Anterior vertebral tethering: imaging of tether rupture.

Anterior vertebral tethering, also known as vertebral body tethering, is an evolving, minimally invasive surgical technique to correct spinal curvature in skeletally immature patients. The procedure involves placement of vertebral screws that are connected by an anterolateral tether. This procedure may be complicated by rupture of the non-radiopaque tether. The radiologist should be aware of imaging findings that suggest this complication on follow-up spine radiographs.

Diagnosis of non-osseous spinal metastatic disease: the role of PET/CT and PET/MRI.

The spine is the third most common site for distant metastasis in cancer patients with approximately 70% of patients with metastatic cancer having spinal involvement. Positron emission tomography (PET), combined with computed tomography (CT) or magnetic resonance imaging (MRI), has been deeply integrated in modern clinical oncology as a pivotal component of the diagnostic work-up of patients with cancer. PET is able to diagnose several neoplastic processes before any detectable morphological changes can be identified by anatomic imaging modalities alone. In this review, we discuss the role of PET/CT and PET/MRI in the diagnostic management of non-osseous metastatic disease of the spinal canal. While sometimes subtle, recognizing such disease on FDG PET/CT and PET/MRI imaging done routinely in cancer patients can guide treatment strategies to potentially prevent irreversible neurological damage.

Anterior vertebral tethering for adolescent idiopathic scoliosis: our initial ten year clinical experience.

BACKGROUND: Anterior vertebral tethering (AVT) is a minimally invasive alternative to fusion surgery for adolescent idiopathic scoliosis (AIS) that offers the potential for definitive scoliosis treatment with the possibility of preservation of the growth, motion, function and overall health of the spine. This study represents our first ten years using AVT to treat AIS. METHODS: In this retrospective review we analyzed our first 74 AIS patients treated with AVT 2010-2020. Multiple Lenke curve types 33-70° were treated with skeletal maturity spanning Risser -1 to 5. RESULTS: Of 74 consecutive AIS patients treated with AVT, 52 patients (47 female, 5 male) had sufficient 2-year follow-up for inclusion. Forty-six of these 52 patients (88%) with 65 curves (35T, 30TL/L) were satisfactorily treated with AVT demonstrating curve correction from 48.6° pre-op (range 33°-70°) at age 15.1 years (range 9.2-18.8) and skeletal maturity of Risser 2.8 (range -1 to 5) to 23.2° post-op (range 0°-54°) and 24.0° final (range 0°-49°) at 3.3 years follow-up (range 2-10 years). Curve corrections from pre-op to post-op and pre-op to final were both significant (p < 0.001). The 0.8° change from post-op to final was not significant but did represent good control of scoliosis correction over time. Thoracic kyphosis and lumbar lordosis were maintained in a normal range throughout while axial rotation demonstrated a slight trend toward improvement. Skeletal maturity of Risser 4 or greater was achieved in all but one patient. Four of the 52 patients (8%) required additional procedures for tether rupture (3 replacements) or overcorrection (1 removal) to achieve satisfactory treatment status after AVT. An additional 6 of the 52 patients (12%), however, were not satisfactorily treated with AVT, requiring fusion for overcorrection (2) or inadequate correction (4). CONCLUSIONS: In this study, AIS was satisfactorily treated with AVT in the majority of patients over a broad range of curve magnitudes, curve types, and skeletal maturity. Though late revision surgery for overcorrection, inadequate correction, or tether rupture was not uncommon, the complication of overcorrection was eliminated after our first ten patients by a refinement of indications. LEVEL OF EVIDENCE: IV.

Volatile vs Total intravenous Anaesthesia for major non-cardiac surgery: a pragmatic randomised triaL (VITAL).

BACKGROUND: Improving outcomes after surgery is a major public health research priority for patients, clinicians and the NHS. The greatest burden of perioperative complications, mortality and healthcare costs lies amongst the population of patients aged over 50 years who undergo major non-cardiac surgery. The Volatile vs Total Intravenous Anaesthesia for major non-cardiac surgery (VITAL) trial specifically examines the effect of anaesthetic technique on key patient outcomes: quality of recovery after surgery (quality of recovery after anaesthesia, patient satisfaction and major post-operative complications), survival and patient safety. METHODS: A multi-centre pragmatic efficient randomised trial with health economic evaluation comparing total intravenous anaesthesia with volatile-based anaesthesia in adults (aged 50 and over) undergoing elective major non-cardiac surgery under general anaesthesia. DISCUSSION: Given the very large number of patients exposed to general anaesthesia every year, even small differences in outcome between the two techniques could result in substantial excess harm. Results from the VITAL trial will ensure patients can benefit from the very safest anaesthesia care, promoting an early return home, reducing healthcare costs and maximising the health benefits of surgical treatments. TRIAL REGISTRATION: ISRCTN62903453. September 09, 2021.

