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.

Patient-specific resurfacing implant knee surgery in subjects with early osteoarthritis results in medial pivot and lateral femoral rollback during flexion: a retrospective pilot study.

PURPOSE: Metallic resurfacing implants have been developed for the treatment of early, small, condylar and trochlear osteoarthritis (OA) lesions. They represent an option for patients who do not fulfill the criteria for unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA) or are too old for biological treatment. Although clinical evidence has been collected for different resurfacing types, the in vivo post-operative knee kinematics remain unknown. The present study aims to analyze the knee kinematics in subjects with patient-specific episealer implants. This study hypothesized that patient-specific resurfacing implants would lead to knee kinematics close to healthy knees, resulting in medial pivot and a high degree of femoral rollback during flexion. METHODS: Retrospective study design. Fluoroscopic analysis during unloaded flexion-extension and loaded lunge was conducted at > 12 months post-surgery in ten episealer knees, and compared to ten healthy knees. Pre- and post-operative clinical data of the episealer knees were collected using a visual analog scale (VAS), the EQ 5d Health, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaires. RESULTS: A consistent medial pivot was observed in both episealer and healthy knees. Non-significant differences were found in the unloaded (p = 0.15) and loaded (p = 0.51) activities. Although lateral rollback was observed in both groups, it was significantly higher for the episealer knees in both the unloaded (p = 0.02) and loaded (p = 0.01) activities. Coupled axial rotation was significantly higher in the unloaded (p = 0.001) but not in the loaded (p = 0.06) activity in the episealer knees. Improved scores were observed at 1-year post-surgery in the episealer subjects for the VAS (p = 0.001), KOOS (p = 0.001) and EQ Health (p = 0.004). CONCLUSION: At 12 month follow-up, a clear physiological knee kinematics pattern of medial pivot, lateral femoral rollback and coupled axial external femoral rotation during flexion was observed in patients treated with an episealer resurfacing procedure. However, higher femoral rollback and axial external rotation in comparison to healthy knees was observed, suggesting possible post-operative muscle weakness and consequent insufficient stabilization at high flexion.

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.

Arthroscopic Minced Cartilage Implantation (MCI): A Technical Note.

Articular cartilage lesions are identified with increasing frequency. Several cartilage repair techniques are available to treat symptomatic cartilage defects. The ultimate goal of any cartilage repair procedure is the prevention of premature osteoarthritis. Autologous chondrocyte implantation provides the best tissue quality. However, 2 operations and a resource-intense culturing process with high regulatory demands are disadvantages of this cartilage repair procedure. Furthermore, cellular dedifferentiation and senescence display further cell culture-associated drawbacks that hamper the procedure. Minced cartilage implantation is a relatively simple and cost-effective one-step procedure with promising biologic potential and satisfying clinical results. We present an arthroscopic surgical technique where the surgeon can apply autologous chondrocytes in a one-step procedure to treat articular cartilage defects at the knee joint.

Sleep is more than rest for plasticity in the human cortex.

Sleep promotes adaptation of behavior and underlying neural plasticity in comparison to active wakefulness. However, the contribution of its two main characteristics, sleep-specific brain activity and reduced stimulus interference, remains unclear. We tested healthy humans on a texture discrimination task, a proxy for neural plasticity in primary visual cortex, in the morning and retested them in the afternoon after a period of daytime sleep, passive waking with maximally reduced interference, or active waking. Sleep restored performance in direct comparison to both passive and active waking, in which deterioration of performance across repeated within-day testing has been linked to synaptic saturation in the primary visual cortex. No difference between passive and active waking was observed. Control experiments indicated that deterioration across wakefulness was retinotopically specific to the trained visual field and not due to unspecific performance differences. The restorative effect of sleep correlated with time spent in NREM sleep and with electroencephalographic slow wave energy, which is thought to reflect renormalization of synaptic strength. The results indicate that sleep is more than a state of reduced stimulus interference, but that sleep-specific brain activity restores performance by actively refining cortical plasticity.

