Justin K. Scheer, Michael J. Harvey, Nader S. Dahdaleh, Zachary A. Smith, Richard G. Fessler
  1. Department of Neurological Surgery, Northwestern University, Feinberg School of Medicine, 676 N. St. Clair Street, Suite 2210, USA
  2. Department of Neurological Surgery, Rush University School of Medicine, Chicago, IL, 60611, USA

Correspondence Address:
Zachary A. Smith
Department of Neurological Surgery, Rush University School of Medicine, Chicago, IL, 60611, USA


Copyright: © 2014 Scheer JK. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

How to cite this article: Scheer JK, Harvey MJ, Dahdaleh NS, Smith ZA, Fessler RG. K-Wire fracture during minimally invasive transforaminal lumbar interbody fusion: Report of six cases and recommendations for avoidance and management. Surg Neurol Int 30-Dec-2014;5:

How to cite this URL: Scheer JK, Harvey MJ, Dahdaleh NS, Smith ZA, Fessler RG. K-Wire fracture during minimally invasive transforaminal lumbar interbody fusion: Report of six cases and recommendations for avoidance and management. Surg Neurol Int 30-Dec-2014;5:. Available from:

Date of Submission

Date of Acceptance

Date of Web Publication


Background:Although rare, minimally invasive spine techniques do have the risk of intraoperative device failure. Kirschner wire (K-wire) fractures during minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) have not been previously reported. This report focuses on the incidence of k-wire fractures following MI-TLIF and describes techniques to help avoid and treat these fractures when they occur.

Methods:Inclusion criteria: (i) patients underwent 1, 2, or 3 level MI-TLIF over a 10-year period and (ii) had a k-wire fracture leading to a retained fragment. Exclusion criteria included: >10° coronal curves, significant sagittal malalignment, infection, and preoperative instrumentation failure.

Results:Of 513 patients undergoing MI-TLIF, 6 (1.2%) sustained k-wire fracture (3 males, 3 females, mean age 43 ± 13 years). Complications included k-wire fracture alone (4 patients), cerebrospinal fluid (CSF) leak (1 patient), and both ileus and revision for hardware removal (1 patient). All six patients went home postoperatively. The mean follow-up duration was 27.7 ± 37.4 months. All retained k-wire fragments were located in the vertebral bodies at the tip of the pedicle screws; none breached the anterior cortex of the vertebral bodies. None of the k-wires migrated at final follow-up 7.8 years (93.7 months) postoperatively. Furthermore, no complications were attributed to retained k-wires.

Conclusions:K-wire fractures during MI-TLIF are rare (incidence of 1.2%) and retained k-wire segments led to no postoperative complications (e.g. no migration).

Keywords: Complications, Kirschner wire, K-wire, minimally invasive, transforaminal lumbar interbody fusion, TLIF


Minimally invasive (MI) spinal surgery has been successfully evolving, and becoming more prevalent over the past decade.[ 5 6 8 ] More MI transforaminal lumbar interbody fusions (MI-TLIFs) are being performed.

This study uniquely evaluated the frequency of Kirschner wire (k-wire) complications occurring during MI-TLIF, while other reports cite K-wire complications leading to anterior cortex breaches, retroperitoneal hematomas, postoperative ileus, instrumentation fracture, and postoperative paraplegia.[ 1 4 7 ]


This is a retrospective review of prospectively collected data for the incidence of k-wire fractures occurring in 513 patients undergoing 1-3 level MI-TLIF for spondylolisthesis at two institutions. Approval from the Institutional Review Board was obtained prior to conducting this study. Patients were identified by querying departmental billing records for Current Procedural Terminology codes for MI-TLIF over a 10-year period from September 2002 to August 2012. Patients with >10° coronal curves, significant sagittal malalignment, infection, and preoperative hardware failure were excluded. Data collected included demographic and preoperative data collected included: Age, sex, and preoperative diagnosis. Operative data collected include: level(s) of operation, operative time, estimated blood loss (EBL), and complications. A routine MI-TLIF technique was utilized in all cases.[ 2 ] A 2.5 cm incision was made 4 cm lateral to midline, and a k-wire was docked to the facet joint of the appropriate level under fluoroscopic guidance. Sequential muscle-splitting tubular dilators (METRx; Medtronic Sofamor Danek, Memphis, Tennessee, USA) were then passed over one another until the required working channel of 24 mm was obtained. Once the cage was placed, autograft supplemented with allograft when necessary and recombinant human bone morphogenetic protein 2 (rhBMP2) were split between the interspace and the interbody cage and then tapped into the center of the disk space. rhBMP was used to enhance the fusion and the authors acknowledge that this is an off-label use of rhBMP. Food and Drug Administration (FDA) approval for rhBMP exists only for anterior lumbar interbody fusion (ALIF) using the LT cage (Medtronic Sofamor Danek).

Instrumentation with pedicle screws was performed through the same incision on the ipsilateral side according to previously published methods.[ 2 ] Specifically regarding k-wires, the use of anteroposterior (AP) fluoroscopy was used to visualize the pedicles and a Jamshidi needle then directed the k-wire into the pedicle with the ‘bull's eye’ technique. After confirmatory AP and lateral fluoroscopy to assess position and trajectory, the wire was advanced to approximately two-thirds of the vertebral body depth. Once the screws were in place the k-wires were removed by backing them out of the cannulated screw. The procedure was then similarly repeated on the contralateral side.


