The sensitivity of carpal bone indices to rotational malpositioning

The Sensitivity of the Scapholunate Interval and Bony Landmarks to Wrist Rotation on Posteroanterior Radiographs

BACKGROUND

The objective of this study was to examine the effect of wrist rotation on the scapholunate interval in the posteroanterior radiograph and to identify radiographic landmarks on the posteroanterior projection that can be used to assess position.

METHODS

Eleven healthy cadaveric wrists were radiographed in the neutral position and subsequently were rotated and imaged from 30° pronation to 30° supination in 10° intervals. At each interval, the scapholunate interval was measured as well as the following landmarks: (1) the visible perimeter of the base of the hook of the hamate; (2) the radial-ulnar distribution of the dorsal nonarticular surface of the distal third metacarpal head; (3) the radial-ulnar distribution of the pisiform about the longitudinal axis of the ulna; and (4) the overlap of the pisiform and triquetrum.

RESULTS

The scapholunate interval was largest in the neutral position and linearly decreased by 34% for every 10° of pronation and decreased nonlinearly by 86% after the first 10° of supination. The appearance of the distal third metacarpal head was shown to be sensitive to both pronation and supination. The perimeter of the hook of the hamate and the distribution of the pisiform compared to the ulna were both shown to be sensitive to supination, whereas overlap of the pisiform and triquetrum was not shown to be sensitive to either direction of rotation.

CONCLUSIONS

Our results highlight the significant effect of rotation on radiographic landmarks at the wrist, indicating that 10° of supination can drastically alter the developed radiograph.

Comparison of computer-aided and manual measurements in the evaluation of carpal alignment

The purpose of this study was to compare computer-aided analysis and different methods of manual measurements in the evaluation of carpal alignment. The radioscaphoid, radiolunate, radiocapitate and radiometacarpal angles were measured on cone-beam computed tomography (CT) scans of 30 healthy wrists by automated software (Disior Ltd.) and by hand surgeons using lateral radiographs reconstructed from the CT data. Hand surgeons were either given (n = 6) or not given (n = 7) prior instructions on how to perform the measurements. Inter- and intra-observer reliability of manual measurements ranged from good to excellent (intra-class correlation coefficients [ICC] 0.77-0.99), being highest in specialists with standardized methods and in reconstructed radiographs with bone overlap digitally removed. Computer-aided software provided excellent intra-observer reliability (ICC 0.94-1.00) consistently and values that were highly comparable (mean difference range 1°-7°) with the manual measurements made in optimal settings. Computer-aided software provides an accurate and repeatable method to measure carpal alignment in CT scans, minimizing observational errors.

Three-dimensional carpal alignment: computer-aided CT analysis of carpal axes and normal ranges

Assessment of carpal alignment traditionally uses carpal bone axes measured on lateral radiographs. In this study, three-dimensional axes were defined for carpal bones using segmentation and numerical modelling of CT data of 121 neutrally positioned, asymptomatic wrists. The geometric axis was used for radius, scaphoid and capitate, whereas the axis based on a line perpendicular to the articular surface was used for the other carpal bones. Normal values of radiocarpal angles in the radial coordinate and the reliability of the computer-aided analysis are reported. The mean sagittal radiocarpal angles (positive in palmar direction) were as follows: scaphoid 58° (SD 10°), lunate 0° (SD 11°), triquetrum 12° (SD 8°), trapezium 17° (SD 8°), trapezoid -10° (SD 7°), capitate -17° (SD 9°) and hamate 2° (SD 7°). The mean coronal radiocarpal angles (positive in ulnar direction) were -42° (SD 9°), -20° (SD 4°), -49° (SD 4°), -32° (SD 6°), -16° (SD 5°), 2° (SD 7°) and 8° (SD 6°), respectively. The intra-observer reliability of the measurements was excellent (mean intraclass correlations coefficient 0.98). This study provides guidelines on how to measure and quantify carpal alignment three-dimensionally, and a database for the normal values. Together, these may be useful when analysing various wrist pathologies and kinematics of the wrist.

