Radioulnar Deviation Research Articles

Dorsal scapholunate stabilization using Viegas’ capsulodesis: 25 cases with 26 months-follow-up

Intercarpal instability is often secondary to a scapholunate interosseous (SLIO) ligament lesion. Its reconstruction is thus essential. Classical capsulodesis techniques fix the scaphoid in extension and do not reproduce the physiologic ligamentous isometry of the wrist. The authors use the technique of Viegas, which seems to respect this isometry: the dorsal intercarpal ligament is re-inserted dorsally to reattach the capsule on the dorsal SLIO and to reinforce it. Between 2006 and 2010, 25 wrists were operated on in 12 men and 12 women of mean age 38years. All patients presented with pain often associated with loss of power, decreased mobility or a debilitating click. The mean follow-up was 26months. Postoperative and preoperative data were compared. Flexion/extension range increased by 2.6°, radioulnar deviation increased by 21.1°. Grip strength increased by 8.7kgf. Pain decreased by 3 points on the VAS and the PRWE improved by 59 points. We observed four CRPS, one EPL lesion and one case of superficial track pin infection. We got eleven excellent results, nine good, two moderate and three bad, two of which were re-operated. Viegas’ capsulodesis does not present major technical difficulty. The results show no stiffness in flexion/extension. There was evident improvement in radioulnar deviation, grip strength, pain and PRWE scores. This technique provides effective treatment for a difficult or irreparable lesion of the SLIO ligament, without fixed carpal instability corresponding to Geissler arthroscopic stages 2 to 4 and Garcia-Elias stages 3 and 4. The capsulodesis produces an effective stabilization without stiffness. Precautions should be undertaken to avoid CRPS and pin complications.

A quantitative, biomechanical analysis of radioulnar deviation between fresh frozen and soft embalmed human forearms

Fresh frozen human cadaveric specimens are considered the gold standard for biomechanical research; however, the testing period of these specimens is limited because they decay rapidly, can be difficult to obtain and can carry infectious diseases. Therefore, various chemical fixation methods to deal with these issues have been developed. Traditional formalin fixation has been shown to significantly affect the biomechanical properties of the tissues; however, a relatively new method called soft embalming could provide an alternative to fresh frozen specimens in the field of biomechanical research. The purpose of this pilot study was to determine the effects soft embalming has on gross anatomical movements. The parameters for testing were radioulnar deviation range of motion with in plane and out of plane angulation measured using an incremented tendon loading protocol. Five fresh frozen human cadaveric forearms were obtained and injected with tantalum tracer beads and tested pre and post embalming using 3D X‐rays. The results showed that the soft embalmed specimens retained their flexibility and was slightly greater than the fresh frozen state. Although, at lighter loading trials, the range of motion in soft embalmed specimens was larger than the fresh frozen state. The results here may provide an argument for the inclusion of soft embalmed specimens in biomechanical testing.

Scaphocapitate Arthrodesis for Treatment of Scapholunate Instability in Manual Workers

To assess the long-term efficacy of scaphocapitate arthrodesis for treatment of chronic scapholunate instability in high-demand patients. We retrospectively analyzed the clinical and radiographic results of 20 manual workers who underwent scaphocapitate arthrodesis for chronic scapholunate instability at a mean follow-up of 10 years (range, 1-23 y). We measured range of motion and grip strength; pain on a scale of 0 to 5; Quick Disabilities of the Arm, Shoulder, and Hand score; and ability to return to work. We assessed radiographs for union, carpal height and alignment, signs of ulnar translation or radiocarpal arthritis, and hardware problems. At most recent follow-up, the arc of motion averaged 87° for flexion-extension and 41° for the radioulnar deviation. The postoperative average maximum grip strength was 21 kg, which was 60% of the opposite, normal wrist. Pain was significantly reduced. The average postoperative Quick Disabilities of the Arm, Shoulder, and Hand score was 19, and the return-to-work rate was 90%. Radiographic analysis showed union in all patients, improvement of carpal height and scaphoid angle, no evidence of ulnar translation, and a 30% rate of radiocarpal osteoarthritis. This report of long-term results demonstrates the efficacy of scaphocapitate limited carpal arthrodesis for the treatment of chronic rotatory subluxation of the scaphoid. We conclude that continued use of this procedure is warranted. Therapeutic IV.

