Faculty Bibliography

OBJECTIVE: The aim of this study is to present our technique for a large focal correction of a partially flexible dropped head deformity through combined anterior and posterior osteotomies, as well as anterior soft tissue releases. METHODS: One patient with dropped head deformity underwent an anterior and posterior osteotomy with anterior soft tissue release. RESULTS: The patient recovered well, with postoperative radiographs demonstrating significant improvement in coronal and sagittal alignment. His C2-C7 sagittal vertical axis improved from 7.5 cm preoperatively to less than 4 cm postoperatively and his C2-C7 sagittal Cobb improved from 35 degrees of kyphosis to 10 degrees of lordosis. CONCLUSION: In this report, we present our technique for a large focal correction of a partially flexible dropped head deformity through combined anterior and posterior osteotomies and anterior soft tissue releases. These more conservative osteotomies permitted gradual deformity correction and alleviated the need for pedicle subtraction osteotomy. We were able to restore horizontal gaze and improve sagittal malalignment. Although the technique we present here is one of many possible options for managing the deformity, we believe this combined approach is safe and effective and well tolerated by patients.

OBJECTIVE Verifying the adequacy of surgical correction of adult spinal sagittal deformity (SSD) leads to improved postoperative alignment and clinical outcomes. Traditionally, surgeons relied on intraoperative measurements of lumbar lordosis (LL) correction. However, T-1 pelvic angle (TPA) and its component angles more reliably predict postoperative alignment. While TPA is readily measured on standing radiographs, intraoperative radiographs offer poor resolution of the bicoxofemoral axis. A method to recreate this radiographic landmark by extrapolating preoperative measurements has been described. The authors aimed to assess the reliability of measurements of global spinal alignment obtained via geometrical reconstitution of the bicoxofemoral axis on prone intraoperative radiographs. METHODS A retrospective review was performed. Twenty sets of preoperative standing full-length and intraoperative prone 36-inch lateral radiographs were analyzed. Pelvic incidence (PI) and sacral to bicoxofemoral axis distance (SBFD) were recorded on preoperative films. A perpendicular line was drawn on the intraoperative radiograph from the midpoint of the sacral endplate. This was used as one limb of the PI, and the second limb was digitally drawn at an angle that reproduced the preoperatively obtained PI, extending for a distance that matched the preoperative SBFD. This final point marked the obscured bicoxofemoral axis. These landmarks were used to measure the L-1, T-9, T-4, and T-1 pelvic angles (LPA, T9PA, T4PA, and TPA, respectively) and LL. Two spine fellows and 2 attending spine surgeons made independent measurements and repeated the process in 1 month. Mixed-model 2-way intraclass correlation coefficient (ICC) and Cronbach's α values were calculated to assess interobserver, intraobserver, and scale reliability. RESULTS Interobserver reliability was excellent for preoperative PI and intraoperative LPA, T9PA, and T4PA (ICC = 0.88, 0.84, 0.84, and 0.93, respectively), good for intraoperative TPA (ICC = 0.68), and fair for preoperative SBFD (ICC = 0.60) and intraoperative LL (ICC = 0.50). Cronbach's α was ≥ 0.80 for all measurements. Measuring PI on preoperative standing images had excellent intraobserver reliability for all raters (ICC = 0.89, range 0.80-0.93). All raters but one showed excellent reliability for measuring the SBFD. Reliability for measuring prone LL was good for all raters (ICC = 0.71, range 0.64-0.76). The LPA demonstrated good to excellent reliability for each rater (ICC = 0.76, range 0.65-0.81). The thoracic pelvic angles tended to be more reliable at more distal vertebrae (T9PA ICC = 0.71, range 0.49-0.81; T4PA ICC = 0.62, range 0.43-0.83; TPA ICC = 0.56, range 0.31-0.86). CONCLUSIONS Intraoperative assessment of global spinal alignment with TPA and component angles is more reliable than intraoperative measurements of LL. Reconstruction of preoperatively measured PI and SBFD on intraoperative radiographs effectively overcomes poor visualization of the bicoxofemoral axis. This method is easily adopted and produces accurate and reliable prone intraoperative measures of global spinal alignment.

