Workbook 1: Introduction to Arthrology & Arthrology of the Hip PDF

Workbook 1: Introduction to Arthrology/Arthrology of the Hip Workbook 1 Introduction to Arthrology & Arthrology of the Hip Joint Physiotherapy Programme...

Workbook 1: Introduction to Arthrology/Arthrology of the Hip Workbook 1 Introduction to Arthrology & Arthrology of the Hip Joint Physiotherapy Programme School of Health Sciences 1 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Contents Aims........................................................................................................................................................ 3 Objectives............................................................................................................................................... 3 Guidance................................................................................................................................................. 3 Introduction to Arthrology...................................................................................................................... 4 Types of Joint …………………….................................................................................................................... 4 Fibrous Joints ……………………………………................................................................................................... 5 Cartilaginous Joints................................................................................................................................. 5 Synovial Joints........................................................................................................................................ 6 The “Close-pack” Position....................................................................................................................... 9 Classification of Joints............................................................................................................................. 9 Proximal End of Femur (Anterior View)................................................................................................. 10 Proximal End of Femur (Posterior View)................................................................................................ 11 Left Innominate (Lateral View).............................................................................................................. 12 What is a Joint? Activity 1....................................................................................................................... 13 What is Cartilage? Activity 2................................................................................................................... 13 What is the Fibrous Capsule?................................................................................................................. 13 Activity 3................................................................................................................................................. 14 What is a Joint Cavity?............................................................................................................................ 14 What is a Synovial Membrane?.............................................................................................................. 14 Activity 4 ………………................................................................................................................................ 14 What are Ligaments?.............................................................................................................................. 14 Activity 5 …………………………………………..................................................................................................... 14 What are Inter-articular Structures?....................................................................................................... 15 Acland’s Atlas of Human Anatomy and Visible Body’s Human Anatomy Atlas......................................... 15 Movement of the Hip Joint..................................................................................................................... 16 Activity 7................................................................................................................................................. 16 Blood Supply........................................................................................................................................... 17 Activity 8................................................................................................................................................. 17 Hip Stability............................................................................................................................................. 17 Activity 9................................................................................................................................................. 17 2 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Aims 1. To study the general features of joints found within the human skeleton 2. To study the main anatomical features of the hip joint and to relate its structure to its function. Objectives On completion of the study guidelines you should be able to: 1. Identify the different types of joint found within the human skeleton and identify their key features 2. Identify the common components of synovial and non-synovial joints and understand their function 3. Understand the process of classifying joints 4. Name and identify the main bony landmarks of the hip region; 5. Describe the classification, structure and formation of the hip joint; 6. Discuss the stability of the hip joint; and 7. State the normal ranges of movement at the hip joint and the main limiting factors to these movements Guidance As you will be studying the hip joint in this workbook, it is important that you can identify the relevant anatomical features and bony landmarks in the hip region. The bony points that are palpable will also be identified in your practical sessions. The photos over the next few pages highlight the important bony landmarks that you will be expected to identify in the practical sessions. 