Mean global ocean temperatures during the last glacial transition.

Little is known about the ocean temperature's long-term response to climate perturbations owing to limited observations and a lack of robust reconstructions. Although most of the anthropogenic heat added to the climate system has been taken up by the ocean up until now, its role in a century and beyond is uncertain. Here, using noble gases trapped in ice cores, we show that the mean global ocean temperature increased by 2.57 ± 0.24 degrees Celsius over the last glacial transition (20,000 to 10,000 years ago). Our reconstruction provides unprecedented precision and temporal resolution for the integrated global ocean, in contrast to the depth-, region-, organism- and season-specific estimates provided by other methods. We find that the mean global ocean temperature is closely correlated with Antarctic temperature and has no lead or lag with atmospheric CO2, thereby confirming the important role of Southern Hemisphere climate in global climate trends. We also reveal an enigmatic 700-year warming during the early Younger Dryas period (about 12,000 years ago) that surpasses estimates of modern ocean heat uptake.

Abrupt ice-age shifts in southern westerly winds and Antarctic climate forced from the north.

The mid-latitude westerly winds of the Southern Hemisphere play a central role in the global climate system via Southern Ocean upwelling1, carbon exchange with the deep ocean2, Agulhas leakage (transport of Indian Ocean waters into the Atlantic)3 and possibly Antarctic ice-sheet stability4. Meridional shifts of the Southern Hemisphere westerly winds have been hypothesized to occur5,6 in parallel with the well-documented shifts of the intertropical convergence zone7 in response to Dansgaard-Oeschger (DO) events- abrupt North Atlantic climate change events of the last ice age. Shifting moisture pathways to West Antarctica8 are consistent with this view but may represent a Pacific teleconnection pattern forced from the tropics9. The full response of the Southern Hemisphere atmospheric circulation to the DO cycle and its impact on Antarctic temperature remain unclear10. Here we use five ice cores synchronized via volcanic markers to show that the Antarctic temperature response to the DO cycle can be understood as the superposition of two modes: a spatially homogeneous oceanic 'bipolar seesaw' mode that lags behind Northern Hemisphere climate by about 200 years, and a spatially heterogeneous atmospheric mode that is synchronous with abrupt events in the Northern Hemisphere. Temperature anomalies of the atmospheric mode are similar to those associated with present-day Southern Annular Mode variability, rather than the Pacific-South American pattern. Moreover, deuterium-excess records suggest a zonally coherent migration of the Southern Hemisphere westerly winds over all ocean basins in phase with Northern Hemisphere climate. Our work provides a simple conceptual framework for understanding circum-Antarctic temperature variations forced by abrupt Northern Hemisphere climate change. We provide observational evidence of abrupt shifts in the Southern Hemisphere westerly winds, which have previously documented1-3 ramifications for global ocean circulation and atmospheric carbon dioxide. These coupled changes highlight the necessity of a global, rather than a purely North Atlantic, perspective on the DO cycle.

Reliability and Validity Analysis of the Distal Radioulnar Joint Ballottement Test.

PURPOSE: Triangular fibrocartilage complex injuries can cause distal radioulnar joint (DRUJ) instability, which can be evaluated clinically with the DRUJ ballottement test. However, the reliability and validity of the test are unclear. This study aimed to analyze the reliability and validity of the test using a tracking device on healthy participants and patients with triangular fibrocartilage complex injuries. METHODS: In this cross-sectional study, three orthopedic hand surgeons performed the DRUJ ballottement test using a technique of holding the carpal bones to the radius on 25 healthy participants (50 hands; 10 men and 15 women; mean age, 33 years; range, 20-51 years) and eight patients with triangular fibrocartilage complex injuries (16 hands; six men and two women; mean age, 43 years; range, 27-59 years). We used a three-dimensional electromagnetic tracking device to quantify the movement of the DRUJ and verify the reliability and validity of the test. RESULTS: The intrarater and interrater intraclass correlation coefficients for DRUJ movement were 0.77 and 0.61, respectively, and the kappa coefficient for grading of DRUJ instability was 0.79. The correlation coefficient between DRUJ movement measured using the tracking device and instability judged clinically was 0.77. A comparison of healthy participants and the patients showed significantly greater DRUJ movement in the patients. CONCLUSIONS: The test showed substantial intrarater and interrater reliability for assessing DRUJ movement and instability. The significant positive correlation between DRUJ movement and instability indicates the concurrent validity of the test. Moreover, the test showed discriminative validity in identifying mild or moderate DRUJ instability. CLINICAL RELEVANCE: The DRUJ ballottement test using the holding technique has a relatively high diagnostic accuracy and can be used to assess DRUJ instability.

