Clinical Outcomes and Registry Data in Total Ankle Arthroplasty.

Total ankle arthroplasty (TAA) is an effective treatment for end-stage ankle arthritis consistently demonstrating good to excellent outcomes, even when considering factors such as deformity, patient age, bilaterality, and arthritis etiology. There is little consensus in the literature with regard to preferred patient-reported outcome metrics (PROMs) for assessing outcomes, although all metrics generally improve following TAA. Several countries have successful registries to track longevity of TAA in populations; however, PROMs are generally not successfully tracked in registries. A trend toward consensus on outcome metrics and collaborative registries is warranted to optimize patient selection and outcomes in TAA.

Reliability of five-minute vs. one-hour heart rate variability metrics in individuals with spinal cord injury.

Background: A previous study showed low reliability of 1-h HRV outcomes in participants with spinal cord injury (SCI), but it was not certain whether the low reliability was due to the unrestricted activity of participants. We aimed to investigate test-retest reliability of HRV metrics in individuals with SCI using a 1-h measurement in a supine position. Methods: Individuals with SCI underwent two sessions of 1-h recording of the time between consecutive R waves (RR-intervals) in a supine position. HRV outcomes were obtained from a single 5-min data segment and for the full 1-h recording. HRV parameters of interest were: standard deviation of all normal-to-normal R-R intervals (SDNN) and square root of the mean of the squared differences between successive R-R intervals (RMSSD) (time domain); and high frequency power (HF), low frequency power (LF), very low frequency power (VLF), ultra-low frequency power (ULF) and total power (TP) (frequency domain). Relative reliability was assessed by intraclass correlation coefficient (ICC). Absolute reliability was assessed by coefficient of variation (CV) and Bland-Altman limits of agreement (LoA). Results: Data from 37 individuals (14 with tetraplegia and 23 with paraplegia) were included. Relative reliability was higher for the 1-h (ICCs ranged from 0.13-0.71) than for the 5-min duration (ICCs ranged from 0.06-0.50) in the overall SCI group for all HRV metrics. Participants with tetraplegia had lower relative reliability compared to participants with paraplegia in all HRV metrics for the 5-min duration (ICCs ranged from -0.01-0.34 vs. 0.21-0.57). For the 1-h duration, participants with paraplegia showed higher relative reliability than participants with tetraplegia in all HRV metrics (ICCs ranged from 0.18-0.79 vs. 0.07-0.54) except TP (ICC 0.69 vs. 0.82). In terms of absolute reliability, the CVs and LoAs for the 1-h duration were better than for the 5-min duration. In general, time domain metrics showed better reliability than frequency domain metrics for both durations in participants with tetraplegia and paraplegia. The lowest CV and narrowest 95% LoA were found for SDNN in 5-min and 1-h durations overall and in both lesion levels. Conclusions: The supine position did not provide better reliability compared to unrestricted activity in participants with SCI. HRV analysis using a 5-min duration is of limited value in SCI due to poor reliability. For the 1-h analysis duration, interpretation of the reliability of HRV varies according to lesion level: it is recommended to take lesion level into account when interpreting reliability measures.

Test-retest reliability of short- and long-term heart rate variability in individuals with spinal cord injury.

