Plant functional traits and canopy structure control the relationship between photosynthetic CO2 uptake and far-red sun-induced fluorescence in a Mediterranean grassland under different nutrient availability.

Sun-induced fluorescence (SIF) in the far-red region provides a new noninvasive measurement approach that has the potential to quantify dynamic changes in light-use efficiency and gross primary production (GPP). However, the mechanistic link between GPP and SIF is not completely understood. We analyzed the structural and functional factors controlling the emission of SIF at 760 nm (F760 ) in a Mediterranean grassland manipulated with nutrient addition of nitrogen (N), phosphorous (P) or nitrogen-phosphorous (NP). Using the soil-canopy observation of photosynthesis and energy (SCOPE) model, we investigated how nutrient-induced changes in canopy structure (i.e. changes in plant forms abundance that influence leaf inclination distribution function, LIDF) and functional traits (e.g. N content in dry mass of leaves, N%, Chlorophyll a+b concentration (Cab) and maximum carboxylation capacity (Vcmax )) affected the observed linear relationship between F760 and GPP. We conclude that the addition of nutrients imposed a change in the abundance of different plant forms and biochemistry of the canopy that controls F760 . Changes in canopy structure mainly control the GPP-F760 relationship, with a secondary effect of Cab and Vcmax . In order to exploit F760 data to model GPP at the global/regional scale, canopy structural variability, biodiversity and functional traits are important factors that have to be considered.

A multi-scale approach of fluvial biogeomorphic dynamics using photogrammetry.

Over the last twenty years, significant technical advances turned photogrammetry into a relevant tool for the integrated analysis of biogeomorphic cross-scale interactions within vegetated fluvial corridors, which will largely contribute to the development and improvement of self-sustainable river restoration efforts. Here, we propose a cost-effective, easily reproducible approach based on stereophotogrammetry and Structure from Motion (SfM) technique to study feedbacks between fluvial geomorphology and riparian vegetation at different nested spatiotemporal scales. We combined different photogrammetric methods and thus were able to investigate biogeomorphic feedbacks at all three spatial scales (i.e., corridor, alluvial bar and micro-site) and at three different temporal scales, i.e., present, recent past and long term evolution on a diversified riparian landscape mosaic. We evaluate the performance and the limits of photogrammetric methods by targeting a set of fundamental parameters necessary to study biogeomorphic feedbacks at each of the three nested spatial scales and, when possible, propose appropriate solutions. The RMSE varies between 0.01 and 2 m depending on spatial scale and photogrammetric methods. Despite some remaining difficulties to properly apply them with current technologies under all circumstances in fluvial biogeomorphic studies, e.g. the detection of vegetation density or landform topography under a dense vegetation canopy, we suggest that photogrammetry is a promising instrument for the quantification of biogeomorphic feedbacks at nested spatial scales within river systems and for developing appropriate river management tools and strategies.

The northernmost hyperspectral FLoX sensor dataset for monitoring of high-Arctic tundra vegetation phenology and Sun-Induced Fluorescence (SIF).

A hyperspectral field sensor (FloX) was installed in Adventdalen (Svalbard, Norway) in 2019 as part of the Svalbard Integrated Arctic Earth Observing System (SIOS) for monitoring vegetation phenology and Sun-Induced Chlorophyll Fluorescence (SIF) of high-Arctic tundra. This northernmost hyperspectral sensor is located within the footprint of a tower for long-term eddy covariance flux measurements and is an integral part of an automatic environmental monitoring system on Svalbard (AsMovEn), which is also a part of SIOS. One of the measurements that this hyperspectral instrument can capture is SIF, which serves as a proxy of gross primary production (GPP) and carbon flux rates. This paper presents an overview of the data collection and processing, and the 4-year (2019-2021) datasets in processed format are available at: https://thredds.met.no/thredds/catalog/arcticdata/infranor/NINA-FLOX/raw/catalog.html associated with https://doi.org/10.21343/ZDM7-JD72 under a CC-BY-4.0 license. Results obtained from the first three years in operation showed interannual variation in SIF and other spectral vegetation indices including MERIS Terrestrial Chlorophyll Index (MTCI), EVI and NDVI. Synergistic uses of the measurements from this northernmost hyperspectral FLoX sensor, in conjunction with other monitoring systems, will advance our understanding of how tundra vegetation responds to changing climate and the resulting implications on carbon and energy balance.