Anatomical quantitative evaluation of popliteal artery visualization during medial approach in supine position.

PURPOSE: The medial approach to the popliteal artery has been less commonly used than the posterior approach in surgical repair of traumatic popliteal injury. This study was performed to quantitatively evaluate the visual field of the popliteal artery obtained by staged myotendotomy in the medial approach to the popliteal artery. METHODS: Twenty legs of fresh-frozen adult cadavers were dissected using the medial approach to the popliteal artery. In stage 1, the popliteal artery was exposed between the vastus medialis and sartorius muscles without myotendotomy. In stage 2, the medial head of the gastrocnemius muscle was dissected. In stage 3, the tendons of the sartorius and semimembranosus muscles were dissected. In stage 4, the tendons of the gracilis and semitendinosus muscles were dissected to fully expose the popliteal artery. The length of the popliteal artery that could be visualized in each stage was measured. RESULTS: The anatomical length of the popliteal artery from the hiatus of the adductor magnus to the tendinous arch of soleus muscle ranged from 15 to 20 cm (mean, 16.3 cm). On average, 45%, 59%, 72%, and 100% of the popliteal artery were visualized in stage 1, 2, 3, and 4, respectively. CONCLUSIONS: The medial approach to the popliteal artery has the advantage of being performed in the supine position, but it requires multiple myotendotomies around the knee. The results of this study may serve as a reference for myotendotomy depending on the site of injury to the popliteal artery.

Clinical outcomes of reposition flap transfer for fingertip amputation.

PURPOSE: This study aimed to describe the reposition flap for reconstructing fingertip amputation when replantation is not possible. METHODS: This study retrospectively reviewed the records of patients with reposition flap transfers and investigated postoperative clinical outcomes and patient satisfaction. Sixteen patients with fingertip amputations treated with a reposition flap from 2016 to 2020. The mean age at injury was 46 years (range, 26-70 years). Ten cases were treated with oblique triangular advancement flaps, 3 with retrograde-flow digital artery flaps, and 3 with thumb palmar advancement flaps. Postoperative outcomes, including wound healing period and the IP/PIP extension angle, and the presence of grafted bone absorption and patient satisfaction were evaluated as of 3 years after surgery. RESULTS: The average reduction in passive extension angle of the IP/PIP joint was 19°. The average time for complete wound healing was 28 days (range, 18-41 days). The reduction in passive extension angle of the IP/PIP joint was significantly correlated with the wound healing period (r = 0.66, p = 0.01). The absorption of the grafted bone was observed in 3 cases. In these cases, the distal tip of the flap became thin due to flap retraction and an insufficient flap volume. All patients were highly or fairly satisfied with the results of surgery. CONCLUSION: Our findings show that IP/PIP flexion contracture can occur due to delayed wound healing after reposition flap transfer, but the patient satisfaction level was generally high. Therefore, reconstruction using a reposition flap gives acceptable clinical outcomes and high patient satisfaction as a result of medium to long-term.

Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica.

The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice-climate feedbacks that further amplify warming.

A cadaveric study of ulnar nerve strain at the elbow associated with cubitus valgus/varus deformity.

