Perioperative Aspects of Endoscopic Anterior Scoliosis Surgery: The Learning Curve for a Consecutive Series of 100 Patients

Determining the learning curve for percutaneous endoscopic lumbar interbody fusion for lumbar degenerative diseases

PURPOSE

Percutaneous endoscopic lumbar interbody fusion (PELIF) is one of the least invasive procedures for lumbar degenerative disorders (LDD). There is limited knowledge of the learning curve for PELIF.

METHODS

A total of 93 consecutive patients who underwent PELIF performed by a single spine surgeon for LDD failed with conservative treatment were retrospectively reviewed. The case series was split into three groups based on timing: A (earliest third of patients); B (middle third of patients); and C (latest third of patients). The following were also recorded: operating time, X-ray exposure time, complications, radiologic fusion rates, pre- and postoperative patient-reported outcome measures (PROMs) scores (visual analogue scale (VAS) for back pain, VAS for leg pain, Japanese Orthopaedic Association, Oswestry Disability Index and MacNab criteria), length of hospital stay, and need for revision surgeries. A learning curve was then developed by a logarithmic curve-fit regression analysis.

RESULTS

The operative time gradually decreased over time, and an asymptote was reached after about 25 cases. Compared with group B or C, group A had significantly longer operative time, significantly longer length of hospital stay, needed significantly more x-ray exposure time. Though not significantly different, there are fewer complications and revision surgeries over time. There is no significant difference over time in PROMs scores except for the VAS back scores.

CONCLUSIONS

PELIF is an alternative for minimal invasive surgery for LDD, PELIF presents a learning curve to the practicing spine surgeon with regard to operative time, x-ray exposure time, length of hospital stay, clinical PROMs and radiographic outcomes and complications. The presented PELIF learning curve provided valuable insight to surgeons interested in performing this surgery.

Quantifying Anterior Chest Wall Deformity in Adolescent Idiopathic Scoliosis: Correlation With Other Deformity Measures and Effects of Anterior Thoracoscopic Scoliosis Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

This study investigated how anterior chest wall deformity is affected by thoracoscopic anterior scoliosis fusion (TASF) surgery in adolescent idiopathic scoliosis patients. We aimed to determine correlations pre- and postoperatively with other clinical and radiological scoliosis measures.

BACKGROUND DATA

Scoliosis surgery aims to halt progression of the deformity, and to reduce its severity. Currently, deformity correction is clinically measured in terms of Cobb angle and rib hump (RH); however, a significant cosmetic concern for patients is anterior chest wall deformity.

METHODS

Pre- and postoperative CT scans of 28 female, Lenke type 1 patients with a mean preoperative Cobb angle of 50.2° ± 7.1° were retrieved from the Research Group's surgical database. Using ImageJ, 3D reconstructions of the thorax were created. Two observers measured the anterior chest wall deformity as a chest wall angle (CWA) and posterior deformity as a posterior apical deformity angle (PDA). We investigated pre- to postoperative changes in CWA, PDA, RH, and Cobb angle as well as their interrelationship.

RESULTS

All deformity parameters (Cobb angle, RH, CWA, and PDA) showed statistically significant improvement post TASF. Correlation was found between RH and Cobb angle pre- and postoperatively, Cobb angle and CWA preoperatively and between postoperative change in Cobb angle and CWA. No relationship was found between CWA and RH or PDA.

CONCLUSIONS

Anterior chest wall deformity is independent from the posterior chest wall measures RH and PDA, indicating that the anterior chest wall deformity is not reflected in the posterior rib cage. The correlation between Cobb angle and CWA indicates that the deformity in the spine and the deformity in the ribs are related, and shows that the anterior chest wall deformity is improved post thoracoscopic anterior scoliosis fusion surgery as the lateral deviation of the spine is corrected.

LEVEL OF EVIDENCE

Level III.

Thoracoscopic Anterior Instrumentation and Fusion as a Treatment for Adolescent Idiopathic Scoliosis: A Systematic Review of the Literature

STUDY DESIGN

A systematic review and meta-analysis on thoracoscopic anterior instrumentation and fusion as a treatment for adolescent idiopathic scoliosis (AIS).

OBJECTIVE

The goal of this study is to determine the current status of thoracoscopic instrumentation and fusion as a treatment for AIS.

SUMMARY OF BACKGROUND DATA

Traditional surgical techniques for AIS have been open anterior thoracotomy with instrumentation and posterior spinal fusion and instrumentation. With the growing clinical interest in growth modulation surgeries, such as vertebral body tethering, there is a resurgence of interest in a thoracoscopic technique.

