Screw-only Constructs Research Articles

Screw-only fibular construct for Weber B ankle fractures: A retrospective clinical and cost comparison to assess feasibility for resource-limited settings

IntroductionAnkle fractures are one of the most common injuries sustained worldwide, with the majority being isolated lateral malleolus fractures. The majority of the world's population live in Low and Middle Income Countries (LMIC), where implant cost may limit surgical treatment of ankle fractures. We investigate if Weber B ankle fractures could be effectively treated with a lower-cost technique using two screws between the fibula and the tibia to neutralize an interfragmentary lag screw. MethodsAfter IRB approval, consecutive patients from January 1, 2020 to December 31, 2020 with Weber-B ankle fractures were treated using AO technique (AOT) with plate osteosynthesis neutralizing an interfragmentary screw. Syndesmotic injuries, as well as injuries to the medial malleolus or foot were treated according to the surgeon's preferences. From January 1, 2021 to December 31, 2021 these injuries were treated with a screw-only technique (SOT) with two fibula pro tibia screws to neutralize an interfragmentary screw. Patient demographics including age, sex, BMI, smoking status, associated rheumatoid arthritis, and associated diabetes mellitus were recorded. The primary outcome variable was a stable radiographic mortise at six weeks post-surgery, secondary outcome variables included clinical union, infection, hardware removal, and implant cost for lateral malleolar fixation charged to the hospital. ResultsSeventeen AOT and 10 SOT constructs were included. Demographic characteristics were similar between groups. All fractures maintained a stable mortise with clinical union at 6 weeks without infection. There was a statistically significant difference in hardware removal (17.6% AOT, 50% SOT, p = 0.012). The average implant cost to the hospital of the lateral malleolar fixation was significantly less in the SOT group ($592 (SD $229)), compared to the AOT group ($1,949.97 (SD $562)), (p < 0.0001). ConclusionWe introduce proof of concept of a novel lower-cost fixation strategy for Weber B ankle fractures that maintained a stable mortise with clinical union at six weeks post-surgery. However, there was a significantly higher rate of hardware removal following fixation with a screw-only construct.

Supination Adduction Vertical Medial Malleolar Fracture Fixation with Buttress Plating vs a Novel Screw-Only Construct: A Cadaveric Biomechanical Study.

Supination adduction ankle fractures are unique among rotational ankle fractures as plate constructs are more commonly used than independent screws for medial malleolar fixation. The purpose of this study was to compare fracture displacement between plate fixation to a novel screw-only construct using a cadaveric biomechanical early-weightbearing model for the treatment of vertical medial malleolus fractures. Six nonosteoporotic fresh-frozen cadaver shanks and feet in matched pairs underwent a vertical osteotomy of the medial malleolus to simulate the supination adduction type injury. Osteoporosis was measured using DEXA scans. One specimen from each pair was fixed with a one-third tubular buttress plate and the other with screw-only fixation. The specimens were then axially loaded for 100 000 cycles to simulate protected weightbearing, and subsequently loaded to failure in supination. Stiffness, fracture displacement, and load to failure were recorded. Statistical significance was set at P <.05. There were no measurable differences in displacement between the 2 constructs during axial cyclic loading after 100 000 cycles (plate, 0.74 ± 0.09 mm; screws, 0.79 ± 0.18 mm; P = .225). During supination and axial load to failure, the plate outperformed the screw construct. For load to failure (2 mm displacement) at the fracture site, the plate group failed at 716 ± 240 N, whereas the screw group failed at 567 ± 237 N (P = .015). During load to catastrophic failure, the plate group outperformed the screw group (plate, 6011 ± 1646 N; screws, 4578 ± 1837 N; P = .002). For vertical medial malleolar fractures, the screw-only construct demonstrated no statistical difference when compared to buttress plating for cyclical axial loading, simulating early weightbearing in a boot. However, buttress plating is 21% to 24% stronger than the screw-only fixation construct in overall strength and prevention of catastrophic failure when loading in a supinated position. The screw-only construct is biomechanically similar to a buttress plate when simulating early protected weightbearing. This suggests that early weightbearing as tolerated in a controlled ankle motion boot beginning 2 weeks postoperatively is mechanically safe for this fracture pattern and does not result in unacceptable amounts of fracture displacement. This construct may be useful as a less invasive treatment modality for the treatment of vertical medial malleolus fractures in select patients.

The analysis of progression of disc degeneration in distal unfused segments and evaluation of long-term functional outcome in adolescent idiopathic scoliosis patients undergoing long-segment instrumented fusion.

