Factors associated with subsequent surgical procedures after intramedullary nailing for tibial shaft fractures

Tibial shaft fractures (TSFs) are frequently occurring injuries [1]. Intramedullary nailing (IMN) is widely considered the best treatment for these injuries because it provides good direct relative fracture stability whilst being minimally invasive with regard to surrounding soft tissue [2]. Nevertheless, for many patients IMN is only the first operation in the process of achieving satisfactory operative outcomes, with (several) additional surgical procedures often required. Current literature reports on reoperation rates after operative treatment of TSFs ranging from 14 to 36%; however, few studies have directly investigated this study question (Table 1) [3‐6]. Furthermore, the majority of these studies do not include or report on removal of implant due to local pain or irritation as a secondary procedure as these are considered discretionary. In a recent review of the literature, we found the average rate of symptomatic screw removal after IMN of TSFs to be 9% [7‐12]. However, from the experience at our level-1 trauma centre we believe this to be an underestimation, hypothesizing that the true rate of screw removal, and therefore the true rate of subsequent surgery, is significantly higher.

Surgery for the removal of symptomatic implants can have a significant impact at a socio-economic level [13] and can increase the risk of additional complications [13, 14]. Decreasing the rate of these procedures should therefore be considered an important goal. However, to the best of our knowledge, thus far, no factors associated with implant removal have been identified.

The primary aim of this study was to assess the total rate of subsequent surgery after IMN of TSFs, including symptomatic implant removals. The secondary aim was to assess what patient, trauma and fracture characteristics are associated with (1) subsequent surgery for wound and fracture healing and (2) subsequent surgery for implant removal. This knowledge will allow clinicians to better inform patients on expected outcomes following surgery. Additionally, it will allow for better insight into the total health economic costs associated with IMN of TSFs.

From 2009 to 2016, 251 patients were treated with IMN for TSFs. Sixty patients (24%) were excluded: 36 patients (14%) had inadequate follow-up, 21 patients (8%) were followed up externally, one patient received palliative care after surgery, one patient had incomplete records and one patient had a pathological fracture.

A total of 191 patients were included. The majority of patients were male (71.2%) with a median age of 37 years (range, 14–90 years). Eighty patients (42%) sustained the fracture in a high-energy trauma, and 39 (20%) were polytrauma patients. Further patient and fracture characteristics are displayed in Table 2.

Eighty-seven patients (46%) underwent at least one subsequent surgical procedure. The most frequent indication for a first subsequent surgical procedure was screw removal due to irritation or pain (40%), followed by closure of wounds (25%) (Table 3). Twenty-nine patients (15%) underwent at least two subsequent surgical procedures. The most frequent second additional surgical procedures were performed for wound healing (31%), followed by closure of wounds (21%) (Table 3). Thirteen patients (7%) underwent more than two additional surgical procedures.

Patients treated with IMN for TSFs should be consented that about one-in-two patients will undergo an additional surgical procedure. Approximately half of these additional surgical procedures are performed to promote fracture or wound healing. Age, multi-trauma, open fractures and index surgery during weekdays are predictors of this type of additional surgical procedures. The other half of procedures are discretionary: performed to remove interlocking screws and/or tibial nails causing pain or irritation. This type of procedures is less frequently performed in patients with higher ASA-PS and is not associated with tibiofibular screw penetration. These data support the consent of patients with TSFs: that IMN may not be a quick fix.

The findings of this study must be appreciated with an understanding of its limitations. Firstly, a substantial number (22%) of patients had to be excluded due to inadequate follow-up. Although loss to follow-up is a well-known problem in Orthopaedic Trauma [18]; in the current study, this relative high number was partly caused by 8% of patients being followed up externally. This is common practice at our hospital, as our hospital services rural locations more than 1000 km away. Secondly, this study was conducted retrospectively. One of the disadvantages of this design is that the independent variables tested were limited to those that had been collected previously. Potentially important variables such as alcohol abuse [3] could therefore not be included. Thirdly, this study was conducted at a single, level-1 trauma centre. This may have resulted in a slight overrepresentation of high-energy trauma and open fractures. However, since mono-trauma cases are also part of our daily routine practice and represented 80% of the entire cohort, we believe the current series is a good representation of the entire spectrum of tibial shaft fractures. Lastly, limited by the number of events per variable we were forced to group a number of independent variables. This may have concealed the effect of certain variables such as the previously documented effect of transverse fractures on the re-operation rate [4, 5].

