Partial Scaphoid Excision of Scaphoid Nonunions

 

 

 

 

DEFINITION

Scaphoid fractures are quite commonplace, representing the most frequently fractured carpal bone with an annual incidence of approximately 29 per 100,000.5 Fractures of the scaphoid, when treated acutely

and appropriately, have union rates greater than 90%.3,9 However, without proper diagnosis and treatment, scaphoid fractures frequently result in nonunion.

Initial treatment for a scaphoid nonunion is typically open reduction and internal fixation (ORIF) with bone graft, be it a corticocancellous wedge or a vascularized graft.

Despite appropriate internal fixation and bone grafting, failure rates are approximately 15% in waist fractures and 33% in proximal pole fractures.12

If ORIF and bone grafting fails, the surgeon is then left with difficult choices.

Revision ORIF with bone grafting (failure rate of 50%)2,16

Salvage procedure which may have a higher rate of satisfactory results

Silicone prostheses previously described have had poor results due to silicone synovitis and implant loosening, dislocation, and breakage.13

When a patient has pain caused by a chronic scaphoid nonunion (FIG 1) with posttraumatic arthritis limited to the distal pole of the scaphoid and radial styloid, partial scaphoid excision (distal fragment) provides a reasonable, low-morbidity alternative treatment option.4,11,15

 

ANATOMY

 

The scaphoid bone represents the bridge between the proximal and distal rows of the carpus. It is tilted in both the volar and radial planes in respect to the central axis of the forearm, articulating with both rows.

 

 

 

FIG 1 • Failed ORIF of a scaphoid nonunion (PA and lateral views).

 

 

The scaphoid is mostly covered in articular cartilage and has important intrinsic and extrinsic ligamentous attachments.

 

Most of the vascular supply to the scaphoid enters the bone distal to the waist and perfuses in a retrograde fashion (FIG 2).6,17

 

The proximal pole is most at risk secondary due to its tenuous blood supply.

 

All of these anatomic features make surgical management complex.

 

PATHOGENESIS

 

Patients with scaphoid fractures who present with delays (>4 weeks) in both diagnosis and treatment can develop a nonunion. Other risk factors for nonunion include proximal fracture location, comminution, fragment displacement or angulation, and associated carpal instability. As with other fractures, smokers are at increased risk for nonunion.

 

 

Acute scaphoid fractures with fracture fragment displacement more than 1.0 mm, an intrascaphoid angle more than 45 degrees, or a height-to-length ratio more than 0.65 have a higher incidence of nonunion.18

 

Because the scaphoid serves as a bridge between the proximal and distal carpal rows, a scaphoid fracture can severely disrupt wrist biomechanics and normal loading patterns.

 

 

Scaphoid fractures disrupt the normal linkage between the two rows, and thus the proximal fragment remains with the lunate via the scapholunate ligament and the distal fragment flexes unimpeded.

 

 

Scaphoid collapse reduces the carpal height and allows the lunate to rotate in a dorsal intercalated segmental instability (DISI) pattern.

 

Scaphoid nonunion advanced collapse (SNAC) arthritis develops from the altered biomechanics.

 

NATURAL HISTORY

 

Most patients with scaphoid fractures, and thus nonunions, are young males between the ages of 20 and 30 years.5,7

 

There is controversy regarding the true natural history of patients with scaphoid nonunions given that most

studies are biased toward symptomatic patients.8 However, it is widely believed that radiographic signs of posttraumatic arthritis will develop in almost 100% of patients with a scaphoid nonunion. These degenerative changes occur in a predictable pattern, and the process may take 5 to 20 years.8,10,14

 

Arthritis first develops between the distal pole of the scaphoid and the radial styloid (SNAC wrist stage I; FIG 3A).

 

Left untreated, stage I SNAC will progress to involve the midcarpal joint (SNAC stages II and III; FIG 3B,C).

 

 

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FIG 2 • A. Volar intraosseous blood supply to the scaphoid with laterovolar and distal vessels visualized. B.

Dorsal intraosseous blood supply to the scaphoid.

 

 

Many patients present once pain and decreased range of motion in the wrist has become increasingly severe. In these cases, salvage procedures requiring arthrodesis are often the only options left.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Most patients present having previously sustained a dorsiflexion injury, although not all patients will remember specific trauma. Some patients will present with no previous treatment and a chronic nonunion (FIG 4), and others will have failed to respond to either operative or nonoperative therapy.

 

 

Slow progression over the preceding years of pain aggravated by use, loss of motion, and loss of grip strength are consistent presenting complaints.

 

It is critical to know the patient's smoking history, occupation, and previous operations, as these will dictate future interventions.

