Christensen, Tyson C.

Case: A 41-year-old man sustained occipitocervical dislocation (OCD) and atlantoaxial dislocation (AAD) injuries in a motor vehicle collision. These injuries were treated nonoperatively with a hard cervical collar and activity restrictions with an excellent result at 4-year follow-up. Conclusion: OCD and AAD injuries require prompt diagnosis and immobilization. Standard of care for coexisting injuries is occipitocervical fusion; however, some patients have coexisting injuries which may prevent operative treatment. These polytrauma patients require a creative nonoperative approach with close follow-up to avoid neurologic decline.

Background: Increasing body mass index (BMI) has been shown to correlate with increased rates of complications after total knee arthroplasty. To our knowledge, body surface area, body mass, and height have not been investigated in this manner. BMI and body surface area are affected differently by changes in height, and they are affected similarly by changes in weight. The purpose of this study was to quantify revision for any reason, mechanical failure, aseptic loosening, polyethylene wear, reoperation, and any infection after total knee arthroplasty using BMI, body surface area, body mass, and height as continuous variables. Methods: Prospectively collected data from a single institution’s total joint registry were used to analyze 22,243 consecutive knees, in 16,106 patients, treated with a primary total knee arthroplasty from 1985 to 2012. The Kaplan-Meier survival method was used to evaluate revision and other common complications, with outcomes assessed using Cox regression analysis. Smoothing spline parameterization was used on physical parameters in these models. Results: Increasing BMI, body surface area, body mass, and height were associated with an increased risk of any revision surgical procedure, mechanical failure, and aseptic loosening after total knee arthroplasty. The risk of a revision surgical procedure was directly associated with each 1 standard deviation increase in BMI (hazard ratio [HR], 1.19; p < 0.01), body surface area (HR, 1.37; p < 0.01), body mass (HR, 1.30; p < 0.01), and height (HR, 1.22; p < 0.01). This association was especially demonstrated with revision for mechanical failure (BMI: HR, 1.15; p < 0.01; body surface area: HR, 1.35; p < 0.01; body mass: HR, 1.27; p < 0.01; and height: HR, 1.23; p < 0.01). The risk of failure in the subgroups of mechanical failure including a revision surgical procedure for aseptic loosening or polyethylene wear was also associated with increasing body surface area, body mass, and height. Increasing BMI (HR, 1.22; p < 0.01), body surface area (HR, 2.56; p < 0.01), and body mass (HR, 2.54; p < 0.01) were also associated with increased risk of any infection. Conclusions: Increasing BMI, body surface area, body mass, and height were strongly associated with the rates of revision, aseptic loosening, and other common complications following total knee arthroplasty. Body surface area and body mass appear to correlate more strongly with mechanical failure outcomes than BMI or height. Level of Evidence: Prognostic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background: Previous studies have reported variable rates of recurrent lateral patellar instability mainly because of limited cohort sizes. In addition, there is currently a lack of information on contralateral patellar instability. Purpose: To evaluate the rate of recurrent ipsilateral patellar dislocations and contralateral patellar dislocations after a first-time lateral patellar dislocation. Additionally, risk factors associated with recurrent dislocations (ipsilateral or contralateral) and time to recurrence were investigated. Study Design: Cohort study; Level of evidence, 3. Methods: This population-based study included 584 patients with a first-time lateral patellar dislocation occurring between 1990 and 2010. A retrospective review was conducted to gather information about the injury, subsequent dislocations (ipsilateral or contralateral), and structural characteristics including trochlear dysplasia, patella alta, and tibial tubercle to trochlear groove (TT-TG) distance. Risk factors were assessed to delineate associations with subsequent dislocations and time to recurrence. Results: At a mean follow-up of 12.4 years, 173 patients had ipsilateral recurrence, and 25 patients had a subsequent contralateral dislocation. At 20 years, the cumulative incidence of ipsilateral recurrence was 36.0%, while the cumulative incidence of contralateral dislocations was 5.4%. Trochlear dysplasia (odds ratio [OR], 18.1), patella alta (OR, 10.4), age <18 years at the time of the first dislocation (OR, 2.4), elevated TT-TG distance (OR, 2.1), and female sex (OR, 1.5) were associated with recurrent ipsilateral dislocations. Time to recurrence was significantly decreased in patients with trochlear dysplasia (23.0 months earlier time to recurrence; P < .001), elevated TT-TG distance (18.5 months; P < .001), patella alta (16.4 months; P = .001), and age <18 years at the time of the first dislocation (15.4 months; P < .001). Risk factors for subsequent contralateral dislocations included patella alta and trochlear dysplasia. Conclusion: At 20 years after a first-time lateral patellar dislocation, the cumulative incidence of recurrent ipsilateral patellar dislocations was 36.0%, compared with 5.4% for contralateral dislocations. Trochlear dysplasia, elevated TT-TG distance, patella alta, age <18 years at the time of the first dislocation, and female sex were associated with ipsilateral recurrence. Trochlear dysplasia, elevated TT-TG distance, patella alta, and age <18 years at the time of the first dislocation were predictive of a statistically significant decrease in time to recurrence.