The one-in-two reoperation rate (46%) identified in this study is substantially higher than previously reported (14–36%) [3‐6]. This is mainly due to the large number (n = 39) of surgical procedures carried out for symptomatic screw removal, which is not included in the majority of the previously reported studies, but very important in informed consent for our patients in the overall picture. It could be argued that the removal of symptomatic locking screws is a relatively minor surgical procedure; however, from a patients’ perspective any type of surgery is often subjectively considered as major. With an estimated total procedural cost of $2000–2500 (AUD) at our institution, this type of surgery can furthermore have significant impact at a socio-economic level [13]. We therefore believe that it is important for clinicians and patients to be aware of this substantial number. It is important to note that the high rate of implant removal is not exclusive to IMN. In a randomized controlled trial comparing IMN and plate fixation of distal TSFs, the rate of subsequent surgery for implant removal was similar between both groups [19].

It is well known that open TSFs are at a higher risk of infection and non-union [20‐23]. In the current study, open fractures were identified as an independent predictor of subsequent surgery. This is in line with what several previous studies have demonstrated [4‐6] (Table 1). Both younger age and multi-trauma were also predictive of subsequent surgery for wound and fracture healing. Both of these variables may be considered indicative of injury severity. With regard to age, this can be explained by the bimodal distribution of TSFs: in younger patients, they are more often caused by traffic accidents, whereas in elderly patients they are most commonly caused by simple falls [24]. Lastly, surgery on weekdays was an independent predictor of subsequent surgery for wound and fracture healing. When initiating this study, we hypothesized the opposite to be true, as various studies have suggested outcome may be worse if patients are admitted or undergo surgery during the weekend [25‐27]. A possible explanation for our finding could be that there may be a tendency to postpone non-acute, yet complex cases during the weekend to weekdays.

Only one variable was associated with subsequent discretionary surgery to remove symptomatic screws and/or nails: in patients with higher ASA-PS significantly less surgery was performed to remove implant. This is likely explained by surgeons and anaesthesiologists being more cautious with additional surgery in this patient group, rather than there being a causal relationship between ASA-PS and symptomatic screws. On the other hand, it may also indicate that we need to more critically review whether removal of screws and/or nails in patients with an ASA I status is necessary as one could argue that this is elective. Whilst it is suggested that screw penetration in the proximal and distal tibiofibular joint may lead to respective lateral sided knee-pain [17, 28] and lateral sided ankle pain [17], there was no higher rate of removal of these screws in our study. Future studies should aim to assess whether screw penetration in the proximal or distal tibiofibular joint indeed causes pain or affects functional outcome. It is important to note that the interlocking screws which were used in this study have been modified in order to give the screw heads a lower profile. This modification was introduced in our hospital after our final inclusion. Future studies should be performed to assess whether this modification results in lower rates of screw removal.

Although we identified several predictors for subsequent surgery for fracture and wound healing, it remains difficult to extrapolate these findings to the individual patient: we present average results of an ‘extrapolated study population’. Moreover, these predictors have not been validated [29]. In orthopaedic surgery, various studies have recently been published that use a streamlined method for developing, validating and deploying prediction models [30, 31]. The use of machine learning algorithms in these studies furthermore may allow for identifying nonlinear relations between variables [32]. Applying such methods could potentially aid in developing, validating and deploying a more practical prediction model to estimate the risk of subsequent surgery in individual patients with TSFs. This may require larger datasets and could be subject of future studies in our era of personalized care.

The current study could not identify any causal predictors of subsequent surgery for removal of implant. This might mostly be determined by type of implant used and local experiences and protocol. Given the high rate of these surgeries, future studies should aim to assess whether there are any other variables associated with these procedures. Identifying such variables may help modifying treatment in order to decrease the rate of these procedures.

In conclusion, nearly one-in-two patients treated with IMN for TSFs will undergo an additional surgical procedure. Approximately half of these procedures are required for wound and fracture healing, whilst the remaining half are discretionarily performed to remove symptomatic screws or nails. Age, open fractures and multi-trauma were independent predictors of the former, whilst a higher rate of symptomatic implant removal was seen in ASA I patients.