Fabricating vascularized, anatomically accurate bone grafts using 3D bioprinted sectional bone modules, in-situ angiogenesis, BMP-2 controlled release, and bioassembly.

Bone grafting is the most common treatment for repairing bone defects. However, current bone grafting methods have several drawbacks. Bone tissue engineering emerges as a promising solution to these problems. An ideal engineered bone graft should exhibit high mechanical strength, osteogenic properties, and pre-vascularization. Both top-down (using bulk scaffold) and bottom-up (using granular modules) approaches face challenges in fulfilling these requirements. In this paper, we propose a novel sectional modular bone approach to construct osteogenic, pre-vascularized bone grafts in anatomical shapes. We 3D-printed a series of rigid, thin, sectional, porous scaffolds from a biodegradable polymer, tailored to the dimensions of a femur bone shaft. These thin sectional modules promote efficient nutrition and waste removal due to a shorter diffusion distance. The modules were pre-vascularized viain-situangiogenesis, achieved through endothelial cell sprouting from the scaffold struts. Angiogenesis was further enhanced through co-culture with bioprinted fibroblast microtissues, which secreted pre-angiogenic growth factors. Sectional modules were assembled around a porous rod incorporated with Bone Morphogenetic Protein-2 (BMP-2), which released over 3 weeks, demonstrating sustained osteogenic activity. The assembled scaffold, in the anatomical shape of a human femur shaft, was pre-vascularized, osteogenic, and possessed high mechanical strength, supporting 12 times the average body weight. The feasibility of implanting the assembled bone graft was demonstrated using a 3D-printed femur bone defect model. Our method provides a novel modular engineering approach for regenerating tissues that require high mechanical strength and vascularization.

Cellular Patterning Alone Using Bioprinting Regenerates Articular Cartilage Through Native-Like Cartilagenesis.

Few studies have proved that bioprinting itself helps recapitulate native tissue functions mainly because the bioprinted macro shape can rarely, if ever, influence cell function. This can be more problematic in bioprinting cartilage, generally considered more challenging to engineer. Here a new method is shown to micro-pattern chondrocytes within bioprinted sub-millimeter micro tissues, denoted as patterned micro-articular-cartilages tissues (PA-MCTs). Under the sole influence of bioprinted cellular patterns. A pattern scoring system is developed after over 600 bioprinted cellular patterns are analyzed. The top-scored pattern mimics that of the isogenous group in native articular cartilage. Under the sole influence of this pattern during PA-MCTs bio-assembling into macro-cartilage and repairing cartilage defects, chondrogenic cell phenotype is preserved, and cartilagenesis is initiated and maintained. Neocartilage tissues from individual and assembled PA-MCTs are comparable to native articular cartilage and superior to cartilage bioprinted with homogeneously distributed cells in morphology, biochemical components, cartilage-specific protein and gene expression, mechanical properties, integration with host tissues, zonation forming and stem cell chondrogenesis. PA-MCTs can also be used as osteoarthritic and healthy cartilage models for therapeutic drug screening and cartilage development studies. This cellular patterning technique can pave a new way for bioprinting to recapitulate native tissue functions via tissue genesis.

Anterior vertebral tethering for adolescent idiopathic scoliosis: our initial ten year clinical experience.

BACKGROUND: Anterior vertebral tethering (AVT) is a minimally invasive alternative to fusion surgery for adolescent idiopathic scoliosis (AIS) that offers the potential for definitive scoliosis treatment with the possibility of preservation of the growth, motion, function and overall health of the spine. This study represents our first ten years using AVT to treat AIS. METHODS: In this retrospective review we analyzed our first 74 AIS patients treated with AVT 2010-2020. Multiple Lenke curve types 33-70° were treated with skeletal maturity spanning Risser -1 to 5. RESULTS: Of 74 consecutive AIS patients treated with AVT, 52 patients (47 female, 5 male) had sufficient 2-year follow-up for inclusion. Forty-six of these 52 patients (88%) with 65 curves (35T, 30TL/L) were satisfactorily treated with AVT demonstrating curve correction from 48.6° pre-op (range 33°-70°) at age 15.1 years (range 9.2-18.8) and skeletal maturity of Risser 2.8 (range -1 to 5) to 23.2° post-op (range 0°-54°) and 24.0° final (range 0°-49°) at 3.3 years follow-up (range 2-10 years). Curve corrections from pre-op to post-op and pre-op to final were both significant (p < 0.001). The 0.8° change from post-op to final was not significant but did represent good control of scoliosis correction over time. Thoracic kyphosis and lumbar lordosis were maintained in a normal range throughout while axial rotation demonstrated a slight trend toward improvement. Skeletal maturity of Risser 4 or greater was achieved in all but one patient. Four of the 52 patients (8%) required additional procedures for tether rupture (3 replacements) or overcorrection (1 removal) to achieve satisfactory treatment status after AVT. An additional 6 of the 52 patients (12%), however, were not satisfactorily treated with AVT, requiring fusion for overcorrection (2) or inadequate correction (4). CONCLUSIONS: In this study, AIS was satisfactorily treated with AVT in the majority of patients over a broad range of curve magnitudes, curve types, and skeletal maturity. Though late revision surgery for overcorrection, inadequate correction, or tether rupture was not uncommon, the complication of overcorrection was eliminated after our first ten patients by a refinement of indications. LEVEL OF EVIDENCE: IV.

