Slide 1

Spine Surgical Research at New England Baptist Hospital David H. Kim, MD Chief of Medical Education Spine Section, Dept of Orthopaedic Surgery Slide 2 Iliac Crest Bone Graft Harvest Related Pain and Morbidity David H. Kim, MD Louis Jenis, MD Robert Banco, MD Sharon Koogler Kelsey Miller Scott Tromanhauser, MD Slide 3 Introduction Frequently reported complications Frequently reported complications chronic pain numbness cosmetic appearance No consensus regarding incidence of pain or functional significance No consensus regarding incidence of pain or functional significance Principal factor driving search for viable bone graft alternatives Principal factor driving search for viable bone graft alternatives Few prospective studies of bone graft harvest site complications; no prospective study of functional disability Few prospective studies of bone graft harvest site complications; no prospective study of functional disability Slide 4 Comparative Use of Bone Graft Alternative Slide 5 Introduction Bone graft harvest site complications & fusion rates are two most important variables in cost-benefit calculations for high- priced technology such as recombinant growth factor Bone graft harvest site complications & fusion rates are two most important variables in cost-benefit calculations for high- priced technology such as recombinant growth factor Slide 6 Purpose Prospectively study rates of ICBG harvest pain & morbidity Prospectively study rates of ICBG harvest pain & morbidity rates & severity of pain numbness cosmetic complaints functional limitations Slide 7 Study Design Prospective cohort study Prospective cohort study Study population Study population patients undergoing autologous ICBG harvest as part of elective spinal surgery Slide 8 Study Population 135 adult patients prospectively enrolled 135 adult patients prospectively enrolled 12 month postop f/u period 12 month postop f/u period 5 patients failed f/u 130 patients in final study group Female/male: 71/59 Female/male: 71/59 Lumbar/cervical: 116/14 Lumbar/cervical: 116/14 Slide 9 Outcome Measures Visual analogue scale (VAS) for pain from ICBG harvest site Visual analogue scale (VAS) for pain from ICBG harvest site 12 month f/u questionnaire regarding symptoms & effect on functional activities. 12 month f/u questionnaire regarding symptoms & effect on functional activities. Slide 10 Methods Preoperative demographic data Preoperative demographic data Postoperative VAS pain scores at 6 wk, 6 mo, & 12 mo f/u Postoperative VAS pain scores at 6 wk, 6 mo, & 12 mo f/u 12 mo f/u questionnaire 12 mo f/u questionnaire Full-time research assistant Full-time research assistant Slide 11 Results Mean harvest site VAS pain scores Mean harvest site VAS pain scores 6 wks: 2.63 (S.D. 2.76) 6 mos: 1.77 (S.D. 2.42) 12 mos: 1.54 (S.D. 2.39) Slide 12 Harvest Site Pain N=129 Slide 13 Harvest Site Pain by Primary Surgical Site Slide 14 Harvest Site Pain by Age Slide 15 Harvest Site Pain by Sex Slide 16 Harvest Site Pain by Diagnosis Slide 17 Results 12 mo f/u: 12 mo f/u: 