KineSpring® Knee Implant System: The First of Its Kind
The KineSpring Knee Implant System is a revolutionary new therapy developed to fill the current void between conservative care and joint altering surgical interventions in the treatment of knee osteoarthritis (OA). It is intended to treat the symptoms of pain and loss of knee function secondary to OA of the medial compartment of the knee.
The shock absorbing system's design is grounded in principles of bioengineering and human kinematics and is intended to address medial knee joint overload, the underlying condition that may lead to the onset or progression of knee OA. The KineSpring System is implanted in the subcutaneous tissue alongside the joint, so it is always cushioning the knee from excessive loading. Even more importantly, the KineSpring System is completely joint sparing: since the device is extra-capsular and extra-articular, no bone, ligament, or cartilage is removed. Therefore, future treatment options are maintained.
The Science Behind the KineSpring System
Healthy joints and cartilage are exposed to mechanical loads during everyday motion and activity. While normal joint loading helps maintain the joint tissues, abnormal loading due to obesity, anatomy, or trauma can begin a clinical sequelae that includes subchondral microfractures, sclerotic bone thickening, and cartilage degradation. Many therapies attempted during the earlier stages of OA only provide pain relief or repair focal cartilage damage. These solutions may be misguided, however, if the underlying biomechanical problem is indeed joint overload. When pathological biomechanics are left untreated, the OA cascade continues and the patient often suffers through several rounds of unsuccessful therapies until he or she is a candidate for arthroplasty.
In contrast, the KineSpring System specifically addresses the biomechanics behind joint overload. The elegant design of the KineSpring System allows the absorber component of the device to actively unload and protect the knee during the stance phase of gait, while remaining passive during the swing phase.
Significantly, the device absorbs up to 13 kg, or 30 lbs. of overload; it does not transfer excess loads to other compartments of the knee.1
How Much to Unload?
Joint unloading is clinically proven to relieve pain.2-9 Non-invasive unloading techniques, such as weight loss, unloading braces, and special orthotics, can be effective if used properly. More invasive unloading techniques, including high tibial osteotomy (HTO) and joint distraction have also demonstrated pain relief for some patients.
A review of clinical journal articles suggests that once a minimum threshold of unloading is achieved, pain relief will follow. One commonly reported measurement of unloading is reduction in Knee Adduction Moment (KAM). Reports of KAM reduction between 5-19% have resulted in pain relief, with no correlation between patient weight and amount of pain relief. The therapeutic window likely extends above and below these reported levels of KAM reduction, but additional studies are required to confirm this theory.
Excessive joint load reduction can result in stress shielding and compromise joint tissue vitality.9 Combining these design variables (threshold KAM reduction and maintaining a normal load), the KineSpring System is designed to absorb up to 30 lbs. of excess load. Because the knee joint still supports a normal mechanical load, cyclic loading of the non-rigid, articulating KineSpring System is capped at 30 lbs., well below the 3x bodyweight that rigid fracture plate and screw systems can experience.
The KineSpring System is intended to treat the symptoms of pain and loss of knee function secondary to OA of the medial compartment of the knee.
1. Data on file at Moximed.
2. Christensen, et al. Weight loss: the treatment of choice for knee osteoarthritis? A randomized trial. Osteoarthritis Cartilage 2005; 13(1): 20-7.
3. Messier, et al. Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis. Arthritis Rheum 2005; 52(7): 2026-32.
4. Messier, et al. Exercise and dietary weight loss in overweight and obese older adults with knee osteoarthritis: the Arthritis, Diet, and Activity Promotion Trial. Arthritis Rheum 2004; 50(5): 1501-10.
5. Flegal K, et al. Prevalence and trends in obesity among US adults, 1999-2000. JAMA 2002; 288:1723.
6. Draganich, et al. The Effectiveness of Self-Adjustable Custom and Off-the-Shelf Bracing in the Treatment of Varus Gonarthrosis .J Bone Joint Surg Am 2006; 88(12): 2645-52.
7. Lindenfeld, et al. Joint loading with valgus bracing in patients with varus gonarthrosis. Clin Orthop Relat Res 1997; (344): 290-7.
8. Pollo, et al. Reduction of medial compartment loads with valgus bracing of the osteoarthritic knee. Am J Sports Med 2002; 30(3): 414-21.
9. Lafeber, et al. Unloading joints to treat osteoarthritis, including joint distraction. Curr Opin Rheumatol 2006; 18(5): 519-25.
