Extensile lateral versus sinus tarsi approach for calcaneal fractures

Abstract Background: Calcaneal fractures are the most common tarsal bone fracture, and are often accompanied by heel pain, local swelling, tenderness, and inability to walk or stand. Surgical intervention results in better reconstruction of the calcaneal anatomy and reduces future complications; however, the optimal incision approach is still controversial. The incision is exposed better with extensile lateral approach (ELA), while the sinus tarsi approach (STA) causes fewer complications. The purpose of this meta-analysis is to compare the outcomes of STA and ELA. Materials and methods: Published trials comparing ELA and STA in calcaneal fractures were included in our analysis. The quality of each study was assessed using the revised Jadad scale and the Newcastle–Ottawa scale. Two researchers (CP and BY) independently extracted data from all selected studies. Fixed- or random-effects models with mean differences and odds ratios were used to pool the continuous and dichotomous variables to determine the heterogeneity of the included studies. Results: Calcaneal height and calcaneal width had high heterogeneity. Results showed that the incidence of incision complications in STA was lower than that in ELA (P < .001). There was high heterogeneity in operative time (I2 = 97%), length of hospital stay (I2 = 98%), Böhler angle (I2 = 80%), Gissane angle (I2 = 98%), and American Orthopaedic Foot & Ankle Society scores (I2 = 73%). No source of heterogeneity was found by sensitivity analysis, subgroup analysis, or regression analysis, and the random-effects model was used. STA operative time was significantly shorter than ELA (P < .001). Length of hospital stay after STA was significantly shorter than after ELA (P = .002). There was no statistical difference in the Böhler and Gissane angles between STA and ELA. Postoperative American Orthopaedic Foot & Ankle Society scores after STA were higher than after ELA (P = .01). Conclusions: Results show that, compared with ELA, STA is superior for treating calcaneal fractures due to anatomical reduction of the calcaneus, reduction of incision complications incidence, and shortened operative time and postoperative stay.


Introduction
Calcaneal fractures are the most common fractures of the tarsal bone, accounting for about 60% of all tarsal fractures. [1] Most patients with calcaneal fractures land on their feet after falling from a height, which causes a vertical impact on the heel. Calcaneal fractures are often accompanied by heel pain, local swelling, tenderness, and the inability to walk and stand. [2] Randomized controlled trials (RCTs) [3,4] and meta-analyses [5][6][7] have shown that surgical treatment is the preferred treatment for calcaneal fractures. And some new techniques are also applied to treat calcaneal fractures. [8,9] Compared with non-surgical treatment, surgery results in better reconstruction of the anatomical structure of the calcaneus and reduces future complications.
Incision-related complications are an important limitation to the generalization of surgical treatment for calcaneal fractures. The traditional surgical approach consists of open reduction and internal fixation through the extensile lateral approach (ELA), [10] where an L-shaped incision directly exposes the fracture site for repair. [11] ELA can easily expose the incision, conducive to anatomical reduction. However, ELA can also damage the blood supply to the corners of the L-shaped flap, causing complications such as wound edge necrosis, nerve damage, and infection. [12][13][14] To this end, clinical researchers have developed several smallincision, minimally invasive reduction techniques. [15] The most common of these is the sinus tarsi approach (STA), which is performed through a small incision in the distal fibula that is anterior to the fibular tendon. While this approach mitigates the damage to the sural nerve and lateral calcaneal artery, some clinicians cite that inadequate exposure may affect the extent of reduction and, ultimately, overall functional recovery. [16] There is increasing interest in this issue, and many metaanalyses have been conducted. [17,9] However, we found errors in the literature inclusion [18] that lead to doubts about the reliability of the conclusions presented from those studies. The present study aims to provide a more valid analysis by updating the literature and excluding inappropriate studies that have previously been used for meta-analysis. Herein, we performed a meta-analysis of STA versus ELA in terms of postoperative calcaneal height, postoperative calcaneus width, complications (marginal necrosis, wound infection, and nerve injury), operative time, postoperative hospital stay, postoperative Böhler angle, postoperative Gissane angle, the American Orthopaedic Foot & Ankle Society (AOFAS)-Ankle Hindfoot Scale score, and comprehensively evaluated the role of STA in the treatment of calcaneal fractures.

