Bertolotti’s Syndrome is defined as chronic low back pain caused by lumbosacral transitional vertebrae. In the spines of these patients, the enlargement of the caudal lumbar vertebrae at the transverse process leads to the fusion or articulation of the transverse process with the sacrum or the ilium, causing discogenic disease and limiting mobility.1 This congenital lumbosacral transitional vertebra (LSTV) defect, which has various presentations, may present as lower back pain syndrome in the third and fourth decade of a patient’s life. Once the cause of the low back pain has been established as LSTV, it is classified as Bertolotti’s Syndrome.2 The pain caused by Bertolotti’s Syndrome is not uniform and originates from different pathology caused by the LSTV. These pathologies include scoliosis, arthropathy of the joints, and muscle strains of the quadratus lumborum and iliopsoas.1 The deformation of the transitional vertebra may cause nerve compression due to compressed discs resulting in neuropathic pain.1 On average, patients report daily pain at above 5/10.3 Along with significant pain, patients with Bertolotti’s Syndrome self-report an average of over 36% on the Oswestry disability scale, correlating to a moderate disability that affects many aspects of daily life.3–5 The patients who have LSTV tend to have a more significant spinal degeneration above the deformity than other conditions leading to chronic lower back pain. However, they tend to have similar levels of pain and disability to those that have back pain without having LSTV.3

Related to its similarity in pain and disability with other causes of back pain, Bertolotti’s Syndrome is diagnosed in two parts; a clinical assessment of pain and advanced imaging demonstrating these anomalies.1–6 Clinically, Bertolotti’s Syndrome presents various pain and tenderness, symmetrically or asymmetrically, at the sacroiliac area, hip, and groin. There may be radicular pain due to nerve compression or pseudo-radicular pain-related due to the bone-on-bone contact at the pseudo-articulate joint of the transverse vertebra.2–7 A clinical exam can include an intra-articular diagnostic block with lidocaine 2% and bupivacaine 0.5% at either the sacroiliac joint or the facet joint under fluoroscopic guidance. Achieving an 80% decrease in pain following these injections is diagnostic.1 Bertolotti’s Syndrome presents with non-specific back pain; therefore, confirmation of the diagnoses must be made through radiologic examination of the lumbosacral spine.1 The lumbosacral spine radiographs will demonstrate unilateral or bilateral enlargement of the transverse processes with potential articulation with the sacrum or ilium.8 These can be complemented with an MRI of the lumbosacral spine if there is radicular pain leading to a suspicion of discogenic pain.1

Bertolotti’s Syndrome encompasses many types of LSTV that are defined under the Castellvi system. In 1984, Dr. Antonio Castellvi determined four defining types of LSTV through examinations of myelograms of 200 patients.9 These four types of LSTV include: Type I-dysplastic transverse process that is at least 19cm wide, Type II-transverse process growth leading to an incomplete sacralization or lumbarization of the transverse process, Type III-complete transverse process sacralization/lumbarization, and Type IV- mixed complete sacralization and incomplete sacralization.9 Of the Castellvi classifications, the most commonly seen LSTV is Type 1 (42%), followed by Type II (38%), Type III (8%), and Type IV (5%).9 Disc herniations are often present at single levels, although some patients have herniations of multiple discs due to the lumbosacral transitional vertebra.9


The presence of an LSTV causes changes in the biomechanics of the spine. Normal skeletal anatomy utilizes the sacrum’s size, surface area, and sacroiliac joint to dissipate the upper body’s weight across the fused bony sacrum and into the legs.10 However, the presence of an LSTV has been shown to cause hypomobility at the L5/S1 level and hypermobility at the superjacent and superior lumbar levels.11

For over a century, the disruption in the biomechanical axis of the spine caused by LSTV has been argued to be causally related to the development of lower back pain. The development of lower back pain is hypothesized to be from the earlier presentation of arthritic changes, disc herniation, disc degeneration, or spinal canal and foraminal stenosis.12,13 Otani et al. found in 2001 that disc herniations occurred more frequently (17% vs. 11%) and at an earlier age (35 yo vs. 59 yo) in patients with LSTV than those without LSTV.14 Additionally, studies have shown that foraminal stenosis, disc degeneration, and facet degeneration occur more frequently at the level immediately above the LSTV than at that same level in patients without LSTV.15

