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n tips & techniquesSection Editor: Steven F. Harwin, MD

Preventing Proximal Adjacent Level Kyphosis With Strap StabilizationKhaled M. Zaghloul, MD; Brett J. Matoian, MS; Nicholas B. Denardin, BS; Vikas V. Patel, MD

Proximal junctional kypho-sis (PJK) is a complication

following spine fusion surgery for various indications, in-cluding degeneration, defor-

mity, trauma, and tumor.1 The reported prevalence ranges between 26% and 39% after posterior segmental spinal fu-sion.2,3 Proximal junctional

kyphosis has been commonly defined as a Cobb angle be-tween the upper-instrumented vertebrae and 2 supra-adjacent vertebrae of 10° or greater.3,4 According to the Scoliosis Research Society patient ques-tionnaires evaluating outcome, PJK is a mostly asymptom-atic radiologic finding with the largest burden being self-image.5 However, once PJK presents, if a fracture of the vertebral body, posterior osseo-ligamentous disruption, or instrumentation failure oc-curs, it is considered by defini-tion to be proximal junctional failure (PJF). In contrast to PJK, PJF does increase the risk of neurological injury and most often requires revision surgery.6 Proximal junctional kyphosis increases the risk of fractures, subluxations, defor-mity, and implant prominence; thus, the presence of PJK ap-pears to create a greater po-tential for the development of PJF.7 Radiologic examples of PJK and PJF are shown in Fig-ures 1-2.

Proximal junctional fail-ure has recently been reported in 5.6% of patients undergo-ing surgery for adult spinal deformities.8 This prevalence is reported to be less than that of PJK. However, given the possibility of severe postop-erative complications resulting from progression from PJK to PJF, much emphasis has been placed on identifying surgi-cal techniques that reduce the prevalence of PJK.

Several studies have stressed the preservation of the interspinous and supraspi-nous ligament complexes im-mediately above instrumented levels, and there is evidence to suggest that disruption of this integrity leads to an increased risk of proximal level construct failure.1,9 In addition, several techniques have recently been studied to support the spinal vertebrae proximal to the fu-sion. These include the use of transitional rods, hooks, and hybrid constructs.4 However, to the current authors’ knowl-edge, the use of strap devices

The authors are from the Department of Orthopedics (KMZ, BJM, NBD, VVP), University of Colorado, Anshutz Medical Campus, and the University of Colorado Hospital (VVP), Aurora, Colorado.

The authors have no relevant financial relationships to disclose.Correspondence should be addressed to: Khaled M. Zaghloul, MD, De-

partment of Orthopedics, University of Colorado, Anshutz Medical Campus, 12631 E 17th Ave, Mailstop B202, Aurora, CO 80045 (Khaled.zaghloul@ucdenver.edu).

Received: March 2, 2015; Accepted: June 23, 2015.doi: 10.3928/01477447-20160503-05

Abstract: A substantial proportion of patients develop proxi-mal junctional kyphosis following spinal surgery. To combat this postoperative change, several techniques have focused on maintaining the structural integrity of adjacent spinal lev-els and adapting the proximal end of the fusion construct to accommodate the increased mechanical stressors produced by long spinal fusion. The use of Mersilene tape (Ethicon, Somerville, New Jersey) for spine and orthopedic surgery is well documented, although considerably less is known about its use for preventing proximal junctional kyphosis. This ar-ticle describes a proposed technique using Mersilene tape to provide a check-rein strap stabilization at the proximal end of fusion constructs. Initial data suggest that use of this tech-nique may prevent formation of proximal junctional kypho-sis. [Orthopedics. 2016; 39(4):e794-e799.]

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such as Mersilene tape (Ethi-con, Somerville, New Jersey) as a substrate for check-rein stabilization has not been re-ported. Given its ease of use, relatively low cost, and po-tential benefit, Mersilene tape is an important tool to reduce PJK.

