The Effect of Robotic Technology on Perioperative Outcomes in Total Knee Arthroplasty

Introduction Robotic technology has recently regained momentum in total knee arthroplasty (TKA) but the effects of this technology on accuracy of implant positioning, intraoperative soft tissue injury and postoperative functional rehabilitation remain unknown. The objectives of this research thesis were to compare a comprehensive range of radiological objectives and perioperative outcomes in conventional jig-based TKA versus robotic-arm assisted TKA, and use optical motion capture technology to quantify the effects of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) resection on knee biomechanics. Methods A series of prospective cohort studies were undertaken in patients with established knee osteoarthritis undergoing primary conventional jig-based TKA versus robotic-arm assisted TKA. Predefined radiological and perioperative study outcomes were recorded by independent observers. Optical motion capture technology during robotic TKA was used to quantify the effects of ACL and PCL resection on knee biomechanics. Results Robotic-arm assisted TKA was associated with improved accuracy of implant positioning, reduced periarticular soft tissue injury, decreased bone trauma, improved postoperative functional rehabilitation, and reduced early systemic inflammatory response compared to conventional jig-based TKA. The Macroscopic Soft Tissue Injury (MASTI) classification system was developed and validated for grading intraoperative periarticular soft tissue injury and bone trauma during TKA. ACL resection created flexion-extension mismatch by increasing the extension gap more than the flexion gap, whilst PCL resection increased the flexion gap proportionally more than the extension gap and created mediolateral laxity in knee flexion but not in extension. Conclusion Robotic-arm assisted TKA was associated with increased accuracy of implant positioning, reduced iatrogenic soft tissue injury, and improved functional rehabilitation compared to conventional jig-based TKA. ACL and PCL resections created unique changes in knee biomechanics that affected flexion-extension gaps and mediolateral soft tissue tension during TKA. On the basis of this thesis, further clinical trials have been established to determine the long-term clinical significance of these findings

Improving surgical techniques and functional outcome in total knee arthroplasty

acceptedVersio

Variations in Surgeon-Applied Loads During Passive Range of Motion Following Total Knee Replacement With Relevance To Computational Modeling

Total knee replacement (TKR) is generally considered a successful treatment for musculoskeletal disorders of the knee. However, as many as 20% of patients report some dissatisfaction in their physical function after TKR. And approximately 50% of early revisions needed to address conditions related to component alignment and soft tissue tension to stabilize the knee. During TKR, surgeons manually perform passive range of motion (ROM) assessments to gain feedback perceived as tension in ligaments and other soft tissues. Such assessments are highly subjective and rely on the surgeon\u27s perception of soft tissue tension rather than quantitative objective means. The variability in applied loads during passive ROM assessments is poorly understood. The broad objective of this thesis was to analyze variations in surgeon-applied loads during passive ROM assessments following TKR on individual cadaver knees. There were three specific aims: 1) experimentally measure surgeon-applied loads during passive ROM of cadaver limbs implanted with TKR; 2) statistically analyze intra-specimen and inter-specimen repeatability in surgeon-applied loading profiles; and 3) process surgeon-applied external loads for input into computational models used to calculate knee ligament tensions. Three cadaveric lower limbs were implanted with TKR and mounted into a custom-designed knee rig instrumented to simulate and measure applied loads and kinematics during passive ROM assessments performed by an experienced orthopaedic surgeon. It was hypothesized that intra-specimen cycles would not be a significant factor affecting the applied loading profiles. It was hypothesized that inter-specimen differences would be a significant factor affecting applied loading profiles. The 4 degrees of freedom tracked (varus-valgus, anterior-posterior, compressive load, and internal-external rotation), external loads applied by the surgeon were highly consistent within the five cycles per trial and the 95% confidence interval varied within 0.5Nm for applied moments and within 5N for applied compressive forces. It was concluded that intra-specimen cycles were not a factor affecting the load profiles and inter-specimen differences were a significant factor affecting applied loading profiles. Variations in external loads during intra-operative assessments of component alignment and soft tissue tension can impact clinical decisions and outcomes. In a biomechanical sense, new technologies and sensors meant to aid intra-operative decisions need to accommodate variability in assumed load magnitudes during passive ROM assessments

