Entangling single atoms over 33 km telecom fibre.

Quantum networks promise to provide the infrastructure for many disruptive applications, such as efficient long-distance quantum communication and distributed quantum computing1,2. Central to these networks is the ability to distribute entanglement between distant nodes using photonic channels. Initially developed for quantum teleportation3,4 and loophole-free tests of Bell's inequality5,6, recently, entanglement distribution has also been achieved over telecom fibres and analysed retrospectively7,8. Yet, to fully use entanglement over long-distance quantum network links it is mandatory to know it is available at the nodes before the entangled state decays. Here we demonstrate heralded entanglement between two independently trapped single rubidium atoms generated over fibre links with a length up to 33 km. For this, we generate atom-photon entanglement in two nodes located in buildings 400 m line-of-sight apart and to overcome high-attenuation losses in the fibres convert the photons to telecom wavelength using polarization-preserving quantum frequency conversion9. The long fibres guide the photons to a Bell-state measurement setup in which a successful photonic projection measurement heralds the entanglement of the atoms10. Our results show the feasibility of entanglement distribution over telecom fibre links useful, for example, for device-independent quantum key distribution11-13 and quantum repeater protocols. The presented work represents an important step towards the realization of large-scale quantum network links.

Fluorescence Enhancement of Single V2 Centers in a 4H-SiC Cavity Antenna.

Solid state quantum emitters are a prime candidate in distributed quantum technologies since they inherently provide a spin-photon interface. An ongoing challenge in the field, however, is the low photon extraction due to the high refractive index of typical host materials. This challenge can be overcome using photonic structures. Here, we report the integration of V2 centers in a cavity-based optical antenna. The structure consists of a silver-coated, 135 nm-thin 4H-SiC membrane functioning as a planar cavity with a broadband resonance yielding a theoretical photon collection enhancement factor of ∼34. The planar geometry allows us to identify over 20 single V2 centers at room temperature with a mean (maximum) count rate enhancement factor of 9 (15). Moreover, we observe 10 V2 centers with a mean absorption line width below 80 MHz at cryogenic temperatures. These results demonstrate a photon collection enhancement that is robust to the lateral emitter position.

Arthroscopic defect size measurement in osteochondral lesions of the talus underestimates the exact defect size and size measurement with arthro-MRI (MR-A) and high-resolution flat-panel CT-arthro imaging (FPCT-A).

PURPOSE: The size of osteochondral lesions of the talus (OLTs) is highly relevant for their treatment. In addition to intraoperative measurement of defect size, preoperative planning by means of magnetic resonance imaging (MRI) or computed tomography (CT) is crucial. METHODS: Four defects of different sizes and depths were created on the talar joint surface in 14 cadaver feet. All defects were evaluated, both arthroscopically and via arthrotomy with a probe. Arthro-MRI (MR-A) and high-resolution flat-panel CT arthro scans (FPCT-A) were acquired. Length, width, and depth were measured for every defect and the defect volume was calculated. To determine the exact defect size, each talar defect was filled with plastic pellets to form a cast and the casts were scanned using FPCT to create a 3D multiplanar reconstruction data set. Finally, the surgically measured values were compared with the radiological values and the exact defect size. RESULTS: Overall, the surgically measured values (both arthroscopic and open) underestimated the exact defect size (p < 0.05). Arthroscopically determined defect length and width showed the largest deviation (p < 0.05) and underestimated the size in comparison with MR-A and FPCT-A. The FPCT-A measurements demonstrated higher correlation with both the arthroscopic and open surgical measurements than did the MR-A measurements (p < 0.05). CONCLUSION: The exact defect size is underestimated on intraoperative measurement, in both arthroscopic and open approaches. Arthroscopic defect size measurement underestimates defect size in comparison with MR-A and FPCT-A. FPCT-A was shown to be a reliable imaging technique that allows free image reconstruction in every plane and could be considered as the new reference standard for preoperative evaluation of defect size in OLT.

Sustained superiority in KOOS subscores after matrix-associated chondrocyte implantation using spheroids compared to microfracture.

