Assessment of posterior stability in total knee replacement by stress radiographs

Abstract

The aim of this study was to assess the posterior stability of two different designs of total knee replacement (TKR) with deep-dished mobile bearing (MB) implants using stress X-rays. In a prospective non-randomized consecutive study, 34 patients with primary osteoarthritis of the knee underwent TKR. In group A (17 knees), they received a MB insert with a Duracon prosthesis and in group B (18 knees), a Genesis prosthesis. In all cases the posterior cruciate ligament (PCL) was resected. All patients had pre- and post-operative kneeling X-rays and were clinically evaluated with the Knee Society Score. Measurements on the radiographs were taken by tracing a line along the posterior cortex of the tibia and then measuring the perpendicular distance to a point marked at the posterior corner of Blumensaat's line. The average follow up was 10.7 months for group A and 5.4 months for group B. No statistical difference could be found in terms of clinical results and pre- and post-operative kneeling X-rays between the two groups. In each group, all knees demonstrated a significant posterior tibial translation postoperatively compare to their pre-operative status (p<0.0001). There are advantages in resecting the PCL in TKR: mobile flexion gap, correction of fixed deformity, more flexibility to adjust the joint line. The use of a deep dished polyethylene (PE) insert provides stability and use of MB insert reduces PE wear whilst retaining congruity. Two designs of deep-dished MB inserts showed significant posterior tibial translation on stress X-rays. It remains to be determined what amount of laxity is optimal for clinical function and polyethylene longevity.

Role of high tibial osteotomy in chronic injuries of posterior cruciate ligament and posterolateral corner

“…In the lateral stress view according to the kneeling method [96], the patient knees on a bench with the knee at 90° of flexion; the bench only supports the lower legs up to the tibial tubercle. In this position a lateral X-ray is taken [96].…”

Clinically Reliable Knee Flexion Angle Measured on Stress Radiography for Quantifying Posterior Instability in Posterior Cruciate Ligament Injury

“…Although new measurement methods without a stress device are being introduced, such as the kneeling position suggested by Louisia et al 19 and supine lateral radiography as described by Kim et al, 15 stress radiography with a Telos device remains the most frequently used method for assessing PCL injuries, grading instability, and evaluating treatment outcomes owing to its reproducibility, quantifiability, and easy application in daily clinical settings. 14 , 20 However, no consensus has been reached regarding the posterior drawer force (89-150 N) 12 , 14 position that provides the optimal method to measure instability.…”

“…Several techniques to quantify posterior instability are available, including stress radiography using a stress device, kneeling position, supine lateral radiography, and arthrometry. 11 , 12 , 14 , 15 , 19 , 24 In PCL injury, stress radiography is generally accepted to be superior in quantifying posterior instability. 10 , 12 , 22 However, the reliability of this measurement method has not been well-evaluated in a larger patient population, and no clear standard method has been established.…”

Comparing the Efficacy of Kneeling Stress Radiographs and Weighted Gravity Stress Radiographs to Assess Posterior Cruciate Ligament Insufficiency

“…In a comparison study by Jung et al, 11 the Telos device, hamstring contraction, 3 kneeling view, 8,13,14 gravity view, 21,22 and axial view 15 stress radiography techniques were assessed based on PTD, time per radiograph, and patient pain. The authors concluded that the Telos method and kneeling view produced the largest PTD values.…”

“…This potential reduction in PTD from pain-related muscular activation or weight shifting may therefore inappropriately alter management decisions that are based on the results of the PCL stress radiographs. 11,18 In a comparison study by Jung et al, 11 the Telos device, hamstring contraction, 3 kneeling view, 8,13,14 gravity view, 21,22 and axial view 15 stress radiography techniques were assessed based on PTD, time per radiograph, and patient pain. The authors concluded that the Telos method and kneeling view produced the largest PTD values.…”