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Popliteomeniscal Fascicles: Anatomic Considerations Using MR Arthrography in Cadavers

¹ Department of Radiology, Veterans Affairs Healthcare System, San Diego, CA.
² Department of Radiology, Westmead Hospital, Darcy Rd., Westmead, Sydney, New South Wales, Australia 2145.

Received May 29, 2007; accepted after revision July 10, 2007.

 
Address correspondence to A. J. Peduto.

Abstract

Top Abstract Introduction Materials and Methods Results discussion References

 
OBJECTIVE. This study was performed to examine the normal MR arthrographic anatomy of the popliteomeniscal fascicles with specific reference to the number of popliteomeniscal fascicles, thickness and course of the fascicles, and presence of other posterior attachments from the medial aponeurosis of the popliteus musculotendinous region.

MATERIALS AND METHODS. Multiplanar 1.5-T MR arthrography of 10 cadaveric knees was performed using a quadrature knee coil. Specimens were frozen and sectioned in the sagittal (n = 4), axial (n = 3), and coronal (n = 3) planes. MR images and anatomic specimens were correlated by two musculoskeletal radiologists.

RESULTS. Three popliteomeniscal fascicles were identified on MR arthrography: anteroinferior and posterosuperior fascicles in all 10 knees and posteroinferior fascicles in four of the knees. The posterosuperior popliteomeniscal fascicle was uniform in thickness, and the anteroinferior popliteomeniscal fascicle was variable in thickness. The anteroinferior popliteomeniscal fascicle formed a conjoined fibular attachment with the popliteofibular ligament. A medial aponeurotic extension from the popliteus musculotendinous region gave rise to the posteroinferior popliteomeniscal fascicle, which extended upward and attached to the inferomedial aspect of the posterior horn of the lateral meniscus. Additional attachments from the medial aponeurosis of the popliteus musculotendinous region to the posterior cruciate ligament, posterior capsule, oblique popliteal ligament, and posterior meniscofemoral ligament of Wrisberg were seen.

CONCLUSION. Three popliteomeniscal fascicles were identified on MR arthrographic images. The popliteus muscle–tendon unit forms robust attachments in the superior, inferior, medial, and lateral oblique aspects, highlighting its importance in posterolateral stability of the knee.

Keywords: anatomy • fascicles • knee • MRI • popliteomeniscal

Introduction

Top Abstract Introduction Materials and Methods Results discussion References

 
Better understanding of the clinical significance of injuries to the posterolateral corner of the knee has led to an increasing focus on clinical evaluation, treatment, and MRI of this region. Unrecognized injuries to the posterolateral corner have been cited as an important factor in postsurgical failure after cruciate ligament reconstruction and in chronic instability and degenerative changes after knee trauma [1, 2]. Within the posterolateral corner of the knee, the functional and structural relations among the lateral meniscus, popliteus muscle and tendon attachments, and the popliteomeniscal fascicles have received considerable emphasis [3–7].

The proximal intraarticular insertion of the popliteus tendon is situated within a shallow concavity in the lateral aspect of the femur designated the popliteal sulcus. The tendon descends in an inferoposterior helicoid manner to the posterolateral corner of the knee. As it passes the posterior horn of the lateral meniscus, the popliteus tendon becomes extraarticular. The popliteomeniscal fascicles are posterolateral meniscocapsular extensions that blend inferiorly into the popliteus musculotendinous region and allow the tendon to pass from an intraarticular to an extraarticular compartment while maintaining the compartmental integrity of the knee joint. The popliteomeniscal fascicles are considered functionally important stabilizers of the lateral meniscus, working in conjunction with the popliteus musculotendinous unit to prevent excessive lateral meniscal movement and possible entrapment [8–10]. Injuries to the popliteomeniscal fascicles are commonly underrecognized both clinically and on imaging studies and are reported [3, 9] to occur in association with acute anterior cruciate ligament tears in as many as 25% of patients. Isolated tears of the popliteomeniscal fascicles can be symptomatic and manifest as localized posterolateral pain and locking of the knee joint [8, 10, 11]. Some authors [11] have referred to this disorder as hypermobile lateral meniscus and describe specific clinical examination techniques that can help in the diagnosis.

