1 Principles top
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Displaced bifocal fractures (11-B2) and fracture dislocations (11-B3) should be considered for replacement of the humeral head and neck, particularly in elderly patients with osteoporosis.
The chance of failure of fixation with conventional implants is high and hemiarthroplasty may be used as primary treatment. Hemiarthroplasty can also be the salvage treatement for cases of failed osteosynthesis attempts.
2 Removing the humeral head top
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Surgical technique
The deltopectoral approach is preferred for placing the prosthesis. Clavicopectoral fascia will be incised and anterior edge of coracoacromial ligament excised. Identification of the displaced components of the fracture is crucial: Heavy stay sutures are placed at the major and minor tubercle fragments at the attachment of the rotator cuff tendons. The head fragment is removed and preserved as a potential source of bone graft if required.
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Retrieving the head fragment
Great care should be taken when retrieving the head in fracture dislocations to avoid injury to the axillary artery and the brachial plexus. The arm is then adducted, extended, and externally rotated to facilitate preparation of the medullary canal in the shaft fragment.
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Preserving the lesser tuberosity
The lesser tuberosity should be detached from the head fragment for later reattachment to the prosthesis. A large bone cutter can be used for this purpose.
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The dotted line shows the cut.
3 Placement of the prosthesis top
Assessing version of prosthesis
After serial reaming of the medullary canal, proper head size and stem size are determined by templating and inserting trials. Appropriate height and version of the prosthesis are determined by assessing tuberosity and cuff tension after reduction of the trial prosthesis and reapproximation of the tuberosities and cuff.
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Placement of the prosthesis
Secure fixation of the prosthesis within the medullary canal requires polymethylmethacrylate cement. Drill holes are made on the proximal part of the shaft fragment before cementation.
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In order to create a stable joint and sufficient range of motion, it is essential to place the prosthesis in 10-20° retroversion (with the elbow in 90° flexion, and a neutral position between external and internal rotation).
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Reduction
After cementing the prosthesis in proper length and version, strong (non-resorbable) stay sutures over the tuberosities are used for their reduction to each other and to the shaft through the proximal drill holes, and secured to the fin of the prosthesis. The tuberosities should be placed under the prosthetic head to avoid subsequent impingement.
4 Closure top
Importance of prosthesis version
Proper stem size, head size, and height of prosthesis are crucial in achieving balance between stability and mobility.
Use long head of the biceps tendon as a landmark
The long head of the biceps tendon is a useful landmark to the rotator interval and it should be preserved throughout the procedure.
The lesser tuberosity may be pulled medially by the subscapularis and should be mobilized as a single bone / tendon unit to preserve blood supply.
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Closure
There should always be overlap between the tuberosity fragments and the humeral shaft.
Closure of the rotator cuff around the prosthesis and of the rotator interval should take place without undue tension.