Radial-ulnar Deviation Research Articles

Wrist Kinematic Coupling and Performance During Functional Tasks: Effects of Constrained Motion

To quantify the coupled motion of the wrist during selected functional tasks and to determine the effects of constraining this coupled motion using a radial-ulnar deviation blocking splint on performance of these tasks. Ten healthy, right-handed men performed 15 trials during selected functional tasks with and without a splint, blocking radial and ulnar deviation. The following tasks were performed: dart throwing, hammering, basketball free-throw, overhand baseball and football throwing, clubbing, and pouring. Kinematic coupling parameters (coupling, kinematic path length, flexion-extension range of motion, radial-ulnar deviation range of motion, flexion-extension offset, and radial-ulnar deviation offset) and performance were determined for each functional task. A generalized estimation equation model was used to determine whether each kinematic coupling parameter was significantly different across tasks. A repeated-measures generalized estimation equation model was used to test for differences in performance and kinematic coupling parameters between the free and splinted conditions. Wrist motion exhibited linear coupling between flexion-extension and radial-ulnar deviation, demonstrated by R(2) values from 0.70 to 0.99. Average wrist coupling and kinematic path lengths were significantly different among tasks. Coupling means and kinematic path lengths were different between free and splinted conditions across all tasks other than pouring. Performance was different between wrist conditions for dart throwing, hammering, basketball shooting, and pouring. Wrist kinematic coupling parameters are task specific in healthy individuals. Functional performance is decreased when wrist coupling is constrained by an external splint. Surgical procedures that restrict wrist coupling may have a detrimental effect on functional performance as defined in the study. Patients may benefit from surgical reconstructive procedures and wrist rehabilitation protocols designed to restore kinematic coupling.

RSL Fusion with Excision of Distal Scaphoid and Triquetrum: A Cadaveric Study

Radioscapholunate (RSL) fusion has been utilized for treatment of radiocarpal arthritis for patients with an intact midcarpal joint. This preserves midcarpal joint motion while alleviating pain. Dart thrower's motion (DTM), which has been emphasized recently, is mainly a midcarpal joint motion. Question A cadaveric study was designed to measure and compare the range of motion (ROM) of the human wrist before and after an RSL fusion, followed by distal scaphoid excision, and finally excision of the triquetrum. Methods Twelve embalmed adult cadaveric upper limbs were assessed. The wrist motion was measured with an electrogoniometer. Measurements of the flexion-extension plane and radial-ulnar deviation plane were obtained for baseline after capsulotomy, after simulated RSL fusion with memory staples, after distal scaphoidectomy, and after excision of the triquetrum. Results The effects of scaphoid and triquetrum excision were expressed as improvements in movement over that of the preceding step. RSL fusion alone resulted in a decrease of the flexion-extension (F-E) arc by 36% and the radioulnar deviation (R-U) arc by 30%. Excision of the distal scaphoid with RSL improved the F-E arc by 34% and the R-U arc by 34%. With excision of the triquetrum, the F-E arc improved further by 13% and the R-U arc by 21%. The ROM of the simulated RSL fusion with distal scaphoidectomy is improved with excising the triquetrum, mainly through an increase in ulnar deviation motion. RSL fusion with distal scaphoidectomy and triquetrectomy can be an alternative to total wrist arthrodesis for patients with an intact midcarpal joint.

Does movement variability increase or decrease when a simple wrist task is performed during acute wrist extensor muscle pain?

