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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 4  |  Issue : 1  |  Page : 14-19

What is the minimum fixation required to repair flail chest?


1 Department of Thoracic Surgery, Oxford University Hospitals NHS Foundation Trust, Oxford, England, UK
2 Nuffield Department of Medicine, Oxford Respiratory Trials Unit, University of Oxford, Oxford, England, UK

Date of Web Publication30-Dec-2019

Correspondence Address:
Elizabeth Belcher
Department of Thoracic Surgery, Oxford University Hospitals NHS Foundation Trust, Oxford, England
UK
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jctt.jctt_5_19

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  Abstract 


Context: Flail chest is associated with significant mortality risk. Chest wall repair is associated with improved outcomes; however, the optimal fixation technique is unknown.
Aims: We undertook a review to assess the optimal fixation technique required in order to successfully repair flail chest.
Subjects and Methods: This is a retrospective review of consecutive patients with multiple rib fractures undergoing surgical fixation. The predictive value of ratio of fractures fixed in relation to flail segment and ratio of ribs fixed in relation to flail segment was assessed by the primary outcome measure of requirement for reoperation.
Results: Thirty-one patients presenting with symptomatic rib fractures were referred to a single surgeon for primary management or a second opinion following previous fixation, between August 2011 and October 2018, and underwent repair. Twenty-two patients were male (71%), and the median age was 66 years (range: 18–81). Twenty-seven patients (87%) were diagnosed with flail segment. Twenty-four patients had a “Fracture Fixation to Flail” ratio (Fx: Fl) ≥1, and none required further rib fixation, whereas three patients had Fx: Fl<1, two of whom (67%) required further rib fixation (P = 0.0085). Twenty patients had Rx: Fl≥1, and none required further rib fixation, whereas seven patients had Rx: Fl<1, in whom five (71%) required no further intervention and two (29%) required further rib fixation (P = 0.0598). Minimum fixation number (MFN) was calculated. MFN was achieved in 22 of 27 patients. Two of the four patients with MFN did not achieve the required refixation (P = 0.0171).
Conclusions: Fx:Flmost accurately predicts the risk of underfixation and subsequent requirement for further intervention in patients undergoing operative repair of flail chest.

Keywords: Chest injury, flail chest, reconstruction, rib fixation


How to cite this article:
Wallwork K, Mitchell J, Rahman N, Belcher E. What is the minimum fixation required to repair flail chest?. J Cardiothorac Trauma 2019;4:14-9

How to cite this URL:
Wallwork K, Mitchell J, Rahman N, Belcher E. What is the minimum fixation required to repair flail chest?. J Cardiothorac Trauma [serial online] 2019 [cited 2020 Jul 4];4:14-9. Available from: http://www.jctt.org/text.asp?2019/4/1/14/274212




  Introduction Top


Flail chest is associated with high mortality rates of up to 33%.[1] It is a marker of significant injury; while a proportion of deaths in such patients may be accounted for associated injuries, almost 10% are directly attributable to the flail chest itself.[2],[3] Conservative treatment with pain control and noninvasive or mechanical ventilation is associated with a high incidence of pneumonia, prolonged intensive care unit (ICU) stay, and subsequent high treatment costs.[4],[5]

Surgical fixation may improve outcomes including reduced rates of pneumonia, shorter ICU and hospital length of stay (LOS), improved pulmonary function, and treatment costs.[6],[7],[8],[9],[10]

While surgical fixation appears beneficial, the optimal fixation technique is uncertain. Fixation of those fractures required to convert flail chest to simple fractures may suffice.[11],[12],[13] Such a policy, however, may be associated with residual deformity, and some authors have suggested that all fractures within a flail segment should be targeted at operation.[14] The exact intraoperative point at which meaningful fixation of flail chest is achieved is, therefore, unknown, and is currently determined in a surgeon-specific manner. The ability to identify such a point would reduce the risk of underfixation while avoiding unnecessary additional operative time and extension of surgical incisions. We hypothesized that calculation of a ratio of the fixation number in relation to the number of fractures within a flail segment, may predict successful repair and guide optimal fixation technique.


