The computational modelling and 3D technology are finding more and more applications in the medical field. Orthopedic surgery is one of the specialties that can benefit the most from this solution. Three case reports drawn from the experience of the authors’ Orthopedic Clinic are illustraded to highlight the benefits of applying this technology.

Drawing on the extensive experience gained within the authors’ Operating Unit, three cases regarding different body segments have been selected to prove the importance of 3D technology in preoperative planning and during the surgery. A sternal transplant by allograft from a cryopreserved cadaver, the realization of a custom made implant of the glenoid component in a two-stage revision of a reverse shoulder arthroplasty, and a case of revision on a hip prosthesis with acetabular bone loss (Paprosky 3B) treated with custom system. In all cases the surgery was planned using 3D processing software and models of the affected bone segments, printed by 3D printer, and based on CT scans of the patients. The surgical implant was managed with dedicated instruments.

The use of 3D technology can improve the results of orthopedic surgery in many ways: by optimizing the outcomes of the operation as it allows a preliminary study of the bone loss and an evalutation of feasibility of the surgery, it improves the precision of the positioning of the implant, especially in the context of severe deformity and bone loss, and it reduces the operating time; by improving surgeon training; by increasing patient involvement in decision making and informed consent.

3D technology, by offering targeted and customized solutions, is a valid tool to obtain the tailored care that every patient needs and deserves, also providing the surgeon with an important help in cases of great complexity.

In a clinical setting, there is a need for simple gait kinematic measurements to facilitate objective unobtrusive patient monitoring. The objective of this study is to determine if a learned classification model's output can be used to monitor a person's recovery status post-TKA.

The gait kinematics of 20 asymptomatic and 17 people with TKA were measured using a full-body Xsens model¹. The experimental group was measured at 6 weeks, 3, 6, and 12 months post-surgery. Joint angles of the ankle, knee, hip, and spine per stride (10 strides) were extracted from the Xsens software (MVN Awinda studio 4.4)¹.

Statistical features for each subject at each evaluation moment were derived from the kinematic time-series data. We normalised the features using standard scaling². We trained a logistic regression (LR) model using L1-regularisation on the 6 weeks post-surgery data2–4.

After training, we applied the trained LR- model to the normalised features computed for the subsequent timepoints. The model returns a score between 0 (100% confident the person is an asymptomatic control) and 1 (100% confident this person is a patient). The decision boundary is set at 0.5.

The classification accuracy of our LR-model was 94.58%. Our population's probability of belonging to the patient class decreases over time. At 12 months post-TKA, 38% of our patients were classified as asymptomatic.

Introduction and Objective

Several factors contribute to the duration of the hospital stay in patients that undergo to total hip arthroplasty (THA), either subjective or perioperative. However, no definite evidence has been provided on the role of any of these factors on the hospitalization length. The aim of this retrospective investigation is to evaluate the correlation between several preoperative and perioperative factors and the length of hospital stay (LOS) in patients that underwent elective total hip arthroplasty.

Tissue engineering by self-assembly offers the possibility to fabricate contiguous cell sheets that are stabilised by intact cell-cell contacts and endogenously produced extracellular matrix (ECM) However, these systems lack the possibility to introduce topographical cues, that are fundamental for the organisation of many types of tissues. Herein we venture to fabricate aligned electrospun thermoresponsive nanofibres to sustain growth and detachment of ECM-rich living substitutes in the presence of a MMC microenvironment. A copolymer of 85% poly-N-isopropylacrylamide and 15% N-tert-butylacrylamide (pNIPAAm/NTBA) were used. To create aligned nanofibers, the polymer was electrospun and collected on a mandrel rotating at 2000 rpm. Human adipose derived stem cells (hADSC) were treated with media containing macromolecular crowders to enhance matrix deposition. Cell viability and morphology were assessed, and immunocytochemistry was conducted to estimate matrix deposition and composition. Non-invasive cell detachment was enabled by decreasing the temperature of culture to 10 °C for 20 minutes. The electrospinning process resulted in the production of pNIPAm/NTBA fibres in the diameter range from 1 to 2 µm and an overall alignment of 80%. Cell viability revealed that hADSCs were able to grow on the scaffold. The cells aligned on the fibres after 3 days and they were able to detach as intact cell sheets in presence of MMC. Moreover, it was demonstrated that MMC, by a volume extrusion effect, enhances collagen type I deposition, one of the main components of the ECM. Collectively the pNIPAm/NTBA fibres were able to successfully sustain growth and detachment of ECM-rich cell sheets.

