New Biomechanics in Illustrations

 

The New Biomechanics of the Hip Joint: A Pictorial Essay

S.V. Arkhipov 

INTRODUCTION 

First in the history of humanity, the mention of ligamentum capitis femoris (LCF) and the pathomechanics of walking associated with its damage is found in the ancient literary monument “Book of Genesis” (32:24-24,31-32), created approximately 3600 years ago (2019Arkhipov_Skvortsov; 2023Архипов).

Fig. 1 The LCF = ligamentum teres of the hip joint, drawing by H.V. Carter (1870Grey).

Fig. 2 Pencil drawing “Crossing of the Jabbok River” based on the “Book of Genesis” 32:22 (author: Lyudmila Arkhipova, 2008).

The first description of LCF in a medical text is given by Hippocrates of Kos in the treatise “Instruments of Reductions” or “Mochlicus”, written in the V-IV centuries BCE (1844Littre).

We know that with the normal LCF, walking it is light, rhythmic, and symmetrical, but we don't know “why”. See video: Supplement 1 Normal Walking

We don't even know why we wiggle our pelvis when walking!

It is known that during single-leg support in normal walking, adduction occurs in the hip joint and the pelvis tilts in the opposite direction.

Fig. 3. Walking in vivo – single-leg support phase in norm; video frame.

Fig. 4. Walking in vitro – single-leg support phase in norm; video frame (2013Архипов).

Fig. 5. Instrumental 3D gait analysis; left – single-leg support phase in normal walking; right – graphs of pelvic and thigh movements in the frontal plane.

Pelvic tilt and adduction in the supporting hip joint in a single-support position are observed.

Fig. 6. Transition from two-legged to single-legged stance (2013Архипов).

In the statue's pose, a pelvic tilt and adduction in the supporting hip joint are observed too.

Fig. 7 Biblical David (artist: Michelangelo, 1501–1504; copy in the Pushkin State Museum, Moscow).

Such a pelvic position was noticed in ancient times, see: Logios Hermes (5th century BCE), Diadumenos (about 420 BCE), Aphrodite of Knidos (4th century BCE), Hercules of the Forum Boarium (2th century BCE), Victorious Youth (300–100 BCE), Antikythera Ephebe (70–60 BCE).

The first image of the pelvic tilt in a medical book is an illustration Andreae Vesalius' treatise “De humani corporis fabrica” (1543Vesale).

Fig. 8. Drawing in the book “De humani corporis Fabrica” (1543Vesale); illustration “Studio of Titian” (Tiziano Vecelli) or Jan Stephan van Calcar (1987Harcourt).

Later, we see this in William Cheselden's “Osteographia” (1733).

Fig. 9. Drawing in the book “Osteographia” (1733Cheselden); author Gerard Vandergucht and/or Jacob Schijnvoet (2011Kornell).

Why do we wiggle pelvis while the walking and the tilt it in the standing position? Our hypothesis: for tensioning of the LCF.

Galen of Pergamum (II-III c. AD) in “Hippocratis de articulis liber Galeni in eum commentarii quatuor” calls LCF - “ἰσχυρότατος” i.e., “strongest” (1829Kühn). Wenger et al (2007): LCF strength can reach 882±168 N! Theoretically, LCF can function as a pelvic suspension.

Fig. 10 Galen of Pergamon; drawing from the book “Operum Hippocratis Coi, et Galeni Pergameni…” (1638René).

Nobel Laureate János (Hans) Selye (1907-1982) wrote that a significant contribution to the study of stress was made through simple means (1960Селье).

Fig. 11 Photographic portrait of prof. Hans Selye (original on the site wikipedia.org, CC BY-SA 4.0, ½ part of the image).

We also initiated research on the biomechanics of the hip joint using simplified models...

DISCUSSION 

I. Initially, it was confirmed that the tilt of the pelvis and hip adduction lead to tensioning of the LCF.

Fig. 12 A planar model of the hip joint with the LCF analog (made before 2004); overall view of the model.

Fig. 13 Simulation of adduction and abduction on a planar model of the hip joint with an LCF analogue.

II. Experiments on a model of the hip joint (synthetic bones) with the LCF analog.

Fig. 14 The model of the hip joint with the LCF analog; modeling of abduction and adduction; visualization of the LCF tension.

III. Experiments on a mechanical model of the hip joint with the LCF analog.

Fig. 15 The mechanical model of the hip joint with the LCF analog; connection of the components and overall view of the model.

Fig. 16 The mechanical model of the hip joint with the LCF analog; modeling of abduction and adduction.

We have proven that LCF serves as the adduction limiter and pelvic stabilizer.

IV. Experiments on a mechanical model of the hip joint with a planar model of the pelvic part and the LCF analog, as well as, a mechanical model of the femoral head with the LCF analog.

