1 Introduction

The development of innovative equipment and novel surgical approaches has made the transition from open to minimally invasive and less exposure surgery for the spine safer and simpler.^1–3 The technique for anterior cervical surgery defined by Cloward⁴ and Smith and Robinson⁵ has been modified over the years by numerous surgeons since 1958.^6–12 These techniques and approach to the anterior cervical spine, although relatively straightforward by most standards, sets the stage for the rest of the operative procedure. It also impacts the patient's first impression and level of satisfaction in the early postoperative period with regards to cosmesis, discomfort and pain.

Healthcare is rapidly changing based on patients’ needs, insurers and surgeon factors in services provided.^13–15 Therefore surgical techniques need to be adapted to continue to be innovative and requires a full comprehension of previous techniques, complications and future challenges. Incision to the anterior cervical spine is based on approach to the recurrent laryngeal nerve.^16–19 However the standard surgical dissection for the anterior cervical spine involves splitting the platysma.⁵

The authors hypothesized that the traditional muscle-splitting approach through the platysma muscle during surgical access to the anterior cervical spine can potentially increase surgical time with time spent ensuring hemostasis on entry and suturing the muscle on closure, can potentially increase blood loss and also contribute to worsened cosmesis.²⁰ A simple and less exposure surgery approach is described and compared, which allows the platysma to glide easily over the sternocleidomastoid muscle and enabling a less invasive technique.

2 Method

We examined the medical records of 496 prospective patients who underwent single and two-level anterior cervical spine surgery. Two groups were assigned: Group 1 (259 patients) included patients who had a platysma muscle-sparing approach in outpatient setting. Group 2 (237 patients) had a standard muscle-splitting approach in the inpatient setting. Muscle-sparing involved using the groove between the platysma and sternocleidomastoid muscles and the loose connective tissue layer (the superficial cervical fascia²¹) as a landmark.

Indications for TDR surgery included symptomatic, spontaneous/degenerative or traumatic herniated cervical nuclei pulposus with or without radiculopathy and cervical degenerative disc degeneration (DDD) without posterior column instability. Indications for ACDF surgery included cervical spondylosis, stenosing herniated discs, degenerative disc disease with instability and facet arthritis, tropism or facetogenic pain. Patients were only considered for surgery after failed conservative management for at least six weeks.

Patient-reported visual analog scores (VAS) for pain both preoperatively, and at the six-month postoperative follow-up appointment were evaluated. Additionally, a questionnaire was developed to evaluate platysma sparing (Fig. 1).

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Fig. 1 Questionnaire evaluating platysma sparing approach.

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2.2

2.2 Surgical technique

Patients were placed under general anesthesia, appropriately positioned, cleaned and draped in the standard sterile surgical fashion. A transverse midline skin incision was made along Langer's lines in skin crease closest to operative level. Subcutaneous dissection was performed above the platysma with the aid of dissecting scissors and skin retractors to expose the platysma muscle (Video 1). The muscle-sparing technique used for access deep to the platysma muscle in Group 1 involved finger retraction from lateral to medial with placement of a Richardson appendiceal retractor to hold the soft tissue out of the operative field (Video 1). The deep cervical fascia identified (Fig. 2) and further dissection performed to expose cervical vertebrae. Operative procedure performed, hemostasis achieved and a Penrose drain placed. Releasing the retraction was all that was required with preservation of platysma demonstrated prior to skin closure (Video 2).

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Figure 2 Photograph of deep cervical fascia.

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Patients in Group 2 technique transverse skin incision, incise fascia over platysma, split platysma and identify anterior border of sternocleidomastoid (SCM). After which fascia of SCM incised and SCM retracted lateral with strap muscles retracted medially. Standard operative techniques and hemostatic measures were then completed with closure of the platysma incision and subcutaneous layers with sutures in Group 2.

Supplementary video related to this article can be found at https://doi.org/10.1016/j.jor.2019.06.003.

The following are the supplementary data related to this article:Video 1Video demonstrating dissection technique of sparing platysma after initial incision, down to deep cervical fascia.2Video 2Video showing intact platysma muscle with Penrose drain prior to skin closure.3

