Intraoperative Distraction Research Articles

Intraoperative Distraction Device for Open Reduction of Nascent Lateral Humeral Condylar Fractures in Five Dogs

AbstractLateral humeral condylar (LHC) nascent malunion fractures are challenging to treat because of extensive callus formation, scar tissue and contracture of surrounding tissues. The objective of this retrospective case series is to describe the novel procedural use of an intraoperative distraction device to aid in the reduction and anatomical alignment of nascent malunion LHC fractures along with long-term functional outcomes in these cases. Medical records of five consecutive cases of dogs with seven nascent malunion LHC fractures that were treated between 2015 and 2018 with the aid of an intraoperative distraction device were reviewed. Relevant clinical and radiographic data, forelimb circumference, elbow goniometry and clinical outcome were evaluated. Anatomic reduction and fixation with complete healing were achieved in all seven cases. Implants were removed in four cases to resolve persisting lameness. Three dogs (4 cases) were available for long-term follow-up: mean circumference and range of motion were decreased in the operated limbs as compared with the contralateral normal limbs. One dog (with bilateral fractures) was euthanized due to poor outcome. In the other five elbows, outcome was acceptable. Based on the results of this case series, use of an intraoperative distraction device to aid in anatomical reduction and fixation of nascent malunion LHC fractures should be considered.

Poster 142: Capsular Repair Demonstrates Similar Restoration of Resistance to Axial Distraction in Interportal and Periportal Capsulotomies: An In Vivo Propensity Matched Cohort Study

Objectives: Hip arthroscopy has become increasingly prevalent in the United States for treating young adult hip disorders. The periportal capsulotomy, in comparison to the interportal capsulotomy, has been proposed as a technique for decreasing post-arthroscopy hip instability; however, the effects of this technique are largely theoretical. The objectives of this study were to compare the intraoperative distraction profiles of hip arthroscopy patients undergoing interportal versus periportal capsulotomies. The authors hypothesized the periportal capsulotomy would demonstrate greater resistance to axial distraction at both 1) the capsulotomy and 2) final capsular repair, when compared to the interportal capsulotomy. Methods: Patients undergoing primary hip arthroscopy by a single surgeon underwent intraoperative axial distraction testing at 25-, 50-, 75-, and 100-pounds force with each axial distraction distance measured by standardized, normalized fluoroscopic evaluation. Demographics, hip radiographic characteristics, and distraction distance measurements were collected on patients undergoing periportal capsulotomy and on a historical control group undergoing an interportal capsulotomy (Figure 1). Propensity matching was conducted using native state distraction, lateral center edge angle, and gender as covariate to achieve balance between groups. Between group comparisons were then conducted across the matched interportal and periportal groups. Student’s T-test for continuous variables and the Fisher exact test for categorical variables. Intragroup comparison was conducted across three capsule states: native, capsulotomy, and repair. Sequential testing of capsular states for each patient was conducted with the paired T-test. Results: Seventy-four interportal capsulotomies and 122 periportal capsulotomies were identified. Propensity matching yielded 74 hips in each group with standard mean differences of <0.03. Demographic and radiographic characteristics were similar between matched cohorts (p > 0.05) (Table 1). Distraction distances were similar between the interportal and periportal groups in both the capsulotomy and repair states (p > 0.05), while the periportal capsulotomy repair demonstrated decreased hip distraction distance when compared to the native state by 1.48mm at 75lbf and 1.54mm at 100lbf (p < 0.001) (Figure 2). Conclusions: The present study demonstrates that periportal capsulotomy and interportal capsulotomy have similar effects on in vivo hip distractibility. An unrepaired interportal capsulotomy led to an increase in hip distraction of 2.71 mm at 100 lbf (p < 0.001) compared to the native state, while an unrepaired periportal capsulotomy led to an increase in hip distraction of 2.44 mm at 100 lbf (p < 0.001). The periportal capsulotomy technique has been discussed as having the unique advantage of not fully disrupting the iliofemoral ligament and therefore potentially not require a repair; however, the results of the present study indicate that it is biomechanically similar to the interportal capsulotomy in the unrepaired state. Although this finding does not definitively establish a need for capsular repair in all cases when utilizing a periportal capsulotomy, if the surgeon wishes to re-establish native biomechanics, repair should be considered. The present study establishes the in vivo, intraoperative biomechanics of the periportal capsulotomy, for which there were previously no available data. Further, this study establishes that although periportal capsulotomy is a minimally disruptive technique, it has a substantial effect on in-vivo, intraoperative hip stability as measured by hip distraction distance as a result of axial traction forces. While this paper is able to address the biomechanics at the time of surgery, this paper cannot make any conclusions about the healing potential of the capsule when comparing an interportal and a periportal capsulotomy. In conclusion, an unrepaired periportal capsulotomy and interportal capsulotomy have a similar effect on increasing hip axial distraction distance intra-operatively. Performing a capsular repair restores intra- operative resistance to axial distraction in both the periportal and interportal capsulotomy. [Table: see text]

Mechanical Failures in Magnetic Intramedullary Lengthening Nails.

