Hospital Orthopedics Committee Information
NextStep Document Center
Here are download links to all NextStep Arthropedix documents.
NextStep Arthropedix LLC., Company Documents
Article, Journal of Arthroplasty, Influence of EBM Implant on Ingrowth and Strength
iNSitu Acetabular Cup Features
Additively Manufactured (3D Printed) Acetabular Cup
Above is a link to view an animal study from the Surgical and Orthopaedic Research Laboratories (University of New South Wales, Prince of Wales Clinical School, Sydney, Australia) using materials additively manufactured with electron beam technology (ARCAM AB, Molndal, Sweden). NextStep Arthropedix utilizes similar electron beam technology to additively manufacture the iNSitu™ acetabular cup. There are additional studies that replicate or compliment these results that can be sent by request.

Excerpt from Bertollo et al manuscript referenced above:

"The porous nature of the EBM (Electron Beam Melting) medium appears to allow bone integration in all planes compared with 2-dimensional planar ingrowth, as is the case for the Ti PS (titanium plasma spray) medium. This accounts for increased shear strength values in cortical implantation sites for EBM compared with Ti PS. Surface roughness of the EBM was also greater compared with the Ti PS, which may also contribute to superior fixation"¹.

The NextStep Arthropedix additively manufactured porous structure (PorosiTi™ Cancellous Metal Matrix) is directly built on the cup substrate (i.e. not an applied coating). The acetabular cup offers superior initial fixation due to the surface roughness and periodic fins located peripherally along the rim of the cup. The acetabular cup design also supports long-term fixation via bone ingrowth into the interconnected porous structure; roughness at the macro-, micro-, and nano- scale promotes osteoblast activity and long-term stability. Refer to the iNSitu Technology Summary for a rendering of the PorosiTi Cancellous Metal Matrix.

1 Excerpt on page 1434 of Bertollo N. et al., “Influence of Electron Beam Melting Manufactured Implants on Ingrowth and Shear Strength in an Ovine Model”. J Arthroplasty. 2012; 27(8):1429-36.

NextStep Alpha UHMWPE Slides
Vitamin-E Blended Cross-Linked UHMWPE (α poly™) Acetabular Liner
NextStep’s α-poly™ is a fourth generation highly cross-linked UHMWPE material that demonstrates superior wear resistance to second and third generation materials in both standard and highly abrasive conditions². NextStep’s α-poly™ also demonstrates state-of-the-art oxidation resistance, as shown by a study performed by Cambridge Polymer Group, a leading authority on UHMWPE³.

2 Data on file at NextStep Arthropedix
3 Data on file at NextStep Arthropedix

iNSitu Stem Size Specifications
iNSitu Stem Features
iNSitu™ Femoral Stem
NextStep developed the iNSitu™ femoral stem by utilizing anthropometric data to provide an optimal fit in wide range of patient morphologies and demographics. Main features that support the optimal fit are a 130° neck angle for both standard and lateral stems, progressive lateralization of head centers with increasing stem size, a reduced lateral shoulder design, and an anatomic contour that properly mates with the lateral femoral cortices. The iNSitu™ femoral stem also promotes osseointegration with an asymmetric sintered bead coating on the proximal portion of the stem.

NextStep incorporated intelligent engineering principles to mitigate risks associated fretting and corrosion (e.g. “trunnionosis”) at the head/neck junction. The iNSitu™ femoral stem taper features flatness, circularity, roughness, and length tolerances that are unrivaled by other OEMs.

iNSitu Sizing and Compatibility Chart
iNSitu Femoral Heads Features
Femoral Heads
By utilizing ultra-low wearing materials and intelligent design, NextStep is able to leverage large head sizes in relatively small cups without sacrificing polyethylene thickness in the load zones (e.g. 36 mm head in a 50 mm cup, 40 mm head in a 54 mm cup). Larger heads in smaller cups, coupled with excellent wear properties, allows the surgeon to increase stability as needed. NextStep manufactures femoral heads from both ceramic and CoCr alloy and achieves the excellent wear properties through strict tolerances and unique polishing processes.

section image
FDA required hip wear studies
There was no measurable wear with the NextStep Vitamin E α-poly™ after 5 million cycles.
FDA adverse conditions wear study of 3 million cycles
In order to simulate the worst possible wear conditions, the femoral heads were scratched and roughened. The NextStep α-poly™ lost 15% of the material while the predicate industry leading competitor wore through completely.
NextStep Instruments
NextStep designs instruments with every stakeholder in mind – simplicity, ergonomics, rapid set turnover, and ease of use are recurring themes in all instrument trays. The instruments can accommodate all surgical approaches, including posterior, anterolateral, and direct anterior. Should the surgeon elect the direct anterior approach, three trays are required, but all other surgical approaches can be performed with only two trays. The NextStep iNSitu Total Hip System is ideal for both inpatient and outpatient settings.
iNSitu Instruments
Reducing Annual Surgical Costs