PURPOSE OF THE STUDY The study aimed to propose an optimal based fl ap creation with the view to ensure long-term survival of the interposition arthroplasty. MATERIAL AND METHODS A total of 28 dorsal wrist capsules were collected from 16 cadavers (with age range at death 18 to 80 years, with no visible wrist pathology). Altogether 112 histological specimens were obtained from these 28 samples. Post-hoc Dunn\'s tests were used to analyse the percentage of vascularisation of individual sides of the dorsal capsule (circumference and area) at the 0.05 level of signifi cance. Spearmann\'s correlation analysis was used to assess the effect of age on vascularization of the dorsal wrist capsule. In cadavers in whom both capsules were collected, the limbs were compared. For the sake of comparison, the Wilcoxon matched pairs test was used. RESULTS Regarding statistical signifi cance, the largest share of the total circumference and area of the measured vessels of the dorsal capsule is constituted by the distal side (35.2% of the circumference and 30.9% of the area). The blood supply of the dorsal capsule received on the ulnar side is the lowest (12.9% of the circumference and 17.6% of the area). There was no signifi cant effect of age on vascularization of the dorsal wrist capsule confi rmed. Also, the comparison of vascularization of both limbs from a single cadaver did not yield any statistically signifi cant results. DISCUSSION Proximal row carpectomy is a long-established surgical technique used to manage the degenerative changes in the wrist. Our results showed the best vascularization on the distal and radial sides of the dorsal wrist capsule. In this light, the distally-based fl ap or the fl ap described by Berger, which respects the clinically important ligaments, appear to be the least invasive and help maintain the future stability of the wrist. CONCLUSIONS In clinical practice, we advise that a radially-based fl ap according to Berger is created and the distal side of the dorsal capsule, the most vascularized portion based on our results, is preserved as much as possible. The fl ap created in this manner also preserves the important carpal ligaments and appears to the authors of this study to be the most benefi cial, also with respect to the presence of the largest arteries, contrary to the distal side. Another option is to use a distally-based fl ap for interposition arthroplasty. Key words: interposition arthroplasty, proximal row carpectomy, vascularization, degenerative changes, wrist.

OBJECTIVE: Clinical-standard MRI is the imaging modality of choice for the wrist, yet limited to static evaluation, thereby potentially missing dynamic instability patterns. We aimed to investigate the clinical benefit of (dynamic) real-time MRI, complemented by automatic analysis, in patients with complete or partial scapholunate ligament (SLL) tears.
METHODS: Both wrists of ten patients with unilateral SLL tears (six partial, four complete tears) as diagnosed by clinical-standard MRI were imaged during continuous active radioulnar motion using a 1.5-T MRI scanner in combination with a custom-made motion device. Following automatic segmentation of the wrist, the scapholunate and lunotriquetral joint widths were analyzed across the entire range of motion (ROM). Mixed-effects model analysis of variance (ANOVA) followed by Tukey\'s posthoc test and two-way ANOVA were used for statistical analysis.
RESULTS: With the increasing extent of SLL tear, the scapholunate joint widths in injured wrists were significantly larger over the entire ROM compared to those of the contralateral healthy wrists (p<0.001). Differences between partial and complete tears were most pronounced at 5°-15° ulnar abduction (p<0.001). Motion patterns and trajectories were altered. Complete SLL deficiency resulted in complex alterations of the lunotriquetral joint widths.
CONCLUSIONS: Real-time MRI may improve the functional diagnosis of SLL insufficiency and aid therapeutic decision-making by revealing dynamic forms of dissociative instability within the proximal carpus. Static MRI best differentiates SLL-injured wrists at 5°-15° of ulnar abduction.

This study aimed to quantify the long-term progression of blunt and sharp cartilage defects and their effect on joint homeostasis and function of the equine carpus. In nine adult Shetland ponies, the cartilage in the radiocarpal and middle carpal joint of one front limb was grooved (blunt or sharp randomized). The ponies were subjected to an 8-week exercise protocol and euthanized at 39 weeks. Structural and compositional alterations in joint tissues were evaluated in vivo using serial radiographs, synovial biopsies, and synovial fluid samples. Joint function was monitored by quantitative gait analysis. Macroscopic, microscopic, and biomechanical evaluation of the cartilage and assessment of subchondral bone parameters were performed ex vivo. Grooved cartilage showed higher OARSI microscopy scores than the contra-lateral sham-operated controls (p < 0.0001). Blunt-grooved cartilage scored higher than sharp-grooved cartilage (p = 0.007) and fixed charge density around these grooves was lower (p = 0.006). Equilibrium and instantaneous moduli trended lower in grooved cartilage than their controls (significant for radiocarpal joints). Changes in other tissues included a threefold to sevenfold change in interleukin-6 expression in synovium from grooved joints at week 23 (p = 0.042) and an increased CPII/C2C ratio in synovial fluid extracted from blunt-grooved joints at week 35 (p = 0.010). Gait analysis outcome revealed mild, gradually increasing lameness. In conclusion, blunt and, to a lesser extent, sharp grooves in combination with a period of moderate exercise, lead to mild degeneration in equine carpal cartilage over a 9-month period, but the effect on overall joint health remains limited.

