A New Bioactive Fibrin Formulation Provided Superior Cartilage Regeneration in a Caprine Model.

The effective and long-term treatment of cartilage defects is an unmet need among patients worldwide. In the past, several synthetic and natural biomaterials have been designed to support functional articular cartilage formation. However, they have mostly failed to enhance the terminal stage of chondrogenic differentiation, leading to scar tissue formation after the operation. Growth factors substantially regulate cartilage regeneration by acting on receptors to trigger intracellular signaling and cell recruitment for tissue regeneration. In this study, we investigated the effect of recombinant insulin-like growth factor 1 (rIGF-1), loaded in fibrin microbeads (FibIGF1), on cartilage regeneration. rIGF-1-loaded fibrin microbeads were injected into full-thickness cartilage defects in the knees of goats. The stability, integration, and quality of tissue repair were evaluated at 1 and 6 months by gross morphology, histology, and collagen type II staining. The in vivo results showed that compared to plain fibrin samples, particularly at 6 months, FibIGF1 improved the functional cartilage formation, confirmed through gross morphology, histology, and collagen type II immunostaining. FibIGF1 could be a promising candidate for cartilage repair in the clinic.

[Pédiatrie - Internal lengthening nails: a novel method of lower limb reconstruction in children]. / Pédiatrie - Clous d'allongement internes : nouvelle méthode de reconstruction des membres inférieurs.

Intramedullary lengthening nails for lower limb reconstruction in children are a rapidly growing field and represent an alternative to external fixators. Today, two types of intramedullary lengthening nails are used: motorized (FITBONE) and magnetically driven (PRECISE) bone lengthening nails. Indications for limb lengthening nails are: 1) Significant lower limb length discrepancy; 2) Short stature and deformities due to musculoskeletal or dysplastic syndromes; 3) Constitutional short stature. Intramedullary lengthening surgery is challenging and represents a safe and reliable mode of treatment in patients under 18 years of age with an excellent reported outcome.

Les clous d'allongement intramédullaires pour la reconstruction des membres inférieurs chez les enfants sont un domaine en plein essor et représentent une alternative aux fixateurs externes. Aujourd'hui, 2 types de clous d'allongement intramédullaires sont utilisés : les clous d'allongement osseux motorisés (FITBONE) et à entraînement magnétique (PRECISE). Les indications pour les clous d'allongement des membres sont les suivantes : a) inégalité significative de longueur des membres inférieurs ; b) petite taille et déformations dues à des syndromes musculosquelettiques ou à des dysplasies et c) petite taille constitutionnelle. La chirurgie d'allongement intramédullaire est exigeante et représente un mode de traitement sûr et fiable chez les moins de 18 ans, avec un excellent résultat rapporté par les patients.

Epidemiology of Pediatric Upper Extremity Fractures in a Tertiary Care Center in Switzerland.

OBJECTIVE: Fractures in children are common and account for 10% to 25% of injuries in children with considerable effects on activity restriction and subsequent high socioeconomically impact. Eighty percent of all fractures in children occur at the upper extremity. The article investigates the epidemiology and fracture pattern of the upper extremity within a pediatric population consulting a tertiary referral hospital in Switzerland. METHODS: Study population included all patients younger than 18 years presenting with an upper extremity fracture. Recorded data were age, sex, side, season of the year, mechanism, type of fracture, and applied treatment. RESULTS: Fractures of the upper extremities represented 76% with a mean age of 9 years and 7 months. Compared with girls, boys had a risk ratio of 1.35 (1.14-1.6) of having a traumatic injury. The radius, with 298 fractures (37%), was the most injured bone. Overall simple fall from his or her height and soccer represented the main injury mechanisms accounting for 26% and 9%, respectively. Eighty-six percent of fractures were treated by cast with or without closed reduction, 11% (92) by closed reduction and pinning or elastic stable intramedullary, and only 3% of fractures were treated by open reduction and internal fixation. CONCLUSIONS: Eighty-six percent of all fractures could be treated by conservative methods. Only 17% need surgical treatments by orthopedic surgeons. This shows how important it is to train residents in pediatrics for the treatment of upper limb fractures in children.

[Pediatrics - Perthes disease : current knowledges and treatment]. / Pédiatrie. Maladie de Perthes : connaissances actuelles et prise en charge.

