Apparatus Reconstruction Research Articles

The myocutaneous gastrocnemius flap for periprosthetic joint infection of the knee.

Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) presents significant challenges, especially in elderly and comorbid patients, often necessitating revision surgeries. We report on a series of patients with confirmed PJI of the knee and concomitant soft-tissue/extensor apparatus defects, treated by using pedicled myocutaneous medial or lateral sural artery perforator (MSAP/LSAP) gastrocnemius flaps. Our retrospective study at the Center for Musculoskeletal Infections, included patients with knee PJI undergoing pedicled myocutaneous MSAP/LSAP gastrocnemius flap reconstruction for combined soft tissue and extensor apparatus defects. The tendinous back of the gastrocnemius muscle was used and, if required, the Achilles tendon for extensor apparatus reconstruction, with the skin island addressing the cutaneous defect. Perioperative complications and postoperative outcomes after 1 year were evaluated, including functional and clinical assessments with the American Knee Society Score (AKSS). Eight patients (mean age 73 years; five female) were included, predominantly with Staphylococcus aureus infections. Six patients involved isolated MSAP flaps, two were extended with the Achilles tendon. The median time for wound healing was 9 days. Short-term follow-up showed successful reconstruction in seven patients, with minor wound dehiscence in one patient. One patient required flap revision for a perigenicular haemato-seroma and two patients were diagnosed with new haematogenous PJI infection. Significant improvement in AKSS scores after surgery was observed (functional AKSS: median 33-85; clinical AKSS: median 64-91, p = 0.001). Pedicled myocutaneous MSAP/LSAP gastrocnemius flaps offer a safe, reliable and versatile option for reconstructing combined soft tissue and extensor apparatus defects in PJI after TKA. This approach yields excellent functional outcomes with minimal peri- and postoperative complications, which is particularly beneficial in elderly and comorbid patients and feasible in settings without microsurgical availability. Level IV.

Interactive editing of virtual chordae tendineae for the simulation of the mitral valve in a decision support system

PurposeDecision support systems for mitral valve disease are an important step toward personalized surgery planning. A simulation of the mitral valve apparatus is required for decision support. Building a model of the chordae tendineae is an essential component of a mitral valve simulation. Due to image quality and artifacts, the chordae tendineae cannot be reliably detected in medical imaging.MethodsUsing the position-based dynamics framework, we are able to realistically simulate the opening and closing of the mitral valve. Here, we present a heuristic method for building an initial chordae model needed for a successful simulation. In addition to the heuristic, we present an interactive editor to refine the chordae model and to further improve pathology reproduction as well as geometric approximation of the closed valve.ResultsFor evaluation, five mitral valves were reconstructed based on image sequences of patients scheduled for mitral valve surgery. We evaluated the approximation of the closed valves using either just the heuristic chordae model or a manually refined model. Using the manually refined models, prolapse was correctly reproduced in four of the five cases compared to two of the five cases when using the heuristic. In addition, using the editor improved the approximation in four cases.ConclusionsOur approach is suitable to create realistically parameterized mitral valve apparatus reconstructions for the simulation of normally and abnormally closing valves in a decision support system.

Gondolelloid multielement conodont apparatus (Scythogondolella) from the Lower Triassic of Jiangsu, East China, revealed by high-resolution X-ray microtomography

The application of high-resolution X-ray microtomography on conodont natural assemblages has provided new information on the structure of the elements and enabled the three-dimensional reconstruction of apparatuses. We herein report four conodont natural assemblages from uppermost Lower Qinglong Formation, Longtan, Nanjing, East China. Using X-ray microtomography, we reconstructed the apparatus of the end-Smithian (Olenekian, Early Trassic) Scythogondolella milleri. Our result confirms that Scythogondolella has an octomembrate apparatus composed of 15 elements (a single S0 element, two pairs of S1–4, M and P1–2 elements) like other gondolelloid apparatuses that have been tested by their corresponding natural assemblages, including Neogondolella, Novispathodus and Nicoraella. Element morphology of Scythogondolella closely resembles that of Neogondolella apparatus from the Illyrian (Anisian, Middle Triassic) of Monte San Giorgio: an alate (hibbardellan) S0 element with two long lateral processes that meet at a denticle anterior of the cusp, a bipennate (hindeodellan) S3 element with a bifurcated anterior process branching from the third denticle anterior of the cusp and an enantiognathiform S2 element with two dissimilar processes of nearly equal in length. It differs from the latter in the length of the inner-lateral process of M element and the posterior process of S0 and S3–4 elements without considering the obvious morphological differences in P elements between them. The element positional homologues of Scythogondolella conforms to those of the standard 15-element plan shared primitively among ozarkodinin, prioniodinin and prioniodontid conodonts, and again confirms that the breviform digyrate elements of cypridodellan and enantiognathiform morphotypes occupy the S1 and S2 positions, respectively, within the superfamily Gondolelloidea.

