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Duke Orthopaedics
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Wheeless' Textbook of Orthopaedics

Radioulnar Synostosis



- Congenital Synostosis:
    - discussion:
           - occurs due to a defect in longitudinal segmentation at the 7th week of development;
           - autosomal dominant inheritance in some cases but often occurs sporatically;
           - bilateral in 60% (most common in males);
           - proximal 1/3 of forearm is most common site of bony union, and the forearm is pronated (avg 30 deg);
    - non operative treatment:
           - patients with a unilateral deformity or with a bilateral deformity & minimal pronation do not need surgery;
           - majority of patients w/ bilateral osseous radioulnar synostosis function adequately despite forearm position;
    - surgical treatment:
           - surgery is rarely indicated for this condition, except for severe pronation deformities (more 60 deg of pronation)
           - resection and interposition procedures fail, and the bridge regrows;
           - in pts w/ severe bilateral hyperpronation, osteotomy of nondominant extremity, to create supination, is indicated.
           - derotational osteotomy through the area of synostosis is recommended, placing one side in 10 to 20 degrees of pronation and the other forearm in a neutral position or slight supination for function;
    - references:
           Congenital proximal radio-ulnar synostosis. Natural history and functional assessment.
           Congenital Proximal Radioulnar Synostosis: Treatment with the Ilizarov Method.
           Congenital radioulnar synostosis.



- Traumatic Synostosis:
    - see discussion of hetertopic ossification and hetertopic ossification of the elbow;
    - discussion:
           - may arise from posterior frx dislocation of the elbow, Monteggia frx dislocation, traumatic rupture of the distal triceps, both bones forearm frx, or from isolated radial head frx;
                  - often these patients have undergone previous surgery;
           - exam findings: absence of forearm pronation and supination;
           - in some patients the hetertopic ossification will extend into the elbow joint which will limit flexion;
    - management:
           - traumatic synostosis is amenable to surgical excision;
           - timing of excision:
                  - traditionally, it has been recommended that hetertopic bone not be excised until there has been maturation (as judge by bone scan or serum alk phos);
                  - this has been challenged by Jupiter et al 1998, who noted no ill effects from excision of synostosis at 6-12 months post injury;
           - surgical approach:
                  - often the synostosis is amenable to excsion via a posterior approach;
                  - w/ proximal synostosis, the ECU and the supinator are elevated off the ulna, which allows exposure of the synostosis and the radius;
                        - w/ proximal synostosis, consider anterior transposition of the ulnar nerve;
                  - denuded bony surfaces are covered w/ a thin layer of bone wax at the end of the case;
           - postoperative care:
                  - in the report by Jupiter and Ring (1998), neither postoperative radiation nor indomethacin was considered essential to prevent recurrence;
                  - head injury patients may be at higher risk for recurrence, and therefore, they may require XRT or NSAIDS
                  - Operative treatment of post traumatic proximal radioulnar synostosis.



Post traumatic radioulnar synostosis.

Post-traumatic proximal radio-ulnar synostosis. Results of surgical treatment.

Cross union complicating fracture of the forearm. Part I: adults.

Treatment of posttraumatic radioulnar synostosis with excision and low dose radiation

Radioulnar synostosis.

Treatment of traumatic radioulnar synostosis by excision and postoperative low dose irradiation.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, December 12, 2012 3:03 pm