Changes in gait patterns after anterior cruciate ligament reconstruction in children.

PURPOSE: Anterior cruciate ligament reconstruction (ACLR) in children is indicated to reduce recurrent knee instability and further damage to the joint. Postoperative modified gait pattern was reported in the adult population after ACLR. The aim of this study was to analyse gait abnormalities, and especially knee and ankle adaptations during gait in children after ACLR. METHODS: A prospective study was performed between 2018 and 2022 on 50 children, aged nine to 15 years with unilateral ACL deficiency. Changes in gait pattern were evaluated by gait analysis before surgery and at the latest follow-up of 24 months. Kinematic data of ACL-deficient limb were compared to contralateral limb and to those of a matched control group of healthy children. RESULTS: Compared to control group, knee flexion was decreased for both ACL-deficient and contralateral knee before surgery. Decreased knee flexion during gait cycle persisted at latest follow-up. Ankle kinematics showed decreased dorsal flexion for both ACL-deficient and contralateral limb before surgery. At latest follow-up, ankle kinematics were modified for ACL-reconstructed limbs only at initial contact and showed no significant difference for contralateral limb compared to the control group. CONCLUSION: In children with ACL injury, abnormal gait patterns persist two years after ligament reconstruction, in spite of extensive rehabilitation and no clinical complaints. These findings might guide neuromuscular training to improve clinical outcomes and reduce the rerupture rate.

Influence of a posteromedial meniscocapsular injury on the knee anterior laxity. A cadaveric study.

PURPOSE: The number of anterior cruciate ligament (ACL) injuries has considerably increased in the recent years, especially in young adults and adolescents. Associated meniscal tears increase anterior and rotary laxity. Posterior peripheral meniscocapsular tear of medial meniscus is also called ramp lesion. Prevalence of 9% to 17% in adults and up to 23% in pediatric population has been reported. The aim of this study was to determine anterior laxity of cadaveric ACL-deficient knees with several size of ramp lesions. METHODS: Fresh cadaveric knees were explored. Major osteoarthritis and/or ACL and meniscal tears on arthroscopy were exclusion criteria. Mean age at death was 86 years old. Dynamic laximetry with GNRB® device was made in several conditions: Knee prior to any procedure, after arthroscopic exploration, after ACL section, and then after increasing sizes of ramp lesions up to 30 mm. Anteroposterior laxity was measured with 2 loading forces successively (134N and 200N). RESULTS: After ACL section only, tibiofemoral joint anterior laxity was significantly increased. Mean increase was 156% regardless of the loading force. No statistical laxity difference was found between knees with ACL section only and knees with ACL and meniscal section for any size of ramp lesions. Increasing size of ramp lesion was not correlated with increasing of laxity. CONCLUSION: We could not find a threshold size of ramp lesion which increases knee anterior laxity. We were not able to determine a threshold recommending a ramp lesion repair.

Clinical predictive model of lumbar curve Cobb angle below selective fusion for thoracic adolescent idiopathic scoliosis: a longitudinal multicenter descriptive study.

PURPOSE: To implement a clinically applicable, predictive model for the lumbar Cobb angle below a selective thoracic fusion in adolescent idiopathic scoliosis. METHODS: A series of 146 adolescents with Lenke 1 or 2 idiopathic scoliosis, surgically treated with posterior selective fusion, and minimum follow-up of 5 years (average 7) was analyzed. The cohort was divided in 2 groups: if lumbar Cobb angle at last follow-up was, respectively, ≥ or < 10°. A logistic regression-based prediction model (PredictMed) was implemented to identify variables associated with the group ≥ 10°. The guidelines of the TRIPOD statement were followed. RESULTS: Mean Cobb angle of thoracic main curve was 56° preoperatively and 25° at last follow-up. Mean lumbar Cobb angle was 33° (20; 59) preoperatively and 11° (0; 35) at last follow-up. 53 patients were in group ≥ 10°. The 2 groups had similar demographics, flexibility of both main and lumbar curves, and magnitude of the preoperative main curve, p > 0.1. From univariate analysis, mean magnitude of preoperative lumbar curves (35° vs. 30°), mean correction of main curve (65% vs. 58%), mean ratio of main curve/distal curve (1.9 vs. 1.6) and distribution of lumbar modifiers were statistically different between groups (p < 0.05). PredictMed identified the following variables significantly associated with the group ≥ 10°: main curve % correction at last follow-up (p = 0.01) and distal curve angle (p = 0.04) with a prediction accuracy of 71%. CONCLUSION: The main modifiable factor influencing uninstrumented lumbar curve was the correction of main curve. The clinical model PredictMed showed an accuracy of 71% in prediction of lumbar Cobb angle ≥ 10° at last follow-up. LEVEL OF EVIDENCE IV: Longitudinal comparative study.