OBJECTIVE:  The aim of this study was to measure the load on the lateral and medial aspects of the proximal radio-ulnar joint during extension of the carpus.
METHODS:  This was an ex vivo biomechanical study.
METHODS:  Twenty-two cadaveric Greyhound thoracic limbs were used.
METHODS:  Twenty-two paired thoracic limbs were used. The olecranon was attached to a custom jig with the foot resting on a stationary anvil. Load sensors were inserted into the proximal radio-ulnar joint, between the radial head and the lateral coronoid process, and between the radial head and the medial coronoid process. Specimens were tested under compression with measurements taken at 0, 4, 9 and 13.5 mm of axial displacement. Data collected at each point included forces on the specimen and medial and lateral coronoid processes as well as the angle of carpal joint extension.
RESULTS:  A linear mixed effects model relating load on the specimen and carpal joint extension angle had an R-squared value of 0.66, and load at the level of the medial coronoid process and angle of carpal extension had an R-squared value of 0.61. There was a significant difference in the loads measured on the lateral and medial coronoid processes at all angles (p < 0.0001).
CONCLUSIONS:  Extension of the carpus results in asymmetric loading of the proximal radio-ulnar joint.
CONCLUSIONS:  The findings of this study show that loading of the medial coronoid process may be more complex than originally thought and supports the future investigation of novel management and therapeutic options for affected patients.

OBJECTIVE. The purpose of this study was to evaluate the variation of the posterior radioscaphoid (RS) angle in patients with and without scapholunate ligament (SLL) tears during wrist radioulnar deviation. SUBJECTS AND METHODS. Seventy-three patients with clinically suspected scapholunate instability were prospectively evaluated with 4D CT and CT arthrography from February 2015 to April 2018. The posterior RS angle is formed between the articular surface of the scaphoid fossa of the radius and the most posterior point of the scaphoid in the sagittal plane. Two independent radiologists calculated this angle during radioulnar deviation. Posterior RS angles were correlated with the SLL status and the presence of a scapholunate diastasis on conventional stress radiographs. RESULTS. Readers 1 and 2 found mean posterior RS angles of 99° and 98°, respectively, in patients without and 107° and 111°, respectively, in patients with a scapholunate diastasis. The posterior RS angle amplitude varied 7.6-9.3° in the subgroups studied. The reproducibility of posterior RS angle measurement was considered good (intraclass correlation coefficient, 0.73). Mean posterior RS angles increased 6-10% and 12-14% when patients with an intact SLL were compared with those with partial tears and full tears, respectively (p < 0.001). These values also increased 8-13% when patients with diastasis were compared with those without (p < 0.0001). A dynamic acquisition was not necessary to assess this angle, with neutral posterior RS angles yielding a sensitivity of 64% and 72% and specificity of 79% and 94% for the diagnosis of SLL tears by readers 1 and 2, respectively. CONCLUSION. Posterior RS angle tended to increase with the severity of SLL tears and with the presence of scapholunate instability and yielded high sensitivity and specificity for the detection of SLL tears.

The study of contact biomechanics of the wrist is a challenge. This is partly due to the relatively small size of the joint as well as the lack of space in the radiocarpal joint which makes the delivery of investigative materials such as pressure sensitive film without causing artifact, difficult. Fortunately, a number of authors have studied the intact wrist, the scapholunate ligament injured wrist, the proximal row carpectomy and the scaphoid excision, four bone fusion. Despite some contrasting findings, there are some general concepts that we understand about wrist mechanics.

BACKGROUND: Isolated injuries of the scapholunate interosseous ligament (SLIL) are insufficient to produce dorsal intercalated segment instability. There is no consensus about which additional ligamentous stabilizers are critical determinants of dorsal intercalated segment instability. The aim of this study was to evaluate the role of the long radiolunate (LRL), scaphotrapeziotrapezoid (STT), and dorsal intercarpal (DIC) ligaments in preventing dorsal intercalated segment instability.
METHODS: Thirty fresh-frozen forearms were randomized to 5 ligament section sequences to study the SLIL, LRL, STT, and DIC ligaments. The DIC-lunate insertion (DIC) and scaphoid insertion (DIC) were studied separately; the DIC insertions on the trapezium and triquetrum were left intact. Loaded posteroanterior and lateral fluoroscopic images were obtained at baseline and repeated after each ligament was sectioned. After each sequence, the wrists were loaded cyclically (71 N). The radiolunate angle was measured with load. Dorsal intercalated segment instability was defined as an increase of >15° in the radiolunate angle compared with baseline.
RESULTS: Division of the SLIL did not increase the radiolunate angle. Section of the SLIL+LRL or SLIL+DIC significantly increased the radiolunate angle but did not produce dorsal intercalated segment instability. Section of the SLIL+STT or SLIL+DIC+DIC produced dorsal intercalated segment instability.
CONCLUSIONS: In order to produce dorsal intercalated segment instability, complete scapholunate injuries require the disruption of at least 1 critical ligament stabilizer of the scaphoid or lunate (the STT or DIC+DIC).
CONCLUSIONS: When treating SLIL tears with dorsal intercalated segment instability, techniques to evaluate the volar and dorsal critical stabilizers of the proximal carpal row should be considered.