METHODS

The most commonly used medical databases (PubMed, Medline, EMBASE, CINAHL, and the Cochrane library) were searched up to November 2016 using the search terms VATS, thoracoscopic scoliosis, and thoracoscopic scoliosis instrumentation.

RESULTS

Thirteen studies met the strict inclusion criteria. Five hundred thirty patients were reported: 81.7% females, with the majority diagnosed as AIS. The mean operative time was 371.5 minutes, mean blood loss of 502.85 mL, and mean hospital stay of 5.9 days. Mean preoperative curve magnitude was 52.9°; postoperative curve magnitude was 17.9°, with a correction of 62.7%. Number of levels instrumented was 6.3, pulmonary function tests returned to preoperative values by 2 years postoperation, and the complication rate was 21.3%. Compared to thoracotomy, VATS had similar complication rates, blood loss, operation theater time, curve correction, and number of fused levels. Compared to posterior fusion, VATS has higher complication rates and operation theater time. Blood loss and percentage correction were similar. VATS had a smaller number of fused segments.

CONCLUSIONS

Advantages include less invasive, excellent curve correction, few levels fused, good satisfaction, and no long-term effect on pulmonary function. Drawbacks are increased operative time and incidence of pulmonary complications. With appropriate surgeon training and careful patient selection, this technique offers an acceptable alternative to the more traditional procedures.

LEVEL OF EVIDENCE

Level II.

Is vertebral rotation correction maintained after thoracoscopic anterior scoliosis surgery? A low-dose computed tomography study

Background

Axial vertebral rotation is a key characteristic of adolescent idiopathic scoliosis (AIS), and its reduction is one of the goals of corrective surgery. Recurrence of deformity after surgical correction may relate to rotation changes that occur in the anterior vertebral column after surgery, but whether any change occurs within the fused segment or in adjacent unfused levels following thoracoscopic anterior spinal fusion (TASF) is unknown. An analysis of measurements from an existing postoperative CT dataset was performed to investigate the occurrence of inter- and intra-vertebral rotation changes after TASF within and adjacent to the fused spinal segment and look for any relationships with the Cobb angle and rib hump in the two years after surgery.

Methods

39 Lenke Type 1 main thoracic patients underwent TASF for progressive AIS and low dose computed tomography scanning of the instrumented levels of the spine at 6 and 24 months after surgery. Vertebral rotation was measured at the superior and inferior endplates on true axial images for all vertebral levels in the fused segment plus one adjacent level cranially and caudally. Intra-observer variability for rotation measurements was assessed using 95% limits of agreement to detect significant changes in inter/intra-vertebral rotation.

Results

Significant local changes in inter- and intra-vertebral rotation were found to have occurred between 6 and 24 months after anterior surgical fusion within the fused spinal segment, albeit with no consistent pattern of location or direction within the instrumented fusion construct. No significant en-bloc movement of the entire fused spinal segment relative to the adjacent un-instrumented cranial and caudal intervertebral levels was found. No clear correlation was found between any vertebral rotation changes and Cobb angle or rib hump measures.

Conclusions

Localised inter- and intra-vertebral rotation occurs between 6 and 24 months after TASF, both within the instrumented spinal segments and in the adjacent un-instrumented levels of the adolescent spine. The lack of measurable en-bloc movement of the fused segment relative to the adjacent un-instrumented levels suggests that overall stability of the instrumented construct is achieved, however the vertebrae within the fusion mass continue to adapt and remodel, resulting in ongoing local anatomical and biomechanical changes in the adolescent spine.

Change in Lung Volume Following Thoracoscopic Anterior Spinal Fusion Surgery: A 3-Dimensional Computed Tomography Investigation

STUDY DESIGN

Lung volumes and thoracic anatomy were measured from low-dose computed tomography (CT) scans preoperatively and 2 years following thoracoscopic anterior spinal fusion (TASF) for adolescent idiopathic scoliosis (AIS).

OBJECTIVE

The aim of this study was to assess changes in lung volume after TASF surgical correction.

SUMMARY OF BACKGROUND DATA

AIS patients are known to have decreased pulmonary function as a consequence of their spinal and ribcage deformity. Several studies have evaluated changes in pulmonary function clinically after scoliosis correction surgery showing varied results. To date, there have been no published studies using CT to evaluate lung volume changes following TASF.

METHODS

Twenty-three female AIS patients with both pre- and 2 years postoperative low-dose CT scans were selected from an ethically approved, historical databank. Three-dimensional lung volumes were reconstructed to determine anatomical lung volumes. Right and left lung volumes, total lung volume, and right-to-left lung volume ratio were obtained as well as hemithoracic symmetry, to indicate the extent of thorax deformity. Cobb angle, rib hump, levels fused in surgery, and patient height were used for correlation analysis with the lung volume results.