The goal of complex tasks can be maintained despite variability in the movements of the multiple body segments involved in the task (VAR(elements)). This variability increases in acute pain and may enable the nervous system to search for less painful/injurious movement options. It is unclear whether VAR(elements) increases when pain challenges simple tasks with fewer movement options, yet maintain successful attainment of the goal. We hypothesised that during acute pain related to a simple movement: (1) the task goal would be maintained; (2) VAR(elements) would be increased; and (3) if VAR(elements) increased during pain, it would decrease over time. Movements of the right wrist/forearm were recorded with a three-dimensional motion analysis system and during a repetitive radial-ulnar deviation task between two target angle ranges (the task goal). We measured success of attaining the goal (repetitions that reached the target range and total absolute error in degrees), and variability in the motion of wrist flexion-extension and forearm pronation-supination (VAR(elements)). Fourteen healthy participants performed the task in one session before, during, and after wrist extensor muscle pain induced with hypertonic saline, and in another session without pain. The task goal was maintained during acute pain. However, VAR(elements) in other motion planes either reduced (pronation-supination) or did not change (flexion-extension). Thus, variability of task elements is constrained, rather than increased, in simple tasks. These data suggest the nervous system adapts simple tasks with limited degrees of freedom by reduction of VAR(elements) rather than the increase observed for more complex tasks.

OUTCOMES OF FOUR-CORNER ARTHRODESIS USING THE HUBCAPTM CIRCULAR PLATE

We present results of four-corner carpal arthrodesis with the Acumed Hubcap circular plate performed at our unit. Eight patients underwent eight procedures over five years, for scapholunate advanced collapse (five wrists) and scaphoid non-union advanced collapse (three wrists). Outcomes included range of motion, quickDASH scores, and visual analogue scores for satisfaction. At final follow-up, mean flexion-extension arc was 56°, mean radial-ulnar deviation 29° and mean quickDASH score was 23/100. Mean score for satisfaction was 7.7/10 (77%). Seven out of eight (87.5%) patients said they would have it done again, and would also recommend it to others. Radiological union was achieved in all cases. One screw broke in one arthrodesis without causing symptoms. The functional outcomes with our use of the Hubcap are comparable to those reported in literature to date with other circular plates (e.g. Spider plate). There were no non-unions, which is the main reported complication with these plates.

The passive stiffness of the wrist and forearm

Because wrist rotation dynamics are dominated by stiffness (Charles SK, Hogan N. J Biomech 44: 614-621, 2011), understanding how humans plan and execute coordinated wrist rotations requires knowledge of the stiffness characteristics of the wrist joint. In the past, the passive stiffness of the wrist joint has been measured in 1 degree of freedom (DOF). Although these 1-DOF measurements inform us of the dynamics the neuromuscular system must overcome to rotate the wrist in pure flexion-extension (FE) or pure radial-ulnar deviation (RUD), the wrist rarely rotates in pure FE or RUD. Instead, understanding natural wrist rotations requires knowledge of wrist stiffness in combinations of FE and RUD. The purpose of this report is to present measurements of passive wrist stiffness throughout the space spanned by FE and RUD. Using a rehabilitation robot designed for the wrist and forearm, we measured the passive stiffness of the wrist joint in 10 subjects in FE, RUD, and combinations. For comparison, we measured the passive stiffness of the forearm (in pronation-supination), as well. Our measurements in pure FE and RUD agreed well with previous 1-DOF measurements. We have linearized the 2-DOF stiffness measurements and present them in the form of stiffness ellipses and as stiffness matrices useful for modeling wrist rotation dynamics. We found that passive wrist stiffness was anisotropic, with greater stiffness in RUD than in FE. We also found that passive wrist stiffness did not align with the anatomical axes of the wrist; the major and minor axes of the stiffness ellipse were rotated with respect to the FE and RUD axes by ∼20°. The direction of least stiffness was between ulnar flexion and radial extension, a direction used in many natural movements (known as the "dart-thrower's motion"), suggesting that the nervous system may take advantage of the direction of least stiffness for common wrist rotations.

