CHAPTER SYNOPSIS:
The unique characteristics of a normal distal radioulnar joint (DRUJ) provide a stable platform to allow both forearm rotation and axial load bearing. When disrupted by injury or disease, such as arthritis, pain and loss of motion can have a significant functional impact. Treatment options range from steroid injections, to partial and complete ulna resection, to even prosthetic replacement.
IMPORTANT POINTS:
Soft tissue structures provide most of the stability to the DRUJ.
Loss of supination is more difficult to compensate for than loss of pronation.
The goal of treatment is not necessarily to recreate a “normal” joint but to decrease pain and improve function.
Patients who are older or less active are usually more satisfied with most surgical options than are patients who are younger or more active.
All resection procedures are plagued by radioulnar convergence.
Joint replacements, although promising, have not withstood the “test of time.”
CLINICAL/SURGICAL PEARLS:
Conservative options should be exhausted before considering surgical treatments.
Plain radiographs should be diagnostic.
Especially in posttraumatic arthritis, be wary of coexisting radiocarpal arthritis.
When performing the Bowers hemiresection procedure, check for and address ulna styloid-carpal impingement.
Use local soft tissue to stabilize the ulna when performing a Darrach ulna head resection.
When performing a Sauve-Kapandji, make your osteotomy as far distal as possible (while leaving enough head for fixation) and create a gap of 1 cm.
CLINICAL/SURGICAL PITFALLS:
Any of the variations of ulna head resection may fail in patients who are very active.
Overaggressive resection can lead to ulna instability and pain.
Failure to protect the triangular fibrocartilage complex (TFCC) during a partial head resection will lead to failure.
Remember to protect the dorsal branch of the ulna nerve.
Uncorrected malalignment of either the ulna or radius will lead to failure.
INTRODUCTION AND SCOPE
The etymology of the word “wrist” is the verb to twist. Healthy proximal and distal radioulnar joints allow for twisting or pronation and supination motions, which were critical in mammalian and hominoid development. Almquist likened the importance of distal radioulnar joint (DRUJ) development to the development of both the opposable thumb and the increase in size of the primate brain.
The evolution of the wrist joint has occurred over 400 million years and appears to have developed from changes in pectoral fins from early fish. Fins progressed to multiple-rayed limbs containing a humerus, radius and ulna, and carpus in amphibians and reptiles; the wrist in these species maintained a loadbearing function. Advances in pectoral limb function became relevant when early mammals took to the trees approximately 230 million years ago. The wrist at this point was a syndesmosis, and it was not until almost 200 million years later that pronation and supination were required for primate brachiation, or hand over hand swinging through trees.
The ulna regressed from its articulation with the triquetrum and pisiform and the syndesmosis lead way to the synovial distal radioulnar joint, now isolated from the carpus. Anatomic changes in the carpus seemed to parallel changes in the distal radius and ulna leading to multiple species of primates with different osseous structures and intercarpal motions. Each of these conformations appeared to provide the primate with anatomy most appropriate to their individual existence. The conformation of the human wrist allowed both forearm rotation and flexion and extension in several planes of motion.
Ultimately, then, the development of the wrist and DRUJ resulted in an upper limb that allows us to position the hand in a manner to both make and use tools. These motions and abilities, coupled with our increased intellectual capacity, separate us from other animals. Injuries (or diseases) of the wrist, which disrupt the final product millions of years in the making, may severely limit our capacity to function.
ANATOMY AND BIOMECHANICS
The upper extremity positions the hand in a manner that allows humans to manipulate their environment. The shoulder, arm, elbow, forearm, wrist, and hand are all integral in this regard. Pronation and supination motions are affected through rotation of the radius at the proximal and distal radioulnar joints. The magnitude of the rotation of the radius proximally and distally appears to be matched because rotation of the radius within the sigmoid notch of the ulna proximally essentially equals the rotation of distal radius about the ulna distally. The ulna rotates very little relative to the humerus and “appears to act as a direct extension of the humerus in the supination and pronation plane of motion.” Cone and colleagues demonstrated that the glenohumeral joint can contribute to forearm rotation when the elbow is extended and contributes more to pronation (10 to 45 degrees) than supination (10 to 15 degrees).
The axis of this rotation is from the center of the radial head, at the proximal radioulnar joint, through a dynamic locus distally at, or near, the fovea of the ulnar head. The location of the axis is not fixed distally because there is both dorsal and volar translation of the distal radius about the fixed ulnar seat during supination and pronation, respectively. This places the ulnar seat on the volar rim of the sigmoid notch in supination and more dorsal in pronation.
Osteology
The distal ulna has two named articulating surfaces, the ulnar pole and seat, which make up the ulnar head. The ulnar pole is slightly domed distally and articulates with the undersurface of the triangular fibrocartilage ( Fig. 8-1 ). It slants ulnarly and proximally as it “tips” toward the ulnar styloid. The fovea is a bare area radial to the styloid and is replete with vascular foramina. The ulnar seat is the proximal and radial-most aspect of the ulnar head and is covered in cartilage between 180 and 270 degrees of its circumference. The seat, which articulates with the sigmoid notch of the radius, is an irregular sphere or ellipse with variable degrees of curvature.