RESULTS

Left lung volume, total lung volume, and hemithoracic ratio all increased significantly 2 years after surgery. There was no significant change in right-to-left lung volume ratio (P = 0.36). Statistical regression found significant positive correlation between lung volume changes, reduction in Cobb angle, increase in height, and improvement in hemithoracic symmetry ratio.

CONCLUSION

TASF resulted in a statistically significant increase in lung volume following surgery, as well as improvement in the symmetry of the thoracic architecture; however, the postoperative lung volumes remained in the lower 50th percentile relative to females without thoracic deformity. Furthermore, change in lung volume was significantly correlated with changes in Cobb angle, hemithoracic asymmetry, and increased patient height, which are important consequences of thoracic deformity correction surgery.

LEVEL OF EVIDENCE

3.

Evaluating the Change in Axial Vertebral Rotation Following Thoracoscopic Anterior Scoliosis Surgery Using Low-Dose Computed Tomography

BACKGROUND CONTEXT

In recent years, there has been increasing appreciation of the need to treat scoliosis as a three-dimensional deformity.

PURPOSE

Assessment of surgical strategies and outcomes should consider not only the coronal plane correction but also derotation of the transverse plane deformity that can affect trunk appearance.

STUDY DESIGN

This study included a cohort of 29 female adolescent idiopathic scoliosis patients who received thoracoscopic single rod anterior fusion (TASF) surgery. This study used pre- and postoperative low-dose computed tomographic (CT) scans to accurately measure apical axial vertebral rotation (AVR).

METHODS

The pre- and postoperative values for clinically measured coronal Cobb correction and rib hump correction as well as AVR were compared to determine whether these values improved postoperatively. There are no conflicts of interest to report for authors of this investigation.

RESULTS

As expected, statistically significant reductions in coronal Cobb angle (mean preoperative Cobb 51°, reducing to 24° at the two-year follow-up) and rib hump (mean preoperative rib hump 15°, reducing to 7° at two-year follow-up) were achieved. The mean reduction in apical AVR measured using CT was only 3° (mean preoperative AVR 16°, reducing to 13° at two-year follow-up), which was statistically but not clinically significant. Significant correlations were found between Cobb angle and rib hump, between Cobb angle and AVR, and between AVR and rib hump, suggesting that patients with greater coronal Cobb correction also achieve better derotation with this surgical procedure.

CONCLUSIONS

The historical low-dose CT data set permitted detailed three-dimensional assessment of the deformity correction that is achieved using thoracoscopic anterior spinal fusion for progressive adolescent idiopathic scoliosis.

Quantitative analysis of a spinal surgeon’s learning curve for scoliosis surgery

Aims

The aim of this study was a quantitative analysis of a surgeon’s learning curve for scoliosis surgery and the relationship between the surgeon’s experience and post-operative outcomes, which has not been previously well described.

Patients and Methods

We have investigated the operating time as a function of the number of patients to determine a specific pattern; we analysed factors affecting the operating time and compared intra- and post-operative outcomes. We analysed 47 consecutive patients undergoing scoliosis surgery performed by a single, non-trained scoliosis surgeon. Operating time was recorded for each of the four parts of the procedures: dissection, placement of pedicle screws, reduction of the deformity and wound closure.

Results

The median operating time was 310 minutes (interquartile range 277.5 to 432.5). The pattern showed a continuous decreasing trend in operating time until the patient number reached 23 to 25, after which it stabilised with fewer patient-dependent changes. The operating time was more affected by the patient number (r =- 0.75) than the number of levels fused (r = 0.59). Blood loss (p = 0.016) and length of stay in hospital (p = 0.012) were significantly less after the operating time stabilised. Post-operative functional outcome scores and the rate of complications showed no significant differences. Take home message: We describe a detailed learning curve for scoliosis surgery based on a single surgeon’s practise, providing useful information for novice scoliosis surgeons and for those responsible for training in spinal surgery. Cite this article: Bone Joint J 2016;98-B:679–85.

Partial Intervertebral Fusion Secures Successful Outcomes After Thoracoscopic Anterior Scoliosis Correction: A Low-Dose Computed Tomography Study

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVES

To analyze intervertebral (IV) fusion after thoracoscopic anterior spinal fusion (TASF) and explore the relationship between fusion scores and key clinical variables.

SUMMARY OF BACKGROUND INFORMATION

TASF provides comparable correction with some advantages over posterior approaches but reported mechanical complications, and their relationship to non-union and graft material is unclear. Similarly, the optimal combination of graft type and implant stiffness for effecting successful radiologic union remains undetermined.

