SPINE Volume 40, Number 17, pp 1345-1351 ©2015, Wolters Kluwer Health, Inc. All rights reserved.
DEFORMITY
Type of Bone Graft or Substitute Does Not Affect Outcome of Spine Fusion With Instrumentation for Adolescent Idiopathic Scoliosis Alexander A. Theologis, MD,* Ehsan Tabaraee, MD,* Tracy Lin, MD,* John Lubicky, MD,† and Mohammad Diab, MD,* and Spinal Deformity Study Group
Study Design. Retrospective cohort analysis. Objective. To compare clinical outcomes after spine instrumentation and fusion using 3 different bone grafts in children with adolescent idiopathic scoliosis (AIS). Summary of Background Data. Autogenous iliac crest bone graft (AIC) is the “gold standard” to promote fusion in posterior AIS operations, although the morbidity of harvest is a concern. There is limited data comparing outcomes after AIS surgery based on types of bone grafts. Methods. Children (10–18 yr) with AIS who underwent deformity correction via a posterior approach were identified in the Spinal Deformity Study Group database. All had a minimum of 2-year follow-up. Patients were subdivided into 3 groups based on bone graft used: AIC, allograft, and bone substitute (BS). Clinical data included patient demographics, operative details, postoperative analgesic use, and perioperative complications. Lenke curve type and curve magnitude changes were radiographically analyzed. The Scoliosis Research Society-30 questionnaire was used to assess clinical outcomes. Results. 461 patients met inclusion criteria (girls: 381, boys: 80; average age 14.7 ± 1.7) and consisted of 152 AIC patients (124 girls, 28 boys), 199 allograft patients (167 girls, 32 boys), and 110 BS patients (90 girls, 20 boys). There was no difference in age (P = 0.41) or gender (P = 0.82). The BS group had significantly smaller preoperative curves and shorter operative times. Postoperatively,
From the *Department of Orthopaedic Surgery, University of California-San Francisco, San Francisco, CA; and †Department of Orthopaedic Surgery, West Virginia University, WV. Acknowledgment date: October 10, 2014. First revision date: February 16, 2015. Second revision date: March 16, 2015. Acceptance date: May 18, 2015. The manuscript submitted does not contain information about medical device(s)/drug(s). The Spinal Deformity Study Group received funding from Medtronic and the Orthopedic Research Education Foundation funds were received in support of this work. Relevant financial activities outside the submitted work: consultancy, employment, stocks, grants, travel/ accommodations/meeting expenses.. Address correspondence and reprint requests to Alexander A. Theologis, MD, Department of Orthopaedic Surgery, University of California-San Francisco, 500 Parnassus Avenue, MU325W, San Francisco, CA 94143-0728; E-mail: [email protected] DOI: 10.1097/BRS.0000000000001002 Spine
patients who received BS had significantly longer hospital stays, used higher quantities of patient-controlled intravenous analgesia and used epidurals longer. The AIC group used patient-controlled intravenous analgesia significantly longer. There were no differences between the groups in regards to curve type, number of levels fused, postoperative infections, pseudarthrosis, reoperations for any indication, and Scoliosis Research Society-30 scores at the latest follow-up. Conclusion. Outcomes after primary posterior spinal fusion with instrumentation are not influenced by type of bone graft or substitute. Key words: adolescent idiopathic scoliosis, posterior instrumentation, bone graft, iliac crest, clinical outcomes. Level of Evidence: 3 Spine 2015;40:1345–1351
T
he genesis of this study is rooted in the premise that the literature is pessimistic about autogenous iliac crest osseous graft (AIC), including donor site morbidity and increased blood loss and operative time.1–7 However, allogeneic osseous graft (AOG) and bone substitutes (BS) also have met criticism.8 Concerns about AOG include limited osteoinductive properties and risk of disease transmission.9 BS is expensive, and conflicts of interest with industry have undermined the interpretation of outcomes.10,11 Although recombinant human bone morphogenetic protein (rhBMP) is effective in promoting fusion, apprehension about its pro-oncogenic potential12 has limited its use in the pediatric population, although this trend may be changing.13 Previous studies have demonstrated no differences in outcomes after posterior fusion and instrumentation in children with adolescent idiopathic scoliosis (AIS) based upon type of bone graft.5,7,14,15 However, few have evaluated the differences between AIC, AOC, and BS, and few have provided definitive answers to clinically important questions in the surgical treatment of AIS. Do patients undergoing AIC harvest have significantly more pain? Does harvesting the iliac crest result in greater blood loss? Does it prolong the operation? Is AIC the “gold standard” for osseous fusion, conferring advantages over nonliving graft? Do bone substitutes confer any advantage that may justify their increased cost? www.spinejournal.com
1345
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE141331_LR 1345
08/08/15 8:25 AM
DEFORMITY
Spine Fusion with Instrumentation • Theologis et al
The objective of this study is to evaluate the differences in intraoperative, clinical, radiographic, and functional outcomes between AIC, AOG, and BS for posterior spine fusion with instrumentation in children with AIS.
