Syndesmosis screw breakage: An analysis of multiple breakage locations

Abstract

Introduction/purpose

Concerns have been raised about screw breakage within the tibia or fibula, referred to as intraosseous breakage. The purpose of this investigation is to analyze the technical aspects of syndesmotic screw placement in multiple anatomic breakage locations.

Materials

A retrospective analysis of over 1056 patients who underwent syndesmosis fixation was completed. Demographics, screw length, width, number, height above the tibial plafond, angle, breakage location, and breakage location on the screw were collected and analyzed.

Results

Intraosseous (IO) screw breakage (91 screws, 68 patients) was more common than clear space (CS) breakage (28 screws, 18 patients) (P = < 0.001). Within the IO group, screw breakage within the tibia (60 screws, 52 patients) was more common compared to fibula breakage (29 screws, 24 patients) (P = < 0.001).

Increased BMI and the use of multiple screws were associated with IO breakage (P = .007) and CS breakage (P = .012), respectively. Increased screw angle and age were associated with fibular IO breakage (P = .021, P = .036) when compared to other IO breakage locations. Screw angle and placement showed no significant differences between compared groups (P = .629, P = .570).

Conclusion

Syndesmosis screw breakage, overall, occurred more commonly in an IO location. When compared to IO breakage, the use of multiple syndesmosis screws is most associated with CS breakage. Increased BMI is associated with increased IO breakage when compared to CS breakage. Patients with IO screw breakage within the fibula had increased age and placed at a higher angle when compared to other IO breakage locations. No other factors related to screw placement, including the height of placement, were found to be significantly associated with location of screw breakage.

Highlights

• •Syndesmosis screw breakage, overall, occurred more commonly in an IO location.
• •When compared to IO breakage, the use of multiple syndesmosis screws is most associated with CS breakage.
• •Increased BMI is associated with increased IO breakage when compared to CS breakage.
• •Patients with IO screw breakage within the fibula had increased age and placed at a higher angle.
• •No other factors related to screw placement were found to be significantly associated with location of screw breakage.

1. Introduction/Purpose

Ankle fractures remain one of the most common fracture types, representing up to 50% of all lower extremity fractures.¹ Among those that are treated operatively, 15%–20% are accompanied by a syndesmotic injury that requires reduction and internal stabilization to provide optimal outcomes.2, 3, 4, 5 Surgical fixation with either suture button devices and metal screws remain the most used fixation methods.^6,7 Metal screws have been used for decades and remain the fixation of choice for many surgeons, although suture button devices are gaining popularity.^8,9 Well-known complications following screw fixation include symptomatic screw breakage, syndesmotic mal-reduction, and additional surgery for removal.10, 11, 12, 13, 14

There remains variability in practice as to retain or to routinely remove intact syndesmotic screws. Many studies have examined outcomes following screw removal versus retention, with the majority showing no clinically significant improvement in outcomes following routine screw removal.15, 16, 17, 18 Metal screws, when retained, may eventually result in clinically significant or asymptomatic loosening or breakage.¹⁰ Breakage of retained screws theoretically provides restoration of physiologic motion between the tibia and fibula and has been thought to be of little clinical significance when compared to non-broken screws.^19,20

Recently, concerns have been raised about screw breakage within the tibia or fibula, defined as intraosseous (IO) screw breakage.^21,22 Syndesmosis screws may also break in the clear space (CS), defined as the space between the tibia and fibula. Although traditionally reported to be clinically insignificant, screw breakage has been shown to lead to pain depending on location in some patients.²² Anatomically, broken syndesmosis screws that span the incisura are at an especially increased risk for painful outcomes. In patients with intraosseous screw breakage, normal physiologic translation in which the distal convex of the fibula fits into the concave tibial incisura can lead to painful bony erosion overtime.²³

Currently, there is very little information available regarding how the technical aspects of syndesmotic screw placement may influence anatomical location of syndesmotic screw breakage. Both technical surgical variables and differing patient characteristics may influence syndesmotic screw breakage rate and breakage location. Technical aspects of surgical screw placement may vary based surgeon preference and from case to case, as such, variability often exists in the screw width, screw length, number of screws used, the number of cortices engaged, screw placement above the tibial plafond, and the screw angle relative to the tibial plafond. Likewise, patient characteristics including gender, time to full weight bearing, body mass index (BMI) also differ in each individual case. Therefore, the purpose of this investigation is to compare technical surgical variables and patient characteristics in patients with different syndesmotic screw breakage locations.