METHODS

A subset of patients from a large single-center series who had TASF for progressive scoliosis underwent low-dose computed tomographic scans 2 years after surgery. The IV fusion mass in the disc space was assessed using the 4-point Sucato scale, where 1 indicates <50% and 4 indicates 100% bony fusion of the disc space. The effects of rod diameter, rod material, graft type, fusion level, and mechanical complications on fusion scores were assessed.

RESULTS

Forty-three patients with right thoracic major curves (mean age 14.9 years) participated in the study. Mean fusion scores for patient subgroups ranged from 1.0 (IV levels with rod fractures) to 2.2 (4.5-mm rod with allograft), with scores tending to decrease with increasing rod size and stiffness. Graft type (autograft vs. allograft) did not affect fusion scores. Fusion scores were highest in the middle levels of the rod construct (mean 2.52), dropping off by 20% to 30% toward the upper and lower extremities of the rod. IV levels where a rod fractured had lower overall mean fusion scores compared to levels without a fracture. Mean total Scoliosis Research Society (SRS) questionnaire scores were 98.9 from a possible total of 120, indicating a good level of patient satisfaction.

CONCLUSIONS

Results suggest that 100% radiologic fusion of the entire disc space is not necessary for successful clinical outcomes following thoracoscopic anterior selective thoracic fusion.

Biological performance of a polycaprolactone-based scaffold plus recombinant human morphogenetic protein-2 (rhBMP-2) in an ovine thoracic interbody fusion model

PURPOSE

We develop a sheep thoracic spine interbody fusion model to study the suitability of polycaprolactone-based scaffold and recombinant human bone morphogenetic protein-2 (rhBMP-2) as a bone graft substitute within the thoracic spine. The surgical approach is a mini-open thoracotomy with relevance to minimally invasive deformity correction surgery for adolescent idiopathic scoliosis. To date there are no studies examining the use of this biodegradable implant in combination with biologics in a sheep thoracic spine model.

METHODS

In the present study, six sheep underwent a 3-level (T6/7, T8/9 and T10/11) discectomy with randomly allocated implantation of a different graft substitute at each of the three levels: (a) calcium phosphate (CaP) coated polycaprolactone-based scaffold plus 0.54 μg rhBMP-2 (b) CaP-coated PCL-based scaffold alone or (c) autograft (mulched rib head). Fusion was assessed at 6 months post-surgery.

RESULTS

Computed Tomographic scanning demonstrated higher fusion grades in the rhBMP-2 plus PCL-based scaffold group in comparison with either PCL-based scaffold alone or autograft. These results were supported by histological evaluations of the respective groups. Biomechanical testing revealed significantly higher stiffness for the rhBMP-2 plus PCL-based scaffold group in all loading directions in comparison with the other two groups.

CONCLUSION

The results of this study demonstrate that rhBMP-2 plus PCL-based scaffold is a viable bone graft substitute, providing an optimal environment for thoracic interbody spinal fusion in a large animal model.

Postoperative pain relief using intermittent intrapleural analgesia following thoracoscopic anterior correction for progressive adolescent idiopathic scoliosis

Background

Thoracoscopic anterior scoliosis instrumentation is a safe and viable surgical option for corrective fusion of progressive adolescent idiopathic scoliosis (AIS) and has been performed at our centre on 205 patients since 2000. However, there is a paucity of literature reporting on or examining optimum methods of analgesia following this type of surgery. A retrospective study was designed to present the authors’ technique for delivering intermittent local anaesthetic boluses via an intrapleural catheter following thoracoscopic scoliosis surgery; report the pain levels that may be expected and any adverse effects associated with the use of intrapleural analgesia, as part of a combined postoperative analgesia regime.

Methods

Records for 32 patients who underwent thoracoscopic anterior correction for AIS were reviewed. All patients received an intrapleural catheter inserted during surgery, in addition to patient-controlled opiate analgesia and oral analgesia. After surgery, patients received a bolus of 0.25% bupivacaine every four hours via the intrapleural catheter. Patient’s perceptions of their pain control was measured using the visual analogue pain scale scores which were recorded before and after local anaesthetic administration and the quantity and time of day that any other analgesia was taken, were also recorded.

Results

28 female and four male patients (mean age 14.5 ± 1.5 years) had a total of 230 boluses of local anaesthetic administered in the 96 hour period following surgery. Pain scores significantly decreased following the administration of a bolus (p < 0.0001), with the mean pain score decreasing from 3.66 to 1.83. The quantity of opiates via patient-controlled analgesia after surgery decreased steadily between successive 24 hours intervals after an initial increase in the second 24 hour period when patients were mobilised. One intrapleural catheter required early removal due to leakage; there were no other associated complications with the intermittent intrapleural analgesia method.