Intercarpal Angles on Hand Versus Wrist Films: Are Hand Radiographs Sufficient for Assessing Intercarpal Angles?

PURPOSE

Carpal angles traditionally are measured on the lateral projection of a standard wrist series; however, this often necessitates obtaining additional radiographic views resulting in additional radiation exposure and increased cost. We aimed to determine whether carpal angles could be measured accurately on a standard series of hand radiographs when compared to wrist radiographs.

METHODS

Carpal indices were measured on lateral wrist and hand radiographs of 40 patients by three orthopedic upper extremity surgeons. Inclusion criteria were no metabolic disease, no hardware, no fractures, radiographic positioning of the wrist in flexion/extension <20°, minimum 3 cm of distal radius visible, and acceptable scaphopisocapitate relationship (defined as the volar cortex of the pisiform lying between the volar cortices of the distal pole of the scaphoid and capitate). Angles measured included radioscaphoid (RSA), radiolunate (RLA), scapholunate (SLA), capitolunate (CLA), and radiocapitate (RCA). Measurements on wrist versus hand radiographs were compared for each patient. Interclass correlation coefficients (ICCs) were computed to assess interrater and intrarater agreement.

RESULTS

Interrater agreement for hand and wrist radiographs were (respectively): SLA 0.746 and 0.763, RLA 0.918 and 0.933, RCA 0.738 and 0.538, CLA 0.825 and 0.650, RSA 0.778 and 0.829. Interrater agreement was superior in favor of hand radiographs for the RCA (0.738 [0.605-0.840] vs 0.538 [0.358-0.700]) and CLA (0.825 [0.728-0.896] vs 0.650 [0.492-0.781]), but not the SLA, RLA, or RSA. Two of the three raters had excellent intrarater agreement for all hand radiograph measures (ICC range, 0.907-0.995). The mean difference in measured angles on hand versus wrist radiographs was <5° for all angles.

CONCLUSIONS

Carpal angles may be measured reliably on hand radiographs with an acceptable scaphopisocapitate relationship and wrist flexion/extension of <20°.

CLINICAL RELEVANCE

By mitigating the need to obtain additional radiographic views, surgeons may be able to reduce the cost and radiation exposure to their patients.

Measurement of Carpal Alignment Indices Using 3-Dimensional Computed Tomography

PURPOSE

This study aimed to establish normal values for wrist carpal alignment measured by 3-dimensional computed tomography (CT) and to show the inter- and intraobserver reliability of this measurement compared with simple radiography.

METHODS

The study utilized 3-dimensional CT and simple radiography of wrist joints in 30 asymptomatic volunteers. The wrist position was standardized using a custom-designed positioning device. Three independent observers measured carpal alignment parameters including distal radius articular angle, radiolunate angle, radioscaphoid angle, radiocapitate angle, radius-third metacarpal angle, scapholunate angle, lunocapitate angle, and lunate-third metacarpal angle.

RESULTS

Based on 3-dimensional CT measurement, the mean values of these parameters were: 12.9° ± 1.8° for the distal radius articular angle; 1.2° ± 3.8° for the radiolunate angle; 54.2° ± 5.6° for the radioscaphoid angle; 1.9° ± 2.2° for the radiocapitate angle; -1.0° ± 2.5° for the radius-third metacarpal angle; 52.9° ± 6.9° for the scapholunate angle; 0.7° ± 4.1° for the lunocapitate angle; -2.3° ± 4.6° for the lunate-third metacarpal angle. All parameters showed high inter- and intraobserver reliability in the 2 modalities.

CONCLUSIONS

The normal values and ranges for carpal alignment angles were evaluated by using 3-dimensional CT. We could obtain high reliability in 3-dimensional CT as well as plain radiograph for the measurement of carpal alignment.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Reliability and validity of carpal alignment measurements in evaluating deformities of scaphoid fractures

PURPOSE

Several radiographic carpal alignment indices are used to evaluate the deformities of scaphoid fractures. The purpose of this study was to determine the reliabilities and validities of radiographic carpal alignment indices commonly used to evaluate deformities of scaphoid fractures.

