Ladislav Nagy

Normal kinematics of carpal bones: A three-dimensional analysis of carpal bone motion relative to the radius

Normal carpal kinematics were studied in 22 cadaver specimens using a biplanar radiography method. The kinematics of the trapezium, capitate, hamate, scaphoid, lunate, and triquetrum were determined during wrist motion in sagittal and coronal planes. The results were expressed using the concept of the screw displacement axis and converted to describe the magnitude of rotation about and translation along three axes (X-axis: pronation-supination axis, Y-axis: flexion-extension axis, and Z-axis: radial-ulnar deviation axis) commonly used for the wrist. The orientation of these axes is expressed relative to the radius. Within the proximal carpal row, considerable differences of carpal behavior around the Y-axis were observed during sagittal plane motion of the wrist. The scaphoid exhibited the greatest magnitude of rotation, and the lunate the least. The magnitude of rotation of the carpal bones around the X-axis during sagittal plane motion of the wrist was small. The proximal carpal bones exhibited some ulnar deviation in 60 degrees of wrist flexion. During coronal plane motion of the wrist, the magnitude of radial-ulnar deviation of the distal carpal bones was mutually similar and generally of a greater magnitude than that of the proximal carpal bones. The proximal carpal bones experienced some flexion during radial deviation of the wrist and extension during ulnar deviation of the wrist. Translation was generally minimal in all carpal bones throughout wrist motion. This study reports results from the largest cadaver wrist kinematics study completed to date. The accuracy of the current method was improved when compared to previous studies. A sufficient number of specimens to allow statistical comparison was used and minimal interspecimen variability was noted. This study enabled a precise description of quantitative analyses of normal carpal kinematics relative to the radius.

Role of MR imaging in chronic wrist pain

Magnetic resonance (MR) imaging for chronic wrist pain is challenging. Correct assessment of the triangular fibrocartilage, hyaline cartilage, ligaments, and tendons has become mandatory for comprehensive decision making in wrist surgery. The MR technique, potential and limits of MR imaging in patients with chronic wrist pain will be discussed. MR arthrography with injection of gadolinium-containing contrast material into the distal radioulnar joint is suggested for evaluation of the triangular fibrocartilage. The clinically meaningful ulnar-sided peripheral tears are otherwise hard to diagnose. The diagnostic performance of MR imaging for interosseous ligament tears varies considerably. The sensitivity for scapholunate ligament tears is consistently better than for lunotriquetral ligament tears. Gadolinium-enhanced MR imaging is considered to be the best technique for detecting established avascularity of bone, but the assessment of the MR results remains challenging. Most cases of ulnar impaction syndrome have characteristic focal signal intensity changes in the ulnar aspect of the lunate. Avascular necrosis of the lunate (Kienböck’s disease) is characterized by signal changes starting in the proximal radial aspect of the lunate. MR imaging is extremely sensitive for occult fractures. Questions arise if occult posttraumatic bone lesions seen on MR images only necessarily require the same treatment as fractures evident on plain films or computed tomography (CT) images. MR imaging and ultrasound are equally effective for detecting occult carpal ganglia. Carpe bossu (carpal boss) is a bony protuberance of a carpometacarpal joint II and III which may be associated with pain.

Peripheral Tear of the Triangular Fibrocartilage: Depiction with MR Arthrography of the Distal Radioulnar Joint