A total of 513 patients were identified over the 10-year period, of which 6 (1.2%) sustained a k-wire fracture [ Table 1 ]. There were three males and three females with an average age of 43 ± 13 years (range 26-61 years). Preoperative diagnoses included spondylosis, spondylolisthesis, spondylolysis, and recurrent disc herniation. The mean operating room (OR) time was 310 ± 157 min (range 158-521 min) and the mean EBL was 496 ± 745cc (range 100-2000 cc). The average length of hospital stay was 4.2 ± 4.0 days (range 1-12 days). Complications included the k-wire fracture alone for four patients. One patient also had a CSF leak and another had an ileus and reoperation for hardware removal. All six patients went home following their surgery. The mean follow-up was 27.7 ± 37.4 months (range 0-93.7 months)

Table 1

Demographics, operating room time, estimated blood loss, and the spinal level of the six patients with retained k-wire fragments


All retained k-wire fragments were located in the vertebral bodies at the tip of the pedicle screw [ Figure 1 ] and none of them breached the anterior cortex of the vertebral body. The locations of the retained k-wire fragments are listed in Table 1 . At final radiographic follow-up, none of the k-wires had migrated, even at 93.7 months (7.8 years) postoperative [ Figure 2 ]. No postoperative complications due to the retained k-wires were reported.

Figure 1

Intraoperative lateral radiograph of a broken k-wire fragment in the L4 vertebral body


Figure 2

Lateral radiographs demonstrating a broken k-wire fragment at 1 day postoperative (left) and at 7 years postoperative (right). Note the k-wire at 93.7 months (7.8 years) postoperative has not migrated



MI-TLIF is a safe and effective procedure for degenerative disorders of the spine. K-wires are an integral part of the operation, but they may break and become lodged in the spine. In this large series of patients undergoing MI-TLIF, although the incidence of k-wire fracture was determined to be 1.2%, there were no postoperative complications or migration.

Ultimately, k-wire fracture occurs when the instrument over-riding it is allowed to deviate from a perfectly parallel trajectory. Lau and colleagues reported one k–wire fracture in the L5 vertebral body out of 127 patients.[ 3 ] Although there is minimal data on k-wire fracture complicating MI-TLIF surgery, it is a well-known complication of various orthopedic procedures.

While k-wire fracture seems to be an inevitable complication of neurologic and orthopedic surgery, it is important to highlight ways that can reduce the chance of k-wire fracture. Do not place any “insertional” instrument at an angle to the k-wire. Mechanistically, repeated kinking and bending of the wire causes it to lose strength, making it weaker and more likely to fracture. It is also recommended to not use a blade to cut the fascia near the k-wire as blades can nick or cut the wire, resulting in a point of weakness and increased probability of wire breakage.

Using mallets, taps, or screw insertion when wire is in place may increase the chances of wire fracture, and it is recommended to avoid this if possible. These techniques can jam a wire in the instrument and cause damage. In addition, it is important not to over-ride the wire or get the instrument within 5-10 mm of the wire's end. Wires tend to break when there is only a small segment exposed distal to the instrument. If a wire becomes bent or damaged, it is best to remove them as early as possible, and discontinue their use. Immediate replacement at the time of hardware compromise can prevent further injury and subsequent fracture of the wire. If one must remove a damaged or bent wire, care must be taken to remove it slowly and with minimal force to prevent possible breaking. It is also helpful to withdraw the over-riding instrument slightly prior to attempting removal of the K-wire.

Currently, we use a technique that places the Jamshidi two-thirds of the way into the vertebral body. This allows the wire to not be advanced any further than the Jamshidi reducing the chances of the Jamshidi bending the wire or breaking it.

In the unfortunate event that a k-wire breaks, the remaining fragments are almost always small (3-6 mm) and universally embedded in bone based on our observational experience. For a broken wire, it is critical to not place a pedicle screw such that it advances the wire out of the bone.

We have presented these six cases to describe a complication that is unique to MI spine surgery and not shared with more traditional, open spine exposures. This is a preventable complication and the current report seeks to both discuss this complication as well as present steps for avoidance. Few reports in spine have discussed this complication, and to our knowledge, this has not been elaborated upon in a larger series.


1. Chung T, Thien C, Wang YY. A rare cause of postoperative paraplegia in minimally invasive spine surgery. Spine. 2014. 39: E228-30

2. Habib A, Smith ZA, Lawton CD, Fessler RG. Minimally invasive transforaminal lumbar interbody fusion: A perspective on current evidence and clinical knowledge. Minim Invasive Surg. 2012. 2012: 657342-

3. Lau D, Khan A, Terman SW, Yee T, La Marca F, Park P. Comparison of perioperative outcomes following open versus minimally invasive transforaminal lumbar interbody fusion in obese patients. Neurosurgical focus. 2013. 35: E10-

4. Mobbs RJ, Raley DA. Complications with K-wire insertion for percutaneous pedicle screws. J Spinal Disord Tech. 2014. 27: 390-4

5. O’Toole JE, Eichholz KM, Fessler RG. Surgical site infection rates after minimally invasive spinal surgery. J Neurosurg Spine. 2009. 11: 471-6

6. Shih P, Wong AP, Smith TR, Lee AI, Fessler RG. Complications of open compared to minimally invasive lumbar spine decompression. J Clin Neurosci. 2011. 18: 1360-4

7. Siddiqui SA, Singh PK, Garg K, Agrawal D, Sharma BS. Intra-operative K-wire breakage during odontoid screw fixation. Neurol India. 2014. 62: 203-4

8. Tafazal SI, Sell PJ. Incidental durotomy in lumbar spine surgery: Incidence and management. Eur Spine J. 2005. 14: 287-90

Leave a Reply

Your email address will not be published. Required fields are marked *