The Vascular Anatomy of the Scaphoid: New Discoveries Using Micro-Computed Tomography Imaging.

PURPOSE: The purpose of this study was to investigate the intraosseous vascular anatomy of the scaphoid using recent advances in micro-computed tomography (micro-CT) imaging and 3-dimensional reconstruction. We also studied the effect of scaphoid shape and screw position on the intraosseous vascular structure. METHODS: Thirteen upper extremities were injected with a contrast agent. The scaphoid bones were extracted and scanned using a micro-CT scanner. The vascular impact of screw insertion at various axes through the scaphoid was calculated and compared using the generated 3-dimensional models. The specimens were 3-dimensionally-printed and the morphology was assessed according to bone dimensions. A relationship between the internal vascular patterns and these morphological features was determined. RESULTS: All specimens received vascular inflow from the dorsal ridge forming a vascular network that supplied an average of 83% of the bone's volume. This network was supplemented in 4 specimens with volar vessels entering at the waist. Another network was identified, created by vessels entering volarly at the tubercle, which supplied the remainder of the scaphoid. One specimen did not receive any vessels at the tubercle. With regards to screw placement, screws placed in the central axis were the least disruptive to the internal vascularity, followed by the antegrade (dorsal) insertion axis. Two morphological bone types were identified: type I or full scaphoids and type II or slender scaphoids. Type I possessed a more robust internal vascular network than type II scaphoids. CONCLUSIONS: This study identifies 2 distinct types of scaphoid morphology with 1 of them having a less robust blood supply, which may prove to be related to development of nonunion, avascular necrosis, or Preiser disease. Central axis and antegrade (dorsal) screw fixation may be least disruptive to the internal blood supply. CLINICAL RELEVANCE: Safer fixation of the scaphoid bone may be achieved by knowledge of intraosseous vascular patterns.

An Anthropometric Assessment of the Proximal Hamate Autograft for Scaphoid Proximal Pole Reconstruction.

PURPOSE: Fragmentation of the scaphoid proximal pole secondary to avascular necrosis presents a difficult reconstructive problem. This anthropometric study assesses the utility of the ipsilateral proximal hamate for complete osteochondral scaphoid proximal pole reconstruction. METHODS: Twenty-nine cadaveric specimens underwent computed tomography scanning and 3-dimensional reconstruction of the carpus and distal radius. Scaphoid height was measured and a third of its height was used to simulate resection of the proximal scaphoid pole and extent of hamate autograft required. The proximal scaphoid and hamate were divided into 6 sections, and compared using an iterative point-to-point distance algorithm. Average distance between the scaphoid and the hamate surfaces was determined. An interbone algorithm was used to assess radioscaphoid joint congruency and articular contact surface of the native scaphoid compared with the scaphoid reconstructed with hamate autograft. RESULTS: The mean height of scaphoid proximal pole excision and proximal hamate autograft height was 9.3 mm. Comparing the morphology of the native scaphoid and hamate autografts, the absolute distances were the largest in the volar radioscaphoid, dorsal radioscaphoid, and dorsal scaphocapitate segments. Without osteotomy, the hamate autograft may cause impaction in the dorsal-radial aspect of the distal radius. The hamate autograft also shifted the articular contact point of the radioscaphoid joint toward the dorsal-radial position. Nine hamate autografts were classified as poor-fitting. Poor-fitting specimens had a greater radial styloid to distal radioulnar joint distance. These specimens also had wider hamates and scaphoids in the radial-ulnar dimension and wider scaphoids in the volar-dorsal dimension. Lunate type did not correspond to anthropometric fit. CONCLUSIONS: The proximal hamate osteochondral graft was poor fitting in 31% of cases (9 of 29 specimens). Wrists with radial-ulnar hamate width less than 10 mm, radial-ulnar scaphoid width less than 10 mm, and volar-dorsal scaphoid width less than 16 mm demonstrate better anthropometric fit. CLINICAL RELEVANCE: This study provides an anthropometric assessment of the recently described proximal hamate autograft, a new bone graft option for proximal scaphoid pole reconstruction.

