Elsevier

The Knee

Volume 7, Issue 2, 1 April 2000, Pages 121-127
The Knee

Medial patellofemoral ligament restraint in lateral patellar translation and reconstruction

https://doi.org/10.1016/S0968-0160(00)00038-7Get rights and content

Abstract

The purpose of this investigation was to evaluate the prevention of lateral patellar displacement by the medial patellar stabilizers and the effectiveness of medial patellofemoral ligament (MPFL) reconstruction against lateral displacement. Ten fresh frozen human knee specimens were studied and anatomical observations were made using seven additional knee specimens. Lateral shift ratios were measured, using a lateral force of 10 N, after sectioning the medial retinaculum and/or the MPFL during 20–120° of knee flexion. The isolated sectioning of the MPFL greatly increased lateral displacement during 20–90°, and the isolated MPFL reconstruction prevented patellar displacement within the normal range during 20–120°.

Introduction

The medial patellar stabilizers are important in preventing the lateral displacement of the patella and controlling the patellar tracking [3], [8]. In recent years, the importance of the medial patellofemoral ligament (MPFL) among the medial patellar stabilizers has been focused biomechanically or clinically [1], [2], [4], [9], [13], [14], [15], [18], [19]. There have been a few reports on MPFL reconstruction [1], [5], [12]. In order to reconstruct the MPFL accurately, we needed to know the detailed function of the MPFL and the effectiveness of reconstruction during a wide range of knee motion. The objective of this study was to investigate at which angle of knee flexion the MPFL is functioning, and whether our MPFL reconstruction method corrects lateral patellar instability over a wide range of motion.

Section snippets

Materials and methods

In order to investigate the changes in tension of the MPFL during a full range of knee motion, and whether the MPFL alone controls the patella tracking within the femoral groove, seven fresh-frozen knees above-the-knee amputations were used. The same testing stand as the section experiment was used and a 1-kgf force was applied to the quadriceps tendon.

Next, in order to investigate the function of the MPFL and the effectiveness of reconstruction during a wide range of knee flexion, a total of

Results

Although it was difficult to detect the MPFL in some knees due to the intervention of loose soft-tissues between the medial retinaculum and MPFL, the MPFL was identified in all 17 knees. From the evaluation of the changes in the tension of the MPFL in seven fresh-frozen knees, the MPFL was slightly relaxed within the range of 15–30° of knee flexion and was taut in other flexion angles. If the 1-kgf force was not applied to the quadriceps tendon, lateral mobility of the patella increased

Discussion

In some recent biomechanical studies, the MPFL has been accepted as the primary restraint among the medial patellar stabilizers [2], [4], [9], [13]. Conlan et al. [2] reported that the MPFL had 53% of the total medial restraining force. Hautamaa et al. [9] and Desio et al. [4] reported that the MPFL contributes an average of 50% of the total medial restraint and 60% of the total restraining force, respectively. We also reported that the isolated MPFL sectioning increased lateral shift ratio

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