Transradial Transcapitate Perilunotriquetral Coalition Fracture Dislocation.

Perilunate fracture dislocations (PLFDs) are uncommon, usually resulting from high-energy trauma. Several classification systems describe the patterns of injury seen, but there is still significant variation and patterns of injury that do not fit within these classifications continue to be described. Carpal coalitions are rare, mostly asymptomatic, and are, as a result, usually identified incidentally. We describe the case of a transradial transcapitate PLFD in a patient with a Minnaar Type 3 lunotriquetral coalition. Radiographic, clinical, and patient-reported outcomes are reported. When presented with a rare anatomical variation in the context of a complex injury, the importance of managing these complex injuries according to principles is highlighted.

Current Concepts in Scapholunate Instability Without Arthritic Changes.

Scapholunate instability (SLI) is the most common carpal instability described. SLI leads to a degenerative arthritic pattern known as scapholunate advanced collapse (SLAC). Diagnosis of SLI can be challenging in pre-dynamic and dynamic stages. CT arthrogram, MR arthrogram and dynamic fluoroscopy are helpful in diagnosis while arthroscopy remains the gold standard. SLI is a multi-ligament injury, which involves not only the scapholunate interosseous ligament (SLIL) but also the extrinsic carpal ligaments. Hence, it is better described as an injury compromising the 'dorsal scapholunate(dSLL) complex'. A repair can be attempted for acute SLI presenting within 6 weeks of injury. Reconstruction is the mainstay of treatment for chronic SLI without degenerative changes. Multiple repair techniques have been described which include capsulodesis and tenodesis procedures. The clinical outcomes of the techniques have improved over the years. However, a common problem of all these techniques is the lack of long-term data on the outcomes and deteriorating radiological parameters over time. SLI staging is an important factor to be considered in choosing the reconstruction techniques for a better outcome. Currently, there is a trend towards more biological and less invasive techniques. Regardless of the technique, it is important to preserve the nerve supply of the dorsal capsuloligamentous structures of the wrist. Arthroscopic techniques being minimally invasive have the advantage of less collateral damage to the capsuloligamentous structures. Rehabilitation involves a team approach where a protected dart thrower's motion is allowed after a period of immobilization. Strengthening SL-friendly muscles and inhibiting SL-unfriendly muscles is a key principle in rehabilitation.

The axial injury tolerance of the human foot/ankle complex and the effect of Achilles tension.

Axial loading of the foot/ankle complex is an important injury mechanism in vehicular trauma that is responsible for severe injuries such as calcaneal and tibial pilon fractures. Axial loading may be applied to the leg externally, by the toepan and/or pedals, as well as internally, by active muscle tension applied through the Achilles tendon during pre-impact bracing. The objectives of this study were to investigate the effect of Achilles tension on fracture mode and to empirically model the axial loading tolerance of the foot/ankle complex. Blunt axial impact tests were performed on forty-three (43) isolated lower extremities with and without experimentally simulated Achilles tension. The primary fracture mode was calcaneal fracture in both groups. However, fracture initiated at the distal tibia more frequently with the addition of Achilles tension (p < 0.05). Acoustic sensors mounted to the bone demonstrated that fracture initiated at the time of peak local axial force. A survival analysis was performed on the injury data set using a Weibull regression model with specimen age, gender, body mass, and peak Achilles tension as predictor variables (R2 = 0.90). A closed-form survivor function was developed to predict the risk of fracture to the foot/ankle complex in terms of axial tibial force. The axial tibial force associated with a 50% risk of injury ranged from 3.7 kN for a 65 year-old 5th percentile female to 8.3 kN for a 45 year-old 50th percentile male, assuming no Achilles tension. The survivor function presented here may be used to estimate the risk of foot/ankle fracture that a blunt axial impact would pose to a human based on the peak tibial axial force measured by an anthropomorphic test device.