[Anatomy and pathobiomechanics of the scaphoid]. / Anatomie und Pathobiomechanik des Skaphoids.

Among the carpal bones the scaphoid (Os scaphoideum) is the most important. The most frequent fracture of the carpus is a fracture of the scaphoid bone. The frequently occurring absence of healing of these fractures as well as unhealed ruptures of the ligament complex between the scaphoid and lunate, lead to the most severe biomechanical and thus the most severe clinical changes of the wrist. The detailed anatomy of the scaphoid, blood flow, ligament attachments, injury mechanisms and pathobiomechanics are described and illustrated.

Kinematics of the anthropoid os centrale and the functional consequences of scaphoid-centrale fusion in African apes and hominins.

In most primates, the os centrale is interposed between the scaphoid, trapezoid, trapezium, and head of the capitate, thus constituting a component of the wrist's midcarpal complex. Scaphoid-centrale fusion is among the clearest morphological synapomorphies of African apes and hominins. Although it might facilitate knuckle-walking by increasing the rigidity and stability of the radial side of the wrist, the exact functional significance of scaphoid-centrale fusion is unclear. If fusion acts to produce a more rigid radial wrist that stabilizes the hand and limits shearing stresses, then in taxa with a free centrale, it should anchor ligaments that check extension and radial deviation, but exhibit motion independent of the scaphoid. Moreover, because the centrale sits between the scaphoid and capitate (a major stabilizing articulation), scaphoid-centrale mobility should correlate with scaphocapitate mobility in extension and radial deviation. To test these hypotheses, the centrale's ligamentous binding was investigated via dissection in Pongo and Papio, and the kinematics of the centrale were quantified in a cadaveric sample of anthropoids (Pongo sp., Ateles geoffroyi, Colobus guereza, Macaca mulatta, and Papio anubis) using a computed-tomography-based method to track wrist-bone motion. Results indicate that the centrale rotates freely relative to the scaphoid in all taxa. However, centrale mobility is only correlated with scaphocapitate mobility during extension in Pongo-possibly due to differences in overall wrist configuration between apes and monkeys. If an extant ape-like wrist characterized early ancestors of African apes and hominins, then scaphoid-centrale fusion would have increased midcarpal rigidity in extension relative to the primitive condition. Although biomechanically consistent with a knuckle-walking hominin ancestor, this assumes that the trait evolved specifically for that biological role, which must be squared with contradictory interpretations of extant and fossil hominoid morphology. Regardless of its original adaptive significance, scaphoid-centrale fusion likely presented a constraint on early hominin midcarpal mobility.

Estimating Scaphoid Lengths Using Anatomical Measurements in the Wrist.

PURPOSE: In reconstructive surgery of scaphoid nonunions with humpback deformity, some surgeons recommend restoration of the normal scaphoid length whereas others overexpand the normal length to ensure carpal realignment and prevent late collapse. To be able to define overexpansion and investigate which levels of overexpansion yield optimal clinical results, a precise method for estimating the original scaphoid length is required. The purpose of this anatomic study was to investigate the precision of estimating normal scaphoid lengths based on intact adjacent bone dimensions, compared with using the contralateral scaphoid length. METHODS: From bilateral computed tomographic scans of 28 healthy wrist pairs, 3-dimensional virtual bone models were created. The left and right scaphoid lengths were determined at the central axis. The capitate length at the central axis and the distal radius width served to derive an ipsilateral scaphoid length estimate. Estimation precision for individual cases was based on the 95% range (±1.96 × SD) of the observed differences between the actual and estimated lengths. RESULTS: On average, the capitate length was 10% smaller than the scaphoid length; the radius width was 9% larger. Consequently, we averaged the capitate length and radius width for ipsilateral estimations. The average difference between the scaphoid length and the latter ipsilateral estimate was 0.1 mm. The average contralateral scaphoid length difference was also 0.1 mm. Estimation precisions, however, were ±2.2 and ±1.4 mm, respectively. CONCLUSIONS: Scaphoid length estimation based on the contralateral scaphoid is more precise than the estimating scaphoid length using the ipsilateral radius and capitate. CLINICAL RELEVANCE: Scaphoid overexpansion can be ensured if the restored length is at least 1.4 mm longer than the contralateral length. This may be valuable information when establishing a target length for reconstruction and investigating the consequences of scaphoid overexpansion on clinical function, such as range of motion, which are currently unknown.