Correction of hypokyphosis in thoracic adolescent idiopathic scoliosis using sublaminar bands: a 3D multicenter study.

INTRODUCTION: The comparison of implants and correction methods remain controversial in AIS. Excellent frontal and axial correction rates have been reported with all-screw constructs, but at the expense of sagittal alignment, which has a tendency to flatten postoperatively. Posteromedial translation using hybrid constructs seems to preserve and improve thoracic kyphosis (TK), but no series exist to date with a significant number of hypokyphotic patients. In addition, the measures of TK in 2D are often wrong in severe AIS due to axial rotation. The goals of this study were therefore to analyze the 3D radiological outcomes of a group of hypokyphotic AIS patients operated with sublaminar bands. METHODS: 35 consecutive AIS hypokyphotic patients (T4T12 <15°) operated in three centers were included, with a minimum 2-year follow-up. The surgical technique was similar in all centers, associating lumbar pedicle screws and thoracic sublaminar bands. Posteromedial translation was the main correction technique, and no patient underwent prior anterior release. 3D spinal reconstructions were performed preoperatively, postoperatively and at the latest follow-up by an independent observer using SterEOS (EOS imaging, Paris, France), and 2D and 3D measurements were compared. In addition, a new 3D parameter [sagittal shift of the apical vertebra (SSAV)], reflecting the translation of the apical vertebra of the main curve in the patient sagittal plane, was described and reported. RESULTS: The age of the cohort was 16 years and the number of sublaminar bands used for correction averaged 6 (±1.5). T1T12 and T4T12 sagittal Cobb angles appeared to be overestimated on 2D postoperatively (3°, p = 0.002 and 4°, p < 0.001, respectively). Hence, only 3D measurements were kept for the quantitative analysis of the postoperative correction. T4T12 TK significantly increased after surgery (average 8° ± 7°, p < 0.001), but 11 patients (31.4%) remained hypokyphotic. Seven out of the eight patients (87.5%) who presented a thoracic lordosis (i.e., T4T12 <0°) preoperatively were corrected after surgery (mean gain 16° ± 4°). A posterior shift (positive SSAV) of the apical vertebra was reported in 24 patients (68.6%). In this subgroup, the mean SSAV was +2 cm (±1). Good correlation was found between the SSAV and the postoperative change in 3D T4T12 kyphosis (r = 0.62). CONCLUSION: Measures in 2D tend to overestimate sagittal alignment and are not sufficient to evaluate postoperative correction. SSAV is a new 3D parameter reflecting the TK change that needs to be further investigated and used in the future. This series confirms that sublaminar bands should be considered in hypokyphotic patients, since thoracic sagittal alignment was restored in 68.6% of the cases.

Proximal junctional kyphosis in thoracic adolescent idiopathic scoliosis: risk factors and compensatory mechanisms in a multicenter national cohort.

