Accessory Facet Research Articles

Non-osseous coalition of accessory anterolateral talar facet-A case series.

The accessory anterolateral talar facet (AALTF) is an anatomical variation that broadens the apex of the lateral talar process. Studies have associated it with other tarsal coalitions as a cause of rigid painful flatfoot. However, a coalition of an AALTF has never been described before. With the advent of MRI, there has been an increase in the detection of these accessory facets. Nevertheless, owing to its small size and unfamiliarity, it is not easily identified. Proper assessment of imaging findings and associated conditions is needed to confirm the diagnosis. Imaging findings in a series of four patients with painful rigid flatfoot revealed the presence of an AALTF with adjacent marrow edema and reduced joint space. This was associated with hindfoot valgus and subfibular impingement. Radiographic suspicion of a non-osseous coalition of AALTF was raised, which was confirmed intraoperatively in one of the patients and demonstrated on CT and MR images in the other patients. This case series presents rare cases of non-osseous coalition of AALTF with a new radiographic sign, the 'reverse tip of the iceberg sign'.

A new elasmosaurid (Sauropterygia, Plesiosauria) from the upper levels of the La Colonia Formation (upper Maastrichtian), Chubut Province, Argentina

A new elasmosaurid, Chubutinectes carmeloi gen. et sp. nov., from the Chubut Province, Argentina, is described. The holotype and only specimen of this species (MPEF-PV 5232) was collected from the La Colonia Formation. Chubutinectes carmeloi gen. et sp. nov. is among the few upper Maastrichtian elasmosaurids from the Southern Hemisphere whose postcranial anatomy is well known. It can be distinguished from other elasmosaurids by the following combination of characters: middle cervical centra longer than high with lateral keel and bilobate articular faces; pectoral and anterior dorsal centra with bilobate articular faces; coracoids with closed cordiform fenestra and long anterior coracoids process; high ratio coracoids/scapular length; ilium with angled shaft; pubis with small lateral cornua; humerus with posterior expansion ending in accessory facet and epipodial facets of humerus almost aligned; accessory ossification between tibia and tibial, and radius and radial. Preliminary phylogenetic analysis recovered Chubutinectes carmeloi gen. et sp. nov. within the Weddellonectia clade, including the Late Cretaceous Wedellian aristonectine elasmosaurids. The study of the associated microfossiliferous assemblages (micro- and nanofossils) suggests a marine inner neritic paleoenvironment, with restricted circulation and warm waters. The presence of Micula prinsii and Micula murus at this latitude indicates a latest Maastrichtian age, upper part of the UC20d sub-biozone and younger than ∼67,3 Ma.

Anatomical variation of the sacroiliac joints: an MRI study with synthetic CT images

BackgroundSynthetic computed tomography (sCT) images are magnetic resonance imaging (MRI)-based images, generated using artificial intelligence. This study aimed to determine the prevalence of anatomical variants of sacroiliac joints (SIJ) on sCT images and the correlation with age, sex and body weight.MethodsMRI of the SIJ including sCT images of 215 patients clinically suspected for sacroiliitis were retrospectively analyzed. The presence of anatomical variants of the SIJ was assessed. Age, sex and body mass index at the time of the MRI were recorded.ResultsSIJ variants were found in 82.8% (356/430) of the evaluated joints. The most frequent variants were iliosacral complex (27.7%), bipartite iliac bony plate (27.2%) and crescent iliac bony plate (27%). One new variant was identified, consisting of an accessory facet of the SIJ on the superior side. Overall, SIJ variants were slightly more frequent in women (85.8% vs. 77.8%), but iliosacral complex was significantly more frequent in men. Isolated synostosis was more prevalent with advancing age, in contrast to semicircular defect and unfused ossification center. The occurrence of iliosacral complex was associated with higher BMI, while crescent iliac bony plate occurred more in patients with lower BMI.ConclusionOver 80% of patients in this study, who were all suspected of sacroiliitis, had at least one SIJ variant. These variants may actually represent subtypes of the normal SIJ. sCT enables detection of very small or subtle findings including SIJ variants.