STUDY DESIGN/METHODS:Retrospective review. OBJECTIVE:Determine whether alignment or myelopathy improvement drives patient outcomes after cervical deformity (CD) corrective surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:CD correction involves radiographic malalignment correction and procedures to improve motor function and pain. It is unknown whether alignment or myelopathy improvement drives patient outcomes. METHODS:Inclusion: Patients with CD with baseline/1-year radiographic and outcome scores. Cervical alignment improvement was defined by improvement in Ames CD modifiers. modified Japanese Orthopaedic Association (mJOA) improvement was defined as mild [15-17], moderate [12-14], severe [<12]. Patient groups included those who only improved in alignment, those who only improved in mJOA, those who improved in both, and those who did not improve. Changes in quality-of-life scores (neck disability index [NDI], EuroQuol-5 dimensions [EQ-5D], mJOA) were evaluated between groups. RESULTS:A total of 70 patients (62 yr, 51% F) were included. Overall preoperative mJOA score was 13.04 ± 2.35. At baseline, 21 (30%) patients had mild myelopathy, 33 (47%) moderate, and 16 (23%) severe. Out of 70 patients 30 (44%) improved in mJOA and 13 (18.6%) met 1-year mJOA minimal clinically important difference. Distribution of improvement groups: 16/70 (23%) alignment-only improvement, 13 (19%) myelopathy-only improvement, 18 (26%) alignment and myelopathy improvement, and 23 (33%) no improvement. EQ-5D improved in 11 of 16 (69%) alignment-only patients, 11 of 18 (61%) myelopathy/alignment improvement, 13 of 13 (100%) myelopathy-only, and 10 of 23 (44%) no myelopathy/alignment improvement. There were no differences in decompression, baseline alignment, mJOA, EQ-5D, or NDI between groups. Patients who improved only in myelopathy showed significant differences in baseline-1Y EQ-5D (baseline: 0.74, 1 yr:0.83, P < 0.001). One-year C2-S1 sagittal vertical axis (SVA; mJOA r = -0.424, P = 0.002; EQ-5D r = -0.261, P = 0.050; NDI r = 0.321, P = 0.015) and C7-S1 SVA (mJOA r = -0.494, P < 0.001; EQ-5D r = -0.284, P = 0.031; NDI r = 0.334, P = 0.010) were correlated with improvement in health-related qualities of life. CONCLUSION/CONCLUSIONS:After CD-corrective surgery, improvements in myelopathy symptoms and functional score were associated with superior 1-year patient-reported outcomes. Although there were no relationships between cervical-specific sagittal parameters and patient outcomes, global parameters of C2-S1 SVA and C7-S1 SVA showed significant correlations with overall 1-year mJOA, EQ-5D, and NDI. These results highlight myelopathy improvement as a key driver of patient-reported outcomes, and confirm the importance of sagittal alignment in patients with CD. LEVEL OF EVIDENCE/METHODS:3.

STUDY DESIGN/METHODS:Retrospective review of prospective multicenter adult spinal deformity (ASD) database. OBJECTIVE:To create a model based on baseline demographic, radiographic, health-related quality of life (HRQOL), and surgical factors that can predict patients meeting the Oswestry Disability Index (ODI) minimal clinically important difference (MCID) at the two-year postoperative follow-up. SUMMARY OF BACKGROUND DATA/BACKGROUND:Surgical correction of ASD can result in significant improvement in disability as measured by ODI, with the goal of reaching at least one MCID. However, a predictive model for reaching MCID following ASD correction does not exist. METHODS:ASD patients ≥18 years and baseline ODI ≥ 30 were included. Initial training of the model comprised forty-three variables including demographic data, comorbidities, modifiable surgical variables, baseline HRQOL, and coronal/sagittal radiographic parameters. Patients were grouped by whether or not they reached at least one ODI MCID at two-year follow-up. Decision trees were constructed using the C5.0 algorithm with five different bootstrapped models. Internal validation was accomplished via a 70:30 data split for training and testing each model, respectively. Final predictions from the models were chosen by voting with random selection for tied votes. Overall accuracy, and the area under a receiver operating characteristic curve (AUC) were calculated. RESULTS:198 patients were included (MCID: 109, No-MCID: 89). Overall model accuracy was 86.0%, with an AUC of 0.94. The top 11 predictors of reaching MCID were gender, Scoliosis Research Society (SRS) activity subscore, back pain, sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis mismatch (PI-LL), primary version revision, T1 spinopelvic inclination angle (T1SPI), American Society of Anesthesiologists (ASA) grade, T1 pelvic angle (T1PA), SRS pain, SRS total. CONCLUSIONS:A successful model was built predicting ODI MCID. Most important predictors were not modifiable surgical parameters, indicating that baseline clinical and radiographic status is a critical factor for reaching ODI MCID. LEVEL OF EVIDENCE/METHODS:Level II.