INTRODUCTION: Proximal junctional kyphosis (PJK) is a frequent complication, up to 46%, in adolescent idiopathic scoliosis surgical treatment (AIS). Several risk factors have been evoked but remain controversial. The purpose of this study was to analyze the incidence of PJK in a multicenter cohort of AIS patient and to determine risk factor for PJK. MATERIALS AND METHODS: Lenke I and II AIS patients operated between 2011 and 2015 (minimum of 2-years follow-up) were included. On fullspine X-rays, coronal and sagittal radiographic parameters were measured preoperatively, postoperatively and at final follow-up. Occurrence of radiological PJK corresponding to a 10° increase in the sagittal Cobb angle, measured between the upper instrumented vertebra (UIV) and UIV + 2, between postoperative and 2-years follow-up X-rays, was reported. RESULTS: Among the 365 patients included, 15.6% (n = 57) developed a PJK and only 10 patients required a revision surgery. Preoperatively, PJK patients had significantly larger pelvic incidence (57° ± 13° vs. 51° ± 12°), larger lumbar lordosis (LL) (63° ± 12° vs. 57° ± 11°) and bigger C7 slope. Postoperatively (3 months), in the non-PJK group, thoracic kyphosis (TK) was increased and LL was not significantly different. However, postoperatively, in the PJK group, no significant change was observed in TK, whereas C7 slope decreased and LL significantly increased. There was also a postoperative change in inflection point which was located at a more proximal level in the PJK group. Between postoperative time and final follow-up, TK and LL significantly increased in the PJK group. CONCLUSION: PJK is a frequent complication in thoracic AIS, occurring 16%, but remains often asymptomatic (less than 3% of revisions in the entire cohort). An interesting finding is that patients with high pelvic incidence and consequently large LL and TK were more at risk of PJK. As demonstrated in ASD, one of the causes of PJK might be postoperative posterior imbalance that can be due to increased LL, insufficient TK or inflection point shift during surgery. These slides can be retrieved under Electronic Supplementary Material.

Magnetically controlled growing rod in early onset scoliosis: a 30-case multicenter study.

PURPOSE: Preliminary results of magnetically controlled growing rods (MCGR) are encouraging. However, only short case series of MCGR for the treatment of early onset scoliosis (EOS) have been reported. Our aim was to evaluate its effectiveness and complications. METHODS: We report a 30-case retrospective, consecutive, multicenter series of MCGR. Effectiveness was judged upon: deformity correction and difficulties to achieve desired distraction. Secondary endpoints included complications and revision surgeries. RESULTS: Median age at surgery was 9.1 years (5-13). Mean follow-up was 18.4 months (12-33.9). Mean Cobb angle was 66° preoperatively and 44° at latest follow-up. MCGR has avoided an average of 2.03 scheduled surgical procedures per patient compared to traditional growing rod (GR). The intended total length gain was 40.1 mm per patient (5-140) and the total measured length gain was 21.9 mm (45.5% discrepancy). There were 24 complications: 7 proximal pull-outs of the hooks, 3 rod breakages, 6 failures of the lengthening of which 4 complete blockages and 2 complete blockages followed by backtracking, 1 proximal junctional kyphosis, 1 wound dehiscence, 1 superficial infection, 1 deep infection requiring implant removal, 1 pulmonary embolism, 1 pulmonary insufficiency, 1 secondary lumbar scoliosis, and 1 painful outpatient distraction. Eight patients had a gradual loss of effectiveness of distractions. There were 13 revision surgeries in 9 patients. CONCLUSIONS: MCGR provides satisfactory deformity correction and avoids repeated surgical procedures for lengthening. However, it has substantial complication rate. Although less frequent than in GR, the law of diminishing returns also applies to MCGR.

Relationship between tibial spine size and the occurrence of osteochondritis dissecans: an argument in favour of the impingement theory.

PURPOSE: Pathophysiology of osteochondritis dissecans (OCD) of the medial femoral condyle remains uncertain. Specifically, the relationship between the size of the anterior tibial spine (ATS) and the presence of OCD has not been explored. The purpose of this study was to evaluate the relationship between ATS size and the occurrence of OCD. METHODS: Seventy-nine children between 8 and 17 years of age were included in two groups: OCD (n = 37) and control (n = 42). The groups were matched in terms of age, gender, BMI and weight. Two independent observers performed an MRI analysis of the size of the tibial spine and intercondylar notch relative to the size of the respective epiphyses. For this study, the "S ratio" was calculated by dividing the height of the tibial spine by the height of the tibial epiphysis. The "N ratio" was calculated by dividing the height of the notch by the height of the femoral epiphysis. These two ratios for both groups were compared using Student's t test. RESULTS: The mean value of the S ratio in the OCD group was 0.39 ± 0.06; the mean value of the S ratio in the control group was 0.32 ± 0.03 (P = 0.004). The mean value of the N ratio in the OCD group was 0.70 ± 0.08; the mean value of the N ratio in the control group was 0.70 ± 0.07 (n.s.). CONCLUSION: This study's findings confirm our hypothesis that patients with OCD have a more prominent tibial spine than in patients without OCD. LEVEL OF EVIDENCE: IV.