The sigmoid notch of the radius is a fairly shallow, rhomboid-shaped structure that accepts the ulnar seat. Dorsal and volar ridges confer slight stability to the joint, whereas a distal ridge separates the radiocarpal joint from the DRUJ. The radius of curvature of the notch is nearly double that of the ulnar head and approximately one fourth the circumference of a circle ( Fig. 8-2 ).
The majority of wear on atraumatic cadaveric specimens has been found on the proximal–dorsal and proximal–central aspect of the sigmoid notch of the radius. The ulnar seat has shown similar wear patterns that extended to the proximal–volar region as well. Wear in these proximal areas seems to be significantly greater than wear more distally on both the radius and ulna. Further, ulnar-positive wrists showed more significant degeneration in these areas, which may be explained by less joint parallelism seen in ulnar-positive wrists.
Studies with pressure-sensitive film have shown that there is an increase in contact area and peak pressure within the sigmoid notch with the wrist loaded axially, radially, and ulnarly. The centroid of contact does shift dorsally in pronation and palmarly in supination, as deduced by Bowers. A relative ulnar shortening as little as 2.5 mm seems to increase peak pressures, and both pressure and contact area increase with shortening from 4 to 6 mm.
Soft Tissues
The shallow sigmoid notch does not adequately constrain the ulnar head, so the soft tissues about the DRUJ—specifically, the components of the triangular fibrocartilage complex (TFCC), the joint capsule, and the interosseous membrane—must contribute. The radioulnar ligaments of the TFCC originate on the dorsal and volar distal rims of the sigmoid notch, blend in with the joint capsule, and have both a superficial and deep insertion on the ulnar styloid. The joint capsule also originates from the dorsal and volar lips of the sigmoid notch and extends ulnarly to encircle the ulnar head. It is indistinct from the ECU subsheath in a groove dorsoradial to the ulnar styloid but is clearly a separate structure than the floor of the fifth extensor compartment, which may be dissected free. The capsule is lax in neutral wrist rotation and reciprocally tightens in pronation and supination. The volar capsule is more robust than the dorsal capsule and has a redundant fold that is able to accept the ulnar head as the radius translates dorsally in supination ( Fig. 8-3 ).
Stability
The differences in radius and arc of curvature of the sigmoid notch and the ulnar seat create an incongruous joint, which is responsible for both rotational and translational movement of the radius over the stable ulnar seat during pronation and supination. When the soft tissues described previously relax or tighten appropriately as the radius rotates around the ulna in pronation and supination, the net result is a stable and functional joint.
HISTORY AND PHYSICAL EXAMINATION
The most common presentation of DRUJ arthritis is pain especially associated with activities that include lifting or axial rotation. Crepitance, decreased motion, and swelling are occasionally secondary complaints. DRUJ osteoarthritis can be seen as an isolated entity or in combination with a more diffusely involved wrist. Posttraumatic DRUJ arthritis almost always has an obvious etiology because the injuries that lead up to this problem are not subtle.
Physical examination should occur with the patient seated in front of the examiner with the affected elbow flexed 90 degrees and resting on a table. Gross inspection may show deformity or scar resulting from prior trauma or surgery and localized swelling. Range of motion is assessed in wrist flexion–extension, radial–ulnar deviation, and pronation–supination as per all routine wrist examinations. Focused examination includes palpation of the DRUJ, the TFCC (distal to the ulnar head and at the ulnar fovea ), the extensor carpi ulnaris (ECU), and the lunotriquetral joint. Provocative tests include the ulna grind test, the “piano key” test, the lunotriquetral ballottement test, and the pisotriquetral grind test. The piano key test is performed by grasping the radius dorsally and volarly with one thumb and index finger and the ulnar head with the other and applying alternating dorsal and volar stresses. This test is noted in neutral and 60 degrees of pronation and supination. Significant side-to-side differences should be noted because the normal geometric incongruity allows for approximately 3 mm of dorsal and 5 mm of volar translation in neutral rotation. The ECU should be independently assessed for subluxation or tendinitis, which can cause ulnar-sided wrist pain (and popping that may be confused with crepitation). The patient should start with fully supinated hands and with the elbows flexed so that their palms are directed toward the face. The patient then ulnarly deviate the wrists. Only painful ECU subluxation should be considered pathologic. Alternatively, active resisted pronation may be used to illicit painful ECU subluxation. The ulna grind test is performed by stabilizing the end of the ulna with slight downward pressure and ulnarly deviating the wrist. The “grind” is produced by flexing and extending the wrist in this deviated posture. A positive response is suggestive of TFCC pathology, which can coexist with DRUJ arthritis. Several painful sites may be uncovered and diagnostic injections, as in other parts of the wrist, may help to clarify and direct treatment options.
IMAGING
An arthritic distal radioulnar joint should be easily identified on plane radiographs. Computed tomography (CT) and magnetic resonance imaging (MRI) are complementary, although usually not necessary, and may illustrate deformity from prior distal radius fracture and tears of the soft tissue support structures including the TFCC.
