Heterotopic Ossification of Bilateral Hips Post-COVID-19 and Prolonged Immobilization: A Case Report.

CASE: A 43-year-old healthy man developed hip pain post-coronavirus disease 2019 (COVID-19) immobilization. Imaging confirmed bilateral bridging heterotopic ossification (HO) of the hips, Brooker Class IV. Bilateral HO caused functional arthrodesis (45° flexion: -20° internal rotation). Bilateral HO resection resulted in almost full mobility at 1-year follow-up (90° flexion; 30° internal rotation). CONCLUSION: Many cases of HO after immobilization for COVID-19 have been reported, but as far as we know, this is the first case report describing surgical intervention as an adequate treatment option for severe restricted mobility caused by HO due to COVID-19-induced prolonged immobilization. Caution and preoperative 3D planning are recommended of HO formation near neurovascular structures.

Systematic review of machine-learning models in orthopaedic trauma.

Aims: Machine-learning (ML) prediction models in orthopaedic trauma hold great promise in assisting clinicians in various tasks, such as personalized risk stratification. However, an overview of current applications and critical appraisal to peer-reviewed guidelines is lacking. The objectives of this study are to 1) provide an overview of current ML prediction models in orthopaedic trauma; 2) evaluate the completeness of reporting following the Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) statement; and 3) assess the risk of bias following the Prediction model Risk Of Bias Assessment Tool (PROBAST) tool. Methods: A systematic search screening 3,252 studies identified 45 ML-based prediction models in orthopaedic trauma up to January 2023. The TRIPOD statement assessed transparent reporting and the PROBAST tool the risk of bias. Results: A total of 40 studies reported on training and internal validation; four studies performed both development and external validation, and one study performed only external validation. The most commonly reported outcomes were mortality (33%, 15/45) and length of hospital stay (9%, 4/45), and the majority of prediction models were developed in the hip fracture population (60%, 27/45). The overall median completeness for the TRIPOD statement was 62% (interquartile range 30 to 81%). The overall risk of bias in the PROBAST tool was low in 24% (11/45), high in 69% (31/45), and unclear in 7% (3/45) of the studies. High risk of bias was mainly due to analysis domain concerns including small datasets with low number of outcomes, complete-case analysis in case of missing data, and no reporting of performance measures. Conclusion: The results of this study showed that despite a myriad of potential clinically useful applications, a substantial part of ML studies in orthopaedic trauma lack transparent reporting, and are at high risk of bias. These problems must be resolved by following established guidelines to instil confidence in ML models among patients and clinicians. Otherwise, there will remain a sizeable gap between the development of ML prediction models and their clinical application in our day-to-day orthopaedic trauma practice.

A Prospective Cohort Study on Accuracy of Dorsal Tangential Views to Avoid Screw Penetration With Volar Plating of Distal Radius Fractures.

OBJECTIVE: To assess diagnostic performance of dorsal tangential views (DTVs) to detect dorsal screw protrusion in clinical practice. DESIGN: Prospective cohort study. SETTING: Level-1 trauma center. PATIENTS: Fifty consecutive patients undergoing volar plating for 50 distal radius fractures were prospectively included. INTERVENTION: Fluoroscopic DTVs were routinely obtained, and screw revision was documented. Multiplanar reconstructions of postoperative CTs allowed for detection and quantification of dorsal screw penetration using reproducible measuring techniques. MAIN OUTCOME MEASUREMENTS: Diagnostic performance (sensitivity, negative predictive value, positive predictive value, and accuracy) of DTV. RESULTS: Intraoperatively, in 16 of 50 patients (32%), screws were revised based on DTV, with 13 of 218 screws (6.0%) being revised due to dorsal prominence. One screw was changed because DTV showed it was in the distal radioulnar joint. Postoperatively, in 10 patients (20%), the computed tomography revealed 12 additional screws penetrating ≥1 mm with an average of 1.8 mm (range 1.0-4.5 mm). DTV had a sensitivity of 52%, a negative predictive value of 95%, and accuracy of 95%. No ≥1-mm protruding screw remained in the third compartment. CONCLUSIONS: In one-third of our patients, the incidence of protruding screws that can cause iatrogenic extensor tendon rupture was reduced by obtaining additional DTVs. Although DTV reduces the incidence of dorsal screw penetration considerably, this study reveals limited sensitivity. Therefore, one should keep in mind that dorsal screw penetration may go unnoticed on DTVs, and proper surgical technique remains paramount of DTV. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Do 3-D Printed Handheld Models Improve Surgeon Reliability for Recognition of Intraarticular Distal Radius Fracture Characteristics?