Triple osteotomy of the pelvis for Legg-Calve-Perthes disease: a mean fifteen year follow-up.

PURPOSE: This study presents the results of a prospective consecutive cohort of patients with Legg-Calvé-Perthes disease (LCPD) operated with triple osteotomy of the pelvis (TOP) between 1989 and 2005. We attempted to determine whether the results of TOP remain stable with time and consequently lower the risk of subsequent osteoarthritis. The primary study aims were to determine the maintenance of head coverage and joint congruity, and functional outcomes of this surgery. METHODS: Forty-five patients with a mean follow-up of 15.2 years (range eight to 24) were included. RESULTS: At latest follow-up, two patients were lost to follow-up, and two required a surgical reoperation. Cumulative maintenance of head coverage and joint congruity rate for all TOP was 84.6 % (95 % CI: 82.3-90.6 %) at 15 years. Factors significantly associated with poor long-term results were the age at diagnosis and Greene index. CONCLUSION: TOP in LCPD provides satisfactory and reproducible long-term clinical results.

Low-dose biplanar radiography can be used in children and adolescents to accurately assess femoral and tibial torsion and greatly reduce irradiation.

PURPOSE: To evaluate in children the agreement between femoral and tibial torsion measurements obtained with low-dose biplanar radiography (LDBR) and CT, and to study dose reduction ratio between these two techniques both in vitro and in vivo. MATERIALS AND METHODS: Thirty children with lower limb torsion abnormalities were included in a prospective study. Biplanar radiographs and CTs were performed for measurements of lower limb torsion on each patient. Values were compared using Bland-Altman plots. Interreader and intrareader agreements were evaluated by intraclass correlation coefficients. Comparative dosimetric study was performed using an ionization chamber in a tissue-equivalent phantom, and with thermoluminescent dosimeters in 5 patients. RESULTS: Average differences between CT and LDBR measurements were -0.1° ±1.1 for femoral torsion and -0.7° ±1.4 for tibial torsion. Interreader agreement for LDBR measurements was very good for both femoral torsion (FT) (0.81) and tibial torsion (TT) (0.87). Intrareader agreement was excellent for FT (0.97) and TT (0.89). The ratio between CT scan dose and LDBR dose was 22 in vitro (absorbed dose) and 32 in vivo (skin dose). CONCLUSION: Lower limb torsion measurements obtained with LDBR are comparable to CT measurements in children and adolescents, with a considerably reduced radiation dose. KEY POINTS: • LDBR and CT lower-limb torsion measurements are comparable in children and adolescents. • LDBR considerably reduced radiation dose necessary for lower-limb torsion measurements. • LDBR can be used for evaluation of lower limb-torsion in orthopaediatric patients.

Vascularized tibial periosteal graft in complex cases of bone nonunion in children.

Bone nonunion in the pediatric population usually occurs in the context of highly unfavorable biological conditions. Recently, the vascularized fibular periosteal flap has been reported as a very effective procedure for treating this condition. Even though a vascularized tibial periosteal graft (VTPG) was described long ago and has been successfully employed in one adult case, there has been no other report published on the use of this technique. We report on the use of VTPG, pedicled in the anterior tibial vessels, for the treatment of two complex pediatric bone nonunion case: a recalcitrant supracondylar femoral pseudarthrosis secondary to an infection in an 11-year-old girl, and a tibial nonunion secondary to a failed bone defect reconstruction in a 12-year-old girl. Rapid healing was obtained in both cases. In the light of the data presented, we consider VTPG as a valuable surgical option for the treatment of complex bone nonunions in children.

