Patellofemoral Joint
Original Editor - Elvira Muhic
Lead Editors - Elvira Muhic, Kim Jackson, Lilian Ashraf, WikiSysop, Ahmed Essam, 127.0.0.1, Admin, Rachael Lowe, Evan Thomas, Michelle Lee, Vidya Acharya, Rucha Gadgil, Jess Bell and Robin Tacchetti
Description[edit | edit source]
The patellofemoral joint is a unique and complex structure consisting of static elements (bones and ligaments) and dynamic elements (neuromuscular system).Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
Anatomy[edit | edit source]
Articulating Surfaces[edit | edit source]
The patella has a configuration of a triangle with its apex directed inferiorly. Superiorly, it articulates with the trochlea, the distal articulating surface of the femur, which are the main articulating surfaces of patellofemoral joint.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
The articular cartilage of the patella is similar to that of other joints in that it contains a solid phase and a fluid phase that is mostly composed of collagen and glycosaminoglycans. The solid phase is somewhat permeable and when the articular surface is under load, the fluid gradually redistributes itself within the solid matrix. Therefore, the pressure within the fluid is strongly associated with the cushioning effect of the articular cartilage and the low friction coefficient of articular surfaces. Any damage to the articular surfaces causes a loss of pressure within the fluid phase, which subsequently results in higher stresses on the collagen fibers and more vulnerability leading to possible breakdown.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
Ligaments & Joint Capsule
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The Medial Patellofemoral Ligament (MPFL) - has an origin on the medial femur and a “sail-shaped” attachment on the patella and quadriceps tendon. Because of its wider attachment than its origin, several authors have promoted the technique of using a double-bundled graft to recreate the anatomy of this complex. Kang and colleagues described two components of MPFL fibers, using the term superior-oblique bundle and inferior-straight bundle. The clinical significance of this is not yet known, but the authors suggested the bundles may vary in their roles as dynamic versus static stabilizers. Furthermore, length differences between the two bundles or attachment sites, have been described. Mochizuki and colleagues showed the length of the MPFL fibers from the origin to the medial patella was 56.3+/-5.1 mm vs. 70.7+/-4.5 mm to the quadriceps tendon.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
Muscles[edit | edit source]
Medial movement of the patella is controlled by the vastus medialis oblique (VMO) muscle. Lateral tracking is guided by both the vastus lateralis and the iliotibial band. Patellar motion is further constrained by the patellofemoral ligament, the patellotibial ligament, and the retinaculum.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
Function[edit | edit source]
Compression at the patellofemoral jointCite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title:
| Activity | Force | %Body Weight | Pounds of Force |
|---|---|---|---|
| Walking | 850 N | 1/2 x BW | 100 Ibs |
| Bike | 850 N | 1/2 x BW | 100 Ibs |
| Stair Ascend | 1500 N | 3.3 x BW | 660 Ibs |
| Stair Descend | 4000 N | 5 x BW | 1000 Ibs |
| Jogging | 5000 N | 7 x BW | 1400 Ibs |
| Squatting | 5000 N | 7 x BW | 1400 Ibs |
| Deep Squatting | 15000 | 20 x BW | 4000 Ibs |
Motions Available[edit | edit source]
Range of Motion
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Osteokinematics[edit | edit source]
Arthrokinematics[edit | edit source]
The patella lies within the quadriceps tendon and thereby increases the mechanical advantage of the quadriceps mechanism. Not only does the patella increase the force of knee extension by 50%, but it also provides stability to the patellar tendon and minimizes the forces placed on the femoral condyles. Tracking of the patella begins with the lower patellar border lying in contact with the suprapatellar fat pad when the knee is fully extended. With knee flexion, the patella moves proximally with a lateral shift.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title During normal patellar tracking, the patella engages in the trochlea at around 30° of knee flexion and remains stable then after due to the bony constraints of the trochlea.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title As the knee continues to flex, the tibia internally rotates and the patella moves upward.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
The patella is engaged with the trochlea at 20-30º of knee flexion. At 90º the patella contacts the lateral and medial femoral facets within the condylar fossa. At 130-135 º of knee flexion, the medial facets of the patella contact the articulating surface of the femoral condyles.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title
Pathology/Injury
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Techniques
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Palpation[edit | edit source]
Examination
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Treatment[edit | edit source]
Resources[edit | edit source]
Recent Related Research (from Pubmed)[edit | edit source]
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References[edit | edit source]
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