Robotic-Assisted Total Hip Arthroplasty in Patients Who Have Developmental Hip Dysplasia

Introduction: Total hip arthroplasty (THA) in the setting of developmental dysplasia of the hip (DDH) presents more inherent complexities than routine primary THA for osteoarthritis. These include acetabular bone deficiency, limb length discrepancy (LLD), and abnormal femoral anteversion. Three-dimensional planning and robot-assisted (RA) bone preparation may simplify these complex procedures and make them more reproducible. The purpose of this study was to evaluate radiographic and clinical outcomes in a cohort of patients who had DDH and underwent an RA THA. Materials and Methods: We retrospectively analyzed 26 DDH patients who underwent RA THA by a single surgeon between 2013 and 2019. Their mean age was 54 years (range, 29 to 72 years) and mean follow up was approximately two years. Medical records were reviewed for demographics, clinical scores, Crowe classifications, and complications. There were thirteen Crowe I and seven Crowe II DDH hips, who were routinely managed with primary cementless implants. Two patients who had Crowe III and four patients who had Crowe IV DDH were also identified. All hips were reconstructed with cementless hemispherical acetabular components with or without the use of screws, but no acetabular augments or bulk allografts. Implants allowing control of femoral anteversion were selected in 23.1% of cases, including all six cases with Crowe III or IV dysplasia, and the need for these implants was uniformly identified using preoperative information about femoral version provided by the three-dimensional planning software. No patient was managed with a shortening femoral osteotomy. Postoperative radiographs were examined for LLD, center of rotation (COR), cup position (inclination and anteversion), and component osseous-integration. Results: Mean radiographic LLD was 1.7mm (range, -9 to +14) in patients who had Crowe I DDH, and there was no clinical LLDs greater than 5mm observed. Although patients who had Crowe II and greater DDH had a mean radiographic LLD of -11.6mm (range, -26 to +2.2), again no clinical LLD greater than 5mm was observed other than one patient who had bilateral Crowe II DDH in whom 10mm of clinical lengthening was accepted at the index arthroplasty with the plan to match lengths when her contralateral THA was performed. There were no cases of dislocation or acetabular fixation failure. One patient who had a femoral deformity and an intra-osseous blade plate from a prior femoral osteotomy suffered a failure of femoral osseous-integration, resulting in revision. A 32-point increase in mean modified Harris Hip Score (mHHS) was found (p=0.002), from 48 points preoperatively to 80 points postoperatively. Discussion: RA THA provides an excellent option for the arthroplasty surgeon to both preoperatively localize and characterize the acetabular deficiency, while providing a targeted, optimal, and secure placement of the components intraoperatively. Our results suggest favorable outcomes when compared to previous research on manual THA in DDH. Further studies, including comparative analyses, could discern possible advantages over traditional THA without robotic assistance in DDH. Conclusion: Total hip arthroplasty (THA) in the setting of developmental dysplasia presents more inherent complexities than routine primary THA. Robotic-assisted THA may simplify these complex procedures.