STUDY DESIGN/METHODS:Retrospective radiographic review. OBJECTIVES/OBJECTIVE:To understand the effect of variability in sacral endplate selection in transitional lumbosacral vertebrae (TLSV) and its impact on pelvic, regional, and global spinal alignment parameters. BACKGROUND:TLSV can have the characteristics of both lumbar and sacral vertebrae. Difficulties in identification of the S1 endplate may come from nomenclature, number of lumbar vertebrae, sacra, and morphology and may influence the interpretation and consistency of spinal alignment parameters. METHODS:Patients with TLSV were identified and radiographic measurements including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), sagittal vertical axis (SVA), T1-pelvic angle (TPA), pelvic incidence-lumbar lordosis (PI-LL) mismatch, thoracic kyphosis (TK), and spinal inclination (T1SPi) were obtained. Radiographic measurements were performed twice with the sacral endplate at the cephalad and caudal options. Paired t tests assessed the difference between different selection groups. RESULTS:Of 1,869 patients, 70 (3.7%) were found to have TLSV on radiographic imaging. Fifty-eight (82.9%) had lumbarized sacral segments whereas 12 (17.1%) had sacralized lumbar segments. T1-SPi (mean: -1.77°) and TK (mean: 34.86°) did not vary from altering sacral endplate selection. Selection of the caudal TLSV as the sacral endplate resulted in an increase in all pelvic parameters (PI: 66.8° vs. 44.3°, PT: 25.1° vs. 12.7°, and SS: 41.6° vs. 31.6°), regional lumbar parameters (LL: -54.1° vs. 44.0°, PI-LL: 12.7° vs. 0.3°), and global parameters (SVA: 46.1 mm vs. 28.3 mm, TPA: 23.3° vs. 10.8°) as compared to selecting the cephalad TLSV. All mean differences between radiographic parameters were found to be statistically significant (p < .001). CONCLUSIONS:Variation in sacral endplate selection in TLSV significantly affects spinal alignment parameter measurements. A standardized method for measuring TLSV is needed to reduce measurement error and ultimately allow more accurate understanding of alignment targets in patients with TLSV. LEVEL OF EVIDENCE/METHODS:Level III.

Background: Recent studies suggest non-routine discharge, includingdischarge to inpatient rehab and skilled nursing facilities, is associatedwith increased cost of care. Given the rising prevalence of cervicaldeformity (CD)-corrective surgery and the necessity of value-basedhealthcare, it is important to identify indicators for non-routine discharge in surgical CD patients.Study Design: Retrospective review of prospective, multicenter CDdatabase.Methods: Included: Surgical CD patients (C2-C7 Cobb [10,CL [10, cSVA [4 cm, or CBVA [25) [18 years with discharge and baseline (BL) radiographic data. Non-routine dischargedefined: inpatient rehab or skilled nursing facility. ConditionalInference Decision Trees identified predictors of non-routine discharge, and cut-off points at which predictors have a global effect.A Conditional Variable Importance Table used non-replacementsampling set of 3000 Conditional Inference trees to identify influential patient/surgical factors. Binary logistic regression indicated effectsize of influential factors at significant cut-off points. Means comparison testing assessed the relationship between non-routinedischarge and reop/HRQL outcomes.Results: Included: 138 patients (61 +/- 10 years, 63%F) undergoingCD-corrective surgery (8.2 +/- 4.6 levels; 49% posterior-onlyapproach, 16% anterior-only, 35% combined). 