Practical experience with optimys and Delta TT

The RM Pressfit vitamys cup is a perfect match for the optimys short stem.

Both are very well suited for primary indications. However, in revision cases the Delta TT cup may be a preferred partner for the optimys short stem.

Dr Philipp Rehbein, Wiesbaden, reports on this and his practical experience in an interview.

Dr Rehbein, you have plenty of experience in using optimys with the RM Pressfit vitamys cup and also the Delta TT cup. In which clinical settings do you use them?

The optimys short stem and the vitamys cup were originally developed for primary indications. This is also where I see the main area of application – the two elements fit together perfectly. By now, we have over 15 years of experience with them.

For revisions, we often use the Delta cup, if the indications are suitable, e.g., revisions of cap prostheses. However, in special cases for the primary treatment of patients, we are using from time to time as well the combination of Delta cup with optimys short stem, if there are peculiarities in the pelvic area, i.e., in the acetabulum. Such cases include patients with congenital dysplasia or a history of post-traumatic changes or pelvic rearrangement, I am fully aware that this represents an off-label use. Nevertheless, in these specific situations, I consider it to be the best available option to meet the needs of my patients.

Let us take a look at the individual systems. What was the original reason for developing the calcar-guided stem design?

The development of a short stem has always been an interesting philosophy.

The first such prostheses were the Mayo short stem and the C.F.P. hip prosthesis in the 1980s to 1990s. However, these were custom-made designs, and experience was limited to a small number of cases.

The short stem is so exciting because of its biochemical parameters. The leg length and the femoral offset – the lateral distance from the femur to the pelvis – can be precisely regulated, and the centre of rotation restored. In this respect, short stems are superior to “standard” long-stem or straight-stem implants.

In the early 2000s, short stems entered the market, however, they still had many “side effects”. Material breakage would occur. Sometimes the awkward design caused periprosthetic fractures during surgery, or the instruments were unsuitable. This prompted us to introduce our own ideas into the development of a short-stem implant.

The result is optimys with the calcar-guided stem design. The conical stem design has the ability to adapt well to the osseous anatomy. The risk of periprosthetic fracture has been significantly reduced. We can now say that this short-stem prosthesis has achieved all our goals. Of course, the material and the instruments also make a big difference.

What is so special about the optimys and RM Pressfit vitamys material and instruments?

The titanium implants, stem, and cup offer good osseointegration and promote long-term bone remodelling.

However, the role of the instruments is also very important and often underestimated. In this case, the instruments have been developed specifically to insert the prostheses according to the planning, e.g., also for obese people. Thanks to the well-designed instruments, tissue-sparing surgical techniques are possible. The implant bed can be prepared easily, and the prosthesis inserted safely. This has become very important nowadays, simply because of the fast-track concepts.

Patients need to get back on their feet quickly. With both implants, we are seeing excellent results in the registries.

Let us move on to the Delta TT cup: How long have you been using it, and what is the clinical added value of this cup for your patients?

I first heard about the Delta TT cup at the EFORT Congress in Copenhagen and immediately purchased it in 2011 as a cup for revision cases. It has good instruments and an extensive size portfolio. It also offers the option of fixing screws, inserting titanium augments, and using liners to fine-tune the sliding pairing. The trial cups are also very advantageous. If they fit well, the surgeon knows that the original will also fit very well.

These special properties of the Delta cup can be very helpful in primary indications with peculiarities of the acetabulum. This is why we now regularly use this implant in cases of severe dysplasia or abraded bone substance in the acetabulum. Here, titanium augments are used, for which we previously needed bone grafts.

This technique works so well that we discontinued the bone bank around eight years ago. The Delta cup with a “dual mobility” option is also suitable for patients with an increased risk of dislocation, for example due to neurological disorders, poor compliance, or muscle deficits.

In short: Whenever additional screw fixation is necessitated by special circumstances, the Delta cup comes into play.

The Trabecular Titanium (TT) material of the Delta cup has been tried and tested for almost 20 years. What experience have you had with it?

Many implants sport a hydroxyl apatite (HA) coating.

The Delta cups have no coating, but consist entirely of Trabecular Titanium. The material is extremely osteoinductive. In addition, titanium has a modulus of elasticity that is very similar to that of human bone, not rigid like concrete, but elastic. This enables a harmonious, form-fitting adaptation of the implant to the bone. Titanium promotes bony integration and bone remodelling, and prevents stress shielding.

What advice do you have for surgeons who are planning to use the optimys short-stem, RM Pressfit vitamys or Delta TT but still have questions or doubts?

As mentioned at the beginning, the RM Pressfit vitamys cup is a perfect match for the optimys short stem and very suitable for many primary indications. The advantage of the Delta cup is that the surgical concept does not have to be changed for challenging restorations on the acetabulum. The short stem can remain, and only the cup is replaced.

Thanks to the good instrumentation for all implants, the implantation is straightforward and easy to learn despite the complexity of the surgery.

However, I would advise anyone interested to visit an expert who uses a large number of these implants. Practice will show you all the pitfalls, and you can learn a lot from it.