Glenohumeral translations are only partially restored after repair of a simulated type II superior labral lesion.

BACKGROUND: The effect on joint stability of repair of type II superior labrum and biceps anchor lesions is unknown. HYPOTHESIS: Increased translations of the glenohumeral joint after a simulated type II lesion will be reduced after the lesion is repaired. STUDY DESIGN: Controlled laboratory study. METHODS: A robotic/universal force-moment testing system was used to simulate load-and-shift and apprehension tests on eight cadaveric shoulders to determine joint kinematics of the shoulder after venting, creation of a type II lesion, and repair of the lesion. RESULTS: At 30 degrees of abduction, anterior translation of the vented joint in response to an anterior load was 18.7 +/- 8.5 mm and was significantly increased to 26.2 +/- 6.5 mm after simulation of a type II lesion. Repair did not restore anterior translation (23.9 +/- 8.6 mm) to that of the vented joint. The inferior translation that also occurred during application of an anterior load was 3.8 +/- 4.0 mm in the vented joint and increased significantly to 8.5 +/- 5.4 mm with a simulated type II lesion. After repair, the inferior translation decreased significantly to 6.7 +/- 5.3 mm. CONCLUSIONS: Repair of a type II lesion only partially restored glenohumeral translations to that of the vented joint. CLINICAL RELEVANCE: Surgical techniques including improved repair of passive stabilizers injured in the type II lesion should be considered.

The suspension sling for arthroscopic fixation of SLAP lesions.

We describe an arthroscopic technique for SLAP fixation. In most of the cases, the arthroscopic view during a SLAP repair is complicated by the posterior-superior labrum falling into the joint. We insert 2 needles over the supraspinatus portal, which are loaded with a No. 1 PDS. One needle is inserted under the surface of the posterior-superior labrum and the other over the surface. By using the anterior-superior portal, we can retrieve the 2 sutures and knot them together. By pulling the 2-knot sutures back over the anterior-superior portal, we create a sling and can hold the posterior-superior labrum back. In doing so, we gain an excellent arthroscopic view for preparing the glenoid neck and precise positioning of fixation devices without interfering with the superior-posterior labrum. The technique is easy and safe.

Retrograde cartilage transplantation on the proximal and distal tibia.

The authors, with experience with more than 400 osteochondral autograft transplantation (OATS) cases since 1996, report a new technique of a retrograde osteochondral autograft transplantation for the treatment of isolated osteochondral lesions of the proximal and the distal tibia started in 1999. We treated 5 patients, 3 who presented with painful traumatic chondral defects in the central weight-bearing portion of the tibial plateau (1 in the medial and 2 in the lateral compartment), and 2 who presented with painful chondral lesions on the distal tibia. An anterior cruciate ligament (ACL) drill guide positioned in the center of the defect was used to accurately prepare the cartilage surface, in one case arthroscopically and in 4 cases through an open incision. A guide-wire was introduced and drilled through the tibia, and a cannulated reamer equal to the diameter of the defect was advanced. An osteochondral cylinder was harvested from the non-weight-bearing zone of the femoral trochlea at the angle that corresponded to the angle on the ACL drill guide. The autograft was inserted in a retrograde fashion from the cortical window into the tibial tunnel to be flush with the articular surface in press-fit technique. The remaining tunnel defect between the cortical window on the tibia and the distal aspect of the autograft was filled with a cancellous bony cylinder and secured with a diagonal bioabsorbable screw. A concomitant varus deformity with the lesion on the medial tibial plateau was corrected in the same surgery using a high tibial osteotomy to relieve stress on the graft. Patients were followed up for 6 to 35 months. A complete healing of the grafts was seen in control magnetic resonance images (MRIs). All patients were satisfied with the surgery. Control arthroscopies showed the osteochondral cylinders well integrated and flush with the articular surface.