PEARLS - A multicentre phase II/III trial of extended field radiotherapy for androgen sensitive prostate cancer patients with PSMA-avid pelvic and/or para-aortic lymph nodes at presentation.

PEARLS is a multi-stage randomised controlled trial for prostate cancer patients with pelvic and/or para-aortic PSMA-avid lymph node disease at presentation. The aim of the trial is to determine whether extending the radiotherapy field to cover the para-aortic lymph nodes (up to L1/L2 vertebral interspace) can improve outcomes for this patient group.

A Thoracoscopic Technique Used in Anterior Vertebral Tethering for Adolescent Idiopathic Scoliosis.

Anterior vertebral tethering (AVT) is a relatively recent alternative to posterior spinal fusion for progressive curves in growing patients with idiopathic scoliosis. AVT uses a thoracoscopic approach to minimize trauma to the thoracic wall and chest cavity. There are limited technical descriptions of this method. Patients benefit from proficiency and reproducibility to allow for appropriate spinal curve correction over time. This Technical Note outlines the steps of the thoracoscopic approach to AVT and reviews the current indications for AVT over posterior spinal fusion, as well as the most recently published clinical outcomes of this procedure.

Polygenic inheritance of adolescent idiopathic scoliosis: a study of extended families in Utah.

A heritability study of 69 extended Utah families with a history of adolescent idiopathic scoliosis (AIS) indicates that AIS is a polygenic, multifactorial condition. Each family reported a history of AIS within four generations; a total of 247 individuals were confirmed via X-rays and medical records to have AIS. Coefficient of kinship was more than 25 standard deviations higher for these 69 families than for the general population. Excluding all probands and assuming autosomal dominant inheritance, 1,260 individuals over the age of 16 were determined to be at risk for AIS because they have a parent with AIS. Assuming 50% of these individuals carry the allele, estimated penetrance in at-risk males is approximately 9%, and estimated penetrance in at-risk females is approximately 29%. Recurrence risk in relatives decreases as the degree of relationship to the affected individual becomes more distant; however, the lowest recurrence risk calculated, for third-degree relatives, is still an average of 9%, well above the general population's risk. Onset of AIS appears to be inherited separate from curve pattern and severity. In a study of phenotypes in 36 of the families, the affected individuals were consistent in either curve severity or curve pattern, but not both. It is unclear whether severity or pattern is more heritable, but it is possible that the location of the curve on the spine is the most heritable trait of the phenotype. The study demonstrates the genetic complexity of AIS, including the low penetrance of its cumulative alleles and variable expression.

Characterizing Anesthetic Management and Perioperative Outcomes Associated with a Novel, Fusionless Scoliosis Surgery in Adolescents.

Anterior vertebral tethering (AVT) is a novel "fusionless" surgical approach to correct scoliosis. This study aims to characterize the anesthetic management and perioperative outcomes of AVT and traditional posterior spinal fusion (PSF) after establishing the technique at our institution. Scoliosis correction procedures performed in patients aged 10 to 21 years between January 2014 and August 2017 were identified in the electronic medical record. Patient characteristics and perioperative data about anesthetic use and pain management were extracted. Descriptive statistics were generated. Thirty-five patients undergoing AVT and 40 patients undergoing PSF met inclusion criteria. Preoperative fluoroscopy-guided epidural placement was used only in the AVT group (86%). The worst pain score on postoperative day (POD) 1 after AVT was a mean (SD) of 5.6 (2.3), with average pain scores on subsequent days ranging from 2.9 (1.2) to 3.6 (1.7). Total in-hospital opioid consumption in morphine milligram equivalents was 70 (76.6) for AVT and 193.4 (137.2) for PSF (P < .01). Discharge occurred on POD 4.4 (1.4) for AVT and POD 6.2 (1.9) for PSF (P < .01). The worst pain score on POD 1 for PSF was 6.6 (2.1), and average pain scores ranged from 3.7 (1.8) to 4.2 (1.8). These results help inform about the expected recovery profile and narcotic requirement after AVT and PSF.

Stereoselective Synthesis of Fused Vinylcyclopropanes by Intramolecular Tsuji-Trost Cascade Cyclization.