BACKGROUND: For fracture care, radiographs and two-dimensional (2-D) and three-dimensional (3-D) CT are primarily used for preoperative planning and postoperative evaluation. Intraarticular distal radius fractures are technically challenging to treat, and meticulous preoperative planning is paramount to improve the patient's outcome. Three-dimensionally printed handheld models might improve the surgeon's interpretation of specific fracture characteristics and patterns preoperatively and could therefore be clinically valuable; however, the additional value of 3-D printed handheld models for fractures of the distal radius, a high-volume and commonly complex fracture due to its intraarticular configuration, has yet to be determined. QUESTIONS/PURPOSES: (1) Does the reliability of assessing specific fracture characteristics that guide surgical decision-making for distal radius fractures improve with 3-D printed handheld models? (2) Does surgeon agreement on the overall fracture classification improve with 3-D printed handheld models? (3) Does the surgeon's confidence improve when assessing the overall fracture configuration with an additional 3-D model? METHODS: We consecutively included 20 intraarticular distal radius fractures treated at a Level 1 trauma center between May 2018 and November 2018. Ten surgeons evaluated the presence or absence of specific fracture characteristics (volar rim fracture, die punch, volar lunate facet, dorsal comminution, step-off > 2 mm, and gap > 2 mm), fracture classification according to the AO/Orthopaedic Trauma Association (OTA) classification scheme, and their confidence in assessing the overall fracture according to the classification scheme, rated on a scale from 0 to 10 (0 = not at all confident to 10 = very confident). Of 10 participants regularly treating distal radius fractures, seven were orthopaedic trauma surgeons and three upper limb surgeons with experience levels ranging from 1 to 25 years after completion of residency training. Fractures were assessed twice, with 1 month between each assessment. Initially, fractures were assessed using radiographs and 2-D and 3-D CT images (conventional assessment); the second time, the evaluation was based on radiographs and 2-D and 3-D CT images with an additional 3-D handheld model (3-D printed handheld model assessment). On both occasions, fracture characteristics were evaluated upon a surgeon's own interpretation, without specific instruction before assessment. We provided a sheet demonstrating the AO/OTA classification scheme before evaluation on each session. Multi-rater Fleiss's kappa was used to determine intersurgeon reliability for assessing fracture characteristics and classification. Confidence regarding assessment of the overall fracture classification was assessed using a paired t-test. RESULTS: We found that 3-D printed models of intraarticular distal radius fractures led to no change in kappa values for the reliability of all characteristics: volar rim (conventional kappa 0.19 [95% CI 0.06 to 0.32], kappa for 3-D handheld model 0.23 [95% CI 0.11 to 0.36], difference of kappas 0.04 [95% CI -0.14 to 0.22]; p = 0.66), die punch (conventional kappa 0.38 [95% CI 0.15 to 0.61], kappa for 3-D handheld model 0.50 [95% CI 0.23 to 0.78], difference of kappas 0.12 [95% CI -0.23 to 0.47]; p = 0.52), volar lunate facet (conventional kappa 0.31 [95% CI 0.14 to 0.49], kappa for 3-D handheld model 0.48 [95% CI 0.23 to 0.72], difference of kappas 0.17 [95% CI -0.12 to 0.46]; p = 0.26), dorsal comminution (conventional kappa 0.36 [95% CI 0.13 to 0.58], kappa for 3-D handheld model 0.31 [95% CI 0.11 to 0.51], difference of kappas -0.05 [95% CI -0.34 to 0.24]; p = 0.74), step-off > 2 mm (conventional kappa 0.55 [95% CI 0.29 to 0.82], kappa for 3-D handheld model 0.58 [95% CI 0.31 to 0.85], difference of kappas 0.03 [95% CI -0.34 to 0.40]; p = 0.87), gap > 2 mm (conventional kappa 0.59 [95% CI 0.39 to 0.79], kappa for 3-D handheld model 0.69 [95% CI 0.50 to 0.89], difference of kappas 0.10 [95% CI -0.17 to 0.37]; p = 0.48). Although there appeared to be categorical improvement in kappa values for some fracture characteristics, overlapping CIs indicated no change. Fracture classification did not improve (conventional diagnostics: kappa 0.27 [95% CI 0.14 to 0.39], conventional diagnostics with an additional 3-D handheld model: kappa 0.25 [95% CI 0.15 to 0.35], difference of kappas: -0.02 [95% CI -0.18 to 0.14]; p = 0.81). There was no improvement in self-assessed confidence in terms of assessment of overall fracture configuration when a 3-D model was added to the evaluation process (conventional diagnostics 7.8 [SD 0.79 {95% CI 7.2 to 8.3}], 3-D handheld model 8.5 [SD 0.71 {95% CI 8.0 to 9.0}], difference of score: 0.7 [95% CI -1.69 to 0.16], p = 0.09). CONCLUSIONS: Intersurgeon reliability for evaluating the characteristics of and classifying intraarticular distal radius fractures did not improve with an additional 3-D model. Further studies should evaluate the added value of 3-D printed handheld models for teaching surgical residents and medical trainees to define the future role of 3-D printing in caring for fractures of the distal radius. LEVEL OF EVIDENCE: Level II, diagnostic study.