 

The examiner should palpate the anatomic snuffbox, which lies between the extensor pollicis longus and

extensor pollicis brevis tendons. Pain in this region may be indicative of a fracture. As arthritis develops, there may be tenderness and soft tissue fullness along the entire radiocarpal joint due to synovitis.

 

 

 

 

FIG 3 • A. Arthritis observed between the distal pole of the scaphoid and the radial styloid (SNAC grade I).

(continued)

 

 

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FIG 3 • (continued) B,C. Stage I SNAC can progress to involve the scaphocapitate articulation (SNAC grade II) with eventual diffuse arthritis in the midcarpal joint (SNAC grade III).

 

 

Measurements of grip strength and range of motion (ROM) need to be ascertained.

 

 

Strength is often decreased by as much as 30% to 40% if the patient is experiencing pain.

 

There will often be a decrease in dorsiflexion of the wrist relative to the contralateral unaffected side.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Posteroanterior (PA), lateral, and ulnar and radial deviation views of the wrist are required. These views are usually enough to determine if a partial scaphoid excision is indicated.

 

 

The lateral plain radiograph allows one to determine the degree of DISI (FIG 5A).

 

 

 

FIG 4 • Chronic nonunion of the scaphoid with SNAC in a patient with no previous treatment.

 

 

If the radiographs reveal intercarpal arthritis (FIG 5B) or a small avascular proximal pole fragment, partial scaphoid excision may be contraindicated.

 

If minimal radioscaphoid arthritis is observed, ORIF (with nonvascularized or vascularized bone graft) to reconstruct the nonunited scaphoid might be the best option.

 

A magnetic resonance imaging (MRI) is often ordered by physicians in the management of scaphoid nonunions to evaluate the blood supply of the proximal pole. However, these studies have little influence in patients who are candidates for a distal fragment excision.

 

From a radiographic perspective, the ideal candidate for distal pole excision of the scaphoid has a nonunion of the scaphoid fracture at the level of the waist or distal pole with concomitant degenerative joint disease between the distal radius and distal pole only (SNAC stage I).

 

DIFFERENTIAL DIAGNOSIS

Acute scaphoid fracture

First or second extensor compartment tendonitis Scapholunate ligament injury

Basilar thumb arthritis Scaphotrapeziotrapezoid arthritis Inflammatory arthritis

 

 

NONOPERATIVE MANAGEMENT

 

Nonoperative management of chronic wrist pain should always be considered in discussion with patients about treatment options. The symptoms may be months or even years old, so there is little rush to intervene if the patient desires further delay.

 

The treatment of any painful joint begins with intermittent immobilization (wrist splinting), activity modification, and nonsteroidal anti-inflammatory drugs (NSAIDs).

 

If immobilization and NSAIDs are ineffective, temporary pain relief can almost always be gained with a steroid injection. These temporizing treatments also put the pain in perspective for the patient. The patient may conclude that medication and splinting is all that is necessary.

 

During the nonoperative management period, the surgeon gains a perspective on the degree of patient discomfort and simultaneously gauges the patient's expectations.

 

 

The operation will work better and the patient will be more satisfied if the patient's and surgeon's expectations are similar.

 

SURGICAL MANAGEMENT

 

Surgical options to treat persistent pain resulting in compromised function in a patient with a scaphoid nonunion and arthritis limited to the area between the distal fragment of the scaphoid and the radial styloid (stage I SNAC wrist arthritis) include the following:

 

 

 

ORIF of the scaphoid nonunion combined with radial styloidectomy Resection of the distal scaphoid fragment

 

 

 

Partial wrist arthrodesis Proximal row carpectomy Wrist denervation

 

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FIG 5 • A. Lateral plain radiograph displaying a DISI deformity. B. When intercarpal arthritis (SNAC grade III) or an avascular proximal pole is found, partial scaphoid excision may be contraindicated.

 

 

A patient with an untreated scaphoid nonunion and no arthritis is best treated by ORIF of the scaphoid with bone grafting. In a patient with SNAC wrist stage II, it is too late for a distal pole excision; this patient may require a proximal row carpectomy or scaphoid excision with intercarpal fusion.

 

Most patients requiring excision of the distal pole have undergone prior treatment that has failed, and both the surgeon and the patient are searching for a reliable procedure with low morbidity to help alleviate the patient's pain and improve function.

 

Distal scaphoid excision requires robust and taut radioscaphocapitate and long radiolunate ligaments in order to support the remaining proximal carpus and prevent collapse (DISI) of the wrist.

 

Contraindications to distal pole excision include the following:

 

 

Preexisting significant DISI deformity. The DISI deformity may indeed get worse with distal pole excision in an individual with poor ligamentous support.