Influence of Topography on 3D printed Titanium Foot and Ankle Implants

Category: Basic Sciences/Biologics; Ankle; Trauma Introduction/Purpose Foot and ankle etiologies such as traumatic fractures, Charcot Arthropathy, nonunion after high risk arthrodesis and infectious debridement can result in critical sized bone defect (CSD). CSD is defined as bone loss greater than 1-2 cm in length or greater than 50% loss in circumference of bone. CSD remain a significant challenge in Orthopaedics. Custom 3D printed porous Titanium implants are currently being implemented when allograft is not an option. However, in a subset of cases, Titanium implants need to be removed due to infection or poor osseous integration where surrounding bone does not grow onto or through the scaffold. There is no one clear reason for poor osseous integration. This study explores effects of 3D printed topography on mechanical and biological properties. Methods: Titanium dog bones and discs were printed via laser powder bed fusion. Roughness groups were polished, blasted, as built, sprouts and rough sprouts. Roughness was measured with line measurement using a confocal microscope. To assess mechanical properties, tensile testing of samples from each roughness group produced stress strain curves. MC3T3 preosteoblast were seeded on discs. Samples were analyzed at 0, 2, and 4 weeks. A cell viability assay and confocal florescent microscopy assessed cell growth. Alkaline Phosphatase (ALP) assay and Quantitative Polymerase Chain Reaction (qPCR) examined cell differentiation. Extracellular matrix (ECM) was stained for collagen and calcium. Scanning Electron Microcopy (SEM) was done on sputter coated discs. Results: Rz, maximum peak to valley distance of the sample profile, for the polished, blasted, as built, sprouts and rough sprouts were 2.6, 22.6, 33.0, 41.4 and 65.1 µm respectively. The addition of printed roughness in the sprouts and rough sprouts group significantly diminished ductility resulting in early strain to failure during tensile testing. Cells adhered and proliferated on discs regardless of roughness group. There was no statically difference in ALP activity, but qPCR showed that rough groups (sprouts and rough sprouts) had diminished Osteocalcin gene expression at week 2 and 4. The ECM observed with SEM in the rough groups was more resistant to repeated washes and was more extensive compared to the less rough groups. Conclusion: The addition of 3D printed artificial roughness leads to inferior mechanical properties and confers no clear benefit regarding cellular proliferation. Printed topography increases the initiation of fractures resulting in diminished tensile strength and ductility. Concurrently, the resolution of LBF is not fine enough at this time to create surface features that enhance cell behavior. Therefore, data in this study suggest that artificially printing roughness is not an effective strategy to enhance osseous integration into Titanium implants for critical sized defects.

One-Year MRI Outcomes of Osteochondral Allograft Transplantation of the Knee for Large Chondral Defects: Comparison of Elliptical, Stacked, and Single Allografts

Objectives: Osteochondral allograft transplantation (OCA) is a proven cartilage restoration procedure for patients with large chondral defects. However, elongated condylar lesions pose a challenge for dowel OCA in restoring articular surface congruity. Recently, instrumentation to harvest a single, elliptical allograft has been developed for treating ovoid lesions without requiring an adjacent-plug (stacked or snowman) technique. The purpose of this study was to compare 1-year MRI outcomes of patients treated with elliptical, stacked, or single OCA using the Osteochondral Allograft MRI Scoring System (OCAMRISS) and percent osseous integration. Methods: A retrospective review on patients treated from 2000 to 2018 with OCA for condylar defects of the knee was conducted. Inclusion criteria included those followed prospectively with a MRI at ˜1 year after surgery. OCAMRISS and osseous integration scores (0-25%; 26-50%; 51-75%; 76%-100%) were graded by a musculoskeletal radiologist blinded to the outcomes. Comparisons of demographics and MRI scores were performed with the ANOVA. Results: A total of 57 knees (mean age, 35.8 years; 70% male) met the inclusion criteria and were treated with either elliptical (n=19), stacked (n=19), or single (n=19) OCA. Mean time to post-operative MRI was 10.7, 11.1, and 12.4 months, respectively (p=0.17). There were no significant differences in demographics or number of prior ipsilateral knee surgeries among groups. Defect characteristics were significantly different between groups, where single plugs treated a higher percentage of LFC defects (58%) compared to elliptical and stacked (26%, each) (p=0.02). Total chondral defect area was greatest in the stacked group (5.4 ± 1.3) compared to elliptical (4.6 ± 1.2) and single (4.6 ± 1.4) (p=0.12). Bone, cartilage, ancillary, and total OCAMRISS scores were not significantly different between groups. A trend towards a higher percentage of osseous integration (single>stacked>elliptical) was noted which correlated with less transplanted allograft bone, however, these differences were not significant (p=0.15). Conclusion: One-year OCAMRISS and osseous integration scores did not differ among patients treated with elliptical, stacked, or single OCA. Further investigation is needed to explore potential differences in clinical outcomes and long-term osseous integration between elliptical and stacked OCA for the treatment of elongated condylar defects of the knee. [Table: see text]