Elsevier

Injury

Volume 48, Issue 6, June 2017, Pages 1170-1174
Injury

Does femoral offset recover and affect the functional outcome of patients with displaced femoral neck fracture following hemiarthroplasty?

https://doi.org/10.1016/j.injury.2017.03.022Get rights and content

Abstract

Background

Restoring preoperative horizontal femoral offset (FO) promised good functional outcome in patients receiving total hip arthroplasty. However, relatively little was known regarding the clinical relevance of restoring the offset in patients with bipolar hemiarthroplasty to treat displaced femoral neck fracture. Therefore, the objective of this study was to evaluate postoperative FO accurately and verify its relation with functional outcome.

Methods

One hundred elderly patients who received bipolar hemiarthroplasty to treat displaced femoral neck fracture were identified. Preoperative CT scanning of contralateral hip joint and reconstruction of images led to rotation-free FO. By referencing postoperative implant specification and comparing to measured values in Picture Archive and Communication System, rotation-free postoperative FO and the amount of change were acquired. Postoperative Harris Hip Score (HHS) and Modified Barthel Index (MBI) were evaluated to measure functional outcome at 12-month after the surgery. Patients with significant FO change were identified. Multiple regression analysis was conducted to determine if the FO change might independently affect the outcome regardless of confounding factors.

Results

The mean preoperative offset was 37.4 ± 2.5 increased by 12.7 ± 9.6% after the surgery. Only 25.0% of postoperative offset after hemiarthroplasty was changed within ±5% of preoperative offset. A total of 45.0% of postoperative offset changed within ±10% while 77.0% of postoperative offset changed within ±20%. 23% of patients whose FO changed more than 20% showed significantly worse outcome score than the patients whose FO change remained within ±20% of initial value. Mean MBI and HHS were negatively correlated with FO change. After adjusting for confounding factors, significant correlation remained between modification of FO and MBI, but not between FO change and HHS (B = 4.576; β = 0.235; 95% confidence interval of B: 0.534 to 8.135).

Conclusions

FO was not properly restored in 23% of subjects receiving bipolar hemiarthroplasty due to femoral neck fracture. FO restoration independently predicted fair MBI after the surgery. Therefore, surgeons should pay attention to restoring FO with meticulous templating.

Introduction

The aging society has posed a grave problem related to hip fractures worldwide [1], [2], [3]. Although the hip fracture incidence in some western countries is decreasing [1], [2], [3], the social and economic burden associated with hip fracture have impacted many Asian countries such as Korea, Japan, and China [4], [5], [6]. Hip fracture is a clinical nuisance to clinicians due to high morbidity and mortality [7]. Unlike trochanteric fractures, displaced femoral neck fractures are treated with arthroplasty [8]. Favorable reports on the outcome after total hip arthroplasty in elderly patients have been presented recently [8], [9], [10]. However, bipolar hemiarthroplasty remains the first treatment of choice for this condition [8].

Unlike modular stem, conventional femoral stems do not provide options for variable offset [11]. Therefore, restoring preoperative vertical and horizontal offset is not always possible [12]. Change of horizontal femoral offset (FO) after bipolar hemiarthroplasty for treating displaced femoral neck fracture has not been paid much attention so far despite its clinical significance compared to total hip arthroplasty [13], [14]. Moreover, past studies have reported inconsistent results regarding the importance of offset change [13], [14]. It has been reported that FO can affect the abductor lever arm, muscle strength, joint reaction force, and joint stability in studies conducted in total hip arthroplasty patients [12], [15], [16], [17]. Likewise, postoperative clinical outcome, activity of daily living, and quality of life after bipolar hemiarthroplasty can be influenced by change of horizontal offset [14]. Moreover, after the surgery, these patients would probably survive longer than before due to lengthened life expectancy. Thus, factors affecting quality of life of these patients would be of paramount interest.

One plausible explanation of the paucity regarding this subject might be the difficulties in evaluating horizontal offset. Vertical offset or leg length discrepancy is easy to evaluate postoperatively in plain radiographs because it is hardly affected by the rotation of affected limb. However, measurement of horizontal offset can be greatly influenced by the rotation of the lower extremity and the anteversion of the femoral stem [17]. Previous studies have acknowledged this limitation [18], [19] while some were confined to such error [20], [21]. Accurate measurement of FO change would be mandatory for proper interpretation of its effect on the postoperative functional outcome.

We hypothesized that FO after bipolar hemiarthroplasty in elderly subjects with displaced femoral neck fracture might differ from the preoperative value and that the amount of change could affect the functional outcome if measured free of radiographical error. Therefore, the objectives of this study were: (1) to investigate the accurate change of femoral offset after hemiarthroplasty in elderly patients with displaced femoral neck fracture, and (2) to clarify whether there was an association between FO change and postoperative functional outcome.

Section snippets

Methods

The study protocol was approved by the Institutional Review Board of our institution. This retrospective observational study was conducted in a single university hospital located in a city with one million inhabitants of East Asians. The hospital has a level 1 trauma center specialized for acute traumas.

One hundred hips in 100 consecutive patients (75 women and 25 men) with displaced femoral neck fracture who underwent bipolar hemiarthroplasty in a single institution were enrolled in the

Results

Patient demographics are reported in Table 1 and five patients passed out during follow-up 1-year. There was no dislocation. The mean preoperative offset measured in the preoperative CT scan of the contralateral hip was 37.4 ± 2.5 mm (range, 30.0–40.5). The offset was increased by 12.7 ± 9.6% (range, −5.4 to 46.7%) after the surgery. Only 25.0% of postoperative offset after hemiarthroplasty changed within ±5% of the preoperative offset. A total of 45.0% of postoperative offset changed within ±10% of

Discussion

In this observational study, we determined whether FO before and after bipolar hemiarthroplasty differed in elderly subjects with displaced femoral neck fracture and whether the amount of change would possibly worsen the functional outcome in such patients. FO increase of more than 20% of preoperative offset resulted in worse functional outcome scores such as MBI and HHS. Although tremendous literature has focused on FO change in the total hip arthroplasty patients [15], [16], [17], [20], [21],

Conclusion

In summary, the current study showed that FO was not correctly restored in 23% of patients receiving bipolar hemiarthroplasty for displaced hip fracture after correction of the rotational error in plain radiographs. Restored FO positively affected MBI, but not HHS. This suggests that restoring FO has clinical relevance in the functional outcome. Therefore, surgeons are recommended to pay attention to restoring the original FO, even in bipolar hemiarthroplasty setting. Further study is needed to

Conflict of interest

None.

References (33)

  • A. Icks et al.

    Trend of hip fracture incidence in Germany 1995–2004: a population-based study

    Osteoporos Int

    (2008)
  • S.Y. Cheng et al.

    Geographic trends in incidence of hip fractures: a comprehensive literature review

    Osteoporos Int

    (2011)
  • H. Orimo et al.

    Hip fracture incidence in Japan: estimates of new patients in 2012 and 25-year trends

    Osteoporos Int

    (2016)
  • Y.C. Ha et al.

    Current trends and future projections of hip fracture in South Korea using nationwide claims data

    Osteoporos Int

    (2016)
  • W.B. Xia et al.

    Rapidly increasing rates of hip fracture in Beijing, China

    J Bone Miner Res

    (2012)
  • J.G. Kim et al.

    Diagnosis of osteoporosis

    J Korean Hip Soc

    (2011)
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