The Effects of Pain, Supination, and Grip Strength on Patient-Rated Disability After Operatively Treated Distal Radius Fractures

The correlation between physician-observed parameters and patient-rated disability in distal radius fractures is complex and poorly understood. Anecdotal clinical experience suggests that supination is an important factor in the return of functional status after distal radius fracture. To explore this relationship, we conducted a retrospective multivariate linear regression analysis of an existing patient database to evaluate the hypothesis that range of motion and other objective parameters are important determinants of patient-rated disability. We analyzed a prospectively gathered registry of patients undergoing operative fixation of distal radius fractures using physical examination parameters measured at each follow-up visit and patient-based outcomes including Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire and visual analog scale for pain. We constructed a multivariate linear regression model to evaluate the association of range of motion, grip strength, and visual analog scale score with the DASH score. We analyzed data from 190 patients and 611 total clinic visits. Pain, grip strength, and supination were significantly correlated with DASH scores, controlling for all other factors. These 3 variables were able to predict 56% of the variability of the DASH score. Flexion-extension, radial-ulnar deviation, and pronation had no significant correlation to DASH score. Pain, strength, and supination appear to be important determinants of patient-rated outcomes after distal radius fracture. Pain and strength continuously improve over time up to 2 years after surgery, whereas supination plateaus more quickly, usually within the first 3 to 6 months. Diagnostic II.

Stiffness, not inertial coupling, determines path curvature of wrist motions

When humans rotate their wrist in flexion-extension, radial-ulnar deviation, and combinations, the resulting paths (like the path of a laser pointer on a screen) exhibit a distinctive pattern of curvature. In this report we show that the passive stiffness of the wrist is sufficient to account for this pattern. Simulating the dynamics of wrist rotations using a demonstrably realistic model under a variety of conditions, we show that wrist stiffness can explain all characteristics of the observed pattern of curvature. We also provide evidence against other possible causes. We further demonstrate that the phenomenon is robust against variations in human wrist parameters (inertia, damping, and stiffness) and choice of model inputs. Our findings explain two previously observed phenomena: why faster wrist rotations exhibit more curvature and why path curvature rotates with pronation-supination of the forearm. Our results imply that, as in reaching, path straightness is a goal in the planning and control of wrist rotations. This requires humans to predict and compensate for wrist dynamics, but, unlike reaching, nonlinear inertial coupling (e.g., Coriolis acceleration) is insignificant. The dominant term to be compensated is wrist stiffness.

Effect of the Position of Ulnar Three Digits on Thumb to Index Tip to Tip Pinch Strength

their dominant wrist performed 15 trials of dart throwing and hammering. Data was acquired at 200 Hzwith a motion capture system. Awrist joint coordinate system was implemented to calculate angles. Performance for dart throwing was measured as distance to the target’s center (mm). Hammering performance was measured as: time takenper nail (sec), total strikes, and percentage of missed strikes. Coupling, was the angle with respect to the positive horizontal axis using arctangent2(y,x). For example, 2458 indicates 1:1 flexion:ulnar-deviat ionand290 indicates isolated flexion. Kinematic Path Lengthwas defined as the total angular distance traveled along the kinematic path for each task. Active range of motion (ROM) and grip strength for the dominant hand and Patient Rated Wrist Evaluat ion (PRWE) scores were compared bet ween groups. One-way ANOVA (a 5 0.05)withLSDpost-hoc testswas used to test differences. Significance was a , 0.016 for post-hoc tests. Results: Flexion-extension (FE) ROM, radial-ulnar deviation (RUD) ROM, grip strength and PRWE scores were worse for MA and PRC groups comparedtohealthy.Clinicalmeasures were not different between MA and PRC. Coupling, kinematic path length and performance were reduced for both MA and PRC groups compared to healthy for dart throwing, however no differences existed between the 2 surgical groups. Kinematic path length was significantly reduced forMAcompared to PRCandhealthy.Hammering performance (time taken and total strikes per nail) was worse in MA compared to PRC and healthy. PRC group showed reduced coupling compared to bothMAandhealthy andwas significantly less than the coupling for healthy subjects. Conclusion: PRC individuals demonstrated improved performance and greater wrist motion compared toMA during hammering. Preserved motion at the midcarpal joint in PRC may be responsible for improved hammering performance. Altered wrist kinematics and functional performance were found after MA and PRC. A better understanding of functional outcomes following wrist reconstruction has implications for patient consent, surgical technique selection, implant design and postoperative rehabilitation. EFFECT OF THE POSITION OF ULNAR THREE DIGITS ON THUMB TO INDEX TIP TO TIP PINCH STRENGTH