Articular Cartilage Regeneration through Bioassembling Spherical Micro-Cartilage Building Blocks.

Articular cartilage lesions are prevalent and affect one out of seven American adults and many young patients. Cartilage is not capable of regeneration on its own. Existing therapeutic approaches for articular cartilage lesions have limitations. Cartilage tissue engineering is a promising approach for regenerating articular neocartilage. Bioassembly is an emerging technology that uses microtissues or micro-precursor tissues as building blocks to construct a macro-tissue. We summarize and highlight the application of bioassembly technology in regenerating articular cartilage. We discuss the advantages of bioassembly and present two types of building blocks: multiple cellular scaffold-free spheroids and cell-laden polymer or hydrogel microspheres. We present techniques for generating building blocks and bioassembly methods, including bioprinting and non-bioprinting techniques. Using a data set of 5069 articles from the last 28 years of literature, we analyzed seven categories of related research, and the year trends are presented. The limitations and future directions of this technology are also discussed.

Anterior vertebral tethering: imaging of tether rupture.

Anterior vertebral tethering, also known as vertebral body tethering, is an evolving, minimally invasive surgical technique to correct spinal curvature in skeletally immature patients. The procedure involves placement of vertebral screws that are connected by an anterolateral tether. This procedure may be complicated by rupture of the non-radiopaque tether. The radiologist should be aware of imaging findings that suggest this complication on follow-up spine radiographs.

A Thoracoscopic Technique Used in Anterior Vertebral Tethering for Adolescent Idiopathic Scoliosis.

Anterior vertebral tethering (AVT) is a relatively recent alternative to posterior spinal fusion for progressive curves in growing patients with idiopathic scoliosis. AVT uses a thoracoscopic approach to minimize trauma to the thoracic wall and chest cavity. There are limited technical descriptions of this method. Patients benefit from proficiency and reproducibility to allow for appropriate spinal curve correction over time. This Technical Note outlines the steps of the thoracoscopic approach to AVT and reviews the current indications for AVT over posterior spinal fusion, as well as the most recently published clinical outcomes of this procedure.

3D-printed insert-array and 3D-coculture-array for high-throughput screening of cell migration and application to study molecular and cellular influences.

Collective cell migration refers to the movement of groups of cells and collective cell behavior and relies on cell-cell communication and cell-environment interactions. Collective cell migration plays a fundamental role in many aspects of cell biology and pathology. Current protocols for studying collective cell migration either use destructive methods or are not convenient for liquid handling. Here we present a novel 3D-printed insert-array and a 3D-coculture-array for collective cell migration study in high-throughput. The fabricated insert-array is comprised of 96 cylinder shaped inserts which can be placed in each well of a 96-well plate generating watertight contact with the bottom of each well. The insert-array has high manufacturing tolerance, and the coefficient of variations of the insert diameter and circularity are 0.67% and 0.03%, respectively. Each insert generates a circular cell-free area within the well without cell damage and provides convenient access for both manual and robotic liquid handling. Using the 3D-printed insert-array, we studied the migration of human umbilical vein endothelial cells (HUVECs) under the molecular influences of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and under the cellular influences of human mesenchymal stem cells (hMSCs) using the 3D-coculture-array. Our results show that the migration of HUVECs was dose-dependent on the VEGF and bFGF with different correlation patterns. They also generated a synergic pro-migration effect. When cocultured with hMSCs, the migration rate increased significantly while dependent on the number of hMSCs. The effects were partially blocked by VEGF inhibitor which suggests that VEGF secreted from hMSCs plays an important role in cell-to-cell communication during cell migration. The 3D-coculture-array can be manufactured at very low cost and shows higher biomolecule transport efficiency than the commercially available transwell. The calculated Z-factor is 0.66, which classifies our system as a perfect high-throughput assay. In summary, our newly developed insert-array and 3D-coculture-array provide a versatile platform to study collective cell migration in high-throughput as well as the molecular and cellular influences upon it.