OBJECTIVE Although central tears of the triangular fibrocartilage are easily seen on imaging, peripheral tears of the ulnar attachment are frequently missed. The aim of this study was to evaluate the accuracy of MR arthrography of the distal radioulnar joint in depiction of peripheral tears of the triangular fibrocartilage. MATERIALS AND METHODS Forty-one patients (18 women, 23 men; mean age, 38 years; age range, 18-60 years) underwent MR arthrography and wrist arthroscopy. For MR arthrography, iopamidol (300 mg I/mL) and gadopentetate dimeglumine (4 mmol/L) were injected into the distal radioulnar joint. Consensus review of both MR arthrograms and conventional arthrograms was performed by two experienced musculoskeletal radiologists. Presence or absence of communicating and noncommunicating tears of the ulnar attachment of the triangular fibrocartilage was recorded. Arthroscopy was used as the standard of reference for determining sensitivity, specificity, and accuracy in detection of tears of the ulnar attachment. RESULTS At MR arthrography, communicating tear of the ulnar attachment was diagnosed in three patients, noncommunicating tear in 19 patients, and normal attachment in 19 patients. Arthroscopy revealed peripheral tear of the triangular fibrocartilage in all three patients with communicating tear, in 14 of 19 patients with noncommunicating tear, and in three of 19 patients with normal attachment. The sensitivity was 85% (17/20), specificity was 76% (16/21), and accuracy was 80% (33/41). CONCLUSION MR arthrography of the distal radioulnar joint is accurate in depiction of peripheral tears of the ulnar attachment of the triangular fibrocartilage. These tears often appear as noncommunicating tears extending from the distal radioulnar joint into the triangular fibrocartilage.

Three-dimensional correction of distal radius intra-articular malunions using patient-specific drill guides

PURPOSE To analyze the feasibility of combining computer-assisted 3-dimensional planning with patient-specific drill guides and to evaluate this technologys surgical outcomes for distal radius intra-articular malunions. METHODS Six symptomatic patients with intra-articular malunions of the distal radius with a stepoff of more than 2 mm were treated with an outside-in corrective osteotomy. The described cases consist of 2 malunited volar Barton fractures, 2 radial styloid fractures, 1 AO-type C1 fracture, and 1 die-punch fracture. The osteotomies were guided by 3-dimensionally generated aiming guides that allowed precise cutting and the reduction of up to 2 fragments. All 6 patients were examined clinically and radiologically after 1 year. The surgical outcomes were quantitatively analyzed by comparing the preoperative and postoperative computed tomographic data. RESULTS In all 6 cases, the osteotomies were consolidated 8 weeks postoperatively. After 1 year, 4 patients were pain-free, 1 had mild pain, and 1 experienced moderate pain during heavy work. Wrist motion and grip strength were improved in all patients. The postoperative radiographs showed no articular stepoff or degenerative changes. CONCLUSIONS Patient-specific aiming guides provided a reliable method to correct intra-articular malunions of the distal radius. This technique allows the surgeon to safely perform difficult intra-articular osteotomies and may help limit the need for salvage procedures such as partial or complete wrist arthrodesis. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.

Axial loading induces rotation of the proximal carpal row bones around unique screw-displacement axes

The changes in carpal bone alignment secondary to the application of an axial compressive load through the major wrist motor tendons while the wrist is kept in neutral position (isometric loading) have been investigated on 13 fresh cadaver specimens using a biplanar radiographic method of kinematic analysis. The scaphoid, lunate and triquetrum rotate an average of 5.1, 4.2, and 3.8 degrees, respectively, around different screw displacement axes, all implying flexion, radial deviation and supination. Based on these findings, a new interpretation of the mechanism by which the wrist remains stable under physiologic loads is provided.

Is Dynamic Gadolinium Enhancement Needed in MR Imaging for the Preoperative Assessment of Scaphoidal Viability in Patients with Scaphoid Nonunion