STUDY DESIGN: Cross-sectional. OBJECTIVES: To investigate test-retest reliability of heart rate variability (HRV) metrics in SCI without restriction of activity over long (24-h) and shorter durations (5-min, 10-min, 1-h, 3-h and 6-h). SETTINGS: University hospital in Khon Kaen, Thailand. METHODS: Forty-five participants (11 with tetraplegia and 34 with paraplegia) underwent two 24-h recordings of RR-intervals to derive time and frequency HRV metrics. Relative reliability was assessed by intraclass correlation coefficient (ICC) and absolute reliability by coefficient of variation (CV) and Bland-Altman limits of agreement (LoA). RESULTS: For 5- and 10-min durations, eight of eleven HRV metrics had moderate to excellent reliability (ICC 0.40-0.76); the remaining three were poor (ICC < 0.4). HRV values from 1-h and 3-h durations showed moderate to excellent reliability (ICC of 0.46-0.81), except for 1-h reliability of ULF and TP (ICC of 0.06 and 0.30, respectively). Relative reliability was excellent (ICC of 0.77-0.92) for 6-h and 24-h durations in all HRV metrics. Absolute reliability improved as recording duration increased (lower CVs and narrower LoAs). Participants with high AD risk (SCI level at or above T6) showed lower test-retest reliability of HF and LF values than participants with low AD risk. CONCLUSION: Relative reliability of HRV was excellent for 6-h and 24-h. The best absolute reliability values were for 24-h duration. Time-domain outcomes were more reliable than frequency domain outcomes. Participants with high risk of AD, particularly those with tetraplegia, showed lower reliability, especially for HF and LF.

Feedback control of heart rate during treadmill exercise based on a two-phase response model.

This work investigated automatic control of heart rate during treadmill exercise. The aim was to theoretically derive a generic feedback design strategy that achieves a constant input sensitivity function for linear, time-invariant plant models, and to empirically test whether a compensator C2 based on a second-order model is more dynamic and has better tracking accuracy than a compensator C1 based on a first-order model. Twenty-three healthy participants were tested using first and second order compensators, C1 and C2, respectively, during 35-minute bouts of constant heart rate treadmill running. It was found that compensator C2 was significantly more accurate, i.e. it had 7% lower mean root-mean-square tracking error (1.98 vs. 2.13 beats per minute, p = 0.026), and significantly more dynamic, i.e. it had 17% higher mean average control signal power (23.4 × 10-4 m2/s2 vs. 20.0 × 10-4 m2/s2, p = 0.011), than C1. This improvement likely stems from the substantially and significantly better fidelity of second-order models, compared to first order models, in line with classical descriptions of the different phases of the cardiac response to exercise. These outcomes, achieved using a treadmill, are consistent with previous observations for the cycle ergometer exercise modality. In summary, whenever heart rate tracking accuracy is of primary importance and a more dynamic control signal is acceptable, the use of a compensator based on a second-order nominal model is recommended.

Heart rate variability changes with respect to time and exercise intensity during heart-rate-controlled steady-state treadmill running.

The aim of this work was to investigate the time and exercise intensity dependence of heart rate variability (HRV). Time-dependent, cardiovascular-drift-related increases in heart rate (HR) were inhibited by enforcing a constant heart rate throughout the exercise with a feedback control system. Thirty-two healthy adults performed HR-stabilised treadmill running exercise at two distinct exercise intensity levels. Standard time and frequency domain HRV metrics were computed and served as outcomes. Significant decreases were detected in 8 of the 14 outcomes for the time dependence analysis and in 6 of the 7 outcomes for the exercise intensity dependence analysis (excluding the experimental speed-signal frequency analysis). Furthermore, metrics that have been reported to reach an intensity-dependent near-zero minimum rapidly (usually at moderate intensity) were found to be near constant over time and only barely decreased with intensity. Taken together, these results highlight that HRV generally decreases with time and with exercise intensity. The intensity-related reductions were found to be greater in value and significance compared to the time-related reductions. Additionally, the results indicate that decreases in HRV metrics with time or exercise intensity are only detectable as long as their metric-specific near-zero minimum has not yet been reached.

Publication trends in ligament augmentation techniques: current concepts.

