Fig. 7.1
Computed tomography evaluation of distal radius nonunion after attempted fixation and allograft bone grafting for comminuted open fracture
7.2.5 Treatment
Given the rarity of distal radius nonunions, it is not possible to provide treatment recommendations based on statistical analysis. Instead, each patient should be considered individually, with the appropriate treatment determined by the fracture personality, patient demands, and presence or absence of infection. Nonoperative treatment is typically appropriate only in the setting of elderly patients with very low functional demands. Historically, the most common treatment of nonunion was with wrist arthrodesis. However, advances in implant technology, such as fixed angle volar locking plates, have improved fracture union rates. Open reduction and internal fixation may have a significantly positive impact on upper extremity function through the resulting preservation of wrist motion [1, 14, 15]. Similar to malunited distal radius fractures, patients with nonunion often experience activity limiting pain and instability, with the majority of problems arising from fracture malalignment. In the setting of acute distal radius fractures, the radiographic parameters of radial height, radial inclination, radial tilt, ulnar variance, and articular congruity are used to correct malalignment. These same parameters are useful in the treatment of nonunion. The goal of treatment should be to provide acceptable, stable fracture alignment with a soft tissue envelope devoid of infection and a biologic environment that is capable of fracture healing.
As discussed earlier in the chapter, failure of healing of metaphyseal distal radius fractures is rare. The definition of delayed union and nonunion of the distal radius is not clearly defined in the literature. While the severity of injury plays an obvious role in the rate of healing, one would expect to see radiographic evidence of progressive healing within 3 months after initial injury. Even in fractures with extensive comminution, one would expect evidence of healing after 4 months. When there is lack of progressive healing in the latent nonunion period between 3 and 6 months from injury or initial treatment, continued immobilization and limb disuse are likely to have a detrimental effect on function and range of motion. Further conservative treatment also fails to address the primary problem if malalignment or atrophic changes are present on radiographs. Therefore, we recommend a low threshold to surgical intervention during this time period.
Surgical treatment of nonunited distal radius fractures with multiple fracture fragments is challenging due the osteopenic quality of the bone, potential presence of fracture reabsorption, and limited options for fracture fixation. The majority of these injuries will present after a failed attempt at previous surgical fixation. In this setting, the orthogonal approach to plating as outlined by Fernandez, Ring, and Jupiter can prove useful [1, 16]. The use of a dual plating technique with fixed angle locking plates provides a greater number of fixation points in the distal segment and greater stability in the setting of atrophic or osteopenic bone (Fig. 7.2). Using this technique, the distal radius is approached through a volar or combined volar and dorsal approach, depending on the type of deformity present. The hybrid volar approach proposed by Chhabra et al. can also be utilized to release the carpal tunnel if median nerve symptoms are present preoperatively or if substantial deformity correction or soft tissue contracture may place the median nerve at risk postoperatively [17]. The fracture ends are identified, fibrous tissue and synovial membrane are removed, and sclerotic or necrotic bone is resected. The medullary canal of each end of the metaphyseal component of the fracture is opened to facilitate intraosseous ingress of blood and growth factors for fracture healing. Release or z-lengthening of the brachioradialis and flexor carpi radialis tendons may be required to correct loss of radial height and inclination. An external fixator with 2.5-mm Schanz screws is often used to aid with reduction and maintain alignment prior to internal fixation. Care should be taken to not place Schanz pins where they may interfere with plate fixation. Kirschner wires are used to stabilize individual fracture fragments. Using the Rikli and Regazzoni columnar classification, one plate is placed on the radial styloid and lateral radius to control the lateral column, while a second plate is placed on the volar or dorsal cortex to stabilize the intermediate column [8]. We recommend initial fixation of the more stable column to the radial shaft, as this may aid with determination of alignment for the more complex or comminuted column. Autogenous cancellous bone graft is used to pack the defect. Following fracture fixation, the distal radial ulnar joint should be assessed for congruency and arthrosis. If uncorrectable malalignment or advance arthritic changes of the sigmoid notch–distal ulna articulation are present, a salvage procedure such as a Darrach distal ulnar resection or Bowers hemiresection interposition arthroplasty may be required.
Fig. 7.2
Volar and dorsal dual plating of a distal radius fracture
Ring and Jupiter reported on a total of 23 patients treated with this technique over a 10-year period [18]. At an average of 28-month follow-up, all but one had gone on to a successful union. The one persistent nonunion was eventually treated with a wrist fusion. Two patients were treated with DRUJ salvage procedures (Darrach or Bowers). While patients demonstrated significant improvement in range of motion and function, they never regained normal motion and only 7 of 23 had good or excellent results, according to the rating system of Fernandez. In another group of 10 patients, Fernandez et al. reported similar results [1]. All 10 successfully healed their fractures. Distal ulnar salvage procedures were performed in 4 patients. Average wrist flexion was 50°, wrist extension was 55°, and pronation and supination were 70 and 75°. According to the Fernandez functional result system, there were 3 excellent, 4 good, 2 fair, and 1 poor result.
Given that the majority of distal radius fracture nonunions have undergone previous surgical intervention, failure to adequately address patterns of fracture instability should be considered in the preoperative evaluation. The most common example of this is the failure to recognize and stabilize the volar ulnar corner fragment. While the advance in fixed angle volar plating techniques has overall improved fracture fixation and allowed earlier return of function, it can be difficult to maintain reduction in complex intra-articular fractures with a volar ulnar corner or rim fracture of the distal radius. Stability of the volar ulnar corner is critical to providing structural support to the carpus and failure to maintain reduction leads to volar carpal subluxation or dislocation and catastrophic effects on wrist function [19–21]. The fragment-specific fixation method proposed by Medoff allows use of two or more low-profile implants to strategically capture specific fracture fragments [10]. This technique may be useful in the setting of a latent nonunion before osteopenia and fracture reabsorption have developed. Newer fixed angle, low-profile hook plates may allow more stable fixation of the volar rim in osteoporotic bone, as long as significant metaphyseal comminution is not present [22]. In the setting of significant metadiaphyseal comminution or fracture reabsorption, the use of low-profile implants is contraindicated, but the principles of fracture-specific fixation remain the same and control of the volar-ulnar fragment is critical for stabilization of the carpus.
