Morphometry of Glenoid Cavity

Objectives: Knowledge of the shape and dimensions of the glenoid are important in the design and fitting of glenoid components for total shoulder arthroplasty. An understanding of variations in normal anatomy of the glenoid is essential while evaluating pathological conditions like osseous Bankart lesions and osteochondral defects. Methods: This study was done on 202 dry, unpaired adult human scapulae of unknown sex belonging to the south Indian population. Three glenoid diameters were measured, the superior-inferior diameter, anterior-posterior diameter of the lower half and the anterior-posterior diameter of the upper half of the glenoid. Based on a notch present on the anterior glenoid rim, variations in the shape of the glenoid cavity were classified as inverted comma shaped, pear shaped and oval. Results: The average superior-inferior diameter on right and the left sides were 33.67±2.82mm and 33.92±2.87mm respectively. The average anterior-posterior diameter of the lower half of the right glenoid was 23.35±2.04mm and that of the left was 23.02±2.30mm. The mean diameter of the upper half of the right glenoid was 16.27±2.01mm and that of the left was 15.77±1.96mm. Conclusion: The dimensions of the glenoid observed in the present study were lesser than those recorded in the studies done on other populations. This fact may be taken into consideration while designing glenoid prostheses for the south Indian population. The current study recorded a higher percentage of glenoid cavities having the glenoid notch as compared to earlier studies. While evaluating defects/lesions of the glenoid, this fact could be useful

Consequences of reaming with flat and convex reamers for bone volume and surface area of the glenoid : a basic science study

Background: The effect of reaming on bone volume and surface area of the glenoid is not precisely known. We hypothesize that (1) convex reamers create a larger surface area than flat reamers, (2) flat reamers cause less bone loss than convex reamers, and (3) the amount of bone loss increases with the amount of version correction. Methods: Reaming procedures with different types of reamers are performed on similar-sized uniconcave and biconcave glenoids created from Sawbones foam blocks. The loss of bone volume, the size of the remaining surface area, and the reaming depth are measured and evaluated. Results: Reaming with convex reamers results in a significantly larger surface area than with flat reamers for both uniconcave and biconcave glenoids (p = 0.013 and p = 0.001). Convex reamers cause more bone loss than flat reamers, but the difference is only significant for uniconcave glenoids (p = 0.007). Conclusions: In biconcave glenoids, convex reamers remove a similar amount of bone as flat reamers, but offer a larger surface area while maximizing the correction of the retroversion. In pathological uniconcave glenoids, convex reamers are preferred because of the conforming shape

Failure characteristics of all polyethylene cemented glenoid implants in total shoulder arthroplasty

Total shoulder arthroplasty (TSA) still suffers today from mid-term and long-term complications such as glenoid implant loosening, wear, humeral head subluxation/dislocation and implant fracture. Unlike the hip and knee joint replacements, the artificial shoulder joint has yet to offer a long-term satisfactory solution to shoulder replacement. With loosening being the number one reason for TSA revision, investigating methods of monitoring the glenoid implant loosening and investigate the effects of various design parameters on the loosening behaviour of the glenoid fixation is necessary to explore the problem. Several studies were carried out using in-vitro cyclic testing and FEA to; investigate failure progression and its correlation to quantitative measures in a 2D study (n = 60), investigating key glenoid design features in a 2D (n = 60) and 3D study (n = 20), investigating the validity of using bone substitute foam for studying glenoid fixation in a cadaveric study and investigating any correlation between failure and CT or in-vitro quantitative measures (n = 10). Visible failure was observed, for the first time, correlating to inferior rim displacement and vertical head displacement measures. CT failure was detected in 70% of specimens before visible failure was observed. Out of the design pairs tested; smooth-back/rough-back (range of roughnesses), peg/keel, curved-back/flat-back and conforming/non-conforming, roughening the back-surface to 3.4 μm or more improved fixation performance (p < 0.05). Roughening the back-surface changed the mode of failure from implant/cement failure inferiorly due to tensile/shear stresses, to cement/bone failure superiorly due to compressive/shear loading. Differences in the other design pairs were marked showing peg to perform better than keel, conforming over non-conforming and no difference in curved-back over flat-back, although these differences are marginal. Improvements in the standard testing method have also been suggested