Conclusions

Local anaesthetic administration via an intrapleural catheter is a safe and effective method of analgesia following thoracoscopic anterior scoliosis correction. Post-operative pain following anterior thoracic scoliosis surgery can be reduced to ‘mild’ levels by combined analgesia regimes.

Learning curve for percutaneous endoscopic lumbar discectomy depending on the surgeon's training level of minimally invasive spine surgery

PURPOSE

To evaluate the differences of learning curve for PELD depending on the surgeon' s training level of minimally invasive spine surgery.

METHODS

We retrospectively reviewed the medical records of 120 patients (surgeon A with his first 60 patients, surgeon B with his first 60 patients) with sciatica and single-level L4/5 disk herniation who underwent PELD by the two surgeons with different training level of minimally invasive spine surgery (Group A: surgeon with little professional training of PELD; Group B: surgeon with 2 years of demonstration teaching of PELD).

RESULTS

Significant differences were observed in the operation time (p=0.000), postoperative hospital stay (p=0.026) and reoperation rate (p=0.050) between the two groups. In the operation time, significant differences were observed between the 1-20 patients group and 41-60 patients group in Group B (p=0.041), but there were no significant differences among the 1-20 patients group, 21-40 patients group and 41-60 patients group in Group A. In the postoperative hospital stay, the significant differences were observed in the 1-20 patients group between Group A and Group B (p=0.011). Significant differences were observed between preoperative and postoperative VAS back score, VAS leg score and JOA score. Higher improvement in the VAS leg score was observed in Group B than Group A (p=0.031). In the rate of reoperation, the significant difference was observed between the 1-20 patients group and 41-60 patients group in Group A (p=0.028) but there were no significant differences among the 1-20 patients group, 21-40 patients group and 41-60 patients group in Group B.

CONCLUSIONS

The surgeons' training level of minimally invasive spine surgery was an important factor for the success of PELD, especially the demonstration teaching of PELD for the new minimally invasive spine surgeons.

Secondary curve behavior in Lenke type 1C adolescent idiopathic scoliosis after thoracoscopic selective anterior thoracic fusion

STUDY DESIGN

Analysis of a case series of 24 patients with Lenke 1C adolescent idiopathic scoliosis (AIS) receiving selective thoracoscopic anterior scoliosis correction.

OBJECTIVE

To report the behavior of the compensatory lumbar curve in a group of patients with Lenke IC AIS after thoracoscopic anterior scoliosis correction and to compare the results of this study with previously published data.

SUMMARY OF BACKGROUND DATA

Several prior studies have reported spontaneous lumbar curve correction for both anterior and posterior selective fusions in patients with Lenke 1C/King-Moe 2; however, to our knowledge no previous studies have reported outcomes of thoracoscopic anterior correction for this curve type.

METHODS

All patients with AIS with a curve classification of Lenke 1C and a minimum of 24-month follow-up were obtained from a consecutive series of 190 patients with AIS who underwent thoracoscopic anterior instrumented fusion. Cobb angles of the major curve, instrumented levels, compensatory lumbar curve, and T5-T12 kyphosis were recorded, as well as coronal spinal balance, T1 tilt angle, and shoulder balance. All radiographical parameters were measured before surgery and at 2, 6, 12, and 24 months after surgery.

RESULTS

Twenty-four female patients with right thoracic curves had a mean thoracic Cobb angle of 53.0° before surgery, decreasing to 24.9° 2 years after surgery. The mean lumbar compensatory Cobb angle was 43.5° before surgery, spontaneously correcting to 25.4° 2 years after surgery, indicating balance between the thoracic and lumbar scoliotic curves. The lumbar correction achieved (41.8%) compares favorably to previous studies.

CONCLUSION

Selective thoracoscopic anterior fusion allows spontaneous lumbar curve correction and achieves coronal balance of main thoracic and compensatory lumbar curves, good cosmesis, and patient satisfaction. Correction and balance are maintained 24 months after surgery.

CT and radiographic analysis of sagittal profile changes following thoracoscopic anterior scoliosis surgery

Background

Previous studies report an increase in thoracic kyphosis after anterior approaches and a flattening of sagittal contours following posterior approaches. Difficulties with measuring sagittal parameters on radiographs are avoided with reformatted sagittal CT reconstructions due to the superior endplate clarity afforded by this imaging modality.