Accessory Cuboid Facet Associated with Calcaneonavicular Coalitions

Category:Hindfoot; OtherIntroduction/Purpose:Though resection and soft tissue interposition is the mainstay of surgical treatment for symptomatic calcaneonavicular coalitions (CNCs) that fail conservative treatment, some consternation exists as to balancing adequacy of resection with violation of adjacent talonavicular and calcaneocuboid (CC) articulations. As better understanding of nearby articular anatomy might be helpful in determining extent of resection, this study aims to identify differences in the anatomy of the CC articulation between feet with and without CNCs.Methods:A retrospective radiographic analysis of patients with symptomatic CNCs presenting to a single tertiary care pediatric hospital from 2010-2019 was performed. Patients without computed tomographic (CT) or magnetic resonance imaging (MRI) were excluded. Using either CT or MRI and standardized anatomic landmarks, the length and morphology of the calcaneal and cuboid articular surfaces were documented at the CC joint. When bilateral imaging was available in patients with a unilateral coalition, measurements were also made on the uninvolved side to provide a cohort of normal controls for comparison.Results:81 CNCs in 55 patients were identified along with18 normal feet. Mean age was 11.7 years at the time of advanced imaging. In the coalition group, an accessory cuboid facet was identified articulating with the calcaneal portion of the coalition in 61/81 (75.3%) feet. The mean total length of the cuboid articular surface measured 28.6 mm (range, 22.4-34.9 mm). The average length of the accessory facet was 10.6 mm (range, 6.0-15.5 mm) while the length of the primary cuboid articulation with the calcaneus was 15.9 mm (range, 6.4-23.2 mm). Thus, the accessory facet comprised 37.2% of the cuboid articular surface in these patients. Patients without CNCs had a significantly larger primary cuboid articulation with the calcaneus of 21.6 mm (p<0.0001). An accessory cuboid facet was identified in only a single foot in the normal cohort.Conclusion:An accessory cuboid facet is present in over 75% of patients with CNCs and comprised nearly 40% of the proximal cuboid articular length. Moreover, significant differences in the shape of the cuboid portion of the CC joint were present in feet with and without CNCs. This information may be useful when planning the extent of CNC surgical resection as including the coalition side of the accessory articulation may have value in restoring hindfoot motion.

Efficacy of Accessory Facet Views in the Detection of Occult Patellar Malreduction: A Biomechanical Analysis.

A simulated fracture model was used to determine the ability of the medial and lateral patellar facet views in detecting magnitudes of articular displacement. Transverse patellar fractures were simulated in ten patients. Medial and lateral translation of the distal fragment were evaluated in 1 mm increments and rotational malalignment along the longitudinal axis of the patella was evaluated in 5 mm increments. In comparison to the true lateral view, the utilization of the medial and lateral patellar facet views considerably improves detection of occult articular surface malreduction.

Accessory Cuboid Facet Associated With Calcaneonavicular Coalitions.

Calcaneonavicular (CN) coalitions are the most commonly encountered tarsal coalition. No study has assessed anatomic variations of the adjacent joints in the presence of a CN coalition. This study sought to identify differences in the anatomy of the calcaneocuboid (CC) articulation in feet with and without CN coalitions. An institutional review board approved retrospective analysis of patients with symptomatic CN coalitions presenting to a single tertiary care pediatric orthopaedic hospital was performed. Patients without computed tomographic or magnetic resonance imaging were excluded. The morphology and dimensions of the cuboid portion of the CC joint were documented. When contralateral imaging was available in patients with a unilateral coalition, the morphology of the uninvolved side was evaluated to provide a cohort of controls for comparison. Imaging was available for 55 patients who had a mean age of 11.7 years. There were 80 CN coalitions and 18 normal feet. An accessory cuboid facet was identified articulating with the calcaneal portion of the coalition in 60/80 (75%) feet in the coalition group. In feet with a coalition and an accessory facet, the mean total length of the cuboid articular surface measured 25.3 mm (range, 17.7 to 33.3 mm). The average length of the accessory facet was 10.7 mm (range, 5.4 to 15.5 mm), while the length of the primary vertical cuboid articulation with the calcaneus was 14.6 mm (range, 6.4 to 21 mm). The accessory facet comprised 42.3% of the cuboid articular surface in these patients. Feet without a coalition as well as feet with a coalition and no accessory facet had primary vertical cuboid articulations that were significantly larger than feet with a coalition and an accessory facet (P<0.0001). An accessory cuboid facet was identified in only a single control foot (5.6%). This study reports the frequent presence of an accessory cuboid facet in patients with CN coalitions. This facet was present in 75% of patients with CN coalitions and comprised just over 40% of the cuboid articular length. This anatomic variation represents a significant difference in CC joint morphology between feet with and without CN coalitions. This information may be useful when planning surgical resections. Level III-retrospective cohort study.

