Medacta Corporate

Different needs...
Your global
solution

DIFFERENT NEEDS, YOUR GLOBAL SOLUTION

In 2003 Medacta conceived  a simple, complete and homogeneous system for knee replacement, ranging from uni-compartmental to totally
constrained (hinge). The GMK Primary System is conceived and designed adopting state-of-the-art solutions respecting the natural anatomy
and kinematics of the knee joint.

 

  1. Asymmetric tibial tray ensures a perfect coverage of the tibial resection, minimizing the risk of overhang and sinking
  2. Mirror polished tibial tray minimizes the risk of backside wear, both for mobile and fixed bearing
  3. Bone preserving design: minimum condylar resections and posterior stabilized version without any box needed
  4. Besides the traditional symmetric inset patella, GMK offers also the asymmetric resurfacing patella increasing the patella-femur contact surface, reducing stress on polyethylene and improving stability
  5. Anatomic design of the trochlea optimizes the patellar tracking, reducing stress on patellar tendon and the risk of patella dislocation
  6. J-curved sagittal profile allows more natural knee kinematics, improves knee flexion and promotes rollback of the femoral component
  7. Large tibial fins ensure rotational stability, moreover a 11x65 mm cemented tibial extension stem is available when further stabilization is needed

The GMK Primary product range, including mobile and fixed bearings, offers different levels of constraint:

  • Cruciate retaining
  • Ultracongruent
  • Posterior-stabilised

STANDARD FEMORAL COMPONENT

7  sizes
Anatomical: left and right
Material: Cobalt-Chrome (Co-Cr-Mo ISO 5832-4)
Cemented: 0.5 mm deep pockets
Cementless: Porous Titanium + Hydroxyapatite double coating
Antiallergic TiNb coated version (cemented only)

POSTERIOR-STABILISED FEMORAL COMPONENT

7  sizes
Anatomical: left and right
Material: Cobalt-Chrome (Co-Cr-Mo ISO 5832-4)
Cemented: 0.5 mm deep pockets
Cementless: Porous Titanium + Hydroxyapatite double coating
Antiallergic TiNb coated version (cemented only)

FIXED TIBIAL COMPONENT

6 sizes
Anatomical: left and right
Material: Cobalt-Chrome (Co-Cr-Mo ISO 5832-4)
Cemented: 0.5 mm deep pockets
Cementless: Porous Titanium + Hydroxyapatite double coating
Antiallergic TiNb coated version (cemented only)

MOBILE TIBIAL COMPONENT

6 sizes
Anatomical: left and right
Material: Cobalt-Chrome (Co-Cr-Mo ISO 5832-4)
Cemented: 0.5 mm deep pockets
Cementless: Porous Titanium + Hydroxyapatite double coating
Antiallergic TiNb coated version (cemented only)

STANDARD FIXED INLAY (CRUCIATE RETAINING)

Symmetric
Anterior flare to accommodate patellar tendon
6 sizes
Five levels of thickness (10, 12 ,14, 17, 20 mm)
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)

ULTRACONGRUENT FIXED INLAY

Symmetric, deep dish
Anterior flare to accommodate patellar tendon
6 sizes
Five levels of thickness (10, 12 ,14, 17, 20 mm)
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)

POSTERIOR-STABILISED FIXED INLAY

Symmetric
Anterior flare to accommodate patellar tendon
6 sizes
Five levels of thickness (10, 12 ,14, 17, 20 mm)
Additional fixation screw
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2

STANDARD MOBILE INLAY (CRUCIATE RETAINING)

Symmetric
Anterior flare to accommodate patellar tendon
7 sizes
Five levels of thickness (10, 12 ,14, 17, 20 mm)
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)

ULTRACONGRUENT MOBILE INLAY

Symmetric, deep dish
Anterior flare to accommodate patellar tendon
7 sizes
Five levels of thickness (10, 12 ,14, 17, 20 mm)
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)

RESURFACING PATELLA

Anatomical shape
4 sizes
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)
Cemented
Three fixation pegs

INSET PATELLA

Round shape
4 sizes
Machined Ultra High Molecular Weight Polyethylene (UHMWPE ISO 5834-2)
Cemented
One central fixation peg

TIBIAL EXTENSION STEM

Diameter x length: 11x 30 mm and  11 x 65 mm
Cemented

ARTICULAR PROFILE

J-curved sagittal profile helps with more natural knee kinematics,  improves knee flexion and promotes femoral roll back. [7,8]

ANTI-NOTCHING ANTERIOR CUT

The 4° sloped anterior cut creates a wedge effect that improves primary stability and reduces the risk of anterior notching.

