Lesser Tuberosity Fractures

Lesser Tuberosity:

• Anterior projection of proximal humerus.
• Medial border of bicipital groove.
• Distal to anatomical neck.
• Smaller than greater tuberosity.

Relationships:

• Lateral: Bicipital groove (Biceps Long Head).
• Lateral to groove: Greater Tuberosity.
• Medial: Articular surface.

Review normal anatomy to identify subtle displacements.

Subscapularis Tendon:

• Primary internal rotator of shoulder.
• Anterior stabilizer of glenohumeral joint.
• Inserts broadly onto lesser tuberosity.
• Deforming force: Pulls fragment medially.

Biceps Tendon (Long Head):

• Runs in bicipital groove immediately lateral to LT.
• Retained by transverse humeral ligament.
• Can be incarcerated in fracture site.
• At risk during screw placement.

The proximity of the biceps tendon determines surgical risk zones.

Avulsion:

• Violent contraction of subscapularis (e.g., seizure).
• Resists posterior dislocation forces.

Displacement:

• Medial displacement due to muscle pull.
• Can creating a mechanical block against the glenoid rim.
• Limits internal rotation if healed in malposition.

Displacement direction is typically medial.

Based on Fragment Size & Displacement:

• Type I: Minimally displaced (less than 5mm), small avulsion.
• Type II: Displaced (greater than 5mm), large fragment involving articular surface.
• Type III: Comminuted fracture.
• Type IV: Associated with posterior dislocation.

This descriptive system aids in surgical planning.

Specific for Lesser Tuberosity:

• Type I (Avulsion): Small fragments, usually isolated.
• Type II (Fracture): Large fragments, often extend into head/neck.
• Key Factor: Size of fragment determines fixation method (anchor vs screw).

Ogawa is useful for fixation implant choice.

Proximal Humerus Specific:

• Incorporates lesser tuberosity as part of 4-part classification.
• 2-part Lesser Tuberosity: Isolated fracture.
• 4-part: GT + LT + Shaft + Head.
• Fracture-Dislocation: Associated with posterior dislocation.

Robinson classifies the overall proximal humerus injury.

Standard Series:

• True AP (Grashey).
• Scapular Y.
• Axillary View (Essential).

Findings:

• AP: Fragment often superimposed on head (double density) or seen medially.
• Axillary: Shows profile of lesser tuberosity anteriorly. Confirms glenohumeral reduction.
• Scapular Y: Helps rule out dislocation.

Standard series is usually sufficient for initial screening.

Indications:

• Confirm diagnosis (often missed on X-ray).
• Assess fragment size and displacement.
• Determine comminution.
• Pre-operative planning (screw vs anchor).

Findings:

• Exact displacement measurement.
• Bicipital groove involvement.
• Reverse Hill-Sachs lesion (if prior dislocation).

CT is the gold standard for lesser tuberosity assessment.

Indications:

• Evaluating tendon integrity (subscapularis tear vs avulsion).
• Biceps tendon pathology.
• Labral pathology.
• Chronic pain.

Role:

• Defines extent of soft tissue injury.
• Assessing reparability of tendon.

MRI is reserved for soft-tissue evaluation.

Indications:

• Displacement less than 5mm.
• Minimally displaced.
• Low demand patient.
• Fragment does not block motion.

Protocol:

• Sling immobilization for 4-6 weeks.
• Passive external rotation restricted (protect subscap) usually to neutral.
• Active internal rotation avoided for 6 weeks.
• Elbow/wrist/hand ROM immediately.
• Progressive strengthening after 6-8 weeks.

Close radiographic follow-up is required to ensure no late displacement.

Indications:

• Displacement greater than 5mm.
• Mechanical block to rotation.
• Intra-articular extension.
• Associated with open reduction of posterior dislocation.
• Biceps tendon incarceration.

Options:

• Open Reduction Internal Fixation (ORIF).
• Excision (for small/comminuted fragments causing block).
• Suture Anchor repair (preferred for small/comminuted).
• Screw fixation (large fragments).
• Arthroplasty (if head destroyed/Reverse Hill-Sachs large).

Surgical strategy depends on fragment size and bone quality.

Deltopectoral Approach:

• Standard approach for lesser tuberosity.
• Position: Beach chair.
• Incision: Coracoid to axillary fold.
• Plane: Pectoralis major (medial) and Deltoid (lateral).
• Cephalic vein: Retract laterally with deltoid.
• Expose clavipectoral fascia, identify conjoined tendon.

Adequate exposure is critical for anatomical reduction.

Screw Fixation:

• Identify fragment and biceps tendon (medial to groove).
• Reduce fragment anatomically.
• Provisional K-wire.
• 4.0mm Cannulated Screws (1 or 2).
• Danger: Avoid penetrating articular surface or bicipital groove.
• Washer can be used to prevent pull-through.

Screws provide rigid columnar support.

Suture Anchor Repair:

• Fragment too small for screws or comminuted.
• Place suture anchors in fracture bed (humeral footprint).
• Pass sutures through subscapularis tendon/fragment interface.
• Secure knot (Suture bridge technique or simple mattress).
• Biomechanically strong and avoids hardware prominence.

Suture constructs are ideal for osteoporotic bone.

Indication:

• Chronic malunion causing block.
• Small piece blocking reduction.
• Late presentation (greater than 6 months).

Technique:

• Excise bony fragment.
• Repair subscapularis tendon to bone (transosseous or anchors).
• Ensure smooth motion arc.

Excision prevents future impingement.