Comparison of knee joint and temporomandibular joint development in pig embryos.

Although the knee joint (KNJ) and temporomandibular joint (TMJ) all belong to the synovial joint, there are many differences in developmental origin, joint structure and articular cartilage type. Studies of joint development in embryos have been performed, mainly using poultry and rodents. However, KNJ and TMJ in poultry and rodents differ from those in humans in several ways. Very little work has been done on the embryonic development of KNJ and TMJ in large mammals. Several studies have shown that pigs are ideal animals for embryonic development research. Embryonic day 30 (E30), E35, E45, E55, E75, E90, Postnatal day 0 (P0) and Postnatal day 30 (P30) embryos/fetuses from the pigs were used for this study. The results showed that KNJ develops earlier than TMJ. Only one mesenchymal condensate of KNJ is formed on E30, while two mesenchymal condensates of TMJ are present on E35. All structures of KNJ and TMJ were formed on E45. The growth plate of KNJ begins to develop on E45 and becomes more pronounced from E55 to P30. From E75 to E90, more and more vascular-rich cartilage canals form in the cartilage regions of both joints. The cartilaginous canal of the TMJ divides the condyle into sections along the longitudinal axis of the condyle. This arrangement of cartilaginous canal was not found in the KNJ. The chondrification of KNJ precedes that of TMJ. Ossification of the knee condyle occurs gradually from the middle to the periphery, while that of the TMJ occurs gradually from the base of the mandibular condyle. In the KNJ, the ossification of the articular condyle is evident from P0 to P30, and the growth plate is completely formed on P30. In the TMJ, the cartilage layer of condyle becomes thinner from P0 to P30. There is no growth plate formation in TMJ during its entire development. There is no growth plate formation in the TMJ throughout its development. The condyle may be the developmental center of the TMJ. The chondrocytes and hypertrophic chondrocytes of the growth plate are densely arranged. The condylar chondrocytes of TMJ are scattered, while the hypertrophic chondrocytes are arranged. Embryonic development of KNJ and TMJ in pigs is an important bridge for translating the results of rodent studies to medical applications.

Global Gene Expression Analysis Identifies Age-Related Differences in Knee Joint Transcriptome during the Development of Post-Traumatic Osteoarthritis in Mice.

Aging and injury are two major risk factors for osteoarthritis (OA). Yet, very little is known about how aging and injury interact and contribute to OA pathogenesis. In the present study, we examined age- and injury-related molecular changes in mouse knee joints that could contribute to OA. Using RNA-seq, first we profiled the knee joint transcriptome of 10-week-old, 62-week-old, and 95-week-old mice and found that the expression of several inflammatory-response related genes increased as a result of aging, whereas the expression of several genes involved in cartilage metabolism decreased with age. To determine how aging impacts post-traumatic arthritis (PTOA) development, the right knee joints of 10-week-old and 62-week-old mice were injured using a non-invasive tibial compression injury model and injury-induced structural and molecular changes were assessed. At six-week post-injury, 62-week-old mice displayed significantly more cartilage degeneration and osteophyte formation compared with young mice. Although both age groups elicited similar transcriptional responses to injury, 62-week-old mice had higher activation of inflammatory cytokines than 10-week-old mice, whereas cartilage/bone metabolism genes had higher expression in 10-week-old mice, suggesting that the differential expression of these genes might contribute to the differences in PTOA severity observed between these age groups.

A 2-year follow-up MRI study for the evaluation of an age estimation method based on knee bone development.

Age estimation is an actual topic in the area of forensic medicine with a special focus on the age limits of 16 and 18 years. Current research on this topic relies on retrospective data of inhomogeneous populations relating to sex, age range, and socioeconomic status. In this work, we present a 2-year follow-up study for the evaluation of an age estimation method on a prospective magnetic resonance imaging (MRI) knee data collective of a homogeneous population. The study includes 40 male subjects from northern Germany aged 14 to 21 years. Three MRI examinations were evenly acquired within 2 years for each subject. As a first evaluation, a three-stage system was used to assess the ossification status of the knee (I:"open", II:"partially ossified", III:"fully ossified"). Three raters assessed the growth plate of the distal femur, proximal tibia, and proximal fibula based on central 2D slices. A good inter-rater agreement was attained (κ = 0.84). All subjects younger than 18 years were rated as stage I and had a cumulative knee score (SKJ) ≤ 5. Based on the follow-up datasets, new parameters quantifying the intra-individual ossification process were calculated. The results of this follow-up analysis show a different start, end, and speed of each growth plate's maturation as well as an ossification peak for individuals at the age of 16. The generated MRI database provides new insights into the ossification process over time and serves as a basis for further evaluations of age estimation methods.

