Instabilities around elbowDr Vishnu raja A

Elbow joint

Joint Capsule

Ligamentous complex

Lateral ligamentous complex – Radial collateral ligament , Annular ligament , LUCL

Medial ligamentous structures - MCL

Medial collateral ligament

Stronger than LCL.

3 bundles – Anterior , Posterior, Transverse

Principle stabiliser of elbow -

Annular ligament

Radial collateral ligament

Lateral ulnar collateral ligament

Stability of elbow joint

Static and dynamic stabilizers confer stability to the elbow .

STATIC STABILISERS

PRIMARY Ulnohumeral jointLcl complexMCL complex

SECONDARYRadiocapitellar joint .CapsuleCommon flexor and extensor origin .

Dynamic stabilisers includes muscles crossing elbow joint anconeusbrachialisTriceps They provide compressive stability.

Secondary varus stability  •LCL, anconeus, and lateral capsule 

Traumatic types A. Acute elbow dislocation .

Simple Complex ( associated with fractures )

B. Chronic / Recurrent . Lateral elbow instability Medial elbow instability Recurrent elbow dislocation Chronic non reduced elbow dislocation

Non-traumatic types Rheumatoid arthritis Connective tissue disorders Gouty arthritis

Mechanism of acute traumatic elbow dislocation Fall on an outstretched hand

• Extension of elbow till contact• Upon contact flexion begins

• External rotation of the UHJ (triceps effect)

• Internal rotation of humerus against forearm

• Valgus moment (mechanical axis)

Combination of ER., valgus and axial compression……. Instability

Biomechanics O Driscoll and collaegues described - 1966 Sequential disruption - Capsular and ligamentous structures

The circle of Horii describes a pattern of soft tissue injury,

a)Stage 1 is a disruption of the LUCL – PLRI .

b) Stage 2 is disruption of the anterior and posterior capsule, which allows the elbow to become “perched”.

c) Stage 3 includes injury is to the medial side of the elbow. 3a the MCL is intact, 3b the anterior band of the MCL is disrupted, 3c the entire distal humerus soft tissue is stripped leading to gross instability of the joint so it is stable only at greater than 90 degree of flexion.

Elbow instabilitiesAccording to O Driscoll

Timing Acute, chronic , recurrent .Articulations involved - The hinge joint (humerus, radius, and ulna) ,the proximal radioulnar joint combination .Direction of displacement – Posterolateral rotatory instability , Anterior , valgus , varus.

Degree of displacement/soft tissue injury

Simple or complex - associated fractures.

Postero lateral rotatory instability Most common type .

Mechanism – Traumatic – following a dislocation . Iatrogenic Secondary to cubitus varus - malunited fracture.- Condition – radius and ulna rotates externally in relation to distal humerus leading to posterior subluxation / dislocation of radial head

Constraints to PLRI – LCL complex , coronoid and radial head .

LCL complex – is the primary constraint to posterolateral rotatory instability, limiting external rotation of the radius and ulna relative to the humerus. Lateral ulnar collateral ligament was considered the main constraint to posterolateral rotatory instability

Radial head - radial head is a significant constraint to posterolateral rotatory instability, contributing to stability by providing osseous congruency and tensioning the lateral ligament complex.

Excision may slacken and de-function the lateral ligament complex .

Following excision of the radial head in human cadavers, Jensen et al 25 found a 7.1˚ mean increase in external rotatory laxity of the forearm .

Schneeberger, Sadowski and Jacob 26 reported doubling of the external rotatory laxity despite intact medial and lateral ligaments

Suggested the development of posterolateral rotatory instability in patients in whom the radial head was excised following a comminuted fracture – REPLACE / CONSERVE – COMMINUTED

CORONOID PROCESS - elbow stabiliser, acting as a constraint to posterior ulnohumeral displacement on axial and varus forces .

Regan and Morrey classification – Type 1 did not increase posterolateral laxity, but stage II fractures with 50% reduction in coronoid height resulted in a 28% increase .

When combined with excision of the radial head, loss of 30% of coronoid height 26 fully destabilised cadaver elbows, leading to ulnohumeral dislocation even in the presence of intact ligaments.