Dorsal distraction bridge plating is a useful technique in nonunions with extensive comminution and bone loss [23, 24]. Segelman and Clark [2] have suggested that union may not be possible if less than 5 mm of subchondral bone is present beneath the lunate facet, as there is inadequate space available for implant fixation. Dorsal distraction plating alleviates this problem and allows for both correction of severe radial shortening and bridging of osteopenic metaphyseal bone (Fig. 7.3). An initial 4-cm dorsal incision is made over the second or third metacarpal, and the extensor tendon is retracted. Choice of the second or third metacarpal is a matter of surgeon preference and may be influenced by individual fracture characteristics. A 4-cm second dorsal incision is centered over the distal radius, at least 4 cm proximal to the level of fracture comminution. Fluoroscopic superimposition of the dorsal plate can aid with plate selection and positioning of the proximal incision. Typically, a 12 or 14 hole limited contact, dynamic compression locking plate is used. Blunt dissection of the proximal incision between the brachioradialis and second dorsal compartment tendons is performed until the dorsal distal radius is exposed. Care should be taken to avoid damage to the superficial sensory nerve, which emerges from deep to the brachioradialis.
Fig. 7.3
Dorsal distraction (bridge) plating of a distal radius nonunion
If the second metacarpal is chosen, the plate will be placed in the second dorsal compartment, and if the third metacarpal is chosen, the plate will be placed deep to the tendons of the fourth compartment. A Freer or Cobb elevator can be used to create a path from the distal to the proximal incisions, and the plate is slide from distal to proximal, avoiding impingement of the extensors. A cortical screw is placed in the center hole of the plate distally to stabilize it to the metacarpal. Fracture reduction is performed with longitudinal traction to restore length, palmar translation of the hand relative to the forearm to correct radial tilt, and pronation of the hand relative to the radius to counteract supination of the carpus. Once reduction is confirmed, a second cortical screw is placed in the middle hole of the proximal end of the plate. The remaining holes are filled with locking screws. Fluoroscopy and physical examination are used to rule out over distraction. The radiocarpal space should not be greater than 5 mm, and full passive finger flexion should be present. Supplemental fixation, including Kirschner wires and fragment-specific plates, can be used to attempt to improve alignment and articular congruency. Iliac crest autogenous bone graft can be used to fill defects. Following surgery, patients are placed in a short arm splint and digit motion is initiated immediately. The plate is removed at the time of radiographic fracture consolidation, and wrist range motion and progressive strengthening are started.
Mithani et al. [23] evaluated a total of 8 patients treated with this technique, reporting healing in all, with plate removal at an average of 148 days from surgery. Patients reported statistically significant improvement in range of motion and DASH scores from preoperative values. Despite successful healing, this technique has some potential complications. Patients must be instructed that plate immobilization for 5–6 months results in a significant loss of wrist range of motion, which requires committed and prolonged therapy to recover. Additionally, over distraction of the wrist can lead to digit contracture, radial nerve neuritis, and complex regional pain syndrome. Finally, there is a risk of tendon irritation and even tendon rupture if the plate is placed in a position that causes tendon entrapment.
Wrist arthrodesis was historically recommended as first-line treatment for distal radius fracture nonunion (Fig. 7.4) [16, 17]. However, since preservation of even minimal wrist range of motion results in a significant improvement in upper extremity function, it is now more commonly employed as a salvage procedure. It is effective a achieving bone stability when reconstruction is either not possible or not recommended. Potential indications include advanced radiocarpal or midcarpal degenerative changes and extensive bone loss or reabsorption.
Fig. 7.4
a Chronic nonunion of distal radius fracture after volar plating. b Treated with hardware removal and wrist arthrodesis
Management of infection in the setting of nonunion adds an additional layer of complexity. A low threshold should be maintained for the suspicion of infection, especially with the appearance of an atrophic malunion on radiographs. Screening white blood cell count, CRP, and ESR are recommended in all patients. If elevated, CRP and ESR are both independently predictive of infection, and the likelihood of infection increases with each additional positive test [25]. Radionucleotide bone scans have been recommended as an additional screening tool for infection, but they are not cost-effective and do not increase the predictive value in the setting of positive laboratory values [25]. Intra-operative tissue cultures from the nonunion site and any associated purulence can be obtained to provide a definitive diagnosis and aid with antibiotic therapy. There is no literature to guide whether infections of the distal radius with retained hardware can be treated with a single operation or require a staged approach. In the setting of gross contamination, eradication of the infection is advisable prior to proceeding with definitive fixation. An external fixator can be useful in correcting and maintaining alignment, while allowing for repeat surgical debridement. Treatment of an infected distal radius nonunion should be viewed as a collaboration between the hand surgeon and an infectious disease team well experienced in the care of orthopedic infections.
Autogenous cancellous bone graft is used to improve biology and fill gaps created by fracture realignment. The distal ulna, olecranon, and iliac crest can all be used a potential donor sites, depending on the amount of graft needed. In the setting of a large segmental defect, tricortical iliac crest graft can be harvested, but with increased donor site morbidity. Bone graft substitutes have also been developed, including bone morphologic protein, demineralized bone matrix, and synthetics, such as calcium phosphate, calcium sulfate, and hydroxyapatite. While they remove the risk of donor site morbidity, all have significantly increased cost and have not proven superior to autograft bone in fracture treatment [26, 27]. Calcium phosphate grafts have an osteoconductive potential and high compressive strength and may be useful when combined with an osteoinductive substance to fill a large segmental defect.
