The Anterior Modified San Diego Acetabuloplasty Does Not Increase Superior-Anterior Coverage in Patient-Specific 3D-Printed Models.

BACKGROUND: Patients with developmental dysplasia of the hip may require pelvic osteotomies to improve acetabular coverage. The purpose of this study was to compare the changes in acetabular version, tilt, and regional coverage angles following the San Diego acetabuloplasty (SDA), the modified San Diego acetabuloplasty (mSDA), and the Pemberton acetabuloplasty (PA). METHODS: Fourteen patients with developmental dysplasia of the hip and computed tomography (CT) imaging were identified. From CT images, 2 identical pelvises were 3-dimensional-printed for each patient. Bone was printed with rigid material, and cartilage with flexible material. For each model pair, the SDA was performed on one and the PA was performed on the other. CT scans were obtained before and after acetabuloplasties. Next, the bone graft in the SDA model was moved anteriorly, representing the mSDA, and the model was rescanned. Acetabular version, tilt, and coverage angles (posterior, superior-posterior, superior, superior-anterior, and anterior) were calculated. Preoperative to postoperative differences were compared (repeated measures analysis of variance or Wilcoxon signed rank test). The significance was set to P <0.05. RESULTS: The mean age at CT was 5.8±1.2 years (range: 3.9 to 7.5 y). All 3 procedures (SDA, mSDA, and PA) significantly increased acetabular tilt; P <0.045), with a similar change observed for all 3 ( P =0.868). PA was the only procedure to significantly decrease relative acetabular version (6.5±6.5 degrees, preoperative: 12.9±5.3 degrees; P =0.004). Both the SDA and mSDA procedures significantly increased coverage in the superior-posterior octant (SDA: 92.6±9.3 degrees, mSDA: 92.3±9.8 degrees, preoperative: 81.9±9.5 degrees; P <0.02), with a similar percent change among the 2 ( P =1.0). All 3 procedures significantly increased superior coverage ( P <0.04); the increase was similar among the 3 ( P =0.205). The PA was the only procedure to produce a significant increase in coverage in the superior-anterior octant (91.0±16.7 degrees, preoperative: 74.0±12.1 degrees; P =0.005) or the anterior octant (50.7±11.7 degrees, preoperative: 45.8±8.9 degrees; P =0.012). CONCLUSIONS: The SDA and mSDA procedures produced similar postoperative changes, primarily in the superior and superior-posterior acetabular octants. Placing the graft more anteriorly did not increase anterior coverage in the mSDA, and only the PA increased coverage in the superior and superior-anterior acetabular octants.

Successful treatment of highly recurrent facial baroparesis in a frequent high-altitude traveler: a case report.

BACKGROUND: Facial baroparesis is a palsy of the seventh cranial nerve resulting from increased pressure compressing the nerve along its course through the middle ear cavity. It is a rare condition, most commonly reported in barotraumatic environments, in particular scuba diving and high-altitude air travel. We report here an unusual case of highly frequent baroparesis, workup, and successful treatment. CASE PRESENTATION: A 57-year-old Caucasian male frequent commercial airline traveler presented with a 4-year history of recurrent episodes of right-sided facial paralysis and otalgia, increasing in both frequency and severity. Incidents occurred almost exclusively during rapid altitude changes in aircraft, mostly ascent, but also during rapid altitude change in an automobile. Self-treatment included nasal and oral decongestants, nasal corticosteroids, and warm packs. Temporal bone computed tomography (CT) scan revealed possible right-sided dehiscence of the tympanic bone segment; audiogram and magnetic resonance imaging of the internal auditory canals were unremarkable. After a diagnosis of facial nerve baroparesis was made, the patient underwent myringotomy with insertion of a pressure equalization tube (PET) into the right tympanic membrane. Despite re-exposure to altitude change multiple times weekly post-treatment, the patient reported being symptom-free for more than 6 months following intervention. CONCLUSIONS: Prompt PET insertion may represent the preferred treatment for individuals who suffer recurrent episodes of facial baroparesis. Education regarding this rare condition may prevent unnecessary testing and treatment of affected patients. Future studies should explore the pathophysiology and risk factors, compare therapeutic options, and provide follow-up data to optimize the management of affected patients.