To analyse the progression of disc degeneration in distal unfused lumbar segments in post-operative Adolescent Idiopathic Scoliosis (AIS) patients; and to evaluate pre-operative and post-operative radiological parameters associated with progressive disc degeneration. A retrospective study of patients, who underwent surgery for AIS between 2006 and 2013 at a tertiary-care spine hospital, was conducted. Only patients aged between 11 and 18years, who underwent deformity correction surgery with pedicle screw-only constructs, minimum of 6.5year follow-up, and complete radiological data, and were included. On plain radiographs, coronal cobb's angle (CCA), apical translation, lower instrumented vertebra tilt (LIV tilt), LIV-Sacral angle, and sagittal spinal and pelvic parameters were measured. Disc degeneration was assessed on Magnetic Resonance Imaging (MRI) using Pfirrmann's grading. Total endplate score (TEPS) and facet degeneration (by Fujiwara's grading) were also measured. Based on the difference in progression of disc degeneration, patients were classified as Pfirrmann's grade static (PGS) and Pfirrmann's grade progressive (PGP) groups. Comparison of all pre- and post-operative parameters was made between PGS and PGP groups, and statistically analyzed. Functional evaluation was performed using SRS-22 score. A total of 58 patients were finally included. The mean follow-up was 9.1years. 43 (74.1%) and 15 (25.9%) patients were classified under PGS and PGP groups, respectively. Among the15 patients in PGP group, selected LIV was L4 in 8, L3 in 3, L1 in 3, and L2 in 1. Among them, 11 patients (73.3%) progressed from grade 1 to grade 2. In the remaining 4 (26.6%), Pfirrmann's grade progressed to ≥ 3. The progression of disc degeneration did not correlate with age or sex distribution (p = 0.3), pre-operative and post-operative TEP scores (p = 032), pre-operative disc or facet degeneration (p = 0.52), number of unfused spinal segments (p = 0.56), pre-operative or post-operative coronal (p = 0.42), or sagittal spinal (p = 0.27) or pelvic parameters (p = 0.14). The final functional outcome (SRS-22) was not significantly different between PGS and PGP groups (p = 0.67). 74% of AIS patients demonstrated no signs of progressive disc degeneration at an average follow-up of 9.1years. 26% (15/58) of AIS patients demonstrated progressive disc degeneration, among whom, degeneration progressed by only 1 Pfirrmann's grade in 74% (11/15). In the remaining four patients, disc degeneration progressed to Pfirrmann's grades 3 or greater. There was no correlation between higher grades of disc degeneration and lower instrumented vertebra (LIV) or functional outcomes scores (SRS-22).

Posterior Correction of Adolescent Idiopathic Scoliosis with High-Density Pedicle Screw-Only Constructs: 5 Years of Follow-Up.

PurposeThis study aimed to analyze radiological outcomes in patients with adolescent idiopathic scoliosis (AIS) who underwent posterior correction with high-density pedicle screw-only constructs. We hypothesized that high-density pedicle screw-only constructs in AIS would provide a high correction rate and would facilitate the maintenance of the correction or obviate the loss thereof.Materials and MethodsWe retrospectively analyzed radiological outcomes over a minimum follow-up period of 5 years in patients with AIS who underwent posterior correction with high-density pedicle screw-only constructs. A total of 124 consecutive patients were included. Demographic data, including age, sex, operated fusion level, numbers of screw, Lenke curve type, Risser stage, and follow-up period were retrospectively collected from electronic medical records and radiological measurements including serial follow-up.ResultsThe average number of pedicle screws was 1.96/vertebra. The average curve correction was 48.3% for the proximal thoracic (PT) curve, 83.1% for the main thoracic (MT) curve, and 80.2% for the thoracolumbar/lumbar (TL/L) curve at final follow-up. Use of high-density pedicle screw-only constructs helped achieve excellent correction rates, with no significant loss of correction at final follow-up.ConclusionWe obtained excellent correction rates of 48.3% for PT, 83.1% for MT, and 80.2% for TL/L curves using high-density pedicle screw-only constructs in AIS, with no significant loss of correction at final follow-up.

Screw fixation of ACPHT acetabular fractures offers sufficient biomechanical stability when compared to standard buttress plate fixation

BackgroundGeriatric acetabular fractures require fixation with sufficient primary stability to allow for immediate full-weight bearing. Minimally-invasive procedures would be desirable in order to keep perioperative morbidity low. The purpose of this study was to compare the biomechanical strength of lag screw-only fixation of anterior column posterior hemi-transverse (ACPHT) acetabular fractures to standard anatomical plate fixation.MethodsStandardized ACPHT fractures were created in fourth generation synthetic pelvis models and stabilized by either an anatomical buttress plate (n = 4) or by a screw-only construct (n = 4). In a validated setup, a cyclic loading protocol was applied with increasing axial force (3200 cycles, 175 N to 2250 N). Construct survival, acetabular fracture motion, and mode of failure were assessed.ResultsThe median number of cycles needed until failure of the construct occurred was 2304 cycles (range, 2020 to 2675) in the plate fixation group and 3200 cycles (range, 3101 to 3200) for the screw fixation constructs (p = .003). With regard to energy absorbed until failure, the plate fixation group resisted to 1.57 × 106 N*cycles (range, 1.21 × 106 to 2.14 × 106) and the screw fixation group to 3.17 × 106 N*cycles (range, 2.92 × 106 to 3.17 × 106; p = .001). All plate fixation specimens failed with a break-out of the posterior-column screw in the quadrilateral wing of the anatomical plate within a maximum load of 1750 N while the screw fixation constructs all survived loading of at least 2100 N. Acetabular fracture gap motion, acetabular rim angle, and medial femoral head subluxation as measures of fracture displacement were all not different between the two groups (p > 0.1).ConclusionsIn this in vitro biomechanical study, screw-only fixation of an ACPHT acetabular fracture resulted in at least as good construct survival as seen for standard buttress plate fixation. Both methods resisted sufficiently to forces that would be expected under physiologic conditions.

