Faculty Bibliography

The aim of this retrospective study was to identify risk factors for hospital-acquired Clostridium difficile infection (HA-CDI) in orthopaedic patients. Thirty-two HA-CDI cases were each matched with two controls. Incidence rate was 0.33 cases per 1000 patient-days. Univariate analyses showed that surgery >24 h after admission, antibiotics for treatment, and proton pump inhibitors were associated with HA-CDI. Multivariate analyses revealed that surgery >24 h after admission was associated with HA-CDI. Patients hospitalized before surgery had a greater risk of HA-CDI, suggesting opportunities to reduce environmental exposure to C. difficile by timelier preoperative medical optimization in the outpatient setting.

BACKGROUND: There is still little known regarding the effects of meniscus resection size on tibiofemoral stability. PURPOSE: To determine if partial medial meniscectomy of the posterior horn significantly alters tibiofemoral stability as measured by the anterior-posterior (AP) position and laxity of the medial femoral condyle. STUDY DESIGN: Controlled laboratory study. METHODS: Five cadaveric knees were dissected to the capsule, preserving all ligaments and the quadriceps tendon. Each specimen was first tested on a rig where the AP position and laxity of the medial femoral condyle were measured while a range of forces was applied from full extension to 90 degrees of flexion. Magnetic resonance imaging (MRI) at 3 tesla was then performed for baseline measurements of the meniscus before partial meniscectomy. Arthroscopic partial medial meniscectomy aimed at 30% of the posterior horn was then performed, followed by repeat mechanical testing and MRI. The sequence was then repeated for arthroscopic partial meniscectomy aimed at 60% and 100% of the posterior horn of the medial meniscus. RESULTS: The MRI analysis demonstrated that 22% +/- 9% of the original width of the posterior horn was removed at the first resection, 46% +/- 11% was removed at the second resection, and the third resection was 100% removal of the posterior horn for all specimens. After 22% resection, no significant difference in AP laxity was observed. A statistically significant increase in AP laxity was observed with 46% resection under a 500-N compressive load compared with the intact meniscus. After full resection, significant increases in AP laxity were observed under a 50-N compressive load compared with the intact and 22% and 46% resections. The 22% resection had similar AP positions as the intact knee, whereas the 46% resection and 100% removal of the posterior horn had statistically further posterior AP positions than the intact knee. CONCLUSION: Partial medial meniscectomy with >/=46% resection of the original width of the posterior horn significantly altered the AP position of the medial femoral condyle and also increased laxity. CLINICAL RELEVANCE: These mechanical changes may lead to abnormal cartilage loading and early osteoarthritis.

Management of traumatic soft-tissue injuries remains a challenging and ever evolving field within orthopedic surgery. The basic principle of addressing life before limb in the initial assessment of critically injured patients has not changed. Although arteriography remains the gold standard for vascular injury screening, computed tomography angiography is being used more often to determine limb viability, and its sensitivity and specificity for detecting vascular lesions are reported to be excellent. Thorough debridement and irrigation with early institution of antibiotics are crucial in preventing infection; debridement should be performed urgently once life-threatening conditions have been addressed. Increasing use of vacuum-assisted closure therapy has created a trend down the reconstructive ladder, with improvements in resulting wound closure. Although the orthoplastics approach and new microsurgical techniques have made limb salvage possible in even the most severely injured extremities, it is important to clearly identify the zone of injury and to inform patients and their families of the outcomes of limb salvage versus amputation. Results from the LEAP (Lower Extremity Assessment Project) trials and similar studies should guide orthopedic surgeons in the management of these complex injuries. Nevertheless, it is important to individualize management plans according to patient factors.

Pulmonary metastasis remains the leading ca use of death for cancer patients. Opportunities to improve treatment outcomes for patients require new methods to study and view the biology of metastatic progression. Here, we describe an ex vivo pulmonary metastasis assay (PuMA) in which the metastatic progression of GFP-expressing cancer cells, from a single cell to the formation of multicellular colonies, in the mouse lung microenvironment was assessed in real time for up to 21 days. The biological validity of this assay was confirmed by its prediction of the in vivo behavior of a variety of high- and low-metastatic human and mouse cancer cell lines and the discrimination of tumor microenvironments in the lung that were most permissive to metastasis. Using this approach, we provide what we believe to be new insights into the importance of tumor cell interactions with the stromal components of the lung microenvironment. Finally, the translational utility of this assay was demonstrated through its use in the evaluation of therapeutics at discrete time points during metastatic progression. We believe that this assay system is uniquely capable of advancing our understanding of both metastasis biology and therapeutic strategies.

We present the case of a patient with malignant transformation of a liposclerosing myxofibrous tumor. The patient had a histologically confirmed liposclerosing myxofibrous tumor that, during a course of 22 months, spontaneously transformed into a lesion appearing like a benign giant cell reactive lesion and subsequently into a high-grade bone sarcoma. Few such cases of spontaneous malignant transformation of liposclerosing myxofibrous tumor have been reported. We report what we believe to be the first case documenting spontaneous transformation of a liposclerosing myxofibrous tumor into an intermediate lesion with benign-appearing histologic features and then into a high-grade malignant tumor.

BACKGROUND: Strain injury to the adductor longus muscle is a common cause of groin pain in athletes and generally occurs in the proximal portion of the muscle, near its origin from the anterior aspect of the pubis. The composition and cross-sectional anatomy of this muscle's origin has not been previously described. HYPOTHESIS: We hypothesize that the adductor longus muscle origin is composed mainly of muscle fibers and that the tendon composes only a small part of the cross section at the origin of the muscle. STUDY DESIGN: Descriptive laboratory study. METHODS: We harvested 42 adductor longus muscles from 28 cadavers and measured the cross-sectional dimensions of the tendon with microcalipers. Next, we determined the relative contributions of the tendon and muscle fibers to the cross-sectional anatomy of the muscle using optical scanning. These 2 sets of measurements were obtained at 3 locations: at the muscle origin and 1.0 and 2.0 cm distal to the origin. RESULTS: The average length and width of the tendon was 11.6 and 3.7 mm, respectively, at the origin. The average cross-sectional areas of the tendon were 49.3, 27.9, and 25.7 mm(2) at points 0.0, 1.0, and 2.0 cm from its origin, respectively. The origin of the adductor longus muscle was composed of 37.9% tendon and 62.1% muscle tissue. At 1.0 cm from the origin, the percentage of tendon decreased to 34%. At 2.0 cm from the origin, the tendon composed 26.7% of the cross section. CONCLUSION: The cross-sectional area of the tendon of the adductor longus muscle is relatively small. The muscle origin is composed predominantly of direct attachment of muscle fibers. CLINICAL RELEVANCE: Knowledge of the cross-sectional anatomy of the adductor longus muscle at its origin may help clinicians better understand the complex nature of injuries in this area