29% of patientsexperienced non-routine discharge (21% inpatient rehab, 8% SNF).BL cervical and upper-cervical malalignment was the strongest predictor of non-routine discharge: [1] C1 slope [14 (OR:8.4 [95%CI:3.1-22.7]), [3] C2 slope [57 (OR: 7.0 [2.6-18.3]), [4] TSCL [57 (OR: 5.9 [2.2-15.9]), [14] C0 slope[-0.66 (OR: 4.2[1.9-9.3]), [15] cSVA [40 mm (OR: 4.6 [2.0-10.9]), [18] McGregor's slope [1.9 (OR: 4.1 [1.7-9.9]). Patient-related predictors ofnon-routine discharge were [2] BL gait impairment (OR: 5.29[2.3-12.4]), [8] age [59 years (OR: 4.3 [1.6-11.1]), [10] apex of CDprimary driver [C7 (OR: 3.9[1.8-8.6]), and [13] admission tosurgical ICU (OR: 5.4 [1.9-14.8]). Experiencing 2 or more complications was predictive of non-routine discharge (OR: 4.2 [1.9-9.2]),but the only specific complications predictive of non-routone discharge were EBL [900 cc (OR: 3.6 [1.7-7.7]) and presence of anyneuro complication (OR: 2.8 [1.8-8.4]). The only surgical predictor ofnon-home discharge was [12] fusion[8 levels (OR: 4.0 [1.8-9.0]).LOS [6 days was also predictive of non-routone discharge (OR: 4.0[1.8-8.9]). There was no relationship between non-routine dischargeand reop within 3 months (P = 0.249), 6 months (P = 0.793), or1 year (P = 0.814) of index procedure. Despite no differences in BLEQ-5D (P = 0.946), non-routine patients had inferior 1-year postopEQ-5D scores (non-routine: 0.75, home: 0.79, P = 0.044).Conclusions: Preop cervical malalignment was a top predictor ofnon-routine discharge in surgical CD patients. Age, driver of deformity, and [8 level fusion also predicted non-routine discharge, andshould be taken into account to improve resource allocation andpatient counseling

Distal junctional kyphosis (DJK) is becoming a morecommonly recognized complication of cervical deformity (CD) surgery. DJK can erode corrections and postoperative cervicalmalalignment has been correlated with poor health outcomes(HRQL). The traditional definition of DJK is arbitrary (DJK angle(DJKA) change\10) and its clinical relevance is unproven. Anew "Severe DJK" definition is explored demonstrating betterspecificity, precision and accuracy with DJK revisions. Severe DJKpatients had the worst cervical alignment by cSVA and C2 Slope(C2S).Hypothesis: The definition of DJK can be improved for more clinicalrelevance.Design: Prospective cohort study.Introduction: Recently, DJK has been described as a complication ofCD correction. However, the current definition of DJK has failed tocorrelate with HRQL or revision rates.Methods: A prospective database of operative CD patients was analyzed. Inclusion criteria were cervical kyphosis [10, cervicalscoliosis [10, cSVA [4 cm or CBVA [25. DJKA was definedas a change from preop to postop kyphosis between LIV to LIV-2.Traditional DJK was defined as DJKA\-10 at any time pointwhile "Severe DJK" was defined as DJKA less than one SD of meanDJKA (-20). Patients without DJK (noDJK) were compared toTraditional and Severe. Cervical alignment was compared betweenthe three groups using ANOVA.Results: 112 patients were included. The mean maximum DJKA forthe whole cohort was-9.00 (SD = 10.0). There were 41 traditionalDJK (35.7%) and 11 Severe DJK (9.8%). Traditional DJK was notassociated with any preop alignment parameters, but Severe DJK wasassociated with an increased CTPA, C2S, cSVA and TSCL at baseline(p< 0.05). TSCL, C2S, and CTPA were increased in the Traditionaland Severe DJK compared to noDJK at 1 year (p< 0.05); postop T1Sand cSVA was increased in the Severe DJK group only. Severe DJKhad more posterior levels fused and more caudal posterior LIV. Therewas no significant difference in HRQL change at 3 months, 6 monthsand 1 year for either DJK group compared to noDJK. The DJKrevision surgery rate was 27.3% for Severe DJK and 8.20% for traditional DJK (p = 0.041). The Severe DJK criteria had betterspecificity (0.92 vs 0.63), precision (0.27 vs 0.12) and accuracy (0.86vs 0.62) for revision surgery. Severe DJK patients had the largest cSVA (61.2, 41.60, 38.56 mm, p<.001) and C2S (52.78, 27.70,24.73, p <.001). The mean time to revision was 4.72 months for thewhole cohort.Conclusions: The modified Severe DJK definition had better specificity, precision and accuracy for DJK revision surgery. Severe DJKpatients had the worst cervical alignment by cSVA and C2 slope withmean alignments well beyond the established thresholds for moderatedisability (Fig. 1)

