Classification of Functions of LCF

Version: 20240224

Introduction

On the biology, the common meaning of 'function' is that of role, effect, or transformation rule (1994MorenoA_Fern´andezJ). The function of ligamentum capitis femoris (LCF) is still unknown (2009LampertC) and the ligament itself continues to bewilder and fascinate orthopaedic surgeons (2020Rosinsky_DombBG). The largest collections of opinions on the function of the LCF are contained in our works (2004Архипов-БалтийскийСВ; 2018,2023АрхиповСВ). The classification of the function of the LCF necessary to determine the directions for further study of this structure, the choice of goals and methods for its surgical recovery. The reconstruction of the LCF without restoring specific functions to solve a clearly defined clinical and biomechanical problem is nothing more than a cosmetic procedure.

The proposed classification based on experimental and clinical studies of the author, as well as because of an analysis of literary sources. All the selected functions of the LCF divided into four types - physical, biochemical, biological and informational (Tables 1-4). We proposed to divide functions into hierarchical units similar to the elements of the systematics of living organisms: phylum, class, order, family, genus, and specie. Each function is marked with a color indicating the highest level of evidence as of the current date. The sequence of levels is located on the “confidence scale” from the highest mark - “axiom” to the lowest mark - “error” (Table 5). With further study of the LCF, we plan to expand on the above above functions and clarify the levels of evidence used.

References

Moreno A, Umerez, J, Fern´andez J. Definition of life and research program in artificial life. Ludus Vitalis. 1994;2(3)15–33.

Lampert C. Läsionen des lig. capitis femoris: pathologie und therapie. Arthroskopie. 2009;22(4)293–8.

Rosinsky PJ, Shapira J, Lall AC, Domb BG. All About the Ligamentum Teres: From Biomechanical Role to Surgical Reconstruction. J Am Acad Orthop Surg. 2020; 28(8)e328–e39.

Архипов-Балтийский С.В. Рассуждение о морфомеханике. Норма. T.2. Калининград, 2004. [In Russ.]

Архипов С.В. Биомеханика пингвинов: заметки к вопросу о причинах ковыляющей походки и перспективах ее ремоделирования…, Т.5. Королев, 2018. [In Russ.]

Архипов С.В. Связка головки бедренной кости: функция и роль в патогенезе коксартроза; 2-ое изд., испр. и доп. Йоэнсуу: Издание Автора, 2023. [In Russ.] 

Physical functions of the LCF (Table 1) 

Elastic forces functions
Static functions
Damping functions:
- for the pelvis
- for the femur
Protective function:
- for the transit vessels (arterial, venous, lymphatic)
- for the nerves (r. post. n. obtur. and other nerves)
Local compression functions:
... of the femoral head:
- the cartilaginous part
- the bony part
...of the acetabulum:
- the cartilaginous part (model of the acetabulum)
- the bony part (lunate surface)
Dislocation functions
Synovial fluid mixing function
Synovial fluid distribution function
Mesenchyme separation function
Reaction force functions (horizontal, vertical, tangential)
Dynamic functions
Functions of restriction (braking):
... translational movements
... of femur:
- on the cranial direction
- on the lateral direction
- on the medial direction
- forward
- back
… of pelvis:
- on the caudal direction
- on the medial direction
- on the lateral direction
- forward
- back
... rotational movements
... of femur
… on the horizontal plane:
- pronation
- supination
… on the frontal plane:
... adduction
... abduction
... of pelvis
… on the horizontal plane:
- turn forward
- turn back
… on the frontal plane:
- medial tilt
Motion correction functions:
... of pelvis:
- lateral tilt with turning forward
- lateral tilt with turning back
- medial tilt with leaning forward
- medial tilt with leaning back
- turn forward after turn back
- turn back after turn forward
- lateral displacement after subluxation
- lateral displacement with adduction, pronation and supination
... of femur:
- increased adduction with flexion
- increased adduction with extension
- increased abduction with pronation
- increased abduction with supination
- medial displacement with adduction, pronation, and supination
- medial displacement with initial lateralization
- increased lateral displacement with abduction and flexion
Biomechanical functions:
Converting a hip into an analog of third-class lever
Shunting of the load of the horizontal part of the iliofemoral ligament
Shunting of the load of the abductor muscle group
Reducing the load on the pronators and supinators while walking
Reducing the load on the pronators and supinators while running
Reducing the load on the flexors and extensors while walking
Reducing the load on the flexors and extensors while running
Ensuring rhythmic walking
Ensuring rhythmic running
Ensuring gait symmetry
Ensuring running symmetry
Ensuring minimal body sway while walking
Determination of the maximum speed of pelvic rotation while walking
Determination of the maximum speed of pelvic rotation while running
Determination of the amplitude of the inclination and rotation of the pelvis while walking
Determination of the amplitude of the inclination and rotation of the pelvis while running
Determination of the maximum frequency of pelvic rotation
Determining the maximum step frequency
Determination of the maximum frequency of shoulder girdle rotation while walking
Determining of the maximum frequency of hand fluctuations
Determination of the trajectory of movement of the common center of mass of the body
Determination of the acceleration of movement of the common center of mass of the body
Converting potential energy into kinetic energy while walking
Converting potential energy into kinetic energy while running
Anti-gravity dynamic functions:
Support pelvic and body while walking
Support pelvic and body while running
Reducing body weight while walking (lifting force generation)
Reducing the vertical component of the reaction force while walking
Reducing the transverse component of the reaction force while walking
Tribological functions:
Influence on friction coefficient
Influence on the reaction force of the femoral head
Static functions
Stabilization functions:
- of pelvis in one-support orthostatic position
- of pelvis in two-support asymmetrical orthostatic position
- of femoral head in the acetabulum:
- macrostabilization (antiluxation)
- microstabilization (antisubluxation)
Anti-gravity static functions (suspension):
- of pelvis in one-support orthostatic position
- of pelvis in two-support asymmetrical orthostatic position
- of femur with flexion-adduction-supination (legs crossed sitting pose)
Conducting functions (bridge, tunnel):
- for transit vessels (arterial, venous, lymphatic)
- for nerves (rr. post. n. obtur., rr. musc. n. fem., n. glut. inf. …)
Functions of the femoral head connection to the:
- fossa acetabulum
- incisura acetabulum
- ligamentum transversum
- periosteum of the pelvis
- membrana obturatoria
Tensorogenic functions:
Influences on the distribution and magnitude of internal forces (stresses) in the:
- femoral head (below «+»; above «-»)
- acetabulum (below «+»; above «-»)
- external ligaments and joint capsule (shunt)
- transverse ligament of the acetabulum (spraining)
- abductor muscle group (shunt)
Influences on the shape, size and position (deformation, displacement):
- of femoral head
- of femoral neck
- of acetabulum
- of hip bone
- of pelvis
- of lumbosacral spine