  Subjects and Methods Top


Patient cohort

A retrospective study was performed on consecutive patients who underwent surgical repair of acute symptomatic chest wall injuries by a single surgeon between August 2011 and October 2018 at Oxford University Hospitals NHS Foundation Trust, UK. Patients with acute chest trauma were referred during the first admission for either primary management or a second opinion following previous fixation. Patients with chronic chest injury were not included in the current study. Indications for surgery were multiple rib fractures with nonresolving or deteriorating respiratory compromise with flail chest, or any fracture pattern with failure of optimal medical management. Flail chest was defined as two or more fractures in two or more consecutive ribs.[15],[16] Bilateral anterior fractures with the same rib position number were considered as flail segments. Indication for reoperation following previous fixation was the clinical scenario of failure to extubate patient, which was considered to be due to ongoing flail chest.

Protocol

Demographics, mechanism of injury, radiological features, and in-hospital outcomes were recorded. Computed tomography scans and reports were examined to include the number of rib fractures, number of ribs fractured, the presence or absence of flail segment, and number of ribs contained within any flail segment. Intraoperative details including number of ribs and rib fractures undergoing fixation and number of plates utilized were examined. Postoperative clinical outcomes were documented via medical records. Postoperative outcomes including mortality, requirement for reintervention, and postoperative and total LOS were documented. As this is an evaluation of our standard of care, ethical approval is not required at our institution. The study was approved by the audit office of the Oxford University Hospitals NHS Foundation Trust.

Surgical procedure

Operations were performed by the same surgeon either as the primary procedure or following previous operations by other surgeons. The surgery was performed under general anesthesia. Anatomical reduction and fixation were undertaken via incisions determined as appropriate by the operating surgeon. Posterior and lateral fixation was undertaken mainly via vertical incision, whereas anterior repair was performed via submammary and/or midline incisions. Where possible, incisions were minimized by the use of separate microstab incisions to facilitate drilling and screw placement at 90° to the plate. Muscle-preserving dissection was performed, where possible. Periosteum was preserved, and fractures were reduced and fixed utilizing MatrixRIB™ Fixation System (Synthes GmbH, Oberdorf, Switzerland) with universal and precontoured plates.

Statistical analysis

We considered fixation first in relation to the number of fractures fixed and second in relation to the number of ribs fixed and compared these with the number of ribs within the flail segment. Three separate calculations were recorded [Figure 1]. Fracture fixation-to-flail ratio (Fx:Fl) and rib fixation-to-flail ratio (Rx:Fl) were calculated. The Fx:Fl is defined as the number of fractures fixed in relation to the number of ribs within the flail. The Rx:Fl is defined as the number of ribs fixed in relation to the number of ribs fixed within the flail. Finally, an MFN was calculated utilizing the formula of the sum of “the number of ribs within the flail segment” and “the number of ribs with more than two fractures.” A three-segment flail chest containing a total of six fractures, where one fracture in each of the three ribs undergoes fixation, will result in an Fx:Fl of 1 and a Rx:Fl of 1. An MFN of three is achieved [Figure 2]. When considering a three-segment flail chest containing a total of six fractures where all undergo fixation, an Fx:Fl of 2 and a Rx:Fl of 1 are achieved. An MFN of three is exceeded [Figure 3]. Finally, where a three-segment flail containing nine fractures, with three fractures/rib are identified, fixation of four fractures to include each rib will result in an Fx:Fl of 1.3 and a Rx:Fl of 1. An MFN of six is not achieved [Figure 4].
Figure 1: Calculation of (a) fracture fixation-to-flail ratio, (b) rib fixation-to-flail ratio, and (c) minimum fixation number