variables. If a significant overall difference was found in the ANOVA analysis, a post hoc analysis was used to assess specific pairwise differences between groups. To assess for differences in continuous variables (curve magnitudes, SRS-30 scores) over time (1 yr and 2 yr postoperatively) a repeated measures ANOVA was conducted that included preoperative values as a covariate. An analysis of covariance (ANCOVA) was also performed to assess for differences in continuous variables (curve magnitudes) at individual postoperative timepoints if significant differences were noted with the ANOVA tests. All statistical tests provided 2-sided P values, which were considered to be significant when P < 0.05.
MATERIALS AND METHODS Approval was obtained from the Committees for Human Research at the 2 participating centers and the Research Committee of the Spinal Deformity Study Group (SDSG). Prospectively collected surgical data on children with AIS from 2002 to 2008 were analyzed retrospectively. Inclusion criteria were: age 10 to 18 years, primary operation, posterior approach, use of a single bone graft, no thoracoplasty, AIC harvest via a separate incision, and a minimum of 2-year follow-up. Patients were subdivided into 3 groups based upon fusion agent: AIC, AOG, and BS.
RESULTS Patient Population 461 patients met inclusion criteria (381 girls and 80 boys), having an average age of 14.7 ± 1.7 years (range, 10–18 yr). 152 patients (124 girls and 28 boys) received AIC, 199 patients (167 girls and 32 boys) received AOG, and 110 patients (90 girls and 20 boys) received BS. There were no differences in age (P = 0.41) or gender (P = 0.82) between the groups. Patients in the bone substitute group received the following bone graft agents: DBM (30; DePuy Synthes), beta-tricalcium phosphate (62; Depuy Synthes), rhBMP (11; Medtronic), coralline hydroxyapatite (5; Medtronic), and Cellect (2; DePuy Synthes—Selective Cell Retention technology in which bone marrow aspirate is combined with a matrix, which enriches the graft with an increased proportion of progenitor cells). 2 patients had bone marrow aspirate combined with BMP. No patients received calcium sulphate as a bone substitute.
Outcomes Clinical data included: age, gender, number of levels fused, intraoperative blood loss, operative time, type and duration of analgesic use postoperatively, length of hospital stay, and perioperative complications. Complications recorded were pseudarthrosis, surgical site infection, other wound problems (i.e., hematoma, dehiscence and suture reaction), and need for reoperation. Pseudarthrosis was identified by clinical and radiographic measures, including postoperative pain, loss of correction and implant failure, as well as at time of reoperation if performed. Radiographic results included Lenke curve type and changes in curve magnitude before and at 1 and 2 years after operation. Radiographic assessments were made on standing full-length posterior-anterior and lateral views, supine anteroposterior right and left bending views. Functional outcomes were assessed with the Scoliosis Research Society (SRS)-30 questionnaire.
