A thorough understanding of anterior cruciate ligament (ACL) function and the effects of surgical interventions on knee biomechanics requires robust technologies and simulation paradigms that align with clinical insight. In vitro orthopedic biomechanical testing for the elucidation of ACL integrity doesn't have an established testing paradigm to simulate the clinical pivot shift exam on cadaveric specimens. The study aim was to develop a robotically simulated pivot shift that represents the clinical exam. An orthopedic surgeon performed a pivot shift on an instrumented ACL-deficient cadaver leg to capture 6 degree-of-freedom motion/loads. The same knee was mounted to the robot and the sensitivity of the motion/loading profiles quantified. Three loading profile candidates that generated positive pivot shifts on the instrumented knee were selected and applied to 7 ACL-intact/deficient specimens and resulted in the identification of a profile that was able to induce a positive pivot shift in all ACL-deficient specimens (p < 0.001). The simulated shifts began at 22 ± 8°and ended at 33 ± 6°of flexion with the average magnitude of the shifts being 12.8 ± 3.2 mm in anterior tibial translation and 17.6 ± 4.3°in external tibial rotation. The establishment and replication of a robotically simulated clinical pivot shift across multiple specimens show the robustness of the loading profile to accommodate anatomical and experimental variability. Further evaluation and refinement should be undertaken to create a useful tool in evaluating ACL function and reconstruction techniques. Statement of clinical significance: Creation and successful demonstration of the simulated clinical pivot shift validates a profile for robotic musculoskeletal simulators to analyze ACL related clinical questions.

Transcription-coupled repair (TCR) is a subpathway of nucleotide excision repair (NER) in which excision repair proteins are targeted to RNA polymerase-arresting lesions located in the transcribed strand of active genes. TCR has been documented in a variety of bacterial and eukaryotic organisms but has yet to be observed in the Archaea. We used Halobacterium sp. NRC-1 and Haloferax volcanii to determine if TCR occurs in the halophilic archaea. Following UV irradiation of exponentially growing cultures, we quantified the rate of repair of cyclobutane pyrimidine dimers in the two strands of the rpoB2B1A1A2 and the trpDFEG operons of Halobacterium sp. NRC-1 and the pts operon of H. volcanii through the use of a Southern blot assay and strand-specific probes. TCR was observed in all three operons and was dependent on the NER gene uvrA in Halobacterium sp. NRC-1, but not in H. volcanii. The halophilic archaea likely employ a novel mechanism for TCR in which an as yet unknown coupling factor recognizes the arrested archaeal RNA polymerase complex and recruits certain NER proteins to complete the process.

Background: The classification of fractures is necessary to ensure a reliable means of communication for clinical interaction, education and research. The Neer classification is the most commonly used classification for proximal humerus fractures. In 2018 the Orthopedic Trauma Association (OTA) and the Arbeitsgemeinschaft für Osteosynthesefragen (AO) Foundation provided an update to the OTA/AO Fracture Classification Scheme addressing many of the concerns about the previous versions of the classification. The objective of the present study was to evaluate the rater reliability of the 2 classifications and if the classifications subjectively better characterized the fracture patterns.Methods: X-rays and Computerized Tomography scans of 24 proximal humerus fractures were given to 7 independent raters for classification according to the Neer and 2018 OTA/AO classification. Both full-forms and short-forms of the classifications were tested. The Fleiss Kappa statistic was used to assess inter-rater agreement and intra-rater consistency for the 2 classifications. For each case the raters subjectively commented on how well each classification was able to characterize the fracture pattern.Results: All raters graded the 2018 OTA/AO classification as good as or better than the Neer classification for an adequate description of the fracture patterns. The short-form 2018 OTA/AO classification had the most 4 rater and 5 rater agreement cases and the second most 6 rater agreement cases. The short-form Neer classification had the second most 4 rater and 5 rater agreement cases and the most 6 rater agreement cases. The full 2018 OTA/AO had the least 4, 5, or 6 rater agreement cases of all the classification systems. Inter-rater agreement was fair for the full and short form of both the Neer and 2018 OTA/AO classification. The full and short Neer classifications together with the short 2018 OTA/AO classification had moderate intra-rater consistency, while the full 2018 OTA/AO classification only had slight intra-rater consistency.Conclusions: The 2018 OTA/AO classification is equivalent in its short-form to the Neer classification in inter-rater reliability and intra-rater consistency; and is superior in its full form for characterizing specific fracture types. The low inter-rater reliability of the full 2018 OTA/AO classification is a concern that may need to be addressed in the future.

A pivot shift is a useful exam for evaluating anterior cruciate ligament (ACL) reconstruction surgery. A positive result is a perceived “clunk” and is quantified by the kinematics that occur during the tibial reduction phase. In vitro evaluation of ACL reconstruction techniques includes robotic testing of cadaveric knees where the applied loads represent estimated in situ loads. Early understanding of the mechanism of the pivot shift has resulted in a simplified representation where static “rotary loads” (10Nm valgus torque, 5Nm internal tibial torque) are applied at a few discrete flexion angles, and changes in anterior tibial translation (ATT) are compared [1]. Building upon this work, and with advances in technology, we are now able to create a robotic test that is more like the clinical exam. Our hypothesis was that kinematics produced during the robotically simulated pivot shift would be similar to the clinical pivot shift but would be significantly different from the rotary loads method. The ability for a test to produce larger kinematic differences between native and deficient states may suggest a more robust methodology by which to evaluate the efficacy of ACL reconstructions.

Objectives:To evaluate a proposed orthopaedic-specific surgical wound classification system (SWCS) and the current Centers for Disease Control (CDC) system in a series of detailed clinical vignettes and to identify the degree of satisfaction with CDC SWCS and desire for institution of an orthopaedic-specific SWCS.Methods:Forty-five clinical vignettes and a 5-question survey were distributed to current and past members of the Orthopaedic Trauma Association's Classification Committee. Respondents were asked to provide wound class for each vignette using the CDC system and orthopaedic-specific SWCS.Results:The orthopaedic-specific and CDC SWCS had interclass correlations of 0.95 and 0.91, respectively. When the systems were compared, in 34% of cases, there was no grade change; in 63% of cases, the wound was graded higher using the orthopaedic-specific SWCS. When only the procedure was changed between vignettes, wound classification was infrequently affected. There was near universal dissatisfaction with the CDC SWCS and desire for an orthopaedic-specific system.Conclusions:Both the CDC SWCS and orthopaedic-specific SWCS have excellent interobserver reliability. Incorporation of orthopaedic-specific language affects wound classification. There is low satisfaction with the current CDC SWCS and a desire exists for further development and validation of an orthopaedic-specific SWCS.