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Distal Radial Ulnar Joint


- See:
    - RU joint subluxation
    - caput ulna syndrome (rheumatoid arthritis)

- Discussion:
    - both proximal & distal radioulnar joints are synovial joints;
    - proximal joint lies between the head of radius & radial notch of the ulna;
    - distal radioulnar joint is separated from wrist by articular disc that extends from base of ulnar styloid process to radius;
    - distral RU joint shares loading forces that occur with forearm rotation and gripping;
    - arc of pronation and supination averages 150-160 deg, w/ most useful portion between 80 deg pronation & 45 deg supination;
    - forces across the wrist:
           - traditionally, it has been thought that the distal radius bears 80% of the load across the wrist and the distal ulna (and TFCC bears 20% of the force);
           - this has recently been challenged by Markolf et al (JBJS, Jun 98) who found that the distal ulna bore only 3% of the force when the elbow was positioned in valgus alignment;
                  - they felt that the TFCC was too compliant to bear significant loads;
    - anatomy:
           - triangular fibrocartilage complex
           - ligamentous attachements: (see ligament of the wrist)
                  - dorsal and palmar radioulnar ligaments are lax except in the extremes or pronation and supination;
                  - palmar radioulnar ligaments (ulnolunate and ulnotriquetral) resist dorsal displacement;
                  - effect of pronation:
                         - ulna assumes a small relative negaive variance position;
                         - ulnar head moves dorsally, and volar ligaments become tight;
                  - effect of supination:
                         - ulna assumes a small relative positive variance position;
                         - ulnar head moves volarly, and dorsal ligaments become tight;
    - diff dx:
            - ulnar sided wrist pain
            - ECU tendonitis

- Injury to RU Joint:
    - intra-articular distal radial frx:
          - frx throug the lunate fossa will enter into the DRUJ;
          - significant radial shortening leads to DRUJ incongruity and a change in the ulnar variance:
    - RU joint subluxation:
    - frx dislocation:
          - references:
                 - Fractures and dislocations of the distal radioulnar joint.   
                 - Irreducible fracture-dislocation of the distal radioulnar joint secondary to entrapment of the extensor carpi ulnaris tendon.
                 - Complex dislocations of the distal radioulnar joint. Recognition and management.
                 - Dislocation of the distal radioulnar joint associated with an intra-articular fracture of the ulnar head: report of two cases
    - ulnocarpal impaction
    - TFCC tear

- Radiographs:
zero rotational view allows assesment of ulnar variance;
    - show displaced frx of distal part of radius & widened distal RU joint;
    - ulnar styloid may sustain avulsion frx & displace into distal RU joint w/ ECU tendon;

- Distal Ulnar Arthroplasty:
    - in selecting a distal ulnar arthroplasty, it is necessary to note:
             - slope of the distal RU joint surface
             - whether it is congruent (an incongruent joint might be made congruent with an oblique ulnar shortening);
             - whether it has degenerative changes (in which case, a resection arthroplasty or Sauve-Kapandji may be indicated);
    - ulnar head resections:
             - Bower's Procedure
             - Darrach's Procedure
    - wafer Procedure
    - sauve-kapandji
    - ulnar shortening osteotomy:
             - most indicated for ulnar impaction syndrome;
                    - this procedure unloads the distal ulna, and thereby relieves distal ulnar impingement symptoms;
             - osteotomy may be performed using a transverse, oblique, or step cut osteotomy;
                    - there is some evidence that the oblique osteotomy allows the fastest healing (8-12 weeks);
             - 2-3 mm of shortening is optimal;
             - postoperatively, patients need to avoid pronation/supination exercises until healing is seen;
             - patients who undergo this procedure should be checked for TFCC pathology and should have it appropriately treated if necessary;
                    - as noted by Cooney, et al (1994), patients who had concomitant ulnar shortening and TFCC repair did better than patients with isolate ulnar shortening;
             - references:
                    - Ulna-shortening osteotomy after failed arthroscopic debridement of the triangular fibrocartilage complex.
                    - Precision oblique osteotomy for shortening of the ulna.  
                    - The ulnar impaction syndrome: follow up note of ulnar shortening osteotomy.  
                    - Ulnar shortening using the AO small distractor.   
                    - Triangular fibrocartilage tears.   
    - en bloc resection:
             - may be indicated for GCT or other tumors involving the distal ulna;
                    - it is essential to repair the TFCC to the ulnar collateral and dorsal RU ligaments as well as repairing the periosteal tube;
             - may also be indicated for previous RU joint arthroplasty failures;
             - as reported by Wolfe SW, et al (1998), 12 patients who had treatment failures following various RU joint reconstructive procedures;
                    - following wide excision (at least 25% but no more that 45% of the ulna), 9/12 patients had a good result with 75% normal grip strength;
                    - no soft tissue reconstructions were attempted in this series;
             - complications:
                    - ulnar translocation which may occur in rheumatoid arthritis;
    - references:
             - En Bloc Resection of Tumors of the Distal End of the Ulna
             - The "wafer" procedure. Partial distal ulnar resection.
             - Wide Excision of the Distal Ulna: A Multicenter Case Study

- Surgical Approach:
    - dorsal approach thru EDQ and ECU;
    - allows access to most of ulnar head, ulnar styloid, TFCC, RU joint

Current Concepts Review.  Carpal Instability.

Distal radioulnar joint arthroplasty. Current concepts.

Anatomy of the distal radioulnar joint.

A study of radioulnar movements following fractures of the forearm in children.

The distal radioulnar joint. Anatomy, biomechanics, and triangular fibrocartilage complex abnormalities.

The blood supply of the human distal radioulnar joint and the microvasculature of its articular disk.

Biomechanics of the distal radioulnar joint.

Evolution of the distal radioulnar joint.

Radial head fractures and their effect on the distal radioulnar joint. A rationale for treatment.

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

Last updated by on Wednesday, December 12, 2012 2:00 pm

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