Percutaneous correction of persistent severe metatarsus adductus in children.

BACKGROUND: Percutaneous techniques for the correction of foot deformities are gaining popularity in the adult population, but remain poorly explored in children. Of the several surgical techniques described to treat persistent severe metatarsus adductus (MA) deformity in children, neither was percutaneous. The purpose of the study was to describe a percutaneous technique for MA correction in children, to report the outcomes, and to discuss the advantages it offers. METHODS: We designed a prospective study on 34 consecutive feet with MA deformity from 26 children undergoing percutaneous correction. All operated feet had severe, rigid MA deformities, most of which were components of residual/recurrent clubfoot deformities. The mean age at surgery was 5.7 years and the mean follow-up was 55.2 months. For clinical evaluation, we used the bisector method; the first cuneometatarsal angle and metatarsal-metaphyseal angle measured in weight-bearing radiographs and AOFASf score were determined preoperatively and postoperatively. In unilateral cases, we used the contralateral foot measurements as control. The operating time and the hospitalization time were also recorded. The surgical technique consisted of performing the Cahuzac procedure for MA correction with a percutaneous approach. RESULTS: At the final follow-up all feet presented a normal heel bisector line. Radiologic parameters were normalized when compared with control feet. The mean surgical and hospitalization time was 14 minutes and 6 hours, respectively. Mean AOFAS score improved from 78 to 98. CONCLUSIONS: A minimally invasive percutaneous technique allowed a successful correction of MA deformity in children and resulted in a substantive decrease in both surgical and hospitalization time and better cosmetic results. LEVEL OF EVIDENCE: Level II.

Resection of calcaneonavicular coalition: Arthroscopic or open approach?

Purpose: Calcaneonavicular coalition accounts for more than half of all tarsal coalitions. Resection of calcaneonavicular coalition by an open approach is the standard treatment. Treatment of calcaneonavicular coalition by an arthroscopic approach appears promising. The objective of our study was to compare the clinical outcomes of calcaneonavicular coalition resection by open approach versus arthroscopic approach. Methods: A retrospective cohort study was conducted to evaluate 127 patients who underwent a resection of calcaneonavicular coalition from 2009 to 2017. Patients were divided into two groups according to whether an arthroscopic approach or an open approach was used. Demographics, operative parameters, and clinical outcomes (foot and ankle ability measure score, subjective score, and global ankle estimation) were assessed. Results: Arthroscopic approach was used for 81 patients and open approach for 46 patients. Treatment with arthroscopic approach resulted in a shorter hospital stay (2.6 ± 0.6 days vs 3.0 ± 0.7; p = 0.02) and a longer operative time (24.5 ± 8.1 min vs 20.5 ± 4.2; p < 0.01) than with open approach. The foot and ankle ability measure sports subscale scored significantly higher in the arthroscopic approach group (90.9 vs 77.3; p = 0.003). Revision rate was significantly higher in the arthroscopic approach group (12 (15%)) versus the open approach group (1 (2%)) (p = 0.024). Persistent symptoms (n = 12) were the main reason for revision. Conclusions: Arthroscopic treatment of calcaneonavicular coalition is associated with a higher revision rate than the open approach. Level of evidence: Level III-retrospective comparative study.

Does harvesting of the semitendinosus tendon really spare the gracilis in pediatric anterior cruciate ligament reconstruction?

Purpose: The use of isolated semitendinosus tendon for Anterior Cruciate Ligament Reconstruction bears several advantages and is popular worldwide. It assumes that the gracilis tendon is spared. The aim of the study was to measure the surface area of the gracilis tendon in children who had undergone arthroscopic reconstruction of the anterior cruciate ligament using a semitendinosus tendon graft. Our hypothesis was that the gracilis tendon may be unintentionally and iatrogenically sectioned due to the anatomical proximity and the small size of the patients. Methods: Fifty patients who had undergone a magnetic resonance imaging preoperatively and postoperatively at 1 year from the surgery and who had been operated between January 2017 and March 2019 were included in this prospective series. The surface area of the gracilis tendon was measured on fat-saturated T2-weighted axial views at the widest point of the medial epicondyle of the femur. Age, sex, body weight, and height were documented. Results: One hundred magnetic resonance imaging of 50 knees were reviewed, from 34 boys (68%) and 16 girls (32%). The mean age was 14.5 years (10-18). The gracilis was visualized in all cases at 1 year postoperatively. The average tendinous surface area of the gracilis before the surgical procedure was 7.13 mm2 versus 8.73 mm2 at 1 year, representing an increase of 1.6 mm2 (p = 0.0003). Conclusions: This study demonstrated that harvesting of the semitendinosus for the purpose of Anterior Cruciate Ligament Reconstruction was a safe technique that preserves the gracilis. Level of evidence: III.