Perthes's disease corresponds to an interruption of the vascularization of the epiphyseal nucleus of the femoral head followed by avascular necrosis. This necrosis weakens the bone and subchondral fractures associated with a deformation of the femoral head is seen. It is important not to miss an extrusion of the femoral head, which makes surgical treatment unavoidable. The loss of joint congruence causes functional limitations and represents an increased risk for early hip osteoarthritis. Non weight bearing limits the subchondral fractures, but requires an important adaptation from the patient and his entourage.

La maladie de Perthes correspond à une interruption de la vascularisation du noyau épiphysaire de la tête fémorale suivie d'une nécrose avasculaire. Cette nécrose fragilise l'os et des fractures sous-chondrales associées à une déformation de la tête fémorale en sont les conséquences. Il est important d'être vigilant quant à une excentration de la tête fémorale, ce qui rend une prise en charge chirurgicale incontournable afin d'éviter des séquelles trop importantes à l'âge adulte. La perte de congruence articulaire engendre une limitation fonctionnelle et représente un risque accru de coxarthrose précoce. La décharge permet de limiter les fractures sous-chondrales, mais demande une adaptation importante de la part du patient et de son entourage.

[Adolescent idiopathic scoliosis : diagnostic criteria and management]. / Scoliose idiopathique de l'adolescent : critères diagnostiques et prise en charge.

The rapid growth of the spine during the pubertal spurt requires greater vigilance for the pediatrician at the annual check during this period to detect the occurrence of scoliosis. Before confirming the diagnosis of idiopathic scoliosis, it is imperative to exclude a secondary cause with appropriate history and clinical examination, and in selective cases with additional testing. Any scoliosis detected during growth should be considered potentially progressive and sent to a specialist if it is equal to or exceeds 20° on the X-rays. Radiological changes of more than 5° during a 6 months interval must also motivate an appointment with a specialist. Regular clinical and radiological surveillance, every 6 months, remains imperative to confirm or deny this risk of progression and decide on treatment.

La forte croissance du rachis durant la période péripubertaire impose l'obligation d'une plus grande vigilance au cours des examens annuels chez le pédiatre, afin de dépister la survenue d'une scoliose. Avant d'en affirmer le caractère idiopathique, il est nécessaire d'écarter une cause secondaire par une anamnèse et un examen clinique ciblé, voire des examens complémentaires. Toute scoliose dépistée en période de croissance doit être considérée comme potentiellement évolutive et adressée auprès d'un spécialiste dès lors qu'elle atteint ou dépasse radiologiquement 20°. Une évolution radiologique de plus de 5° en 6 mois doit également motiver une consultation spécialisée. La surveillance radioclinique régulière, tous les 6 mois, reste donc un impératif pour confirmer ou infirmer ce risque évolutif et décider du traitement.

NBAS mutations cause a multisystem disorder involving bone, connective tissue, liver, immune system, and retina.

We report two unrelated patients with a multisystem disease involving liver, eye, immune system, connective tissue, and bone, caused by biallelic mutations in the neuroblastoma amplified sequence (NBAS) gene. Both presented as infants with recurrent episodes triggered by fever with vomiting, dehydration, and elevated transaminases. They had frequent infections, hypogammaglobulinemia, reduced natural killer cells, and the Pelger-Huët anomaly of their granulocytes. Their facial features were similar with a pointed chin and proptosis; loose skin and reduced subcutaneous fat gave them a progeroid appearance. Skeletal features included short stature, slender bones, epiphyseal dysplasia with multiple phalangeal pseudo-epiphyses, and small C1-C2 vertebrae causing cervical instability and myelopathy. Retinal dystrophy and optic atrophy were present in one patient. NBAS is a component of the synthaxin-18 complex and is involved in nonsense-mediated mRNA decay control. Putative loss-of-function mutations in NBAS are already known to cause disease in humans. A specific founder mutation has been associated with short stature, optic nerve atrophy and Pelger-Huët anomaly of granulocytes (SOPH) in the Siberian Yakut population. A more recent report associates NBAS mutations with recurrent acute liver failure in infancy in a group of patients of European descent. Our observations indicate that the phenotypic spectrum of NBAS deficiency is wider than previously known and includes skeletal, hepatic, metabolic, and immunologic aspects. Early recognition of the skeletal phenotype is important for preventive management of cervical instability.

