Interview with
Prof. Dr Alexander Berth

«The first clinical findings with the cementless glenoid are very promising»

After two successful years of use in a multi-centre study, the new TSA implant «Affinis Glenoid vitamys uncemented» is now ready for the market. We talked to the lead investigator, Prof. Alexander Berth, about his clinical experience with this implant so far. 

Prof. Dr Alexander Berth

is a specialist in orthopaedics and trauma surgery, rheumatology, chiropractic medicine and sports medicine, and works as a senior physician at the orthopaedic department of Otto von Guericke University in Magdeburg. In this function, he is responsible for the field of shoulder surgery. Prof. Berth is a member of several orthopaedic societies.

He has gained extensive experience in the field of modern arthroscopic and open shoulder surgery. His present scientific focus is on the further development of current shoulder prosthesis systems. 


Dear Prof. Berth: Since its first application in 2004, the stemless humeral head has set new standards in shoulder arthroplasty. Now there are signs that cementless glenoid replacement is experiencing a renaissance in clinical use. How important is this in practice?

In anatomical TSA, cemented glenoid replacement is currently considered the gold standard. Nevertheless, aseptic loosening of this implant in the long run represents one of the most frequent complications necessitating revision. Therefore, further development of the glenoid replacement is a crucial step to address this issue. Implant optimisation in terms of design, fixation and improved material properties justifies the assumption that new cementless glenoid components may represent a possible approach to a solution here.

What are the potential advantages of cementless glenoids in this respect?
The various manufacturers of this new generation of cementless implants are pursuing different strategies to improve the service life of glenoid components.  
With regard to the «Affinis Glenoid vitamys uncemented» by Mathys, here several crucial design aspects are taken into account that make it an innovative implant.  

This cementless glenoid component is a so-called monobloc implant. This design principle has already proven its worth in the acetabular components used in hip arthroplasty, such as in the use of the RM cup by Mathys. The monobloc glenoid consists of a full-polyethylene (PE) body and, unlike modular systems, is not made up of subcomponents such as baseplate, screws and inlay. Thus, undesirable interactions that occur at interfaces between the individual components of the overall implant due to the differing material properties and give rise to processes such as abrasion, corrosion and fretting can be reduced or avoided, respectively.

The PE of the «Affinis Glenoid vitamys uncemented» moreover has specific characteristics that additionally suggest durability of the primary material properties and hence a long service life of the implant. A highly cross-linked PE (HXLPE) is used, which is mixed with vitamin E, an antioxidant («vitamys» by Mathys). This additive results in significant material advantages. Several studies have shown that this vitamin E-enriched HXLPE has higher resistance to oxidation, ageing and abrasion than other PE types have.

In addition, this HXLPE also has improved mechanical properties. In particular, its isoelasticity should be mentioned here: The modulus of elasticity of this HXLPE is comparable to that of cancellous human bone. Thus, virtually physiological force transmission from the implant into the periprosthetic bone bed may be assumed. This property can help prevent «stress shielding», which is a major cause of aseptic implant loosening. This pathophysiological stress pattern of the periprosthetic bone is detectable with cementless implants made of titanium, which is comparatively rigid, and can lead to premature implant failure due to reactive bone resorption.

The primary stability of the «Affinis Glenoid vitamys uncemented» is based on its press-fit anchorage in a suitable glenoid bone bed. However, for ensuring sufficient secondary stability as well, osteointegration of the implant into the surrounding bone tissue is crucial. This process is supported in the case of the «Affinis Glenoid vitamys uncemented» by the rear surface and anchoring pins being provided with a layer of pure titanium particles and having a coarsely porous surface structure to promote formation of the bond between bone tissue and implant.

«The new cementless glenoid demands precision during implantation.»

Do you see clinical challenges for «Affinis Glenoid vitamys uncemented» as well?  

