior. In the intact specimens, maximum plantar flexion was associated with a mean (and standard deviation) of 1.9 +/- 4.12 degrees of internal rotation of the talus and maximum dorsiflexion, with a mean of 7.2 +/- 3.88 degrees of external rotation. Varus angulation increased slightly with plantar flexion compared with the value in dorsiflexion (2.4 +/- 2.40 compared with 0.3 +/- 1.96 degrees). Internal and external rotation was not affected by fibular osteotomy or by transection of the superficial fibers of the deltoid ligament. Transection of the deep fibers of the deltoid ligament caused a significant (p < 0.02) increase in external rotation of the talus at maximum plantar flexion; this was corrected incompletely by insertion of an anatomical fibular plate. With the numbers available for study, we could not show that varus or valgus angulation was significantly affected by any combination of sectioning of the deltoid ligament and fibular osteotomy. These experiments were repeated with the addition of fixation of the subtalar joint with a talocalcaneal screw. With the number of specimens available, we could detect no significant difference, with respect to axial rotation, due to fixation of the subtalar joint. However, along the coronal axis, increased valgus angulation (p < 0.02) was seen during plantar flexion when either the deep or the superficial fibers of the deltoid ligament had been cut. CLINICAL SIGNIFICANCE: These results indicate that stability of the loaded ankle is primarily due to the deltoid ligament, which exerts a restraining influence on external rotation of the talus. Complete fibular osteotomy did not cause abnormal motion of the ankle in the absence of a medial injury. In the presence of a complete injury, lateral reconstruction only partially restored the mechanical integrity of the ankle. The results provide justification for the non-operative treatment of isolated fractures of the lateral malleolus. The data also suggest that a lateral fracture associated with a major injury of the deltoid ligament should be treated with anatomical lateral fixation followed by immobilization without early motion, to allow adequate healing of the deltoid ligament at its resting length.

An axially loaded model of the ankle after pronation external rotation injury.

Using a testing apparatus that allows axial loading and displacement in the sagittal, axial, and coronal planes, 6 ankles were tested under experimental conditions intended to model the Lauge-Hansen pronation external rotation injury. All specimens were rotated through a continuous range of sagittal motion with the ankle under 300 N of axial load as the coupled motion of the ankle in the coronal and axial axes was recorded. Combinations of fibular osteotomy, disruption of the syndesmosis up to 6 cm above the plafond, and deltoid transection were tested to mimic Stages I to III of the pronation external rotation ankle fracture. The effects of stabilization of the fibula and syndesmosis also were examined. Neither fracture of the fibula 4 cm above the plafond nor disruption of the syndesmosis to 6.0 cm resulted in a significant change in coupled motion of the talus. When the superficial deltoid was sectioned, the ankle had increased external rotation in plantar flexion. When the deep deltoid was sectioned, the ankle dislocated in plantar flexion unless the fibula was stabilized. This prevented dislocation but failed to restore normal talar kinematics. This study found no biomechanical support for placement of a syndesmotic screw unless the medial side cannot be stabilized anatomically.

Norwegian scabies: occurrence in a patient undergoing immunosuppression.

Norwegian scabies is rare yet distinctive. The majority of reported cases have been in patients with relatively small group of diseases, including Down syndrome and lepromatous leprosy. A case occurred in a patient on long-term immunosuppressive therapy following a kidney transplant. Altered host factors appear to be the prime determinants in the pathogenesis of the disease.