METHODS

Thirty-six patients with a scaphoid fracture were evaluated. Five carpal alignment indices were assessed on lateral plain radiographs, namely, scapholunate angle, radioscaphoid angle, radiolunate angle, radiocapitate angle, and capitolunate angle. Three examiners measured these radiographic indices at two sessions, and intraobserver and interobserver reliabilities were determined and expressed as intraclass correlation coefficients. Discriminant validities of radiographic carpal alignment indicies between injured and uninjured wrists were evaluated. For convergent validity testing, the correlation between the radiographic carpal alignment indices and intrascaphoid angles (ISAs) or height-to-length (HL) ratios on CT longitudinal scans was assessed. Further, carpal alignment indices after surgical reconstruction were compared to the Mayo wrist score.

RESULTS

Scapholunate and radiolunate angles had the highest reliabilities, and radiocapitate angle had the lowest. Radiolunate angle had the highest discriminant validity followed by scapholunate, and capitolunate angles. In convergent validity testing, scapholunate angles and radiolunate angles correlated with ISA angles, and radiolunate and capitolunate angles correlated with HL ratios. Only the radiolunate angles correlated with the Mayo wrist scores.

CONCLUSIONS

Among radiographic carpal alignment measures, radiolunate angle is the most reliable and valid carpal alignment index for evaluating deformities of scaphoid fractures. Scapholunate and capitolunate angles could be used as an alternative, but have less validity.

A laboratory comparison of computer navigation and individualized guides for distal radius osteotomy

PURPOSE

This article presents the results of a multiuser, randomized laboratory trial comparing the accuracy and precision of image-based navigation against individualized guides for distal radius osteotomy (DRO).

METHODS

Six surgeons each performed four DROs using image-based navigation and four DROs using individualized guides in a laboratory setting with plastic phantom replicas of radii from patients who had received DRO as treatment for radial deformity. Time required and correction errors of ulnar variance, radial inclination, and volar tilt were measured.

RESULTS

There were no statistically significant differences in the average correction errors. There was a statistically significant difference in the standard deviation of ulnar variance error (2.0 mm for navigation vs. 0.6 mm for guides). There was a statistically significant difference in the standard deviation of radial inclination error ([Formula: see text] for navigation vs. [Formula: see text] for guides). There were statistically significant differences in the times required (705 s for navigation vs. 214 s for guides) and their standard deviations (144 s for navigation vs. 98 s for guides).

CONCLUSIONS

Compared to navigated DRO, individualized guides were easier to use, faster, and produced more precise correction of ulnar variance and radial inclination. The combination of true three-dimensional planning, ease of use, and accurate and precise corrective guidance makes the individualized guide technique a promising approach for performing corrective osteotomy of the distal radius.

Effect of wrist position on the measurement of carpal indices on the lateral radiograph

The purpose of this study was to find out whether the carpal indices measured on lateral radiographs with a slightly malpositioned wrist are the same as those measured in the true neutral position. Lateral radiographic views of 25 wrists were taken with 5° intervals from 20° of flexion to 20° of extension. Most carpal indices measured in the flexed or extended position were significantly different from the wrist in zero flexion-extension, except scapholunate angle at 5° of extension and scaphocapitate angle at 5° and 10° of flexion. Starting from the flexed position, there was an average of -4.0° change in radioscaphoid angle, -1.0° in scapholunate angle, -1.0° in scaphocapitate angle, +3.0° in radiolunate angle, and +2.0° in lunocapitate angle for each 5° of extension with linear trends. The results from this study suggest that even minimal degrees of flexion-extension can affect the measurements of carpal indices on lateral radiographs.

RADIOGRAPHIC SIGNS OF STATIC CARPAL INSTABILITY WITH DISTAL END RADIUS FRACTURES: IS CURRENT TREATMENT ADEQUATE?