Similar regeneration of articular cartilage defects with autologous & allogenic chondrocytes in a rabbit model.

Background & objectives: Articular cartilage defects in the knee have a very poor capacity for repair due to avascularity. Autologous chondrocyte transplantation (ACT) is an established treatment for articular cartilage defects. Animal studies have shown promising results with allogenic chondrocyte transplantation since articular cartilage is non-immunogenic. In addition to being economical, allogenic transplantation has less morbidity compared to ACT. This study was undertaken to compare ACT with allogenic chondrocyte transplantation in the treatment of experimentally created articular cartilage defects in rabbit knee joints. Methods: Cartilage was harvested from the left knee joints of six New Zealand white rabbits (R1-R6). The harvested chondrocytes were cultured to confluence and transplanted onto a 3.5 mm chondral defect in the right knees of 12 rabbits [autologous in 6 rabbits (R1-R6) and allogenic in 6 rabbits (R7-R12)]. After 12 wk, the rabbits were euthanized and histological evaluation of the right knee joints were done with hematoxylin and eosin and safranin O staining. Quality of the repair tissue was assessed by the modified Wakitani histological grading scale. Results: Both autologous and allogenic chondrocyte transplantation resulted in the regeneration of hyaline/mixed hyaline cartilage. The total histological scores between the two groups showed no significant difference. Interpretation & conclusions: Allogenic chondrocyte transplantation seems to be as effective as ACT in cartilage regeneration, with the added advantages of increased cell availability and reduced morbidity of a single surgery.

Rebound Deformity After Growth Modulation in Patients With Coronal Plane Angular Deformities About the Knee: Who Gets It and How Much?

BACKGROUND: With observed success and increased popularity of growth modulation techniques, there has been a trend toward use in progressively younger patients. Younger age at growth modulation increases the likelihood of complete deformity correction and need for implant removal before skeletal maturity introducing the risk of rebound deformity. The purpose of this study was to quantify magnitude and identify risk factors for rebound deformity after growth modulation. METHODS: We performed a retrospective review of all patients undergoing growth modulation with a tension band plate for coronal plane deformity about the knee with subsequent implant removal. Exclusion criteria included completion epiphysiodesis or osteotomy at implant removal, ongoing growth modulation, and <1 year radiographic follow-up without rebound deformity. Mechanical lateral distal femoral angle, mechanical medial proximal tibial angle, hip-knee-ankle angle (HKA), and mechanical axis station were measured before growth modulation, before implant removal, and at final follow-up. RESULTS: In total, 67 limbs in 45 patients met the inclusion criteria. Mean age at growth modulation was 9.8 years (range, 3.4 to 15.4 y) and mean age at implant removal was 11.4 years (range, 5.3 to 16.4 y). Mean change in HKA after implant removal was 6.9 degrees (range, 0 to 23 degrees). In total, 52% of patients had >5 degrees rebound and 30% had >10 degrees rebound in HKA after implant removal. Females below 10 years and males below 12 years at time of growth modulation had greater mean change in HKA after implant removal compared with older patients (8.4 vs. 4.7 degrees, P=0.012). Patients with initial deformity >20 degrees had an increased frequency of rebound >10 degrees compared with patients with less severe initial deformity (78% vs. 22%, P=0.002). CONCLUSIONS: Rebound deformity after growth modulation is common. Growth modulation at a young age and large initial deformity increases risk of rebound. However, rebound does not occur in all at risk patients, therefore, we recommend against routine overcorrection. LEVEL OF EVIDENCE: Level IV-retrospective study.

The Spatial Order of Physeal Maturation in the Normal Human Knee Using Magnetic Resonance Imaging.

