Effect of Tourniquet Application on Postoperative Outcomes in Minimally Invasive Surgery for Intraarticular Calcaneus Fractures

Background: Tourniquets are commonly used during foot and ankle surgery to provide a bloodless operative eld and for the sake of the surgeon`s comfort, despite the potential risks associated with it. This study was performed to compare postoperative outcomes of tourniquet-assisted to non-tourniquet-assisted operative xation of calcaneal fractures. Methods: A total of 131 patients with closed calcaneal fracture who underwent minimally invasive surgery of calcaneal fractures between March 2015 and December 2018 were reviewed retrospectively. Patients for whom a tourniquet was used intraoperatively (n = 62) were compared to those without (n = 69). Operating time and visualization, blood loss, postoperative pain according to visual analogue scale (VAS), the American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot score, and hospital length of stay were recorded for all the patients. Results: Statistical analysis of the results showed signicant differences between tourniquet and non-tourniquet groups in the mean operation time, visibility of the surgical eld, mean estimated intraoperative and postoperative blood loss, and mean VAS pain scores 24 H, 48 H, 72 H postoperatively (P < 0.05), whereas no signicant difference between two groups in the mean Serum CPK levels, postoperative swelling, mean length of stay, AOFAS score, wound and fracture healing time, and the mean time for return to work. Conclusion: Our study demonstrated that tourniquet application during minimally invasive surgery of calcaneal fractures can signicantly shorten the operation time, improve surgical visualization, and reduce intraoperative blood loss. However, adverse events associated with the use of tourniquet include increased postoperative pain, and more amount of postoperative bleeding. Due to higher postoperative pain and more amount of postoperative bleeding, more attention should be paid on the postoperative phase for those who tourniquet was used. The surgeon's decision to use a tourniquet during calcaneal fractures surgery should be carefully considered.


Background
Calcaneal fracture comprises approximately 1-2% of all adult fractures and 60% of tarsal bones fracture.
However, about 60-80% of calcaneal fractures are displaced intra-articular fractures [1].Due to the unique shape of displaced intra-articular fractures of the calcaneum, location, and limited soft tissue envelope, treatment is a considerable challenge to the foot and ankle surgeons. Open reduction and internal xation (ORIF) have become a reality and primary method for treating calcaneal fracture. However, about 15-25% of complication such as wound infection and ap necrosis has been reported [2].
Currently, minimally invasive techniques have been reported to achieve better clinical and radiological outcomes with less wound infections, short hospitalization, and early recovery compared to ORIF techniques [3,4].
Many factors may affect early weight-bearing and ambulation, and clinical outcomes of the patients after minimally invasive technique of calcaneus fractures. Early weight-bearing may reduce ankle stiffness, bone and muscle atrophy, and help with early recovery activities.
At present, tourniquet is commonly used in a variety of orthopedic surgeries. The purpose of a tourniquet is to prevent blood loss and optimize operative eld visualization, thereby improving technical precision and limiting operative duration. However, the use of tourniquet is potentially risky; so, working with tourniquet requires care and expertise. Some studies have shown that tourniquet application is not necessary during minimally invasive such as Arthroscopic ankle surgery [5,6]. Tourniquet application has potential risks of improper and even proper use during lower limb surgery, including muscle injury, functional weakness and reduced muscle strength, joint stiffness and postoperative swelling [7,8].
Previous studies have shown that tourniquet is also thought to be associated with an increased postoperative pain, and increased hospital length of stay [9].
Accordingly, the objective of this study was to assess the effect of tourniquet application during minimally invasive technique of intra-articular calcaneal fractures on postoperative outcomes, with the aim of quantifying the value of tourniquet application for visibility and reducing blood loss intraoperatively.

Study design and period
A retrospective study was conducted at our institution from March 2015 to December 2018 to determine the effect of tourniquet application during minimally invasive technique for intra-articular calcaneal fractures on postoperative outcomes. informed written consent was obtained from all patients for participation in this study.