16.5% more severe pain from harvest site than primary surgical site 3.9% bothered by scar appearance 29.1% noticeable numbness 11.3% bothersome numbness Slide 18 Results Functional disability due to persistent harvest site pain: Functional disability due to persistent harvest site pain: 18.8% walking 10.3% job 19.0% recreational activity 21.5% household chores 10.8% sexual activity 5.1% irritation from clothing Slide 19 Conclusions High rate of persistent pain & morbidity from iliac crest bone graft harvest when associated with elective spine surgery High rate of persistent pain & morbidity from iliac crest bone graft harvest when associated with elective spine surgery Mean pain scores progressively decline over first postop year Mean pain scores progressively decline over first postop year Harvest site pain remains functionally limiting in many patients one year following surgery Harvest site pain remains functionally limiting in many patients one year following surgery Rates for functional limitation are higher than those previously reported Rates for functional limitation are higher than those previously reported Slide 20 Polymorphic Variation of the GTP Cyclohydrolase 1 Gene in Patients Undergoing Surgical Treatment for Lumbar Degenerative Disc Disease David H. Kim, MD; Mitchell Max, PhD; Inga Peter, PhD; Inna Belfer, PhD; Robert Banco, MD; Scott Tromanhauser, MD; Louis Jenis, MD; Carolyn Schwartz, ScD New England Baptist Hospital, Boston, USA National Institutes of Health, Bethesda, USA Slide 21 Introduction Pain is genetically determined Pain is genetically determined Genes that modulate pain sensitivity in humans Genes that modulate pain sensitivity in humans COMT [Diatchenko et al, Hum Mol Genet 2005; Zubieta et al, Science 2003] Mc1r [Mogil et al, Proc Natl Acad Sci USA 2003] GCH1 [Tegeder et al, Nature Med 2006] Slide 22 GCH1 GTP cyclohydrolase (GCH1) GTP cyclohydrolase (GCH1) Rate-limiting enzyme in BH4 synthesis BH4 essential cofactor for tyrosine, tryptophan, and phenylalanine hydroxylases, iNOS Expression in brain, spinal cord, and peripheral nerve [Lentz & Kapatos, Neurochem Int 1996; Hwang et al, Synapse 1998] Loss of function mutation causes hereditary progressive dystonia with marked diurnal fluctuation (HPD) aka dopa responsive dystonia [Ichinose et al, Nature Gen 1994] Slide 23 GCH1 and Pain Sensitivity 15 single nucleotide polymorphisms 15 single nucleotide polymorphisms Pain protective haplotype in 15.4% Pain protective haplotype in 15.4% Distribution follows Hardy-Weinberg Equilibrium in general population Distribution follows Hardy-Weinberg Equilibrium in general population Associated with less pain following lumbar discectomy Associated with less pain following lumbar discectomy Homozygotes reduced experimental pain sensitivity Homozygotes reduced experimental pain sensitivity [Tegeder et al, Nature Med 2006] [Kim & Dionne, Mol Pain 2008] Slide 24 Study Design Prospective cohort study Prospective cohort study 100 patients undergoing surgical treatment for lumbar DDD 100 patients undergoing