Complications, outcomes, and need for fusion after minimally invasive posterior cervical foraminotomy and microdiscectomy

Abstract

Background context

Posterior cervical foraminotomy (PCF) with or without microdiscectomy (posterior cervical discectomy [PCD]) is a frequently used surgical technique for cervical radiculopathy secondary to foraminal stenosis or a laterally located herniated disc. Currently, these procedures are being performed with increasing frequency using advanced minimally invasive techniques. Although the safety and efficacy of minimally invasive PCF/PCD (MI-PCF/PCD) have been established, reports on long-term outcome and need for secondary surgical intervention at the index or adjacent level are lacking.

Purpose

To determine the rates of complications, long-term outcomes, and need for secondary surgical intervention at the index or adjacent level after MI-PCF and microdiscectomy.

Study design

Retrospective analysis of a prospective cohort.

Patient sample

Seventy patients treated with MI-PCF and/or MI-PCD for cervical radiculopathy.

Outcome measures

Visual Analog Scale for neck/arm (VAS_N/A) pain and Neck Disability Index (NDI).

Methods

Ninety-seven patients underwent MI-PCF with or without MI-PCD between 2002 and 2011. Adequate prospective follow-up was available for 70 patients (95 cervical levels). The primary outcome assessed was need for secondary surgical intervention at the index or adjacent level. The secondary outcomes assessed included complications and improvements in NDI and VAS_N/A scores. All complications were reviewed. Mixed-model analyses of variance with random subject effects and autoregressive first-order correlation structures were used to test for differences among NDI, VAS_A, and VAS_N measurements made over time while accounting for the correlation among repeated observations within a patient. All statistical hypothesis tests were conducted at the 5% level of significance.

Results

Patients were followed for a mean of 32.1 months. Of 70 patients operated, there were 3 (4.3%) complications (1 cerebrospinal fluid leak, 1 postoperative wound hematoma, and 1 radiculitis), none of which required a secondary operative intervention. Five patients required an anterior cervical discectomy and fusion (eight total levels fused) on average 44.4 months after the index surgery. Of those, five (5.3%) were at the index level and three (2.1%) were at adjacent levels. Neck Disability Index scores improved significantly (p<.0001) immediately postoperatively and continued to decrease gradually with time. Visual Analog Scale for neck/arm scores improved significantly (p<.0001) from baseline immediately postoperatively but tended to plateau with time.

Conclusions

Minimally invasive PCF with or without MI-PCD is an excellent alternative for cervical radiculopathy secondary to foraminal stenosis or a laterally located herniated disc. There is a low rate (1.1% per index level per year) of future index site fusion and a very low rate (0.9% per adjacent level per year) of adjacent-level disease requiring surgery.

Introduction

Evidence & Methods

Interest in motion-preserving approaches for the management of cervical degenerative conditions has increased in recent years. While many studies with short-term follow-up support the safety of these interventions, there is little information on the long-term impact of such procedures, particularly the need for further surgery. In this context, the authors performed a retrospective review of a series of 70 patients with approximate mid-term follow-up (mean 32.1 months).

The authors noted substantive improvements in neck pain and neck disability index scores following surgery. Approximately four percent of patients sustained a complication and 5% necessitated an anterior cervical fusion within the follow-up period.

This study provides further information on the safety profile and short-term efficacy of minimally invasive posterior cervical foraminotomy and microdiscectomy. However, the data may have been collected, this study is a retrospective analysis and subject to confounding by selection, indication, information bias, and patients lost to follow-up. The study presents a series of patients treated in like fashion, without any control arm. Additionally, with a mean follow-up of less than three years' time, this study may be at risk of under-reporting the long-term need for further surgery.

—The Editors

Cervical radiculopathy is one of the most common pathologies treated by spinal surgeons. Although many patients will respond to appropriate nonoperative measures, those who continue to be symptomatic have several surgical options available. Whereas anterior cervical discectomy and fusion (ACDF) remains the gold standard for the surgical treatment of cervical radiculopathy, motion-preserving procedures including disc replacement and posterior cervical foraminotomy (PCF) have become popular alternatives [1].

Posterior cervical foraminotomy is a motion-preserving technique that was first described by Spurling and Scoville in 1944 [2], but today, it can be performed using advanced minimally invasive techniques. When performed minimally invasively, authors have shown equivalent efficacy to open procedures with a significant reduction in blood loss, postoperative length of stay, and postoperative medication use [4], [5], [6], [7]. The procedure can be divided into minimally invasive PCF (MI-PCF) or MI posterior cervical discectomy (MI-PCD) that includes a foraminotomy. Candidates for this surgical technique include patients with a soft-disc herniation lateral to the spinal cord and compressing the nerve root or with foraminal osteophytes originating from the facet joint[3]. Contraindications to PCF/PCD include pure axial neck pain without neurologic symptoms, gross cervical instability, symptomatic central disc herniation, diffuse ossification of the posterior longitudinal ligament, and a kyphotic deformity of the cervical spine [4]. Although several studies have shown that MI-PCF/PCD is an effective option in the treatment of cervical radiculopathy, to our knowledge, no study has investigated the need for secondary surgery at the index or adjacent level after this procedure. The purpose of our study was to report on the long-term outcomes and need for secondary surgical intervention at the index or adjacent level after MI-PCF/PCD.