Study participants and eligibility criteria
Both men and women aged ≥ 20 years at the time of surgery, with closed intra-articular calcaneal fractures and received screw xation versus plate xation via the sinus tarsi approach, had at least two years of clinical follow-up from the date of surgery. Exclusion criteria were as follows: patients with open multiple, bilateral fractures, and patients with incomplete medical data. Written informed consent was obtained from all participants. Personal details, age, gender, smoking habit, mechanism of injury, body mass index (BMI), and operative details were recorded accurately on admission.
Sample size and preparation A total of 131 closed calcaneal fractures patients who underwent minimally invasive procedure were eligible for inclusion. Patients for whom tourniquet was in ated intraoperatively (n=62) were compared to those for whom a tourniquet was not in ated (n=69). If there were swelling of the tissues, surgery was delayed until the swelling of the soft tissue had subsided su ciently. In all patients, an appropriately sized tourniquet cuff was overlapped around the thigh before anesthesia. Webril bandage or elastic stockinette was always applied under the tourniquet, and an impervious drape was also placed around the cuff to prevent uids pooling. Patients were blind randomly assigned in ation or not during the operation. When tourniquet was used, the in ation was applied to approximately 100~125 mm Hg over the systolic blood pressure. After surgery, we encourage patients to move and elevate their foot and ankle second day after surgery. Two weeks after surgery, sutures were removed. Then patients were able to exercises and partial weight bearing wearing cast boot or splint 4 to 6 weeks after surgery. We informed them should not weight bear on the injured foot within less than 2 months.

Operation and tourniquet time
The time interval between incisions to completion the dressing was set as the operation time. The tourniquet was in ated just before the incision was made and de ated after skin closure, so the tourniquet time was equal to the operation time. Operating time and tourniquet time were obtained from computer logs and e patient's medical records.

The operative view
After operation, surgeons were asked to rate visualization of the operative eld on 4 points, (1. excellent = no limitation of visualization, procedure not impeded; 2. good = visualization was slightly limited, procedure not impeded; 3. fair = visualization was limited, procedure was slightly impeded; 4. poor = visualization was limited, procedure was markedly impeded).

Intra-operative and Postoperative Blood Loss Estimation
Intraoperative blood loss was measured by the amount of blood in the suction canister minus the amount of irrigation uid used. Visual estimation of blood volume in surgical gauze also was measured. Postoperatively, wound was typically covered with surgical gauze dressing (45 × 10 cm dry surgical rolled gauze), then compression dressing using cotton padding and ACE elastic bandage. 24 hours after surgery, surgical wound dressing was changed, after that if there were no bleeding, surgical wound dressing was changed every 48 hours. The simple rule of visual estimation of blood volume in surgical rolled gauze was measured as follows: 45*10 cm dry rolled gauze (Topline ®), 10 ml, 30 ml, and 50 ml of blood saturates about 25%, 50%, and 100% of the surface area, respectively [10].

Hemoglobin Concentration (Hb)
Hemoglobin was measured preoperatively and 48 h postoperatively. The normal HB value in our hospital is between 130 and 175 g/L for men and between 115 and 150 g/L for women.
Serum Creatine Phosphokinase (CPK) Serum creatine phosphokinase was measured preoperatively, 24 h, 48 h, and 72 h postoperatively. The normal CPK value in our hospital is between 25 and 200 IU / L for men and between 25 and 170 IU / L for women.

Postoperative Pain
Visual Analog Scale (VAS) was used to evaluate postoperative pain. VAS is s a proven subjective measure for acute and chronic pain. The score is recorded by marking a handwritten mark on the 10-cm line, which indicates the continuity between "no pain" and " severe pain". Patients were asked to rate their pain level during the rst 24 h, 48 h and 72 h postoperatively.
The amount of swelling of the ankle To assess the swelling, the circumference of the ankle (around the narrow part of the ankle, usually above the malleoli) was measured preoperatively, 2 and 4 days after surgery [11].

Hospital Length of Stay
Hospital length of stay was de ned as the total number of hospital days from the night of surgery to discharge, because most of patients were admitted into the hospital few days prior to the surgery.
American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot Scale AOFAS scale was used to evaluate objective and functional outcomes. It including 100 points for total: pain (40 points), function (50 points) and alignment (10 points). Scores between 90 and 100 points rated as an excellent, between 80 and 89 points rated as a good, between 70 and 79 rated as a fair, and < 70 points rated as a poor.

Wound healing time
Wound healing refers to the total number of days from the day of surgery to the day that stitches were removed without redness or necrosis.