Conventional marker based optical motion capture (mocap) methods for estimating the position and orientation (pose) of anatomical segments use assumptions that anatomical segments are rigid bodies and the position of tracking markers is invariant relative to bones. Soft tissue artefact (STA) is the error in pose estimation due to markers secured to soft tissue that moves relative to bones. STA is a major source of pose estimation error and is most prevalent when markers are placed over joints. Mocap and bi-plane videoradiography data were recorded synchronously while three individuals walked on a treadmill. For all three, pose of the thigh and shank, and movement of markers relative to the bones, were determined from the videoradiography data (DSX, C-Motion). Independently, pose of thighs and shanks was estimated using mocap data (Visual3D, C-Motion). Our measures of error in the mocap pose estimation were the relative thigh and shank translations. X-ray data from two subjects were used to generate a regression model for the antero/posterior movement of the lateral knee marker against internal/external hip rotation. The mocap translation errors of the third subject, attributed to STA of the knee marker, were 15.6mm and 32.0mm respectively. The pose of the third subject was then estimated using a probabilistic algorithm incorporating our regression model. Mocap translation errors were reduced to 10.6mm (thigh) and 4.4mm (shank). The results from these data suggest that errors in pose estimation due to STA may possibly be reduced via the application of algorithms based on probabilistic inference to mocap data.

Fabrication of biogenic coatings with suitable mechanical properties is a key goal in orthopedics, to overcome the limitations of currently available coatings and improve the clinical results of coated implants compared to uncoated ones. In this paper, biological-like apatite coatings were deposited from a natural bone-apatite source by a pulsed electron deposition technique (PED).

Bone apatite-like (BAL) films were deposited directly from bone targets, obtained by standard deproteinization of bovine tibial cortical shafts and compared to films deposited by sintered stoichiometric-hydroxyapatite targets (HA). Deposition was performed at room temperature by PED in the Ionized Jet Deposition (IJD) version. Half of the samples was annealed at 400°C for 1h (BAL_400 and HA_400). As-deposited and annealed coatings were characterized in terms of composition and crystallinity (XRD, FT-IR), microstructure and morphology (SEM-EDS, AFM) and mechanical properties (nanoindentation and micro-scratch). For the biological tests, human dental pulp stem cells (hDPSCs) were isolated from dental pulp from patients undergoing a routine tooth extraction, plated on the samples (2500 cells/cm2) and cultured for 3 weeks, when the expression of typical osteogenic markers Runx-2, osteopontin, Osx and Osteocalcin in hDPSCs was evaluated.

Results showed that deposition by PED allows for a close transfer of the targets” composition. As-deposited coatings exhibited low cristallinity, that was significantly increased by post-deposition annealing, up to resembling that of biogenic apatite target. As a result of annealing, mechanical properties increased up to values comparable to those of commercial plasma-sprayed HA-coatings.

In vitro biological tests indicated that BAL_400 promotes hDPSCs proliferation to a higher extent compared to non-annealed bone coating and HA-references. Furher, immunofluorescence and western blot analyses revealed that the typical osteogenic markers were expressed, indicating that BAL_400 alone can efficiently promote the osteogenic commitment of the cells, even in absence of an osteogenic medium.

In conclusion, bone-like apatite coatings were deposited by PED, which closely resembled composition and structure of natural-apatite. Upon annealing at 400°C, the coatings exhibited satisfactory mechanical properties and were capable of providing a suitable microenvironment for hDPSCs adherence and proliferation and for them to reach osteogenic commitment.

These results suggest that bone apatite-like thin films obtained by biogenic source may represent an innovative platform to boost bone regeneration in the orthopedic, maxillofacial and odontoiatric field.

Background

The goal of this study was (1) to investigate the relationships between the bony contours of the knee and the popliteus tendon before and after TKA and (2) to analyse the influence of implant sizing. Our hypothesis was that an apparently well-sized prosthesis, will modify the position or the tracking of popliteus tendon.