View larger version (49K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1 —Drawing shows superolateral view of posterolateral corner of knee with femur and superficial fibular attachments removed. Arrangement between popliteus muscle (8) and tendon (9) (cut proximally and reflected) and anteroinferior (11) and posterosuperior (10) popliteomeniscal fascicles is apparent. Inferolateral portion of anteroinferior popliteomeniscal fascicle (11) forms common fibular styloid attachment with anterior arm of popliteofibular ligament (6). 1 = anterior cruciate ligament, 2 = posterior cruciate ligament, 3 = lateral meniscus, 4 = anterior meniscofemoral ligament of Humphry, 5 = posterior meniscofemoral ligament of Wrisberg, 7 = posterior arm of popliteofibular ligament, 12 = fibula. (Reprinted with permission from Stäubli HU, Birrer S. The popliteus tendon and its fascicles at the popliteal hiatus: gross anatomy and functional arthroscopic evaluation with and without anterior cruciate ligament deficiency. Arthroscopy 1990; 6:209–220 [3])

The presence of a third popliteomeniscal fascicle, known as the posteroinferior popliteomeniscal fascicle, is controversial. This fascicle is reported to be located medial to the popliteal hiatus [11, 14–16]. Last [17] in 1950 described a broad and robust aponeurotic extension from the medial aspect of the musculotendinous region of the popliteus muscle that had a prominent attachment to the inferior margin of the posterior horn of the lateral meniscus. Terry and LaPrade [15] and Ullrich et al. [16] also described the medial aponeurotic extension and designated the attachment to the inferior margin of the posterior horn of the lateral meniscus the posteroinferior popliteomeniscal fascicle. This fascicle passes upward from the medial aponeurosis of the popliteus muscle and inserts on the inferior margin of the posterior horn of the lateral meniscus near the origin of the posterior meniscofemoral ligament of Wrisberg. Feipel et al. [14] found the posteroinferior popliteomeniscal fascicle present in 17% of 42 dissections of embalmed knee specimens. Most other reports of the posteroinferior popliteomeniscal fascicle do not state its frequency.

The medial aponeurosis of the popliteus musculotendinous region has been reported to have additional medial attachments to the inferolateral aspect of the posterior cruciate ligament, the posterior capsule, and an infero lateral connection with the oblique popliteal ligament [14, 16]. A variant of the posterior meniscofemoral ligament of Wrisberg has been reported in which the origin is the medial aponeurosis of the popliteus musculotendinous region rather than the posterior horn of the lateral meniscus [14].

This study was performed to examine the normal MR arthrographic imaging anatomy of the popliteomeniscal fascicles with specific reference to the number of popliteomeniscal fascicles, the thickness and course of the fascicles, and the presence of other posterior attachments from the medial aponeurosis of the popliteus musculotendinous region.

Materials and Methods

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After institutional review board approval was obtained, 10 fresh unembalmed frozen cadaveric knee specimens were obtained from the department of anatomy donor program at our institution. Specimens were from five men and five women whose average age at death was 85 years (range, 73–93 years).

MR Arthrography
Before MRI, specimens were allowed to thaw to room temperature for 24 hours, after which arthrography was performed under fluoroscopic guidance. Approximately 55–60 mL of a solution containing 1 mL of gadopentetate dimeglumine (Magnevist, Bayer Schering Pharma) diluted in 250 mL of equal parts saline solution and iohexol (Omnipaque 350, GE Healthcare) was injected into each knee joint via a lateral suprapatellar approach with an 18-gauge needle. T1-weighted spin-echo imaging was performed on a 1.5-T MRI system (Signa LX Horizon, software version 8.3, GE Healthcare) with a quadrature knee coil in the orthogonal sagittal, axial, and coronal planes. The following MRI parameters were used: TR/TE, 900/22; bandwidth, 16 kHz; matrix size, 512 x 256; field of view, 12 x 12 cm; slice thickness, 2.5-mm; interslice gap, 0.5 mm; single acquisition; imaging time, approximately 5 minutes for each sequence.

Specimen Sectioning and Photography
After MRI, the knee specimens were placed in a freezer (Forma Bio-Freezer, Forma Scientific) and deep frozen to –40°C. The frozen knee specimens were sectioned with a band saw into 3-mm slices in the sagittal (n = 4), axial (n = 3), and coronal (n = 3) planes. After debris was rinsed from the surface of the specimens, the sections were thawed, floodlit, and photographed with a digital camera (Coolpix 990, Nikon).