The standard posteroanterior (PA) views are obtained with the shoulder abducted and the elbow flexed 90 degrees The ulnar styloid sits directly opposite the radial styloid in this neutral rotation PA view. Sclerosis, deformity, and osteophytes may be evident about the ulnar head and sigmoid notch ( Fig. 8-4 ). Ulnar variance also should be noted. Positive ulnar variance may be associated with degenerative tears of the TFCC, which could contribute to ulnar-sided wrist pain. The lateral radiograph is inspected to ensure that the ulnar head sits in the sigmoid notch. A neutral rotation lateral view is required to ensure that the radius is not subluxed on the ulnar head because small rotations in this view may result in an apparent pseudosubluxation. This “true” lateral is obtained when the proximal pole of the scaphoid is completely superimposed on the lunate and triquetrum and the radial styloid is centered on the superimposed proximal carpus.
CT of the wrist provides more detail of the sigmoid notch and can also show instability of the joint. CT studies have shown extension of fractures to the sigmoid notch in 65% of intraarticular distal radius fractures. Two thirds of these were associated with articular incongruity. CT can also show subluxation of the radius on the ulna. Several methods have been proposed: ulnar head position relative to radioulnar lines, the epicenter method, radioulnar congruency, and the radioulnar ratio. For the workup of DRUJ arthritis, however, these more detailed studies are seldom necessary.
TREATMENT
The overall goals of treatment are to decrease pain, improve motion and function, and avoid complications. Available surgical procedures primarily include capsular release for contracture, partial or complete resection arthroplasty, arthrodesis, and replacement arthroplasty. Other than capsular release, which is used for posttraumatic contracture with minimal or no pain, all the other procedures aim to obliterate the pain generators in the arthritic DRUJ joint. Although this in itself is straightforward, the trick is to maintain the important functional motions of pronation and supination provided by the normal DRUJ. Additionally, resection of the distal ulna can result in painful instability or ulna impingement (when the ulna stump rubs against the side of the radius) ( Fig. 8-5 ).
Several surgical procedures exist to address the painful distal radioulnar joint. Bone-sparing procedures include Bowers hemiresection interposition arthroplasty and Watson’s matched distal ulna resection. The Darrach procedure excises the ulnar head and the Sauve-Kapandji procedure ablates the arthritis DRUJ joint through an arthrodesis while allowing motion through a proximal pseudoarthrosis. Distal ulnar head replacement, and more recently total DRUJ arthroplasty, are too new to understand long-term implications but do offer moderately promising early results. In general, anyone who fails conservative treatment but is functionally inhibited by pain or motion loss can be considered for surgical treatment with the following caveats. The more bone resected, the more likely the problems with instability, although instability issues can occur even with a hemiresection interposition technique (HIT) or matched distal ulna resection. Distal ulna replacements, which should theoretically improve the problem of instability, are still new and lack long-term data. As with all prosthetic replacements, ulna head (and DRUJ replacements) should not be used in situations of recent infection or with poor soft tissue coverage. The more active the patient, the more likely that the end results of any of these DRUJ procedures will be suboptimal. Finally, salvage procedures for failed ulna resection are difficult and often unrewarding.
Conservative Treatment
Conservative treatment is always the first line of treatment. Options include antiinflammatory medications, narcotic analgesics (only when necessary), splinting, activity modification, and intraarticular injections. The DRUJ can be splinted with a formfitting dorsal and volar thermoplastic clamshell or a Muenster-type splint. Neither of these splints are practical for a patient who is active, but temporary splinting for 4 to 6 weeks may calm down a bad flareup. Local steroid injections may be able to decrease painful synovitis and edema also. A combination of 1 cc each of 1% lidocaine and 0.5% marcaine with 1 cc of 40 mg/mL of methylprednisolone or triamcinolone 40 mg/mL can be given in a sterile injection with the wrist in a fully supinated position, which decreases articular contact and allows for easier palpation of the joint. As in other parts of the body, flare reactions are possible and it may be a good idea to warn the patient of this.
DRUJ Capsulectomy
Capsular release is indicated for a patient with painless limited supination or pronation, or both, as might occur following trauma. Because pain is not a major issue, the DRUJ joint itself does not have to be ablated and the surgery can focus on contracted capsule. Absolute motion values are not realistic and each patient must be assessed with respect to their ability to return to prior vocational or recreational activities. Malunion and significant DRUJ deformity can also cause stiffness and are contraindications to this procedure.
A fibrotic or contracted palmar capsule restricts supination, and pathologic thickening of the dorsal capsule restricts pronation. Most patients have greater difficulty in recovering supination (which may have greater functional implications as a result of limited compensation through the shoulder) and, as noted by Kleinman, all require excision of the volar capsule. Patients with limitations in pronation, assessed again after the palmar capsule is excised, also will require a dorsal capsulectomy. Luchetti has described successful arthroscopic arthrolysis of the DRUJ.
Surgical Technique
Palmar Capsulectomy
A 4-cm skin incision is made just radial to the flexor carpi ulnaris (FCU) tendon starting at the proximal wrist flexion crease. The ulnar artery and nerve can be identified with careful dissection. The artery and nerve can be retracted ulnarly and the digital flexors and median nerve can be taken radially. The ulnar head and volar capsule should now be exposed in the floor of the incision.