A stereoselective intramolecular Tsuji-Trost cascade cyclization of (homo)allylic vicinal diacetates with a pendant ß-ketoamide or related carbon nucleophile to give γ-lactam-fused vinylcyclopropanes is reported. In addition to two new rings, the products contain three new C-C stereocenters (two of which are quaternary) with a 9:1 dr. Moreover, the reaction proceeds in >94% enantiospecificity with optically enriched starting materials, using an inexpensive carbohydrate as the source of chirality.

Anterior cervical fixation: analysis of load-sharing and stability with use of static and dynamic plates.

BACKGROUND: Anterior plates provide stability following decompression and fusion of the cervical spine. Various plate designs have emerged, and they include static plates with fixed-angle screws, rotationally dynamic plates that allow the screws to toggle in the plate, and translationally dynamic plates that allow the screws to both toggle and translate vertically. The goal of this study was to document the effects of plate design following a single-level corpectomy and placement of a full-length strut graft and the effects following 10% subsidence of the graft. METHODS: A total of twenty-one cadaveric cervical spines (C2-T1) were randomized into three treatment groups and were tested for initial range of motion. A C5 corpectomy was performed, reconstruction was done with a full-length interbody spacer containing a load-cell, and an anterior cervical plate was applied. Load-sharing data were recorded with incremental axial loads. The range of motion was measured with +/- 2.5 Nm of torque in flexion-extension, lateral bending, and axial rotation. Then, the total length of the interbody spacer was reduced by 10% to simulate subsidence, and load-sharing and the range of motion were retested. RESULTS: With the full-length interbody spacer, there were no significant differences in the abilities of the constructs to share load or limit motion. Following shortening of the interbody spacer, the static plate construct lost nearly 70% of its load-sharing capability, while neither of the dynamic plate constructs lost load-sharing capabilities. Also, the static plate construct allowed significantly more motion in flexion-extension following simulated subsidence than did either of the dynamic plate constructs (p < 0.05). CONCLUSIONS: Although all of the tested anterior cervical plating systems provide similar load-sharing and stiffness following initial placement of the interbody spacer, the static plate system lost its ability to share load and limit motion following simulated subsidence of the interbody spacer. Both dynamic plate systems maintained load-sharing and stiffness despite simulated subsidence. CLINICAL RELEVANCE: This study provides an improved understanding of the immediate performance of anterior cervical fusion surgery with plate fixation.

Less invasive posterior fixation method following transforaminal lumbar interbody fusion: a biomechanical analysis.

BACKGROUND CONTEXT: Current surgical trends increasingly emphasize the minimization of surgical exposure and tissue morbidity. Previous research questioned the ability of unilateral pedicle screw instrumentation to adequately stabilize posterior fusion constructs. No study to date has addressed the effects of reduced posterior instrumentation mass on interbody construct techniques. Unilateral surgical exposure for transforaminal lumbar interbody fusion (TLIF) allows ipsilateral pedicle screw placement. Theoretically, percutanous contralateral facet screw placement could provide supplemental construct support without additional surgical exposure. PURPOSE: Identify the biomechanical effects of reduced spinal fusion instrumentation mass on interbody construct stability. STUDY DESIGN: An in vitro biomechanical study using human lumbar spines comparing stability of TLIF constructs augmented by: (1) bilateral pedicle screw fixation, (2) unilateral pedicle screw fixation, or (3) a novel unilateral pedicle screw fixation supplemented with contralateral facet screw construct. METHODS: Seven fresh frozen human cadaveric specimens were tested in random construct order in flexion/extension, lateral bending, and axial rotation using +/-5.0 Nm torques and 50 N axial compressive loads. Analysis of torque rotation curves determined construct stability. Using paired statistical methods, comparison of construct stiffness and total range of motion within each specimen were performed using the Wilcoxon signed ranks test with a Holm-Sidák multiple comparison procedure (alpha=0.05). RESULTS: In flexion/extension, lateral bending, and axial rotation, there were no measurable differences in either stiffness or range of motion between the standard bilateral pedicle screw and the novel construct after TLIF. After TLIF, the unilateral pedicle screw construct provided only half of the improvement in stiffness compared with bilateral or novel constructs and allows for significant off-axis rotational motions, which could be detrimental to stability and the promotion for fusion. CONCLUSIONS: All tested TLIF constructs with posterior instrumentation decreased segmental range of motion and increased segmental stiffness. While placing unilateral posterior instrumentation decreases overall implant bulk and dissection, it allows for significantly increased segmental range of motion, less stiffness, and produces off-axis movement. The technique of contralateral facet screw placement provides the surgical advantages of unilateral pedicle screw placement with stability comparable to TLIF with bilateral pedicle screws.