BACKGROUND: Cubital tunnel syndrome can be caused by overtraction and dynamic compression in elbow deformities. The extent to which elbow deformities contribute to ulnar nerve strain is unknown. Here, we investigated ulnar nerve strain caused by cubitus valgus/varus deformity using fresh-frozen cadavers. METHODS: We used six fresh-frozen cadaver upper extremities. A strain gauge was placed on the ulnar nerve 2 cm proximal to the medial epicondyle of the humerus. For the elbow deformity model, osteotomy was performed at the distal humerus, and plate fixation was performed to create cubitus valgus/varus deformities (10°, 20°, and 30°). Ulnar nerve strain caused by elbow flexion (0-125°) was measured in both the normal and deformity models. The strains at different elbow flexion angles within each model were compared, and the strains at elbow extension and at maximum elbow flexion were compared between the normal model and each elbow deformity model. However, in the cubitus varus model, the ulnar nerve deflected more than the measurable range of the strain gauge; elbow flexion of 60° or more were considered effective values. Statistical analysis of the strain values was performed with Friedman test, followed by the Williams' test (the Shirley‒Williams' test for non-parametric analysis). RESULTS: In all models, ulnar nerve strain increased significantly from elbow extension to maximal flexion (control: 13.2%; cubitus valgus 10°: 13.6%; cubitus valgus 20°: 13.5%; cubitus valgus 30°: 12.2%; cubitus varus 10°: 8.3%; cubitus varus 20°: 8.2%; cubitus varus 30°: 6.3%, P < 0.001). The control and cubitus valgus models had similar values, but the cubitus varus models revealed that this deformity caused ulnar nerve relaxation. CONCLUSIONS: Ulnar nerve strain significantly increased during elbow flexion. No significant increase in strain 2 cm proximal to the medial epicondyle was observed in the cubitus valgus model. Major changes may have been observed in the measurement behind the medial epicondyle. In the cubitus varus model, the ulnar nerve was relaxed during elbow extension, but this effect was reduced by elbow flexion.

Acromioclavicular joint instability on cross-body adduction view: the biomechanical effect of acromioclavicular and coracoclavicular ligaments sectioning.

BACKGROUND: The acromioclavicular (AC) and coracoclavicular (CC) ligaments are important stabilizers of the AC joint. We hypothesized that AC and trapezoid ligament injuries induce AC joint instability and that the clavicle can override the acromion on cross-body adduction view even in the absence of conoid ligament injury. Accordingly, we investigated how sectioning the AC and CC ligaments contribute to AC joint instability in the cross-body adduction position. METHODS: Six fresh-frozen cadaveric shoulders were used in this study, comprising five male and one female specimen, with a mean age of 68.7 (range, 51-87) years. The left side of the trunk and upper limb, and the cervical and thoracic vertebrae and sternum were firmly fixed with an external fixator. The displacement of the distal end of the clavicle relative to the acromion was measured using an electromagnetic tracking device. We simulated AC joint dislocation by the sequential resection of the AC ligament, AC joint capsule, and CC ligaments in the following order of stages. Stage 0: Intact AC and CC ligaments and acromioclavicular joint capsule; stage 1: Completely sectioned AC ligament, capsule and joint disc; stage 2: Sectioned trapezoid ligament; and stage 3: Sectioned conoid ligament. The superior clavicle displacement related to the acromion was measured in the horizontal adduction position, and clavicle overriding on the acromion was assessed radiologically at each stage. Data were analyzed using a one-way analysis of variance and post-hoc tests. RESULTS: Superior displacement was 0.3 mm at stage 1, 6.5 mm at stage 2, and 10.7 mm at stage 3. On the cross-body adduction view, there was no distal clavicle overriding at stages 0 and 1, and distal clavicle overriding was observed in five cases (5/6: 83%) at stage 2 and in six cases (6/6: 100%) at stage 3. CONCLUSION: We found that AC and trapezoid ligament sectioning induced AC joint instability and that the clavicle could override the acromion on cross-body adduction view regardless of conoid ligament sectioning. The traumatic sections of the AC and trapezoid ligament may lead to high grade AC joint instability, and the distal clavicle may subsequently override the acromion.

