[On the orientation of palmar whorl patterns]. / Ob orientatsii zavitkovykh uzorov ladoni.

The objective of the present work was to study the palmar whorl patterns for the inclusion them in the scope of dermatoglyphic signs along with the arc and loop patterns having a well apparent structural organization. For the first time in the history of domestic dermatoglyphic studies, we described the structure of palmar whorl patterns (based on the palmar prints obtained from 555 subjects) with respect to the surrounding tri-radii. Moreover, the role of their radiants in the formation of node orientation was considered. The analysis of the variants of palmar whorl patterns encountered in the study sample provided a basis for the elaboration of the rule for determining their orientation. Specifically, the orientation of the palmar whorl patterns can be found from the direction of the embracing radiants as in the loop or complex patterns.

Bony palmar ridges of the phalanges of the human fingers.

PURPOSE: On imaging studies, bony ridges can be seen at the palmar aspect of the phalanges of the fingers. Our purpose was to address the following: (1) which structures insert on to the ridges and what is the histological appearance? (2) Is there a difference between the different fingers? (3) Is there a correlation between the ridges and age? MATERIALS AND METHODS: Two observers retrospectively evaluated 270 radiographs (135 men; 135 women; mean age 44 years), and 33 CT scans (22 men; 11 women; mean age 46 years). Three cadaveric hands were also studied. The ridges were graded using a 4-point scale. A Chi-square test was used to compare the different fingers (p < 0.05) and to study the prominence of the ridges in relation to age (p < 0.05). RESULTS: On histology with routine stains the A2 pulley was inserted on the ridges of the proximal phalanx, and the flexor superficialis and A4 pulley on the ridges of the middle phalanx. On histology, the insertion showed a transition zone consisting of fibrocartilage. The prominence of the ridges was significantly different between fingers with III and IV categorized higher than II and III. There was a significant correlation with age for all fingers except for the middle phalanx of II and III. CONCLUSION: The bony palmar ridges have characteristics of enthesophytes. They correspond to the insertion site of the A2 pulley, and the flexor superficialis tendon and A4 pulley, at the proximal and middle phalanx, respectively. The ridges become more prominent with age, and their prominence is different between the fingers with III and IV categorized higher than II and V.

Proximal interphalangeal joint volar plate configuration in the crimp grip position.

PURPOSE: To study the configuration of the proximal interphalangeal joint volar plate (VP) in the crimp grip position (metacarpophalangeal joint at 0° to 45° flexion, proximal interphalangeal joint at 90° to 100° flexion, and distal interphalangeal joint at 0° to 10° hyperextension) using magnetic resonance imaging techniques in healthy volunteers and cadaver fingers and to compare the results with histological sections. METHODS: Magnetic resonance imaging was performed on 24 fingers of 8 healthy volunteers and 12 fingers of 4 embalmed cadaver hands in the neutral position and in the crimp grip position. The translation of the VP body relative to the middle phalanx base during finger flexion was measured. In 6 of 12 cadaver specimens, a load of 10 N was applied to the flexor tendons to examine how this would affect the histological VP fiber configuration. RESULTS: When the flexor tendons were under load in the crimp grip position, the volunteers' VP body was translated an average of 3.2 mm, and the cadaver fingers' VP body was translated an average of 3.0 mm, relative to the middle phalanx base in a distal direction. Histological analysis of the crimp grip position revealed reversing fibers in the VP insertion at the base of the middle phalanx when the flexor tendons were under load and the VP body was translated. When no load was applied in the crimp grip position, no translation of the VP body occurred. CONCLUSIONS: This article describes a VP translation in a distal direction relative to the middle phalanx base in the crimp grip position when the flexor tendons are under load. CLINICAL RELEVANCE: A more precise knowledge of the histological properties of the proximal interphalangeal joint VP during finger flexion can be expected to provide greater diagnostic capabilities and can lead to a better comprehension of injuries.

An anatomical study of the watershed line on the volar, distal aspect of the radius: implications for plate placement and avoidance of tendon ruptures.