Treatment of hallux valgus in children and adolescents.

Juvenile hallux valgus is one of the most common pathologies of the forefoot in children and adolescents. Nevertheless, its treatment is still controversial. This deformity has some distinct anatomical features, particularly a lateral tilt of the articular facet of the head of the first metatarsal and congenital metatarsus adductus, which often occur in combination. Some mediocre surgical treatment results can be explained by the lack of correction of all these factors when we approach the problem as we would in adults. A double osteotomy to correct the DMAA and varus of the first metatarsal is a good solution in most cases with satisfactory functional outcomes. A percutaneous approach seems efficient in the pediatric population, given that the periosteum and growth plates, which are very active in younger children, help the osteotomies to heal and remodel. Guided growth surgery - using this approach is a viable alternative in this age bracket. Finally, minimally invasive surgery for juvenile hallux valgus allows another surgery to be done on minimally or undamaged tissues if needed later on.

Bone Lengthening with a Motorized Intramedullary Nail in 34 Patients with Posttraumatic Limb Length Discrepancies.

The Fitbone® motorized nail system has been used to correct limb length discrepancies (LLD) for several years. This study focuses on its application in posttraumatic limb lengthening surgery, its outcome and challenges. MATERIALS AND METHODS: A prospective, single center study was conducted between 2010 and 2019 in patients treated with motorized lengthening nails. The inclusion criteria were symptomatic LLD of 20 mm or more. An imaging analysis was done using TraumaCad® software (Brainlab AG, Munich, Germany) to compare frontal alignment angles and limb length discrepancy (LLD) on preoperative and latest follow-up radiographs of the lower limbs. RESULTS: Thirty-four patients were included with a mean age of 28.8 ± 9.7 years, a mean follow-up of 27.8 ± 13 months and a mean hospital stay of 4.4 ± 1.7 days. The mean LLD was 44 ± 18 mm in 29 femoral and 32 ± 8 mm in 4 tibial cases, which was reduced to less than 10 mm in 25/34 (74%) patients. The mean healing index was 84.6 ± 62.5 days/cm for femurs and 92 ± 38.6 days/cm for tibias. The mean time to resume full weight-bearing without walking aids was 226 days ± 133. There was no significant difference between preoperative and final follow-up alignment angles and range of motion. The mechanical lateral distal femoral angle (mLDFA) was corrected in the subgroup of 10 LLD patients with varus deformity of the femur (preoperative 95.7° (±5.0) vs. postoperative 91.5° (±3.4), p = 0.008). According to Paley's classification, there were 14 problems, 10 obstacles and 2 complications. DISCUSSION: Six instances of locking screw pull out, often requiring reoperation, raise the question of whether a more systematic use of blocking screws that provide greater stability might be indicated. Lack of compliance can lead to poor outcomes, patient selection in posttraumatic LLD patients is therefore important. CONCLUSION: Limb lengthening with a motorized lengthening nail for posttraumatic LLD is a relatively safe and reliable procedure. Full patient compliance is crucial. In-depth knowledge of lengthening and deformity correction techniques is essential to prevent and manage complications.

Influence of the sublaminar band density in the treatment of Lenke 1 adolescent idiopathic scoliosis.

