Indications

Choosing between ablative procedures is often a matter of personal preference, but certain principles should be employed to aid in the decision-making process. If the sigmoid notch is incongruous or arthritic, an ablative procedure is usually required. The same is true for the ulnar head. If the articular surface of the ulnar head is deficient, once again an ablative procedure is most often appropriate. None of the distal radioulnar joint salvage procedures is entirely predictable with regard to restoration of painless and stable pronation/supination. Some loss of grip strength is also common after any of the DRUJ salvage procedures.

Caveats

The success of the HIT procedure depends on an intact or reconstructable triangular fibrocartilaginous complex (TFCC). The procedure cannot succeed if the TFCC is not a functional structure. This is often the case in advanced rheumatoid arthritis, and the HIT procedure is not recommended in this setting. In such a patient, a Darrach resection or a Sauvé-Kapandji procedure is recommended. In the absence of inflammatory disease, the TFCC is typically intact or reconstructable. In the setting of a markedly malunited distal radius, a peripheral tear is often present but the overall integrity of the ligament typically remains intact.

Conceptually, the HIT procedure preserves the ulnocarpal ligament complex, thus maintaining some stability while simultaneously addressing the problematic DRUJ by removing the involved distal ulnar articular surface. Thus, the resection involves resection of the ulnar articular head while the shaft/styloid relationship is left intact. The ideal nonrheumatoid candidate presents with a painful distal radioulnar joint with or without a distal radius malunion. The procedure is rarely indicated in the acute setting. The TFCC can be partially deficient, but it must be able to be repaired. It is best if the TFCC is intact; and if it is neither intact nor can be repaired, the procedure offers no advantages over a Darrach procedure. The HIT procedure may also be successfully utilized in the setting of a partially treated distal radius fracture associated with a fracture of the ulnar styloid with associated dislocation of the distal ulna (Fig. 35-1).

FIGURE 35-1 Preoperative posteroanterior (A) and lateral (B) radiographs of a partially treated distal radius fracture with ulnar styloid fracture and distal ulna dislocation. C, After ORIF of the distal ulna using a tension band technique and DRUJ temporary stabilization with two K-wires. D, Despite restoration of reasonable forearm rotation, pain and crepitus persisted, requiring an HIT procedure.

Contraindications

The most significant contraindication for the HIT procedure is the lack of a functional TFCC. The other relative contraindication for the HIT procedure is significant ulnar-positive variance. In this setting, failure to consider postoperative stylocarpal impingement is likely to result in a clinical failure.

Preoperative Considerations

Before considering an HIT procedure, proper radiographs are obtained, including a posteroanterior film in neutral rotation, as well as a grip-loaded posteroanterior view in full pronation to assess variance and estimate the likelihood of postoperative stylocarpal impingement. After excision of the articular surface, the maximum migration of the radius and ulna toward each other is 0.75 cm. If this amount of migration allows the styloid to come within 2 mm of the ulnar-deviated carpus, stylocarpal impingement can be anticipated with a possible clinical failure. Solutions include partial ulnar styloidectomy, osteotomy of the ulnar styloid with shortening and osteosynthesis of the styloid, ulnar shaft shortening with plate fixation, or an interposition anchovy such as the palmaris longus to the radioulnar void.

The HIT Arthroplasty

The procedure is typically performed utilizing general or regional anesthesia under arm tourniquet control. Prophylactic antibiotics are recommended. If a distal radius osteotomy is required, it is recommended that this be performed first. A separate incision is most often required in this setting.

With the forearm pronated, an angled or straight incision is made over the distal ulna (Fig. 35-2). The incision lies dorsal to the dorsal sensory branches of the ulnar nerve. Care is taken to preserve these small branches, which often include both transverse and oblique branches around the DRUJ. The ulnar head presents beneath the retinaculum, between the extensor carpi ulnaris and the extensor digiti minimi (Fig. 35-3). The extensor digiti minimi is used as a guide for fashioning the retinacular flap. In a nonrheumatoid wrist it is recommended that both the retinacular and capsular flaps be ulnar based (Fig. 35-4). The retinaculum is incised over the extensor digiti minimi, retracting the tendon radialward. Once the tendon is retracted, the dorsal margin of the sigmoid notch, the DRUJ capsule, and the TFCC are easily identified. The capsule is then detached from the radius reflecting it ulnarward, leaving a 1-mm cuff for possible later repair (Fig. 35-5). The capsule is dissected along the head of the ulna subperioseally beneath the extensor carpi ulnaris sheath. For more distal exposure, the distal aspect of the dorsal retinaculum can also be reflected as an ulnarly based flap, with care taken to avoid disrupting the dorsal fibers of the TFCC (Fig. 35-6). In the nonrheumatoid wrist, it is not necessary to violate the extensor carpi ulnaris subsheath.

FIGURE 35-2 The incision (A) and design of retinacular flaps (B).

FIGURE 35-3 With the forearm pronated, the distal ulna presents between the extensor digiti minimi radialward and the extensor carpi ulnaris ulnarward.

FIGURE 35-4 After reflecting the retinacular flap, the capsule is then incised and reflected ulnarward. a, proximal retinaculum; b, distal retinaculum; c, DRUJ capsule.

FIGURE 35-5 A and B, In this nonrheumatoid wrist, the two retinacular flaps have been reflected ulnarward, allowing visualization of the DRUJ, dorsal limb of the TFC, and, with further dissection, the lunotriquetral joint. a, proximal retinaculum; b, distal retinaculum; c, DRUJ capsule.

FIGURE 35-6 A and B, A small, flat osteotome is used to osteotomize the distal ulna for excision. It is recommended that the first cut be from distal to proximal.

