Dural tear is associated with an increased rate of other perioperative complications in primary lumbar spine surgery for degenerative diseases

Incidental Durotomy Repair in Lumbar Spine Surgery: Institutional Experience and Review of Literature

STUDY DESIGN

: Retrospective Chart Review.

OBJECTIVES

Incidental durotomies (IDs) are common spine surgery complications. In this study, we present a review on the most commonly utilized management strategies, report our institutional experience with case examples, and describe a stepwise management algorithm.

METHODS

A retrospective review was performed of the electronic medical records of all patients who underwent a thoracolumbar or lumbar spine surgery between March 2017 and September 2019. Additionally, a literature review of the current management approaches to treat IDs and persistent postoperative CSF leaks following lumbar spine surgeries was performed.

RESULTS

We looked at 1133 patients that underwent posterior thoracolumbar spine surgery. There was intraoperative evidence of ID in 116 cases. Based on our cohort and the current literature, we developed a progressive treatment algorithm for IDs that begins with a primary repair, which can be bolstered by dural sealants or a muscle patch. If this fails, the primary repair can be followed by a paraspinal muscle flap, as well as a lumbar drain. If the patient cannot be weaned from temporary CSF diversion, the final step in controlling postoperative leak is longterm CSF diversion via a lumboperitoneal shunt. In our experience, these shunts can be weaned once the patient has no further clinical or radiographic signs of CSF leak.

CONCLUSIONS

There is no standardized management approach of IDs and CSF leaks in the literature. This article intends to provide a progressive treatment algorithm and contribute to the development process of a treatment consensus.

Transforaminal Endoscopic Ventral Stenosis Decompression in Calcified Lumbar Disc Herniation: A Long Term Outcome in 79 Patients

BACKGROUND

Calcified lumbar disc herniations (CLDH) causing calcified ventral stenosis pose a therapeutic challenge to the treating surgeon due to their neural adhesions, location, and hardness.

METHODS

This retrospective study analyzed all the cases of CLDH/calcified ventral stenosis managed by transforaminal endoscopic lumbar discectomy with a minimum follow-up of 24 months. The preoperative images were analyzed for the level, migration; and grade (Lee's migration zones), and location (Michigan State University classification). Detailed surgical technique and intraoperative parameters including the duration of surgery and complications have been recorded. The clinical parameters including visual analog scale (VAS), Oswestry disability index (ODI), length of stay in hospital, days of return to basic work, and patient satisfaction index were analyzed. Postoperatively the images were analyzed for the adequacy of decompression.

RESULTS

The mean VAS for back pain and leg pain was 4.7 ± 2.6 (0-9), and 7.45 ± 2.2 (1-10), respectively. The mean preoperative ODI was 78.2 ± 13.2 (63.2-95.6). Nineteen patients (24%) had neurological deficits preoperatively. The mean duration of surgery was 90.5 ± 15.8 (58-131) minutes. Postoperative magnetic resonance imaging revealed adequate decompression in 97.5% (n = 77). The mean duration of hospital stay was 1.05 ± 0.22 (1-2) days, and the postoperative back and leg pain VAS was 1.14 ± 1.2 (0-3) (P < 0.05) and 1.7 ± 0.5 (0-6) (P < 0.05), respectively. The ODI at final follow-up was 6.5 ± 3.7 (2.2-18) (P < 0.05). Neurological recovery occurred in 17 (89.5%) patients and they returned to basic work/jobs in 19.5 ± 3.3 (14-26) days. The mean patient satisfaction index was 1.18 ± 0.47 (1-2) at a mean follow-up of 5.52 ± 2.91 (2-12.75) years.

CONCLUSIONS

Transforaminal endoscopic lumbar discectomy is a complete, safe, and efficacious procedure in patients with CLDH with earlier recovery considering the surgery is performed with the patient being awake.

Incidental dural tears do not affect the overall patients' reported outcome of spine surgery at long-term follow-up: results of a systematic review

To conduct a systematic review of the literature in order to establish if there is an overall adverse effect of accidental durotomy on the long-term patients' reported outcome after elective spine surgery. A systematic literature search was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data about pre- and postoperative clinical outcomes of patients with accidental durotomy and patients without were extracted and analysed. After screening, eleven studies were included with a total of 80,541 patients. About 4112 of these patients (5.10%) had incidental dural tear. When comparing patients with dural tear to patients without, 9/11 authors found no patients' reported differences at last follow-up. One author found a slightly worse VAS back pain in dural tear patients, and another author found inferior SF-36 and ODI scores in dural tear patients (both below minimal clinically important difference). Accidental dural tear did not have a significant adverse effect on clinical outcome of elective spine surgery. More studies are needed to better demonstrate this result.

Intraoperative and Postoperative Management of Incidental Durotomies During Open Degenerative Lumbar Spine Surgery: A Systematic Review

SUMMARY OF BACKGROUND DATA

Incidental durotomy is a common intraoperative complication of lumbar spine surgery. Intra and postoperative protocols in the management of this common complication vary considerably, with no consensus in the literature.

OBJECTIVE

To systematically review (1) lumbar dural repair techniques for open degenerative procedures; (2) review described postoperative protocols after lumbar dural repairs.

STUDY DESIGN

Systematic review.

MATERIALS AND METHODS

A systematic review of the literature was performed for all articles published from inception until September 2022 using Pubmed, EMBASE, Medline, and Cochrane databases to identify articles assessing the management of durotomy in open surgery for degenerative diseases of the lumbar spine. Two independent reviewers assessed the articles for inclusion criteria, and disagreements were resolved by consensus. Outcomes included persistent leaks, return to the operating room, recurrent symptoms, medical complications, or patient satisfaction.

RESULTS

A total of 10,227 articles were initially screened. After inclusion criteria were applied, 9 studies were included (n=1270 patients) for final review. Repair techniques included; no primary repair, suture repair in running or interrupted manner with or without adjunctive sealants, sealants alone, or patch repair with muscle, fat, epidural blood patch, or synthetic graft. Postoperative protocols included the placement of a subfascial drain with varying durations of bed rest. Notable findings included no benefit of prolonged bedrest compared with early ambulation ( P =0.4), reduced cerebrospinal fluid leakage with fat graft compared with muscle grafts ( P <0.001), and decreased rates of revision surgery in studies that used subfascial drains (1.7%-2.2% vs 4.34%-6.66%).

