- Congenital Synostosis:
- 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;
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;
- 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;
- 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.