There have been reports of strap devices stabilizing orthopedic repairs (eg, ster-num repair after sternotomy, coracoclavicular fixation after unstable clavicle fracture, and segmental spinal fixation).10-12

Biomechanically, it was prov-en that 1 loop of Mersilene and 2 loops of Ethibond (Ethi-con) had similar loads at fail-ure, although the strength was significantly lower than stain-less steel wire. In addition, in an animal study, Grobler et al showed, when compar-ing the use of Mersilene tape and stainless steel wire, that fixation was adequate in both groups and that the distinct connective tissue membrane surrounding the Mersilene tape was more mature and bet-

ter formed than that surround-ing the stainless steel wire.10,13

Mersilene tape is a non-absorbable, braided, sterile surgical suture composed of polyethylene-terephthalate. It is prepared from fibers of high-molecular-weight, long-chain, linear polyesters having recur-rent aromatic rings as an inte-gral component. Mersilene tape sutures are indicated for use in general soft tissue approxima-tion and/or ligation, including use in cardiovascular, ophthal-mic, and neurological proce-

dures. Mersilene tape elicits a minimal acute inflammatory reaction in tissue, followed by a gradual encapsulation of the suture by fibrous connective tissue. Implantation studies in animals show no meaning-ful decline in polyester suture strength over time, and the polyester fiber suture material is pharmacologically inactive.10

Thus, the use of Mersi-lene tape for adjacent level soft stabilization presents a straightforward addition to a fusion construct that requires

Figure 1: Preoperative lateral (A) and anteroposterior (B) radiographs of a patient with junctional breakdown above fusion L2-S1 with sagittal imbalance. Antero-posterior (C) and lateral (D) radiographs after L2 pedicle subtraction osteotomy and instrumentation T10-L5.

A B C D

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little additional effort to imple-ment. Given the persistence of PJK and PJF in the current patient population, the authors believe that implementation of this technique will reduce the prevalence of PJK and improve surgical outcome.

Materials and MethodsFrom 2011 to 2014, a to-

tal of 23 patients had a poste-rior spinal fusion with use of Mersilene tape adjacent to the most proximal level treated with pedicle screws. The av-erage age of the patients was 63 years (range, 42-83 years). Eleven were men and 12 were women. Average follow-up was 11.9 months (range, 1-29 months). Four patients had primary fusion surgery and the rest underwent revision of posterior fusion for junctional disease or nonunion. In all cases, Mersilene tape was used adjacent to the proximal end of

the construct. Bone cement was used in 3 cases at the top instru-mented vertebrae for screw support and not at the adjacent levels. Two patients had com-plications in the postoperative period. There was 1 case of in-fection, which was treated with debridement and irrigation and subsequent revision and exten-sion of fusion and anterior cor-pectomy. The other case was complicated by an ileus, which was managed conservatively.

All patients were followed with radiographs immediately postoperatively and at 6 weeks, 3 months, 6 months, 1 year, and 2 years. Procedure, follow-up, and demographic information is presented in the Table. Several patients are not yet 6 months post-fusion; further follow-up is needed for these patients.

surgical techniqueThe technique is imple-

mented after pedicle screw

placement. A 5-mm Mersilene suture (Figure 3) is used to con-nect the proximal screws (Fig-ures 4-6) or cross-link (Figure 3) to the spinous process above the last instrumented vertebra. The tape is available with 2 needles, which can facilitate passage with a needle driver. The suture is passed proximal to the adjacent level spinous process, staying deep to the su-praspinous and the interspinous ligaments (Figure 7). It is then looped distal to the spinous process with each needle, thus creating a 360° loop around the adjacent level spinous process. Alternatively, if needed, drill holes can be made in the spi-nous process to facilitate pas-sage of the suture and to keep it from slipping off of a steeply slanted spinous process (Fig-ure 5). The tape is then passed under the rod on each side and the ends are tied with good ten-sion. Alternatively, it can be

tied to a cross-link instead of the rods. Both techniques allow for direct midline tension on the adjacent level.

resultsOn the initial analysis of

outcomes following implemen-tation of Mersilene tape–based strap stabilization, none of the 18 patients have thus far de-veloped PJK by definition of a Cobb angle of 10° or greater. Average follow-up was 11.9 months (range, 2-31 months).