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Figure 2: Schematic of three-segment flail (a) and fixation of three fractures over three ribs (b) demonstrating fracture fixation-to-flail ratio of 1 and rib fixation-to-flail ratio of 1. A minimum fixation number of three has been achieved

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Figure 3: Schematic of three-segment flail (a) and fixation of six fractures over three ribs (b) demonstrating fracture fixation-to-flail ratio of 2 and rib fixation-to-flail ratio of 1. A minimum fixation number of three has been exceeded

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Figure 4: Schematic of three-segment flail consisting of nine fractures over three ribs (a) and fixation of four fractures over three ribs (b) demonstrating fracture fixation-to-flail ratio of 1.3 and rib fixation-to-flail ratio of 1. A minimum fixation number of six has not been achieved

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Continuous data were presented as median (interquartile range [IQR]); categorical variables were presented as n (%). Primary outcome measure was requirement for reoperation where failure to extubate following initial fixation was due to continuing flail. Fisher's exact test was used for inferential comparison due to event rates <5 in some categories. Statistical analysis was performed using the GraphPad Prism statistical package (version 4.0; GraphPad Software Inc., San Diego, California, USA).


  Results Top


Patient demographics

Thirty-one patients with symptomatic rib fractures were referred to a single surgeon for primary management or a second opinion following previous fixation, between August 2011 and October 2018, and underwent chest wall repair. Twenty-two patients were male (71%), and their median age was 66 years (range: 18–81). Mechanisms of injury included road traffic accident (n = 13), fall (n = 15), cardiopulmonary resuscitation (n = 2), and crush injury (n = 1). In 17 patients (55%), thoracic injuries were associated with polytrauma. Anatomical distribution of the chest injury included unilateral–posterior (n = 1), antero–lateral (n = 3), postero–lateral (n = 12), antero–postero–lateral (n = 3), and bilateral (n = 12). Demographics are presented in [Table 1].
Table 1: Demographics of 31 patients undergoing fixation

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Six patients underwent sternal fixation; one in isolation and five in association with rib fixation. Sternal injuries were, for the purpose of this review, considered separately and not identified as “rib” fractures in data interpretation.

Treatment characteristics

Four hundred and twenty-six fractures were noted in 31 patients. The median number of rib fractures/patient was 12 (IQR: 10–16), and the median number of ribs fractured was nine (IQR: 7–12). Flail segment was present in 27 patients (87%). The median time to operation was 3 days (IQR: 2–5). The median number of ribs per flail segment was four (IQR: 3–6). The median number of fractures which were fixed at operation was seven (IQR: 5–9) on six ribs (IQR: 5–7). The median number of rib plates utilized was seven (IQR: 5–8). The median LOS was 16 days (IQR: 8–28), and the median postoperative LOS was 11 days (IQR: 6–20). Two patients died in the hospital, while the remainder were discharged home or to other specialties due to associated injuries.

Fracture fixation ratio and rib fixation ratio

Calculations for patients with flail chest are shown in [Table 2]. Fx:Fl, defined as the proportion of fractures undergoing fixation in relation to the number of ribs contained within the flail segment, was calculated [Figure 1]a. Fx:Fl ratio was significantly associated with need for further rib fixation; 24 patients had a ratio of ≥1, and none required further rib fixation; whereas three had a ratio of <1, of whom two (67%) required further rib fixation (P = 0.0085, Fisher's exact test, 1 df). The median Fx: Fl was 1.5 (IQR 1–2.3). Rx:Fl, defined as the proportion of ribs undergoing fixation in relation to the number of ribs contained within the flail segment, was calculated [Figure 1]b. Rx:Fl ratio was nonsignificantly associated with the need for further rib fixation; twenty patients had a ratio ≥1, and none required further rib fixation, whereas seven had a ratio of <1, of whom two required further rib fixation due to failure to progress (P = 0.0598, Fisher's exact test, 1df). The median Rx:Fl was 1.2 (IQR 0.8–2.3). In both patients who required further rib fixation, Fx:Fl and Rx:Fl were <1. Additional fixation in these patients included ribs 3, 4, 5, 6, 7 and 5, 6, 7, respectively. In both patients requiring further rib fixation, Fx:Fl, but not Rx:Fl, increased to ≥1. Only one patient with an Fx:Fl<1 did not require refixation, whereas five patients tolerated a Rx:Fl<1 without requirement for refixation [Figure 5].
Table 2: Calculation of fracture fixation-to-flail ratio, rib fixation-to-flail ratio, and minimum fixation number