PtII -Catalyzed Hydroxylation of Terminal Aliphatic C(sp3 )-H Bonds with Molecular Oxygen.

The practical application of Shilov-type Pt catalysis to the selective hydroxylation of terminal aliphatic C-H bonds remains a formidable challenge, due to difficulties in replacing PtIV with a more economically viable oxidant, particularly O2 . We report the potential of employing FeCl2 as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O2 in the Pt reoxidation. For the selective conversion of butyric acid to γ-hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O2 in comparison to current state-of-the-art systems (TON<10). In this regard, essential reaction parameters affecting the overall activity were identified, along with specific additives to attain catalyst stability at longer reaction times. Notably, deactivation by reduction to Pt0 was prevented by the addition of monodentate pyridine derivatives, such as 2-fluoropyridine, but also by introducing varying partial pressures of N2 in the gaseous atmosphere. Finally, stability tests revealed the involvement of PtII and FeCl2 in catalyzing the non-selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C-H bonds with O2 is presented.

Do Stem Design and Surgical Approach Influence Early Aseptic Loosening in Cementless THA?

BACKGROUND: Some studies have revealed an increased risk of early aseptic loosening of cementless stems in THA when inserted through an anterior or anterolateral approach compared with a posterior approach, whereas approach does not appear to be a risk factor in others. Stem design, whether "anatomic" (that is, stems with a curved lateral profile or an obtuse angle at the proximal-lateral portion of the stem) or "shoulder" (that is, straight with a proximal shoulder), may also be associated with a differential risk of aseptic loosening in cementless THA depending on the surgical approach used, but if so, this risk is not well characterized. QUESTIONS/PURPOSES: In this national registry study, we investigated the association between surgical approach and early aseptic loosening of (1) cementless femoral stems with a proximal angular shape (shoulder); and (2) anatomically shaped femoral stems. METHODS: The Dutch Arthroplasty Registry is a nationwide population-based register recording data on primary and revision hip arthroplasty. We selected all primary THAs (n = 63,354) with a cementless femoral stem inserted through an anterior, anterolateral, or posterior approach from 2007 to 2013 with a minimal followup of 2 years. Femoral stems were classified as "anatomic," "shoulder," or "other" (that is, not classifiable as anatomic or shoulder). From the 47,372 THAs with an anatomic or shoulder stem (mean followup, 3.5 years; SD, 1.8 years), 340 (0.7%) underwent revision surgery as a result of aseptic loosening of the femoral stem, 1195 (2.5%) were revised for other reasons, and 1558 patients (3.3%) died. We used Cox proportional hazard models to determine hazard ratios for aseptic loosening of anatomic and shoulder stems for the anterolateral and anterior approaches compared with the posterior approach. RESULTS: After controlling for relevant confounding variables such as sex, American Society of Anesthesiologists score, previous surgery, and coating and material of the femoral stem, we found that there was a stem-approach interaction. Separate analysis showed that shoulder stems had a greater likelihood of early aseptic loosening when the anterolateral approach (hazard ratio [HR], 2.28; 95% confidence interval [CI], 1.43-3.63; p < 0.001) or anterior approach (HR, 10.47; 95% CI, 2.55-43.10; p = 0.001) was used compared with the posterior approach. Separate analysis of the anatomic stems yielded no association with approach (anterolateral: HR, 1.07, 95% CI, 0.70-1.63, p = 0.77; anterior: HR, 1.31, 95% CI, 0.91-1.89, p = 0.15). CONCLUSIONS: In THA, cementless femoral stems with a proximal shoulder are associated with early aseptic loosening when inserted through an anterior or anterolateral approach compared with a posterior approach. An anatomically shaped stem may be preferred with these approaches, although further analysis with larger registry volumes should confirm our results, in particular for shouldered stems when implanted through an anterior approach. LEVEL OF EVIDENCE: Level III, therapeutic study.

Kinematic Magnetic Resonance Imaging Assessment of the Degenerative Cervical Spine: Changes after Anterior Decompression and Cage Fusion.