PATELLO-FEMORAL JOINT

The GMK Primary patello-femoral joint is designed to mimic the natural anatomy and kinematics of the healthy knee in order to optimise patella tracking, improve articular stability and reduce polyethylene wear. GMK incorporates state of the art design features:

  • Deepened trochlear groove: allowing the patella to articulate at the same height as the normal patella, reducing the occurrence of patella clunk and crepitus. [1]
  • Wide contact area between patella and femoral component: reducing  polyethylene stress due to compressive forces. [2,3,4]
  • Higher anterior-lateral wall of the femoral component: guiding and supporting the patella in the initial phases of flexion.
  • 6° oriented sulcus: limiting lateral shear forces on the patella component. [2,6]
  • Asymmetric resurfacing patella with a prolonged lateral flange: providing better contact surface and mimicking the shape of natural patella. [5]

MATERIAL
Published papers show that polyethylene that does not undergo any irradiation or thermal treatments, that may affect mechanical properties, may show reduced potential of delamination[1]. Medacta provides machined, non-irradiated polyethylene for all GMK tibial inserts.

READ MORE

ASYMMETRIC SHAPE
Asymmetric design of the tibial baseplate maximises bone coverage, thus assuring optimal load distribution and avoiding risk of overhanging. [14]


MIRROR POLISHED SURFACE
Both for mobile and fixed bearing, the internal surface of the tibial baseplate is mirror polished, minimising the risk of backside wear. [15]

Cementless femoral components are made of Cobalt Chrome alloy (CoCrMo, ISO 5832-4) with a state-of-the-art double coating: plasma sprayed unalloyed titanium (ASTM F1580) plus hydroxyapatite (ASTM F1185). No additional screws are required. [16]

ADAPTING TO YOUR  OWN SURGICAL TECHNIQUE
Every surgeon is unique. The GMK instrumentation is specifically designed to provide flexible solutions according to every single surgeon’s preferences: accuracy, ease of use and reproducibility are the guidelines followed  for GMK instrumentation development.
The GMK Primary can be implanted following different surgical techniques, according to the surgeon’s philosophy:

  • Bone referencing
  • Ligament balance
  • iMNS Computer Assisted
  • MyKnee patient matched cutting blocks

 

Each surgical technique also provides various options, each one designed to fit every surgical scenario :

  • Standard or muscle sparing surgical approach
  • Intramedullary or extramedullary tibia options
  • Conventional ligament balance technique, based on LBS system or ligament tensor
  • Computer Assisted surgery, both referring to measured resections and ligament balance with the ligament  tensor
  • MyKnee patient matched cutting blocks: standard, minimally invasive and allowing intraoperative ligament balance

 

DESIGN RATIONALE
[1] Anderson MJ, Becker DL, Kieckbusch T. - Patellofemoral complications after posterior-stabilized total knee arthroplasty: a comparison of 2 different implant designs. - J Arthroplasty. 2002 Jun;17(4):422-6
[2] D'Lima DD, Chen PC, Kester MA, Colwell CW Jr. - Impact of patellofemoral design on patellofemoral forces and polyethylene stresses. - J Bone Joint Surg Am. 2003;85-A Suppl 4:85-93.
[3] Morra EA, Greenwald AS. - Patellofemoral replacement polymer stress during daily activities: a finite element study - J Bone Joint Surg Am. 2006 Dec;88 Suppl 4:213-6
[4] Sharma A, Komistek RD, Ranawat CS, Dennis DA, Mahfouz MR - In vivo contact pressures in total knee arthroplasty. - J Arthroplasty. 2007 Apr;22(3):404-16
[5] Baldwin JL, House CK. - Anatomic dimensions of the patella measured during total knee arthroplasty. - J Arthroplasty. 2005 Feb;20(2):250-7.
[6] Kulkarni SK, Freeman MA, Poal-Manresa JC, Asencio JI, Rodriguez JJ. - The patellofemoral joint in total knee arthroplasty: is the design of the trochlea the critical factor? - J Arthroplasty. 2000 Jun;15(4):424-9.
[7] Ranawatt et al, Design may be counterproductive for optimizing flexion after TKR – Clin Orthop Relat Res. 2003 Nov;(416):174-6
[8] Kim et al, Range of motion of standard and high-flexion posterior cruciate-retaining total knee prostheses a prospective randomized study. – J Bone Joint  Surg Am. 2009 Aug;91(8):1874-81
[9] Kondo et al. “Arthroscopy for evaluation of polyethylene wear after total knee arthroplasty”, J Orthop Sci, 13:433-437, 2008. Orthop Sci, 13:433-437, 2008
[10] White et al., “Effects of sterilization on wear in total knee arthroplasty”, Clin Orthop, 331:164-71, 1996.
[11] Ries M D, “Highly Cross-Linked Polyethylene. The Debate is Over-In Opposition”, The Journal of Arthroplasty, 20:59-62, 2005.
[12] Baker et al., “The effects of degree of Crosslinking on the fatigue crack initiation and propagation resistane of orthopedic-grade polyethylene”, J Biomed Mater Res A, 66(1):146-54, 2002.
[13] Muratoglu et al., “Unified wear model for highly crosslinked ultra-high molecular weight polyethylenes (UHMWPE)”, Biomaterials, 20:1463-70, 1999.
[14] Westrich, Insall, Resection specimen analysis of proximal tibial anatomy based on 100 total knee arthroplasty specimens – J Arth, 1995  Feb;(1);47-51
[15] Engh et al, In vivo deterioration of tibial baseplate locking mechanisms in contemporary modular total knee components. – JBJS Am. 2001 Nov; 83-A(11); 1660-5
[16] Onsten et alt. Hydroxypatite augmentation of the porous coating improves fixation of tibial components, J Bone Joint Surg [Br] 1998;80-B:417-25.
[17] Polyethylene in TKA: Do we really need cross-linked polyethylene?, MORE Journal Vol. 1 May 2011
[18] No differences in human knee morphometry and gender-specific clinical outcomes: a literature review, MORE Journal Vol. 1 May 2011