Microstructure of Triassic conodont Pseudofurnishius murcianus van den Boogaard: Functional implications

Pseudofurnishius murcianus van den Boogaard is a Triassic conodont with a very characteristic morphology, a blade with a rostral platform heavily denticulated, that makes it easily distinguishable from other coeval species. It is a well-know taxon that has been the object of several palaeobiological works, focused on their apparatus reconstruction, ontogeny and, recently, their P1 element function. In order to increase our palaeobiology knowledge of this taxon we undertook a histological analysis to corroborate the functional hypothesis established for this conodont. The histological study demonstrated the presence of different microstructural types, suggesting that they are functional adaptions due to the slicing function that the P1 elements performed

Entire mitral reconstruction with porcine extracellular matrix in an acute porcine model

ObjectiveThe objective of our study was to investigate the feasibility of reconstructing the entire mitral valvular and subvalvular apparatus in pigs using a modified tube graft design made of 2-ply small intestinal submucosa extracellular matrix. MethodsThe reconstructions were performed in an acute 80-kg porcine model with 8 pigs, each acting as its own control. A modified tube graft was designed from a sheet of 2-ply small intestinal submucosa extracellular matrix. Before and after mitral valve reconstruction, echocardiography was used to assess mitral regurgitation, left ventricular outflow tract obstruction due to systolic anterior motion, mitral stenosis, leaflet mobility, and leaflet geometry. ResultsThe reconstructed mitral valves were fully functional without any observable echocardiographic signs of regurgitation. We did not observe any left ventricular outflow tract obstruction due to systolic anterior motion nor any mitral valve stenosis, despite a diminished septal-lateral distance after reconstruction. The reconstruction had a reduced tenting area, a reduced coaptation length (9.6 ± 1.7 mm vs 7.9 ± 1.0 mm, P = .010, diff = −1.7 mm, 95% confidence interval, −3.1 to −0.4 mm), and atrial bending of both leaflets. ConclusionsIn this acute porcine study, entire mitral valvular and subvalvular apparatus reconstruction using a modified tube graft design made from 2-ply small intestinal submucosal extracellular matrix was feasible. The 2-ply small intestinal submucosa extracellular matrix could withstand the pressure exerted by the left ventricle without any signs of tearing or rupture. These promising results warrant further assessment of both the annular geometry and the long-term durability.

Apparatus architecture of the conodont Nicoraella kockeli (Gondolelloidea, Prioniodinina) constrains functional interpretations

AbstractWe reconstruct the apparatus architecture of the gondollelid conodont Nicoraella kockeli based on fused clusters from the early Middle Triassic (middle Anisian, Pelsonian) of Luoping County, east Yunnan Province, south‐west China. This material was characterized non‐invasively using synchrotron x‐ray tomographic microscopy and the ensuing data analysed using computed tomography, allowing us to infer the composition, homologies and architectural arrangement of elements within the apparatus. Much of the original three‐dimensional architecture of the apparatus is preserved and our apparatus reconstruction is the best characterized of any taxon within the superfamily Gondolelloidea. This allows us to test architectural models for gondolelloids and prioniodinins, more generally, as well as the functional interpretations based upon them. In particular, we reject a recent functional interpretation of the conodont feeding apparatus which was based on a biomechanically‐optimized inference of apparatus architecture in a close gondolelloid relative of Nicoraella. Nevertheless, our architectural model provides a foundation for future functional interpretations of gondolleloids and prioniodinins, more generally.