PURPOSE: To evaluate the safety and efficacy of matrix-associated autologous chondrocyte implantation (ACI) using spheroids in comparison to arthroscopic microfracture for the treatment of symptomatic cartilage defects of the knee. METHODS: In a prospective multicenter-controlled trial, patients aged between 18 and 50 years, with single symptomatic focal cartilage defects between 1 and 4 cm2 (mean 2.6 ± 0.8, median 2.75, range 1.44-5.00) in the knee were randomized to treatment with ACI with spheroids (n = 52) or microfracture (n = 50). Primary clinical outcome was assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS). Analyses were performed in a defined hierarchical manner where outcomes of ACI were first compared to baseline values followed by a comparison to the microfracture group with repeated-measures ANCOVA with a non-inferiority approach. Subgroup analyses were performed to investigate the influence of age and defect size on the overall KOOS. Secondary clinical outcomes were the magnetic resonance observation of cartilage repair tissue (MOCART), modified Lysholm score and International Knee Documentation Committee (IKDC) examination form. Safety data focused on adverse events. Here the 5 years results are presented at which there were 33 observed cases in the ACI group and 30 in the microfracture group. RESULTS: The overall KOOS and its five subscores were significantly improved compared to baseline for both the ACI and microfracture group. Non-inferiority of ACI to microfracture was confirmed for the overall KOOS and the subscores, while for the subscores activities of daily living, quality of life and sports and recreation of the threshold for superiority was passed. In the ACI group, a notably more rapid initial improvement of the KOOS was found at three months for the older age group compared to the younger age group and the microfracture group. No other differences were found based on age or defect size. In addition, clinical improvement was found for the MOCART, modified Lysholm and IKDC examination form both the ACI and microfracture group. No safety concern related to either treatment was observed. CONCLUSION: This study confirms the safety and efficacy of matrix-associated ACI with spheroids at a mid to long-term follow-up. Non-inferiority of ACI to microfracture was confirmed for the overall KOOS and all subscores, while superiority was reached for the subscores activities of daily living, quality of life and sports and recreation in the ACI group. This underlines the importance of ACI for the young and active patients. LEVEL OF EVIDENCE: I.

High degree of consensus amongst an expert panel regarding focal resurfacing of chondral and osteochondral lesions of the femur with mini-implants.

INTRODUCTION: The rationale for the use of mini-implants for partial resurfacing in the treatment of femoral chondral and osteochondral lesions is still under debate. The evidence supporting best practise guidelines is based on studies with low-level evidence. A consensus group of experts was convened to collaboratively advance towards consensus opinions regarding the best available evidence. The purpose of this article is to report the resulting consensus statements. METHODS: Twenty-five experts participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted via an online survey of two rounds, for initial agreement and comments on the proposed statements. An in-person meeting between the panellists was organised during the 2022 ESSKA congress to further discuss and debate each of the statements. A final agreement was made via a final online survey a few days later. The strength of consensus was characterised as: consensus, 51-74% agreement; strong consensus, 75-99% agreement; unanimous, 100% agreement. RESULTS: Statements were developed in the fields of patient assessment and indications, surgical considerations and postoperative care. Between the 25 statements that were discussed by this working group, 18 achieved unanimous, whilst 7 strong consensus. CONCLUSION: The consensus statements, derived from experts in the field, represent guidelines to assist clinicians in decision-making for the appropriate use of mini-implants for partial resurfacing in the treatment of femoral chondral and osteochondral lesions. LEVEL OF EVIDENCE: Level V.

Revision of inlay resurfacing prosthesis with patellar realignment surgery and a new inlay prosthesis for persistent patellofemoral pain und patella subluxation.

We present the case of a 35-year-old patient who underwent inlay patellofemoral arthroplasty (I-PFA) followed by secondary patellar realignment surgery and inlay-to-inlay revision. Revision was performed because of ongoing pain, crepitation, and lateral subluxation of the patella. The original patella component (30-mm button) was replaced with a 35-mm dome, while the Hemi-Cap Wave® (7 × 5 mm) I-PFA was replaced with the Hemi-Cap Kahuna® (10 × 5 mm). At the 1-year follow-up, the clinical symptoms were resolved. Radiography revealed an aligned patellofemoral compartment with no signs of loosening. Inlay-to-inlay PFA revision appears to be a reasonable alternative to total knee arthroplasty and conversion to onlay-PFA (O-PFA) for symptomatic patients with primary I-PFA failure. Thorough patellofemoral evaluation and appropriate patient and implant selection are key for successful I-PFA, while additional procedures for patellar realignment may also be required for satisfactory long-term outcomes.

