Combining sensor and robotic technologies to achieve a well balanced total knee arthroplasty while avoiding any soft tissue releases

Achieving a balanced total knee throughout the entire range of motion leads to improved patient reported outcomes and satisfaction. Sensor-assisted technology allows the surgeon to quantitatively assess and address imbalance through either soft tissue releases or bone recuts. However, balancing through soft tissue releases leads to unpredictable gap increments and frequent early over-releases.METHODS: During a consecutive and prospective series of 29 robotic total knee surgeries, intra-operative load sensors were used following the initial bone resections to quantitatively assess the knee’s state of balance through the range of motion with trial components in place. Load measurements were taken at 10 and 90 degrees of knee flexion. Based on previous literature, a balanced knee is defined as having a mediolateral load difference below 15 pounds (lbf) through the range of motion, with an absolute load magnitude per compartment above 5lbf and not exceeding 45lbf. The initial load numbers were recorded as well as the number and type of subsequent corrections needed to achieve quantitative balance.RESULTS Of the 29 robotics cases, only 12 (41%) were well-balanced after the initial bone cuts (mechanical alignment by measured resection). Another two cases were too loose and required an increase in the polyethylene thickness size of two millimeters to achieve a well-balanced knee without further bone resection. In 14 cases, a bone recut was required to balance the knee. More specifically, four cases required a recut of the femur, ten cases required a recut of the tibia. Eventually, one case was left unbalanced in flexion with a mediolateral load differential of 20 lbf. It should be noted explicitly that no soft tissue releases were done for any of the 29 cases. At the end, all 29 knees were considered well balanced in extension and all but six (79%) at 90° of flexion. For these six cases with balance issue at 90° of flexion, absolute load magnitude in both compartments was below 45 lbf and above 5lbf, though the mediolateral load differential was between 15lbf and 30lbf.DISCUSSION Based on a preliminary series, this work demonstrates the opportunity of combining multiple technologies to achieve a quantitatively balanced knee through the range of motion without any soft tissue release.

Numerical Simulation of Reflective Crack Forming in Semi-Rigid Asphalt Pavement Subjected to Traffic Load

Reflective crack is one of the major technical problems in highway with semi-rigid base, studying its formatting mechanism is of great significance. By means of a numerical analysis method named RFPA, formatting process of reflective crack such as initiation and expansion was studied in asphalt pavement with semi-rigid base. Two-dimensional model of asphalt pavement with cement-treated base was established based on mechanical parameters, thickness and homogeneity of commonly used structural layer in china, symmetrical and non-symmetrical load were both considered, and crack of cement-treated base was set before loaded. First, reasons for crack initiation were studied below the bottom layer subjected to different types of loads. The conclusion showed crack under symmetrical load mainly due to pull destruction while crack under non-symmetrical load mainly due to shear failure. Then, crack expansion in asphalt layer subjected to different load numbers with different homogeneity material was studied. The result showed that with the increase of the load numbers, the deformation in the same level deformation grows continuously. Different homogeneity level of layer material has an important influence on crack expansion; higher homogeneity has better regularity.

The Impact of State and Federal Legislation on Public School Speech, Language, and Hearing Clinicians

This study reports the effects of Massachusetts Law Chapter 766 on 211 public-school speech, language, and hearing clinicians approximately 14 months after its September 1974 implementation. Data revealed that since the implementation of Chapter 766, there has been a 38% reduction in case load numbers and a 22% increase in number of clinicians hired. Clinician case load profiles have changed and now reflect significantly greater numbers of children with language disorders and more severely handicapping conditions. Clinicians reported a significant increase in interaction with other specialists, paperwork and administrative duties, inservice education, supervision, preschool screening, writing behavioral objectives, and other education-related activities. They expressed high interest in training that would better prepare them to participate as an integral part of total educational services.