[Sport medicine consultation for adolescents]. / Pédiatrie. (2.) Consultation de médecine du sport dédiée à l'adolescent.

Sport activity is a determinant of health and well-being for adolescents' psychological and physic development. Early detection of traumatic lesions or pathological condition among sportive adolescent in the light of their developmental stage is of outmost importance and is best done by an interdisciplinary team. This clinical management also aims at preventing consequences of inappropriate training. The CHUV has set-up a specific sports medicine outpatient consultation clinic for adolescents in the order to provide the best integrative management of young athletes.

[Targeted approach to osteoporosis for children and teenagers]. / Pédiatrie 5. Approche ciblée de l'ostéoporose chez l'enfant et l'adolescent.

The osteoporosis of the child and the teenager is a pathological reality; its multifactorial pathogenesis often requires a collaborative approach and multidisciplinary. The osteoporosis characterized by a reduction in the bone mineral density is not a uniform pathology; it must be dealt with on all the levels by analyzing the factors of risks, by giving itself the diagnostic means and while insisting on the importance of a preventive approach as well as therapeutic.

Single versus double retrograde intramedullary nail technique for treatment of displaced proximal humeral fractures in children: A retrospective cohort study.

Background: Highly displaced proximal humeral fractures in children with low remodeling potential need to be reduced and fixed. The use of two flexible retrograde nails became the most popular fixation technique due to the excellent functional outcome, the low complication rates, and the possibility of early mobilization. A modified single retrograde technique has been suggested by the authors to address the main disadvantage of this technique, the long operative duration. The aim of this study was to compare these techniques in terms of efficacy, and clinical and radiological outcomes. Methods: We performed a retrospective, monocentric study. Two groups of patients were defined: One was treated with the standard flexible retrograde double nail technique and the other with the modified single nail technique. The demographic and fracture characteristics were similar in both groups and the postoperative immobilization with a simple sling for 2 weeks. We compared the surgical duration for the initial fixation and hardware removal procedures. The Quick Disabilities of the Arm, Shoulder, and Hand score, the secondary displacement at 1-week follow-up, the radiological union at 6-week follow-up, and the perioperative and short-term complications were also assessed for both groups. Results: The surgical duration of the initial fixation procedure was significantly shorter in single nail technique group (p = 0.005). The percentage of excellent Quick Disabilities of the Arm, Shoulder, and Hand score (0) was similar in the two groups (p = 0.98). No secondary displacement was reported for the double nail technique group. In only one patient from the single nail technique group, we detected a secondary displacement at the first week control which did not need reoperation. In both groups, fractures were healed on the 6-week radiologic control. No cases of infection, superficial skin irritation, neurological damage, or complications related to implant removal were reported in both groups. Conclusions: The single nail technique of fixation proximal humeral fractures in children addresses the disadvantage of long surgical times, described until today, with the double nail technique without compromising the excellent functional and radiological short-term outcomes. Level of evidence: level III.

Lateral condyle fracture of the humerus in children treated with bioabsorbable materials.

The aim of this study was to compare clinical and radiological outcome of lateral condyle fracture of the elbow in children treated with bioabsorbable or metallic material. From January 2008 to December 2009, 16 children with similar fractures and ages were grouped according to the fixation material used. Children were seen at 3, 6, and 12 months and more than 4 years (mean 51.8 months) postoperatively. The clinical results were compared using the Mayo Elbow Performance Score (MEPS). Radiographic studies of the fractured and opposite elbow were assessed at last follow-up control. Twelve children had a sufficient followup and could be included in the study. Seven could be included in the traditional group and 5 in the bioabsorbable group. At 12 months, the MEPS was 100 for every child in both groups. Asymptomatic bony radiolucent visible tracks and heterotopic ossifications were noted in both groups. There were no significant differences in terms of clinical and radiological outcome between the two groups. The use of bioabsorbable pins or screws is a reasonable alternative to the traditional use of metallic materials for the treatment of lateral condyle fracture of the elbow in children.

Treatment perspective after failed open reduction of congenital hip dislocation. A systematic review.