IMPORTANCE: Ligament augmentation techniques (LATs) are surgical procedures, in which an anatomical ligament repair or reconstruction is strengthened with a synthetic material. During the last decade, LATs have increased in prevalence in clinical practice and academic literature. Observing the trends in LAT publications can be used to identify clusters of strong evidence for clinical practice and to highlight areas of the literature which need further development. OBJECTIVE: This article aims to define ligament augmentation as a technique category, observe anatomical, procedural, and temporal trends in LAT publication, and report on the state of current research in this field. EVIDENCE REVIEW: Primary literature in the English language, which describes ligament augmentation and reports on human, cadaveric, or biomechanical models, and published prior to May 24th, 2022, was targeted for analysis. PubMed, Embase, and Cochrane CENTRAL databases were explored using a focused keyword search strategy, and the resulting publications were reviewed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data were collected and analysed using descriptive statistics. FINDINGS: Two hundred eighty-three publications reporting ligament augmentation techniques, published from May 1989 to May 2022, were included for final analysis. A wide technical and anatomical variety of procedures are reported. 36.8% of LAT publications describe knee ligaments, among which the anterior cruciate ligamenthas the highest focus in ligament augmentation publications (31.8% of articles). LAT literature has recently expanded in anatomical scope, with many contemporary articles describing the usage of a LAT in the ankle syndesmosis and coracoclavicular ligaments. 60.4% of LAT literature has been published since 2017. There has been an 11% average increase in the rate of LAT publication reports since 2015. Novel fixation devices-suture buttons and suture anchors-have gained wide popularity in the literature. CONCLUSIONS AND RELEVANCE: In this review, we define LATs and quantitatively describe the expansion of LAT use reported in the literature. This data will provide physicians an overview of the history of these methods, as well as illustrate the broad range of applications available for the use of LATs.

Ligament augmentation repair is broadly applied across different orthopaedic subspecialities: an ISAKOS international survey of orthopaedic surgeons.

OBJECTIVES: To evaluate how ligament augmentation repair (LAR) techniques are currently used in different anatomic regions in orthopaedic sports medicine, and to identify the most common indications and limitations of LAR. METHODS: We sent survey invitations to 4,000 members of the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine society. The survey consisted of 37 questions total, with members only receiving some branching questions specific to their area of specialisation. Data were analysed using descriptive statistics, and the significance between groups was evaluated using chi-square tests of independence. RESULTS: Of 515 surveys received, 502 were complete and included for the analysis (97% completion rate). 27% of respondents report from Europe, 26% South America, 23% Asia, 15% North America, 5.2% Oceania, and 3.4% Africa. 75% of all survey respondents report using LAR, most frequently using it for the anterior talofibular ligament ( 69%), acromioclavicular joint ( 58%), and the anterior cruciate ligament (51%). Surgeons in Asia report using LAR the most (80%), and surgeons in Africa the least (59%). LAR is most commonly indicated for additional stability (72%), poor tissue quality (54%), and more rapid return-to-play (47%). LAR users state their greatest limitation is cost (62%), while non-LAR users state their greatest reason not to use LAR is that patients do well without it (46%). We also find that the frequency of LAR use among surgeons may differ based on practice characteristics and training. For example, surgeons who treat athletes at the professional or Olympic level are significantly more likely to have a high annual use of LAR (20+ cases) compared to surgeons that treat only recreational athletes (45% and 25%, respectively, p â€‹= â€‹0.005). CONCLUSION: LAR is broadly applied in orthopaedics but its rate of use is not homogeneous. Outcomes and perceived benefits vary depending on factors such as surgeon specialty and treatment population. LEVEL OF EVIDENCE: Level V.

Os supranaviculare and navicular osteochondral lesion contributing to the development of a navicular stress fracture in an adolescent male athlete: Case report.

Stress fractures of the tarsal navicular bone can be problematic in the athlete. This case details the injury and outcome of an adolescent male athlete who experienced one year of intermittent foot pain without acute trauma. Radiographs and computed tomography demonstrated a triad of a navicular stress fracture, an os supranaviculare, and an osteochondral defect of the navicular bone. The patient underwent successful operative fixation and returned to painless full function with imaging demonstrating healing at six months. Diagnosis of a navicular stress fracture in the setting of both an os supranaviculare and osteochondral lesion of the navicular bone have not been reported elsewhere in the literature. While repetitive loading on the navicular bone can independently produce a stress fracture, the patient had an increased risk for this injury; the presumably pre-existing navicular osteochondral lesion and os supranaviculare may have resulted in decreased effective articular surface area, thereby increasing force on the navicular bone and producing a stress fracture. Understanding navicular stress fractures and concomitant bony pathology contributing to injury is crucial to successful diagnosis, management, and prevention of recurrence.

