Osteokinematics is the study of bone movement, while arthrokinematics is the study of joint surface movement. Both are branches of biomechanics that describe how the body moves.

Definitions

Osteokinematics: Movement between two bones (flexion/extension, IR/ER)
Arthrokinematics: Movement of joint surfaces, such as roll, glide, spin - such movements are used to improve the range of motion
Rule of convex surface moving on a fixed concave surface: Roll and glide occur in opposite directions to allow for motion to occur - movement of distal and proximal segments are in opposite directions
Rule of the concave surface moving on a fixed convex surface: Roll and glide occur in the same direction to allow for motion to occur - movement of distal and proximal segments is in the same direction

Shoulder (Convex on concave rule)

Flexion: Roll anterior, slide posterior
Horizontal adduction: Roll anterior, slide posterior
Internal rotation: Roll anterior, slide posterior
Extension: Roll posterior, slide anterior
Horizontal abduction: Roll posterior, slide anterior
External rotation: Roll posterior, slide anterior
Abduction: Roll superior, slide inferior

Elbow (Concave on convex rule)

Flexion: Roll anterior, slide anterior
Extension: Roll posterior, slide posterior

Wrist (Convex on concave rule)

Flexion: Roll anterior, slide posterior
Extension: Roll posterior, slide anterior
Radial deviation: Roll radial, slide ulnar
Ulnar deviation: Roll ulnar, slide radial

Hip (Convex on concave rule)

Flexion: Roll anterior, slide posterior
Extension: Roll posterior, slide anterior
Adduction: Roll medial, slide superior
Abduction: Roll lateral, slide inferior
Internal rotation: Roll medial, slide posterior
External rotation: Roll lateral, slide anterior

Knee (Concave on convex rule)

Flexion: Roll posterior, slide posterior
Extension: Roll anterior, slide anterior

Ankle (Convex on concave rule)

Dorsiflexion: Roll anterior, slide posterior
Plantarflexion: Roll posterior, slide anterior
Supination/Inversion: Roll medial, slide lateral
Pronation/Eversion: Roll lateral, slide medial

Joint mobilization

Joint mobilization is a manual therapy technique that involves moving a joint passively to improve its range of motion and reduce pain. The above arthrokinematics chart is how the therapist will perform joint mobilizations at each joint.

Indications for joint mobilization

Pain
Muscle spasm
Joint hypomobility
Functional limitation at joint ROM

Precautions for joint mobilization

Joint hypermobility
Joint effusion
Inflammation

Contraindications for mobilization

Malignancy
Fracture
Bone disease
Rheumatoid arthritis (RA)
Individuals on anticoagulants

The grades of joint mobilization (Maitland approach)

Grade I - small amplitude movement at the beginning of the joint’s range of motion
- Typically used in acute phases for pain management
Grade II - large amplitude movement within the joint’s range, not reaching the limit
- Typically used, like Grade I, to manage pain
Grade III - large amplitude movement reaching the limit of the joint’s range
- Typically used in sub-acute phases for return of range of motion
Grade IV - small amplitude movement at the end of the joint’s range
- Used to increase tissue extensibility, reduce stiffness, and improve range of motion

Joint positions

Joint position or mechanics are ways to define the joint’s level of stability. An open position (also called loose-packed position or resting position) refers to a joint position where the articulating surfaces have minimal contact, ligaments are relaxed, and the joint has the least stability. A closed position (also called a close-packed position) is when the joint surfaces are fully congruent, ligaments are maximally taut, and the joint is at its most stable position. The open positions are those in which joint mobilizations will occur.