Hanhivaara et al. found that LSTV of Castellvi Types II, III, and IV are associated with higher amounts of lumbar disc degeneration at all lumbar levels except L2-L3.16 In the setting of acute lumbar disc herniation, Kanna et al. demonstrated the presence of an LSTV was the most significant predictor of a failed selective nerve root block with an Odds Ratio of 20.1.17 In patients with low back pain, the presence of an LSTV is linked with a significantly higher amount of sacroiliac joint dysfunction than in those without an LSTV.18


Bertolotti’s Syndrome has a widely debated incidence. Studies have projected that between 4 and 36% of people have LSTV.19 Hsieh et al. analyzed patients who had no current symptoms and determined by radiographic imaging that 4% of the population of chiropractic patients had LSTV of Castellvi types II-IV.20 Examining radiographs of 6200 patients in the general population, Ucar et al. determined that 18.7% of people in the general public have LSTV.21 The study determined that there are significantly more men with LSTV than there were women with LSTV in the general population.21 As well, there are significantly more men with sacralization of their LSTV than women.21 This study found that the Castellvi Type Ia and Ib dominated the diagnosis of LSTV followed in order by IIa and IIb, IIIa and IIIb, and IV.21 Although there is a high incidence of LSTV in the general population, many are asymptomatic, leading to a debate about whether LSTV is a true cause of back pain. While Castellvi determined pain is derived from the anomaly of the lumbar spine, others have determined pain and severity of back pain are not associated with LSTV.9,14,22 Due to the historical uncertainty of the connection between lower back pain and the LSTV, it is difficult to define the true incidence of patients with Bertolotti’s Syndrome. To determine its actual prevalence, Elster examined 2000 patients who lived with lower back pain and determined that 140 (7%) patients had LSTV and thus were diagnosed with Bertolotti’s Syndrome.23

Conservative Management

Case reports have demonstrated a successful reduction in pain through a 1-month follow-up using an injection of triamcinolone acetate and lidocaine at the articulation of the ilium and the transverse process.24 Physical therapy represents another modality, with one case report utilizing lumbosacral manipulation and exercises resulting in improvements in pain and mobility over two weeks.25 Similarly, two patients undergoing manual therapy under the care of a chiropractor noted substantial but incomplete improvement, one at two weeks and one at four weeks, in their perceived pain levels and mobility.26 While not explicitly addressed in Bertolotti’s Syndrome, a 2015 systematic review reported Pilates may provide short-term benefit over minimal physical exercise or no intervention for patients with non-specific chronic low back pain.27 Authors did note large heterogeneity in the analyzed studies, including outcome measures and actual Pilates protocols.27 As much of the current data is based on small populations with highly variable follow-up, further study is needed before reliable conclusions on conventional management can be drawn.

Forms of conservative management for Bertolotti’s Syndrome include activity modification, pharmacologic therapy, physical therapy, and interventional therapy.28 In a case series of 5 patients with heterogeneous symptoms and pain generators, Zhang et al. suggested that transforaminal or interlaminar epidural steroid injections may provide some benefit when presentations are consistent with irritation of the nerve root.28 A recent review by Holm et al. highlights the difficulty of directly comparing the current data on steroid management as compared to surgery.29 In one prior study, the use of local lidocaine at the pathologic joint in 10 of 11 patients in the cohort led to 5 who were pain-free and 4 with immediate pain reduction.30 These patients were not naïve to injections or physiotherapy, and all 11 were eventually given surgical management.30 The outcomes at follow-up were improved or pain-free in 9 of 11, and the authors hypothesized that response to anesthetic injection might correlate to future successful surgical management.30

In contrast, Santavirta et al. did not necessarily note this association.31 Of 16 study patients for surgical intervention, 6 had local anesthetic injections in the transitional articulation, which authors noted did transiently relieve the pain.31 However, only 4 of the 6 later had a successful surgical intervention, leading to the conclusion that a preoperative response may not correlate well with the ultimate treatment result; however, they still did recommend a role in using anesthetic injections in the diagnostic workup.31 Additionally, as local anesthetic and steroids are sometimes given within a short period, or perhaps even mixed, it makes isolating the effects of steroids themselves difficult. In a study of 15 patients comparing injections of lidocaine with saline versus lidocaine with cortisone (glucocorticoid receptor agonist), for symptomatic LSTV type II or IV, there were no differences between groups, yet when pooled patients did experience significant reductions in mean VAS scores from baseline to 4 weeks as well as the 12-week timepoint.32 Combined injections serve as a common approach, as Marks et al. reported 8 of 10 patients in the cohort studied experienced total relief within 30 minutes of infiltration with methylprednisolone acetate and lidocaine with relative pain relief lasting from 1 day to over 27 months in this cohort.33