The apparatus composition and architecture of Erismodus quadridactylus and the implications for element homology in prioniodinin conodonts

AbstractThe apparatus composition and architecture of prioniodinin conodonts is poorly understood, largely because few prioniodinin taxa are represented by articulated oral feeding apparatuses (natural assemblages) in the fossil record, but also due to the highly variable gradational morphology of their constituent elements that makes apparatus reconstruction problematic. We describe here a natural assemblage of Erismodus quadridactylus (Stauffer), a prioniodinin, from the Sandbian (Late Ordovician) of North Dakota, USA. The assemblage demonstrates that the apparatus architecture of Erismodus is similar to those of late Palaeozoic prioniodinins namely, Kladognathus Rexroad and Hibbardella Bassler, but also has similarities with ozarkodinin apparatuses. In addition, there is evidence to suggest that E. quadridactylus shares topological similarities to balognathid architecture, with respect to the position of its inferred P elements. The apparatus composition and architecture presented here indicate that, at least with respect to the M–S array, an ‘ozarkodinin‐type’ bauplan is probably more widely representative across prioniodontids. The assemblage demonstrates that element morphotypes traditionally considered to lie within the S array are M elements, whereas others traditionally interpreted as P elements are found in the S array. These observations are used as a basis for refining concepts of element homology among prioniodinin conodonts and their closest relatives.

Middle Triassic conodont apparatus architecture revealed by synchrotron X-ray microtomography

The composition of conodont apparatuses is crucial for understanding the feeding mechanisms of these early vertebrates. However, the multielement apparatus reconstructions of most species remain equivocal because they have been inferred from loose element collections, guided by knowledge from rare articulated ‘bedding plane assemblages’ and fused clusters, often from distantly related taxa. Even these natural assemblages can be difficult to interpret because the component elements can be closely juxtaposed or embedded in matrix, making it hard to discern the morphology of each element and their relative positions within the architecture of the feeding apparatus. Here we report five exceptionally preserved conodont clusters from the Middle Triassic Luoping Biota, Yunnan Province, Southwest China. These materials were scanned using synchrotron radiation X-ray tomographic microscopy (SRXTM), revealing the morphology and positional homology of the component elements in the fused clusters. We confirm that the apparatus of Nicoraella was composed of eight types of elements, comprising a total of 15 elements. SRXTM reveals the positional homologies of the component elements, viz. a single alate element is located in the S0 position, flanked successively abaxially by pairs of breviform digyrate S1 and S2 elements, bipennate S3 and S4 elements, and a pair of inwardly curved breviform digyrate M elements. Carminate elements occupy the P1 and P2 positions. The apparatus of Nicoraella is among the most completely characterised of all conodonts and serves as a template for the reconstruction of gondollellids.

A new icriodontid conodont cluster with specific mesowear supports an alternative apparatus motion model for Icriodontidae

Increasing numbers of conodont discoveries with soft tissue preservation, natural assemblages and fused clusters of the hard tissue have strengthened the hypothesis regarding the function and mechanism of the conodont feeding apparatus. Exceptional fossil preservation serves as a solid basis for modern reconstructions of the conodont apparatus illustrating the complex interplay of the single apparatus elements. Reliable published models concern the ozarkodinid apparatus of Pennsylvanian and Early Triassic conodonts. Recognition of microwear and mammal-like occlusion, especially of platform elements belonging to individuals of the genus Idiognathodus, allows rotational closure to be interpreted as the crushing mechanism of ozarkodinid platform (P1) elements. Here we describe a new icriodontid conodont cluster of Caudicriodus woschmidti that consists of one pair of icriodontan (I) and 10 pairs of coniform (C1–5) elements, with I elements being preserved in interlocking position. The special kind of element arrangement within the fused cluster provides new insights into icriodontid apparatus reconstruction and notation of elements. However, orientation of coniform elements is limited to a certain degree by possible preservational bias. Four possible apparatus models are introduced and discussed. Recognition of specific wear on denticle tips of one of the icriodontan elements forms the basis for an alternative hypothesis of apparatus motion. Analysis of tip wear suggests a horizontal, slightly elliptical motion of opposed, antagonistically operating I elements. This is supported by similar tip wear from much better preserved, but isolated, elements of Middle Devonian icriodontids. More detailed interpretation of the masticatory movement will allow enhanced understanding of anatomical specifications, diet and palaeobiology of different euconodont groups.