A Novel 3D Bioprinter Using Direct-Volumetric Drop-On-Demand Technology for Fabricating Micro-Tissues and Drug-Delivery.

Drop-on-demand (DOD) 3D bioprinting technologies currently hold the greatest promise for generating functional tissues for clinical use and for drug development. However, existing DOD 3D bioprinting technologies have three main limitations: (1) droplet volume inconsistency; (2) the ability to print only bioinks with low cell concentrations and low viscosity; and (3) problems with cell viability when dispensed under high pressure. We report our success developing a novel direct-volumetric DOD (DVDOD) 3D bioprinting technology that overcomes each of these limitations. DVDOD can produce droplets of bioink from < 10 nL in volume using a direct-volumetric mechanism with < ± 5% volumetric percent accuracy in an accurate spatially controlled manner. DVDOD has the capability of dispensing bioinks with high concentrations of cells and/or high viscosity biomaterials in either low- or high-throughput modes. The cells are subjected to a low pressure during the bioprinting process for a very short period of time that does not negatively impact cell viability. We demonstrated the functions of the bioprinter in two distinct manners: (1) by using a high-throughput drug-delivery model; and (2) by bioprinting micro-tissues using a variety of different cell types, including functional micro-tissues of bone, cancer, and induced pluripotent stem cells. Our DVDOD technology demonstrates a promising platform for generating many types of tissues and drug-delivery models.

Rapid Fabrication of Anatomically-Shaped Bone Scaffolds Using Indirect 3D Printing and Perfusion Techniques.

Fused deposit modeling (FDM) 3D printing technology cannot generate scaffolds with high porosity while maintaining good integrity, anatomical-surface detail, or high surface area-to-volume ratio (S/V). Solvent casting and particulate leaching (SCPL) technique generates scaffolds with high porosity and high S/V. However, it is challenging to generate complex-shaped scaffolds; and solvent, particle and residual water removal are time consuming. Here we report techniques surmounting these problems, successfully generating a highly porous scaffold with the anatomical-shape characteristics of a human femur by polylactic acid polymer (PLA) and PLA-hydroxyapatite (HA) casting and salt leaching. The mold is water soluble and is easily removable. By perfusing with ethanol, water, and dry air sequentially, the solvent, salt, and residual water were removed 20 fold faster than utilizing conventional methods. The porosities are uniform throughout the femoral shaped scaffold generated with PLA or PLA-HA. Both scaffolds demonstrated good biocompatibility with the pre-osteoblasts (MC3T3-E1) fully attaching to the scaffold within 8 h. The cells demonstrated high viability and proliferation throughout the entire time course. The HA-incorporated scaffolds demonstrated significantly higher compressive strength, modulus and osteoinductivity as evidenced by higher levels of alkaline-phosphatase activity and calcium deposition. When 3D printing a 3D model at 95% porosity or above, our technology preserves integrity and surface detail when compared with FDM-generated scaffolds. Our technology can also generate scaffolds with a 31 fold larger S/V than FDM. We have developed a technology that is a versatile tool in creating personalized, patient-specific bone graft scaffolds efficiently with high porosity, good scaffold integrity, high anatomical-shaped surface detail and large S/V.

Biofabrication of valentine-shaped heart with a composite hydrogel and sacrificial material.

3D bioprinting represents a potential solution for organs regeneration, however, the production of complex tissues and organs that are in large size, randomly shaped, hollow, and contain integrated pre-vascularization still faces multiple challenges. This study aimed to test the feasibility of our 3D printing scheme for the manufacturing of micro-fluid channel networks complex three-dimensional tissue structures. The reverse engineering software was used to design the CAD model and polyvinyl alcohol (PVA) was used as the sacrificial material to print the sacrificial stent use the bioprinter nozzle 1. Hydrogel composite H9c2 and human umbilical vein endothelial cells (HUVECs) were mixed with sodium alginate, agarose solution and platelet-rich plasma (PRP) as cellular bioink, which was extruded through nozzle 2 to deposit the internal pores of the sacrificial scaffold. The scaffold dissolved, change to a flexible, hollow and micro-fluid channel networks complex structure. The 3D-bioprinting technology can construct a micro-fluid channel networks valentine heart with a self-defined height and hollow in suitable mechanical properties. The cells proliferate and maintain their biological properties within the printed constructs. This study demonstrates that valentine heart-like constructs can be fabricated with 3D bioprinting using sacrificial and hydrogel materials.

