Hip and Knee Machines

Controlled. Gentle. Effective.

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Providing a targeted, safe, and efficient solution.

David Hip & Knee Solution is the key to managing the challenges set by an aging population and improving surgery outcomes with pre- and post-operative treatment programs.



The David Hip & Knee Solution is designed to tackle
various hip and knee-based disorders using
the most effective and biomechanically correct
cloud-based rehabilitation system available.

Tackling the degeneration with movement

Human joints were designed by nature to last about 40 years. Degenerative diseases of the joints have become the main reason for pain, and therefore, quality of life in the middle-aged and elderly population has decreased.
The popularity of football, ice hockey, and skiing have all contributed to the increased frequency of injuries, such as MCL tears. There is an increasing consensus in the medical community that controlled physical activity can be a major contributing factor in preventing and healing various knee and hip problems.
Also, it is a well-proven fact that for many musculoskeletal illnesses that require surgery as treatment, the outcome has been significantly improved by rehabilitative muscle training.

Several studies have shown that movement can act as medicine for painful joints. With joints like the knee, which are relatively simple structures, movements are simple, and loading is easy to apply in a controlled manner, but special devices are required to isolate the target area to provide total control in the movement and loading.
All movements should start with limited range, low loading, and within the pain tolerance. Time is essential since physiological changes are slow. Ideal treatment should run for three months with an ongoing program afterwards.

Typical indications

Osteoarthritis is the most common cause of chronic disability among the aging population. The effectiveness of an exercise in knee and hip osteoarthritis is attributed to its ability to reverse muscle sensomotoric dysfunction (weakness, fatigue, poor control) preventing abnormal movement, and to restore normal biomechanics, effecting better gait, relieving pain, and improving function.
The medial collateral ligament is one of the most injured ligaments of the knee. The treatment of medial-sided knee injuries has evolved from surgical treatments to mostly non-operative management with an appropriate functional rehabilitation program. Active range of motion is initiated early to prevent stiffness with associated strengthening exercises.
Patellar instability describes patellar dislocation, patellar subluxation, and general symptomatic patellar instability. It accounts for 11% of the musculoskeletal symptoms, and has a higher incidence rate in females. Patellar instability can often be treated successfully without an operation. For ideal rehabilitation, pain should be avoided during exercise.
The anterior cruciate ligament (ACL) of the knee controls the movement of the lower leg bone (tibia) relative to the thigh bone (femur) and guides knee extension. The goal of treating ACL ruptures is to obtain the best functional level for the patient without risking new injuries or degenerative changes in the knee.

Scientific evidence

Our unique variable resistance method was examined in a set of studies supervised under Professor Paavo Komi, which compared David to other methods and used EMG to validate the correctness of the loading curves and efficacy of training. The outcomes were very clear; the David variable principle was optimal and had a great fatiguing effect on the muscles.

In conclusion, the present findings suggest that the repeated concentric contractions of the knee extensor muscles against the variable resistance may create optimal loading conditions that result in great fatiguing effects on the neuromuscular performance.

E.g. Effects of fatiguing loading with variable resistance equipment on neural activation and force production of the knee extensor, K. Häkkinen, H. Kauhanen and P. V. Komi, Electromyogr. Clin. Neurophysiol. 1988, 28, 79-87.

One study compared the David variable resistance against artificial (pneumatic) loading (HUR). The findings demonstrated that with correct variable loading, it is possible to provide greater levels of fatigue, which is essential in restoring the function of any joint.

The present study showed that, at least in untrained subjects, the weight stack device induced greater levels of peripheral fatigue during hypertrophic loading. It also led to large central fatigue during maximum strength loading and power loading.

Neuromuscular responses to different resistance loading protocols using pneumatic and weight stack devices, Heikki Peltonen, Keijo Häkkinen, Janne Avela, Journal of Electromyography and Kinesiology (2012). 

Another study looked at variable vs. constant resistance in a leg press exercise and found that the best training effect can be obtained by slightly increasing loading with a variable resistance method (used in David G210 Multifunctional Leg Press).

This study has demonstrated that the use of variable resistance during the leg press exercise can increase force and consequently EMG activity at larger knee angles during single repetition steady-paced contractions.

Kinetic and electromyographic analysis of single repetition constant and variable resistance leg press actions, Simon Walker, Heikki Peltonen, Janne Avela, Keijo Häkkinen, Journal of Electromyography and Kinesiology 21 (2011) 262–269.


biomechanical engineering creates safety, control, and effectiveness. This means that optimally designed devices can be utilized both in early-stage rehabilitation as well as in high-intensity elite athletes’ training.
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