Comparison of 3 Pediatric Pelvic Osteotomies for Acetabular Dysplasia Using Patient-specific 3D-printed Models.

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.

Strains in trussed spine interbody fusion implants are modulated by load and design.

Titanium cages with 3-D printed trussed open-space architectures may provide an opportunity to deliver targeted mechanical behavior in spine interbody fusion devices. The ability to control mechanical strain, at levels known to stimulate an osteogenic response, to the fusion site could lead to development of optimized therapeutic implants that improve clinical outcomes. In this study, cages of varying design (1.00 mm or 0.75 mm diameter struts) were mechanically characterized and compared for multiple compressive load magnitudes in order to determine what impact certain design variables had on localized strain. Each cage was instrumented with small fiducial sphere markers (88 total) at each strut vertex of the truss structure, which comprised of 260 individual struts. Cages were subjected to a 50 N control, 1000 N, or 2000 N compressive load between contoured loading platens in a simulated vertebral fusion condition, during which the cages were imaged using high-resolution micro-CT. The cage was analyzed as a mechanical truss structure, with each strut defined as the connection of two vertex fiducials. The deformation and strain of each strut was determined from 50 N control to 1000 N or 2000 N load by tracking the change in distance between each fiducial marker. As in a truss system, the number of struts in tension (positive strain) and compression (negative strain) were roughly equal, with increased loads resulting in a widened distribution (SD) compared with that at 50 N tare load indicating increased strain magnitudes. Strain distribution increased from 1000 N (+156 ± 415 µÎµ) to 2000 N (+180 ± 605 µÎµ) in 1.00 mm cages, which was similar to 0.75 mm cages (+132 ± 622 µÎµ) at 1000 N load. Strain amplitudes increased 42%, from 346µÎµ at 1000 N to 492µÎµ at 2000 N, for 1.00 mm cages. At 1000 N, strain amplitude in 0.75 mm cages (481µÎµ) was higher by 39% than that in 1.00 mm cages. These amplitudes corresponded to the mechanobiological range of bone homeostasis+formation, with 63 ± 2% (p < .05 vs other groups), 72 ± 3%, and 73 ± 1% of struts within that range for 1.00 mm at 1000 N, 1.00 mm at 2000 N, and 0.75 mm at 1000 N, respectively. The effective compressive modulus for both cage designs was also dependent on strut diameter, with modulus decreasing from 12.1 ± 2.3 GPa (1.25 mm) to 9.2 ± 7.5 GPa (1.00 mm) and 3.8 ± 0.6 GPa (0.75 mm). This study extended past micro-scale mechanical characterization of trussed cages to compare the effects of design on cage mechanical behavior at moderate (1000 N) and strenuous (2000 N) load levels. The findings suggest that future cage designs may be modulated to target desired mechanical strain regimes at physiological loads.

Pulsed lavage cleansing of osteochondral grafts depends on lavage duration, flow intensity, and graft storage condition.

INTRODUCTION: Osteochondral 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. METHODS: OCs 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). RESULTS: Gross 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%. CONCLUSIONS: The 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.

Ex vivo loading of trussed implants for spine fusion induces heterogeneous strains consistent with homeostatic bone mechanobiology.

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 50N control (4±114µÎµ, mean±SD) to 1000N (-23±273µÎµ) and 2000N (-48±414µÎµ), and between 1000N and 2000N. With similar loading of multiple cages, the strain distribution at 2000N (23±389µÎµ) increased from 50N control. With repeated loading by contoured plastic platens, induced strains at 2000N had a distribution similar to that induced by vertebral platens (84±426µÎµ). In all studies, cages exhibited increases in strut strain amplitude when loaded from 50N to 1000N or 2000N. Correspondingly, at 2000N, 59-64% of struts exhibited strain amplitudes consistent with mechanobiologically-regulated bone homeostasis. At 2000N, vertically-oriented struts exhibited deformation of -2.87±2.04µm and strain of -199±133µÎµ, 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.

Flexural properties of native and tissue-engineered human septal cartilage.

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.