surgical treatment for lumbar DDD Moderate to severe LBP > 6 months Failed nonoperative treatment (activity modification, NSAIDs, PT, injection) MRI evidence of 1-2 level DDD Venous blood sample, DNA extraction, GCH1 DNA sequence analysis Venous blood sample, DNA extraction, GCH1 DNA sequence analysis Slide 25 Results 15 single nucleotide polymorphisms (SNPs) in noncoding regions of GCH1 distributed evenly across gene 15 single nucleotide polymorphisms (SNPs) in noncoding regions of GCH1 distributed evenly across gene 14 of 15 loci informative in study population 14 of 15 loci informative in study population Slide 26 GCH1 Allele Frequencies Standard Locus Allele Frequency Error GCH1_1 C 0.7813 0.0264 GCH1_1 G 0.2188 0.0264 GCH1_2 A 0.2833 0.0352 GCH1_2 C 0.7167 0.0352 GCH1_3 C 0.7789 0.0265 GCH1_3 T 0.2211 0.0265 GCH1_4 C 0.2188 0.0264 GCH1_4 T 0.7813 0.0264 GCH1_5 C 0.3495 0.0321 GCH1_5 T 0.6505 0.0321 GCH1_6 A 0.3495 0.0330 GCH1_6 G 0.6505 0.0330 GCH1_7 G 0.0806 0.0205 GCH1_7 T 0.9194 0.0205 GCH1_8 C 0.1389 0.0305 GCH1_8 T 0.8611 0.0305 GCH1_9 C 0.7857 0.0322 GCH1_9 T 0.2143 0.0322 GCH1_10 A 0.3187 0.0334 GCH1_10 G 0.6813 0.0334 GCH1_11 A 0.7865 0.0274 GCH1_11 T 0.2135 0.0274 GCH1_12 C 0.9194 0.0205 GCH1_12 G 0.0806 0.0205 GCH1_13 A 0.5852 0.0379 GCH1_13 G 0.4148 0.0379 GCH1_14 C 0.8000 0.0262 GCH1_14 T 0.2000 0.0262 Standard Locus Allele Frequency Error Slide 27 GCH1 Genotype Frequencies HWD Standard Locus Genotype Frequency Coeff Error GCH1_1 C/C 0.5729 -0.0374 0.0129 GCH1_1 C/G 0.4167 -0.0374 0.0129 GCH1_1 G/G 0.0104 -0.0374 0.0129 GCH1_2 A/A 0.1000 0.0197 0.0222 GCH1_2 A/C 0.3667 0.0197 0.0222 GCH1_2 C/C 0.5333 0.0197 0.0222 GCH1_3 C/C 0.5684 -0.0383 0.0131 GCH1_3 C/T 0.4211 -0.0383 0.0131 GCH1_3 T/T 0.0105 -0.0383 0.0131 GCH1_4 C/C 0.0104 -0.0374 0.0129 GCH1_4 C/T 0.4167 -0.0374 0.0129 GCH1_4 T/T 0.5729 -0.0374 0.0129 GCH1_5 C/C 0.0860 -0.0361 0.0225 GCH1_5 C/T 0.5269 -0.0361 0.0225 GCH1_5 T/T 0.3871 -0.0361 0.0225 GCH1_6 A/A 0.0968 -0.0253 0.0229 GCH1_6 A/G 0.5054 -0.0253 0.0229 GCH1_6 G/G 0.3978 -0.0253 0.0229 GCH1_7 G/G 0.0108 0.0042 0.0095 GCH1_7 G/T 0.1398 0.0042 0.0095 GCH1_7 T/T 0.8495 0.0042 0.0095 GCH1_8 C/C 0.0667 0.0474 0.0202 GCH1_8 C/T 0.1444 0.0474 0.0202 GCH1_8 T/T 0.7889 0.0474 0.0202 GCH1_9 C/C 0.6374 0.0200 0.0195 GCH1_9 C/T 0.2967 0.0200 0.0195 GCH1_9 T/T 0.0659 0.0200 0.0195 GCH1_10 A/A 0.0879 -0.0136 0.0223 GCH1_10 A/G 0.4615 -0.0136 0.0223 GCH1_10 G/G 0.4505 -0.0136 0.0223 GCH1_11 A/A 0.5843 -0.0343 0.0133 GCH1_11 A/T 0.4045 -0.0343 0.0133 GCH1_11 T/T 0.0112 -0.0343 0.0133 GCH1_12 C/C 0.8495 0.0042 0.0095 GCH1_12 C/G 0.1398 0.0042 0.0095 GCH1_12 G/G 0.0108 0.0042 0.0095 GCH1_13 A/A 0.3523 0.0098 0.0259 GCH1_13 A/G 0.4659 0.0098 0.0259 GCH1_13 G/G 0.1818 0.0098 0.0259 GCH1_14 C/C 0.6105 -0.0295 0.0122 GCH1_14 C/T 0.3789 -0.0295 0.0122 GCH1_14 T/T 0.0105 -0.0295 0.0122 HWD Standard Locus Genotype Frequency Coeff Error Slide 28 Linkage disequilibrium measure, := cov(I 1, I 2 ) = p 1 p 2 h 12 = h 11 h 22 h 12 h 21 := cov(I 1, I 2 ) = p 1 p 2 h 12 = h 11 h 22 h 12 h 21Where: I 1, I 2 denote two