Dynamic CT technique for assessment of wrist joint instabilities

To develop a 4D [three-dimensional (3D) + time] CT technique to capture high spatial and temporal resolution images of wrist joint motion so that dynamic joint instabilities can be detected before the development of static joint instability and onset of osteoarthritis (OA). A cadaveric wrist was mounted onto a custom motion simulator and scanned with a dual source CT scanner during radial-ulnar deviation. A dynamic 4D CT technique was utilized to reconstruct images at 20 equidistant time points from one motion cycle. 3D images of carpal bones were generated using volume rendering techniques (VRT) at each of the 20 time points and then 4D movies were generated to depict the dynamic joint motion. The same cadaveric wrist was also scanned after cutting all portions of the scapholunate interosseus ligament to simulate scapholunate joint instability. Image quality were assessed on an ordinal scale (1-4, 4 being excellent) by three experienced orthopedic surgeons (specialized in hand surgery) by scoring 2D axial images. Dynamic instability was evaluated by the same surgeons by comparing the two 4D movies of joint motion. Finally, dose reduction was investigated using the cadaveric wrist by scanning at different dose levels to determine the lowest radiation dose that did not substantially alter diagnostic image quality. The mean image quality scores for dynamic and static CT images were 3.7 and 4.0, respectively. The carpal bones, distal radius and ulna, and joint spaces were clearly delineated in the 3D VRT images, without motion blurring or banding artifacts, at all time points during the motion cycle. Appropriate viewing angles could be interactively selected to view any articulating structure using different 3D processing techniques. The motion of each carpal bone and the relative motion among the carpal bones were easily observed in the 4D movies. Joint instability was correctly and easily detected in the scan performed after the ligament was cut by observing the relative motion between the scaphoid and lunate bones. Diagnostic capability was not sacrificed with a volume CT dose index (CTDI(vol)) as low as 18 mGy for the whole scan, with estimated skin dose of approximately 33 mGy, which is much lower than the threshold for transient skin erythema (2000 mGy). The proposed dynamic 4D CT imaging technique generated high spatial and high temporal resolution images without requiring periodic joint motion. Preliminary results from this cadaveric study demonstrate the feasibility of detecting joint instability using this technique.

Chronic scapholunate instability treated by scaphocapitate fusion: A midterm outcome perspective

Chronic scapholunate instability can lead to functional deficits and radiocarpal osteoarthritis. A number of procedures, namely scapho-trapezio-trapezoid (STT) fusion, scaphocapitate (SC) fusion or soft tissue reconstruction procedures, aim to improve function while protecting the wrist from osteoarthritis. Define the role of scaphocapitate fusion in comparison to STT fusion and capsulodesis and ligament reconstruction. A clinical, radiographic and functional evaluation was performed on 31 SC fusion cases with an average follow-up of 5 years. Range of motion was 41° in flexion and 39° in extension. Radial-ulnar deviation was 43°. Strength was 32.5 kgf (Jamar). The DASH was 27% and the PRWE was 25%. Fifty percent of the wrists were pain-free at rest. Ninety-four percent of patients were satisfied with the procedure. Seventy-eight percent of patients had returned to their occupation. Radiographic analysis revealed that consolidation was obtained at 10.1weeks. The postoperative radioscaphoid angle was 55° with good radioscaphoid congruence. There was no osteoarthritis in the radioscaphoid joint in 84% of the cases. The non-union rate was 13%. These data are similar to the few series that exist. STT fusion leads the same clinical results, but it is technically more difficult and has a higher rate of complications. Capsulodesis and ligament reconstruction provide the same functional results as SC fusion, but with slightly less stiffening. However, these techniques do not seem to protect the wrist from arthritic degeneration at longer follow-up. SC fusion is superior to STT fusion for the treatment of chronic scapholunate instability. This is a pain-relieving intervention with good clinical results and preservation of scaphoid stability. As a component of the surgeon's armamentarium, it can be held in the same regard as capsulodesis and ligament reconstruction for cases of chronic scapholunate instability with a non-reducible scaphoid, or after failure of a soft tissue reconstruction procedure. Level 4, retrospective study.

