Ligamentoplasty using the ulnotriquetral ligament with wafer procedure for chronic triangular fibrocartilage complex foveal tear: Short-tem outcome.

BACKGROUND: We developed a new ligamentoplasty technique using the ulnotriquetral ligament (UTL) via a palmar approach for cases with dorsal instability of the ulna due to a foveal tear of the triangular fibrocartilage complex (TFCC). The study aimed to evaluate the clinical outcomes of this procedure. METHODS: We retrospectively analyzed 19 cases with foveal tears of TFCC who underwent the ligamentoplasty using UTL. We harvested the UTL from the triquetrum as a pedicle graft, avoiding damage of the connection between the base of the UTL and palmar radioulnar ligament (PRUL) as possible. The graft was flipped proximally and pulled out through the bone tunnel from the ulnar fovea to the ulnar neck, then fixed to the fovea using a tenodesis screw. The function of the TFCC can be reproduced by pulling out the UTL along with the PRUL through the ulnar fovea and re-establishing the PRUL tension. Clinical results were evaluated at least 12 months following surgery. The preoperative and postoperative wrist pain level on a neumerical rating scale (NRS), the radioulnar joint (DRUJ) ballottement test, the range of motion, the grip strength, and the Patient-rated wrist evaluation (PRWE) scores were evaluated. RESULTS: In all cases, the DRUJ ballottement test became negative at the final follow up compared with the normal side on manual examination. The pain levels significantly decreased as reflected by a decrease in NRS from 6.8 to 2.5 at final follow up (p < 0.01). The range of pronation/supination motion was improved from 149° to 157°. The mean PRWE score significantly decreased from 52.1 to 22.8 (p < 0.01). The postoperative pain level on the NRS scale of the three patients poorly improved. One case of the three with the 3 mm positive ulnar variance needed additional ulnar shaft shortening using a plate seven months after the primary procedure. CONCLUSIONS: The ligamentoplasty using UTL efficiently restored the ulnar palmar stability in all 19 cases and significantly decreased the wrist pain and the PRWE scores. STUDY DESIGN: Clinical, retrospective study.

Lunate fracture healing after partial capitate shortening in Kienböck disease.

BACKGROUND: It is unclear whether lunate fracture types in Kienböck disease correlate with the degree of fracture healing. This study aimed to review the clinical results of stage 3 Kienböck disease treated using partial capitate shortening (PCS) and to evaluate the healing rates of lunate fractures based on the fracture types. METHODS: Twenty-three patients were clinically and radiographically followed up for >2 years after PCS. The preoperative location and postoperative healing of the lunate fracture were evaluated using plain radiography, computed tomography, and/or magnetic resonance imaging. Results were evaluated using the Kienböck scoring system by Nakamura. RESULTS: PCS was clinically effective, demonstrating excellent and good results in 11 and 11 patients, respectively. Pain evaluated using the visual analog scale, wrist extension, flexion motion, and grip strength significantly improved postoperatively (p < 0.01). Fractures were preoperatively detected in all 23 cases. Fracture locations were preoperatively classified into five subtypes based on radiographs: volar pole in five patients, dorsal pole in three, coronal in five, transverse in nine, and ulnar in one. The overall union rate of the lunate fracture was 48%, whereas none of the coronal fractures healed. CONCLUSIONS: PCS was effective in treating stage 3 Kienböck disease. Coronal lunate fractures had a poor healing rate relative to those of the other fracture types. STUDY DESIGN: Clinical, retrospective study.

Intra-articular corrective osteotomy for intra-articular malunion of distal radius fracture using three-dimensional surgical computer simulation and patient-matched instrument.