Four-Dimensional Real-Time Cine Images of Wrist Joint Kinematics Using Dual Source CT with Minimal Time Increment Scanning

PurposeTo validate the feasibility of real time kinematography with four-dimensional (4D) dynamic functional wrist joint imaging using dual source CT.Materials and MethodsTwo healthy volunteers performed radioulnar deviation and pronation-supination wrist motions for 10 s and 4 s per cycle in a dual source CT scanner. Scan and reconstruction protocols were set to optimize temporal resolution. Cine images of the reconstructed carpal bone of the moving wrist were recorded. The quality of the images and radiation dosage were evaluated.ResultsThe 4D cine images obtained during 4 s and 10 s of radioulnar motion showed a smooth stream of movement with good quality and little noise or artifact. Images from the pronation-supination motion showed noise with a masked surface contour. The temporal resolution was optimized at 0.28 s.ConclusionUsing dual source CT, 4D cine images of in vivo kinematics of wrist joint movement were obtained and found to have a shorter scan time, improved temporal resolution and lower radiation dosages compared with those previously reported.

Wrist Tendon Forces With Respect to Forearm Rotation

Early motion therapy protocols are desirable to reduce wrist stiffness after carpal injuries and distal radius fractures. Based on our assumption that a reduction in wrist tendon forces will be associated with a reduction in radioulnar carpal joint reaction force, the goal of this study was to determine the forearm position at which the wrist tendon forces required to initiate wrist motion were the least. We tested 8 fresh-frozen cadaver forearms in a wrist and forearm motion simulator. In each specimen, we generated a wrist flexion-extension motion and a radioulnar deviation motion by pulling on the wrist flexor and extensor tendons with the forearm in supination, pronation, or neutral. We also performed a wrist flexion-extension motion during active forearm rotation. During each motion, we continuously recorded the forces in the 5 wrist tendons. We used repeated-measure analyses of variance to compare tendon forces. During the wrist flexion-extension motion, the summed peak wrist extensor forces were significantly less with the wrist in forearm supination than with the forearm in neutral or during active forearm rotation. For the summed peak wrist flexor forces, flexor tendon forces were significantly less with the forearm in supination compared with active forearm rotation. The extensor carpi radialis longus and flexor carpi ulnaris forces were significantly less in supination than during active forearm motion. During wrist radioulnar deviation motion, peak extensor carpi ulnaris force was significantly less with the forearm in supination than in neutral, and peak flexor carpi radialis force was significantly less with the forearm in supination than in pronation. Peak wrist tendon forces were least in the static forearm supinated position. To reduce deforming forces on a fresh carpal injury or distal radial fracture, active rehabilitation appears to be best initiated with the forearm held in supination.

Assessment of Velocity, Range, and Smoothness of Wrist Circumduction Using Flexible Electrogoniometry

To quantify the range, velocity, and smoothness of wrist circumduction, to explore the oblique functional plane of wrist circumduction, and to establish the reproducibility and reliability of these measures. Forty healthy subjects with a mean age of 43 years and without a history of wrist pathology or pain participated in this study. We used a flexible electrogoniometer with a twin-axis sensor to measure the relative angles between the 2 end blocks while the subject performed maximum excursion of flexion-extension, radioulnar deviation, and circumduction of the wrist held in a standardized, fully pronated position. A software package was used to further analyze the characteristics of the circumduction curve or oval such as the mean area (designated as degree-degree or oo) shape, size, rate, smoothness, and orientation. The mean area of circumduction (4729 [degree-degree]) and circumference (265°) of the circumduction curve indicated the total range of circumduction. The velocity of circumduction (mean 179°/s) and the time (1.6 second) taken to complete 1 cycle of circumduction were similar in both hands. The 4 quadrants for the velocity of circumduction showed that the velocity was faster in the radioulnar deviation quadrants compared with flexion and extension. Quadrant analysis showed the smoothness was greater in the radioulnar deviation quadrants than in the flexion and extension quadrants. The oblique planes of the circumduction curves of all the normal wrists lie in ulnopalmar and radiodorsal direction with a mean angle of 28° to the vertical flexion and extension plane. This technique was accurate and reliable in measuring the velocity, range, and smoothness of wrist circumduction.