Hybrid constructs pedicle screw with apical sublaminar bands versus pedicle screws only for surgical correction of adolescent idiopathic scoliosis

To compare the 2-year minimum postoperative results of posterior correction and spinal arthrodesis using translational correction with hybrid (sublaminar bands on concave side and pedicle screw) constructs versus correction with intermediate density pedicle screw-only constructs in the treatment of AIS (Lenke 1). A total of 37 patients with AIS at single institutions who underwent posterior spinal arthrodesis pedicle screw with sublaminar bands at the apex (19 patients) (Group A) or pedicle screw-only (18) constructs (Group B) were selected and matched according to similar age at surgery 13.8years (Group A) and 14.3years (Group B), similar arthrodesis area 12.3 (Group A) and 11.5 (Group B), all curves Lenke type 1 with similar pre-op curve 54° (Group A) and 57° (Group B). Patients were evaluated pre-op, immediately post-op, and at min 2-year follow-up according to radiographic curve correction, operating time, intraoperative blood loss, and f.u. loss of correction. The average curve correction was 65.6% in sublaminar group and 68% in pedicle screw group. At 2-year follow-up, loss of the major curve correction was 2% in sublaminar group compared to 3% in pedicle screw group. Postoperative coronal and sagittal balance was similar in both groups. Operating time averaged 200min (Group A) and 180min (Group B). Intraoperative blood loss was significantly different in both groups 700 ± 160cc in sublaminar group and 630 ± 150cc in pedicle screw group. There were no neurologic complications in both groups. The two groups offer similar curve correction without neurologic complications in the surgical treatment of AIS (Lenke 1). The use of sublaminar bands on the apex (concave side) can be a valid fixation in the presence of hypoplastic pedicle, can reduce the thoracic hypokyphosis and derotate the vertebra but had more blood loss comparing to pedicle screws alone. These slides can be retrieved under Electronic Supplementary Material.

Management of spinal cord injury-related scoliosis using pedicle screw-only constructs.

Almost all pediatric patients who incur a spinal cord injury (SCI) will develop scoliosis, and younger patients are at highest risk for curve progression requiring surgical intervention. Although the use of pedicle screws is increasing in popularity, their impact on SCI-related scoliosis has not been described. The authors retrospectively reviewed the radiographic outcomes of pedicle screw-only constructs in all patients who had undergone SCI-related scoliosis correction at a single institution. Medical records and radiographs from Shriner's Hospital for Children-Philadelphia for the period between November 2004 and February 2011 were retrospectively reviewed. Thirty-seven patients, whose mean age at the index surgery was 14.91±3.29 years, were identified. The cohort had a mean follow-up of 33.2±22.8 months. The mean preoperative coronal Cobb angle was 65.5°±25.7°, which corrected to 20.3°±14.4°, translating into a 69% correction (p<0.05). The preoperative coronal balance was 24.4±22.6 mm, with a postoperative measurement of 21.6±20.7 mm (p=1.00). Preoperative pelvic obliquity was 12.7°±8.7°, which corrected to 4.1°±3.8°, translating into a 68% correction (p<0.05). Preoperative shoulder balance, as measured by the clavicle angle, was 8.2°±8.4°, which corrected to 2.7°±3.1° (67% correction, p<0.05). Preoperatively, thoracic kyphosis measured 44.2°±23.7° and was 33.8°±11.5° postoperatively. Thoracolumbar kyphosis was 18.7°±12.1° preoperatively, reduced to 8.1°±7.7° postoperatively, and measured 26.8°±20.2° at the last follow-up (p<0.05). Preoperatively, lumbar lordosis was 35.3°±22.0°, which remained stable at 35.6°±15.0° postoperatively. Pedicle screw constructs appear to provide better correction of coronal parameters than historically reported and provide significant improvement of sagittal kyphosis as well. Although pedicle screws appear to provide good radiographic results, correlation with clinical outcomes is necessary to determine the true impact of pedicle screw constructs on SCI-related scoliosis correction.

Treatment for Severe Idiopathic Upper Thoracic Scoliosis in Adolescence

To review the study of severe upper thoracic scoliosis (>90 degrees) in adolescence treated with pedicle screw constructs. The purpose of the present study was to analyze the treatment for upper thoracic scoliosis in adolescence. Upper thoracic scoliosis is an uncommon spinal deformity in young children. Upper thoracic scoliosis is special. There were 21 patients (11 boys and 10 girls) with severe upper thoracic scoliosis and their mean age was 15 years (range, 13-18 y). The mean Cobb angle was 102.2 degrees (90-118 degrees) The clavicle angle ranged from 18 to 23 degrees, with an average of 21 degrees. Patients with the major curve of scoliosis located in the upper thoracic spine were treated with a posterior spinal fusion with a pedicle screw-only construct. There was a minimum 2-year follow-up. Follow-up information was obtained clinically and radiologically. All patients underwent a posterior spinal fusion with a pedicle screw-only construct. Their shoulders were nearly balanced. The preoperative major curve was 102.2±8.9 degrees with a flexibility of 25.8%±8.1% in a side-bending film. The deformity was corrected to 29.7±5.9 and 32.1±5.6 degrees at the most recent follow-up. There was a 3.9-degree correction loss during the postoperative follow-up. There were no neurological or vascular complications at 2 years of follow-up. There was no crankshaft phenomenon. The pedicle screw constructs can be safely used for severe upper thoracic scoliosis. Curve correction is powerful for these curves, which are stiff and difficult to manage. Screw accuracy was excellent in this review.