Magnetic intramedullary lengthening nails (MILNs) have gained popularity in recent years for the treatment of limb-lengthening discrepancies. We sought to catalog mechanical failures and their prevention and management in a large, single-institution series. We specifically assessed the rate of mechanical failures, the types of failures observed, and management strategies. We retrospectively reviewed 377 patients (420 limbs) who underwent limb lengthening with early (P1) or later (P2) MILN iterations with ≥12-month follow-up. Mechanical failure was defined as mechanical breakage of the instrumentation or nail and/or failure of the internal lengthening mechanism. Failure assessment was arranged by lengthening phases and was sorted with a complication classification system. All lengthening and alignment parameters were assessed radiographically. Mechanical failure was observed in 40 nails (9.5%), most of which (63%) were corrected with an additional surgical procedure. The mechanical failure rate was 11.3% in P1 nails and 9% in P2 nails. Two nails failed the intraoperative distraction test, and 1 nail was found to have a broken washer during the insertion phase. Sixteen nails had mechanical failures in the lengthening phase. Some nails (8 of 16) required nail replacement surgery. Thirteen nails failed during the consolidation phase; 7 of these cases were managed by replacement with either a functional MILN or a conventional intramedullary nail. Eight failures happened during the extraction phase and were managed intraoperatively. A 9.5% overall rate of mechanical failure of MILNs was observed in this large series. Resolution was achieved with an additional surgery in most cases. Nail distraction and weight-bearing compliance should be closely monitored during the lengthening and consolidation phases. Nail removal can be difficult and requires a careful study of radiographs for locking-screw bone overgrowth and backup removal equipment. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Hounsfield Unit Value with Conventional Computed Tomography and Intraoperative Distraction on Postoperative Intervertebral Height Reduction in Patients Following Stand-Alone Anterior Cervical Discectomy and Fusion.

ObjectiveThe most common complication of anterior cervical discectomy and fusion (ACDF) is cage subsidence and maintenance of disc height affects postoperative clinical outcomes. We considered cage subsidence as an inappropriate indicator for evaluating preservation of disc height. Thus, this study aimed to consider patients with complications such as reduced total disc height compared to that before surgery and evaluate the relevance of several factors before ACDF. MethodsWe retrospectively reviewed the medical records of 40 patients who underwent stand-alone single-level ACDF using a polyetheretherketone (PEEK) cage at our institution between January 2012 and December 2018. Our study population comprised 19 male and 21 female patients aged 24–70 years. The minimum follow-up period was 1 year. Twenty-seven patients had preoperative bone mineral density (BMD) data on dual-energy X-ray absorptiometry. Clinical parameters included sex, age, body mass index, smoking history, and prior medical history. Radiologic parameters included the C2-7 cobb angle, segmental angle, sagittal vertical axis, disc height, and total intervertebral height (TIH) at the preoperative and postoperative periods. Cage decrement was defined as the reduction in TIH at the 6-month follow-up compared to preoperative TIH. To evaluate the bone quality, Hounsfield unit (HU) value was calculated in the axial and sagittal images of conventional computed tomography. ResultsLumbar BMD values and cervical HU values were significantly correlated (r=0.733, p<0.001). We divided the patients into two groups based on cage decrement, and 47.5% of the total patients were regarded as cage decrement. There were statistically significant differences in the parameters of measuring the HU value of the vertebra and intraoperative distraction between the two groups. Using these identified factors, we performed a receiver operating characteristic (ROC) curve analysis. Based on the ROC curve, the cut-off point was 530 at the HU value of the upper cortical and cancellous vertebrae (p=0.014; area under the curve [AUC], 0.727; sensitivity, 94.7%; specificity, 42.9%) and 22.41 at intraoperative distraction (p=0.017; AUC, 0.722; sensitivity, 85.7%; specificity, 57.9%). Using this value, we converted these parameters into a bifurcated variable and assessed the multinomial regression analysis to evaluate the risk factors for cage decrement in ACDF. Intraoperative distraction and HU value of the upper vertebral body were independent factors of postoperative subsidence. ConclusionInsufficient intraoperative distraction and low HU value showed a strong relationship with postoperative intervertebral height reduction following single stand-alone PEEK cage ACDF.

Pain Distraction During Awake Major Colorectal Surgery: Supporting Patients Beyond the COVID-19 Era. Preliminary Findings.