Background: Failure of open reduction of developmental hip dislocation is a serious complication and revision surgery appear to be technically demanding with high complication rates. Little attention has been given in literature to patients in whom open reduction of developmental hip dislocation has failed. We present a systematic review about current perspectives and timing when to perform surgical revision after failed open reduction of developmental hip dislocation in children. Methods: Following the recommendations of the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) statements we performed a comprehensive search of the PubMed and Google Scholar bibliographic database in order to select all studies published between 1980 and 2022. Studies were screened for the reasons for failure of open reduction, timing when revision surgery was performed, and for the surgical techniques used for revision. Results: A total of 10 articles including 252 patients and 268 hips has been recorded. The most common causes of re-dislocation after open reduction are inadequate exposure and failure to release the obstructing soft tissues inside and around the hip. In 90% of the cases the anterolateral approach was performed for revision surgery. Avascular necrosis occurred in 5%-67% of cases and was the most encountered complication. Conclusion: Redislocation of developmental hip dislocation after an open reduction has poor long-term outcomes mainly due to a high rate of avascular necrosis of the femoral head. It is mandatory to obtain a stable reduction at the second surgery combining soft tissue release, capsulorrhaphy, pelvic and femoral osteotomies.

Functional and Patient-related Outcomes of Total Hip Arthroplasty in Patients Younger Than 20 Years.

Background: Total hip arthroplasty (THA) in adolescent and young adults represent only about 10% of all THAs. Despite the advances in hip conservation surgery, there are still adolescents and young adults who progress to severe joint degeneration. THA seems to be the last solution in these cases. We aimed to assess the clinical and patient-related outcomes at short-term to midterm follow-up for THAs performed before the age of 20 years. Material and methods: We performed a retrospective monocentric study including all patients that underwent a THA before the age of 20 years between January 2008 and December 2018 at our tertiary orthopaedic center with a minimum follow-up of 2 years. Demographic data were recorded. The Harris and Oxford hip scores were used to assess clinical and patient-related outcomes. Results: A total of 11 patients (12 THAs) were included. Juvenile inflammatory arthritis and avascular necrosis due to slipped capital femoral epiphysis were the most commonly encountered etiologies. The mean age at surgery was 16 years (minimum 13, maximum 19 years). The mean follow-up duration was 6 years (minimum 2, maximum 9 years) without any revision. Regarding the Harris and Oxford hip scores, the mean score were 81 and 39.5 for clinical and patient-related outcomes respectively. The Spearman correlation test revealed a statistically significant positive correlation between the 2 scores of ρ = 0.811 with a P value < .001. Conclusions: THA in adolescents and young adults suffering from end-stage osteoarthritis due to pediatric hip disorders provides improved hip function and notable pain relief at short-term to midterm follow-up.

Myositis ossificans in the pediatric population: a systematic scoping review.

Introduction: Circumscribed or pseudomalignant myositis ossificans (MO) is a rare and benign condition characterized by heterotopic bone formation in soft tissues. The clinical presentation of MO, imaging investigations, histological findings, and treatment strategies are unclear, especially in the pediatric population. Materials and methods: A literature search was conducted in PubMed, Scopus, and Google Scholar electronic databases to identify original articles and reviews in English or French of traumatic and non-traumatic MO. Studies were selected by 2 independent reviewers following the PRISMA recommendation and descriptive data were extracted. We harvest in each case the sex, age at diagnosis, location, presence of initial trauma, pre-emptive diagnosis, modalities of imagery used, realized biopsy, treatment performed, and type of follow-up. Results: Sixty pediatric cases of MO were identified between 2002 and 2023. Twenty-three patients (38.3%) were diagnosed with idiopathic/pseudomalignant and 37 patients (61.7%) with circumscribed. The mean age at diagnosis was 9.5 years (range 0.2-17 years), with a male-to-female ratio of 1:1. The initial pre-emptive diagnosis was neoplasia in 13 patients (21.7%). The biopsy was percutaneous in 9 patients (15%) and incisional in 7 patients (11.7%). Histological analysis was achieved in 35 cases (57%). Surgical excision was the first line treatment in 46.7% of patients, and non-surgical in the remaining patients. The follow-up strategy was clinical in 16 patients (26.7%) or based on imaging investigation in 23 patients (38.3%). Discussion: Although MO in children is described as a rare pathology, identifying the benignity of the condition is essential to avoid unnecessary invasive treatment and to avoid delaying the treatment of a potentially life-threatening entity. It seems that there is no consensus established concerning the proper imaging for diagnosis. Clinicians should acknowledge that the absence of a triggering trauma tends to direct the investigation and the management toward a surgical attitude. Conservative management is key, however, surgical excision can be proposed on matured lesions on a case-by-case basis. The absence of recurrence is not excluded. Therefore, a close clinical follow-up is suggested for all cases. The true benefit of a radiological is questioned in a question known to be self-resolving.