Many biomechanical studies exist which focus the impact of screw placement, specifically focused on screw position relative to the plafond.24, 25, 26, 27, 28 Clinical studies have investigated such variables with screw width and placement above the plafond being the primary focus, however screw breakage was not analyzed.^29-30 While others have attempted to compare risk factors for clear space syndesmosis breakage versus intraosseous breakage.²² As such, additional investigation comparing different anatomical locations of syndesmotic screw breakage would shed light on a nearly unstudied topic.

To the best of our knowledge, no study has attempted to compare technical surgical variables and patient characteristics between the multiple breakage locations presented here. We hypothesize that IO screw breakage will occur more frequently than CS and that height of screw placement of above tibial plafond will have larger impact on breakage location when compared to the angle of screw placement relative to the tibial plafond.

2. Materials & methods

A retrospective analysis of all patients undergoing syndesmosis fixation from January 1, 2008 to December 17, 2020 was performed. Institutional review board approval was obtained prior to initiating the investigation. All patients who underwent an ankle fracture or injury that required surgical fixation were reviewed for potential syndesmosis disruption. Post-operative radiographic evidence of screw breakage was required for inclusion. Any patient with syndesmosis fixation using suture-button, intraoperative screw breakage, and placement of a syndesmosis screw for reasons other than stabilization of the syndesmosis were excluded. Patient demographic data, BMI, screw length, width, number, placement height above the tibial plafond, angle, location of breakage, and breakage distance location on the screw were all collected for analysis.

Patients were analyzed based a syndesmosis screw breakage location including IO, CS, IO + CS. The IO was subsequently broken down into tibia only, fibula only, and tibia + fibula groups for further analysis. See Fig. 1. A, B, C, D, E.

Fig. 1.

A, B, C, D, E. (A) Intraosseous screw breakage within tibia only. (B) Intraosseous screw breakage within fibula only. (C) Clear space breakage only. (D) Intraosseous screw breakage within the tibia and fibula. (E) Intraosseous and clear space breakage with intraosseous breakage within the fibula and tibia.

Many variables required radiographic evaluation, including screw height above the tibial plafond, angle of each screw relative to the tibiotalar joint, and screw breakage distance from the clear space. All measurements were done using our institution's picture archiving and communication system (PACS). All screws were measured prior to screw breakage using mortise radiographs taken at the patient's first postoperative visit. Subsequent measurements of breakage location were made using mortise radiographs following the initial discovery of the breakage.

Radiographic measurement of the screw breakage location was measured both from the clear space and the lateral most aspect of the fibula to break on the syndesmotic screw. All reported IO breakage distances were measured as the distance between the breakage location on the screw and the medial most aspect of the clear space. When comparing IO breakage versus CS breakage the lateral most aspect of the fibula was used as a reference point. The angle and height of screw placement were both measured using plain mortise and anterior-posterior (AP) radiographs with the tibial plafond as a reference point. The screw angle was measured within the coronal plain using a 90-degree angle created by using the tibial plafond and a line extending to the screw serving as a reference point. Any deviation from the 90-degree angle was used to measure the angle of screw placement. All measurements were made in both the mortise and AP views, however, there was no statistical difference between the two measurements and the mortise measurements were used for reporting. Examples of each measurement are depicted in Fig. 2. A, B. Fig. 3. A, B.

Fig. 2.

A, B. Broken intraosseous screw within the tibia. Screw breakage was measured from the first available radiograph showing the breakage. (A) Breakage distance measured from the clear space to screw breakage point (B) Breakage distance measured from the fibular plate to screw breakage point.

Fig. 3.

A, B. (A) Screw angle relative to the tibial plafond (tibial talar joint). The angle measured (red square) and the reference 90-decgree angle (black) are shown. (B) Height of screw placement relative to the tibial plafond (tibial talar joint). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

All patients were treated at our institution by orthopedic surgeons well-equipped to treat ankle fractures. Decisions regarding screw size, number, cortices used, placement location, were all made by these surgeons using their best clinical judgement. The diagnosis of syndesmotic disruption was made using radiographic evidence including clinical indications, radiographic indicators such as tibiofibular overlap, tibiofibular clear space, talar tilt, contralateral ankle imaging and intraoperative indictors such as fluoroscopic stress-testing and hook testing were all used. Following adequate restoration of fibular length and subsequent screw fixation, satisfactory syndesmotic reduction was determined using intraoperatively mortise and AP radiographs.