Scaphocapitolunate Arthrodesis and Radial Styloidectomy for Posttraumatic Degenerative Wrist Disease

Long-standing scaphoid nonunion, scaphoid malunion, and chronic scapholunate dissociation result in malalignment of the carpal bones, progressive carpal collapse, instability, and osteoarthritis of the wrist. The most commonly used procedures to treat scaphoid nonunion advanced collapse (SNAC) and scapholunate advanced collapse (SLAC) wrists are the four-corner fusion (4CF) and the proximal row carpectomy (PRC). The purpose of this study was to evaluate the clinical outcome of a different treatment modality: radial styloidectomy and scaphocapitolunate (SCL) arthrodesis. This treatment option is chosen in an effort to maintain the joint contact surface and load transmission across the radiocarpal joint. We conducted a retrospective review of 20 patients (average age 62 years, range: 27 to 75 years) treated from 1994 to 2010. Seven patients were treated for SNAC, 12 patients for SLAC wrists, and 1 for degenerative joint disease following a transscapho-transcapitate perilunar dislocation. Sixteen patients had Herbert screw fixation, and four had Spider plate fixation. All patients had autologous bone graft used for the arthrodesis. The mean follow-up was 4.6 years (range: 2 to 9.6 years). Patients were evaluated clinically and radiographically. Nineteen of 20 arthrodeses healed on an average of 9.6 weeks. One patient was reoperated 8 months after the initial operation with salvage of the SCL arthrodesis with a spider plate with an adequate result. The mean active flexion-extension arc was 70 degrees and the radioulnar deviation arc was 23 degrees. Pain decreased in all patients, 13 of whom were pain free postoperatively. The average postoperative disabilities of arm, shoulder, and hand score was 24. Radiographically, neither radiolunate nor radioscaphoid arthritis was noted on follow-up. SCL arthrodesis with radial styloidectomy resulted in an adequate residual range of motion and pain relief. This method preserves the normal ulnar sided joints of the carpus and maintains a more physiologic joint surface for radiocarpal load sharing.

Static Progressive Orthosis for Patients with Limited Radial and/or Ulnar Deviation: An Innovative Orthotic Design

After injury to the wrist and forearm, therapists and patients frequently work to regain the motions of wrist flexion/extension and forearm pronation/supination. Although these motions play a vital role in everyday functioning, for some, limitations in wrist radial/ulnar deviation can also present functional challenges. These authors describe the creation and utilization of a static progressive orthosis to assist a patient in regaining wrist radioulnar deviation

Effectiveness of Four-Corner Arthrodesis with Use of a Locked Dorsal Circular Plate

