Pseudomonas aeruginosaSeptic Arthritis and Osteomyelitis after Closed Reduction and Percutaneous Pinning of a Supracondylar Humerus Fracture: A Case Report and Review of the Literature

Infectious complications of closed reduction and percutaneous pinning of supracondylar humerus fractures are exceedingly rare. Although postoperativePseudomonasinfection is a feared complication associated with noncompliance and a wet cast, there are no reports in the literature of this occurring. We present the devastating complication of a pediatric patient who developedPseudomonas aeruginosasubperiosteal abscess, osteomyelitis, and elbow septic arthritis after presenting to the clinic multiple times with a wet cast after closed reduction and percutaneous pinning of a supracondylar humerus fracture. We describe the treatment course for this patient, followed by the sequelae of posterolateral rotary instability. This case not only confirms that patients can getPseudomonasinfections if they get their cast wet but also stresses the importance of patient communication and compliance in preventing unfortunate complications.

A Cadaveric Study: Is There a Correlation Between Clinical Tests for Anterior-Posterior Laxity and Rotary Instability?

Instability is not necessarily determined by knee laxity, yet passive clinical tests are included in the examination which determines the functional status of the knee. The current arthrokinematic findings and validated clinical tests support the definition of excessive sagittal plane and frontal-plane laxity; however it is unknown if these findings in a single plane predict rotary instability of the knee.

Reconstructions of the Knee Following Combined Injury to the Posterior Cruciate Ligament and the Posterior Lateral Structures

The posterior cruciate ligament (PCL) provides primary restraint to posterior tibial translation (1). Knee injuries involving only the PCL usually result in minimal disability, and are commonly treated non-surgically (2). However, combined injuries of the PCL and the posterior lateral structures (PLS) in the knee can result in considerable abnormal posterior laxity and posterolateral rotary instability leading to rapid cartilage degeneration (3). There is consensus that, in most cases, knees with this combined injury require surgical reconstruction.

Characterization and Detection of Crack-induced Rotary Instability

System instability and chaotic response are the failure modes that could significantly impact the reliability and operating safety of high-speed rotor-dynamical machines. Initiation and propagation of surface cracks in rotary shafts are common causes for such failure modes. To be able to detect the onset and progression of these faults will considerably extend the lifetime and improve the reliability of the mechanical system. A wavelet-based algorithm effective in identifying mechanical chaotic response has been applied to determine the nonlinear dynamical characteristics of a model-based, cracked rotor. This investigation confirms reported correlation of surface crack breathing with rotor chaotic motions. The effectiveness of the algorithm in detecting rotor-dynamic instability induced by mechanical faults as contrast to algorithms that are based on nonlinear dynamics is discussed. The results show not just the feasibility of the algorithm in mechanical fault diagnosis but also suggest its applicability to in-line, real-time condition monitoring at both the system and component levels.