Classic stems versus short hip femoral stems in primary hip replacement - radiological analysis of 360 cases, five year follow-up

Objectives The aim of the study was to analyse stability after the implantation of cementless classic femoral stems in comparison to short femoral stems.

It’s important to know which of the stems provides the best stability and most favourable early and long-term postoperative results.

Methods In a five year follow-up comparative study we have analysed the data of 360 patients (198 F/162 M), 60 patients for each stem:

Abb 1

• 180 patients with classic femoral stems (Summit, Synergy, Accolade - Fig.1a), the average age 68.9 years old (ranging 43-91).

• 180 patients with short femoral stems (Minihip, SMF, Furlong Evolution Fig.1b), the average age 66.9 years old (ranging 37-84).

• 162 patients (90 %) in the classic stem group have been operated on with postero-lateral and 18 patients (10 %) with

antero-lateral approach. In the short stem group 149 patients (82.8 %) with Direct Anterior Approach(DAA), 28 patients (15.5 %) with postero-lateral and 3 patients (1.7 %) with antero-lateral approach.

The statistical outcomes were analysed on SPSS program.

Results and Conclusion Evaluation of the radiographical outcomes:

• Subsidence (vertical stem migration) > 2 mm: 16 patients (4.4 %) in the classic stem group, 72 patients (20 %) in the short stem group, result P = 0.011 is statistically significant to the disadvantage of the short stems (Tab.1, Fig.2).

• Angular stem migration in frontal plane (varus/valgus) > 2°: no patients in the classic stem group, 61 patients (16.9 %) in the short stem group, result P = 0.0084 is statistically significant to the disadvantage of the short stems (Tab.2, Fig.3).

• Axial (lateral) angular stem migration was not statistically significant.

• Distal femur cortical hypertrophy with thigh pain (stress shielding): all patients in the short stem grup 26 (7.2 %), P = 0.1369, difference was not statistically significant (Fig. 3, 4).

• Periprosthetic fractures: 2 cases (0.55 %) in the classic stem group, 26 cases (7.2 %) in the short stem group.

• Malalignment: 5 cases (1.39 %) in the short stem group (all SMF)(Fig.4).

Conclusions

• Long-term durability of the hip replacement with proper implantation is an important consideration.

• In our study, short stems are less stable in comparison to classic stems. Differences are statistically significant: susbsidence P = 0.011, angular varus/valgus stem migration P = 0.0084.

• The SMF stem is less stable in comparison to other stems - revision hip replacements were necessary in 6 cases (1.6 %) - all were SMF stems.

• Stress shielding with thigh pain were observed only by patients in the short stem group.

• Short stems can be replaced using a classic hip stem if revision hip arthroplasty is necessary (Fig. 3,4).

Stichwörter short stems, classic stems, Summit, Synergy, Accolade, SMF, Minihip, Evolution, hip arthroplasty, stress shielding

Publication History

Article published online:
15 October 2020