Subtle Dynamic Flatfoot Deformity: Is It More Than Stage I PTTD?

Adult acquired flat foot has long been considered synonymous with posterior tibial tendon dysfunction (PTTD), first described by Johnson and Strom in 1989. This is based on the authors’ clinical experience and a small case series described in 1994. However, there is little evidence that PTTD invariably leads to flat foot deformity. We propose a rethinking of stage I PTTD as subtle dynamic flatfoot, wherein adult acquired flat foot is driven largely by gastrocsoleus tightness and progressive hypermobility of the first ray. Clinical assessment should consist of careful evaluation of first ray stability as well as the spring ligament, tibiotalar range of motion, and impingement over the sinus tarsi. We present our preferred treatment strategy. Nonoperatively, patients are managed with a stretching program focused on the hamstrings and gastrocsoleus as well as the use of orthotics and night splint. Operative treatment consists of treatment of any areas of impingement and correcting the biomechanics of the foot and ankle with a Strayer, Cotton Osteotomy, and lateral column lengthening. Resection of the accessory facet of the talus is optional depending on preoperative symptoms.

Bilateral Accessory C1 and C2 Facet Joints; Clinical, Neuroradiological and Peroperative Findings in an Adult with Quadriparesis

Objectives Accessory C1 and C2 facet joints are very rare. Only few cases were reported in the literature. We report a case of bilateral accessory facets in an adult with special attention to clinical, neuroradiological, as well as peroperative findings. Case report A 37-year-old male presented with progressive quadriparesis. Radiology revealed bilateral posterior accessory C1 and C2 facet joints compressing the spinal cord with craniovertebral junction (CVJ) instability. Both accessory C1 and C2 facets with the posterior arch of the C1 were removed. Lateral mass screws and plates fixation at the C1 and C2 level, as well as fusion, were performed. Postoperatively, the patient recovered well. Conclusion In accessory C1 and C2 facet joints, when symptomatic, neuroradiological findings can guide to the proper diagnosis, to pathological understanding, and, ultimately, to management strategy.

The first ophthalmosaurid ichthyosaur from the Upper Jurassic of the Umbrian–Marchean Apennines (Marche, Central Italy)

AbstractThe first ophthalmosaurid ichthyosaur from the Upper Jurassic deposits of the Central–Northern Apennines (Marche, Italy) is here described for the first time. The specimen is relatively complete and is referred toGengasaurus nicosiaigen. et sp. nov. based on a unique combination of characters, including a peculiar condition of the preaxial accessory facet on the humerus. The faunal association of the ichthyosaur-bearing level indicates a late Kimmeridgian – earliest Tithonian age, and its finding contributes significantly to our knowledge of the diversity of Late Jurassic ichthyosaurs from the Western Tethys. Two shark teeth assigned to the order Hexanchiformes were also recovered in association with the ichthyosaur specimen, suggesting that scavenging of the carcass might have occurred.Gengasauruscan be referred to Ophthalmosauridae based on the reduced extracondylar area of the basioccipital, and the presence of a preaxial digit. It differs fromOphthalmosaurusspp. in several respects, including the shape of the posterior basisphenoid, the shape of the supraoccipital, the anteriorly deflected preaxial facet of the humerus, and a proximodistally shortened ulna. The new taxon actually shares diagnostic characters with both members of the two main lineages recovered in previous phylogenetic analyses, more nested within Ophthalmosauridae. The affinities ofGengasaurusto genera from both the northern and southern hemispheres also suggest that connectivity between pelagic habitats was high during the early Late Jurassic, allowing dispersal of some forms, followed by local, endemic divergence.