Scaphoid tuberosity excursion is minimized during a dart-throwing motion: A biomechanical study.

PURPOSE: The purpose of this study was to determine whether the excursion of the scaphoid tuberosity and therefore scaphoid motion is minimized during a dart-throwing motion. METHODS: Scaphoid tuberosity excursion was studied as an indicator of scaphoid motion in 29 cadaver wrists as they were moved through wrist flexion-extension, radioulnar deviation, and a dart-throwing motion. RESULTS: Study results demonstrate that excursion was significantly less during the dart-throwing motion than during either wrist flexion-extension or radioulnar deviation. CONCLUSION: If the goal of early wrist motion after carpal ligament or distal radius injury and reconstruction is to minimize loading of the healing structures, a wrist motion in which scaphoid motion is minimal should reduce length changes in associated ligamentous structures. Therefore, during rehabilitation, if a patient uses a dart-throwing motion that minimizes his or her scaphoid tuberosity excursion, there should be minimal changes in ligament loading while still allowing wrist motion. STUDY DESIGN: Bench research, biomechanics, and cross-sectional. LEVEL OF EVIDENCE: Not applicable. The study was laboratory based.

[Anatomy and biomechanics of the scaphoid]. / Anatomie und Biomechanik des Kahnbeins.

The scaphoid is biomechanically and clinically of great importance for function of the wrist. In the literature, its anatomy and biomechanics are clearly underrepresented as well as underestimated. In the following review the scaphoid will be presented in more detail, according to recent information and findings. Not only will the origin of the name and the history of previous names, such as cotyloid or navicular, be introduced, but also for the first time in medical literature the significant phylogeny and ontogeny of the scaphoid will be shown. Moreover, the clinically very important blood supply, the ligaments of the scaphoid and relevant biomechanical details will be described.

The Palpable Scaphoid Surface Area in Various Wrist Positions.

PURPOSE: To determine the theoretical amount of surface area available for palpation of the scaphoid in various wrist positions and to provide a guide depicting which wrist position will expose proximal pole, waist, and distal pole fractures. METHODS: Using 3 fresh-frozen male cadaver wrists, we digitized palpable surface areas (dorsal, volar, and snuffbox) of the scaphoid in several wrist positions. The entire scaphoid was then excised and a digitized 3-dimensional reconstruction of the entire scaphoid was obtained. The 2 images were superimposed and the surface area was calculated RESULTS: The maximum palpable area of the scaphoid was achieved with the wrist in neutral extension and maximum ulnar deviation and the wrist in maximum flexion and neutral deviation. Neutral wrist extension and ulnar deviation exposed all but the most proximal portion of the proximal pole and the distal pole, which made this the ideal position to detect tenderness from a scaphoid waist fracture and larger proximal pole fractures. Maximum wrist flexion with neutral wrist deviation exposed the entire proximal pole, which made this the ideal position to detect tenderness from a proximal pole scaphoid fracture. CONCLUSIONS: Wrist position influences the amount of scaphoid surface area available for palpation and should be considered when examining a patient with a suspected scaphoid fracture. CLINICAL RELEVANCE: The scaphoid should be palpated in 3 anatomic regions with the wrist placed in different positions to maximally expose the anatomical region being palpated.

Anthropometry of the Human Scaphoid Waist by Three-Dimensional Computed Tomography.