7.2.6 Postoperative Care
Given that many patients will have significant preoperative stiffness and dysfunction from deformity and prolonged immobilization, early postoperative range of motion should be emphasized, with initiation of digit and forearm range of motion on the morning after surgery. Patients are immobilized in a postoperative short arm splint for a total of 10–14 days. After this, a removable splint can be placed and rehabilitation is initiated, focusing on early progressive range of motion. Strengthening exercises are restricted until there is radiographic evidence of healing, usually 12 weeks from surgery. With more extensive bone loss, healing may be detailed. Patients should be counseled that this is a salvage procedure in the setting of significant preoperative stiffness, deformity, and dysfunction and that recovery of full range of motion and strength is unlikely.
7.3 Distal Radioulnar Joint Instability
7.3.1 Background
The DRUJ is a diarthrodial articulation that acts as the distal stabilizing structure between the radius and ulna. It functions as a pivot point, allowing the radius to rotate round the ulna in supination and pronation. The ligamentous structures, which confer its stability, can be injured in a mechanism similar to that, which produces distal radius fractures. This typically consists of an axial load with wrist pronation and extension, such as a fall on an outstretched wrist. As a result, DRUJ instability can occur either in isolation or the setting of a distal radius fracture [28].
Chronic instability can occur from both a nonunited fracture of the base of the ulnar styloid or a purely ligamentous injury to the TFCC and DRUJ joint capsule. In the latter setting, the instability can be viewed as a consequence of soft tissue “nonunion” of the DRUJ. Given the frequency with which DRUJ instability accompanies a distal radius fracture, as high as 11% in one study, the management of distal radius nonunion and malunion should include a clear understanding of the evaluation and management of this injury [29].
7.3.2 Anatomy and Biomechanics
The articulation between the distal radius through the sigmoid notch and the ulnar head encompasses the bony architecture of the DRUJ. The relative asymmetry of this relationship results in minimal conferred stability. The sigmoid notch is significantly more shallow than the ulnar head, with a radius of curvature that is 50–100% greater (15–19 mm vs. 10 mm) [28, 30]. Given the size mismatch with the ulnar head, the volar and dorsal rims of the sigmoid notch must contribute to stability. Post-traumatic deficiencies of either rim lead to decreased joint stability in biomechanical testing [28, 31–34]. The dorsal rim has an acute angulation, while the volar rim is rounded with a fibrocartilaginous lip [28]. There is significant variation between the coronal and axial alignment of the DRUJ articular surface. In the coronal plane, the joint assumes one of three slopes relative to the long axis of the radius and ulna: parallel, oblique, or reverse oblique [33]. While, at baseline, the shape has no effect on stability or function, changes in relative length of the radius or ulna may result in a mismatch between the articular surfaces and increased contact pressure. For instance, an ulnar shortening osteotomy in a patient with a reverse oblique configuration can result in loading and increased contact pressure in the proximal ulnar head and sigmoid notch [35].
In the axial or transverse plane, there are 4 potential configurations of the sigmoid notch: flat face, ski slope, C type, and S type. The flat notch shape has the least inherent stability and is more prone to failure with soft tissue reconstruction alone in a cadaveric model [36]. The ulnar head is the stable unit of the DRUJ articulation, acting as a platform around which the radius rotates. The contour of the ulnar head articular surface is often slightly asymmetric when compared to that of the sigmoid notch, which can lead to a CAM effect with forearm rotation and further propagate instability with ligamentous injury [28]. The end result of these anatomic factors is that only 20% of DRUJ constraint is provided by the ulnar head and sigmoid notch articulation, with the majority of stability contributed by soft tissue attachments, including the TFCC [32].
Along with the TFCC, the DRUJ capsule, pronator quadratus, extensor carpi ulnaris, and interosseus membrane all contribute to the stability of the DRUJ. The components of the TFCC are the most important in providing stability and maintaining DRUJ kinematics [30, 37]. The TFCC is comprised of several confluent structures that provide distinct functions. They include extending the articular surface of the radius to cover the ulnar head, absorbing and transmitting axial load forces, linking the distal radius and ulna, and supporting the ulnar carpus [28]. The components of the TFCC are the volar and dorsal radioulnar ligaments, volar and dorsal ulnocarpal ligaments, articular disk, meniscus homolog, and extensor carpi ulnar tendon sheath [28, 37]. The radioulnar ligaments contribute the primary stabilizing force to the DRUJ and are necessary for normal stability with volar and dorsal translation. Cadaveric studies have demonstrated that they maintain normal DRUJ joint kinematics after division of other soft tissue stabilizers [38]. Originating from the volar and dorsal aspects of the sigmoid notch, each ligament divides into two limbs in the coronal plane as they extend across the ulna. The deep radioulnar ligament is the more proximal of the two as it attaches to the fovea, a shallow concavity at the base of the ulnar styloid that is bare of cartilage and contains blood vessels that supply the TFCC. The superficial limb courses distally, inserting on the mid-portion of the ulnar styloid [39]. The differing attachment points of the ligaments exert an effect on the stability of ulnar styloid fractures. Fractures of the base of the styloid often indicate instability of the DRUJ from detachment of the deep limbs from the fovea [28].
The precise mechanism by which the radioulnar ligaments provide stability remains in debate, although both ligaments must be present to prevent translation in either direction [28, 32, 40]. In one proposed mechanism, the dorsal radioulnar ligaments act as the primary restraint from dorsal dislocation of the ulna with pronation, while the volar ligament opposed volar escape in supination. This is supported by a cadaveric study measuring ligament strain at the extremes of rotation [40–42]. The other theory is the exact opposite and was developed by observing bone displacement with application of a translation force. In this scenario, the volar ligaments opposing dorsal displacement in pronation and dorsal ligaments countering volar displacement in supination via a tethering effect [32, 43]. Both theories have little effect on clinical management, other than reinforcing the idea that the ligaments exert a synergistic effect and that injury to both ligaments should be expected in the setting of bidirectional or severe unidirectional instability that permits joint dislocation [28, 40].