An ulnar-based flap of the pathologically thickened capsule is created by beginning the capsulectomy proximal to the volar radioulnar ligament ulnarly and extending to the sigmoid notch. The capsule is incised from distal to proximal. The incision is brought transversely again at the proximal border of the volar sigmoid notch to the ulnar insertion of the capsule. The raised leaf of volar capsule should be resected. Supination should then be reassessed and, if still restricted, more proximal tissue resection may be necessary. The components of the TFCC should be protected throughout the procedure.
Dorsal Capsulectomy
A dorsal capsulectomy is indicated if pronation is limited preoperatively and remains limited after a volar capsulectomy. A chevron or curvilinear incision is made with the apex at the DRUJ and the base ulnarly. After spreading the subcutaneous fat to visualize the extensor retinaculum and capsule ( Fig. 8-6 ), the capsule is clearly evident between the extensor digiti minimi (EDM) and the ECU tendons. The EDM should be partially freed from its compartment and retracted radially. A dorsal capsulectomy should be performed in the same manner as the volar capsulectomy. Always remember to protect the TFCC, particularly the dorsal radioulnar ligament.
The wrist is dressed in a bulky dressing and a volar splint for comfort. Motion is not restricted, but strict elevation is encouraged for the first 48 hours postoperatively. These patients are instructed on hourly pronation and supination exercises, which include passive end-range stretching. Occupational therapy may be helpful but is not always necessary. The dressings are removed at 2 weeks, and patients are allowed to progress with their daily activities as tolerated. Return to full activity can be expected by 6 weeks postoperatively.
Pearls and Pitfalls
Capsular release alone will not provide adequate pain relief in cases of significant arthritis.
Mild arthritis can be successfully debrided (especially if it only involves the proximal joint surfaces).
Either a therapist-directed or a strict home therapy program is essential for a successful result.
Hemiresection Interposition Arthroplasty and Matched Distal Ulnar Resection
The principle behind the Bowers HIT and Watson’s matched distal ulna resection is to remove the cartilage and subchondral bone of the ulnar seat and pole while leaving the ulnar styloid and preserving the attachments of the TFCC. By maintaining the functional integrity of the ulnocarpal and radioulnar ligaments, the DRUJ remains stable. The ulnar carpus is still supported on the triangular fibrocartilage and the triquetrum and lunate remain suspended to the TFC and ulnar styloid via the ulnotriquetral and ulnolunate ligaments. By preserving stability of the distal ulna via these soft tissue attachments, postsurgical strength and outcomes should exceed complete resection of the distal ulna. The main difference between the two procedures is that the Bowers resection is a straight cut (with a saw or osteotome) and the matched resection is a curved cut (with a burr) extending along the radial margin of the ulnar metadiaphysis. Theoretically, this decreases residual impingement from the edges of a straight cut.
Because these procedures are designed to protect all of the components of the TFCC, the major contraindication to performing either procedure would be a nonrepairable TFCC tear resulting in instability. Central tears in the articular disc are often inconsequential after the HIT or matched resection as the ulnar pole is excised and decompresses the tear. One potential problem with both of these procedures is ulna carpal impingement. Some convergence of the ulna and radius is expected (0.75cm, according to Bowers ), which shifts the ulna styloid to a more central position. With ulnar deviation, ulna carpal impingement can result. Ulna-positive variance 2 mm or greater increases the chances of this, and strategies for avoiding this for postoperative stylotriquetral impingement include avoidance of this procedure in ulna-positive wrists, shortening osteotomy of the styloid, or anchovy placement within the resection space of the DRUJ. Although Bowers described using a palmaris longus tendon graft, others have modified the procedure to use any reasonable soft tissue interposition including the DRUJ capsule itself.
Surgical Technique
With the forearm fully pronated, an ulnar-based curvilinear or Brunner incision begins ulnarly 5 cm proximal to the DRUJ, has an apex at the DRUJ, and ends ulnarly approximately 3 cm distal to the ulnocarpal joint ( Fig. 8-7 ). The extensor retinaculum is exposed and the ulnar sensory nerve is identified and protected as it enters the operative field distal and volar to the ulnar styloid ( Fig. 8-8 ). The EDM tendon is evident radial to the proximal ulnar head and the ECU tendon lies ulnarly as they enter the fifth and sixth extensor compartments, respectively. The dorsal DRUJ capsule lies between these two tendons at this level.
The EDM tendon is partially released by longitudinally dividing the roof of the proximal two thirds of the fifth extensor compartment. A proximal, ulnar-based retinacular flap is created by transversely dividing the proximal two thirds of the retinacular flap from the remaining distal one third. The distal one third can be used later to reconstruct the radioulnar ligaments by making a radially based flap if needed. The ECU subsheath is protected as the ulnar head is exposed by carefully dissecting the retinaculum and the overlying capsule ( Fig. 8-9 ). The capsule is divided from the dorsal rim of the sigmoid notch leaving enough tissue for repair at the conclusion of the case. The capsule is divided transversely, proximal to the dorsal radioulnar ligament, and reflected ulnarly if no TFC pathology is expected. Figures 8-9 and 8-10 show the capsular incision to expose the ulnar head, TFC, lunate, and triquetrum.