All patients were kept non-weight bearing with routine physical therapy during the first 6 weeks post-operatively. A gradual progression to unrestricted weight bearing status no earlier than 12 weeks was advised. Patients were seen in the clinic at 2, 4, 6, 12 weeks, and as needed post-operatively.

3. Statistics

All statistical analysis was completed using SPSS version 23 (IBM Corporation, Armonk, NY). The initial analysis included three groups based on screw breakage location: Intraosseous (IO), Clear Space (CS), or a combination (CS + IO). Any screw with a breakage location within the fibula or tibia or both were included in the IO group. Any screw with a breakage location between the fibula and tibia was included in the CS group (Table 1).

Table 1.

Patient and screw data (Clear Space breakage versus Intraosseous breakage).

Variable	Clear Space (CS)	Intraosseous (IO)	CS + IO	p-value
Patients (n)	18	68	2	<0.001
Screws (#)	28	91	2	<0.001
Time from surgery to breakage (weeks)	46.13	48.67	60.56	0.595
Patient Characteristics
Age	36.2	39.8	37.0	0.27
Male, n (%)	11 (61.1%)	33 (48.5%)	1 (50%)	0.430
Female, n (%)	7 (38.9%)	35 (51.4%)	1 (50%)
BMI	31.07	34.27	34.25	0.021
Screw Characteristics (averages)
Screw length (mm)	53.43	52.57	52.5	0.180
Screw width (mm)	3.75	3.64	3.5	0.121
Number of cortices	3.48	3.30	4	0.107
Number of screws broken	1.79	1.61	2	0.282
Breaks in each screw	1.04	1.033	2	0.6297
Angle tibial plafond (degrees)	94.41	94.84	86.7	0.875
Height of screw placement (mm)	21.21	19.74	32.06	0.493
Screw placement height >20 mm	17	31	2	0.657
Breakage distance from distal fibula	9.53	18.5	9.49, 21.61	0.1271

*Screws with >1 fracture occurring in different locations were included within each breakage location.

When comparing IO versus CS breakage Chi-square analysis was used to assess categorical variables between groups and student's t-test was used for numerical variables. Likewise, when comparing tibia, fibula, and tibia + fibula breakage the Fisher exact test and the student's test were used. A binomial regression was used to assess several independent variables relative to their ability to predict breakage location, IO versus CS (Table 2). Further analysis was then completed by separating the intraosseous group based on location; tibia, fibula, tibia + fibula (Table 3). A subsequent binomial regression was performed to assess the same independent variables' ability to predict breakage location within the fibula and tibia (Table 4).

Table 2.

Multiple linear regression (Intraosseous breakage versus Clear Space breakage).

	Intraosseous (IO)				Clear space (CS)
Variable	Sig.	Odds Ratio	95% C.I.		Sig.	Odds Ratio	95% C.I.
			Lower	Upper			Lower	Upper
BMI	0.007	1.138	1.035	1.251	0.007	0.879	0.799	0.966
Number of screws	0.012	0.036	0.003	0.477	0.012	28.073	2.095	376.132
Breakage distance from distal fibula	0.024	0.905	0.83	0.987	0.024	1.105	1.013	1.204
Breakages in each screw	0.047	20.366	1.042	397.881	0.047	0.049	0.003	0.959
Screw width (mm)	0.215	0.385	0.085	1.743	0.215	2.598	0.574	11.764
Age	0.284	1.021	0.983	1.06	0.284	0.98	0.943	1.017
Number of screws broken	0.465	0.631	0.184	2.168	0.465	1.584	0.461	5.439
Angle	0.57	1.015	0.965	1.068	0.57	0.985	0.937	1.037
Time from surgery to breakage	0.577	0.996	0.984	1.009	0.577	1.004	0.991	1.016
Height of screw placement (mm)	0.629	1.016	0.952	1.084	0.629	0.984	0.923	1.05
Gender	0.67	0.745	0.193	2.875	0.67	1.341	0.348	5.174
Number of cortices	0.705	1.255	0.386	4.081	0.705	0.797	0.245	2.59
Screw length (mm)	0.962	0.997	0.887	1.121	0.962	1.003	0.892	1.127

Table 3.