BACKGROUND: Corrective osteotomy of malunited intra-articular distal radius fracture is challenging. In this study, we investigated the results in patients with malunited intra-articular distal radius fracture who underwent intra-articular corrective osteotomy through an extra-articular approach using three-dimensional (3-D) computer simulation and a patient-matched instrument (PMI). METHODS: We retrospectively studied five consecutive patients with symptomatic malunited intra-articular distal radius fracture who underwent corrective osteotomy using a PMI. The maximal step-off on computed tomography and the deformity angle on plain radiographs were evaluated. The clinical examination parameters included range of motion (ROM), grip strength, pain according to visual analog scale (VAS), and Patient-Rated Wrist Evaluation (PRWE) score. RESULTS: The maximal step-off was significantly reduced from 4.9 ± 1.8 to 1.0 ± 0.2 mm (p = 0.008). The absolute differences between the affected side and the normal contralateral side in radial inclination were significantly reduced from 5.4° ± 3.4°-1.2° ± 1.1° (p = 0.043). These differences were not significantly reduced postoperatively in the volar tilt and ulnar variance. VAS was significantly reduced from 4.1 ± 1.6 to 0.9 ± 0.7 cm (p = 0.006). The PRWE score significantly improved from 41.6 ± 22.0 to 15.7 ± 19.5 (p = 0.043). Grip strength was significantly increased from 54.0% ± 14.8%-85.8% ± 18.8% (p = 0.003). The preoperative and postoperative total arc of the wrist and forearm ROM were not significantly different. CONCLUSIONS: Intra-articular corrective osteotomy using PMI could be one of the reliable treatment options for intra-articular malunion. PMI has exceptionally high precision performance, and it is also anticipated to yield superior surgical results.

Correlation between playing position, elbow physical findings and elbow pain in elementary school baseball players: Results of a multi-regional study in Japan.

BACKGROUND: Elbow injuries are common in young baseball players and evaluating the characteristics of young baseball players in a large-scale population is necessary. However, few studies have compared playing position, length of baseball experience, physical findings, and elbow pain in young baseball players. This retrospective multi-regional cohort study sought to document the physical findings at the elbow in Japanese elementary school baseball players and to examine the relationship between playing position, length of baseball experience, physical findings at the elbow, and elbow pain. METHODS: In 2014, 720 fifth-grade baseball players from four regions in Japan were invited to participate in a questionnaire survey and undergo physical examination to obtain data on position played, length of baseball experience, presence of elbow pain, and physical findings at the elbow, including range of motion, tenderness, and valgus stress test results. Potential risk factors associated with elbow pain and correlations between physical findings and playing position, length of baseball experience, and elbow pain were investigated. RESULTS: The 720 subjects had a mean age of 10.4 years and 29.4% reported having experienced elbow pain for ≥1 week. Risk factors for elbow pain included playing pitcher and catcher, playing pitcher and fielder, and length of baseball experience. The most frequent finding was limitation of flexion (21.1%) followed by tenderness of the medial epicondyle (18.3%) and a positive valgus stress test (14.3%). These three findings were also significantly associated with elbow pain. Elbow extension was limited in 14.9% of subjects but there was no correlation with length of baseball experience or elbow pain. CONCLUSIONS: Our data show that elementary school baseball players who experienced elbow pain are likely to have valgus stress overload. Elbow pain might be prevented by not playing pitcher and catcher.

Bidirectional Dislocation of the Distal Radioulnar Joint After Distal Radius Fracture: Case Report.

We report a patient with bidirectional dislocation of the distal radioulnar joint after malunited distal radius fracture, in which the ulnar head dislocated dorsally during forearm pronation and palmarly during supination without manual compression of the ulnar head. The patient had chronic ulnar wrist pain and experienced a painful clunk during forearm rotation. The distal radioulnar joint ballottement test was positive in both the dorsal and palmar directions. Her distal radius was malunited with a 20° dorsal angulation and 18° pronation deformity. A corrective osteotomy of the radius with open repair of the triangular fibrocartilage complex foveal avulsion yielded success. At the 7-year follow-up, there was almost a normal range of wrist and forearm motion, 83% grip strength, no arthritis, and a stable distal radioulnar joint.

Computed tomography arthrography using a radial plane view for the detection of triangular fibrocartilage complex foveal tears.