PURPOSE: The watershed line is a useful surgical landmark for positioning a volar locking plate. Implants placed on or distal to it can impinge on flexor tendons and cause injury. However, the details of the anatomy of this line are unclear. We studied macroscopically and histologically the structures of the volar aspect of the distal radius. METHODS: We studied 20 distal forearm regions of 10 cadavers (5 males and 5 females; mean age, 79 y [range, 56-88 y]) to clarify the details of the watershed line. In 16 specimens, we investigated the macroscopic appearance of the volar aspect of the radius and the relationships among the bone, the volarradiocarpal ligaments, and the pronator quadratus. Histological analyses were performed in 4 specimens of 2 cadavers to examine the morphology of the margin of the bony structures. RESULTS: In the medial half of the distal volar radius, 2 lines were identified by direct macroscopic visualization; one was the proximal line that corresponded to the distal ridge of the pronator fossa, and the other was the distal line, which was more prominent. A medial bony prominence was situated on the distal line. In the lateral half, the distal and proximal lines of the medial half merged to form a single line. A lateral prominence was situated on this line. CONCLUSIONS: The watershed line might not be a distinct line, and it corresponds to the distal margin of the pronator fossa in the lateral half of the volar radius and to a hypothetical line between the distal and proximal lines in the medial half. The medial and lateral bony prominences on the volar radius should be key structures for accurate plate placement to avoid flexor tendon injury. CLINICAL RELEVANCE: The present study suggests bony landmarks for positioning a volar locking plate.

Biomechanics of the volar plate of the proximal interphalangeal joint: a dynamic ultrasonographic study.

PURPOSE: To study the biomechanics of the volar plate of the proximal interphalangeal (PIP) joint using ultrasonography. METHODS: The subjects were 20 normal and 5 pathological digits. We included as normal subjects 20 digits (10 index and 10 middle fingers) of 10 hands of 10 volunteers who had no history of trauma or any other hand-related pathological conditions. To clarify the biomechanical effect of the A3 pulley for the volar plate motion, we included a total of 5 digits (1 index, 2 middle, and 2 ring) of 4 hands of 4 consecutive patients who had flexor tendon repair surgeries in zone II with the A3 pulley left open as pathological subjects. Transducers were applied volarly to the PIP joint and the ultrasonographic plane was kept in the central axis of the digits to display the volar plate and the flexor tendons in the same image. We recorded cine videos during active joint motion. We also obtained sequential static images for morphological analysis. RESULTS: The motion of the volar plate of the normal PIP joint was as follows: when joint flexion started, the volar plate slid proximally to lie parallel to the condylar slope of the proximal phalanx. In 30° of flexion, the flexor tendons tightened and the distal portion of the volar plate moved volarward. In 45° or more of flexion, the distal portion protruded over the lip of the middle phalanx. The lip rolled dorsalward in the recess in return. In the flexor tendon repair cases, the distal portion of the volar plate did not move volarward at all, even when the joint flexed 45° or more. The main body of the volar plate showed a marked wavelike or sigmoid deformity. CONCLUSIONS: To characterize the biomechanics of the volar plate of the PIP joint, we propose the following 3 sequential phases: sliding, elevating, and rolling in the recess. The A3 pulley may serve as an elevator of the volar plate, triggering the next phase of rolling in the recess. The recess can provide some articulation which the lip of the middle phalanx can roll in.

The Importance of Restoring Anatomy of the Proximal Interphalangeal Joint in Dorsal Fracture Dislocations.

The proximal interphalangeal joint (PIPJ) is a complex anatomical structure. In managing fracture dislocations about the PIPJ, the aim is to restore a congruent joint that allows for smooth gliding motion. Detailed knowledge of the anatomy and biomechanics of the PIPJ is necessary in managing these injuries with predictable success. The breadth of techniques previously described in the treatment of such injuries is testament to the difficulties faced in achieving optimal clinical and radiological outcomes. In this article we detail the anatomy and biomechanics of the PIPJ and summarize current literature and principles for the treatment of dorsal fracture dislocations.

Sex-related differences in carpal arch morphology.