PURPOSE To compare the accuracy of dynamic gadolinium-enhanced magnetic resonance (MR) imaging with that of standard MR imaging for assessing the viability of the proximal pole of the scaphoid in patients with nonunion. MATERIALS AND METHODS The study protocol was submitted to the institutional review board, and the need to obtain additional approval was waived for this retrospective study. Twenty-eight patients (mean age ± standard deviation, 24.3 years ± 6.4) with nonunion of a scaphoid fracture underwent dynamic gadolinium-enhanced MR imaging of the wrist 28 days ± 19 before surgery. Dynamic gadolinium-enhanced MR imaging consisted of acquisition of 40 consecutive coronal T1-weighted images over 1 minute. Two readers retrospectively evaluated MR images obtained with a standard protocol and rated the viability of the proximal scaphoid pole. The steepest upslope of gadolinium uptake was calculated in a region of interest placed in the proximal scaphoid pole by a third reader. Receiver operating characteristic curves were calculated, and the areas under the receiver operating characteristic curve (A(z) values) were compared. Diagnostic performance in determining scaphoid viability was calculated for readers 1 and 2. Histologic findings in 11 patients and surgical findings in all patients served as the standard of reference. RESULTS The sensitivity, specificity, and accuracy of standard MR imaging in the detection of scaphoid necrosis were 54%, 93%, and 75%, respectively, for reader 1 and 62%, 93%, and 78% for reader 2. Interreader reliability was excellent (κ = 0.92). The A(z) was 0.82 for reader 1 and 0.87 for reader 2. The diagnostic performance of dynamic gadolinium-enhanced MR imaging, determined with the steepest upslope value, was inferior to that of standard MR imaging, with an A(z) of 0.57. Findings at histologic examination (viable bone, necrotic bone, callus formation) did not correlate with those at dynamic gadolinium-enhanced MR imaging. CONCLUSION Because the diagnostic performance of dynamic gadolinium-enhanced MR imaging in the evaluation of scaphoid viability was inferior to that of a standard MR imaging protocol, dynamic acquisition may not be needed in patients with nonunion of scaphoid fractures.

Corrective osteotomies in malunions of the distal radius: do we get what we planned?

Fifteen patients with symptomatic malunions of the distal radius were treated with osteotomies, corticocancellous bone grafting, and plate and screw fixation. We investigated the ability of precise preoperative planning of the size and shape of the corticocancellous bone graft to restore alignment of the radius to within 5° angular deformity and 2 mm ulnar variance as compared with the opposite uninjured wrist. Only six of 15 patients (40%) satisfied these criteria. Inter-rater reliability of radiographic assessment was greater than 0.85. Five patients had residual radial inclination or sagittal tilt greater than 10° with respect to the uninvolved wrist. Four patients had a residual ulnar variance greater than 2 mm with respect to the uninvolved wrist. Residual shortening (three of four patients), but not residual angulation, was associated with unsatisfactory pain and stiffness an average of 19.5 months after osteotomy (range, 11-32 months). We conclude that a distal radius osteotomy using a precisely planned and measured interpositional corticocancellous graft does not restore distal radius alignment in most patients, and that failure to restore length is associated with continued pain and stiffness.Level of Evidence: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Assessment of Radial and Ulnar Torsion Profiles with Cross-sectional Magnetic Resonance Imaging: A Study of Volunteers

BACKGROUND We determined whether the torsion profiles of the radius and ulna could be reliably assessed with cross-sectional magnetic resonance imaging and whether these torsion profiles were comparable on the two sides of volunteers. METHODS We assessed magnetic resonance imaging cross sections of the left and right forearms of twenty-four asymptomatic volunteers. The torsion profile of the ulna was defined as the angle formed between a line tangential to the volar cortical surface of the distal part of the humerus and a line connecting the center of the ulnar head and the center of the ulnar styloid. Use of paired proximal and distal landmarks resulted in five different methods of assessment of the radial torsion profile. Intrarater and interrater reliabilities and side-to-side variability were assessed. RESULTS This method of assessment of the ulnar torsion profile had intraclass and interclass coefficients of 0.95 and 0.91, respectively. A method previously described by Bindra et al. had the best combined intrarater and interrater reliabilities for assessment of the radius. The mean differences between the right and left sides of the volunteers were the lowest with the use of these two methods; nevertheless, the maximum side-to-side difference was > 30 degrees with techniques. CONCLUSIONS Torsion-profile assessment with cross-sectional magnetic resonance imaging had high intrarater and interrater reliabilities. However, individual side-to-side variations in the radial and ulnar profiles are important considerations. CLINICAL RELEVANCE Cross-sectional magnetic resonance imaging is currently the only available method to quantify rotational malunion of the radius and ulna. Its low side-to-side reliability warrants comparison between the imaging results and the clinical findings. A side-to-side difference in the rotation profile may serve as a reason to perform an axial osteotomy when the results of the clinical and magnetic resonance imaging assessments are consistent with each other.