Image Interpretation
MR arthrographic images and specimen photographs were simultaneously reviewed by two musculoskeletal radiologists working in consensus. Identification and location of the anteroinferior, posterosuperior, and postero inferior popliteomeniscal fascicles and the medial aponeurosis with its medial attachments were based on gross anatomic descriptions obtained from the literature [3, 12, 14–16]. The number of popliteomeniscal fascicles visualized and their location on MR arthrographic images were recorded for each specimen. The reviewers inspected MR arthrographic images obtained through the popliteal hiatus, with the anteroinferior popliteomeniscal fascicle originating from the lateral surface of the body of the lateral meniscus and forming the floor and lateral wall of the hiatus, and the posterosuperior popliteomeniscal fascicle originating from the superior edge of the posterior horn of the lateral meniscus and forming the roof and medial wall of the hiatus. MR arthrographic images obtained medial to the popliteal hiatus were inspected for the presence of a medial aponeurotic extension from the musculotendinous junction of the popliteus muscle, which has been reported [15–17] to send an attachment to the inferior edge of the posterior horn of the lateral meniscus. This attachment is designated the posteroinferior popliteomeniscal fascicle and is immediately beneath the origin of the meniscofemoral ligament of Wrisberg.

View larger version (108K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A —Anteroinferior popliteomeniscal fascicle and popliteofibular ligament of cadaver specimens. A and B are matching MRI and anatomic sections from one cadaver; C and D are matching MRI and anatomic sections from another cadaver. Sagittal T1-weighted MR arthrographic images with corresponding cadaveric sections show anteroinferior popliteomeniscal fascicle extending in posteroinferior course from lateral aspect of lateral meniscus (LM) and to blend with popliteus tendon. Conjoined attachment of anteroinferior popliteomeniscal fascicle and popliteofibular ligament (asterisk) at styloid process of fibula (f) is evident. Variable appearance of anteroinferior popliteomeniscal fascicle (arrows) is thin and membrane-like in A and B and thick in C and D. POP = popliteus tendon.

View larger version (112K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B —Anteroinferior popliteomeniscal fascicle and popliteofibular ligament of cadaver specimens. A and B are matching MRI and anatomic sections from one cadaver; C and D are matching MRI and anatomic sections from another cadaver. Sagittal T1-weighted MR arthrographic images with corresponding cadaveric sections show anteroinferior popliteomeniscal fascicle extending in posteroinferior course from lateral aspect of lateral meniscus (LM) and to blend with popliteus tendon. Conjoined attachment of anteroinferior popliteomeniscal fascicle and popliteofibular ligament (asterisk) at styloid process of fibula (f) is evident. Variable appearance of anteroinferior popliteomeniscal fascicle (arrows) is thin and membrane-like in A and B and thick in C and D. POP = popliteus tendon.

View larger version (109K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2C —Anteroinferior popliteomeniscal fascicle and popliteofibular ligament of cadaver specimens. A and B are matching MRI and anatomic sections from one cadaver; C and D are matching MRI and anatomic sections from another cadaver. Sagittal T1-weighted MR arthrographic images with corresponding cadaveric sections show anteroinferior popliteomeniscal fascicle extending in posteroinferior course from lateral aspect of lateral meniscus (LM) and to blend with popliteus tendon. Conjoined attachment of anteroinferior popliteomeniscal fascicle and popliteofibular ligament (asterisk) at styloid process of fibula (f) is evident. Variable appearance of anteroinferior popliteomeniscal fascicle (arrows) is thin and membrane-like in A and B and thick in C and D. POP = popliteus tendon.

View larger version (114K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2D —Anteroinferior popliteomeniscal fascicle and popliteofibular ligament of cadaver specimens. A and B are matching MRI and anatomic sections from one cadaver; C and D are matching MRI and anatomic sections from another cadaver. Sagittal T1-weighted MR arthrographic images with corresponding cadaveric sections show anteroinferior popliteomeniscal fascicle extending in posteroinferior course from lateral aspect of lateral meniscus (LM) and to blend with popliteus tendon. Conjoined attachment of anteroinferior popliteomeniscal fascicle and popliteofibular ligament (asterisk) at styloid process of fibula (f) is evident. Variable appearance of anteroinferior popliteomeniscal fascicle (arrows) is thin and membrane-like in A and B and thick in C and D. POP = popliteus tendon.

Results

Top Abstract Introduction Materials and Methods Results discussion References

 
The anteroinferior and posterosuperior popliteomeniscal fascicles were identified with MR arthrography in all 10 specimens. Together the anteroinferior and posterosuperior popliteomeniscal fascicles formed a meniscocapsular sheath enveloping the popliteal tendon as it passed through the popliteal hiatus and became extraarticular in location (Fig. 1).