PURPOSE: To classify triangular fibrocartilage complex (TFCC) foveal lesions on the basis of computed tomography (CT) arthrography using a radial plane view and to correlate the CT arthrography results with surgical findings. We also tested the interobserver and intra-observer reliability of the radial plane view. METHODS: A total of 33 patients with a suspected TFCC foveal tear who had undergone wrist CT arthrography and subsequent surgical exploration were enrolled. We classified the configurations of TFCC foveal lesions into 5 types on the basis of CT arthrography with the radial plane view in which the image slices rotate clockwise centered on the ulnar styloid process. Sensitivity, specificity, and positive predictive values were calculated for each type of foveal lesion in CT arthrography to detect foveal tears. We determined interobserver and intra-observer agreements using kappa statistics. We also compared accuracies with the radial plane views with those with the coronal plane views. RESULTS: Among the tear types on CT arthrography, type 3, a roundish defect at the fovea, and type 4, a large defect at the overall ulnar insertion, had high specificity and positive predictive value for the detection of foveal tears. Specificity and positive predictive values were 90% and 89% for type 3 and 100% and 100% for type 4, respectively, whereas sensitivity was 35% for type 3 and 22% for type 4. Interobserver and intra-observer agreement was substantial and almost perfect, respectively. The radial plane view identified foveal lesion of each palmar and dorsal radioulnar ligament separately, but accuracy results with the radial plane views were not statistically different from those with the coronal plane views. CONCLUSIONS: Computed tomography arthrography with a radial plane view exhibited enhanced specificity and positive predictive value when a type 3 or 4 lesion was identified in the detection of a TFCC foveal tear compared with historical controls. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

The biomechanical effect of the distal interosseous membrane on distal radioulnar joint stability: a preliminary anatomic study.

PURPOSE: The distal interosseous membrane (DIOM) is a secondary stabilizer of the distal radioulnar joint (DRUJ) and has a considerably variable morphology. The purpose of this study was to investigate whether innate DRUJ stability is influenced by the anatomic variation of the DIOM. METHODS: Ten fresh-frozen cadaver upper extremities were used in this study. The humerus and the ulna were affixed rigidly to a custom-made apparatus, with the elbow in 90° of flexion. Testing was performed by translating the radius in volar and dorsal directions relative to the ulna, with a 20-N applied force in neutral forearm alignment, 60° pronation, and 60° supination. Total translation of the radius was measured as DRUJ laxity. After the experiment, we investigated anatomic variation of the DIOM, especially regarding the existence of the distal oblique bundle (DOB), which is a notably thick fiber within the DIOM. We compared the DRUJ stability between the groups with and without the DOB. RESULTS: The DOB was found in 4 of 10 specimens. The group with a DOB demonstrated a significantly greater DRUJ stability in the neutral position than the group without a DOB. In pronated and supinated forearm positions, no significant difference in DRUJ stability was obtained between the groups with and without a DOB. CONCLUSIONS: Innate DRUJ stability in the neutral forearm position was greater in the group with a DOB than in those without a DOB. CLINICAL RELEVANCE: This study suggests that considerable variation exists in DRUJ laxity and that it partially depends on anatomical variations of the DIOM.

Three-dimensional analysis of cubitus varus deformity after supracondylar fractures of the humerus.