The efficacy and integrity of shape memory alloy staples and bone anchors with ligament tethers in the fusionless treatment of experimental scoliosis.

BACKGROUND: Scoliosis is a complex three-dimensional deformity with limited treatment options. Current treatments present potential problems that may be addressed with use of fusionless techniques for the correction of scoliosis. However, there are few data comparing the efficacy of different fusionless implant strategies in controlling scoliosis or on the integrity of rigid compared with flexible devices in an in vivo setting over time. The objective of this study was to compare the efficacy and integrity of rigid and flexible anterior thoracic tethers used to treat experimental scoliosis. METHODS: Experimental scoliosis was created in twenty-four Spanish Cross-X female goats and was subsequently treated with either anterior shape memory alloy staples or anterior ligament tethers attached to bone anchors. Serial radiographs were analyzed to determine the efficacy of the implants in controlling scoliosis progression as well as the integrity of the implants at study completion. After the goats were killed, the implants were analyzed with use of three quantitative indices of implant integrity and implant pullout testing. RESULTS: Over the treatment period, scoliosis progressed from 77.3 degrees to 94.3 degrees in the goats treated with staples and was corrected from 73.4 degrees to 69.9 degrees in the goats treated with bone anchors, with loosening of eighteen of forty-two staples (two of the eighteen dislodged) and evidence of drift in two of forty-nine anchors. Histologic sections revealed a consistent halo of fibrous tissue around the staple tines but well-fixed bone anchors at all sites. Pullout testing demonstrated that bone anchors had greater strength than staples initially and at the study completion, with an increase in bone anchor fixation over the course of the study. CONCLUSIONS: In this scoliosis model, the flexible ligament tethers attached to bone anchors demonstrated greater efficacy and integrity than the more rigid shape memory alloy staples.

Distinctive trajectory groups of mental health functioning among assertive community treatment clients: an application of growth mixture modelling analysis.

OBJECTIVE: Assertive community treatment (ACT) studies that have used conventional, statistical growth modelling methods have not examined different trajectories of outcomes or covariates that could influence different trajectories, even though heterogeneity in outcomes has been established in other research on severe mental illness. The purpose of our study was to examine the general trend in mental health functioning of ACT clients over a 2-year follow-up time period, to discover groups of ACT clients with distinctive longitudinal trajectories of mental health functioning, and to examine if some of the key sociodemographic and illness-related factors influence group membership. METHOD: A 2-year, prospective, within-subjects study of 216 ACT clients within southern Ontario, collected functional outcome data at baseline and 12 and 24 months using the Colorado Client Assessment Record. Baseline covariates included sex, primary diagnosis, number of comorbidities, hospitalization history, and duration of illness. Growth mixture modelling (GMM) was used to examine trajectories. RESULTS: Clinical staff assessments of ACT clients showed a statistically significant improvement in functioning and 84% achieved successful community tenure. GMM analysis identified 2 classes of ACT clients: class 1 (79.63% of clients) experienced lower and stable overall functioning, and class 2 (20.37%) showed a better baseline functioning score and improvement in the overall functioning over time. Class membership was predicted by the number of comorbidities and diagnosis. CONCLUSIONS: Our study suggests general stability in overall functioning for the sampled ACT clients over 2 years, but significant heterogeneity in trajectories of functioning.

Objectif : Les études sur le traitement communautaire dynamique (TCD) qui ont utilisé des méthodes de modèle de croissance statistiques traditionnelles n'ont pas examiné les différentes trajectoires des résultats ou covariantes qui pourraient influencer les différentes trajectoires, même si l'hétérogénéité des résultats a été établie dans d'autres recherches sur la maladie mentale grave. Le but de notre étude était d'examiner la tendance générale du fonctionnement de la santé mentale chez des clients de TCD sur une période de suivi de 2 ans, afin de découvrir des groupes de clients de TCD ayant des trajectoires longitudinales distinctes du fonctionnement de la santé mentale et d'examiner si certains des facteurs sociodémographiques clés et liés à la maladie influencent l'adhésion au groupe. Méthode : Une étude prospective sur 2 ans intra-sujets de 216 clients de TCD du sud de l'Ontario a recueilli des données de résultat fonctionnel au départ et à 12 et 24 mois, à l'aide du registre d'évaluation des clients du Colorado. Les covariantes de départ incluaient le sexe, le diagnostic primaire, le nombre de comorbidités, les antécédents d'hospitalisation, et la durée de la maladie. Le modèle de croissance à mélange de distributions (MCMD) a servi à examiner les trajectoires. Résultats : Les évaluations cliniques du personnel des clients de TCD ont indiqué une amélioration statistiquement significative du fonctionnement et 84 % ont atteint un statut d'occupation réussie dans la communauté. L'analyse du MCMD a identifié 2 classes de clients de TCD : la classe 1 (79,63 % des clients) a connu un fonctionnement général plus faible et stable, et la classe 2 (20,37 %) a obtenu un meilleur score de fonctionnement au départ et une amélioration du fonctionnement général avec le temps. L'adhésion à la classe était prédite par le nombre de comorbidités et le diagnostic. Conclusions : Notre étude suggère une stabilité générale du fonctionnement global pour les clients de TCD échantillonnés sur 2 ans, mais une hétérogénéité significative des trajectoires du fonctionnement.

