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. 2009 Dec;467(12):3297-306.
doi: 10.1007/s11999-009-1052-y. Epub 2009 Aug 19.

Clinical anatomy of the quadriceps femoris and extensor apparatus of the knee

Andrew C Waligora  1 , Norman A Johanson, Bruce Elliot Hirsch
Affiliations

Clinical anatomy of the quadriceps femoris and extensor apparatus of the knee

Andrew C Waligora et al. Clin Orthop Relat Res. 2009 Dec.

Abstract

Most descriptions of the extensor mechanism of the knee do not take into account its complexity and variability. The quadriceps femoris insertion into the patella is said to be through a common tendon with a three-layered arrangement: rectus femoris (RF) most superficially, vastus medialis (VM) and lateralis (VL) in the intermediate layer, and vastus intermedius (VI) most deeply. We dissected 20 limbs from 17 cadavers to provide a more detailed description of the anterior components of the knee: the tendon, the patellar retinacula, and the patellofemoral ligaments. Only three of the 20 specimens exhibited the typically described quadriceps pattern. The remainder had bilaminar and even more complex trilaminar and tetralaminar fiber arrangements. We found an oblique head of the vastus lateralis (VLO), separated from the longitudinal head by a layer of fat or fascia, in 60% of the specimens. However, we found no distinct oblique head of the vastus medialis (VMO) in any specimen. The medial patellofemoral ligament (MPFL) was more common than the lateral (LPFL), supporting its suggested role as the principal passive medial stabilizer of the patella. Because the quadriceps muscle group plays a direct role in patellofemoral joint function, investigation into the clinical applications of its highly variable anatomy may be worthwhile with respect to joint dysfunction and failures of TKAs.

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Figures

Fig. 1A–D
Fig. 1A–D
A schematic is shown of the various patterns of the layers of the quadriceps tendon. (A) A sagittal section of the patella and its relation to the quadriceps and patellar tendons is illustrated. (B) Bilaminar, (C) trilaminar, and (D) quadrilaminar patterns of the quadriceps tendon are shown. R = Rectus femoris, L = Vastus lateralis, M = Vastus medialis, I = Vastus intermedius.
Fig. 2
Fig. 2
The approximate areas of attachment of the quadriceps tendon components onto the base and sides of the patella are superimposed on photographs of the bone. RF = Rectus femoris, VL = Vastus lateralis, VM = Vastus medialis, VI = Vastus intermedius, L = Lateral, S = Superior, M = Medial.
Fig. 3
Fig. 3
Tendon fibers from the VL run inferomedially across the patella (*) toward the medial tibial condyle. S = Superior, M = Medial.
Fig. 4
Fig. 4
Tendon fibers from the VM (arrows) run inferolaterally across the patella toward the lateral tibial condyle. A = Anterior, I = Inferior.
Fig. 5
Fig. 5
The LPFL is lifted by the hemostat. The curved arrows indicate the fascial plane separating the oblique and longitudinal heads of the VL. A = Anterior, I = Inferior.
Fig. 6
Fig. 6
This is an example of a two-layered quadriceps tendon whose superficial (S) and deep (D) layers fuse proximal to the patella. Articularis genus (lower curved arrow) and fibers from the VM (upper curved arrow) can be seen inserting into the suprapatellar bursa (*). A = Anterior, S = Superior.
Fig. 7
Fig. 7
In this three-layered quadriceps tendon, the layers remain distinct until they come together and fuse into one tendon proximal to the patella. The superficial (S), intermediate (I), and deep (D) layers are indicated. Su = Superior.
Fig. 8
Fig. 8
In this specimen with a three-layered quadriceps tendon, the layers fuse into a single tendon proximal to the patella, but a bundle of fibers (unlabeled short arrow) first passes from the VI to the intermediate layer joining the VL and VM. The superficial (S), intermediate (I), and deep (D) layers are indicated. Su = Superior.
Fig. 9
Fig. 9
The medial patellofemoral ligament (MPFL) runs between the medial femoral epicondyle and the superolateral corner of the patella (*). It is partially covered by VM, which sends a fascial expansion to the ligament. A = Anterior, S = Superior.
Fig. 10
Fig. 10
In this specimen the MPFL is a very wide band attaching to the medial femoral epicondyle anteroinferior to the adductor tubercle (+). VM = vastus medialis, A = Anterior, S = Superior.
Fig. 11
Fig. 11
The MPFL (arrow) has an extensive connection to the VM before it reaches the patella. + = Adductor tubercle, A = Anterior, S = Superior.
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