Femoral condyle resurfacing using an inlay metal implant: low revision rate of 266 patients in a 5-10 years follow-up.

PURPOSE: To assess the clinical outcome and survival of an inlay resurfacing prosthesis for focal femoral condyle chondral and osteochondral defects. METHODS: Two hundred sixty-six patients (mean age, 38.25 years; range 25-56 years) with symptomatic femoral condyle chondral and osteochondral defects were reviewed. The mean follow-up period was 7.3 years (range 5-10 years). The medial femoral condyle was involved in 229 and the lateral condyle in 37 patients. Previous cartilage surgery was done in 235 patients. All patients were treated with focal femoral condyle resurfacing with the HemiCAP® device. The preoperative and the last follow-up values of the Knee Injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS), 36-item Short Form Survey (SF-36) and Visual Analogue Scale (VAS) were examined. Complications, reoperation rate and survival were analyzed. RESULTS: At the last follow-up, all clinical score values showed significant improvement as compared with the corresponding preoperative values (p < 0.001). Age presented a negative correlation with KOOS (p = 0.03) and SF-36 improvement (p = 0.014). Kellgren-Lawrence grade influenced OKS (p = 0.036). BMI, gender, side, medial or lateral condyle and size did not affect the outcome. Patients who had previous biological cartilage procedures demonstrated better clinical improvement in comparison with those that did not have prior surgery (p < 0.05). Survival was 96.2% at 10 years, using as endpoint implant revision or/and progression of osteoarthritis. The cumulative hazard for any-reason reoperation was 12.0%. CONCLUSIONS: Femoral condyle resurfacing using the HemiCAP® device is an effective treatment option to address focal chondral and osteochondral defects. It can be successfully used either as a primary procedure or after prior biological cartilage reconstruction. Subjective clinical outcomes are expected to be good to excellent in mid- to long term, while reoperation and revision rates are low. Progression of osteoarthritis is the most common mode of failure; thus, patient selection is very important. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Discharging the medial knee compartment: comparison of pressure distribution and kinematic shifting after implantation of an extra-capsular absorber system (ATLAS) and open-wedge high tibial osteotomy-a biomechanical in vitro analysis.

PURPOSE: Young and active patients suffering early degenerative changes of the medial compartment with an underlying straight-leg axis do face a therapeutical gap as unloading of the medial compartment cannot be achieved by high tibial osteotomy. Extracapsular absorbing implants were developed to close this existing therapeutical gap. Purpose of the present cadaveric biomechanical study was to compare the unloading effect of the knee joint after implantation of an extra-articular absorber system (ATLAS) in comparison to open-wedge high tibial osteotomy (OW-HTO) under physiological conditions. The hypothesis of the study was that implantation of an extra-capsular absorber results in an unloading effect comparable to the one achievable with OW-HTO. METHODS: Eight fresh-frozen cadaveric knees were tested under isokinetic flexion-extension motions and physiological loading using a biomechanical knee simulator. Tibiofemoral area contact and peak contact pressures were measured using pressure-sensitive film in the untreated medial compartment. The tibiofemoral superior-inferior, latero-medial translation and varus/valgus rotation were measured with a 3D tracking system Polaris. Pressures and kinematics changes were measured after native testing, ATLAS System implantation and OW-HTO (5° and 10° correction angles) performed with an angular stable internal fixator (TomoFix). RESULTS: The absorber device decreased the pressure in the medial compartment near full extension moments. Implantation of the ATLAS absorbing system according to the manufacturers' instruction did not result in a significant unloading effect. Deviating from the surgery manual provided by the manufacturer the implantation of a larger spring size while applying varus stress before releasing the absorber resulted in a significant pressure diminution. Contact pressure decreased significantly Δ0.20 ± 0.04 MPa p = 0.044. Performing the OW-HTO in 5° correction angle resulted in significant decreased contact pressure (Δ0.25 ± 0.10 MPa, p = 0.0036) and peak contact pressure (Δ0.39 ± 0.38 MPa, p = 0.029) compared with the native test cycle. With a 10° correction angle, OW-HTO significantly decreased area contact pressure by Δ0.32 ± 0.09 MPa, p = 0.006 and peak contact pressure by Δ0.48 ± 0.12 MPa, p = 0.0654 compared to OW-HTO 5°. Surgical treatment did not result in kinematic changes regarding the superior-inferior translation of the medial joint section. A significant difference was observed for the translation towards the lateral compartment for the ATLAS system Δ1.31 ± 0.54 MPa p = 0.022 and the osteotomy Δ3.51 ± 0.92 MPa p = 0.001. Furthermore, significant shifting varus to valgus rotation of the treated knee joint was verified for HTO 5° about Δ2.97-3.69° and for HTO 10° Δ4.11-5.23° (pHTO 5 = 0.0012; pHTO 10 = 0.0007) over the entire extension cycle. CONCLUSION: OW-HTO results in a significant unloading of the medial compartment. Implantation of an extra-capsular absorbing device did not result in a significant unloading until the implantation technique was applied against the manufacturer's recommendation. While the clinical difficulty for young and active patients with straight-leg axis and early degenerative changes of the medial compartment persists further biomechanical research to develop sufficient unloading devices is required.