The effect of two clinically relevant fusionless scoliosis implant strategies on the health of the intervertebral disc: analysis in an immature goat model.

STUDY DESIGN: Immature goat spines were instrumented at 5 levels with 2 different fusionless scoliosis implants. Instrumented and subadjacent spinal segments were analyzed to determine the effect on the disc and endplate. OBJECTIVE: Analyze the regional biochemistry and histology of spinal motion segments in healthy goat spines treated with 2 clinically relevant, fusionless scoliosis implants. SUMMARY OF BACKGROUND DATA: Fusionless scoliosis surgery is thought to be more physiologic than fusion as it preserves the growth, motion, and function of the spine. There are presently little data supporting this belief. METHODS: Scoliosis was created in twelve 8-week-old female goats (n = 6 per group) using 1 of 2 fusionless scoliosis implant strategies: 2 SMA staples per level or a bone anchor/ligament tether. A third group served as controls (n = 6). Goats were analyzed after 6 months. Qualitative and quantitative analyses were performed on spinal motion segments using H&E, TUNEL, and caspase-3 staining. RESULTS: Neither implant strategy produced degenerative changes in the disc. However, discs at instrumented levels in both groups demonstrated decreased cell density (P < 0.01) and increased cellular apoptosis (P < 0.001) compared to controls. Subadjacent discs demonstrated preservation of viable cells and endplate vascularity compared to instrumented discs. CONCLUSION: Fusionless scoliosis implants result in alterations in viable cell density within the disc and reduced vascularity in the vertebral endplates of instrumented but not subadjacent discs. Though obvious disc degeneration was not observed, the implications of the cellular and histologic changes are not known. Additional study will be necessary to better understand various fusionless scoliosis surgery strategies and their effect on surrounding tissues.

Primary paraganglioma of the parathyroid: a case report and clinicopathologic review.

Paragangliomas are relatively uncommon neoplasms that arise in adrenal and extra-adrenal paraganglia of the autonomic nervous system. Parasympathetic paraganglioma develop predominantly in the head and neck. It is exceedingly uncommon to develop a primary intraparathyroid paraganglioma. There is only a single case report in the English literature. The information from the single previous case report (Medline 1960-2009) was combined with this case report. Our patient was a 69 year old woman who presented with a thyroid gland mass, with extension into the substernal space. The patient had a history of renal cell carcinoma removed 18 months before. At surgery, a thyroid lobectomy and a parathyroidectomy were performed. The parathyroid tissue showed a very well defined zellballen arrangement of paraganglion cells within the parenchyma of the parathyroid gland. The cells had ample basophilic, granular cytoplasm. The nuclei were generally round to oval with 'salt-and-pepper' nuclear chromatin distribution. There was a richly vascularized stroma. Mitotic figures, necrosis, invasive growth, and profound nuclear pleomorphism were absent. The neoplastic cells were strongly and diffusely immunoreactive with chromogranin, synaptophysin, CD56, and focally with cyclin-D1. The paraganglioma showed a delicate S-100 protein positive supporting sustentacular framework. Keratin, CD10, PTH, calcitonin and RCC markers were negative. The patient showed no stigmata of Multiple Endocrine Neoplasia (MEN) and has no paraganglioma in any other anatomic site. She is alive without any additional findings 12 months after surgery. Isolated paraganglioma within the parathyroid is rare, and should be separated from parathyroid adenoma, hyperplasia or metastatic disease to assure appropriate management.

The search for idiopathic scoliosis genes.