Talus Idiopathic Versus Stress-Injury-Related Osteonecrosis and Its Resolution: A Case Report.

A 34-year-old healthy long-distance runner sustained a possible stress injury to the talus. This injury progressed into osteonecrosis (ON) or might have presented idiopathically. This patient had a complete normal metabolic workup. Non-surgical management, including resting, activity modification, and bone stimulators, led to resolution. Serial exams and magnetic resonance imaging demonstrated gradual resolution of the ON. At two years old, she was pain-free and had returned to running. Talus ON is uncommon and even more so in the absence of metabolic disorders or precipitating trauma. This case presents a debatable stress injury, an overuse injury, or even an idiopathic ON. It healed with non-surgical management. Serial, advanced imaging surveillance was implemented. There is a lack of impactful literature regarding the management of early ON and a paucity of strong recommendations to guide non-surgical treatment options in the early stages. This presentation is quite debatable as to whether there was a stress fracture leading to ON or if it was idiopathic ON. Yet, these entities could easily overlap, and physicians and orthopedists should be aware.

Medial Column Fusions in Flatfoot Deformities: Naviculocuneiform and Talonavicular.

Progressive collapsing foot deformity (PCFD; commonly referred to as flatfoot deformity) is a complex condition classically characterized by hindfoot valgus, midfoot abduction, and forefoot varus. Medial column arthrodesis can be used to reliably correct severe, arthritic, and unstable PCFD involving the medial column. Although both naviculocuneiform arthrodesis and talonavicular arthrodesis have their own indications, patient selection and careful radiographic and clinical assessment are crucial for any medial column arthrodesis. Herein, the authors discuss the indications for medial column arthrodesis procedures, outcomes as reported in the literature, and several case examples using medial column arthrodesis in deformity correction.

Noninvasive Soft Tissue Expansion Strips and Wound Complications After Total Ankle Arthroplasty.

BACKGROUND: Total ankle arthroplasty through the anterior approach (TAR-AA) is an increasingly popular treatment for ankle arthritis, but it carries a known risk for wound complications. Several products have been investigated to mitigate this risk; however, most are either costly or invasive. Noninvasive skin expansion strips (NSESs) were designed to transfer tension away from the incision and induce new skin growth at the edges of the strips. We hypothesize that postoperative application of NSESs will decrease unplanned clinic visits and wound complications after TAR-AA. METHODS: This is a prospective cohort study of 41 patients at a single institution (3 surgeons) treated with NSESs after undergoing TAR-AA. An additional 41 consecutive historical patients treated without NSESs were retrospectively included as a control group. Patients received application of NSESs in the operating room after routine wound closure and again 2 weeks postoperatively. No other changes were made to the surgeons' wound closure technique, immobilization, follow-up timing, or rehabilitation protocols. Primary outcomes included (1) additional clinic visit required for wound assessment or suture removal, (2) superficial wound complication, and (3) deep infection. RESULTS: Baseline demographics did not differ significantly from our 41 consecutively treated historical controls. Additional clinic visits for suture removal or wound evaluation were significantly lower for patients treated with NSESs (15%, 6 of 41) compared to the control group (49%, 20 of 41) (P = .001). There was also a significant difference in the superficial wound complication rate in the treatment group vs control group, 2% and 12%, respectively (P = .04). There were no deep infections in either group. CONCLUSION: Noninvasive skin expansion strips placed after TAR-AA with an anterior approach have the potential to decrease wound complications and unplanned clinic visits. Further high-volume or randomized studies are needed to clarify their cost effectiveness and effect on long-term outcomes. LEVEL OF EVIDENCE: Level II, prospective cohort study.