Introduction: During the coronavirus disease 2019 (COVID-19) pandemic, hospitals rapidly ran out of intensive care beds. Because minimally invasive surgery and general anaesthesia are both aerosol-generating procedures, their use has become controversial. We report a case series of awake undelayable colorectal surgeries which, innovatively, took advantage of intraoperative pain distraction. Moreover, we describe our frugal solution to social distancing in psychological support of inpatients.Methods: Between October 2020 and February 2021, five patients underwent acute-care colorectal surgery under locoregional anaesthesia in our department. A 3D mobile theatre (3DMT) was used during the operation to distract the patients from pain. Vital signs, pain intensity, ergonomic comfort/discomfort, sense of presence and distress were intraoperatively monitored. A postoperative “cuddle delivery” service was instituted: video messages from relatives and close friends were delivered daily to the patient through the 3DMT. Emotional effects were investigated through clinical interviews conducted by a psychologist at our hospital.Results: Both intraoperative and postoperative pain were always well controlled. Conversion to general anaesthesia and postoperative intensive support/monitoring were never necessary. The “cuddle delivery” initiative helped patients fill the emotional gap created by the strict containment measures implemented inside the hospital, distracting them from emotional anxiety and physical pain.Conclusions: During the next phase of the COVID-19 pandemic and even after the COVID-19 era, awake laparotomy under locoregional anaesthesia may be a crucial option for delivering acute-care surgery to selected patients when intensive care beds are unavailable and postponing surgery is unacceptable. We also introduce a new modality for the provision of emotional support during postoperative inpatient care as a countermeasure to the restrictions imposed by social distancing measures.

Minimally invasive triangular lumboiliac and iliosacral fixation of posterior pelvic ring injuries with vertical instability: Technical note

To date, no strong consensus exists on the best way to treat posterior pelvic ring injuries when there is no neurological deficit. Various fixation methods have been described; more recently, constructs that combine lumboiliac and iliosacral fixation have been introduced. This type of fixation is mainly indicated in cases of spinopelvic dissociation with large displacement of fracture fragments in the sagittal plane. However, these techniques are associated with postoperative complications, particularly infections and severe skin complications. This led us to propose a minimally invasive lumboiliac and iliosacral fixation technique for posterior pelvic ring injuries. The procedure is done with the patient prone. It consists of pedicle screw insertion into L4 or L5 and screw fixation of the ilium with fluoroscopy guidance; intraoperative distraction can be done depending on the amount of displacement. An iliosacral screw is then inserted percutaneously to allow reduction in the transverse plane and yield a triangular construct. In the five patients that we have operated using this technique, the mean preoperative vertical displacement was 11.9±6.9mm (SD) (min 1.3, max 19.7) versus 3.7±3.2mm (min 0.3, max 6.7) postoperatively and the mean preoperative frontal displacement was 7.5±3.7mm (min 4.2, max 12.4) versus 2.5±2.0mm (min 0.3, max 4.3) postoperatively. Minimally invasive iliosacral and lumboiliac fixation is an option for treating posterior pelvic ring fractures free of neurological deficit and especially spinopelvic dissociation.

An intraoperative laterally placed distractor for gradual load sharing correction of severe spastic neuromuscular spinal deformity.

To analyze the overall deformity correction for severe neuromuscular scoliosis using laterally placed intra-operative distraction and compare to those receiving standard surgical technique. This was a retrospective, IRB-approved, cohort study of patients with GMFCS 4 or 5 spastic cerebral palsy with neuromuscular scoliosis, age greater than 10years, who underwent posterior spinal fusion from 2007 to 2019. All patients had vectored cervical traction with Gardner-Wells tongs, with hips flexed in a relative sitting position. The study cohort underwent intraoperative, laterally placed correction using a distractor placed between two upper ribs and the ipsilateral greater trochanter while the control cohort did not. The 24 study patients were compared to 22 control patients. Preoperative comparisons identified significant differences in Cobb angle, preoperative flexibility, and pelvic obliquity with the study group having larger, stiffer deformities with greater obliquity. There were no differences in pre-operative sagittal plane deformity. Mean post-operative upright Cobb angle correction was 67.3° ± 14.8° in the study and 55.3° ± 9.9° in the control group, representing a 66% and 60% correction, respectively. No neurological or other complications were noted from the use of this technique. The use of a laterally placed distraction device from upper ribs to ipsilateral greater trochanter allowed gradual lateral un-bending of large stiff neuromuscular spine deformities with greater correction than that of standard technique. In this small series, the technique allowed load-sharing during correction, with hips remaining in a functional sitting position, and without neurological complications. Level III-retrospective cohort study.

The correlation of intraoperative distraction of intervertebral disc with the postoperative canal and foramen expansion following oblique lumbar interbody fusion.