Correlation between the efficacy of stem cell therapy for osteonecrosis of the femoral head and cell viability.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a common disease that greatly affects the quality of life of patients. Repair of the necrotic area is key to successful treatment. Currently, the combination of stem cell transplantation and decompression is used clinically to promote the repair of necrotic areas based on the characteristics of stem cells. However, a considerable number of patients do not achieve a satisfactory outcome in terms of repair of the femoral head necrotic area, and it is very important to determine the reasons for the poor curative effect. The aim of this study was to investigate the correlation between stem cell viability and the repair efficacy of stem cell therapy combined with core decompression for early-stage ONFH. METHODS: A total of 30 patients with idiopathic ONFH underwent core decompression combined with autologous stem cell transplantation. The Harris hip score (HHS) and difference in necrosis area before and after surgery were measured. The mean repair ratio was set as the threshold to divide the patients into group A (ratio above the mean) and group B (ratio below the mean). The ultrastructure, proliferative capacity, and multidirectional differentiation ability were compared between the groups. RESULTS: At 9 months after surgery, the HHS and magnetic resonance imaging (MRI) findings improved by varying degrees. Based on the mean repair ratio of (62.2 ± 27.0)%, the threshold for dividing the patients into groups A and B was set to 62.2%. Better repair (group A) was associated with more rapid proliferation and a healthier ultrastructure. The cells in group A showed stronger specific staining signifying osteogenic and chondrogenic differentiation; alkaline phosphatase (ALP) activity, an indicator of osteogenic differentiation, was higher in group A than in group B (OD, 2.39 ± 0.44 and 1.85 ± 0.52; p <  0.05). CONCLUSIONS: The quality of implanted stem cells is closely related to treatment efficacy and determines whether the defective self-repair in the necrotic area can be corrected to enhance repair and thus achieve the desired therapeutic outcome. TRIAL REGISTRATION: The trial registration number: ChiCTR-ORC-17011698 (retrospectively registered at 2017-06-19).

The Relationship Between Lumbar Lateral Listhesis and Radiculopathy in Adult Scoliosis.

STUDY DESIGN: Retrospective review and prospective validation study. OBJECTIVE: To develop a classification system of lumbar lateral listhesis that suggests different likelihoods of having radiculopathy in adult scoliosis. SUMMARY OF BACKGROUND DATA: The association of lumbar lateral listhesis with radiculopathy remains uncertain. METHODS: A retrospective cohort of patients with adult scoliosis enrolled from 2011 to 2015 was studied to develop a classification system of lateral listhesis that can stratify the likelihood of having radiculopathy. Four radiological aspects of lateral listhesis, including Nash and Moe vertebral rotation, L4-L5 lateral listhesis, the number of consecutive listheses, and the presence of a contralateral lateral listhesis at the thoracolumbar junction above a caudal listhesis, were evaluated on radiographs. Their associations with the presence of radicular leg pain were evaluated using multivariable logistic regression. The classification system of lateral listhesis was thus developed using the most influential radiological factors and then validated in a prospective cohort from 2016 to 2017. RESULTS: The retrospective cohort included 189 patients. Vertebral rotation is more than or equal to grade 2 (odds ratio [OR] = 9.45, 95% confidence interval [CI]: 4.07-25.14) and L4-5 listhesis (OR = 4.56, 95%CI: 1.85-12.35) were the two most influential listhesis factors associated with radiculopathy. The classification system of lateral listhesis was thus built based on the combinations of their respective presence: Type 0, 1, 2, 3 were defined as not having listhesis at all, none of the two factors present, one of the two presents, and both present, respectively. This classification significantly stratified the probability of radiculopathy, in both the retrospective cohort (0%, 6.4%, 33.8%, and 68.4% in Type 0, 1, 2, and 3, respectively; P < 0.001) and a prospective cohort of 105 patients (0%, 16.7%, 46.9%, and 72.7%; P < 0.001). CONCLUSION: Lumbar lateral listhesis is associated with the presence of radiculopathy in adult scoliosis. Types 2 and 3 lateral listhesis on radiographs may alert surgeons treating patients with spinal deformity. LEVEL OF EVIDENCE: 2.