Anterior cruciate ligament tunnel placement: Comparison of insertion site anatomy with the guidelines of a computer-assisted surgical system.

PURPOSE: With the development of computer-assisted surgery (CAS) systems, the surgeon's ability to operate a CAS planning station will become essential. For example, default parameters in computed tomographic (CT) data are being used to place tunnels in anterior cruciate ligament (ACL) reconstruction. The goal of this study was to compare the location of the insertion sites in ACL reconstruction anatomically, via roentgenographic images and via CT scan data and to validate these tunnel placement parameters. TYPE OF STUDY: Cadaveric analysis. METHODS: Eight human cadaveric knees were marked with 6 copper wires 1 mm in diameter around the circumference of the insertions of the ACL. Using lateral roentgenograms and CT scans that were subsequently transferred to the CAS planning station, the tunnel locations were determined. These were based on a distance from the back of the condyle (location A) and from the roof of the notch (location B) on the femur and on a distance posterior from the tuberosity to the posterior margin along the tibial plateau, which is set as the CAS planning station's default. Locations according to roentgenograms and CT scans were then compared and the accuracy of the CAS planning station was assessed. RESULTS: Comparison of roentgenograms and CT revealed a femoral insertion at 27.5% +/- 3.2% and 26.9% +/- 3.5% (roentgenograms) and 26.6% +/- 1.9% and 26.3% +/- 2.4% (CT), respectively. The CAS planning station provided a tunnel location that was 1.3 +/- 1.0 mm (0.3 to 2.5 mm) away from the actual femoral ACL insertion. The tibial tunnel was placed according to the copper wire markers and was found to be at 46.2% +/- 2.8% (roentgenograms) and 45.4% +/- 2.1% (CT). No statistical differences between position in CT and roentgenograms could be detected (P >.05). CONCLUSIONS: The compared methodologies showed similar locations of the ACL insertions, assuring accurate preoperative planning with the CAS system. However, the CAS system requires adjustment to each individual knee anatomy.

Accuracy of anterior cruciate ligament tunnel placement with an active robotic system: a cadaveric study.

PURPOSE: The objective of this study was to evaluate the accuracy of tunnel placement for ACL reconstruction performed with an active robotic system. TYPE OF STUDY: Cadaveric analysis. METHODS: A reference screw containing 4 fiducials was placed in the femur and tibia of 13 fresh-frozen cadaveric knees. A preoperative plan was developed using images from 3-dimensional computed tomography reconstructions of the knee. The active robotic system then drilled the tunnels. The location and direction of each planned tunnel in the femur and tibia were determined from the preoperative plan. To compare these parameters postoperatively, a mechanical digitizer and a tunnel plug were used. The deviation in location and direction between the planned and drilled tunnel was determined. RESULTS: In preliminary trials, the tibial tunnel was located inaccurately because slippage of the drill bit occurred on the bone at the start of tunnel drilling. This was minimized by decreasing the feed rate of the robot by 75%. For the remaining 10 knees, deviations with respect to the preoperative plan were found of 2.0 +/- 1.2 mm and 1.1 degrees +/- 0.7 degrees for the intra- articular tibial tunnel location and direction, respectively. For the femur, the deviations were 1.3 +/- 0.9 mm for the tunnel location (intra-articular) and 1.0 degrees +/- 0.6 degrees for the tunnel direction. CONCLUSIONS: The active robotic system is highly accurate for tunnel placement during ACL reconstruction, meaning that the robot drills the tunnels very close to the surgeon's plan. Comparison to a control group of surgeons could not be made because no preoperative plan is usually created in traditional surgery. However, accuracy values in this study were found to be below the values for precision of repeated tunnel placements reported in the literature.

Treatment of articular cartilage defects with the autologous chondrocyte transplantation (ACT).