INTRODUCTION: Optimal pedicle screw density for the treatment of adolescent idiopathic scoliosis (AIS) remains unknown. It is not clear whether higher implant density results in better clinical outcomes. Large variability in implant density exists among hybrid or all screw constructs. Significant heterogeneity exists with respect to the number of sublaminar bands (SB) used, and the influence of SB density on curve correction in the treatment of AIS. HYPOTHESIS: We hypothesize that increased SB density does not improve sagittal or coronal plane curve correction. METHODS: A single-center, retrospective study of 131 consecutive patients (118 females) with Lenke 1 adolescent idiopathic scoliosis, all operated between 2012 and 2015 by two surgeons using identical surgical technique and type of instrumentation (SB hybrid instrumentation treatment). SB density was measured using the number of SB reported as well as the number of vertebrae instrumented. Radiographic measurements included preoperative thoracic curve flexibility, Cincinnati reduction index (CRI), and postoperative thoracic Cobb (POCC) and kyphosis (POKC) angle correction measured on immediate postoperative radiographs and at 2 years postoperatively. RESULTS: Median patient age was 15.6 years (IQR, 12-18). The median SB density was 0.4 (IQR 0.4-0.5). No statistically significant correlation was identified between SB density and CRI (p=0.71), POCC (p=0.55), or POKC (p=0.61) at 2-years postoperatively. Preoperative curve flexibility was found to have significant effect both on immediate (r=-3.02, p<0.001) and 2-year (r=-2.69, p<0.001). DISCUSSION: SB utilized as a part of a hybrid construct for patients with flexible Lenke I AIS achieve satisfactory deformity correction regardless of SBd. The use of low SB density is appropriate for a subset of patients with flexible Lenke 1 adolescent idiopathic scoliosis.

Hypophosphatasia may lead to bone fragility: don't miss it.

Hypophosphatasia is an inheritable disorder characterised by defective bone mineralisation due to the impaired activity of tissue-non-specific alkaline phosphatase (AP). Clinical presentation ranges from stillbirth without mineralised bone to pathological fractures in late adulthood. During childhood, the main manifestations include rickets, growth delay and dental problems. Fractures and bone pain usually characterise the adult form. A 9-year-old girl was referred for repetitive fractures after minimal trauma. She had normal growth, normal sclerae, no rickets and minimal dental abnormalities. Her sister had also presented fractures. The proband, her sister and mother had low total and bone-specific AP levels and E435K mutation in exon 12 of the liver/bone/kidney AP gene. Low AP levels must lead to genetic analysis. Bone fragility and repetitive fractures may be symptoms of hypophosphatasia in childhood, which must not be neglected. Associated factors such as vitamin D or calcium deficiency must be prevented. In conclusion, hypophosphatasia must not be forgotten as an aetiological factor of repetitive fractures or bone pain in children and AP activity should be checked accurately.

A measurement technique to evaluate the macroscopic permeability of the vertebral end-plate.

The remodelling response of vertebral segments in idiopathic scoliosis or disc degeneration, shows a modification of the disc hydration. The investigation of mass transport between the disc and the vertebral body is relevant to understanding the normal and pathological behaviour of the spine. The measurement method we adopted, to derive the macroscopic permeability of the vertebral end-plate, used the relaxation pressure due to a transient-flow rate into the biological structure. Our approach mimicked the in vivo conditions of mass transfer between the disc and the vertebral bodies. It minimized the flow-induced matrix compaction and it allowed the boundary conditions of the specimen to be controlled. We proposed a specific theoretical method and an associated device according to poroelastic theory. A preliminary evaluation with a controlled porous medium, preceded a pilot study in an animal model (lumbar L(4)-L(5) segment of a 4 months old female pig). The macroscopic permeability of multilayered cylindrical specimens including the trabecular bone, subchondral bone and cartilage end-plate was measured, using a 'cartilage-towards-bone' fluid flow direction. A histologic evaluation completed the biomechanical approach. Results showed that the central zone was more permeable than the periphery and this concurred with qualitative studies from the literature.

Paper #12: Effectiveness of Bracing Alone in Idiopathic EOS.

We hypothesized that bracing alone was an adequate treatment for idiopathic EOS and was as effective as serial casting in most cases. This retrospective, single Institution series demonstrates this is a valid alternative under close monitoring.