Patient-Specific Implants in Musculoskeletal (Orthopedic) Surgery

Most of the treatments in medicine are patient specific, aren’t they? So why should we bother with individualizing implants if we adapt our therapy to patients anyway? Looking at the neighboring field of oncologic treatment, you would not question the fact that individualization of tumor therapy with personalized antibodies has led to the thriving of this field in terms of success in patient survival and positive responses to alternatives for conventional treatments. Regarding the latest cutting-edge developments in orthopedic surgery and biotechnology, including new imaging techniques and 3D-printing of bone substitutes as well as implants, we do have an armamentarium available to stimulate the race for innovation in medicine. This Special Issue of Journal of Personalized Medicine will gather all relevant new and developed techniques already in clinical practice. Examples include the developments in revision arthroplasty and tumor (pelvic replacement) surgery to recreate individual defects, individualized implants for primary arthroplasty to establish physiological joint kinematics, and personalized implants in fracture treatment, to name but a few

Development of the Telemetrical Intraoperative Soft Tissue Tension Monitoring System in Total Knee Replacement with MEMS and ASIC Technologies

The alignment of the femoral and tibial components of the Total Knee Arthoplasty (TKA) is one of the most important factors to implant survivorship. Hence, numerous ligament balancing techniques and devices have been developed in order to accurately balance the knee intra-operatively. Spacer block, tensioner and tram adapter are instruments that allow surgeons to qualitatively balance the flexion and extension gaps during TKA. However, even with these instruments, the surgical procedure still relies on the skill and experience of the surgeon. The objective of this thesis is to develop a computerized surgical instrument that can acquire intra-operative data telemetrically for surgeons and engineers. Microcantilever is chosen to be used as the strain sensing elements. Even though many high end off-the-shelf data acquisition components and integrated circuit (IC) chips exist on the market, yet multiple components are required to process the entire array of microcantilevers and achieve the desired functions. Due to the size limitation of the off-chip components, an Application Specific Integrated Circuit (ASIC) chip is designed and fabricated. Using a spacer block as a base, sensors, a data acquisition system as well as the transmitter and antenna are embedded into it. The electronics are sealed with medical grade epoxy

Polymeric Microsensors for Intraoperative Contact Pressure Measurement

Biocompatible sensors have been demonstrated using traditional microfabrication techniques modified for polymer substrates and utilize only materials suitable for implantation or bodily contact. Sensor arrays for the measurement of the load condition of polyethylene spacers in the total knee arthroplasty (TKA) prosthesis have been developed. Arrays of capacitive sensors are used to determine the three-dimensional strain within the polyethylene prosthesis component. Data from these sensors can be used to give researchers a better understanding of component motion, loading, and wear phenomena for a large range of activities. This dissertation demonstrates both analytically and experimentally the fabrication of these sensor arrays using biocompatible polymer substrates and dielectrics while preserving industry-standard microfabrication processing for micron-level resolution. An array of sensors for real-time measurement of pressure profiles is the long-term goal of this research. A custom design using capacitive-based sensors is an excellent selection for such measurement, giving high spatial resolution across the sensing surface and high load resolution for pressures applied normal to that surface while operating at low power

Poro-viscoelastic material parameter identification of brain tissue-mimicking hydrogels

Understanding and characterizing the mechanical and structural properties of brain tissue is essential for developing and calibrating reliable material models. Based on the Theory of Porous Media, a novel nonlinear poro-viscoelastic computational model was recently proposed to describe the mechanical response of the tissue under different loading conditions. The model contains parameters related to the time-dependent behavior arising from both the viscoelastic relaxation of the solid matrix and its interaction with the fluid phase. This study focuses on the characterization of these parameters through indentation experiments on a tailor-made polyvinyl alcohol-based hydrogel mimicking brain tissue. The material behavior is adjusted to ex vivo porcine brain tissue. An inverse parameter identification scheme using a trust region reflective algorithm is introduced and applied to match experimental data obtained from the indentation with the proposed computational model. By minimizing the error between experimental values and finite element simulation results, the optimal constitutive model parameters of the brain tissue-mimicking hydrogel are extracted. Finally, the model is validated using the derived material parameters in a finite element simulation