Time to Union
Postoperatively and during regular follow-up, standard radiograph (X ray radiography and CT scan) were used to assess union time and fracture healing. And time to union was de ned by the ability of the patient to walk without pain and con rmed by radiographs showing invisibility of the fracture line and continuity of the cortex.

Return to Work
Return to work was de ned by the patient's ability to walk and perform daily activities without pain or crutches.
Statistical Analysis SPSS (version 23.0; SPSS IBM Corp., Chicago, IL, USA) was used for statistical analysis. Data obeying normal distribution were expressed as (mean ± SD). The difference between two groups was analyzed by using an independent t-test. And P < 0.05 was considered as statistically signi cant.

Baseline and Follow-up
Between March 2015 and December 2018, a total of 131 closed calnaneal fracture patients who underwent minimally invasive procedure were included. The patients were followed up for at least 24 months. The tourniquet was used in 62 patients, whereas it was not used in 69 patients. General information of the patients is summarized in Table 1. In the tourniquet group, there were 62 patients, including 46 males and 16 females, with a mean age of 47.0 ± 13.0 years. There were 38 fractures on the right side and 24 fractures on the left side, 12 of patients were smoker and 50 were not. 28 fractures resulted from road tra c accidents and 34 fractures resulted from falls down. We classi ed all fractures according to the CT classi cation described by Sanders et al. [

Operation time
The mean tourniquet in ation of the tourniquet group was 258.3 ± 9.1 mm Hg. The mean operation time of the tourniquet group was 64.7 ± 3.5 minutes, while that of the non-tourniquet group was 76.0 ± 6.1 minutes. Compared with the non-tourniquet group, the tourniquet group reduced the operation time by 11.3 ± 2.6 minutes. The difference between the two groups was statistically signi cant (P < 0.001) ( Table 2). The visibility in the tourniquet group (n = 62) was rated excellent in 56 cases, good in 4 cases, and fair in 2 cases. None of the cases was rated poor visibility.
The visibility in the non-tourniquet group (n = 69) was rated excellent in 28 cases, good in 22 cases, fair in 14 cases and poor in 5 cases.
The operative view was statistically signi cant between two groups (P < 0.001). visibility in the tourniquet group was satisfactory (excellent/good) in 60 cases and unsatisfactory (fair/poor) in 2 cases. Visibility in the non-tourniquet group was satisfactory (excellent/good) in 50 cases and unsatisfactory (fair/poor) in 19 cases. The tourniquet required in ation in 9 cases (in which visibility was rated fair/poor) intraoperatively, and accounted for 13-75% of the total operation time, the in ation reason was recorded as bleeding in 4 cases and poor view in 2 cases. Of those, the visibility of 8 (88.9%) cases was improved to at least a good level ( Table 2).

Blood Loss Estimation
In the tourniquet group, the mean estimated intraoperative and postoperative blood loss was 56.6 ± 33.0, and 100.0 ± 25.3 mL, respectively, while that of the non-tourniquet group was 205.0 ± 31.6, and 38.3 ± 19.8 mL, respectively. Compared with two groups, intraoperative bleeding was more in the non-tourniquet group by 148.4 ± 5.0 mL, whereas postoperative bleeding was more in tourniquet group by 61.6 ± 3.5 mL. This difference was statistically signi cant between the two groups (P < 0.05) ( Table 2).

Hemoglobin Concentration (Hb)
The mean HB level was 135.3 ± 14.2 g/L preoperatively, and 134.3 ± 12.7 g/L 48 h postoperatively, in the tourniquet group. In the non-tourniquet group, the mean HB level was 135.2 ± 14.1 g/L preoperatively, and 131.7 ± 10.1 g/L 48 postoperatively. This difference was not statistically signi cant between the two groups (P > 0.05) (

Hospital Length of Stay
The mean length of stay in hospitals was 3.8 ± 1.4 days in the tourniquet group, while that of the nontourniquet group was 3.1 ± 1.2 days. This difference was not statistically signi cant between the two groups (P > .05) ( Table 4).

American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot Scale
In the tourniquet group the mean total AOFAS was 94.0 ± 3.7 points, while that of the non-tourniquet group was 93.1 ± 3.0 points at the last follow up. This difference was not statistically signi cant between the two groups (P > 0.05) ( Table 4).