Development of a Belt-actuated Robotic Platform for Early Rehabilitation.

In order to promote early rehabilitation, we proposed a system which provides full-body arm-leg training for patients in a bed-lying position. As the preliminary development, a platform for leg movement was investigated. An innovative system with four servo drives was designed and manufactured. An artificial leg frame was attached to the platform via belts. The positions of the hip and knee joints were recorded using potentiometers. Closed-loop PID position control algorithms were implemented for production of various stepping movements. Technical evaluation on a test participant showed that the platform tracked the circular trajectory of the foot in a supine-lying position with an area difference of 8.2%, and produced walking-like trajectories in the hip and knee joints in a side-lying position with a mean error of 10.6%. The mechanical structure can be resized, and the control system can be expanded, so as to produce 3-dimensional stepping movement in both arms and legs. This innovative platform combined with the closed-loop position control strategy shows the technical potential to be a promising full-body rehabilitation platform for the patients in the early post-injury stage.

Two Orthogonal Nitinol Staples and Combined Nitinol Staple-Screw Constructs for a First Metatarsophalangeal Joint Arthrodesis: A Biomechanical Cadaver Study.

BACKGROUND: End-stage hallux metatarsophalangeal (MTP) joint arthritis is commonly treated with arthrodesis using stainless steel or titanium implants. These implants provide static compression that is maximal at the time of implant insertion. Alternatively, nitinol staples are capable of dynamic compression. They have most frequently been used for midfoot arthrodesis procedures. However, their biomechanical performance during hallux MTP arthrodesis has not been described. METHODS: 8 matched pairs of cadaveric feet (4 female, 4 male) were prepared for hallux MTP arthrodesis using cup and cone reamers. Cadaveric pairs were then instrumented with either (1) a transarticular lag screw and dorsal nitinol staple or (2) orthogonal nitinol staples placed dorsally and medially. Walking in a short leg cast for 6 weeks was simulated by applying 90-N forces at 3 Hz to the plantar proximal phalanx for up to 250 000 cycles. Failure was defined as catastrophic implant failure or plantar gapping beyond 7 mm. RESULTS: 15 of 16 specimens failed cyclic loading. All 8 specimens fixed with orthogonal staples failed at an average of 37 ± 81 cycles. 7 of 8 specimens fixed with a dorsal staple and crossed screw failed at 14 900 ± 39 000 cycles. Collectively, 5 specimens failed because of bone fracture (1 in orthogonal staples, 4 in staple-screw group) and 10 failed because of excessive gap formation (7 in orthogonal staples, 3 in staple-screw group). The number of cycles to failure was significantly lower (P = .0469) in the orthogonal staple constructs compared with the dorsal staple and crossed screw constructs. CONCLUSION: The tested constructs permit significant motion at the first MTP fusion surface during simulated protected weightbearing. Although multiple in vivo factors should be considered when extrapolating results from this cadaveric study, this motion may result in clinical failure with early postoperative weightbearing protocols. CLINICAL RELEVANCE: We report the first biomechanical evaluation of hallux MTP arthrodesis using modern nitinol staples in 2 separate constructs.

Management of Treatment Failures in Osteochondral Lesions of the Talus.

Osteochondral lesions of the talus are a common result of traumatic ankle injury. Due to the low success rates of nonoperative management, surgical management of osteochondral lesions of the talus (OLTs) has evolved considerably over the past decade as more outcomes research has emerged, new techniques have been described, and we have developed a better understanding of the role of biologics in the treatment algorithm. We describe, in sequence, the surgical management options, including salvage procedures, for failed treatment of OLTs.

Significant variations in surgical construct and return to sport protocols with syndesmotic injuries: an ISAKOS global perspective.