The articular disk of the TFCC is composed of fibrocartilage, which extends from the articular edge of the distal radius until in blends with the deep volar and dorsal radioulnar ligaments. Its primary function is to bear and transmit compressive loads across the DRUJ and provides minimal stability to DRUJ translation [41, 44]. The deep radioulnar ligaments reinforce the disk by preventing splaying with compressive force [35].
The ECU tendon sheath runs from the dorsal ulnar head to the carpus. It not only stabilizes the ECU tendon, but acts to augment the dorsal DRUJ joint capsule. The volar portion of the TFCC also contains three ulnocarpal ligaments named for the carpal bone to which they insert. These are the ulnotriquetral, ulnolunate, and ulnocapitate ligaments. The ulnotriquetral and ulnolunate ligaments originate from the volar radiolunate ligament, while the ulnocapitate ligament runs more volar and originates from the fovea. They theoretically provide a restraint to ulnocarpal translation and rotation, although their contribution to DRUJ stability is unknown [28]. The meniscus homolog is named for the loose connective tissue that occupies the space between joint capsule, disk, and proximal surface of the triquetrum and provides an unknown function [28].
7.3.3 Clinical Evaluation
Incompetency of the soft tissue stabilizers of the DRUJ manifests clinically as complaints of pain, decreased grip strength and mechanical symptoms [39]. As with any initial assessment, it should begin with a detailed history of the patient’s injury mechanism and attempted treatment. The location, quality, severity, and frequency of pain and instability should be obtained, along with any factors that alleviate or aggravate symptoms. Patients will typically describe a history of a fall on an outstretched wrist or passive forceful wrist rotation, such as with a jammed power tool [28]. Initial ulnar-sided wrist pain that is aggravated by forearm rotation, may, over time, evolve into activity limiting pain, weakness, and mechanical symptoms. Patients with more severe instability may describe a palpable clunk with forearm rotation activities, such as turning a screwdriver [28].
Given that injuries to the radiocarpal, ulnocarpal, lunotriquetral, and proximal radioulnar joints can cause similar symptoms, a comprehensive examination of the affected extremity from the elbow distal is required. The examiner should begin with inspection of the DRUJ, wrist, and forearm, evaluating for swelling or prominence of the ulnar head compared to the contralateral side. Tenderness to palpation of the ulnar styloid can occur in the setting of fracture nonunion. Tenderness of the fovea, located at the soft depression between the flexor carpi ulnaris, ulnar styloid, and triquetrum, can be indicative of a TFCC injury. Active and passive range of motion of both extremities, including wrist motion and pro-supination, should be measured for comparison. Significant crepitus or decreased and painful motion should be noted, as this may be indicative of DRUJ arthritis, which would be a contraindication to a soft tissue reconstructive procedure [45]. The shuck test is performed to assess for stability. The distal ulna is grasped with one hand, while the distal radius is stabilized by the other hand. The ulna is then forcefully translated in a volar and dorsal direction. Pain or increased translation compared to the contralateral side is indicative of DRUJ injury. Translation can vary depending on forearm rotation, so the test should be repeated in supination, pronation, and neutral positioning [28, 45].
Ulnocarpal joint stress testing should be performed to assess for TFCC disk tears and symptomatic ulnocarpal impaction syndrome. The presence of pain with the press test, in which a patient axially loads the wrist by using his or her arms to push up from a seated to a standing position, is indicative of a TFCC tear [45]. The test may also be informative in the setting of DRUJ instability. With attempted press up from the chair, the ulnar head will appear more depressed on the affected side. Maneuvers in which the wrist is taken through a range of motion (flexion–extension and/or pronation–supination) while the wrist is axially loaded in ulnar deviation are also useful in eliciting TFCC and ulnocarpal pathology [28].
ECU subluxation and tendinitis and lunotriquetral (LT) ligament tears can both result in symptoms similar to DRUJ injury. Instability of the ECU can be elicited by the “ice cream scoop” test with rotation of the wrist from a position of pronation and radial deviation to supination and ulnar deviation. Lunotriquetral ligament injury can be examined using the LT shear test. The lunate is stabilized between the examiner’s index finger and thumb, while the other hand provides a volar to dorsal translated force to the triquetrum. A positive test is manifested by pain [28].
7.3.4 Imaging
Initial radiographic evaluation should consist of standard PA and lateral views. Bilateral images are useful for comparison, and care should be taken to insure proper positioning in order to obtain symmetric views. Slight variations in rotation can exert a significant effect on measurement of radiographic parameters. Ulnar variance is best measured using the PA view, although diastasis between the distal radius and ulna, especially when not present on images of the contralateral limb, can be indicative of DRUJ instability. On occasion, a small fleck of bone is avulsed from the fovea, indicating detachment of the deep radioulnar ligaments [28]. In patients with symptoms of ulnocarpal impaction syndrome, the forearm pronated PA or clenched fist view can be helpful in assessing for dynamic ulnar positive variance [46–48]. The goal of an accurate lateral view is for the pisiform to bisect the volar surfaces of the distal pole of the scaphoid and the capitate (scaphopisocapitate lateral view) [28]. While commonly used to assess for DRUJ instability, it is imprecise, as a subluxed ulna can appear reduced and a dislocated ulna can appear subluxed with only 10° of forearm rotation [49]. Suspected instability can be further evaluated by lateral stress view with the patient holding a 5 lb. weight in a position of pronation [50]. Semi-pronated and semi-supinated views allow visualization of the sigmoid notch and ulnar head to assess for fracture, incongruence, and early degenerative changes and osteophyte formation [28]. Radiographs should also be used to assess for a malunited distal radius fracture, which may be the source of DRUJ instability.
Computed tomography can be a useful tool as it is able both to assess the congruency of the distal radioulnar articulation and to evaluate for advanced degenerative changes, which would contraindicate a soft tissue reconstruction. It is most useful in the case of a symptomatic patient with subtle instability [28]. For complete comparison, both wrists should be imaged in identical forearm positions, including neutral, pronation, and supination [28]. Measurement methods utilize the axial images. These include the dorsal and volar radioulnar lines, congruency method, epicenter method, and radioulnar ratio [49, 51, 52]. Numerous studies have demonstrated variability in findings for all methods. So, most authors recommend combing multiple measurements, while continuing to rely most heavily on the patient examination and clinical history [28].