3 Results

Overall mean age of 51.57 ± 0.8 years, 259 patients in Group 1 (platysma-sparing) 49% were female with the group's mean age being 50.8 ± 0.89 years and BMI 27.77 ± 0.47 kg/m². Of the 237 patients in Group 2 (platysma splitting) 53% were female with the group's mean age being 51.5 ± 1.2 years and BMI 23.3 ± 1.5 kg/m². No statistical differences in gender, age and BMI were found between groups, p = 0.473, 0.219 and 0.165 respectively. In group 1, 159 (62%) single level and 100 (38%) two levels procedures performed. In group 2, 146 single level and 91 two levels procedures were performed demographics are summarized in Table 1. There was no significance between preoperative VAS neck, arm and NDI scores between Groups 1 and 2, p = 0.129, p = 0.484, and p = 0.401 respectively. Analysis of follow up at six months demonstrated; group 1 mean preoperative VAS neck scores improved from 7.6 ± 0.2 to 3.9 ± 0.1, p < 0.001. Preoperative VAS arm score improved from 4.5 ± 0.2 to 2.7 ± 0.2, p < 0.001. Preoperative mean NDI score decreased from 51.0 ± 1.6 to 26.3 ± 0.8 at six month follow up, p < 0.001. Group 2 mean preoperative VAS neck scores improved from 8.3 ± 1.0 to 4.7 ± 0.3 at six month follow-up, p = 0.001. Preoperative VAS arm scores improved from 4.8 ± 0.5 to 2.9 ± 0.2, p < 0.001. Preoperative mean NDI reduced from 48.1 ± 2.1 to 32 ± 1.2 at six month follow up, p = 0.001. There is an overall improvement in VAS neck, arm and NDI scores shown in Figs. 3 and 4 respectively. Intergroup comparison of postoperative outcomes demonstrated statistical significant difference in VAS neck and NDI scores p = 0.009 and p = 0.012 respectively. No difference was demonstrated in VAS arm scores, p = 0.173. The surgical operative time in group 1 was 91 ± 6 min as compared to group 2 which was 139 ± 3 min, p = 0.003. Estimated blood loss of 55 ± 3 ml in group 1 compared to 81 ± 9 ml in group, p = 0.006.

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Figure 3 Bar graph depicting VAS neck and arm scores.

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Fig. 4 Bar graph depicting NDI scores.

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The main postoperative complaint of postoperative dysphagia was defined as any discomfort or difficulty with swallowing which was not historically present prior to surgery. The severity was assessed using the Bazaz-Yoo dysphagia severity scale of mild, moderate and severe, over the initial 3 month postoperative period.²² A total of 9 patients complained of dysphagia, 3 patients in group 1 and 6 patients in group 2, p = 0.3216. There were no post op wound infections reported in either group.

4 Discussion

Surgical treatment of the anterior cervical spine is indicated for a range of clinical pathologies most commonly trauma, deformities and age-related degeneration. In particular, ACDF, popularized in the 1950s, has established itself as one of the safest and most frequently performed spine surgeries today.^23,24

The surgical approach is primarily dependent on surgeon-discretion. Proponents for a left-sided approach have shown a reduction in risk of injuring the more variable right recurrent laryngeal nerve, further reduced when combined with intermittent endotracheal cuff deflation.²⁵

There is no evidence-based consensus found in the literature, which guides the surgeon's decision to incise the platysma muscle during the first phase of surgical access. Retraction of the platysma has not been shown by our results to increase the risk of postoperative dysphagia. In a surgical subspecialty that is rapidly transitioning toward minimally and less invasive techniques and approaches to the spinal column, these results are in favor of the less invasive philosophy of anatomy preservation and reduction of patient morbidity. A study by Agrawal et al.²⁰ demonstrated improved cosmesis with less puckering of the skin by splitting the platysma compared to cutting.

Our study findings demonstrate improved outcomes for VAS neck and NDI scores. There was also statistically significant less pain as it relates to use of platysma muscle based on survey at 48 h and three months post op (Table 2 and Table 3).

A few limitations of this study were identified; objective measurements of surgical time gained with the muscle-sparing technique and the blood loss prevented. Surgical time recorded was for overall procedure and not at each stage of procedure: (1) The theoretical time gained by avoiding incision and closure of the muscle was not measured as this is a retrospective review (2) however, the authors believe this may have impacted overall surgery time but unable to justify clinical significance. With regards to blood loss, only overall blood loss was recorded and not during the specific stage of the operation presented. Furthermore, both TDRs and ACDFs were included in both groups, which would impact surgical time as well as blood loss independently with the more extensive and technically demanding ACDF having higher expected values for each parameter.

The authors no longer practice splitting the platysma during an anterior approach to the cervical spine and have shown that patients have satisfactory clinical outcomes.

5 Conclusion

The technique description provided has been shown improved clinical outcomes by a statistically significant margin as well as improved pain at 48 h an three months postoperatively; while not impacting the incidence of dysphagia when compared with the standard muscle-splitting approach. We acknowledge that the traditional muscle-splitting method employed by many surgeons does not harbor any catastrophic clinical consequences. However, the decrease in blood loss and operative time, does give merit to a muscle-sparing approach, at least in an outpatient setting; where less is always more for the surgeon, institution and most importantly, the patient.

Conflicts of interest and sources of funding

We did not seek or receive any funding from the National Institutes of Health, Wellcome Trust, Howard Hughes Medical Institute, or others for this work. KRC is a shareholder in and receives other benefits from SpineFrontier Inc.; none of the other authors (FJRP, AB, JAS) have any potential conflicts of interest to declare for this work.