Revision surgical intervention in patients with chronic suppurative otitis media with cholesteatoma after sanitation operations with tympanoplasty

The authors analyzed surgical treatment of 438 patients with chronic suppurative otitis media with cholesteatoma; of them 401 patients have undergone various types of sanitation interventions with sound conducting apparatus reconstruction: 180 persons had the closed type interventions and 221 persons had modified radical surgery. The average follow-up period was 39 months. 226 patients (52 children at the age from 4 to 15 years and 174 adults above 15 years old) had surgical revision at different stages after the primary surgery. Residual cholesteatoma was detected in 26.0% of adults and 21.3% of children, recurrent one – in 7.8% and 7.5% respectively, and correlation of primary and residual cholesteatoma localization was found. The study showed a higher risk of recurrent cholesteatoma development in patients that underwent sanitizing operation with the closed type tympanoplasty. It is noted that the incidence of the disease recurrence increases with the lapse of time after the primary surgery. The authors developed an algorithm for postoperative management of patients with chronic suppurative otitis media with cholesteatoma.

Des trucs et astuces pour la replantation digitales chez les enfants

Introduction The amputation of the thumb or any other finger in children has the absolute indication of replantation in order to avoid the psychological trauma suffered by the child - the future adolescent and young adult. Functional results, sensitivity and aesthetic outcomes are better than in adults. The younger the patient, the more difficult reconstructive techniques of bone, tendon and soft tissue repair, vascular or nerve micro-anastomosis, postoperative care are. The very good outcome, fast social reintegration and satisfaction of the parents, deserves all the needed effort. Material and methods The study is based on 5 cases of digital amputation in children (4 boys and 1 girl) aged between 3 and 4 years and 6 months old. In 2 cases, the amputation was at the first phalanx of the index. In other 2 cases, the amputation was at the second phalanx of the middle finger and in the fifth case, at the second phalanx of the fourth finger. The trauma occurred during housekeeping activities such as wood cutting using an ax. Bone repair was difficult due (with needle) to the need of keeping the growth cartilage intact. The small vessel diameter constrained us to use 11-0 suture thread and a reduced number of stitches. Postoperative analgesia played an important role in preventing vasospasm and increased the chance of a successful replantation. The splinting was done taking into account the principles of immobilization in children. The 4 year old child developed a postoperative venous insufficiency that we managed successfully. In one case, a secondary surgical intervention was necessary for the extensor apparatus reconstruction. Discussions In order to evaluate the outcomes, we used for sensibility the Weber and Semmes-Weinstein tests. According to Nakamura Tamai criteria, the outcomes were excellent in all cases. Conclusions Replantation of the amputated finger in children has an absolute indication. The younger the patient the more difficult the surgical repair is, but is counterbalanced by the good functional and aesthetic results.

A 17‐element conodont apparatus from the Soom Shale Lagerstätte (Upper Ordovician), South Africa

Abstract: Natural assemblages of a new conodont taxon, Notiodella keblon, from the Upper Ordovician Soom Shale Lagerstätte of South Africa contain 17 elements. This is the first time that a 17‐element apparatus plan has been unequivocally demonstrated in conodonts. The apparatus comprises paired P1, P2, P3, M, S1, S2, S3 and S4 elements and an unpaired, axial S0 element and provides a new template for use in the reconstruction of apparatuses from the collections of dispersed elements, particularly for those with icrion‐bearing P1 elements and perhaps for other balognathids.

Extensor Function After Medial Gastrocnemius Flap Reconstruction of the Proximal Tibia

Reconstruction of the extensor mechanism after resection of the proximal tibia is challenging, and several methods are available. A medial gastrocnemius flap commonly is used, although it may be associated with an extensor lag. This problem also is encountered, although perhaps to a lesser extent, with other techniques for reconstruction of the extensor apparatus. It is not known how such lag develops with time and how it correlates with functional outcome. We therefore (1) assessed patellar height with time, (2) correlated patellar height with function using the Musculoskeletal Tumor Society (MSTS) score, and (3) correlated patellar height with range of motion (ROM) after medial gastrocnemius flap reconstruction. Sixteen patients underwent tumor endoprosthesis implantation and extensor apparatus reconstruction between 1997 and 2009 using a medial gastrocnemius flap after sarcoma resection of the proximal tibia. These patients represented 100% of the population for whom we performed extensor mechanism reconstructions during that time. The minimum followup was 2 years (mean, 5 years; range, 2-11 years). Fourteen patients were alive at the time of this study. We used the Blackburne-Peel Index to follow patellar height radiographically with time. Functional outcomes were assessed retrospectively using the MSTS, and ROM was evaluated through active extensor lag and flexion. Eleven patients had patella alta develop, whereby the maximal patellar height was reached after a mean of 2 years and then stabilized. More normal patellar height was associated with better functional scores, a smaller extensor lag, but less flexion; the mean extensor lag (and flexion) of patients with patella alta was 17° (and 94°) compared with only 4° (and 77°) without. In our patients patella alta evolved during the first 2 postoperative years. Patella alta is associated with extensor lag, greater flexion, and worse MSTS scores. Surgical fixation of the patellar tendon more distally to its anatomic position or strict postoperative bracing may be advisable. Level IV, clinical cohort study. See the Guidelines for Authors for a complete description of levels of evidence.