discussionProximal junctional kypho-

sis is a common radiographic finding following long spinal fusions. Risk factors for PJK include upper instrumented vertebrae above L2, older age at operation, low bone mineral density, short fusion constructs, and inadequate restoration of global sagittal balance.2 Along with these risk factors, pres-

Figure 2: A 36-year-old woman with fractures to T7-T8 resulting in diskitis and fusion of the vertebrae and progressive kyphosis. This patient was treated with pedicle subtraction osteotomy at T8 and posterior spinal fusion T2-L3. She developed proximal junctional kyphosis 6 weeks after surgery. This progressed to proximal junctional failure via osseo-ligamentous failure at the C7-T1 level. Preoperative lateral radiograph (A) and sagittal computed tomography scan (B). Postoperative lateral radiograph of the fusion from L3-T2 (C). Lateral radiograph (D) and sagittal computed tomography scan (E) of the construct after the failure and progression to proximal junctional failure.

A B C D E

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ervation of the natural biome-chanical support of the spine is important in preventing PJK.1,9

The interspinous/supraspi-nous ligament complex imme-diately above the instrumented

level has been found to maintain the natural support of spinal lev-els above the construct and to

potentially reduce the prevalence of PJK.1,2 If the interspinous/ supraspinous ligament com-

Table

Demographic Distribution of Patients Receiving Strap Stabilization

ProcedureAge at

Operation, y Preoperative DiagnosisFollow-up,

mo Gender

L3-4 XLIF and PSF L3-4 42 PJK after fusion L4-S1 6 Male

Re-instrumentation L2-3 61 L2-3 with pseudarthrosis 6 Female

L1-S1 PSF, L3-4 TLIF, L2-3 PSO 62 PJK with pseudarthrosis L2-S1 6 Female

T10-S1 PSF, L2-S1 XLIF 83 Degenerative scoliosis with failed L4-5 fusion

7 Male

T4-S1 PSF 68 Idiopathic scoliosis with degenerative disk disease

7 Female

L3-S1 PSF, L5-S1 TLIF, L3-4 TLIF 58 PJK with spinal canal stenosis L3-S1 8 Male

L1-5 XLIF, L1-S1 PSF, L5-S1 TLIF 74 Degenerative lumbar scoliosis 10 Female

T10-S1 PSF, L2-5 XLIF 67 Degenerative lumbar scoliosis with PJK 10 Female

T10-S1 PSF 74 Pseudarthrosis with PJK 12 Male

L2-S1 PSF, iliac screw placement 79 Degenerative lumbar disk disease with severe lumbar spinal stenosis

12 Female

T4-7 PSF 71 PJK with thoracolumbar myelopathy 31 Female

L3-4 TLIF, L4-5 HWR, L5-S1 PSF 57 PJK spondylolisthesis and spinal stenosis at L3-4

16 Female

L4-5 PSF, TLIF 71 PJK with spondylolisthesis and spinal steno-sis and degeneration at L4-5

20 Female

L3-S1 ALIF with PSF 53 L3-4, L4-5, L5-S1, with spinal stenosis and spondylosis

20 Female

L2-4 XLIF, L3-5 PSF 67 Degenerative lumbar disk disease L2-3 and 3-4 with prior L4-S1 spinal fusion

20 Female

PSF T5-12, PSO T11 74 Pseudarthrosis 22 Male

L3 screw removal and vertebroplasty with change of rod

52 PJK with hardware that appears to be loos-ened at L3

26 Male

PSO L1 and L2, TLIF L5-S1, and instrumentation T10-pelvis

53 Posttraumatic kyphosis lumbar spine and fusion L1-S1

6 Female

PSO L2 and instrumentation T10-L5 66 Junctional breakdown above fusion L2-S1 with sagittal imbalance

5 Male

Revision of instrumentation, debridement, and re-instrumentation T4-pelvis with Mersilene tape (Ethicon, Somerville, New Jersey) to T2. Corpec-tomy L4 with cage reconstruction.