Surgical Management

There are surgical options to treat Bertolotti’s Syndrome. Although an effective method of treatment when indicated, there are inherent risks with surgery. One of the most common forms of treatment is resection, also known as the “Processectomy,” of the lumbosacral transitional vertebra. This surgery addresses back pain in a patient with LSTV related to the mechanical stress of the pseudo articulation or the articulation.30,34,35 To determine if the pain is from the LSTV, a diagnostic anesthetic block is done, looking for positive pain relief.34 If positive, a surgeon may partially remove or completely resect the LSTV.35 Studies reviewing the outcomes of the surgical resection of the LSTV have demonstrated positive outcomes .in these cohorts. In a study by Jonsson et al. following eleven patients undergoing resection, seven patients had alleviated all of their pain, and two of the patients had alleviated a proportion of their pain.30 Four of the patients reported increased mobility directly following the resection due to the freed transverse process and decreased biomechanical stress.30 Of the two failed surgeries, one was determined to be due to previous degeneration of the spine, while the failure of the other was due to unknown factors.30 As such, resection of the LSTV should be performed in younger patients who do not present with degeneration of the spine.30,31

In a retrospective study, patients with Bertolotti’s Syndrome of Castellvi type I or II who underwent the transverse processectomy had decreased pain, as reported by the VAS pain quantifying system, of 50% from their preoperative levels.34,36 Despite the relief in the pain levels that the patients had, five of the eight patients who had undergone the resection presented with degeneration of the disc above the previously resected vertebrae. Three of those who had the resection were subjected to a second surgery due to the failure of the first surgery to manage the symptoms.31 Resection should be limited to select patients; those absent of adjacent transitional vertebrae disc pathology are most likely candidates for the resection procedure.31

A spine fusion is a surgical procedure that helps relieve the chronic pain caused by Bertolotti’s Syndrome. A study by Santavirta followed eight patients who underwent a resection of the transverse process and eight who underwent a posterolateral fusion. When comparing the long-term outcomes, the fusion cohort had an increased disc degeneration in the disc immediately superior to the fusion, with 7 of 8 patients showing degeneration at follow-up.31 However, patients with previous disc degeneration of the LSTV disc, but not the superior disc, fared better with the fusion than the resection.31 As such, it is recommended that fusion be considered on selected patients who have previous disc pathology.

In examining surgical efficacy compared to non-operative management, Santavirta demonstrated the surgical group fared only slightly better than the non-operative controls (1.9 versus 2.5 on the Oswestry Scale), independent of which surgery they received.31,37 Undergoing a surgical procedure is considered a last line of treatment. However, it can manage pain effectively, as seen in the studies of patients receiving resections and fusions. Although these results were positive, it is recommended that surgery, whether resection or fusion, not be the first line of treatment for patients with Bertolotti’s Syndrome. Still, instead, patients should be offered physiotherapy, ergonomic relief efforts, and other less invasive treatment options before being offered the opportunity for surgery.30,31,35

Some patients undergo decompression of the stenosed foramen below the LSTV. Patients who have radiculopathy due to the LSTV are candidates for nerve decompression surgery. The decompression requires the translocation of the nerve medially and the resection of the bone spur or pseudoarticulation.38 A recorded complication from this surgery was transient hypesthesia that resolved after two weeks.38 Certain hypothesized positioning variations to the surgical methods have been proposed to minimize the temporary hypesthesias of the leg.38 A study by il Ju et al. examined decompression in conjunction with resection surgery, documenting a decrease in the VAS pain score by 72% postoperatively.34 Decompressive surgery of the nerve root can relieve pain by freeing the nerve from the anomalous growth of the transverse process. Related to its variation of anatomical presentation, surgeons must take an individualized approach to a surgical operation on patients with Bertolotti’s Syndrome.7

Radiofrequency Ablation

Continuous radiofrequency ablation (RFA) for pain management arose in the mid to late 20th century, designed to create coagulative necrosis using a high-frequency alternating current.39 Several types of nerve ablation exist, including chemical, direct electrical, cryoablation, and radiofrequency-based ablation, the latter of which spans subtypes such as pulsed RFA, cold RFA, and bipolar RFA. In considering an approach to general sacroiliac joint pain, unlike ablation for lumbar nerves, there is more anatomic variation in sacral branches.40 A cooled RFA technique was developed to generate a larger lesion to compensate for variable nerve locations. However, compared to traditional RFA, this technique did not lead to any difference through 12 months, with only about 40% of patients in both groups reporting over 50% pain relief at the 3-month time point.41

