Daniel Kendoff

Transtibial versus anteromedial portal reaming in anterior cruciate ligament reconstruction: an anatomic and biomechanical evaluation of surgical technique.

PURPOSE The purpose of this study was to objectively evaluate the anatomic and biomechanical outcomes of anterior cruciate ligament (ACL) reconstruction with transtibial versus anteromedial portal drilling of the femoral tunnel. METHODS Ten human cadaveric knees (5 matched pairs) without ligament injury or pre-existing arthritis underwent ACL reconstruction by either a transtibial or anteromedial portal technique. A medial arthrotomy was created in all cases before reconstruction to determine the center of the native ACL tibial and femoral footprints. A 10-mm tibial tunnel directed toward the center of the tibial footprint was prepared in an identical fashion, starting at the anterior border of the medial collateral ligament in all cases. For transtibial femoral socket preparation (n = 5), a guidewire was placed as close to the center of the femoral footprint as possible. With anteromedial portal reconstruction (n = 5), the guidewire was positioned centrally in the femoral footprint and the tunnel drilled through the medial portal in hyperflexion. An identical graft was fixed and tensioned, and knee stability was assessed with the following standardized examinations: (1) anterior drawer, (2) Lachman, (3) maximal internal rotation at 30°, (4) manual pivot shift, and (5) instrumented pivot shift. Distance from the femoral guidewire to the center of the femoral footprint and dimensions of the tibial tunnel intra-articular aperture were measured for all specimens. Statistical analysis was completed with a repeated-measures analysis of variance and Tukey multiple comparisons test with P ≤ .05 defined as significant. RESULTS The anteromedial portal ACL reconstruction controlled tibial translation significantly more than the transtibial reconstruction with anterior drawer, Lachman, and pivot-shift examinations of knee stability (P ≤ .05). Anteromedial portal ACL reconstruction restored the Lachman and anterior drawer examinations to those of the intact condition and constrained translation with the manual and instrumented pivot-shift examinations more than the native ACL (P ≤ .05). Despite optimal guidewire positioning, the transtibial technique resulted in a mean position 1.94 mm anterior and 3.26 mm superior to the center of the femoral footprint. The guidewire was positioned at the center of the femoral footprint through the anteromedial portal in all cases. The tibial tunnel intra-articular aperture was 38% larger in the anteroposterior dimension with the transtibial versus anteromedial portal technique (mean, 14.9 mm v 10.8 mm; P ≤ .05). CONCLUSIONS The anteromedial portal drilling technique allows for accurate positioning of the femoral socket in the center of the native footprint, resulting in secondary improvement in time-zero control of tibial translation with Lachman and pivot-shift testing compared with conventional transtibial ACL reconstruction. This technique respects the native ACL anatomy but cannot restore it with a single-bundle ACL reconstruction. Eccentric, posterolateral positioning of the guidewire in the tibial tunnel with the transtibial technique results in iatrogenic re-reaming of the tibial tunnel and significant intra-articular aperture expansion. CLINICAL RELEVANCE Anteromedial portal drilling of the femoral socket may allow for improved restoration of anatomy and stability with ACL reconstruction compared with conventional transtibial drilling techniques.

Robot-Assisted Unicompartmental Knee Arthroplasty

The outcomes of unicompartmental knee arthroplasties (UKAs) have demonstrated inconsistent long-term survival. We report the first clinical series of UKA using a semiactive robotic system for the implantation of an inlay unicondylar knee arthroplasty. Ten patients were selected for this study. Preoperative mechanical leg alignment values ranged from 0.3 degrees varus to 9.8 degrees varus. A haptic guidance system was used; a detailed description is given in the manuscript. The setup time for the robot was 41 minutes; intraoperative registration process, 7.5 minutes (6-13 minutes); skin incision, 8 cm; robot-assisted burring, 34.8 minutes (18-50 minutes); mean tourniquet time, 87.4 minutes (68-113 minutes); and overall operation time, 132 minutes (118-152 minutes). The planned and intraoperative tibiofemoral angle was within 1 degrees. The postoperative long leg axis radiographs were within 1.6 degrees. Haptic guidance in combination with a navigation module allows for precise planning and execution of both inlay components in UKA.

