Halovest dynamic loads: full crossover comparison of three vest types

Efficacy and safety of halo-gravity traction in the treatment of spinal deformities: A systematic review of the literature

OBJECTIVE

To determine, through a systematic review, the effects of halo gravity traction in spinal deformity.

METHODS

Prospective studies or case series of patients with scoliosis or kyphosis treated with cranial halo gravity traction (HGT) were included. Radiological outcomes were measured in the sagittal and/or coronal planes. Pulmonary function was also assessed. Perioperative complications were also collected.

RESULTS

Thirteen studies were included. Congenital etiology was the most frequent etiology observed. Most studies provided clinically relevant curve correction values in the sagittal and coronal planes. Pulmonary values improved significantly after the use of HGT. Finally, there were a pool of 83 complications in 356 patients (23.3%). The most frequent complications were screw infection (38 cases).

CONCLUSIONS

Preoperative HGT appears to be a safe and effective intervention for deformity that allows correction prior to surgery. However, there is a lack of homogeneity in the published studies.

Efficacy and safety of halo-gravity traction in the treatment of spinal deformities: A systematic review of the literature

OBJECTIVE

To determine, through a systematic review, the effects of halo-gravity traction (HGT) in spinal deformity.

METHODS

Prospective studies or case series of patients with scoliosis or kyphosis treated with cranial HGT were included. Radiological outcomes were measured in the sagittal and/or coronal planes. Pulmonary function was also assessed. Perioperative complications were also collected.

RESULTS

Thirteen studies were included. Congenital etiology was the most frequent etiology observed. Most studies provided clinically relevant curve correction values in the sagittal and coronal planes. Pulmonary values improved significantly after the use of HGT. Finally, there were a pool of 83 complications in 356 patients (23.3%). The most frequent complications were screw infection (38 cases).

CONCLUSIONS

Preoperative HGT appears to be a safe and effective intervention for deformity that allows correction prior to surgery. However, there is a lack of homogeneity in the published studies.

Transarticular Screw Fixation in the Treatment of Severe C1-C2 Dislocation: A Case Series Report

Background

To aim of the present paper was to evaluate the results of halo traction and transarticular screw fixation combined with bone autoplasty in patients with severe atlantoaxial dislocation.

Case presentation

This is a retrospective study of severe cases of atlantoaxial dislocation in nine patients (six men and three women) treated with preoperative halo traction and posterior C1–C2 transarticular screw fixation combined with bone autoplasty from June 2006 to June 2011 at the Saint Paul Hospital (Hanoi). The mean age of patients was 37.48 ± 13.753 years (range, 26–50 years). The possibility of fixing dislocation using a halo apparatus was investigated through a series of preoperative halo corrections performed within a span of 1–2 weeks. For transarticular screw fixation, two transarticular screws were used that were positioned according to the Magerl technique. For bone autoplasty, an iliac crest bone graft approximately 3 × 2 cm in size was used. The postoperative assessment of clinical improvement was performed using the neck disability index (NDI), the American Spinal Injury Association (ASIA) impairment scale, and the visual analog scale (VAS) measurement instruments, through the gradation of atlantoaxial dislocation, and via the clivoaxial angle(CAA) index and the space available for cord (SAC) index after 6 months. The image diagnosis demonstrates that all the cases of atlantoaxial dislocations are unstable and correspond to the Fielding and Hawkins type III dislocation. Eight patients underwent complete reduction using the halo fixation device. In one patient, the C1–C2 displacement was manually reduced during surgery. CT scanning revealed that the accuracy of screw placement was 94.4%. The bone fusion rate was 100% after 6 months. Based on the ASIA impairment scale, the preoperative examination of patients revealed grade C injuries in seven patients and grade D injuries in two patients. After surgery, all patients had grade D injuries. Six months after surgery, four patients had moderate self‐reported neck disability (30%–48%) and five patients reported mild disability (10%–28%); that is, the patient perception of the neck problem improved. In the postoperative phase, all patients showed an improvement in VAS pain scores and the SAC score returned to the normal range in all patients. The CAA returned to normal in only seven patients; in the other two patients, the CAA returned to a value that was close to normal (145° and 149°).

Conclusion

Through halo traction combined with transarticular screw fixation and bone autoplasty, noticeable postoperative improvements were attained based on the clinical scores for NDI, ASIA, and VAS, as well as SAC and CAA.

The freedom to heal: nonrigid immobilization by a halo orthosis

Halo orthoses present a paradox. On the one hand, the nominally rigid immobilization they provide to the head aims to remove loads on the cervical spine following injury or surgery, and the devices are retightened routinely to maintain this. On the other hand, bone growth and remodeling are well known to require mechanical stressing. How are these competing needs balanced? To understand this trade-off in an effective, commercial halo orthosis, the authors quantified the response of a commercial halo orthosis to physiological loading levels, applied symmetrically about the sagittal plane. They showed for the first time that after a few cycles of loading analogous to a few steps taken by a patient, the support presented by a standard commercial halo orthosis becomes nonlinear. When analyzed through straightforward structural modeling, these data revealed that the nonlinearity permits mild head motion while severely restricting larger motion. These observations are useful because they open the possibility that halo orthosis installation could be optimized to transfer mild spinal loads that support healing while blocking pathological loads.