Correction to: Bone Marrow Derived Pluripotent Cells are Pericytes which Contribute to Vascularization.

Please note the following errors in the original version.

Postoperative Radiographic Evaluation Following Adult Spine Deformity Correction: The Impact on Subsequent Management and Associated Risk of Radiation Exposure.

BACKGROUND: During the follow-up visits after Adult Spine Deformity (ASD) surgery, obtaining surveillance radiographs is a usual practice, and this study tried to identify evidence to support or refute such practice. METHODS: This is a retrospective, diagnostic case series (Level IV) of 49 patients. We identified the abnormal radiographic findings and their association with need for revision surgery. We determined the odds of obtaining an abnormal radiographs that lead to revision surgery at each of the given time intervals of follow-up. We also estimated the risk versus benefit of obtaining radiographs at each of the given time intervals of follow-up. RESULTS: We identified a total of 11 individual types of abnormal postoperative radiographic findings. Of them, the two radiographic findings that always needed revision surgery because of the associated clinical presentation were pedicle screw pullout and bilateral rod fracture. One abnormal radiographic finding that was never associated with revision surgery was the halo around a pedicle screw. In each of the given postoperative time intervals of follow-up at which the routine radiographs were obtained, we noted that the odds of noticing abnormal radiographic finding that lead to revision surgery was always >1. We found that the cumulative hazard rate for exposure to radiation was significantly higher during the initial follow-up visits when compared to subsequent follow-up visits. CONCLUSION: This study finds evidence to support the practice of routine postoperative radiographic evaluation of patients who come for follow-up after ASD surgery.

Progression of idiopathic thoracic or thoracolumbar scoliosis and pelvic obliquity in adolescent patients with and without limb length discrepancy.

ΒACKGROUND: Both limb length inequality and scoliosis are associated with pelvic obliquity. METHODS: This is an observational study of adolescents with growth potential presenting for evaluation of thoracic or thoracolumbar idiopathic scoliosis at an outpatient pediatric orthopedic clinic. Patients were evaluated for limb length discrepancy (LLD) (using bilateral femoral head height difference), pelvic obliquity (using bilateral iliac crest height difference and sacral takeoff angle), and scoliotic curve (using Cobb angle and rotation) on full spine standing radiographs. The same radiographic parameters were measured at a follow-up visit at least 2 years later. RESULTS: Seventy-three consecutive patients with a mean (SD) age of 13.3 (0.2) years at initial examination were included in the study. Scoliosis (major curve Cobb angle ≥ 10°) was confirmed in all 73 patients, pelvic obliquity (iliac crest height difference > 1 cm or sacral takeoff angle > 5°) appeared in 23 (31.5%) patients with scoliosis, and LLD (> 1 cm femoral head height difference) was identified in 6 (8.2%) patients with scoliosis and pelvic obliquity. At a subsequent visit, a mean of 2.8 (range 2-5.8) years later, no significant change (p > 0.05) in limb length inequality was observed but a statistically significant increase (p < 0.05) in scoliotic and pelvic deformity parameters was found. CONCLUSIONS: In adolescent patient population with thoracic or thoracolumbar scoliosis, the anisomelia remains stable with growth but both the scoliotic deformity and pelvic obliquity progress. TRIAL REGISTRATION: MGH no 2012-P-000774/1.

Robotic Patterning a Superhydrophobic Surface for Collective Cell Migration Screening.

Collective cell migration, in which cells migrate as a group, is fundamental in many biological and pathological processes. There is increasing interest in studying the collective cell migration in high throughput. Cell scratching, insertion blocker, and gel-dissolving techniques are some methodologies used previously. However, these methods have the drawbacks of cell damage, substrate surface alteration, limitation in medium exchange, and solvent interference. The superhydrophobic surface, on which the water contact angle is greater than 150 degrees, has been recently utilized to generate patterned arrays. Independent cell culture areas can be generated on a substrate that functions the same as a conventional multiple well plate. However, so far there has been no report on superhydrophobic patterning for the study of cell migration. In this study, we report on the successful development of a robotically patterned superhydrophobic array for studying collective cell migration in high throughput. The array was developed on a rectangular single-well cell culture plate consisting of hydrophilic flat microwells separated by the superhydrophobic surface. The manufacturing process is robotic and includes patterning discrete protective masks to the substrate using 3D printing, robotic spray coating of silica nanoparticles, robotic mask removal, robotic mini silicone blocker patterning, automatic cell seeding, and liquid handling. Compared with a standard 96-well plate, our system increases the throughput by 2.25-fold and generates a cell-free area in each well non-destructively. Our system also demonstrates higher efficiency than conventional way of liquid handling using microwell plates, and shorter processing time than manual operating in migration assays. The superhydrophobic surface had no negative impact on cell viability. Using our system, we studied the collective migration of human umbilical vein endothelial cells and cancer cells using assays of endpoint quantification, dynamic cell tracking, and migration quantification following varied drug treatments. This system provides a versatile platform to study collective cell migration in high throughput for a broad range of applications.