Summary: In cervical deformity surgery, failure to correct cSVA andC2 slope (C2S) is associated with poor clinical outcomes. Currentsurgical planning and intraoperative measurements are limited tocervical lordosis (CL) correction. By predicting T1 Slope (T1S)change from baseline to 3 month postop and adding a correctionfactor for the change in distal junctional kyphosis angle (DJKA),cSVA and C2S can be predicted more accurately.Hypothesis: While correction of CL is commonly used to predictpost-op alignment, post-op cSVA, and C2S can be predicted betterusing additional variables.Design: Prospective cohort study.Introduction: Cervical malalignment is associated with severe disability. Currently, surgical planning and intraop measurements ofcorrection are limited to CL change. We aim to develop a predictivemodel for postop cSVA C2S and T1S using more than CL change.Methods: A prospective database of operative CD patients wasanalyzed. Inclusion criteria were cervical kyphosis [10, cervicalscoliosis [10, cSVA [4 cm or CBVA [25. The patients wererandomly filtered to include 66.7% of the cohort for model development. Predictive models were developed to estimate post-op T1S,cSVA, and C2S using linear regression. The new predictive equationswere validated in the remaining 33.3% of the cohort.Results: 153 patients with CD met inclusion criteria. T1S changedsignificantly (32.4-35.2, p =.05) from baseline to 3M follow-up.The mean DJKA change was-6.59. 101 patients were included inmodel development. To predict post-opT1S, CLchange and preT1Sexplained 62.4% of the variability of data (R2 = 0.624). By includingDJKA, R2 improved to 0.724. When predicting postop cSVA,CLchange and preop cSVA accounted for 57.2% of variability(R2 = 0.572). With change in DJKA, the R2 improved to 0.661. Themodel was optimized with the change in T1S (R2 = 0.777). Pre-opC2S and CLchange lead to poor predictability in post-op C2S(R2 = 0.348). Using DJKA change, the R2 improved to 0.550. Byincluding DJKA and T1S change, the model was optimized(R2 = 0.926).The predictive equations were applied to the remaining 52 patientsusing the mean DJKA (-6.59) for the DJKA variable and the T1Schange calculated for the predictive model. Predicted postop alignments correlated to postop T1S, cSVA, and C2S (R = 0.712,R = 0.736, and R = 0.584 respectively, p <0.01).Conclusions: Realignment in CD surgery is critical to obtain optimaloutcomes. Current surgical planning of CD does not accurately predict postop cSVA and C2S. A reliable predictive model is presentedfor cSVA and C2S using changes in T1S and DJKA

Cervical deformity (CD) can be debilitating. Surgery forsevere CD has high rates of radiographic and clinical failure. Among66 patients with severe CD, 62% had failure of radiographic correction at 1 year. Failed corrections were associated with worse baselinecervical alignment, male gender and greater intraoperative blood loss.Patients with failed corrections had less improvement in NDI at6 months and 1 year. More patients with successful correctionsattained MCID for NDI (84.2%) at 6 months.Hypothesis: Surgery for severe CD is challenging and there are highrates of radiographic and clinical failure.Design: Prospective cohort study.Introduction: Cervical malalignment is associated with disability.Surgical corrections of severe CD present considerable challenges.Demographic, surgical and postop factors associated with failedradiographic and clinical outcomes have not been well established.Methods: A prospective database of operative CD patients (Inclusioncriteria: cervical kyphosis[10, cervical scoliosis [10, cSVA [4 cm or CBVA [25) was analyzed. Inclusion was restricted tosevere baseline cervical deformities (cSVA [4 cm or C2 Slope(C2S) [20) and 1 year follow-up. Failed surgeries was defined ascSVA [4 cm at 1 year while successful surgery was defined ascSVA\4 cm at 1 year. Successful surgeries were compared to failedones with health related outcome measures, including the MCID forNDI (improvement [7).Results: 66 patients with severe CD met inclusion criteria, including41 failed (62%) surgery and 25 successful. Failed surgery patients hadworse alignment at baseline and 1 year by cSVA, C2S, T1S, TS-CL,and