BACKGROUND: What is thought of as a classic "cubitus varus" deformity usually consists of varus, extension, and internal rotation. However, its 3-dimensional (3D) pattern with 3D imaging has not been reported. This study aimed to obtain such 3D patterns using 3D bone models created from computed tomography data and evaluate the accuracy of conventional radiographic and clinical methods of assessing the deformity. METHODS: Imaging of 25 humeri of 25 patients with cubitus varus deformity caused by previous humeral supracondylar fractures was performed. The deformity was assessed by superimposing the 3D bone model onto a mirror-image model of the contralateral normal humerus. The 3D deformity pattern of cubitus varus was evaluated based on the 3 deformity components. Values obtained from conventional radiographic and physical measurements--that is, humerus-elbow-wrist angle (HEW-A), tilting angle (TA), maximal elbow flexion angle (MEF), and internal rotation angle (IRA)--were compared with those from the 3D technique. RESULTS: Of the patients, 44% had varus, extension, and rotation deformities of 10° or greater; 20% had varus and extension deformities of 10° or greater; 16% had varus and internal rotation deformities of 10° or greater; and 20% had varus deformity only. When the 3D measurements were considered accurate, an error of 10° or greater was found in 8%, 24%, 8%, and 44% of cases in terms of HEW-A, TA, MEF, and IRA values, respectively. CONCLUSION: Of the humeri, 80% had other bony deformities in addition to varus and 20% had isolated varus deformities. HEW-A and MEF showed reasonable accuracy as measures for the degree of deformity, whereas TA and IRA were found to be relatively inaccurate.

Proximal Horizontal Flap Tears of TFCC Diagnosed by Computed Tomography Arthrography: Six Case Series.

Background Proximal horizontal tears of the triangular fibrocartilage complex (TFCC) represent the tears at the proximal surface of the articular disk with a normal appearance of the distal surface. Preoperative diagnosis of TFCC flap tears is challenging. Objectives This report aims to present a diagnostic method using computed tomography (CT) arthrography for the proximal horizontal flap tears of the TFCC and to report our clinical outcomes. Patients and Methods Six patients were included who were preoperatively suspected to have proximal horizontal flap tears of the TFCC via CT arthrography. Arthrography was conducted by injecting dye into the distal radioulnar joint (DRUJ), and CT images were obtained immediately following arthrography. We performed arthroscopic or direct flap debridement with concomitant surgeries: ulnar shortening with positive ulnar variance and corrective osteotomy with the malunion following distal radius fracture. Results Preoperative CT arthrography clearly revealed the flaps to be flipped over toward the radiopalmar side of the DRUJ in four cases and a teardrop-shaped dye defect in two. We were able to identify the dislocated flap by arthroscopy avulsed from the proximal aspect of the articular disk within the DRUJ in all six cases. The mean pain level decreased from 10 preoperatively to 0.3 postoperatively on the visual analog scale. The mean patient-rated wrist evaluation score decreased from 43.5 preoperatively to 11.2 postoperatively. Conclusions Our study shows that CT arthrography can be a promising method for diagnosing proximal horizontal flap tears of the TFCC. Debridement of the flaps and concomitant surgeries showed satisfactory clinical results. Level of Evidence This is a Level 4, diagnostic study.

Distal Ulnar Metaphyseal Wedge Osteotomy for Ulnar Abutment Syndrome.

Background Ulnar shortening osteotomy of the diaphysis is a common and effective surgical procedure for ulnar abutment syndrome. However, this procedure has some disadvantages, such as a long period until union and a relatively high nonunion rate. To overcome these disadvantages, we have developed distal ulnar metaphyseal wedge osteotomy. The purpose of this article is to describe the technique and to report its clinical results. Patients and Methods Distal ulnar metaphyseal wedge osteotomy consists of resection of the wedge fragment at the distal ulnar metaphysis, compressing the distal fragment of the ulna toward the radial-proximal direction and fixation with a Herbert type headless screw. We performed this procedure for 58 patients with ulnar abutment syndrome, and the clinical data of 43 patients who were followed for > 6 months were analyzed. We evaluated range of motion, grip strength, and HAND20 which is a validated subjective scoring system in Japan. Results All patients experienced relief from their ulnar wrist pain, and bone union was achieved within an average of 2.6 months. The range of dorsiflexion improved from 63° preoperatively to 69° postoperatively, grip strength compared with the contralateral hand improved from 77% preoperatively to 87% postoperatively, and HAND20 improved from 41.3 points preoperatively to 22.4 points postoperatively. Discussion This procedure has advantages especially in early bone union. This procedure should be taken into consideration as one of the options to treat ulnar abutment syndrome.