CLINICAL FOLLOW UP
[19] International Evaluation Group , GMK Primary   1 year clinical follow up – study report , MORE Journal Vol. 1 May 2011
[20] Prim Dr W Anderl, Dr S Dittrich, Mag B Laky, PhD, Dr P Viè, GMK Primary 3 year clinical follow up – study report
[21] Dr P Lambert, Dr V Leon, Dr R Mendelin, Dr E Rinciari, Mechanical Axis Alignment After Total Knee Replacement Performed Through A Navigation System (iMNS) – study report, MORE Journal Vol. 1 May 2011

SINERGY
[22] MyKnee Publication Review MORE Journal Vol. 2 Supplement  June 2012
[23] Schroer et al. Mini-subvastus approach for total knee arthroplasty. J of Arthroplasty. 2008 Jan; 23(1): 19-25.
[24] McAllister et al. of minimally invasive surgical techniques on early range of motion after primary totalMcAllister et al. The impact of minimally invasive surgical techniques on early range of motion after primary total knee arthroplasty. J of Arthroplasty. 2008 Jan; 23(1): 10-18.
[25] Bonutti et al. Minimally invasive total knee arthroplasty. JBJS Am. 2004; 86: 26-32.
[26] King et al. Minimally invasive total knee arthroplasty compared with traditional total knee arthroplasty. Assessment of the learning curve and the postoperative recuperative period. JBJS Am. 2007 Jul; 89(7): 1497-503.
[27] Schroer et alt. Isokinetic Strength Testing of Minimally Invasive Total Knee Arthroplasty Recovery.  Journal of Arthroplasty, 2010 Feb; 25(2); 274-279

Medacta offers you the opportunity to experience an anatomic knee replacement system with the enhanced accuracy and proven efficiency of a system specifically designed for each individual patient: this is the synergy between GMK system and MyKnee.
MyKnee is a patient-specific cutting block, allowing the surgeon to realize his pre-operative 3D planning, based on CT or MRI images of the patient’s knee.

EXPERIENCE THE SYNERGY BETWEEN THE GMK SYSTEM AND MYKNEE

The MyKnee technology provides a unique set of potential benefits:

  • IT WORKS: proven accuracy and effectiveness of MyKnee. [22]
  • Real cutting blocks, not just pin positioners.
  • CT or MRI based.
  • Online interactive 3D planning.
  • Complete in-house technology ensuring the assistance of a personal MyKnee technician and only 3 weeks lead time.

 
Moreover, thanks to MyKnee the surgeon and the hospital can benefit of:

  • Potentially one extra case per surgery session.
  • Up to 66% reduction of time and cost in washing, assembling and sterilization procedure
M.O.R.E. EDUCATION KNEE PROGRAM

GMK AND MUSCLE SPARING KNEE SURGERY

In daily practice, every surgeon faces the increasing demand for excellent and reproducible knee arthroplasty outcomes.
Medacta is committed to developing high level technologies to improve the surgeon’s daily activities and maximize patient satisfaction.
Published papers show how muscle sparing knee Surgery (MSS) minimizes surgical trauma and reduce knee pain, providing earlier functional recovery:

  • Reduction of hospital stay (17% - 43% time less) [23,24]
  • Earlier functional recovery (110° ROM 6 weeks earlier) [24]
  • Shorter rehabilitation [25]
  • Less pain (16% less at discharge) [24]
  • Less medication needed (12% less at 2 weeks) [26]

 
Different MSS approaches are available for TKR., but only the mini subvastus provides a specific set of potential benefits:

  • No muscle cut
  • No patella eversion
  • No joint dislocation
  • Reduced scar
  • Excellent exposure
  • Versatile approach

 
Moreover, patients can benefits of mini-subvastus approach not only in the  short term:

At 1 year, the quadriceps strength of the mini-Subvastus TKA knee was equal to that of the uninvolved side, whereas MMP [the medial parapatellar] TKA was 24% weaker than the uninvolved side.” [27]
 

QUADRICEPS STRENTH COMPARED TO NON-OP LEG AT 1 YEAR


Adapted from Schroer et alt. [27]