Study Design A prospective cohort study. Objective Decompression and fusion of cervical vertebrae is a combined procedure that has a high success rate in relieving radicular symptoms and stabilizing or improving cervical myelopathy. However, fusion may lead to increased motion of the adjacent vertebrae and cervical deformity. Both have been postulated to lead to adjacent segment pathology (ASP). Kinematic magnetic resonance imaging (MRI) has been increasingly used to evaluate range of motion (ROM) of the cervical spine and ASP. Our objective was to measure ASP, cervical curvature, and ROM of individual segments of the cervical spine using kinematic MRI before and 24 months after monosegmental cage fusion. Methods Eighteen patients who had single-level interbody fusion were included. ROM (using kinematic MRI) and degeneration, spinal stenosis, and cervical curvature were measured preoperatively and 24 months postoperatively. Results Using kinematic MRI, segmental motion of the cervical segments was measured with a precision of less than 3 degrees. The cervical fusion did not affect the ROM of adjacent levels. However, pre- and postoperative ROM was higher at the levels immediately adjacent to the fusion level compared with those further away. In addition, at 24 months postoperatively, the number of cases with ASP was higher at the levels immediately adjacent to fusion level. Conclusions Using kinematic MRI, ROM after spinal fusion can be measured with high precision. Kinematic MRI can be used not only in clinical practice, but also to study intervention and its effect on postoperative biomechanics and ASP of cervical vertebrae.

Evolution of the ischio-iliac lordosis during natural growth and its relation with the pelvic incidence.

PURPOSE: Human fully upright ambulation, with fully extended hips and knees, and the body's center of gravity directly above the hips, is unique in nature, and distinguishes humans from all other mammalians. This bipedalism is made possible by the development of a lordosis between the ischium and ilium; it allows to ambulate in this unique bipedal manner, without sacrificing forceful extension of the legs. This configuration in space introduces unique biomechanical forces with relevance for a number of spinal conditions. The aim of this study was to quantify the development of this lordosis between ischium and ilium in the normal growing and adult spine and to evaluate its correlation with the well-known clinical parameter, pelvic incidence. METHODS: Consecutive series of three-dimensional computed tomography scans of the abdomen of 189 children and 310 adults without spino-pelvic pathologies were used. Scan indications were trauma screening or acute abdominal pathology. Using previously validated image processing techniques, femoral heads, center of the sacral endplate and the axes of the ischial bones were semi-automatically identified. A true sagittal view of the pelvis was automatically reconstructed, on which ischio-iliac angulation and pelvic incidence were calculated. The ischio-iliac angle was defined as the angle between the axes of the ischial bones and the line from the midpoint of the sacral endplate to the center of the femoral heads. RESULTS: A wide natural variation of the ischio-iliac angle (3°-46°) and pelvic incidence (14°-77°) was observed. Pearson's analysis demonstrated a significant correlation between the ischio-iliac angle and pelvic incidence (r = 0.558, P < 0.001). Linear regression analysis revealed that ischio-iliac angle, as well as pelvic incidence, increases during childhood (+7° and +10°, respectively) and becomes constant after adolescence. CONCLUSIONS: The development of the ischio-iliac lordosis is unique in nature, is in harmonious continuity with the highly individual lumbar lordosis and defines the way the human spine is biomechanically loaded. The practical parameter that reflects this is the pelvic incidence; both values increase during growth and remain stable in adulthood.

Evaluation of pelvic morphology in the sagittal plane.

BACKGROUND CONTEXT: It is generally accepted that for normal subjects the angle of pelvic incidence (PI) increases during childhood and then remains unchanged throughout adolescence and adulthood. However, recent findings show that PI increases linearly throughout the lifespan due to morphological changes of the pelvis. PURPOSE: A retrospective study aiming to determine the extent of morphological changes of the pelvis related to the age of the subjects. STUDY DESIGN: Pelvic morphology was evaluated in a normal adult population by measuring the anatomical parameters of sagittal pelvic alignment. PATIENT SAMPLE: The final study cohort consisted of 330 subjects (mean age, 45.3 years; standard deviation, 18.1 years; range, 18-87 years; 164 male and 166 female subjects). OUTCOME MEASURES: Physiologic measures, obtained as measurements of PI, sacral end plate width (S1W), and pelvic thickness (PTH). METHODS: Parameters of PI, S1W, and PTH were evaluated from computed tomography images of the subjects. The measured PTH was normalized according to S1W and age of the subjects, allowing the comparison among anatomies of different sizes. The normalized components of PTH in anteroposterior and cephalocaudal directions were computed to determine the configuration and extent of changes in pelvic morphology related to subject age. RESULTS: Statistically significant correlation with both age and PI was obtained for all normalized parameters (except for the anteroposterior component of PTH for male subjects), and no statistically significant differences were observed between the sexes. With increasing PI that occurs due to the aging process, a decrease of PTH can be observed that is manifested not only as an increase of the distance between the sacrum and the hip axis in the anterior direction but considerably more as a decrease of the distance between the sacrum and the hip axis in the cephalic direction. By considering these morphological changes in the pelvis simultaneously, the hip axis can move only within a narrow area. CONCLUSIONS: The changes in pelvic morphology due to the aging process occur in the anterior direction, which may be due to the remodeling process affecting the coxal bone that results in an anterior drift of the acetabulum relative to the sacrum. More importantly, the changes are considerably more evident in the cephalic direction, which may be the result of the weight-bearing loads and consequent wear of acetabular cartilage.