3 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Introduction to Arthrology A joint is defined as a place where two or more bones meet or articulate. In long bones the ends are the parts which form the joints; in flat bones the joints are normally formed at the edges; in short bones the joints may occur at various parts of their surfaces. There are different types of joints or articulations in the body. The nature of the joint is dependent on the amount of movement permitted or required between two bones. The study of the structure and function of the joints in the body is called arthrology. When studying a joint the following format is suggested as a guideline: 1. Classification of joint; 2. Bones in articulation & features of their articular surfaces; 3. Arrangement of capsule & synovial membrane; 4. Ligaments; 5. Intra-articular structures (structures within the joint cavity that serve a special function); 6. Movements, stability & limiting factors Types of joints 4 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Fibrous joints In these articulations the opposing bony surfaces are connected to each other by fibrous tissue. Fibrous joints are divided into three types: a) Sutures are found only in the skull where the margins of the bones articulate with each other They are strongly reinforced by fibrous tissue in the form of a sutural ligament. As a result, there is no appreciable movement at a fibrous joint Clinical comment In a new born child, the bones of the cranial vault have not yet met each other at sutures. This leaves gaps covered only by connective tissue and these are called fontanelles. These gaps close within the first 2 years In the young, the bones continue to expand by growth at the sutures. When growth comes to an end, the sutural ligament ossifies (is replaced by bone). This process occurs into the 20’s b) Gomphosis are special fibrous articulations restricted to the fixation of the teeth into the mandible and maxilla. These joints are particularly relevant to dentists, but not really of interest to physiotherapists! c) Syndesmoses are rare in mammals and the only true example of this type of articulation is the inferior tibiofibular joint which we will study in this module Cartilaginous joints There are two types of cartilaginous joint: a) Synchondroses (primary cartilaginous joints) These joints are held together by a plate of hyaline cartilage. These are temporary joints designed to allow growth of bones but not movement Joints at the growth plates of long bones fall into this category and are gradually ossified when growth is complete b) Symphyses (secondary cartilaginous joints) The secondary cartilaginous joints or symphyses are all in the midline of the body. The articular surfaces are covered by hyaline cartilage and the bones are held together by a plate of fibrocartilage. The bones are also united by ligaments which fuse with the fibrocartilage at the periphery and provide additional, flexible linkage A symphysis joint allows a limited degree of movement due to the compressibility of the Fibrocartilage and the degree of leverage available. These types of joints are of particular interest to the physiotherapist, as they occur frequently in the pelvis and spine. They are also common sites of injuries and problems which require physiotherapy intervention! 5 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Synovial joints Most of the joints in the body are classified as synovial type. These joints are freely moveable to varying degrees and reflect this in their characteristic features: a) The bony surfaces of the joint are in contact but not continuity and are normally covered by a glassy, friction-free substance known as articular hyaline cartilage. You will learn more about this substance in other modules. The function of hyaline articular is to provide a wear-resistant, low friction and lubricated surface which has both compressibility and elasticity and is able to accommodate the forces of compression and shearing that human movement creates. Hyaline cartilage is one of the most resilient substances in the human body – just think for a moment how tough and low friction this substance must be to avoid breaking down in the face of human movement. The thickness of the cartilage varies with the shape of the surface and the area of the body. In large joints, such as the hip, articular cartilage can be almost 1cm thick! Whereas it may only be 1mm thick in joints of the fingers, for example. Clinical comment Despite being a wonderful substance, with age, articular cartilage may show some signs of degeneration. The surface of the cartilage may start to become more ragged, creating friction. Changes in the ground substance of cartilage start to affect its water-holding properties, making it less resistant to strain. Once articular cartilage has been damaged, it cannot regenerate, it can only be repaired by