Published measurements for the scaphoid are scarce. The purpose of this study is to define anthropometric norms for the waist of the scaphoid to assist in optimizing bone graft quantity and implant use. Computed tomography images of the wrist were reviewed by three surgeons. Anthropometric data were gathered, including the scaphoid waist diameter in two dimensions and the scaphoid waist volume. Each study was measured twice, allowing for determination of inter- and intraobserver reliability. Forty-three studies were examined (23 female and 20 male). Average measurements of the scaphoid waist were 11.28 ± 0.26 mm in the sagittal plane and 8.70 ± 0.17 mm in the coronal plane, and the waist volume was 715 ± 33.0 mm3. Specific measures of the narrowest portion of the scaphoid are provided by this study. Measurements of the scaphoid waist through the use of three-dimensional imaging are an accurate method with good inter- and intraobserver reliability. The measurements obtained from this study can be applied to guide graft and implant selection for treatment of scaphoid waist fractures and nonunions.

Intraosseous rotation of the scaphoid: assessment by using a 3D CT model--an anatomic study.

OBJECTIVES: The purpose of this study was to assess intraosseous rotation as the third dimension of scaphoid anatomy on a 3D CT model using common volume rendering software to impact anatomical reconstruction of scaphoid fractures. METHODS: CT images of 13 cadaver wrist pairs were acquired. Reference axes for the alignment of distal and proximal scaphoid poles were defined three-dimensionally. Two methods for rotation measurement-the reference axis method (RAM) and the scapho-trapezio-trapezoidal joint method (STTM)-were developed and compared by three independent observers. RESULTS: Rotation measured by the RAM averaged 66.9° ± 7 for the right and 67.2° ± 5.8 for the left wrists. Using the STTM there was a mean rotation of 68.6° ± 6.6 for the right and 68.6° ± 6.8 for the left wrists. The overall results showed a significant variability of the measured values between different specimens (P < 0.05). There was no significant difference between left and right wrists of the same specimen, neither for the RAM (P = 0.268) nor for the STTM (P = 0.774). Repeatability coefficients between the observers were low, indicating good repeatability. CONCLUSIONS: The presented methods are practical tools to quantify intraosseous rotation between distal and proximal scaphoid poles using common volume rendering software. For clinical application the opposite side provides the best reference values to assess malrotation in scaphoid fracture cases. KEY POINTS: Scaphoid intraosseous rotation can be measured using common volume rendering software. The opposite uninjured side provides good reference values for rotation measurement. Assessment of malrotation may impact anatomical reconstruction of scaphoid fractures.

New concept of scapholunate dissociation treatment and novel modification of Brunelli procedure - anatomical study.

BACKGROUNDS: This paper describes a novel method in treatment of scapholunate dissociation accompanied with rotatory subluxation of the scaphoid. The idea of this method is to create a kind of axial lever that can fully reconstruct anatomical relationship between the scaphoid and the lunate, with no involvement of extrinsic ligaments, and with simultaneous restriction of pathological alignment of the scaphoid. Based on this technique, we have also proposed a new modification of Brunelli procedure in scapholunate dissociation with rotatory subluxation of the scaphoid and dorsal intercalated segmental instability. METHODS: At the initial stage of the study, 20 human wrists fixed in Ethanol were used, followed by 12 fresh human wrists used in part two. The first stage included functional, biomechanical and strength tests carried out by means of a 5 kg load and intended to find the most anatomical and durable treatment method. The second stage involved testing the proposed methods on fresh cadaver wrists. RESULTS: We have discovered that the new method is able to recreate anatomical forces and properties of scapholunate ligament; what's more, it can also prevent rotatory subluxation of the scaphoid. The performed strength tests have proven that it is possible to treat scapholunate instability also in case of dorsal intercalated segmental instability. CONCLUSIONS: We highly recommend using both the new technique and the new modification of Brunelli procedure for treatment of scapholunate dissociation in both dynamic and static instabilities.

Influence of screw design, sex, and approach in scaphoid fracture fixation.