Preexisting and treated concomitant ankle instability does not compromise patient-reported outcomes of solitary osteochondral lesions of the talus treated with matrix-induced bone marrow stimulation in the first postoperative year: data from the German Cartilage Registry (KnorpelRegister DGOU).

PURPOSE: The purpose of this study was to compare the subjective ankle function within the first year following matrix-induced bone marrow stimulation (M-BMS) of patients with a solitary osteochondral lesion of the talus (OCLT) with and without concomitant chronic ankle instability (CAI). METHODS: Data from the German Cartilage Registry (KnorpelRegister DGOU) for 78 patients with a solitary OCLT and a follow-up of at least 6 months were included. All patients received M-BMS for OCLT treatment. The cohort was subdivided into patients with OCLT without CAI treated with M-BMS alone (n = 40) and patients with OCLT and CAI treated with M-BMS and additional ankle stabilisation (n = 38). The Foot and Ankle Ability Measure (FAAM), the Foot and Ankle Outcome Score (FAOS), and the Numeric Rating Scale for Pain (NRS) were used to assess patient-reported outcomes (median (minimum-maximum)). RESULTS: From preoperatively to 12 months postoperatively, patients with OCLT without CAI treated with M-BMS alone had a significant improvement of all subscales in the FAAM [activity of daily living 64.3 (10-100) to 88.1 (39-100); sports 34.4 (0-100) to 65.6 (13-94), functional activities of daily life 50 (0-90) to 80 (30-100), functional sports 30 (0-100) to 70 (5-100)] and FAOS [pain 61.1 (8-94) to 86.1 (50-100), symptoms 60.7 (18-96) to 76.8 (29-100), activities of daily living 72.1 (24-100) to 91.9 (68-100), sport/recreational activities 30.0 (0-70) to 62.5 (0-95), quality of life 31.3 (6-50) to 46.9 (19-100)]. Within the first year, patients with OCLT and CAI treated with M-BMS and ankle stabilisation also showed significant improvement in the FAAM [activity of daily living 68.8 (5-99) to 90.5 (45-100); sports 32.8 (0-87.5) to 64.1 (0-94), functional activities of daily life 62.5 (25-100) to 80 (60-90), functional sports 30 (0-100) to 67.5 (0.95)] and the FAOS [pain 66.7 (28-92) to 87.5 (47-100), symptoms 57.1 (29-96) to 78.6 (50-100), activities of daily living 80.1 (25-100) to 98.5 (59-100), sport/recreational activities 35.0 (0-100) to 70.0 (0-100), quality of life 25.0 (0-75) to 50.0 (19-94)]. The pain level decreased significantly in both groups. No significant difference was found between both groups regarding the subscales of FAAM, FAOS and the NRS 1 year postoperatively. CONCLUSION: Improvements in subjective ankle function, daily life activities and sports activities were observed within the first year following M-BMS. Our results suggest that preexisting and treated ankle instability did not compromise subjective outcome in patients treated with M-BMS in the first postoperative year. LEVEL OF EVIDENCE: Level IV.

The lack of retropatellar resurfacing at index surgery is significantly associated with failure in patients following patellofemoral inlay arthroplasty: a multi-center study of more than 260 patients.