a less effective form of fibrocartilage. Physiotherapists know this condition well – Osteoarthritis. It responds well to exercise and movement, but may require joint replacement surgery if too far progressed. b) The space between the bones is the joint cavity and contains a viscous fluid called synovial fluid. Synovial fluid is often a pale yellow colour, and is highly viscous. It is present only in small amounts, even in large joints, and effectively acts like the oil in an engine. Synovial fluid has two main functions: As a source of nutrition for the articular cartilage As a lubricant to increase joint efficiency and reduce wear Clinical comment In most joint injuries an excess of synovial fluid is produced so that marked swelling occurs. Restoration of the normal structure involves reabsorption of this fluid in the healing process and benefits from techniques such as ice and gentle movement c) The bones at a synovial joint are linked together by a fibrous capsule. A capsule consists of bands of tissue which form a sleeve around the joint – supporting and enclosing it but not interfering with the movement. Capsules vary in their structure. Some are a complete sleeve around the joint (such as the hip joint) whereas others are incomplete – instead being replaced by other structures such as ligaments and muscles (this is the case in the knee joint). The capsule is often perforated by blood vessels, nerves, and may also allow pouches of the synovial membrane to protrude from inside the joint. These are known as bursae, and act as cushions. We will discuss bursae in more depth when we come to the knee joint 6 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Articular Hyaline Cartilage of the elbow – in vivo – note the shiny, glassy surface to reduce friction A simple representation of a synovial joint, including joint cavity, cartilage and capsule Posterior hip joint capsule – in vivo – note the dense, white tissue (high proportion of collagen) Taken from “Human Anatomy – Color Atlas and Textbook” available on your reading list 7 Workbook 1: Introduction to Arthrology/Arthrology of the Hip d) Lining the joint capsule and the non-articular parts of the bones inside the capsule is the synovial membrane. The synovial membrane is formed of cells called synoviocytes – Type A synoviocytes are responsible from the removal of debris within the joint. Type B synoviocytes produce and secrete synovial fluid into the joint. Synovial membrane isn’t just found within synovial joints. It also lines structures such as bursae and tendon sheaths – synovial membrane occurs wherever human beings need to minimize friction between moving parts. Synovium has a rich blood supply and the vessels near the joint surface are another source of nutrition for articular cartilage (the others being the synovial fluid itself, and the underlying bone) Clinical comment The synovial membrane is the main target tissue for the inflammatory joint disease known as Rheumatoid Arthritis (RA) e) The bones are usually connected by a variable number of ligaments which provide the joint with additional support. A ligament is a structure which most commonly connects bone to bone. A tendon is a structure which most commonly connects muscle to bone. Ligaments are named accordingly to their position or attachment (e.g. the iliofemoral ligament of the hip connects the ilium and the femur) Ligaments can be capsular – as in they blend with the fibrous capsule or are simply thickenings of the fibrous capsule – or they can be extracapsular. Extracapsular ligaments often attach beyond the margins of the joint and are also called accessory ligaments. All ligaments share a basic function – to prevent excessive or abnormal movement at a joint, and prevent damage to a joint, without impacting normal movement f) Some synovial joints have specialised structures which reside within the capsule or joint cavity. These are known as intra-articular structures. They often have a special purpose, such as the important menisci of the knee, or the labrum of the hip. We will discuss these structures in more detail as we encounter them throughout the body. g) Movement is always possible at a synovial joint – that’s why they exist! – but it can vary from a little to a lot depending upon the location and purpose of the joint in question. The extent of movement at a synovial joint is determined by: The closeness and shape of the joint surfaces The nature and density of the surrounding soft tissue (including muscle tissue) The form and attachment of the ligaments surrounding the joint Movements can be simple gliding actions of one surface over another, or involve more complex rotational or angular movement. We will encounter simple movement of bones at the hip, but much more complex rolling, spinning and sliding movements when we get to the knee joint As a general rule, joints in the lower limb favour stability over mobility, whereas in the upper limb this relationship is reversed. Think of how much more mobile the joints of your hand are than the joints of your foot! 8 Workbook 1: Introduction to Arthrology/Arthrology of the Hip The “Close-pack” position All synovial joints have a position in which they are most stable. This is when the bony contact is highest between the bones, or when the ligaments and soft tissue surrounding the joint are at their most taut, or a combination of the two. This is known as the “close-pack” position The opposite situation – where the bony surfaces are in least contact, or where