Due to its ability to provide detailed images of the soft tissue structures, MRI is the primary advanced imaging modality utilized in evaluation of TFCC tears in the acute setting. Arthroscopy remains the gold standard for diagnosis of TFCC injuries, but the sensitivity and specificity of MRI continues to improve [28, 53]. In the subacute or chronic setting, the use of MRI is less well defined. Although it has yet to be formally tested, MRI may be useful for assessing attenuation of the TFCC and resulting inability to perform a primary repair in the patient who present weeks or months from initial injury.
7.4 Treatment
7.4.1 Acute Distal Radioulnar Joint Instability
The treatment of acute instability of the DRUJ falls largely outside the scope of a chapter on nonunion of the wrist and hand, but bears mentioning for sake of completeness. The most common cause of acute DRUJ instability is a distal radius fracture. The majority of these injuries will be stable following accurate fracture reduction and stabilization. Following management of the distal radius fracture, stability should be reassessed over a full range of pronation and supination. If stability is maintained in only full pronation or supination, the DRUJ should be pinned in that position. Commonly, dorsal dislocations are stable in supination, while volar dislocations are stable in pronation [28]. If instability persists, then an open repair of the TFCC, which is discussed in detail later in this chapter, is indicated.
7.4.2 Chronic Distal Radioulnar Joint Instability
The goals of any treatment for DRUJ instability should be restoration of stability and a full, pain-free range of motion. Although it is unknown if DRUJ instability predisposes a patient to arthritis, chronic instability symptoms will rarely improve without surgical management [28]. Functional bracing has been proposed, which showed effectiveness in decreasing subluxation and improving range of motion [54]. This may be a consideration in lower demand patients. Surgical treatment options include operative fixation of instability resulting from an ulnar styloid nonunion, direct repair of the TFCC, or soft tissue reconstruction. In the setting of chronic instability, the TFCC is frequently irreparable and a soft tissue reconstruction technique is indicated [39]. Less straightforward is the treatment of subacute injuries or subtle instability, in which soft tissue attenuation is less pronounced.
Ulnar styloid fractures are a common finding in the setting of a distal radius fracture, occurring 61% of the time [55]. As discussed earlier, fractures of the tip of the styloid often retain stability of the DRUJ, as the deep volar and dorsal radioulnar ligaments remain intact [28, 56]. Fractures of the base of the styloid may involve both the deep and superficial ligaments and result in DRUJ instability, especially in the setting of significant fracture displacement [28, 29, 57]. Ulnar styloid fracture nonunions are often asymptomatic. If the DRUJ is stable, painful tip fractures can be excised without affecting stability [29, 57]. In the setting of a large fragment and stable DRUJ, excision of a symptomatic fragment should be performed with caution (Fig. 7.5). Stability should be re-assessed, and if the DRUJ becomes unstable, the TFCC should be repaired to the fovea of the styloid, using interosseus sutures [57]. In the setting of DRUJ instability, fixation of a styloid base fracture can be attempted. Numerous techniques have been described, including Kirschner wires, compression screws, mini fragment plates, tension band wiring, and sutures anchors [28]. The implant chosen depends on a combination of surgeon preference and the size of the fragment. DRUJ stability should be re-assessed following fragment fixation and, if instability persists, requires a soft tissue reconstruction procedure.
Fig. 7.5
Chronic ulnar styloid nonunion that remained asymptomatic
With regard to isolated soft tissue injury, tears of the ulnar-sided attachments of the TFCC are most commonly associated with instability of the DRUJ. While tears of TFCC are common in the setting of distal radius fractures, the majority will not cause acute TFCC instability and do not progress if adequately addressed at the time of injury [28]. Both arthroscopic and open repair techniques have been described for repair of TFCC injuries resulting in DRUJ instability. The indications for arthroscopic TFCC repair in the setting of chronic DRUJ instability have not been completely described, and there is concern that soft tissue repair alone may not confer adequate stability. Newer arthroscopic techniques, such as pushlock anchors, which facilitate repair of the TFCC directly to the fovea through a drill hole in the ulna, may be of benefit, but have not been adequately studied in this setting. Open repair is performed through a dorsal approach to the DRUJ between the fifth and sixth extensor compartments, as described by Adams [28]. The extensor digiti mini tendon is mobilized and retracted ulnarly. An L-shaped capsulotomy is then made in the dorsal capsule, with the longitudinal portion of the incision centered over the radial aspect of the ulnar neck and the transverse limb beginning proximal to the dorsal radioulnar ligament. With retraction of the capsulotomy, the TFCC can be visualized.
If amenable to repair, a second transverse capsular incision is made distal to the dorsal radioulnar ligament to visualize the tear. Sutures are passed in either a horizontal or vertical mattress configuration through the peripheral edge of the tear and adjacent joint capsule. Holes are placed in the ulna using K wires or a small caliber drill, facilitating direct repair of the tear to the bone of the fovea. A suture-passing device is valuable in passing the sutures through the bone tunnels. The sutures are then tied over the bone with ulnar reduced in neutral forearm rotation. The dorsal capsule and extensor retinaculum are closed in a single layer, excluding the extensor digiti minimi, which is left superficial to the closure. Following completion of the case, DRUJ stability should be restored. If not, augmentation with a soft tissue reconstruction should be considered.
