KineSpring® Knee Implant System: A First Surgical Option
The KineSpring System is designed to be a first surgical option for patients with 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 KineSpring System is a partial load absorber that reduces knee joint load by up to 13 kg. The absorber is implanted in the extra-capsular space along the medial side of the joint, and it is actively unloading the knee during the stance phase of gait. 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, the procedure is reversible.
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 OA therapies only provide short-term 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.
How Much to Unload?
Joint unloading is clinically proven to relieve pain.1-8 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 literature indicates 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.
Healthy cartilage requires normal loading and motion to maintain homeostasis.9,10 Furthermore, unloading osteoarthritic cartilage and maintaining motion is known to reduce OA symptoms, progression and potentially reverse cartilage damage. 10,11 Combining these design variables, the KineSpring System is designed to absorb up to 13 kg of load while maintaining normal kinematics.
1. Christensen, et al. Weight loss: the treatment of choice for knee osteoarthritis? A randomized trial. Osteoarthritis Cartilage 2005; 13(1): 20-7.
2. 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.
3. 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.
4. Flegal K, et al. Prevalence and trends in obesity among US adults, 1999-2000. JAMA 2002; 288:1723.
5. 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.
6. Lindenfeld, et al. Joint loading with valgus bracing in patients with varus gonarthrosis. Clin Orthop Relat Res 1997; (344): 290-7.
7. Pollo, et al. Reduction of medial compartment loads with valgus bracing of the osteoarthritic knee. Am J Sports Med 2002; 30(3): 414-21.
8. Lafeber, et al. Unloading joints to treat osteoarthritis, including joint distraction. Curr Opin Rheumatol 2006; 18(5): 519-25.
9. Crawford, D. Cartilage, Mechanical Load & Biology of Osteoarthritis. Joint Unloading for the Young Arthritic Patient: Rationale, Techniques, Practical Workshop. ESSKA 2012 Industry Symposium. Geneva, Switzerland.
10. Salzman, et al. Motion versus fixed distraction of the joint in the treatment of ankle osteoarthritis: A prospective randomized controlled trial. J Bone Joint Surg Am 2012; 94: 961-70.