Wound healing time
In the tourniquet group the mean wound healing time was 12.3 ± 2.3 days, while that of the nontourniquet group was 12.1 ± 1.6 days. This difference was not statistically signi cant between the two groups (P > 0.05) ( Table 4).

Complications
In the tourniquet group, delayed wound healing was seen in 5 cases, and 2 cases in the non-tourniquet group. Conservative treatment with systemic antibiotic therapy and local wound care were applied for those patients (Table 4).

Time to Union
In the tourniquet group, the mean time to union was 11.6 ± 0.8 weeks, in the non-tourniquet group the mean time to union was 12.1 ± 1.2 weeks as determined by X-ray. This difference was not statistically signi cant between the two groups (P > 0.05) ( Table 4).

Return to Work
The mean time for return to work was 15.2 ± 3.4 weeks in the tourniquet group, whereas in the nontourniquet group the mean time for return to work was 15.5 ± 3.7 weeks. This difference was not statistically signi cant between the two groups (P > 0.05) ( Table 4).

Discussion
Tourniquet is a commonly used in a variety of foot and ankle surgeries in order to improve surgical eld visibility, decrease intraoperative blood loss, and reduce operating time. This study aimed to quantify the effect of tourniquet application on postoperative outcomes after minimally invasive surgery of calcaneal fractures. Overall, our study showed that tourniquet application resulted in decreased operating time, improved operative eld visibility, and reduced intraoperative blood loss. Besides, the ndings of the study showed that tourniquet application was associated with increased postoperative pain, and blood loss in the rst 24hr, 48hr, and 72 hr.
To our knowledge, no prior studies have examined the effect of tourniquet use on outcomes in minimally invasive treatment for calcaneal fractures. We believe this is the rst article assessing feasibility and visibility of the minimally invasive procedures, so this article adds new information to the published literature.
In this study, we found that the mean operating time was signi cantly longer in the patients who undergo surgery without tourniquet. This may be due to the care that exerted by the surgeons when staunch the bleeding and to the fact that, partially obstruction of the surgical eld without the tourniquet.
We assessed the di culty of the operation based on the operative eld of vision and time. We have found that the visualization was signi cantly better in the tourniquet group. In the non-tourniquet group, more ushing was required to provide a better view onto the surgical eld. However, the visibility improved in 88.9 of cases after tourniquet in ation.
In the patients without tourniquets, the mean amount of estimated postoperative blood loss was signi cantly lower during the rst 24 h. No patients from either group received a blood transfusion. In the without tourniquet group, electrocautery was used to seal off bleeding blood vessels, whereas no homeostasis was used for the tourniquet group, and the tourniquet is de ated only after skin closure. Based on our extensive experience as foot and ankle surgeons; avoiding tourniquet de ation before skin closure has not caused any problems. Interestingly, similar experience was reported by some researcher on their experience with total knee replacement, internal xation of ankle fractures, and carpal tunnel release [7,13,14].
Muscle tissue damage that caused by tourniquet is not well described. The duration of tourniquet use may cause elevated serum CPK levels; this increase may accurse 8 hours following muscle damage.
Muscle tissue damage can lead to increased pain postoperatively compared to non-tourniquet group [15]. However, there were no signi cant differences in the CPK level between tourniquet and non-tourniquet patients during consecutive measurements, and CPK level did not exceed the normal levels at any of the measuring time points.
Patients in the tourniquet group showed signi cant higher postoperative pain when compared to nontourniquet group patients. However, our study results showed that the pain was signi cantly increased 24 h postoperatively after removing the pressure dressing, and then gradually decreased at 48 h, and 72 h, postoperatively, revealed that it is less likely to be a direct result of ischemic edema and hypoxia caused by the tourniquet, but it may be the result of swelling and hematoma. In the non-tourniquet group, ankle swelling was decreased slowly on postoperative days 2 and 3. This may be the reason for the higher postoperative pain in the tourniquet group.
Postoperative pain remains a signi cant barrier of delay discharging patients, and it has a signi cant impact on the patient's ability to return to normal activities after discharge [9]. Postoperative analgesia plays a signi cant role in allowing the patients exercise and restore mobility, promoting recovery while reducing hospital stay [16].