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Figure 5: Predictive value of (a) fracture fixation-to-flail ratio < 1, (b) rib fixation to flail ratio <1, (c) minimum fixation number achieved. Dark blue represents ratio ≥1; light blue represents ratio <1 (a and b). Dark blue represents minimum fixation number achieved; light blue represents minimum fixation number not achieved, (c) Red represents patients requiring refixation

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Minimum fixation number

We calculated an MFN for patients who underwent fixation of flail chest. The MFN was defined as the sum of the number of ribs within the flail segment and the number of ribs with >2 fractures [Figures 1c]. The median MFN was five (IQR: 3–6). In 23 of 27 patients who underwent repair of flail chest, the number of fractures fixed was greater than or equal to the MFN. In four patients undergoing repair, the MFN exceeded the number of fractures fixed (P = 0.0171, Fisher's exact test, 1 df). Two of these four patients required refixation for ongoing flail, whereas the other two tolerated MFN not being achieved without requirement for re-repair [Figure 5].


  Discussion Top


Surgical fixation may improve outcomes including reduced rates of pneumonia, reduced ICU and hospital LOS, improved pulmonary function, and reduced treatment costs.[6],[7],[8],[9],[10] Despite this, the optimal fixation technique is not known, and the point at which meaningful fixation has occurred intraoperatively is determined in a surgeon-specific manner. The relative importance of the number of fractures and/or ribs undergoing fixation within a flail segment is uncertain. We have demonstrated an Fx:Fl ratio ≥1, a Rx:Rl ratio ≥1, and achieving fixation of a minimum number of fractures as predicted by the calculation of an MFN, all predict successful repair.

An Fx:Fl<1 most accurately predicts subsequent requirement for further intervention in those patients undergoing operative repair of flail chest injury. While a Rx:Rl ratio ≥1 also predicts success, a Rx:Fl<1 appears to overpredict the risk of further intervention. Only two of the seven patients with a Rx:Fl<1 required reoperation compared to two of the three patients with an Fx:Fl<1. Fx:Fl, therefore, appears to be a better predictor of risk of underfixation when compared to Rx:Fl. The number of fractures fixed rather than the number of ribs fixed appears to be of greater significance in successful fixation. Not achieving fixation of the number of ribs based on the calculation of an MFN was intermediate in the prediction of requirement for reoperation between Rx:Fl<1 and Rx:Fl<1.

Previous studies have not directly addressed the number of ribs of fractures which should be fixed in order to successfully repair flail chest. In a study of patients undergoing rib fixation utilizing STRATOS™ bars (MedXpert GmbH, Heitersheim, Germany), an average of 3.3 ± 0.6 bars were used to fix an average of 7.7 ± 2.4 fractures.[11] While the number of ribs within each flail segment was not stated, this may suggest a lower ratio than that identified in the present study. The authors treated only one of the two ribs where displaced or comminuted fractures were identified, with the adjacent rib being wrapped using vicryl suture on the osteosynthesis rib. Calculation of Fx: Fl based on bars utilized from this study, would, therefore, have underestimated the number of fractures required for meaningful fixation.