Fixation of Lapidus Arthrodesis with a Plantar Interfragmentary Screw and Medial Locking Plate: A Report of 88 Cases

Lapidus arthrodesis is a powerful procedure that can be used to correct pathologic features within the forefoot or midfoot. Many different methods of fixation for this procedure have been reported. The use of plating constructs has been shown to provide increased stability compared with screw-only constructs. The technique we have described consists of a plantar to dorsal retrograde lag screw across the arthrodesis site, coupled with a low-profile medial locking plate. A total of 88 consecutive patients were treated with this modification of the Lapidus procedure by 2 surgeons and were retrospectively evaluated. All patients followed an early postoperative weightbearing protocol. Patient age, gender, follow-up duration, interval to weightbearing and radiographic fusion, preoperative and postoperative intermetatarsal angle, hardware removal, preoperative and postoperative American Orthopaedic Foot and Ankle Society midfoot scores, and adjunct procedures were analyzed. The mean follow-up period was 16.76 ± 5.9 (range 12 to 36) months, and all healed fusions demonstrated radiographic union at a mean of 51 ± 19.1 (range 40 to 89) days. The patients were treated with weightbearing starting a mean of 10.90 ± 4.1 (range 5 to 28) days postoperatively. Complications included 15 patients (17%) requiring hardware removal, 2 cases (2%) of hallux varus, 6 cases (7%) of radiographic recurrent hallux valgus, and 2 patients (2%) with first metatarsocuneiform nonunion. The results of the present study have demonstrated that plantar lag screw fixation with medial locking plate augmentation for Lapidus arthrodesis allows for early weightbearing with satisfactory outcomes, improved clinical and radiographic alignment, and improved American Orthopaedic Foot and Ankle Society scores.

Postoperative Trunk Shift in Lenke 1C Scoliosis

A risk factor analysis study. To identify the causative factors for postoperative trunk shift in Lenke 1C scoliosis and investigate how to prevent it. When selective thoracic fusion is performed, postoperative trunk shift is a significant problem in the management of Lenke 1C scoliosis. It is often accompanied by unsatisfactory clinical outcomes and a risk of reoperation. We reviewed all the patients with adolescent idiopathic scoliosis (AIS) surgically treated in our institution from 2002 through 2008. Inclusion criteria were as follows: (1) patients with Lenke 1C curves who were treated with selective thoracic fusion using posterior pedicle screw-only constructs; (2) the lowest instrumented vertebra (LIV) ending at L1 level or above; and (3) 2-year radiographical follow-up. Eighteen radiographical parameters were chosen as potential risk factors. The 18 parameters measured (1) amount of correction obtained by surgery; (2) preoperative position of LIV; (3) magnitude of major thoracic and thoracolumbar/lumbar (MT and TL/L) curves and ratio of MT: TL/L curve; and (4) curve flexibility. Both comparative and correlation analyses were performed. Those parameters that had shown highest correlation with the 2-year thoracic apical vertebra-center sacral vertical line (AV-CSVL) distance were selected to form a linear regression model, by which the correlations were quantified. Of the 278 patients reviewed, 44 met the inclusion criteria. The parameters that measured the preoperative position of LIV and ratio of MT: TL/L curve showed high correlation with the 2-year thoracic AV-CSVL distance. With regard to the parameters that measured the amount of correction obtained by surgery, only the correction of the thoracic AV-T1 distance showed low correlation. Among the 18 parameters, preoperative lowest instrumented vertebra-lower end vertebra (LIV-LEV) difference and ratio of MT: TL/L Cobb angle were selected to form a formula to help predict postoperative trunk shift. The formula was as follows: 2-year thoracic AV-CSVL distance = -26.6 + 22.7 (ratio of MT: TL/L Cobb angle) - 3.9 (preoperative LIV-LEV difference). The model R2 = 0.55. Both LIV selection and ratio of MT: TL/L curve were found to be highly correlated with the onset of postoperative trunk shift in Lenke 1C scoliosis. Amount of correction obtained by surgery, however, did not seem to be an independent causative factor. Postoperative trunk shift is less likely to occur when selecting LEV as LIV and the ratio of MT: TL/L Cobb angle of 1.2° or more.

Postoperative spinal alignment remodeling in Lenke 1C scoliosis treated with selective thoracic fusion

Selective thoracic fusion may cause spinal imbalance in certain patients; how the spinal alignment changes over time after surgery is highly correlated with the final spinal balance. To investigate how spinal alignment changes over time after selective thoracic fusion and how spinal alignment remodeling affects spinal balance. All adolescent idiopathic scoliosis (AIS) cases surgically treated in our institution between 2002 and 2008 were reviewed. Inclusion criteria were as follows: Lenke 1C scoliosis patients treated with posterior pedicle screw-only constructs; the lowest instrumented vertebra (LIV) ended at L1 level or above; and 2-year radiographic follow-up. Standing anteroposterior and lateral digital radiographs from four different time points (preoperatively, immediately, 3 months, and 2 years postoperatively) were reviewed. In each standing anteroposterior radiograph, the center sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, and the translation (deviation from the CSVL) of some key vertebrae was measured, such as the LIV, LIV+1 (the first vertebra below LIV), LIV+2 (the second vertebra below LIV), LIV+3 (the third vertebra below LIV), lumbar apical vertebra (AV), thoracic AV, and T1. Additionally, the Cobb angles of the major thoracic and lumbar curves were measured at different time points, and the correction rates were calculated. Furthermore, clinical photographs of the patients from the back were taken preoperatively and postoperatively. Of 278 AIS patients reviewed, 29 met the inclusion criteria. The continuous follow-up of our present study revealed an interesting phenomenon: postoperative spinal alignment remodeling. A hypothetical criterion was established to determine the onset of the phenomenon. By means of a series of analyses, the criterion was validated. The results of our present study showed that selective thoracic fusion tended to cause leftward spinal imbalance in these Lenke 1C AIS patients. Twenty of the 29 patients had leftward spinal imbalance immediately after surgery. Although some patients regained spinal balance through postoperative spinal alignment remodeling, 11 patients remained imbalanced at 2-year follow-up. Selective thoracic fusion is prone to cause leftward spinal imbalance in Lenke 1C scoliosis patients. Postoperative spinal alignment remodeling can facilitate recovery of spinal balance in some patients. Postoperative spinal imbalance in Lenke 1C scoliosis patients could be prevented by selecting stable vertebra or the vertebrae above as LIV, checking the balance condition during surgery, or considering ratio criteria when selecting candidates for selective thoracic fusion.