Methods
This meta-analysis was designed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines [19] and was registered on the Prospero website (CRD: 42019122640). Analyses were based on previously published studies; thus, no ethical approval and patient consent are required.

Literature search strategies
Two authors (CP and BY) independently searched the online databases PubMed, Embase, and Cochrane on June 28, 2019 for studies comparing ELA and STA in the surgical treatment of calcaneal fractures using internal fixation. The keywords included: calcaneus, (fractures, bone), general surgery, surgical procedures, operative, and surgical wound. There were no restrictions on language, time, or any other parameters of the articles during literature retrieval. Meanwhile, the investigators also manually searched the references of relevant articles.

Inclusion and exclusion criteria
Inclusion criteria consisted of 1) adult calcaneal fracture patients; 2) studies comparing postoperative functional outcomes of calcaneal fractures via ELA and STA; 3) studies reporting at least 1 of the following outcomes: postoperative calcaneal height, postoperative calcaneal width, complications (marginal necrosis, postoperative infection, and nerve injury), operative time, length of hospital stay, postoperative Böhler angle, postoperative Gissane angle, and AOFAS scores; and 4) cohort studies, controlled clinical trials, and RCTs.
Exclusion criteria consisted of 1) animal or cadaver studies; 2) studies in which valid data cannot be extracted or converted; 3) case reports; 4) systematic reviews and meta-analyses; and 5) conference papers without full text.
The 2 authors (CP and BY) independently screened titles and abstracts of the resulting studies based on inclusion criteria and excluded ineligible studies. Subsequently, the authors read the full texts independently to determine whether a study should be included in the final analysis. Any discrepancies that occurred were resolved through discussions with a third author until a consensus between all 3 authors (HT) was reached.

Outcome measures
The primary outcomes include calcaneal height, calcaneal width, and the complications (marginal necrosis, wound infection, and nerve injury), and the secondary outcomes include operative time, length of hospital stay, Böhler angle, and Gissane angle.
Calcaneal height and width are 2 important outcome indicators for predicting postoperative functional recovery. Calcaneal height is a radiographic parameter measured on the lateral radiographic view from the most posterior point of the tuberosity to the calcaneocuboid joint. There are 3 parts that should be calculated about the width of the calcaneus, including the width of the anterior calcaneus, middle calcaneus, and posterior calcaneus. The width of the calcaneus is defined as the horizontal line of each part on the same axial plane. And the loss of height and width of the calcaneus predicts postoperative dysfunctions, such as walking pain and varied load-bearing point of the heel.
Incision-related complications, operative time, and postoperative hospital stay are important considerations for the clinical application of STA. All these outcomes can be found after the surgery of calcaneal fractures, often used as indicators of recovery time.
The Böhler angle is an imaging index that serves as an anatomical landmark for the posterior articular surface of the subtalar joint. A decrease in the Böhler angle indicates a collapse of the load-bearing posterior articular surface of the calcaneus, which subsequently moves the center of gravity of the body forward and reduces the calcaneal height. The Gissane angle represents the angle between the anterior and posterior articular surfaces of the calcaneus. An increased Gissane angle indicates a collapse of the posterior surface of the calcaneus.
The AOFAS rating scale is used to score postoperative function; the maximum potential score is 100 points, and a score of 75 points or more is excellent. [13,14,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] 2.4. Data extraction Two authors (CP and BY) independently extracted the data from each study that met the inclusion criteria. The following outcome measures were collected: postoperative calcaneal height, postoperative calcaneal width, complications (marginal necrosis, postoperative infection, and nerve injury), operative time, length of hospital stay, postoperative Böhler angle, postoperative Gissane angle, and AOFAS scores. Baseline data included: study time, type of study, mode of internal fixation, number of feet, the average age of patients, male to female ratio, and follow-up time. Discrepancies were resolved by discussions with a third author until an agreement was reached by all 3 authors (HT). We contacted the original authors via email to obtain the data that was not available in the original.

Quality assessment
Two authors (CP and BY) independently assessed the quality of the included literature using the modified Jadad scale for RCTs where scores 1 to 3 are considered low quality and scores 4 to 7 are high quality. [36] Cohort studies were assessed using the Newcastle-Ottawa Scale, [37] where scores 1 to 4 are considered low quality and scores 5 to 9 are high quality. Discrepancies were resolved by discussions with a third author (HT) until all 3 authors agreed.