Symptomatic chondral lesions in the knee remain a problem for young sportsmen and pose a difficult management issue for orthopedic surgeons and patients alike. Damaged articular cartilage has a limited potential for healing and can lead to premature arthritis. Articular defects larger than 2 mm to 4 mm in diameter rarely heal. Neither articular cartilage possesses a lymphatic drainage, a sufficient blood supply, nor neural elements. Also, they are sheltered even from immunological recognition, because of the extracellular matrix surrounding the chondrocyte.

Normal and pathological MR findings in osteochondral autografts with longitudinal follow-up.

The purpose of this study was to analyze normal and pathological MR findings in osteochondral autograft transfer systems (OATS) of the knee and ankle in the longitudinal follow-up and in relation to the clinical findings. MR imaging was performed in 55 patients (21 females: 34 males; mean age 34.5+/-12.1 years) after OATS procedures in the knee (n=45) and ankle (n=10). MR sequences were obtained with and without intravenous Gd-DTPA administration within the first year post-operatively, in 30 patients within the second and in 13 patients in the third year. One hundred and five OATS cylinders were implanted. MR findings consistent with osteonecroses were detected in eight cylinders (n=6 in the knee and n=2 in the ankle) in six patients; four out of eight were demonstrated during the first year and four/eight in the second year. Edema around and/or in the cylinders was found in 28/55 of the patients within the first year, five/30 in the second year and in two/13 in the third year. No substantial changes in the cartilage signal intensity or the cartilage-cartilage interface were demonstrated in the longitudinal follow-up within the first three years. Clinical and MR findings were not consistently associated in particular in the patients with osteochondral autograft necroses.

Variants of the superior labrum and labro-bicipital complex: a comparative study of shoulder specimens using MR arthrography, multi-slice CT arthrography and anatomical dissection.

The purpose of the present study was to evaluate the anatomical variability of the superior labrum and to compare the value of MR arthrography and multi-slice CT arthrography in the diagnosis of variants of the labro-bicipital complex. Forty-three human shoulder specimens (age range and mean age at death, 61-89 years and 78.3 years) were examined with the use of MR arthrography and multi-slice CT arthrography prior to joint exploration and macroscopic inspection of the superior labrum and labro-bicipital complex. Two radiologists evaluated MR and CT arthrograms, and the results were compared with macroscopic assessments. Anatomical dissection of all shoulder specimens revealed a sublabral recess in 32/43 (74%) cases. The attachment of the superior labrum was categorised as type 1 in ten (23%) cases, as type 2 in eight (19%), as type 3 in ten (23%), and as type 4 in 14 (33%) cases. One superior labrum showed detachment consistent with a superior labral anteroposterior (SLAP) type 3 lesion. On MR arthrography and CT arthrography the attachment of the superior labrum was categorised in concordance with macroscopic assessments in 79% and 84% of cases, respectively. The anteroposterior extension of sublabral recesses was accurately determined with MR and CT arthrography in 59% and 81% of cases, respectively. The attachment of the superior labrum shows considerable variability. Thus, exact depiction of variants is essential in order to avoid the false positive diagnosis of a superior labral tear (SLAP or Andrews lesion). Both, MR arthrography and multi-slice CT arthrography were effective in the detection and classification of sublabral recesses.

Anterior shoulder instability: accuracy of MR arthrography in the classification of anteroinferior labroligamentous injuries.