Dynamic analysis of the ulnar nerve and cubital tunnel morphology using ultrasonography: a cadaveric study.

BACKGROUND: The causes of ulnar neuropathy at the elbow are unclear. The authors hypothesized that the humeral trochlea protrudes into the cubital tunnel during elbow flexion and causes a dynamic morphologic change of the ulnar nerve in the cubital tunnel. METHODS: An ultrasonic probe was fixed to the ulnar shafts of 10 fresh cadavers with an external fixator, and dynamic morphology of the cubital tunnel and ulnar nerve was observed. The distance from the Osborne band to the trochlea (OTD), distance from ulnar nerve center to the trochlea (UTD), and the short- and long-axis diameters of the nerve at 30°, 60°, 90°, and 120° of elbow flexion were recorded. We compared the OTD, UTD, and the flattening of the ulnar nerve at the different angles of flexion using single-factor analysis of variance. Correlation between the ulnar nerve flattering, OTD, and UTD was examined using Spearman correlation coefficient. A P value less than .05 was used to denote statistical significance. RESULTS: Flattening of the ulnar nerve progressed with increasing elbow flexion and was significantly different between 0° and 60°, 90°, and 120° (P = .03 at 60°, P < .01 at 90° and 120°). OTD decreased with elbow flexion, and there was a significant difference at all elbow flexion angles (all P < .01). UTD decreased significantly from 0° flexion to 90° flexion (P = .03). Flattening of the nerve was significantly correlated with the OTD (r = 0.66, P < .01). CONCLUSIONS: A positive correlation was found between the protrusion of the humeral trochlea into the cubital tunnel during elbow flexion and ulnar nerve flattening using cadaveric elbow and ultrasonography.

Impacted intraarticular fragments of distal radius fractures: A radiographic characterization and analysis of reliability and diagnostic accuracy.

BACKGROUND: Reduction using ligamentotaxis may not be effective enough to treat impacted intraarticular fragments of distal radius fractures. Articular incongruence resulting from the loss of reduction is a risk factor for postoperative osteoarthritis and worse clinical outcome. This study aimed to analyze the radiographic characterization of the impacted intraarticular fragments of distal radius fractures using two/three-dimensional computed tomography (CT). Further, we assessed the reliability and diagnostic accuracy in detecting the fragments using plain radiographs. METHODS: We analyzed 167 three-dimensional CT images of the intraarticular distal radius fractures and selected 12 fractures with impacted intraarticular fragments. We recorded the location, size, and displacement of the fragment using CT images. In addition, six examiners evaluated 25 fractures including those 12 fractures having the fragments using plain radiographs for detecting the fragments and their displacements. Further, we evaluated the reliability and diagnostic accuracy of the plain radiographs in the detection of the fragment. RESULTS: Fifteen impacted intraarticular fragments were found in 12 wrists. The displacement of the scaphoid facet fragment was significantly larger than that of the lunate facet fragment in CT measurement (7.0 mm and 3.6 mm). Inter and intraobserver reliability of the diagnosis for the fragment in plain radiographs were poor and fair (κ: 0.14 and κ:0.27). Diagnostic accuracy in detecting the fragment in plain radiographs generated mean sensitivity: 0.4, mean specificity: 0.73, and mean accuracy: 0.58. The mean sensitivity in detecting a lunate facet fragment was lower than that of a scaphoid facet fragment in plain radiographs (0.24 and 0.44). CONCLUSION: Impacted intraarticular fragments were found in 7% of intraarticular distal radius fractures. We observed low reliability and sensitivity in detecting the fragment using plain radiographs. Preoperative recognition of the fragments using plain radiograph were difficult, even though the magnitude of step-off of the scaphoid facet fragment was large.