Lanea carlsiConodont Apparatus Reconstruction and its Significance for Subdivision of the Lochkovian

Slavik, L. 2011. Lanea carlsi conodont apparatus reconstruction and its significance for subdivision of the Lochkovian. Acta Palaeontologica Polonica 56 (2): 313–327.

Footwear traction and knee joint moments

Patellar complications are a source of poor total knee arthroplasty (TKA) outcomes that can require re-operation or prosthetic revision. Complications can occur with or without patellar resurfacing. The objective of this work is to answer six questions. (1) Have risk factors been identified, and can they help to prevent patellar complications? Patellar complications are associated with valgus, obesity, lateral retinacular release, and a thin patella. Selecting a prosthetic trochlea that will ensure proper patellar tracking is important. Resurfacing is an option if patellar thickness is greater than 12 mm. (2) What is the best management of patellar fracture? The answer depends on two factors: (a) is the extensor apparatus disrupted? and (b) is the patellar implant loose? When either factor is present, revision surgery is needed (extensor apparatus reconstruction, prosthetic implant removal). When neither factor is present, non-operative treatment is the rule. (3) What is the best management of patellar instability? Rotational malalignment should be sought. In the event of femoral and/or tibial rotational malalignment, revision surgery should be considered. If not performed, options consist of medial patello-femoral ligament reconstruction and/or medialization tibial tuberosity osteotomy. (4) What is the best management of patellar clunk syndrome? When physiotherapy fails, arthroscopic resection can be considered. Recurrence can be treated by open resection, despite the higher risk of complications with this method. (5) What is the best management of anterior knee pain? The patient should be evaluated for causes amenable to treatment (fracture, instability, clunk, osteonecrosis, bony impingement on the prosthetic trochlea). If patellar resurfacing was performed, loosening should be considered. Otherwise, secondary resurfacing is appropriate only after convincingly ruling out other causes of pain. A painstaking evaluation is mandatory before repeat surgery for anterior knee pain: surgery is not in order in the 10% to 15% of cases that have no identifiable explanation. (6) What can be done to treat patellar defects? Available options include re-implantation (with bone grafting, cement, a biconvex implant, or a metallic frame), bone grafting without re-implantation, patellar reconstruction, patellectomy (best avoided due to the resulting loss of strength), osteotomy, and extensor apparatus allograft reconstruction.V, expert opinion.

DISRUPTED CONODONT BEDDING PLANE ASSEMBLAGES, UPPER BAKKEN FORMATION (LOWER MISSISSIPPIAN) FROM THE SUBSURFACE OF WESTERN CANADA

Abstract Disrupted conodont bedding plane assemblages are described from two laterally equivalent mudstone core samples of the Lower Mississippian upper shale member of the Bakken Formation in the subsurface of southeastern Alberta and southwestern Saskatchewan. The core bedding plane conodont assemblage representing the bispathodid biofacies from southeastern Alberta (Locality 1) shows little evidence of winnowing. Thus, this assemblage, along with collections of discrete conodont elements, is a potential source of data for reconstructing paleoecology and taphonomy as well as for testing apparatus reconstructions. The assemblage representing the siphonodellid biofacies from the southwestern Saskatchewan core (Locality 2) shows evidence of a greater degree of breakage and winnowing of elements, making it less suitable as a source of data. Postmortem compaction of mudstones and processing methods also affect the preservation of the conodont elements, due to breakage along lines of fracture in the elements....