Radiographic Assessment The majority of patients had Lenke 1 curves, followed by Lenke type 2, with no significant differences between the groups in distribution of curve types (Table 1). Average curve magnitudes were greater than 50° in all groups (Table 2), although they were significantly different (P = 0.003). Post hoc analysis demonstrated that the BS group had significantly lower mean preoperative curve magnitudes than the AIC and AOC groups (Table 2). Postoperative curve magnitudes were significantly different between the groups (Table 2). With preoperative curve magnitude controlled for as a covariate,
Statistical Analysis All statistical analyses were performed using the statistical package FAS 9.2 and SAS v. 9.3. Descriptive statistics were calculated and are presented as the frequency (percentage) for categorical variables and mean and standard deviation (SD) for variables measured on a continuous scale. Differences in continuous variables by group were assessed with analysis of variance (ANOVA) and χ2 or Fisher Exact Tests for categorical
TABLE 1. Lenke Curve Types in Children With Adolescent Idiopathic Scoliosis Who Underwent
Posterior Operation With 1 of 3 Types of Bone Grafts
Lenke Curve Type 1
2
3
4
5
6
AIC (n; %)
80 (52.6)
36 (23.7)
10 (6.6)
8 (5.3)
9 (5.9)
9 (5.9)
AOG (n; %)
92 (46.2)
50 (25.1)
18 (9.0)
8 (4.0)
18 (9.0)
13 (6.5)
BS (n; %)
53 (48.2)
27 (24.6)
8 (7.3)
0 (0)
10 (9.1)
12 (10.9)
P = 0.38. AIC indicates autogenous iliac crest osseous graft; AOG, allograft; BS, bone substitutes.
1346
www.spinejournal.com
September 2015
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE141331_LR 1346
08/08/15 8:25 AM
DEFORMITY
Spine Fusion with Instrumentation • Theologis et al
TABLE 2. Changes in Major Curve Cobb Angles After Posterior Operation for Adolescent Idiopathic
Scoliosis Based on Type of Bone Graft Used During the Index Operation AIC (n = 152)
AOG (n = 199)
BS (n = 110)
P
Preop (degrees; SD) (range)
58.7 ± 9.1 (38–88)
59.7 ± 12.8 (27–99)
54.8 ± 12.1 (26–95)*
0.003
1 yr (degrees; SD) (range)
27.2 ± 11.0 (3–54)†
25.4 ± 11.1 (0–69)
21.8 ± 9.6 (0–54)
0.007
2 yr (degrees; SD) (range)
24.2 ± 10.8 (1–61)‡
21.9 ± 10.7 (0–77)
18.9 ± 10.3 (1–52)
0.004
*Significantly smaller than AIC and AOG based on post hoc analysis. †Significantly higher than AOG (P = 0.006) based on ANCOVA analysis. ‡Significantly higher than AOG (P = 0.006) and BS (P = 0.03) based on ANCOVA analysis. AIC indicates autogenous iliac crest osseous graft; AOG, allograft; BS, bone substitutes.
patients who received AIC had significantly greater postoperative curve magnitudes compared with patients treated with AOG (1 and 2 yr) and BS (1 yr) (Table 2). Postoperatively, average curve magnitudes in the 3 groups were less than 25°; this was maintained throughout the 2-year follow-up (Table 2).
Operative and Hospital Parameters These are summarized in Table 3. Average number of levels fused was greater than 11 in each group, with no statistically significant difference. Although it did not reach statistical significance, average blood loss was lowest for the AIC group, 85 mL less than AOG and 63 mL less than BS. Operative time averaged greater than 230 min in each group. Patients who received bone substitute had significantly shorter operative times than those who received AIC and AOG. Length of hospital stay was significantly longer for the BS group, but did not differ between AIC and AOG groups.
Inpatient Use of Narcotic Medications The data are presented in Table 4. Patients who received AIC or AOG were equally divided between patient-controlled intravenous analgesia (PCIA) and patient controlled epidural analgesia (PCEA) postoperatively. More than 90% of BS patients received PCIA. Patients who received AIC used PCIA an average 10 hours longer than patients who had BS and 12 hours longer than patients who had AOG, which were significant differences. When BS patients
were given PCEA, they used it nearly 30 hours longer than patients receiving AIC or AOG. Patients who received AIC used significantly less oral and supplemental analgesics than the other 2 groups.