Methods

A prospective study of 30 Lenke 1 adolescent idiopathic scoliosis (AIS) patients receiving selective thoracoscopic anterior spinal fusion (TASF) was performed. Participants had ethically approved low dose CT scans at minimum 24 months after surgery in addition to their standard care following surgery. The change in sagittal contours on supine CT was compared to standing radiographic measurements of the same patients and with previous studies. Inter-observer variability was assessed as well as whether hypokyphotic and normokyphotic patient groups responded differently to the thoracoscopic anterior approach.

Results

Mean T5-12 kyphosis Cobb angle increased by 11.8 degrees and lumbar lordosis increased by 5.9 degrees on standing radiographs two years after surgery. By comparison, CT measurements of kyphosis and lordosis increased by 12.3 degrees and 7.0 degrees respectively. 95% confidence intervals for inter-observer variability of sagittal contour measurements on supine CT ranged between 5-8 degrees. TASF had a slightly greater corrective effect on patients who were hypokyphotic before surgery compared with those who were normokyphotic.

Conclusions

Restoration of sagittal profile is an important goal of scoliosis surgery, but reliable measurement with radiographs suffers from poor endplate clarity. TASF significantly improves thoracic kyphosis and lumbar lordosis while preserving proximal and distal junctional alignment in thoracic AIS patients. Supine CT allows greater endplate clarity for sagittal Cobb measurements and linear relationships were found between supine CT and standing radiographic measurements. In this study, improvements in sagittal kyphosis and lordosis following surgery were in agreement with prior anterior surgery studies, and add to the current evidence suggesting that anterior correction is more capable than posterior approaches of addressing the sagittal component of both the instrumented and adjacent non instrumented segments following surgical correction of progressive Lenke 1 idiopathic scoliosis.

Is there a learning curve in foot and ankle surgery?

BACKGROUND

Previous studies of orthopaedic learning curves have largely described the introduction of new techniques to experienced consultants. End points have usually involved technical considerations. A paucity of evidence surrounds foot and ankle surgery. This study investigates the learning curve during a foot and ankle surgeon's first year, defined by functional outcome.

METHODS

150 patients underwent elective foot or ankle surgery during the whole period. Preoperative and 6 month postoperative functional scores were compared between the first and second 6 month groups.

RESULTS

Functional improvement was greater, approaching significance, in the second group (p=0.0605). There was no difference for forefoot cases (p=0.345). Functional improvement was significantly greater in the second group with forefoot cases removed (p=0.0333).

CONCLUSIONS

A learning curve exists in the first year of practice of foot and ankle surgery, demonstrated by functional outcome. This is confined to ankle, hindfoot and midfoot, but not forefoot surgery.

The relationship between deformity correction and clinical outcomes after thoracoscopic scoliosis surgery: a prospective series of one hundred patients

STUDY DESIGN

Prospective clinical case series of 100 patients receiving thoracoscopic anterior scoliosis correction.

OBJECTIVE

To evaluate the relationship between clinical outcomes of thoracoscopic anterior scoliosis surgery and deformity correction, using the Scoliosis Research Society (SRS) outcomes instrument.

SUMMARY OF BACKGROUND DATA

Surgical treatment of scoliosis is quantitatively assessed in the clinic, using radiographic measures of deformity correction and the rib hump, but it is important to understand the extent to which these quantitative measures correlate with self-reported improvements in patients' quality of life after surgery.

METHODS

A series of 100 consecutive adolescent idiopathic scoliosis patients received a single anterior rod via a thoracoscopic approach at the Mater Children's Hospital, Brisbane, Australia. Patients completed SRS outcomes questionnaires before surgery and at 24 months after surgery. Multiple regression and t tests were used to investigate the relationship between SRS scores and deformity correction achieved (radiographic measurements and rib hump) after surgery.

RESULTS

There were 94 females and 6 males with a mean age of 16.1 years. The mean Cobb angle improved from 52° before surgery to 25° after surgery (52%) and the mean rib hump improved from 16° to 8° (51%). The mean total SRS score for the cohort was 99.4/120. None of the deformity-related parameters in the multiple-regression were significant. However, patients with the lowest postoperative major Cobb angles reported significantly higher SRS scores than those with the highest postoperative Cobb angles, but there was no difference on the basis of rib hump correction. There were no significant differences between patients with either rod fractures or screw-related complications compared to those without complications.

CONCLUSION

Patients undergoing thoracoscopic anterior scoliosis correction reported good SRS scores which are comparable with those in previous studies. Postoperative major Cobb angle is a significant predictor of patient satisfaction when comparing subgroups of patients with the highest and lowest postoperative Cobb angles.

Virtual reality in orthopaedics: is it a reality?

