Whether Hemiarthroplasty Remains a Gold Standard Treatment for Patients With Displaced Femoral Neck Fractures? - A 20-year Sample of 4516 Patients From a Single Institute


 BackgroundFemoral neck fracture (FNF) is among the commonest fractures affecting the geriatric population. Hemiarthroplasty (HA) is a standard treatment procedure and has been performed by hip surgeons for decades. Recently, primary total hip replacement has proved advantageous for the treatment of such fractures. This study analysed the causes of HA failure and reevaluated whether HA remains a gold standard treatment for patients with displaced FNFs.MethodsA total of 4516 patients underwent HA at our centre from 1998 to 2017. The HA implants included unipolar and bipolar prostheses. Patients were enrolled who received the diagnosis of a displaced FNF, underwent primary HA initially, required second revision procedures, and were followed up for a minimum of 36 months. Data were collected and comprehensively analysed.ResultsIn 4516 cases, 99 patients underwent second surgeries. The revision rate was 2.19%. Reasons for failure were acetabular wear (n = 30, 30.3%), femoral stem subsidence (n = 24, 24.2%), periprosthetic fracture (n = 22, 22.2%), infection (n = 16, 16.2%), and recurrent dislocation (n = 7, 7.1%). The mean follow-up period was 78.1 months. The interval between failed HA and revision surgery was 22.8 months.ConclusionHA has an extremely low revision rate and remains a gold standard treatment for patients with displaced FNFs.Levels of Evidence: Level III, Retrospective Cohort Study, Therapeutic Study


Introduction
Femoral neck fracture (FNF) is among the commonest fractures affecting the geriatric population. In displaced fracture types, treatments include closed or open reduction and internal xation, hemiarthroplasty (HA), and total hip replacement (THR). HA is a frequently recommended treatment and has been performed for decades. [1] Nevertheless, the use of primary THR has increased substantially in clinical research.
Several randomised control trials have also demonstrated that for displaced FNF, THR results in superior functional outcomes to those of HA. However, THR is more expensive and results in higher complication rates. The clinical results appear contradictory. [2][3][4][5][6] This study analysed the failure rate for primary HA, compared patients subject to different causes of HA failure, and evaluated factors that might increase the risk of revision surgery being required. Whether HA remains a gold standard treatment for patients with displaced FNF can thereby be evaluated.

Material And Methods
This was a retrospective cohort study and was performed at a single trauma centre. From 1998 to 2017, 4516 patients underwent hemiarthroplasty in our institute following a diagnosis of displaced FNF. The HA implants included the Austin Moore (unipolar monoblock) prosthesis and various bipolar systems (including the Zimmer, Osteonics, and United systems) (Fig. 1). Patients were enrolled who received a diagnosis of displaced FNF, underwent primary HA and second revision surgery, and were followed up for at least 36 months. Patients with multiple fractures, open fractures, pathological fractures, or paediatric fractures; patients who had received previous ipsilateral hip surgeries; and patients whose follow-up periods were insu ciently long were excluded. Data were collected in our database system and comprehensively analysed. The study was approved for publication by the institutional review board of our hospital.
Surgical procedures were performed by various surgeons according to the protocol of our department. Prophylactic antibiotics, including rst-generation cephalosporin, were administered 30 min before skin incision and macrolides to patients with a penicillin allergy. Under spinal or general anaesthesia, patients were operated on in a lateral position, using either the anterolateral (Watson-Jones) approach or the posterior (Moore or Southern) approach. The prosthesis system was chosen according to the preference of the surgeon, and the use of cement xation depended on bone quality and was decided intraoperatively. A portable radiograph of the hip joint was examined before the patient was transferred back to the ward unit.
Oral analgesic agent and intravenous morphine (PRN) were administered for pain control if not contraindicated. Intravenous antibiotics were continuously administered every 8 h after surgery for 1 day and prolonged depending on the patient's clinical condition.
Each patient had his or her own chart with detailed records, including personal data, the mechanism of injury and associated conditions, fracture type and classi cation, course of management, implantation details, xation technique, surgical approach, and functional recovery process. Regular follow-ups were arranged after discharge for all patients. The anteroposterior and lateral radiograph views of the wound condition were evaluated during each outpatient department visit.