The effect of lunate position on range of motion after a four-corner arthrodesis: A biomechanical simulation study

A four-corner arthrodesis of the wrist is a salvage procedure for the treatment of specific wrist disorders, to achieve a movable, stable and pain free joint. However, a partial arthrodesis limits the postoperative range of motion (ROM). The goal of this study is to understand the mechanism of the reduction of the ROM and to evaluate the effect of the orientation of the lunate in the four-corner arthrodesis on the range of motion by using a biomechanical model, containing articular contacts and ligaments. Multi-body models of a normal wrist and a four-corner arthrodesis wrist with different orientation of the lunate were used for simulations of flexion–extension motion (FEM) and radial–ulnar deviation motion (RUD). The ROM of the postoperative wrist was reduced from 145° to 82° of the total arc of FEM and from 73° to 41.5° of the total arc of RUD. The model simulations show that the range of motion reduction is caused by overtension of the extrinsic wrist ligaments. Different positioning of the lunate changes the balance between the contact forces and ligament forces in the wrist. This explains the effect on the postoperative range of motion. The 20° flexed lunate did not give any gain in the extension motion of the wrist, caused joint luxation in flexion and limitation in RUD. The 30° extended lunate caused overtension of the extrinsic ligaments attached to the lunate. The ROM in this case is dramatically reduced. The model simulations suggest that the neutral position of the lunate seems to be most favorable for mobility of the wrist after a four-corner arthrodesis procedure.

Upper limb kinematics: Development and reliability of a clinical protocol for children

This study proposed a child-friendly measurement procedure for the three-dimensional analysis of upper limb movements, based on a comprehensive movement protocol. Within and between session reliability was tested in a group of 10 typically developing children (TDC) (mean age 10.3±3.2years). The movement protocol was constructed for children with hemiplegic cerebral palsy (HCP) and contained three reach tasks (forwards, upwards, sideways), three reach-to-grasp tasks (with objects requiring different hand orientations) and three gross motor tasks. Upper limb kinematics were calculated following the ISB-guidelines. Reliability of movement duration/speed and endpoint joint angles was assessed with the intraclass correlation coefficient; similarity of the waveforms with the coefficient of multiple correlation; measurement errors were also calculated.Reliability coefficients were generally high for movement duration/speed and most kinematic parameters. Endpoint angles for scapular tilting, shoulder elevation plane and elevation, elbow flexion-extension and wrist ulnar-radial deviation showed highest reliability. Angular waveforms were best repeated for scapular medio-lateral rotation and pro-retraction, shoulder elevation plane and elevation, and elbow flexion-extension. Results also seemed task-dependent.This study indicated that the proposed procedure could be used reliably to quantify upper limb movements in TDC. However, to compose proper age-related standards for the different tasks, larger study samples are needed. This will also help with a well-founded task-selection depending on the joints of interest. Finally, further research will need to establish the reliability in children with HCP.