the soft tissue structures of the joint are most lax – is known as the “loose pack” position. It is important to understand the close pack position – particularly for joints of the lower limb – as this will give us the most stability when standing. It is an important consideration for designing exercises and rehabilitating our patients. Classification of Synovial Joints Synovial joints can be classified according to four criteria: a) Type – Is the joint Fibrous, Cartilaginous, or Synovial? Keep in mind that most joints we will study are synovial joints b) Complexity – joints can be classified according to three levels of increasing complexity: Simple – Two articular surfaces without any intervening structures (such as the hip joint) Compound – More than two articular surfaces without any intervening structures (such as the ankle joint) Complex – A joint which possess an intra-articular structure which intervenes between the articular surfaces (such as the knee joint) c) Freedom of movement – joints can be classified according to three levels of increasing freedom of movement: Uni-axial – movement can occur in one plane of movement only (such as the ankle joint) Bi-axial – movement can occur in two planes of movement (such as the knee joint) Multi-axial – movement can occur in three planes of movement (such as the hip joint) d) Description or shape – this final category is a descriptive illustration of the shape of the joint and its joint surfaces. Some examples of this type of classification are below: Ball and socket – such as the shoulder or hip Hinge – such as the ankle or joints of the toes Saddle – such as the 1st Carpometacarpal Joint at the base of the thumb This final category will make more sense when you’ve seen the joint surfaces and their shape Example – Hip joint The hip joint is classified as follows: Synovial – it possess a joint cavity, articular cartilage and a capsule/synovial membrane. It allows movement between two bones Simple – it is the joint between only two bony surfaces – the femur and the innominate bone of the pelvis – and has no intervening structures between these surfaces Multi-axial – the hip joint is a very mobile joint. It is capable of moving in 3 planes of movement (6 individual movements in pairs – Flexion/extension, Abduction/adduction, Medial/Lateral rotation) Ball and socket – it is formed of the hollow, concave acetabulum and the rounded, convex head of femur. This arrangement looks like a ball and socket joint and moves like one too. 9 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Arthrology of the Hip Joint Bony Landmarks Proximal End of Femur (Anterior View) 10 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Proximal End of Femur (Posterior View) 11 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Left Innominate (Lateral View) 12 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Remember - What is a Joint? A joint is defined as a place where two or more bones meet or articulate. There are 3 types of joint which vary in structure and function, the majority belong to the synovial classification (the other 2 types will be studied later). Remember, when studying any joint, the following format is suggested as a learning guideline: Classification of joint Bones involved in the articulation & features of the articular surfaces Arrangement of capsule & synovial membrane Ligaments Intra-articular structures Movements & limiting factors Activity 1 From your anatomy textbook, make notes that: 1. Identify the bones in articulation at the hip joint; and 2. Describe the shape and extent of the articulating surfaces. Remember - What is Cartilage? The cartilage in a synovial joint is usually articular hyaline cartilage, occasionally it may be fibrocartilage, for a bone which has undergone intramembranous ossification. Cartilage provides a low friction, wear resistant surface which has both compressibility and elasticity and is able to accommodate the forces of compression and shearing that weight bearing/muscle action generate. The thickness of the cartilage varies with the shape of the surface - on convex shaped surfaces it is thickest centrally and thins at the periphery; on concave surfaces the converse occurs. The nutrition for cartilage arises from the underlying cancellous bone, the synovial membrane and the synovial fluid. Activity 2 From your anatomy textbook, make notes that: 1. Briefly describe the arrangement of the articular cartilage at the hip joint. Remember - What is the Fibrous Capsule? The bones at the synovial joint are linked together by a fibrous capsule which consists of parallel and interlacing bundles of connective tissue forming a cuff around the joint. This surrounds the joint but does not interfere with the mobility because it is attached relatively loosely around the articular margins. The capsule is perforated by blood vessels and nerves, and may present with one or more apertures through which the lining membrane protrudes to form a pouch or sac. 13 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Activity 3 From your anatomy textbook, make notes that: 1. Describe the attachments of the fibrous capsule of the hip joint; 2. Identify areas where the capsule is thickest; and 3. Describe the special features of the direction of the fibres of the capsule. Remember - What is the Joint Cavity? The space between the bones is the joint cavity and contains a viscous fluid called synovial fluid. This is a clear or pale yellow, highly viscous fluid, and is normally present