The ulna head is now ready for resection. Lines of the osteotomy are illustrated in FIGURE 8-11 . The osteotomy is performed with an oscillating saw and an osteotome. The volar margin of the ulnar head is difficult to completely resect, and a laminar spreader may increase visualization. For the matched resection, 3 cm proximal to the ulnar head is subperiosteally exposed. Fluoroscopy is particularly useful as a 3-mm burr contours the distal ulna shaft.
The radius and ulna are axially compressed as the forearm is rotated to assess for impingement of the ulna into the radius. Once the ulnar head resection is deemed adequate, the radius and ulna are again axially compressed while ulnarly deviating the wrist. A shortening osteotomy through the styloid base may be performed if impingement is suspected or an anchovy of palmaris longus can be placed in the resection space. Harvesting the palmaris longus tendon can be easily performed using a tendon stripper through a 5-mm transverse incision in the distal wrist crease. Multiple half hitches in the palmaris increase bulk as necessary, and this “balled” anchovy is secured to the volar capsule.
The dorsal capsule is repaired and the skin is closed over a small drain, which is removed by the patient postoperative day one. Buried 3-0 and 4-0 monocryl sutures and Steri-strips complete the closure.
Postoperative treatment is broken up into passive therapies and splinting followed by range of motion and, last, strengthening. The forearm unit is splinted to prevent pronation and supination to protect the capsular repair. Digital motion is encouraged immediately, but power grip even in the splint should be avoided. Formal hand therapy is prescribed if edema prevents full active and passive digital motion within the constraints of the postoperative dressing. Operative dressings are removed and the wound is checked at 2 weeks; sutures are removed if needed. Neutral rotation posteroanterior radiographs are obtained and a thermoplastic Muenster splint is placed for the next 4 weeks. The patient can remove the splint for showers only. Active and passive wrist flexion, extension, and pronation or supination starts 6 weeks postoperatively and strengthening begins at 8 weeks. An extra week delay before starting pronation and supination may be a good idea if the TFC is repaired.
Outcomes
Literature support for these procedures is generally good because pain relief and range of motion are both reliably improved in primary and posttraumatic arthritis. Some less favorable reports note both relatively high levels of patient dissatisfaction and high incidences of postoperative instability. Although Schober and colleagues supported the Bowers resection, they did report an approximately 40% incidence of instability. The major complication with the hemiresection procedure is stylocarpal impingement. This is best prevented with preoperative anticipation in an ulnar-positive wrist and placement of an anchovy at the time of surgery to prevent ulnar migration of the distal radius. The ulnar styloid may also be excised while maintaining TFCC attachments.
Pearls and Pitfalls
Competent distal radioulnar ligaments are prerequisites for a good result.
Check for ulnar styloid-carpal impingement and address with an ulnar shortening or soft tissue interposition.
Darrach Procedure
Darrach popularized an operation to treat distal radioulnar joint pathology–related pain and loss of motion. Although this procedure predates partial head excision procedures (the Bowers and matched head resection), it remains popular today. Excising the entire ulna head in this operation removes the painful cooptation of the arthritic sigmoid notch and ulnar seat. This procedure is associated with several well-known postoperative complications, which include abutment of the distal radius on the ulnar stump, ulnar stump instability with or without attritional extensor tendon rupture and crepitance, and ulnar translocation of the carpus. Because of these known complications, elderly patients and patients with low functional demands are better candidates for this procedure because repetitive and powerful forearm loading increase instability and abutment.
Several variations on the technique exist, and there is no consensus on how to perform the operation. The ulnar head is excised, but this may be performed subperiosteally or extraperiosteally. The styloid may be osteotomized and left in situ protecting the components of the TFCC, and the remaining ulnar stump may be stabilized or left to scar to local tissues. Dingman noted that patients with good and excellent results had very little bone removed or had bone regenerate to the point where little final discrepancy between the lengths of the radius and ulna existed. Although there are multiple stability augmenting procedures described such as weaving part of the ECU (and FCU) through the end of the ulna or interposing the pronator quadratus between the end of the ulna and the radius, none of these techniques are predictably successful. This may be explained by the biomechanical study by Sauerbier and colleagues demonstrating that none of these techniques affected the tendency for these two bones to converge.
Surgical Technique
A dorsal longitudinal curvilinear incision is centered over the distal radioulnar joint, and the dorsal sensory branches of the ulnar nerve should be identified distally and protected throughout the procedure. The capsule is incised between the ECU and EDM tendons to the distal extent of the ulnar head, and the exposed ulnar styloid can be osteotomized while protecting the dorsal radioulnar and volar ulnocarpal ligaments. The capsular dissection is continued subperiosteally both radially and ulnarly while keeping the ECU subsheath intact. Once exposed, the ulnar neck is ostotomized at the proximal margin of the sigmoid notch and the ulnar head is removed ( Fig. 8-12 ).