loci p 1 p 2 denote allele frequencies h 12 denotes haplotype frequency = 0 linkage equilibrium 0 linkage disequilibrium Slide 29 Linkage disequilibrium measure, D D = x 11 p 1 q 1 D = x 11 p 1 q 1 A1A1A1A1 A2A2A2A2Total B1B1B1B1 x 11 =p 1 q 1 + D x 21 =p 2 q 1 - D q1q1q1q1 B2B2B2B2 x 12 =p 1 q 2 - D x 22 =p 2 q 2 + D q2q2q2q2 Total p1p1p1p1 p2p2p2p21 Slide 30 Lewontins D' Extension for diploid cells Extension for diploid cells D depends on allele frequency D depends on allele frequency D' = D/D max when D 0 D' = D/D max when D 0 D' = D/D min when D < 0 D' = D/D min when D < 0 Where: D max = lesser of p 1 q 2 or p 2 q 1 D min = greater of (-)p 1 q 1 or (-)p 2 q 2 D min = greater of (-)p 1 q 1 or (-)p 2 q 2 Slide 31 Correlation coefficient between loci pairs r 2 = D 2 /(p 1 p 2 q 1 q 2 ) r 2 = D 2 /(p 1 p 2 q 1 q 2 ) Slide 32 Linkage disequilibrium of GCH1 in patients with lumbar DDD Haploview results with confidence interval method Slide 33 --------Test for HWE-------- Number Number of of Hetero- Allelic Chi- Pr > Locus Indiv Alleles PIC zygosity Diversity Square DF ChiSq GCH1_1 96 2 0.2834 0.4167 0.3418 4.6063 1 0.0319 GCH1_2 90 2 0.3236 0.3667 0.4061 0.8490 1 0.3568 GCH1_3 95 2 0.2851 0.4211 0.3444 4.7095 1 0.0300 GCH1_4 96 2 0.2834 0.4167 0.3418 4.6063 1 0.0319 GCH1_5 93 2 0.3513 0.5269 0.4547 2.3454 1 0.1257 GCH1_6 93 2 0.3513 0.5054 0.4547 1.1563 1 0.2822 GCH1_7 93 2 0.1373 0.1398 0.1483 0.3055 1 0.5805 GCH1_8 90 2 0.2106 0.1444 0.2392 14.1226 1 0.0002 GCH1_9 91 2 0.2800 0.2967 0.3367 1.2861 1 0.2568 GCH1_10 91 2 0.3400 0.4615 0.4342 0.3594 1 0.5488 GCH1_11 89 2 0.2794 0.4045 0.3358 3.7224 1 0.0537 GCH1_12 93 2 0.1373 0.1398 0.1483 0.3055 1 0.5805 GCH1_13 88 2 0.3676 0.4659 0.4855 0.1429 1 0.7054 GCH1_14 95 2 0.2688 0.3789 0.3200 3.2237 1 0.0726 GCH1 allele procedure marker summary Slide 34 Results Genotype ratios for 4 SNPs significantly divergent from Hardy-Weinberg Equilibrium Genotype ratios for 4 SNPs significantly divergent from Hardy-Weinberg Equilibrium Underrepresented: rs10483639 (minor allele frequency, MAF 22%) p=0.0319 rs10483639 (minor allele frequency, MAF 22%) p=0.0319 rs752688 (MAF 22%); p=0.0300 rs752688 (MAF 22%); p=0.0300 rs4411417 (MAF 22%); p=0.0319 rs4411417 (MAF 22%); p=0.0319 Overrepresented: homozygous carriers of GCH1 rs12147422 (MAF 14%); p=0.0002 homozygous carriers of GCH1 rs12147422 (MAF 14%); p=0.0002 Slide 35 Conclusions As a group, patients presenting for surgical treatment of lumbar DDD demonstrate significant divergence from HWE and the general population for a set of polymorphisms in the pain-modulating gene GCH1 As a group, patients presenting for surgical treatment of lumbar DDD demonstrate significant divergence from HWE and the general population for a set of polymorphisms in the pain-modulating gene GCH1 Allelic variations in GCH1 may both predispose and protect patients from developing chronic pain associated with lumbar DDD Allelic variations in GCH1 may both predispose and protect patients from developing chronic pain associated with lumbar DDD Slide 36 Thank you!