To examine the correlation of intraoperative distraction of intervertebral disc with the postoperative central canal and foramen expansion by oblique lumbar interbody fusion (OLIF) with indirect decompression. Patients who underwent OLIF between October 2013 and April 2017 were included. Clinical outcomes included back and leg pain evaluated by visual analog scale (VAS) and Oswestry Disability Index (ODI). Intraoperative radiographic parameters of height ratio [(HR) = disc height/intervertebral body height)] and cage location were evaluated on intraoperative fluoroscopic images. Disc height (DH), foraminal height (FH), cross-sectional area of spinal canal (CSAC), and CSA of the foramen (CSAF) were measured. A total of 47 patients involving 62 levels were enrolled in this study. Mean follow-up was 43.8 ± 12.0months. These patients reported an improvement of 61.7% in VAS back, 68.1% in VAS leg, and 46% in ODI (all p < 0.01). Radiographic parameters including HR, DH, FH, CSAC, and CSAF were also significantly increased by 32.6%, 48.2%, 21.4%, 44.0%, and 40.1% (left-side CSAF) or 45.4% (right-side CSAF), respectively (p < 0.05). HR increment was correlated with CSA (canal and foramen) increment. Slightly higher improvements of HR, DH, FH, CSAC, and CSAF (both sides) were noted when cage was located at middle rather than anterior (p > 0.05). The ligamentotaxis effect of OLIF is capable of supporting indirect decompression of central canal and neural foramina and clinical improvement. HR is a reliable intraoperative assessment method. In addition, intraoperative HR increment was correlated with postoperative neural elements expansion.

Effect of Changes in Postoperative Intervertebral Space Height on Clinical and Radiological Outcomes After Cervical Disc Replacement

Narrowing of intervertebral space height (ISH) is an important pathological change in degenerative spinal disease, and ideal intraoperative distraction and postoperative intervertebral space maintenance is one of the most expectant goals pursued by spinal surgeons. The effect of postoperative ISH changing on the clinical and radiological outcomes after cervical disc replacement is not fully understood, however. In this study, the height variation and general trend of postoperative ISH in all patients were analyzed. The patients were divided into 3 groups based on the change of postoperative intervertebral space height (ISH)-group A (ISH <2 mm), group B (ISH 2-4 mm), and group C (ISH >4mm)-and the clinical and radiographic results compared among the 3 groups. A total of 120 consecutive patients with symptomatic cervical disc disease were included in this study. The results showed that the mean ISH increased significantly from 0.729 mm before surgery to 1.143 mm at 1 week, then gradually decreased to 1.032 mm at 3 months, 0.980 mm at 6 months, 0.760 mm at one year, and 0.750 mm at the final follow-up. The average postoperative Neck Disability Index (NDI) was 19.73 ± 0.81, 13.74 ± 4.94, 17.19 ± 4.22, respectively, in the 3 groups at 1 year after surgery and the average range of motion (ROM) was 5.44° ± 3.85° in group A, 9.34° ± 4.38° in group B, and 6.51° ± 4.38° in group C. The mean diameter of the intervertebral foramen was 6.54 ± 1.86 mm in group A, 9.63 ± 2.38 mm in group B, and 9.31 ± 1.68 mm in group C. Degeneration at the superiorly adjacent disc level was observed in 13.51% patients in group A, 9.37% in group B, and 21.05% in group C. Degeneration at the inferiorly adjacent level was radiographically identified in 21.62% in group A, 14.06% in group B, and 26.32% in group C. This study revealed that cervical disc replacement cannot maintain the intervertebral disc height obtained immediately after surgery. There is no obvious correlation between the change in intervertebral space height and clinical efficacy in the early postoperative stage. Nonetheless, the intervertebral disc height may affect the NDI index 1 year after surgery. If the postoperative intervertebral space height change can be maintained at 2-4 mm at 1 year, satisfactory ROM, intervertebral foramen diameter, and relatively low adjacent segment degeneration may be obtained after cervical disc replacement.

Iatrogenic Peroneal Nerve Palsy Rates Secondary to Open Reduction Internal Fixation for Tibial Plateau Fractures Using an Intraoperative Distractor.