The anteroinferior popliteomeniscal fascicle (Fig. 2A, 2B, 2C, 2D) extended in an inferoposterior direction from its attachment at the lateral aspect of the body of the lateral meniscus and formed the lateral wall and floor of the popliteal hiatus. The thickness of the anteroinferior popliteomeniscal fascicle was variable. In five of 10 specimens, this fascicle was categorized as thick, in three as intermediate, and in two as thin. The anteroinferior popliteomeniscal fascicle curved in the inferior direction adjacent to the posteromedial aspect of the fibular styloid process and blended with the popliteofibular ligament to form a conjoined fibular attachment, which was found in eight of 10 specimens (Fig. 2A, 2B, 2C, 2D). In the more medial aspect the anteroinferior popliteomeniscal fascicle formed the floor of the popliteal hiatus and fused with the deep musculotendinous portion of the popliteus complex. The popliteofibular ligament was seen on MR arthro graphic images of nine of 10 specimens and had a robust attachment to the posteromedial aspect of the fibular styloid process (Fig. 2A, 2B, 2C, 2D). Only a single attachment site of the popliteofibular ligament was discernible.

The posterosuperior popliteomeniscal fascicle was in a medial position in relation to the popliteus tendon at the level of the popliteal hiatus and extended in a posterior direction from the posterosuperior corner of the posterior horn of the lateral meniscus (Fig. 3A, 3B, 3C, 3D, 3E, 3F, 3G) to the posterior joint capsule immediately above the diverging popliteus tendon. In this region the popliteus tendon widened and formed a broad aponeurotic attachment with the posterior capsule, anchoring the posterior horn of the lateral meniscus to the popliteus muscle via the posterosuperior popliteomeniscal fascicle and capsule. The posterosuperior popliteomeniscal fascicle was uniform in thickness in all 10 of the specimens and was categorized as thick.

View larger version (120K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3A —Popliteomeniscal fascicular attachments of cadaver specimen. Series of sagittal T1-weighted MR arthrographic images of lateral meniscus extending from lateral to medial shows three popliteomeniscal fascicular attachments. Anteroinferior popliteomeniscal fascicle (AI-PMF) is thinner than posterosuperior popliteomeniscal fascicle (PS-PMF) in this knee. The posteroinferior popliteomeniscal fascicle (PI-PMF) extends upward and in medial direction from medial aponeurotic extension (arrowheads, F and G) of popliteus musculotendinous region and attaches to inferior margin of posterior horn of lateral meniscus immediately below posterior meniscofemoral ligament of Wrisberg (curved arrow in G).

View larger version (109K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3B —Popliteomeniscal fascicular attachments of cadaver specimen. Series of sagittal T1-weighted MR arthrographic images of lateral meniscus extending from lateral to medial shows three popliteomeniscal fascicular attachments. Anteroinferior popliteomeniscal fascicle (AI-PMF) is thinner than posterosuperior popliteomeniscal fascicle (PS-PMF) in this knee. The posteroinferior popliteomeniscal fascicle (PI-PMF) extends upward and in medial direction from medial aponeurotic extension (arrowheads, F and G) of popliteus musculotendinous region and attaches to inferior margin of posterior horn of lateral meniscus immediately below posterior meniscofemoral ligament of Wrisberg (curved arrow in G).

View larger version (103K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3C —Popliteomeniscal fascicular attachments of cadaver specimen. Series of sagittal T1-weighted MR arthrographic images of lateral meniscus extending from lateral to medial shows three popliteomeniscal fascicular attachments. Anteroinferior popliteomeniscal fascicle (AI-PMF) is thinner than posterosuperior popliteomeniscal fascicle (PS-PMF) in this knee. The posteroinferior popliteomeniscal fascicle (PI-PMF) extends upward and in medial direction from medial aponeurotic extension (arrowheads, F and G) of popliteus musculotendinous region and attaches to inferior margin of posterior horn of lateral meniscus immediately below posterior meniscofemoral ligament of Wrisberg (curved arrow in G).