Lowest instrumented vertebra selection in Lenke 3C and 6C scoliosis: what if we choose lumbar apical vertebra as distal fusion end?

The aim of this study was to investigate whether or not post-op curve behaviour differs due to different choices of lowest instrumented vertebra (LIV) with reference to lumbar apical vertebra (LAV) in Lenke 3C and 6C scoliosis. We reviewed all the AIS cases surgically treated in our institution from 2002 through 2008. Inclusion criteria were as follows: (1) patients with Lenke 3C or 6C scoliosis who were treated with posterior pedicle screw-only constructs; (2) 2-year radiographic follow-up. All the included patients were categorized into three groups based on the relative position of LIV and LAV: Group A-the LIV was above the LAV; Group B-the LIV was at the LAV; Group C-the LIV was below the LAV. All the radiographic parameters were then compared among the groups. All image data were available in our picture archiving and communication systems. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four times (pre-op, post-op, 3-month and 2-year). In each standing AP radiograph, centre sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, followed by measuring T1-CSVL, LIV-CSVL, (LIV+1)-CSVL, LAV-CSVL and thoracic AV-CSVL distance. In addition, the Cobb angles of major thoracic and lumbar curves were measured at the four times and the correction rates were then calculated. Of the 278 patients reviewed, 40 met the inclusion criteria; 11 of these were included in Group A (LIV above LAV), another 11 in Group B (LIV at LAV) and the remaining 18 in Group C (LIV below LAV). At 2-year follow-up, the lumbar vertebrae such as LIV, LIV+1 and LAV were all more deviated than before surgery in Group A (LIV above LAV), whereas in Group B and C (LIV at and below LAV) they were all less deviated than before surgery. No significant differences were found in thoracic or lumbar correction rate, global coronal balance and incidence rate of trunk shift among the three groups. In conclusion, in Lenke 3C and 6C scoliosis, post-op lumbar curve behaviour differs due to different choices of LIV with reference to LAV, that is, the deviation of lumbar curve improves when the LIV is either at or below the LAV but deteriorates when the LIV is above the LAV. Although the greatest correction occurs when the LIV is below the LAV, choosing LAV as LIV can still be the optimal option in certain cases, since it can yield similar correction while preserving more lumbar mobility and growth potential.

Extensive fusion for Lenke 3C and 6C scoliosis: a two year radiographic follow-up

To investigate the correction effectiveness, incidence rate of distal adding on, and post-operative spinal balance in Lenke 3C and 6C AIS treated with extensive fusion using posterior pedicle screw-only constructs. We reviewed all AIS cases surgically treated in our institution between 2002 and 2008. The inclusion criteria were as follows: (1) Lenke 3C or 6C scoliosis patients who were treated with extensive fusion using posterior pedicle screw-only constructs; (2) minimum two year radiographic follow-up; (3) the lowest instrumented vertebra (LIV) ended at L2, L3 or L4 level. All image data were available in our picture archiving and communication systems (PACSs) , and all radiographic measurements were performed. Standing anteroposterior (AP) and lateral digital radiographs were reviewed at four different time points (pre-op, post-op, three months, and two years). In each standing AP radiograph, CSVL (center sacral vertical line, the vertical line bisecting the proximal sacrum) was first drawn, followed by measurement of the translation (deviation from the CSVL) of some key vertebrae, such as the lowest instrumented vertebra (LIV), LIV + 1 (the first vertebra below LIV), lumbar apical vertebra, thoracic apical vertebra and T1, enabling depiction of how translation of different parts of the spine changes over time. Additionally, the Cobb angles of major thoracic and lumbar curves were measured at the different time points and the correction rate was calculated. Of the 278 patients reviewed, 25 met the inclusion criteria. Immediately after surgery, satisfactory corrections were achieved from the perspective of not only Cobb angle but also vertebral translation. And the corrections were well retained in the following two years. The incidence rate of distal adding-on was low in this group of patients. In the course of two years following surgery, only six patients had an increase of greater than 5 mm in LIV + 1 translation, and among which only two patients had greater than 10 mm. Regarding global balance, overall, it neither improved nor deteriorated after extensive fusion. Furthermore, trunk shift was found in only three patients at two year follow-up. In Lenke 3C and 6C scoliosis, extensive fusion can produce satisfactory corrections from the perspectives of both Cobb angle and vertebral translation and rarely causes significant distal adding-on, global imbalance or trunk shift.