To report the rate of peroneal nerve palsy after routine use of intraoperative distraction during open reduction internal fixation (ORIF) for lateral unicondylar and bicondylar tibial plateau fracture (TPF) repairs. Retrospective chart review. Level I trauma center. Patients with traumatic TPF treated with ORIF between 2007 and 2017. ORIF for lateral unicondylar and bicondylar TPF. Presence and resolution of neurovascular injury. There were a total of 21 lateral unicondylar and 40 bicondylar TPFs repaired through ORIF in 60 patients identified during the study period with 1-year follow-up and complete records for review. Thirty-six patients had staged external fixation before ORIF while 24 were treated with ORIF initially. Of the staged patients, 9 of 36 (25%) developed nerve palsy while those undergoing initial ORIF (not staged) developed palsy in only one case (1 of 24, or 4%). Of the patients who developed nerve palsy, 9 of 10 (90%) were staged with an initial external fixator before ORIF. The incidence of iatrogenic peroneal nerve palsy secondary to intraoperative distraction was 16.4% (10 of 61). Only 60% (6 of 10) of peroneal nerve palsies recovered clinically with a mean recovery time of approximately 14 weeks. Comparison of demographics in patients with peroneal nerve palsy versus those without yielded no significant difference by sex (P = 0.08), age (P = 0.27), fracture type (P = 0.29), tobacco use (P = 0.44), or alcohol use (P = 0.78). Peroneal nerve palsy is a common sequela of ORIF for TPFs involving the lateral compartment using an intraoperative distractor. Staged external fixation followed by definitive ORIF using intraoperative distraction was associated with significant risk for developing nerve palsy (9/10). Many patients (40%) who develop peroneal nerve palsies do not recover, leading to permanent loss of motor and/or sensory function for 7% of patients studied. None of the epidemiologic variables evaluated yielded predictive value for development of peroneal nerve palsy or subsequent resolution. Caution should be exercised in avoiding overdistraction when using intraoperative distraction, especially in those cases that had staged fixation, most notably bicondylar injuries. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Risk Factors of Allogenous Bone Graft Collapse in Two-Level Anterior Cervical Discectomy and Fusion.

ObjectiveAnterior cervical discectomy and fusion (ACDF) is commonly used surgical procedure for cervical degenerative disease. Among the various intervertebral spacers, the use of allografts is increasing due to its advantages such as no harvest site complications and low rate of subsidence. Although subsidence is a rare complication, graft collapse is often observed in the follow-up period. Graft collapse is defined as a significant graft height loss without subsidence, which can lead to clinical deterioration due to foraminal re-stenosis or segmental kyphosis. However, studies about the collapse of allografts are very limited. In this study, we evaluated risk factors associated with graft collapse. MethodsWe retrospectively reviewed 33 patients who underwent two level ACDF with anterior plating using allogenous bone graft from January 2013 to June 2017. Various factors related to cervical sagittal alignment were measured preoperatively (PRE), postoperatively (POST), and last follow-up. The collapse was defined as the ratio of decrement from POST disc height to follow-up disc height. We also defined significant collapses as disc heights that were decreased by 30% or more after surgery. The intraoperative distraction was defined as the ratio of increment from PRE disc height to POST disc height. ResultsThe subsidence rate was 4.5% and graft collapse rate was 28.8%. The pseudarthrosis rate was 16.7% and there was no association between pseudarthrosis and graft collapse. Among the collapse-related risk factors, pre-operative segmental angle (p=0.047) and intra-operative distraction (p=0.003) were significantly related to allograft collapse. The cut-off value of intraoperative distraction ≥37.3% was significantly associated with collapse (p=0.009; odds ratio, 4.622; 95% confidence interval, 1.470-14.531). The average time of events were as follows: collapse, 5.8±5.7 months; subsidence, 0.99±0.50 months; and instrument failure, 9.13±0.50 months. ConclusionWe experienced a higher frequency rate of collapse than subsidence in ACDF using an allograft. Of the various preoperative factors, intra-operative distraction was the most predictable factor of the allograft collapse. This was especially true when the intraoperative distraction was more than 37%, in which case the occurrence of graft collapse increased 4.6 times. We also found that instrument failure occurs only after the allograft collapse.

Anterior correction of angular kyphosis in children: description of the technique and analysis of clinical series

Objective. To describe the original technical surgical procedure simplifying the correction of kyphosis in children due to instrumental distraction of the anterior column of the spine, to analyze its effectiveness in the setting of clinical series. Level of evidence – IV. Material and Methods. The study included 9 patients aged 7 months to 14 years (median age: 4 years 8 months) with angular kyphosis (median magnitude 53°, min – 38°, max – 80°) associated with tuberculous (n = 4) and non-specific (n = 4) spondylitis and with a sequelae of spinal cord injury (n = 1). Deformity correction was achieved using temporary instrumental interbody distraction followed by anterior fusion with titanium mesh cage filled with autologous bone graft during a single-step two-stage reconstruction and stabilization surgery. Results. The duration of surgery was 3 hours 2 min ± 44 min, the volume of blood loss – 190 ml ± 39 ml. In all cases, the deformity was corrected by 75–85 % with restoration of physiological thoracic kyphosis and spinal profile. Conclusion. A safe and effective technique for intraoperative anterior instrumental distraction can be used to correct angular kyphosis in children, including infants.