CONCLUSIONS

Significant variability in intraoperative durotomy repair techniques and postoperative protocols exists. Primary repair with fat graft augmentation seems to have the highest success rate. Postoperatively, the use of a subfascial drain with early ambulation reduces the risk of pseudomenignocele formation, medical complications, and return to the operating room. Further research should focus on prospective studies with the goal to standardize repair techniques and postoperative protocols.

Association between preoperative neutrophil-lymphocyte ratio, uric acid, and postoperative delirium in elderly patients undergoing degenerative spine surgery

PURPOSE

There are few reports regarding the association between the neutrophil-lymphocyte ratio (NLR), uric acid, and the development of postoperative delirium (POD) in patients who are undergoing spine surgeries. We investigated the associations between the NLR, uric acid as a natural antioxidant, and POD in elderly patients undergoing degenerative spine surgery.

PATIENTS AND METHODS

This was a single-center, observational, and retrospective study conducted in Japan. We enrolled 410 patients who underwent degenerative spine surgery. POD was diagnosed after the surgeries by psychiatrists, based on the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V). We performed a multivariable logistic regression analysis to clarify whether the NLR and uric acid values were associated with the development of POD in the patients.

RESULTS

129 of the 410 patients were excluded from the analysis. Of the 281 patients (137 females, 144 males), 32 patients (11.4%) were diagnosed with POD. The multivariable logistic regression analysis revealed that the preoperative uric acid level (adjusted odds ratio [aOR]: 0.67, 95% confidence interval [CI]: 0.49-0.90, p = 0.008) and age (aOR: 1.09, 95% CI: 1.02-1.16, p = 0.008) were significantly associated with POD. The preoperative NLR (aOR: 0.82, 95% CI: 0.60-1.13, p = 0.227) and antihyperuricemic medication (aOR: 0.97, 95% CI: 0.24-3.82, p = 0.959) were not significantly associated with POD.

CONCLUSION

Our results demonstrated that in elderly patients undergoing degenerative spine surgery, the preoperative NLR was not significantly associated with POD, but a lower preoperative uric acid value was an independent risk factor for developing POD. Uric acid could have a neuroprotective impact on POD in patients with degenerative spine diseases.

Incidental Dural Tears During Lumbar Spine Surgery: Prevalence and Evaluation of Management Outcomes

INTRODUCTION

 Incidental dural tears (IDTs) are sometimes observed as an intraoperative complication associated with lumbar spine surgery. Commonly, this complication is recognized and repaired during surgery, but if it is undiagnosed or inadequately treated, a variety of consequences may occur. Many techniques have been developed to treat cerebrospinal fluid (CSF) leakage, and each has its limitations.  Objectives: To assess the prevalence of incidental dural tears in lumbar spine surgeries and evaluate the outcomes of the sandwich technique in the management of this complication.

METHODS

A total of 92 patients who underwent lumbar spine surgery at the Royal Rehabilitation Center in Amman from January 2018 to December 2021 were retrospectively reviewed. Patients were divided into two groups: group A (patients without IDT) and group B (patients with IDT), where group B was repaired using the sandwich technique. The follow-up period was six months. Further, the sandwich technique involves repairing the dural defect with interlocking sutures, painting medical glue around the dural incision, covering this with gelatin sponge, and finally covering the gelatin sponge with medical glue again.

RESULTS

The overall prevalence of IDT in the study group was 14.1%. IDT was more common among elderly patients above the age of 60 (17.2%), females (16.7%), patients with multiple lumbar levels treated (66.7%), open approaches (21%), and those who had previous spinal surgery (72.7%). Most IDTs were diagnosed and managed intraoperatively (84.6%). Among those patients, only one complained of a surgical site infection. Patients in group B had a significantly higher postoperative length of hospital stay, amount of drainage, and operative time compared to group A (P<0.001). Regarding postoperative pain, patients in group B had significantly higher pain on the Numerical Pain Scale at day three post-operation compared to patients in group A (P<0.001).

CONCLUSION

Based on our results, the sandwich technique was effective in the management and prevention of CSF leakage. Further prospective studies with long-term follow-up are needed to confirm our findings.

Risk Factor Analysis of Surgery-related Complications in Primary Thoracic Spine Surgery for Degenerative Diseases and Characteristics of the Patients Also Undergoing Surgery on the Cervical and/or Lumbar Spine

STUDY DESIGN

A retrospective cohort study using prospectively collected data.

OBJECTIVE

This study primarily aimed to investigate the risk factors for surgery-related complications in primary thoracic spine surgery for degenerative diseases using a surgeon-maintained database. The secondary purpose was to elucidate the characteristics of surgically treated thoracic myelopathy that also required cervical and/or lumbar spine surgery in the study period.

SUMMARY OF BACKGROUND DATA

Few studies reported surgical complications and the feature of tandem spinal stenosis in thoracic myelopathy in detail because of their rarity.

MATERIALS AND METHODS

This study included 840 thoracic myelopathy patients undergoing primary surgery for degenerative diseases from 2012 to 2021, investigating the effects of diseases, surgical procedures, and patient demographics on postoperative neurological deterioration, dural tear, dural leakage, surgical-site infection, and postoperative hematoma. In thoracic myelopathy patients who were surgically treated and also undergoing cervical and/or lumbar surgery, we investigated the proportion, the effects of diseases, and the order and intervals between surgeries.

RESULTS

Multivariate logistic regression revealed that significant risk factors (P<0.05) for postoperative neurological deterioration were intervertebral disk herniation [odds ratio (OR): 4.59, 95% confidence interval (CI): 1.32-16.0) and degenerative spondylolisthesis (OR: 11.1, 95% CI: 2.15-57.5). Ossification of the ligamentum flavum (OR: 4.12, 95% CI: 1.92-8.86), anterior spinal fusion (OR: 41.2, 95% CI: 4.70-361), and circumferential decompression via a posterior approach (OR: 30.5, 95% CI: 2.27-410) were risk factors for dural tear. In thoracic myelopathy patients surgically treated, 37.0% also underwent degenerative cervical and/or lumbar surgery.

CONCLUSIONS

Pathologies involving anterior decompression and instability increased the risk of postoperative neurological deterioration. The risk of dural tear was increased when dura mater adhesions were likely to be directly operated upon. It should be recognized that a relatively high proportion (37.0%) of surgically treated thoracic myelopathy patients also underwent cervical and/or lumbar surgery.

