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Reasons To Choose the Medial Ball-and-Socket Knee

Further updates on why you should choose the medial ball-and-socket knee will be posted here and shared on LinkedIn, please bookmark our page and ‘follow us’ to keep up-to-date on all our news, meetings and events!

A Pedigree with Heritage and Clinical Data

  • The original ball-and-socket knee portfolio
  • Over 25 years’ clinical heritage and ODEP 13A[1]
  • Low revision rates, better high-end activity
  • Better patient-reported success and satisfaction
  • A step further for the ‘forgotten knee’

The Medial Rotation Knee™ (MRK™) is the most successful total knee replacement on the market; this is demonstrated in The National Joint Registry alongside comparative studies on other products.

The MRK™ was patented by Finsbury Orthopaedics in 1990 and developed based on the company’s vast knowledge of anatomy and structures of the knee dating back to 1978. This anatomical approach along with a desire to meet the patients’ growing needs has resulted in a revolutionary and very successful knee design that resembles the movement of the natural knee – we refer to this as the medial-ball- and-socket design.

The MatOrtho SAIPH® Knee is a modern update of the MRK™ , it has been developed using the same principles and it is presenting the same high levels of satisfaction.

For more information please visit the product pages to freely download literature or arrange to speak with your local representative.

  1. Orthopaedic Data Evaluation Panel (ODEP). Latest ODEP ratings can be found at


Natural Asymmetry

  • Anatomical and functional asymmetry
  • Physiological medial stability
  • Lateral freedom to move AP
  • Physiologically lateralised trochlea
  • Normal feeling of stability and movement

In normal healthy knees the shapes of the medial and lateral tibial condyles are different: the medial side is concave; the lateral side is convex. Stability is provided collectively by the collateral ligaments (ACL and PCL) and the menisci.

The resulting pattern of movement during flexion is asymmetric: the medial condyle is stable throughout the range of motion; on the lateral side there is limited freedom to move anterior-posterior (tibia with respect to femur).

The anatomy of the patellofemoral articulation is also asymmetric: the femoral trochlea is lateral to the midline and the patella has a larger lateral facet compared to the medial facet. As a result, normal patellar tracking is asymmetric.

The Medial Rotation Knee™ (MRK™) and the SAIPH® Knee were both designed on the principle that by providing this asymmetry in all three components, better function and increased patient satisfaction can be achieved. The clinical data supports this philosophy.


Complete Stability

  • Substitutes for the ACL, PCL and meniscus
  • Full-range Posterior Stabilised
  • No mid-stance instability or paradoxical motion
  • Physiological lateral stability from extensor mechanism

A ‘medial pivot’ design implies that a TKR is intended to conform to an idea that the normal knee always exhibits a medial centre of rotation. This is not the case: the normal knee centre of rotation is not static and in some activities lateral AP translation is suppressed. Normal knees are however stable throughout flexion. The provision of stability by the articular shapes and constraining tissues is greatest on the medial side but both the lateral and patellofemoral compartments also contribute to stability. If any compartment is neglected, the outcome is compromised.

As such, the defining principle of MatOrtho® ball-and-socket knees is the provision of full-ROM stability. Because this is achieved with a medial deep-dish ball-and-socket articulation the concept is better termed ‘medially stabilised’. However overall stability is achieved with appropriate constraint in all compartments and this is demonstrated by assessment of total knee AP stability throughout ROM.

The defining principle of MatOrtho® ball-and-socket knees is provision of full-ROM stability.


Designed Without Compromise

  • Combines the design attributes of all four basic philosophies in Total Knee Replacement
  • Highly conforming, low contact stress for low wear
  • Proportional flexion radii for the patient population
  • Tibia locking mechanism eliminates micromotion

The MatOrtho® medial ball-and-socket knee design consistently achieves superior functional performance and excellent survivorship. With a heritage of low revision rates, the fixation design and tibiofemoral constraint work with normal knee function and preserve fixation longevity.

Proven materials are used with long-standing clinical evidence to support its design. The design provides the right balance for natural freedom of movement and stability for every compartment (medial, lateral and patellofemoral).

The medial-ball-and-socket knee provides the benefits of all other bearing designs rolled into one: fixed condylar, bicruciate substituting, posterior stabilised and mobile bearing.

The unique and proven tibia locking mechanism eliminates micromotion, which can be experienced with alternative designs, and offers excellent femoral and tibial contact throughout ROM resulting in low stresses and wear on the implant components.

The clinical data supports this information.

Information relating to our knee portfolio can be found on the relevant product page.

A useful document for your reference is the SAIPH® Clinical Rationale –


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