 

Proximal pole that is less than half the entire size of the scaphoid. If the distal fragment is greater than 50% of the size of the scaphoid, resultant collapse of the carpus may occur with severe morbidity.

 

Preoperative Planning

 

Preoperative planning is done based on a thorough review of the patient's plain radiographs.

 

 

If the distal pole is to be excised, there must be enough proximal pole (>½) left to support the distal row of the carpus. If only a very small (and possibly an avascular) proximal pole remains, the carpus is likely to

collapse, resulting in failure of the procedure.

 

Positioning

 

 

The patient is placed in the supine position with the extremity on an arm board. A proximal arm pneumatic tourniquet is applied.

Approach

 

The distal pole of the scaphoid can be excised through either a dorsal or palmar approach. The approach may be dictated by existing scars.

 

 

The palmar approach is the preferred method due to the relatively accessible palmar position of the distal fragment.

 

An advantage of the dorsal approach is the ease of excision of the posterior interosseous nerve for wrist denervation.

 

A radial styloidectomy can be performed through either approach.

 

 

 

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TECHNIQUES

• Volar Approach for Excision of the Distal Scaphoid Fragment

Incision and Scaphoid Excision

An incision is made directly over the flexor carpi radialis (FCR) tendon, incorporating any previous incisions (TECH FIG 1A,B).

The tendon is retracted ulnarly and the subsheath of the tendon is incised longitudinally (TECH FIG 1C).

The radiocarpal joint capsule is opened longitudinally and the distal pole of the scaphoid is excised with osteotomes and rongeurs (TECH FIG 1D-G).

 

 

 

 

TECH FIG 1 • A. Chronic scaphoid nonunion with SNAC. The patient had no previous treatment. B. An incision is made directly over the FCR tendon. C. The tendon is retracted and its subsheath opened longitudinally. D. The radiocarpal joint is opened longitudinally and the scaphoid is visualized. E,F. The distal pole of the scaphoid is excised with osteotomes and rongeurs. If indicated, a radial styloidectomy can be performed at this point. G. Excised distal pole of the scaphoid.

Radial Styloidectomy

 

If indicated, an oblique radial styloidectomy can be performed at this point using an osteotome.

 

In this situation, the distal pole may be too large to excise and a radial styloidectomy can accomplish the same purpose.

 

The styloidectomy should be large enough so that the arthritic distal pole no longer touches the radius in radial deviation but not so large as to disrupt the origin of the radioscapholunate ligament, as this may preclude later proximal row carpectomy.

Wound Closure

 

 

 

The capsule and volar extrinsic ligaments are closed with interrupted permanent sutures. The skin is closed with interrupted nonabsorbable sutures.

 

• Dorsal Approach for Excision of the Distal Scaphoid Fragment

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An incision is made over the radial aspect of the carpus, incorporating any old incisions (TECH FIG 2). The radial sensory nerve is identified and retracted.

 

The interval between the extensor pollicis longus and the radial wrist extensors is entered.

 

The radial artery and its branches are retracted and protected, and then the joint capsule is incised.

 

The distal scaphoid fragment will be deep and is best removed using rongeurs after defining its borders with a no. 15 blade.

 

 

A radial styloidectomy can be performed if necessary as mentioned earlier. The capsule is closed with absorbable suture.

 

The skin is closed with interrupted nonabsorbable sutures.

 

The patient is placed in a well-padded forearm-based splint, leaving the finger metacarpophalangeal joints and thumb interphalangeal joint free. This volar thumb spica splint is placed after either the volar or dorsal approach.

 

 

 

TECH FIG 2 • An incision over the dorsoradial aspect of the wrist may be used when prior surgery has been performed.

 

PEARLS AND PITFALLS
	Indications ▪ It is critical to observe that arthritis does not involve the midcarpal joint. There must be enough proximal scaphoid remaining to support the carpus. The proximal 50% of the scaphoid should be sufficient to support the capitate and the remaining carpus (FIG 6).

Approach

and technique

• The procedure is simpler to perform through a palmar approach.

• Avoid injury to either the radial sensory nerve or radial artery.

• Interpositional material in the space left by the resected distal pole of the scaphoid is not necessary.

 

FIG 6 • A,B. Scaphoid nonunion after previous internal fixation with development of SNAC wrist arthritis. C,D. Collapse of the scaphoid resulting from too much resection (more than two-thirds) of the distal pole of the scaphoid, with evidence of DISI deformity on postoperative radiographs.

 

 

 

 

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POSTOPERATIVE CARE

 

 

Patients are immobilized for 2 weeks in a well-padded volar splint. The splint and sutures are removed 2 weeks after the procedure.