OBJECTIVES: Although the body of literature on syndesmosis injuries is growing with regard to both the biomechanics and clinical outcomes for various fixation constructs, there is little consensus on the optimal treatment and return to sport strategy for these injuries. We endeavoured to assess the current approaches to managing syndesmotic injuries through a Research Electronic Data Capture survey. METHODS: The survey consisted of 27 questions, including respondent demographics, indications for treatment of syndesmotic injuries, preferred treatment and technique, and postoperative management. Responses were generated through six different athlete scenarios: moderate impact, high impact, and very high impact athletes with/without complete deltoid injury. Frequencies and percentages were calculated for all categorical responses. RESULTS: A total of 742 providers responded to the survey, including 457 American surgeons and 285 members of various international societies. Flexible devices were the preferred fixation construct (47.1%), followed by screws (29.6%), hybrid fixation (e.g. combination of flexible device and screw, 18%), and other (5.3%). Sixty-four percent of respondents noted that their rehabilitation protocols would not change for each athlete scenario. Considerable variability was present in anticipated return to full participation, largely dependent on the presence or absence of a deltoid ligament injury. CONCLUSION: The most common elements used as surgical indications were syndesmosis widening > 2 mm on x-ray, an anterior inferior talofibular ligament injury in combination with a posterior inferior talofinular ligament or deltoid ligament involvement on magnetic resonance imaging, and widening of the distal tibiofibular joint during arthroscopic evaluation. Overall, flexible fixation (e.g. suture button) was the preferred device choice for the repair of an injured syndesmosis. Most respondents did not alter their rehab protocol or anticipated return to play timeline based on the injury severity. However, there was considerable variability between respondents on the time to weight-bearing, running, and full participation. Further pragmatic outcomes data are necessary to guide safe return to play protocols for syndesmotic injuries. LEVEL OF EVIDENCE: Level IV.

Usability evaluation of an interactive leg press training robot for children with neuromuscular impairments.

BACKGROUND: The use of robotic technology for neurorehabilitative applications has become increasingly important for adults and children with different motor impairments. OBJECTIVE: The aim of this study was to evaluate the technical feasibility and usability of a new interactive leg-press training robot that was developed to train leg muscle strength and control, suitable for children with neuromuscular impairments. METHODS: An interactive robotic training system was designed and constructed with various control strategies, actuators and force/position sensors to enable the performance of different training modes (passive, active resistance, and exergames). Five paediatric patients, aged between 7 and 16 years (one girl, age 13.0 ± 3.7 years, [mean ± SD]), with different neuromuscular impairments were recruited to participate in this study. Patients evaluated the device based on a user satisfaction questionnaire and Visual Analog Scale (VAS) scores, and therapists evaluated the device with the modified System Usability Scale (SUS). RESULTS: One patient could not perform the training session because of his small knee range of motion. Visual Analog Scale scores were given by the 4 patients who performed the training sessions. All the patients adjudged the training with the interactive device as satisfactory. The average SUS score given by the therapists was 61.2 ± 18.4. CONCLUSION: This study proposed an interactive lower limb training device for children with different neuromuscular impairments. The device is deemed feasible for paediatric rehabilitation applications, both in terms of technical feasibility and usability acceptance. Both patients and therapists provided positive feedback regarding the training with the device.

Diagnostic Accuracy of the Progressive Collapsing Foot Deformity (PCFD) Classification.