BACKGROUND: The spatial order of physeal maturation around the distal tibia has been shown to place adolescent patients at risk for certain transitional injuries, such as Tillaux or triplane fractures. Less is known about physeal maturation around the knee. The purpose of this study was to establish the spatial order of physeal maturation in the normal human knee using magnetic resonance imaging (MRI). METHODS: We retrospectively collected all knee MRI scans from patients presenting to our institution from January 2004 to January 2014. Patients who were suspected on the basis of clinical or radiographic findings of having abnormal knee physeal development or injury were excluded. We then applied a previously described MRI staging system of knee physeal maturation to the MRI scans of the remaining patients at 8 defined knee locations. Associations between the stage of maturation and mean chronological age were then evaluated across the 8 knee locations. Interrater and intrarater reliabilities were assessed. RESULTS: A total of 165 knee MRI scans (from 98 boys, 67 girls) met the inclusion criteria. Significant differences were found between each stage of physeal maturation and the mean chronological ages at all 8 knee locations for both boys and girls (each, P<0.001). Interestingly, within each stage of physeal maturation, no significant difference was found in the mean chronological ages at any of the 8 knee locations, suggesting that physeal development occurs uniformly in the normal human knee for both boys and girls. Interrater and intrarater reliability were nearly perfect at all locations. CONCLUSIONS: The spatial order of physeal maturation in the normal human knee was uniform across 8 knee locations for both boys and girls. This uniformity may help to explain why transitional injuries do not follow a recognizable pattern in the knee. Furthermore, the uniformity aids with surgical decision making, because minimal growth modulation or disturbance is likely when early physeal closure is present in a portion of the physis. LEVEL OF EVIDENCE: Level III.

Removal of Metaphyseal Screw Only After Hemiepiphysiodesis Correction of Coronal Plane Deformities Around the Knee Joint: Is This a Safe and Advisable Strategy?

PURPOSE: Correcting lower limb angular deformities in the skeletally immature patient with guided growth is a very common procedure. Using an 8-plate construct to produce reversible hemiepiphysiodesis allows correction of the mechanical axis of the limb. It has become routine strategy to remove only the metaphyseal screw from the 8-plate construct after desired correction is achieved, in order to ease its reinsertion in case of deformity recurrence. In this study, we evaluated the efficacy and safety of this technique. METHODS: We reviewed the results of 80 patients (133 limbs) who were treated by guided growth using 8-plate hemiephisiodesis around the knee. After achievement of the correction goal, both screws and plate were removed in 78 limbs while only the metaphyseal screw was removed in 55 limbs. RESULTS: The mean age of patient was 8.9 years at the time of surgery. Within the group whose metaphyseal screw was removed, 12 limbs showed radiographic signs of deformity recurrence and underwent reinsertion of the metaphyseal screw. In 9 of the cases of metaphyseal screw reinsertion, the plate or its location had to be changed (mean follow-up after screw removal was 14 mo). There were 2 cases where leaving the plate with an epiphyseal screw caused a radiographic bone bar and undesired clinical growth arrest. CONCLUSIONS: On the basis of our experience, leaving the 8-plate construct with an epiphyseal screw in place exposes the patient to risks of bony bar, growth arrest, and an additional surgery for hardware removal. The majority of 8-plate constructs are not suitable for reinsertion of the metaphyseal screw.

Cell origin, volume and arrangement are drivers of articular cartilage formation, morphogenesis and response to injury in mouse limbs.

Limb synovial joints are composed of distinct tissues, but it is unclear which progenitors produce those tissues and how articular cartilage acquires its functional postnatal organization characterized by chondrocyte columns, zone-specific cell volumes and anisotropic matrix. Using novel Gdf5CreERT2 (Gdf5-CE), Prg4-CE and Dkk3-CE mice mated to R26-Confetti or single-color reporters, we found that knee joint progenitors produced small non-migratory progenies and distinct local tissues over prenatal and postnatal time. Stereological imaging and quantification indicated that the columns present in juvenile-adult tibial articular cartilage consisted of non-daughter, partially overlapping lineage cells, likely reflecting cell rearrangement and stacking. Zone-specific increases in cell volume were major drivers of tissue thickening, while cell proliferation or death played minor roles. Second harmonic generation with 2-photon microscopy showed that the collagen matrix went from being isotropic and scattered at young stages to being anisotropic and aligned along the cell stacks in adults. Progenitor tracing at prenatal or juvenile stages showed that joint injury provoked a massive and rapid increase in synovial Prg4+ and CD44+/P75+ cells some of which filling the injury site, while neighboring chondrocytes appeared unresponsive. Our data indicate that local cell populations produce distinct joint tissues and that articular cartilage growth and zonal organization are mainly brought about by cell volume expansion and topographical cell rearrangement. Synovial Prg4+ lineage progenitors are exquisitely responsive to acute injury and may represent pioneers in joint tissue repair.