View larger version (106K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3D —Popliteomeniscal fascicular attachments of cadaver specimen. Series of sagittal T1-weighted MR arthrographic images of lateral meniscus extending from lateral to medial shows three popliteomeniscal fascicular attachments. Anteroinferior popliteomeniscal fascicle (AI-PMF) is thinner than posterosuperior popliteomeniscal fascicle (PS-PMF) in this knee. The posteroinferior popliteomeniscal fascicle (PI-PMF) extends upward and in medial direction from medial aponeurotic extension (arrowheads, F and G) of popliteus musculotendinous region and attaches to inferior margin of posterior horn of lateral meniscus immediately below posterior meniscofemoral ligament of Wrisberg (curved arrow in G).

View larger version (106K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3E —Popliteomeniscal fascicular attachments of cadaver specimen. Series of sagittal T1-weighted MR arthrographic images of lateral meniscus extending from lateral to medial shows three popliteomeniscal fascicular attachments. Anteroinferior popliteomeniscal fascicle (AI-PMF) is thinner than posterosuperior popliteomeniscal fascicle (PS-PMF) in this knee. The posteroinferior popliteomeniscal fascicle (PI-PMF) extends upward and in medial direction from medial aponeurotic extension (arrowheads, F and G) of popliteus musculotendinous region and attaches to inferior margin of posterior horn of lateral meniscus immediately below posterior meniscofemoral ligament of Wrisberg (curved arrow in G).

View larger version (103K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3F —Popliteomeniscal fascicular attachments of cadaver specimen. Series of sagittal T1-weighted MR arthrographic images of lateral meniscus extending from lateral to medial shows three popliteomeniscal fascicular attachments. Anteroinferior popliteomeniscal fascicle (AI-PMF) is thinner than posterosuperior popliteomeniscal fascicle (PS-PMF) in this knee. The posteroinferior popliteomeniscal fascicle (PI-PMF) extends upward and in medial direction from medial aponeurotic extension (arrowheads, F and G) of popliteus musculotendinous region and attaches to inferior margin of posterior horn of lateral meniscus immediately below posterior meniscofemoral ligament of Wrisberg (curved arrow in G).

View larger version (125K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3G —Popliteomeniscal fascicular attachments of cadaver specimen. Series of sagittal T1-weighted MR arthrographic images of lateral meniscus extending from lateral to medial shows three popliteomeniscal fascicular attachments. Anteroinferior popliteomeniscal fascicle (AI-PMF) is thinner than posterosuperior popliteomeniscal fascicle (PS-PMF) in this knee. The posteroinferior popliteomeniscal fascicle (PI-PMF) extends upward and in medial direction from medial aponeurotic extension (arrowheads, F and G) of popliteus musculotendinous region and attaches to inferior margin of posterior horn of lateral meniscus immediately below posterior meniscofemoral ligament of Wrisberg (curved arrow in G).

View larger version (115K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4A —Attachment of medial aponeurosis to posterior cruciate ligament. Axial T1-weighted MR arthrographic image shows inferomedial extension from medial aponeurosis to inferolateral aspect (arrows) of posterior cruciate ligament (PCL).

View larger version (142K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4B —Attachment of medial aponeurosis to posterior cruciate ligament. Axial section of different specimen from A with traction on medial aponeurotic extension of popliteus muscle–tendon unit shows attachment to posterior cruciate ligament (arrows). POP = popliteus tendon.

View larger version (75K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5A —Medial aponeurosis attachments of cadaver specimen. Series of axial T1-weighted MR arthrographic images from inferior (A) to superior (D) aspects. PCL = posterior cruciate ligament. MR arthrographic image shows relation between popliteus tendon (POP) and medial aponeurosis (arrowheads). Medial attachments to posterior capsule (large arrow) and ligament of Wrisberg (small arrow) extend from medial aponeurosis. LM = lateral meniscus.

View larger version (139K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5B —Medial aponeurosis attachments of cadaver specimen. Series of axial T1-weighted MR arthrographic images from inferior (A) to superior (D) aspects. PCL = posterior cruciate ligament. Successive superior MR arthrographic images show Wrisberg extension (short arrows) of medial aponeurosis can be followed upward. Upward extension of medial aponeurosis (arrowheads) forms inferior connection with oblique popliteal ligament (long arrows, D). Asterisk (B and C) indicates meniscofemoral ligament of Humphry.

View larger version (134K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5C —Medial aponeurosis attachments of cadaver specimen. Series of axial T1-weighted MR arthrographic images from inferior (A) to superior (D) aspects. PCL = posterior cruciate ligament. Successive superior MR arthrographic images show Wrisberg extension (short arrows) of medial aponeurosis can be followed upward. Upward extension of medial aponeurosis (arrowheads) forms inferior connection with oblique popliteal ligament (long arrows, D). Asterisk (B and C) indicates meniscofemoral ligament of Humphry.