BACKGROUND: A consensus group recently proposed the term progressive collapsing foot deformity (PCFD) and a new classification with 2 stages plus 5 classes to describe the complex array of flatfoot deformities. This study aimed to validate different diagnostic accuracy rates of the PCFD classification. METHODS: This was a survey-based study distributed among 13 foot and ankle fellowship programs for 3 groups of participants with varied experience in practice (group 1: fellows in training, group 2: surgeons in practice for 1-4 years, and group 3: surgeons in practice for ≥5 years). Each participant was asked to assign 20 different cases of flatfoot deformity to the appropriate classes and stages using the PCFD classification. The overall diagnostic accuracy, class, and stage diagnostic accuracy rates for the 20 cases were calculated first for the entire cohort and then compared among the 3 groups. The misdiagnosis rate for each class of deformity (the sum of overdiagnosis and underdiagnosis rates) of the entire cohort was calculated and compared with the other classes. Mean and standard evidence were used to describe numerical data. One-way analysis of variance was used to compare values among the 3 groups and the 5 classes. P <.05 was considered statistically significant. RESULTS: For the whole cohort, the overall diagnostic accuracy, class diagnostic accuracy, and stage diagnostic accuracy rates were 71.0%, 78.3%, and 81.7%, respectively There was a statistically significant difference between group 1 and 2, and group 1 and 3, in overall diagnostic accuracy and class diagnostic accuracy, with no significant difference among the 3 groups regarding stage diagnostic accuracy. Class B had a significantly higher overdiagnosis rate than the rest of the classes, whereas class D was significantly underdiagnosed than others. The misdiagnosis rates for classes A to E were 3.3%, 17.5%, 11.1%, 26.0%, and 3.7%, respectively. CONCLUSION: The PCFD classification showed overall fair diagnostic accuracy rates. The highest diagnostic accuracy was for "hindfoot valgus deformity" and "ankle instability." Further content validation of the PCFD classification is needed to examine the terminology and interpretation of those classes with low diagnostic accuracy including "midfoot/forefoot abduction deformity," "forefoot varus deformity/medial column instability," and "peritalar subluxation/dislocation."Level of Evidence: Level II, prospective comparative study.

Osteochondral Lesions of the Tibial Plafond and Ankle Instability With Ankle Cartilage Lesions: Proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle.

BACKGROUND: An international consensus group of experts was convened to collaboratively advance toward consensus opinions based on the best available evidence on key topics within cartilage repair of the ankle. The purpose of this article is to present the consensus statements on osteochondral lesions of the tibial plafond (OLTP) and on ankle instability with ankle cartilage lesions developed at the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. METHODS: Forty-three experts in cartilage repair of the ankle were convened and participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted within 4 working groups focusing on specific topics within cartilage repair of the ankle, after which a comprehensive literature review was performed and the available evidence for each statement was graded. Discussion and debate occurred in cases where statements were not agreed on in unanimous fashion within the working groups. A final vote was then held. RESULTS: A total of 11 statements on OLTP reached consensus. Four achieved unanimous support and 7 reached strong consensus (greater than 75% agreement). A total of 8 statements on ankle instability with ankle cartilage lesions reached consensus during the 2019 International Consensus Meeting on Cartilage Repair of the Ankle. One achieved unanimous support, and seven reached strong consensus (greater than 75% agreement). CONCLUSION: These consensus statements may assist clinicians in the management of these difficult clinical pathologies. LEVEL OF EVIDENCE: Level V, mechanism-based reasoning.

Heart rate control using first- and second-order models during treadmill exercise.

Heart rate control using first- and second-order models was compared using a novel control design strategy which shapes the input sensitivity function. Ten participants performed two feedback control test series on a treadmill with square wave and constant references. Using a repeated measures, counterbalanced study design, each series compared controllers C1 and C2 based on first- and second-order models, respectively. In the first series, tracking accuracy root-mean-square tracking error (RMSE) was not significantly lower for C2: 2.59 bpm vs. 2.69 bpm (mean, C1 vs. C2), p = 0.79. But average control signal power was significantly higher for C2: 11.29 × 10 - 4 m 2 / s 2 vs. 27.91 × 10 - 4 m 2 / s 2 , p = 3.1 × 10 - 10 . In the second series, RMSE was also not significantly lower for C2: 1.99 bpm vs. 1.94 bpm, p = 0.39; but average control signal power was again significantly higher for C2: 2.20 × 10 - 4 m 2 / s 2 vs. 2.78 × 10 - 4 m 2 / s 2 , p = 0.045. The results provide no evidence that controllers based on second-order models lead to better tracking accuracy, despite the finding that they are significantly more dynamic. Further investigation using a substantially larger sample size is warranted.