Kingella kingae Spinal Infections in Children.

Nowadays, Kingella kingae is considered an important cause of primary spinal infections in children aged between 6 and 48 months. The presentation of the disease is often characterized by mild clinical features and a moderate biological inflammatory response, requiring a high index of suspicion. Performing magnetic resonance imaging (MRI) and obtaining an oropharyngeal specimen and subjecting it to a K. kingae-specific nucleic acid amplification test are recommended for its diagnosis. Most patients respond promptly to conservative treatment after administration of antibiotic therapy, which is prolonged for up to 3 months according to the individual clinical and biological response. Invasive surgical procedures are not required except for children who do not improve with antibiotic treatment, develop signs of cord compression, or if the presence of atypical microorganisms is suspected. Kingella kingae spinal infections usually run an indolent and benign clinical course, living no permanent sequelae.

Epidemiology of paediatric lower extremity fractures in a tertiary care center in Switzerland.

PURPOSE: About 20% of all fractures in children occur at the lower extremity. This study aims to investigate the epidemiology and injury pattern of lower extremity fractures within the pediatric population consulting a tertiary referral hospital in Switzerland. METHODS: Study population included all patients up to 16 years presenting with a lower extremity fracture over a period of one year. Recorded data were age, gender, side, season of the year, mechanism, type of fracture and applied treatment. RESULTS: Fractures of the lower extremity represent 23% of all fractures with a mean age of 9 years and 6 months. The tibia, with 94 fractures (38%), represents the most frequently injured bone. Peak incidence is seen in winter and 24% of tibia shaft fractures were due to board sports. Overall, 82% of fractures were treated by cast with or without closed reduction, and only 18% requested surgery. CONCLUSION: Board sports seems to be a leading cause of tibial shaft fracture in our region. Nevertheless, only 18% of fractures had recourse to an orthopedic surgeon, hence the importance of the teaching quality of pediatric residents for conservative fracture treatment.

Pediatric phalanx fractures: A retrospective study and review of the literature.

Purpose: Conventional radiography is frequently performed in pediatric patients in whom finger fractures are suspected. However, until now, the rate of positive findings of finger radiographic examinations in pediatric patients is unknown. This study aimed to evaluate the number of positive findings in the standard radiographic examinations of finger injuries in pediatric patients in a Level 1 trauma center systematically. Methods: We conducted a retrospective study on all children 0-16 years old admitted for acute finger injury in the Emergency Department of a University Hospital during the first semester of 2019 and received a radiographic examination. Their demographic characteristics, fracture pattern, and treatment were then analyzed and interpreted. Results: Out of 478 finger injuries reviewed in this cohort, 160 X-rays revealed positive for a fracture giving a fracture rate of 33.5%. More than half of them (51.9%) occurred in the age group of adolescents (11-16 years). Among all finger fractures, only 3.8% of them treated surgically. Conclusion: In this study, a relevant amount of standard finger radiographs revealed a low fracture rate and a rare operative indication of 3.8%. Therefore, indications for X-rays should be reviewed properly and alternative procedures should be discussed. Clinical decision rules should be developed and the necessary pathways must be implemented to minimize radiation exposure, waiting time, and costs.Level of evidence: level IV.

Comparison of treatment outcomes of stable and unstable developmental dysplasia of the hip with the Tübingen splint.

