Edward C. Benzel

Posterior Atlantoaxial Fixation with Screw-Rod Constructs: Safety, Advantages, and Shortcomings

he use of screw-rod constructs for subaxial cervical spinal fusions has become commonplace, with the widespread T use of lateral mass bone screws, small polyaxial screw heads, and compatible rods. Goel and Harms expanded the use of segmental screw fixation to C1-C2 fusion applications, which they described in their technique and case series articles in 1994 and 2001 (1, 2). Since then, the use of screw-rod fixation for various atlantoaxial pathologies has expanded greatly. The GoelHarms technique of C1-C2 fixation has been applied for traumatic injuries involving the atlantoaxial complex to various degenerative, oncologic, and congenital malformations that result in atlantoaxial instability. To date, more than 700 publications have reported on the novel use, testing, or comparison of the technique to other previously described fixation modalities. Screwrod fixation of the atlantoaxial complex has become the preferred method of fusion of C1-C2 at our institution for many years. We think it offers significant ease of use, favorable biomechanical properties, and flexibility when used in challenging clinical situations. However, there exist perceived and real compromises with this approach that can affect patient outcome.

C1-C2 fusion: promoting stability, reducing morbidity.

he surgical treatment of atlantoaxial instability has been evolving for more than 100 years. The first report was T a case presentation in 1910, by Mixter and Osgood (30), who described using heavy silk thread to secure the posterior arch of the atlas to the spinous process of the axis. The next few decades were associated with multiple advances, including approaches using dorsal cervical wiring techniques. These included the Gallie technique (13, 16, 27), the Brooks-Jenkins technique (5), and the technique of Dickman and Sonntag (9) and Dickman et al. (10). Nonwiring techniques included interlaminar clamps (21), the Magerl transarticular screw technique (26), plate and screw techniques (17, 18), rod-cantilever techniques (19, 33, 40), translaminar screw techniques (25, 42, 43), and a variety of other strategies (28, 32). Although the approaches and indications vary, the fusion rates for these procedures have been observed to be as high as 90%e100% (2, 9, 12, 28).

The Employment of the “Sniff Test”

T he testing of a spinal construct by mechanical means is fraught with difficulty. Oftentimes, in the case of published studies, the data acquired and presented are found to be tatistically significant. Although, on the surface, the study may ppear to be methodologically sound, the actual and literal concluions may, in fact, be irrelevant to the clinical situation at hand. The tudy presented herein by Daniel et al. is no exception. I am not eing critical of Daniel et al. in particular; nor am I singling them out. am, conversely, casting aspersions on the majority of biomechanial studies that assess the integrity and efficacy of spinal constructs n cadavers via quasistatic flexibility testing strategies.

Use of CT Based Intraoperative Spinal Navigation: Utility versus Risk

W T he notion that radiation exposure is toxic is not a revelation. We have seen the devastation it can wreak from prior experiences, such as the Manhattan Project, Nagaaki, Hiroshima, Chernobyl, and now the Japanese tsunami. oentgen, in a sense, unleashed a monster that can be haressed to, on the one hand, much good. However, on the other and, radiation can cause harm. The aforementioned manmade isasters each had “two edges” to their “swords.” The positive dges included the ending of wars and the provision of energy. he negative edges were associated with radiation contaminaion, disability, and death.

Occipitocervical Fusion in Elderly Patients: Lessons Learned

I t goes without saying that occipitocervical fusion is different today than yesterday. Technologies and techniques have improved. Our knowledge base regarding occipitocervical athologies and their management has broadened and deepned. Simultaneously, however, our patient population has aged, ith the 80-year-old patients of today being physiologically imilar to 70-year-old patients of 2 decades prior. So our aging opulation is becoming more fit and tolerant of surgical insults, hile our ability to “intelligently” decompress and stabilize the pine is becoming safer and more effective. With that informaion at hand, we surgeons are gradually acquiring an increased argin of safety and effectiveness. What a deal!