PURPOSE: To evaluate the clinical outcomes of patients with a minimum 2-year follow-up following contemporary patellofemoral inlay arthroplasty (PFIA) and to identify potential risk factors for failure in a multi-center study. METHODS: All patients who underwent implantation of PFIA between 09/2009 and 11/2016 at 11 specialized orthopedic referral centers were enrolled in the study and were evaluated retrospectively at a minimum 2-year follow-up. Clinical outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Tegner Scale, the visual analogue scale (VAS) for pain, and subjective patient satisfaction. Pre- and perioperative risk factors were compared among failures and non-failures to determine potential risk factors. RESULTS: A total of 263 patients (85% follow-up rate) could be enrolled. The mean age at the time of index surgery was 49 ± 12 years with a mean postoperative follow-up of 45 ± 18 months. The overall failure rate was 11% (28 patients), of which 18% (5 patients) were patients with patella resurfacing at index surgery and 82% (23 patients) were patients without initial patella resurfacing. At final follow-up, 93% of the patients who did not fail were satisfied with the procedure with a mean transformed WOMAC Score of 84.5 ± 14.5 points, a mean KOOS Score of 73.3 ± 17.1 points, a mean Tegner Score of 3.4 ± 1.4 points and a mean VAS pain of 2.4 ± 2.0 points. An increased BMI was significantly correlated with a worse postoperative outcome. Concomitant procedures addressing patellofemoral instability or malalignment, the lack of patellofemoral resurfacing at the index surgery and a high BMI were significantly correlated with failure in our patient cohort. CONCLUSION: Patellofemoral inlay arthroplasty shows high patient satisfaction with good functional outcomes at short-term follow-up and thus can be considered a viable treatment option in young patients suffering from isolated patellofemoral arthritis. Patellar resurfacing at index surgery is recommended to decrease the risk of failure. LEVEL OF EVIDENCE: Retrospective case series, Level IV.

The novel dynamic MPFL-reconstruction technique: cheaper and better?

PURPOSE: Reconstruction of the medial patellofemoral ligament (MPFL) is an established procedure to restore patellar stability. Aim of this study is to evaluate the results of a dynamic MPFL reconstruction technique in a large university hospital setting. METHODS: Two hundred and thirteen consecutive patients with 221 knees were surgically treated for recurrent lateral patellar dislocation. All patients obtained dynamic reconstruction of the MPFL with detachment of the gracilis tendon at the pes anserinus while maintaining the proximal origin at the gracilis muscle. Patellar fixation was performed by oblique transpatellar tunnel transfer. Follow-up data including Kujala and BANFF score, pain level as well as recurrent patella instability were collected at a minimum follow-up of 2 years. RESULTS: Follow-up could be obtained from 158 patients (71%). The mean follow-up time was 5.4 years. Mean pain level was 1.9 ± 2.0 on the VAS. Mean Kujala score was 78.4 ± 15.5. Mean BANFF score was 62.4 ± 22.3. MPFL-reconstructions that were performed by surgeons with a routine of more than ten procedures had a significantly shorter surgical time 52.3 ± 17.6 min. Male patients yielded higher satisfaction rates and better clinical scores compared to females. Complications occurred in 27.2% of procedures, 20.9% requiring revision surgery of which were 9.5% related to recurrent patellar instability. 78% of all patients indicated they would undergo the procedure again. CONCLUSION: Dynamic MPFL reconstruction presents a reproducible procedure with increased complication rates, inferior to the results of static reconstruction described in the literature. Despite, it appears to be an efficient procedure to restore patellar stability in a large university hospital setting, without the necessity for intraoperative fluoroscopy. TRIAL REGISTRATION: The study was registered in ClinicalTrials.gov with the registration number NCT04438109 on June 18th 2020.

[Guidelines for the treatment of unicompartmental cartilage defects of the knee-Cartilage repair, osteotomy, mini-implant or arthroplasty?] / Leitfaden unikompartimenteller Gelenkknorpelschaden am Knie ­ Knorpelersatz, Osteotomie, Mini-Implantat oder Prothese?

The treatment of unicompartmental cartilage defects offers a large variety of therapeutic options. With help of an algorithm, decision-making for the most suitable treatment approach is supported. Correction of malalignment is key for successful treatment. Defect size, influencing factors such as "age" and prior treatments play an important role in choosing the most appropriate operative treatment option.

Long-Distance Distribution of Atom-Photon Entanglement at Telecom Wavelength.