 

A removable orthosis is applied and the patient is instructed on active and passive ROM exercises.

 

Once active and passive ROM has been achieved, strength exercises are started (usually at 4 weeks postoperatively).

 

Regaining full ROM and strength typically takes about 3 months.

 

Pain relief is noticeable within 2 to 4 weeks of surgery.

OUTCOMES

Review of outcomes in the literature suggest that both ROM and grip strength improve postoperatively.3,4,5

Pain relief can be expected if the proper indications for surgery are followed.

All patients have some degree of DISI preoperatively, and this pattern of deformity may worsen after excision of the distal pole of the scaphoid. DISI deformities that are severe can result in both loss of

motion and pain. This problem is not well documented in the literature but certainly exists.5

 

In the patient undergoing multiple procedures, outcomes of distal pole excision are better than attempting another bone graft and internal fixation, where the failure rate can approach 50%.1

 

 

COMPLICATIONS

The presence of midcarpal arthritis undiagnosed before distal pole excision can lead to persistent pain. Resection of too large a distal pole (>50%) can result in collapse of the scaphoid.

If the procedure is performed in a very loose-jointed individual, the DISI pattern may significantly worsen, leading to persistent pain.

 

 

REFERENCES

1. Bishop AT. Vascularized bone grafts. In: Green DG, Hotchkiss R, Pederson W, eds. Green's Operative Hand Surgery. New York: Churchill Livingstone, 1999.

    

    

2. Chang MA, Bishop AT, Moran SL, et al. The outcomes and complications of 1,2 intercompartmental supraretinacular artery pedicled vascularized bone grafting of scaphoid nonunions. J Hand Surg Am 2006;31(3):387-396.

    

    

3. Dias JJ, Wildin CJ, Bhowal B, et al. Should acute scaphoid fractures be fixed? A randomized controlled trial. J Bone Joint Surg Am 2005;87(10):2160-2168.

    

    

4. Drac P, Manak P, Pieranova L. Distal scaphoid resection arthroplasty for scaphoid nonunion with radioscaphoid arthritis. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2006;150: 143-145.

    

    

5. Duckworth AD, Jenkins PJ, Aitken SA, et al. Scaphoid fracture epidemiology. J Trauma Acute Care Surg 2012;72(2):E41-E45.

    

    

6. Gelberman RH, Menon J. The vascularity of the scaphoid bone. J Hand Surg Am 1980;5(5):508-513.

    

    

7. Hove LM. Epidemiology of scaphoid fractures in Bergen, Norway. Scand J Plast Reconstr Surg Hand Surg 1999;33:423-426.

    

    

8. Kerluke L, McCabe SJ. Nonunion of the scaphoid: a critical analysis of recent natural history studies. J Hand Surg Am 1993;18:1-3.

    

    

9. Kuschner SH, Lane CS, Brien WW, et al. Scaphoid fractures and scaphoid nonunion. Diagnosis and treatment. Orthop Rev 1994; 23:861-871.

    

    

10. Lindström G, Nyström A. Natural history of scaphoid non-union, with special reference to “asymptomatic” cases. J Hand Surg Br 1992;17:697-700.

     

     

11. Malerich MM, Clifford J, Eaton B, et al. Distal scaphoid resection arthroplasty for the treatment of

    degenerative arthritis secondary to scaphoid nonunion. J Hand Surg Am 1999;24:1196-1205.

     

     

12. Merrell GA, Wolfe SW, Slade JF III. Treatment of scaphoid nonunions: quantitative meta-analysis of the literature. J Hand Surg Am 2002;27(4):685-691.

     

     

13. Peimer CA, Medige J, Eckert BS, et al. Reactive synovitis after silicone arthroplasty. J Hand Surg Am 1986;11:624-638.

     

     

14. Ruby LK, Stinson J, Belsky MR. The natural history of scaphoid non-union: a review of 55 cases. J Bone Joint Surg Am 1985;67: 428-432.

     

     

15. Ruch DS, Papadonikolakis A. Resection of the scaphoid distal pole for symptomatic scaphoid nonunion after failed previous surgical treatment. J Hand Surg Am 2006;31:588-593.

     

     

16. Smith BS, Cooney WP. Revision of failed bone grafting for nonunion of the scaphoid. Treatment options and results. Clin Orthop Relat Res 1996;(327):98-109.

     

     

17. Taleisnik J, Kelly PJ. The extraosseous and intraosseous blood supply of the scaphoid bone. J Bone Joint Surg Am 1966;48:1125-1137.

     

     

18. Trumble TE, Salas P, Barthel T, et al. Management of scaphoid nonunions. J Am Acad Orthop Surg 2003;11:380-391.