- Division of Neurosurgery, Duke University Medical Center, Durham, NC, USA
- Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, USA
Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, USA
DOI:10.4103/2152-7806.103868Copyright: © 2012 Adogwa O. 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: Adogwa O, Johnson K, Min ET, Issar N, Carr KR, Huang K, Cheng J. Extent of intraoperative muscle dissection does not affect long-term outcomes after minimally invasive surgery versus open-transforaminal lumbar interbody fusion surgery: A prospective longitudinal cohort study. Surg Neurol Int 26-Nov-2012;3:
How to cite this URL: Adogwa O, Johnson K, Min ET, Issar N, Carr KR, Huang K, Cheng J. Extent of intraoperative muscle dissection does not affect long-term outcomes after minimally invasive surgery versus open-transforaminal lumbar interbody fusion surgery: A prospective longitudinal cohort study. Surg Neurol Int 26-Nov-2012;3:. Available from: http://sni.wpengine.com/surgicalint_articles/extent-of-intraoperative-muscle-dissection-does-not-affect-long-term-outcomes-after-minimally-invasive-surgery-versus-open-transforaminal-lumbar-interbody-fusion-surgery-a-prospective-longitudinal-co/
Background:Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) versus open TLIF, addressing lumbar degenerative disc disease (DDD) or grade I spondylolisthesis (DS), are associated with shorter hospital stays, decreased blood loss, quicker return to work, and equivalent short- and long-term outcomes. However, no prospective study has assessed whether the extent of intraoperative muscle trauma utilizing creatinine phosphokinase levels (CPK) differently impacts long-term outcomes.
Methods:Twenty-one patients underwent MIS-TLIF (n = 14) versus open-TLIF (n = 7) for DDD or DS. Serum CPK levels were measured at baseline, and postoperatively (days 1, 7, and 1.5, 3 and 6 months). The correlation between the extent of intraoperative muscle trauma and two-year improvement in functional disability was evaluated (multivariate regression analysis). Additionally, baseline and two-year changes in Visual Analog Scale (VAS)-leg pain (LP), VAS-back pain (BP), Oswestry Disability Index (ODI), Short-Form-36 (SF-36) Physical Component Score (PCS) and SF-36 Mental Component Score (MCS), and postoperative satisfaction with surgical care were assessed.
Results:Although the mean change from baseline in the serum creatine phosphokinase level on POD 1 was greater for MIS-TLIF (628.07) versus open-TLF (291.42), this did not correlate with lesser two-year improvement in functional disability. Both cohorts also showed similar two-year improvement in VAS-LP, ODI, and SF-36 PCS/MCS.
Conclusion:Increased intraoperative muscle trauma unexpectedly observed in higher postoperative CPK levels for MIS-TLIF versus open-TLIF did not correlate with any differences in two-year improvement in pain and functional disability.
Harms and Rolinger first described the open transforaminal lumbar interbody fusion (TLIF) technique in 1982. It was devised to improve fusion rates, maintain vertebral alignment, and relieve mechanical back pain (BP).[
The primary aim of this two-year prospective study was to determine whether increased tissue distraction (based on the change in postoperative serum CPK levels), presumably more attributed to open-TLIF versus MIS-TLIF, would result in less improvement in pain/functional disability (change in ODI score). All patients underwent TLIF surgery by one of the two fellowship-trained spine surgeons at our institution. The institutional review board approved this study. The inclusion criteria included: (1) magnetic resonance imaging (MR) evidence of degenerative disc disease (DDD) or grade I spondylolisthesis (DS); (2) mechanical low back pain and radicular symptoms; (3) age between 18 and 70 years old; and (4) failure of at least 6 weeks of conservative therapy. The exclusion criteria included: (1) prior back surgery; (2) an extraspinal cause of back pain or sciatica; (3) an active medical or workman's compensation lawsuit; (4) any pre-existing spinal pathology; or (5) unwillingness or inability to participate with follow-up procedures. Patients with notable associated abnormalities, such as inflammatory arthritis, or metabolic bone disease, were also excluded.
Twenty-one patients undergoing MIS-TLIF or open-TLIF between 2008 and 2009 were prospectively entered into the database, and none were excluded or lost to follow-up.