Posteriorer Zugang zum Schultergelenk

Zusammenfassung : Operationsziel : Schonender Zugang zum posterioren Schultergelenkbereich. Indikationen : Posteriore Schulterstabilisation. Posteriorer Knochenaufbau/-spananlage des Glenoids. Korrekturosteotomie des Glenoids. Versorgung von Skapulahalsfrakturen. Versorgung von posterioren Glenoidrandfrakturen. Versorgung von Akromionfrakturen. Schulterarthrodese. Biopsien. Tumorentfernung. Relativ: Schulterendoprothese mit z.B. gleichzeitigem posterioren Glenoidaufbau. Relativ: Behandlung von Luxationsfrakturen des proximalen Humerus. Kontraindikationen : Allgemeine Kontraindikationen. Operationstechnik : In Seitenlagerung Aufsuchen der Landmarken: Spina scapulae und Akromion. Variabler Hautschnitt je nach zu versorgender Struktur: horizontal, über der Spina scapulae zentriert, bis schräg entlang der Margo lateralis scapulae, bis vertikal über dem Gelenk zentriert. Eigene Präferenz: Winkelhalbierende zwischen Spina scapulae und Margo lateralis scapulae. Von lateral (Subakromialraum) nach medial Ablösen des Musculus deltoideus mit einer kleinen Knochenschuppe von der Spina scapulae. Zum Glenoid: Eingehen zwischen Musculus infraspinatus (Nervus suprascapularis) und Musculus teres minor (Nervus axillaris). Zum Skapulahals (Achtung: Nervus axillaris identifizieren!): Eingehen zwischen Musculus teres minor (Nervus axillaris) und Musculus teres major (Nervus subscapularis) Falls eine Erweiterung des Zugangs erforderlich ist, ansatznahes Durchtrennen der Sehne des Musculus infraspinatus, welcher nach medial gehalten werden kann (cave: Nervus suprascapularis und Arteria circumflexa scapulae!). Weiterbehandlung : Entsprechend der zugrundeliegenden operierten Pathologie. Ergebnisse : Die Ergebnisse nach Operation über einen posterioren Zugang sind vor allem von der behandelten Pathologie abhängig. In der Klinik der Autoren wurden zwischen 1982 und 1995 24 Patienten (26 Schultern) mit posteriorer Instabilität durch einen offenen posteroinferioren Kaspelshift behandelt. Die durchschnittliche Nachuntersuchungszeit betrug 7,6 Jahre. Der alters- und geschlechtsadaptierte Constant- Murley-Score lag bei 91%. Subjektive Patientenbewertung: 24 Schultern gut bis sehr gut, zwei Schultern mäßig. Die Rezidivrate betrug 23% (alle Schultern waren voroperiert, oder es war ein erneutes, adäquates Trauma aufgetreten). Zugangskomplikationen (Schwäche oder Insuffizienz) wurden nicht beobachte

Were early pterosaurs inept terrestrial locomotors?

Pterodactyloid pterosaurs are widely interpreted as terrestrially competent, erect-limbed quadrupeds, but the terrestrial capabilities of non-pterodactyloids are largely thought to have been poor. This is commonly justified by the absence of a non-pterodactyloid footprint record, suggestions that the expansive uropatagia common to early pterosaurs would restrict hindlimb motion in walking or running, and the presence of sprawling forelimbs in some species. Here, these arguments are re-visited and mostly found problematic. Restriction of limb mobility is not a problem faced by extant animals with extensive fight membranes, including species which routinely utilise terrestrial locomotion. The absence of non-pterodactyloid footprints is not necessarily tied to functional or biomechanical constraints. As with other fully terrestrial clades with poor ichnological records, biases in behaviour, preservation, sampling and interpretation likely contribute to the deficit of early pterosaur ichnites. Suggestions that non-pterodactyloids have slender, mechanically weak limbs are demonstrably countered by the proportionally long and robust limbs of many Triassic and Jurassic species. Novel assessments of pterosaur forelimb anatomies conflict with notions that all non-pterodactyloids were obligated to sprawling forelimb postures. Sprawling forelimbs seem appropriate for species with ventrally-restricted glenoid articulations (seemingly occurring in rhamphorhynchines and campylognathoidids). However, some early pterosaurs, such as Dimorphodon macronyx and wukongopterids, have glenoid arthrologies which are not ventrally restricted, and their distal humeri resemble those of pterodactyloids. It seems fully erect forelimb stances were possible in these pterosaurs, and may be probable given proposed correlation between pterodactyloid-like distal humeral morphology and forces incurred through erect forelimb postures. Further indications of terrestrial habits include antungual sesamoids, which occur in the manus and pes anatomy of many early pterosaur species, and only occur elsewhere in terrestrial reptiles, possibly developing through frequent interactions of large claws with firm substrates. It is argued that characteristics possibly associated with terrestriality are deeply nested within Pterosauria and not restricted to Pterodactyloidea as previously thought, and that pterodactyloid-like levels of terrestrial competency may have been possible in at least some early pterosaurs

