Evaluation of Patella Anatomy for Total Knee Arthroplasty Approaches

Abstract

Background: The patella, or kneecap, is a sesamoid bone situated deep to the fascia latae and the tendinous fibers of the rectus femoris. The medial and lateral facets of the patella articulate with the medial and lateral condyles of the femur, respectively, to form the patellofemoral component of the knee joint. When joint cartilage is destroyed due to osteoarthritis, inflammatory arthritis, post-traumatic degenerative joint disease, or osteonecrosis/joint collapse with cartilage loss, a surgical treatment called knee arthroplasty, or total knee arthroplasty (TKA), is used to rebuild the knee joint.

Objectives: The purpose of our study is to provide a detailed morphometric analysis of the human patella.

Methods: A total of 168 patellae (86 left, 82 right) were examined. Eleven parameters were determined to evaluate patella morphometry, and the bones were also evaluated with the Wiberg classification.

Result: Type I patella was observed in 13 samples (7.74%); 109 (64.88%) and 46 (27.38%) were Type II and Type III, respectively. In the statistical analysis, significant differences were found between the right and left patellae in terms of patellar thickness, vertical ridge length, and Wiberg angle (p<0.05). There were also significant differences between the Wiberg types and the medial articular width and lateral articular width (p<0.05).

Conclusion: In order to avoid potential difficulties during knee surgery, it is crucial to understand the typical morphological and morphometric properties of the patella. We believe that this study will be useful to surgeons who perform surgical approaches to the knee and to clinicians who evaluate the diseases of the region.

Keywords: anatomy; morphometry; patella; total knee replacement (tkr); wiberg classification.

Figure 1. Demonstration of measured parameters: articular surface (a), anterior surface (b), lateral view (c) of the patella

PL: patellar length; PW: patellar width; PT: patellar thickness; MAW: medial articular width; LAW: lateral articular width; ASH: articular surface height; VRL: vertical ridge length; WA: Wiberg angle; PFT: patellar facet thickness.

Figure 2. Distribution of patellae according to Wiberg types

Type I: The medial and lateral facets are equal in size; Type II: The ridge is situated slightly towards the medial border of the patella, and the medial facet is smaller than the lateral; Type III: The ridge is displaced medially to such a degree that there is no space left for the medial facet.

Figure 3. Distribution of the MAW and LAW according to Wiberg types

MAW: medial articular width; LAW: lateral articular width