Dynamics of wrist rotations

Understanding the dynamics of wrist rotations is important for many fields, including biomechanics, rehabilitation and motor neuroscience. This paper provides an experimentally based mathematical model of wrist rotation dynamics in Flexion–Extension (FE) and Radial–Ulnar Deviation (RUD), and characterizes the torques required to overcome the passive mechanical impedance of wrist rotations.We modeled the wrist as a universal joint with non-intersecting axes. The equations of motion of the hand rotating about the wrist joint include inertial, damping, and stiffness terms, with parameter values based on direct measurements (stiffness) or measurements combined with data available in the literature (inertia, damping). We measured the wrist kinematics of six young, healthy subjects making comfortable and fast-paced wrist rotations (±15° in FE, RUD, and combinations) and inserted these kinematic data into the model of wrist rotation dynamics. With this we quantified the torques required to overcome the impedance of wrist rotations and evaluated the relative importance of individual impedance terms as well as interactions between the degrees of freedom.We found that the wrist’s passive stiffness is the major impedance the neuromuscular system must overcome to rotate the wrist. Inertia and passive damping only become important for very fast movements. Unlike elbow and shoulder reaching movements, inertial interaction torques are negligible for wrist rotations. Interaction torques due to stiffness and damping, however, are significant. Finally, we found that some model terms (inertial interaction torques, axis offset, and, for moderately sized rotations, non-linearities) can be neglected with little loss of accuracy, resulting in a simple, linear model useful for studies in biomechanics, motor neuroscience, and rehabilitation.

Erste Ergebnisse der multidirektional-winkelstabilen palmaren Osteosynthese der distalen Radiusfraktur

The management of fractures of the distal radius continues to evolve. New operative strategies have recently been developed including the use of fixed-angle plates. This study reviews the results of 20 patients with fractures of the distal radius treated with a new multidirectional fixed angle plate. A total of 20 patients with closed Colles type fractures of the distal radius were treated with Medartis (Aptus 2.5) palmar fixed-angle plates. Surgery was performed under plexus anesthesia using the standard or extended flexor carpi radialis (FCR) approach. Patients were evaluated prospectively with a mean follow-up of 26 weeks (range 23-28 weeks). Pain, range of motion, grip strength, DASH score, modified Mayo wrist score and radiographs were obtained. The level of significance was set at 95% and the χ(2) and ANOVA tests in combination with a post hoc Tukey test were used for statistical analysis. The average range of motion (ROM) in extension-flexion was 87° (76% of the contralateral side) and in ulnar-radial deviation 42° (88% of the contralateral side). Pain values (visual analogue scale 0-100) at follow-up were 3 (without stress) and 24 (with stress). Grip strength improved to 84% of the contralateral side, the mean DASH score was 13 points and the modified Mayo wrist score confirmed the excellent results with a mean value of 83±27 points. Radiological examination showed a satisfactory result with an ulna variance of 0.9±0.4 mm, radio-ulnar inclination of 21±5° and palmar inclination of 4±6°. Our data show that treating unstable distal radius fractures with multidirectional palmar fixed-angle plates is reliable and effective and produces good early functional and radiological results. However, long-term results with a larger number of patients and randomized prospective studies comparing this technique with other established procedures are required.

Freies gefäßgestieltes Beckenkamm-Transplantat bei aseptischer Mondbeinnekrose im Stadium III

The aim of this retrospective study is to report the clinical and radiological long-term results (follow-up >10 years) after revascularisation of the lunate in Kienböck's disease using a free vascularised iliac bone graft in patients with Lichtman stage III disease. 23 patients (14 male, 9 female) aged between 17 and 43 years were treated with a free vascularised iliac bone graft. The average follow-up time was 13 (10-15) years. Assessment included active range of wrist motion, grip strength, level of pain, patient disability and functional outcome measured by the DASH questionnaire as well as the Green and O'Brien score. Radiological evaluation included Ståhl index, Youm carpal height index, radioscaphoidal angle, radiolunate angle and integration of the free vascularised bone graft. All long-term results were compared to the preoperative state. In 20 of 23 patients definite osteointegration of the vascularised bone graft was achieved. The average extension-flexion arc increased from 75 degrees to 100 degrees postoperatively and the average ulnar-radial deviation arc increased from 35 degrees to 45 degrees . The grip strength improved from 45 kg to 65 kg postoperatively and the pain level decreased from 65 to 6. Radiologically the average Ståhl index improved to 0.44 (preoperative 0.33), the average Youm index to 0.54 (preoperative 0.51) and the average radioscaphoidal angle to 50 degrees (preoperative 46 degrees ). The mean DASH score was 14.2. The Green and O'Brien score showed 11 (48%) excellent, 5 (22%) good, 4 (17%) fair und 3 (13%) bad results. 3 patients presented with a resorption of the bone graft with ongoing radiological progression of Lichtman stage, reduced range of motion and high pain level. Free vascularised iliac bone grafts for Kienböck's disease is a reasonable treatment option and the clinical and radiological improvements last for a long period of time. Long-term restoration of carpal height was demonstrated. Progression of disease was prevented in 87% (20 of 23) of patients over a mean time of 13 years. In our hands this technique remains the best option for the treatment of Kienböck's disease stage III.