Patients presenting with distal end radius fractures may have concomitant carpal instability due to disruption of the scapholunate ligament. This study examined the incidence of static radiographic signs of carpal instability in patients with distal radial fractures before and after fracture treatment. We performed a retrospective radiographic study of 141 patients presenting to Central Middlesex Hospital, London between January 2002–May 2004 with distal end radius fractures. We used abnormal scapholunate angle as the primary indicator of possible carpal dissociation. Abnormal scapholunate angles were noted in 39% of patients at presentation and 35% of patients after treatment with no statistically significant intra-patient variability. Persistent static radiographic signs of carpal instability are high in this subset of patients. The long-term morbidity of persistent wrist instability may be avoided by early radiological diagnosis with clinical correlation to identify carpal ligament injuries and initiate treatment that addresses both the bony and ligamentous components of the injury.

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.

[Radiological procedures in the traumatised wrist]

Injuries of the wrist are difficult to diagnose because of the complex and narrow anatomic structures. On the basis of precise clinical examination, X-rays, CT and MRI are valuable additional tools that can be used. In the case of bone injury, spiral computer tomography with multiplanar reformatting is currently the method of choice. MRI is indicated for the identification of soft tissue or ligamentous injury and avital fragments or necrosis. Other diagnostic tools for the wrist are currently of minor importance. Technical and methodological innovations allow ever better visualisation and classification of lesions, as well as their extent, thus enabling more targeted therapy. However, prerequisites of effective use include differential assessment and precise knowledge of the procedures.

[Radiological procedures in the traumatised wrist]

Injuries of the wrist are difficult to diagnose because of the complex and narrow anatomic structures. On the basis of precise clinical examination, X-rays, CT and MRI are valuable additional tools that can be used. In the case of bone injury, spiral computer tomography with multiplanar reformatting is currently the method of choice. MRI is indicated for the identification of soft tissue or ligamentous injury and avital fragments or necrosis. Other diagnostic tools for the wrist are currently of minor importance. Technical and methodological innovations allow ever better visualisation and classification of lesions, as well as their extent, thus enabling more targeted therapy. However, prerequisites of effective use include differential assessment and precise knowledge of the procedures.

The radiographic measurement of ulnar translation

Our purpose was to quantify the Gilula score for measurement of lunate uncovering, to compare it with another method of measurement and to examine the reliability of these measurements in posteroanterior (PA) views in radial and ulnar deviation. Seventy-six normal wrist arthrograms were reviewed retrospectively. Carpal height and lunate uncovering measurements were made. Statistical analysis included mixed effects models to evaluate the difference between the mean measurements in each position. Reproducibility was assessed using imprecision estimates. Normal values for the Gilula method were 40% lunate uncovering in neutral, 49% in radial and 20% in ulnar deviation. There was a statistically significant difference between the values in the different views. Ulnar translation of the carpus can be measured reliably on neutral and radially deviated PA views using the Gilula method, but the different normal values for each view should be used. The Schuind method of measurement is comparable to the Gilula method in the neutral PA view.

A normal data-base of posteroanterior radiographic measurements of the wrist in healthy Egyptians

The roentgenographic morphology of the wrist has been described in textbooks and in articles but no ethnographic differences were reported. This study aims to identify normal radiographic anthropometry reference values and variations according to age and sex of carpal bones and joints in healthy Egyptians that might be useful in clinical practice. Selected landmarks were digitized on 300 posteroanterior wrist radiographs of asymptomatic volunteers. Men and women were equally represented as were two age groups (20-40 years and above 40-60 years). The roentgenograms were made, with standard exposure with the wrist and forearm in the neutral positions. It was found that in all age groups, males showed higher values than females in most of the measurements. The width of the distal radio-ulnar joint space, ulnar variance and length of the 3rd metacarpal were reduced in older subjects while radius of radio-carpal joint arc, carpal height, carpal-ulnar ratio and radial inclination were increased in older subjects. In ulnar variance and radial inclination, there were differences with respect to those reported in Mexicans and in Japanese. Information regarding normal values in wrist measurements could be used as the normal reference value for the evaluation of surgical management and follow-up of the wrist abnormalities.