The Pivot-Shift Phenomenon During Computer-Assisted Anterior Cruciate Ligament Reconstruction

Anterior cruciate ligament reconstruction was one of the first procedures in which computer-assisted techniques were used in orthopaedic surgery. However, the use of navigation for tunnel placement in anterior cruciate ligament surgery remains problematic, as the optimal position for placement of the tunnels is debatable. The technical specification of tunnel position is clinically relevant, but the targets and tolerances for this technical specification are poorly understood. The inability to reliably quantify knee kinematics and stability before, during, or after anterior cruciate ligament reconstruction remains a problem. A navigated examination to assess knee stability could potentially close the computer-assisted surgery treatment loop by providing quantitative feedback about various reconstruction techniques. Recent iterations of navigated examinations for the assessment of stability include even complex pathologic movements, such as those detected with the pivot-shift examination. In this paper, we review conventional stability measurements of the knee and compare them with navigated techniques, with a focus on the navigated pivot-shift examination. In summary, direct intraoperative measurements and quantifications of knee stability, including the pivot-shift phenomenon, are now possible with the use of navigation. Consequently, more reproducible and clinically meaningful quantification of the pivot-shift phenomenon may allow for more accurate evaluation of various anterior cruciate ligament reconstruction techniques in the future.

Intraoperative 3D imaging in calcaneal fracture care-clinical implications and decision making.

BACKGROUND In operative calcaneal fracture care malposition of screws and joint line incongruity frequently remain unrecognized using fluoroscopy intraoperatively, and are frequently only recognized on postoperative computed tomography scans. The purpose of this study was to analyze the feasibility and utility of a new C-arm-based three-dimensional imaging technology for calcaneal trauma care. METHODS The C-arm-based three- dimensional imaging device (ISO-C-3D) was used in 32 patients during a 2-year period. Patients were indicated for open reduction and internal fixation using standard techniques and fluoroscopy. After reduction and implant placement was determined to be correct, the ISO-C-3D procedure was performed. The time for setup and use, and the consequences were recorded. An assessment was obtained from the surgeon regarding the feasibility and the adequacy and quality of the data provided, using a Visual Analog Scale. RESULTS The average total time required for ISO-C-3D use was 610 seconds. The information obtained from the scan led the surgeon to alter the reduction or screw placement during the procedure in 41% of the patients. Surgeons rating according to a Visual Analog Scale: feasibility 9.5, accuracy and quality 9.2, clinical benefit 8.2. CONCLUSION Intraoperative three- dimensional visualization with the ISO-C-3D provides important information in the operative treatment of calcaneal fractures which cannot always be obtained from plain films or standard fluoroscopy alone. The use of the device adds minimal time to the overall procedure, and was found to be extremely useful in evaluating reduction and implant position intraoperatively in calcaneal fractures.

Intraoperative 3D imaging: value and consequences in 248 cases.

BACKGROUND Intraoperative visualization of articular surfaces is technically demanding, and standard two-dimensional fluoroscopic imaging frequently does not provide adequate detail of nonplanar joints. New imaging modalities allow for intraoperative 3D visualization, which are useful in articular fractures. Purpose of this study was to evaluate the utility of 3D imaging in articular fracture reconstruction. METHODS In a prospective cohort study, we evaluated 248 consecutive patients with intra-articular fractures. After fracture fixation using standard fluoroscopy, 3D imaging was performed intraoperatively using the Iso-C3D system for all patients. Surgeons filled out questionnaires regarding the utility and perceived accuracy of the 3D system. Postoperative CT scans were performed on approximately half of the patients. Main outcome measurements were based on the surgeons decision to immediately revise the articular reduction or implant position. The setup time for the system was recorded. For patients with postoperative CT scans, articular surface gaps of 2 mm or intra-articular hardware placement was again evaluated. RESULTS In 19% of all cases, intraoperative image analysis resulted in immediate adjustment of the reduction or hardware exchange. These revisions were based on Iso-C3D views of the articular surface that were not visible using fluoroscopy. Of the 129 postoperative CT scans, five cases revealed a technical error of the joint reconstruction, and a secondary revision procedure was performed. CONCLUSION In conclusion, the Iso-C3D was a valuable intraoperative tool, providing additional information about the articular surface compared with conventional fluoroscopy in a variety of anatomic regions.