Biomechanics of halo-vest and dens screw fixation for type II odontoid fracture

STUDY DESIGN

An in vitro biomechanical study of halo-vest and odontoid screw fixation of Type II dens fracture.

OBJECTIVE

The objective were to determine upper cervical spine instability due to simulated dens fracture and investigate stability provided by the halo-vest and odontoid screw, applied individually and combined.

SUMMARY OF BACKGROUND DATA

Previous studies have evaluated posterior fixation techniques for stabilizing dens fracture. No previous biomechanical study has investigated the halo-vest and odontoid screw for stabilizing dens fracture.

METHODS

A biofidelic skull-neck-thorax model was used with 5 osteoligamentous whole cervical spine specimens. Three-dimensional flexibility tests were performed on the specimens while intact, following simulated dens fracture, and following application of the halo-vest alone, odontoid screw alone, and halo-vest and screw combined. Average total neutral zone and total ranges of motion at C0/1 and C1/2 were computed for each experimental condition and statistically compared with physiologic motion limits, obtained from the intact flexibility test. Significance was set at P < 0.05 with a trend toward significance at P < 0.1.

RESULTS

Type II dens fracture caused trends toward increased sagittal neutral zone and lateral bending range of motion at C1/2. Spinal motions with the dens screw alone could not be differentiated from physiologic limits. Significant reductions in motion were observed at C0/1 and C1/2 in flexion-extension and axial rotation due to the halo-vest, applied individually or combined with the dens screw. At C1/2, the halo-vest combined with the dens screw generally allowed the smallest average percentages of intact motion: 3% in axial rotation, 17% in flexion-extension, and 18% in lateral bending.

CONCLUSION

The present reduction in C1/2 motion observed, due to the halo-vest and dens screw combined is similar to previously reported immobilization provided by the polyaxial screw/rod system and transarticular screw fixation combined with wiring. The present biomechanical data may be useful to clinicians when choosing an appropriate treatment for those with Type II dens fracture.

Effect of halo-vest components on stabilizing the injured cervical spine

STUDY DESIGN

An in vitro biomechanical study.

OBJECTIVES

The objectives were to develop a new biofidelic skull-neck-thorax model capable of quantifying motion patterns of the cervical spine in the presence of a halo-vest; to investigate the effects of vest loosening, superstructure loosening, and removal of the posterior uprights; and to evaluate the ability of the halo-vest to stabilize the neck within physiological motion limits.

SUMMARY OF BACKGROUND DATA

Previous clinical and biomechanical studies have investigated neck motion with the halo-vest only in the sagittal plane or only at the injured spinal level. No previous studies have quantified three-dimensional intervertebral motion patterns throughout the injured cervical spine stabilized with the halo-vest or studied the effect of halo-vest components on these motions.

METHODS

The halo-vest was applied to the skull-neck-thorax model. Six osteoligamentous whole cervical spine specimens (occiput through T1 vertebra) were used that had sustained multiplanar ligamentous injuries at C3/4 through C7-T1 during a previous protocol. Flexibility tests were performed with normal halo-vest application, loose vest, loose superstructure, and following removal of the posterior uprights. Average total range of motion for each experimental condition was statistically compared (P < 0.05) with the physiologic rotation limit for each spinal level.

RESULTS

Cervical spine snaking was observed in both the sagittal and frontal planes. The halo-vest, applied normally, generally limited average spinal motions to within average physiological limits. No significant increases in average spinal motions above physiologic were observed due to loose vest, loose superstructure, or removal of the posterior uprights. However, a trend toward increased motion at C6/7 in lateral bending was observed due to loose superstructure.

CONCLUSION

The halo-vest, applied normally, effectively immobilized the cervical spine. Sagittal or frontal plane snaking of the cervical spine due to the halo-vest may reduce its immobilization capability at the upper cervical spine and cervicothoracic junction.

Muscle atrophy after treatment with Halovest

STUDY DESIGN

A prospective study was conducted on the sequential changes in the muscles around the cervical spine following external fixation for an extended period.

OBJECTIVE

Muscular atrophy around the cervical spine following prolonged external fixation with a Halovest and subsequent recovery from the atrophy were examined.

SUMMARY OF BACKGROUND DATA

There are a number of reports on the usefulness of the Halovest. However, there have been no descriptions about muscular atrophy following fixation by the Halovest.

METHODS

The study participants were 10 patients who were conservatively treated by the Halovest. Imaging by CT was performed periodically following fixation by the Halovest. The cross sections of the sternocleidomastoid muscle and the nuchal muscle group at C5-C6 were computed by using NIH Image Software. The results were used to evaluate muscular atrophy following fixation by the Halovest and the subsequent recovery after removal of the fixation.

RESULTS

Following fixation by the Halovest, atrophy of the muscles around cervical spine sequentially progressed. Three months after fixation, muscular atrophy was about 15% at the sternocleidomastoid muscle and 22% for the nuchal muscle group, but the patients recovered from the atrophic state following the removal of the device.

CONCLUSION

Following fixation by the Halovest, muscular atrophy around the cervical spine sequentially progressed. After the device was removed, however, the muscles recovered from the atrophic state. Muscular atrophy caused by prolonged fixation by the Halovest was a reversible change.