Soft tissue reconstruction procedures are indicated in the setting of an irreparable TFCC injury. Numerous surgical techniques have been described, which can be divided into the categories of extra-articular linking of the radius and ulna via tenodesis or ulnocarpal sling and intra-articular reconstruction of the radioulnar ligaments. Indirect reconstruction techniques have been studied in a cadaveric model by Adams and Petersen and failed to restore native DRUJ stability or kinematics [58]. However, they may be necessary in the setting of a previous ulnar head resection, when an anatomic reconstruction is no longer possible. These include proposed techniques by Boyes and Bunnell and by Hui and Linscheid utilizing a strip of the flexor carpi ulnaris (FCU) tendon to reconstruct the volar ulnocarpal ligaments [59, 60]. Both techniques raise concern for the long-term stability of the DRUJ due to the unknown contribution to DRUJ stability from volar ulnocarpal ligaments. There is an additional risk of loss of motion from the tethering effect of the tendon [39].
Attempted anatomic reconstruction of one or both radioulnar ligaments has been described in techniques by Scheker et al. [50], by Johnston et al. [61], and by Adams and Berger [31]. In the technique by Scheker et al., a tendon graft is used to reconstruct only the dorsal radioulnar ligament. This raises concern for the long-term stability of the construct, as cadaveric models have demonstrated that both ligaments must be ruptured for instability to occur [62]. Nonetheless, they reported that all 14 patients treated with the procedure were satisfied with their outcome, with no recurrent instability, improved grip strength, and near complete resolution of pain at an average of 1.5-year follow-up [50]. The techniques proposed by Johnston et al. and by Adams and Berger seek to reconstruct both the volar and dorsal radioulnar ligaments with a palmaris longus autograft [31, 61]. Both reported similar midterm results. Johnston et al. [61] reported satisfactory results in 13 of 14 patients, with range of motion at least 90% of the unaffected side in all patients. Adams and Berger reported that patients recovered approximately 85% of the grip strength and wrist motion of the contralateral side [31]. In the both studies, 12 of 14 patients were able to return to their previous level of employment [31, 61].
Similar to open treatment of a TFCC injury, the technique described by Adams and Berger utilizes a dorsal approach to the DRUJ between the fifth and sixth extensor compartments [28, 39]. The extensor retinaculum is divided longitudinally for later repair, and the EDM tendon is mobilized and retracted ulnarly. A dorsal L-shaped capsulotomy is performed, and care should be taken to not violate the ECU sheath. The periosteum of the dorso-ulnar distal radius is elevated, deep to the fourth extensor compartment. Depending on the size of the palmaris longus graft, a 3.2–4 mm cannulated drill bit system is used to place a tunnel in the distal radius from dorsal to volar at a position approximately 5 mm proximal to the lunate fossa and 5 mm radial to the sigmoid notch. The same cannulated drill is used to place a second tunnel in the ulnar beginning in the ulnar neck and exiting at the fovea. C-arm fluoroscopy is valuable in confirming the position of the guide wires prior to drilling. A whipstitch is placed in each end of the graft, and a suture passer is then used to weave the graft through the radius and ulna. The remaining limbs of the graft are passed around the subcutaneous border of the ulnar neck and tied into place with the ulna reduced and the forearm in neutral rotation. Care should be taken to insure that branches of the ulnar nerve are entrapped in the construct. Additionally, if the graft is not long enough to pass around the ulna after passing through the ulnar tunnel, a biocomposite interference screw can be utilized to stabilize the graft within the ulnar tunnel [28]. The dorsal capsulotomy and extensor retinaculum are closed in a single layer, and the EDM tendon is left superficial to the capsular closure.
In patients with flat face alignment of the sigmoid notch or who have sustained a fracture of the rim of the sigmoid notch, an osteoplasty can be considered as an isolated or complimentary procedure to prevent dorsal subluxation of the distal ulna [28]. Axial computed tomography images can be useful in assessing notch alignment and deformity [28]. The procedure proposed by Wallwork and Bain can be combined with reconstruction of the TFCC ligaments [63, 64]. The distal radius is accessed through a dorsal approach to the DRUJ. Osteotomes are used to make 2 parallel transverse osteotomies in the dorsal ulnar corner of the distal radius, one just proximal to the subchondral surface and the second at the proximal edge of the sigmoid notch. A third, longitudinal cut is then performed connecting the parallel osteotomies 5 mm from the sigmoid notch. This produces a thin osteocartilaginous flap, which can be backfilled with cancellous bone graft from the distal radius. To this point, only a case report and a technique article have been published on this subject. Clinical trials would be beneficial to determine long-term results.
7.4.2.1 Postoperative Management
Following soft tissue reconstruction, patients are immobilized in a long are splint for 3 weeks in neutral forearm rotation. At 3 weeks, the splint is removed and they are converted to a short arm cast and limited forearm rotation is permitted for an additional 3 weeks. The patient is then converted to a removable wrist brace to be used for an additional 2 months. Therapy is initiated with active and gentle-only passive wrist flexion, extension, pronation, and supination. Strengthening is started early, with care taken to avoid high forces with the arm in full pronation and supination. More aggressive passive range of motion and strengthening are delayed until the 4-month mark, with the goal of recovering 85% of native forearm rotation by 6 months. Return to activities and lifting greater than 5 lbs is delayed until at least 4 months post-surgery [28, 31].
7.5 Carpal Bones
7.5.1 Scaphoid
7.5.1.1 Background
The scaphoid is the most commonly fractured bone in the carpus, accounting for between 60 and 70% of all carpal bone fractures [65]. Fractures most frequently affect a young, active, male patient population. In a study of US military personal, the incidence was 121 per 100,000 person-years, with fractures most commonly occurring in males ages 21–24 [66]. Achieving union is of paramount importance, as fractures that fail to heal progress to a predictable pattern of disability, carpal collapse, and eventual radiocarpal arthrosis. Healing of these injuries is a complex process, influenced by fracture location and orientation, displacement, and vascular supply to the scaphoid. As a result of the ligamentous connections between the bones of the carpus, a healing scaphoid fracture is subjected to significant shearing and bending forces [65]. Despite this, nondisplaced or minimally displaced fractures that involve the body of the scaphoid and distal can be treated with rigid immobilization in a cast with expected union rates reported at greater than 90% [67]. Delayed diagnosis, fracture displacement greater than 1 mm, angulation greater than 15°, proximal fracture location, and evidence of osteonecrosis on radiographs represent risk factors for nonunion and are commonly used as indications for surgical management. The rate of union after acute surgical management has been reported in several meta-analyses and approaches 100% [68–72]. As a result, correct initial assessment and management of these fractures is of paramount importance. When fractures fail to heal as expected or present in a delayed fashion care of the nonunited scaphoid can prove challenging. The correct approach to a delayed union or nonunion of the scaphoid is a topic of continuing research and debate among hand specialists and will be discussed in this section.