Change in the length of the ulnocarpal ligaments during radiocarpal motion: possible impact on triangular fibrocartilage complex foveal tears.

PURPOSE: The fovea of the ulnar head is the primary attachment site for both the distal radioulnar and the ulnocarpal ligaments. Thus, both ligaments should be simultaneously affected by the traumatic avulsion of the triangular fibrocartilage complex from its ulnar attachment. Little attention, however, has been directed toward the role of the ulnocarpal ligaments in the mechanics of this type of injury. The purpose of this study was to investigate the changes in length of the ulnocarpal ligaments during various radiocarpal motions and to determine the type of radiocarpal motion that makes the ulnocarpal ligament taut and that could cause foveal avulsion if it were excessive. METHODS: The 3-dimensional kinematics of the wrist joint were investigated noninvasively using a markerless bone registration technique in vivo. Magnetic resonance images of the wrists of 15 healthy volunteers were acquired in at least 5 positions during each wrist flexion-extension motion, radioulnar deviation, or the so called dart-throwing motion (radial extension-ulnar flexion motion). The 3-dimensional ligament paths of the ulnotriquetral, ulnolunate, ulnocapitate, and palmar radioulnar ligaments were modeled as the shortest paths between the fovea and the insertion point of each ligament. Changes in the 3-dimensional ligament length of each ligament between the neutral position and each wrist position were then calculated. RESULTS: The lengths of the ulnotriquetral and ulnocapitate ligaments increased the most on wrist radial extension, and the length of the ulnolunate ligament increased the most on wrist extension. The length of the palmar radioulnar ligament changed minimally during any motion. CONCLUSIONS: The ulnocarpal ligaments are likely to be stretched tensely in wrist radial extension and wrist extension. This study supports the hypothesis that one of the mechanisms responsible for a triangular fibrocartilage complex foveal tear is excessive traction of the ulnocarpal ligament caused by a fall on the outstretched hand.

Tenodesis of the Ulnotriquetrum Ligament to the Fovea for a Triangular Fibrocartilage Complex Tear.

We developed a novel procedure to treat a triangular fibrocartilage complex (TFCC) foveal tear, namely tenodesis of the ulnotriquetrum ligament (UTL) to the fovea. We attempted to reestablish the tension of the palmar radioulnar ligament by the procedure specifically in cases with palmar radius instability relative to the ulna. We used a palmar surgical approach to expose the palmar aspect of TFCC in which the ulnocarpal ligament merges with the palmar radioulnar ligament. UTL was distally excised at a 4 mm width from the triquetrum without disrupting its ligamentous connection to the palmar radioulnar ligament proximally. We pulled out the distal UTL through the bone tunnel from the fovea to ulnar neck. The UTL graft was fixed to the fovea with an interference screw. In 13 cases, this procedure effectively decreased ulnar wrist pain, improved distal radioulnar joint instability, and restored wrist motion and grip strength.

The in vivo isometric point of the lateral ligament of the elbow.

BACKGROUND: Many reports have discussed reconstruction of the lateral ulnar collateral ligament for the treatment of posterolateral rotatory instability of the elbow, but information regarding the isometric point of the lateral ligament of the elbow is limited. The purposes of the present study were to investigate the in vivo and three-dimensional length changes of the lateral ulnar collateral ligament and the radial collateral ligament during elbow flexion in order to clarify the role of these ligaments as well as to identify the isometric point for the reconstructed lateral ulnar collateral ligament on the humerus where the grafted tendon should be anchored. METHODS: We studied in vivo and three-dimensional kinematics of the normal elbow joint with use of a markerless bone-registration technique. Magnetic resonance images of the right elbows of seven healthy volunteers were acquired in six positions between 0 degrees and 135 degrees of flexion. We created three-dimensional models of the elbow bones, the lateral ulnar collateral ligament, and the radial collateral ligament. The ligament models were based on the shortest calculated paths between each origin and insertion in three-dimensional space with the bone as obstacles. We calculated two types of three-dimensional distances for the ligament paths with each flexion position: (1) between the center of the capitellum and the distal insertions of the ligaments (to investigate the physiological change in ligament length) and (2) between eight different humeral origins and the one typical insertion of the lateral ulnar collateral ligament (to identify the isometric point of the reconstructed lateral ulnar collateral ligament). RESULTS: The three-dimensional distance for the lateral ulnar collateral ligament was found to increase during elbow flexion, whereas that for the radial collateral ligament changed little. The path of the lateral ulnar collateral ligament gradually developed a detour because of the osseous protrusion of the lateral condyle with flexion. The most isometric point for the reconstructed lateral ulnar collateral ligament was calculated to be at a point 2 mm proximal to the center of the capitellum. CONCLUSIONS: The radial collateral ligament is essentially isometric, but the lateral ulnar collateral ligament is not. The lateral ulnar collateral ligament is loose in elbow extension and becomes tight with elbow flexion.