The overall mean ± SD age was 47.28 ± 9.86 years (14 women and 7 men) [
Baseline and two-year clinical outcome measures
Two-year outcomes after TLIF surgery were prospectively assessed. Baseline and two-year postoperative pain/functional disability were assessed via face-to-face interviews by an independent investigator who was not involved with the clinical care. Questionnaires administered included: the Visual Analog Scales for low back pain (BP-VAS)[
At presentation, the overall mean ± SD back pain-VAS and leg-pain-VAS were 6.60 ± 2.12 (MIS-TLIF: 6.80 ± 2.40; open-TLIF: 6.14 ± 1.67; P = 0.47) and 5.74 ± 2.82 (MIS-TLIF: 5.99 ± 2.61; open-TLIF: 6.07 ± 2.69; P = 0.95), respectively [
Assessment of postoperative narcotic use, time to return to work, general satisfaction
The duration of narcotic use and the time to return to work were documented in real time as part of a standard of care protocol. Patients were also asked about their general satisfaction with their overall care, and outcomes after spine surgery. Patient satisfaction was dichotomized as either “YES” or “NO” on whether they were satisfied with their surgical outcome 2 years after surgery.
Performance of minimally invasive transforaminal lumbar interbody fusion versus open-transforaminal lumbar interbody fusion by two surgeons based on “preference”
MIS-TLIF versus open-TLIF was performed purely based on surgeon preference. All open-TLIFs were performed by one surgeon who uniformly preferred open approaches, while MIS-TLIFs were performed by a second surgeon who uniformly preferred MIS approaches. Nevertheless, both surgeons practiced similar postoperative management paradigms. In all cases, surgeons encouraged discharge from the hospital beginning 72 hours after surgery, weaned patients off narcotics beginning 2-3 weeks after surgery, and returned patients to work as soon as the patient felt capable.
Creatine phosphokinase measurements
Creatine phosphokinase (CPK) is an enzyme that is found primarily in skeletal muscle. Trauma and other conditions that damage skeletal muscle elevate serum CPK levels. To assess the significance of intraoperative muscle damage on long-term outcomes, peripheral venous blood samples were collected before surgery, and then postoperatively; days 1 and 7, and 1.5, 3, and 6 months. Serum concentrations of total CPK were measured using agarose gel electrophoresis, and the values were recorded in units/liter (U/L).
The primary aim of this study was to assess the independent effect of the extent of intraoperative muscle trauma on two-year outcomes (change in disability; ODI score) after MIS-TLIF versus open-TLIF surgery utilizing serum CPK levels. Parametric data were expressed as the mean ± standard deviation, and were compared utilizing the Student's t-test. Nonparametric data are expressed as the median (interquartile range), and were compared utilizing the Mann-Whitney U-test. Nominal data were compared with the χ2-test. Variables trending or significantly associated with two-year ODI in univariate regression analysis (P < 0.10) were entered into a multiple linear regression model to identify the independent predictors of postoperative outcome (change in ODI score). Stepwise multiple regression was performed to identify all the variables that were independently associated with two-year ODI (P < 0.05).
MIS-TLIF: Shorter Surgery, Less Estimated Blood Loss and Hospital Length of Stay Versus Open-TLIF.
MIS-TLIF and open-TLIF were performed at the L4-L5(52%) and L5-S1(48%) levels, and solely involved one-level fusions. The mean ± SD duration of surgery was longer for MIS-TLIF procedures versus open-TLIF procedures (235 ± 88.36 min versus 211± 43.23, P = 0.60). The mean ± SD estimated blood loss during surgery was less for MIS-TLIF versus open-TLIF [220 ± 207.32 mL versus 280 ± 219.65, P = 0.61]. The median (inter quartile range) length of hospitalization after surgery was less for MIS-TLIF compared with open-TLIF [3.0 (3.0-4.0) versus 3.5 (3.5-4) days, P = 0.65].
Minimal short-term postoperative complications
Of interest, postoperatively, no patients from either surgical category developed surgical site infections, or hardware failures. There were no perioperative complications in the MIS-TLIF cohort, including the absence of cerebrospinal fluid (CSF) leaks. However, for patients undergoing open-TLIF, two exhibited incidental durotomies (CSF leaks) that were successfully repaired intraoperatively, without any subsequent complications.
