Simultaneous Evaluation of Bone Cut and Implant Placement Accuracy in Robotic-Assisted Total Knee Arthroplasty.

Background: This study aimed to evaluate the accuracy of bone cuts and implant placements, simultaneously, for total knee arthroplasty (TKA) performed using a system with an active robotic arm. Methods: Two experienced orthopaedic surgeons performed TKA on ten cadaveric legs. Computed tomography scans were performed to compare the bone cuts and implant placements with the preoperative planning. The differences between the planned and actual bone cuts and implant placements were assessed using positional and angular errors in the three anatomical planes. Additionally, the cut-implant deviations were calculated. Statistical analysis was performed to detect systematic errors in the bone cuts and implant placements and to quantify the correlations between these errors. Results: The root-mean-square (RMS) errors of the bone cuts (with respect to the planning) were between 0.7-1.5 mm and 0.6-1.7°. The RMS implant placement errors (with respect to the planning) varied between 0.6-1.6 mm and 0.4-1.5°, except for the femur and tibia in the sagittal plane (2.9°). Systematic errors in the bone cuts and implant placements were observed, respectively, in three and two degrees of freedom. For cut-implant deviations, the RMS values ranged between 0.3-2.0 mm and 0.6-1.9°. The bone cut and implant placement errors were significantly correlated in eight degrees-of-freedom (ρ ≥ 0.67, p < 0.05). Conclusions: With most of the errors below 2 mm or 2°, this study supported the value of active robotic TKA in achieving accurate bone cuts and implant placements. The findings also highlighted the need for both accurate bone cuts and proper implantation technique to achieve accurate implant placements.

Anterior Petrosectomy With Intertentorial Approach.

BACKGROUND AND OBJECTIVES: The extradural anterior petrosal approach (EAPA) can present a challenge because it deals with critical structures in a narrow, confined corridor. It is associated with several potential approach-related risks including temporal lobe and venous injuries. Tentorial peeling has the potential to largely eliminate these risks during the approach and may offer more options for tailoring the dural opening to the anatomic region that one wants to expose. METHODS: Anatomic dissections of five adult injected non-formalin-fixed cadaveric heads were performed. Anterior petrosectomy with intertentorial approach (APIA) through a tentorial peeling was completed. Step-by-step documentation of the cadaveric dissections and diagrammatic representations are presented along with an illustrative case. RESULTS: Tentorial peeling separates the tentorium into a temporal tentorial leaf and posterior fossa tentorial leaf, adding a fourth dural layer to the three classic ones described during a standard EAPA. This opens out the intertentorial space and offers more options for tailoring the dural incisions specific to the pathology being treated. This represents a unique possibility to address brainstem or skull base pathology along the mid- and upper clivus with the ability to keep the entire temporal lobe and basal temporal veins covered by the temporal tentorial leaf. The APIA was successfully used for the resection of a large clival chordoma in the illustrative case. CONCLUSION: APIA is an interesting modification to the classic EAPA to reduce the approach-related morbidity. The risk reduction achieved is by eliminating the exposure of the temporal lobe while maintaining the excellent access to the petroclival region. It also provides several options to tailor the durotomies based on the localization of the lesion.

Posterior to anterior malleolar extended lateral approach to the ankle (PAMELA): a cadaveric anatomic study.

INTRODUCTION: The posterolateral approach is used in most cases of surgical treatment of ankle fractures involving the posterior and lateral malleoli. However, this approach does not allow access to the anterolateral structures of the ankle, which represent important landmarks to allow an anatomical reduction in case of complex ankle fracture. Our objective is to propose a novel surgical approach for optimal management of injuries including both a fracture of the posterior malleolus and a complex lesion of the lateral and/or anterolateral portions of the ankle. METHODS: Cadaveric dissection, including a vascular study, was performed on eight specimens. Assessment included density of the vascular supply around the lateral malleolus, identification of the structures at risk, quality of exposure of the bony structures, and convenience of hardware fixation. RESULTS: The cutaneous flap benefits from a rich interconnected arterial supply. Structures at risk, including the superficial peroneal and sural nerves, the lesser saphenous vein, and the peroneal artery are easily identified and protected. The interval between the peroneal tendons and the flexor hallucis longus muscle provides optimal access to the posterior malleolus. The lateral malleolus is exposed by retracting the peroneal tendons medially. An anterolateral arthrotomy, respecting the anterior talofibular and tibiofibular ligaments, offers a sharp view on the talo-tibio-fibular junction. Hardware placement can be done with optimal access to any exposed surfaces. CONCLUSIONS: The PAMELA opens a new perspective in the optimal management of complex fractures of the ankle. The approach allows optimal exposure to address fractures of the posterior malleolus, of the lateral malleolus, and of the anterolateral portion of the ankle through a single incision. Application in clinical practice is the subject of a future study in our institution.

Toward safer thanatopraxy cares: formaldehyde-releasers use.

Human cadavers constitute very useful educational tools to teach anatomy in medical scholarship and related disciplines such as physiology, for example. However, as biological material, human body is subjected to decay. Thanatopraxy cares such as embalming have been developed to slow down and inhibit this decay, but the formula used for the preservation fluids are mainly formaldehyde (FA)-based. Very recently, other formulas were developed in order to replace FA, and to avoid its toxicity leading to important environmental and professional exposure concerns. However, these alternative FA-free fluids are still not validated or commercialized, and their efficiency is still under discussion. In this context, the use of FA-releasing substances, already used in the cosmetics industry, may offer interesting alternatives in order to reduce professional exposures to FA. Simultaneously, the preservation of the body is still guaranteed by FA generated over time from FA-releasers. The aim of this review is to revaluate the use of FA in thanatopraxy cares, to present its benefits and disadvantages, and finally to propose an alternative to reduce FA professional exposure during thanatopraxy cares thanks to FA-releasers use.

Role of the microtubule destabilizing proteins SCG10 and stathmin in neuronal growth.

The related proteins SCG10 and stathmin are highly expressed in the developing nervous system. Recently it was discovered that they are potent microtubule destabilizing factors. While stathmin is expressed in a variety of cell types and shows a cytosolic distribution, SCG10 is neuron-specific and membrane-associated. It contains an N-terminal targeting sequence that mediates its transport to the growing tips of axons and dendrites. SCG10 accumulates in the central domain of the growth cone, a region that also contains highly dynamic microtubules. These dynamic microtubules are known to be important for growth cone advance and responses to guidance cues. Because overexpression of SCG10 strongly enhances neurite outgrowth, SCG10 appears to be an important factor for the dynamic assembly and disassembly of growth cone microtubules during axonal elongation. Phosphorylation negatively regulates the microtubule destabilizing activity of SCG10 and stathmin, suggesting that these proteins may link extracellular signals to the rearrangement of the neuronal cytoskeleton. A role for these proteins in axonal elongation is also supported by their growth-associated expression pattern in nervous system development as well as during neuronal regeneration.