Navigated intraoperative analysis of lower limb alignment

Introduction: Accurate intraoperative assessment of lower limb alignment is crucial for the treatment of long bone fractures, implantation of knee arthroplasties and correction of deformities. During orthopaedic surgery, exact real time control of the mechanical axis is strongly desirable. The aim of this study was to compare conventional intraoperative analysis of the mechanical axis by the cable method with continuous, 3-dimensional imaging with a navigation system. Materials and methods: Twenty legs of fresh human cadaver were randomly assigned to conventional analysis with the cable method (n=10) or navigated analysis with a fluoroscopy based navigation system (n=10). The intersection of the mechanical axis with the tibia plateau was presented as percentage of the tibia plateau (beginning with 0% at the medial border and ending with 100% laterally). CT-scans were performed for all legs and the CT-values of the mechanical axis were compared to the measurements after cable method and navigation. Furthermore, the radiation time and dose area product of both groups for single analysis of the mechanical axis was compared. Results: Conventional evaluation of the mechanical axis by the cable method showed 6.0±3.1% difference compared to the analysis by CT. In the navigated group the difference was 2.6±1.8% (P=0.008). Radiation time and dose area product were highly significantly lower after conventional measurement. Conclusions: Navigated intraoperative evaluation of the mechanical axis offers increased accuracy compared to conventional intraoperative analysis. Furthermore, navigation provides continuous control not only of the mechanical axis, but also of the sagittal and transverse plane. Using the cable method, radiation exposure depends on the number of measurements and is lower compared to the navigation system for single intraoperative analysis of the mechanical axis, but may be higher in case of repeated intraoperative measurements.

Organism profile in periprosthetic joint infection: pathogens differ at two arthroplasty infection referral centers in Europe and in the United States.

Infecting microorganism is a strong predictor of treatment success for periprosthetic joint infection (PJI). The purpose of this study was to compare the infecting pathogens causing PJI at two large infection referral centers in the United States and in Europe. In this study, 898 consecutive cases of PJI were identified at the HELIOS ENDO-Klinik Hamburg in Europe and 772 cases were identified at the Rothman Institute in the United States. The incidence of organisms at the HELIOS ENDO-Klinik Hamburg versus the Rothman Institute was: coagulase-negative Staphylococcus (39.3 vs. 20.2%), S. aureus (13.0 vs. 31.0%), Streptococcus (6.5 vs. 5.8%), Enterococcus (7.0 vs. 3.9%), anaerobic (9.0 vs. 0.9%), fungal (0.3 vs. 2.3%), mycobacterial (0 vs. 0.6%), polymicrobial (3.4 vs. 7.4%), culture negative (16.1 vs. 15.8%), and other organisms (0.9 vs. 5.4%). The percentage of methicillin-resistant S. aureus was significantly higher at the American center than at the European center (48.1 vs. 12.8%; p < 0.0001). Our findings show higher virulence and resistance organisms are more prevalent at a referral center in the United States compared with one in Europe.

International Consensus on Periprosthetic Joint Infection: Description of the Consensus Process