Biochemical functions of the LCF (Table 2)

Functions of regulation of synovial fluid properties:
- volume
- fluidity
- osmotic pressure
- viscosity
- surface tension
- wetting
- density
- temperature
- gas pressure
Producing functions:
Water excretion
Production of organic components
Production of inorganic components
Gas excretion
Excretion of atypical chemicals
Absorption function:
Water absorption
Absorption of organic components
Absorption of inorganic
Absorption of atypical chemical compounds (e.g. drugs)
Gas absorption
Dissolution functions:
Dissolution of inorganic substances (urates, calcium dihydropyrophosphate, hydroxyapatite)
Dissolution of organic substances (fibrinolysis, emulsification of bone marrow fat)
Gas dissolution
Deposition functions:
Crystallization of inorganic substances (urates, calcium dihydropyrophosphate)
Protein denaturation
Demulsification of fat

Biological functions of the LCF (Table 3)

Adaptation functions:
Synovial fluid volume regulation
Synovial fluid composition regulation
Hip joint temperature regulation
Hip joint pressure regulation
Involvement in immune processes
Maintaining one-support orthostatic position and two-support asymmetrical orthostatic position
Device for locomotion
Resource allocation functions:
Power distribution
Material distribution
Synthetic functions:
Cytopoietic function (synoviocytes, histiocytes, lymphocytes, neutrophils, monocytes)
The formation of chondromic bodies (synovial chondromatosis)
The formation of synovial cysts
Sanitation functions (synovial fluid sanitation):
Destruction function (cells, fibers, bacteria, tissue detritus, pus, blood clots, bone, cartilage fragments)
Extraction function (removal of degradation products)
Hormonal functions of adipose tissue:
Hormone synthesis (leptin, angiotensin, estrogen, resistin, adipsin, adiponectin)
Enzyme synthesis (plasminogen, liporotein lipase)
Peptide synthetsis (cytokines, eicosanides)
Remodeling functions:
Synovial fluid remodeling
Remodeling of adipose tissue of the acetabulum
Remodeling of the ligamentous apparatus
Articular cartilage remodeling
Acetabular labral remodeling
Bone remodeling
Tendon remodeling of abductor muscles
Remodeling muscle tissue of abductor muscles
Shape-forming functions (morphogenesis, transformation):
The formation of the external ligaments of the hip joint
The formation of cartilage (labrum acetabulum, femoral head, cartilage model of the acetabulum)
The formation of hip bone and femur
The formation of adjacent joints (pubic symphysis, sacroiliac joint, knee)
The formation of the parts of the skeleton (pelvis, spine)
Trophic functions:
Cartilage nutrition
Blood supply of the femoral head
Transport functions:
Tissue transport
Blood circulation
Lymphatic circulation

Information functions of the LCF  (Table 4)

Conductive functions:
Afferent function
Efferent function
Receptor functions:
Mechanoreceptor functions:
Baroreceptor function
Vibroreceptor function
Tensoreceptor function
Thermoreceptor functions:
Cold-sensitive function
Heat-sensitive function
Chemoreceptor function
Sensitive functions:
Kinesthesia
Proprioception
Nociception
Immuno-information functions:
Cellular immune function
Humoral immune functions
Trigger function
Metronome function

Levels of evidence of functions of the LCF with their conventional names and symbols (Table 5)

Color and number designations of evidence levels	Names of evidence levels
1	Axiom
2	Research
3	Experiment
4	Observation
5	Calculation
6	Figure
7	Publication
8	Hypothesis
9	Error

Keywords 

ligamentum capitis femoris, ligamentum teres, ligament of head of femur, role, function, hip joint, biomechanics

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