CTPA (p<0.05). Failed surgery patients were more commonlymale (51.2 vs 12%, p <0.01) and had greater intraop blood loss (1.2vs. 44L, p <0.01). History of prior cervical fusion, age, frailty, fusionlength, op-time, use of 3CO, DJK rate, and revision surgery were notassociated with failed surgery. Patients with failed surgery had lessimprovement in clinical outcomes by NDI at 6 months (-8.6 vs-21.7, p <.05) and 1 year (-7.7 vs-17.6, p <.05). Morepatients with successful surgery attained MCID for NDI at 6 months(84.2 vs 51.7%, p = 0.02) but there was no sig difference at 1 year(76.0 vs 56.8%, p = 0.12).Conclusions: Baseline cervical malalignment, male gender and intraop blood loss were associated with failed radiographic outcomes inpatients with severe CD. Failed surgery patients had less improvement in NDI at 6 months and 1 year. More patients with successfulsurgeries attained MCID for NDI at 6 months. In correcting severeCD, surgeons need to obtain optimal radiographic alignment to attainbetter clinical outcomes

Introduction: Cervical deformity (CD) correction has becomeincreasingly complex and challenging. Osteotomies are commonlyperformed to correct sagittal malalignment, however the risks andbenefits of performing a major osteotomy for cervical deformitycorrection have been understudied. The purpose of this study was toinvestigate the risks and benefits of performing a major osteotomy forCD correction.Methods: Retrospective review of a multicenter prospective CDdatabase. CD was defined as at least one of the following: C2-C7Cobb [10, CL [10, cSVA [4 cm, CBVA [25. Patientsstratified based on having a major osteotomy (MAJ-pedicle subtraction osteotomy or vertebral column resection) or minor (MIN).Propensity score matching (PSM) was performed controlling forbaseline cSVA and T1S. Flexibility of the deformity was assessedusing C2-C7 lordosis and T1S change greater than 10 betweenflexion and extension. Independent t-tests and Chi Squared tests wereused to assess differences between MAJ and MIN.Results: 89 CD patients were included (62 years, 65%F). 19 (21.3%)CD patients underwent a MAJ osteotomy. MAJ and MIN had nodifferences in any baseline radiographic parameters, with the exception of cSVA (MAJ: 59.3 mm, MIN: 41.9 mm, p = 0.007). AfterPSM for cSVA, 38 patients were included (60 years, 60%F). 19(21.3%) CD patients underwent a MAJ osteotomy (14 pedicle subtraction osteotomy, 5 vertebral column resection). MAJ patientsunderwent more invasive surgeries, with more levels fused (10.6 vs7.1, p <0.001) and blood loss (1442 cc vs 802 cc, p = 0.036),despite similar operative time and intra-and post-operative complication rates as MIN patients. At 3 M post-op, MAJ and MIN patientshad similar NDI, mJOA, and EQ5D scores, however by 6M and 1Ypost-op MAJ patients reached MCID for NDI less than MIN patients(10.5 vs 57.9%, p = 0.003). Comparing patients with fixed versusnon-fixed CL, MAJ patients with non-fixed lordosis trended towardsimprovement in NDI (p = 0.30) but also trended towards highercomplication (78 vs 43%, p = 0.182) and reoperation rates (44 vs 0%,p = 0.069) than fixed deformities. Rigid deformities trended towardsimprovement in TS-CL (43% improve vs 33%, p = 0.54) and cSVA(14 vs 0%, p = 0.49) for MAJ patients and lower complication rate(MIN most commonly had DJK and reoperation) (43 vs 100%,p = 0.09).Conclusions: Cervical deformity patients who underwent a majorosteotomy had similar clinical outcomes at 3-months but worseclinical outcomes at 6-months and 1-year, assessed by NDI and EQ-5D, as compared with patients with minor osteotomies, in partbecause patients undergoing major osteotomies have more severedeformities and have more prolonged recovery kinetics. Patients withflexible curves showed similar alignment and clinical outcomes butincreased complication risk when undergoing a major osteotomy.Contrarily, patients with rigid deformities who underwent a majorosteotomy trended towards radiographic and clinical improvementand lower rates of DJK and reoperation