Repeatability and reproducibility of a telemanipulated fracture reduction system.

We evaluate the inter- and intraobserver variability of a telemanipulated femur fracture reduction system using a joystick device. Five examiners performed virtual reduction of 3D femur fracture models on two separate occasions. We assessed the inter- and intraobserver variability for the final alignment and reduction. The average difference between testing rounds was only 0.3 mm for overall displacement and 0.5° for overall rotation. There was an average time reduction between rounds of 11.7 s. The mean differences in overall displacement between examiners ranged between 0.2 and 0.9 mm; between 0.2° and 3.2° for overall rotation; and between 9 and 82 s for time to reduction. The time required to complete the reduction did not have a significant effect on the overall displacement or rotation of the final model. Telemanipulated fracture reduction is a reliable and reproducible technique, which does not require extensive training.

Feasibility of a navigated registration technique in FAI surgery.

INTRODUCTION: Arthroscopic femoral osteoplasties might be technically demanding, might cause prolonged operative times and restrict the intraoperative overview. An automated navigated matching process of preoperative CT-data and intraoperative fluoroscopy should allow for noninvasive registration for FAI-surgery. METHOD: Six hip joints were used with a conventional navigation system. Defined osseous lesion (2 × 2 mm) in the femoral neck, head neck junction, and head region were created followed by automated segmentation including CT-fluoro image fusion by the navigation system. Precision of registration process was tested trough a lateral arthroscopic portal. In vivo distances between pointer tip to bone were measured. Secondary in vivo distances between an inserted navigated shaver and the osseous lesions were measured. RESULTS: Our results allow a CT-fluoroscopy matching procedure for noninvasive registration process for navigated FAI-surgery in multiplanar planes. Precision is more accurate at the femoral neck and head-neck junction than at the femoral head area. CONCLUSION: Future navigated applications might simplify and increase precision of FAI-surgery.

Comparing stability of different single- and double-bundle anterior cruciate ligament reconstruction techniques: a cadaveric study using navigation.

PURPOSE: The objective of this study was to analyze 2 different single-bundle anterior cruciate ligament (ACL) reconstruction procedures and compare their ability to reduce the pivot-shift phenomenon with an anatomic double-bundle (DB) technique. METHODS: Twelve fresh-frozen cadaveric hip-to-toe lower extremity specimens were used. ACL reconstructions were performed by conventional single-bundle, anteromedial (AM) single-bundle, and DB techniques. Anterior tibial translation was measured in the intact knee, ACL-deficient knee, and the 3 ACL reconstructions in response to a Lachman test and a mechanized pivot-shift test. A surgical navigation system (Praxim Medivision, Grenoble, France) simultaneously tracked kinematics. RESULTS: Intact knees were clinically graded as grade 0 (n = 12). ACL-deficient knees were graded as grade 1 (n = 10) and grade 2 (n = 2). With a mechanized pivot-shift test, anterior tibial translation was 1.7 +/- 3.0 mm, 9.7 +/- 3.8 mm, 4.4 +/- 1.0 mm, 1.8 +/- 1.5 mm, and -1.7 +/- 3.3 mm for intact knees, ACL-deficient knees, conventional technique, AM technique, and DB technique, respectively. There was a significant difference between the DB technique and both single-bundle techniques tested (P < .05). CONCLUSIONS: The model used represents an isolated ACL injury without concomitant injury to the capsuloligamentous restraints or menisci. However, during the pivot shift, neither type of single-bundle ACL reconstruction stabilized the knee to the same degree as the DB ACL reconstruction. CLINICAL RELEVANCE: In this cadaveric model a DB repair offers great anterior and rotational stability. Although this study suggests that the DB technique is biomechanically superior to a single-bundle technique using traditional transtibial tunnel positions, there appear to be minimal differences in knee kinematics during stability testing with the DB technique versus an AM graft position. Indeed, compared with the AM position alone, the DB technique "overconstrained" the kinematics of the knee during a pivoting maneuver at time zero in a cadaveric model with an isolated ACL injury.

Mechanized pivot shift test achieves greater accuracy than manual pivot shift test.

The objective of this study was to design a navigated mechanized pivot shift test setup and evaluate its repeatability in the ACL-deficient knee. It was hypothesized that translations and rotations measured with the mechanized pivot shift would be more repeatable when compared to those obtained with a manual pivot shift. Twelve fresh frozen cadaveric hip-to-toe whole lower extremities were used for this study. A manual pivot shift test was performed in the intact knee and in the ACL-deficient knee and was repeated three times. A navigation system simultaneously recorded tibial translation and rotation. The mechanized pivot shift test consists of a modified continuous passive motion (CPM) machine and a custom-made foot holder to allow for the application of internal rotation moments at the knee. Valgus moments were achieved by a 45 degrees tilt of the CPM machine with respect to the supine position and a Velcro strap secured across the proximal tibia. The mechanized pivot shift was repeated three times. Repeated measures ANOVA was used to compare manual and mechanized pivot shift testing. An intra-class correlation coefficient (ICC) was used to determine variability within each knee at each testing condition. In the ACL-deficient knee, translation with manual pivot shift testing (11.7 +/- 2.6 mm) was significantly higher than with mechanized pivot shift testing (7.4 +/- 2.5 mm; p < 0.05). Rotation with the manual pivot shift testing (18.6 +/- 5.4 degrees) was also significantly higher than with mechanized pivot shift testing (11.0 +/- 2.3 degrees; p < 0.05). The intra-class ICC for translations was 0.76 for manual pivot shift and 0.92 for the mechanized pivot shift test. The intra-class ICC for rotations was 0.89 for manual pivot shift and 0.82 for the mechanized pivot shift test. This study introduced a modified CPM for mechanized pivot shift testing. Although recorded translations and rotations with the mechanized pivot shift test were lower than with manual testing, the clinical advantage of mechanized pivot shift testing is a more repeatable measurement of ATT when compared to manual pivot shift testing. This setup may increase consistency of clinical grading of the pivot shift test.

Perioperative management of unicompartmental knee arthroplasty using the MAKO robotic arm system (MAKOplasty).

Unicompartmental knee arthroplasty (UKA) is a popular treatment for unicompartmental knee arthritis. Indications for UKA include mechanical axis of less than 10 degrees varus and less than 5 degrees valgus, intact anterior cruciate ligament (ACL), and absence of femorotibial subluxation. Appropriately selected patients can expect UKA to last at least 10 years. UKA failures are not common and involve technical errors that are thought to be corrected with use of newly developed robotic technology. The surgeon using this technology may be able to arrive at a set target, enhance surgical precision, and avoid outliers. Whether improved precision will result in improved long-term clinical outcome remains a subject of research. In this article, we describe the perioperative management of patients who undergo UKA whether with conventional techniques or robotic arm assistance. We also describe the distinct aspects of preoperative, intraoperative, and postoperative pain management and of intraoperative anesthesia and blood management.