Elsevier

Injury

Volume 51, Issue 3, March 2020, Pages 663-669
Injury

Factors affecting dislocation after bipolar hemiarthroplasty in patients with femoral neck fracture

https://doi.org/10.1016/j.injury.2020.01.025Get rights and content

Highlights

  • Patients with dislocation become susceptible to various complications and morbidities.

  • Clinicians should pay attention to prevent hip dislocation after HA.

  • Smaller OP, CE angle of the operated side, and higher FHEI and smaller HHC of the non-operated side should be monitored.

  • These factors are associated with a high incidence of dislocation.

Abstract

Purpose

This study aimed to investigate the anatomic risk factors associated with dislocation following bipolar hemiarthroplasty for the treatment of femoral neck fracture.

Materials and Methods

We retrospectively reviewed 208 consecutive patients (133 women, 75 men) with femoral neck fractures who were treated with bipolar hemiarthroplasty between 2015 and 2018. A comparative analysis was performed between dislocation (n = 18) and non-dislocation (n = 190) groups in terms of patient demographics, surgical and pelvic morphologic factors, and clinical outcomes, including postoperative Harris and modified Harris hip scores. Independent risk factors affecting dislocation were also evaluated.

Results

The mean follow-up period was 30.8 ± 2.0 (range, 12–48) months. The mean age was 79.2 ± 7.4 (range, 71–94) years. The dislocation rate was 8.6% (18/208), and the mean dislocation time after operation was 2.0 ± 1.1 (range, 1–4) months. Patient-related factors did not differ between the dislocated and non-dislocated groups. As regards dislocation, statistically significant difference was observed in surgical and pelvic morphologic factors, including femoral offset, residual femoral neck length, trochanter upper end and femoral head center distance, and height of the hip center of the operated side (p = 0.025, p = 0.013, p = 0.002, p = 0.008, respectively). Moreover, the femoral offset, height of the hip center, and femoral neck-shaft angle of the non-operated side are significantly different between the groups (p = 0.007, p = 0.001, p = 0.027, respectively). Decrease in the center edge (CE) angle, offset of prosthesis, and increase in femoral head extrusion index (FHEI) of the operated side and decrease in the height of the hip center of the non-operated side increased the risk of dislocation (p = 0.030, OR: 1,306; p = 0.041, OR: 8.15; p = 0.020, OR: 1.038; p = 0.010, OR: 2.02, respectively).

Conclusions

Pelvic morphologic features and surgical factors were found to affect dislocation. Patients with smaller OP, CE angle of the operated side, and higher FHEI and smaller height of the hip center of the non-operated side should be carefully monitored to decrease postoperative dislocation.

Introduction

The incidence rate of hip fractures is increasing with increasing average life span and social activities in elderly patients. In this patient population, the main goal after a hip fracture is to try to return to performing daily activities at pre-fracture levels as soon as possible to prevent complications [1].

Surgical options for displaced adult femoral neck fractures include closed/open reduction internal fixation, total hip arthroplasty, and hemiarthroplasty. Arthroplasty is a widely accepted treatment because it allows early patient mobilization. Open reduction and internal fixation is rarely used for femoral neck fractures in an elderly population because of high nonunion rates and poor functional outcomes after transition to arthroplasty [2]. Hemiarthroplasty offers a better alternative to displaced femoral neck fractures than open reduction and internal fixation when considering factors such as complications, revision rate, and health-related quality of life [2]. Moreover, hemiarthroplasty is the preferred treatment because it is a shorter and relatively simple procedure with less blood loss compared to total hip arthroplasty. In addition, its reported dislocation rate is lower than that of total hip arthroplasty [3], [4], [5]. Although its incidence is lower than that of total hip arthroplasty, dislocation in hemiarthroplasty remains consistently occur and can increase the mortality and morbidity rates in elderly patients [6].

Hemiarthroplasty dislocation is a serious complication with incidence rates ranging from 1.5% to 16% [7], [8], [9]. Various risk factors for dislocation related to the patient or surgery have been reported [8,[10], [11], [12]]. Some of the causes of patient-related risk factors are neurological disorders; abductor muscle weakness; hip joint deformities, where surgery-related dislocations were associated with different surgical approaches, prosthetic; and other problems [10]. In several recent studies, femoral offset, leg-length discrepancy, and acetabular center edge (CE) angle have been identified as potential factors affecting the dislocation rates [8,11,12]. However, a comprehensive evaluation was not performed.

In this study, we aimed to investigate factors that may cause dislocation following a bipolar hemiarthroplasty by evaluating the pelvic geometry in addition to the patient characteristics and investigate the incidence of dislocation for the treatment of femoral neck fractures in elderly patients.

Section snippets

Study population

We retrospectively reviewed the medical records and radiographs of 250 patients who underwent bipolar hemiarthroplasty for femoral neck fracture between June 2015 and April 2018. Of these, 208 consecutive patients (133 women, 75 men with a mean age of 79.2 ± 7.4 years; range, 71–94 years) were finally enrolled, after excluding 42 patients. The inclusion criteria were as follows: [1] patients underwent bipolar hemiarthroplasty through a posterolateral approach, [2] surgery due to displaced

Results

Among 208 hemiarthroplasty cases, dislocation occurred in 18 of 208 cases (8.6%) during follow-up, and all dislocations followed a posterior direction. The mean patient age was 79.2 ± 7.4 (range, 71–94) years. The mean follow-up period was 30.8 ± 12.0 (range, 12–48) months. The mean dislocation time after operation was 2.0 ± 1.1 (range, 1–4) months. Patient-related factors did not differ between the dislocated and non-dislocated groups. Patients’ characteristics are summarized in Table 1.

As

Discussion

This study mainly found that pelvic morphologic features and surgical factors affect hemiarthroplasty dislocation. Decreased CE angle, increased offset of the prosthesis, and increased FHEI on the operated side and decreased height of the hip center on the non-operated side were found to be significant risk factors of dislocation. Patient characteristics and other surgical factors had no effect on the risk of dislocation. Further, the mean postoperative Harris and modified Harris hip scores did

Conclusion

Once the dislocation has occurred, the patient becomes susceptible to various complications and morbidities. Therefore, the clinicians should pay attention to prevent hip dislocation after hemiarthroplasty because conditions such as reduction difficulties, need for open reduction, and increased risk of revision surgery after dislocation may lead to a significant increase in morbidity and mortality. The results of this study suggest that patients with smaller offset of the prosthesis, CE angle

Declaration of Competing Interest

Turan Bilge Kizkapan, Abdulhamit Misir, Erdal Uzun, Sinan Oguzkaya and Mustafa Ozcamdalli declare that they have no actual or potential conflict of interest including any financial, personal, or other relationships with other people or organizations within 3 years of beginning the submitted work that could inappropriately influence, or be perceived to influence, their work.

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