BACKGROUND

Virtual reality (VR) simulation has been a requirement for airline and military pilots for decades and is only now being integrated into surgical training programs. Thus far, orthopaedic training programs have been slow to adopt VR training.

QUESTIONS/PURPOSES

We therefore asked (1) how VR has worked for other surgical specialties; (2) what VR solutions are available for orthopaedics; and (3) should VR simulation become part of the orthopaedic curriculum?

METHODS

An informal literature review was performed, searching for orthopaedically-oriented VR surgical simulators and comparing this to the number of programs available for general surgery teaching programs. An in-depth review of a VR simulator for knee arthroscopy is also presented. WHERE ARE WE NOW?: The number of papers specific to orthopaedics and VR is limited. VR is used effectively in other specialties, especially general surgery. VR simulators are readily available for shoulder and knee arthroscopy but not as well incorporated into training curricula. WHERE DO WE NEED TO GO?: VR technology is available today for training programs. Integration of VR into the orthopaedic curriculum will save time in the OR, reduce operative errors, and improve the resident's overall educational experience. The public will expect their surgeons to train on these simulators. HOW DO WE GET THERE?: Orthopaedic training programs should take advantage of the commercially available VR simulators for orthopaedic procedures and incorporate them into their training curricula. This effort could be led by the American Academy of Orthopaedic Surgeons (AAOS) and the American Board of Orthopaedic Surgery (ABOS), two of the primary sponsors of a major study in the effectiveness of VR simulators for knee arthroscopy.

A biomechanical study of top screw pullout in anterior scoliosis correction constructs

STUDY DESIGN.: Biomechanical testing of vertebral body screw pullout resistance with relevance to top screw pullout in thoracoscopic anterior scoliosis constructs.

OBJECTIVE

To analyze the effect of screw positioning and angulation on pullout resistance of vertebral body screws, where the pullout takes place along a curved path as occurs in anterior scoliosis constructs.

SUMMARY OF BACKGROUND DATA

Top screw pullout is a significant clinical problem in thoracoscopic anterior scoliosis surgery, with rates of up to18% reported in the literature.

METHODS

A custom-designed biomechanical test rig was used to perform pullout tests of Medtronic anterior vertebral screws where the pullout occurred along an arc of known radius. Using synthetic bone blocks, a range of pullout radiuses and screw angulations were tested, in order to determine an "optimal" configuration. The optimal configuration was then compared with standard screw positioning using a series of tests on ovine vertebrae (n=29).

RESULTS

Screw angulation has a small but significant effect on pullout resistance, with maximum strength being achieved at 10-degree cephalad angulation. Combining 10-degree cephalad angulation with maximal spacing between the top 2 screws (maximum pullout radius) increased the pullout resistance by 88% compared with "standard" screw positioning (screws inserted perpendicular to rod at midbody height).

CONCLUSION

The positioning of the top screw in anterior scoliosis constructs can significantly alter its pullout resistance.

Lateral bone density variations in the scoliotic spine

Adolescent Idiopathic Scoliosis (AIS) is the most common deformity of the spine, affecting 2-4% of the population. Previous studies have shown that the vertebrae in scoliotic spines undergo abnormal shape changes, however there has been little exploration of how scoliosis affects bone density distribution within the vertebrae. In this study, existing CT scans of 53 female idiopathic scoliosis patients with right-sided main thoracic curves were used to measure the lateral (right to left) bone density profile at mid-height through each vertebral body. Five key bone density profile measures were identified from each normalized bone density distribution, and multiple regression analysis was performed to explore the relationship between bone density distribution and patient demographics (age, height, weight, body mass index (BMI), skeletal maturity, time since Menarche, vertebral level, and scoliosis curve severity). Results showed a marked convex/concave asymmetry in bone density for vertebral levels at or near the apex of the scoliotic curve. At the apical vertebra, mean bone density at the left side (concave) cortical shell was 23.5% higher than for the right (convex) cortical shell, and cancellous bone density along the central 60% of the lateral path from convex to concave increased by 13.8%. The centre of mass of the bone density profile at the thoracic curve apex was located 53.8% of the distance along the lateral path, indicating a shift of nearly 4% toward the concavity of the deformity. These lateral bone density gradients tapered off when moving away from the apical vertebra. Multi-linear regressions showed that the right cortical shell peak bone density is significantly correlated with skeletal maturity, with each Risser increment corresponding to an increase in mineral equivalent bone density of 4-5%. There were also statistically significant relationships between patient height, weight and BMI, and the gradient of cancellous bone density along the central 60% of the lateral path. Bone density gradient is positively correlated with weight, and negatively correlated with height and BMI, such that at the apical vertebra, a unit decrease in BMI corresponds to an almost 100% increase in bone density gradient.