Differential diagnosis of pathologically induced upper and lower limb asymmetry in a burial from late medieval Ireland (CE 1439–1511)

This paper reports a case study from 15 to 16th century Ireland of a mature adult male with upper and lower limb asymmetry. All of the bones of the right upper and lower extremity were atrophied and demonstrated limb shortening. This individual also had severe scoliosis and accessory facets on the superior aspect of the distal ends of the right metatarsals. These facets were most likely caused by the individual walking predominately on his toes to make up for the height difference between the lower limbs. Based on the patterning of affected bones and associated pathological changes, the individual was diagnosed as suffering from cerebral palsy with right-sided hemiplegia. Few definite cases of cerebral palsy have been identified in the archaeological record and most often only include the shortening of one or two long bones. The case from Ballinderry provides one of the most definitive archaeological cases to date.

An anatomic study of the accessory anterolateral talar facet.

A small accessory facet with articular surface morphology is occasionally seen on the talus, bordering on the lateral end of the sinus tarsi. This facet has been named the accessory anterolateral talar facet. However, few anatomical studies have addressed this facet. Here we present the precise morphology of accessory anterolateral talar facet with emphasis on anatomical correlation between the presence of this facet and the angle of the infero-lateral surface of the talus (talar infero-lateral surface - TILS angle). A total of 22 (11 male, 11 female) adult cadavers with no known pathological conditions in the talocalcaneal joints were examined during educational dissection at Nagoya City University Medical School in 2013. After exclusion of 1 joint due to the poor condition of the talus, 43 talus (22 right, 21 left) were analysed. We judged the presence of the accessory anterolateral talar facet and measured TILS angle. We performed statistical analysis on the point of laterality, gender difference and the difference in the TILS angles in tali with or without the accessory anterolateral talar facets. An accessory anterolateral talar facet was identified in 11 (26%) of the 43 specimens. Of the 21 cadavers with paired talar specimens, 5 displayed the facet bilaterally. There was no sex difference and no significant laterality, however we found that TILS angle was significantly larger in accessory anterolateral talar facet positive samples than in negative ones.

Accessory talar facet impingement in pathologic conditions of the peritalar region in adults.

Associations between accessory anterolateral talar facet (AALTF) and sinus tarsi pain in adults have not been reported. This study aimed to investigate the clinical and imaging characteristics of pathologic conditions of the peritalar region in adults with painful accessory talar facet impingement (ATFI). We included 31 patients (aged 19-75 years) with persistent sinus tarsi pain who underwent surgery and had pathologic conditions of the peritalar region, including adult acquired flatfoot deformity (AAFD; 18 patients), ankle osteoarthritis (8 patients), and ankle instability (5 patients). Continuity between the articular surface of the posterior facet of the talus and AALTF was identified on preoperative computed tomography and magnetic resonance imaging (MRI) of the cartilage. In addition, focal abutting bone marrow edema (FABME) of the talus and calcaneal neck around the AALTF on short TI inversion recovery sequence MRI was confirmed. Subtalar arthroscopy was used to evaluate the AALTF surface characteristics. Pre- and postoperative objective scores were compared. Eight pre- and postoperative radiographic parameters were compared to confirm the effect of foot alignment changes after reconstructions on sinus tarsi pain with ATFI. Pre- and postoperative changes in FABME were compared with 17.1 (7-60) months of follow-up. Subjects underwent accessory facet resection with balancing reconstruction. Arthroscopically, 66% of patients showed a focal defect on the AALTF cartilage surface, and 83% showed attenuation of the posterior capsular ligament. All x-ray parameters in AAFD patients showed significant improvement postoperatively (P < .001). Mean objective scores improved from 54.0 preoperatively to 91.0 postoperatively (P < .001). Sinus tarsi pain and FABME were absent in all cases at the final follow-up. AALTF represents a new etiology of subsequent painful intra-articular talocalcaneal impingement. When addressing sinus tarsi pain, it is important to detect the signs of AALTF on MRI of the cartilage and accompanying FABME. Level IV, retrospective case series.