Radiographic study on the pattern of wrist joint destruction in rheumatoid arthritis.

When planning therapy for rheumatoid arthritis (RA) in the wrist joint, knowing the pattern of joint destruction is important. There were a few studies using the Larsen and modified Larsen method to evaluate RA wrist joint destruction. However, these methods are inadequate for thoroughly assessing the severity of joint destruction because joint bone erosion and joint space narrowing could not be evaluated individually in these methods. To clarify the pattern of RA wrist joint destruction in the different zones of the wrist, we conducted a large-scale radiographic study. We modified the van der Heijde/Sharp method to assess radiographic images. Subjects were 191 RA patients (22 men and 169 women; mean age 57.0 years) who were examined at our center between 2001 and 2003 and underwent plain X-ray of both wrist joints (n = 382). Using X-ray images of the wrist joint, classification was performed based on the severity of wrist joint surface bone erosion and joint space narrowing at different zones, and the results were statistically analyzed. The results showed that joint space narrowing in the midcarpal joint (MCJ) advanced faster than in the radiocarpal joint (RCJ). Conversely, bone erosion in the RCJ advanced faster than in the MCJ. In X-ray diagnosis of RA wrist joint disorders, knowing the pattern of destruction is useful for assessing the presence or absence of early joint destruction and in planning therapy.

The stabilizing effect of the distal interosseous membrane on the distal radioulnar joint in an ulnar shortening procedure: a biomechanical study.

BACKGROUND: The importance of the stabilizing effect of the distal interosseous membrane on the distal radioulnar joint, especially in patients with a distal oblique bundle, has been described. The purpose of this study was to evaluate the stability of the distal radioulnar joint after an ulnar shortening osteotomy and to quantify longitudinal resistance to ulnar shortening when the osteotomy was proximal or distal to the ulnar attachment of the distal interosseous membrane. These relationships were characterized for forearms with or without a distal oblique bundle. METHODS: Ten fresh-frozen cadavers were used. A transverse osteotomy and ulnar shortening was performed proximal (proximal shortening) and distal (distal shortening) to the ulnar attachment of the distal interosseous membrane. Distal radioulnar joint laxity was evaluated as the volar and dorsal displacements of the radius relative to the fixed ulna with 20 N of applied force. Testing was performed under controlled 1-mm increments of ulnar shortening up to 4 mm, with the forearm in neutral alignment, 60° of pronation, and 60° of supination. Resistance to ulnar shortening was quantified as the slope of the load-displacement curve obtained by displacing the distal ulnar segment proximally. RESULTS: In proximal shortening, significantly greater stability of the distal radioulnar joint was obtained with even 1 mm of shortening compared with the control, whereas distal shortening demonstrated significant improvement in stability of the distal radioulnar joint only after shortening of ≥4 mm in all rotational positions. Significantly greater stability of the distal radioulnar joint was achieved with proximal shortening than with distal shortening and in specimens with a distal oblique bundle than in those without a distal oblique bundle. The longitudinal resistance to ulnar shortening was significantly greater in proximal shortening than in distal shortening. The stiffness in proximal shortening was not affected by the presence of a distal oblique bundle in the distal interosseous membrane. CONCLUSIONS: Ulnar shortening with the osteotomy carried out proximal to the attachment of the distal interosseous membrane had a more favorable effect on stability of the distal radioulnar joint compared with distal osteotomy, especially in the presence of a distal oblique bundle.