Patient and screw data (Tibia breakage versus Fibula breakage).

Variable	Tibia	Fibula	Tibia + Fibula	p-value
Patients (n)	52	24	2	<0.001
Screws (#)	60	29	2	<0.001
Time from surgery to breakage (weeks)	46.13	48.67	60.56	0.218
Patient Characteristics
Age	36.97	46.28	37.0	0.0321
Male	24 (46.2%)	12 (50%)	2	0.8081
Female	28 (53.8%)	12 (50%)	0
BMI	33.46	35.9	28.9	0.241
Screw Characteristics (averages)
Number of screws used	1.89	2.21	2	0.097
Screw length (mm)	53.1	50.65	52.5	0.056
Screw width (mm)	3.62	3.7	3.5	0.323
Number of cortices	3.29	3.33	4	0.783
Number of screws broken	1.53	1.79	2	0.132
Breaks in each screw	1.02	1.03	2	0.432
Angle tibial plafond (degrees)	93.05	99.65	86.7	0.021
Height of screw placement (mm)	21.05	17.71	32.06	0.145
Screw placement height >20 mm	31	13	2	0.696
Breakage distance from CS	7.74	7.81	9.49, 21.61	0.956

*Screws with >1 fracture occurring in different locations were included within each breakage location.

Table 4.

Multiple linear regression (Tibia breakage versus Fibula breakage).

	Tibia				Fibula
Variable	Sig.	Odds Ratio	95% C.I.		Sig.	Odds Ratio	95% C.I.
			Lower	Upper			Lower	Upper
Age	0.036	0.96	0.924	0.997	0.036	1.042	1.003	1.082
Breakages in each screw	0.055	0.132	0.017	1.042	0.055	7.551	0.959	59.439
Screw width (mm)	0.083	0.222	0.04	1.219	0.083	4.506	0.821	24.737
Screw length (mm)	0.096	1.122	0.98	1.286	0.096	0.891	0.778	1.021
Angle	0.228	0.964	0.908	1.023	0.228	1.038	0.977	1.102
Height of screw placement (mm)	0.313	1.035	0.968	1.106	0.313	0.966	0.904	1.033
Number of screws broken	0.407	0.546	0.13	2.287	0.407	1.832	0.437	7.68
Complication	0.495	0.594	0.133	2.655	0.495	1.684	0.377	7.53
Gender	0.529	1.571	0.384	6.429	0.529	0.636	0.156	2.604
Time from surgery to breakage	0.598	0.998	0.989	1.009	0.598	0.998	0.989	1.009
Breakage distance from CS	0.605	0.98	0.91	1.057	0.605	1.02	0.946	1.099
BMI	0.736	0.988	0.92	1.061	0.736	1.012	0.943	1.087
Number of screws	0.782	0.806	0.174	3.73	0.782	1.241	0.268	5.748
Number of Cortices	0.844	0.888	0.272	2.9	0.844	1.126	0.345	3.678

4. Results

In total, 1056 patients were identified who underwent syndesmotic fixation. After excluding patients who did not meet inclusion criteria, a cohort of 88 (8.3%) patients who experienced syndesmosis screw breakage remained. This cohort included 45 males and 43 females who received a total of 121 screws. The average age and body mass index (BMI) of all patients was 39.19 years and 33.63 kg/m², respectively. The average time from surgical fixation to syndesmosis screw breakage was 50.59 weeks (range, 12.4–257.57 weeks). Of the patients treated with a single syndesmotic screw, 23 were treated with 3.5 mm screws and 6 were treated with 4.5 mm screws. In the patients treated with multiple screws, 72 screws were 3.5 mm and 18 were 4.5 mm.

Of the 121 broken screws, 91 (75.2%) broke within an IO location (68 patients, 77.3%). Sixty screws (52 patients, 59.9%), broke within the tibia, while 29 screws (24 patients 27.7%) broke within the fibula. Twenty-eight screws (23%.1) (18 patients, 20.5%) broke exclusively within the clear space (CS). Two screws (2 patients, 2.27%) broke within an IO location and the CS.

The average screw length was 52.57 mm (range, 40–70 mm). Most of the screws used were 3.5 mm in width (80.99%). Twenty-three screws (19.0%) were either 4.5 mm or 4.0 mm in width. Twenty-nine (23.97%) of screw breakages occurred with only one syndesmosis screw placed versus 96 (76.0%) when multiple screws were used.