2018 International Olympic Committee consensus statement on prevention, diagnosis and management of paediatric anterior cruciate ligament (ACL) injuries.

In October 2017, the International Olympic Committee hosted an international expert group of physiotherapists and orthopaedic surgeons who specialise in treating and researching paediatric anterior cruciate ligament (ACL) injuries. Representatives from the American Orthopaedic Society for Sports Medicine, European Paediatric Orthopaedic Society, European Society for Sports Traumatology, Knee Surgery and Arthroscopy, International Society of Arthroscopy Knee Surgery and Orthopaedic Sports Medicine, Pediatric Orthopaedic Society of North America, and Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte attended. Physiotherapists and orthopaedic surgeons with clinical and research experience in the field, and an ethics expert with substantial experience in the area of sports injuries also participated. Injury management is challenging in the current landscape of clinical uncertainty and limited scientific knowledge. Injury management decisions also occur against the backdrop of the complexity of shared decision-making with children and the potential long-term ramifications of the injury. This consensus statement addresses six fundamental clinical questions regarding the prevention, diagnosis, and management of paediatric ACL injuries. The aim of this consensus statement is to provide a comprehensive, evidence-informed summary to support the clinician, and help children with ACL injury and their parents/guardians make the best possible decisions.

Skeletal assessment and secular changes in knee development: a radiographic approach.

OBJECTIVES: The purpose of this study is to conduct an analysis of ossification patterns in the distal femoral, proximal tibial, and proximal fibular epiphyses, and the patella. The results generated from this analysis will be compared with previous standards published by Elgenmark () and Garn et al. () to determine if clinical and skeletal age assessment standards should be updated for contemporary Americans. MATERIALS AND METHODS: Using the Pediatric Radiology Interactive Atlas (Patricia), a total of 1,317 epiphyses were scored for presence or absence from radiographs of 1,056 white individuals born in or after 1990. Statistical modeling of epiphyseal appearance was conducted for all major percentiles, including the 5th and 95th percentiles through logistic regression. RESULTS: Compared with Elgenmark () and Garn et al. (), our data suggest that the distal femoral and proximal tibial epiphyses show overall earlier ossification, while the proximal fibular epiphysis shows later ossification. When examining the pooled sex 50th percentile for our data, we found that ossification timing differences are 1.2 weeks earlier in the distal femoral epiphysis, 2.1 weeks earlier in the proximal tibial epiphysis, and 1.4 years later in the proximal fibular epiphysis. DISCUSSION: The epiphyses that appear early in life, for example the distal femoral epiphysis, require gestational age information to accurately estimate appearance times. There are considerable differences between the ossification timing patterns presented in this study and those of previous standards, which did not include gestational ages. Several factors may explain the observed differences in the epiphyses of the knee including: the availability of gestational age information, the analysis of longitudinal versus cross-sectional data, differences in socioeconomic status and prenatal care, and secular change. KEYWORDS age estimation, growth standards, ossification, skeletal maturation, subadult/juvenile growth.

Radiographic Assessment of Guided Growth: The Correlation Between Screw Divergence and Change in Anatomic Alignment.