View larger version (145K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5D —Medial aponeurosis attachments of cadaver specimen. Series of axial T1-weighted MR arthrographic images from inferior (A) to superior (D) aspects. PCL = posterior cruciate ligament. Successive superior MR arthrographic images show Wrisberg extension (short arrows) of medial aponeurosis can be followed upward. Upward extension of medial aponeurosis (arrowheads) forms inferior connection with oblique popliteal ligament (long arrows, D). Asterisk (B and C) indicates meniscofemoral ligament of Humphry.

Additional attachments of the medial aponeurosis were seen. An attachment to the posterior joint capsule was seen on MR arthrographic images of eight of the 10 knees. A deeper extension to the inferolateral aspect of the posterior cruciate ligament was found in seven of the 10 specimens (Fig. 4A, 4B). A focal thickening of the medial aponeurosis coursed upward, where it joined the oblique popliteal ligament to form an inferior connection between the medial aponeurosis and the oblique popliteal ligament in seven of the 10 specimens (Fig. 5A, 5B, 5C, 5D). In one knee in which both the anterior and posterior meniscofemoral ligaments were present, the medial aponeurotic extension from the popliteus musculotendinous region extended medially to form the posterior meniscofemoral ligament of Wrisberg (Fig. 5A, 5B, 5C, 5D). In this knee, the anterior meniscofemoral ligament of Humphry had a normal attachment to the posterior horn of the lateral meniscus.

discussion

Top Abstract Introduction Materials and Methods Results discussion References

 
There has been increasing interest in the meniscocapsular attachments of the popliteus muscle–tendon complex. These attachments not only are important in allowing the tendon to pass through the joint capsule to assume an extraarticular location but also act in concert with the popliteus complex to retract the lateral meniscus from the joint during knee flexion to prevent excessive meniscal shearing forces and entrapment [8–10]. A number of studies [3, 9] have shown a relatively high prevalence of disruption of the popliteomeniscal fascicle at arthroscopic surgery on patients with anterior cruciate ligament tears.

In this series, the anteroinferior and posterosuperior popliteomeniscal fascicles were seen on all MR arthrographic studies. In comparison, Feipel et al. [14] found the anteroinferior popliteomeniscal fascicle in 83% and the posterosuperior popliteomeniscal fascicle in 90% of dissections of 42 embalmed knee specimens. Terry and LaPrade [15] and Stäubli and Birrer [3] described the presence of these fascicles in their studies of 30 and 14 fresh cadavers, but they did not discuss how frequently the fascicles were seen in the specimens. In arthroscopic studies [3, 15, 18], the anteroinferior and posterosuperior popliteomeniscal fascicles have been reported to be present in nearly all patients examined. Tria et al. [19], unlike most other investigators, found fascicular attachments to the lateral meniscus in only 22 of 40 knee dissections.

In our study, unlike the posterosuperior popliteomeniscal fascicle, which had uniform thickness, the anteroinferior popliteomeniscal fascicle had variable thickness, ranging from a thin membrane-like structure to a much more robust structure. Bozkurt et al. [20] described a lateral meniscofibular ligament that appeared to correspond to the anatomic description of the anteroinferior popliteomeniscal fascicle in all 50 specimens examined by microdissection and transillumination. We found the lateral portion of the anteroinferior popliteomeniscal fascicle passed downward and in a lateral direction to form a conjoined attachment with the popliteofibular ligament at the fibular styloid process, resulting in a connection between the lateral aspect of the body of the lateral meniscus and the styloid process of the fibula that matched the description of a meniscofibular ligament by Bozkurt et al.

Terry and LaPrade [15] described a third popliteomeniscal fascicle designated the posteroinferior popliteomeniscal fascicle, which extended from the medial aponeurotic extension of the popliteus tendon to attach to the inferior margin of the posterior horn of the lateral meniscus. The posteroinferior popliteomeniscal fascicle was seen in 40% of the knees in our study compared with 17% of those studied by Feipel et al. [14]. Ullrich et al. [16] found a third popliteomeniscal fascicle in their dissections of 13 fresh knees, but the frequency of the finding of a posteroinferior popliteomeniscal fascicle was not stated. Inconsistencies in descriptions of the third popliteomeniscal fascicle and doubts about its existence may relate to studies concentrated solely on the popliteal hiatus region without consideration of the more medially located capsular aponeurotic extension from the popliteus tendon and its complex posteromedial attachments. Last [17], in a report on the popliteus complex in 1950, described the broad medial aponeurotic extension from the medial portion of the popliteus muscle with a prominent attachment to the inferior margin of the posterior horn of the lateral meniscus. This description corresponds to other descriptions of the posteroinferior popliteomeniscal fascicle.

