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Classification
Mason Classification
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- Type I: Nondisplaced fractures
- Type II: Marginal fractures with displacement
- Type III: Comminuted fractures involving the entire head
- Type IV: Radial head fractures associated with dislocation of the elbow (Not originally described by Mason)
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- Surgical Indications:
- Radial head excision can be considered if it is an isolated injury(i.e. there is not an Essex-Lopresti fracture).
- In the setting of an Essex-Lopresti fracture (radial head fracture, DRUJ disruption, and intraosseous membrane injury) proximal migration of the radius and a reduction in grip strength, valgus instability, posterolateral rotatory instability, heterotopic ossification, and post-traumatic arthritis of the ulnohumeral articulation may occur. Therefore it is recommended to either repair or replace the radial head.
- optimal scenarios include elderly, low energy injuries, no concomitant ligamentous injuries
- isolated, displaced two-part fractures are preferrably treated with ORIF
- Simple excision of fragments less than 1/3 of radial head may be considered if unrepairable.
- The radial head should be repaired or replaced when:
- There are associated soft tissue injuries at the elbow, including:
- Disruption of the anterior band of the MCL (secondary valgus instability)
- Essex-Lopresti Fracture (secondary longitudinal instability)
- Lateral collateral ligament (posterolateral rotatory instability; presence of radial head allows for proper tensioning of the LCL)
- Elbow dislocation (posterolateral rotatory instability, recurrent posterior dislocation)
- If there is a block to flexion/extension, or rotation
- Angulation more than 30o
- Depression of articular surface of more than 3 mm
- Greater than 1/3 of radial head involved
- There are associated soft tissue injuries at the elbow, including:
- Open reduction internal fixation is indicated for:
- Partial articular fractures with a single fragment
- Mason type 3 (complete articular) fractures with three or fewer fragments
Ref 12377912 . - ORIF is carried out in 70% of patients for whom it is intended due to the fact that there is often more comminution found intraoperatively than was apparent on preoperative radiographs. One must be prepared for a "plan B" replacement.
- Radial head replacement is recommended for:
- Tenuous fixation
- Mason type 3 fractures with more than three articular fragments
Ref 12377912 . - Advanced age, sedentary, smokers, patients on medications that impair healing (eg prednisone), significant medical comorbidities
- Irreparable cartilage injury
- patients with osteoporotic bone
- Radial head excision can be considered if it is an isolated injury(i.e. there is not an Essex-Lopresti fracture).
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- Closed reduction and possible pinning of the DRUJ
- ORIF vs. replacement of the radial head
- excision of the radial head is contraindicated due to longitudinal instability
- see the radial head fracture review page for more discussion
Techniques:
- Arthroplasty:
- Over- or understuffing the radiohumeral joint by 2.5 mm or more significantly alters elbow kinematics and radiocaptiallar pressure
Ref 15590846 . Overstuffing may lead to pain and early EJD, while undersuffing increases the risk of valgus instability. - The plane of the articular surface of the radial head is located 0.9mm proximal to the plane of the lateral articular surface of the coronoid
Ref 16443104 A visual lateral ulnohumeral joint gap seen intraoperatively is a reliable indicator of over-lengthening greater than 2mm. Radiographic asymmetry of the medial ulnohumeral joint is insensitive for detecting over-lengthening, as incongruity of ulnohumeral joint only occurs after over-lengthening of the radius by 6mm or more.Ref 19571097
- Over- or understuffing the radiohumeral joint by 2.5 mm or more significantly alters elbow kinematics and radiocaptiallar pressure
Figure: Overstuffed radial head replacement.
- voids caused by impacted fragments should be filled with cancellous autograft from the lateral epicondyle
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- Heterotopic ossification
- risk factors:
- extensive muscle damage
- neurotrauma
- revisions
- Prophylaxis modalities
- indomethacin
- radiation
- risk factors:
- radioulnar synostosis
- nonunion
- collapse
- DJD
- decreased range of motion
- loss of full extension most common
- Radial head overgrowth
- Premature physeal closure
- Avascular necrosis of the radial head
- Alteration in the carrying angle
- Neuromuscular problems (ulnar nerve problems with valgus)
References
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