In vitro evaluation of decellularized ECM-derived surgical scaffold biomaterials.

Decellularized extracellular matrix (ECM) biomaterials are increasingly used in regenerative medicine for abdominal tissue repair. Emerging ECM biomaterials with greater compliance target surgical procedures like breast and craniofacial reconstruction to enhance aesthetic outcome. Clinical studies report improved outcomes with newly designed ECM scaffolds, but their comparative biological characteristics have received less attention. In this study, we investigated scaffolds derived from dermis (AlloDerm Regenerative Tissue Matrix), small intestinal submucosa (Surgisis 4-layer Tissue Graft and OASIS Wound Matrix), and mesothelium (Meso BioMatrix Surgical Mesh and Veritas Collagen Matrix) and evaluated biological properties that modulate cellular responses and recruitment. An assay panel was utilized to assess the ECM scaffold effects upon cells. Results of the material-conditioned media study demonstrated Meso BioMatrix and OASIS best supported cell proliferation. Meso BioMatrix promoted the greatest migration and chemotaxis signaling, followed by Veritas and OASIS; OASIS had superior suppression of cell apoptosis. The direct adhesion assay indicated that AlloDerm, Meso BioMatrix, Surgisis, and Veritas had sidedness that affected cell-material interactions. In the chick chorioallantoic membrane assay, Meso BioMatrix and OASIS best supported cell infiltration. Among tested materials, Meso BioMatrix and OASIS demonstrated characteristics that facilitate scaffold incorporation, making them promising choices for many clinical applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 585-593, 2017.

Regulators of Stem Cells Proliferation in Tissue Regeneration.

This review summarizes recent breakthroughs in studies regarding proliferation of adult stem cells which complement and extend our knowledge to various aspects of cell biology and signal pathways. In recent years, many interesting results and discoveries were achieved regarding the proliferative properties of stem cells. In vitro expansion of stem cells may benefit from high proliferation rates, which can produce a large amount of cells to regenerate tissue defects. Meanwhile, optimizing the culture conditions for stem cell propagation is helpful in maintaining the pluripotency and differentiation potential of stem cells, which are critical for tissue engineering and regenerative medicine. Additionally, understanding the proliferation of stem cells may help us to uncover new mechanisms of drug resistance, since stem cells are believed to play an important role in drug resistance. In this review, we focus on signaling pathways regulating the proliferation of various stem cells isolated from adult tissues. We also emphasize the significance of stem cells proliferation in cell research, as well as rapid propagation of adult stem cells for regenerative medicine.

Fishtail deformity--a delayed complication of distal humeral fractures in children.

BACKGROUND: Concavity in the central portion of the distal humerus is referred to as fishtail deformity. This entity is a rare complication of distal humeral fractures in children. OBJECTIVE: The purpose of this study is to describe imaging features of post-traumatic fishtail deformity and discuss the pathophysiology. MATERIALS AND METHODS: We conducted a retrospective analysis of seven cases of fishtail deformity after distal humeral fractures. RESULTS: Seven children ages 7-14 years (five boys, two girls) presented with elbow pain and history of distal humeral fracture. Four of the seven children had limited range of motion. Five children had prior grade 3 supracondylar fracture treated with closed reduction and percutaneous pinning. One child had a medial condylar fracture and another had a lateral condylar fracture; both had been treated with conservative casting. All children had radiographs, five had CT and three had MRI. All children had a concave central defect in the distal humerus. Other imaging features included joint space narrowing with osteophytes and subchondral cystic changes in four children, synovitis in one, hypertrophy or subluxation of the radial head in three and proximal migration of the ulna in two. CONCLUSION: Fishtail deformity of the distal humerus is a rare complication of distal humeral fractures in children. This entity is infrequently reported in the radiology literature. Awareness of the classic imaging features can result in earlier diagnosis and appropriate treatment.