The distal ulna can be stabilized with a distally based slip of the ECU tendon. An ECU slip 3 or 4 cm proximal to the osteotomy site should be created and a hole should be drilled 1 to 2 cm proximal to the remaining distal ulna and out the intramedullary canal of the ulna. The tendon slip can be easily fed through the canal distally and out the hole proximally with a Houston suture passer. The tendon stump is secured to itself with the wrist slightly supinated with nonabsorbable sutures. The dorsal capsular incision and periosteum should be repaired if possible. Alternatively, the pronator quadratus can be released from the underside of the ulna and transposed between the end of the ulna and the sigmoid notch. The muscle can be secured to drill holes in the end of the ulna or oversewn into the dorsal capsular tissue.
The wound is closed over a drain with buried sutures and a sugar-tong splint is placed in slight supination. The patient and caregivers are instructed to remove the drain on postoperative day one. Supervised hand therapy is initiated for range of motion and edema control if needed. The sugartong splint is converted to a thermoplastic Muenster splint, again in slight supination, to complete 6 weeks of limited forearm pronation and supination. Strengthening follows range-of-motion exercises and progresses over the next 4 to 6 weeks.
Outcomes
The continued use of the Darrach procedure despite multiple subsequently introduced alternative options should attest to its generally favorable results. The key to a good outcome, as with many other surgeries, seems to be patient selection. Tulipan and colleagues reported on 33 patients (average age of 50 years) who underwent Darrach distal ulna resection for posttraumatic “derangement” of the DRUJ. More than 90% had good or excellent results with pain relief, improved motion, and improved strength. Hansen and colleagues in a similar cohort of patients reported around 80% of patients achieving good pain relief and warned that patients with minimal symptoms may not be good surgical candidates. Fraser and colleagues emphasized patient selection and showed markedly better results in patients with rheumatoid arthritis (86% painfree) as opposed to those suffering from posttraumatic arthritis (36% painfree). Likewise, Schiltenwolf and colleagues found only 13 of 21 patients with posttraumatic arthritis were satisfied following resection of the ulna head. The primary reason for suboptimal results seems to be the development of ulna stump instability, and multiple authors have reported their results of treatment for the “failed Darrach resection.” McKee and Richards, however, noted that although a significant proportion of patients did demonstrate stress induced radioulnar convergence, this rarely correlated with a poor outcome.
Pearls and Pitfalls
Resect as little bone as possible.
Avoid this procedure in laborers or in patients who are very active.
Strip as little tissue as possible to maintain soft tissue stability.
Use soft tissue augmentation (strip of tendon or pronator quadratus) to decrease ulnar stump instability.
Suave-Kapandji Procedure
The Suave-Kapandji procedure combines an arthrodesis at the DRUJ with a pseudarthrosis at the level of the ulnar neck. This combination maintains ulnar carpal support and shifts forearm pronation and supination away from the diseased DRUJ to the level of the osteotomy. This operation eliminates postoperative ulnocarpal translocation that may be seen with the Darrach procedure; however, stump instability is estimated to occur in up to one third of cases. This may be decreased with soft tissue support of the ulnar stump during the index procedure, although many consider this step unnecessary.
This procedure was devised to treat both pain at and instability of the DRUJ and may be a reasonable alternative for healthy, younger patients with posttraumatic arthritis and an intact ulnar head, although stump instability (as seen after Darrach resections) can still be a difficult problem. Additionally, bony healing of the osteotomy is a rare additional complication. Patients who have had fractures of both the distal radius and ulna with a nonunion of the ulnar head fracture are generally better suited for a Darrach procedure augmented by soft tissue stabilization of the proximal stump.
Surgical Technique
The surgical incision and approach are identical to that of the Darrach procedure, although a 2-mm lip of tissue should be maintained for repair. Starting at the ulnar margin, the head should be drilled and tapped for a 4-mm cannulated transfixion screw prior to osteotomizing the ulna. By slightly off-setting this screw distally, a supplemental K-wire can be added to the fixation.
The status of the articular disk of the triangular fibrocartilage and the ulnar variance both determine the width of the osteotomy segment at the ulnar neck. The postoperative gap should be 1 cm long and should extend from the proximal aspect of the sigmoid notch to the remaining distal ulna. The osteotomy length should equal 1 cm plus the length of ulnar positivity, although 2 mm should be added in the case of a neutral variant wrist with an articular disk tear (so the ulnar variance can be “shortened”). The periosteum and bone segment should be excised with a sagittal saw, and the bone should be saved for graft.
The sigmoid notch and the ulnar seat can be decorticated using a combination of burrs, rongeurs, and curettes, and the bone surfaces should be peppered with a K-wire. After positioning the ulnar head at the desired level (with the forearm in pronation), the guide wire for the cannulated screw should be advanced through the previously drilled ulnar head and across the radius. A second K-wire drilled parallel and proximally provides rotational stability and can be removed 6 weeks postoperatively. The radius can be drilled and, after inserting bone graft into the arthrodesis site, an appropriately sized 4-0 mm compression screw is placed across the DRUJ.