BACKGROUND: Screw fixation of scaphoid fractures has gained popularity. A long central screw has been shown to be biomechanically advantageous. QUESTIONS/PURPOSES: We compared the ability of different screw designs to obtain this goal and determined the influence of sex and approach on screw length. METHODS: We performed all measurements on three-dimensional reconstructions of 20 CT scans of normal scaphoids (10 men and 10 women) with the use of software. The three-dimensional computer models were analyzed, the central axis was defined, and the screws were placed along this axis. We compared 15 different available screw designs and volar and dorsal screw placement. RESULTS: The length of the scaphoid along its central axis was longer in men (mean, 27.14 mm; standard error of the mean, 0.97 mm) than in women (mean, 23.86 mm; standard error of the mean, 0.37 mm). The screw length that can be used was longer in the volar approach (mean, 23.72 mm; standard error of the mean, 0.19 mm) than in the dorsal approach (mean, 23.31 mm; standard error of the mean, 0.19 mm) regardless of the screw design. Screws with a trailing thread diameter greater than 3.9 mm and leading thread diameter greater than 3.0 mm were shorter. CONCLUSIONS: Scaphoids in women are smaller than in men. Theoretically, fixation of scaphoid fractures through a volar approach will allow the surgeon to use longer screws. The screw design has a significant influence on the screw length that can be used in scaphoid fracture fixation. We recommend using a differential pitch screw with a thread diameter of 3.9 mm or less.

The anterolateral corner of the radial metaphysis as a source of bone graft for the treatment of scaphoid nonunion.

As a source of corticocancellous grafts for treating scaphoid nonunions, the anterolateral corner of the distal radial metaphysis has several advantages over other alternatives: it provides good-quality corticocancellous bone, it allows one to harvest the graft and treat the scaphoid through the same incision, it does not require general anesthesia, and it has less morbidity than occurs when obtaining the graft from the iliac crest.

Scapholunate instability: current concepts in diagnosis and management.

Injuries to the scapholunate joint are the most frequent cause of carpal instability and account for a considerable degree of wrist dysfunction, lost time from work, and interference with activities. Although it is insufficient to cause abnormal carpal posture or collapse on static radiographs, an isolated injury to the scapholunate interosseous ligament may be the harbinger of a relentless progression to abnormal joint mechanics, cartilage wear, and degenerative changes. Intervention for scapholunate instability is aimed at arresting the degenerative process by restoring ligament continuity and normalizing carpal kinematics. In this review, we discuss the anatomy, kinematics, and biomechanical properties of the scapholunate articulation and provide a foundation for understanding the spectrum of scapholunate ligament instability. We propose an algorithm for treatment based on the stage of injury and the degree of secondary ligamentous damage and arthritic change.

Elongation of the dorsal carpal ligaments: a computational study of in vivo carpal kinematics.

PURPOSE: The dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments play an important role in scapholunate and lunotriquetral stability. The purpose of this study was to compute changes in ligament elongation as a function of wrist position for the DRC and the scaphoid and trapezoidal insertions of the DIC. METHODS: We developed a computational model that incorporated a digital dataset of ligament origin and insertions, bone surface models, and in vivo 3-dimensional kinematics (n = 28 wrists), as well as an algorithm for computing ligament fiber path. RESULTS: The differences between the maximum length and minimum length of the DRC, DIC scaphoid component, and DIC trapezoidal component over the entire range of motion were 5.1 ± 1.5 mm, 2.7 ± 1.5 mm, and 5.9 ± 2.5 mm, respectively. The DRC elongated as the wrist moved from ulnar extension to radial flexion, and the DIC elongated as the wrist moved from radial deviation to ulnar deviation. CONCLUSIONS: The DRC and DIC lengthened in opposing directions during wrist ulnar and radial deviation. Despite complex carpal bone anatomy and kinematics, computed fiber elongations were found to vary linearly with wrist position. Errors between computed values and model predictions were less than 2.0 mm across all subjects and positions. CLINICAL RELEVANCE: The relationships between ligament elongation and wrist position should further our understanding of ligament function, provide insight into the potential effects of dorsal wrist incisions on specific wrist ranges of motion, and serve as a basis for modeling of the wrist.