The medial aponeurotic extension of the popliteus muscle appears to be an important structural element of the popliteus complex. In addition to blending with the posterior capsule, this extension forms an inferior connection with the popliteal oblique ligament, sends attachments to the posterior cruciate ligament and posterior horn of the lateral meniscus (posteroinferior popliteomeniscal fascicle), and in some individuals gives origin to a variant of the ligament of Wrisberg. Thus the popliteus muscle–tendon complex has attachments that form a robust-appearing cruciate arrangement: a superior attachment to the femur at the popliteal sulcus, an inferior triangular attachment of the main muscle bulk to the posterior aspect of the tibia, a robust inferolateral attachment to the fibular styloid process via the popliteofibular ligament, and several complex superomedial attachments to the joint capsule, lateral meniscus, oblique popliteal ligament, and ligament of Wrisberg. The importance of the popliteus muscle–tendon unit is highlighted by these robust-appearing attachments and by study findings [16, 21, 22] of dynamic and static functions that include balancing and controlling neutral tibial rotation, acting as a principal dorsolateral knee stabilizer, and preventing lateral meniscal entrapment during knee flexion by retraction of the meniscus via popliteomeniscal fascicle attachments.

Limitations of this study included the relatively small number of specimens, allowing only limited comment on the frequency of variations in the attachments of the popliteus complex. In addition, the cadavers were those of elderly persons (average age at death, 85 years). In most specimens, moderate degenerative joint disease was present, with variable areas of articular surface wear and meniscal degeneration or tearing. These changes might have affected visualization of structures on MR arthrographic images. Ligament, capsular, and fascicular degenerative changes might also have contributed to variability in the appearance of these structures with resultant adaptive thickening or attenuation. No history of knee injury or surgery was evident in any of the knee specimens, but untreated or unreported injury cannot be excluded.

Arthrographic fluid in the joints provided excellent joint distention and optimized visualization of the popliteomeniscal fascicles, but this technique is not part of routine MRI of the knee. In the absence of substantial joint effusion or hemarthrosis, it is unlikely that visualization of the popliteomeniscal fascicles will be as optimal in nonarthrographic studies of the knee. Hemarthrosis is a common finding in patients with acute tear of the anterior cruciate ligament, who have been found to be at particular risk of popliteomeniscal fascicle tears [3, 9]. Sakai et al. [7] used an optimized oblique coronal plane in combination with nonarthrographic MRI and found the anteroinferior popliteomeniscal fascicle in 94.1% and the posterosuperior popliteomeniscal fascicle in 88.2% of subjects. We used all three orthogonal MR arthrographic imaging planes in analysis and did not assess the visibility of the popliteomeniscal fascicles in individual imaging planes. Our impression, however, was that the popliteomeniscal fascicles were best seen on sagittal MR arthrographic images.

We studied the normal MRI anatomic features of the popliteomeniscal fascicles and found three fascicles. The third, or posteroinferior, popliteomeniscal fascicle was located medial in relation to the popliteal hiatus and arose from a medial aponeurotic extension of the popliteus musculotendinous region, which had additional capsular, oblique popliteal ligament, posterior cruciate, and ligament of Wrisberg attachments. These extensive attachments, combined with femoral, tibial, and fibular attachments, highlight the important role of the popliteus muscle–tendon unit in the posterolateral corner of the knee.

References

Top Abstract Introduction Materials and Methods Results discussion References

 

