Accessory Joint Play

Classification

Element	Detail
Category	Non-Swedish — Joint Mobilization
Subcategory	Accessory movement restoration (glides, spins, rolls)
FOMTRAC	PC 3.2o
Fritz Method	Joint movement (accessory motion assessment and restoration)

Purpose

Restore non-voluntary accessory movements (glides, spins, rolls) that are prerequisite for normal physiological ROM
Assess joint function by testing accessory motion quality and quantity
Normalize joint mechanics when physiological ROM is limited by accessory motion restriction

Mechanism

Every physiological joint movement (flexion, extension, abduction, etc.) requires concurrent accessory movements at the articular surface. When you flex your knee, the tibial plateau does not simply hinge — it simultaneously glides anteriorly on the femoral condyles. If this anterior glide is restricted (due to capsular adhesion, fibrosis, or immobilization), full knee flexion becomes impossible regardless of muscle length or flexibility. Accessory joint play testing identifies WHICH accessory motion is restricted, and accessory mobilization restores it. The convex-concave rule governs the relationship between physiological and accessory movements:

Convex surface moving on concave (e.g., humeral head on glenoid): the accessory glide occurs in the OPPOSITE direction to the physiological movement
Concave surface moving on convex (e.g., tibial plateau on femoral condyles): the accessory glide occurs in the SAME direction as the physiological movement

Restoring the correct accessory glide restores the physiological movement it supports.

Indications

Joint ROM limitation that persists after muscular restrictions have been addressed (muscle length is normal but joint ROM is still limited)
Non-capsular pattern of joint restriction (suggesting accessory motion loss rather than capsular fibrosis)
Post-immobilization stiffness (accessory motions are the first to be lost during immobilization)
Specific movement loss that correlates with a specific accessory glide restriction
Assessement: accessory play testing is essential for determining whether a ROM limitation is muscular, capsular, or due to accessory motion loss

Contraindications

Joint instability or hypermobility (accessory motions are already excessive)
Acute fracture
Active joint infection
Malignancy near the joint
Acute ligament rupture
Rheumatoid arthritis in acute flare
Severe osteoporosis (fracture risk)

Effects

Immediate:

Restored accessory glide, spin, or roll at the affected joint
Increased physiological ROM (the movement that depends on the restored accessory motion)
Mechanoreceptor stimulation (pain modulation)
Improved joint biomechanics

Cumulative (over multiple sessions):

Normalized joint mechanics
Progressive restoration of full ROM
Reduced compensatory movement patterns
Improved joint nutrition through normalized articular surface contact

Risks and Side Effects

Post-treatment soreness (24-48 hours) if aggressive mobilization is applied
Joint irritation if incorrect direction or excessive force is used
Hypermobility if applied to joints that already have excessive play
Aggravation if applied during acute inflammation

Common errors:

Not stabilizing the proximal bone (both bones move, so no accessory motion is produced)
Applying the glide in the wrong direction (violating the convex-concave rule)
Confusing passive ROM with accessory play (ROM = physiological movement; accessory = non-voluntary joint surface movement)
Testing accessory play with the joint in close-packed position (must be in resting position)
Applying mobilization without first assessing which specific accessory motion is restricted

Expected Outcomes

Short-term (same session):

Restored accessory motion on reassessment
Immediate improvement in the associated physiological ROM
Client reports easier or smoother movement

Medium-term (over 3-6 sessions):

Sustained accessory motion restoration
Full ROM recovery in the physiological movement
Normalized joint biomechanics

Execution

Assessment (Accessory Play Testing)

Step	Detail
1. Position	Joint in RESTING (loose-packed) position
2. Stabilize	Fix the proximal bone firmly
3. Test glides	Apply a translatory force (anterior, posterior, medial, lateral) to the distal bone; assess excursion and end-feel
4. Test spin	Rotate the distal bone around its long axis; assess excursion
5. Test roll	(Usually assessed functionally rather than manually)
6. Compare bilaterally	Test the same joint on both sides; compare excursion and end-feel
7. Grade	Hypomobile (restricted), normal, or hypermobile

