Traumatic pneumorrhachis: etiology, pathomechanism, diagnosis, and treatment.

BACKGROUND CONTEXT: Traumatic pneumorrhachis (PR) is a rare entity, consisting of air within the spinal canal. It can be classified as epidural or subarachnoid, identifying the anatomical space where the air is located, and is associated with different etiologies, pathology, and treatments. PURPOSE: To conduct a systematic review of the scientific literature focused on the etiology, pathomechanism, diagnosis, and treatment of PR, and to report a case of an asymptomatic epidural type. STUDY DESIGN: International medical literature has been reviewed systematically for the term "traumatic pneumorrhachis" and appropriate related subject headings, such as traumatic intraspinal air, traumatic intraspinal pneumocele, traumatic spinal pneumatosis, traumatic spinal emphysema, traumatic aerorachia, traumatic pneumosaccus, and traumatic air myelogram. All cases that were identified were evaluated concerning their etiology, pathomechanism, and possible complications. SAMPLES: Studies that included one of the aforementioned terms in their titles. METHODS: A systematic review was performed to identify, evaluate, and summarize the literature related to the term "traumatic pneumorrhachis" and related headings. Furthermore, we report a rare case of an asymptomatic epidural PR extending to the cervical and thoracic spinal canal. We present the current data regarding the etiology, pathomechanism, diagnosis, and treatment modalities of patients with PR. RESULTS: The literature review included 37 related articles that reported 44 cases of traumatic PR. Only isolated case reports and series of no more than three cases were found. In 21 cases, the air was located in the epidural space, and in 23 cases, it was in the subarachnoid space. Most of the cases were localized to a specific spinal region. However, eight cases extending to more than one spinal region have been reported. CONCLUSIONS: Traumatic PR is an asymptomatic rare clinical entity and often is underdiagnosed. It usually resolves by itself without specific treatment. We stress the significance of this information to trauma specialists, so that they may better differentiate between epidural and subarachnoid PR. This is of great significance because subarachnoid PR is a marker of severe injury. The management of traumatic PR has to be individualized and frequently requires multidisciplinary treatment, involving head, chest, and/or abdomen intervention.

Cadaveric study of anterior cruciate ligament failure patterns under uniaxial tension along the ligament.

PURPOSE: The purpose of our study was to clarify the events that take place during anterior cruciate ligament (ACL) failure, focusing on the behavior of the ACL as a composition of multiple fibers, during uniaxial tension along the ligament. METHODS: Ten fresh-frozen human cadaveric knee specimens were fixed in an Instron machine (Instron, Norwood, MA), and load was applied parallel to the ACL axis. Two cameras were used to detect the failure mode of the ACL and its different groups of fibers. The distinct bundles of fibers were marked in each specimen before testing. The macroscopic findings during the experiment were used for comparison with the biomechanical results. RESULTS: The ACL showed a non-monotonic response during testing. The load-elongation curve showed a plateau or a second peak after the initial drop in load. Macroscopically, some fibers were failing initially, whereas the intact fibers had a remaining load potential. In our setting, 3 different failure patterns were recognized, specifically, a midsubstance tear of the anteromedial or the posterolateral bundle with a subsequent failure of the intact bundle or an initial avulsion of the anteromedial attachment. Analysis of the video frames showed a direct connection between the failure patterns in the load-elongation curves and the macroscopic sequence of events during ACL failure. CONCLUSIONS: The ACL ligament acts as a multifiber construction. In our setting, rupture follows 3 specific patterns where a complete or partial tear of the fiber bundles occurs first and the remaining intact fiber bundles have a potential load resistance. CLINICAL RELEVANCE: Our study allows a better understanding of the mechanical properties of the ACL. An update on the biomechanics of ACL failure during uniaxial tension after the "double-bundle revolution" could provide data helpful for ACL reconstruction.

Solitary tibial osteolytic lesion.

We report an unusual case of solitary osteolytic tibial metastasis from a primary endometrial cancer in a 62-year-old woman. The primary cancer was treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy combined with postoperative external beam radiotherapy, while the tibial metastasis was treated with an above knee amputation. The rarity of the case lies on the fact that metastases distally to the elbow and knee are uncommon and endometrial cancer rarely gives distal bone metastases and particularly solitary to the extremities.