The dorsal capsule is repaired and the wound is closed over a small drain. A volar splint is used for comfort. The patient and caregivers should be instructed to remove the drain on postoperative day one. Postoperative edema control and digital range of motion should be emphasized, and supervised hand therapy should be initiated only as needed. The volar splint can be converted to a thermoplastic volar Muenster splint for 6 weeks or until osseous union occurs. Pain limiting activity as tolerated may be allowed. The K-wire should be pulled at 6 weeks and range-of-motion exercises should begin. Strengthening follows when motion is no longer painful. Full activities are expected by 16 to 24 weeks because most postoperative symptoms usually resolve by 3 months.
Outcomes
In general, the literature is supportive of the Sauve-Kapandji procedure, although when the complication of ulnar instability or impingement does occur, it has been historically difficult to deal with. Couturier and Alnot reported on a 42-month followup on 10 wrists having undergone the Sauve-Kapandji procedure for nontraumatic osteoarthritis. All had significant pain relief (7 reported being painfree) and no complications were reported. Voche and colleagues reported less compelling results in a cohort of 21 patients with posttraumatic arthritis. Fourteen results were considered good or excellent, but 7 were poor to fair. Zilch and Kauschke, however, had excellent results (60% improvement in supination, 84% improvement in pronation, and 55% improvement in strength) in 12 patients with posttraumatic arthritis. They emphasized that the key to their success was an arthritic-free radiocarpal joint. Minami and colleagues demonstrated superior pain relief, improved strength, and less complications with the Sauve-Kapandji when compared with Darrach resection, while George and colleagues found no significant difference in subjective and objective parameters between the two procedures. Finally, several studies have reported definite improvements in grip, range of motion, and pain relief, but they noted either high incidences of instability, or, although improved from preoperative levels, still-ongoing functional deficits.
Pearls and Pitfalls
Correct positive ulna head variance.
Predrill and tap the ulna head prior to performing osteotomy.
Excise enough bone (and periosteum) to maintain a 1-cm gap between the ulna stump and the ulna head.
Ulnar Head Replacement
Ulnar head replacement has become an acceptable primary or salvage treatment for disorders at the distal radioulnar joint. Swanson published his report on 73 wrists treated with a silicone ulnar head and stem. Four of these patients were treated for posttraumatic arthritis and resulted in good satisfaction and decreased pain. These results were not sustained, however, because particulate synovitis and implant fracture lead to failure. Further development was spurred by continued frustrations with Darrach and Suave-Kapandji results. Indeed, biomechanical data suggested that this was a logical approach to avoid radioulnar convergence.
Herbert and colleagues developed an ulnar head prosthesis aimed at stabilizing the ulnar stump following failed Darrach resections. They published a 27-month followup study on 23 such patients and found only one failure after prosthetic salvage and soft tissue reconstruction. Fernandez published results on a smaller population of patients treated to salvage failed Suave-Kapandji procedures and again noted decreased pain and improved stability in all patients at an average of 2.6 years postoperatively. Willis and colleagues reported on 19 wrists that underwent endoprosthesis distal ulnar replacement for a variety of etiologies including inflammatory arthritis, posttraumatic changes, and salvage of failed ulna resection procedures. Almost all patients were satisfied and reported significant pain relief. One patient had persistent pain. Complications were rare and included two cases of mechanical loosening, one progression of sigmoid notch arthritis, and one case of progressive instability. Based on these results, many have begun using an ulnar head prosthesis as a primary treatment for DRUJ arthrosis, and, as would be expected, several manufacturers now produce their own versions of this device to replace all or part of the ulna head. Surgical techniques are individualized according to the manufacturers but generally involve a similar approach as described for the Darrach procedure. All emphasize soft tissue stabilization either using available local tissue (TFCC and capsule) or augmenting with allograft or autograft tissue. The sigmoid notch is burred down to accept the ulna head prosthesis if necessary. Although there might be a theoretic concern regarding the interaction of the hard metal (or ceramic) head on the softer bone, this has not seemed to be a clinical problem ( Fig. 8-13 ).
Only the APTIS Medical prosthesis attempts to reconstruct the entire DRUJ and restore stability without significant soft tissue reconstruction. The prosthesis consists of a ulna endoprosthesis semiconstrained in a radial component ( Fig. 8-14 ). The radial component does have a small area for bone ingrowth but is secured to the radius with screws. The inventor, Scheker, reported that pain decreased and strength increased in 49 patients with at least 2 years of followup. A smaller subset reported similar results when either examined or interviewed via telephone at a mean of 6 years. The radial component in particular seems to be at high risk for loosening because of its reliance on screw fixation. So far, this has not appeared to be a problem.
Although these products seem to have promise, at this time there are relatively little clinical data available and widespread use may be premature. Bony alignment needs to be addressed separately, and no matter which prosthesis or soft tissue reconstruction procedure is used, a dislocated DRUJ resulting from proximal radius or ulna malunion cannot be maintained in a reduced position without addressing the malunion itself.
INTRODUCTION AND SCOPE
The etymology of the word “wrist” is the verb to twist. Healthy proximal and distal radioulnar joints allow for twisting or pronation and supination motions, which were critical in mammalian and hominoid development. Almquist likened the importance of distal radioulnar joint (DRUJ) development to the development of both the opposable thumb and the increase in size of the primate brain.