At this point, if the articular surface is sufficiently involved, the ulna articular surface is removed with small, flat osteotomes and a rongeur (Figs. 35-6 and 35-7). I recommend starting with a flat osteotome from distal to proximal, removing the dorsal half of the ulna head. Care is taken to ensure that the foveal attachment of the TFCC is not disrupted. A second oblique cut is then made once again from distal to proximal after rotating the forearm. It is typically necessary to make a third cut from proximal to distal once again using a small, flat osteotome. This “third cut” removes the palmar portion of the head, which is easy to miss if one is not careful. A rasp or small rongeur is used to smooth out the remaining bone. The remaining shaft/styloid axis should be round in cross section and resemble a tapering 1-cm diameter dowel. A small laminar spreader is used to facilitate exposure to be sure an adequate resection has been performed, particularly volarward. All osteophytes around the sigmoid notch and all the bone of the ulnar head beneath the articular surface must be excised. Inadequate bone removal can result in a clinical failure.

FIGURE 35-7 A, The third cut is from proximal to distal, once again using the same flat osteotome. B, Resected specimen.

After completing the bony resection, all remaining synovium is excised and the integrity of the TFCC is inspected. If necessary, the articular disc can be débrided at this point. An assessment of stylocarpal impingement is then performed, typically with the aid of a portable fluoroscopy unit (Fig. 35-8). While under fluoroscopy, the radius and ulna are compressed and rotated with the wrist in ulnar deviation. If one remains concerned that the styloid will impinge on the carpus, options include interposing a tendon “anchovy,” such as the palmaris longus (Fig. 35-9), or performing an ulnar shortening for more obvious degrees of impingement. Available expendable tendons would include the palmaris longus (most common), one half of the flexor carpi radialis, the extensor indicis proprius, or a long toe extensor. The tendon graft is rolled into a ball around a straight clamp and sutured with absorbable 3-0 Vicryl sutures to keep it intact. It is then placed into the cavity after the partial ulnar head resection and sutured to the volar capsule and pronator quadratus to prevent displacement. The dorsal capsule is then anatomically repaired back to the septum between the extensor digiti minimi and the DRUJ.

FIGURE 35-8 Intraoperative inspection with the aid of a portable fluoroscopy unit is recommended to assess adequacy of resection and stylocarpal impingement syndrome.

FIGURE 35-9 An “anchovy” prepared from the palmaris longus is inserted into the newly created cavity as a means of preventing stylocarpal impingement.

If one decides that an anchovy is inadequate to prevent impingement and that an ulnar shortening is required, it can be performed at one of three locations. The first and most straightforward location is at the tip of the styloid. This is useful in those cases in which there is a long, hooked styloid. In this instance, the distal aspect of the styloid is exposed and excised. Preservation of the deep fibers of the TFCC attached to the fovea preserves DRUJ stability. The second option is a shortening through the metaphyseal base of the ulnar head at the proximal margin of the head excision, with excision of a wedge of bone and fixation using a compression interosseous wire loop (Fig. 35-10). This is technically more demanding. The final alternative is a formal shortening through the proximal ulnar shaft and plate fixation. This is typically recommended when the preoperative ulnar-positive variance is greater than 3 to 4 mm. When considering stylocarpal impingement, the preoperative variance radiographs are critical. The variance is best determined by an anteroposterior pronated grip radiograph.⁹ In borderline cases (preoperative variance between neutral and 2 mm positive), an anchovy may be utilized, but in most cases the capsule and retinaculum are the only materials interposed and are sutured to the volar capsule (Fig. 35-11).

FIGURE 35-10 Postoperative radiograph after HIT procedure with ulnar styloid osteotomy, shortening, and osteosynthesis using a wire loop.

FIGURE 35-11 A to C, In this patient, no interposition other than the infolded capsule and retinaculum was required. These are sutured to the palmar capsule. a, proximal retinaculum; b, distal retinaculum; c, DRUJ capsule.

Postoperative Care

Typically, the postoperative care depends on what other procedures have been performed. If a corrective distal radius osteotomy has been performed along with a hemi-resection, immobilization may vary depending on the stability of the construct.

In the absence of a distal radius osteotomy, a long-arm plaster splint is utilized for 10 days. The sutures are then removed, and a removable Muenster splint is utilized for 2 to 3 additional weeks. Radiographs are typically obtained at this time. During this period, active elbow and digital motion are encouraged. After approximately 4 weeks, active and gentle passive forearm rotation is begun. If an ulnar shortening is required, a short arm cast is utilized for 4 to 6 weeks while the osteotomy heals. An osteotomy at the site of the ulnar head resection typically heals within 6 weeks, whereas a shortening performed at the shaft level requires a longer period of protection. Supervised hand therapy is most often done, depending on the patient’s progress. A return to full activities typically takes 3 to 4 months.

Complications

The most common complication involves stylocarpal impingement. It does not typically occur if it is anticipated and dealt with at the primary procedure. Another potential complication is painful and/or restricted forearm rotation. In the absence of stylocarpal impingement, this is usually the result of inadequate bony resection. Computed tomography obtained in full pronation/supination can be helpful in this regard. Another potential complication involves painful instability of the remaining distal ulna. Because of the lack of the “ulnar seat,” some degree of instability is inevitable. Most often, however, this does not result in significant symptoms.

Results

In carefully selected cases, the anticipated results are generally good to excellent. Some patients continue to experience mild pain, particularly with heavy use, but most can expect clinical improvement within 3 to 6 months. As with most DRUJ salvage procedures, a return to heavy labor is not anticipated. In patients with significant ongoing symptoms after an appropriate HIT procedure, a DRUJ prosthesis can be utilized with success.

ACKNOWLEDGMENT

The author wishes to thank William H. Bowers, M.D., for providing some of the photos used in this manuscript.