Morphological traits in sacra associated with complete and partial lumbarization of first sacral segment

Background context Transitional states of vertebrae at the lumbosacral junction are associated with low back pain. Lumbarization may present as partial (incomplete separation of S1–S2 bodies and their neural arches) or complete separation of the S1 from the S2 segment in a sacrum. Separation of S1 entails alteration of the anatomy at the lumbosacral junction that affects load bearing at the region. Purposes To 1) identify characteristic structural features in sacra associated with lumbarization of the S1 sacral element; 2) compare linear dimensions and surface areas in such sacra with that of the normal samples; 3) calculate relative contributions of different dimensions in the variant sacral corpuses by working out indices; and 4) analyze load bearing at these sacra in light of their altered morphology. Study design Three hundred thirty-two dried human sacra were measured for specific dimensions and surface areas. They were screened for partial or complete lumbarization of the S1 segment. Outcome measures All parameters and indices of the lumbarized specimen were compared with those in the normal sacra. Methods Seven linear dimensions and five surface areas were measured in 332 sacra. Nine indices were formulated from them. Sacra with partial or complete lumbarization of S1 were analyzed for all the parameters and evaluated for their morphological variations and traits. Results A total of 3.9% of sacra presented lumbarization, seven (2.1%) with partial and six (1.8%) with complete separation of the S1. Sacrum with partial lumbarization presented parameters similar to the normal variety. Auricular surfaces in these sacra were situated lower than normal with negligible contribution from the S1 segments. Parameters in sacral samples showing complete separation of S1 (with remaining S2-S5 segments) were smaller than normal dimensions except for some. These “baseline” (S2–S5) sacra transmitted load to the sacroiliac joints via the S2 and S3 elements. Four of six of these samples demonstrated unilateral or bilateral accessory facets between the transverse elements of the free S1 segment and the ala of the remaining sacrum (formed by S2). Significant load passed through the accessory articulations that abutted near the sacroiliac joints. A good number of these sacra showed highly attenuated laminae and at times presented incomplete fusion at the spines (spina bifida). Conclusions Lumbarization involved distinct anatomical alterations at the S1–S2 junctions. Partially lumbarized samples showed 1) gap (mean 1.43 mm) between S1 and S2 bodies; 2) incomplete separation between S1 and S2 neural arch elements with the S1 arches resembling lumbar laminae; 3) well-developed “baseline” (S2–S5) segments; and 4) “low-down” (positioned at S2–S3) auricular surfaces. Complete separation of S1 involved 1) smaller overall dimensions with diminished facet depth, sacral height, and facet area at S1; 2) auricular surface areas comparable to the normal and greater than those found in the partially lumbarized specimen; 3) large “baseline” (S2–S5) sacra with “high-up” auricular surfaces (positioned at S2–S3); 4) occasional S1–S2 accessory articulations; and 5) small zygapophyseal joints and attenuated sacral laminae with high sacral hiatuses associated at times, with “spina bifida.”

Morphometric analysis and identification of characteristic features in sacra bearing accessory articulations with L5 vertebrae

Background context Occurrence of transitional vertebrae at the lumbosacral junction, especially accessory lumbosacral articulations (partial sacralization of the L5 vertebrae), is not uncommon. These transitional states are frequently associated with low back pain situations requiring surgical intervention. Purpose The study aimed to investigate the presence of distinct morphological features and structural peculiarities associated with these sacra. The features related to sacra bearing L5-S1 transitions might be significantly different from those of the normal sacra. This study tries to understand whether accessory L5-S1 articulations demonstrate altered mechanisms of load transfer as a result of structural changes at the L5–S1 junction. Study design Morphometric measurements of several linear dimensions and articular areas were obtained from 332 sacra. Thirty sacra demonstrated unilateral accessory facets on their ala. Twelve sacra showed bilateral accessory lumbosacral articulations. Indices were calculated based on the linear dimensions and on the surface areas of the bones to detect proportional contributions of the dimensions and surface areas to the overall structure of all the sacra. Outcome measures All the parameters obtained from the transitional sacra were compared with the same parameters worked out on 290 normal sacra. All parameters in the sacra bearing accessory articulations were statistically compared with parameters in the normal sacra. Method Seven linear dimensions and five surface areas were measured in 290 normal sacra. Thirty sacra bearing unilateral accessory articular facets and 12 sacra with bilateral accessory facets on their alae were measured for the same linear parameters and surface areas. Nine indices were calculated from these measurements in both the normal and transitional sacra and statistically verified. Results Analysis of the results indicated that sacra bearing accessory articulations, in comparison to the normal, carried their auricular surfaces at a higher level; possessed load bearing features mainly confined to the two upper sacral segments; showed lesser distances between the facet joints; showed smaller distance of the coronal plane of the facet joints from the posterior aspect of the S1 vertebral body; exhibited smaller and more coronally oriented facet joint surfaces; and exhibited smaller body width and height. The auricular surface area and superior surface of the body of S1 in these “transitional” sacra were similar in comparison to normal sacra. Linear dimensions in sacra with bilateral accessory articulations were smaller than the ones having unilateral accessory L5-S1 articulations. Conclusions Lumbosacral accessory articulations constituted the bulk of transitional variations at the junction. Accessory articulations were unilateral (9%) and bilateral (3%) with a total of 12% of all studied samples (n=332) demonstrating this type L5–S1 transition. Sacra with lumbosacral pseudoarticulations were associated with different anatomical features in contrast to normal sacra. Analysis of these structural differences with the normal variants may possibly help in understanding the biomechanical properties at these transitional sites. Evaluation of the relative proportions of dimensions within these bones may help plan surgical interventions or probably predict the pattern of abnormal weight bearing in these sacra.