Compared with traditional methods of fixation in four-corner arthrodesis, reviews of results using a dorsal circular plate (DCP) have identified higher complication rates. As the use of circular plate fixation for limited wrist arthrodesis was found to be a valuable concept per se and continued innovation and technical advancement are crucial to improve future treatment, changes in plate design were encouraged. To further evaluate the use of DCP fixation in four-corner arthrodesis, we report the first results using a radiolucent, nonmetallic (polyetheretherketone), locked DCP for four-corner arthrodesis. We retrospectively analyzed the clinical and radiographic results of 24 patients who underwent four-corner arthrodesis with a locked DCP at a minimum followup of 63months (mean, 76months; range, 63-91months). There were nine women and 15 men, with a mean age of 53years (range, 37-78years) at the time of surgery. We evaluated ROM with a goniometer and grip strength with a dynamometer. Function was assessed using QuickDASH. Radiographs were evaluated for union, carpal alignment, and hardware problems. At latest followup, ROM averaged 66% and 77% of the uninjured side in flexion-extension and radioulnar deviation, respectively. Grip strength averaged 70% of the uninjured side. The average postoperative QuickDASH score was 19.11. Union was achieved by 22 of the 24 patients. Our data show four-corner arthrodesis with a radiolucent, nonmetallic, locked DCP is an effective procedure that allows stable primary fixation as a basis for good functional outcome, provided surgical technique and quality of bone graft are adequate. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Scaphoid Excision and Midcarpal Arthrodesis: The Effect of Triquetral Excision—A Biomechanical Study

To evaluate the biomechanical alterations that occur after traditional scaphoid excision and midcarpal arthrodesis with and without excision of the triquetrum. The hypothesis of this study was that removal of the triquetrum increases the radiolunate contact pressure. We cyclically moved 10 fresh cadaver wrists using a wrist joint motion simulator while measuring the contact pressures between the proximal carpal row and the distal radius and ulna using a dynamic pressure sensor. We acquired data in the intact wrist, after a midcarpal arthrodesis with the scaphoid excised, and then again with the triquetrum removed, which is also known as a capitolunate arthrodesis. The peak pressures in the radiolunate fossa significantly increased with either of the midcarpal arthrodeses compared with the intact wrist during each of the 3 dynamic wrist motions. In comparing the 2 midcarpal arthrodeses, the peak pressure in the ulnocarpal fossa significantly decreased after the triquetrum was removed during wrist radioulnar deviation and in the static ulnarly deviated position. After arthrodesis, we could identify no differences during any motion or static wrist position in the peak radiolunate pressures with or without the triquetrum. We found that scaphoid excision and 4-corner arthrodesis shifts loads to the radiolunate joint. Isolated capitolunate arthrodesis with excision of the scaphoid and triquetrum further alters carpal kinematics and loading patterns. These findings raise concern about routine excision of the triquetrum when performing a midcarpal arthrodesis.

Free bone flap transplantation with descending genicular vessels for treatment of scaphoid nonunion

Objective To evaluate the effect of bone flap transplantation with descending genicular vessels for treatment of scaphoid nonunion.Methods From January 2007 to August 2009,6 cases of scaphoid nonunion were treated with free bone flap transplantation with descending genicular vessels.The results of the procedure were assessed in terms of osseous union,pain,grip strength and active motion of the wrist.Postoperatively treatment outcomes were evaluated by the Mayo modified wrist score system based on patients' perception of function,while vascularity of the scaphoid was evaluated by using color Doppler ultrasonography.Results Postoperative follow-up averaged 18 months.Scaphoid union occurred in all cases at an average of 12 weeks (range,11 to 16 weeks).The average pain score for these 6 patients was 1.0 points (range,0 to 2.2points) on the visual analog scale.The postoperative grip strength was 85％ of the contralateral side.The range of motion of the wrist was:flexion-extension ( 115 ± 10)°,radioulnar deviation (54 ± 14)°.An excellent outcome in the wrist function was found in 4 patients,a good outcome in 1 patient,fair in 1 patient.Vascularity of the scaphoid was good as confirmed by color Doppler ultrasonography. Conclusion Transplantation of bone flap with descending genicular vessels is an effective method for the treatment of scaphoid nonunion with avascular necrosis of the proximal fragment or with previously failed conventional bone grafting. Key words: Scaphoid bone; Fractures,ununited; Descending genicular vessels

Carpal kinematics in quadrupedal monkeys: towards a better understanding of wrist morphology and function.

