Accuracy of bony landmarks for restoring the natural joint line in revision knee surgery: an MRI study

Abstract

Purpose Restoring the joint line (JL) improves clinical and functional outcome in total knee arthroplasty (TKA). Therefore, anatomical landmarks to approximate the JL have been published. So far, the natural deviation of the JL 90°to the mechanical tibial axis has not been considered. Thus, we designed this study to: (1) determine the natural JL of knees in healthy persons in respect to the mechanical tibial axis, (2) validate and double-check intra-operative bony landmarks already been published in respect to the natural JL and (3) find possible correlations between distances from bony landmarks to the JL and femoral and tibial width. Methods Eighty MRI scans of knees of healthy persons were examined by two independent observers. Distances from the tip of the fibular head (FH), the medial (ME) and lateral (LE) epicondyles and the adductor tubercle (AT) to the JL within the medial and lateral compartment were measured. Further, we determined the orientation of the JL in respect to the mechanical axis of the tibia. Interobserver correlations were calculated. Differences were analyzed using Student's t test. Linear regression models were calculated to analyze correlations. Results Interobserver correlation was excellent. Mean JL deviation was 4.2°varus. Distance between the FH, ME, LE and AT to the JL within the medial compartment was 12.2, 33.9, 33.4 and 45.4 mm, respectively. Within in the lateral compartment, distances were 15.3, 31.0, 30.6 and 42.3 mm to the JL. Strong correlation was found between femoral width and distances from the AT, ME and LE to the JL. ConclusionIn TKA, the JL is usually altered due to the classic resection technique, which does not respect the natural deviation of the JL. Estimating the natural JL by adding absolute values to bony landmarks, as proposed in the literature, is not recommended. According to our data, the JL can be best estimated by adding the calculated value: 6.40+(width femur [mm] × 0.49) to the AT.

Joint line restoration during revision total knee arthroplasty: an accurate and reliable method

“…The one-way ANOVA test did not reveal a significant difference (F test not significant) in the intra and inter-observer reliability of the ATJL and FD measurements (Table 1 ). These findings are identical to Clement et al ( 2014 ) who also proved the reliability of the FD measurement, as well as Iacono et al ( 2013 ) and Maderbacher et al Maderbacher et al 2014 ) who confirmed likewise the reliability of the ATJL measurement. In addition, Romero et al ( 2010 ) had similar findings concerning distal femoral measurements.…”

Effect of Joint Line Elevation after Posterior-stabilized and Cruciate-retaining Total Knee Arthroplasty on Clinical Function and Kinematics

“…[ 5 ] Maderbacher et al . [ 14 ] and Iacono et al . [ 15 16 ] concluded that the femoral adductor tubercle was an accurate and stable anatomical landmark for measurement of knee JL position, and that its position was not affected by knee flexion or extension.…”

The medial and lateral epicondyle as a reliable landmark for intra-operative joint line determination in revision knee arthroplasty

“…The posterior medial articular distance (PMAD) and posterior lateral articular distance (PLAD) were defined as the distance between the most prominent points of the medial and lateral epicondyles and the posterior joint lines/posterior articular surfaces of the medial and lateral condyles perpendicular to the anatomical axis of the femur in the sagittal plane. The anatomical axis of the femur and the joint line were determined as previously described by Maderbacher et al 9 , 12 In brief, the femoral mechanical axis is defined as the line from the midpoint of the centre of the shaft to the midpoint of the distal femur, and the joint line defined as the line tangent to the most distal points of both the medial and the lateral femoral condylar articular surfaces. The most prominent points of the medial and lateral epicondyles and the joint lines were re-identified for each measurement ( Fig.…”

“…This issue still remains an object of interest. 9 - 11 The present study aimed to identify an accurate, reliable and easily performed standardised method for determining the correct anatomical position of the joint line intra-operatively during revision TKA. The hypothesis was that a ratio could be determined based on the distal and posterior articular distances from the epicondyles to indicate the imaginary borders of the distal femur and the level of the joint line in revision TKA, and therefore enable an accurate decision regarding the size and location of the femoral component.…”