Results
Of 4516 patients, 99 were selected to receive second revision surgery, including 5 open reductions and internal xations, 18 revision hemiarthroplasties, and 76 conversion THRs. The revision rate of failed HA and the conversion rate of THR were 2.19% (99 of 4516) and 1.68% (76 of 4516), respectively. The average age of the patients at the time of the injury was 76.4 ± 8.7 years (range: 44-93 years). Of the patients, 57 were male and 42 were female. The physical health and associated medical conditions of the patients were rated based on the American Society of Anaesthesiologists' (ASA) physical status classi cation: 32 patients were in class II, 41 patients were in class III, and 26 patients were in class IV. The mean body weight index (BMI) was 22.8 kg/m 2 (range: 16.9-30.9). Of the fractures, 54 were left sided and 45 were right sided. The interval between injury and surgery was 1.8 ± 1.6 days (range: 1-8). The mean follow-up period was 78.1 ± 55.8 months (range: 40-219). Fourteen patients expired during the follow-up period due to infections (intraabdominal infection and pneumonia were identi ed), malignancies, or cardiovascular diseases. All patients' demographic data are summarised in Table 1.   (Fig. 2). The interval between primary HA and revision surgery was 22.8 ± 30.0 months. Data are summarised in Table 2.

Discussion
The National Health Insurance Research Database of Taiwan documents more than 100 000 hip fracture diagnoses that have caused more than 2000 in-hospital mortalities every year. Along with the trend of rapid population aging, standard management for hip fractures is a prominent theme and represents a challenge for orthopaedic surgeons. [7][8] For displaced FNFs, HA is the standard treatment. However, one study reported that the rate of THR use as a primary treatment option signi cantly increased from 0.7-7.7% between 1999 and 2011. Younger patients are being treated with THRs due to their superior mobility and range of joint motion. [9][10] Clinical research has also shown that THR is superior to HA. For example, Ravi reported that THR is associated with lower revision surgery rates and signi cantly reduces the total costs of hospitalisation. Nevertheless, Sonaje et al stated that HA yielded superior functional outcomes and cost-effectiveness to THR. Wang et al also reported lower proportional hazard values for reoperation in patients treated with HA compared with those treated with a THR. [2][3][4][5][6] Although clinical results are controversial, the surgical procedure of HA has a much shorter duration, results in less tissue damage and exposure, reduces blood loss, improves primary stability, and reduces dislocation and complication rates compared with THR. Moreover, catastrophic metallosis and osteolysis are rarely observed in hemiarthroplasty. These advantages of HA ostensibly make it a superior treatment for older adults with various underlying comorbidities. [1,5] Some concerns in relation to HA have been discussed in other studies: The reoperation rate for failed HA is reportedly as high as 24%, and the problem of acetabular wear has been noted as the primary cause of HA failure. [11][12][13][14][15] These concerns might provide additional motivation for the recommendation of primary THR for FNF displacement. However, in the present study, the HA failure rate and the THR conversion rate were 2.19% and 1.68%, respectively. In this study, the reasons for the failure of HA were acetabular wear (30.3%), femoral stem subsidence (24.2%), periprosthetic fracture (22.2%), infection (16.2%), and recurrent dislocation (7.1%). The prevalence of acetabular wear, femoral stem subsidence, and periprosthetic fracture were similar within the rst 6 months after primary HA according to a multinomial logistic regression analysis. The main cause of early failure was periprosthetic fracture, but the cause of failure became evenly distributed for all 5 groups as time elapsed, and the rates of acetabular wear gradually increased in patients followed up for more than 3 years. A signi cant difference was demonstrated using a statistical analysis (P < .001***). The aggressive prevention of postoperative trauma is ostensibly more critical than is long-term acetabular wear.
No signi cant difference was noted in the comparison among the groups for the 5 HA failure types in terms of age, sex, BMI index, ASA classi cation, prosthesis use, xation technique, surgical approach, and femoral cup size. Results are shown in Table 3. The risk factor of HA failure was not identi ed. Peter et al found that higher ASA scores and BMI indexes (> 40) are strong predictors of revision THR requirement, but similar results were not obtained in our data analysis. Further studies are required to determine the major predictors of HA failure. [16]  This study has limitations. First, it was a single-centre retrospective cohort study. Second, surgeries were performed by different surgeons and using different surgical approaches, xation methods, and prosthesis systems. More comprehensive research and randomised control studies are required to elucidate these results.

Conclusion
On the basis of the encouraging long-term outcomes in this population, we consider that hemiarthroplasty remains the gold standard treatment for patients with displaced FNFs.
This article consisted of a retrospective cohort study which contained information of patients and has been approved by The Institutional Review Board of Taipei Veterans General Hospital of Taiwan with TPEVGH IRB No. 2020-03-011CC. Informed consents were obtained from all individual participants included in the study.

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