Complications Cumulatively, there were a total of 12 complications (Table 5). The most common complication was central spine surgical site infections (SSI): 4 developed in the AIC group and 1 in both the AOG and BS groups. There were no infections of the bone graft harvest site. There were 4 reoperations in the AIC group, 3 of which were for central spine SSI and 1 for implant revision. There was 1 pseudarthrosis, which occurred in a patient who received AIC and occurred 8 months after the index procedure. An initial revision was performed to replace a prominent rod that was tenting the skin as a result of a disengaged hook. During this operation, 8 cm of the prominent rod was removed. One year later the patient developed an infection. The second revision resulted in removal of implants, during which a pseudarthrosis was noted at T3 to T4. The patient returned to the original institution 5 years following operation without complaint or further complication. There were 2 revision operations in the BS group—one for a central spine SSI and the other for implant failure. There were no reoperations in the AOG group. Differences in complication and reoperation rates did not reach statistical significance between the groups.
TABLE 3. Intraoperative and Hospital Data After Posterior Operation for Adolescent Idiopathic
Scoliosis Correction Based on Type of Bone Graft
Mean # levels fused (SD) (range) EBL (mL; SD) * (range) OR time (min; SD) (range) LOS (d; SD) (range)
AIC (n = 152)
AOG (n = 199)
BS (n = 110)
P
11.3 ± 2.2 (6–16)
11.4 ± 2.4 (4–15)
11.4 ± 2.2 (6–15)
0.87
671 ± 352 (100–1700)
756 ± 430 (100–2000)
734 ± 434 (100–2,000)
0.16
279 ± 65 (160–480)
277 ± 74 (125–460)
232 ± 80 (100–420)
0.00
4.9 ± 1.1 (3–9)
4.8 ± 1.2 (3–10)
5.4 ± 1.3 (3–9)
0.0004
*Limited to patients with ≤ 2000 cc EBL. AIC indicates autogenous iliac crest graft; AOG, allograft; BS, bone substitute; EBL, estimated blood loss; OR, operating room; LOS, length of hospital stay.
Spine
www.spinejournal.com
1347
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE141331_LR 1347
08/08/15 8:25 AM
DEFORMITY
Spine Fusion with Instrumentation • Theologis et al
TABLE 4. Type and Duration of Analgesic Use After Primary Posterior Operation for Adolescent
Idiopathic Scoliosis Based on Type of Bone Graft AIC (n = 152)
AOG (n = 199)
BS (n = 110)
P
64 (42.1)
101 (50.8)
102 (92.7)
DEFORMITY
Type of Bone Graft or Substitute Does Not Affect Outcome of Spine Fusion With Instrumentation for Adolescent Idiopathic Scoliosis Alexander A. Theologis, MD,* Ehsan Tabaraee, MD,* Tracy Lin, MD,* John Lubicky, MD,† and Mohammad Diab, MD,* and Spinal Deformity Study Group
Study Design. Retrospective cohort analysis. Objective. To compare clinical outcomes after spine instrumentation and fusion using 3 different bone grafts in children with adolescent idiopathic scoliosis (AIS). Summary of Background Data. Autogenous iliac crest bone graft (AIC) is the “gold standard” to promote fusion in posterior AIS operations, although the morbidity of harvest is a concern. There is limited data comparing outcomes after AIS surgery based on types of bone grafts. Methods. Children (10–18 yr) with AIS who underwent deformity correction via a posterior approach were identified in the Spinal Deformity Study Group database. All had a minimum of 2-year follow-up. Patients were subdivided into 3 groups based on bone graft used: AIC, allograft, and bone substitute (BS). Clinical data included patient demographics, operative details, postoperative analgesic use, and perioperative complications. Lenke curve type and curve magnitude changes were radiographically analyzed. The Scoliosis Research Society-30 questionnaire was used to assess clinical outcomes. Results. 461 patients met inclusion criteria (girls: 381, boys: 80; average age 14.7 ± 1.7) and consisted of 152 AIC patients (124 girls, 28 boys), 199 allograft patients (167 girls, 32 boys), and 110 BS patients (90 girls, 20 boys). There was no difference in age (P = 0.41) or gender (P = 0.82). The BS group had significantly smaller preoperative curves and shorter operative times. Postoperatively,