Complications in the Surgical Treatment of 19,360 Cases of Pediatric Scoliosis

Retrospective review of a multicenter database. To determine the complication rates associated with surgical treatment of pediatric scoliosis and to assess variables associated with increased complication rates. Wide variability is reported for complications associated with the operative treatment of pediatric scoliosis. Limited number of patients, surgeons, and diagnoses occur in most reports. The Scoliosis Research Society Morbidity and Mortality (M&M) database aggregates deidentified data, permitting determination of complication rates from large numbers of patients and surgeons. Cases of pediatric scoliosis (age ≤18 years), entered into the Scoliosis Research Society M&M database between 2004 and 2007, were analyzed. Age, scoliosis type, type of instrumentation used, and complications were assessed. A total of 19,360 cases fulfilled inclusion criteria. Of these, complications occurred in 1971 (10.2%) cases. Overall complication rates differed significantly among idiopathic, congenital, and neuromuscular cases (P < 0.001). Neuromuscular scoliosis had the highest rate of complications (17.9%), followed by congenital scoliosis (10.6%) and idiopathic scoliosis (6.3%). Rates of neurologic deficit also differed significantly based on the etiology of scoliosis (P < 0.001), with the highest rate among congenital cases (2.0%), followed by neuromuscular types (1.1%) and idiopathic scoliosis (0.8%). Neur-omuscular scoliosis and congenital scoliosis had the highest rates of mortality (0.3% each), followed by idiopathic scoliosis (0.02%). Higher rates of new neurologic deficits were associated with revision procedures (P < 0.001) and with the use of corrective osteotomies (P < 0.001). The rates of new neurologic deficit were significantly higher for procedures using anterior screw-only constructs (2.0%) or wire-only constructs (1.7%), compared with pedicle screw-only constructs (0.7%) (P < 0.001). In this review of a large multicenter database of surgically treated pediatric scoliosis, neuromuscular scoliosis had the highest morbidity, but relatively high complication rates occurred in all groups. These data may be useful for preoperative counseling and surgical decision-making in the treatment of pediatric scoliosis.

Distal Adding-On Phenomenon in Lenke 1A Scoliosis

Retrospective study. To identify risk factors for the presence of distal adding-on in Lenke 1A scoliosis and compare different treatment strategies. Distal adding-on is often accompanied by unsatisfactory clinical outcome and high risk of reoperation. However, very few studies have focused on distal adding-on and its attendant risk factors and optimal treatment strategies remain controversial. All surgically treated patients with adolescent idiopathic scoliosis were retrieved from a single institutional database. Inclusion criteria included: (1) Lenke 1A scoliosis patients treated with posterior pedicle screw-only constructs, (2) minimum 1-year radiographic follow-up. Distal adding-on was defined as a progressive increase in the number of vertebrae included distally within the primary curve combined with either an increase of more than 5 mm in deviation of the first vertebra below instrumentation from the center sacral vertical line (CSVL), or an increase of more than 5° in the angulation of the first disc below the instrumentation at 1 year follow-up. Wilcoxon rank sum test, Fisher exact test, and Spearman correlation test were used to identify the risk factors for adding-on. A multiple logistic regression model was built to identify independent predictive factor(s). Risk factors included: (1) age at surgery; (2) preoperative Cobb angle; (3) correction rate; (4) the gap difference of stable vertebra-lowest instrumented vertebra (SV-LIV), neutral vertebra-lowest instrumented vertebra (NV-LIV), and end vertebra-lowest instrumented vertebra (EV-LIV). Gap difference means, for example, if SV is at L2 and LIV is at Th12, then the difference of SV-LIV is 2; (5) the preoperative deviation of LIV+1 (the first vertebra below the instrumentation) from the CSVL (the vertical line that bisects proximal sacrum). Five methods for determining LIV were compared in both the adding-on group and no adding-on group. Out of the 278 patients reviewed, 45 met the inclusion criteria; 23 of these met the definition for distal adding-on, and were included in the adding-on group. The remaining 22 patients were included in the no adding-on group. The average follow-up was 3.6 years. Age, SV-LIV difference, EV-LIV difference, and LIV+1 deviation from CSVL were significantly different (P<0.05) between the two groups, and were also found to be significantly correlated with the presence of adding-on (P<0.05). Preoperative Cobb angle, correction rate, and NV-LIV difference were not found to be affiliated with the presence of adding-on. Multiple logistic regression results indicated that preoperative LIV+1 deviation from CSVL was an independent predictive factor. Among the five methods, choosing EV as LIV was nearly unable to prevent distal adding-on; choosing EV+1 as LIV resulted in fusing many more segments than necessary; only choosing DV as LIV showed satisfactory outcome from both perspectives. In Lenke 1A type scoliosis, the selection of LIV is highly correlated with the presence of adding-on; incidence increases dramatically when the preoperative LIV+1 deviation from CSVL is more than 10 mm. Choosing DV (the first vertebra in cephalad direction from sacrum with deviation from CSVL of more than 10 mm) as LIV may provide the best outcome as it not only prevents adding-on but also conserves more lumbar motion.

