PurposeSlipped capital femoral epiphysis (SCFE) can result in a complex three-dimensional (3D) deformity of the proximal femur. A three-plane proximal femoral osteotomy (TPFO) has been described to improve hip mechanics. The purpose of this study was to evaluate the benefits of using 3D print technology to aid in surgical planning.Patients and MethodsFifteen children treated with TPFO for symptomatic proximal femoral deformity due to SCFE were included in this study. Ten patients were treated by a single surgeon with (model group, n = 5) or without (no-model group, n = 5) a 3D model for pre-operative planning, and compared with patients treated by two senior partners without the use of a model (senior group, n = 5) to evaluate for a learning curve. Peri-operative data including patient body mass index (BMI), surgical time and fluoroscopy time were recorded.ResultsChildren in all three groups had similar BMIs at the time of the TPFO. Post-operative radiographic parameters were equally improved in all three groups. On average, surgical time decreased by 45 minutes and 38 minutes, and fluoroscopy time decreased by 50% and 25%, in the model group compared with the no-model and senior groups, respectively.ConclusionsPatient-specific 3D models aid in surgical planning for complex 3D orthopaedic deformities by enabling practice of osteotomies. Results suggest that 3D models may decrease surgical time and fluoroscopy time while allowing for similar deformity correction. These models may be especially useful to overcome steep learning curves for complex procedures or in trainee education through mock surgical procedures.

Background: Children with developmental dysplasia of the hip may require a pelvic osteotomy to treat acetabular dysplasia. Three osteotomies are commonly performed in these patients (Pemberton, Dega, and San Diego), though comparative studies of each are limited. The purpose of this study was to compare changes in acetabular morphology (acetabular version, volume, and octant coverage angles) created by these 3 osteotomies using matched patient-specific 3D-printed pelvic models. Methods: Fourteen patients with developmental dysplasia of the hip and preoperative computed tomography (CT) imaging were retrospectively included. For each patient CT, bone and cartilage tissues were independently segmented, and 3 identical pelvises were 3D-printed using a dual material printer. Bone was printed with rigid material and cartilage with flexible material to simulate the flexibility of the triradiate cartilage and pubic symphysis. Pemberton, Dega, and San Diego acetabular osteotomies were performed on the triplicate set of 3D prints. Acetabular version, volume, and octant coverage angles (posterior, superior-posterior, superior, superior-anterior, and anterior) were determined before and after each mock surgery by morphologic assessment using preoperative and postoperative CT images. Results: San Diego osteotomy yielded a small increase (+3.34±1.71 degrees) in version, compared with decreases with Pemberton (−5.47±1.54 degrees) and Dega (−8.57±1.21 degrees, P<0.05). Acetabular volume decreased similarly for Pemberton (−13.36%±2.88%), Dega (−19.21%±2.73%), and San Diego (−19.29%±2.44%; P=0.215) osteotomies. San Diego osteotomy tended to have a larger postoperative increase in the posterior regions, and the Dega and Pemberton osteotomies tended to have larger postoperative increases in the anterior coverage regions. Conclusions: Quantifiable differences were identified in acetabular octant coverage angles and version between the 3 pelvic osteotomies. San Diego osteotomy increased acetabular coverage posteriorly resulting in acetabular anteversion, whereas Pemberton and Dega had greater superior-anterior coverage resulting in relative acetabular retroversion. This study is the first known to utilize 3D-printed models for comparison of surgical approaches in pediatric pelvic osteotomies.