1. Fleming RE Jr, Blatz DJ, McCarroll JR. Posterior problems in the knee: posterior cruciate insufficiency and posterolateral rotatory insufficiency. Am J Sports Med 1981;9 : 107–113[Abstract/Free Full Text]
2. Hughston JC, Jacobson KE. Chronic posterolateral rotatory instability of the knee. J Bone Joint Surg Am1985; 67:351 –359[Abstract/Free Full Text]
3. Stäubli HU, Birrer S. The popliteus tendon and its fascicles at the popliteal hiatus: gross anatomy and functional arthroscopic evaluation with and without anterior cruciate ligament deficiency. Arthroscopy 1990;6 : 209–220[Medline]
4. De Smet AA, Asinger DA, Johnson RL. Abnormal superior popliteomeniscal fascicle and posterior pericapsular edema: indirect MR imaging signs of a lateral meniscal tear. AJR2001; 176:63 –66[Abstract/Free Full Text]
5. Blankenbaker DG, De Smet AA, Smith JD. Usefulness of two indirect MR imaging signs to diagnose lateral meniscal tears. AJR 2002; 178:579 –582[Abstract/Free Full Text]
6. Johnson RL, De Smet AA. MR visualization of the popliteomeniscal fascicles. Skeletal Radiol 1999;28 : 561–566[CrossRef][Medline]
7. Sakai H, Sasho T, Wada Y, Sano S, Morita F, Moriya H. MRI of the popliteomeniscal fasciculi. AJR 2006;186 : 460–466[Abstract/Free Full Text]
8. Simonian PT, Sussmann PS, Wickiewicz Tl, et al. Popliteomeniscal fasciculi and the unstable lateral meniscus: clinical correlation and magnetic resonance diagnosis. Arthroscopy 1997;13 : 590–596[Medline]
9. LaPrade RF. Arthroscopic evaluation of the lateral compartment of knees with grade 3 posterolateral knee complex injuries. Am J Sports Med 1997; 25:596 –602[Abstract/Free Full Text]
10. Simonian PT, Sussmann PS, van Trommel M, Wickiewicz TL, Warren RF. Popliteomeniscal fasciculi and lateral meniscal stability. Am J Sports Med 1997; 25:849 –853[Abstract/Free Full Text]
11. LaPrade RF, Konowalchuk BK. Popliteomeniscal fascicle tears causing symptomatic lateral compartment knee pain: diagnosis by the figure-4 test and treatment by open repair. Am J Sports Med2005; 33:1231 –1236[Abstract/Free Full Text]
12. Diamantopoulos A, Tokis A, Tzurbakis M, Patsopoulos I, Georgoulis A. The posterolateral corner of the knee: evaluation under microsurgical dissection. Arthroscopy 2005;21 : 826–833[Medline]
13. Munshi M, Pretterklieber ML, Kwak S, Antonio GE, Trudell DJ, Resnick D. MR imaging, MR arthrography, and specimen correlation of the posterolateral corner of the knee: an anatomic study. AJR 2003; 180:1095 –1101[Abstract/Free Full Text]
14. Feipel V, Simonnet ML, Rooze M. The proximal attachments of the popliteus muscle: a quantitative study and clinical significance. Surg Radiol Anat 2003;25 : 58–63[CrossRef][Medline]
15. Terry GC, LaPrade RF. The posterolateral aspect of the knee: anatomy and surgical approach. Am J Sports Med1996; 24:732 –739[Abstract/Free Full Text]
16. Ullrich K, Krudwig WK, Witzel U. Posterolateral aspect and stability of the knee joint. Part 1. Anatomy and function of the popliteus muscle–tendon unit: an anatomical and biomechanical study. Knee Surg Sports Traumatol Arthrosc 2002;10 : 86–90[CrossRef][Medline]
17. Last RJ. The popliteus muscle and the lateral meniscus: with a note on the attachment of the medial meniscus. J Bone Joint Surg Br 1950; 32:93 –99
18. Patel D. Proximal approaches to arthroscopic surgery of the knee. Am J Sports Med 1981;9 : 296–303[Abstract/Free Full Text]
19. Tria AJ, Johnson CD, Zawadsky JP. The popliteus tendon. J Bone Joint Surg Am 1989;71 : 714–716[Abstract/Free Full Text]
20. Bozkurt M, Elhan A, Tekdemir I, Tonuk E. An anatomical study of the meniscofibular ligament. Knee Surg Sports Traumatol Arthrosc 2004; 12:429 –433[Medline]
21. Moorman CT 3rd, LaPrade RF. Anatomy and biomechanics of the posterolateral corner of the knee. J Knee Surg2005; 18:137 –145[Medline]
22. LaPrade RF, Ly TV, Wentorf FA, Engebretsen L. The posterolateral attachments of the knee: a qualitative and quantitative morphologic analysis of the fibular collateral ligament, popliteus tendon, popliteofibular ligament, and lateral gastrocnemius tendon. Am J Sports Med 2003; 31:854 –860[Abstract/Free Full Text]

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