EVANS and COTTON wedges
In words of Leonardo DaVinci, the foot “is a masterpiece of engineering and a work of art”.
In words of Leonardo DaVinci, the foot “is a masterpiece of engineering and a work of art”, but, like any structure subjected to repeated mechanical loads, it can end up having problems.
The around 8,000 steps a day on average that it supports makes it prone over the years to suffer pathologies. It is estimated that more than 80% of the population will suffer health problems of varying severity in the feet at some point in their life.
Among the multiple pathologies that occur, flatfoot deformity (valgus flatfoot of the adult) is one of the most relevant and complex, and continuously changing and innovating.
Surgical treatment of valgus flatfoot rarely requires a single isolated procedure, but rather a selection of techniques. Among these techniques, Evans and Cotton osteotomies occupy an important place.
OsteoSinter® EVANS and COTTON wedges: description and indications
OsteoSinter® EVANS and COTTON wedges are titanium implants used to correct adult-acquired flatfoot deformities, specifically for stage II posterior tibial tendon dysfunction (according to Bluman classification).
The wedges are intended to be used as an implant specifically designed for Evans procedures (for lateral foot column lengthening) or Cotton (improve the inclination of the first radius and avoid overloading the external column). These wedges allow very precise control of the amount of lengthening or declination of osteotomies.
The material of these wedges is the OsteoSinter® porous titanium, manufactured using the powder metallurgy technology. The material is pure biomedical grade titanium, and has a porosity of 62-66%. The shape of the porosity mimics the trabecular bone, thereby inducing a great osteointegration of the surrounding bones through the interconnected porosity: 57% of bone colonization is achieved after just 4 weeks of implantation.
The porous structure of the material and the relief shape of the surfaces provide a high primary fixation to the bone.
OsteoSinter® EVANS and COTTON wedges are offered in 15 sizes which, in comparison to unconfigured allografts, reduce the surgery time and remove its planning cost.
The OsteoSinter® EVANS and COTTON wedges are placed using a single-use instrument kit, which include a tweezer, an impactor and a set of sizers used to choose the right size for each patient.
AFTER 4 WEEKS
The result is a very fast osteointegration,reaching 57% of bone colonization.
OsteoSinter® EVANS and COTTON wedges are intended to be used for internal bone fixation for foot osteotomies such as:
• Opening wedge osteotomies of the bones of the foot (including addition osteotomies for Hallux Valgus).
• Opening wedge of medial cuneiform or Cotton osteotomies.
• Lateral column lengthening (Evans lengthening osteotomy or calcaneal Z osteotomy).
• Metatarsal/cuneiform arthrodesis.
OsteoSinter® EVANS and COTTON wedges are intended to be used with ancillary fixations.
Single-use instruments kit
OsteoSinter® EVANS and COTTON wedges are delivered with a single-use and recyclable surgical instrument kit, made of polyamide grade 12, which contributes to a precise implantation of the product.
This kit is used in conjunction with the typical instrumentation of a standard orthopedic surgery for both Evans and Cotton osteotomies.
The single-use OsteoSinter® EVANS and COTTON instrument kits include a set of sizers (one for each size and type of wedge), a tweezer to hold and insert the wedge, and an impactor to seat the implant in its suitable position by tapping gently with a standard hammer (not supplied in the kit).
Single-use OsteoSinter® EVANS instruments
Single-use OsteoSinter® COTTON instruments
OsteoSinter® EVANS wedges9 sizes (3 dimensions with different surfaces and 3 thicknesses for each one)
|Footprintoptions||Name||Width(mm) [W]||Length(mm) [L]||Height(mm) [H]||Heightoptions||Reference|
|18x18 mm||OsteoSinter® EVANS wedge18W x 18L x 8H||18||18||8||P00200|
|OsteoSinter® EVANS wedge18W x 18L x 10H||18||18||10||P00201|
|OsteoSinter® EVANS wedge18W x 18L x 12H||18||18||12||P00202|
|20x20 mm||OsteoSinter® EVANS wedge20W x 20L x 8H||20||20||8||P00203|
|OsteoSinter® EVANS wedge20W x 20L x 10H||20||20||10||P00204|
|OsteoSinter® EVANS wedge20W x 20L x 12H||20||20||12||P00205|
|22x22 mm||OsteoSinter® EVANS wedge22W x 22L x 8H||22||22||8||P00206|
|OsteoSinter® EVANS wedge22W x 22L x 10H||22||22||10||P00207|
|OsteoSinter® EVANS wedge22W x 22L x 12H||22||22||12||P00208|
OsteoSinter® COTTON wedges6 sizes (2 dimensions with different surfaces and 3 thicknesses for each one)
|Footprintoptions||Name||Length(mm) [L]||Height(mm) [H]||Heightoptions||Reference|
|15 mm||OsteoSinter® COTTON wedge15L x 4.5H||15||4.5||P00300|
|OsteoSinter® COTTON wedge15L x 5.5H||15||5.5||P00301|
|OsteoSinter® COTTON wedge15L x 6.5H||15||6.5||P00302|
|20 mm||OsteoSinter® COTTON wedge20L x 4.5H||20||4.5||P00303|
|OsteoSinter® COTTON wedge20L x 5.5H||20||5.5||P00304|
|OsteoSinter® COTTON wedge20L x 6.5H||20||6.5||P00305|
The OsteoSinter® material
Ultraporous pure titanium
The OsteoSinter® material is pure titanium grade 2 according to ASTM F67, biocompatible, according to ISO 10993:2018, and manufactured by means of Power Metallurgy technology.