Intraoperative electrophysiological monitoring during posterior craniocervical distraction and realignment for congenital craniocervical anomaly.

Congenital craniocervical segmentation anomaly associated with malalignment of the odontoid process causes progressive spinal cord compression with myelopathy. Recent literatures have reported that ventral decompression could be achieved with posterior craniocervical realignment through posterior instrumented reduction. The purpose of the present study is to show the efficacy of intraoperative electrophysiological monitoring during craniocervical realignment through screws and rod system for congenital craniocervical segmentation anomaly. Consecutive ten patients with a congenital craniocervical segmentation anomaly and myelopathy due to a malaligned odontoid process, who underwent posterior craniocervical realignment, were included. Klippel-Feil syndrome (KFS) was combined in four patients. Gait disturbance and motor weakness were the main presentation. Craniocervical realignment was achieved by intraoperative distraction through a rod and screw system. Intraoperative neuromonitoring was performed with transcranial motor-evoked potential (TcMEP) and somatosensory-evoked potential (SSEP). Significant change in TcMEP occurred in two patients with KFS during surgery, but the change was reversed with release of distraction. All patients were awakened without neurological deficit. Motor weakness and gait disturbance were normalized within 6 months in all patients. Postoperative computed tomography scan and/or magnetic resonance imaging showed that the reduction was complete in all patients. Craniocervical realignment through screws and rod system may be safe and efficacious surgical technique for the treatment of congenital craniocervical anomaly with the help of intraoperative neuromonitoring. However, distraction should be cautiously monitored, especially when Klippel-Feil syndrome is combined.

Surgical Management of Adult Reducible Atlantoaxial Dislocation, Basilar Invagination and Chiari Malformation with Syringomyelia.

To analyze retrospectively the surgical management of reducible atlantoaxial dislocation (AAD), basilar invagination (BI) and Chiari malformation (CHM) with syringomyelia through a single-stage posterior approach. Forty-three patients with reducible AAD, BI and CHM with syringomyelia underwent surgery from January 2009 to January 2013. Intraoperative restoration followed by posterior decompression and plate-rod placement with occipital cortical screws and C2/C3 lateral mass cortical screws fixation devices were used in all patients. Results were recorded both pre- and postoperatively and these outcome measures included Nurick grading (NG) and radiology findings (atlantodental interval (ADI), space available for the spinal cord (SAC), interval between odontoid and Chamberlain's line (IOC), and the cervicomedullary angle (CMA)). Forty (93%) of the 43 patients were followed up. Thirty-six (90%) patients' symptoms improved and four (10%) stabilized. No patients became progressively worse. The difference between preoperative and postoperative Nurick grades was statistically significant. All patients achieved restoration, including thirty (75%) patients had full restoration and ten (25%) had part restoration. The size of syringomyelia was obviously decreased in 32 (80%) patients and stable in 8 (20%) patients. All radiology findings (ADI, IOC, SAC, CMA) showed significant changes from pre- to postoperative (p < 0.01). Intraoperative distraction, extension combined posterior decompression with use of plate-rod-screws occipitocervical fusion device is an effective method to treat AAD, BI and CHM with syringomyelia.

Precise positioning of an intraoral distractor using augmented reality in patients with hemifacial microsomia

BackgroundThrough three-dimensional real time imaging, augmented reality (AR) can provide an overlay of the anatomical structure, or visual cues for specific landmarks. In this study, an AR Toolkit was used for distraction osteogenesis with hemifacial microsomia to define the mandibular osteotomy line and assist with intraoral distractor placement. Methods20 patients with hemifacial microsomia were studied and were randomly assigned to experimental and control groups. Pre-operative computed tomography was used in both groups, whereas AR was used in the experimental group. Afterwards, pre- and post-operative computed tomographic scans of both groups were superimposed, and several measurements were made and analysed. ResultsBoth the conventional method and AR technique achieved proper positioning of the osteotomy planes, although the AR was more accurate. The difference in average vertical distance from the coronoid and condyle process to the pre- and post-operative cutting planes was significant (p < 0.01) between the two groups, whereas no significant difference (p > 0.05) was observed in the average angle between the two planes. The difference in deviations between the intersection points of the overlaid mandible across two cutting planes was also significant (p < 0.01). ConclusionThis study reports on an efficient approach for guiding intraoperative distraction osteogenesis. Augmented reality tools such as the AR Toolkit may be helpful for precise positioning of intraoral distractors in patients with hemifacial microsomia in craniofacial surgery.

