A Cadaveric Study Measuring Femoral Nerve Tension During Anterior Total Hip Arthroplasty Approach.

Femoral nerve palsy is a rare but devastating complication of anterior total hip arthroplasty. Its etiology is still unknown, but several studies have suggested that anterior acetabular retractors may place the femoral nerve at increased risk. This study hypothesized that hip extension and traction places tension on the femoral nerve, offering an additional explanation for the development of femoral nerve palsy. A spring device was secured across 6 transected femoral nerves from 5 lower extremity cadavers and the hip was extended and pulled into traction with and without retractor placement. The change in spring length was used to determine femoral nerve tension. The average spring length changed +8.83 mm with hip extension, +3.73 mm with traction, -0.7 mm with traction and placement of the anterior acetabular retractor, and -1.15 mm with extension and placement of the femoral retractor. Femoral nerve tension was greatest with hip extension followed by traction. Acetabular and femoral retractor placement decreased average femoral nerve tension in both traction and hip extension. This may be due to medialization of the femoral nerve by the retractors, reducing the overall distance traveled, and thereby reducing tension. Previous studies have found femoral nerve pressure to be greatest during anterior acetabular retractor placement. It is likely that both pressure and tension contribute to femoral nerve palsy. Careful retractor placement, staying safely on anterior acetabular bone, and efficient femoral preparation to decrease time under hip extension and traction may help to minimize the risk of femoral nerve palsy.

An Online Learning Tool to Obtain, Optimize, and Interpret Radiographs During Total Hip Arthroplasty.

Total hip arthroplasty (THA) is a common orthopedic procedure which has been growing in popularity with the elderly population. With more surgeons completing anterior THAs, intraoperative radiographs have become commonplace. Unfortunately, there is a lack of education in regard to obtaining, optimizing, and interpreting these radiographs. The purpose of this study was to develop and test the efficacy of an online learning tool that medical students, residents, and C-arm technicians could use to improve their understanding of THA radiography. The learning tool taught users how to obtain an optimal AP pelvis radiograph and how to interpret radiographs so THA components could be placed in their optimal position. This learning tool was sent to medical students, orthopedic surgery residents, and C-arm technicians along with a pre-test, post-test, and feedback survey. Twenty users (eleven medical students and nine orthopedic surgery residents) completed the learning tool. Post-test scores (M=96.4%, SD=2.9%) were significantly greater than pre-test scores (M=68.3%, SD=23.9%) for all users (t=5.5069, P<.0001). The user's level of training was positively correlated with pre-test scores. Surveys from the users revealed that the learning tool provided significant learning opportunities, was relatively easy to understand, but was slightly too long. Users felt that this learning tool would be best suited for senior medical students, junior orthopedic surgery residents, and C-arm technicians. With the positive results of this study, the authors hope to further develop this learning tool for widespread adoption and to develop similar learning tools in the future.

Implications of Spinopelvic Mobility on Total Hip Arthroplasty: Review of Current Literature.

Understanding the impact of pathologic spinopelvic mobility on total hip arthroplasty instability requires an appreciation of the dynamic interplay between and the spine, hip and pelvis. This complex interdependent relationship changes with position, pathology and surgical intervention. Spinal pathology may prevent normal dynamic motion leading to spinopelvic stiffness and abnormal pelvic position. Patients at high risk for pathologic spinopelvic motion and subsequent total hip arthroplasty (THA) dislocation should be assessed with a functional imaging series with lateral standing, sitting and AP standing radiographs. Common patterns of stiffness and imbalance as well as proposed surgical treatment algorithms are presented and discussed in this review.

Maisonneuve fracture associated with a bimalleolar ankle fracture-dislocation: a case report.

The Maisonneuve fracture consists of a proximal fibular fracture with associated syndesmotic ligament disruption and injury to the medial ankle structures. The accepted mechanism of injury is an external rotation force applied to the ankle with the foot in either supination or pronation. Because most Maisonneuve fractures involve complete syndesmotic disruption, operative treatment is usually indicated. A case report is presented of an unusual fracture pattern-i.e., that of a distal fibular fracture with lateral ankle dislocation associated with a Maisonneuve fracture. To our knowledge, only two other similar cases are reported in the English literature.