Osseous microarchitecture of the scaphoid: Cadaveric study of regional variations and clinical implications.

Bone strength and structure are closely associated with fracture and screw fixation, however osseous micro architecture on scaphoid has not been clearly addressed. We conducted histomorphometric study of the scaphoid using micro CT to find regional variations and differences in the scaphoid to provide better understanding of fracture mechanism and suggest optimal screw position. We divided scaphoid into eight regions and collected regional data from eleven different cadaveric scaphoids. A computer program was used to measure parameters, which includes mean subchondral bone thickness, bone mineral density for bone density parameters, and tissue mineral density, trabecular thickness, trabecular spacing, trabecular number and bone volume fraction for bone quality parameters. All bone strength parameters were measured the maximum value in the regions where scaphoid articulates with radius. Articular regions presented higher bone strength parameters and thicker subchondral bone. The minimum value of trabecular number was in midcarpal side of waist portion. There was trend of higher subchondral bone thickness in the scaphoid which articulates with capitate and radius. This histomorphometric study showed regional variation of the scaphoid in terms of bone density and quality parameters. Waist portion presented thick subchondral and trabecular bone for high cross section moment of inertia against bending. Three point bending for scaphoid fracture and vertical screw placement are suggested based on these variations.

Osseous and ligamentous scaphoid anatomy: Part I. A systematic literature review highlighting controversies.

PURPOSE: The interpretation of scaphoid anatomy and kinematics is confusing and controversial. This results from a lack of consensus on the anatomy of the ligaments attaching to the scaphoid and an overwhelming variety of substantially different anatomic descriptions and classification systems of the wrist joint in the literature. The present study systemically reviews the consistencies or inconsistencies of the various scaphoid ligament descriptions and aims to clarify and unify different concepts and classification systems. METHODS: We performed a systematic search of the medical literature from 1950 to 2010. We included all descriptive reports of the anatomy or morphology of the scaphoid, ligaments, or both. With the aim to describe the best available evidence, we considered all anatomical descriptions but emphasized a selection of the most frequently cited articles. RESULTS: The literature search resulted in 555 potentially eligible descriptive reports, 58 of which met the inclusion criteria and were included in the review. Variations in the anatomic descriptions appear to be mostly due to the difficulty of identifying individual interdigitating ligaments or bundles by macroscopic dissections, as well as the interindividual variability in ligament anatomy. The most important areas of controversy in the scaphoid ligament attachments include the radial collateral ligament, dorsal radiocarpal ligament, dorsal intercarpal ligament, volar scaphotriquetral ligament, and scaphotrapezium-trapezoid ligament. CONCLUSIONS: None of the scaphoid ligaments other than the scaphocapitate ligament have been described consistently. Future research is required to verify the ligament attachments that currently have the most controversial descriptions, while addressing the interindividual variability of ligament insertions and morphology. CLINICAL RELEVANCE: Thorough knowledge of the anatomy will enhance our understanding of the kinematics of the scaphoid.

Scaphoid and lunate translation in the intact wrist and following ligament resection: a cadaver study.

PURPOSE: To determine the amount of scaphoid and lunate translation that occurs in normal cadaver wrists during wrist motion, and to quantify the change in ulnar translation when specific dorsal and volar wrist ligaments were sectioned. METHODS: We measured the scaphoid and lunate motion of 37 cadaver wrists during wrist radioulnar deviation and flexion-extension motions using a wrist joint motion simulator. We quantified the location of the centroids of the bones during each motion in the intact wrists and after sectioning either 2 dorsal ligaments along with the scapholunate interosseous ligament or 2 volar ligaments and the scapholunate interosseous ligament. RESULTS: In the intact wrist, the scaphoid and lunate statistically translated radially with wrist ulnar deviation. With wrist flexion, the scaphoid moved volarly and the lunate dorsally. After sectioning either the dorsal or volar ligaments, the scaphoid moved radially. After sectioning the dorsal or volar ligaments, the lunate statistically moved ulnarly and volarly. CONCLUSIONS: Measurable changes in the scaphoid and lunate translation occur with wrist motion and change with ligament sectioning. However, for the ligaments that were sectioned, these changes are small and an attempt to clinically measure these translations of the scaphoid and lunate radiographically may be limited. The results support the conclusion that ulnar translocation does not occur unless multiple ligaments are sectioned. Injury of more than the scapholunate interosseous ligament along with either the dorsal intercarpal and dorsal radiocarpal or the radioscaphocapitate and scaphotrapezial ligaments is needed to have large amounts of volar and ulnar translation.