BACKGROUND: Assessment of changes in anatomic alignment following guided growth traditionally utilizes full-length standing radiographs which subjects patients to larger radiation doses than does a single anteroposterior radiograph of the knee. In an effort to minimize radiation exposure, the present study sought to determine whether changes in screw divergence (SD) of the 2-hole tension band plate used for hemiepiphysiodesis reliably predicts change in alignment. METHODS: A retrospective review was conducted involving all patients with genu varum or genu valgum treated with hemiepiphysiodesis at a single institution. Preoperative anatomic alignment of the femur, using anatomic lateral distal femoral angle (aLDFA) and anatomic femoral-tibial angle (aTFA), and intraoperative divergence of hemiepiphysiodesis screws were compared with postoperative imaging. Linear regression analysis determined the relationship between changes in SD and changes in alignment, and multivariate regression analysis explored the relationship between the angular changes being measured and various demographic factors. RESULTS: Linear regression analysis revealed that for every 1 degree change in SD there was a resultant 1.80 degrees of change in aTFA and 2.11 degrees of change in aLDFA. Change in aTFA is predicted by the equation: [INCREMENT]aTFA=0.41×|[INCREMENT]SD|+1.39. The change in aLDFA was predicted by the equation [INCREMENT]aLDFA=0.27×[INCREMENT]SD+1.84 with a R2 of 0.31. [INCREMENT]aTFA and [INCREMENT]SD had a correlation coefficient of 0.68 (95% confidence interval, 0.54-0.78.) [INCREMENT]aLDFA and [INCREMENT]SD had a correlation coefficient of 0.56 (95% confidence interval, 0.42-0.68). [INCREMENT]SD and sex were the only 2 independent predictors for [INCREMENT]aLDFA and [INCREMENT]aTFA as determined by multivariate regression analysis. CONCLUSION: Change in coronal plane anatomic alignment in patients being treated for genu valgum or genu varum with hemiepiphysiodesis can be reasonably estimated by measuring the change in SD. Therefore, when following patients postoperatively, focal radiographic imaging of the knee can be utilized in lieu of standing full-length limb radiographs to limit radiation to the pelvis in this sensitive patient population. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Angular deformity correction by guided growth in growing children: Eight-plate versus 3.5-mm reconstruction plate.

BACKGROUND: Guided growth using the eight-plate (8-plate) is the most commonly used method to correct angular deformities in children; however, implant failure has been reported. Recently, the 3.5-mm reconstruction plate (R-plate) has been used as an alternative option for guided growth; however, hardware prominence has been problematic. This study aimed to compare the coronal angular deformity correction results of guided growth between relatively thin 8-plates with cannulated screws and thick R-plates with solid screws. METHODS: Thirty-nine physes (24 distal femoral, 15 proximal tibial) in 20 patients underwent hemiepiphysiodesis using 8-plates, and 61 physes (40 distal femoral, 21 proximal tibial) in 35 patients underwent hemiepiphysiodesis using R-plates. Coronal angular corrections were measured and compared preoperatively, and after the completion of corrections. Amounts and rates of correction and complications were compared between the groups. RESULTS: Mean body mass index was 18.7 kg/m2 in the 8-plate group, and 22.7 kg/m2 in the R-plate group. Angular correction was achieved in all deformities at a mean of 13.7 months and 19.7 months in the 8-plate and the R-plate group, respectively. The mean corrected mechanical lateral distal femoral angle was 9.0° in the 8-plate group, and 9.9° in the R-plate group (P = 0.55). The mean corrected medial proximal tibial angle was 7.1° in the 8-plate group, and 9.0° in the R-plate group (P = 0.07). The mean rates of angular correction were also not significantly different in the distal femur (1.03°/month vs. 0.77°/month, P = 0.2) and the proximal tibia (0.66°/month vs. 0.63°/month, P = 0.77). There was one superficial infection in each group, and one case of implant failure in the R-plate group. Two rebound deformities were observed and needed repeat hemiepiphysiodesis. Permanent physeal arrest was not observed in this series.

Copy number variation in CEP57L1 predisposes to congenital absence of bilateral ACL and PCL ligaments.

BACKGROUND: Absence of the anterior (ACL) or posterior cruciate ligament (PCL) are rare congenital malformations that result in knee joint instability, with a prevalence of 1.7 per 100,000 live births and can be associated with other lower-limb abnormalities such as ACL agnesia and absence of the menisci of the knee. While a few cases of absence of ACL/PCL are reported in the literature, a number of large familial case series of related conditions such as ACL agnesia suggest a potential underlying monogenic etiology. We performed whole exome sequencing of a family with two individuals affected by ACL/PCL. RESULTS: We identified copy number variation (CNV) deletion impacting the exon sequences of CEP57L1, present in the affected mother and her affected daughter based on the exome sequencing data. The deletion was validated using quantitative PCR (qPCR), and the gene was confirmed to be expressed in ACL ligament tissue. Interestingly, we detected reduced expression of CEP57L1 in Epstein-Barr virus (EBV) cells from the two patients in comparison with healthy controls. Evaluation of 3D protein structure showed that the helix-binding sites of the protein remain intact with the deletion, but other functional binding sites related to microtubule attachment are missing. The specificity of the CNV deletion was confirmed by showing that it was absent in ~700 exome sequencing samples as well as in the database of genomic variations (DGV), a database containing large numbers of annotated CNVs from previous scientific reports. CONCLUSIONS: We identified a novel CNV deletion that was inherited through an autosomal dominant transmission from an affected mother to her affected daughter, both of whom suffered from the absence of the anterior and posterior cruciate ligaments of the knees.