Three-dimensional kinematics of the rheumatoid wrist after partial arthrodesis.

BACKGROUND: Partial arthrodesis of the wrist, such as radiolunate and radioscapholunate arthrodesis, is intuitively more appealing for the treatment of the rheumatoid wrist than total arthrodesis is because it preserves some motion. However, wrist kinematics after partial arthrodesis are incompletely understood. The purpose of the present study was to evaluate the kinematics of the radiocarpal and midcarpal joints of rheumatoid wrists with use of three-dimensional computed tomography before and after partial arthrodesis. METHODS: We selected ten wrists that were affected by rheumatoid arthritis in which the radiolunate joint was severely damaged but the midcarpal joint congruities were relatively well preserved. Six radiolunate and four radioscapholunate arthrodeses were then performed, with preservation of the joint congruity between the scaphoid, lunate, and capitate. We acquired in vivo three-dimensional kinematic data during wrist flexion-extension preoperatively and postoperatively with use of computed tomography and a markerless bone-registration technique. Postoperative midcarpal joint congruity and range of motion were compared with preoperative values. RESULTS: The mean range of global wrist motion was 48 degrees +/- 21 degrees after radiolunate arthrodesis and 47 degrees +/- 14 degrees after radioscapholunate arthrodesis. Midcarpal joint congruities and motion between the scaphoid, lunate, and capitate were well preserved in all ten wrists. The postoperative range of capitate motion relative to the lunate was 109% of the preoperative value after radiolunate arthrodesis and 88% after radioscapholunate arthrodesis. The directions of capitate motion relative to the lunate after both types of partial arthrodesis were significantly more oblique than before the arthrodeses, changing from radiodorsal to ulnopalmar along the so-called dart-throwing motion plane (p < 0.05). CONCLUSIONS: The results of this kinematic analysis, which showed that midcarpal motion occurred in the dart-throwing motion plane, may support the use of radiolunate and radioscapholunate arthrodeses as an alternative to total wrist arthrodesis in patients with symptomatic rheumatoid arthritis of the wrist.

Analysis of radiocarpal and midcarpal motion in stable and unstable rheumatoid wrists using 3-dimensional computed tomography.

PURPOSE: The kinematic evaluation of carpal motion, especially midcarpal motion, in rheumatoid arthritis (RA) has been extremely difficult because of limited imaging techniques previously available. The purpose of this study was to evaluate the amount of radiocarpal and midcarpal motion in the flexion-extension plane in both stable and unstable rheumatoid wrists using three-dimensional computed tomography. METHODS: We acquired in vivo kinematic data on 30 wrists with RA by three-dimensional computed tomography with the wrist in 3 positions: neutral, maximum flexion, and maximum extension. All cases were radiographically classified into 1 of 2 subtypes, the stable form or unstable form, according to the classification by Flury et al. We evaluated the precise range of radiocarpal and midcarpal motion using a markerless bone registration technique and calculated the individual contributions to the total amount of wrist motion in the flexion-extension plane in the different radiographic subtypes of RA. RESULTS: The average range of motion of radiocarpal and midcarpal joint was 27 degrees +/-15 and 32 degrees +/-17, respectively. The average contribution of midcarpal motion to the total amount of wrist motion was 54%. The average contribution of midcarpal motion in the unstable form was 67%, which was significantly higher than 47% (p< .05) in the stable form. CONCLUSIONS: Midcarpal motion of rheumatoid wrists in the flexion-extension plane was better preserved than previously thought. The contribution of midcarpal motion to the total amount of wrist motion was significantly greater (p< .05) in the unstable form than in the stable form of RA.