Delayed cerebrospinal fluid (CSF) leak following anterior cervical discectomy and fusion surgery

Background

An uncommon complication of anterior cervical discectomy and fusion (ACDF) is dura tear, which may be further complicated by cerebral spinal fluid (CSF) leak. Dural tears with CSF leak can lead to catastrophic neurologic outcomes and should be recognized early.

Case Description

This case report describes a 43-year-old female patient with history of Ehlers-Danlos syndrome who presented 1-year post-ACDF with positional headaches and lightheadedness. Imaging revealed ACDF plate subsidence and CSF leak with inferior displacement of the cerebellar tonsils.

Outcome

The patient underwent a revision procedure with removal of index screws and CSF repair using epidural blood patch, fat graft, and Tisseel. The original bicortical screws were replaced with shorter larger diameter unicortical screws. Post-operative imaging at 2 and 6 weeks confirmed resolution of CSF leak.

Conclusions

Healthcare professionals and patients undergoing spinal surgery should be aware of late presentation CSF leaks which can represent gradual decline in neurological function. Surgical candidates at risk to develop CSF leaks should be counseled about possible complications in preoperative planning.

Local contamination is a major cause of early deep wound infections following open posterior lumbosacral fusions

PURPOSE

Postoperative surgical site infection in patients treated with lumbosacral fusion has usually been thought to be caused by perioperative contamination. With the proximity of these incisions to the perineum, this study sought to determine if contamination by gastrointestinal and/or urogenital flora should be considered as a major cause of this complication.

METHODS

We conducted a retrospective review of adults treated with open posterior lumbosacral fusions between 2014 and 2021 to identify common factors in deep postoperative infection and the nature of the infecting organisms. Cases of tumor, primary infection and minimally invasive surgery were excluded.

RESULTS

489 eligible patients were identified, 20 of which required debridement deep to the fascia (4.1%). Mean age, operative time, estimated blood loss and levels fused were similar between both groups. The infected group had a significantly higher BMI. The mean time from primary procedure to debridement was 40.8 days. Four patients showed no growth, 3 showed Staphylococcus sp. infection (Perioperative Inside-Out) requiring debridement at 63.5 days. Thirteen showed infection with intestinal or urogenital pathogens (Postoperative Outside-In) requiring debridement at 20.0 days. Postoperative Outside-In infections led to debridement 80.3 days earlier than Perioperative Inside-Out infections (p = 0.007).

CONCLUSIONS

65% of deep infections in patients undergoing open lumbosacral fusion were due to early contamination by pathogens associated with the gastrointestinal and/or urogenital tracts. These required earlier debridement than Staphylococcus sp.

INFECTIONS

There should be renewed focus on keeping these pathogens away from the incision during the early stages of wound healing.

A Case of Remote Cerebellar Hemorrhage in Spinal Surgery without Dural Injury: Case Report

Introduction

Remote cerebellar hemorrhage (RCH) has been reported as a serious complication of spine surgery and is considered to be caused by dural injury. However, we have experienced a case in which intracranial hemorrhage occurred immediately after lumbar spine surgery without dural tear. There were no reports of RCH in spinal surgery without dural injury as far as we could find.

Case Report

We described a rare presentation of an 80-year-old male who suffered a loss of consciousness after lumbar surgery. He was diagnosed with impaired consciousness due to chronic and acute intracranial hemorrhage. He went through two hematoma removal surgeries and his consciousness improved.

Conclusion

RCH can occur in spinal surgery in patients with predicted cerebrovascular fragility, even in the absence of dural injury. Pre-operative imaging evaluation could be useful in assessing cerebrovascular fragility.

Clinical Consequences of Incidental Durotomy during Full-Endoscopic Lumbar Decompression Surgery in Relation to Intraoperative Epidural Pressure Measurements

Background: Seizures, neurological deficits, bradycardia, and, in the worst cases, cardiac arrest may occur following incidental durotomy during routine lumbar endoscopy. Therefore, we set out to measure the intraoperative epidural pressure during lumbar endoscopic decompression surgery. Methods: We conducted a retrospective observational cohort study to obtain intraoperative epidural measurements with an epidural catheter-pressure transducer assembly through the spinal endoscope on 15 patients who underwent lumbar endoscopic decompression of symptomatic lumbar herniated discs and spinal stenosis. The endoscopic interlaminar technique was employed. Results: There were six (40.0%) female and nine (60.0%) male patients aged 49.0667 ± 11.31034, ranging from 36 to 72 years, with an average follow-up of 35.15 ± 12.48 months. Three of the fifteen patients had seizures with durotomy and one of these three had intracranial air on their postoperative brain CT. Another patient developed spinal headaches and diplopia on postoperative day one when her deteriorating neurological function was investigated with a brain computed tomography (CT) scan, showing an intraventricular hemorrhage consistent with a Fisher Grade IV subarachnoid hemorrhage. A CT angiogram did not show any abnormalities. Pressure recordings in the epidural space in nine patients ranged from 20 to 29 mm Hg with a mean of 24.33 mm Hg. Conclusion: Most incidental durotomies encountered during lumbar interlaminar endoscopy can be managed without formal repair and supportive care measures. The intradural spread of irrigation fluid and intraoperatively used drugs and air entrapment through an unrecognized durotomy should be suspected if patients deteriorate in the recovery room. Ascending paralysis may cause nausea, vomiting, upper and lower motor neuron symptoms, cranial nerve palsies, hypotension, bradycardia, and respiratory and cardiac arrest. The recovery team should be prepared to manage these complications.

Risk Factors and Outcomes of Central Nervous System Infection After Spinal Surgery: A Retrospective Cohort Study

OBJECTIVE

To investigate the risk factor associated with central nervous system infection, a rare and dire complication after spinal surgery.

METHODS

Univariate and multivariate logistic regression analyses were performed to screen for the independent risk factors. According to the different administration methods of antibiotics, patients were divided into intravenous and intrathecal groups. The differences in time needed for body temperature, white blood cells (WBC), and C-reactive protein (CRP) to return to normal and the time of antibiotic application were compared between the 2 groups. In addition, the differences in WBC, neutrophil ratio, CRP, procalcitonin in blood, and WBC in cerebrospinal fluid were compared before intrathecal injection, after the first one, and the last one. The incidence of complications in the 2 groups was observed.