Quantitative analysis of the closure pattern of the neurocentral junction as related to preexistent rotation in the normal immature spine.

BACKGROUND CONTEXT: The normal spine is not a symmetrical structure. In recent studies, we demonstrated the presence of an axial rotational pattern that is similar to what is seen in the most prevalent curve patterns in idiopathic scoliosis at different ages. This suggests that if the spine starts to decompensate into scoliosis, it follows this preexistent rotational pattern. In scoliosis, the neurocentral junctions (NCJs) close asymmetrically, which leads to a different pedicle morphology in the convexity and concavity of the curve. The present study aimed to establish at which age the NCJ closes in different regions of the spine, whether it closes asymmetrically in the nonscoliotic spine as well and whether the closure pattern is related to the earlier demonstrated preexistent rotation. PURPOSE: To evaluate the closure pattern and surface area of the left and right NCJs throughout the normal immature spine in relation to the preexistent spinal rotation at different ages. STUDY DESIGN: Retrospective cohort study using a systematic, semiautomatic analysis. PATIENT SAMPLE: Computed tomography (CT) scans of the thorax and abdomen of 199 nonscoliotic children (0-16 years old) were systemically analyzed. CT scans had been obtained for several reasons unrelated to this study, for example, recurrent respiratory infections, malignant disease (not involving the spine), or work up before bone marrow transplantation. Scans were categorized according to the criteria of the Scoliosis Research Society into infantile (0-3 years old), juvenile (4-9 years old), and adolescent (10-16 years old) age cohorts. OUTCOME MEASURES: Closure, absolute surface area, and the angle between the longitudinal axis of the left and right NCJ and preexistent vertebral rotation at each spinal level. METHODS: Transverse CT slices were systemically analyzed for closure and asymmetry of the absolute area of 4,992 NCJs from spinal levels T2-L5. The outcome measures were analyzed semiautomatically using custom-made software developed at our institution (ImageXplorer; Image Sciences Institute). Inter- and intraobserver reliabilities were calculated. RESULTS: For all subjects, the entire thoracic area was available. Complete scans down to L5 of the lumbar spine were available in 43 cases. Closure of the NCJs was first observed in the lumbar spine, then in the high thoracic spine, and finally in the mid- and low thoracic spine. Closure occurred asymmetrically, left-right predominance depended on the age. In the mid- and low thoracic spine, the surface areas of the right NCJs were larger at the infantile age, whereas at the juvenile age the areas of the left NCJs were larger. This corresponded to the spine's preexistent rotation. Rotation of the high thoracic vertebrae was to the left in all age cohorts. Rotation in the mid- and low thoracic spine was to the left in the infantile cohort but reversed to the right in the juveniles and even more so in the adolescents. The lumbar spine was rotated to the left at the infantile age and not significantly rotated at the juvenile and adolescent ages. Orientation of the NCJs in relation to the vertebraes' longitudinal axis was symmetrical, not dependent on age, and more transverse at the midthoracic levels than at other spinal levels. CONCLUSIONS: This study focuses on the asymmetry and the regional pattern of closure of the NCJs at different ages. It suggests that preexistent rotation of the spine is related to the asymmetrical closure of the NCJs. Whether the asymmetry is the cause of or is caused by the preexistent rotation cannot be derived from this study.

Sagittal spinal profile and spinopelvic balance in parents of scoliotic children.