A newer method under investigation involves bipolar RFA therapy along a strip overlying the sacrum targeting L5-S3. This newer method requires further study but may represent an improvement over cold-RFA, with over 70% of patients retaining over 50% pain relief at three months.42 The development of these ablative techniques in general sacroiliac joint pain may warrant their investigation in Bertolotti’s Syndrome. In a report out of Alberta, Canada, a 56-year-old woman with initial pain treated with L4/L5 facet joint RFA did not have a durable response, was found to have an elongated L5 transverse process with sacral articulation, and was finally treated with bipolar RFA strip lesions around this area, leading to complete pain control until 16-month follow-up.43 Their initial protocol was to lesion circumferentially around the articulation, using fluoroscopic guidance and two 18-gauge RF needles placed 2-3mm from the articular margins, using a temperature of 80 degrees Celsius and contact time of 90 seconds.43 This case report was one of the first to document a successful RFA technique for Bertolotti syndrome.43,44

More recently, a team from Japan reported success with pulsed RFA among four patients with Castellvi type IIa/b through a mean follow-up at eight months, using pulse widths of 20ms and 20 V at 42 degrees Celsius for 4 minutes at three sites.45 They reported that in their experience, this technique led to less procedural pain compared to thermal RF.45

A current limitation with the analysis of these case reports is the uncertainty of the pain generator and how management should differ in the various subtypes of LSTV.10,24 In a study restricted to 20 Bertolotti’s syndrome Castellvi type 1a patients with scoliosis, the most common source of pain was the ipsilateral facet joint; however, contralateral facet joint pain, sacroiliitis, discogenic pain, and non-articulation pain were also reported.1 We were unable to find specific applications of discogenic therapies for Bertolotti’s Syndrome; however, the following two examples represent possible future directions based on work in general lower back pain patients. If the patient’s pain is discogenic in nature, two or more treatments of RF lesioning of the ramus communicans at 80 degrees Celsius for 60 seconds may improve such pain.46 Another approach for discogenic pain involves introducing a thermal resistive coil into the center of the target disc, heating the coil to 90 degrees Celsius, corresponding to an annular temperature in the 60-degree Celsius range, and leaving it in place for 4 minutes. This approach aims to shrink collagen and coagulate nerve tissue, thus theoretically addressing both mechanical and nociceptor components of discogenic pain and was reported to be efficacious in some LBP patients.47 Because patient presentation may be heterogeneous. The most successful therapy is hard to predict initially. Further research into the efficacy of non-surgical ablation techniques for patients with Bertolotti’s Syndrome is warranted.


Bertolotti’s Syndrome is a back-pain syndrome caused by a congenital defect of the last vertebra of the lumbar spine leading to the articulation, pseudo articulation, or full fusion of the transverse process to the sacrum the ilium. Bertolotti’s Syndrome, which is present in approximately 7% of chronic lower back pain patients, is defined as a pain syndrome in conjunction with the LSTV. There are many treatment options for Bertolotti’s Syndrome. However, a lack of research into the Syndrome hinders evidence supporting one specific therapy.

Outlined in Jancuska et al. is a guideline for the step-based therapy for Bertolotti’s Syndrome.10 It is essential to start with conservative methods, including activity modification, physiotherapy, steroid injections, and anesthetic injections. Failure of these modalities signals for a progression towards interventional and or surgical management. Surgical methods, which have proved only slightly superior to non-surgical management, can differ depending on the preoperative degeneration of the spine. Resection and posterolateral fusion are both equally effective methods. Still, they both hold general surgical risks and the risk of revision surgery and further degeneration of the adjacent level. Radiofrequency ablation in any form (continuous RFA, pulsed RFA, cold RFA, or bipolar RFA) may provide an effective treatment method for patients with Bertolotti’s Syndrome. Ablation can address the nociceptive and mechanical pain caused by Bertolotti’s Syndrome, but there is currently a lack of research into RFA treatment for the variable presentations of LSTV. It is important that when patients present with back pain and LSTV, they are approached individually.

Declarations of Interest

We declare no competing interests

Conflict of Interest