Introduction

Robotic assisted laparoscopic radical prostatectomy (RALP) is recently used as a contemporary minimally surgical treatment option for organ-confined prostate cancer due to various benefits such as less blood loss, operation time, pain, hospital stay, and complication rate [1, 2]. Besides, RALP has positive effects on patients’ outcomes [1]. On the other hand, low-lithotomy and steep Trendelenburg position during RALP can cause musculoskeletal complications that can affect comfort of patients during postoperative period [3]. Prolonged lithotomy with steep Trendelenburg position may cause orbital and conjunctival edema, injuries in brachial plexus and skin, rhabdomyolysis, compartment syndrome, deep venous thrombosis, etc. [3, 4]. Additionally, general anesthesia may install risks of muscle and nerve injuries [5]. All these above may lead to decrease in quality of life and late recovery after operation. However, there have been some published studies on these, but data on pain and neuromuscular complications after RALP are still lacking.

We here evaluated postoperative pain and neuromuscular complications (i.e., hip adduction, flexion weakness, pain or loss of sensitivity on upper and lower extremities), which are related to prolonged exposure to the steep Trendelenburg and low-lithotomy position during RALP.

Methods

Study design

This was both non-randomized and non-placebo study with retrospective view of prospective recorded data. We investigated patients’ data between September 2010 and June 2014. There were 534 patients who underwent RALP at our institute. Our certificated cancer center approved the ethical statement of research involving human participants and also the statement of informed consents. Then, all patients provided signed consent forms and understood the operation and the study. The exclusion criterion was lack of follow-up data.

All RALP procedures were performed on the same surgical table (MAQUET Medical Systems, Wayne, NJ, USA) and Da Vinci Robotic surgery system (DaVinci® S Intuitive Surgical, Inc., Sunnyvale, CA, USA). Additionally, Tempur material was used as surgical table’s mattress.

Data consisted of patients’ age, body mass index (BMI), comorbidities, previous operations, presence of any implant, operation time, American Society of Anesthesiologists (ASA) score, postoperative complications associated with positioning, pain score with visual analogue scale (VAS), and hospital stay. All complications were assessed according to modified Clavien classifications [6].

Patient positioning

At the start of the operation, all patients were positioned under general anesthesia. Patients’ positions were adjusted by operating room staff that is consisted of surgeons and urology fellows under supervision of experienced mentors of the clinic. The patient was placed in lithotomy position and his legs were separated in flexion and abduction. Patient’s arms were positioned as adducted parallel to his body, in supine position. Thereafter, patient’s body was tilted 15°–20° downward in a steep Trendelenburg position. His head was lifted up nearly 15°–20° and a shoulder support was used to prevent sliding during operation and better fixation [7]. We were very careful not to make brachial plexus compression. Protective silicon pads were placed for head, elbows, wrists, shoulders, ankles, and heels to prevent sliding and neuromuscular complications [8]. The pressure points of body and lower extremities had been well supported via adequately comfortable pads and supporting instruments (Fig. 1). Therefore, we aimed to prevent postoperative neuromuscular complications and pain associated with positioning [4].

Fig. 1
figure 1

The patient is positioned in steep Trendelenburg and low-lithotomy position. Supportive pads are placed for preventing complications associated with positioning

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Positioning obese patients and patients who had any bone implant might be problematic [9]. Thus, we were more careful with positioning those patients before RALP.

Brief description of the procedure

The DaVinci® robotic surgery system (DaVinci® S Intuitive Surgical, Inc., Sunnyvale, CA, USA) was used, and all patients were positioned after undergoing general anaesthesia.

A standardized 6-port placement configuration was used as we described before [6]. After positioning, retroperitoneal space was created by blunt finger dissections through a subumblical incision. A 10-mm ballon trocar (Herloon, BBraun, Aesculap AG, Tuttlingen, Germany) was used for creating adequate space in extraperitoneal area, a 12-mm trocar was placed, and other trocars were placed under direct vision in a “W” shape manner; two 8-mm robotic trocars, two 11-mm assistant trocars, and an extra 6-mm assistant trocar were placed on the suprapubic area [7]. Pneumo-extraperitoneum was provided by CO2 insufflation (maximum gas pressure, 15 mmHg; maximum gas flow, 30 mL/s) [7].

Then, DaVinci® robotic surgery system was docked between the legs of the patient. The patient cart base is located at the base of operating table. The height of working robotic arm was set according to safety rules. If it was deemed necessary to avoid patient’s legs from hitting the arms during movements, patient’s legs were lowered. Operating room lights and equipments are drawn aside [10].