BACKGROUND CONTEXT: It is well known that spinal biomechanics and familial predisposition play an important role in the onset and evolution of idiopathic scoliosis. The relationship between the sagittal profile of the spine and spinal biomechanics has also been established in a number of studies. It has been suggested previously that a certain sagittal spinal configuration with implications for spinal rotational stiffness is inherited, thus providing a possible explanation for the well-known hereditary component in adolescent idiopathic scoliosis (AIS). PURPOSE: To test the hypothesis that the familial trend in AIS may be partially explained by the inheritance of a sagittal spinal profile, which has been shown to make the spine less resistant to rotatory decompensation. STUDY DESIGN: A prospective case controlled radiographic analysis of the sagittal profile of the spine and spinopelvic alignment. PATIENT SAMPLE: One hundred two parents of scoliotic children, compared with 102 age-matched controls (parents of nonscoliotic children). OUTCOME MEASURES: Physiologic measures: sagittal profile of the spine and spinopelvic alignment. METHODS: Freestanding lateral radiographs of 51 parent couples of girls with severe (Cobb angle >30°) progressive AIS (AIS group) and 102 age-matched controls (control group) were taken. Parents with manifest spinal deformities or spinal pathology of any kind were excluded based on history or spinal X-ray to avoid distorted sagittal images with unreliable measurements. Values were calculated for thoracic kyphosis (T4-T12), lumbar lordosis (L1-L5), spinal balance (sagittal plumb line of C7 and T4, T1-L5 sagittal spinal inclination, T9 sagittal offset), curvature parameters (expressed in the area under the curve [AUC]), and pelvic parameters (pelvic tilt, pelvic incidence, and sacral slope). In addition, the height, offset, and length of the posteriorly inclined spinal segment, inclination of each vertebra, and normalized sagittal spinal profile were calculated. Differences in spinopelvic alignment between fathers and mothers of both groups were analyzed. RESULTS: In the fathers of the AIS group, the plumb line of T4 was significantly less posteriorly positioned relative to the hip axis (79 mm vs. 92 mm; p=.009); the overall AUC and the lumbar AUC were significantly smaller (p=.002 and p=.008, respectively) as compared with the fathers in the control group. Vertebrae T11-L2 were significantly less backwardly inclined in the fathers of the AIS group (T11, L2: p<.05 and T12-L1: p<.01). An analysis of sagittal spinal profile showed a significantly flatter spine in the fathers of the AIS group (p=.01). No significant differences were observed in height, offset, and length of the backwardly inclined spinal segment. In the mothers of the AIS group, no statistically significant differences were observed in the spinopelvic parameters, spinal curvature, inclination of the vertebrae, and declive spinal segment parameters or sagittal spinal profile as compared with the mothers in the control group. CONCLUSIONS: The sagittal spinal profile of the fathers of scoliotic children was significantly flatter than the sagittal spinal profile of fathers of nonscoliotic children. No difference was found in the sagittal spinal profile of the mothers of scoliotic children as compared with mothers of nonscoliotic children. Although it is well known that scoliotic mothers have an increased risk of having a scoliotic offspring, this study indicates that fathers may possibly contribute as well through their sagittal spinal profile to the inheritance of idiopathic scoliosis.

Posteriorly directed shear loads and disc degeneration affect the torsional stiffness of spinal motion segments: a biomechanical modeling study.

STUDY DESIGN: Finite element study. OBJECTIVE: To analyze the effects of posterior shear loads, disc degeneration, and the combination of both on spinal torsion stiffness. SUMMARY OF BACKGROUND DATA: Scoliosis is a 3-dimensional deformity of the spine that presents itself mainly in adolescent girls and elderly patients. Our concept of its etiopathogenesis is that an excess of posteriorly directed shear loads, relative to the body's intrinsic stabilizing mechanisms, induces a torsional instability of the spine, making it vulnerable to scoliosis. Our hypothesis for the elderly spine is that disc degeneration compromises the stabilizing mechanisms. METHODS: In an adult lumbar motion segment model, the disc properties were varied to simulate different aspects of disc degeneration. These models were then loaded with a pure torsion moment in combination with either a shear load in posterior direction, no shear, or a shear load in anterior direction. RESULTS: Posteriorly directed shear loads reduced torsion stiffness, anteriorly directed shear loads increased torsion stiffness. These effects were mainly caused by a later (respectively earlier) onset of facet joint contact. Disc degeneration cases with a decreased disc height that leads to slackness of the annular fibers and ligaments caused a significantly decreased torsional stiffness. The combination of this stage with posterior shear loading reduced the torsion stiffness to less than half the stiffness of a healthy disc without shear loads. The end stage of disc degeneration increased torsion stiffness again. CONCLUSION: The combination of a decreased disc height, that leads to slack annular fibers and ligaments, and posterior shear loads very significantly affects torsional stiffness: reduced to less than half the stiffness of a healthy disc without shear loads. Disc degeneration, thus, indeed compromises the stabilizing mechanisms of the elderly spine. A combination with posteriorly directed shear loads could then make it vulnerable to scoliosis. LEVEL OF EVIDENCE: N/A.

A review of methods for evaluating the quantitative parameters of sagittal pelvic alignment.