Resting and closed positions

Sternoclavicular
- Resting position: arm resting at the side
- Closed position: arm maximally elevated
Acromioclavicular
- Resting position: arm resting at the side
- Closed position: arm abducted to 90 degrees
Glenohumeral
- Resting position: 40-55 degrees abduction; 30 degrees of horizontal adduction
- Closed position: maximum abduction and external rotation
Humeroulnar (elbow)
- Resting position: 70 degrees flexion, 10 degrees supination
- Closed position: full extension and supination
Humeroradial (elbow)
- Resting position: full extension and supination
- Closed position: 90 degrees flexion and 5 degrees supination
Proximal radioulnar (forearm)
- Resting position: 70 degrees flexion and 35 degrees supination
- Closed position: 5 degrees of supination
Distal radioulnar (forearm)
- Resting position: 10 degrees of supination
- Closed position: 5 degrees of supination
Radio/ulnarcarpal
- Resting position: neutral with slight ulnar deviation
- Closed position: full extension with radial deviation
Hip
- Resting position: 30 degrees flexion, 30 degrees abduction, and slight lateral rotation
- Closed position: full extension, abduction, and internal rotation
Knee
- Resting position: 25-degree flexion
- Closed position: full extension and external rotation
Talocrural (ankle/foot)
- Resting position: mid inversion/eversion and 10 degrees plantar flexion
- Closed position: full dorsiflexion
Subtalar (ankle/foot)
- Resting position: midway between inversion and eversion
- Closed position: full inversion
Midtarsal (ankle/foot)
- Resting position: midway between inversion and eversion
- Closed position: full supination
Tarsometatarsal (ankle/foot)
- Resting position: midway between supination/pronation
- Closed position: full supination

Capsular patterns

A capsular pattern is a specific limitation in the range of motion that indicates joint tightness or inflammation. It’s a combination of pain and limited movement that can occur in any joint that’s controlled by muscles. Certain pathologies, as denoted in later chapters, will be defined specifically from the capsular pattern that exists within the joint.

Below are capsular patterns of joints

Glenohumeral
- External rotation, abduction, internal rotation
Sternoclavicular
- Shoulder elevation
Acromioclavicular
- Shoulder elevation
Humeroulnar
- Flexion, extension
Humeroradial
- Flexion, extension
Proximal radioulnar
- Pronation, supination
Distal radioulnar
- Pronation, supination
Wrist
- Flexion, extension
Hip
- Flexion, internal rotation, abduction
Knee
- Flexion
Tibiofibular (proximal and distal)
- Equal limitations of flexion and extension

End feels of joints

End feel of a joint refers to the sensation a clinician feels when they reach the limit of a joint’s passive range of motion during an assessment, essentially describing the quality of tissue resistance at the end of movement. Normal end feels are characterized as soft, firm, or hard depending on the tissue that limits the motion. By evaluating the end feel, a clinician can determine if a joint is moving within its normal range and identify potential abnormalities like inflammation, ligamentous damage, or joint stiffness.

Below are the characteristics of normal end feels

Soft end feel:
- Occurs when soft tissues, such as muscles, meet, often felt as a cushioned sensation (example: knee flexion)
Firm end feel:
- A more defined resistance, usually due to the tension of ligaments or joint capsule at the end of range (example: wrist flexion)
Hard end feel: (Bony)
- A sudden, abrupt stop to movement, typically caused by bone-on-bone contact (example: elbow extension)

Pathological end feels are those indicating there has been injury to the joint, tendon, or muscle.

Pathological end feels that may be present

Springy block
- A rebounding sensation is often associated with internal joint derangements, like a torn meniscus
Empty end feel:
- Significant pain experienced before reaching the end of the range of motion, usually indicating acute inflammation
Boggy or soft end feel
- A “mushy” sensation due to joint effusion or edema, typically seen in acute injuries
Hard end feel
- Excessive bony resistance beyond the normal endpoint, potentially from osteoarthritis or bone spurs
Muscle spasm end feel
- Sudden, sharp resistance due to muscle guarding, causing pain and limiting movement

Phases of healing and types of musculoskeletal interventions

The musculoskeletal system has three stages in which disease processes can be classified: 1. Acute or inflammatory phase, 2. Subacute or proliferative phase, and 3. Chronic phase.

The acute phase refers to the initial inflammatory stage following an injury, characterized by pain, swelling, and redness. The acute phase typically lasts for 3-7 days.

The subacute phase is the subsequent repair stage where new tissue begins to grow, and the body starts to rebuild damaged structures, usually occurring a few days after the initial injury and lasting several weeks.

The chronic phase is not a natural part of healing but occurs when healing has stopped in either the acute or subacute phase. Injuries are classified as chronic if no progression past the acute or subacute phases for greater than 3 months.

Interventions in each phase

PTA role: The supervising PT establishes and modifies the plan of care. As the PTA, you carry out the plan within each phase and report changes in the patient’s status back to the PT rather than independently re-evaluating or changing the intervention plan.