The evolution of the wrist joint has occurred over 400 million years and appears to have developed from changes in pectoral fins from early fish. Fins progressed to multiple-rayed limbs containing a humerus, radius and ulna, and carpus in amphibians and reptiles; the wrist in these species maintained a loadbearing function. Advances in pectoral limb function became relevant when early mammals took to the trees approximately 230 million years ago. The wrist at this point was a syndesmosis, and it was not until almost 200 million years later that pronation and supination were required for primate brachiation, or hand over hand swinging through trees.
The ulna regressed from its articulation with the triquetrum and pisiform and the syndesmosis lead way to the synovial distal radioulnar joint, now isolated from the carpus. Anatomic changes in the carpus seemed to parallel changes in the distal radius and ulna leading to multiple species of primates with different osseous structures and intercarpal motions. Each of these conformations appeared to provide the primate with anatomy most appropriate to their individual existence. The conformation of the human wrist allowed both forearm rotation and flexion and extension in several planes of motion.
Ultimately, then, the development of the wrist and DRUJ resulted in an upper limb that allows us to position the hand in a manner to both make and use tools. These motions and abilities, coupled with our increased intellectual capacity, separate us from other animals. Injuries (or diseases) of the wrist, which disrupt the final product millions of years in the making, may severely limit our capacity to function.
ANATOMY AND BIOMECHANICS
The upper extremity positions the hand in a manner that allows humans to manipulate their environment. The shoulder, arm, elbow, forearm, wrist, and hand are all integral in this regard. Pronation and supination motions are affected through rotation of the radius at the proximal and distal radioulnar joints. The magnitude of the rotation of the radius proximally and distally appears to be matched because rotation of the radius within the sigmoid notch of the ulna proximally essentially equals the rotation of distal radius about the ulna distally. The ulna rotates very little relative to the humerus and “appears to act as a direct extension of the humerus in the supination and pronation plane of motion.” Cone and colleagues demonstrated that the glenohumeral joint can contribute to forearm rotation when the elbow is extended and contributes more to pronation (10 to 45 degrees) than supination (10 to 15 degrees).
The axis of this rotation is from the center of the radial head, at the proximal radioulnar joint, through a dynamic locus distally at, or near, the fovea of the ulnar head. The location of the axis is not fixed distally because there is both dorsal and volar translation of the distal radius about the fixed ulnar seat during supination and pronation, respectively. This places the ulnar seat on the volar rim of the sigmoid notch in supination and more dorsal in pronation.
Osteology
The distal ulna has two named articulating surfaces, the ulnar pole and seat, which make up the ulnar head. The ulnar pole is slightly domed distally and articulates with the undersurface of the triangular fibrocartilage ( Fig. 8-1 ). It slants ulnarly and proximally as it “tips” toward the ulnar styloid. The fovea is a bare area radial to the styloid and is replete with vascular foramina. The ulnar seat is the proximal and radial-most aspect of the ulnar head and is covered in cartilage between 180 and 270 degrees of its circumference. The seat, which articulates with the sigmoid notch of the radius, is an irregular sphere or ellipse with variable degrees of curvature.
The sigmoid notch of the radius is a fairly shallow, rhomboid-shaped structure that accepts the ulnar seat. Dorsal and volar ridges confer slight stability to the joint, whereas a distal ridge separates the radiocarpal joint from the DRUJ. The radius of curvature of the notch is nearly double that of the ulnar head and approximately one fourth the circumference of a circle ( Fig. 8-2 ).
The majority of wear on atraumatic cadaveric specimens has been found on the proximal–dorsal and proximal–central aspect of the sigmoid notch of the radius. The ulnar seat has shown similar wear patterns that extended to the proximal–volar region as well. Wear in these proximal areas seems to be significantly greater than wear more distally on both the radius and ulna. Further, ulnar-positive wrists showed more significant degeneration in these areas, which may be explained by less joint parallelism seen in ulnar-positive wrists.
Studies with pressure-sensitive film have shown that there is an increase in contact area and peak pressure within the sigmoid notch with the wrist loaded axially, radially, and ulnarly. The centroid of contact does shift dorsally in pronation and palmarly in supination, as deduced by Bowers. A relative ulnar shortening as little as 2.5 mm seems to increase peak pressures, and both pressure and contact area increase with shortening from 4 to 6 mm.
Soft Tissues
The shallow sigmoid notch does not adequately constrain the ulnar head, so the soft tissues about the DRUJ—specifically, the components of the triangular fibrocartilage complex (TFCC), the joint capsule, and the interosseous membrane—must contribute. The radioulnar ligaments of the TFCC originate on the dorsal and volar distal rims of the sigmoid notch, blend in with the joint capsule, and have both a superficial and deep insertion on the ulnar styloid. The joint capsule also originates from the dorsal and volar lips of the sigmoid notch and extends ulnarly to encircle the ulnar head. It is indistinct from the ECU subsheath in a groove dorsoradial to the ulnar styloid but is clearly a separate structure than the floor of the fifth extensor compartment, which may be dissected free. The capsule is lax in neutral wrist rotation and reciprocally tightens in pronation and supination. The volar capsule is more robust than the dorsal capsule and has a redundant fold that is able to accept the ulnar head as the radius translates dorsally in supination ( Fig. 8-3 ).