We observed the effect of pressing the acetabulum to the head of the femur.

Fig. 17 The mechanical model of the hip joint with a planar model of the pelvic part and the LCF analog – modeling of adduction (left); mechanical model of the femoral head with the LCF analog – emergence of the resultant force (right).

The effect of pressing the acetabulum against the femoral head is important in preventing hip dislocation.

V. Tensioning of the LCF forms a cable-stayed type of pelvic suspension and provides additional support to the body.

Fig. 18 The planar model of the hip joint with the LCF analog (1/2 of the pelvic part); modeling of adduction.

A cable-stayed bridge as an analogy of the pelvic–LCF system.

Fig. 19 The cable-stayed bridge (Vladivostok, Russia).

The LCF functions as a cable-stayed type of pelvic suspension.

VI. Transformation of the hip joint into a class three lever and compression on the lower sector of the femoral head; experiments on a mechanical model of the proximal femur with the LCF analog.

Fig. 20 The mechanical model of the proximal femur with the LCF analog; modeling of adduction.

Fig. 21 The planar model of the hip joint with the LCF analog (1/2 of the pelvic part); modeling of adduction – compression on the lower sector of the femoral head occurs.

Tensioning of the LCF causes the appearance of compression in the lower sector of the femoral head.

VII. The reaction force of the LCF reduces compression on the upper sector of the femoral head and increases it in the lower sector.

Fig. 22 The mechanical model of the hip joint with a planar model of the pelvic part and the LCF analog; modeling of abduction.

VIII. Morphological Evidence.

In the lower sector of the femoral head, the cartilaginous layer is thinner because the compression from the lower sector of the acetabulum is greater.

Fig. 23. Fracture of the femoral neck and traumatic rupture of the LCF; intraoperative observation; pay attention to the thickness of the cartilage in the lower sector of the femoral head.

Ligamentous-muscular interaction provides compression of the upper end of the femur.

Fig. 24 Simplified scheme of the interaction between LCF and muscles in the hip joint area.

The medial sector of the second trabecular system of the upper end of the femur is the result of pressure on the lower sector of the femoral head from the acetabulum side.

Fig. 25 Trabecular systems of the femur and pelvis; II M – medial area of the second trabecular system.

IX. Tensioned LCF shunts the body mass and unloads the abductor muscle group of the hip joint.

Fig. 26. Mechanical model of the hip joint with an LCF analog and an analog of the abductor muscle group.

LCF serves as a shunt for body mass and transforms the hip joint into a class three lever.

X. Without LCF, the hip joint functions only as a class one lever.

Fig. 27 Mechanical model of the hip joint with an analog of the abductor muscle group and without an LCF analog.

XI. Contradiction as evidence.

In “classic biomechanics” (without LCF), the hip joint functions as a class one lever. Compression of the femoral head in a single-support stance is 175 kg (1976Pauwels), reaching 229 kg during normal walking (1993Bombelli).

Fig. 28 Schemes of “classic biomechanics” of the hip joint (illustrations from Pauwels (1976), and Bombelli (1993) as graphic quotations).

In some cases, during walking, compression exceeds the subject's weight by 5.8 times (1966Paul).

Some researchers question, “...what compensates for the enormous forces applied to the femoral head?” (1975Янсон).

Indeed, what can compensate for the immense pressure on the femoral head?

Paul (1966), Pauwels (1976), and Bombelli (1993) are correct; in the absence of LCF, the force generated by the abductor muscle group is approximately three times the body weight: i.e., equivalent to 210 kg with a total body mass of 70 kg.

Fig. 29. Lever model of the hip joint (without an LCF analog).

Kapandji (2009): m. gluteus medius can develop force – 16 kg, m. gluteus minimus – 4.9 kg, m. tensor fascia lata – 7.6 kg; i.e., a total of 28.5 kg!

XII. Paradox of the m. gluteus medius as evidence.

During single-leg support, in the middle and end of the single-support phase of the gait cycle, the force (electromyographic activity) of the m. gluteus medius is reduced.

Fig. 30 EMG of the m. gluteus medius; instrumental 3D gait analysis.

The reason for the reduction in muscle activity is the tensioning of LCF.

XIII. During single-leg stance, in the pose of the ancient statue, and in the single-support phase of the gait cycle, LCF is tensioned.

Fig. 31. Pelvic tilt and thigh adduction during walking; LCF is tensioned.

XIV. X-ray in a single-leg standing position (radiographic confirmation).

Fig. 32. Upward displacement of the femoral head pit (red arrow) during adduction in the supporting hip joint.

LCF - tensioned.

Fig. 33. Downward displacement of the femoral head pit (red arrow) during abduction in the supporting hip joint.

