Utilizing Evolved Extramedullary Techniques for Conventional Knee Arthroplasty in Post-traumatic Knee Arthritis With Retained Hardware: A Retrospective Analysis

TL;DR

This study shows that a new extramedullary technique can safely and effectively perform knee replacements in patients with post-traumatic arthritis and retained hardware.

Contribution

A novel extramedullary method for conventional TKA in post-traumatic knee arthritis with retained hardware is introduced and validated.

Findings

Good restoration of mechanical alignment was achieved with a mean HKA angle of 180.2° post-surgery.

Clinical outcomes showed high Knee Society scores and no allogenic transfusions or implant failures.

Short-term benefits included reduced blood loss, shorter inpatient stays, and faster recovery.

Abstract

Introduction

For post-traumatic knee arthritis with retained implants, performing conventional primary total knee arthroplasty (TKA) can be challenging due to altered bony structures or mechanical obstructions. Without current computer-aided navigation, we can still perform conventional TKA by extramedullary means according to the parallelism and the reference to inherent anatomical landmarks. In this study, we aim to present a novel extramedullary method applied during conventional total knee arthroplasty (TKA) and the clinical outcomes observed in our series.

Methods

Between April 2014 and March 2021, patients with post-traumatic knee arthritis and retained hardware scheduled for TKAs at our institute were included. All the index procedures were performed with primary cemented TKA prostheses by the same surgeon. After the proximal tibial cut perpendicular to the tibial shaft, the following distal femur cut was executed according to the parallelism between these cuts. Certain interfering hardware located on the metaphyseal area, like screws or staples, were removed as needed. In addition, most of the conventional principles and techniques in traditional knee replacement were followed. Clinical outcomes, including perioperative blood loss, transfusion rate, inpatient stay, knee functional score, and radiographic evaluation, were recorded and reviewed.

Results

Within a period of eight years, there were 12 patients with a mean age of 67.8 years old enrolled. Overall, there was a good restoration of optimal mechanical alignment after surgery, and the mean hip-knee-ankle (HKA) angle was 180.2o compared to their preoperative deformity (HKA 174.0o ± 10.4o). Clinical assessments according to the Knee Society score showed good knee scores (87.1), functional scores (87.1), and motion arc (106.7o). No patient required allogenic blood transfusion or prolonged stays (range: five to eight days). In the last outpatient visit, no radiographic implant failure was found, and no surgical site-specific complications were reported after clinical follow-ups for at least two years.

Conclusions

Our results suggest that post-traumatic knee arthritis with remnant hardware can be safely and effectively treated with conversion TKAs according to the suggested extramedullary (EM) techniques in this study. With minimal removal of interfering hardware, reduced surgical trauma as well as operation time, helps to achieve short-term clinical benefits, including reduced blood loss, inpatient stay, faster recovery, and even restoration of optimal limb alignment.

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