Variability in developmental timings of the knee in young American children as assessed through Pyle and Hoerr's radiographic atlas.

This study examines the accuracy of the Pyle and Hoerr radiographic atlas technique in an effort to document the extent of normal variation associated with developmental timings in the knee for purposes of age estimation. The atlas has been previously tested; however, accuracy rates were produced from a dataset, which spread in age from mostly 7-16 years. This study took a closer look at the younger age groups, examining radiographs from 297 children (147 female and 150 male) from birth to 6 years. Standard deviations representing the difference between the skeletal and chronological age were calculated according to two groupings. Each group represents episodes, or time periods, of differential developmental rates as expressed through the number of plates within the atlas dedicated to documenting each year of life. The beginning year of life is characterized by the most rapid of development as represented by the numerous image plates used to depict this time period. Individuals assigned to plates with a skeletal age between birth and 1 year were grouped collectively to document the variation associated with such rapidly changing morphology (SD = 2.5 months in female children; 2.3 months in male children). Years 1-3.8 years (female) and 1-4.5 years (male) were represented by two or three images within the atlas, and therefore, individuals assigned to plates with a skeletal age falling within this range were placed within a second grouping (SD = 5.2 months in female children; 7.0 months in male children). As expected, variation was observed to decrease as developmental processes accelerated in the younger children. The newly calculated standard deviations offer tighter predictions for estimating age in young children while at the same time maintaining an acceptable width that accounts for normal variation in developmental timings.

Accuracy of scoring of the epiphyses at the knee joint (SKJ) for assessing legal adult age of 18 years.

Important aspects of forensic practice are age estimation and discrimination of individuals of unknown age as adults and minors. The developing knee joint was recognized as a potential site for age examination in late adolescence. We analyzed a sample of anteroposterior x-rays of the knee joints from 446 living individuals from Umbria, Italy (234 males and 212 females), aged between 12 and 26 years. We evaluated the ossification of the distal femoral (DF), proximal tibial (PT), and proximal fibular (PF) epiphyses. We took into account possible persistence of the epiphyseal scars in the ossified epiphyses by the adopted stages of those previously introduced by Cameriere et al. (2012). We also used measurements from all three epiphyses to calculate the total score of maturation for the knee joint (SKJ). Cohen Kappa coefficients of intrarater agreement for staging the DF, PT, and PF epiphyses were 0.839, 0.894, and 0.907, while interrater agreement was 0.919, 0.791, and 0.907, respectively. The resulting receiver operating characteristic (ROC) curves of SKJ show better discriminatory power than those for DF, PT, and PF epiphyses in predicting that the participant, either male or female, was an adult or a minor. The areas under the curves for SKJ were 0.991 and 0.968 vs. 0.944, 0.962, 0.974 and 0.891, 0.910, 0.918 for males and females, respectively. The results of the 2 by 2 contingency tables showed that SKJ score of 4 in males and SKJ score of 5 in females were the most suitable cut-off value in discriminating between adults and minors. Principally, the sensitivity test for males was 0.94, with 95 % confidence interval (95 % CI) 0.90 to 0.97 and specificity was 0.96 (95 % CI 0.91 to 0.98). The proportion of correctly classified individuals was 0.95 (95 % CI 0.91 to 0.97). For females, the sensitivity test was 0.89 (95 % CI 0.84 to 0.92) and specificity was 0.92 (95 % CI 0.87 to 0.96), the proportion of correctly classified individuals was 0.90 (95 % CI 0.85 to 0.94). These results indicate that the SKJ method may give valuable supporting information in forensic procedures for discriminating individuals of legal adult age of 18 years. Further studies should address the usefulness of the SKJ method in different populations.

Anterior cruciate ligament and intercondylar notch growth plateaus prior to cessation of longitudinal growth: an MRI observational study.