Statistical analysis

The Statistical Package for the Social Sciences (SPSS) for Windows 16.0 (SPSS Inc., Chicago, IL) was used for statistical analysis. Chi-square test was used to compare postoperative pain and neuromuscular complications. Independent predictors for postoperative pain and neuromuscular complication were analyzed with univariate logistic regression analysis. Multivariate analyses were used for confirmation data. Independent variables were determined. p ≤ 0.05 was considered significant.

Results

Data of 534 RALP patients were evaluated. Mean age was 65.2 ± 7.3 years, and mean BMI was 27.3 ± 3.8 kg/m2. Mean ASA score was 2.2 ± 0.6. Mean operative time was 198.8 ± 43.7 min with mean hospital stay 9.8 ± 1.7 days. Calculated mean pain score was 3.6 ± 1.2. All these findings are summarized in Table 1.

Table 1 Demographic, perioperative, and postoperative data of patients
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Neuromuscular complications and pain, which are associated with positioning, were observed in 81 patients (15.1 %). Neuromuscular complications were paresthesia, numbness, and weakness. Postoperative pain was observed in 54 patients (10.1 %), and neuromuscular complications were also observed in 27 patients (5.1 %) (Table 2).

Table 2 Position-related pain and neuromuscular complications in different localizations
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Pain associated with postoperative position was observed in 54 patients (10.1 %). The locations were as follows: 1 neck pain, 13 back pain, 4 shoulder pain, 4 rib pain, 3 hip pain, 3 inguinal pain, 1 sacral pain, 5 lumbar pain, 9 upper leg pain, 12 lower leg pain, 6 knee pain, 6 foot pain, 2 arm pain, and 2 hand pain. Neuromuscular complications (paresthesia, numbness, and weakness), which are associated with positioning, were also observed in 27 patients (5.1 %) as follows: 5 patients experienced loss of sensation in hip, 4 patients in knee, 8 patients in upper leg, 6 patients in lower leg, 6 patients in hand, and 14 patients in foot (the most often one) (Table 2). Neuromuscular complications and/or pain was observed in some of the patients, in different localizations at the same time. All these complications, which needed additional drugs and/or physiotherapy, were of Clavien grade 1.

Comparison of age, ASA score, BMI, implant, operation time, comorbidity, previous operation with postoperative pain is presented in Table 3. ASA score, BMI, and comorbidity were significantly associated with postoperative pain in univariate analyses (p = 0.01, p = 0.01, and p = 0.01, respectively; Table 3). Comparison of age, ASA score, BMI, implant, operation time, comorbidity, previous operation with postoperative neuromuscular complication associated with positioning is presented in Table 4. ASA score, previous operation, and comorbidity were significantly associated with postoperative neuromuscular complication in the univariate analysis (p = 0.04, p = 0.01, and p = 0.02, respectively; Table 4).

Table 3 Comparison of age, American Society of Anaesthetists score, body mass index, having implant, operation time, comorbidity, previous operation according to postoperative pain
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Table 4 Comparison of age, American Society of Anaesthetists score, body mass index, having implant, operation time, comorbidity, previous operation with position-related postoperative neuromuscular complications
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Multivariate logistic regression analyses showed that postoperative pain was significantly associated with BMI < 30 kg/m2 and presence of bone implants (p = 0.01 and p = 0.03, respectively; Table 5). Besides these, comorbidity and previous operations were higher in patients whose BMI < 30 kg/m2. In addition, we found that postoperative pain was higher in patients with bone implants. Comorbidity was also significantly associated with postoperative neuromuscular complications in the multivariate analyses (p = 0.04; Table 5).

Table 5 Multivariate logistic regression analysis of postoperative pain and neuromuscular complications
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Discussion

Trendelenburg position has been widely used in order to keep away abdominal viscera from surgical structures with gravity effect [11], while lithotomy position has been used to provide surgical access to deep structures in the pelvis in RALP [1]. However, this position can cause physiologic changes in these patients. Studies noted postoperative neuromuscular complications, such as nerve and extremity injuries including brachial plexus neuropraxia, related to steep Trendelenburg position for prolonged operation time during RALP [11–17]. Akhavan et al. [18] reported neuromuscular complications associated with patient positioning during RALP. Wen et al. [3] reported costs of neuromuscular complications. In the present study, we evaluated postoperative neuromuscular complications and pain associated with positioning during RALP. In addition, we investigated benefits of appropriate surgical table, mattress (Tempur), paddings, and protective materials for reducing neuromuscular complications associated with positioning.