Analysis of posterior pedicle screw-only constructs in surgical treatment of adolescent idiopathic scoliosis with a minimum three-year follow-up

To evaluate clinical outcomes of a group of adolescent idiopathic scoliosis (AIS) patients undergoing posterior pedicle screw-only instrumentations. Between April 2002 and July 2006, 121 AIS patients (93 female and 28 male, average age at operation was 15.5 years which ranged from 10 to 20 years) received posterior pedicle screw-only instrumentation and fusion. All the patients were evaluated by the various-parameters measured in X-ray films before and after surgery, including Cobb angle on coronal plane, Cobb angle on sagittal plane, clavicle angle and shoulder height difference, lowest instrumented vertebrae (LIV) angulation, proximal junction kyphotic angle, the distances of central sacral vertical line (CSVL) to the LIV, to the apical vertebra and to the C(7) plumb line respectively. Complications were followed. An average of (11.0 + or - 1.5) levels was fused. An average coronal correction of proximal thoracic curve was 41.8%, of thoracic curve was 70.8%, of thoracolumbar/lumbar curves was 74.0%. No significant change was found in sagittal alignment. Shoulder balance and apex vertebral to central sacral line were restored well. There were no pseudoarthroses and loss of correction during the follow-ups. One adding-on, 4 proximal thoracic decompensation and 15 proximal junction kyphosis were found during the follow-ups. Posterior pedicle screw-only instrumentation and fusion has excellent radiographic and clinical results with minimal complications in the surgical treatment of AIS.

Revision Rates Following Primary Adult Spinal Deformity Surgery

Retrospective study. To analyze the prevalence of and reasons for unanticipated revision surgery in an adult spinal deformity population treated at one institution. No recent studies exist that analyze the rate or reason for unanticipated revision surgery for adult spinal deformity patients over a long period. All patients presenting for primary instrumented spinal fusion with a diagnosis of adult deformity at a single institution from 1985 to 2008 were reviewed using a prospectively acquired database. All surgical patients with instrumented fusion of > or =5 levels using hooks, hybrid, or screw-only constructs were identified. Patient charts and radiographs were reviewed to provide information as to the indication for initial and any subsequent reoperation. A total of 643 patients underwent primary instrumented fusion for a diagnosis of adult idiopathic scoliosis (n = 432), de novo degenerative scoliosis (n = 104), adult kyphotic disease (n = 63), or neuromuscular scoliosis (n = 45). The mean age was 37.9 years (range, 18-84). Mean follow-up for the entire cohort was 4.7 years, and 8.2 years for the subset of the cohort requiring reoperation (range, 1 month-22.3 years). A total of 58 of 643 patients (9.0%) underwent at least one revision surgery and 15 of 643 (2.3%) had more than one revision (mean 1.3; range, 1-3). The mean time to the first revision was 4.0 years (range, 1 week-19.7 years). The most common reasons for revision were pseudarthrosis (24/643 = 3.7%; 24/58 = 41.4%), curve progression (13/643 = 2.0%; 13/58 = 20.7%), infection (9/643 = 1.4%; 9/58 = 15.5%), and painful/prominent implants (4/643 = 0.6%; 4/58 = 6.9%). Uncommon reasons consisted of adjacent segment degeneration (3), implant failure (3), neurologic deficit (1), and coronal imbalance (1). Revision rates over the follow-up period were: 0 to 2 years (26/58 = 44.8%), 2 to 5 years (17/58 = 29.3%), 5 to 10 years (7/58 = 12.1%), >10 years (8/58 = 13.8%). Repeat surgical intervention following definitive spinal instrumented fusion for primary adult deformity performed at a single institution demonstrated a relatively low rate of 9.0%. The most common reasons for revision were predictable and included pseudarthrosis, proximal or distal curve progression, and infection.

Pedicle Screw-only Constructs With Lumbar or Pelvic Fixation for Spinal Stabilization in Patients With Duchenne Muscular Dystrophy

Retrospective case study. We present a retrospective clinical study of 36 patients of Duchenne muscular dystrophy (DMD) treated for correction of scoliosis with pedicle screw-only constructs with the objective to analyze our technique, correction and maintenance of spinal and pelvic deformity, spinal fusion, the complications we encountered, and the adequacy of lumbar fixation. Pedicle screw constructs have shown better deformity correction and maintenance as compared with other methods of instrumentation in adolescent idiopathic scoliosis. There are very few reports of pedicle screw-only constructs for DMD patients. Thirty-six patients were followed up for an average period of 37.75 months (min 24 mo). All patients were instrumented from T2, T3, or T4 to L5 and all levels were instrumented. Pelvic fixation was performed only if the pelvic tilt was more than 15 degrees (10 patients). Cobb angle improved 65% (P<0.001) after surgery from a mean preoperative value of 71 degrees to an average postoperative value of 25.5 degrees. Balanced sitting posture was obtained in all patients. The lumbar lordosis improved significantly (P<0.0001) from an average preoperative value of -21.4 degrees to a mean immediate postoperative value of 23.7 degrees and to 19.5 degrees at final follow-up. In patients where pelvic fixation was performed, pelvic tilt improved 62% (P<0.0001) from an average of 25.8 degrees preoperatively to 9 degrees postoperatively to 11 degrees at final follow-up. In patients where pelvic fixation was not performed, the pelvic obliquity also improved from 10.5 degrees preoperatively to 5.8 degrees postoperatively (41.5% correction) and 8.5 degrees at final follow-up (4.2% correction). Pedicle screw-only constructs provide good stability allowing better correction and maintenance of coronal and lumbar deformities, obtaining good sitting balance, and mobilizing patients early after surgery. Longer follow-up is required to adequately comment on the need for pelvic stabilization.