LCF - relaxed.

XV. Tensioned LCF is a synergist of the abductor muscle group of the hip joint.

Fig. 34. Lever model of the hip joint with an LCF analog.

XVI. Pelvic tilt and adduction in the hip joint without ligaments.

Fig. 35. Modeling the single-support phase of the gait cycle during normal walking, on a dynamic model of the hip joint with an analog of the m. gluteus medius (without ligament analogs).

The force of the m. gluteus medius analog increases.

XVII. Pelvic tilt and adduction in the hip joint with only LCF.

Fig. 36. Modeling single-leg support during walking on a dynamic model of the hip joint with an LCF analog and an analog of the m. gluteus medius.

The force of the m. gluteus medius analog decreases.

XVIII. Pelvic tilt and adduction in the hip joint with the presence of external ligaments and LCF.

Fig. 37. Modeling single-leg support during walking on a dynamic model of the hip joint with an LCF analog, analogs of external ligaments, and an analog of the m. gluteus medius.

The force of the m. gluteus medius analog decreases, and pelvic stability increases.

IXX. Experiments on a dynamic model of the hip joint.

Modeling the single-leg support phase during normal walking.

Watch the video: Supplement 2 Gluteus Medius & LCF

It has been experimentally confirmed that LCF acts as a thigh adduction limiter, transforms the hip joint into a class three lever, prevents dislocation, suspends the pelvis, and acts as a synergist to the abductor muscle group.

XX. Modeling on a single leg pose with maximum pelvic tilt and thigh adduction.

Fig. 38. Dynamic model of the hip joint with analogs of ligaments and muscles.

The greatest pelvic stability is achieved when all hip joint ligaments are tensioned.

XXI. Modeling on a single leg pose without pelvic tilt.

Fig. 39. Dynamic model of the hip joint with analogs of ligaments and muscles.

Pelvic stability is achieved only by the force of the m. gluteus medius and the m. rectus femoris.

XXII. Modeling on a single leg pose with optimal pelvic tilt and hip adduction.

Fig. 40 Dynamic model of the hip joint with analogs of ligaments and muscles.

Pelvic stability is achieved through the tension of LCF and the force of the m. gluteus medius.

XXIII. When activating the abductor muscle group, with the tension of LCF and external ligaments, pressure on the femoral head is evenly distributed.

Normally, pressure on the upper sector of the femoral head is approximately equivalent to body weight.

Fig. 41. Distribution of forces in the hip joint when standing on one leg, as well as in the pose of an ancient statue, and in the single-leg support phase during normal walking (with pelvic tilt and thigh adduction).

XXIV. Moment rule for the supporting hip joint when standing on one leg, as well as in the pose of an ancient statue, and in the single-leg support phase during normal walking (considering only the reaction forces of ligaments, abductor, and adductor muscles).

Fig. 42. Moment rule for the supporting hip joint when standing on one leg, as well as in the pose of an ancient statue, and in the single-leg support phase during normal walking.

CONCLUSION

LCF is an essential component of the hip joint. Pelvic tilt and thigh adduction in the supporting hip joint when standing on one leg, in the pose of an ancient statue, as well as in the single-leg support phase during normal walking, provide tension to LCF. This element supports the pelvis as a suspension, unloads the abductor muscle group of the hip joint, and contributes to the even distribution of pressure on the femoral head.

LIMITATIONS

We acknowledge that this study has limitations inherent to experimental research on mechanical models. Additional research is needed to refine the pressure distribution on the femoral head for the supporting hip joint when standing on one leg, in the pose of an ancient statue, and in the single-leg support phase during normal walking.

References

Arkhipov SV, Skvortsov DV. Ligamentum capitis femoris: first written mentions. Muscles, Ligaments and Tendons Journal. 2019, 9(2)156–64.

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Cheselden W. Osteographia, or the anatomy of the bones. London: W. Bowyer [?], 1733.

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Kornell M. (2011, August 22) Accuracy and Elegance in Cheselden’s Osteographia (1733). Retrieved September 20, 2019. from publicdomainreview.org 

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In translating to English, the author is assisted by ChatGPT (version 3.5) and the Google Translate service.

If you notice an error, please let us know!

The first version:

Arkhipov SV. New Biomechanics of the Hip Joints: Ligamentum Teres as a Functional Relation. Part I. Pictorial Essay. Ligamentum Teres – Ligamentum Incognitum. 2019, September 22:1–25. DOI: 10.13140/RG.2.2.11991.62881 [researchgate.net , ligteres.com]

Keywords: ligamentum capitis femoris, ligamentum teres, ligament of head of femur, abductor muscle group, hip joint, model, biomechanics, walk, gait cycle, gluteus medius, single-legged stance

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