Statistical analysis
Review Manager (Version 5.3) and Stata (Version 14) were used for data analysis. Dichotomous variables were assessed using risk  [20] 2012.  [22] 2014.  [24] 2009.  [28] 2012.  [29] 2004.  ratios and 95% confidence interval (CI). Continuous variables were analyzed as the mean ± standard deviation and 95% CI. A value of P < .05 was considered statistically significant, and I 2 values were calculated to assess heterogeneity across the studies. An I 2 < 50% was considered low heterogeneity, and a fixedeffects model was used. An I 2 > 50% indicated high heterogeneity, and the source of heterogeneity was determined through sensitivity analysis, subgroup analysis, and regression analysis. If the heterogeneity could not be reduced, a random-effects model was used. Sensitivity analysis was performed by removing the included studies one by one. Subgroup analysis was conducted based on different types of internal fixation, where there were 5 subgroups, including 1) ELA plate fixation vs STA screw fixation, 2) ELA plate fixation vs STA plate fixation, 3) ELA screw fixation vs STA plate fixation, 4) ELA mixed fixation vs STA screw fixation, and 5) ELA plate fixation vs STA mixed fixation. Egger test was used to check for publication bias if more than 10 articles were included in the data analysis.

Results
After an initial search, 726 articles were available from the following databases: 149 from Embase, 553 from PubMed, and 24 from Cochrane. We manually searched references of the 21 additional related articles. A total of 111 duplicate articles were removed, and another 570 articles were excluded by screening titles and abstracts. The remaining 66 articles were enrolled for full-text review, and an additional 48 articles (42 contentunrelated and 6 outcome-unrelated articles) were excluded thereafter. Thus, 18 articles were included in the final analysis (details of the literature selection are shown in Fig. 1).  Test for overall effect: Z = 5.06 (P < 0.00001)
Of the 6 RCTs, there was 1 low-quality study [34] that did not describe the method of random number generation and 5 highquality studies. Of the 12 cohort studies, 2 low-quality studies did not depict researcher choices clearly, [25,27] and the other 10 were high-quality studies.

Complications
Three common postoperative complications, including marginal necrosis, wound infection, and nerve injury, were analyzed by subgroup analysis. The results showed that the incidence of incision complications in STA was lower than that in ELA (OR = 0.25; 95%CI: 0.17, 0.36; P < .001) (Fig. 4).

ELA with plate and STA with screw
Alex J2013

ELA with plate and STA with plate
Bin Jia2017 ChengL2017 Jinti Lin2019

ELA with plate and STA is mix
Zhou HC2017

Total (95% CI)
Heterogeneity: Tau²    fixation) found no difference in the length of hospital stay between the 2 groups. There was poor stability in the outcomes as an inconsistent type of internal fixation was used in the control group. This may be caused by the high rates of complications after ELA surgery.