From the *Department of Orthopaedic Surgery, University of California-San Francisco, San Francisco, CA; and †Department of Orthopaedic Surgery, West Virginia University, WV. Acknowledgment date: October 10, 2014. First revision date: February 16, 2015. Second revision date: March 16, 2015. Acceptance date: May 18, 2015. The manuscript submitted does not contain information about medical device(s)/drug(s). The Spinal Deformity Study Group received funding from Medtronic and the Orthopedic Research Education Foundation funds were received in support of this work. Relevant financial activities outside the submitted work: consultancy, employment, stocks, grants, travel/ accommodations/meeting expenses.. Address correspondence and reprint requests to Alexander A. Theologis, MD, Department of Orthopaedic Surgery, University of California-San Francisco, 500 Parnassus Avenue, MU325W, San Francisco, CA 94143-0728; E-mail: [email protected] DOI: 10.1097/BRS.0000000000001002 Spine
patients who received BS had significantly longer hospital stays, used higher quantities of patient-controlled intravenous analgesia and used epidurals longer. The AIC group used patient-controlled intravenous analgesia significantly longer. There were no differences between the groups in regards to curve type, number of levels fused, postoperative infections, pseudarthrosis, reoperations for any indication, and Scoliosis Research Society-30 scores at the latest follow-up. Conclusion. Outcomes after primary posterior spinal fusion with instrumentation are not influenced by type of bone graft or substitute. Key words: adolescent idiopathic scoliosis, posterior instrumentation, bone graft, iliac crest, clinical outcomes. Level of Evidence: 3 Spine 2015;40:1345–1351
T
he genesis of this study is rooted in the premise that the literature is pessimistic about autogenous iliac crest osseous graft (AIC), including donor site morbidity and increased blood loss and operative time.1–7 However, allogeneic osseous graft (AOG) and bone substitutes (BS) also have met criticism.8 Concerns about AOG include limited osteoinductive properties and risk of disease transmission.9 BS is expensive, and conflicts of interest with industry have undermined the interpretation of outcomes.10,11 Although recombinant human bone morphogenetic protein (rhBMP) is effective in promoting fusion, apprehension about its pro-oncogenic potential12 has limited its use in the pediatric population, although this trend may be changing.13 Previous studies have demonstrated no differences in outcomes after posterior fusion and instrumentation in children with adolescent idiopathic scoliosis (AIS) based upon type of bone graft.5,7,14,15 However, few have evaluated the differences between AIC, AOC, and BS, and few have provided definitive answers to clinically important questions in the surgical treatment of AIS. Do patients undergoing AIC harvest have significantly more pain? Does harvesting the iliac crest result in greater blood loss? Does it prolong the operation? Is AIC the “gold standard” for osseous fusion, conferring advantages over nonliving graft? Do bone substitutes confer any advantage that may justify their increased cost? www.spinejournal.com
1345
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE141331_LR 1345
08/08/15 8:25 AM
DEFORMITY
Spine Fusion with Instrumentation • Theologis et al
The objective of this study is to evaluate the differences in intraoperative, clinical, radiographic, and functional outcomes between AIC, AOG, and BS for posterior spine fusion with instrumentation in children with AIS.
variables. If a significant overall difference was found in the ANOVA analysis, a post hoc analysis was used to assess specific pairwise differences between groups. To assess for differences in continuous variables (curve magnitudes, SRS-30 scores) over time (1 yr and 2 yr postoperatively) a repeated measures ANOVA was conducted that included preoperative values as a covariate. An analysis of covariance (ANCOVA) was also performed to assess for differences in continuous variables (curve magnitudes) at individual postoperative timepoints if significant differences were noted with the ANOVA tests. All statistical tests provided 2-sided P values, which were considered to be significant when P < 0.05.
MATERIALS AND METHODS Approval was obtained from the Committees for Human Research at the 2 participating centers and the Research Committee of the Spinal Deformity Study Group (SDSG). Prospectively collected surgical data on children with AIS from 2002 to 2008 were analyzed retrospectively. Inclusion criteria were: age 10 to 18 years, primary operation, posterior approach, use of a single bone graft, no thoracoplasty, AIC harvest via a separate incision, and a minimum of 2-year follow-up. Patients were subdivided into 3 groups based upon fusion agent: AIC, AOG, and BS.