Patient-specific metal implants for focal chondral and osteochondral lesions in the knee; excellent clinical results at 2 years.

PURPOSE: Surgical treatment options for the management of focal chondral and osteochondral lesions in the knee include biological solutions and focal metal implants. A treatment gap exists for patients with lesions not suitable for arthroplasty or biologic repair or who have failed prior cartilage repair surgery. This study reports on the early clinical and functional outcomes in patients undergoing treatment with an individualised mini-metal implant for an isolated focal chondral defect in the knee. METHODS: Open-label, multicentre, non-randomised, non-comparative retrospective observational analysis of prospectively collected clinical data in a consecutive series of 80 patients undergoing knee reconstruction with the Episealer® implant. Knee injury and Osteoarthritis Outcome Score (KOOS) and VAS scores, were recorded preoperatively and at 3 months, 1 year, and 2 years postoperatively. RESULTS: Seventy-five patients were evaluated at a minimum 24 months following implantation. Two patients had undergone revision (2.5%), 1 declined participation, and 2 had not completed the full data requirements, leaving 75 of the 80 with complete data for analysis. All 5 KOOS domain mean scores were significantly improved at 1 and 2 years (p < 0.001-0.002). Mean preoperative aggregated KOOS4 of 35 (95% CI 33.5-37.5) improved to 57 (95% CI 54.5-60.2) and 59 (95% CI 55.7-61.6) at 12 and 24 months respectively (p < 0.05). Mean VAS score improved from 63 (95% CI 56.0-68.1) preoperatively to 32 (95% CI 24.4-38.3) at 24 months. The improvement exceeded the minimal clinically important difference (MCID) and this improvement was maintained over time. Location of defect and history of previous cartilage repair did not significantly affect the outcome (p > 0.05). CONCLUSION: The study suggests that at 2 years, Episealer® implants are safe with a low failure rate of 2.5% and result in clinically significant improvement. Individualised mini-metal implants with appropriate accurate guides for implantation appear to have a place in the management of focal femoral chondral and osteochondral defects in the knee. LEVEL OF EVIDENCE: IV.

Unicondylar Tibiofemoral Arthroplasty - Opinions of the Members of the German Knee Society (DKG) and the German Professional Association of Orthopaedic and Trauma Specialists (BVOU). / Unikondyläre tibiofemorale Endoprothetik ­ Meinungsbild in der Deutschen Kniegesellschaft (DKG) und dem Bundesverband der Orthopäden und Unfallchirurgen (BVOU).

BACKGROUND: The number of implanted unicondylar tibiofemoral knee arthroplasties (UKA) is despite the potential advantages in comparison to total knee arthroplasties (TKA) in Germany relatively low. Goal of this survey, initiated by the Small Implants Group of the German Knee Society, was to gather opinions and put them into context of the current literature. METHODS: Based on the Delphi method and the AWMF rules and standards, 19 statements were developed, which were presented to the members of the DKG and BVOU in an anonymous online survey using "SurveyMonkey". Overall, 410 colleagues participated. RESULTS: The biggest detected controversies were the determination of indications with respect to the body mass index and the existence of a patellofemoral arthrosis. A general consent was determined that a contralateral tibiofemoral arthrosis grade III - IV and meniscal deficiency in the contralateral compartment are an absolute contraindication. There was a consent that age is not a limitation for the implantation of an UKA. If a personal minimum volume of 15 implantations/year should be implemented was seen controversial. CONCLUSION: The personal opinion, eventually built by personal experiences, appears to be in conflict with the knowledge of scientific literature in many instances. Intensive training and education appears necessary.

Phase-amplitude coupling of sleep slow oscillatory and spindle activity correlates with overnight memory consolidation.