7.5.1.2 Anatomy and Biomechanics
The bones of the carpus are aligned in two matching rows, supported by both intrinsic ligaments and a complex system of volar and dorsal extrinsic ligaments. The scaphoid has a complex three-dimensional anatomy, closely resembling a peanut, with articular cartilage covering 80% of its surface. It is the only carpal bone that bridges both carpal rows. There are three anatomic regions into which the bone is divided: the proximal pole, waist or body, and distal pole or tubercle. The proximal pole articulates with scaphoid fossa of the distal radius and the lunate, while the distal pole forms the scapho-trapezial-trapezoid articulation. The bone of the proximal pole is the most dense, as it transmits axial load across the carpus from the distal radius. In contrast, the bone of the waist has the lowest density, which may explain why a majority of fractures occur in this region [73, 74]. Morphologic evaluation has demonstrated that male scaphoids are longer than those of females, which may have an impact on screw length with surgical fixation [73].
As a result of the scaphoid being almost entirely covered with articular cartilage, there is minimal space for perforating blood vessels to enter. This unique anatomy results in a complex blood supply. A cadaveric study performed by Gelberman et al. determined that approximately 80% of blood flow was provided via a branch of the radial artery entering the dorsal ridge at the scaphoid waist and supplying the proximal pole in a retrograde fashion. The remaining 20% is supplied by further volar radial branches entering the distal pole. The tenuous blood supply of the proximal pole results in a unique susceptibility to nonunion and avascular necrosis following fractures of the scaphoid waist or proximal [75].
The precise mechanism by which a scaphoid fracture occurs has not been clearly elucidated, although it appears to be a combination of axial load and either wrist hyperextension or, less commonly, wrist flexion [76, 77]. As described earlier, healing potential is dependent on a number of factors including location, displacement, angulation, and vascularity [28]. Intramembranous ossification is the mechanism by which scaphoid fractures heal. The resulting lack of protective callus formation renders the scaphoid susceptible to mechanical forces throughout the healing process. This can lead to fracture displacement or angulation if proper immobilization or stabilization is not provided. A scaphoid waist fracture is exposed to a combination of bending, shearing, and translation forces. Axial load applied to the wrist prior to fracture healing will result in progressive flexion and pronation of the distal pole. Over time, the distal pole will continue to angulate as volar bone is reabsorbed, leading to a “humpback deformity.” This is further compounded by the limited blood supply of proximal fractures. The combination of fracture displacement, angulation, and absent blood supply all contribute to the development of a nonunion and eventual avascular necrosis [28].
If left untreated, scaphoid nonunion leads to a predictable pattern of degenerative arthritis within the radiocarpal and midcarpal joints known as scaphoid nonunion advanced collapse (SNAC). The scaphoid is a vital link between the proximal and distal carpal rows. As a result, scaphoid nonunion leads to a significant disruption of carpal mechanics. In a normal wrist, the scaphoid and lunate are connected by the scapholunate interosseus ligament, which draws the lunate into a flexed position with the scaphoid with wrist radial deviation. The volar collapse of the distal pole in a humpback deformity results in reduced carpal height. With radial deviation, the lunate continues to extend along with the proximal pole of the scaphoid, while the distal pole remains in a flexed position. Over time, the resulting dorsal intercalated segmental instability (DISI) pattern becomes fixed and the progression of degenerative changes is similar to that observed in a scapholunate ligament deficient wrist. Degenerative changes begin in the radial styloid articulation with the scaphoid before spreading to the entire radioscaphoid, radiolunate, and scaphocapitate joints, and ending in pancarpal arthritis. Patients may be initially asymptomatic, but will eventually develop progressive activity-related pain. In one study, 97% of patients with at least a 5-year history of scaphoid nonunion demonstrated degenerative changes on radiographs [78].
7.5.1.3 Clinical Evaluation
The evaluation of patients with known or expected scaphoid nonunion should begin with a detailed history. Most patients will often present with pain, stiffness, or inability to resume normal activities beyond the period of time one would expect for fracture healing, while a subset will remain asymptomatic. Although it can be difficult, an onset of injury should try to be obtained. Occasionally, patients will not be able to recall a specific event, but rather a decrease in function, onset of pain, or loss of motion. Clinical records should be reviewed to determine any previous treatment. In the case of closed management, the duration and type of immobilization use should be obtained. For patients treated with surgery, the approach and type of fixation used are beneficial for later preoperative planning. Although the majority of these patients are young and active, a complete medical history should be obtained. Particular attention should be applied to use of tobacco products. While not an absolute contraindication to surgery, their use is a risk factor for nonunion and the patient should be counseled for and offered help with tobacco cessation [79, 80].
The physical examination should attempt to localize the source of pain in as gentle a manner as possible. Wrist range of motion should be obtained and compared to the contralateral side. While pain is not always localized to the anatomic snuff box area or either pole of the scaphoid, diffuse pain and significantly decreased range of motion should alert the examiner to the possibility of advanced degenerative changes.
The goal of the radiographic evaluation should be to determine the degree of healing, alignment, and vascularity of the fracture, as well as any evidence of degenerative changes. Initial radiographs should include standard posteroanterior, lateral, 45 degree pronated oblique, and navicular (PA in wrist ulnar deviation) views. They may reveal sclerosis, cyst formation, bone reabsorption, fracture displacement or angulation, or hardware loosening or failure. The lateral radiographs can also be used to evaluate for a DISI deformity, with a scapholunate angle >60° or a radiolunate angle >30° [81, 82]. If present, it factors into preoperative planning, as correction of both the alignment of the scaphoid and the normal scapholunate relationship can be challenging [83]. All previous radiographs, including initial injury films, should be reviewed to determine the progression of healing and any evidence of progressive fracture displacement or angulation.