Entanglement between stationary quantum memories and photonic channels is the essential resource for future quantum networks. Together with entanglement distillation, it will enable efficient distribution of quantum states. We report on the generation and observation of entanglement between a ^{87}Rb atom and a photon at telecom wavelength transmitted through up to 20 km of optical fiber. For this purpose, we use polarization-preserving quantum frequency conversion to transform the wavelength of a photon entangled with the atomic spin state from 780 nm to the telecom S band at 1522 nm. We achieve an unprecedented external device conversion efficiency of 57% and observe an entanglement fidelity between the atom and telecom photon of ≥78.5±0.9% after transmission through 20 km of optical fiber, mainly limited by decoherence of the atomic state. This result is an important milestone on the road to distribute quantum information on a large scale.

Safety and efficacy of matrix-associated autologous chondrocyte implantation with spheroid technology is independent of spheroid dose after 4 years.

PURPOSE: The aim of this study was to investigate the effect of product dose in autologous chondrocyte implantation (ACI) for the treatment of full-thickness cartilage defects of the knee and to assess its influence on clinical and morphological mid-term outcome. METHODS: Seventy-five patients were included in this single-blind, randomised, prospective, controlled clinical trial. Patients were assigned randomly to three different dose groups [low (3-7 spheroids/cm2), medium (10-30 spheroids/cm2), or high (40-70 spheroids/cm2)] and assessed using standardised clinical and morphological scoring systems (KOOS, IKDC, MOCART) for 4 years following the intervention. RESULTS: The analysis population comprised 75 patients (22 women, 53 men) aged 34 ± 9 years. Defect sizes ranged from 2 to 10 cm2 following intraoperative debridement. The assessment of the primary variable 'overall KOOS' showed a statistically significant improvement, compared with baseline, for each dose group, i.e., at baseline the mean 'overall KOOS' scores were 60.4 ± 13.6, 59.6 ± 15.4, and 51.1 ± 15.4 for the low-, medium-, and high-dose groups, respectively, and 57.0 ± 15.2 for 'all patients'. After 48 months those values improved to 80.0 ± 14.7, 84.0 ± 14.9, and 66.9 ± 21.5 in the respective dose groups and 77.1 ± 18.6 for 'all patients'. Pairwise comparisons of these dose groups did not reveal any statistically significant differences. Likewise, assessment of the subjective IKDC score revealed no statistically significant differences between the three dose groups up to the 48-month visit. However, between 12 and 48 months there was a low, but steady, improvement in the low-dose group and a substantial amelioration in the medium-dose group. The mean MOCART total scores 3 months after treatment were 59.8 ± 10.9, 64.5 ± 10.3, and 64.7 ± 9.4 for the low-, medium-, and high-dose groups, and 62.9 ± 10.3 for 'all patients'; 48 months after treatment these were 73.9 ± 13.1, 78.0 ± 12.4, and 74.3 ± 14.0 for the respective dose groups and 75.5 ± 13.1 for 'all patients'. CONCLUSIONS: Results of this study confirm the efficacy and safety of the applied "advanced therapy medicinal product"; no dose dependence was found either for the incidence or for the severity of any adverse reactions. All doses applied in the present study led to significant clinical improvement over time and can therefore be regarded as effective doses. The influence of product doses in the range investigated seems to be low and can be neglected. Thus, the authorised dose range of 10-70 spheroids/cm2 confirmed by this clinical trial offers a broad therapeutic window for the surgeon applying the product, thereby reducing the risk of over- or underdosing. LEVEL OF EVIDENCE: I.

Concomitant ankle instability has a negative impact on the quality of life in patients with osteochondral lesions of the talus: data from the German Cartilage Registry (KnorpelRegister DGOU).