RESULTS

Dural tears, laminectomy, and operation time >3 hours were identified as independent risk factors. The time needed for body temperature, WBC, and CRP to return to normal and the antibiotic application time were significantly different between the 2 groups (all P < 0.05). Before and after the first intrathecal injection and after the last intrathecal injection, the differences in WBCs, neutrophil ratios, CRP, procalcitonin in blood, and cerebrospinal fluid-WBC were statistically significant in overall and pairwise comparisons (P < 0.05). Complications occurred in 2 and 14 cases, respectively.

CONCLUSIONS

The independent risk factors for central nervous system infection after spinal surgery were a dural tear, laminectomy, and operation time > 3 hours. Combined intravenous and intrathecal injections of antibiotics led to a better effect than intravenous injection alone; however, this approach was associated with more complications.

Incidental dural tears associated with worse clinical outcomes in patients operated for lumbar spinal stenosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Incidental dural (ID) tear is a common complication of spine surgery with a prevalence of 4-10%. The association between ID and clinical outcome is uncertain. Former studies found only minor differences in Oswestry Disability Index (ODI). We aimed to examine the association of ID with treatment failure after surgery for lumbar spinal stenosis (LSS).

METHODS

Between 2007 and 2017, 11,873 LSS patients reported to the national Norwegian spine registry (NORspine), and 8,919 (75.1%) completed the 12-month follow-up. We used multivariate logistic regression to study the association between ID and failure after surgery, defined as no effect or any degrees of worsening; we also compared mean ODI between those who suffered a perioperative ID and those who did not.

RESULTS

The mean (95% CI) age was 66.6 (66.4-66.9) years, and 52% were females. The mean (95% CI) preoperative ODI score (95% CI) was 39.8 (39.4-40.1); all patients were operated on with decompression, and 1125 (12.6%) had an additional fusion procedure. The prevalence of ID was 4.9% (439/8919), and the prevalence of failure was 20.6% (1829/8919). Unadjusted odds ratio (OR) (95% CI) for failure for ID was 1.51 (1.22-1.88); p < 0.001, adjusted OR (95% CI) was 1.44 (1.11-1.86); p = 0.002. Mean postoperative ODI 12 months after surgery was 27.9 for ID vs. 23.6 for no ID.

CONCLUSION

We demonstrated a significant association between ID and increased odds for patient-reported failure 12 months after surgery. However, the magnitude of the detrimental effect of ID on the clinical outcome was small.

Complications and Risk Factors in En Bloc Resection of Spinal Tumors: A Retrospective Analysis on 298 Patients Treated in a Single Institution

En bloc resection consists in the surgical removal of a vertebral tumor in a single piece with a sufficient margin, to improve survival and reduce recurrence rate. This procedure is technically demanding and correlates with a high complication rate. The purpose of this study is to investigate the risk factors for complications in en bloc resection and evaluate if benefits overcome the risks in term of overall survival. We retrospectively analyzed prospectively collected data of patients treated with en bloc resection between 1980 and 2021. Complications were classified according to SAVES-V2. Overall Survival was estimated using Kaplan-Meier method. A total of 149 patients out of 298 (50%) suffered from at least one complication. Moreover, 220 adverse events were collected (67 intraoperative, 82 early post-operative, 71 late post-operative), 54% of these were classified as grade 3 (in a severity scale from 1 to 6). Ten years overall survival was 67% (95% CI 59-74). The occurrence of relapses was associated to an increased risk of mortality with OR 3.4 (95% CI 2.1-5.5), while complications did not affect the overall survival. Despite a high complication rate, en bloc resection allows for a better control of disease and should be performed in selected patients by specialized surgeons.

Cerebrospinal fluid leaks following intradural spinal surgery—Risk factors and clinical management

Background

Cerebrospinal fluid leakage (CSFL) following spinal durotomy can lead to severe sequelae. However, while several studies have investigated accidental spinal durotomies, the risk factors and influence of clinical management in planned durotomies remain unclear.

Methods

We performed a retrospective analysis of all patients who underwent planned intradural spinal surgery at our institution between 2010 and 2020. Depending on the occurrence of a CSFL, patients were dichotomized and compared with respect to patient and case-related variables as well as dural closure technique, epidural drainage placement, and timing of mobilization.

Results

A total of 351 patients were included. CSFL occurred in 4.8% of all cases. Surgical indication, tumor histology, location within the spine, previous intradural surgery, and medical comorbidities were not associated with an increased risk of CSFL development (all p > 0.1). Age [odds ratio (OR), 0.335; 95% confidence interval (CI), 0.105–1.066] and gender (OR, 0.350; 95% CI, 0.110–1.115) were not independently associated with CSFL development. There was no significant association between CSFL development and the dural closure technique (p = 0.251), timing of mobilization (p = 0.332), or placement of an epidural drainage (p = 0.321).

Conclusion

CSFL following planned durotomy pose a relevant and quantifiable complication risk of surgery that should be factored in during preoperative patient counseling. Our data could not demonstrate superiority of any particular dural closure technique but support the safety of both early mobilization within 24 h postoperatively and epidural drainage with reduced or no force of suction.

Incidence and risk factors for incidental durotomy in spine surgery for lumbar stenosis and herniated disc

PURPOSE

Incidental durotomy (ID) is one of the most common complications in degenerative surgery. Due to the negative consequences of ID, knowledge about incidence and risk factors is warranted.

METHODS

A total of 1,139 surgical procedures for lumbar spinal stenosis (LS) and lumbar herniated disc (LDH) were included from the spine surgery database: DaneSpine. Uni- and multivariate analyses were performed for the assessment of possible risk factors.

RESULTS

ID occurred in 10.4% of the surgical procedures. A multivariate regression analysis revealed an increased relative risk of ID by 2% per year of age, 58% by revision surgery, and 55% by decompression on multiple levels.

CONCLUSION

In our single-centre cohort study, one in ten patients experiences an ID. Increasing age, revision surgery and decompression of multiple levels are risk factors of ID in degenerative surgery of the lumbar spine.

Repair of Incidental Durotomy Using Sutureless Nonpenetrating Clips via Biportal Endoscopic Surgery

STUDY DESIGN

Technical report.

