87: Four-Corner Fusion

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Procedure 87 Four-Corner Fusion

Jeffrey A. Greenberg

imageSee Video 65: 4-Corner Fusion Using Kirschner Wires

Indications

image Scapholunate advanced collapse (SLAC)

image Scaphoid nonunion advanced collapse (SNAC)

image Radiocarpal arthrosis

image Carpal instability patterns

image Failed soft tissue reconstructions

Examination/Imaging

Clinical Examination

image Radial fullness

image Decreased range of motion

image Decreased grip strength

image Painful range of motion

image Crepitus

image Painful extension loading

image Watson maneuver eliciting pain

image Styloid tenderness

image Carpal tunnel syndrome possible

Imaging

image Plain radiographs are usually sufficient for diagnosis. SLAC wrist, stage 3, demonstrates abnormal position of the scaphoid, scapholunate widening, radioscaphoid degenerative change and midcarpal arthrosis (Fig. 87-1).

image In cases in which there is uncertainty about the status of the radiolunate joint, advanced imaging (computed tomography) may be used.

image

FIGURE 87-1

Surgical Anatomy

image In either SLAC or SNAC, there will be widening at the scapholunate interval.

image Significant scaphoid flexion, lunate extension, and dorsal lunate prominence develop.

image Radioscaphoid degenerative change with styloid prominence and osteophytes is noted.

image Proximal scaphoid pole necrosis and/or arthrosis is present (Fig. 87-2).

image Synovitis is present.

image Scaphotrapeziotrapezoid arthrosis may be present.

image The dorsal ligaments of the wrist—dorsal radiocarpal (DRC) and dorsal intercarpal (DIC)—have a conjoined insertion on the triquetrum. They provide the capsulotomy landmarks for wrist exposure.

image The volar extrinsic ligaments (radioscaphocapitate, short and long radiolunate) originate from the volar radius and extend obliquely to the carpus. These should be respected during scaphoid excision (Fig. 87-3).

image

FIGURE 87-2

image

FIGURE 87-3

Positioning

image The patient is positioned supine, the hand and forearm are supported on a hand surgery table, and a proximal tourniquet is used.

image Operating on the wrist is easier if the surgeon is positioned at the head of the patient as opposed to at the axilla.

Exposures

image A dorsal midline incision centered over the radiocarpal joint is used.

image Thick flaps are elevated dorsal to the retinaculum, keeping cutaneous nerves within these flaps.

image The retinaculum over the third dorsal compartment is incised.

image Retinacular flaps are raised, exposing the second through fifth compartments (Fig. 87-4).

image The extensor tendons are retracted using retractors placed between the second and fourth compartments.

image A posterior interosseous neurectomy is performed.

image A capsulotomy is performed by dividing the dorsal capsule along the dorsal intercarpal and dorsal radiocarpal ligaments (Fig. 87-5). The flap is elevated off the dorsum of the triquetrum and reflected, keeping it radially based (Fig. 87-6).

image

FIGURE 87-4

image

FIGURE 87-5

image

FIGURE 87-6

Pearls

Wrist flexion and bluntly removing fibrofatty tissue from the dorsal capsule facilitate visualization of the DIC and DRC.

Pitfalls

Dividing the DRC too distally makes it difficult to access and work on the lunate.

Failure to expose the capsule between the second and fifth compartments compromises visualization.

Procedure

Step 1

image Inspection of the radiolunate joint is performed to ensure that it is free of degenerative change.

image A threaded gimlet, Schanz screw, or Steinman pin is used as a joystick to facilitate removal of the scaphoid (Fig. 87-7).

image The scaphoid is excised in one piece (Fig. 87-8).

image

FIGURE 87-7

image

FIGURE 87-8

Step 1 Pearls

Avoid the temptation to morselize the scaphoid or remove it piecemeal because it is easier to carefully dissect the bone subperiosteally and remove it in one piece. A curved, sharp Carroll elevator facilitates the deeper dissection.

Step 1 Pitfalls

Care must be taken to avoid injury to the volar extrinsic ligaments, radial artery, and capsular flap during scaphoid excision.

Step 2

image After scaphoid removal, a styloidectomy is performed.

image Cancellous bone graft is harvested from the distal radius, accessing cancellous bone through the styloidectomy site (Fig. 87-9).

image

FIGURE 87-9

Step 2 Pitfalls

Avoid an excessive styloidectomy because this can compromise the volar extrinsic ligaments and lead to ulnar translational instability.

Step 3

image A 0.062-inch Kirschner wire is placed in the dorsal lunate as a joystick. The lunate is usually in an abnormally extended position, and it must be reduced to a colinear relationship with the capitate (Fig. 87-10). Soft tissue release may be necessary to achieve this relationship.

image After confirming that reduction is possible, the midcarpal joint is exposed, and the cartilage and subchondral bone of the distal lunate and capitate are removed.

image Bone graft is placed, and the lunate is reduced.

image Provisional K-wire fixation holds the lunate, and the capitate is reduced (Fig. 87-11).

image Intraoperative fluoroscopy confirms reduction.

image

FIGURE 87-10

image

FIGURE 87-11

Step 3 Pearls

Occasionally a large dorsal lunate osteophyte is present and may be removed to facilitate visualization of the midcarpal joint.

