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.

Does routine pin re-torquing of patients wearing a halo-thoracic orthosis reduce the need for pin replacement?

Background: The halo orthosis is a treatment option currently used in Australia for cervical spine immobilisation following trauma, fracture and post surgical stabilisation. In a previous study, the authors reported halo pin replacement to be a common complication. The aim of this study was to investigate the potential correlation between routine halo pin re-torquing and the incidence of pin replacement. Case description and methods: A retrospective case series study was undertaken. A total of 258 charts were reviewed, with 170 patients included in the study. Patients were fitted with a Bremer HALO System with the initial application torque maintained by routine re-torquing throughout the duration of wear. Findings and outcomes: A total of 680 pins (4 per patient) were inserted during the initial application of the halo orthoses, with only six pins replaced (0.88%) throughout the duration of the study. Conclusion: The findings from this study demonstrate a potential correlation between routinely re-torquing halo pins and decreasing the incidence of pin replacement. Clinical relevance This case series study has identified a potential improvement in clinical management of patients wearing a halo-thoracic orthosis.

Open reduction and internal fixation for angulated, unstable odontoid synchondrosis fractures in children: a safe alternative to halo fixation?

External orthosis is the accepted and historical management of odontoid synchondrosis fractures; however, this conservative therapy carries a significant complication and fracture nonunion rate among young children. The purpose of this study was to evaluate the authors' own experience in the context of the literature, to explore surgical fixation as a primary treatment for unstable fractures. The authors retrospectively reviewed 2 cases of unstable odontoid synchondrosis fractures treated at their institution; both showed radiographic progression of deformity and subsequently underwent an open surgical reduction and fusion. A literature review was conducted to compare the authors' management strategy with those in published data. External orthosis for treatment of odontoid synchondrosis fractures has a strong history of success. However, in the literature, patients treated with a halo orthosis had a 43.3% rate of complications and an 11.4% risk of nonunion. There are radiographic findings that suggest instability, such as severe angulation and displacement of the odontoid process. Both patients in the present report underwent successful fusion without complication, as documented on CT scans obtained 3 months after surgery. Given the high rate of fusion attained with conservative therapy, it is recommended for most synchondrosis fractures. However, there is a recognized subgroup of synchondrosis fractures with severe angulation (> 30°) and displacement suggestive of significant ligamentous injury. In these patients, surgical fixation may be a safe and efficacious alternative to halo orthosis as the primary treatment.

Occipitocervical instrumentation in the pediatric population using a custom loop construct: initial results and long-term follow-up experience

Object Rigid occipitocervical instrumentation for craniovertebral instability is gaining widespread acceptance for use in pediatric patients; however, most of the instrumentation has been modified from adult-sized hardware. The Wasatch loop system (formerly the Avery-Brockmeyer-Thiokol loop system) is a rigid occipitocervical fixation device designed specifically for use in children. It affixes to the occiput and incorporates either C1–2 transarticular screws or C-2 pars screws. It is preformed and is available in a variety of sizes. The authors describe their clinical experience and long-term follow-up experience with the first 22 patients. Methods An institutional review board–approved retrospective review of medical records and radiographs was performed for patients who underwent occipitocervical fusion with the Wasatch loop. The mean patient age was 4.9 years (1.2–13 years), and the overall mean follow-up was 4 years (1.5–6.5 years). Six patients had posttraumatic instability, and 16 patients had congenital instability. Results Twelve patients underwent placement of bilateral C1–2 transarticular screws, 6 patients had placement of a combination of C1–2 transarticular and C-2 pars screws, and 4 patients had placement of bilateral C-2 pars screws. One patient required a halo orthosis; the others were treated postoperatively with a hard cervical collar. All patients had radiographic evidence of solid occipitocervical arthrodesis on last follow-up examination. Conclusions The Wasatch loop system is a novel internal fixation device for children who have posttraumatic or congenital occipitocervical instability. Successful arthrodesis was achieved in all patients with minimal use of halo orthoses.

Management of brain abscesses associated with halo fixation

✓ Halo orthoses are commonly used in the management of a variety of cervical spinal pathological conditions. Although placement of the cranial pins was initially believed to be safe with minimal complications, minor complications related to the cranial pins have the potential to create a setting for formation of cerebral abscesses. The risk of death due to cerebral abscesses has declined in the modern antibiotic era, but cerebral abscesses are associated with long-standing neurological morbidity that should not be considered negligible. Prevention by careful pin placement and hygiene and appropriate early management are crucial to prevent more serious complications. The authors report the case of a patient treated with a halo orthosis after incurring cervical spinal trauma who developed a cerebral abscess as a complication related to the cranial pins of the halo fixation device. They review the literature in an attempt to formulate a standardized treatment algorithm to prevent this disease process and to treat an abscess if it should form.