Knee joint loading

Smith, A.J., Lloyd, D.G., and Wood, D.J., Pre-surgery knee joint loading patterns during walking predict the presence and severity of anterior knee pain after total knee arthroplasty, /. Orthop. Res., 22,260,2004. 

Summary of Average Knee joint Loading for Activities of Daily Living... 

The development of satisfactory total replacement synovial joints is sometimes described as the major advance in orthopaedic surgery in recent times. The hip joint was the first major load bearing joint to respond to the efforts of surgeons, engineers and materials scientists in the past two decades to develop satisfactory replacements, but attention is now focussed upon the more complex knee joint. 

A knee joint simulator was designed and built in the bioengineering laboratory at Leeds in the late 1970 s to enable the mechanical and tribological characteristics of current and projected knee joint replacements tp.he assessed. The simulator has been described by Dowson et al and it is shown in Figure 1. Realistic load and motion cycles are applied to the knee joints to simulate any desired activity, but usually walking, and the penetration of the metallic femoral components into the polymeric tibial components after a large number of cycles can then be used to assess the life of the joints. Furthermore, the penetrations recorded, which include both wear and creep, can be related to results of laboratory wear studies of the behaviour of UHMWPE and to the in-vivo performance of total replacement knee joints. The simulator is therefore an Important machine in both the pragmatic and fundamental aspects of total replacement knee join development. 

The derived wear factor (k) for the Freeman-Swansog and Leeds knee joints tested in the simulator for about 10 cycles are both interesting and similar. The ln-vlvo Freeman-Swanson joint was kindly made available by Professor S.A.V. Swanson and the conditions of service were not known with any certainty. The joint had functioned in an elderly patient for some four years, with a light to medium level of walking activity. It was therefore assumed that /PdX remained constant at 47.7 Nm/cycle and that the patient achieved 6000 strides or 3000 loading cycles per day. These assumptions are consistent with a subsequent study of the walking activity of patients fitted with total replacement joints reported by Wallbrldge and Dowson, but considerable scope for errors... 

The prosthesis for total knee joint replacement consists of femoral, tibial, and patellar components. Compared to the hip joint, the knee joint has a more complicated geometry and movement biomechanics, and it is not intrinsically stable. In a normal knee, the center of movement is controlled by the geometry of the ligaments. As the knee moves, the ligaments rotate on their bony attachments and the center of movement also moves. The eccentric movement of the knee helps distribute the load throughout the entire joint surface [Burstein and Wright, 1993]. 

Paul, l.P. 1976. Loading on normal hip and knee joints and joint replacement.. In Advances in Hip and Knee Joint Technology, M. Schaldach and D. Hohmann (Eds.), pp. 53-77, Springer-Verlag, Berlin. 

Muscle and joint loading are much lower during gait than during knee-extension exercise. Various studies have used inverse-dynamics or static optimization (Hardt, 1978 Crowninshield and Brand, 1981 Glitsch and Baumann, 1997) and forward-dynamics or dynamic optimization (Davy and Audu,... 

Co-Cr-Mo + UHMWPE (Duo-Patella) 1.8 mg/10 cycles NA Knee joint simulator 700 lb peak load Velocity = 33 cycles/min Duration 10 cycles Lub double spun bovine serum Creep and fatigue cracks evident. Rose et al (1984)... 

Scientists have used water to create almost frictionless lubricated surfaces that stay slippery even under heavy loads. The coating they have developed could shed light on how natural joints are lubricated and provide new ways to protect hip and knee joint implants from friction damage. Over time, the body s immune systan attacks artificial joints. Researchers are now targeting biological interactions rather than trying to solve the problem with new materials. 

The pivot-shift phenomenon [9, 31], which consists of a tibial anterior dislocation and a subsequent reduction of lateral compartment of the knee joint, is a dynamic instability [3, 9]. Losee reported the pivot-shift test in which the hip was abducted and the knee was passively flexed from full extension with internal tibial torque, axial load, and valgus stress applied manually to induce the pivot-shift phenomenon (Eig. 11.3) [3]. The pivot-shift test is usually positive in ACL-deficient knees but sometimes positive in ACL-reconstructed knees in which anterior stability has been successfully restored. The pivot-shift test has been reported to be associated with subjective symptoms and knee functions [32] therefore, this test has been considered as an important test to assess knee stability. The grade of the pivot-shift phenomenon can be graded by the examiner subjectively as none (—), glide (+), clunk (++), or gross (+++) according to the International Knee Documentatimi Committee (IKDC) form (Table 11.2) [33]. 

For the cell source, we focused on MSC and endothelial progenitor cell (EPC). With MSCs, we evaluated biomechanically and histologically whether intra-articularly injected MSCs can accelerate the healing of a partially tom ACL using a rat model. We created an ACL partially transected model in rats and injected 1 X 10 MSCs into the knee joint [38]. We demonstrated that the transected area was covered with healing tissues at 2 and 4 weeks after MSC injection, and we found that the ultimate failure load of the femur-ACL-tibia complex was significantly improved by intra-articular MSC injection (Fig. 43.2). 

BS ISO 14243-1 (2009), Implants for surgery. Wear of total knee-joint prostheses. Loading and displacement parameters for wear-testing machines with load control and corresponding environmental conditions for test, London, British Standards Institute. 

Bones, and their joints, are sometimes damaged by accidents, disease, aging, etc. When hip and knee joints are damaged, patients sometimes feel severe pain, and have much difficulty in walking, since these joints must slide smoothly at least a few thousand times every day under a load over several times body weight. In such cases, the joints must be replaced with artificial ones. The present number of hip and knee joints replaced with artificial ones total about 100 000 in Japan, and 600 000 in the United States. 

Figure 17.1 Knee joint with color coding of different skeletal tissue (cartilage, gray ligament/ tendon, white bone, black), loading characteristics, and mechanical properties.

In the present study, a knee joint simulator is used to simulate the tibial axis load and flexion-extension motion under walking condition. The lubrication condition or fluid film formation in knee prosthesis models is evaluated by measuring the electric contact resistance between the femoral metallic component and tibial conductive polymeric or elastomeric component under the constant applied voltage in a knee joint simulator. 

The mechanical simulation of movement and load conditions of the knee joint is attained by the knee joint simulator shown in Flg.l. The general view of the simulator is shown in Fig. 2. The tibial axis load[7 in Fig. 1] and flexion-extension motion [4] for steady walking were fed to this simulator. Their model patterns (6, 7) are depicted in Fig. 3. In the present test, the... 

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