Medial arch instability/internal foot overload association with non-insertional Achilles tendinopathy and the 'Zone of Conflict Theory'.

BACKGROUND: Non insertional Achilles tendinopathy [AT] is a degenerative condition that is prevalent in runners. 30% have no preceding history and many runners do not develop AT. Overuse, pronation, and compromised blood supply are hypothesised as causal. The exact precipitant is still unknown. The link between medial arch instability and AT has not been made. The purpose of this study was to investigate the association between spring ligament (SL) laxity and first ray (FRI) instability, and the presence of (AT). METHODS: Ethical approval was obtained. Patients were identified from hospital databases for unilateral AT, allowing the opposite unaffected foot to be used as an internal control. SL laxity was measured using the lateral translation score and FRI was measured using a modified digital Klauemeter. Ultrasound was used to assess the tendoachilles [TA] in affected vs unaffected legs. RESULTS: 17 patients were recruited with a mean age of 55.6 and mean body mass index (BMI) of 33.3. The average symptom duration was 3.62 years. There were 12 left feet and 5 right feet. There was no statistical difference in dorsiflexion angles for the TA or the gastrocnemius. All Beighton scores < 5. Lateral translation scores, FRI scores and TA thickness was significantly greater in AT feet [p < 0.05]. More affected feet had Tibialis posterior tendon pain (TP) [p < 0.05]. CONCLUSIONS: Feet with AT exhibit higher lateral translation scores and greater FRI compared to healthy feet, and combined with previous literature evidence, suggests alteration of the subtalar axis alters force moments that may lead to an intrinsic overload of the TA, when the foot enters a "zone of conflict". Medial arch instability, in particular SL laxity and FRI, may contribute to the development of non-insertional AT and treatment of this with early arch support may prevent progressive degeneration.

Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study / Configuración y localización óptima de los tornillos posteriores en las fracturas de calcáneo Sanders 2B: estudio biomecánico

Background: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. Methods: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). Results: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations...(AU)

Introducción: Las fracturas de calcáneo suelen ser lesiones intraarticulares de alta energía asociadas con hundimiento articular. Además, se añade con frecuencia el estallido de la pared lateral, la superposición de la pared medial, la conminución y la pérdida de hueso bajo la carilla articular. La deformidad secundaria, como el varo del retropié, altera la biomecánica del pie. Nuestra comunidad utiliza cada vez más abordajes mínimamente invasivos con reducción indirecta de la tuberosidad del calcáneo para mantener la reducción mediante tornillos posteriores. Hay estudios que proponen diferentes configuraciones de tornillos, tras experimentación biomecánica, pero aún no es bien conocido qué configuración controla mejor la deformidad en varo. Este estudio tiene como objetivo determinar la configuración óptima del tornillo para controlar la deformidad en varo en las fracturas de calcáneo Sanders 2B. Método: Se prepararon modelos en Sawbone para replicar la fractura de Sanders tipo 2B, con pérdida de hueso central y con conminución. Se eliminó una cuña medial de 0,5cm de la tuberosidad calcánea para crear inestabilidad en varo. Tras estabilizar el ángulo de Gissane con un tornillo aislado parcialmente roscado de 4mm y una placa moldeada, se utilizaron tornillos de compresión multiuso Charlotte (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) sin cabeza, canulados y parcialmente roscados de 7mm insertados sobre una AK bajo escopia. El desplazamiento del plano sagital del fragmento de tuberosidad fracturado en comparación con el cuerpo al aplicar una fuerza de 5N, 10N y 20N se midió en milímetros (mm). Resultados: Dos tornillos insertados (un tornillo medial en el sustenaculum tali de inferior a superior y un tornillo lateral en el eje largo del astrágalo) proporciona el menor desplazamiento (0,88±0,390 a 5N y 1,7±1,251 a 20N) y resulta la construcción más estable (p<0,05) en comparación con otras configuraciones...(AU)

[Artículo traducido] Configuración y localización óptima de los tornillos posteriores en las fracturas de calcáneo Sanders 2B: estudio biomecánico / Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study

Background: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. Methods: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). Results: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations...(AU)

Introducción: Las fracturas de calcáneo suelen ser lesiones intraarticulares de alta energía asociadas con hundimiento articular. Además, se añade con frecuencia el estallido de la pared lateral, la superposición de la pared medial, la conminución y la pérdida de hueso bajo la carilla articular. La deformidad secundaria, como el varo del retropié, altera la biomecánica del pie. Nuestra comunidad utiliza cada vez más abordajes mínimamente invasivos con reducción indirecta de la tuberosidad del calcáneo para mantener la reducción mediante tornillos posteriores. Hay estudios que proponen diferentes configuraciones de tornillos, tras experimentación biomecánica, pero aún no es bien conocido qué configuración controla mejor la deformidad en varo. Este estudio tiene como objetivo determinar la configuración óptima del tornillo para controlar la deformidad en varo en las fracturas de calcáneo Sanders 2B. Método: Se prepararon modelos en Sawbone para replicar la fractura de Sanders tipo 2B, con pérdida de hueso central y con conminución. Se eliminó una cuña medial de 0,5cm de la tuberosidad calcánea para crear inestabilidad en varo. Tras estabilizar el ángulo de Gissane con un tornillo aislado parcialmente roscado de 4mm y una placa moldeada, se utilizaron tornillos de compresión multiuso Charlotte (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) sin cabeza, canulados y parcialmente roscados de 7mm insertados sobre una AK bajo escopia. El desplazamiento del plano sagital del fragmento de tuberosidad fracturado en comparación con el cuerpo al aplicar una fuerza de 5N, 10N y 20N se midió en milímetros (mm). Resultados: Dos tornillos insertados (un tornillo medial en el sustenaculum tali de inferior a superior y un tornillo lateral en el eje largo del astrágalo) proporciona el menor desplazamiento (0,88±0,390 a 5N y 1,7±1,251 a 20N) y resulta la construcción más estable (p<0,05) en comparación con otras configuraciones...(AU)

Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study.

