Mechanical failure of the Mobi-C implant for artificial cervical disc replacement: report of 4 cases.

Cervical spondylosis is one of the most commonly treated conditions in neurosurgery. Increasingly, cervical disc replacement (CDR) has become an alternative to traditional arthrodesis, particularly when treating younger patients. Thus, surgeons continue to gain a greater understanding of short- and long-term complications of arthroplasty. Here, the authors present a series of 4 patients initially treated with Mobi-C artificial disc implants who developed postoperative neck pain. Dynamic imaging revealed segmental kyphosis at the level of the implant. All implants were locked in the flexion position, and all patients required reoperation. This is the first reported case series of symptomatic segmental kyphosis after CDR.

Head injuries in hospital-admitted adolescents and adults with skateboard-related trauma.

OBJECTIVE: To provide new information on properties of skateboarders who were hospital admitted with head injuries with details of the injuries including region of head impact. METHODS: Hospital records of patients aged 15 and older with a skateboard injury admitted to one Level II Trauma Centre during a 10-year period were reviewed. Data on demographic, exposure, severity, diagnostic and clinical factors for patients with head injury (HI) and without HI (N-HI) were compared analytically. RESULTS: While there were no differences for patients with HI and N-HI by age, gender, mechanism of injury or alcohol use, patients with HI were more severely injured. Although significantly more head impacts occurred to the occipital region of the head, haematomas and/or contusions were much more likely to occur in the frontal region of the brain. Acute neurosurgical intervention was needed in 14% of HI skateboarders. CONCLUSION: Skateboarding is not an innocuous recreational activity, with head injury present in 75% of patients who were hospital-admitted. Pre-hospital treatment protocols should be aware of this growing injured population. Falls while on a skateboard lead to impacts to the back of head with a contra-coup brain injury resulting in severe and sometimes fatal outcomes. The very low prevalence of helmet use among skateboarders with head injuries indicates that greater efforts should be directed toward incentives for their use.

Retroperitoneal lateral lumbar interbody fusion with titanium threaded fusion cages.

OBJECT: Intertransverse arthrodesis in which instrumentation is placed is associated with an excellent fusion rate; however, treatment of patients with symptomatic nonunion presents a number of difficulties. Revision posterior and traditional anterior procedures are associated with methodological problems. For example, in the latter, manipulation of the major vessels from L-2 to L-4 may be undesirable. The authors describe a method for performing retroperitoneal lumbar interbody fusion (LIF) in which a threaded cage is placed from L-2 through L-5 via a lateral trajectory, and they also detail a novel technique for implanting a cage from L-5 to S-1 via an oblique trajectory. Although they present data obtained over a 2-year period in the study of 15 patients, the focus of this report is primarily on describing the surgical procedure. METHODS: The lateral lumbar spine was exposed via a standard retroperitoneal approach. Using the anterior longitudinal ligament as a landmark, the L2-3 through L4-5 levels were fitted with instrumentation via a true lateral trajectory; the L5-S1 level was fitted with instrumentation via an oblique trajectory. A single cage was placed at each instrumented level. Fifteen symptomatic patients in whom previous lumbar fusion had failed underwent retroperitoneal LIF. Thirty-eight levels were fitted with instrumentation. There have been no instrumentation-related failures, and fusion has occurred at 37 levels during the 2-year postoperative period. CONCLUSIONS: The use of retroperitoneal LIF in which threaded fusion cages are used avoids the technical difficulties associated with repeated posterior procedures. In addition, it allows L2-S1 instrumentation to be placed anteriorly via a single surgical approach. This construct has been shown to be biomechanically sound in animal models, and it appears to be a useful alternative for the management of failed multilevel intertransverse arthrodesis.