Radius Ulna Synostosis / Congenital Radial Ulnar Synostosis

Treatment

• Nonoperative

  • observation

  • • • indications

        • • usually the preferred treatment, particularly when asymptomatic and unilateral

  • Operative

• • • indications

      • absolute

        • deformity is limiting ability to participate in specific activities (sports, hygiene, eating)

      • relative

        • severe pronation deformity > 60°

        • bilateral deformities

    • general options

      • mobilization of the synostosis - to restore active forearm rotation

      • rotational osteotomy - to improve static forearm and hand position

    • synostosis excision with soft tissue interposition

      • • goal

          • • restore active forearm rotation

        • technique

          • • excise synostosis and interpose vascularized fascio-fat graft

              • • vascularized fat better than free fat graft

                • interposed anconeus muscle did not prevent reossification

            • excision alone without graft interposition results in nearly 100% recurrence of synostosis

• • • • • • outcomes

            • • gain in active forearm motion is usually slight

              • unsatisfactory results in most studies

• • • forearm derotational osteotomy

      • • goal

• • • • • • place the forearm in more functional resting position

• • • • technique

        • perform between 3-6 years of age (average age ~5 years)

        • osteotomy location

• • • • • • radius and ulna proximal diaphysis at synostosis

            • • rotation takes place over narrow space - risks soft tissue tightness, loss of correction and neurovascular compromise

          • radius and ulna diaphysis distal to synostosis, at different levels

• • • • • • • osteotomies at different levels distributes rotational correction - less soft tissue tightness and risk of neurovascular complications

• • • • • • radius distal diaphysis alone

• • • • • timing of correction

• • • • • • immediate correction at time of osteotomy

          • delayed correction 10 days following osteotomy

          • gradual correction with circular external fixator frame (Ilizarov)

            • lowest rate of neurovascular complications (compartment syndrome, nerve palsies)

• • • • • positioning

• • • • • • unilateral - fix the forearm in 0-30° pronation

            • • bilateral - fix dominant forearm in 0-15° pronation and nondominant forearm in neutral

              • • older studies state the nondominant forearm should be placed in 10-15° of supination; however, this was at a time when keyboards and mobile devices were not as ubiquitous and is no longer recommended

• • • • • stabilization

          • • casting alone (no fixation)

• • • • • • • • circular external fixator frame (Ilizarov)

              • percutaneous pins

• • • • • outcomes

          • • most techniques result in improved forearm position and patient function with low rate of deformity recurrence

Complications

• Recurrence of synostosis

  • • nearly 100% recurrence of synostosis with excision alone or with interposition of anconeus muscle

    • interposition of vascularized fascio-fat graft has 0% recurrence

• Recurrence of malrotation

• • casting after derotational osteotomy associated with 15-20° loss of correction

• Compartment syndrome

  • • up to 36%

    • associated with large rotational corrections > 60°

    • close observation post-operatively

    • some authors advocate for prophylactic forearm fasciotomies in acute and/or large deformity corrections

• Neurologic deficit

  • • PIN palsy - particularly with proximal (synostosis) osteotomy

    • AIN palsy

    • radial nerve palsy

    • higher risk with acute/large deformity correction

    • most resolve within 3 months

Post-traumatic cases are most likely to develop following surgery for a forearm fracture, this is more common with high-energy injuries where the bones are broken into many pieces (comminuted).[1] It can also develop following soft tissue injury to the forearm where there is haematoma formation.

Treatment[edit]

It is sometimes possible to correct the problem with surgery, though this has high failure rates for treatment of post-traumatic radioulnar synostosis.[1]

References

https://www.orthobullets.com/hand/6071/congenital-radial-ulnar-synostosis

https://en.wikipedia.org/wiki/Radioulnar_synostosis

Wurapa, Raymond (7 January 2017). "Radioulnar Synostosis: Background, Pathophysiology, Etiology". eMedicine. Retrieved 2 March 2017.

"Congenital radio-ulnar synostosis | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov. Retrieved 2 March 2017.

"OMIM Entry - RADIOULNAR SYNOSTOSIS". omim.org. Retrieved 2 March 2017.

RADIOULNAR SYNOSTOSIS WITH AMEGAKARYOCYTIC THROMBOCYTOPENIA 1; RUSAT1". omim.org. Retrieved 2 March 2017.