OBJECTIVE: To evaluate the effect of ulnar shortening on distal forearm loading following simulated dynamic motion.
METHODS: Ulnar shortening was simulated using a custom-built adjustable implant to simulate up to 4 mm of ulnar shortening (-4 mm) in 9 cadaveric extremities. Load cells were placed in the distal ulna and radius to quantify axial loading. Using a wrist and forearm motion simulator, absolute and percentage loads were measured during dynamic flexion, ulnar deviation (UD), flexion dart throw (DT), and pronation.
RESULTS: There was a significant decrease in absolute and percentage distal ulnar loads at each interval of ulnar shortening during flexion, UD, DT, and pronation. The distal ulna bore no compressive loads, and in fact, tensile loads were measured in the ulna at 2 mm of ulnar shortening during DT and pronation, at 3 mm during flexion, and at 4 mm during UD.
CONCLUSIONS: A progressive decrease in distal ulnar loads with generation of tensile loads was observed with sequential ulnar shortening.
CONCLUSIONS: Ulnar shortening greater than 2 mm can result in tensile loading in the distal ulna. When managing ulnar impaction syndrome, excessive shortening may not be required to provide relief of symptoms.

Pisiformectomy is the gold standard treatment for pisotriquetral arthritis resistant to conservative treatment. We evaluated the long-term clinical and functional outcomes after pisiformectomy in resistant pisotriquetral arthritis cases. We retrospectively evaluated 11 patients (12 wrists), mean age of 59 years (49-69) treated by pisiformectomy using a standardized surgical technique. Pisiformectomy was performed for primary osteoarthritis in 10 cases, for post-traumatic osteoarthritis in 1 case and for pisotriquetral instability in 1 case. The clinical and functional evaluation was carried out by an independent examiner. Mean time to review was 90 months (63-151). Pain on a Visual Analog Scale (/10) decreased significantly to 1.1 from 6.8 preoperatively. Mean range of motion was 79° in flexion, 61.5° in extension, 18° in ulnar deviation and 36° in radial deviation. Mean grip strength of the operated wrist was 86% of the non-operated wrist. Functional scores significantly improved with a gain of 40 points for the QuickDASH and 53 points for the PRWE. Based on this long-term follow-up study, pisiformectomy seems to alleviate wrist pain and improve the quality of life in a low-demand population with pisotriquetral osteoarthritis resistant to conservative treatment. When compared to the pisotriquetral arthrodesis, pisiformectomy is easier to perform, allows quicker mobilization of the wrist and leads to good functional outcomes.

METHODS: Randomized control trial.
BACKGROUND: During weight-bearing wrist movement, potential stabilizing forces caused by carpal stabilizing taping (CST) may restrict movement of the carpal bones, allowing greater wrist joint extension.
OBJECTIVE: The purpose of study was to investigate the effect of CST during weight-bearing wrist movement on pain intensity and range of motion (ROM) of wrist extension in subjects with dorsal wrist pain.
METHODS: Thirty participants with dorsal wrist pain when weight bearing through the hand were randomly allocated into 2 groups: (1) a CST group using rigid tape and (2) placebo taping (PT) group using elastic tape. Subjects performed weight-bearing wrist movements with CST or PT in 6 sessions for 1 week. Active and passive ROM (AROM and PROM), and the visual analog scale (VAS) were assessed at baseline and after the intervention.
RESULTS: The AROM and PROM of wrist extension increased significantly in both groups compared with preintervention values (P < .01). Comparing the PT and CST groups, the differences between preintervention and postintervention AROM (mean difference [MD] = +8.6°) and PROM (MD = +6.8°) were significantly greater in the CST group than in the PT group (P < .01). The CST group also showed greater improvement in VAS compared with the PT group (MD = -18 mm) (P < .01).
CONCLUSIONS: We recommend CST during weight-bearing wrist movement as an effective intervention for both increasing wrist extension ROM and decreasing pain in patients with dorsal wrist pain during weight bearing through the hand.