Background: The Tübingen splint was initially developed for the treatment of stable developmental hip dysplasia (DDH). Later on, some authors expanded its include for the treatment of unstable DDH, but there remain some controversies in the literature. This study aims to compare the outcome between stable and unstable DDH treated with a Tübingen splint. Methods: Epidemiological data and ultrasonographic data of all infants diagnosed with DDH and initially treated with a Tübingen splint at our institution between May 2017 and February 2020 were assessed retrospectively. We divided the population into stable and unstable hips using the Graf classification. Age at treatment initiation, duration of treatment, complications, and radiological outcome between 12 and 24 months were investigated. Results: We included a total of 45 patients (57 hips) affected by DDH treated with the Tübingen splint. Treatment has been successful in 93% of stable hips and only 40% of unstable hips. Radiological outcome at 1-year follow-up significantly correlated with initial Graf classification (p < 0.001). Conclusion: The Tübingen splint is a safe and effective treatment for stable hips, nevertheless, for unstable hips, closed reduction, and spica cast remains the gold standard.

Diagnostic Utility of Synovial Fluid Cell Counts and CRP in Pediatric Knee Arthritis: A 10-Year Monocentric, Retrospective Study.

BACKGROUND: Orthopedic surgeons often use the intra-articular white blood counts (WBCs) and the percentage of polymorphonuclear cells (PMN) in the diagnosis of an acute swollen and painful knee joint in children. Today, there is no established threshold for the synovial WBC, and their differentiation, as indicative of native joint knee bacterial arthritis. We determine the sensitivity and specificity of synovial WBCs and PMN percentages in the prediction of a community-acquired, acute bacterial native joint septic arthritis (SA) in the pediatric population. METHODS: A retrospective study on healthy children 0-16 years of age who underwent knee joint aspiration for a community-acquired, acute irritable knee effusion in our tertiary-care children's hospital between May 2009 and April 2019 was conducted. We divided the study population into two groups according to the detection of bacterial arthritis in the synovial fluid (bacterial arthritis versus its absence) and compared the intra-articular leukocyte and C-reactive protein (CRP) levels. RESULTS: Overall, we found a statistically significant difference regarding the total CRP (p = 0.017), leukocyte or PMN counts (p ≤ 0.001 in favor of a bacterial arthritis). In contrast, the percentage of the neutrophils was not determinant for the later confirmation of bacterial pathogens, and we were unable to establish diagnostically determining minimal thresholds of the intra-articular CRP and leukocyte levels. CONCLUSIONS: This pilot study suggests that either the leukocyte or PMN counts may be associated with a bacterial origin of knee arthritis in children. We plan a larger prospective interventional study in the future to confirm these findings including the investigation of other joint aspirate biomarkers.

A Single Retrograde Intramedullary Nail Technique for Treatment of Displaced Proximal Humeral Fractures in Children: Case Series and Review of the Literature.

Displaced proximal humeral fractures in older children with low remodeling potential need to be reduced and fixed. There are many options for stabilization, including external fixation, rigid internal fixation with screws and plates, percutaneous pinning, and flexible intramedullary nailing. The use of 2 flexible retrograde nails, originated at the University of Nancy, France, became the most popular technique in Europe. The aim of this study was to describe and assess a modified, single retrograde nail technique to treat fractures of the proximal part of the humerus. METHODS: We performed a retrospective monocentric study. From June 2016 to May 2019, a modified retrograde nail technique with 1 prebent nail was used for the management of 21 consecutive children with a closed displaced proximal humeral fracture. Demographic and surgical data were collected. The surgical technique is similar to the classic elastic stable intramedullary nailing, but only 1 nail is used. The average surgical time and perioperative complications were used as criteria for the feasibility of this technique. Radiographs were obtained preoperatively; at 1, 4, and 6 weeks postoperatively; and after implant removal at an average of 4.2 months postoperatively. The clinical outcomes were assessed on the basis of the shoulder range of motion documented in the medical records and by using the French edition of the QuickDASH (shortened version of the Disabilities of the Arm, Shoulder and Hand [DASH] questionnaire) evaluation scale at the time of implant removal. RESULTS: Nineteen patients with a mean age of 12.6 years and a mean follow-up of 6 months were included in the study. The mean surgical time was 49 minutes. The single intramedullary nail technique provided a satisfactory reduction of all fractures. No perioperative complication occurred. In 1 case, partial loss of reduction was observed on the first-week control radiograph. All patients had a healed fracture, no deficits, excellent results according to the QuickDASH score, a normal range of motion, and excellent strength of the shoulder joint at the time of implant removal (at a mean of 4.2 months). CONCLUSIONS: The current study confirms the feasibility and efficacy of the single retrograde intramedullary nail technique to treat displaced proximal humeral fractures in children. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.