In the present study, the prevalence of FBSS was 11%, and this rate is in the range reported elsewhere as the incidence of FBSS is recognized to be between 10% and 40% after lumbar laminectomy with or without fusion [2]. In the current study, the female to male ratio was 1.0:1.6, and this result differs from that reported by Fritsch et al. [10], and Parker et al. [11] where the rate is approximately equal in both sexes. In the present study, the most frequent age group was 40-49 years with a mean age of 50.3 years. These results differ from those reported from Georgetown University where the mean age of BFSS patients was 67 years, and 80% of them were over 60 years old [12,13]. The incidence of FBSS in younger age groups compared to older ages in other countries around the world may reflect that the lifespan of people in Yemen is lower than that in other countries for example for Iran it is 77 years old, Saudi Arabia is 75 years old and the USA is 85 years old The United Kingdom is 85 years old, while in Yemen 66 years [14].

Regarding the first symptoms that occurred after laminectomy in the current study, the incidence of back pain was only 16.1% or leg pain only 6.4%, while most patients had back and leg pain (77.5%). Symptoms of FBSS should ideally begin with a detailed evaluation of the history and clinical examination. The evaluation should compare preoperative symptoms with recent symptoms. If the pain is in its first onset or is the similar such as the pain before surgery, the cause may be intraoperative or postoperative complications [15]. Central is defined as pain move on the way to or from the lumbar spine as a result of repetitive motions, and is suggestive of disc pain. Radicular pain may be due to insufficient decompression, foraminal stenosis, recurrent disc herniation or epidural fibrosis [15]. In most cases [15], it includes back and foot pain, as it is with the patients of the current study.

In the current study, regarding first onset of FBSS: early onset occurred in 38.7% of FBSS patients, while median time onset occurred in 13% of FBSS patients, while late onset occurred more frequently as 48.3% showed late onset. This result is similar to that reported by Waguespack et al. [16] and Waddell et al. [17] as late onset of FBSS occurred in more than 50% of their patients. If the pain is in its early beginning or is the similar such as the pain before surgery, it may be attributable to intraoperative or postoperative complications [15]. Regarding FBSS by postoperative diagnosis (postoperative causes), herniated disc was the most common diagnostic cause associated with FBSS patients accounting for 58.1% of cases, followed by instability accounting for 32.2%. Postoperative causes can be separated into surgery-related factors and disease progression. Recurrent herniated discs are known to occur in approximately 6%–23% of patients who underwent microdiscectomy at the same site or adjacent level [11, 18] less than reported in our study.

Adjacent segment disease, a known complication of lumbar fusion with ra­diological and clinical subcategories, is a significant risk factor for re-operation post primary micro endoscopic dis­cectomy [18]. On the other hand, the incidence of clinical instability (adjacent segment disease) is thought to be approximately 27% [19] close to our rate (32.2%); Sagittal balance plays an important role because unbalanced and compensated balanced spines predispose to adjacent disc degeneration [20].  Therefore, radicular pain might be due to foramen stenosis, as nerve root entrapment in epidural fibrosis is believed to be a causative or contributing factor to postoperative pain in 20% - 36% of FBSS cases [2,15], while canal stenosis accounted for 9.7%.  in the current study.  A history of improvement occurred after the first operation in the patients between good improvement in 64.5% of FBSS patients and very good improvement occurred in 9.7% while there was no improvement in 22.6% of FBSS cases. Regarding FBSS interference with daily activities of FBSS patients, 54.8% of FBSS patients answered yes while the rest said no.

In the current study, a wrong level was diagnosed in 21.1%, recurrent disc at the same level was diagnosed in 29%, canal stenosis was diagnosed in only 3.2%, root injury was diagnosed in 9.7%, instability in 19.4%, fibrosis in 9.7%, and adhesive arachnoiditis in 6.5 %. While 6.5% of FBSS patients had no causes diagnosed.  Patients who have undergone one or more operations on the lumbar spine and continue to experience pain afterward can be divided into two groups. The first group consisted of those for whom surgery was not actually indicated or for whom the surgery was not likely to achieve the desired result, and those for whom surgery was indicated but technically did not achieve the desired result [7]. Patients whose complaints of pain are of a radicular nature have a better chance of achieving a good outcome than those whose pain is limited to back pain. The second group includes patients who underwent incomplete or inadequate surgeries. Lumbar spinal stenosis possibly will be unnoticed, particularly when correlated with disc protrusion or herniation. Disc removal, while not treating the primary presence of the stenosis, can lead to disappointing results [8]. Occasionally operating on the wrong level occurs, as does failure to recognize an extruded or sequestered disc fragment. Inadequate or inappropriate surgical exposure can lead to other problems if the underlying pathology is not reached. Hackelius reported a 3% incidence of serious nerve root damage [9]. Regarding assessment and prognostic methods used in diagnosis and follow-up of patients, CT was used in 58.1% of FBSS patients and MRI was used in 41.9% of patients.  As it known Computed Tomography (CT), another excellent modal­ity to assess spinal instrumentation-related complications, can help qualify and quantify a fusion mass in an instru­mented spine when instrumentation removal is contem­plated [21]. In patients with contraindications to MRI, Computed Tomography (CT) myelography can be employed which might show the compres­sion of neural structures by bony or other elements [15].  The treatment of FBSS presents a major, similar dilemma to the patient and physician. It needs to be emphasized that FBSS treatment should be multidisciplinary. As a team, pain physicians, spine surgeons, physical therapists, and psychiatrists should target demystifying the pain for the patient. Further, the alternative definition of FBSS that “its consequences when the result of lumbar spine surgery does not convene the preoperative expectations of the patient and surgeon” [16], leads to patient education being con­sidered paramount; patients should be an integral part of the treatment process. In the current study regarding the second types of management applied in our FBSS patients, surgical treatment was performed in FBSS patients in 61.3% and conservative intervention in 38.7%. Removal of a disc at one level can lead to disc herniation at a different level at a later time. Even the most complete surgical excision of the disc still leaves 30–40% of the disc, which cannot be safely removed. This retained disc can re-herniate sometime after surgery. Virtually every major structure in the abdomen and the posterior retroperitoneal space has been injured, at some point, by removing discs using posterior laminectomy/discectomy surgical procedures. Most notable is the rupture of the left internal iliac vein, which is located near the front of the disc [22,23].  In some studies, recurrent pain in the same radicular pattern or a different pattern can be as high as 50% after disc surgery [23,24].  In fact, Surgical management of FBSS should be reserved for pa­tients with a documented anatomic or pathologic cause for their pain and/or with failed medical treatment [2]. As the fact, the success rate of the surgery decreases with every reoperation [26].