Gait cycle time variability in patients with knee osteoarthritis and its possible associating factors.

[Purpose] Knee osteoarthritis can alter gait variability; however, few studies have investigated the associating factors with gait cycle time variability. The first objective was to compare gait cycle variability between female patients with knee osteoarthritis and healthy elderly females and to determine gait characteristics in patients with knee osteoarthritis. The second objective was to identify the associating factors with gait cycle time variability. [Participants and Methods] The participants included 24 female patients diagnosed with knee osteoarthritis and 12 healthy elderly females. Gait cycle variability (coefficient of variation of gait cycle time), knee extension range of motion, knee extension strength, 5-m walk test, Timed Up & Go Test, and Western Ontario and McMaster Universities Osteoarthritis Index were measured. All assessment results were compared between the knee osteoarthritis and healthy groups. [Results] Gait cycle time variability was significantly higher in the knee osteoarthritis group than in the healthy group. Further, it showed a significant positive correlation with the 5-m walk test and the Western Ontario and McMaster Universities Osteoarthritis Index. [Conclusion] Patients with knee osteoarthritis presented greater gait cycle variability than that of healthy individuals. Therefore, rehabilitation to improve gait variability might enhance the quality of life of patients with knee osteoarthritis.

Partial Trapeziotrapezoid Resection and Thumb Range of Movement After Trapeziometacarpal Joint Fusion-A Biomechanical Study.

PURPOSE: Trapeziometacarpal (TMC) joint arthrodesis is an effective treatment for stage III osteoarthritis. Although this procedure alleviates thumb pain and restores grip power and pinch strength, persistent limitation of thumb movement is inevitable. This biomechanical study aimed to investigate the altered kinematics of thumb circumduction motion after TMC joint arthrodesis and subsequent excision of the trapeziotrapezoid (TT) and trapezio-second metacarpal (T-2MC) joint spaces. METHODS: Eight cadaver upper extremities were mounted on a custom testing apparatus. The hand and carpal bones were fixed to the apparatus, except for the first metacarpal bone, trapezium, and trapezoid. A 50-g load was applied at the tip of the first metacarpal head to generate passive thumb circumduction. An electromagnetic tracking system measured the angular and rotational displacement of the first metacarpal. All specimens were tested in 4 conditions: intact, after simulated TMC joint fusion, after subsequent excision of 3 mm of bone at the TT joint space, and after additional 3 mm resection at the T-2MC joint space. RESULTS: After simulated TMC arthrodesis, the range of angular motion of thumb circumduction decreased to 25% that of the intact thumb. Subsequent resections at the TT and T-2MC joint spaces increased circumduction ranges to 49% (TT joint) and 73% (TT plus T-2MC joints) that of the intact thumb. The range of thumb rotational motion showed a similar trend. CONCLUSIONS: Trapeziometacarpal arthrodesis decreased the range of both angular and rotational motion during thumb circumduction. Subsequent resections at the paratrapezial space increased the range of thumb motion, suggesting that hypermobility of the paratrapezial joints increases thumb mobility after TMC joint fusion. CLINICAL RELEVANCE: Patients with hypermobile paratrapezial joints may have larger thumb movement after TMC joint fusion. Additional resections of the TT and T-2MC joint spaces may further mobilize the thumb in patients who complain of stiffness after TMC fusion.

Vascularized pedicled bone graft from the distal radius supplied by the anterior interosseous artery for treatment of ulnar shaft nonunion: An anatomical study of cadavers and a case report.

