Leah Elson

Are morbidly obese patients undergoing total hip arthroplasty at an increased risk for component malpositioning

Acetabular cup positioning is a critical factor in determining adverse clinical outcomes in THA. This evaluation was performed to determine if morbid obesity (BMI ≥35kg/m(2)) is a contributing risk factor to cup malpositioning. Two groups of patients were obtained from a local arthroplasty registry and match-controlled for gender, age, and diagnosis (n=211 morbidly obese; n=211 normal). Intraoperative data and postoperative AP pelvis and cross-table lateral radiographs were obtained for each patient. The Martell Hip Analysis Suite was used to calculate cup positioning (successful positioning defined as 30°-45° of abduction, and 5°-25° of anteversion), as well as varus-valgus alignment of the femoral stem. There was a significant correlation between morbid obesity with respect to underanteversion; using multivariate analysis, there was a trend toward a combined underanteversion/overabduction of the acetabular cup. Of all variables considered, high BMI was the most significant risk factor leading to malpositioning.

Dynamic Soft Tissue Balancing in Total Knee Arthroplasty

Achieving optimal soft tissue balance intraoperatively is a critical element for a successful outcome after total knee arthroplasty. Although advances in navigation have improved the incidence of angular outliers, spatial distance measurements do not quantify soft tissue stability or degrees of ligament tension. Revisions caused by instability, malrotation, and malalignment still constitute up to one-third of early knee revisions. The development of integrated microelectronics and sensors into the knee trials during surgery allows surgeons to evaluate and act on real-time data regarding implant position, rotation, alignment, and soft tissue balance through a full range of motion.

Precision of acetabular cup placement in robotic integrated total hip arthroplasty.

Aims The aim of this study was to assess the efficacy of stereotactic-arm assisted acetabular component placement during total hip arthroplasty (THA). Methods 120 patients underwent primary THA at 4 different medical centres. A preoperative pelvic CT protocol was used to plan socket placement followed by robotic-arm assisted acetabular preparation and cup insertion. Intraoperative cup position was recorded and postoperative placement measured using Martell suite analysis software. Results Using a 95% predictive intervals, robotic-arm cup placement was within +/-4 degrees of planned position in 95% of cases. Applying these data to the so-called safe zone, 96% of sockets were within the defined safe zone. Our data confirms that intraoperative robotic assistance improves the precision of preparation and position of the acetabular cup during total hip arthroplasty.

A novel technique using sensor-based technology to evaluate tibial tray rotation.

Rotational tibiofemoral congruency and centralized patellar tracking are critical technical factors that affect the postoperative success of total knee arthroplasty (TKA). Several techniques are used to position the femoral component, but there is no validated method for achieving the ideal rotational position of the tibial component. It has been suggested that referencing the midmedial third of the tibial tubercle intraoperatively mitigates positional outliers. This study used data collected from intraoperative sensors to quantify the variability associated with using the midmedial third of the tibial tubercle in 170 patients undergoing primary TKA. With the sensor-equipped trial insert in place, the knee was taken into extension and the location of the femoral condylar contact point on the articular surface of the tibial insert was displayed. Rotational adjustments of the tibial tray were evaluated in real time as the surgeon corrected tray malpositioning. The initial and final angles of tibial tray rotation were captured and recorded with intraoperative video feed. When referencing the tubercle, 53% of patients had asymmetric tibiofemoral congruency in extension. Of those patients, 68% had excessive internal rotation of the tibial tray relative to the femur and 32% had excessive external rotation. The average tibiofemoral incongruency deviated from a neutral position by 6° (range, 0.5°-19.2°). Data from this evaluation suggest that use of the tibial tubercle to maximize tibiofemoral congruency is highly variable and inconsistent for confirming the final rotation of the tibial tray.

A Targeted Approach to Ligament Balancing Using Kinetic Sensors

BACKGROUND Currently, soft-tissue imbalance contributes to several of the foremost reasons for revision following primary TKA, including instability, stiffness, and aseptic loosening. In order to decrease the incidence of soft-tissue imbalance, intraoperative sensors were developed to provide real-time, quantitative load data within the knee. This study examines the intraoperative data of a group of multicenter patients to determine how targeted ligament releases affect intra-articular loading, and to understand which types of releases are necessary to achieve quantified ligament balance. METHODS A group of 129 patients received sensor-assisted TKA, as part of a multicenter study. Medial and lateral loading data were collected pre-release, during any sequential releases, and post-release. All data were collected at 10°, 45°, and 90° during range of motion testing. Ligament release type, release technique type, and resultant loading were collected. RESULTS Loading across the joint decreased, overall, and became more symmetrical after releases were performed. On average, between 2 and 3 corrections were made (up to 8) in order to achieve ligament balance. The ligament release type and subsequent quantified change in loading were in agreement with historical, qualified sources. CONCLUSION Objective data from sensor output may assist surgeons in decreasing loading variability and, thereby, decreasing ligament imbalance and its associated complications.