PresentationPresentation•Symptoms

• Pain is the primary symptom• PLRI patients complain of mechanical symptoms (clicking, catching, etc.)

with elbow extension, e.g. pushing off from arm of chair

Symptoms are often brought on by activities such as pushing up from a chair or doing press-ups, which place the elbow in an unstable position of external rotation of the forearm with valgus and axial loading of the elbow

CLINICAL DIAGNOSIS

Table I. Clinical tests for posterolateral rotatory instability of the elbow

Lateral pivot-shift test .

Patient supine, affected limb overhead. With forearm supinated, valgus and axial loadingapplied, elbow is flexed from full extension. In posterolateral rotatory instability as theelbow is flexed the radial head subluxes/dislocates, seen as an osseous prominence posterolaterally.With flexion beyond 40° the radial head suddenly reduces with a palpableand visible clunk. The test may also be done starting with the elbow flexed and thenextending, reversing the above sequence. The test is best done under general anaesthesiafor radial head dislocation and relocation to be seen.

Posterolateral rotatory drawer test

Patient supine, affected limb overhead, elbow flexed 40°. Anteroposterior force is appliedto the radius and ulna with the forearm in external rotation. This aims to sublux the forearmaway from the humerus on the lateral side, pivoting on the intact medial ligaments.Under general anaesthesia the radial head is seen dislocating, whereas with the patientawake apprehension occurs.

Table-top relocation test

Patient performs a press-up on the edge of a table using one arm, with the forearm in supination. In the presence of instability, apprehension occurs at about 40˚ flexion. The manoeuvre is repeated while the examiner’s thumb

presses on the radial head,preventing subluxation. The test is positive if thumb pressure relieves apprehension.

Active floor push-up sign

Patient pushes off the floor with elbows flexed 90˚, forearms supinated and arms abducted. The test is positive if apprehension or radial head dislocation occurs as the elbow is extended.

Chair sign Patient seated with elbows flexed 90°, forearms supinated and arms abducted. Patient tries to rise from the chair pushing down only with the arms. The test is positive if apprehension or radial head dislocation occurs with elbow extension.

Further investigations can contribute to the diagnosis,value is often limited. Plain radiography may show an avulsion fracture of the origin or insertion of the lateral ligament

complex ,demonstrate the integrity of the radial head, coronoid process and capitellum,and the presence of degenerative changes.

Stress x-ray views are important.

Value of MRI in the diagnosis of posterolateral rotatory instability remains controversial. Arthroscopic diagnosis:

Shows widening of lateral edge of the joint, elongation of lateral ligament.

MANAGEMENT Depends upon severity of symptoms . Avoiding provocative manoeuvres and bracing to limit supination and

valgus loading.

Surgery aims at- Re-attaching, retensioning or reconstructing the lateral ligament complex .- Dealing with bone deficiency of the radiocapitellar and ulnohumeral articulation by replacement of the radial head or coronoid reconstruction, and correcting any varus deformity of the humerus by osteotomy.

Coronoid fractures –

Cerclage wire or No. 5 suture through ulna drill holes for Type I injuriesORIF with retrograde cannulated screws or plate for Type II or III injuriesORIF with buttress plate fixation or pins and lateral ligament repair for posteromedial rotatory instability 

Radial head fractures-

radial head ORIF vs. arthroplasty•radial head arthroplasty indicated for comminuted radial head fracture 

•use of modular prosthesis preferable•sizing based on fragments removed from elbow•implant should articulate 2mm distal to the tip of the coronoid process•radial head resection without replacement is not used

•it <25% head damaged or fragments not reconstructable and nonarticulating, can excise fractured portion if elbow stable (rarely indicated)

•radial head ORIF indicated if non comminuted with good bone stock and fracture involves < 40% articular surface •1.5, 2.0, or 2.4mm countersunk screws 

•plating if necessary; 2.0 plates cause minimalloss of motion even when placed on radial neck

LCL repair / reconstruction Standard posterior approach to elbow – raising subcutaneous flaps. Preferable – aces to medial and lateral structures.

Ligament avulsions, most commonly from the humeral attachment, were repaired by reinsertion through bone tunnels using heavy non-absorbable sutures .Ligamentous laxity was addressed by overlapping and advancement of the ligament and capsule.Ligament reconstruction done with autograft of palmaris longus , use of triceps fascia, semitendinosus, gracilis, plantaris,tendo Achillis, and synthetic mersilene .

PMRI, Valgus instabity , surgical techniques -2