BACKGROUND CONTEXT: The sagittal alignment of the pelvis represents the basic mechanism for maintaining postural equilibrium, and a number of methods were developed to assess normal and pathologic pelvic alignments from two-dimensional sagittal radiographs in terms of positional and anatomic parameters. PURPOSE: To provide a complete overview of the existing methods for quantitative evaluation of sagittal pelvic alignment and summarize the relevant publications. STUDY DESIGN: Review article. METHODS: An Internet search for terms related to sagittal pelvic alignment was performed to obtain relevant publications, which were further supplemented by selected publications found in their lists of references. By summarizing the obtained publications, the positional and anatomic parameters of sagittal pelvic alignment were described, and their values and relationships to other parameters and features were reported. RESULTS: Positional pelvic parameters relate to the position and orientation of the observed subject and are represented by the sacral slope, pelvic tilt, pelvic overhang, sacral inclination, sacrofemoral angle, sacrofemoral distance, pelvic femoral angle, pelvic angle, and sacropelvic translation. Anatomic pelvic parameters relate to the anatomy of the observed subject and are represented by the pelvisacral angle (PSA), pelvic incidence (PI), pelvic thickness (PTH), sacropelvic angle (PRS1), pelvic radius (PR), femorosacral posterior angle (FSPA), sacral table angle (STA), and sacral anatomic orientation (SAO). The review was mainly focused on the evaluation of anatomic pelvic parameters, as they can be compared among subjects and therefore among different studies. However, ambiguous results were yielded for normal and pathologic subjects, as the reported values show a relatively high variability in terms of standard deviation for every anatomic parameter, which amounts to around 10 mm for PTH and PR; 10° for PSA, PI, and SAO; 9° for PRS1 and FSPA; and 5° for STA in the case of normal subjects and is usually even higher in the case of pathologic subjects. Among anatomic pelvic parameters, PI was the most studied and therefore represents a key parameter in the complex framework of sagittal spinal alignment and related deformities. From the reviewed studies, the regression lines for PI and the corresponding age of the subjects indicate that PI tends to increase with age for normal (PI = +0.17 × age+46.40) and scoliotic (PI = +0.20 × age+50.52) subjects and decrease with age for subjects with spondylolisis or spondylolisthesis (PI = -0.26 × age+75.69). CONCLUSIONS: Normative values for anatomic parameters of sagittal pelvic alignment do not exist because the variability of the measured values is relatively high even for normal subjects but can be predictive for spinal alignment and specific spinopelvic pathologies.

Analysis of pelvic incidence from 3-dimensional images of a normal population.

STUDY DESIGN: Pelvic incidence (PI) was measured in 3 dimensions from computed tomographic (CT) images of normal subjects using a computerized method. OBJECTIVE: To obtain the angle of PI from 3-dimensional (3D) images and analyze its distribution in a normal population. SUMMARY OF BACKGROUND DATA: The sagittal alignment of the pelvis is usually evaluated in 2-dimensional (2D) sagittal radiographs. The purpose of this study is to measure and analyze PI, which represents a key parameter of sagittal alignment, in 3D images. METHODS: A computerized method, based on image-processing techniques, was used to automatically determine the anatomical references required to measure PI, that is, the centers of the femoral heads in 3 dimensions and the center and inclination of the sacral end plate in 3 dimensions. Multiplanar image reformation was applied to obtain perfect sagittal views with all anatomical structures completely in line with the hip axis from which PI was calculated. RESULTS: PI was successfully obtained in CT images of 370 normal subjects (mean age: 41.5 years; range: 1-87 years). The mean PI (± standard deviation) was equal to 46.6° (±9.2°) for male subjects, 47.6° (±10.7°) for female subjects, and 47.1° (±10.0°) for both sexes. No statistically significant differences were obtained between the sexes, and statistically significant correlation was obtained between PI and age. CONCLUSION: In this study, the sagittal alignment of the pelvis was evaluated in terms of PI completely in 3 dimensions. The results show that computerized measurements of PI in 3 dimensions are less variable than manual measurements. The large span of PI values for normal subjects indicates that the natural variation of PI is relatively large.

Platelet pool inventory management: theory meets practice.