Our nding did not con rm previous studies that the tourniquet application increases postoperative swelling and length of in-hospital stay [7,9]. Reduced length of stay in hospitals has signi cant bene ts for the hospital, including resource and cost savings. Whilst some factors that prognosticate hospital length of stay have been identi ed, the direct and indirect interaction between these factors is less clear.
The length of stay in a hospital is an important indicator of resource consumption.
The nding of our study showed that tourniquet application did not result in delayed wound healing or return to work and activities. Generally, minimally invasive procedure is associated with less wound complications, early rehabilitation, and good to excellent clinical outcomes [3,4,17,18].
Time to return to work was evaluated in the study of Maffulli et al. [19] which reported an average difference of 7 days between the tourniquet and non-tourniquet group. Further studies are recommended to evaluate the impact of tourniquet use on return to work after calcaneal fracture surgery.
In the tourniquet group, delayed wound healing was seen in 5 patients, and 2 patients in the nontourniquet group. According to previous studies, patients with increased BMI, Sanders type, smoking, and postoperative hemovacuum drain may at higher risk of infection and delayed wound healing [20][21][22]. Furthermore, a recent study by Benedick et al. [23] assessed the effect of tourniquet use on wound healing following ankle fracture surgery, demonstrated that the use of a tourniquet did not delay wound healing or increases the incidence of incision complication.
After surgery, it is recommended to apply a compression dressing using ACE elastic bandage as supplementary negative pressure drainage. The aps are evenly compressed to decrease bleeding and eliminating space enhances the effectiveness of negative pressure.
Critical hypoxia levels where normal cell function is affected usually in patients with higher tourniquet pressure and longer duration of de ation. However, low tourniquet pressure (< 250 mm Hg) may not be risky and tourniquet in ation for 1 to 3 hours as a safe limit for tourniquet time, and if the anticipated time of surgery is more than 2.5 hours, it should be de ate the tourniquet for 10 to 15 minutes and elevate the leg before re-in ating again [24,25]. However, three hours is much more than the duration of surgery reported in this study in the presence of a tourniquet. In our study, conservative treatment with systemic antibiotic therapy and local wound care were applied for those with delayed wound healing patients.
Calcaneal fractures are a serious injury and the most common fracture of the tarsal bones that may lead to lifelong problems. Pain in the joints, stiffness and arthritis frequently develop. Sometimes a fracture fails to heal in the right position. The long-term consequences of calcaneal fractures are decreased ankle motion and limping when walking, which are caused by fracture collapse and loss of length in the leg. It may require a revision surgery and long-term or permanent use of an orthotic device or brace to deal with complications.
Open reduction versus plate xation via the sinus tarsi approach are currently accepted treatments method for calcaneal fractures. The good to excellent clinical and radiological outcomes, with less wound complications and early recovery have been reported in the minimal invasive sinus tarsi approach.
Even complex calcaneus fractures can be fully exposed using a minimally invasive sinus tarsi approach to achieve anatomic reduction and stable internal xation [3,4,17,18].
Bleeding in the surgical eld is the most important problem without the use of a tourniquet. Tourniquets are widely used during upper and lower limbs surgery to provide a bloodless eld. There is a lot of controversy about the use of a tourniquet, and the possible bene ts must be weighed against the potential risks. Minimal bleeding in the surgical eld is the main advantage of using a tourniquet during upper and lower limb orthopaedic surgery. Due to improved visibility, it can shorten the operation time and reduce the technical di culty of the operation.
Our study has some limitation worth noting. Firstly, this is a retrospective study from a single institution.
Secondly, the tourniquet was in ated just before the incision was made and de ated after skin closure, so we cannot comment on the tourniquet de ation before skin closure. Further studies are needed to clarify these points.

Conclusions
the results of this study demonstrated that the advantages of tourniquets application during minimallyinvasive technique for intra-articular calcaneal fractures are shorten the operation time, optimized visibility of the surgical eld, and decreased technical di culty by minimize intraoperative blood loss. However, adverse events associated with the use of tourniquet include increased postoperative pain, and more amount of postoperative bleeding. Due to higher postoperative pain and more amount of postoperative bleeding, more attention should be paid on the postoperative phase for those who tourniquet was used. The surgeon's decision to use a tourniquet during calcaneal fractures surgery should be carefully considered.