BACKGROUND: A vascularized distal radius graft can be a reliable solution for the treatment of refractory ulnar nonunion. The aim of this study is to establish the anatomical basis of a vascularized bone graft pedicled by the anterior interosseous artery and report its clinical application, using cadaveric studies and a case report. METHODS: Fourteen fresh frozen cadaveric upper limbs were used. The branches of the anterior interosseous artery (the 2, 3 intercompartmental supraretinacular artery and the fourth extensor compartment artery) were measured at the bifurcation site. The anatomical relationship between the anterior interosseous artery and motor branches of the posterior interosseous nerve was investigated. An anterior interosseous artery pedicled bone flap was used in a 48-year-old woman with refractory ulnar nonunion. RESULTS: There were two variations depending on whether the 2,3 intercompartmental supraretinacular artery branched off distally or proximally from the terminal motor branch of the posterior interosseous nerve. The proximal border of the graft was located at an average of 10.5 cm (range, 6.5-12.5 cm) from the distal end of the ulnar head in the distal type (57%) and 17.5 cm (range, 9.5-21.5 cm) in the proximal type (43%). In the clinical application, successfully consolidation was achieved 4 months post-surgery. The patient had not developed any postoperative complications until the 2-year postoperative follow-up. CONCLUSIONS: The anterior interosseous artery-pedicled, vascularized distal radius bone graft would be a reliable alternative solution for the treatment of an ulnar nonunion located within the distal one-third of the ulna.

Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.

The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere-asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere-asthenosphere response. Carbon dioxide is involved, but is not determinative, in the evolution of the 100,000-year glacial cycles.

Tamai Zone 1 Fingertip Amputation: Reconstruction Using a Digital Artery Flap Compared With Microsurgical Replantation.

PURPOSE: The surgical treatment of fingertip amputations is controversial. This study was designed to compare the clinical results of 2 surgical procedures for fingertip amputation: reconstruction with a digital artery flap and microsurgical replantation. METHODS: Between 2003 and 2015, 37 patients with Tamai zone 1 fingertip amputation of the index or middle finger were treated by reconstruction with a digital artery flap (n = 23) or microsurgical replantation (n = 14). Data for these patients were evaluated retrospectively. Nerve suture was not conducted in microsurgical replantation because spontaneous sensory recovery is expected in zone 1 replantation. Primary outcomes included hand dexterity (Purdue Pegboard Test), and disability of the upper extremity (Disabilities of the Arm, Shoulder, and Hand score). Secondary outcomes included strength (key pinch), digital sensitivity (Semmes-Weinstein test), and finger mobility (% total active motion). RESULTS: The average follow-up period was 34 months. There was no significant difference in the primary outcomes between the 2 groups. The reconstruction group showed significantly better results for the secondary outcomes. CONCLUSIONS: This study suggests that the 2 procedures were comparable regarding postoperative activities of daily living and hand performance, but reconstruction using a digital artery flap gave better objective functional outcomes than microsurgical replantation. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Arthroscopic Distal Scaphoid Resection for Isolated Scaphotrapeziotrapezoid Osteoarthritis.

PURPOSE: To investigate the radiographic and clinical results of arthroscopic distal scaphoid resection for isolated scaphotrapeziotrapezoid (STT) osteoarthritis and analyze the radiographic parameters associated with the functional outcomes. METHODS: From 2008 to 2014, 17 wrists with symptomatic isolated STT osteoarthritis without carpal deformity underwent arthroscopic distal scaphoid resection. We evaluated visual analog scale (VAS) scores for pain, grip strength, pinch strength, and Patient-Rated Wrist Evaluation (PRWE) scores before surgery and at the final follow-up. We analyzed correlations between the resection height and the radiographic and functional outcomes. RESULTS: The average follow-up period was 42 months. The average VAS score improved from 6.1 ± 2.3 before surgery to 1.7 ± 1.9 after surgery. The average grip strength improved from 18 ± 6 to 19 ± 9 kg, pinch strength from 2.5 ± 1.1 to 4.4 ± 1.7 kg, and PRWE score from 52 ± 23 to 32 ± 24. Carpal deformity (C-L angle of > 15°) was seen in 2 patients at the final follow-up. The deformity was more likely to occur when the resection height was greater than 3 mm. CONCLUSIONS: Arthroscopic distal scaphoid resection alone can reduce pain and improve functional outcomes for early to mid-stage isolated STT osteoarthritis in patients without dorsal intercalated segment instability deformity. Resection of greater than 3 mm of the distal scaphoid may result in carpal malalignment. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Predictors of Hand Dexterity after Single-Digit Replantation.