A Systematic Literature Review of Three Modalities in Technologically Assisted TKA

In effort to reduce the revision burden of total knee arthroplasty (TKA), industry emphasis has focused on replacing manual techniques—which are subject to variability—with technological implements. Unfortunately, technological innovation often continues before adequate time for critical evaluation has passed. Therefore, the purpose of this descriptive literature review was to collect a large sample of international data and report on the clinical and economic efficacy of three major types of technologically assisted TKA: navigation, patient-specific instrumentation, and sensorized trials.

Effects of Cementing on Ligament Balance During Total Knee Arthroplasty

Complications related to joint imbalance may contribute to some of the most predominant modes of failure in total knee arthroplasty (TKA). These complications include instability, aseptic loosening, asymmetric component wear, and idiopathic pain. Fixation may represent a step that introduces unchecked variability into the procedure and may contribute to the incidence of joint imbalance-related complications. The ability to quantify in vivo loading in the medial and lateral compartments would allow for the ability to confirm balance after fixation and prior to wound closure. This retrospective study sought to capture any variability and imbalance associated with cementing technique. A total of 93 patients underwent sensor-assisted TKA. All patients were confirmed to have quantifiably balanced joints prior to cementation. After cementing and final component placement, the sensor was reinserted into the joint to capture any cementation-induced changes in loading. Imbalance was observed in 44% of patients after cementation. There was no difference in the proportion of imbalance due to surgeon experience (P=.456), cement type (P=.429), or knee system (P=.792). A majority of knees exhibited loading increase in the medial compartment. It was concluded that cementation technique contributes to a significant amount of balance-related variability at the fixation stage of the procedure. The use of the sensor in this study allowed for the correction of all instances of imbalance prior to closure. More objective methods of balance verification may be important for ensuring optimal surgical outcomes. [Orthopedics. 2017; 40(3):e455-e459.].

Arthroscopy Following Total Hip Replacement

Despite outstanding results in the majority of patients total hip replacement may be associated with a number of unplanned outcomes. Some of these are visible radiographically, such as a trochanteric wire or titanium bead within the joint or a screw backing out. However some painful conditions are not readily diagnosable by imaging. These conditions may include dense scar from an anterior hip approach tethering the iliopsoas muscle. Trunnion metallosis, when early, may also not be visualized. It is for all of the above reasons that arthroscopy, for patients with unremitting pain post-arthroplasty is valuable. It can directly visualize the joint articulation and bearing surfaces. It can identify and treat arthrofibrosis and tethering scar. It can facilitate loose body or hardware removal. It may also help, because the joint can be moved, demonstrate dynamic pathologic soft-tissue conditions. Since the procedure is performed as an outpatient it reduces surgical risk and cost.

History of Hip Arthroscopy in the USA

Anatomic constraints greatly contributed to the difficulty with arthroscopic hip access. Burman from New York, in 1931, did publish his experience on achieving intra-articular visualization in cadavers, but only in the peripheral compartment. In North America, clinical experience began in the early 1980s, following Glick and McCarthy’s development of dedicated hip distractors. Johnson, in a similar time frame, published his technique utilizing a fracture table in the supine position. Both portal access and hip-specific instrumentation have evolved significantly as procedural indications and complexity have expanded. Cartilage and labral imaging were greatly facilitated by Palmer and McCarthy’s publication on the use of gadolinium-enhanced arthro MRI scanning and oblique views. Potter’s pioneering work, at Hospital for Special Surgery, with multiplanar, thin-slice, high-resolution non-contrast MRI advanced understanding of both joint and soft-tissue pathology. Dgemric, initiated at Boston Children’s Hospital, furthered our understanding of early stages of cartilage wear. All of these developments, in concert with the work of international colleagues, have facilitated procedural advancements in the central and peripheral hip compartments and now to the extra-articular tissues.