OBJECTIVES

Dural tear is one of the most common complications of endoscopic spine surgery. Although endoscopic dural repair of the durotomy area may be difficult, we successfully repaired the dural tear area using nonpenetrating clips during biportal endoscopic surgery. We introduce the surgical technique of dural repair using nonpenetrating titanium clips in biportal endoscopic spine surgery and report its clinical outcome.

METHODS

We retrospectively reviewed and analyzed 5 patients who were treated via primary dural repair using nonpenetrating titanium clips during biportal endoscopic lumbar surgery. The 2 methods of dural clipping and repair include 2 or 3 portals. We analyzed radiological parameters such as cerebrospinal fluid collection as well as clinical parameters, including postoperative clinical outcomes.

RESULTS

Five patients underwent biportal endoscopic dural repair using nonpenetrating clips. Incidental durotomy was successfully repaired using nonpenetrating titanium clips in all 5 patients. No cerebrospinal fluid collection was detected in the postoperative magnetic resonance images. Clinically, preoperative symptoms improved significantly after surgery (P < .05).

CONCLUSIONS

We repaired the dural tear area completely using nonpenetrating titanium vascular anastomosis clips in biportal endoscopic lumbar surgery. Dural repair via clipping method may be an effective alternative for incidental durotomy.

Clinical and Patient-reported Outcomes After Posterior Versus Transforaminal Lumbar Interbody Fusion-A Propensity Score-matched Cohort Study on 422 Patients with 2-year Follow-up

STUDY DESIGN

This was a dual-center study over an eight-year period on patients undergoing single level fusion surgery with either posterior- (PLIF) or transforaminal lumbar interbody fusion (TLIF). We analyzed prospectively collected pre- and postoperative data from the national Danish surgical spine database (DaneSpine).

OBJECTIVE

The aim of this study was to compare clinical and patient-reported outcome (PRO) 2 years after TLIF or PLIF in patients with symptomatic lumbar mechanical disc degeneration.

SUMMARY OF BACKGROUND DATA

PLIF and TLIF are well-described techniques for treating lumbar mechanical disc degeneration but whether the theoretical differences between the two techniques translate to different clinical outcomes is unknown.

METHODS

The primary outcome was Oswestry Disability Index (ODI) score at 2-year follow-up. Secondary outcome measures were scores on the European Quality of Life-5 Dimensions (EQ-5D) and visual analog scale (VAS) and the rate of intraoperative complications. To minimize baseline differences between the groups, propensity-score matching was employed in a 1:1 fashion, balancing the groups on preoperative factors including age, sex, back and leg pain, ODI, EQ-5D, and previous spine surgery.

RESULT

The matched cohort included 211 patients in each cohort. There was no significant difference between the groups in the mean score on the ODI at two years (PLIF: 33 ± 20 vs. TLIF: 35 ± 20, P = 0.328). We found no statistically significant differences in EQ-5D score (0.54 ± 0.35 vs. 0.51 ± 0.34, P = 0.327), VAS score for back pain (47 ± 32 vs. 48 ± 29, P = 0.570) or leg pain (42 ± 33 vs. 41 ± 32, P = 0.936) between the PLIF and TLIF groups, respectively, at 2-year follow-up. Dural tears occurred in 9.5% in the PLIF group and 1.9% in the TLIF group (P = 0.002) corresponding to a relative risk of 5.0 (95% CI 1.7-14.4).

CONCLUSION

We found no significant difference in PRO at 2-year follow-up between PLIF and TLIF for the treatment of lumbar disc degeneration. PLIF is associated with a five times higher risk of dural tears.Level of Evidence: 3.

Open epidural blood patch to augment durotomy repair in lumbar spine surgery: surgical technique and cohort study

BACKGROUND CONTEXT

Incidental durotomy during elective spine surgery is relatively common. While usually benign and self-limited, it can be associated with morbidity, increased cost, and medicolegal ramifications. Dural repair typically involves performing a primary closure using a suture or dural staple; repairs are then frequently augmented with a sealant, patch, or fat/fascial graft. Although primary repair of an incidental durotomy is standard practice, the ideal secondary sealant or augment choice remains unclear. A wide variety of commercially available dural sealant options exist, and while none have demonstrated consistent superiority, all are associated with single-use costs in the hundreds to thousands of dollars and have concerns regarding swelling, local inflammation, or short-lived dural adherence.

PURPOSE

The goal of this study is to compare the results of dural repair augmentation using an open intraoperative epidural blood patch to a hydrogel technique.

STUDY DESIGN/SETTING

Retrospective comparative cohort study at an academic referral center PATIENT SAMPLE: Adult patients undergoing lumbar spine surgery from March 2017 to January 2021 who sustained an incidental durotomy. Patients undergoing surgery for infection were excluded.

OUTCOME MEASURES

The primary outcome was failure of the repair as determined by a return to the operating room for re-exploration of a persistent cerebrospinal fluid (CSF) leak within 30 days of the index procedure. A secondary outcome was the incidence of a postoperative positional headache, and if present, the method used to obtain resolution. The primary predictor was use of a suture and hydrogel technique ("hydrogel" group), or the use of an epidural blood patch ("EBP" group).

METHODS

The method for applying an open epidural blood patch is presented in detail and involves primarily repairing the durotomy followed by allowing whole blood to pool and clot in the operative field until the durotomy is completely covered. This was compared with a group of patients undergoing secondary augmentation with commercially available hydrogel. In both groups, mechanical resistance to CSF leakage was confirmed with direct visualization and a Valsalva maneuver, respectively. Patients were instructed to remain flat until the morning after surgery. Chart review was used for data abstraction on preoperative, demographic, perioperative, and postoperative clinical factors. To compare between the hydrogel and EBP group, Wilcoxon rank-sum testing was used to test for non-parametric comparisons of means, and chi-square testing between binomial data.

RESULTS

Of 732 patients during the study period, forty-eight patients met study criteria. Twenty-five patients were in the hydrogel group and 23 in the EBP group. Mean age was 69.3 years (standard error 1.3 years). Patients were predominantly female (n = 31, 64.6%) with a mean BMI of 29.5 (SE 0.8), with no significant baseline differences between the hydrogel and EBP groups. Two patients in the hydrogel group (8.0%) and two in the EBP group (8.7%) had mild positional headaches postoperatively that resolved without intervention within 24 hours. One (4.3%) patient in the EBP group had positional headaches following an initial headache-free period; this patient was returned to the operating room and no evidence of a persistent CSF leak was found despite meticulous exploration.