The purpose of this study is to provide new data on carpal kinematics in primates in order to deepen our understanding of the relationships between wrist morphology and function. To that end, we provide preliminary data on carpal kinematics in seven species of quadrupedal monkeys that have not been previously investigated in this regard (cercopithecoids, n = 4; ceboids, n = 3). We radiographed wrists from cadavers at their maximum radial and ulnar deviations, as well as at maximum flexion and extension. We took angular measurements to quantify the contribution of the mobility of the two main wrist joints (antebrachiocarpal and midcarpal) with respect to total wrist mobility. We also recorded qualitative observations. Our quantitative results show few clear differences among quadrupedal monkeys for radioulnar deviation and flexion-extension: all the primates studied exhibit a greater midcarpal mobility (approximately 54-83% of the total range of motion) than antebrachiocarpal mobility; however, we identified two patterns of carpal kinematics that show the functional impact of previously recognised morphological variations in quadrupedal monkeys. Firstly, qualitative results show that the partition that divides the proximal joint of the wrist in ceboids results in less mobility and more stability of the ulnar part of the wrist than is seen in cercopithecoids. Secondly, we show that the olive baboon specimen (Papio anubis) is characterised by limited antebrachiocarpal mobility for extension; this effect is likely the result of a radial process that projects on the scaphoid notch, as well as an intraarticular meniscus. Because of these close relationships between carpal kinematics and morphology in quadrupedal monkeys, we hypothesise that, to some extent, these functional tendencies are related to their locomotor hand postures.

Effects of proximal row carpectomy on wrist biomechanics: A cadaveric study

Background Many studies show good clinical results after proximal row carpectomy. Some biomechanical consequences are documented, but to our knowledge muscle moment arm variations have not previously been quantified. Methods In five fresh–frozen wrist, kinematics and tendon excursions were measured using a 3D electrogoniometer and Linear Variable Differential Transformers (SOLARTRON Inc., AMETEK Advanced Measurement Technology, Inc, 801 South Illinois Avenue, Oak Ridge, TN 37831-2011, USA), respectively, in three conditions: intact wrist, after posterior capsulotomy and after proximal row carpectomy. Mean pivot point, defined as the point whose sum of the squared distances to the helical axes is minimum, wrist range of motion and mean moment arms were measured during dorso-palmar flexion, radioulnar deviation and circumduction movements. Findings No alteration of the range of motion was observed. On the other hand, the mean pivot point shifted proximally (6.8–9.1 mm) after proximal row carpectomy (p < 0.05) for all motions tested and most muscle moment arms decreased significantly after proximal row carpectomy. Interpretation The results of this study allow a better understanding of the biomechanical effects of this procedure. The important moment arm reduction and pivot point displacement suggest modifications of joint biomechanical parameters which could influence the functional outcome of PRC.

Scaphoid and Lunate Translation in the Intact Wrist and Following Ligament Resection: A Cadaver Study

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. 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. 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. 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.

Scaphoid and Lunate Movement in Different Ranges of Carpal Radioulnar Deviation

We aimed to investigate scaphoid and lunate movement in radial deviation and in slight and moderate ulnar deviation ranges in vivo. We obtained computed tomography scans of the right wrists from 20° radial deviation to 40° ulnar deviation in 20° increments in 6 volunteers. The 3-dimensional bony structures of the wrist, including the distal radius and ulna, were reconstructed with customized software. The changes in position of the scaphoid and lunate along flexion-extension motion (FEM), radioulnar deviation (RUD), and supination-pronation axes in 3 parts--radial deviation and slight and moderate ulnar deviation--of the carpal RUD were calculated and analyzed. During carpal RUD, scaphoid and lunate motion along 3 axes--FEM, RUD, and supination-pronation--were the greatest in the middle third of the measured RUD (from neutral position to 20° ulnar deviation) and the smallest in radial deviation. Scaphoid motion along the FEM, RUD, and supination-pronation axes in the middle third was about half that in the entire motion range. In the middle motion range, lunate movement along the FEM and RUD axes was also the greatest. During carpal RUD, the greatest scaphoid and lunate movement occurs in the middle of the arc--slight ulnar deviation--which the wrist frequently adopts to accomplish major hand actions. At radial deviation, scaphoid and lunate motion is the smallest.