The Influence of Distraction Force on the Intradiscal Pressure Gradient in the Bridged Lumbar Spine

A biomechanical calf cadaver study. The purpose of this study was to determine the intradiscal pressure gradient of bridged healthy intervertebral segments in correlation with intraoperative distraction force. Bisegmental dorsal stabilization and anatomic reduction is a common treatment option for incomplete burst fractures of the lumbar spine. However, it remains unknown to what extent bridging and intraoperative distraction compromises an intact intervertebral disc. The L2-L3 intervertebral disc level was evaluated in 6 freshly frozen calf cadaver spines. Pressure measurements were obtained with the spine uninstrumented, after dorsal segmental instrumentation from L1 to L3, and after distraction with 400 N and 800 N. Pressure gradient measurements were accomplished with a balloon pressure sensor placed within the nucleus pulposus of the L2-L3 intervertebral disc. Pressure data were recorded by computer data acquisition. Flexion, extension, and lateral bending moments were applied continuously by a testing machine up to a load moment of 7.5 N·m. The pressure gradients were compared with respect to the effects of added instrumentation and distraction. After segmental bridging the mean pressure gradients were significantly reduced in all movement directions (P < 0.001). However, after dorsal stabilization a continuously rising intervertebral disc pressure was recordable. In contrast, no relevant additional reduction of the intradiscal pressure gradient was detectable after applying distraction forces of 400 N or 800 N. In a calf model, a distraction force of up to 800 N leads to no additional reduction of the pressure gradient of bridged healthy lumbar segments under flexion and extension moments.

Neuromonitoring Changes Are Common and Reversible With Temporary Internal Distraction for Severe Scoliosis

Study DesignRetrospective review of consecutive cases. ObjectiveTo examine the neurologic implications of applying intraoperative distraction to large curves. Summary Of Background DataTemporary rods provide internal distraction during correction of severe scoliosis and may be an alternative to prolonged halo traction or vertebral column resection. MethodsA single surgeon’s consecutive experience with posterior-only spinal fusion with temporary distraction rods was reviewed retrospectively. Inclusion criteria were long posterior-only spinal fusion (10 or more levels) for severe scoliosis (major Cobb angle 80° or greater), treated with temporary internal distraction. Records were reviewed for age, gender, diagnosis, intraoperative course, and complications. Radiographs were reviewed for Cobb angles, T1–S1 length, and space available for each lung. ResultsTwenty-two patients with a mean age of 14 years and a mean of 15 levels fused (range, 10–18 levels) were included. The mean preoperative coronal Cobb angle was 113° (range, 83°–144°), and a mean correction of 62° (54%) was achieved. There was a mean T1–S1 increase of 8.4 cm (range, 2.4–14 cm). Nine patients had 2-stage procedures separated by a mean of 7 days. Thirteen patients had a single procedure. Of 22 patients, 9 (41%) had intraoperative neuromonitoring changes. All neuromonitoring changes were reversed after releasing distraction on the temporary rod, except in 1 case. No patient had a clinical neurologic deficit. ConclusionsUse of temporary distraction rods for severe scoliosis produces curve correction while providing a mean increase in T1–S1 height of 8 cm. Most steps in this surgery are reversible. Neuromonitoring changes are common, but they are reversible with release of some distraction. Neuromonitoring changes did not affect the final magnitude of correction, and there were no clinical neurologic deficits. We recommend that this procedure be performed only with good neuromonitoring.

Radiographic and clinical outcome after 1- and 2-level transsacral axial interbody fusion

The paracoccygeal approach allows for instrumentation of L5/S1 and L4/5 by using a transsacral rod (AxiaLIF; TransS1, Inc.). The authors analyzed clinical and radiographic outcomes of 1- or 2-level AxiaLIF procedures with focus on durability of the construct. This was a retrospective study of 38 consecutive patients who underwent either 1-level (32 patients) or 2-level (6 patients) AxiaLIF procedures at the authors' institution. The Oswestry Disability Index (minimum clinically important difference [MCID] ≥ 12) and visual analog scale ([VAS]; MCID ≥ 3) scores were collected. Disc height and Cobb angles were measured on pre- and postoperative radiographs. Bony fusion was determined on CT scans or flexion/extension radiographs. Implantation of a transsacral rod allowed for intraoperative distraction of the L5/S1 intervertebral space and resulted in increased segmental lordosis postoperatively. At a mean follow-up time of 26.2 ± 2.4 months, however, graft subsidence (1.9 mm) abolished partial correction of segmental lordosis. Moreover, subsidence of the construct reduced L5/S1 lordosis in patients with 1-level AxiaLIF by 3.2° and L4-S1 lordosis in patients with 2-level procedures by 10.1° compared with preoperative values (p < 0.01). Loss of segmental lordosis predicted failure to improve VAS scores for back pain in the patient cohort (p < 0.05). Overall, surgical intervention led to modest symptomatic improvement; only 26.3% of patients achieved an MCID of the Oswestry Disability Index and 50% of patients an MCID of the VAS score for back pain. At last follow-up, 71.9% of L5/S1 levels demonstrated bony fusion (1-level AxiaLIF 80.8%, 2-level AxiaLIF 33.3%; p < 0.05), whereas none of the L4/5 levels in 2-level AxiaLIF fused. Five constructs developed pseudarthrosis and required surgical revision. The AxiaLIF procedure constitutes a minimally invasive technique for L5/S1 instrumentation, with low perioperative morbidity. However, the axial rod provides inadequate long-term anterior column support, which leads to subsidence and loss of segmental lordosis. Modification of the transsacral technique to allow for placement of a solid interposition graft may counteract subsidence of the construct.