Relationship between serum creatine phosphokinase levels and duration of surgery
CPK levels peaked higher for MIS-TLIF one day postoperatively versus open-TLIF, but both returned to comparable levels within one postoperative week. Prior to surgery, the mean ± SD CPK levels were slightly elevated for the open-TLIF (96 ± 30) versus MIS-TLIF (111 ± 130) (P = 0.68) patients. However, the peak mean ± SD serum CPK level on POD 1 was higher for MIS-TLIF (739 ± 1002) versus open-TLIF (387 ± 242; P = 0.23) [
Differences in postoperative creatine phosphokinase levels for men and women
Preoperatively, there was no statistically significant difference in serum CPK levels between males and females (males: 188.33 ± 175.41 U/L; females: 73.46 ± 36.28 U/L; P = 0.17). As expected, on the first postoperative day, the total serum CPK level was significantly higher in males (1332.15 ± 1095 U/L) versus females (284.06 ± 134.85 U/L, P = 0.03) [
Comparison of the serum creatine phosphokinase (CPK) levels based on gender preoperatively and 1 day after surgery. Although serum CPK levels were significantly higher in males versus females (P= 0.03) 1 day postoperatively, both reported similar two-year improvement in pain/functional capacity
Both MIS-TLIF and open-TLIF cohorts demonstrated similar improvement in back pain-VAS, leg-pain-VAS, ODI, SF-36 PCS, and SF-12 MCS. The mean two-year outcomes were significantly improved from baseline levels for VAS-BP (3.14 versus 6.14 P = 0.0001), VAS-LP (1.58 versus 6.07, P = 2.94E-05), ODI (11.93 versus 22.57, P = 0.007), SF-36 PCS (39.28 versus 27.25, P = 0.002), and SF-36 MCS (52.32 versus 37.00, P = 0.04) [
Difference in serum creatinine phosphokinase (CPK) levels stratified by the surgery duration. Compared to with patients in the short operative time cohort, serum CPK levels were significantly higher in patients undergoing longer duration surgery (P=0.02). Independent of the extent of surgical invasiveness, patients in both cohorts reported similar two-year improvements in pain and functional capacity
Variables correlating with two-year improvement in pain/functional disability
In a univariate analysis, the baseline level of pain and functional disability (preoperative ODI and VAS BP/LP), quality of life (preop SF-36 PCS, SF-36 MCS), BMI, estimated intraoperative blood loss (EBL), and the extent of intraoperative muscle damage (change in serum CPK level) were all associated with two-year improvement in pain and functional disability. Alternatively, patient age, comorbidities such as diabetes, HTN, MI, depression and osteoporosis, and the duration of symptoms were not associated with a two-year improvement in pain and functional disability.
Correlation between postoperative creatine phosphokinase levels and two-year improvement in pain and functional disability
When included in a multivariate linear regression model, increasing intraoperative muscle damage (based on postoperative change in the serum CPK level) was not associated with less two-year improvement in pain and functional disability [
Correlation between postoperative change in serum cpk and patient satisfaction with care
Overall, 84% of patients reported being satisfied with their surgical outcome (MIS-TLIF: 85%; open-TLIF: 83%; P = 0.90). In a univariate analysis, baseline pain and functional disability (preop ODI and VAS BP/LP), quality of life (preop SF-36 PCS, SF-36 MCS), BMI, estimated intraoperative blood loss (EBL), extent of intraoperative muscle damage (change in serum CPK level), history of depression, patient age, and gender were all associated with patient-reported satisfaction with care. When included in a multivariate linear regression model, the extent of intraoperative muscle damage (based on postop change in serum CPK level) was not associated with patient satisfaction [
Similar two-year outcomes for minimally invasive transforaminal lumbar interbody fusion versus open-transforaminal lumbar interbody fusion: independent of muscle trauma
In this two-year prospective longitudinal cohort study, we assessed the clinical significance of elevated serum CPK levels on improvement in pain and functional disability 2 years after MIS-TLIF versus open-TLIF surgery. The two-year outcomes were similar, and independent of the extent of intraoperative muscle trauma. Independent of baseline levels of pain and functional disability, quality of life (preop SF-36 PCS, SF-36 MCS), BMI, and extent of surgical invasiveness, increasing serum CPK levels (a measure of muscle trauma) was not significantly or independently associated with less improvement in pain, functional disability, and patient reported satisfaction with care 2 years after MIS versus open-TLIF surgery.