CONCLUSIONS

An open, intraoperatively placed epidural blood patch may be an efficacious and cost-effective way to manage an incidental durotomy. This method merits further study as an allergy-free, no swell, cost-neutral method of dural repair augmentation.

Is there a variance in complication types associated with ALIF approaches? A systematic review

Purpose

Anterior lumbar interbody fusion (ALIF) is a well-established alternative to posterior-based interbody fusion techniques, with approach variations, such as retroperitoneal, transperitoneal, open, and laparoscopic well described. Variable rates of complications for each approach have been enumerated in the literature. The purpose of this study was to elucidate the comparative rates of complications across approach type.

Methods

A systematic review of search databases PubMed, Google Scholar, and OVID Medline was made to identify studies related to complication-associated ALIF. PRISMA guidelines were utilised for this review. Meta-analysis was used to compare intraoperative and postoperative complications with ALIF for each approach.

Results

A total of 4575 studies were identified, with 5728 patients across 31 studies included for review following application of inclusion and exclusion criteria. Meta-analysis demonstrated the transperitoneal approach resulted in higher rates of retrograde ejaculation (RE) (p < 0.001; CI = 0.05–0.21) and overall rates of complications (p = 0.05; CI = 0.00–0.23). Rates of RE were higher at the L5/S1 intervertebral level. Rates of vessel injury were not significantly higher in either approach method (p = 0.89; CI =  − 0.04–0.07). Rates of visceral injury did not appear to be related to approach method. Laparoscopic approaches resulted in shorter inpatient stays (p = 0.01).

Conclusion

Despite the transperitoneal approach being comparatively underpowered, its use appears to result in a significantly higher rate of intraoperative and postoperative complications, although confounders including use of bone morphogenetic protein (BMP) and spinal level should be considered. Laparoscopic approaches resulted in shorter hospital stays; however, its steep learning curve and longer operative time have deterred surgeons from its widespread adaptation.

Risk Factors for Accidental Dural Tears in Spinal Surgery

BACKGROUND

Accidental dural tears (DTs) are familiar complications of spinal surgery. Their reported incidence varies widely, and several risk factors have been proposed in the literature. The aim of this study was to conduct a systematic review and meta-analysis to determine the rate of DTs and assess their associated risk factors.

METHODS

A systematic literature search was conducted using specific MeSH and Text terms. Only articles with prospective data reporting the incidence and risk factors were selected and reviewed based on specific inclusion and exclusion criteria.

RESULTS

Twenty-three studies were included. The reported incidence rate ranged from 0.4% to 15.8%, giving an overall pooled incidence rate of 5.8% (95% confidence interval [CI] 4.4-7.3). The incidence rate varied in relation to the part of the spine and the type of surgery. Three factors were associated with a high rate of DTs: age (overall mean difference of 3.04, 95% CI 2.49-3.60), revision surgery (overall odds ratio of 2.28, 95% CI 1.84-2.83), and lumbar stenosis (overall odds ratio of 2.03, 95% CI 1.50-2.75). Diabetes was weakly associated with DTs, with an odds ratio of 1.40 (95% CI 1.01-1.93). The overall effects of sex and obesity were not statistically significant.

CONCLUSION

Advancing age, revision surgery, and lumbar stenosis were significantly associated with increased risk of DTs. These factors should be taken into consideration during the consenting process for spinal surgery.

CLINICAL RELEVANCE

Risk of dural tear during spine surgery.

Dural Tears During Lumbar Spinal Endoscopy: Surgeon Skill, Training, Incidence, Risk Factors, and Management

BACKGROUND

Incidental dural tears during lumbar endoscopy can be challenging to manage. There is limited literature on their appropriate management, risk factors, and the clinical consequences of this typically uncommon complication.

MATERIALS AND METHODS

To improve the statistical power of studying durotomy with lumbar endoscopy, we performed a retrospective survey study among endoscopic spine surgeons by email and chat groups on social media networks, including WhatsApp and WeChat. Descriptive and correlative statistics were done on the surgeons' recorded responses to multiple-choice questions. Surgeons were asked about their clinical experience with spinal endoscopy, training background, the types of lumbar endoscopic decompression they perform by approach, the decompression instruments they use, and incidental durotomy incidence with routine lumbar endoscopy.

RESULTS

There were 689 dural tears in 64 470 lumbar endoscopies, resulting in an incidental durotomy incidence of 1.07%. Seventy percent of the durotomies were reported by 20.4% of the surgeons. Eliminating these 19 outlier surgeons yielded an adjusted durotomy rate of 0.32. Endoscopic stenosis decompression (54.8%; P < .0001), rather than endoscopic discectomy (44.1%; 41/93), was significantly more associated with durotomy. Medium-sized dural tears (1-10 mm) were the most common (52.2%; 48/93). Small pinhole durotomies (less than 1 mm) were the second most common type (46.7%; 43/93). Rootlet herniations were seen by 46.2% (43/93) of responding surgeons. The posterior dural sac injury during the interlaminar approach (57%; 53/93) occurred more frequently than traversing nerve-root injuries (31.2%) or anterior dural sac (23.7%; 22/93). Exiting nerve-root injuries (10.8%;10/93) were less common. Over half of surgeons did not attempt any repair or closure (52.2%; 47/90). Forty percent (36/90) used sealants. Only 7.8% (7/90) of surgeons attempted an endoscopic repair or sutures (11.1%; 10/90). DuralSeal was the most commonly used brand of commercially available sealant used (42.7%; 35/82). However, other sealants such as Tisseal (15.9%; 13/82), Evicel (2.4%2/82), and additional no-brand sealants (38; 32/82) were also used. Nearly half of the patients (48.3%; 43/89) were treated with 24-48 hours of bed rest. The majority of participating surgeons (64%; 57/89) reported that the long-term outcome was unaffected. Only 18% of surgeons reported having seen the development of a postoperative cerebrospinal fluid (CSF)-fistula (18%;16/89). However, the absolute incidence of CSF fistula was only 0.025% (16/64 470). Severe radiculopathy with dysesthesia; sensory loss; and motor weakness in association with an incidental durotomy were reported by 12.4% (11/89), 3.4% (3/89), and 2.2% (2/89) of surgeons, respectively.