Osseous and ligamentous scaphoid anatomy: Part II. Evaluation of ligament morphology using three-dimensional anatomical imaging.

PURPOSE: There are many controversies in the literature regarding the morphology of the scaphoid ligaments. The aim of this study was to provide a more accurate description by quantitatively describing the 3-dimensional, geometrical aspects of the scaphoid ligaments and their attachments, using cryomicrotome images of cadaveric wrists. METHODS: Eight fresh-frozen human cadaver wrists were examined with computed tomography (CT) and an imaging cryomicrotome. A series of 2-dimensional cryoimages created a 3-dimensional anatomical data set of each test specimen. Detection of ligaments and their surface areas was performed by manually marking the course and attachment points for each ligament, using dedicated visualization software. The 3-dimensional bone surfaces were segmented from the acquired CT images and incorporated in the 3-dimensional anatomical data set of the same anatomical specimen to facilitate the detection procedure. The results of the morphological parameters and attachment areas of the scaphoid ligaments are described 3-dimensionally. RESULTS: The mean size of the whole scaphoid surface was 1503 ± 17 mm(2), and the mean size of all ligament attachments on the scaphoid was 131 ± 14 mm(2); thus, ligament attachments consist of 9% ± 0.9% of the total scaphoid surface area. Based on the data, a 3-dimensional representation of the wrist was created to present the scaphoid ligament attachment areas and paths. The dorsal intercarpal ligament had the most individual variability between specimens in attachments. CONCLUSIONS: The quantitative results were almost completely consistent with the findings of previous reports. The only inconsistency in ligament morphology regarded the scaphocapitate ligament, which in this study was found to be the thickest ligament attached to the scaphoid. CLINICAL RELEVANCE: The results of this study improve our knowledge of scaphoid ligament anatomy, as they corroborate previous findings. This is important for carpal surgery and will pave the way to a better understanding of the biomechanics involved in destabilization of wrist fractures.

Scaphotrapezial ligament: normal arthro-CT and arthro-MRI appearance with anatomical and clinical correlation.

The purpose of our study was to demonstrate and describe the MR and arthro-CT anatomic appearance of the scaphotrapezial ligament and illustrate some of the pathologies involving this structure. This ligament consists of two slips that originate from the radiopalmar aspect of the scaphoid tuberosity and extend distally, forming a V shape. The ulnar fibers, which are just radial to the flexor carpi radialis sheath, inserted along the trapezial ridge. The radial fibers were found to be thinner and inserted at the radial aspect of the trapezium. Twelve fresh cadaver wrists were dissected, with close attention paid to the scaphotrapezio-trapezoidal (STT) joint. An osseoligamentous specimen was dissected with removal of all musculotendinous structures around the STT joint and was performed with high-resolution acquisition in a 128-MDCT scanner. Samples of the wrist area were collected from two fetal specimens. A retrospective study of 55 patients with wrist pain that were submitted to arthrography, arthro-CT, and arthro-MRI imaging was performed (10 patients on a 3-T superconducting magnet and 45 patients on a 1.5-T system). Another ten patients had high-resolution images on a 3-T superconducting magnet without arthrographic injection. MR arthrography and arthro-CT improved visualization and provided detailed information about the anatomy of the scaphotrapezial ligament. Knowledge of the appearance of this normal ligament on MRI allows accurate diagnosis of lesions and will aid when surgery is indicated or may have a role in avoiding unnecessary immobilization.