Alignment Influences Wear in the Knee after Medial Unicompartmental Arthroplasty

144

140

Section: Discussionmentioning

confidence: 99%

Constitutional Varus Does Not Affect Joint Line Orientation in the Coronal Plane

Victor

Bassens

Bellemans³

et al. 2014

144

140

“…Despite the success of the procedure, the functional outcomes and survival of UKA are influenced by a variety of factors, including the underlying diagnosis, patient selection, prosthesis design, polyethylene quality, and implant alignment and fixation [1-3, 5, 7-9, 11]. Tibial and femoral component and/or limb malalignment is poorly tolerated in UKA and can jeopardize long-term survival [5,[7][8][9]14]. Swienckowski and Page reported that coronal malalignment of the tibial component beyond 3°predisposed to failure [15].…”

Section: Introductionmentioning

confidence: 99%

Robotic Arm-assisted UKA Improves Tibial Component Alignment: A Pilot Study

Lonner

John

Conditt³

2010

192

114

The alignment of the components of unicompartmental knee arthroplasty (UKA) reportedly influences outcomes and durability. A novel robotic arm technology has been developed with the expectation that it could improve the accuracy of bone preparation in UKA. During the study period, we compared the postoperative radiographic alignment of the tibial component with the preoperatively planned position in 31 knees in 31 consecutive patients undergoing UKA using robotic arm-assisted bone preparation and in 27 consecutive patients who underwent unilateral UKA using conventional manual instrumentation to determine the error of bone preparation and variance with each technique. Radiographically, the root mean square error of the posterior tibial slope was 3.1°w hen using manual techniques compared with 1.9°when using robotic arm assistance for bone preparation. In addition, the variance using manual instruments was 2.6 times greater than the robotically guided procedures. In the coronal plane, the average error was 2.7°± 2.1°more varus of the tibial component relative to the mechanical axis of the tibia using manual instruments compared with 0.2°±

“…Accuracy of bone cutting and implant positioning based on anatomic references are major requirements for avoiding implant failure in TKA and UKA [12,17,18,24,34]. However, compared with coronal and sagittal alignment of the knee, there are no data for reliable rotational alignment of a UKA.…”

Section: Discussionmentioning

confidence: 99%

“…Accuracy of implant positioning and reconstruction of the mechanical leg axis are major requirements for avoiding aseptic loosening and polyethylene wear [12,17,18,24,34]. However, compared with coronal and sagittal alignment of the knee, it is difficult to implant components in the correct rotational position in small operating fields, particularly with mini-incision surgery.…”

Section: Introductionmentioning

confidence: 99%

Is the Medial Wall of the Intercondylar Notch Useful for Tibial Rotational Reference in Unicompartmental Knee Arthroplasty?

Kawahara¹,

Matsuda²,

Okazaki³

et al. 2012

Background It is difficult to implant components in the correct rotational position in the narrow operating field in a unicompartmental knee arthroplasty. Although no rotational reference has been confirmed for unicompartmental knee arthroplasty, the AP axis of the tibia may serve as a reference for unicompartmental knee arthroplasty and TKA. However, it is difficult to identify the AP axis during unicompartmental knee arthroplasty, especially with the tibia first-cut technique. Questions/purposes We explored whether the medial wall of the intercondylar notch could be useful for the tibial rotational reference as an alternative to the AP axis in unicompartmental knee arthroplasty. Methods We scanned the knees of 24 healthy Asian patients (45 knees) at a flexion angle of 908 using open MRI, then measured the angle between the AP axis and the medial wall of the notch. We determined whether the origins of the ACL and PCL were located lateral to the line on the medial wall of the notch and whether the mediolateral dimension of the bone cut surface of the medial tibial plateau was wide enough relative to the AP dimension to use the commercially available unicompartmental knee arthroplasty tibial components when the tibia was cut parallel to the medial wall of the notch.Results At 908 flexion the medial wall of the notch was externally rotated 0.18 ± 4.48 relative to the AP axis. In all knees, the ACL and PCL were located lateral to the line on the medial wall of the notch. The mediolateral dimension of the bone cut surface was wide enough to use the commercially available tibial components. Conclusions At 908 flexion the medial wall of the intercondylar notch is almost parallel to the AP axis of the tibia at and we believe a reasonable candidate for a rotational reference of tibial placement in unicompartmental knee arthroplasty. This landmark would need to be confirmed in other populations and in patients with osteoarthritis.