MRI-identified abnormalities and wrist range of motion in asymptomatic versus symptomatic computer users

BackgroundPrevious work has shown an association between restricted wrist range of motion (ROM) and upper extremity musculoskeletal disorders in computer users. We compared the prevalence of MRI-identified wrist abnormalities and wrist ROM between asymptomatic and symptomatic computer users.MethodsMR images at 1.5 T of both wrists were obtained from 10 asymptomatic controls (8 F, 2 M) and 14 computer users (10 F, 4 M) with chronic wrist pain (10 bilateral; 4 right-side). Maximum wrist range of motion in flexion and radioulnar deviation was measured with an electrogoniometer.ResultsExtraosseous ganglia were identified in 66.6% of asymptomatic wrists and in 75% of symptomatic wrists. Intraosseous ganglia were identified in 45.8% of asymptomatic wrists and in 75% of symptomatic wrists, and were significantly (p < .05) larger in the symptomatic wrists. Distal ECU tendon instability was identified in 58.4% of both asymptomatic and symptomatic wrists. Dominant wrist flexion was significantly greater in the asymptomatic group (68.8 ± 6.7 deg.) compared to the symptomatic group (60.7 ± 7.3 deg.), p < .01. There was no significant correlation between wrist flexion and intraosseous ganglion burden (p = .09)ConclusionsThis appears to be the first MRI study of wrist abnormalities in computer users.This study demonstrates that a variety of wrist abnormalities are common in computer users and that only intraosseous ganglia prevalence and size differed between asymptomatic and symptomatic wrists. Flexion was restricted in the dominant wrist of the symptomatic group, but the correlation between wrist flexion and intraosseous ganglion burden did not reach significance. Flexion restriction may be an indicator of increased joint loading, and identifying the cause may help to guide preventive and therapeutic interventions.

Changes in lengths of the wrist ligaments during wrist radioulnar deviation: an in vivo study

Objective To investigate changes in lengths of the wrist ligaments during wrist radioulnar deviation. Methods Six volunteers were included in the study. CT scans was used to detect the changes under different positions of the wrist in the volunteers. The wrists were scanned from the position of radial deviation of 20° to the one of ulnar deviation of 40° at an interval of 20°. The 3-dimensional carpal and distal radioulnar joint structures were reconstructed with customized software and chauges in length of the palmar and dorsal wrist ligaments in radioulnar deviation were computed. Results From wrist radial deviation to neutral position, the lengths of the radioscaphocapitate ligament, the long radiolunate ligament and the dorsal intercarpal ligament increased significantly (P ＜ 0.05), they increased (2.4±0.3) mm, (2.3±0.8) mm,(1.2±0.6) mm, (1.2±1.2)mm and (2.6±1.0) mm respectively. While from wrist ulnar deviation to neutral position, ulnocapitate ligament and the dorsal radiocarpal ligament increased significantly (P ＜ 0.05), they increased (0.8 ±0.6) nm and (1.0±0.5) mm respectively. Conclusion At wrist radial deviation, the radioscaphocapitate, long radiolunate and dorsal intercarpal ligaments are slack. At wrist ulnar deviation, the ulnocapitate ligament and the dorsal radiocarpal ligament are slack. These positions may be favorable to healing of these ligaments. Key words: Wrist; Ligaments; Tomography, X-ray computed

Reliability of Distal Upper Extremity Posture Matching Using Slow-Motion and Frame-by-Frame Video Methods