The Australian Cretaceous ichthyosaur Platypterygius australis: a description and review of postcranial remains

ABSTRACT Australian Cretaceous ichthyosaur material is amongst the most complete in the world. This study describes postcranial remains referred to the upper Albian species Platypterygius australis, including the first record of pelvic and hind limb elements for this taxon. A combination of phylogenetically significant traits such as lack of fusion between the atlas-axis complex and third cervical centrum, the presence of three distal facets on both the humerus/femur for accommodation of the anterior zeugopodial elements plus the radius/tibia and ulna/fibula, concave preaxial accessory facet surfaces on both the humerus and the femur, and complete fusion of the ischiopubis with closure of the obturator foramen, are considered diagnostic for the species and (in conjunction with other previously identified cranial/postcranial features) may serve to distinguish P. australis from the other paleogeographically disparate Platypterygius spp.

Accessory Anterolateral Facet of the Pediatric Talus

The accessory anterolateral talar facet may be associated with talocalcaneal impingement in the painful flatfoot. We performed an anatomic study to identify this accessory facet and its associated osteologic features. Within the Hamann-Todd Human Osteological Collection, seventy-nine paired tali and calcanei were identified among forty-three skeletons from individuals who had had an average age of 13.4 years at the time of death. Each specimen was surveyed for an accessory anterolateral talar facet, a calcaneal neck anterior extension facet, a dorsal talar beak, and the talocalcaneal facet pattern. Measurements included the angle of Gissane, posterior facet inclination, calcaneal neck length, posterior facet length, overall calcaneal and talar lengths, and accessory facet dimensions. Lateral radiographs of specimens with accessory facets were made in neutral and everted subtalar alignment. An accessory anterolateral talar facet was identified in twenty-seven (34%) of the seventy-nine specimens and was large in two (2.5%). Of the thirty-six skeletons with paired specimens, fifteen had an accessory facet and, of those, ten had the finding bilaterally. Degenerative changes or tarsal coalitions were not observed. Lateral radiographs demonstrated that subtalar eversion obscured observation of the facet. The accessory facet was associated with greater mean age (16.7 compared with 10.9 years; p < 0.0001), male sex (63% compared with 21%; p = 0.011), and a smaller mean angle of Gissane (116.2 degrees compared with 122.2 degrees; p = 0.018). Relative accessory facet volume was positively correlated with increased relative calcaneal posterior facet length (r = 0.53, p = 0.029). The accessory facet was significantly associated with dorsal talar beaking (29% compared with 4%; p = 0.028). An accessory anterolateral talar facet was found in 34% of the specimens in a pediatric osteologic collection. The facet was associated with male sex, a smaller angle of Gissane, and dorsal talar beaking.

Relationship between the tendon of the long head of biceps brachii and the glenoidal labrum in humans

The relationship between the tendon of the long head of the biceps brachii muscle and the glenoidal labrum was investigated in a large number of dissected human shoulder joints. In about 70% of the specimens examined, the labrum was deficient at the posterosuperior margin of the glenoid because the tendon of the biceps coursed over this margin to blend with the labrum. Because of this, a small crescentic accessory facet was observed at the posterosuperior margin of the glenoid. In the majority of cases, the tendon of the biceps blended with the glenoidal labrum, and only a small part of the tendon attached to the supraglenoid tubercle. However, in 25% of the specimens, the major portion of the tendon was attached to the supraglenoid tubercle.