Reproducibility of an Intraoperative Pressure Sensor in Total Knee Replacement

Appropriate soft tissue tension in total knee replacement (TKR) is an important factor for a successful outcome. The purpose of our study was to assess both the reproducibility of a modern intraoperative pressure sensor (IOP) and if a surgeon could unconsciously influence measurement. A consecutive series of 80 TKRs were assessed with an IOP between January 2018 and December 2020. In the first scenario, two blinded sequential measurements in 48 patients were taken; in a second scenario, an initial blinded measurement and a subsequent unblinded measurement in 32 patients were taken while looking at the sensor monitor screen. Reproducibility was assessed by intraclass correlation coefficients (ICCs). In the first scenario, the ICC ranged from 0.83 to 0.90, and in the second scenario it ranged from 0.80 to 0.90. All ICCs were 0.80 or higher, indicating reproducibility using a IOP and that a surgeon may not unconsciously influence the measurement. The use of a modern IOP to measure soft tissue tension in TKRs is a reproducible technique. A surgeon observing the measurements while performing IOP may not significantly influence the result. An IOP gives additional information that the surgeon can use to optimize outcomes in TKR.

Design of an affordable, modular implant device for soft tissue tension assessment and range of motion tracking during total hip arthroplasty

<p>Inexperienced surgeons undertaking hip arthroplasties are twice as likely to experience errors than their experienced colleagues, leading to dislocations, pain and discomfort for the patients. To address this issue, a new 3DOF force measurement system was developed and integrated in multiple new prototypes able to measure forces and movements intraoperatively in 3D. The prototypes were evaluated in three cadaver trials, with the goal of providing surgeons objective data to help determine the optimal implant fit and configuration. The devices comprise deformable polymer material that provide strain-based displacements measured with electromagnetic-based sensors and inertial measurement unit (IMU) for motion data. Device results show an accuracy of approx. 2 N and a sensitivity of approx. 1 N. Cadaver results indicated that soft tissue forces on the hip joint peak in the order of ~100 N and trend with positions of the leg during range of motion (ROM) tests, although force patterns differ between each cadaver. We propose that by monitoring forces and force patterns, in combination with standardised ROM tests, anomalies could be detected and corrected during surgery.</p>

Current Concepts in Humeral Component Design for Anatomic and Reverse Shoulder Arthroplasty

The history of humeral component design has evolved from prostheses with relatively long stems and limited anatomic head options to a contemporary platform with short stems and stemless implants with shared instrumentation and the ability to provide optimal shoulder reconstruction for both anatomic and reverse configurations. Contemporary humeral components aim to preserve the bone, but they are potentially subject to malalignment. Modern components are expected to favorably load the humerus and minimize adverse bone reactions. Although there will likely continue to be further refinements in humeral component design, the next frontiers in primary shoulder arthroplasty will revolve around designing an optimal plan, including adequate soft tissue tension and providing computer-assisted tools for the accurate execution of the preoperative plan in the operating room.

Sequence-specific response of collagen-mimetic peptides to osmotic pressure

Native collagen molecules usually contract upon dehydration, but the details of their interaction with water are poorly understood. Previous molecular modeling studies indicated a spatially inhomogeneous response, with a combination of local axial expansion and contraction. Such sequence-dependent effects are difficult to study with native collagen. In this article, we use collagen-mimetic peptides (CMPs) to investigate the effect of osmotic pressure on several collagen-mimetic sequences. Synchrotron x-ray diffraction combined with molecular dynamics simulations shows that CMPs pack differently depending on osmotic pressure and exhibit changes in the helical rise per residue of individual molecules. Infrared spectroscopy reveals that osmotic pressure affects the stability of the triple helix through changes in triple helix-stabilizing hydrogen bonds. Surprisingly, CMPs with the canonical collagen sequence glycine–proline–hydroxyproline are found to elongate upon dehydration, while sequence modifications are able to reverse this tendency. This strongly suggests that the overall contraction of native collagen molecules is not programmed into the canonical sequence but is specific to local amino acids that substitute for proline or hydroxyproline along the protein chain. Collagen is an essential protein in mammalian extracellular tissues and a better understanding of its mechanical function is important both from a materials science and from a biomedical viewpoint. Recently, collagen has been shown to contract along the fibre direction when subjected to osmotic stress, a process that could play important roles in strengthening bone and in developing tissue tension during extracellular matrix development. The present work uses collagen-like short peptides to show that the canonical collagen sequence is not responsible for this contraction. The conclusion is that the collagen amino acid sequence must have evolved to include guest sequences within the canonical glycine-proline-hydroxyproline repeat that provide the observed contractility. Impact statement Collagen is an essential protein in mammalian extracellular tissues and a better understanding of its mechanical function is important both from a materials science and from a biomedical viewpoint. Recently, collagen has been shown to contract along the fibre direction when subjected to osmotic stress, a process that could play important roles in strengthening bone and in developing tissue tension during extracellular matrix development. The present work uses collagen-like short peptides to show that the canonical collagen sequence is not responsible for this contraction. The conclusion is that the collagen amino acid sequence must have evolved to include guest sequences within the canonical glycine-proline-hydroxyproline that provide the observed contractility. Graphic Abstract

