The German Endoprosthesis Register (EPRD) has been reporting increases in short stem care for years. Most recently, the proportion of short stems was 13.3%. Nevertheless, the short stem often falls short, according to the opening statement by Prof. Dr. Stefan Budde, Bielefeld, and Dr. Sebastian Meller, Berlin. The two scientific directors of the EKB Short Stem Seminar and the invited experts are therefore united in the goal of advancing the topic of short stems across manufacturers and implants.

PD Dr. Marco Ezechieli, Salzkotten, began by recalling the importance of anatomical reconstruction for younger patients. The anterior offset has often been neglected in the past. In a CT-based cadaver study it was shown that stems that partially preserved the femoral neck reconstructed the center of rotation better compared to conventional straight stems.[1] There are also advantages for soft tissue reconstruction and muscle tension when using a short stem. Dr. Ezechieli advocated greater consideration of short stems in the care concept for younger patients in order to reduce the revision rate of this clientele in the future.

PD Dr. Peter Savov, Oldenburg, presented the still unpublished results of a study: The working group had analyzed around 2,300 hip X-ray images. The result is a detailed classification that – based on the CPAK classification in knee arthroplasty – was named CPAH (Coronal Plane Alignment of the Hip). The CPAH classification takes three essential parameters into account: the metadiaphyseal configuration based on the Dorr classification, the consideration of the CCD angle, and the definition of the lateral offset.

In addition, the treatment with different types of stems (short stem, anatomical stem or straight stem) was planned virtually on a random basis. The goal: The best reconstruction of the patient’s anatomy. The majority of the classified combinations can be easily supplied with a short stem. But: Where are the limits of the short stem? Finding out this is the task of the near future, stated PD Dr. Savov.

Dr. Sebastian Meller, Berlin, presented the first data from a prospective, single-center randomized study that has not yet been published. The aim of the study was to find out whether the reconstruction of the hip joint anatomy can be reconstructed more accurately and minimally invasively by using short stems (A2® short stem) compared to straight stems (SL-Plus MIA stem). For this purpose, the study design envisaged the recording of radiological (rotational MRI, X-ray), clinical and laboratory parameters.

After the 6-month follow-up, the results for the 40 patients showed very good clinical and radiological results with short and straight stems as well as very high patient satisfaction. When comparing short and straight stems, initial trends can be seen: The implantation of a short stem tends to lead to less gluteal muscle and tendon damage. Radiologically, an increased global offset was observed in the short-stem group. In addition, the stem antetorsion could be better reconstructed in the short stem group compared to the straight stem, and the influence on the leg axis was also more natural. In a second step, further radiological evaluation and laboratory chemical evaluation of the examined cohort is now pending.

Prof. Dr. Karl-Philipp Kutzner, Mainz, reported on preclinical investigations for a cemented short stem. The starting point was the realization that bone quality rather than age was a contraindication to cement-free short stem restorations.[2],[3] With a view to demographic development, good concepts are now needed, stated Prof. Kutzner. This includes the cemented short stem. Several experimental cadaver studies have therefore dealt with the primary stability of a cemented short stem, including reversible micro-movements and irreversible migration. On the one hand, the focus was on the cementing technology by comparing the undersized standard with the line-to-line cementing technology. Both techniques showed comparable results, so that line-to-line cementation, which is more advantageous for the short stem, could be pursued.[4],[5] On the other hand, the stem design itself was considered and a cemented short stem was compared with a cemented straight stem. No significant differences in micro-movements, migration and breaking load could be determined here.[6] Prof. Kutzner was convinced that a cemented short stem would be an important addition to the spectrum of care and that short-stem care as a whole could become the future standard.

Dr. Ahmed Yaseen, Innsbruck, represented Dr. Bertram Regenbrecht, Lilienthal, presented the first results of a multicenter user observation study on the cemented A2® short stem. The average age of the patients (n = 121; 90 f, 31 m) was 77.8 ± 4.7 years. The stem design produced consistently inconspicuous and good results. The clinical scores (HHS and FJS) showed very encouraging results. The average FJS at 1-year follow-up was comparable to the results of non-implant recipients. As expected, the patient clientele presented challenges: Due to the old age of the patients, an increased drop-out rate was observed during follow-up. Complications and abnormalities also arose due to the age and comorbidities of the study cohort. In addition, a revision was documented that was carried out after inadequate cementation and the resulting early postoperative sintering of the short stem. The survival rate of the cemented A2® short stem was 99.17% after one year.

Prof. Dr. Arnd Steinbrück, Augsburg, spoke about the EPRD registry data for the short stem. In principle, the short stems showed good results, but the still young registry does not yet have any long-term results. And there is still no sufficient data for older patients either. In addition to patient selection, the experience of the surgeons influences the results. In two thirds of the clinics that report to the EPRD, only 5% of the short stems are used, while 50 clinics in Germany implant over 50% of the short stems. According to Prof. Steinbrück, it is important that training is used to minimize the learning curve and ensure that the results remain as good.

The prejudice that the revision record of the short stem is only so good because it is primarily implanted in young and healthy patients and by experts has been scientifically verified. If the registry data is statistically adjusted for influencing factors such as patient age and gender, the short stem tends to perform better than the normal stem, although this is not statistically significant.[7] What is interesting, however, is the infection rate, which is significantly lower with the short stems 3 years after the procedure than with the standard stems. The hypothesis: The lower soft tissue trauma could be responsible for this effect.

Prof. Dr. Stefan Budde, Bielefeld, finally traced the history of the short stem. Since the beginning with the Mayo prosthesis in the mid-1980s, many short-stem implants with different philosophies have come onto the market and disappeared again. For the “short-stem idealists”, the calcareous-guided short stem today offer a solution for both the proximal introduction of force and for primary stability. In view of the additional advantages that were brought together in the presentations, the short stem could be a “game changer,” according to Prof. Budde. The short stem has the potential to become the new standard.

[1] Ezechieli, M. et al. (2022). Archives of Orthopedic and Trauma Surgery. 142. 1-12. DOI: 10.1007/s00402-021-03957-2.

[2] Kutzner KP. Arch Orthop Trauma Surg. 2023 Feb;143(2):1049-1059. DOI: 10.1007/s00402-022-04354-z.

[3] Gkagkalis G et al. BMC Geriatrics 2019 Apr 17;19(1):112. DOI: 10.1186/s12877-019-1123-1.

[4] Kutzner KP et al. Clin Biomech. 2018 Feb;52:86-94. DOI: 10.1016/j.clinbiomech.2018.01.004.

[5] Azari F et al. J Orthop Res. 2021 Aug;39(8):1681-1690. DOI: 10.1002/jor.24887.

[6] Freitag T et al. Arch Orthop Trauma Surg. 2021 Oct;141(10):1797-1806. DOI: 10.1007/s00402-021-03843-x.

[7] Steinbrück, A et al. Orthopedist 50,296–305 (2021). https://doi.org/10.1007/s00132-021-04083-y