Clinical Outcomes of Scaphoid and Triquetral Excision With Capitolunate Arthrodesis Versus Scaphoid Excision and Four-Corner Arthrodesis

To compare the clinical outcomes of scaphoid and triquetral excision combined with capitolunate arthrodesis versus 4-corner (capitate, hamate, lunate, triquetrum) intercarpal arthrodesis. We retrospectively identified 50 patients with scapholunate advanced collapse wrist changes who had 4-corner arthrodesis. Thirty-four patients were able to return and complete all follow-up evaluations. Patient demographics were similar between the 2 groups. Follow-up evaluation included radiographs, wrist range of motion (flexion-extension, radial-ulnar deviation, and pronation-supination); grip strength; visual analog scale (VAS); and Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Complications of nonunion, hardware migration, conversion to wrist arthrodesis or arthroplasty, and pisotriquetral arthritis were recorded. Sixteen patients had capitolunate arthrodesis, and 18 patients had a 4-corner arthrodesis. There was no statistical difference in radial-ulnar deviation, pronation-supination, grip strength, VAS, or DASH scores between groups. There was a slight increase in flexion-extension in the 4-corner group. There were 2 nonunions in the 4-corner group and none in the capitolunate group. Five patients in the capitolunate group required screw removal secondary to migration. Three patients in the 4-corner group required a subsequent pisiform excision. Capitolunate arthrodesis compares favorably to 4-corner arthrodesis at an average 3-year follow-up in this series with respect to range of motion, grip strength, DASH scores, and VAS. Advantages of capitolunate arthrodesis include a lessened need for bone graft harvesting while maintaining a similarly low nonunion rate, easier reduction of the lunate following triquetral excision, and avoiding subsequent symptomatic pisotriquetral arthritis. Screw migration, however, remains a concern with this technique. Therapeutic III.

The effect of triangular fibrocartilage complex injury on extensor carpi ulnaris function and friction

Background It has been previously shown that injury to the triangular fibrocartilage complex increases the moment arm of the extensor carpi ulnaris. This will reduce the force producing capacity of the muscle in some situations, but will also increase its mechanical advantage. It is also possible that the change in the tendon path may increase tendon friction, predisposing the patient to future repetitive motion injury. It is the purpose of this study to determine the effects of triangular fibrocartilage complex injury on extensor carpi ulnaris moment producing capacity and tendon friction. Methods A simple simulation was used to examine muscle moment producing capacity throughout the range of motion, at varying speeds and in both injured and healthy states. Six fresh frozen human cadaveric wrists were used to determine the effect of injury on tendon friction. A custom made device was used to move the wrists through a range of motion, while a constant force was applied to the proximal tendon and force was recorded at the distal tendon. Friction was measured before and after the creation of injury. Findings The decreases in muscle force following injury were small, even in the worse case. The moment producing capacity of the muscle was increased following injury. Tendon friction during flexion–extension was decreased following injury. The friction during radial-ulnar deviation was unchanged. Interpretation When making surgical decisions about triangular fibrocartilage complex repair, it is not necessary to consider extensor carpi ulnaris moment producing capacity or tendon friction.