The purpose of this study was to investigate the sex-based differences in the carpal arch morphology. Carpal arch morphology was quantified using palmar bowing and area of the arch formed by the transverse carpal ligament. The carpal arch was imaged at the distal and proximal tunnel levels using ultrasonography in 20 healthy young adults (10 women and 10 men). It was found that females had a smaller carpal arch height compared to men at both distal and proximal levels (p<0.05) and smaller carpal arch width only at the proximal level (p<0.05) but not distally. Palmar bowing index, the carpal arch height to width ratio, was significantly smaller in females at the distal level (p<0.05) but not at the proximal level. Carpal arch cross-sectional area normalized to the wrist cross-sectional area was found to be significantly smaller in females at both tunnel levels compared to men (p<0.05). This study demonstrates that females have a smaller carpal arch compared to men with a reduced palmar bowing distally and a smaller arch area at both tunnel levels. The findings help explain the higher incidence of carpal tunnel syndrome in women as a smaller carpal arch makes the median nerve more vulnerable to compression neuropathy.

Anatomy and Biomechanics of the Finger Proximal Interphalangeal Joint.

A complete understanding of the normal anatomy and biomechanics of the proximal interphalangeal joint is critical when treating pathology of the joint as well as in the design of new reconstructive treatments. The osseous anatomy dictates the principles of motion at the proximal interphalangeal joint. Subsequently, the joint is stabilized throughout its motion by the surrounding proximal collateral ligament, accessory collateral ligament, and volar plate. The goal of this article is to review the normal anatomy and biomechanics of the proximal interphalangeal joint and its associated structures, most importantly the proper collateral ligament, accessory collateral ligament, and volar plate.

The distal radius palmar cortical angle in adolescent versus adult populations.

PURPOSE: Volar distal radius plates are pre-contoured to aid restoration of anatomy during open reduction internal fixation of distal radius fractures. Incorrectly contoured plates can result in malreduction, leading to malunion, pain, and loss of function. The purpose of this study was to investigate whether adolescent distal radius anatomy on the palmar cortical surface differs from that in adults, in order to determine whether adult plates are suitable for use in adolescents. METHODS: Lateral wrist radiographs were used to measure the distal radius palmar cortical angle (PCA) in adolescent age groups (12-13, 14-15, and 16-17 years old) and compared to a skeletally mature control group (30-50 years old). Two assessors measured 423 PCAs twice. RESULTS: There was a statistically significant ( p = <0.05) difference in the PCA of the control group compared to each adolescent group. The mean PCA for both males and females decreased as age increased (increasing curvature of the volar distal radius with age). The mean PCA (male/female) was 164.38°/163.00° in ages 12-13, 162.14°/160.92° in ages 14-15, 157.52°/158.18° in ages 16-17, and 149.65°/154.03° in the control group aged 30-50 years. Agreement between assessors was high with an Interclass correlation coefficient (ICC) of 0.97. CONCLUSION: There is a statistically significant and potentially clinically important difference in the curvature of the distal radius volar cortex between adolescents and adults. This difference persists even in the 16-17 age group. As the PCA curvature is significantly greater in adults compared to adolescents, plates pre-contoured for adults may lead to malreduction of distal radius fractures into flexion in adolescent patients.

Volar morphology of the distal radius in axial planes: a quantitative analysis.

To investigate the cause of rupture of the flexor pollicis longus (FPL) after volar plate fixation of distal radius fractures, previous studies have examined the shape of the distal radius in the sagittal plane or in the lateral view. However, there are no reports on the anatomical shape of the volar surface concavity of the distal radius in the axial plane. We hypothesized that this concavity might contribute to the mismatch between the plate and the surface of the radius. To test this hypothesis, we constructed three-dimensional models of the radius and FPL based on computed tomography scans of 70 normal forearms. We analyzed axial cross-sectional views with 2 mm intervals. In all cases, the volar surface of the distal radius was concave in the axial plane. The concavity depth was maximum at 6 mm proximal to the palmar edge of the lunate fossa and progressively decreased toward the proximal radius. FPL was closest to the radius at 2 mm proximal to the palmar edge of the lunate fossa. The volar surface of the distal radius was externally rotated from proximal to distal. These results may help to develop new implants which fit better to the radius and decrease tendon irritation.