William Cats-Baril PhD, Thorsten Gehrke MD,Katherine Huff BA, Daniel Kendoff MD,Mitchell Maltenfort PhD, Javad Parvizi MD, FRCSBackgroundPeriprosthetic joint infection (PJI),with all its disastrous consequences,continues to pose a challenge to theorthopaedic community. Practicingorthopaedic surgeons have investedgreat efforts to implement strategiesthat may minimize surgical site infec-tion (SSI). While new discoveries inorthopaedic research allow us toanswer more questions each year onthe basis of high-level evidence, thereremain numerous topics—includingmany important ones—for which theevidence is limited, contradictory, orabsent. For these clinical issues, itsometimes is helpful to know whethergeneral consensus on diagnosis ortreatment exists among individualswho specialize in these areas.Toward that end, we convened ameeting of an international panel ofexperts during 2 days (July 31 andAugust 1, 2013) in Philadelphia, PA,USA. The meeting was the penulti-mate step of a 10-month-long processto generate a set of best practices formanagement of PJI through engage-ment of experts in the field. More than300 experts from various disciplinesincluding orthopaedic surgery, infec-tious disease, musculoskeletalpathology, microbiology, anesthesiol-ogy, dermatology, nuclear medicine,rheumatology, musculoskeletal radiol-ogy, veterinary surgery, and pharmacy,as well as numerous scientists withinterest in orthopaedic infectionsattended. Delegates from 52 countriescovering all major regions of the globeparticipated, representing 160 medicalinstitutions and research centers, hav-ing memberships in more than 100medical societies and boards, andsharing a collective experience ofmany thousands of cases. The panelundertook this consensus effort to helpthe global medical communityimprove the efficacy, lower the com-plication rates, and move towardadoption of standardized measures andtechniques for management of PJI.As mentioned, the lack of evidencefor many aspects of clinical practice

Perspectives on computer-assisted orthopaedic surgery: movement toward quantitative orthopaedic surgery.

The fundamental goal of computer-assisted surgery is to make orthopaedic surgery patient-specific, minimally invasive, and quantitative. The components of computer-assisted surgery include preoperative imaging and planning, intraoperative execution, and postoperative evaluation. Ideally, these components are integrated such that sophisticated diagnostic technologies are used to create a patient-specific surgical plan. This plan is then programmed into a computer-assisted intraoperative system so that it can be precisely executed. Finally, the patient outcome is tracked longitudinally in a quantitative fashion. Computer-assisted surgery relies on the use of quantitative data rather than surgeon feel and intuition to facilitate clinical decision-making. As surgeons rely more on quantitative feedback, they must establish appropriate specifications for various operations. These specifications should be clinically relevant and must have known targets and tolerances. This overview provides examples of quantitative surgery as applied in navigated total knee replacement and anterior cruciate ligament reconstruction and in the more recent indication of robotic unicondylar knee replacement. Computer-assisted surgery represents a set of tools that facilitate quantitative surgery. To effectively use these tools, however, one must identify technical specifications that are clinically relevant for the various procedures; these specifications must be associated with known target values and tolerances and must have the capability of being reliably measured by computer-assisted surgery tools. Clinical and basic-science research is necessary to better define technical specifications for navigated procedures.

The Phosphatidylinositol 3-Kinase Signaling Pathway Exerts Protective Effects during Sepsis by Controlling C5a-Mediated Activation of Innate Immune Functions

The PI3K/Akt signaling pathway has been recently suggested to have controversial functions in models of acute and chronic inflammation. Our group and others have reported previously that the complement split product C5a alters neutrophil innate immunity and cell signaling during the onset of sepsis and is involved in PI3K activation. We report in this study that in vivo inhibition of the PI3K pathway resulted in increased mortality in septic mice accompanied by strongly elevated serum levels of TNF-α, IL-6, MCP-1, and IL-10 during sepsis as well as decreased oxidative burst activity in blood phagocytes. PI3K inhibition in vitro resulted in significant increases in TLR-4-mediated generation of various proinflammatory cytokines in neutrophils, whereas the opposite effect was observed in PBMC. Oxidative burst and phagocytosis activity was significantly attenuated in both neutrophils and monocytes when PI3K activation was blocked. In addition, PI3K inhibition resulted in strongly elevated TLR-4-mediated generation of IL-1β and IL-8 in neutrophils when these cells were costimulated with C5a. C5a-induced priming effects on neutrophil and monocyte oxidative burst activity as well as C5a-induced phagocytosis in neutrophils were strongly reduced when PI3K activation was blocked. Our data suggest that the PI3K/Akt signaling pathway controls various C5a-mediated effects on neutrophil and monocyte innate immunity and exerts an overall protective effect during experimental sepsis.