61 Vertebral fracture above instrumentation T10 and destruction L4 secondary to infection and mechanical failure

5 Male

Revision instrumentation, removal of broken screw, extension fusion T10-pelvis

60 Previous multiple lumbar surgery with non-union, pelvic implant fracture, and sagittal imbalance

5 Female

VCR T12, T4-L5 PSF 44 Congenital hemivertebra D12 4 Male

L3 pedicle subtraction osteotomy, T10-S1 posterior fusion

65 Sagittal imbalance of the lumbar spine secondary to iatrogenic flat back

2 Male

Abbreviations: ALIF, anterior lumbar interbody fusion; HWR, hardware removal; PJK, proximal junctional kyphosis; PSF, posterior spinal fusion; PSO, pedicle subtraction osteotomy; TLIF, transforaminal lumbar interbody fusion; VCR, vertebral column resection; XLIF, extreme lateral interbody fusion.

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plex is compromised, or more support above the construct is needed, several techniques have been implemented to mimic the actions of these structures and to provide a transition from the rigidity of a completed spinal fu-sion to the naturally more flex-ible proximal vertebrae.

The use of sutures made from material such as Mersilene tape to provide strap stabiliza-tion for adjacent spinal levels is an under-documented technique that the authors believe provides several advantages over other

check-rein and soft stabilization techniques. When considering the cost of implementation and the risk of neurologic sequelae, the authors believe that the use of Mersilene tape serves as a unique and valuable option for reducing the prevalence of PJK.

Although the authors are ex-cited about the prospects of this surgical technique for prevent-ing PJK, more follow-up data are needed to assess the efficacy of Mersilene tape in preventing PJK in the long term. Although initial data suggest that the use

of Mersilene tape represents a potentially important additional tool for spinal deformity sur-gery, this material should not replace proper surgical plan-ning or technique. Also, as with many surgical spine procedures, there is a risk of implant failure. For this technique specifically, suture and/or spinous process failure is possible. Currently, however, the risk factors associ-ated with failure have not been identified and the prevalence has not been quantified.

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3. Glattes RC, Bridwell KH, Lenke LG, et al. Proximal junc-tional kyphosis in adult spinal deformity following long in-strumented posterior spinal fusion: incidence, outcomes and risk factor analysis. Spine. 1976; 30(14):1643-1649.

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Figure 3: Mersilene tape (Ethicon, Somerville, New Jersey) suture.

Figure 4: Mersilene tape (Ethicon, Somerville, New Jersey) passed around the spinous process and at-tached to a cross-link.

Figure 5: Mersilene tape (Ethicon, Somerville, New Jersey) passed through thoracic saw bone level.

Figure 6: Mersilene tape (Ethicon, Somerville, New Jersey) passed through lumbar saw bone level.

Figure 7: Mersilene tape (Ethicon, Somerville, New Jersey) passed around the spinous process and un-der the rods.

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spinal deformity surgeries from two years to three- to five-years follow-up. Spine. 2010; 35(20):1849-1854.

9. Cammarata M, Aubin CE, Wang X, Mac-Thiong JM. Biomechanical risk factors for proximal junctional kyphosis: a detailed numerical analysis of

surgical instrumentation vari-ables. Spine. 2014; 39(8):E500-E507.

10. Gaines RW Jr, Abernathie DL. Mersilene tapes as a substitute for wire in segmental spinal instrumentation for children. Spine (Phila Pa 1976). 1986; 11(9):907-913.

11. Puc MM, Antinori CH, Villan-ueva DT, et al. Ten-year experi-ence with Mersilene-reinforced sternal wound closure. Ann Tho-rac Surg. 2000; 70(1):97-99.

12. Yang SW, Lin LC, Chang SJ, Kuo SM, Hwang LC. Treatment of acute unstable distal clavicle fractures with single coracocla-

vicular suture fixation. Ortho-pedics. 2011; 34(6):e172-e177.

13. Grobler LJ, Gaines RW, Kempff PG. Comparing Mer-silene tape and stainless steel wire as sublaminar spinal fixa-tion in the Chagma baboon (Papio ursinus). Iowa Orthop J. 1997; 17:20-31.