Initially independent lines of research suggest that sleep-specific brain activity patterns, observed as electroencephalographic slow oscillatory and sleep spindle activity, promote memory consolidation and underlying synaptic refinements. Here, we further tested the emerging concept that specifically the coordinated interplay of slow oscillations and spindle activity (phase-amplitude coupling) support memory consolidation. Particularly, we associated indices of the interplay between slow oscillatory (0.16-1.25 Hz) and spindle activity (12-16 Hz) during non-rapid eye movement sleep (strength [modulation index] and phase degree of coupling) in 20 healthy adults with parameters of overnight declarative (word-list task) and procedural (mirror-tracing task) memory consolidation. The pattern of results supports the notion that the interplay between oscillations facilitates memory consolidation. The coincidence of the spindle amplitude maximum with the up-state of the slow oscillation (phase degree) was significantly associated with declarative memory consolidation (r = .65, p = .013), whereas the overall strength of coupling (modulation index) correlated with procedural memory consolidation (r = .45, p = .04). Future studies are needed to test for potential causal effects of the observed association between neural oscillations during sleep and memory consolidation, and to elucidate ways of modulating these processes, for instance through non-invasive brain-stimulation techniques.

Brief periods of NREM sleep do not promote early offline gains but subsequent on-task performance in motor skill learning.

Sleep modulates motor learning, but its detailed impact on performance curves remains to be fully characterized. This study aimed to further determine the impact of brief daytime periods of NREM sleep on 'offline' (task discontinuation after initial training) and 'on-task' (performance within the test session) changes in motor skill performance (finger tapping task). In a mixed design (combined parallel group and repeated measures) sleep laboratory study (n=17 'active' wake vs. sleep, n=19 'passive' wake vs. sleep), performance curves were assessed prior to and after a 90min period containing either sleep, active or passive wakefulness. We observed a highly significant, but state- (that is, sleep/wake)-independent early offline gain and improved on-task performance after sleep in comparison to wakefulness. Exploratory curve fitting suggested that the observed sleep effect most likely emerged from an interaction of training-induced improvement and detrimental 'time-on-task' processes, such as fatigue. Our results indicate that brief periods of NREM sleep do not promote early offline gains but subsequent on-task performance in motor skill learning.

Perfectionistic Tendencies in Insomnia Patients' Behavior During Psychometric Testing.

According to self-report questionnaire studies, insomnia patients differ from healthy controls with respect to several personality traits. The current study aimed at exploring how these personality traits may translate into behavior. Insomnia patients' behavior during psychometric testing (n = 163) was investigated in comparison to healthy controls (n = 81), patients with other sleep disorders (n = 80), and patients with obsessive-compulsive disorder (n = 36). In line with our hypotheses, insomnia patients made more additional comments than healthy controls and more corrections than patients with other sleep disorders during sleep-related questionnaire completion. Furthermore, insomnia patients calculated the sum score of a depression questionnaire more frequently than both healthy controls and patients with other sleep disorders. These findings further support the assumption of an altered personality profile in patients with primary insomnia. Future work should aim to elucidate what personality factors these novel behavioral markers may reflect.

Prolonged sleep under Stone Age conditions.

STUDY OBJECTIVES: We report on a unique experiment designed to investigate the impact of prehistoric living conditions on sleep-wake behavior. METHODS: A group of five healthy adults were assessed during life in a Stone Age-like settlement over two months. RESULTS: The most notable finding was that nocturnal time in bed and estimated sleep time, as measured by actigraphy, markedly increased during the experimental period compared to the periods prior to and following the experiment. These increases were primarily driven by a phase-advance shift of sleep onset. Subjective assessments of health and functioning did not reveal any relevant changes across the study. CONCLUSIONS: Our observations provide further evidence for the long-held belief that the absence of modern living conditions is associated with an earlier sleep phase and prolonged sleep duration. COMMENTARY: A commentary on this article appears in this issue on page 723.

The effect of sleep-specific brain activity versus reduced stimulus interference on declarative memory consolidation.