Comparative pre- and postoperative results analysis of functional state of the esophagus assessment in patients with various stages of achalasia☆

The aim of this study was to evaluate main results of morpho-functional state of the esophagus assessment in patients with various stages of achalasia before and after surgical treatment. Between 1993 and 2002, a total of 65 patients with achalasia (26 males, 39 females; mean age 44.5+/-14.0 years; range 16-79) underwent specific type of surgical treatment based on the results of functional state of the esophagus assessment. Barium swallow, manometry and 24-h pH-metry were performed by standard methods; the main parameters of each study were evaluated before and after operation. Patients were divided into three groups according to the esophageal diameter (barium swallow examination data). Group I (n = 22, diameter < 4 cm), group II (n = 35, diameter from 4 to 7 cm), group III (n = 8, diameter > 7 cm, with the cardiac stenosis and S-shape deformation of the distal esophagus). All the patients in groups I and II underwent esophagocardiomyotomy with the creation of dilating antireflux cardia by Onopriev (fundoplication + esophageal ligament apparatus reconstruction). Five patients in group III with the cardiac stenosis underwent resection of the cardia with segmental esophagocardioplasty, three patients with the cardiac stenosis and sigmoid esophagus underwent resection of the stenosed cardia, extirpation of the esophageal muco-submucosal layer with subsequent replacement of it with the left colon placed in saved muscular sheath of the esophagus. There were no deaths or reoperations. The study showed that a decrease of both maximal and residual LES pressures after operation in group I (from 24.3+/-3.8 to 21.7+/-2.4 and from 17.2+/-2.4 to 11.8+/-1.4, respectively) and group II (from 29.6+/-2.6 to 21.7+/-2.4 and from 21.7+/-3.1 to 11.8+/-1.4, respectively) of patients with achalasia enables to eliminate obstruction and therefore to decrease esophageal diameter. We suggest that dilating antireflux cardia provides adequate bolus passage and properly realizes antireflux barrier function, maintaining the esophageal distal pH within the physiological ranges even without esophageal peristalsis restoration, and dilating mechanism serve to prevent the recurrence of the disease. Despite excellent relief of dysphagia and functional state of the esophagus improvement, the main values of functional state assessment results in group III of patients were beyond physiological ranges.

Siluro‐devonian Conodonts from the Camelford Limestone, Wellington, New South Wales, Australia

Conodont data have been utilized to identify the Silurian/Devonian boundary within the Camelford Limestone near Wellington, NSW. Conodont faunas are documented from the eosteinhornensis Zone to early delta Zone with one new species of Walliserodus (W. multistriatus) and two new species of Ozarkodina (O. brocki and O. camelfordensis) described. An apparatus reconstruction of Belodella anomalis is also presented.

Extensor apparatus reconstruction with Leeds-Keio ligament in total knee arthroplasty

The outcome of reconstruction of patellar tendon rupture in total knee arthroplasty has not been particularly good. Five cases of extensor mechanism rupture in total knee arthroplasty are presented. The surgical technique consisted of suture of the extensor apparatus augmented by a Lees-Keio ligament. Active extension of — 10° was achieved by all the patients with flexion of 90° or more. One superficial infection developed, which required antibiotic treatment. In the course of time, the reconstruction elongated less than 1 cm without significantly affecting function. Although the numbers are small and the complications significant, the final results of this technique have been reasonable. The technique permits early weight bearing and immediate mobilization, which enables an adequate range of motion to be achieved.

Apparatus composition and structure of the Pennsylvanian conodont genus Gondolella based on assemblages from the Desmoinesian of northwestern Illinois, U.S.A.

Gondolella pohli new species assemblages, from the Desmoinesian of Illinois, confirm that the initial apparatus reconstruction of the conodont genus Gondolella was incomplete and support later reconstructions based on discrete elements.Gondolella pohli is the first species of a biostratigraphically important conodont genus to be based primarily on assemblages and to be placed within a known phylogeny. The 43 assemblages confirm the presence of seven distinct element types in the Gondolella apparatus and permit the reconstruction of each of these to a greater degree than previously possible. Because the assemblages are probably all fecal, the apparatus of the closely related Neogondolella is used to interpret the apparatus plan—the position and identity of the 15 elements—single pairs of Pa, Pb, M, Sb1, and Sb2 elements, two pairs of Sc elements, and an unpaired bilaterally symmetrical Sa element in the Gondolella apparatus. Using the similarity of the latter to the apparatuses of the better known ozarkodinids, we infer a three-dimensional fanlike apparatus architecture for the prioniodinid Gondolella. Gondolella is apparently restricted to the Pennsylvanian and probably evolved in the Early Pennsylvanian from the Idioprioniodus-Embsaygnathus lineage by loss of the Pa element posterior process and by remodelling of the other apparatus elements. Some species in the Idioprioniodus-Gondolella lineage are atypical among prioniodinids in having developed a Pa element platform; the lineage is also noteworthy because both ancestor and descendant inhabited low-energy, low pH environments during the Pennsylvanian.