CONCLUSIONS

The incidence of dural tears with lumbar endoscopy is about 1%. The incidence of durotomy is higher with the use of power drills and the interlaminar approach. Stenosis decompression that typically requires the more aggressive use of these power instruments has a slightly higher incidence of dural tears than does endoscopic decompression for a herniated disc. Most dural tears are small and can be successfully managed with mechanical compression with Gelfoam and sealants. Two-thirds of patients with incidental dural tears had an entirely uneventful postoperative course. The remaining one-third of patients may develop a persistent CSF leak, radiculopathy with dysesthesia, sensory loss, or motor function loss. Patients should be educated preoperatively and reassured.

LEVEL OF EVIDENCE

3.

Clinical Outcome of Spine Surgery Complicated by Accidental Dural Tears: Meta-Analysis of the Literature

STUDY DESIGN

Systemic review and meta-analysis.

OBJECTIVES

Several studies have reported the impact of accidental dural tears (DT) on the outcome of spinal surgery, some with conflicting results. Therefore, the aim of this study was to carry out a systemic review and meta-analysis of the literature to establish the overall clinical outcome of spinal surgery following accidental DT.

METHOD

A systemic literature search was carried out. Postoperative improvement in Oswestry Disability Index (ODI), Short-Form 36 survey (SF36), leg pain visual analogue scale (VAS), and back pain VAS were compared between patients with and without DT at different time intervals.

RESULTS

Eleven studies were included in this meta-analysis. There was a slightly better improvement in ODI and leg VAS score (standardized mean difference of -0.06, 95% confidence interval [CI] -0.12 to -0.01, and -0.06, 95% CI -0.09 to -0.02, respectively) in patients without DT at 12 months postsurgery, but this effect was not demonstrated at any other time intervals up to 4 years. There were no differences in the overall SF36 (function) score at any time interval or back pain VAS at 12 months.

CONCLUSION

Based on this study, accidental DT did not have an overall significant adverse impact on the short-term clinical outcome of spinal surgery. More studies are needed to address the long-term impact and other outcome measures including other immediate complications of DT.

Incidental Durotomy in Lumbar Spine Surgery; Risk Factors, Complications, and Perioperative Management

Incidental durotomy (ID) can occur in up to 14% of all lumbar spine surgeries. The risk of this complication is markedly higher among elderly patients with advanced spinal pathology. In addition, revision cases and other more invasive procedures increase the risk of ID. When unrepaired, IDs can increase the risk of developing meningitis and can lead to the formation of cerebrospinal fluid fistulas and pseudomeningoceles. Intraoperative recognition and repair are essential to ID management, although repair techniques vary considerably. Although primary suture repair is considered the "benchmark," indirect repair alone has shown comparable outcomes. Given the concern for infection after ID, many have indicated for prolonged prophylactic antibiotic regimens. However, there is little clinical evidence that this is necessary after adequate repair. The addition of subfascial drains have been shown to promote wound healing and early ambulation, whereas no consensus on duration of indwelling drains exists and such management is largely case dependent. Early ambulation after surgery has not shown to be associated with increased risk of further ID complications and decreases rehabilitation time, length of stay, and risk of venous thromboembolism. However, there remains a role for conservation mobilization protocols in more severe cases where notable symptoms are observed.

Incidental Durotomy Is Associated With Increased Risk of Delirium in Patients Aged 65 and Older

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To evaluate the impact of incidental durotomy during spine surgery on the development of delirium in patients aged 65 and older.

SUMMARY OF BACKGROUND DATA

Delirium after spine surgery has been shown to increase the risk of adverse events, including morbidity and readmissions. Durotomy has previously been postulated to influence the risk of delirium, but this has not been explored in patients 65 and older, the demographic at greatest risk of developing delirium.

METHODS

We obtained clinical data on 766 patients, including 182 with incidental durotomy, from the Partners healthcare registry (2012-2019). Patients had their medical records abstracted and age, biologic sex, body mass index, smoking status, preoperative diagnosis, use of a fusion-based procedure, and number of comorbidities were recorded. Our primary outcome was the development of delirium. Our primary predictor was incidental durotomy. We used logistic regression techniques to adjust for sociodemographic and clinical confounders. We performed propensity score matching as a sensitivity test. We hypothesized that elderly patients would be at increased risk of delirium following durotomy.

RESULTS

Delirium was identified in 142 patients (19%). Among patients with an incidental durotomy, 26% were diagnosed with delirium. The incidence of delirium was 16% in the control group. Following adjusted analysis, the likelihood of delirium was significantly greater in patients with a durotomy (odds ratio [OR] 1.91; 95% confidence interval [CI] 1.27, 2.88). After propensity score matching, durotomy remained significantly associated with delirium in multivariable adjusted analyses (OR 1.90; 95% CI 1.07, 3.39).

CONCLUSION

This investigation is among the first to specifically evaluate an association between durotomy and delirium in elderly patients undergoing spine surgery. The increased association between durotomy and delirium in this cohort should prompt increased surveillance and interventions designed to minimize the potential for cognitive deterioration or impairment during postoperative management of a durotomy.

LEVEL OF EVIDENCE

3.

The True Effect of a Lumbar Dural Tear on Complications and Cost

STUDY DESIGN

Retrospective database analysis.

OBJECTIVE

The aim of this study was to match risk factors for complications in patients who did and did not sustain a dural tear while undergoing posterior lumbar spine surgery and compare local and systemic complications.

SUMMARY OF BACKGROUND DATA

Current data do not adequately define whether the event of sustaining an isolated dural tear increases the risk for postoperative complications while controlling for other confounding risk factors.

METHODS

The PearlDiver Database was queried for patients who underwent posterior lumbar spine decompression and/or fusion for degenerative pathology. Patients with and without dural tears were 1:2 matched based on demographic variables and comorbidities. Complications, cost, length of stay (LOS), and readmission rates were analyzed.

RESULTS

The 1:2 matched cohort included 9038 patients with a dural tear and 17,340 patients without a dural tear. All complications assessed were significantly higher in the dural tear group (P < 0.03). Venothromboembolic (VTE) events occurred in 1.3% of patients with a dural tear and 0.9% of patients without a dural tear (odds ratio [OR] 1.46, P < 0.0001). Meningitis occurred in 25 patients (0.3%) with a dural tear and eight patients (<0.1%) without a dural tear (OR 6.0, P < 0.0001). Patients with a dural tear had 120% higher medical costs, 200% greater LOS, and were two times more likely to be readmitted (P < 0.0001).