Use of bone plates and screws to manage chronic mandibular dislocation

Different treatment modalities are described in literature to treat mandibular recurrent dislocation, including intra- capsular esclerosant injections, articular eminence reduction, soft tissues suture to limit condilar movement, and grafts or implants to create mechanical interference, like zygomatic arch down fracture or articular eminence in- crease by bone plates. In this paper, a patient with mandibular recurrent dislocation episodes were eliminated after bilateral fixation of bone plates to the lateral sur-face of the zygomatic arch to restrict mandibular movements. One arm of the plate was extended me-dially just below the articular eminence and fixed at lateral zygomatic arch portion by two screws. The surgical technique is described and 24 months follow-up period is demonstrate with excellent recovery and functional activities. The temporomandibular joint (TMJ) function was unimpeded and no recu-rrence of condilar dislocation was observed. We concluded that this technique is safe and efficient to hinder dislocations of mandible, preserve the TMJ initial characteristics, and prevent abnormal condi-lar movements over the eminenc

Glenoid failure in Total Shoulder Arthroplasty

Compared to hip and knee, anatomic shoulder arthroplasty is relatively poorly understood, underdeveloped and reported loosening rates are very high, the common cause of failure being glenoid aseptic loosening. The aim of this thesis was first to establish in-vitro and in-vivo CT protocols allowing direct monitoring of glenoid fixation and aseptic loosening and secondly to identify key elements of the procedure that could improve results of prosthetic surgery. First, in-vitro, the ASTM standard method for evaluating loosening of glenoid implants was modified, so that, with the use of CT-scans at regular interval basis, it allows the direct monitoring of the failure observed in the laboratory setting. The failure was observed at the cement-implant interface and progressed from the edges of the implants, both superior and inferior, towards the keel. Secondly, an in-vivo CT protocol was established that eliminates most of the metallic artefacts caused by the humeral head and consequently enhances the visualisation of the radiolucent lines and osteolysis around the glenoid. The link between radiological lucencies and aseptic loosening was confirmed first in a study including 68 cases using this CT protocol, which confirmed the progression of the lucencies over time, and secondly, by the use of Spect-CT. The 3-dimensional spatial (mal)position of the glenoid component and the resulting consequences were analysed in three additional studies. The effect of malposition on clinical results and radiological lucencies; the relationship to the preoperative eroded glenoid and the relationship to polyethylene wear were all investigated. These studies stressed how inaccurately the glenoid components are positioned in clinical practise and that this inaccuracy has a detrimental effect on polyethylene wear; aseptic loosening and ultimately on clinical outcome. Future work should focus on establishing the optimal position of the glenoid implant, and how to achieve this optimal placement in surgical practise

Like Father, like son: assessment of the morphological affinities of a.l. 288-1 (a. afarensis), sts 7 (a. africanus) and omo 119-73-2718 (australopithecus sp.) through a three-dimensional shape analysis of the shoulder joint

The postcranial evidence for the Australopithecus genus indicates that australopiths were able bipeds; however, the morphology of the forelimbs and particularly that of the shoulder girdle suggests that they were partially adapted to an arboreal lifestyle. The nature of such arboreal adaptations is still unclear, as are the kind of arboreal behaviors in which australopiths might have engaged. In this study we analyzed the shape of the shoulder joint (proximal humerus and glenoid cavity of the scapula) of three australopith specimens: A.L. 288-1 (A. afarensis), Sts 7 (A. africanus) and Omo 119-73-2718 (Australopithecus sp.) with three-dimensional geometric morphometrics. The morphology of the specimens was compared with that of a wide array of living anthropoid taxa and some additional fossil hominins (the Homo erectus specimen KNM-WT 15000 and the H. neanderthalensis specimen Tabun 1). Our results indicate that A.L. 288-1 shows mosaic traits resembling H. sapiens and Pongo, whereas the Sts 7 shoulder is most similar to the arboreal apes and does not present affinities with H. sapiens. Omo 119-73-2718 exhibits morphological affinities with the more arboreal and partially suspensory New World monkey Lagothrix. The shoulder of the australopith specimens thus shows a combination of primitive and derived traits (humeral globularity, enhancement of internal and external rotation of the joint), related to use of the arm in overhead positions. The genus Homo specimens show overall affinities with H. sapiens at the shoulder, indicating full correspondence of these hominin shoulders with the modern human morphotype