CLINICAL FINDINGS USING THE VERASENSE KNEE SYSTEM THE INTELLIGENT CHOICE FOR FLEXION STABILITY

Transcription

1 CLINICAL FINDINGS USING THE VERASENSE KNEE SYSTEM THE INTELLIGENT CHOICE FOR FLEXION STABILITY

2 TIGHT PCL Unfavorable Clinical Outcomes of an Excessively Tight PCL A tight PCL can result in excessive femoral rollback and tibial lift-off. This may lead to posterior polyethylene degradation, pain in flexion, limited range of motion, and instability. VERASENSE ENSURES AN APPROPRIATE PCL RELEASE Patient exhibits excessive medial roll-back indicating a tight posterior cruciate ligament. Release of the PCL is performed via a pie-crusting technique, using a 19-gauge needle. Constrained excursion is observed during a posterior drawer test, indicating tension in the PCL. Symmetrical translation and appropriate laxity is observed during a final posterior drawer test. The PCL is appropriately tensioned with symmetrical rollback resulting in a favorable outcome.

3 PCL LAXITY Complications Associated with Excessive PCL Laxity An excessively lax PCL will cause flexion instability, exhibited by post-operative knee pain, swelling, and unfavorable clinical outcomes 10-20% of TKA revisions are due to instability.* VERASENSE GUIDES JOINT STABILIZATION An intraoperative posterior drawer test shows extensive femoral excursion across the bearing surface using the VERASENSE tracking option. With the addition of a thicker tibial insert, the femoral excursion is minimized and the knee joint shows stability during the posterior drawer test. * Rodriguez-Merchan. Instability following Total Knee Arthroplasty. HHSJ 2011

4 LOAD IMBALANCE: BONY ADJUSTMENT Patient exhibits mediolateral imbalance, with medial loading in excess of 50 lbs. Surgeon adds 1 of varus to the tibial plateau. Femoral contact point location is symmetrical, and the mediolateral loading is in balance. VERASENSE INDICATES TIBIAL SLOPE BONY CORRECTION Patient exhibits excessive femoral rollback and excessive loading on the medial and lateral compartments due to tension in the PCL Surgeon is adding 2 of posterior slope to increase the flexion gap. With an improved flexion gap, favorable symmetrical rollback and optimal (< 15lb. difference) intercompartmental loads were achieved. Drawer test is applied and inter-compartmental loads depict a stable endpoint.

5 LOAD IMBALANCE: SOFT-TISSUE ADJUSTMENT Clinical Consequences Associated with Imbalanced Collateral Ligamenture A well aligned knee with imbalanced intercompartmental loading, due to excessive ligament tension in either compartment, can result in an uneven distribution of kinetic joint forces across the bearing surface. This may lead to accelerated wear/degradation of the tibial insert and, ultimately, implant failure. VERASENSE ENABLES QUANTIFIABLE AND REPRODUCIBLE LIGAMENTURE BALANCE Patient exhibits excessive lateral tension in extension (displaying 0 lbs. medially; 80 lbs. laterally) Surgeon performs a posterior lateral release (arcuate complex) using an #11 blade. After sufficient release of the ligament, intercompartmental load balance was achieved.

6 MALROTATION Complications of Tibiofemoral Incongruency TKA Malrotation contributes to poor knee kinematics, unfavorable patellofemoral tracking, and is a common cause of undiagnosed postoperative pain. These complications may lead to an increased risk of early revision, and patient dissatisfaction. Generally, the mid/medial third of the tibial tubercle serves as an anatomical reference point for tibial tray rotation. In a study*, conducted by an experienced, high-volume TKA surgeon, 145 patients were evaluated to assess rotational accuracy of using the medial-third of the tibial tubercle. 54% of patients exhibited asymmetrical tibiofemoral contact in extension (70% exhibited internal tray rotation; 30% of cases exhibited external tray rotation). VERASENSE PROVIDES VISUAL VALIDATION OF CORRECTION DURING MALROTATION After tibial tray alignment to the tibial tubercle, femoral contact points exhibit external rotation with a 15 lb. intercompartmental difference. A correction through a 20.6 arc, internally, was needed to correct malrotation originally based on position of the tibial tubercle. Optimal inter-compartmental balance was achieved with appropriate tibial femoral rotation prior to any soft tissue release. * Roche M. Variability of Tray Rotation: How accurate are our most reliable methods? Rotational verification using intraoperative sensors. ISTA: Podium, OrthoSensor, Inc Griffin Road, Suite A-310 Dania Beach, FL USA Tel ORTHO ( ) Fax XXX-XX-0000 Rev 0