PURPOSE: Increasing numbers of children and adolescents are being treated for ACL tears. In order for surgeons to safely optimize treatment during ACL surgery, we must better understand ACL growth and intercondylar notch patterns in the skeletally immature knee. The aim of this study is to measure ACL and intercondylar notch volume in paediatric patients and observe how these volumes change as a function of age and gender. METHODS: Data were extracted from the picture archiving and communication systems (PACS) computer records. Sample consisted of 137 MRI knee examinations performed between January 2006 and July 2010 in patients aged 3-13. Subjects were grouped into 1-year age intervals. Patients with imaging reports including ACL tears, previous surgeries, congenital structural anomalies, or syndromes were excluded. RESULTS: Measures of ACL volume significantly increased with age (P < 0.001). A linear increase in ACL volume was observed until the age 10, with a mean increase in volume of 148 mm(3) per age group. ACL volume plateaued at 10 years, after which minimal increase in ACL volume was observed. Sex was not found to be a significant predictor of ACL volume in the multiple linear regression (P = 0.57). Similar to ACL volume, there was a significant increase in intercondylar notch volume with age with a mean increase of 835 mm(3) per age group (P < 0.0001). Intercondylar notch volume reached a plateau at age 10, after which a minimal increase in notch volume was observed in older groups. Female patients had notch volumes that were on average 892 + 259 mm(3) smaller than male patients who were in the same age group (P = 0.0006). CONCLUSION: The plateau in the growth of ACL and notch volume occurs at age 10, prior to the halt in longitudinal growth of boys and girls. Female patients have significantly smaller intercondylar notch volumes than their age-matched male counterparts, while no gender difference was seen in ACL volume. These results suggest that notch volume is an intrinsically sex-specific difference, which may contribute to the higher rate of ACL tears among females. These growth patterns are clinically relevant as it allows surgeons to better understand the anatomy, pathology, and risk factors related to ACL tears and its reconstruction. LEVEL OF EVIDENCE: Observational Study, Level IV.

Intraarticular hamstring graft diameter decreases with continuing knee growth after ACL reconstruction with open physes.

PURPOSE: To evaluate the graft diameter size after one-year follow-up or more of patients Tanner II, III, and IV who were submitted to anterior cruciate ligament reconstruction. METHODS: Ten patients [five males (mean age: 14.4 years) and five females (mean age: 13.6 years)] with open physis and anterior cruciate ligament tear were submitted to transphyseal anterior cruciate ligament reconstruction with quadruple hamstrings graft. During the procedure, graft and tunnel size were recorded. After last clinical follow-up (range 1-11 years), an MRI study was requested and their measurements near the tibial tunnel were compared with the graft diameter measured and used during primary procedure. RESULTS: Four patients had Tanner stage II, four patients Tanner stage III, and two Tanner IV. There were statistically significant decreases in the quadruple hamstrings graft diameter size (average of 25.3%). Mean size at time of surgery was 7.9 mm (±0.87), and mean size measured at different points of follow-up evaluation was 5.9 mm (±0.65). CONCLUSION: Diameter size of hamstring graft in skeletally immature patients is smaller in most cases. If there is a decrease in the diameter of the graft along postoperative time, the risk of a re-rupture is theoretically further increased. Quadruple hamstring graft decreases a mean 25.3% in diameter from time of anterior cruciate ligament reconstruction surgery until reassessment period in skeletally immature patients. LEVEL OF EVIDENCE: IV.

Anterior cruciate ligament reconstruction in adolescents (Tanner stages 2 and 3).