IntroductionOsteochondral allograft (OCA) transplantation is generally effective for treating large cartilage lesions. Cleansing OCA subchondral bone to remove donor marrow elements is typically performed with pulsed lavage. However, the effects of clinical and experimental parameters on OCA marrow removal by pulsed lavage are unknown. The aim of the current study was to determine the effects on marrow cleansing in human osteochondral cores (OCs) of (1) lavage duration, (2) lavage flow intensity, and (3) OC sample type and storage condition.MethodsOCs were harvested from human femoral condyles and prepared to a clinical geometry (cylinder, diameter = 20 mm). The OCs were from discarded remnants of Allograft tissues (OCA) or osteoarthritis patients undergoing Total Knee Replacement (OCT). The experimental groups subjected to standard flow lavage for 45 seconds (430 mL of fluid) and 120 seconds (1,150 mL) were (1) OCT/FROZEN (stored at -80°C), (2) OCT/FRESH (stored at 4°C), and (3) OCA/FRESH. The OCA/FRESH group was subsequently lavaged at high flow for 45 seconds (660 mL) and 120 seconds (1,750 mL). Marrow cleansing was assessed grossly and by micro-computed tomography (μCT).ResultsGross and μCT images indicated that marrow cleansing progressed from the OC base toward the cartilage. Empty marrow volume fraction (EMa.V/Ma.V) increased between 0, 45, and 120 seconds of standard flow lavage, and varied between groups, being higher after FROZEN storage (86–92% after 45–120 seconds) than FRESH storage of either OCT or OCA samples (36% and 55% after 45 and 120 seconds, respectively). With a subsequent 120 seconds of high flow lavage, EMa.V/Ma.V of OCA/FRESH samples increased from 61% to 78%.ConclusionsThe spatial and temporal pattern of marrow space clearance was consistent with gradual fluid-induced extrusion of marrow components. Pulsed lavage of OCAs with consistent time and flow intensity will help standardize marrow cleansing and may improve clinical outcomes.

A truss structure was recently introduced as an interbody fusion cage. As a truss system, some of the connected elements may be in a state of compression and others in tension. This study aimed to quantify both the mean and variance of strut strains in such an implant when loaded in a simulated fusion condition with vertebral body or contoured plastic loading platens ex vivo. Cages were each instrumented with 78 fiducial spheres, loaded between platens (vertebral body or contoured plastic), imaged using high resolution micro-CT, and analyzed for deformation and strain of each of the 221 struts. With repeated loading of a cage by vertebral platens, the distribution (variance, indicated by SD) of strut strains widened from 50 N control (4 ± 114 με, mean ± SD) to 1000 N (−23 ± 273 με) and 2000 N (−48 ± 414 με), and between 1000 N and 2000 N. With similar loading of multiple cages, the strain distribution at 2000 N (23 ± 389 με) increased from 50 N control. With repeated loading by contoured plastic platens, induced strains at 2000 N had a distribution similar to that induced by vertebral platens (84 ± 426 με). In all studies, cages exhibited increases in strut strain amplitude when loaded from 50 N to 1000 N or 2000 N. Correspondingly, at 2000 N, 59–64% of struts exhibited strain amplitudes consistent with mechanobiologically-regulated bone homeostasis. At 2000 N, vertically-oriented struts exhibited deformation of −2.87 ± 2.04 μm and strain of −199 ± 133 με, indicating overall cage compression. Thus, using an ex vivo 3-D experimental biomechanical analysis method, a truss implant can have strains induced by physiological loading that are heterogeneous and of amplitudes consistent with mechanobiological bone homeostasis.

Objective To determine and compare the bending moduli of native and engineered human septal cartilage. Study Design Prospective, basic science. Setting Research laboratory. Subjects and Methods Neocartilage constructs were fabricated from expanded human septal chondrocytes cultured in differentiation medium for 10 weeks. Constructs (n=10) and native septal cartilage (n=5) were tested in a 3-point bending apparatus, and the bending moduli were calculated using Euler–Bernoulli beam theory. Results All samples were tested successfully and returned to their initial shape after unloading. The bending modulus of engineered constructs (0.32 ± 0.25 MPa, mean ± SD) was 16% of that of native septal cartilage (1.97 ± 1.25 MPa). Conclusion Human septal constructs, fabricated from cultured human septal chondrocytes, are more compliant in bending than native human septal tissue. The bending modulus of engineered septal cartilage can be measured, and this modulus provides a useful measure of construct rigidity while undergoing maturation relative to native tissue.