A comparison of the inflammatory host response to particulate debris adjacent to unlocked and locked screws of a growth guidance system for early onset scoliosis.

PURPOSE: The SHILLA™ Growth Guidance system is a stainless-steel rod and screw system used for Early Onset Scoliosis which incorporates a unique flanged set screw designed to capture the rod, while allowing it to slide as the patient grows. Concomitant with this design is the potential for generation of wear debris and for an inflammatory host response. We hypothesized that the magnitude of the host response adjacent to the unlocked screws and rods would be greater than the host response to the locked rod/screws. METHODS: Seven tissue samples adjacent to locked (3) and unlocked screws (4) from three SHILLA patients (mean implantation time of 19 post-operative months) with infantile idiopathic scoliosis were obtained as part of an explant analysis protocol during a PMDA-approved clinical trial in Japan. Gross appearance, high-resolution radiographs, and histology were assessed. ISO Standard 10993 Part 6 was used to assess the host response. RESULTS: All three locked screw had no metallosis. In contrast, metallosis for unlocked screw tissue samples were rated as "ubiquitous" (2/4), "focal" (1/4), or "absent" (1/4). Microscopic metallic debris was found intracellularly and within interstices of fibrous connective tissues more frequently adjacent to unlocked screws compared to locked screws. Cell type and population scoring consistently showed a modestly larger inflammatory response (macrophages) in the unlocked tissue samples. CONCLUSIONS: The peri-prosthetic tissue response to the unlocked rods/screws had a higher reactivity grade (slight reaction, Δ = 4.0) per ISO 10993 Part 6 compared to the locked screws in three patients with the SHILLA™ Growth Guidance scoliosis system.

The Top 50 Most-Cited Articles on Thoracolumbar Fractures.

OBJECTIVE: To identify the top 50 most-cited articles in the literature focusing on thoracolumbar spine fractures. METHODS: Using the ISI Web of Science version 5.11 database and the search phrase "thoracolumbar fracture," we queried for the 50 most-cited articles on thoracolumbar fractures. The study was performed in September 2017. We searched for articles published between 1900 and 2017. Articles were sorted and ranked based on the total number of citations. We evaluated the following information pertaining to each article: first author, year of publication, journal, and title. RESULTS: A total of 2718 studies matched our search criteria, of which the top 50 most-cited ranged between 267 and 81 citations. Twelve articles were cited more than 200 times. The article by McLain et al. was the most-cited article, with 267 citations, followed by Vaccaro et al. with 237 and Mumford et al. with 236. The majority of the studies originated from the United States (n = 26) and were published in the 1990s. Spine was the most frequent destination journal (n = 26), followed by the Journal of Bone and Joint Surgery (n = 7). Most of the articles focused on the clinical management of thoracolumbar fracture (82%). Vaccaro and McAfee were the most cited first authors, with 3 articles each. CONCLUSIONS: Thoracolumbar fractures are the most common injuries of the spine, and the incidence is increasing globally. To understand current treatment guidelines and how treatment of these fractures has evolved, it is important to know the most-cited articles pertaining to these fractures.