BACKGROUND: The shelf life of platelet concentrates (PCs) is a matter of days. Simultaneously, the demand is highly variable, shortages are not allowed, and producing too many results in outdating. Concurrently, younger PCs, implying an extended time till outdating (TTO), are preferred. Common PC inventory management relies on experience-based order-up-to rules. This study aimed at minimizing outdating and shortages, while extending the TTO through a theoretical approach. It focuses on PCs processed from whole blood donations. STUDY DESIGN AND METHODS: A combined approach of stochastic dynamic programming and simulation techniques (SDP/S), from the mathematical discipline operations research, has been implemented. This approach included the design of the dedicated software tool thrombocyte inventory management optimizer (TIMO). Based on the 2007 data, an optimal order-up-to rule was calculated. Outdating percentages and TTOs have been collected from August 2005 to July 2010. The resulting order-up-to rule has been applied and adjusted from summer 2007 onward. RESULTS: Over the study period, the results of the practical implementation showed significant improvements. The median weekly outdating percentage dropped to less than 1% and a gain in TTO of 0.48 day was reached. The results and the additional computer simulations brought confidence to the personnel to apply and adopt the "theoretical" approach and TIMO. CONCLUSION: Applying theory may help a blood bank to improve its PC inventory management and may help to identify to what extent practical limits can approach theoretical limits. The application of the theory has led to both a significant improvement and a more structured and less panic-driven PC inventory management.

Experimental animal models in scoliosis research: a review of the literature.

BACKGROUND CONTEXT: Many animal species and an overwhelming variety of procedures that produce an experimental scoliosis have been reported in the literature. However, varying results have been reported on identical procedures in different animal species. Furthermore, the relevance of experimental animal models for the understanding of human idiopathic scoliosis remains questionable. PURPOSE: To give an overview of the procedures that have been performed in animals in an attempt to induce experimental scoliosis and discuss the characteristics and significance of various animal models. STUDY DESIGN: Extensive review of the literature on experimental animal models in scoliosis research. METHODS: MEDLINE electronic database was searched, focusing on parameters concerning experimental scoliosis in animal models. The search was limited to the English, French, and German languages. RESULTS: The chicken appeared to be the most frequently used experimental animal followed by the rabbit and rat. Additionally, scoliosis has been induced in primates, goats, sheep, pigs, cows, dogs, and frogs. Procedures widely varied from systemic to local procedures. CONCLUSIONS: Although it has been possible to induce scoliosis-like deformities in many animals through various ways, this always required drastic surgical or systemic interventions, thus making the relation to human idiopathic scoliosis unclear. The basic drawback of all used models remains that no animal resembles the upright biomechanical spinal loading condition of man, with its inherent rotational instability of certain spinal segments. The fundamental question remains what the significance of these animal models is to the understanding of human idiopathic scoliosis.

Analysis of preexistent vertebral rotation in the normal infantile, juvenile, and adolescent spine.

STUDY DESIGN: Vertebral rotation was systematically analyzed in the normal, nonscoliotic thoracic spine of children aged 0 to 16 years. Subgroups were created to match the infantile, juvenile, and adolescent age groups according to the criteria of the Scoliosis Research Society. OBJECTIVE: To determine whether a distinct pattern of vertebral rotation in the transverse plane exists in the normal, nonscoliotic infantile, juvenile, and adolescent spine. SUMMARY OF BACKGROUND DATA: We assume that, once the spine starts to deteriorate into a scoliotic deformity, it will follow a preexisting rotational pattern. Recently, we identified a rotational pattern in the normal nonscoliotic adult spine that corresponds to the most common curve types in adolescent idiopathic scoliosis. In infantile idiopathic scoliosis, curves are typically left sided and boys are affected more often than girls, whereas in adolescent idiopathic scoliosis, the thoracic curve is typically right sided and predominantly girls are affected. The present study is the first systematic analysis of vertebral rotation in the normal children's spine. METHODS: Vertebral rotation in the transverse plane of T2-T12 was measured by using a semiautomatic method on 146 computed tomographic scans of children (0-16 years old) without clinical or radiologic evidence of spinal pathology. Scans were mainly made for reasons such as recurrent respiratory tract infections, malignancies, or immune disorders. Vertebral rotational patterns were analyzed in the infantile (0-3-year-old), juvenile (4-9-year-old), and adolescent (10-16-year-old) boys and girls. RESULTS: In the infantile spine, vertebrae T2-T6 were significantly rotated to the left (P < 0.001). In the juvenile spine, T4 was significantly rotated to the left. In the adolescent spine, T6-T12 were significantly rotated to the right (P ≤ 0.001). Rotation to the left was more pronounced in infantile boys than in the girls (P = 0.023). In juvenile and adolescent children, no statistical differences in rotation were found between the sexes. CONCLUSION: These data support the hypothesis that the direction of the spinal curve in idiopathic scoliosis is determined by the built-in rotational pattern that the spine exhibits at the time of onset. The well-known predominance of right-sided thoracic curves in adolescent idiopathic scoliosis and left-sided curves in infantile idiopathic scoliosis can be explained by the observed patterns of vertebral rotation that preexist at the corresponding age.