Unanticipated higher creatine phosphokinase levels for minimally invasive transforaminal lumbar interbody fusion
Although short-term (1 day) serum CPK levels were higher following MIS-TLIF procedures compared to open-TLIF procedures, no statistically significant long-term differences in postoperative serum CPK levels were found between the two. The higher one-day postoperative CPK levels found with MIS-TLIF were unexpected, as one would assume these procedures would involve “less muscle dissection”, resulting in lower serum CPK levels. One possible explanation might be the “iatrogenic compartment syndrome” that can develop around a “contained” surgical bed. The small incision and limited surgical area of MIS procedures could limit the available space that displaced muscle and blood volume may migrate into. This in turn could lead to greater endothelial cell dysfunction, increased volume in the interstitial space of the affected tissues, and consequently, increases in tissue pressure. In contrast, the open-TLIF procedures have longer incisions and wider surgical beds, which decrease intramuscular pressures, and, consequently reduce the likelihood of developing an “iatrogenic compartment syndrome.” Future randomized, prospective studies are needed to determine whether the muscle splitting technique utilized to place the tubular retractor system for the MIS-TLIF procedures result in more or less muscle trauma versus the subperiosteal detachment of the muscle from the spinous process characteristic of open-TLIF.
Comparable long-term pain and functional capacity outcomes for minimally invasive transforaminal lumbar interbody fusion versus open-transforaminal lumbar interbody fusion
This study and others′ studies strongly suggest that both techniques (MIS-TLIF versus open-TLIF) are equally effective at relieving long-term pain, and provide similar benefits in long-term functional capacity.[
Other studies found an association between postoperative creatine phosphokinase and gender
A number of previous studies have found an association between postoperative serum CPK activity and gender.[
Limitations of this study
Lack of Creatine phosphokinase isoenzyme measurement
The first key limitation of this study was the lack of CPK isoenzyme measurement. Creatine phosphokinase has three known isoenzymes: CPK-BB in the brain, CPK-MB in the heart, and CPK-MM in skeletal muscle. In this study, only total serum CPK concentration was measured; however, CPK-MM accounts for greater than 95% of the total CPK level.[
Retrospective and nonrandomized study design
Another major limitation of this study is the lack of prospective randomization; one surgeon performed all open-TLIF procedures, and another performed all MIS-TLIF. These findings, therefore, may be surgeon-based/surgeon-specific and not generalizable. Nevertheless, the strength of the current study lies in the systematic postoperative evaluation of pain intensity and functional outcome in relation to serum CPK levels, and the unanticipated finding that, on postoperative day 1, more muscle trauma was associated with the longer MIS-TLIF versus open-TLIF procedures. Furthermore, the current study demonstrates that MIS-TLIF, using the tubular retractor system, was not superior to open-TLIF.
Although both MIS-TLIF and open-TLIF procedures provided comparable 2-year improvement in pain and functional capacity, contrary to expectations, MIS-TLIF was associated with greater muscular trauma reflected in higher short-term postoperative (1-day) serum CPK levels versus open-TLIF.
1. Adogwa O, Parker SL, Bydon A, Cheng J, McGirt MJ. Comparative effectiveness of minimally invasive versus open transforaminal lumbar interbody fusion: 2-year assessment of narcotic use, return to work, disability, and quality of life. editors. J Spinal Disord Tech. 2011. 24: 479-84
2. Arts M, Brand R, van der Kallen B, Lycklama A, Nijeholt G, Peul W. Does minimally invasive lumbar disc surgery result in less muscle injury than conventional surgery.A randomized controlled trial?. editors. Eur Spine J. 2011. 20: 51-57
3. Arts MP, Brand R, van den Akker ME, Koes BW, Bartels RH, Peul WC. Tubular diskectomy vs conventional microdiskectomy for sciatica: A randomized controlled trial. editors. JAMA. 2009. 302: 149-58
4. Arts MP, Nieborg A, Brand R, Peul WC. Serum creatine phosphokinase as an indicator of muscle injury after various spinal and nonspinal surgical procedures. editors. J Neurosurg Spine. 2007. 7: 282-6