The effect of rotational malalignment on X-rays of the wrist

This study evaluates the effect of rotational malposition of the wrist on measured radiographic parameters of the distal radius and carpus. Ten wrists from five healthy volunteers were imaged in varying degrees of rotation. The wrists were placed in a custom, calibrated jig and images were taken in 5 degrees increments to a maximum pronation and supination of 20 degrees . The results demonstrate the following: a steady decrease in the scapholunate and radioscaphoid angles with extremes of supination; an increase in palmar tilt with supination and a decrease in palmar tilt with pronation. The palmar tilt varied from -4 degrees to 15 degrees and the scapholunate angle ranged from 48 degrees to 29 degrees at the extremes of rotation. These results demonstrate how malrotation in X-ray positioning can have a significant effect on the apparent alignment of the distal radius and carpal bones. Measurements taken from poor X-rays typically fall outside the normal range and could adversely effect treatment decisions.

Modélisation du carpe osseux et biomécanique

Carpal morphology and orientation of carpal bones are usually studied on two-plane radiography. Those measurements depend on the incidence of X-ray and on the expertise of physician. A method that eliminates both should improve the accuracy of those measurements. The digital data from computed tomography scans can be use to describe carpal geometry. We defined biometric and angular parameters allowing the study of carpal morphology and bones orientation. From digital data from computed tomography scans software can obtain bone volume, inertia principal axis and volume of ellipsoid of inertia. Bone centroid location and principal axis orientation can be used to study bones orientation. 3D distances ratio between geometry centroid of carpal bones. The measurements allowed by this methodology are numerous. A study of a more consistent series of normal wrists will allow in the future for each quantitative parameter to define the normal range. A comparative study of normal wrists and pathology wrists should allow defining, for each pathology, the most judicious quantitative parameters.

From scans to sutures: computer-assisted orthopedic surgery in the twenty-first century

Computer-assisted surgery is the process of using medical images, such as CT scans, X-ray fluoroscopy, or 3D ultrasound, to improve patient care. A typical surgical procedure begins by acquiring and processing a CT scan with specially developed image-analysis software. A surgeon then performs a "virtual surgery" on the patient to develop a preoperative plan. In the operating room the medical image is registered to the patient's anatomy by finding an optimal rigid-body transformation. This transformation allows an object or motion in one coordinate frame to be represented in the other frame, and thus a surgeon can visualize the location of an instrument deep within concealed anatomy while avoiding structures at risk. The operating surgeon can also use computer-tracked fluoroscopy or ultrasound for 3D guidance. For the past seven years, our interdisciplinary research group has been investigating fundamental problems in orthopedic surgery of bones and joints. This paper is an overview of the problems and solutions that have been tested in a set of pilot clinical trials in which we have treated more than 250 patients for early or advanced arthritis, poorly healed bone fractures, and treatment of deep bone tumors.

Enhancing depth perception in translucent volumes

We present empirical studies that consider the effects of stereopsis and simulated aerial perspective on depth perception in translucent volumes. We consider a purely absorptive lighting model, in which light is not scattered or reflected, but is simply absorbed as it passes through the volume. A purely absorptive lighting model is used, for example, when rendering digitally reconstructed radiographs (DRRs), which are synthetic X-ray images reconstructed from CT volumes. Surgeons make use of DRRs in planning and performing operations, so an improvement of depth perception in DRRs may help diagnosis and surgical planning.