Congenital atlantoaxial dislocation: a dynamic process and role of facets in irreducibility

Patient age at presentation with congenital atlantoaxial dislocation (CAAD) is variable. In addition, the factors determining irreducibility or reducibility in these patients remain unclear. The facets appear to contribute to the stability of the joint, albeit to an unknown extent. The objective of this paper was to study the characteristics of C1-2 facets in these patients and their bearing on the clinicoradiological presentation and management. Twenty-four patients with CAAD were studied. Fifteen patients had irreducible CAAD (IrAAD); 3 of these patients experienced incomplete reduction after traction, and 9 had reducible CAAD (RAAD). The images (CT scans of the craniovertebral junction in a neutral position) obtained in the parasagittal, axial, and coronal planes were studied with respect to the C1-2 facets and were compared with 32 control scans. The inferior sagittal and coronal C-1 facet angles were measured. The lordosis of the cervical spine (cervical spine angle calculated on radiographs of the cervical spine, neutral view) in these patients was compared with normal. The management of these patients is described. The inferior sagittal C-1 facet angle and at least one coronal angle in patients with IrAAD were significantly acute compared with those in patients with RAAD and the control population. A significant correlation was found between age and the acuteness of the inferior sagittal C-1 facet angle (that is, the more acute the angle, the earlier the presentation). The lordosis of the cervical spine was exaggerated in patients with IrAAD. Three patients with IrAAD who had smaller acute angles experienced a partial reduction after traction and a complete reduction after intraoperative distraction of the facets, thereby avoiding a transoral procedure. An inferior sagittal C-1 facet angle of more than 150° in the sagittal plane predicted reducibility. Drilling a wedge off the facet in the sagittal plane to make the inferior sagittal C-1 facet angle 150° can reduce the C1-2 joint intraoperatively by posterior approach alone. The acuteness of the inferior C-1 sagittal facet angles possibly determines the age at presentation and reducibility. The coronal angles determine the telescoping of C-2 within C-1. Patients with IrAAD can be treated using a posterior approach alone with the exception of those with extremely acute angles or a retroflexed dens. The exaggerated lordosis of the cervical spine in these patients is a compensatory phenomenon.

Subsidence and Nonunion after Anterior Cervical Interbody Fusion Using a Stand-Alone Polyetheretherketone (PEEK) Cage

BackgroundThe purposes of the present study are to evaluate the subsidence and nonunion that occurred after anterior cervical discectomy and fusion using a stand-alone intervertebral cage and to analyze the risk factors for the complications.MethodsThirty-eight patients (47 segments) who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage and an autologous cancellous iliac bone graft from June 2003 to August 2008 were enrolled in this study. The anterior and posterior segmental heights and the distance from the anterior edge of the upper vertebra to the anterior margin of the cage were measured on the plain radiographs. Subsidence was defined as ≥ a 2 mm (minor) or 3 mm (major) decrease of the segmental height at the final follow-up compared to that measured at the immediate postoperative period. Nonunion was evaluated according to the instability being ≥ 2 mm in the interspinous distance on the flexion-extension lateral radiographs.ResultsThe anterior and posterior segmental heights decreased from the immediate postoperative period to the final follow-up at 1.33 ± 1.46 mm and 0.81 ± 1.27 mm, respectively. Subsidence ≥ 2 mm and 3 mm were observed in 12 segments (25.5%) and 7 segments (14.9%), respectively. Among the expected risk factors for subsidence, a smaller anteroposterior (AP) diameter (14 mm vs. 12 mm) of cages (p = 0.034; odds ratio [OR], 0.017) and larger intraoperative distraction (p = 0.041; OR, 3.988) had a significantly higher risk of subsidence. Intervertebral nonunion was observed in 7 segments (7/47, 14.9%). Compared with the union group, the nonunion group had a significantly higher ratio of two-level fusion to one-level fusions (p = 0.001).ConclusionsAnterior cervical fusion using a stand-alone cage with a large AP diameter while preventing anterior intraoperative over-distraction will be helpful to prevent the subsidence of cages. Two-level cervical fusion might require more careful attention for avoiding nonunion.