The prevention and treatment of postoperative pain are a long-debated issue which is attracting more and more attention. Thyroidectomy is associated both to postoperative pain located in the surgical wound and in the posterior neck. In particular, in 2015, Han et al. (Han et al. 2006) reported that 80% of patients who underwent thyroid surgery complain about posterior neck pain postoperatively. Posterior neck pain is probably due to the position of the patient on the operative bed with the neck hyperextended (Han et al. 2006). Indeed, the operating table is equipped with a manually adjustable headrest to calibrate neck extension keeping the head in a stable position.

Postoperative neck pain, a distinct entity from surgical pain located at the wound, occurs commonly after thyroidectomy and is treated with analgesics. As wound pain occurs immediately after surgery, it usually lasts for about 48 h (Genc et al. 2019).

In our study, the inclination angle of hyperextension on the operating table was significantly associated with postoperative neck pain (p < 0.001; beta 0.270), indicating a direct correlation. Our results are consistent with the study by Lang et al. (Lang et al. 2015), who compared postoperative pain in patients scheduled for thyroidectomy with or without neck hyperextension on the operating table. The authors reported that postoperative pain was associated with neck hyperextension, although they did not correlate it with the degree of inclination.

The correlation between the angle of inclination and postoperative neck pain can be attributed to several factors. Intraoperative positioning, which involves hyperextension of the neck, can lead to unnatural postures and tension in the neck muscles, trapezius, and brachial plexus. The duration of the surgery and the use of anaesthetics combined with muscle relaxants contribute to the relaxation and subsequent tension of the neck and shoulder muscles, as well as the nerves of the brachial plexus. Surgical manoeuvres to improve the visibility of the operative field and access to the thyroid lobes, as well as to ensure adequate exposure of vital structures like the laryngeal nerve and parathyroids, can also contribute to discomfort (Lang et al. 2015). Additionally, the use of retractors and the pressure and tension applied to the skin, subcutaneous tissues, and muscle fascia, along with manipulation of anatomical structures around the trachea and the inherent elasticity of the neck, play a role.

Although no other parameter in our analysis was correlated with postoperative pain, a trend toward a correlation with the type of surgery was observed: TT was associated with the onset of postoperative neck pain, though it did not achieve statistical significance (p = 0.052). TT predisposes patients to postoperative neck pain. The duration of this surgery necessitates maintaining the neck in a hyperextended position on the operating table for a longer period compared to HT, maintaining cervical muscles and ligaments stretched.

The absence of statistically significant correlations, aside from the one between the angle of inclination and postoperative neck pain, underscores the critical importance of this factor in developing this adverse outcome.

Furthermore, our findings suggest that as the angle of neck inclination increases, postoperative pain will likely increase. We hope that in the future, larger studies will explore more in depth this aspect.

Unfortunately, our study fails to establish an ideal range of neck inclination to avoid postoperative neck pain; however, it could be recommended not to overextend the neck of patients undergoing open thyroidectomy. Indeed, overextension does not significantly improve the access to the thyroid gland, as reported by Serpell et al. (Serpell et al. 2003); on the other hand, it may promote the onset of postoperative pain and discomfort (Lang et al. 2015) which may persist for several days and may negatively affect daily life (Rodriguez-Torres et al. 2019; Lang and Lo 2010; Serpell et al. 2003; Lang and Wong 2013; Shih et al. 2010; Han et al. 2006; Genc et al. 2019; Lang et al. 2015).

The management of postoperative pain is a serious issue. It is of primary importance to implement a bundle of pain prevention that focuses on the early identification of patients at risk (i.e. patients reporting neck stiffness, not engaging in sports, experiencing sporadic episodes of stiff neck without documented pathologies) to be addressed to perform head-neck stretching exercises to increase the degree of elasticity of neck muscles (Takamura et al. 2005). These exercises may lead to a decrease in the request for postoperative analgesics, limiting the unnecessary use of opioid drugs (Ferrell et al. 2021). Moreover, pain management improves postoperative comfort and patient satisfaction; it aids recovery and promotes rapid discharge.

Strategies reported in literature to treat postoperative neck pain include bilateral great occipital nerve blockade with bupivacaine (Han et al. 2006), intraoperative transcutaneous electrical nerve stimulation applied on the trapezius muscle (Park et al. 2015), and physiokinesiotherapy (Genc et al. 2019). Anyway, a further effort to assess factors associated with neck pain should be made in order to prevent it rather than treating it.

This study’s strengths include using objective measurement tools, such as the orthopaedic goniometer, a detailed data collection process, and analysis, which enhance the reliability of the results. A variety of validated tools are available for detecting pain, but most of the literature focuses on the NRS scale, considering it as the most popular. Similarly, this scale has been used to measure pain in previous studies in the field of thyroidectomy (Jo et al. 2021; Shrestha et al. 1976; Thorsen et al. 2022). Additionally, the study was conducted at a European reference centre for thyroidectomies, allowing for precise measurement of the inclination angle of hyperextension on the operating table. Other positive aspects include the uniformity of operating times, the sample’s consistency, and the healthcare workers’ standardised work methods.