BACKGROUND: Microsurgical replantation of the thumb and digits has become an increasingly familiar technique in clinical practice worldwide. However, successful digit replantation does not always provide better hand function than revision amputation. Little information is available regarding predictors of motor skill activities of replanted hands. Therefore, we retrospectively evaluated hand dexterity after single-digit replantation at a minimum follow-up of 1 year and analyzed the factors influencing dexterity. METHODS: This retrospective cohort study included 23 patients treated for amputation injuries at our institution from 2014 to 2015. Patients with amputations from Tamai's zone 2 to 5 of the thumb (3 patients), index finger (11 patients), or middle finger (9 patients) who underwent digital replantation surgery and were followed up for more than 1 year were included. Follow-up evaluations were conducted at an average of 23 months postoperatively (range: 13-25 months). We hypothesized that possible factors influencing hand dexterity after single-digit replantation were patient age, injured finger, key pinch strength, Semmes-Weinstein test result, and percentage of total active motion. Relationships between the outcome variable, which was the result of the Purdue Pegboard Test of hand dexterity, and explanatory variables were analyzed using Spearman's correlation coefficient. A p-value of < 0.05 indicated statistical significance. RESULTS: No postoperative complications occurred. Univariate analysis indicated that decreased hand dexterity after single-digit replantation was significantly associated with older age (p = 0.001) and poor recovery of sensation, as shown by the Semmes-Weinstein test (p = 0.012). CONCLUSION: Patient age was a risk factor for low hand dexterity after replantation surgery. Recovery of finger sensitivity enhanced dexterity of motor skill activities following finger replantation surgery.

New methods for measuring atmospheric heavy noble gas isotope and elemental ratios in ice core samples.

RATIONALE: The global ocean constitutes the largest heat buffer in the global climate system, but little is known about its past changes. The isotopic and elemental ratios of heavy noble gases (krypton and xenon), together with argon and nitrogen in trapped air from ice cores, can be used to reconstruct past mean ocean temperatures (MOTs). Here we introduce two successively developed methods to measure these parameters with a sufficient precision to provide new constraints on past changes in MOT. METHODS: The air from an 800-g ice sample - containing roughly 80 mL STP air - is extracted and processed to be analyzed on two independent dual-inlet isotope ratio mass spectrometers. The primary isotope ratios (δ15 N, δ40 Ar and δ86 Kr values) are obtained with precisions in the range of 1 per meg (0.001‰) per mass unit. The three elemental ratio values δKr/N2 , δXe/N2 and δXe/Kr are obtained using sequential (non-simultaneous) peak-jumping, reaching precisions in the range of 0.1-0.3‰. RESULTS: The latest version of the method achieves a 30% to 50% better precision on the elemental ratios and a twofold better sample throughput than the previous one. The method development uncovered an unexpected source of artefactual gas fractionation in a closed system that is caused by adiabatic cooling and warming of gases (termed adiabatic fractionation) - a potential source of measurement artifacts in other methods. CONCLUSIONS: The precisions of the three elemental ratios δKr/N2 , δXe/N2 and δXe/Kr - which all contain the same MOT information - suggest smaller uncertainties for reconstructed MOTs (±0.3-0.1°C) than previous studies have attained. Due to different sensitivities of the noble gases to changes in MOT, δXe/N2 provides the best constraints on the MOT under the given precisions followed by δXe/Kr, and δKr/N2 ; however, using all of them helps to detect methodological artifacts and issues with ice quality.