Dorsal Approach (Thompson)

See:

• Plating Techniques
• Radial Shaft Fractures: Discussion

Discussion

• dorsolateral approach is best suited to frxs of proximal & middle thirds of radius as well as to address injury to proximal RU joint;
• advantages:
  • much less soft tissue stripping is required with this approach (as compared to anterior approach), and patients can expect much more rapid return of wrist and hand function;
  • plate on the dorsal aspect of the proximal radius is less likely to produce mechanical block to pronation than if applied to the anterior surface;
• disadvantages:
  • potential risk of injury to PIN with proximal fractures;
  • risk of tendonitis from fist and second wrist compartment tendons with distal fractures;

Interneural Approach

• interval between ECRB (Radial nerve) and EDC (PIN) (or EPL distally);
  • which is the same interval used in the lateral approach to the elbow;
• PIN must be identified & protected w/ this approach;
• exposing proximal third of radius is difficult because deep branch of radial nerve traverses it w/ in supinator;

Surgical Technique

Arm Position

• pt is supine w/ shoulder abducted and the arm resting on hand table;
• arm is placed on arm board, w/ flexed elbow, & mid pronation of forearm;

Incision

• radial extensor group is palpated (mobile wad of Henry: ECRL, ECRB and brachioradialis);
• incision is made on line extending from lateral epicondyle of humerus to radial styloid process, along dorsal border of mobile wad;
• alternatively, make skin incision over the proximal and middle thirds of radius along line 1.5 cm anterior to the lateral humeral epicondyle;
  • when forearm is pronated, this line is virtually straight;
  • expose lateral (radial) border of extensor digitorum communis in the distal part of the incision;
• fascia between digital extensors and mobile wad is split;
  • this interval is sometimes more apparent distally where outcropping muscles of the thumb cross over the radius;

Surgical Dissection

• reflect EDC ulnarly to expose supinator muscle (which covers the dorsal aspect of proximal radius);
• develop an interval between supinator & ECRB;
• fascia between the ECRB & EDC is incised;
• in the distal 1/3, APL and EPB emerge obliquely;
• w/ careful dissection, separate both muscles from shaft of the radius, just sufficiently for a plate to be slipped beneath;
• proximally, identify radial nerve before it enters supinator and then emerges distally from the muscle;
  • some surgeons prefer to identify the nerve distal to the supinator, where it lies in the 4th compartment;
• subperiosteal dissection of the supinator:
  • bring the forearm into full supination, to bring its insertion into view;
  • free muscle from bone subperiosteally from its insertion and reflect it either proximally or distally w/ nerve;
• APL is visible distally, retract it distally and ulnarly to expose part of posterior surface of radius;
• continue dissection proximally between EDC & ECRB-ECRL to lateral humeral epicondyle

References

• Vulnerability of the posterior interosseous nerve during proximal radius exposures.
• Anatomical methods of approach in operations on the long bones of the extremities.
• Surgical exposure of the dorsal proximal third of the radius: how vulnerable is the posterior interosseous nerve?
• The posterior interosseous nerve and the posterolateral approach to the proximal radius.