PURPOSE: To retrospectively evaluate the accuracy of magnetic resonance (MR) arthrography in the classification of anteroinferior labroligamentous injuries by using arthroscopy as the reference standard. MATERIALS AND METHODS: Ethical committee approval and informed consent were obtained. MR arthrograms obtained in 205 patients, including a study group of 104 patients (74 male and 30 female; mean age, 28.2 years) with arthroscopically proved labroligamentous injuries and a control group of 101 patients (65 male and 36 female; mean age, 31.4 years) with intact labroligamentous complex, were reviewed in random order. MR arthrograms were analyzed for the presence and type (Bankart, anterior labral periosteal sleeve avulsion [ALPSA], Perthes, glenolabral articular disruption [GLAD], or nonclassifiable lesion) of labroligamentous injuries by two radiologists in consensus. Results were compared with arthroscopic findings. Sensitivity, specificity, accuracy, and corresponding 95% confidence intervals for the detection and classification of anteroinferior labroligamentous lesions with MR arthrography were calculated. RESULTS: At arthroscopy, 104 anteroinferior labroligamentous lesions were diagnosed, including 44 Bankart lesions, 22 ALPSA lesions, 12 Perthes lesions, and three GLAD lesions. Twenty-three labral lesions were nonclassifiable at arthroscopy, all of which occurred after a history of chronic instability. Nineteen (83%) of these 23 lesions were also nonclassifiable at MR arthrography. With arthroscopy used as the reference standard, labroligamentous lesions were detected and correctly classified at MR arthrography with sensitivities of 88% and 77%, specificities of 91% and 91%, and accuracies of 89% and 84%, respectively. Bankart, ALPSA, and Perthes lesions were correctly classified in 80%, 77%, and 50% of cases, respectively. The three GLAD lesions were all correctly assessed. CONCLUSION: MR arthrography is accurate in enabling classification of acute and chronic anteroinferior labroligamentous injuries, although correct interpretation of Perthes lesions remains difficult.

Anatomy and function of the glenohumeral ligaments in anterior shoulder instability.

The anatomy of the glenohumeral ligaments has been shown to be complex and variable and their function is highly dependent on the position of the humerus with respect to the glenoid. The superior glenohumeral ligament with the coracohumeral ligament was shown to be an important stabilizer in the inferior direction, even though the coracohumeral ligament is much more robust than the superior glenohumeral ligament. The middle glenohumeral ligament provides anterior stability at 45 degrees and 60 degrees abduction whereas the inferior glenohumeral ligament complex is the most important stabilizer against anteroinferior shoulder dislocation. Therefore, this component of the capsule is the most frequently injured structure. An appropriate surgical procedure to repair the inferior glenohumeral ligament complex after shoulder dislocation must be considered. In addition, a detached labrum can lead to recurrent anterior instability and a compromised inferior glenohumeral ligament complex. However, additional capsular injury usually is necessary to allow anterior dislocation.

Diagnostic performance of MR arthrography in the assessment of superior labral anteroposterior lesions of the shoulder.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of MR arthrography in the assessment of superior labral anteroposterior (SLAP) lesions of the shoulder with emphasis on the classification of SLAP lesions. MATERIALS AND METHODS: Two hundred sixty-five MR arthrograms including 68 MR arthrograms of patients with arthroscopically proven SLAP lesions of the shoulder and 197 MR arthrograms of patients with an intact superior labrum and biceps anchor were retrospectively reviewed in random order. MR arthrography was performed using triplanar T1-weighted spin-echo sequences and a coronal oblique T2-weighted fast spin-echo sequence. MR arthrograms were evaluated by two radiologists with agreement by consensus, and the results were compared with arthroscopic findings. RESULTS: Of 68 SLAP lesions, seven (10%) were arthroscopically classified as type I, 41 (60%) as type II (including 20 type II lesions with coexisting Bankart lesions [29%]), 14 (21%) as type III, and six (9%) as type IV. Compared with arthroscopy as the gold standard, MR arthrography showed a sensitivity of 82% and a specificity of 98% for the overall detection of SLAP lesions. MR arthrographic grading and arthroscopic grading were concurrent in 45 (66%) of 68 arthroscopic diagnoses. Of the surgically confirmed SLAP lesions, involvement of the biceps insertion and SLAP type II lesions with coexisting Bankart lesions were assessed correctly in 75% and 95% of cases, respectively. CONCLUSION: MR arthrography is a highly effective method for the detection of SLAP lesions, but this technique is limited in the classification of different types of SLAP lesions. However, for preoperative planning MR arthrography provides accurate information about the stability of the biceps insertion and the presence of associated anteroinferior labral injuries.