A special design of the manufacturing process allows to obtain a product of high interconnected porosity (62-66% in volume), an with great stochasticity of pores distribution.
The result is a material that mimics the trabecular structure of human bone and its mechanical properties.
The manufacturing process of the OsteoSinter® material guarantees a high homogeneity of porosity and material characteristics piece by piece in large serial production.
The high porosiy of the OsteoSinter® material and its special pore size distribution favor the osteointegration of the surrounding bones through the interconnected porosity.
The performed studies indicate that 57% of bone colonization is achieved in just 4 weeks after its implantation.
AFTER 4 WEEKS
The result is a very fast osteointegration, reaching 57% of bone colonization.
The OsteoSinter® material exhibits a mechanical behavior very similar to the human bone, both in elastic modulus as in compression and fatigue resistance.
It also has a great wear resistance (expressed as abrasion in the next table), and a high friction coefficient that ensures high primary fixation to the bone.
|Elastic modulus (GPa)||2,5-3,5||2,0||3,2||1,6||2,7||3,2|
|Compressive yield strength (MPa)||40-45||10-30||76||N.D.||86||N.D.|
|Compressive fatigue limit||5 M cycles at > 18 MPawithout failure||N.D.||N.D.||N.D.||N.D.||10 M cycles at > 10 MPawithout failure|
|Abrasion (% of weight loss at 1.000 N)||0,34||N.D.||N.D.||N.D.||13,0||0,20|
 ADVANCE ®BIOFOAM TM Cancellous Titanium_tibial implants_Technical Monograph.
 Bobyn, J. D., Stackpool, G. J., Hacking, S. A., Tanzer, M., & Krygier, J. J. (1999). Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial. The Journal of Bone and Joint Surgery. British Volume, 81-B(5), 907–914.
 Shirazi-Adl A1, Dammak M, Paiement G. Experimental determination of friction characteristics at the trabecular bone/porous-coated metal interface in cementless implants. J Biomed Mater Res. 1993 Feb;27(2):167-75.
 Trabecular MetalTM Material Product Brochure.
 Coefficient of Friction for Porous Metal Structures Against Cortical Bone Gupta G McLain * Biomet Inc 56 E Bell Dr., Warsaw, IN 465882. ®2013 Society For Biomaterials.
 Mechanical Characteristics of OsteoSync TM Ti: 2007-001-41 REV A.
BENEFITS IN HEALTHCARE COSTS
Porous structure that mimics the bone morphology:
High primary fixation
Great capacity of primary fixation
to the bone
Variety of sizes to cover
the whole anatomical spectrum
Simple instruments that minimize
the healthcare costs
Porous Titanium Wedges
Moore, S. H., Carstensen, S. E., Burrus, M. T., Cooper, T., Park, J. S., & Perumal, V. (2018). Porous Titanium Wedges in Lateral Column Lengthening for Adult-Acquired Flatfoot Deformity. Foot & Ankle Specialist, 11(4), 347–356.
Porous Titanium Wedges
Gross, C. E., Huh, J., Gray, J., Demetracopoulos, C., & Nunley, J. A. (2015). Radiographic Outcomes Following Lateral Column Lengthening With a Porous Titanium Wedge. Foot & Ankle International, 36(8), 953–960.
Matthews, Michael et al. (2018). Long-Term Outcomes of Corrective Osteotomies Using Porous Titanium Wedges for Flexible Flatfoot Deformity Correction. The Journal of Foot and Ankle Surgery, Volume 57, Issue 5, 924 – 930.
Porous Titanium Wedges
Andrew B. Bridgforth, M. Tyrrell Burrus, Joseph S. Park (2016). Varus Deformity of the Distal Tibia From Physeal Growth Arrest Treated Using a Titanium Metal Porous Wedge. Volume: 9 issue: 5, page(s): 452-456.
titanium metal foam wedge implant
Tucker D (2010)..Lateral column lengthening in adult flatfoot surgery using a titanium metal foam wedge implant. Tech and Foot Ankle. (9), 205-210.
Wedge Osteotomy for Correction
Giovanni R. et al.(2019).Medial Cuneiform Opening Wedge Osteotomy for Correction of Flexible Flatfoot Deformity: Trabecular Titanium vs. Bone Allograft Wedges. BioMed Research International. Volume 2019, 7 pages.
Porous Titanium Wedges
Carstensen S, Moore S, Park JD, Truitt M, Cooper M, Perumal.(2018)..Porous Titanium Wedges are an Alternative in Lateral Column Lengthening for Adult Acquired Flatfoot Deformity. AOFAS Annual Meeting. Foot & Ankle Orthopaedics, 3(3)
Gordon S, Clifton T.(2018)..Minimally Invasive Opening Wedge Calcaneal Osteotomy Usinga Titanium Structural Fusion device. EC Orthopaedics 9.9. 626-631.