Three-dimensional postoperative accuracy of extra-articular forearm osteotomies using CT-scan based patient-specific surgical guides

BackgroundComputer assisted corrective osteotomy of the diaphyseal forearm and the distal radius based on computer simulation and patient-specific guides has been described as a promising technique for accurate reconstruction of forearm deformities. Thereby, the intraoperative use of patient-specific drill and cutting guides facilitate the transfer of the preoperative plan to the surgery. However, the difference between planned and performed reduction is difficult to assess with conventional radiographs. The aim of this study was to evaluate the accuracy of this surgical technique based on postoperative three-dimensional (3D) computed tomography (CT) data.MethodsFourteen patients (mean age 23.2 (range, 12-58) years) with an extra-articular deformity of the forearm had undergone computer assisted corrective osteotomy with the healthy anatomy of the contralateral uninjured side as a reconstruction template. 3D bone surface models of the pathological and contralateral side were created from CT data for the computer simulation. Patient-specific drill and cutting guides including the preoperative planned screw direction of the angular-stable locking plates and the osteotomy planes were used for the intraoperative realization of the preoperative plan. There were seven opening wedge osteotomies and nine closing wedge (or single-cut) osteotomies performed.Eight-ten weeks postoperatively CT scans were obtained to assess bony consolidation and additionally used to generate a 3D model of the forearm. The simulated osteotomies- preoperative bone models with simulated correction - and the performed osteotomies - postoperative bone models – were analyzed for residual differences in 3D alignment.ResultsOn average, a significant higher residual rotational deformity was observed in opening wedge osteotomies (8.30° ± 5.35°) compared to closing wedge osteotomies (3.47° ± 1.09°). The average residual translation was comparable small in both groups, i.e., below 1.5 mm and 1.1 mm for opening and closing wedge osteotomies, respectively.ConclusionsThe technique demonstrated high accuracy in performing closing wedge (or single-cut) osteotomies. However, for opening wedge osteotomies with extensive lengthening, probably due to the fact that precise reduction was difficult to achieve or maintain, the final corrections were less accurate.

Three-Dimensional Computed Tomographic Analysis of 11 Scaphoid Waist Nonunions

PURPOSE To virtually assess nonunions of the scaphoid waist using 3-dimensional computed tomography (CT) reconstruction for the amount of displacement of the distal fragment and the postfracture reduction position using the intact opposite scaphoid for reference. METHODS We generated 3-dimensional reconstructions for 11 nonunions of the scaphoid waist and the contralateral intact scaphoids based on CT. The mean age of the patients was 25 years and the time from injury to the CT scan was 2.4 years. We used the mirrored 3-dimensional model of the healthy scaphoid to guide virtual reduction of the nonunion and calculated the amount of displacement of the distal pole fragment from prereduction to postreduction. We compared the results with the intrascaphoid angles calculated using single CT slices. RESULTS The scaphoid nonunions showed a mean flexion deformity of 23°, an ulnar deviation of 5°, and a pronation deformity of 10°. Mean translation was 0.9 mm volarward, 0.2 mm radialward, and 3.3 mm distalward. After reduction, all scaphoids showed a bony overlap on the dorsoradial side; the mean volume of this region was 3% of total bone volume. There was no correlation between the degree of displacement and the intrascaphoid angle measurements. CONCLUSIONS Preoperative planning for scaphoid reconstruction is usually performed using conventional radiographs and single CT slices. However, by synthesizing the information from the CT into a 3-dimensional reconstruction, an exact analysis is possible. This method also allows quantification of prosupination displacement. The postreduction area of dorsal bone overlap may be due to appositional callus formation. CLINICAL RELEVANCE Simple volar opening of the scaphoid allows correction of angulation deformities but results in lengthening of the scaphoid. Correct reduction of the scaphoid fragments is often only possible if the dorsal appositional callus is resected.