PURPOSE: The purpose of this study was to compare patients with osteochondral lesions of the talus (OCLT) with and without concomitant chronic ankle instability (CAI). METHODS: Data from the German Cartilage Registry (KnorpelRegister DGOU) for 63 patients with a solitary OCLT were used. All patients received autologous matrix-induced chondrogenesis (AMIC) for OCLT treatment. Patients in group A received an additional ankle stabilisation, while patients in group B received AMIC alone. Both groups were compared according to demographic, lesion-related, and therapy-related factors as well as baseline clinical outcome scores at the time of surgery. The Foot and Ankle Ability Measure (FAAM), the Foot and Ankle Outcome Score (FAOS), and the Numeric Rating Scale for Pain (NRS) were used. RESULTS: Patients in group A were older compared to group B [median 34 years (range 20-65 years) vs. 28.5 years (range 18-72 years)]; the rate of trauma-associated OCLTs was higher (89.7% vs. 38.3%); more patients in group A had a previous non-surgical treatment (74.1% vs. 41.4%); and their OCLT lesion size was smaller [median 100 mm2 (range 15-600 mm2) vs. 150 mm2 (range 25-448 mm2)]. Most OCLTs were located medially in the coronary plane and centrally in the sagittal plane in both groups. Patients in group A had worse scores on the FAOS quality-of-life subscale compared to patients in group B. CONCLUSION: Patients with OCLT with concomitant CAI differ from those without concomitant CAI according to demographic and lesion-related factors. The additional presence of CAI worsens the quality of life of patients with OCLT. Patients with OCLT should be examined for concomitant CAI, so that if CAI is present, it can be integrated into the treatment concept. LEVEL OF EVIDENCE: IV.

Clinical outcome and success rates of ACI for cartilage defects of the patella: a subgroup analysis from a controlled randomized clinical phase II trial (CODIS study).

AIM: Cartilage defects of the patella are considered as a problematic entity. Purpose of the present study was to evaluate the outcome of patients treated with autologous chondrocyte implantation (ACI) for cartilage defects of the patella in comparison to patient with defects of the femoral condyles. PATIENTS AND METHODS: 73 patients with a follow-up of 5 years have been included in this subgroup analysis of the randomized controlled clinical trial (RCT). In dependence of defect location, patients were divided into two groups [patella defects (n = 45) and femoral condyle defects (n = 28)]. Clinical outcome was evaluated by the means of the KOOS score at baseline and 6 weeks, 3, 6, 12, 18, 24, 36, 48 and 60 months following ACI. RESULTS: "Responder rate" at 60 months (improvement from baseline of > 7 points in the KOOS score) in patients with patella defects was 86.2%. All scores showed a significant improvement from baseline. While overall KOOS score at 60 months was 81.9 (SD 18.6) points in femoral condyle defects, a mean of 82.6 (SD 14.0) was observed in patella defects (p = 0.2483). CONCLUSION: ACI seems an appropriate surgical treatment for cartilage defects of the patella leading to a high success rate. In this study, the clinical outcome in patients with patellar defects was even better than the already excellent results in patients with defects of the femoral condyle even though the study included relatively large defect sizes for both groups (mean defect size 6.0 ± 1.7 and 5.4 ± 1.6 for femur and patella, respectively).

Infrared laser threshold magnetometry with a NV doped diamond intracavity etalon.

We propose a hybrid laser system consisting of a semiconductor external cavity laser associated to an intra-cavity diamond etalon doped with nitrogen-vacancy color centers. We consider laser emission tuned to the infrared absorption line that is enhanced under the magnetic field dependent nitrogen-vacancy electron spin resonance and show that this architecture leads to a compact solid-state magnetometer that can be operated at room-temperature. The sensitivity to the magnetic field limited by the photonshot-noise of the output laser beam is estimated to be less than 1 pT/Hz. Unlike usual NV center infrared magnetometry, this method would not require an external frequency stabilized laser. Since the proposed system relies on the competition between the laser threshold and an intracavity absorption, such laser-based optical sensor could be easily adapted to a broad variety of sensing applications based on absorption spectroscopy.

Coherent Control and Wave Mixing in an Ensemble of Silicon-Vacancy Centers in Diamond.

Strong light-matter interactions are critical for quantum technologies based on light, such as memories or nonlinear interactions. Solid state materials will be particularly important for such applications due to the relative ease of fabrication of components. Silicon vacancy centers (SiV^{-}) in diamond feature especially narrow inhomogeneous spectral lines, which are rare in solid materials. Here, we demonstrate resonant coherent manipulation, stimulated Raman adiabatic passage, and strong light-matter interaction via the four-wave mixing of a weak signal field in an ensemble of SiV^{-} centers.

Arthroscopic microfracture vs. arthroscopic autologous matrix-induced chondrogenesis for the treatment of articular cartilage defects of the talus.