An increased BMI was associated with an increased risk of IO screw breakage compared to the CS (P = .007). An increased mean age was seen between patients with IO tibia breakage (46.28) and those with IO fibula breakage (36.97) or both tibia and fibula breakage (37.0) (P = .0321) (P = .036) (Table 3) (Table 4). The use of multiple screws was associated with an increased risk for CS breakage (P = .012) (Table 2). An increased angle of screw placement was associated with increased risk of IO screw breakage within the fibula when compared to tibia breakage (P = .021). Notably, screw angle and height had no other statistically significant effect on screw breakage location (P = .629, P = .570) (Table 2).

5. Discussion

Syndesmosis screw breakage has previously been considered to have equivalent or, in some reports, improved clinical outcomes. In some ways this has led to a view that syndesmosis screw breakage is of little significance or inconsequential clinically. However, there is evidence that patients who experience screw breakage are at risk for pain and/or functional limitation which may ultimately necessitate screw removal in some patients. However, any surgery, including screw removal, is not a benign procedure and, as such, is associated with significant risks and costs^14,22 Currently, existing literature has very little to offer with regards to the impact of syndesmosis breakage location in such patients. There is even less information regarding how the technical aspects of surgical placement and patient characteristics may influence where a syndesmosis screw breaks. To the best of knowledge, no study has compared breakage in multiple intraosseous locations, the clear space, and the combination of the two based on the technical aspects presented here.

To date, patients have often been reported to have better outcomes following syndesmosis screw breakage, however, upon further review of the existing we provide evidence for further investigation. For instance, Boyl et al. conducted a prospective randomized study comparing syndesmotic screw retention versus removal over the course of one year. The authors conclude that screw removal has no effect on 12-month outcomes nor is it necessary when screws are broken or loose. The reported findings are based on a syndesmosis screw retention group consisting of 23 patients, in which 4 patients with intact screws and 19 with loose or broken screws are compared. However, within the loose/broken screw group only 9 patients had confirmed screw breakage while the remaining 10 patients had screws that were only loose or were removed without report on whether the screws were broken prior to removal. Due to the heterogeneity of the broken/loose group and only 9 confirmed screw breakage cases compared which were compared to only 4 confirmed intact screws it is difficult to definitively conclude screw breakage has improved outcomes.

Similarly, Manjoo et al. performed a retrospective evaluation of clinical and radiographic outcomes comparing intact, removed, and broken/loose screws in which the authors conclude that patients with broken/loose screws have improved outcomes.²⁰ In this study, there was no mention of the number of solely broken screws within the broken/loose group. Again, the heterogeneity and lack of reporting on solely broken syndesmotic screw makes a definitive conclusion difficult. In contrast, Hamid et al. performed a retrospective review of 52 patients, in which the authors do delineate the exact number of broken screws.¹⁹ In this comparison of broken, intact, and planned screw removal the broken group consisted of 10 patients. It was found that patients with broken screws had higher AOFAS scores after a mean follow-up of 30 months. In this study, no difference was reported between groups using the visual analog scale (VAS) (P = .217). Although the AOFAS group difference statistically significant (P = .0466), it was very close to not being significant. This combined with a broken screw group consisting of only 10 patients provides reason for hesitation. In all three studies there was no mention of breakage location.

IO syndesmosis screw breakage has been reported to lead to painful bony erosion secondary the physiologic movement of the tibia and fibula.²⁸ A 2020 investigation by Ibrahim et al. reported increased rates of removal following IO syndesmosis screw breakage secondary to pain when compared to CS breakage. This together with the previously stated concerns regarding the commonly cited studies as evidence for improved outcomes following syndesmosis screw breakage, warrant further examination of the effect of broken screws may or may not have. Although screw breakage occurs in a relatively small cohort of patients, it is important to address any complication in patients who may suffer pain, functional limitations, or hardware removal, following any orthopedic procedure. Hardware removal is a complication that is specifically unwelcome as it the technique is difficult and can result in many unwanted complications.²⁶ Additionally, it remains important to further analyze screw breakage as routine removal remains unsupported in the literature and surgeons are increasingly electing to leave syndesmotic screw in situ which may lead to an increased incidence in the near future.