Lymph node tissue homeostasis and adaptation to immune challenge resolved by fibroblast network mechanics

Emergent physical properties of tissues are not readily understood by reductionist studies of their constituent cells. Here, we show molecular signals controlling cellular physical properties, collectively determining tissue mechanics of lymph nodes, an immunologically-relevant, adult mammalian tissue. Lymph nodes paradoxically maintain robust tissue architecture in homeostasis yet are continually poised for extensive tissue expansion upon immune challenge. We find that following immune challenge, cytoskeletal mechanics of a cellular meshwork of fibroblasts determine tissue tension independently of extracellular matrix scaffolds. We determine that CLEC-2/podoplanin signalling regulates the cell surface mechanics of fibroblasts, permitting cell elongation and interdigitation through expedited access to plasma membrane reservoirs. Increased tissue tension through the stromal meshwork gates the initiation of fibroblast proliferation, restoring homeostatic cellular ratios and tissue structure through expansion.

How to tie dangerous surgical knots: easily. Can we avoid this?

ObjectiveSecure knots are essential in all areas of surgical, medical and veterinary practice. Our hypothesis was that technique of formation of each layer of a surgical knot was important to its security.DesignEqual numbers of knots were tied, by each of three groups, using three techniques, for each of four suture materials; a standard flat reef knot (FRK), knots tied under tension (TK) and knots laid without appropriate hand crossing (NHCK). Each knot technique was performed reproducibly, and tested by distraction with increasing force, till each material broke or the knot separated completely.SettingTemporary knot tying laboratory.MaterialsThe suture materials were, 2/0 polyglactin 910 (Vicryl), 3/0 polydioxanone, 4/0 poliglecaprone 25 (Monocryl) and 1 nylon (Ethilon).ParticipantsThree groups comprised, a senior surgeon, a resident surgeon and three medical students.Outcome measuresProportion of each knot type that slipped, degree of slippage and length of suture held in loop secured by each knot type.Results20% of FRK tied with all suture materials slipped; all knots tied with the other two techniques, with all materials, slipped, TK (100%) and NHCK (100%). The quantitative degree of slip was significantly less for FRK (mean 6.3%–, 95% CI 2.2% to 10.4%) than for TK (mean 312%, 95% CI 280.0% to 344.0%) and NHCK (mean 113.0%, –95% CI 94.3% to 131.0%).The mean length of suture in loops held within (FRK mean 25.1 mm 95% CI 24.2 to 26.0 mm) was significantly greater than mean lengths held by the other techniques (TK mean 17.0 mm, 95% CI 16.3 to 17.7 mm), (NHCK mean 16.3 mm, 95% CI 15.9 to 16.7 mm). The latter two types of knot may have tightened more than anticipated, in comparison to FRK, with potential undue tissue tension.ConclusionMeticulous technique of knot tying is essential for secure knots, appropriate tissue tension and the security of anastomoses and haemostasis effected.

Neglected сlubfoot treated by Ilizarov and Ponseti methods

The Ponseti method has revolutionized clubfoot treatment. Though completely neglected clubfeet are now rare, partially or incompletely and improperly treated feet are not uncommon. Relapses after successful correction may occur due to non-compliance with bracing. In scarred soft tissues due to previous surgery, soft tissue distraction using external fixation helps achieve correction. The Ilizarov fixator permits us to follow the Ponseti protocol, using correction methods that may either be constrained or unconstrained by hinges. Applying force vectors perpendicular to the moment arm allows us to correct the еquinus without damaging the ankle joint. All of the above is possible when the talus is round. Full correction of the deformity is possible. However, longterm follow-up of these patients has revealed stiffness of the ankle setting and frequently with tibio-talar osteophytes anteriorly. They are probably a reaction to excessive pressure developed in the joint due to the tight soft tissues. Hence the author has now added a mild shortening of the tibia and fibula to reduce soft tissue tension, rather than resorting to further soft tissue releases through scarred tissues. This allows faster correction with the Ponseti-Ilizarov protocol and allows good ankle range of motion to persist.

Current concepts in total knee arthroplasty

Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.

Morphological Changes In Bone Tissue In Chronic Osteomyelitis On The Background Of Application Of Plate Concentrate

The method of laser osteoperforation developed experimentally was approved in 142 patients with chronic osteomyelitis of different forms. A diode laser was used in which wavelength was 970 nm and power – 30 W. Laser osteoperforation was performed transcutaneously in a contact way with a quartz light guide of 0, 4 mm diameter in the projection of bone destruction foci with formation of 2-20 holes. Normalization of temperature and blood indices as well as pain decrease, reduce of soft tissue tension and edema was observed in all the patients in the immediate days after surgery. As a rule, fistulae closed by 4-10 day. In case of chronic osteomyelitis persistent remission is noted during 2-5 years by the objective data (roentgenography, flowmetry, densitometry). Thus, the experience of laser osteoperforation clinical use demonstrates its high effectiveness in treatment of osteomyelitis different forms. The method is of little invasiveness and it allows to reduce the periods of treatment and rehabilitation to a great extent.