Studies suggest that the consolidation of newly acquired memories and underlying long-term synaptic plasticity might represent a major function of sleep. In a combined repeated-measures and parallel-group sleep laboratory study (active waking versus sleep, passive waking versus sleep), we provide evidence that brief periods of daytime sleep (42.1 ± 8.9 min of non-rapid eye movement sleep) in healthy adolescents (16 years old, all female), compared with equal periods of waking, promote the consolidation of declarative memory (word-pairs) in participants with high power in the electroencephalographic sleep spindle (sigma) frequency range. This observation supports the notion that sleep-specific brain activity when reaching a critical dose, beyond a mere reduction of interference, promotes synaptic plasticity in a hippocampal-neocortical network that underlies the consolidation of declarative memory.

Increased EEG sigma and beta power during NREM sleep in primary insomnia.

The hyperarousal model of primary insomnia suggests that a deficit of attenuating arousal during sleep might cause the experience of non-restorative sleep. In the current study, we examined EEG spectral power values for standard frequency bands as indices of cortical arousal and sleep protecting mechanisms during sleep in 25 patients with primary insomnia and 29 good sleeper controls. Patients with primary insomnia demonstrated significantly elevated spectral power values in the EEG beta and sigma frequency band during NREM stage 2 sleep. No differences were observed in other frequency bands or during REM sleep. Based on prior studies suggesting that EEG beta activity represents a marker of cortical arousal and EEG sleep spindle (sigma) activity is an index of sleep protective mechanisms, our findings may provide further evidence for the concept that a simultaneous activation of wake-promoting and sleep-protecting neural activity patterns contributes to the experience of non-restorative sleep in primary insomnia.

The timing of learning before night-time sleep differentially affects declarative and procedural long-term memory consolidation in adolescents.

Sleep after learning has been shown to foster the consolidation of new memories. However, fundamental questions on the best timing of learning before night-time sleep persist. We tested the hypothesis that learning directly prior to night-time sleep compared to 7.5 hrs prior to night-time sleep provides better conditions for the consolidation of declarative and procedural memories. Fifty healthy female adolescents (aged 16-17 years) were trained on a declarative word-pair and a procedural finger-tapping task at 3 pm (afternoon group, n = 25) or at 9 pm (evening group, n = 25), followed by a sleep laboratory night. Retrieval was assessed 24 hours and 7 days after initial training. Subjects trained in the afternoon showed a significantly elevated retention rate of word-pairs compared to subjects trained in the evening after 24 hours, but not after 7 days. In contrast, off-line gains in finger-tapping performance were significantly higher in subjects trained in the evening compared to those trained in the afternoon after both retention intervals. The observed enhanced consolidation of procedural memories after training in the evening fits to current models of sleep-related memory consolidation. In contrast, the higher retention of declarative memories after encoding in the afternoon is surprising, appeared to be less robust and needs further investigation.

EEG Σ and slow-wave activity during NREM sleep correlate with overnight declarative and procedural memory consolidation.

Previous studies suggest that sleep-specific brain activity patterns such as sleep spindles and electroencephalographic slow-wave activity contribute to the consolidation of novel memories. The generation of both sleep spindles and slow-wave activity relies on synchronized oscillations in a thalamo-cortical network that might be implicated in synaptic strengthening (spindles) and downscaling (slow-wave activity) during sleep. This study further examined the association between electroencephalographic power during non-rapid eye movement sleep in the spindle (sigma, 12-16 Hz) and slow-wave frequency range (0.1-3.5 Hz) and overnight memory consolidation in 20 healthy subjects (10 men, 27.1 ± 4.6 years). We found that both electroencephalographic sigma power and slow-wave activity were positively correlated with the pre-post-sleep consolidation of declarative (word list) and procedural (mirror-tracing) memories. These results, although only correlative in nature, are consistent with the view that processes of synaptic strengthening (sleep spindles) and synaptic downscaling (slow-wave activity) might act in concert to promote synaptic plasticity and the consolidation of both declarative and procedural memories during sleep.