In the study by Ibrahim et al., 531 patients with syndesmotic fixation, of which, 43 patients (8.1%) experienced syndesmosis screw breakage consisting of 32 IO breaks and 11 CS breaks were examined. The authors concluded that the placement of screws at least 20 mm above the tibial were more likely to break within the CS, while screws placed closer to the tibial plafond were at increased risk of intraosseous breakage.²² All other variables that were analyzed showed no significant differences including age, BMI, gender, number of screws, screw diameter/length, and cortices engaged. Interestingly, our analysis does not support this conclusion and we report no statistically significant differences in breakage location based the height of screw placement. Rather, we report that CS breakage was associated with an increased number of syndesmosis screws used when compared to IO breakage. Ibrahim et al. found no differences in breakage location based on screw angle when comparing IO and CS breakage. Likewise, we report no difference between IO, CS, and IO + CS breakage. We did, however, report that a higher angle of screw placement was associated with IO breakage within the fibula when compared tibia breakage or the combination of the two. However, screw width and screw length were not found to be significant factors.

In our study, other significant factors found to influence breakage location included increased age, which was also associated with an increased risk of IO breakage within the fibula and BMI. Patients with increased BMI were at increased risk of IO screw breakage when compared to CS breakage. Our institution has previously described a small cohort of patients with broken syndesmosis screws.²⁴ The patients in this cohort were found to have an average BMI of 38.92± (22.05–56.34), consistent with Grade II obesity. Additional research by Mendelsohn et al. supports the idea that increased BMI is also associated with increased overall risk of syndesmosis screw failure.²⁵ The findings of this study may provide evidence that patients with an increased BMI and are at higher risk of IO screw breakage. Age and occupation status should also be taken into consideration when evaluating syndesmosis screw breakage. Occupation was not reported consistently by all patients and was unable to be assessed in our study. Occupational differences between patients may influence breakage location in addition to overall breakage risk. As stated previously, the only difference reported here based on age is that patients with IO fibula breakage were on average older than those with IO tibia breakage.

There are many clinical implications and potential applications as a result of this study. As discussed, syndesmotic screw breakage may lead to differing complications and outcomes based on location. In addition, increased awareness of the impacts of breakage locations, surgeons may better council patients based on breakage location. Specifically, patients with increased BMI are at a higher risk of IO breakage, which may increase their risk for unwanted complications due to bony erosion and should receive appropriate pre- and post-surgical counseling. Based on our results, surgeons should not be concerned that screw angle within the coronal plane or the height of screw placement will impact breakage location. Conversely, surgeons should not place screws at an increased height to increase the likelihood of a sought-after CS breakage when using newer screw designs that encourage breakage within the CS.²¹ Likewise, our results suggest an increased angle and age may encourage breakage within the fibula when compared to tibia breakage and should both be kept in mind when screws encouraging CS breakage and operating on older patients. However, the findings are not supported when comparing IO and CS breakage as whole, therefore, more research is encouraged. As more research becomes available based on breakage location its impact on clinical outcomes the findings presented here can further guide clinical practice.

Our study is not without limitations. The data presented here reveals many findings within a cohort of patients with broken screws; it does not compare screw breakage to patients without breakage. As such, we are only able to comment on the variables that differ between each breakage site and our findings cannot be extrapolated to the overall risk factors of screw breakage. Future investigations should examine the associations of these risk factors in both patients with and without broken syndesmosis screws to overcome this limitation. Additionally, only 88 patients were found to meet inclusion criteria. This further raises the question as to underlying differences between these patient populations, and future research should examine these differences. Finally, due to the nature of the plain radiographs and lack of computerized tomography (CT) imaging in enough patients to statistically compare, we were unable to account for angulation in the transverse plane. Current recommendations suggest syndesmosis screws should be inserted between 25 and 30° relative to the coronal plane. At our institution, no surgeon deviates from the current recommendations.

6. Conclusion

Syndesmosis screw breakage, overall, occurred more commonly in an IO location. When compared to IO breakage, the use of multiple syndesmosis screws is most associated with CS breakage. Increased BMI is associated with increased IO breakage when compared to CS breakage. Patients with IO screw breakage within the fibula had increased age and placed at a higher angle when compared to other IO breakage locations. No other factors related to screw placement, including the height of placement, were found to be significantly associated with location of screw breakage.

Declaration of competing interest

The authors declare that they have no conflicts of interest in the creation and publication of this manuscript and received no funding to assist in its completion.