STUDY DESIGN: A cohort of 145 patients with adolescent idiopathic scoliosis (AIS) were identified and contacted to determine whether they had a family history of scoliosis. These results were submitted to an internal genealogical database to screen for potential connections to other AIS families. The severity and incidence of AIS in extended family groups were also analyzed. OBJECTIVES: Our objectives were to quantify the genetic effect in AIS, determine the expressivity and penetrance of AIS in large family groupings, and examine larger scoliosis pedigrees for evidence of multiple genes. SUMMARY OF BACKGROUND DATA: Previous reports have suggested an 80% connectedness among scoliosis families, but no clear evidence of multiple genes. It is not known if there are major gene(s). METHODS: A cohort of 145 AIS probands were identified and contacted to ascertain whether they had a family history of AIS. Their medical records and spine radiographs were reviewed to confirm the diagnosis and determine the disease severity. Using an internal genealogical database, the cases were screened for potential connections that would produce larger extended pedigrees. RESULTS: Overall, 131 of the probands were in the database and 127 showed connections to other scoliosis families, a 97% connectedness. These results suggest a major scoliosis gene, as more than 50% of the probands were connected by founders that all resided in England in the mid 1500s. The differences in penetrance (41% vs. 34%) and expressivity (38% vs. 61%) between seemingly unrelated large family groupings might suggest that two different genes are a major influence for AIS in these families. CONCLUSIONS: Nearly all (97%) AIS patients have familial origins. There appears to be at least one major gene, and the differences in penetrance and expressivity in two large unconnected pedigrees might suggest the presence of more than one gene.

Relative versus absolute modulation of growth in the fusionless treatment of experimental scoliosis.

STUDY DESIGN: Absolute and relative growth modulation of apical spinal segments were measured during creation and correction of an experimental scoliosis in a goat model. OBJECTIVE: To differentiate relative and absolute changes in growth on the concavity and convexity of an experimental scoliosis treated with anterior vertebral stapling. SUMMARY OF BACKGROUND DATA: The creation and correction of vertebral wedge deformities have been previously described in a rat tail model using external fixation as well as in a goat model using anterior vertebral body stapling. METHODS: Progressive, structural, scoliotic curves convex to the right in the thoracic spine were created in 14 Spanish Cross-X female goats using a posterior asymmetric tether. After 7-13 weeks, all tethers were removed, and goats were randomized into stapled (n = 8) and untreated (n = 6) groups. Stapled goats underwent anterior vertebral stapling with 4 shape memory alloy staples (Medtronic Sofamor Danek, Memphis, TN) along the convexity of the maximal curvature. All goats were observed for an additional 7-13 weeks. There were 12 additional goats matched for age, sex, and weight used as growth controls throughout the study. Serial radiographs were used to document progression or correction of the maximal scoliotic deformity, and changes in relative and absolute growth at the apical spinal segment T9-10 (2 adjacent vertebrae and the intervening disc). RESULTS: All tethered goats had progressive, structural, scoliotic curves of significant magnitude during the tethering period (average 61.4 degrees, range 49 degrees to 73 degrees) (P = 0.001). There was 1 goat from each group eliminated from the study because its apical spinal segment did not match the T9-10 level used to establish normal growth in controls. During the treatment period, stapled goats had a correction of -6.9 degrees (P = 0.03), whereas untreated goats had little change (-1.4 degrees). Apical spinal segment wedging progressed in all tethered goats, from 11.1 degrees to 22.4 degrees, during the tethering period (P = 0.001). During the treatment period, wedging corrected -2.2 degrees (range 22.5 degrees to 20.3 degrees) in the stapled goats but progressed +3.5 degrees (range 22.3 degrees to 25.8 degrees) in the untreated goats (P < 0.05). Apical spinal segment growth in all tethered goats was decreased on the concavity by 78% and increased on the convexity by 33% when compared to growth controls (P < 0.001). During the treatment period, growth on the concavity of the apical spinal segment of the stapled goats was decreased by 10% but increased in the untreated goats by 37% when compared to growth controls. On the convexity, apical spinal segment growth at T9-10 was decreased in the stapled goats by 18% and increased in the untreated goats by 29% when compared to growth controls (P < 0.04). CONCLUSIONS: Data in this study show the ability to modulate relative and absolute growth, according to the Hueter-Volkmann law, at the apical spinal segment of a progressive experimental scoliosis. However, anterior vertebral stapling, although able to control progressive wedging and scoliosis at the apical spinal segment, was not able to reverse fully the Hueter-Volkmann effect.