Yes, I do. The goal is to use this new implant to build on the very good clinical results achieved with use of cemented glenoid components. At the same time, this should address the problem of aseptic loosening. Both objectives are linked to consideration of certain prerequisites upon determination of the indication for this component. Here I would particularly emphasise the aspect of preoperative glenoid morphology. This patient-specific parameter is an important factor for the clinical outcome after TSA, and for the service life of the implanted glenoid components. Since the «Affinis Glenoid vitamys uncemented» is an implant for which medium and long-term results are still outstanding, I am currently limiting myself to centred glenoid types A and decentred B1 cups of the Bercik–Walch classification1 when determining indications. The bone quality of the glenoid is also an important factor. In this respect, I would also have concerns if this new cementless glenoid component were to be used indiscriminately at the present time in secondary indications for anatomical TSA, such as rheumatoid arthritis or metabolic arthropathies. Preoperative parameters such as the degree of glenoid retroversion and the extent of humeral head subluxation are also important in determining the indication. The correction of a significantly increased retroversion angle during glenoid preparation for implant reception that is necessary here might be associated with a weakening of the periprosthetic bone bed. Therefore, in cases where an anatomical endoprosthetic restoration is still indicated despite pre-existing significantly increased glenoid retroversion, I tend to implant rather a cemented HXLPE glenoid with two pins.  

In addition to these patient-specific factors, however, precise performance of the surgical technique is also crucial for this cementless implant to prove its worth in clinical use. For the «Affinis Glenoid vitamys uncemented», there are implant-specific features whose knowledge and consideration may affect the functional and radiological result. Special attention should be paid to preparation of the glenoid articular surface. Here, in addition to protection of the subchondral bone zone, care must be taken at the same time during reaming to ensure complete contact of the coated rear surface when implanting the original component so as to ensure stability of the implant. Careful preparation of the drilled holes to accommodate the two pins of this implant is also important for this.

You are the lead investigator of a prospective study on the cementless glenoid. What insights have you gained so far?

The first implantation of the «Affinis Glenoid vitamys uncemented» in January 2020 was the start of this multicentre study, whose central objective is to prospectively evaluate the clinical and radiological results of using this new cementless glenoid component in intermediate stages over a long-term course. All of the 75 patients who were included into this prospective study and underwent endoprosthetic treatment at the five German shoulder surgery centres participating in the study showed promising clinical and radiological short-term results. No complications have occurred so far either. Thus the assumption appears justified that use of the new «Affinis Glenoid vitamys uncemented» will produce very good results in the medium and long-term follow-up period, with regard to the functional and radiological parameters as well as to complication rates and service life.

«Affinis Glenoid vitamys uncemented is an option for many patients.»

Is the cementless glenoid suitable for all patients who need a new shoulder joint?

Such a statement cannot be derived from the data currently available on this new implant yet. For the reasons mentioned above, we as investigators deliberately took care to precisely define the inclusion criteria for the first clinical application of the «Affinis Glenoid vitamys uncemented» in the planning of the study. At present, I consider it advisable to stick to this selected indication range also outside of use in the course of clinical trials. If the very good short-term results shown so far are confirmed as stable and reliable in routine clinical use on a broader basis, there is definitely the prospect of expanding the current range of indications.

Are there any special caveats for patients after implantation of the new cementless glenoid replacement?

If the instructions on indication and surgical technique are observed, high primary stability can be assumed with the «Affinis Glenoid vitamys uncemented». In this respect, I would not see any implant-specific difference in terms of load-bearing capacity and postoperative follow-up in relation to the previously established treatment schemes for anatomical TSA using cemented glenoid components. Hence, the patients have no disadvantages in terms of rehabilitation. According to previous experience, there are no differences with regard to the general recommendations concerning the later load-bearing capacity and sporting ability after implantation of shoulder prostheses either.

«Recently, I have ceased fitting cemented glenoids in suitable indications.»

You have two years of experience with the new glenoid replacement. Do you already have new requests for the development department?

With regard to the «Affinis Glenoid vitamys uncemented», our study group has not yet been able to discover any design weaknesses. The clinical as well as the radiological results look very good. This implant has not caused problems in any of the patients so far. The most important task at present is to record and carefully evaluate the data from the further course. Moreover, I consider the further development of TSA significant, in particular for the area of increasing revision surgeries. In this context, addressing glenoid defects adequately is a particular challenge. In addition to surgical expertise, case-specific solutions are increasingly required. This clinical area still holds great potential for innovation with regard to computer-based navigation and the manufacture of patient-specific revision components.

Thank you very much for this interview, Prof. Berth! 


1 Bercik MJ, Kruse K 2nd, Yalizis M, Gauci MO, Chaoui J, Walch G. A modification to the Walch classification of the glenoid in primary glenohumeral osteoarthritis using three-dimensional imaging. J Shoulder Elbow Surg. 2016 Oct;25(10):1601-6.


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