CONCLUSION

Sustaining a dural tear while undergoing posterior lumbar spinal decompression and/or fusion for degenerative pathology significantly increased the risk of complications and increased length of stay, risk of readmission, and overall 90-day hospital cost. Dural tears specifically increased the risk of a VTE complication by 1.46 times and meningitis by six times; these are important complications to have a high degree of suspicion for in the setting of durotomy, as they can lead to significant morbidity for the patient.

LEVEL OF EVIDENCE

3.

Incidence and Risk Factors for Postoperative Delirium in Patients Undergoing Spine Surgery: A Systematic Review and Meta-Analysis

Background

The present study aims to investigate the incidence and risk factors associated with postoperative delirium in patients undergoing spine surgery.

Methods

PubMed, EMBASE, Cochrane Library, and Science Citation Index were searched up to August 2019 for studies examining postoperative delirium following spine surgery. Incidence and risk factors associated with delirium were extracted. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for outcomes. The Newcastle-Ottawa Scale (NOS) was used for the study quality evaluation.

Results

The final analysis includes a total of 40 studies. The pooled analysis reveals that incidence of delirium is 8%, and there are significant differences for developing delirium in age (OR 1.07; 95% CI 1.04-1.09), age more than 65 (OR 4.77; 95% CI 4.37-5.16), age more than 70 (OR 15.87; 95% CI 6.03-41.73), and age more than 80 (OR 1.91; 95% CI 1.78-2.03) years, male (OR 0.81; 95% CI 0.76-0.86), a history of alcohol abuse (OR 2.11; 95% CI 1.67-2.56), anxiety (OR 1.74; 95% CI 1.04-2.44), congestive heart failure (OR 1.4; 95% CI 1.21-1.6), depression (OR 2.5; 95% CI 1.52-3.49), hypertension (OR 1.12; 95% CI 1.04-1.2), kidney disease (OR 1.41; 95% CI 1.16-1.66), neurological disorder (OR 4.66; 95% CI 4.22-5.11), opioid use (OR 1.86; 95% CI 1.18-2.54), psychoses (OR 2.77; 95% CI 2.29-3.25), pulmonary disease (OR 1.81; 95% CI 1.27-2.35), higher mini-mental state examination (OR 0.7; 95% CI 0.5-0.89), preoperative pain (OR 1.88; 95% CI 1.11-2.64), and postoperative urinary tract infection (OR 5.68; 95% CI 2.41-13.39).

Conclusions

A comprehensive understanding of incidence and risk factors of delirium can improve prevention, diagnosis, and management. Risk of postoperative delirium can be reduced based upon identifiable risk factors.

Invasiveness has no influence on the rate of incidental durotomies in surgery for multisegmental lumbar spinal canal stenosis (≥ 3 levels) with and without fusion. Analysis from the German Spine Registry data (DWG-Register)

BACKGROUND

Nowadays, perioperative complications as dural tear (DT) with subsequent neurological deficits are documented in independent registers. However, the relationship of these complications with the grade of invasiveness (≥3 levels) is still unclear. We attempted to evaluate perioperative complications, particularly DT with subsequent neurological deficits, between patients undergoing laminotomy and decompression and decompression and fusion in ≥3 levels.

METHODS

Retrospective analysis of the data pool of the DWG register based on cases described by 10 clinics between January 2012 and December 2016 was performed. Surgically treated LSS in ≥3 segments were divided into decompression with or without instrumentation and fusion. Cases with intraoperative DT in both subgroups were analysed for risk factor occurrence. The Surgical Invasive Index (SII) was used.

RESULTS

DT occurred in 102/941 (10.8%) patients. Difference in DT between groups was non- significant. The likelihood of DT increased by 2.12-fold with previous spinal surgery at the same level and by 1.9-fold for BMI 30-34 and >35 in comparison with BMI 26-29, respectively. Postoperative deep wound infection was increased by 2.39-fold after DT than without. Significance in outcomes between patients with/without DT was not found. The invasiveness index explained 48% of the variation in blood loss and 51% of the variation in surgery duration.

CONCLUSIONS

The rate of incidental DT during decompression for LSS with and without fusion in ≥3 levels was associated with BMI and previous surgery at the same spinal level. Invasivness (SII) is valid rather for variables proper to surgery such as bledding and Op-time but no with incidence for DT and subsequent CSF-leackage.

Prognostic impact of intra- and postoperative management of dural tear on postoperative complications in primary degenerative lumbar diseases

Aims

The aim of this study was to explore risk factors for complications associated with dural tear (DT), including the types of DT, and the intra- and postoperative management of DT.

Patients and Methods

Between 2012 and 2017, 12 171 patients with degenerative lumbar diseases underwent primary lumbar spine surgery. We investigated five categories of potential predictors: patient factors (sex, age, body mass index, and primary disease), surgical factors (surgical procedures, operative time, and estimated blood loss), types of DT (inaccessible for suturing/clipping and the presence of cauda equina/nerve root herniation), repair techniques (suturing, clipping, fibrin glue, polyethylene glycol (PEG) hydrogel, and polyglycolic acid sheet), and postoperative management (drainage duration). Postoperative complications were evaluated in terms of dural leak, prolonged bed rest, headache, nausea/vomiting, delayed wound healing, postoperative neurological deficit, surgical site infection (SSI), and reoperation for DT. We performed multivariable regression analyses to evaluate the predictors of postoperative complications associated with DT.

Results

In total, 429/12 171 patients (3.5%) had a DT. Multivariable analysis revealed that PEG hydrogel significantly reduced the incidence of dural leak and prolonged bed rest, and that patients treated with sealants (fibrin glue and PEG hydrogel) significantly less frequently suffered from headache. A longer drainage duration significantly increased the incidence of headache, nausea/vomiting, and delayed wound healing. Headache and nausea/vomiting were significantly more prevalent in younger female patients. Postoperative neurological deficit and reoperation for DT significantly depended on the presence of cauda equina/nerve root herniation. A longer operative time was the sole independent risk factor for SSI and was also a risk factor for dural leak, prolonged bed rest, and nausea/vomiting.

Conclusion

Sealants, particularly PEG hydrogel, may be useful in reducing symptoms related to cerebrospinal fluid leakage, whereas prolonged drainage may be unnecessary. Younger female patients should be carefully treated when DT occurs. Cite this article: Bone Joint J 2019;101-B:1115–1121.