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04±0.971 at 5N and 11.24±7.590 at 20N) (p<0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.

Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study. / [Artículo traducido] Configuración y localización óptima de los tornillos posteriores en las fracturas de calcáneo Sanders 2B: estudio biomecánico.

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5 cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4 mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7 mm cannulated partially threaded CharlotteTM (Wright Medical Technology, Memphis, USA) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5 N, 10 N and 20 N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88 ± 0.390 at 5 N and 1.7 ± 1.251 at 20 N) and the most stable construct (p < 0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04 ± 0.971 at 5 N and 11.24 ± 7.590 at 20 N) (p < 0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.

Identification of a new all-trans-retinol metabolite produced through a new retinol metabolic pathway.

In vitro incubation of all-trans-retinol (atROL) with kidney homogenate from vitamin A-deficient and retinoic acid-supplemented (VAD-RAS) female rats produces a new retinol metabolite. Reverse-phase (RP) and normal-phase (NP) high-performance liquid chromatography (HPLC) analysis showed that this metabolite coelutes with the unknown all-trans-retinol (atROL) metabolite previously found in the day 10 conceptus and kidneys of vitamin A-deficient rats maintained on all-trans-retinoic acid (VAD-RA) and given 2 microg of [3H]atROL. Normal-phase (NP) HPLC purification of the metabolite collected from a RP HPLC column further separated the radiolabeled material into two components. The two isolated compounds have identical or very similar spectroscopic properties. Their nuclear magnetic resonance (1H NMR) and mass spectra (MS) indicated that they are isomers. Spectroscopic studies of the metabolites and their derivatives showed that they are nine-carbon fragments resulting from an oxidative cleavage of the side chain of atROL. The cleavage occurs at C-9, and the product is then oxidized to a keto group. The primary hydroxy group from atROL is preserved in the metabolite. A sulfide bridge is formed between C-11 and C-14, which interrupts the conjugation. The formation of the new metabolites, possessing a 2,5-dihydrothiophene ring, is catalyzed by an enzyme(s) located in the cytosolic fraction of kidneys. The process represents a new retinol metabolic pathway; however, its biological significance is unknown.

All-trans 3,4-didehydroretinoic acid equals all-trans retinoic acid in support of chick neuronal development.

All-trans 3,4-didehydroretinoic acid (at-ddRA) has been identified as a biologically important retinoid in avian, but not mammalian, embryonic development. In this report, we show that at-ddRA, like all-trans retinoic acid (atRA), supports the survival and differentiation of sympathetic neurons of the embryonic chick. Furthermore, the expression of the retinoid-responsive gene RARbeta2 is increased in neurons exposed to either at-ddRA or atRA. The mechanism whereby at-ddRA exerts its effects in chick neurons may involve binding to and activation of nuclear retinoid receptors. For this reason, the binding of recombinant chick RARbeta2 to at-ddRA and to receptor-specific DNA response elements was examined and compared with the binding characteristics of recombinant murine RARbeta2. The chick RARbeta2, like the mammalian RAR, binds to [3H]atRA with high affinity (Kd=0.7-2 nM). Furthermore, both chick and murine RARbeta2 bind equally well to at-ddRA, atRA, and 9-cis RA, but neither receptor shows appreciable binding to 13-cis RA. The chick RARbeta2 recognizes previously described retinoic acid response elements of mammalian gene promoters and, like mammalian RARbeta2, shows enhanced binding in the presence of RXR. This study provides evidence that at-ddRA, like atRA, supports neuronal development in the chick by its interaction with nuclear retinoid receptors.

Human 25-hydroxyvitamin D3-24-hydroxylase, a multicatalytic enzyme.

Human 25-hydroxyvitamin D-24-hydroxylase has been expressed in Spodoptera frugiperda (Sf21) insect cells using the previously cloned cDNA in baculovirus (AcNPV-P450cc24). The activity of recombinant h-P450cc24 required adrenodoxin, adrenodoxin reductase, and NADPH. Incubation of this reconstituted system with 25-OH-[26,27-(3)H]D3 substrate produced several metabolites that were resolved on a normal-phase cyano HPLC system. These products exactly comigrated with authentic standards for 24-oxo-25-OH-D3, 23(S),25-(OH)2D3, 24(R),25-(OH)2D3, and 24-oxo-23(S),25-(OH)2D3. The soluble proteins from Sf21 cells infected with wild-type baculovirus produced neither 24,25-(OH)2D3 nor any of the other 25-OH-D3 metabolites. The products were isolated and subjected to a normal-phase amino HPLC for further separation, purification, and characterization. Comigration on two HPLC systems, periodate cleavage reactions, and NaBH4 reduction established clearly the identity of these metabolites. Incubation of recombinant h-P450cc24 with 25-OH-[3 alpha-3H]D3 led to the isolation of an additional product that comigrated with 24,25,26,27-tetranor-23-OH-D3. Treatment of putative 24,25,26,27-tetranor-23-OH-[3 alpha-3H]D3 with acetic anhydride changed its migration on amino HPLC to a less polar position, indicating acetylation of a hydroxyl group(s). These data demonstrate conclusively that h-P450cc24 is a multicatalytic enzyme catalyzing most, if not all, of the reactions in the C-24/C-23 pathway of 25-OH-D3 metabolism. It is likely that this enzyme by itself converts 25-OH-D3 and 1,25-(OH)2D3 to one of its final excretion products.