To determine the mechanisms and extents of popliteus impingements before and after TKA and to investigate the influence of implant sizing. The hypotheses were that (i) popliteus impingements after TKA may occur at both the tibia and the femur and (ii) even with an apparently well-sized prosthesis, popliteal tracking during knee flexion is modified compared to the preoperative situation.

The location of the popliteus in three cadaver knees was measured using computed tomography (CT), before and after implantation of plastic TKA replicas, by injecting the tendon with radiopaque liquid. The pre- and post-operative positions of the popliteus were compared from full extension to deep flexion using normosized, oversized and undersized implants (one size increments).

At the tibia, TKA caused the popliteus to translate posteriorly, mostly in full extension: 4.1mm for normosized implants, and 15.8mm with oversized implants, but no translations were observed when using undersized implants. At the femur, TKA caused the popliteus to translate laterally at deeper flexion angles, peaking between 80º-120º: 2.0 mm for normosized implants and 2.6 mm with oversized implants. Three-dimensional analysis revealed prosthetic overhang at the postero-superior corner of normosized and oversized femoral components (respectively, up to 2.9 mm and 6.6 mm).

A well-sized tibial component modifies popliteal tracking, while an undersized tibial component maintains more physiologic patterns. Oversizing shifts the popliteus considerably throughout the full arc of motion. This study suggests that both femoro- and tibio-popliteus impingements could play a role in residual pain and stiffness after TKA.

Systemic metal ion monitoring (Co;Cr) has proven to be a useful screening tool for implant performance to detect failure at an early stage in metal-on-metal hip arthroplasty. Several clinical studies have reported elevated metal ion levels after total knee arthroplasty (TKA), with fairly high levels associated with rotating hinge knees (RHK) and megaprostheses¹. In a knee simulator study, Kretzer², demonstrated volumetric wear and corrosion of metallic surfaces. However, prospective in vivo data are scarce, resulting in a lack of knowledge of how levels evolve over time. The goal of this study was to measure serum Co and Cr levels in several types TKA patients prospectively, evaluate the evolution in time and investigate whether elevated levels could be used as an indicator for implant failure.

The study was conducted at Ghent University hospital. 130 patients undergoing knee arthroplasty were included in the study, 35 patients were lost due to logistic problems. 95 patients with 124 knee prostheses had received either a TKA (primary or revision) (69 in 55 patients), a unicompartimental knee arthroplasty (7 UKA), a RHK (revision −7 in 6 patients) or a megaprosthesis (malignant bone tumours − 28 in 27 patients). The TKA, UKA and RHK groups were followed prospectively, with serum Co and Cr ions measured preoperatively, at 3,6 and 12 months postoperatively. In patients with a megaprosthesis, metal ions were measured at follow-up (cross-sectional study design).

In primary knees, we did not observe an increase in serum metal ion levels at 3, 6 or 12 months. Two patients with a hip arthroplasty had elevated preTKA Co and Cr levels. There was no difference between unilateral and bilateral knee prostheses. In the revision group, elevated pre-revision levels were found in 2 failures for implant loosening. In both cases, ion levels decreased postoperatively. In revisions with a standard TKA, there was no significant increase in metal ions compared to primary knee arthroplasty. RHK were associated with a significant increase in Co levels even at short-term (3–12 months). The megaprosthesis group had the highest metal ion levels and showed a significant increase in Co and Cr with time in patients followed prospectively. With the current data, we could not demonstrate a correlation between metal ion levels, size of the implant or length of time in situ.

In primary knee arthroplasty with a standard TKA or UKA, metal ion levels were not elevated till one year postoperatively. This suggests a different mechanism of metal ion release in comparison to metal-on-metal hip arthroplasties. In two cases of revision for implant loosening, pre-revision levels were elevated, possibly associated with component wear, and decreased after revision. With RHK, slightly elevated ion levels were found prospectively. Megaprostheses had significantly elevated Co and Cr levels, due to corrosion of large metallic surfaces and/or wear of components which were not perfectly aligned during difficult reconstruction after tumour resection. Further research is needed to assess the clinical relevance of metal ion levels in knee arthroplasty.