When correctly reduced, the capitate appears to overhang the radial margin of the lunate.

Colinearity of the lunate to the capitate, or even slight lunate flexion, is desirable.

Step 3 Pitfalls

Malreduction or incomplete reduction of the lunate is the most common error and is associated with poor clinical results.

Step 4

image The lunotriquetral, triquetrohamate, and capitohamate intervals are prepared by removing cartilage and subchondral bone.

image Graft is placed in these intervals.

image Provisional fixation from the triquetrum to the capitate is performed.

Step 4 Pearls

The capitohamate relationship is relatively immobile and does not need to be completely taken down for fusion preparation.

Step 4 Pitfalls

Inadequate articular surface preparation can lead to delayed union and/or nonunion.

If power tools are used for surface preparation, it is important to keep heat at a minimum to avoid bone necrosis.

Step 5

image The radiocarpal joint is flexed, and a guidewire for a cannulated screw is placed down the central lunate-capitate axis.

image A cannulated screw is placed compressing the midcarpal joint.

image A second screw is placed obliquely to the first screw, usually from the triquetrum into the capitate (Fig. 87-12).

image Range of motion and stability are checked.

image Fluoroscopy confirms hardware placement (Fig. 87-13).

image

FIGURE 87-12

image

FIGURE 87-13

Step 5 Pearls

Screw back-out can be limited by placing two screws obliquely to one another.

No fixation is necessary across the capitohamate interval.

Two screws are usually adequate to secure the entire fusion mass.

Step 5 Pitfalls

Parallel placement of screws has been associated with screw back-out and potential damage to the distal radial articular surface.

Additional Steps

image An additional graft is placed to fill the prepared interfaces (Fig. 87-14).

image The capsule is closed anatomically with nonabsorbable suture (Fig. 87-15).

image The retinaculum is closed leaving the extensor pollicis longus (EPL) transposed.

image The skin is closed with nonabsorbable suture.

image A bulky compressive dressing is applied to allow digital range of motion and to help control edema (Fig. 87-16).

image

FIGURE 87-14

image

FIGURE 87-15

image

FIGURE 87-16

Postoperative Care and Expected Outcomes

image The postoperative dressing is maintained for 2 weeks.

image The wrist is then immobilized in a removable custom-molded splint that is worn full time except for bathing.

image Range-of-motion exercises can commence 6 to 8 weeks after surgery.

image Strengthening exercises begin at 12 weeks.

image Patients can expect to lose about 50% of their preoperative range of motion with a total arc of motion of about 60 to 90 degrees.

image Complete recovery can be prolonged—up to 12 to 18 months.

Pearls

If fixation intraoperatively is tenuous, postoperative cast immobilization is recommended.

Pitfalls

Premature range of motion or excessive use in noncompliant patients can lead to hardware failure and nonunion.

Evidence

Bain GI, Watts AC. The outcome of scaphoid excision and four-corner arthrodesis for advanced carpal collapse at a minimum of ten years. J Hand Surg [Am]. 2010;35:719-725.

This study evaluated 31 patients who were available for review from a cohort of 35 patients who underwent scaphoid excision and four-corner arthrodesis. Minimum follow-up was 10 years. Preoperative pain scores of 6/10 decreased to 0/10 at 1 year. A decrease in wrist flexion by an average of 22% was noted. Grip strength did not change significantly. Pain scores, wrist function, patient satisfaction, and arc of motion were maintained between 1 and 10 years. Two patients required total wrist arthrodesis for persistent pain. (Level IV evidence)

Cohen MS, Kozin SH. Degenerative arthritis of the wrist: proximal row carpectomy versus scaphoid excision and four-corner arthrodesis. J Hand Surg [Am]. 2001;26:94-104.

In this comparative retrospective study, 19 patients with an average of 28 months of follow-up achieved a flexion arc that was 58% of the unaffected side and grip strength that was 79% of the unaffected side. (Level III evidence)

Dacho AK, Baumeister S, Germann G, et al. Comparison of proximal row carpectomy and midcarpal arthrodesis for the treatment of scaphoid nonunion advanced collapse (SNAC-wrist) and scapholunate advanced collapse (SLAC-wrist) in stage II. J Plast Reconstr Aesthet Surg. 2008;61:1210-1218.

DASH scores improved from 43 preoperatively to 21 postoperatively in this group of 17 patients. They noted 72% grip strength of the opposite side, 56% flexion-extension arc, and an 88% rate of return to previous employment. (Level III evidence)

Vance MC, Hernandez JD, Didonna ML, et al. Complications and outcome of four-corner arthrodesis: circular plate fixation versus traditional techniques. J Hand Surg [Am]. 2005;30:1122-1127.

Thirty-one patients with an average of 59 months of follow-up reported recovery of 50% of the flexion-extension arc and 60% of the radioulnar deviation arc as well as 79% of grip strength. DASH scores averaged 8; 30 of the 31 patients were able to return to previous employment activities. (Level IV evidence)

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