Long-term results of lunocapitate arthrodesis with scaphoid excision for SLAC and SNAC wrists

When treating the degenerative arthritis that follows scapholunate instability or scaphoid pseudarthrosis, excision of the scaphoid must be combined with a stabilisation of the midcarpal joint. Two alternatives have been proposed for that purpose: fusing the lunate, triquetrum, capitate and hamate (four corner fusion), 4CF; or limiting the arthrodesis to the lunate and capitate, preserving or excising the triquetrum. Previous reports have attributed a high level of complications to lunocapitate arthrodesis, mainly in respect of nonunion. We have reviewed 17 patients who had been treated with a lunocapitate fusion, after an 8 to 12-year follow-up period, and found similar results compared with 4CF, even with a major degree of motion in ulnar-radial deviation. Recent work on the innervation of the radiotriquetral ligaments has given relevance to the preservation of lunotriquetral motion in maintaining proprioception. Also if the triquetrum is excised to gain more motion, the proprioceptive role of the radiotriquetral ligaments is compromised.

The role of SLIL in 3D movement of scaphoid and lunate during wrist radio-ulnar deviation

Objective To observe the effects of transection of scapholunate interosseous ligament (SLIL)and its subregions on the 3D movement of scaphoid and lunate during wrist radio-ulnar deviation, and study the rule of SLIL subregions in 3D motion of the scaphoid and lunate. Methods Twelve fresh adult cadaver upper extremities (6 left side and 6 right side) were divided to normal control group, proximal SLIL subregion transection group, proximal and dorsal SLIL subregion transection group, proximal and palmar SLIL subregion transection group and entire SLIL transection group (6 each). 3D laser scanning and reconstruction techniques were applied to measure 3D motion of the scaphoid and lunate during wrist radio-ulnar deviation, and data were statistically analyzed, on the normal and sequential sectioning of SLIL subregions during wrist flexion-extension and wrist radlal-ulnar deviation were determined. Results In the intact wrist specimens, the scaphoid and lunate deviated radially and ulnarly during wrist radial-ulnar deviation, along with obvious flexion and extension.At the same time, there was minimal scaphoid and lunate pronation-supination. With sectioning of proximal subregions of the SLIL, no significant kinematics changes were observed in the scaphoid and lunate bones. After sectioning proximal and palmar or proximal and dorsal subregions of the SLIL, kinematics of the scaphoid and lunate were changed. Sectioning the whole SLIL caused increased volar flexion of the scaphoid and decreased volar flexion of the lunate. Conclusion 3D laser scanning and reconstruction can precisely measure 3D motion of the scaphoid and lunate. Kinematic study of SLIL subregions showed that partial or complete sectioning of SLIL led to obvious change in volar flexion of the scaphoid and lunate. However, the proximal subregion of SLIL has no prominent effect on the motion of scaphoid and lunate. Key words: Carpal joints; Scaphoid bone; Lunate bone; Ligaments,articular; 3D movement

Dynamic Biomechanical Evaluation of the Dorsal Intercarpal Ligament Repair for Scapholunate Instability

A variety of soft tissue surgical procedures have been developed for treatment of scapholunate dissociation. One reconstruction method, using the dorsal intercarpal ligament, has been used clinically with some success. The purpose of this study was to evaluate biomechanically use of the dorsal intercarpal ligament for static scapholunate dissociation. Eight cadaver wrists were tested in a wrist joint motion simulator. Each wrist was moved in continuous cycles of flexion-extension and radial-ulnar deviation. Kinematic data for the scaphoid and lunate were recorded for each wrist in the intact state, after the scapholunate interosseous, dorsal radiocarpal, and dorsal intercarpal ligaments were sectioned, and after reconstruction using the dorsal intercarpal ligament. Ligamentous sectioning resulted in static scapholunate dissociation. Visually, the repair initially reduced the gap between the scaphoid and lunate, but within a few cycles of wrist motion, there were statistically significant increases in scaphoid flexion, scaphoid ulnar deviation, and lunate extension. In 6 arms, gapping between the scaphoid and lunate was observed. In 2 arms, a gap occurred and the repair also pulled out of the bone junction. This study does not support the hypothesis that the dorsal intercarpal ligament repair alone will stabilize the scaphoid and lunate after scapholunate instability in the immediate postoperative period.