5. Arts MP, Peul WC, Brand R, Koes BW, Thomeer RT. Cost-effectiveness of microendoscopic discectomy versus conventional open discectomy in the treatment of lumbar disc herniation: A prospective randomised controlled trial [ISRCTN51857546]. editors. BMC Musculoskelet Disord. 2006. 7: 42-
6. Copay AG, Glassman SD, Subach BR, Berven S, Schuler TC, Carreon LY. Minimum clinically important difference in lumbar spine surgery patients: A choice of methods using the Oswestry Disability Index, Medical Outcomes Study questionnaire Short Form 36, and pain scales. editors. Spine J. 2008. 8: 968-74
7. Copay AG, Subach BR, Glassman SD, Polly DW, Schuler TC. Understanding the minimum clinically important difference: A review of concepts and methods. editors. Spine J. 2007. 7: 541-6
8. Datta G, Gnanalingham KK, Peterson D, Mendoza N, O’Neill K, Van Dellen J. Back pain and disability after lumbar laminectomy: Is there a relationship to muscle retraction?. editors. Neurosurgery. 2004. 54: 1413-20
9. Fairbank JC, Couper J, Davies JB, O’Brien JP. The Oswestry low back pain disability questionnaire. editors. Physiotherapy. 1980. 66: 271-3
10. Fairbank JC, Pynsent PB. The Oswestry Disability Index. editors. Spine (Phila Pa 1976). 2000. 25: 2940-52
11. Foley KT, Holly LT, Schwender JD. Minimally invasive lumbar fusion. editors. Spine (Phila Pa 1976). 2003. 28: 26-35
12. Gallagher EJ, Liebman M, Bijur PE. Prospective validation of clinically important changes in pain severity measured on a visual analog scale. editors. Ann Emerg Med. 2001. 38: 633-8
13. Gandek B, Ware JE, Aaronson NK, Apolone G, Bjorner JB, Brazier JE. Cross-validation of item selection and scoring for the SF-12 Health Survey in nine countries: Results from the IQOLA Project.International Quality of Life Assessment. editors. J Clin Epidemiol. 1998. 51: 1171-8
14. Gronblad M, Hupli M, Wennerstrand P, Jarvinen E, Lukinmaa A, Kouri JP. Intercorrelation and test-retest reliability of the Pain Disability Index (PDI) and the Oswestry Disability Questionnaire (ODQ) and their correlation with pain intensity in low back pain patients. editors. Clin J Pain. 1993. 9: 189-95
15. Harms J, Rolinger H. [A one-stager procedure in operative treatment of spondylolistheses: Dorsal traction-reposition and anterior fusion (author's transl)]. editors. Z Orthop Ihre Grenzgeb. 1982. 120: 343-7
16. Jang JS, Lee SH. Minimally invasive transforaminal lumbar interbody fusion with ipsilateral pedicle screw and contralateral facet screw fixation. editors. J Neurosurg Spine. 2005. 3: 218-23
17. Kawaguchi Y, Matsui H, Tsuji H. Changes in serum creatine phosphokinase MM isoenzyme after lumbar spine surgery. editors. Spine (Phila Pa 1976). 1997. 22: 1018-23
18. Ntoukas V, Muller A. Minimally invasive approach versus traditional open approach for one level posterior lumbar interbody fusion. editors. Minim Invasive Neurosurg. 2010. 53: 21-4
19. Peng CW, Yue WM, Poh SY, Yeo W, Tan SB. Clinical and radiological outcomes of minimally invasive versus open transforaminal lumbar interbody fusion. editors. Spine (Phila Pa 1976). 2009. 34: 1385-9
20. Roland M, Fairbank J. The Roland-Morris Disability Questionnaire and the Oswestry Disability Questionnaire. editors. Spine (Phila Pa 1976). 2000. 25: 3115-24
21. Schizas C, Tzinieris N, Tsiridis E, Kosmopoulos V. Minimally invasive versus open transforaminal lumbar interbody fusion: Evaluating initial experience. editors. Int Orthop. 2009. 33: 1683-8
22. Shumate JB, Brooke MH, Carroll JE, Davis JE. Increased serum creatine kinase after exercise: A sex-linked phenomenon. editors. Neurology. 1979. 29: 902-4
23. Termote JL, Baert A, Crolla D, Palmers Y, Bulcke JA. Computed tomography of the normal and pathologic muscular system. editors. Radiology. 1980. 137: 439-44
24. Thurber S, Snow M, Honts CR. The Zung Self-Rating Depression Scale: Convergent validity and diagnostic discrimination. editors. Assessment. 2002. 9: 401-5
25. Ware J, Kosinski M, Keller SD. A 12-Item Short-Form Health Survey: Construction of scales and preliminary tests of reliability and validity. editors. Med Care. 1996. 34: 220-33
26. Wu RH, Fraser JF, Hartl R. Minimal access versus open transforaminal lumbar interbody fusion: Meta-analysis of fusion rates. editors. Spine (Phila Pa 1976). 2010. 35: 2273-81
27. Wukich DK, Van Dam BE, Graeber GM, Martyak T. Serum creatine kinase and lactate dehydrogenase changes after anterior approaches to the thoracic and lumbar spine. editors. Spine. 1990. 15: 187-190
28. Zung WW, Richards CB, Short MJ. Self-rating depression scale in an outpatient clinic.Further validation of the SDS. editors. Arch Gen Psychiatry. 1965. 13: 508-15