Treatment (Accessory Mobilization)

Step	Detail
1. Identify restriction	From assessment: which specific accessory motion (direction) is restricted?
2. Position	Joint in resting position
3. Stabilize	Fix the proximal bone
4. Direction	Apply the convex-concave rule to determine the correct glide direction for the restricted physiological movement
5. Mobilize	Apply Grade I-IV oscillations or sustained stretch IN THE RESTRICTED ACCESSORY DIRECTION
6. Duration	30-60 seconds per set, 3-5 sets
7. Reassess	Re-test both accessory play and physiological ROM

Parameters

Parameter	Range	Clinical Reasoning
Joint position	Resting (loose-packed)	Maximum capsular laxity allows maximum accessory motion
Grade	I-IV (match to clinical presentation: pain vs. stiffness)	Grade I-II for painful joints; Grade III-IV for stiff joints
Direction	Per convex-concave rule	Incorrect direction will not restore the target physiological movement
Force	Gentle to moderate (assess joint reactivity first)	Start gentle; increase based on tissue response
Bilateral comparison	Always	The unaffected side provides the reference for normal play

Clinical Notes

The convex-concave rule in practice:
Shoulder (glenohumeral): Humeral head is convex → glide OPPOSITE to restricted movement. Restricted ER? → Anterior glide. Restricted abduction? → Inferior glide.
Knee (tibiofemoral): Tibial plateau is concave → glide SAME direction as restricted movement. Restricted flexion? → Posterior glide. Restricted extension? → Anterior glide.
Elbow (humeroulnar): Ulna is concave → glide SAME direction. Restricted flexion? → Anterior glide.
Accessory play vs. passive ROM: This is a fundamental distinction. Passive ROM tests how far the joint moves through its physiological range (flexion, extension, etc.). Accessory play tests the non-voluntary movements at the articular surface (glides, spins, rolls). A joint can have full passive ROM but restricted accessory play (compensating through adjacent segments), or restricted ROM caused specifically by accessory motion loss.
Clinical pearl: Accessory play assessment is the key diagnostic tool for determining whether a ROM limitation is muscular or articular. If muscle length tests are normal but ROM is still limited, test accessory play — the restriction is likely at the joint surface. This distinction determines whether you use MET/stretching (muscular) or mobilization (articular).

Verbal Script

"I'm going to test the small movements that happen inside your joint — movements you can't do on your own. I'll be sliding your [bone] in different directions while I hold the other bone still. You'll feel a gentle pushing or sliding sensation. This tells me exactly what's limiting your movement."

Distinguishing Features

Feature	Accessory Joint Play	Passive ROM
Movement type	NON-VOLUNTARY (glides, spins, rolls at the articular surface)	PHYSIOLOGICAL (flexion, extension, abduction — movements the client can do)
Client ability	Client CANNOT perform these movements voluntarily	Client CAN perform these movements actively
What it tells you	Quality and quantity of articular surface motion	Overall joint range through a physiological arc
Treatment implication	Restriction → joint mobilization	Restriction may be muscular (MET/stretching) OR articular (mobilization) — further testing needed
Joint position for testing	Resting (loose-packed)	Varies (depends on the movement being tested)

Feature	Accessory Joint Play	Joint Traction
Direction	Parallel to joint surface (translates)	Perpendicular to joint surface (separates)
Effect	Restores specific directional accessory motion	Decompresses; stretches capsule uniformly
Specificity	Targets one direction at a time	Non-directional (entire capsule)

Key Takeaways

Accessory joint play refers to the non-voluntary glides, spins, and rolls at articular surfaces that must occur for normal physiological ROM — they cannot be performed actively by the client
The convex-concave rule determines glide direction: convex moving = glide opposite; concave moving = glide same direction as restricted physiological movement
Accessory play assessment is the key tool for distinguishing articular from muscular ROM limitations — if muscle length is normal but ROM is limited, test accessory play
Always test in the resting (loose-packed) position; always compare bilaterally
Distinct from passive ROM (which tests physiological movement) and from traction (which separates surfaces rather than translating them)