Anatomical considerations of C2 lamina for the placement of translaminar screw: a review of the literature.

PURPOSE: The thorough knowledge of C2 lamina anatomy is essential for the avoidance of complications during screw fixation. We performed a review of the literature, aiming to detect what was found about anatomical feasibility of C2 translaminar fixation in different populations, along with possible recommendations for the avoidance of complications, and to detect whether factors such as race or gender could influence axis lamina anatomy and fixation feasibility. METHODS: We performed a search in PubMed and Cochrane database of systematic reviews for studies which correlated axis lamina anatomy with fixation feasibility. We extracted data concerning measurements on C2 lamina, the methods and conclusions of the studies. RESULTS: Twenty-six studies met our inclusion criteria. The studies mainly focused on Asian populations. Male gender was generally related to larger anatomical parameters of C2 lamina. The use of a C2 translaminar screw with a diameter of 3.5 mm was generally feasible, even in children, but there was disagreement about risk of vertebral artery injury. Computed tomography was most frequently recommended preoperatively. Three-dimensional reconstruction was suggested by some authors. CONCLUSION: C2 lamina anatomy generally permitted screw fixation in most studies, but there was disagreement about risk of vertebral artery injury. Preoperative computed tomography was generally recommended, while, according to some authors, three-dimensional reconstruction could be essential. However, there is a relative lack of studies about non-Asian populations. More research could further illustrate the anatomy of C2 lamina, clarify the safety of axis fixation for more populations and perhaps modify preoperative imaging protocols.

Morphometric analysis of the odontoid process: using computed tomography--in the Greek population.

AIM: A morphometric analysis of the odontoid process of the A2 vertebra, in the Greek population, was conducted using CT scan. We aimed to determine the feasibility to use one or two screws when treating fractures of this anatomic element. PATIENTS AND METHODS: One hundred and fifteen patients (57 men) of a mean age of 48 years (16-95 years) underwent a cervical spine CT scan examination. The anterior-posterior and transverse diameters of the odontoid process were measured from the base, at 1-mm interval upward on axial CT images. The length from the tip of the odontoid process to the anterior-inferior angle of the body of the axis was calculated. Data concerning the height and weight of the examined patients were collected. RESULTS: The mean transverse and anterior-posterior distances were found to be 11.46 and 10.45 mm, respectively, for the upper end of the odontoid process. At the neck level of the odontoid process, the equivalent mean values were 11.12 and 8.73 mm, respectively, while at the base, these distances were found to be 13.84 and 12.3 mm, respectively. The mean distance from the tip of the odontoid to its base was 17.25 and 17.28 mm, respectively, while the mean distance from the tip of the dens to the anterior-inferior corner of the axis' body was 39.2 mm. Men showed greater values than women. CONCLUSIONS: In this study, it was shown that in the Greek population there is enough room for one 4.5-mm or one 3.5-mm cannulated screw to be used. The application of two 3.5-mm screws is feasible in 58.6 % of the male and 26.3 % of the female population. This confirms that the knowledge of the true dimensions of the odontoid process is of paramount importance before the proper management of fractured dens using the anterior screw technique.

Comparative study of internal and hybrid external fixation in tibial condylar fractures.

BACKGROUND: The spectrum of injuries to the tibial plateau is so great that no single method of treatment has been proven to be uniformly successful. The purposes of this study were to evaluate the clinical results, to identify the advantages and disadvantages and to take out useful conclusions of the application of the internal and hybrid external fixation in the treatment of these fractures. METHOD: Sixty tibial condylar fractures, of all types, according to Schatzker's classification were treated with open reduction and internal fixation (30 patients) or with hybrid external fixation (30 patients). The following parameters were recorded: time of surgical procedure, time of postoperative hospitalization, time of starting of weight bearing on the affected extremity, complications, and postoperative functional (according to Knee Society Score) and radiological results (according to Rasmussen's Radiological Score). The average time of follow-up was 12 months. RESULTS: Neither of the two methods showed superiority regarding the duration of the surgical procedure [mean difference 4.4 ± 5.4 (min), P = NS], the postoperative hospitalization time [0.6 ± 0.7 (days), P = NS], and the radiological and functional evaluation (χ(2), P = NS for all comparisons). However, the internal fixation method proved to be superior to the hybrid external fixation regarding the time of starting the weight bearing [3.1 ± 0.4 (weeks), P < 0.001]. CONCLUSION: Internal fixation showed superiority to the time starting of weight bearing as it occurred at an earlier time than that of hybrid external by almost 3 weeks whereas no other differences were identified in the other parameters regarding patients' rehabilitation.

Successful treatment of congenital pseudarthrosis of the tibia: still a challenge.

The congenital pseudarthrosis of the tibia (CPT) is one of the most challenging problems in pediatric orthopedics. The primary treatment goals are outlined as osteosynthesis, stabilization of the ankle mortise by fibular stabilization and lower-limb-length equalization. Despite the fact that each of the aforementioned goals is difficult to be achieved regardless the surgical option, the main biological consideration is the same: pseudarthrosis resection, biological bone bridging of the defect by stable fixation and the correction of any angular deformity. The external fixation method is suggested as valuable treatment of CPT because it can address not only pseudarthrosis but also all complex deformities associated with this condition. However, treatment of CPT is impaired with complications due to the complex nature of the disease thus failure is common. The most common of these are refracture, growth disturbance, poor foot and ankle function with stiffness. Of these, refracture is the most common and serious complication after primary healing and might result in the reestablishment of pseudarthrosis. Therefore, an effective, safe and practical treatment method that minimizes the residual challenges after healing and accomplishes the multiple goals of treatment is needed. In this article, we report a patient with CPT treated successfully with external fixation. Level of evidence IV retrospective.

Fixed versus mobile bearing knee arthroplasty: a review of kinematics and results.

There are several total knee arthroplasty designs available with wide variation in features. The long-term results of total knee replacement with a fixed bearing design have shown a high degree of clinical success. However, implant loosening and polyethylene wear became recognized as long-term causes of late failure. Mobile bearing knee replacements were designed to create a durable surface articulation by using a polyethylene insert that articulates with a metallic femoral component and a metallic tibial tray. The purpose of this article is to review clinical and basic scientific studies comparing the clinical results, the biomechanical features, and the kinematic patterns of fixed versus mobile bearing knee designs. Beside the fact that in vitro kinematic studies have shown reduced polyethylene wear in mobile bearings due to increased implant conformity and reduced polyethylene contact stresses, which should hypothetically prolong polyethylene life, various independent studies for both mobile bearing and fixed bearing prostheses have documented results that are comparable in terms of survival and performance.