Distal radius measurements and efficacy of fixed-angle locking volar plates.

AIM: For surgical treatment of unstable distal radius fractures, fixed-angled locking volar plate fixation is becoming popular nowadays because of some advantages over other surgical techniques. In this article, we discuss the fitting of fixed-angle locking volar plates to the distal radius in relation to the changes in the distal radial angles. MATERIALS AND METHODS: First, we took conventional radiography images of 18 dried radii and later we measured the palmar subchondral angle, dorsal subchondral angle, mid-subchondral angle, and palmar cortical angle using lateral radiography. RESULTS: According to the measurements, the volar subchondral angles (alpha) ranged from 10.2 degrees to 28.1 degrees, the middle subchondral angles ranged from 55.9 degrees to 93.2 degrees, the dorsal subchondral angles ranged from 77 degrees to 109.6 degrees, and the volar cortical angles ranged from 134.5 degrees to 158.4 degrees. CONCLUSION: Although fixed-angle locking volar plates are accepted as anatomical, our measurements showed that volar cortical angles and the subchondral angles are variable. Therefore, the term "anatomic distal radius volar plate" should be discussed.

Three-dimensional analysis of the palmar plate and collateral ligaments at the proximal interphalangeal joint.

The purpose of this study was to analyze the palmar plate complex at the proximal interphalangeal joint using a three-dimensional (3D) technique, which makes it easier to understand the dimensions of structures and their relationship to the adjacent components. This method allows individual elements to be removed virtually, facilitating clearer observation of each component. Sixteen cadaveric specimens were dissected and reconstructed in a 3D virtual environment. The palmar plate is made up of a distal, fibrous portion and a proximal, membranous portion, which anchors distally on the base of the middle phalanx and is continuous with the bilateral check-rein ligaments proximally. The accessory collateral ligaments and the A3 pulley suspend the palmar plate laterally.

Distal volar radial plates: how anatomical are they?

BACKGROUND: Fractures of the distal radius are common, with volar locking plates being increasingly used in their treatment. They aim to provide stable internal fixation and are designed to mirror the natural anatomy. Current volar plate designs incorporate a volar cortical angle (VCA) of 25 degrees. HYPOTHESIS: The aim of this study is to determine whether the VCA in uninjured distal radii corresponds accurately with modern volar plate designs. MATERIALS AND METHODS: A retrospective radiological analysis utilizing Computed Tomography scans to assess the VCA of 100 distal radii. Each distal radius was subjected to 3 measurements of the VCA in the sagittal plane. RESULTS: One hundred patients were identified (67 male, 33 female; mean age 37.4 years). The mean VCA was 32.9 degrees (S.D.±5.14 degrees). The VCA in male patients was significantly greater than in females (33.6 vs 31.5 degrees; P=0.04). There was a statistically significant difference between the lateral VCA and medial VCA (32.2 vs 34.3 degrees, P=0.02). DISCUSSION: Our study clearly demonstrates that the VCA measured in the distal radius is significantly greater than the volar angulation incorporated within modern plate design. Given that the aim of ORIF is to anatomically reconstruct the distal radius, our study highlights that this may not be possible with current plates. LEVELS OF EVIDENCE: Level IV Retrospective case series.

Presence of multiple tendinous insertions of palmaris longus: a unique variation of a retrogressive muscle.

BACKGROUND: Palmaris longus, being the most variable muscle of the upper extremity is generally considered important morphologically rather than functionally. The palmar aponeurosis represents the distal part of the tendon of Palmaris longus. CASE DETAILS: We report here a unique case of palmaris longus presenting variation distally as its tendon divides to gain multiple attachments with the fascia covering the abductor pollicis brevis, flexor retinaculum and the tendon of flexor carpi ulnaris. In addition, it also continues as palmar aponeurosis as its normal course. CONCLUSION: Presence of this kind of variation might result in compression of the median and ulnar nerves and may aggravate the complications in case of inflammation of palmar aponeurosis thus mimicking the manifestations of Dupuytren's contracture.

The volar anatomy of the distal radius--an MRI study of the FCR approach.