We found that the incidence of postoperative neuromuscular complications was associated with positioning in 27 patients (5.1 %) who underwent RALP. The comparison of neuromuscular complications in published studies with those in the present study is summarized in Table 6. The back pain, which is associated with positioning, was the most observed pain type. Additionally, the most common neuromuscular complication was loss of sensation in foot (in 14 patients, 19.7 %). Koc et al. [19] reported neuropathy in lower extremity for 5 (1.3 %) of 377 patients within first 7 days after RALP on a split-leg table. Mills et al. [9] reported neuromuscular complications related to positioning at a rate of 6.6 % in 22 of 334 patients who underwent robotic assisted laparoscopic urological surgeries. Besides these, Wen et al. [3] represented their complications of RALP series in terms of positioning at a rate of 0.4 % in 249 of 61,656 patients. Our results were in line with reports above. The patient positioning during RALP can result in various complications like position injuries. It is very important to avoid complications of positioning. Thus, operating room staff should be careful when they are positioning patients before RALP.

Table 6 Comparison of neuromuscular complication rate in published studies and the present series, after robotic assisted laparoscopic surgeries
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Koc et al. [19] reported complications of positioning associated with prolonged operation time. This was because of more exposure to nerve compression during prolonged operations. Additionally, Mills et al. [9] agreed with this report and revealed that when operation time was shorter than 240 min, positioning injuries might not occur. In our study, mean operation time was 195 min and this was not statistically associated with postoperative neuromuscular complications and pain. Our results were not in line with studies above; this might be the reflection of appropriate operation time in RALP. We strongly believe that operation time may be shortened by surgical experience. Thus, neuromuscular complications and higher rate of pain can be prevented.

The ASA score has been used to evaluate patients’ risk factors and physical status [9]. In our study, mean ASA score was “2” and this was statistically associated with postoperative pain. In addition, this was significantly associated with postoperative neuromuscular complications. Mills et al. [9] reported that higher ASA score was associated with positioning complications. Our results were similar to their results. In case of higher ASA score, surgeons should consider potential positioning complications. However, this should be investigated in detail in another study.

Comorbidity has another negative impact on operation outcomes [1, 9]. According to our findings, postoperative neuromuscular complications were observed 1.79 times more in patients who had comorbidities (higher ASA). Wen et al. [3] reported significantly increased incidence of eye, nerve, compartment syndrome, during RALP with patients who have comorbidities. Preoperative assessment of comorbidity can be a pathfinder for minimizing neuromuscular complications related to positioning. There is no doubt that obesity is another comorbidity and this can cause complication during positioning [1, 9]. We found that postoperative pain was more in patients with BMI > 30 kg/m2. This was statistically significantly associated with obesity. On the other hand, multivariate logistic regression analyses showed postoperative pain was more observed in patients whose BMI was lower than 30 kg/m2. This may be due to the fact that obese patients’ adipose tissue may help to support muscle and joints during RALP. Nevertheless, it is an important risk factor as obesity may negatively affect postoperative patient outcomes [1, 9].

Chitlik [1] revealed that previous operations could be one of the position-related risk factors during RALP. However, there has been a widespread opinion among surgeons that if a patient had previous operation, the patient can have another operation. We do not agree with Chitlik [1]. However, it is important to know previous operation history of a patient who would undergo RALP. Moreover, patients with previous bone implant history may be at risk of complications associated with positioning. We could demonstrate this point in statistical analyses. However, more evidence-based studies are needed for accurate results on this issue.

The present study has some limitations. At the first, we used retrospective pattern for data analyses. Additionally, although we used VAS for pain evaluation, there may be differences in pain perception among patients. On the other hand, there was no patient with permanent sequelae in follow-up period. All complications were managed by medications and physical therapies. However, this can be a subject of another study. We focused on neuromuscular complications [18]. Lastly, we would like to make a note that the mean hospital stay is 9.8 days in our series. This is related to health system in our community, and not mostly related to complications.

Nonetheless, our study is unique in the published literature, in which postoperative pain and neuromuscular complications after RALP were evaluated with multivariate analyses. Protective precautions should be considered in terms of using appropriate surgical table with mattress, paddings, and protective materials for reducing neuromuscular complications associated with positioning considering patients’ bone implants and previous neuromuscular diseases. BMI < 30 kg/m2 and having previous implants were risk factors for pain after RALP, and having comorbidity was associated with neuromuscular complications.

Conclusions

Patient positioning during RALP may result in postoperative complications. Patients who have comorbidities and operative history, notably with implants, can be at an increased risk of postoperative neuromuscular complications and pain after RALP. Patients who have high ASA score may be at a greater risk of positioning complications. Operating room staff should be careful to minimize postoperative complications associated with positioning, specifically in case of steep Trendelenburg and low-lithotomy position. Protective precautions should be taken into account during RALP to avoid complication associated with positioning.