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

Abstract

During revision total knee arthroplasty, the joint line is frequently malpositioned, due to the disappearance of the anatomical landmarks following previous interventions. This leads to decreased clinical outcome and increased risk of re-intervention. Many methods have been proposed to restore the joint line, but none of them has shown itself to be reliable. We describe an accurate and precise method to localize the exact position of the joint line which guarantees a better clinical knee score. The adductor tubercle (AT) is recognized to be the most reliable landmark used to localize the knee joint line (JL). The distance from the AT to the JL on antero-posterior radiographs (ATJL) and the femoral diameter (FD) on true lateral views were measured on 200 randomly selected normal knees. These measurements were tested for intra- and inter-observer differences. Then, the relationship between these two measurements was studied. A significant correlation and linear regression between FD and ATJL was found (p < 0.001), making the adductor tubercle a valid landmark to accurately position the prosthetic joint within 4 mm from the normal position. No significant difference was noted in the intra and inter-observer measurements (F test not significant). Sex was found to be an intervening variable (p ˂ 0.001). The correlation and regression between ATJL and FD had to be adjusted accordingly. Once the ATJL was determined preoperatively, the JL level is found during surgery by using a caliper that is held on the easily palpable AT. Knowing the femoral diameter, we can easily locate the joint line level surgically, using the adductor tubercle as a landmark. This method leads to better clinical outcomes and a reduced risk of re-intervention following revision total knee arthroplasty.

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

“… 3 , 4 , 9 Although subsequent studies reported the acceptable critical range as sd 5 mm, 8 , 11 more recently opinion in the literature on this subject has been changed by newer reports indicating that a deviation of more than 4 mm in the joint line proximally or distally from its normal position leads to unfavourable results. 10 - 13 , 14 - 16 Thus, it is clear that exact determination of the anatomical joint line is essential to achieve an optimal post-operative clinical outcome. We believe that the anatomical joint line can be restored within the acceptable zone of less than 5 mm proximally or distally from its neutral/original anatomical position by using this simple, and reproducible method that we have presented herein.…”

Radiographic Morphology and Method for Localization of the Adductor Tubercle on Anterior–Posterior Knee Radiographs

“…However, we expect that our technique may result in a longer joint line distance compared with other reports because most other authors designated a more distal site as the location of the AT, according to the stated methods and illustrations in their publications. 8,13,14 In future studies, we plan to measure the joint line distance in a normal population using our technique.…”

“…Most researchers did not clearly describe their method for identifying the AT. 7,8,[11][12][13][14] One study showed how the AT was localized by only drawing the indicating lines on radiographs, but there was no corresponding descriptive explanation in the text. 7 Some authors described the localization of the AT in their studies; however, in their illustrations, the ATs were seemingly not correctly labeled, as presumed AT shadows were apparently proximal to the designated sites.…”

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“…AP view were taken such a way that femoral and tibial condyles are symmetrical and head of fibula slightly overlapping the lateral tibial condyle. Lateral views were taken with femoral condylar overlap [3] . Institute's Ethical committee approval has been obtained.…”

“…4. Sagittal tibial diameter (STD): the diameter of the tibia at the level of the TT in the sagittal plane, perpendicular to the tibial shaft [3] . 5.…”