This study reveals that the benefits regarding cosmetic outcomes after minimally invasive surgery, seen previously in other reports, could not be documented. Minimally invasive surgery had no positive effect on patients scar evaluation after MIP, based on assessment scales. This reflects the result that patients were as well satisfied with cosmetic results of the conventional surgery, as the minimally invasive procedure. Patients late postoperative symptoms were minimal and the appearances of scars were acceptable after MIP or CP. According to the plastic surgeons blinded assessment, there was no significant difference between both groups. Thus, the relationship between scar length and patient assessment scores does not appear to be as certain as previously thought.
Parathyroid surgery has evolved over the last decades, particularly with the advent of minimally invasive thyroid surgery, resulting in shorter incision lengths. A shorter incision, however, does not necessarily mean an improvement of patients overall satisfaction 19. Despite the fact that smaller incisions are regarded as improving wound appearance in general, the exposure is often very limited. Significant retraction during surgery is warranted to provide adequate access to target the pathologic gland. The force of retraction, which may give way to inadvertent stretching and lengthening of the incision, has also been considered to be associated with damage to the wound edge, which may alter normal wound healing.
Until recently, several so-called minimally invasive techniques have been described and carried out safely for parathyroid gland surgery; the unilateral approach, radioguided surgery, open minimally invasive (mini-incision) surgery, video-assisted and fully endoscopic parathyroidectomy, as well as robot-assisted surgery. These have been proposed to improve cosmetic outcomes 19. MIP has become very popular and an incision of 3 cm or less in length or no scar in the neck has been the main features differentiating minimally invasive approaches from traditional approaches 11. General characteristics of minimally invasive techniques are; a smaller incision, when compared to classic open transverse cervical incision and a targeted approach, focused on the pathological parathyroid gland(s). Especially focused parathyroidectomy has been adopted widely, since it is accepted to be a simple procedure carried out without the need for any additional equipment on hand, and as successive as the traditional approach on the other hand. According to the International Association of Endocrine Surgeons Survey, more than half of the surgeons implemented the MIP 20. MIP must be recommended only for patients with sporadic hyperparathyroidism and when preoperative concordant imaging studies have localized a single adenoma. Patients suspected for multiglandular disease on imaging studies or patients with familial hyperparathyroidism may not be eligible for these limited procedures. The advantages of MIP are reported as follows: decreased operating times, decreased hospital stay, reduced level of physical invasiveness, and better cosmetic results 21.
To evaluate the expectations of the surgical patient is of utmost importance, since expectations influence the patient's perception of the surgical outcome. It is this perception that determines the ultimate psychological response to the results of the operation 22. The concept of image is important for understanding the psychological reaction to sequelae of surgery. The cosmetic importance of the front of the neck comes from its anatomical visibility. This is why in patients undergoing thyroid and parathyroid surgery, it is important to assess patients' expectations before the procedure. These expectations influence patient's perception on the surgical outcome. The potentially important body image factors affecting patient satisfaction, include patients subjective perception to the surgical change, patients expectations, social evaluation of surgical change and age, as well as gender 23. Since surgeons are aware of these expectations awaiting better patients satisfaction after smaller or no neck scar, a lot of new surgical techniques, like mini-incision, endoscopic, robotic, transaxillary and video-assisted techniques have been developed, as presented above. Meanwhile, new techniques describe for thyroid and parathyroid surgery carry potential new risks, as expected 24. Increased satisfaction with scar cosmesis is expected to be the primary clinical advantage of these approaches. However, not all studies showed statistically significant difference in scar cosmesis between the groups beyond months 11,12,14.
Long-term follow-up regarding scar assessment is important, because of the time warranted for the natural wound healing process. A criticism may be made towards why at least 8 months time point to perform wound assessment after surgery was chosen as an appropriate time. As previously reported by OConnel et al 12, the cellular processes that underlie scar remodeling are most active during the first 6 months following the creation of a wound. These wounds then undergo greatly reduced remodeling over the subsequent 6 months, with indefinite minimal remodeling that is lifelong 12. This means that any study reporting early postoperative data regarding scar assessment should be criticized.
