Mortality After Hemiarthroplasty for Femoral Neck Fractures

An Evaluation of the German Arthroplasty Registry

Femoral neck fractures range among the most common fractures in Germany, with 81 000 cases every year. Because of demographic change, their incidence is rising strongly—about 23% within the past decade. Recent data show that patients with indications of osteoarthritis of the hip are usually treated surgically by means of hemiarthroplasty (hemiprosthesis or dual head prosthesis) (1). Fixation of the shaft can be undertaken as a cemented or uncemented variant. This study aimed to compare mortality in patients with cemented and uncemented hemiarthroplasty after femoral neck fracture on the basis of the German Arthroplasty Registry (EPRD).

Methods

We evaluated retrospectively the data from patients with femoral neck fracture treated by implantation of a hemiarthroplasty between November 2012 and September 2021 from the registry. As data from associations of statutory health insurance funds (AOK Bundesverband GbR [federal association of statutory health insurance funds], Verband der Ersatzkassen e.V., vdek [federal association of alternative health insurance funds, reg. assoc.]), the German Medical Technology Association (BVMed), and several hospitals were included, the included interventions to 2020 added up to a substantial 1.6 million (2). Hemiarthroplasties after femoral neck fracture were categorized into subgroups according to shaft fixation (cemented versus uncemented) and matched by age, sex, body mass index (BMI), and the Elixhauser score by using Mahalanobis distance matching (Figure 1). The death rate after implantation was determined by comparing the data on arthroplasties with deaths registered in insurance data and analyzed with the stratified log rank test.

Figure 1

Inclusion and exclusion criteria of the present analysis from the German Arthroplasty Registry (EPRD) of hemiprostheses in the treatment of femoral neck fractures.

Results

36 862 patients with femoral neck fractures and treatment by hemiarthroplasty were identified in the arthroplasty registry and used for matching. After 3:1 matching of cemented and uncemented hemiarthroplasties by age, sex, Elixhauser comorbidity score, and BMI, 18 180 patients were included in the subsequent data evaluation (Figure 1). During the acute inpatient stay, the mortality risk for patients with a cemented stem increased by 6.4% compared with 5.4% for persons with an uncemented hemiprosthesis. After a month, the rates rose to 8.5% for uncemented and 9.0 for cemented hemiarthroplasties; the difference did not reach significance for the total time period (stratified log rank test: p=0.231; hazard ratio for cemented stems: 1.03; 95% confidence interval [0.98; 1.08). After six months the probability of a patient’s death was 21.9% for uncemented and 22.0% for cemented hemiarthroplasties and rose to 29.0% for both variants one year after implantation. Within 3 years the number of deaths was roughly half (uncemented: 49.76%; cemented: 51.2%) and after 5 years some two thirds of all patients treated (Figure 2).

Figure 2

Trend in patient mortality after femoral neck fracture treated by cemented or uncemented hemiarthroplasty (stratified log-rank test p = 0.231)

Discussion

The probability of dying after implantation of a cemented hemiarthroplasties was not significantly increased for the total follow-up period of 5 years. During inpatient stays, a risk increase of 1% was found for cemented fixation compared with uncemented fixation. Over time the difference in the mortality risk fell for both fixation techniques. Still, a continuous, initially exponential and subsequently linear, growth in mortality manifested for both fixation techniques, of roughly a third within the year after implantation. The working group of Parker in 2010 in a systematic review of randomized controlled trials clearly showed the advantages of uncemented fixation, with more rapid mobilization and reduction in postoperative pain (3). As regards mortality, earlier studies did not show a clear advantage of a stem fixation method over the other over the long term. Only data from the UK fracture registry showed in an unmatched population significantly lower mortality after cemented stem fixation (4). By contrast, our evaluation of the EPRD, which compared matched data in a large study population, demonstrated over the entire follow-up period no significantly higher mortality in hemiarthroplasties with cemented stem fixation. This is consistent with the mortality of 6.4% (cemented) versus 5.4% (uncemented hemiarthroplasties) found in our analysis. Subsequently no difference was observed.

A theory for the increased mortality immediately after implantation is bone cement implantation syndrome (BCIS). This develops in some 28% of all cemented hemiarthroplasty interventions and in 6.8% at higher grades (BCIS grade 2 and 3). It manifests as hypoxia, sudden loss of arterial pressure, pulmonary hypertension, arrhythmias, and even cardiac arrest (5). Although the exact pathomechanism has not been explained fully and a multifactorial origin seems most likely, the commonly occurring intraoperative, occasionally subclinical pulmonary embolisms have a role. To prevent these, existing safety concepts need to be heeded and close perioperative and postoperative monitoring needs to be established.

Conclusions

Mortality after cemented hemiarthroplasty for femoral neck fracture in a 5-year period was not statistically significantly higher than uncemented fixation. Because of the indistinguishable mortality rate over the longer term and the advantages described in the literature, the recommended intervention is for cemented femoral shaft fixation in hemiarthroplasties after femoral neck fracture.

Conflict of interest statement
AG is medical director of the EPRD; AS is the scientific/academic director of the EPRD. The remaining authors declare that no conflict of interest exists.

Manuscript received on 3 October, revised version accepted on 11 January 2023.

Translated from the original German by Birte Twisselmann, PhD.

Cite this as:
Szymski D, Walter N, Melsheimer O, Grimberg A, Alt V, Steinbrück A, Rupp M: Mortality after hemiarthroplasty for femoral neck fractures—an evaluation of the German Arthroplasty Registry. Dtsch Arztebl Int 2023; 120: 297–8.
DOI: 10.3238/arztebl.m2023.0007

References

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2. Jansson V, Grimberg A, Melsheimer O, Perka C, Steinbrück A: Orthopaedic registries: the German experience. EFORT Open Rev 2019; 4: 401–8.

3. Parker MJ, Gurusamy KS, Azegami S: Arthroplasties (with and without bone cement) for proximal femoral fractures in adults. Cochrane Database Syst Rev 2010; CD001706.

4. Costa ML, Griffin XL, Pendleton N, Pearson M, Parsons N: Does cementing the femoral component increase the risk of peri-operative mortality for patients having replacement surgery for a fracture of the neck of femur? Data from the National Hip Fracture Database. J Bone Joint Surg Br 2011; 93: 1405–10.

5. Olsen F, Kotyra M, Houltz E, Ricksten S-E: Bone cement implantation syndrome in cemented hemiarthroplasty for femoral neck fracture: incidence, risk factors, and effect on outcome. Br J Anaesth 2014; 113: 800–6.