Acute phase

Pain management
Maitland mobilizations - grade I or II
Joint protection to prevent further injury
Edema management
Therapeutic exercise: 40%-60% of 1 rep max in pain-free ROM
Stretching is contraindicated

Subacute phase

Avoid overuse pain, as resting pain should be at a minimum
Stretching is initiated to aid in restoring the full range of motion
Endurance training will begin
Resistance training will begin
Postural and biomechanical education

Chronic phase

Identify healing phase (acute vs subacute) and make intervention selections based on phase of healing
Emphasize postural and biomechanical strengthening
Improve flexibility and joint alignment

Osteokinematics and arthrokinematics

Osteokinematics: bone-on-bone movement (flexion/extension, IR/ER)
Arthrokinematics: joint surface movement (roll, glide, spin) used to improve ROM
Convex-on-concave rule: roll and glide occur in opposite directions
Concave-on-convex rule: roll and glide occur in the same direction

Joint-specific roll/glide patterns

Shoulder & wrist & hip & ankle: convex-on-concave rule (roll/slide opposite)
Elbow & knee: concave-on-convex rule (roll/slide same direction)
Key examples:
- Shoulder flexion: roll anterior, slide posterior
- Elbow flexion: roll anterior, slide anterior
- Hip flexion: roll anterior, slide posterior
- Knee flexion: roll posterior, slide posterior
- Ankle dorsiflexion: roll anterior, slide posterior

Joint mobilization

Manual technique to passively move joint, improve ROM, reduce pain
Indications: pain, muscle spasm, hypomobility, functional ROM limits
Precautions: hypermobility, effusion, inflammation
Contraindications: malignancy, fracture, bone disease, RA, anticoagulant use

Maitland grades of mobilization

Grade I: small amplitude, beginning of range — acute pain control
Grade II: large amplitude, mid-range — pain management
Grade III: large amplitude to end range — sub-acute, restore ROM
Grade IV: small amplitude at end range — increase tissue extensibility/stiffness

Joint positions

Open/loose-packed position: minimal surface contact, relaxed ligaments, least stable — used for mobilizations
Closed/close-packed position: maximal congruency, taut ligaments, most stable
Key resting positions:
- Glenohumeral: 40-55° abduction, 30° horizontal adduction
- Hip: 30° flexion, 30° abduction, slight lateral rotation
- Knee: 25° flexion
Key closed positions:
- Glenohumeral: max abduction + external rotation
- Hip: full extension, abduction, internal rotation
- Knee: full extension + external rotation

Capsular patterns

Specific ROM limitation pattern indicating joint tightness/inflammation
Glenohumeral: ER, abduction, IR (in that order of restriction)
Hip: flexion, internal rotation, abduction
Knee: flexion only
Wrist/humeroulnar/humeroradial: flexion, extension

End feels of joints

Normal end feels:
- Soft: tissue approximation (e.g., knee flexion)
- Firm: ligament/capsule tension (e.g., wrist flexion)
- Hard (bony): abrupt bone-on-bone stop (e.g., elbow extension)
Pathological end feels:
- Springy block: internal derangement (torn meniscus)
- Empty: pain before end range, acute inflammation
- Boggy/soft: effusion/edema
- Hard: excessive bony block (osteoarthritis, spurs)
- Muscle spasm: sudden sharp resistance from guarding

Phases of healing and interventions

Acute/inflammatory phase: 3-7 days; pain, swelling, redness
Subacute/proliferative phase: days to weeks after injury; tissue repair/rebuilding
Chronic phase: healing stalled >3 months past acute/subacute
PTA role: implement PT’s plan of care, report status changes, do not independently modify plan

Acute phase interventions

Pain and edema management
Maitland grade I or II mobilizations
Joint protection
Therapeutic exercise at 40-60% of 1RM, pain-free ROM
Stretching contraindicated

Subacute phase interventions

Minimize overuse/resting pain
Begin stretching to restore full ROM
Initiate endurance and resistance training
Postural/biomechanical education

Chronic phase interventions

Identify underlying healing phase (acute vs subacute) to guide treatment
Emphasize postural/biomechanical strengthening
Improve flexibility and joint alignment

Next | 5.4 Upper extremity anatomy

Joint mechanics and phases of healing

Osteokinematics and arthrokinematics