In this study, approximately half of the patients were treated with MIP and experienced skin incisions and scars less than 3 cm (mean 2.6 cm) in length. Although superior results of independent observers, assessment of cosmesis by the plastic surgeon and the patient him/herself revealed no superiority of the minimally invasive approach, when compared to conventional parathyroid surgery. These results are supported by the prospective cohort study by OConnell et al 12. A combined group of 11 patients treated by conventional-access thyroidectomy and parathyroidectomy (mean incision length, 7.6 cm) were compared to a group of 11 patients treated by minimal access parathyroidectomy (mean incision length, 3.4 cm). Patients with smaller incision were not more satisfied than patients having longer incision. No significant differences were found between objective measures of scar appearance such as the Vancouver and Patient & Observer Scar Assessment Scales (POSAS). Besides, there was increased visibility of the conventional surgery group scars by the named naive viewers. That study gives us further evidence that the length of incision does not affect patient satisfaction and suggests that the issue of parathyroidectomy scar satisfaction is not only simply being a question of length. However, the study of OConnell et al. may be criticized due to its small sample size and the mean age of the population reaching 70 years. This came in for criticism by Terris and Seybt 25 and they comment that elderly women would not be concerned with the appearance of their scar as the young patients do. The mean age of our study group was 54+9.3. This confirms the results regarding PSAS of the latter study and shows that scar perception is not changing between young and old patients, as asserted by Terris and Seybt.
Another study, carried out by Linos et al. 11, reported that minimally invasive procedures for the thyroid and parathyroid gland were not associated with statistically significant improvements in patient satisfaction. A recent paper systematically reviewed the evidence for whether minimally invasive techniques were comparable to conventional bilateral neck exploration methods in terms of success and complication rate; and if they were comparable, which technique is likely to be best for cosmesis, patient safety and satisfaction 26. Based on the evidence, long term cosmetic satisfaction has not been shown to be significantly better for bilateral neck exploration compared with minimally invasive parathyroidectomy. Another long-term study, with a higher number of cases assigned to each group is therefore essential to verify the findings of these studies.
Despite this, since the lack of studies regarding parathyroid surgery, there are studies reporting surgical approaches like minimally invasive video-assisted surgery may result in additional advantages compared to conventional surgery for the thyroid in terms of pain relief and cosmetic outcomes 6,8,27. A trial of video-assisted thyroidectomy versus conventional thyroidectomy showed that although lasting longer, the minimally invasive approach was related to an improved cosmetic outcome and less post-operative pain scores 6. These results are supported by Gal et al 27. who also found that the minimally invasive approach offered distinct advantages to selected patients in terms of very good to excellent cosmetic results and reduced postoperative distress. A recent meta-analysis reported that minimally invasive video-assisted thyroidectomy is superior to conventional surgery in terms of cosmesis and pain relief 28.
The limitation of most of these studies is the method of scar assessment, which has generally been conducted via a simple patient-reported Likert scale of satisfaction. A better analysis of scar appearance and patient satisfaction would be gained by use of a validated scar assessment tool that includes objective scoring of scar appearance by an independent observer, such as the Patient & Observer Scar Assessment Scale (POSAS) or Vancouver Scar Assessment Scale. These assessment scales are assessing more than just the appearance of scars using parameters like vascularity, pigmentation, thickness, relief, pliability, color, stiffness, regularity of the wound and patient factors such as pain and itching. Another point to criticize is the short follow-up time for scar assessment.
As other studies do, this study also possesses certain limitations. One of these limitations is its retrospective nature and the small sample size. Recall bias represents a major threat to the internal validity of retrospective studies. Nevertheless, regarding the power analysis of the similar prospective cohort study of OConnel et al 12, using an α of 0.05 and a power of 0.8, at least 9 samples for each group would be sufficient to show a difference of 3 points on a 10-point scale. We therefore assume the risk of type II error to be low in this study. Another limitation is the lack of patient satisfaction assessment. This may be achieved by carrying out future studies, using approved questionnaires and surveys regarding health-related quality of life as well.
Overall, this is one of the very few studies addressing the impact of the incision length of parathyroid surgery on cosmetic outcome in the long term. In addition, this study reveals that parathyroidectomy needs not be performed through excessively short incisions for the sake of scar appearance. Although observers were more able to point out a worse cosmetic appearance in the conventional surgery group, the patients themselves did not seem to notice any benefit with smaller scars.