PURPOSE: Microfracture is an established method to treat osteochondral defects of the talus. The value of the addition of an acellular matrix is still under debate. This study compared the results of arthroscopic microfracture vs. arthroscopic autologous matrix-induced chondrogenesis using a collagen I/III matrix (AMIC) in the management of articular cartilage defects of the talus. METHODS: Patients with a minimum follow-up of 5 years after arthroscopic management for an articular cartilage defect of the talus with either microfracture alone or an additional acellular matrix were matched according to age, sex and BMI. The Hannover Scoring System for the ankle (HSS) and a Visual analog scale (VAS) for pain, function and satisfaction were used to evaluate the clinical outcome. Postoperative MRI was used to assess cartilage repair tissue based on the degree of defect repair and filling of the defect, integration to border zone, surface of the repair tissue, structure of the repair tissue, and subchondral bone alterations. RESULTS: Thirty-two patients (16 microfracture, 16 AMIC) were included. No significant between-group differences were observed in demographic data and preoperative score values. Both groups showed statistically significant improvement when comparing the pre- and postoperative score values. No statistically significant differences were identified between the median values of the groups with the HSS (microfracture: 82 (range 71-96) points; AMIC 88 (range 40-98) points). Accordingly, no significant differences were observed for the VAS pain (microfracture: 0.95 (range 0-3.8); AMIC: 1.0 (range 0-8.5)), VAS function (microfracture: 8.4 (range 3.5-10); AMIC: 9.0 (range 1.5-10)) and VAS satisfaction (microfracture: 8.9 (range 2.8-10); AMIC: 9.45 (range 1.5-10)). MRI showed regeneration of tissue in the treated area without differences between the two groups. CONCLUSION: Good clinical results were observed for arthroscopic microfracture with or without an additional acellular collagen I/III matrix in the treatment for articular cartilage defects of the talus. It appears that for defects as treated in this study, it is not worthwhile adding the collagen I/III matrix to the microfractures. LEVEL OF EVIDENCE: III.

High tibial osteotomy increases patellofemoral pressure if adverted proximal, while open-wedge HTO with distal biplanar osteotomy discharges the patellofemoral joint: different open-wedge high tibial osteotomies compared to an extra-articular unloading device.

PURPOSE: Valgus high tibial osteotomy (HTO) and a recently introduced extra-articular absorber have been shown to efficiently unload the medial compartment of the knee. However, only little is known about the influence of these treatment modalities on biomechanics of the patellofemoral joint. The purpose of this study was to investigate and compare the impact of different HTO techniques and implantation of an extra-articular absorber on patellofemoral contact forces. METHODS: Fourteen fresh frozen cadaveric knees were tested in a specially designed knee simulator that allowed simulation of isokinetic flexion-extension motions under physiological loading. Mean contact pressure (ACP) and peak contact pressure (PCP) of the patellofemoral joint was measured continuously between 0° and 120° of knee flexion using a pressure sensitive film in the following conditions: native, after biplanar medial open-wedge HTO with 5° and 10° correction angle performing an ascending frontal osteotomy of the tibial tuberosity, and after implantation of an extra-articular absorber system (KineSpring®). Including a second testing cycle with a biplanar medial open-wedge HTO with 5° and 10° correction angle performing descending frontal osteotomy of the tibial tuberosity. Values after each procedure were compared to the corresponding values of the native knee. RESULTS: Biplanar proximal osteotomy leaded to a significant increase of retropatellar compartment area contact pressure compared to the first untreated test cycle (Δ 0.04 ± 0.01 MPa, p = 0.04). Similar results were observed measuring peak contact pressure (Δ 1.41 ± 0.15 MPa, p = 0.03). With greater correction angle 5°, respectively, 10° peak and contact pressure increased accordingly. In contrast, the biplanar distal osteotomy group showed significant decrease of pressure values (p = 0.004). The extracapsular, extra-articular absorber had no significant influence on pressure levels in the patellofemoral joint. CONCLUSION: HTO with a proximal biplanar osteotomy of the tuberositas tibia significantly increased patellofemoral pressure conditions depending on the correction angle. In contrast a distally directed biplanar osteotomy diminished these effects while implantation of an extracapsular, extra-articular absorber had no influence on the patellofemoral compartment at all. Consequently, patients with varus alignment with additional retropatellar chondropathia should be treated with a distally adverted osteotomy to avoid further undesirable pressure elevation in the patellofemoral joint.