Assessment of four midcarpal radiologic determinations

Several radiologic measurement methods have been described for determining static carpal alignment of the wrist. These include the scapholunate, radiolunate, and capitolunate angles. The triangulation method is an alternative radiologic measurement which we believe is easier to use and more reproducible and reliable than the above mentioned methods. The purpose of this study is to assess the intraobserver reproducibility and interobserver reliability of the triangulation method, scapholunate, radiolunate, and capitolunate angles. Twenty orthopaedic residents and staff at varying levels of training made four radiologic measurements including the scapholunate, radiolunate and capitolunate angles as well as the triangulation method on five different lateral, digitized radiographs of the wrist and forearm in neutral radioulnar deviation. Thirty days after the initial measurements, the participants repeated the four radiologic measurements using the same radiographs. The triangulation method had the best intra-and-interobserver agreement of the four methods tested. This agreement was significantly better than the capitolunate and radiolunate angles. The scapholunate angle had the next best intraobserver reproducibility and interobserver reliability. The triangulation method has the best overall observer agreement when compared to the scapholunate, radiolunate, and capitolunate angles in determining static midcarpal alignment. No comment can be made on the validity of the measurements since there is no radiographic gold standard in determining static carpal alignment.

Ulnar-positive variance as a predictor of distal radioulnar joint ligament disruption

PURPOSE

Previous cadaveric data show that disruption of the triangular fibrocartilage complex (TFCC) at the wrist allows 0.5 to 3.0 mm of proximal radius migration. Anatomic studies have documented the presence of superficial and deep fibers of both the palmar and the dorsal distal radioulnar joint (DRUJ) ligaments. The aim of this study was to determine the contribution of the superficial and deep fibers of the DRUJ ligaments to longitudinal forearm stability as measured by ulnar-positive variance.

METHODS

Eight fresh-frozen cadaver specimens were included in this study. Each specimen was secured with external fixation clamps to a sequential loading frame with the elbow in 90 degrees of flexion and the forearm and wrist in neutral pronation supination, neutral ulnar-radial deviation, and neutral volar-dorsal angulation. The radial head was resected and a force gauge was applied to the proximal radius. The peripheral TFCC was identified through an incision between the fifth and sixth extensor compartments and the dorsal capsulotomy of the DRUJ capsule. After baseline measurement sequential transection of the superficial and deep fibers of the TFCC was performed. Before and after each step load application and removal were performed by attaching an 88.90-N weight to the end of a force gauge and via longitudinal traction on the proximal part of the radius, and ulnar variance was measured with wrist fluoroscopy.

RESULTS

Transection of the superficial TFCC fibers resulted in radius migration of 0.70 mm. This migration, however, was not significantly different from that observed at baseline. After both the superficial and deep TFCC fibers were transected the radius migrated proximately with load. This change of ulnar variance was significantly greater than that observed at baseline or after transection of only the superficial TFCC fibers.

CONCLUSIONS

Traumatic injury to the TFCC with radiographic evidence of ulnar-positive variance may be an indication of disruption of the deep TFCC fibers.

Assessment of midcarpal deformity of the wrist using the triangulation method

PURPOSE

The purpose of this study is to present an alternative method for static radiologic assessment of the wrist for midcarpal instability (ie, palmar intercalated segmental instability [PISI] and dorsal intercalated segmental instability [DISI]). The triangulation method uses 3 anatomic landmarks observed on the standard lateral x-ray of the wrist.

METHODS

A total of 125 normal lateral radiographs were measured to determine the normal range for the dorsal limb (DL) to palmar limb (PL) ratio. A 2-step process of performing triangulation is described. The first step is nonspecific screening of the radiograph and defines values greater than 1.0 as having a DISI deformity and values less than 0.5 as having a PISI deformity. The second step is used only for borderline values, which takes the position of the wrist into consideration and uses a normagram (reference chart) to match the DL:PL ratio with the radiometacarpal (RM) angle.

RESULTS

The average lateral wrist position was 8.4 degrees of extension (-8.4). The average DL:PL ratio was 0.75 +/- 0.09 (range, 0.93-0.57).

CONCLUSIONS

Based on these data we defined DISI deformity of the wrist as DL:PL ratios greater than 1.0, and ratios less than 0.5 representing PISI deformities. The triangulation method of assessing midcarpal alignment of the carpus is a practical and simple alternative to the traditional static radiologic method of assessing midcarpal instability of the wrist.