RESULTS Patient Population 461 patients met inclusion criteria (381 girls and 80 boys), having an average age of 14.7 ± 1.7 years (range, 10–18 yr). 152 patients (124 girls and 28 boys) received AIC, 199 patients (167 girls and 32 boys) received AOG, and 110 patients (90 girls and 20 boys) received BS. There were no differences in age (P = 0.41) or gender (P = 0.82) between the groups. Patients in the bone substitute group received the following bone graft agents: DBM (30; DePuy Synthes), beta-tricalcium phosphate (62; Depuy Synthes), rhBMP (11; Medtronic), coralline hydroxyapatite (5; Medtronic), and Cellect (2; DePuy Synthes—Selective Cell Retention technology in which bone marrow aspirate is combined with a matrix, which enriches the graft with an increased proportion of progenitor cells). 2 patients had bone marrow aspirate combined with BMP. No patients received calcium sulphate as a bone substitute.
Outcomes Clinical data included: age, gender, number of levels fused, intraoperative blood loss, operative time, type and duration of analgesic use postoperatively, length of hospital stay, and perioperative complications. Complications recorded were pseudarthrosis, surgical site infection, other wound problems (i.e., hematoma, dehiscence and suture reaction), and need for reoperation. Pseudarthrosis was identified by clinical and radiographic measures, including postoperative pain, loss of correction and implant failure, as well as at time of reoperation if performed. Radiographic results included Lenke curve type and changes in curve magnitude before and at 1 and 2 years after operation. Radiographic assessments were made on standing full-length posterior-anterior and lateral views, supine anteroposterior right and left bending views. Functional outcomes were assessed with the Scoliosis Research Society (SRS)-30 questionnaire.
Radiographic Assessment The majority of patients had Lenke 1 curves, followed by Lenke type 2, with no significant differences between the groups in distribution of curve types (Table 1). Average curve magnitudes were greater than 50° in all groups (Table 2), although they were significantly different (P = 0.003). Post hoc analysis demonstrated that the BS group had significantly lower mean preoperative curve magnitudes than the AIC and AOC groups (Table 2). Postoperative curve magnitudes were significantly different between the groups (Table 2). With preoperative curve magnitude controlled for as a covariate,
Statistical Analysis All statistical analyses were performed using the statistical package FAS 9.2 and SAS v. 9.3. Descriptive statistics were calculated and are presented as the frequency (percentage) for categorical variables and mean and standard deviation (SD) for variables measured on a continuous scale. Differences in continuous variables by group were assessed with analysis of variance (ANOVA) and χ2 or Fisher Exact Tests for categorical
TABLE 1. Lenke Curve Types in Children With Adolescent Idiopathic Scoliosis Who Underwent
Posterior Operation With 1 of 3 Types of Bone Grafts
Lenke Curve Type 1
2
3
4
5
6
AIC (n; %)
80 (52.6)
36 (23.7)
10 (6.6)
8 (5.3)
9 (5.9)
9 (5.9)
AOG (n; %)
92 (46.2)
50 (25.1)
18 (9.0)
8 (4.0)
18 (9.0)
13 (6.5)
BS (n; %)
53 (48.2)
27 (24.6)
8 (7.3)
0 (0)
10 (9.1)
12 (10.9)
P = 0.38. AIC indicates autogenous iliac crest osseous graft; AOG, allograft; BS, bone substitutes.
1346
www.spinejournal.com
September 2015
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE141331_LR 1346
08/08/15 8:25 AM
DEFORMITY
Spine Fusion with Instrumentation • Theologis et al
TABLE 2. Changes in Major Curve Cobb Angles After Posterior Operation for Adolescent Idiopathic
Scoliosis Based on Type of Bone Graft Used During the Index Operation AIC (n = 152)
AOG (n = 199)
BS (n = 110)
P
Preop (degrees; SD) (range)
58.7 ± 9.1 (38–88)
59.7 ± 12.8 (27–99)
54.8 ± 12.1 (26–95)*
0.003
1 yr (degrees; SD) (range)
27.2 ± 11.0 (3–54)†
25.4 ± 11.1 (0–69)
21.8 ± 9.6 (0–54)
0.007
2 yr (degrees; SD) (range)
24.2 ± 10.8 (1–61)‡
21.9 ± 10.7 (0–77)
18.9 ± 10.3 (1–52)
0.004
*Significantly smaller than AIC and AOG based on post hoc analysis. †Significantly higher than AOG (P = 0.006) based on ANCOVA analysis. ‡Significantly higher than AOG (P = 0.006) and BS (P = 0.03) based on ANCOVA analysis. AIC indicates autogenous iliac crest osseous graft; AOG, allograft; BS, bone substitutes.
patients who received AIC had significantly greater postoperative curve magnitudes compared with patients treated with AOG (1 and 2 yr) and BS (1 yr) (Table 2). Postoperatively, average curve magnitudes in the 3 groups were less than 25°; this was maintained throughout the 2-year follow-up (Table 2).