Surgical Correction and Fusion Using Posterior-Only Pedicle Screw Construct for Neuropathic Scoliosis in Patients With Cerebral Palsy

It is a retrospective study of 52 neuromuscular scoliosis patients with cerebral palsy (CP). To determine the effectiveness and amount of correction using posterior-only pedicle screw construct. Although there have been many reports in literature supporting the use of pedicle screw-only constructs for the correction of adolescent idiopathic scoliosis, similar studies have not been reported in patients with CP. We retrospectively evaluated outcomes of 52 neuropathic scoliosis patients (28 males and 24 females) with CP over minimum 2 years of follow-up. All patients underwent pedicle screw fixation without any anterior procedure for the correction. Pelvic fixation was done in 10 patients who had pelvis obliquity more than 15 degrees . All coronal and sagittal parameters were noted after surgery and at final follow-up. Patient's functional outcome was measured using modified Rancho Los Amigos Hospital system criteria. Complications were recorded from record sheets and any change in the ambulatory status was also recorded. Mean age was 22 years at the time of operation and average follow-up was 36.1 month. Cobb's angle was improved to 62.9% (P < 0.0001) from 76.8 degrees to 30.1 degrees after surgery and 31.5 degrees at final follow-up. This correction of scoliosis (41% approximately 92%) was found to be statistically significant (P < 0.0001). Overall correction in pelvic obliquity was 56.2% from 9.2 degrees before surgery to 4.0 degrees after surgery which was 43.1% at final follow-up to 5.2 degrees. Twenty-one patients (42%) improved their functional ability by grade 1 with 2 patients by grade 2. After the operation parent or caretakers of patients exhibited better sitting balance and nursing care. There were 32% complications in the series major being pulmonary. There were 2 perioperative deaths and 1 patient developed neurologic deficit due to screw impingement in canal, which was resolved after removal. We reported satisfactory coronal and sagittal correction with posterior-only pedicle screw fixation without higher complication rate in CP patients. Further long-term study is recommended to evaluate the success of pedicle screw in this population.

Posterior fusion only for thoracic adolescent idiopathic scoliosis of more than 80°: pedicle screws versus hybrid instrumentation

The treatment of thoracic adolescent idiopathic scoliosis (AIS) of more than 80 degrees traditionally consisted of a combined procedure, an anterior release performed through an open thoracotomy followed by a posterior fusion. Recently, some studies have reassessed the role of posterior fusion only as treatment for severe thoracic AIS; the correction rate of the thoracic curves was comparable to most series of combined anterior and posterior surgery, with shorter surgery time and without the negative effect on pulmonary function of anterior transthoracic exposure. Compared with other studies published so far on the use of posterior fusion alone for severe thoracic AIS, the present study examines a larger group of patients (52 cases) reviewed at a longer follow-up (average 6.7 years, range 4.5-8.5 years). The aim of the study was to evaluate the clinical and radiographic outcome of surgical treatment for severe thoracic (>80 degrees) AIS treated with posterior spinal fusion alone, and compare comprehensively the results of posterior fusion with a hybrid construct (proximal hooks and distal pedicle screws) versus a pedicle screw instrumentation. All patients (n = 52) with main thoracic AIS curves greater than 80 degrees (Lenke type 1, 2, 3, and 4), surgically treated between 1996 and 2000 at one institution, by posterior spinal fusion either with hybrid instrumentation (PSF-H group; n = 27 patients), or with pedicle screw-only construct (PSF-S group; n = 25 patients) were reviewed. There were no differences between the two groups in terms of age, Risser's sign, Cobb preoperative main thoracic (MT) curve magnitude (PSF-H: 92 degrees vs. PSF-S: 88 degrees), or flexibility on bending films (PSF-H: 27% vs. PSF-S: 25%). Statistical analysis was performed using the t test (paired and unpaired), Wilcoxon test for non-parametric paired analysis, and the Mann-Whitney test for non-parametric unpaired analysis. At the last follow-up, the PSF-S group, when compared to the PSF-H group had a final MT correction rate of 52.4 versus 44.52% (P = 0.001), with a loss of -1.9 degrees versus -11.3 degrees (P = 0.0005), a TL/L correction of 50 versus 43% (ns), a greater correction of the lowest instrumented vertebra translation (-1.00 vs. -0.54 cm; P = 0.04), and tilt (-19 degrees vs. -10 degrees; P = 0.005) on the coronal plane. There were no statistically significant differences in sagittal and global coronal alignment between the two groups (C7-S1 offset: PSF-H = 0.5 cm vs. PSF-S = 0 cm). In the hybrid series (27 patients) surgery-related complications necessitated three revision surgeries, whereas in the screw group (25 patients) one revision surgery was performed. No neurological complications or deep wound infection occurred in this series. In conclusion, posterior spinal fusion for severe thoracic AIS with pedicle screws only, when compared to hybrid construct, allowed a greater coronal correction of both main thoracic and secondary lumbar curves, less loss of the postoperative correction achieved, and fewer revision surgeries. Posterior-only fusion with pedicle screws enabled a good and stable correction of severe scoliosis. However, severe curves may be amenable to hybrid instrumentation that produced analogous results to the screws-only constructs concerning patient satisfaction; at the latest follow-up, SRS-30 and SF-36 scores did not show any statistical differences between the two groups.