only in small amounts in the joint e.g. 0.5ml fluid can be aspirated from a normal knee joint. The synovium has two main functions: 1. Nutritive source for the articulate cartilage; and 2. Lubricant to increase joint efficiency. Remember – What is a Synovial Membrane? Lining the joint capsule and the non-articular parts of the bones inside the capsule is a synovial membrane. In many joints the membrane accumulates adipose or fatty tissue. The larger accumulations of fat are called articular fat pats. These form flexible cushions which fill potential spaces and irregularities within the joint cavity. They are contain nerve endings which inform the brain of the movement of the joint. The membrane is formed by synoviocytes. Type A cells remove debris from the joint. Type B cells produce and secrete synovial fluid. Some synoviocytes are involved in the immune system. Activity 4 From your anatomy textbook, make notes on: 1. The synovial membrane of the hip joint. Remember - What are Ligaments? Ligaments act to prevent unwanted movement at a joint. They connect bone to bone and can be part of the joint capsule, or separate from it. They are often named according to their location or according to the bones they connect. Ligaments which are separate from the joint capsule are often called accessory ligaments and they may act to stabilise several joints at once, particularly where the area of anatomy is quite small – such as in the foot or hand. Activity 5 From your anatomy textbook, make notes that: 1. Describe the position, attachments, shape and direction of fibres of each of the ligaments; and 2. Identify the main role of each of the capsular ligaments 14 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Remember - What are Intra-articular Structures? Many synovial joints have structures other than capsules and ligaments. These structures may take the form of fat pads, labrums, or fibrocartilaginous discs. Whatever they are, they have a special purpose within the joint in which they’re found. The hip joint has four of these structures: The Transverse Ligament (otherwise known as the transverse acetabular ligament) The Acetabular Labrum (fibrocartilaginous margin on the image below) The Ligamentum Teres (otherwise known as the Ligament of the Head of the Femur or Ligamentum Femoris Capitis in latin) The Acetabular Fat Pad (Fat in acetabular fossa on the image below) Activity 6 From your anatomy textbook, make brief notes that: 1. Describe the position, attachments and function of the transverse ligament 2. Describe the shape, extent, nature and function of the acetabular labrum; 3. Describe the position, attachments and function of the ligamentum teres; and 4. Describe the position and function of the acetabular fat pad. Acland’s Atlas of Human Anatomy and Visible Body In order to understand the arrangement of these structures in the human body you could access the electronic resources: Acland’s Atlas of Human Anatomy or Visible Body’s Human Anatomy Atlas. Both of these resources – and more – are available through your reading list or via the University Health Sciences Library Pages 15 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Movement at the Hip Joint All synovial joints have one position where the surfaces fit together precisely and where there is maximum contact between the surfaces. This is called the close-packed position. The opposite condition where the structures of the joint are most lax and the surfaces least in contact is called the loose-packed position. The movements possible at the hip joint are: Flexion / Extension; Abduction / Adduction; and Medial / Lateral Rotation. Activity 7 From your anatomy textbook, make notes that: 1. Describe the close-pack position and loose-pack position for the hip joint. 2. Make and compete your own movement table like the one shown below. Movement Normal range of movement Limiting factors (ROM) Flexion Extension Abduction Adduction Medial rotation Lateral rotation 16 Workbook 1: Introduction to Arthrology/Arthrology of the Hip Blood Supply Synovial joints have a rich blood supply, although some structures within them are poorly supplied by blood, such as cartilage. Each joint we will encounter throughout your studies is supplied by a complex network of arteries and veins. They are also supplied by a complex network of nerves for sensory information. We will not be venturing into too much detail regarding this unless it is clinically relevant. The blood supply of the hip joint is particularly important from a clinical perspective. Fractures of the hip – particularly to those of the neck of the femur – can disrupt the blood supply to the head of the femur and cause complications such as necrosis (or death) of the bony tissue Activity 8 From your anatomy textbook, or from other resources: 1. Identify the blood supply to the head of femur; and 2. Consider why a fracture to the neck of femur may disrupt this blood supply Hip Stability The stability of the hip joint is determined by: shape and angle of the bones; strong reinforcing ligaments; acetabular labrum; and muscles crossing the joint The direction of the femoral neck is also important in maintaining stability. Activity 9 From your anatomy textbook, or other resources, look up the following terms and make brief notes: Angle of inclination; and Angle of anteversion. Clinical Comment Increases in either of the 2 angles above, or damage to the capsular ligaments can lead to instability of the hip joint and a tendency to dislocation. 17