INTRODUCTION: Fractures of the distal radius are one the commonest orthopaedic injuries. Recent advances in implant technology have seen a dramatic rise in the number of fractures treated with volar locked plates, as they permit accurate peri-articular reconstruction. The surgical approach along the bed of flexor carpii radialis (FCR) tendon encounters a number of key soft tissue and neurovascular structures during the dissection to the fracture plane. The aim of this study was to describe the exact position of such structures involved (and hence at risk) during the FCR approach. METHODS: 100 adult MRI scans were reviewed. The relationships between the brachioradialis tendon (BR), flexor carpi radialis (FCR) tendon, flexor pollicis longus (FPL) tendon, median nerve (MN) and radial artery (RA) were measured. RESULTS: The male to female ratio was 35:65. Average age was 39. FCR tendon was 7.4 mm (SD 1.46) from the RA and 7.01 mm (SD 2.37) from the MN. The distance between BR and RA was significantly different between male and female (5.06 mm vs. 4.1 mm, p=0.034). CONCLUSION: This study highlights the precise nature of the surgical anatomy involved in dissection to the fracture site. Vigilance is needed during the initial steps of the FCR-bed approach to avoid damage to the radial artery and median nerve which lie in close proximity. If the approach is extended to include a brachioradialis tenotomy, we suggest this should be made under direct vision, given its relationship with the radial artery.

Various circular arc radii of the distal volar radius and the implications on volar plate osteosynthesis.

The purpose of this anatomical study was to explore the different circular arc radii of the distal volar radius and provide more detailed anatomic information that will further the understanding of volar plate osteosynthesis. The profiles of the volar distal radii of 100 cadaver specimens were measured with a common profile gauge. Profiles were copied onto paper and then matched to a best-fit circular arc template to determine the radius of curvature on the radial and ulnar sides of the distal volar radius. The mean circular arc radius of the distal volar surface was 2.6 cm (+/-1 cm, 1-6 cm) on the radial side and 2.3 cm (+/-1 cm, 1-6 cm) on the ulnar side. A significant difference (P<.01) was noted in the radii of curvature of the distal radius in 55% of the study population. In 37% of these cases, the circular arc radius flattens toward the ulnar side. In 63%, it flattens toward the radial side. This characteristic may lead to a false rotation position of the distal fracture fragment following volar plate osteosynthesis. In addition, suboptimal or incorrect plate position may result due to the discrepancy between the plate radius of curvature and the radius of curvature of either the radial or ulnar volar radius.

Bone density spatial patterns in the distal radius reflect habitual hand postures adopted by quadrupedal primates.

Primates adopt diverse hand postures during terrestrial and above-branch quadrupedal locomotion--knuckle-walking, digitigrady, and palmigrady--that incorporate varying degrees of wrist dorsiflexion (i.e., extension). Although relationships between hand postures, wrist joint range of motion, and the external properties of wrist bones (e.g., surface morphology) have been examined, the relationship between hand postures and the internal properties of wrist bones (e.g., bone density) remains largely unexplored. Because articular joint surfaces transmit mechanical loads between conjoining limb bones, measures of density (e.g., magnitudes and patterns) in the subchondral cortical plate of bone of the distal radius can be used to evaluate load regimes experienced by the wrist joint in different hand postures. We assessed apparent (i.e. optical) density patterns in several extant catarrhine primate taxa partitioned into different hand posture groups: knuckle-walking apes, digitigrade monkeys, and palmigrade monkeys. Computed tomography osteoabsorptiometry (CT-OAM) was used to construct maximum intensity projection (MIP) maps of apparent densities. High apparent density areas were characterized relative to a dorsal-volar reference plane and compared across hand posture groups. All groups had large percentage areas of high apparent density in the dorsal region of the distal radial articular surface. Only knuckle-walking apes, however, had a large percentage area of high apparent density in the volar region of the distal radial articular surface. These patterns are consistent with radiocarpal articulations in specific hand postures as evidenced by available radiographic data and suggest that the different habitual hand postures adopted by monkeys and African apes during quadrupedal locomotion have different stereotypic loading patterns. This has implications for understanding the functional morphology and evolution of knuckle-walking and digitigrade hand postures in primates.