Operative and Hospital Parameters These are summarized in Table 3. Average number of levels fused was greater than 11 in each group, with no statistically significant difference. Although it did not reach statistical significance, average blood loss was lowest for the AIC group, 85 mL less than AOG and 63 mL less than BS. Operative time averaged greater than 230 min in each group. Patients who received bone substitute had significantly shorter operative times than those who received AIC and AOG. Length of hospital stay was significantly longer for the BS group, but did not differ between AIC and AOG groups.
Inpatient Use of Narcotic Medications The data are presented in Table 4. Patients who received AIC or AOG were equally divided between patient-controlled intravenous analgesia (PCIA) and patient controlled epidural analgesia (PCEA) postoperatively. More than 90% of BS patients received PCIA. Patients who received AIC used PCIA an average 10 hours longer than patients who had BS and 12 hours longer than patients who had AOG, which were significant differences. When BS patients
were given PCEA, they used it nearly 30 hours longer than patients receiving AIC or AOG. Patients who received AIC used significantly less oral and supplemental analgesics than the other 2 groups.
Complications Cumulatively, there were a total of 12 complications (Table 5). The most common complication was central spine surgical site infections (SSI): 4 developed in the AIC group and 1 in both the AOG and BS groups. There were no infections of the bone graft harvest site. There were 4 reoperations in the AIC group, 3 of which were for central spine SSI and 1 for implant revision. There was 1 pseudarthrosis, which occurred in a patient who received AIC and occurred 8 months after the index procedure. An initial revision was performed to replace a prominent rod that was tenting the skin as a result of a disengaged hook. During this operation, 8 cm of the prominent rod was removed. One year later the patient developed an infection. The second revision resulted in removal of implants, during which a pseudarthrosis was noted at T3 to T4. The patient returned to the original institution 5 years following operation without complaint or further complication. There were 2 revision operations in the BS group—one for a central spine SSI and the other for implant failure. There were no reoperations in the AOG group. Differences in complication and reoperation rates did not reach statistical significance between the groups.
TABLE 3. Intraoperative and Hospital Data After Posterior Operation for Adolescent Idiopathic
Scoliosis Correction Based on Type of Bone Graft
Mean # levels fused (SD) (range) EBL (mL; SD) * (range) OR time (min; SD) (range) LOS (d; SD) (range)
AIC (n = 152)
AOG (n = 199)
BS (n = 110)
P
11.3 ± 2.2 (6–16)
11.4 ± 2.4 (4–15)
11.4 ± 2.2 (6–15)
0.87
671 ± 352 (100–1700)
756 ± 430 (100–2000)
734 ± 434 (100–2,000)
0.16
279 ± 65 (160–480)
277 ± 74 (125–460)
232 ± 80 (100–420)
0.00
4.9 ± 1.1 (3–9)
4.8 ± 1.2 (3–10)
5.4 ± 1.3 (3–9)
0.0004
*Limited to patients with ≤ 2000 cc EBL. AIC indicates autogenous iliac crest graft; AOG, allograft; BS, bone substitute; EBL, estimated blood loss; OR, operating room; LOS, length of hospital stay.
Spine
www.spinejournal.com
1347
Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. SPINE141331_LR 1347
08/08/15 8:25 AM
DEFORMITY
Spine Fusion with Instrumentation • Theologis et al
TABLE 4. Type and Duration of Analgesic Use After Primary Posterior Operation for Adolescent
Idiopathic Scoliosis Based on Type of Bone Graft AIC (n = 152)
AOG (n = 199)
BS (n = 110)
P
64 (42.1)
101 (50.8)
102 (92.7)