ELA with plate and STA is mix
Zhou HC2017

Discussion
Our meta-analysis showed that surgical treatment utilizing an STA can effectively reduce incision-related complications, operative time, and hospital stay in patients with calcaneal fractures, which is similar to some other articles. [18] However, this approach has similar therapeutic effects compared with ELA in terms of calcaneal height, calcaneal width, Gissane angle, Böhler angle, and AOFAS score. A calcaneal fracture is the most common type of humeral fractures, and secondary diseases include traumatic arthritis, Achilles tendinitis, and tendonitis. [2] Patients suffer from foot pain and movement disorders, and present with abnormal gait or claudication due to the abnormality in the whole force line of the foot, manifested as reduced foot arch and calcaneus valgus. [2] Therefore, effective treatments are particularly important for calcaneal fracture patients. Conventional treatments include nonsurgical and surgical options, and in recent years, surgical treatment for calcaneal fractures has become the preferred method. However, there is still a large dispute over the optimal surgical incisions and approaches. In the traditional ELA, an Lshaped incision of 8 to 10 cm is made to fully expose the fracture site, the subtalar joint, and bone tissue at the inner calcaneal wall, which is convenient for direct reduction and strengthening fixation of the fracture. [38,39] In STA, a small incision of 3 to 4 cm is made parallel to the sole of the foot to expose the fracture, which is believed to better protect the blood supply and nerves around the incision. However, some researchers believe that, compared with ELA, an STA does not have obvious clinical advantages, [40] especially in the recovery of important anatomical landmarks (calcaneal height, calcaneal width, Gissane angle, and Böhler angle). [17,40,9] In addition, STA has less exposure to the fracture compared with ELA, which may result in decreased ability to ensure a proper anatomical reduction of the calcaneus and subtalar joints, and even influence long-term functional recovery. [41,42] Even more compelling is the evidence that STA may increase wound complications. [43] However, our metaanalysis showed that both surgical approaches were effective in reducing calcaneal fractures, and STA was not worse than ELA in restoring calcaneal height, calcaneal width, Gissane angle, and Böhler angle. Despite shortened operative times and hospital stays and reduced postoperative incision-related complications, STA had no obvious advantages in the long-term functional score at present. Further clinical trials are needed for verification.
In this study, primary outcome measures included calcaneal height, calcaneal width, and postoperative wound-related complications, including marginal necrosis, nerve injury, and wound infection. Compared with ELA, STA causes fewer wound complications due to the smaller surgical incision that avoids important vascular nerve structures and has less interference with bones and soft tissues around the fracture. The long incision used for ELA is more likely to damage the peroneal artery and its branches, resulting in insufficient blood supply to the lateral skin and a higher incidence of wound complications. [43] We found high heterogeneity between the 2 groups in terms of calcaneal height and calcaneal width, However, sensitivity analysis showed that when excluding Jia et al, [21] the heterogeneity was significantly reduced. There was no statistically significant difference between the 2 groups after the removal of heterogeneous sources.
In this study, there was shortened operative time with STA, which may be due to the fact that it is unnecessary to be overly careful when utilizing a small incision. In addition, the STA group had a shorter postoperative hospital stay when compared to the ELA group with longer incisions. In the latter group, much more soft tissue was damaged, accompanied by more severe incision complications, which subsequently resulted in a more complex recovery. The results of the meta-analysis showed no significant difference in Böhler and Gissane angles between STA and ELA. This indicates that although the incision in STA incision was smaller and operative time was shortened, STA did not affect the anatomical reduction of the calcaneus.
In this meta-analysis, AOFAS scores were used to assess postoperative functions, including pain, range of motion, walking distance, and stability. Previous studies have shown no significant difference in functional recovery between the 2 surgical approaches. [17,9,25,26,29,40,44] ELA can fully expose the fracture site for a more comprehensive treatment of calcaneal injuries (especially subtalar joint injuries), at the expense of higher incision complication incidence and longer hospital stay. STA can mitigate some troubles in postoperative recovery, at the expense of a potential impact on the anatomical reduction of the calcaneus and subtalar joints due to limited surgical exposure. However, STA revealed no disadvantage in terms of anatomical reduction. Our meta-analysis data showed that the AOFAS score in the STA group was significantly higher than that in the ELA  group. In other words, postoperative functional recovery was better after STA, consistent with the results of Zeng et al. [18] However, our subgroup analysis showed no difference between ELA and STA in terms of ELA plate fixation vs STA screw fixation, ELA plate fixation vs STA plate fixation, and ELA mixed fixation vs STA screw fixation. Only ELA plate fixation vs STA mixed fixation showed the AOFAS score was higher in the STA group than the ELA group. However, this group contained only 2 studies and STA mixed fixation may result in poor stability of the experimental results, meaning that this result should be treated with caution.

Limitations
This meta-analysis only collected 6 RCTs (the rest being cohort studies), which may have biased the collected data. Additionally, the number of patients in some included studies is small, [14,20,34,35] which may lead to unreliable results in the meta-analysis.

Strengths
In this meta-analysis, we established strict criteria for literature inclusion and exclusion, excluded inappropriate studies contained in previous meta-analyses, and only included RCT and cohort studies. During data analysis, we adopted various analytical methods such as sensitivity analysis, subgroup analysis, and regression analysis. In particular, we grouped the studies according to the types of research and internal fixation for subgroup analyses. This study is currently the most comprehensive meta-analysis concerning the outcomes of calcaneal fractures.

Conclusions
Our meta-analysis results show that, compared with ELA, an STA is superior in the treatment of calcaneal fractures, due to effective anatomical reduction of the calcaneus, effective reduction of the incidence of incision complications, and shortened operative time and postoperative hospital stay.
Author contributions