PURPOSE: Management of anterior cruciate ligament injuries in skeletally immature patients (in Tanner stages 2 and 3) is controversial. Conventional reconstruction used in adults can cause iatrogenic growth disturbance due to physeal damage, and studies that report long-term results using a specific technique are scarce. The aim of this study is to evaluate in a large series the mid- and long-term results of a partial transphyseal technique and define the safe percentage of lesions of the femoral growth plate. METHODS: Between 1989 and 2012, 42 adolescents at risk of growth disturbances (growth prediction of lower limbs >5 cm-Tanner 2, 3) underwent reconstruction of the anterior cruciate ligament using the semitendinosus and gracilis tendons. Growth characteristics of all the patients were assessed preoperatively, and the percentage of damage that would be produced in the femoral physis by the drilling of a 6-mm-diameter tunnel was determined. The technique used achieved graft fixation at both insertion sites, drilling the femoral physis and avoiding the tibial physis. We distinguished two groups: (a) long-term follow-up (mean 13 years 7 months, min 10.9, max 16.2) and (b) medium follow-up (mean 6 years 3 months, min 3.7, max 9.9). All knees were evaluated subjectively by history and objectively by KT2000 testing, and X-rays of both knees were compared for osteoarthritis using the Kellgren-Lawrence classification. RESULTS: In group A (12 patients) one osteoarthritis grade 2, one instability, and ten good stability and function were observed. The mean KT2000 arthrometer values at 30 lb showed a difference of +2.4 mm (range 1-4 mm) between the operated and non-operated sides (p < 0.05). In group B (21 patients) no growth disturbance of the lower limbs, two failures (reinjury while participating in pivoting sports), and 19 good stability and function were observed. The mean KT2000 arthrometer values at 30 lb showed a difference of +1.9 mm (range 1-5 mm) between the operated and non-operated sides (p < 0.05). The average IKDC score of all the patients was 90 (min: 68, max: 97). None of the adolescents had consequences on growth after an eccentric damage passing tendons less than 7% on the frontal plane and of 1% on cross-sectional area of the femoral physis, and after an oblique tunnel passing 6-mm-diameter tendons of the tibial epiphyseal nucleus. CONCLUSIONS: This study defines the possibility to perform a partial transphyseal intra-articular ACL reconstruction in patients in Tanner stages 2 and 3 that avoids tibial physis, involves the distal femoral physis, and produces good results at mid- and long-term follow-up without causing growth disturbances. LEVEL OF EVIDENCE: IV.

How does lower leg alignment differ between soccer players, other athletes, and non-athletic controls?

PURPOSE: The influence of type and intensity of sports during growth on knee alignment was investigated. The second aim was to ascertain whether the distal femur or proximal tibia contribute most to knee alignment. Also, the influence of field position and leg dominancy on knee alignment in soccer players was audited. METHODS: Standardized full-leg standing digital radiographs were obtained from 100 males and 100 females on which 8 different alignment parameters were measured. Participants were questioned on their sports activities during different stages of growth. Sports activities were graded according to the Tegner score. RESULTS: The mean (±SD) hip-knee-ankle angle (HKA) was significantly lower (p < 0.001) in high-activity male athletes (-2.8° ± 2.4°) than in low-activity male athletes (-0.9° ± 1.9°). No differences in HKA were observed between different activity levels in females. Males who practiced soccer between 10-12 years and 15-17 years had, in turn, a lower HKA than athletes practicing other high-activity sports in these age categories (mean difference ≥1.2°, p ≤ 0.046). The most contributing factor for the varus alignment in male soccer players was a lower medial proximal tibial angle (MPTA). CONCLUSION: High-activity sports participation during youth is associated with varus alignment at the end of growth in males. The most pronounced bowlegs were observed in male soccer players, and this was primarily determined by the proximal tibia. Adjustments in loads applied to the knees during skeletal growth in males might prevent the development of varus alignment and associated pathology, but further studies are required. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Alteration of cartilage surface collagen fibers differs locally after immobilization of knee joints in rats.

The purpose of this study was to examine the ultrastructural changes of surface cartilage collagen fibers, which differ by region and the length of the experimental period in an immobilization model of rat. Male Wistar rats were randomly divided into histological or macroscopic and ultrastructural assessment groups. The left knees of all the animals were surgically immobilized by external fixation for 1, 2, 4, 8 or 16 weeks (n = 5/time point). Sagittal histological sections of the medial mid-condylar region of the knee were obtained and assessed in four specific regions (contact and peripheral regions of the femur and tibia) and two zones (superficial and deep). To semi-quantify the staining intensity of the collagen fibers in the cartilage, picrosirius red staining was used. The cartilage surface changes of all the assessed regions were investigated by scanning electron microscopy (SEM). From histological and SEM observations, the fibrillation and irregular changes of the cartilage surface were more severe in the peripheral region than in the contact region. Interestingly, at 16 weeks post-immobilization, we observed non-fibrous structures at both the contact and peripheral regions. The collagen fiber staining intensity decreased in the contact region compared with the peripheral region. In conclusion, the alteration of surface collagen fiber ultrastructure and collagen staining intensity differed by the specific cartilage regions after immobilization. These results demonstrate that the progressive degeneration of cartilage is region specific, and depends on the length of the immobilization period.