The overprediction of a rib-based calculation such as Rx:Fl reveals the importance of the rib position in the context of flail chest pathology. In patients with a Rx:Fl<1 requirement for reintervention was determined by the position of the nonfixed ribs within the flail segment. Fixation of ribs within the “respiratory vital” zone of rib position 2–7 was more important than fixation of ribs outside this zone. Both patients undergoing refixation required additional plating of ribs within this zone. In the five patients with a Rx:Fl<1 not requiring fixation, ribs not fixed within the flail segment included 2nd, 3rd, 10th, 11th, and/or 12th, and no further intervention was required. Where a flail segment includes ribs 1, 2, 3, 10, 11, and 12, an Fx:Fl<1 may be acceptable.

Position of the flail in terms of whether rib positions 2–7 are affected may explain the wide range of percentage fixation undertaken in the partial repairs of Nickerson et al.[13] In their study of complete versus partial fixation, the authors concluded that conversion of flail chest into simple fractures is sufficient to restore chest wall physiology. Where partial fixation only was undertaken, between 20% and 80% of fractures within the flail segment were repaired. While the authors did not consider the position of the flail, this may explain the apparent wide range of percentage of fractures fixed in a cohort of patients who underwent successful fixation. Jayle et al.[11] also noted in their study of rib fixation that a combination of high ipsilateral fractures of rib position numbers 1–3 not addressed surgically was associated with successful fixation. These conclusions support our current findings regarding the importance of the “respiratory vital” zone where fractures outside ribs 2–7 may be left with a resulting Fx:Fl ratio <1 in association with successful fixation.

It may be important to take account of not only the number of ribs within the flail, but also the number of fractures in each rib contained within the flail. While most flail segments involve two fractures per rib, those patients with more than two fractures per rib may be at risk of underfixation [Figure 6]a and b]. Such patients require fixation of more than one fracture per rib in order to eliminate flail. We, therefore, calculated an “MFN” for each patient which takes account of not only the number of ribs in the flail but also the number of fractures in each rib in the flail. This fracture-based calculation was superior to the rib-based calculation, Rx:Fl, in the prediction of requirement for reoperation.
Figure 6: Posterior view (a) and inferolateral view (b) computer tomography of the chest with three-dimensional reconstruction demonstrating in both views more than two fractures per rib in the flail segment. Fixation of one fracture per rib will result in a residual flail in such patients

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The present study has a number of limitations. The study is subject to the attendant biases of retrospective analyses. Such a review is limited by retrospective interpretation of contemporaneous operation notes regarding the details of rib plates' and fractures' number and location. While Fx:Fl ratio may be a useful predictor of underfixation, it is not possible to determine from this study whether Fx:Fl ratio could be used to identify those who may have undergone overfixation. In addition, there were a relatively small number of events in this cohort.

We have demonstrated that calculation of Fx:Fl most accurately predicts the risk of underfixation and requirement for further intervention in patients undergoing chest wall fixation for flail chest injury. Calculation of Fx:Fl may facilitate optimal repair of flail chest. Studies of prospective calculation of Fx:Fl are required to validate its role in the prediction of optimal repair of flail chest injury.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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5.
Doben AR, Eriksson EA, Denlinger CE, Leon SM, Couillard DJ, Fakhry SM, et al. Surgical rib fixation for flail chest deformity improves liberation from mechanical ventilation. J Crit Care 2014;29:139-43.  Back to cited text no. 5
    
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11.
Jayle CP, Allain G, Ingrand P, Laksiri L, Bonnin E, Hajj-Chahine J, et al. Flail chest in polytraumatized patients: Surgical fixation using stracos reduces ventilator time and hospital stay. Biomed Res Int 2015;2015:624723.  Back to cited text no. 11
    
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Nickerson TP, Thiels CA, Kim BD, Zielinski MD, Jenkins DH, Schiller HJ. Outcomes of complete versus partial surgical stabilization of flail chest. World J Surg 2016;40:236-41.  Back to cited text no. 13
    
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Marasco S, Liew S, Edwards E, Varma D, Summerhayes R. Analysis of bone healing in flail chest injury: Do we need to fix both fractures per rib? J Trauma Acute Care Surg 2014;77:452-8.  Back to cited text no. 14
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2]



 

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