Glenohumeral translations are increased after a type II superior labrum anterior-posterior lesion: a cadaveric study of severity of passive stabilizer injury.

The effects of simulated type II superior labrum anterior-posterior (SLAP) lesions were studied to determine whether the severity of the lesion affected glenohumeral joint translations. A robotic/universal force-moment sensor testing system was used to simulate load-and-shift tests by applying an anterior or posterior load of 50 N to each shoulder. The apprehension test for anterior instability was simulated by applying an anterior load of 50 N with an external rotation torque of 3 Nm at 30 degrees and 60 degrees of abduction. This loading protocol was repeated after creating two type II SLAP lesions of different severity. In the first the superior labrum and the biceps anchor were elevated subperiosteally from the glenoid bone (SLAP-II-1), and in the second the biceps anchor was completely detached (SLAP-II-2). Statistical analysis was performed with a 2-factor repeated-measures analysis of variance followed by multiple contrasts, and the significance level was set at P <.05. At 30 degrees of abduction, anterior translation of the vented joint from anterior loading was 18.5 +/- 8.5 mm. It was significantly increased (26.2 +/- 6.5 mm, P =.03), after the SLAP-II-2 lesion and compared with the SLAP-II-1 lesion (25.0 +/- 6.8 mm, P =.03). Increases in anterior translations at 60 degrees of abduction were not significantly differ in comparison to the two SLAP lesions. Inferior translation also resulted from anterior loading. At 30 degrees of abduction in the vented joint, it was 3.8 +/- 4.0 mm and was significantly increased (8.5 +/- 5.4 mm, P =.05) after the SLAP-II-2 lesion, no different than that after the SLAP-II-1 lesion (7.8 +/- 4.9 mm). No significant increases in anterior translation occurred in response to the combined loading condition between the two SLAP lesions. Glenohumeral translation was increased, regardless of severity, after simulation of type II SLAP lesions. During stabilizing surgical interventions, passive stabilizers that are injured in the type II SLAP lesion should be considered as well as dynamic activity in the tendon of the long head of the biceps brachii.

Large osteochondral defects of the femoral condyle: press-fit transplantation of the posterior femoral condyle (MEGA-OATS).

BACKGROUND AND AIMS: Large osteochondral defects in the weight-bearing zone of the knee remain a challenging therapeutic problem. Surgical options include drilling, microfracturing, and transplantation of osteochondral plugs but are often insufficient for the treatment of large defects of the femoral condyle. PATIENTS AND METHODS: Large osteochondral defects of the femoral condyle (mean defect size 7.2 cm(2) range 3-20) were treated by transplantation of the autologous posterior femoral condyle. Between 1984 and 2000, 29 patients were operated on: in 22 the medial, in 6 the lateral femoral condyle, and in one the trochlear groove was grafted. Thirteen patients underwent simultaneous high tibial valgus osteotomy. In the first series (1984-1999) the graft was temporarily fixed with a screw ( n=12), but from 1999 we used a newly developed press-fit technique ( n=17) avoiding screw fixation of the graft. The operative technique comprising graft harvest, defect preparation, transplantation, and fixation is described. Patients were clinically evaluated using the Lysholm score, and magnetic resonance imaging with intravenous contrast was performed 6 and 12 weeks after surgery (mean follow-up 17.7 months (range 3-46). RESULTS: Pain and swelling were reduced in 26 patients. Three patients of the first series reported persistent problems and were subjectively not satisfied. The mean Lysholm score rose from preoperatively 52 to 77 points after 3 months, 74 after 6, 88 after 12, and 95 after 18. Magnetic resonance imaging showed good graft viability in all cases. We saw one arthrofibrosis after 6 months but noted no problems related to the loss of the missing posterior condyle. CONCLUSION: Large osteochondral defects of the femoral condyle can be treated by transplantation of the autologous posterior femoral condyle. The use of only one osteochondral piece renders better approximation of the femoral cartilage curvature and thus joint congruence than in mosaic plasty. However, whether loss of the posterior condyle has a long-term negative impact on the knee joint remains to be elucidated.