The aim of this study was to determine the effects of video playback speed on posture matching reliability of the distal upper extremity. Video is frequently used in ergonomic assessments, yet there remains a need to determine the effects of viewing speed on posture observations. Participants were 7 graduate students experienced with posture-based observational methods. Categorical posture scales were used to evaluate forearm pronation/supination, wrist flexion/extension, wrist radioulnar deviation,and hand activity from workplace video at three playback speeds (quarter, half, and real time). Wrist flexion/extension was also evaluated with a frame-by-frame video method. Posture counts increased with slower viewing speeds for the wrist and hand, but percentage durations in each posture category were similar for all methods. Posture matching interrater reliability scores increased with slow-motion video playback but remained low even for quarter-time video playback. The highest interrater scores were found in the frame-by-frame analysis of wrist flexion/extension for three posture categories (percentage agreement = 84.9% +/- 1.3%; kappa = 0.54 +/- 0.02). Although slower video playback speeds increased the number of posture counts for the wrist and hand scales, percentage durations were similar, and reliability scores increased only slightly with slow-motion video playback. Reviewing video using slow-motion or frame-by-frame methods improves distal upper extremity posture matching reliability. However, ergonomic assessment tools based on percentage duration may not be appreciably enhanced by slowing viewing speed. Thus, the increased viewing time with slower playback should be justified with respect to assessment needs.

Wrist Tendon Forces During Various Dynamic Wrist Motions

A common treatment of arthritis of the thumb carpometacarpal joint requires all or a portion of the flexor carpi radialis tendon (FCR) to be used as an interpositional graft. The purpose of this study was to examine the in vitro tendon forces in 6 wrist flexors and extensors to determine whether their force contribution changes during various dynamic wrist motions along with a specific application to the FCR. We tested 62 fresh-frozen cadaver wrists in a wrist joint motion simulator. During wrist flexion-extension, radioulnar deviation, dart throwing, and circumduction motions, the peak and average tendon forces were determined for the extensor carpi ulnaris, extensor carpi radialis brevis and longus, abductor pollicis longus, flexor carpi radialis, and flexor carpi ulnaris. During a dart-throwing motion, the mean and peak FCR forces were statistically less than during the other 3 motions. Conversely, the mean and peak flexor carpi ulnaris forces were statistically greater during the dart-throwing motion than during the other 3 motions. Patients who have undergone a surgical procedure in which all or a portion of the FCR has been harvested may experience a decrease in wrist strength with wrist motion, as the FCR tendon normally applies force during wrist motion. The motion least likely to be affected by such surgery is the dart-throwing motion when the force on the remaining FCR is minimized.

The effect of tendon loading on in-vitro carpal kinematics of the wrist joint

Measurements of in-vitro carpal kinematics of the wrist provide valuable biomechanical data. Tendon loading is often applied during cadaver experiments to simulate natural stabilizing joint compression in the wrist joint. The purpose of this study was to investigate the effect of tendon loading on carpal kinematics in-vitro. A cyclic movement was imposed on 7 cadaveric forearms while the carpal kinematics were acquired by a 4-dimensional rotational X-ray imaging system. The extensor- and flexor tendons were loaded with constant force springs of 50 N, respectively. The measurements were repeated without a load on the tendons. The effect of loading on the kinematics was tested statistically by using a linear mixed model. During flexion and extension, the proximal carpal bones were more extended with tendon loading. The lunate was on the average 2.0° ( p=0.012) more extended. With tendon loading the distal carpal bones were more ulnary deviated at each angle of wrist motion. The capitate was on the average 2.4° ( p=0.004) more ulnary deviated. During radioulnar deviation, the proximal carpal bones were more radially deviated with the lunate 0.7° more into radial deviation with tendon loading ( p<0.001). Conversely, the bones of distal row were more flexed and supinated with the capitate 1.5° more into flexion ( p=0.025) and 1.0° more into supination ( p=0.011). In conclusion, the application of a constant load onto the flexor and extensor tendons in cadaver experiments has a small but statistically significant effect on the carpal kinematics during flexion–extension and radioulnar deviation.