Radiographic outcomes over time after endoscopic anterior scoliosis correction: a prospective series of 106 patients

STUDY DESIGN

A prospective, consecutive series of 106 patients receiving endoscopic anterior scoliosis correction.

OBJECTIVE

To analyze changes in radiographic parameters and rib hump in the 2 years after surgery.

SUMMARY OF BACKGROUND DATA

Endoscopic anterior scoliosis correction is a level sparing approach and therefore, it is important to assess the amount of decompensation which occurs after surgery.

METHODS

All patients received a single anterior rod and vertebral body screws using a standard compression technique. Cleared disc spaces were packed with either mulched femoral head allograft or rib head/iliac crest autograft. Radiographic parameters (major, instrumented, minor Cobb, T5-T12 kyphosis) and rib hump were measured at 2, 6, 12, and 24 months after surgery. Paired t tests and Wilcoxon signed ranks tests were used to assess the statistical significant of changes between adjacent time intervals.

RESULTS

Mean loss of major curve correction from 2 to 24 months after surgery was 4 degrees. Mean loss of rib hump correction was 1.4 degrees. Mean sagittal kyphosis increased from 27 degrees at 2 months to 30.6 degrees at 24 months. Rod fractures and screw-related complications resulted in several degrees less correction than patients without complications, but overall there was no clinically significant decompensation after complications.

CONCLUSION

There are small changes in deformity measures after endoscopic anterior scoliosis surgery, which are statistically significant but not clinically significant.

A century of spine surgery: what can patients expect?

PURPOSE

To evaluate the hypothesis that spinal fusion surgery is an effective method to address spinal deformity-associated clinical problems, including magnitude of curvature (Cobb angle), pulmonary dysfunction, and pain.

METHOD

A systematic review was carried out using Science Citation Index (SCI) Expanded (1900 - present), Social Sciences Citation Index (1956 - present), Arts and Humanities Citation Index (1965 - present), Medline (1950 - present) and PubMed Central databases (1887 - present) to access information regarding efficacy of spine surgery in preventing or improving the health and function of patients diagnosed with scoliosis in adolescence.

RESULTS

Since 1950, more than 12,600 articles on scoliosis have been published, and nearly 50% (5721) focus on methods, rationale, outcome, and complications of surgical intervention. Among these, 82 articles have documented outcome for groups of > or =10 patients, treated for adolescent idiopathic scoliosis, and followed for at least 2 years after treatment. These data provide an overview of the impact of spine surgery on scoliosis for 5780 patients as surgery methods and approaches have evolved.

CONCLUSIONS

For most patients, a reduced magnitude of spinal curvature can be achieved through one or more spinal fusion surgeries. There is no evidence to support the premise that this result is correlated with improved pulmonary function or reduced pain.

The use of fulcrum bending radiographs in anterior thoracic scoliosis correction: a consecutive series of 90 patients

STUDY DESIGN

A prospective, consecutive series of 90 patients receiving fulcrum bending radiographs before endoscopic anterior scoliosis correction.

OBJECTIVE

To assess the effectiveness of fulcrum bending radiographs in predicting correction of the structural curve in anterior scoliosis surgery for a series of 90 consecutive patients.

SUMMARY OF BACKGROUND DATA

The fulcrum bending radiograph is highly predictive of scoliosis curve correction for posterior instrumented fixation. However, its use has been questioned in relation to anterior scoliosis surgery due to the disc removal in anterior procedures.

METHODS

Fulcrum bending radiographs were performed before endoscopic anterior scoliosis correction following the protocol of Cheung and Luk. All patients received a single anterior rod and vertebral body screws using a standard compression technique. In all cases, cleared disc spaces were packed with mulched femoral head allograft. Surgical correction was assessed using 6- to 8-week postoperative standing radiographs. Paired t tests and least squares linear regression analysis were used to compare the preoperative major Cobb angle achieved on the fulcrum bending radiograph with the postoperative Cobb angles for each patient.

RESULTS

Mean (+/-SD) major curve correction rate was 60.1% +/- 12.4%. Mean instrumented curve correction rate was 63.7% +/- 11.7%. Mean fulcrum flexibility was 60.8% +/- 15.5%. Mean fulcrum bending correction index was 104%. There was no statistically significant difference between the mean fulcrum bending radiograph Cobb angle (20.4 +/- 9 degrees) and the mean postoperative major Cobb angle for the structural curve (20.5 +/- 7.1 degrees).

CONCLUSION

The results of this study show that fulcrum bending radiographs are predictive of surgical correction for anterior scoliosis surgery.