Computed tomography (CT) scans provide the most detailed images of the osseous anatomy and can be useful in determining nonunion in the setting of equivocal radiographs. CT has demonstrated high intra-observer reliability in determining displacement and fracture union (Fig. 7.6) [84]. CT can also provide valuable information regarding bone reabsorption following collapse and early evidence of degenerative changes. CT images are used to determine angulation of the scaphoid with the lateral intrascaphoid angle or height-to-length ratio on sagittal images [84]. For accuracy, the CT should be oriented perpendicular to the long axis of the scaphoid, rather than the wrist [85]. The normal lateral intrascaphoid angle is 24°, while an angle greater than 45° is predictive of an increased risk of arthritis, even in healed fractures [86]. Although the height-to-length ratio has demonstrated a greater intra-observer reliability than the intrascaphoid angles, the clinical significance of this is unknown. Scaphoid collapse is considered significant with a height-to-length ratio greater than 0.65 [87, 88]. CT can also evaluate for technical errors, such as screw misplacement and inadequate fracture reduction and compression. Current CT protocols with metal suppression are useful in minimizing hardware artifact. While not as effective as MRI, CT can predict proximal pole osteonecrosis through increased radio-opacity of the proximal pole and lack of bridging trabeculae between fracture fragments [85, 89].
Fig. 7.6
Computed tomography scan showing nonunion of a scaphoid waist fracture previously treated with screw fixation
Due to the unreliability of radiographs in predicting osteonecrosis, MRI plays a key role in the preoperative evaluation of scaphoid nonunion. Studies have established MRI as the most effective imaging modality in determining vascularity of the proximal pole (Fig. 7.7) [90–93]. It can also be effective in diagnosing occult scaphoid fractures and determining the degree of devascularized bone in patients who have undergone previous surgical treatment [83]. Decreased or absent signal intensity on T1 and T2 weight images has been associated with compromised vascular supply [93]. Patients with this finding on preoperative MRI demonstrated suboptimal healing rates when not treated with a vascularized bone graft [93]. Additionally, a clinical study has directly correlated absence of T1 signal on MRI with the presence of osteonecrosis, empty bone lacunae, and poor uptake on bone scan within intra-operative bone biopsy specimens [93]. While MRI is unnecessary if plain radiographs clearly demonstrate osteonecrosis, it is recommended to completely evaluate for the presence of osteonecrosis in any waist or proximal pole fracture with an established diagnosis of nonunion.
Fig. 7.7
Magnetic resonance image of scaphoid nonunion with signal changes on t1 and t2 consistent with avascular necrosis of the proximal pole
7.5.1.4 Treatment
Surgical treatment is indicated in the setting of nonunion, as spontaneous healing is extremely rare [94]. The addition of cast immobilization and/or pulsed electromagnetic field treatment with a bone stimulator does not result in predictable consolidation once the diagnosis of nonunion has been established [95]. The healing rate was only 69% with the use of casting and bone stimulators in nondisplaced nonunions without radiographic evidence of osteonecrosis [95].
Delayed union represents a category of fracture that merits individual discussion. Although there is no clear definition of delayed union, it should be considered when radiographs fail to demonstrate expected progression of healing. Initial conservative treatment of nondisplaced fractures of the waist or distal pole is a reasonable approach. However, surgical intervention should be strongly considered when radiographs fail to show signs of healing after 6–8 weeks of immobilization and certainly by 12 weeks. Determination of healing can be difficult due to the lack of callus deposition, and a CT scan may be necessary for definitive evaluation. This is especially prudent in athletes and young laborers, as research has demonstrated faster return to play and work and decreased overall medical cost with early surgical intervention [96, 97]. Also, prolonged long arm cast immobilization can lead to elbow and wrist stiffness, exerting its own negative impact on function and quality of life. Further, management of delayed union without bone reabsorption, collapse, or osteonecrosis is technically less demanding and may be accomplished with compression screw without the need for bone graft. Whether initial patient presentation is acute or delayed, fracture displacement greater than 1 mm, fracture comminution, fracture of the proximal pole, fracture angulation as manifested by an intrascaphoid angle greater than 45° or height-to-length ratio greater than 0.65, and poor patient compliance all represent predictors of eventual non- or malunion and warrant immediate surgical management [86, 87, 98].
In the setting of established nonunion, the majority of authors recommend open reduction and internal fixation of the fracture with bone graft (Fig. 7.8) [98–102]. Throughout the evolution of surgical stabilization, a number of implants have been used, including Kirschner wires, staples, plates, and compression screws. The implant of choice must be capable of withstanding shearing forces with disrupt fracture healing. Kirschner wires lack the compressive strength necessary to maintain fracture reduction, while the use of staples and plates, although displaying satisfactory healing rates with acute fractures, raise concern hardware impingement and damage to the surrounding articular cartilage and often require later hardware removal [103, 104]. New mini-plate technology may alleviate some of these concerns, while theoretically provided increased torsional stability compared to a screw [105, 106]. Nevertheless, compression screws remain the mainstay for current treatment of acute scaphoid fractures and nonunion. Herbert developed the initial headless screw. Even without a compression design, they reported a union rate of 100% for acute fractures and 83% overall [107]. Subsequent advances have demonstrating increased compression through a partially threaded or fully threaded, variable pitch design. The addition of a cannulated system utilizing guide wire placement under fluoroscopic guidance has improved accuracy of screw placement. Studies have demonstrated that accurate screw positioning is critical, with the greatest stability imparted by a screw positioned in the center–center position of the bone on PA and lateral views or perpendicular to the fracture line [108, 109]. Additionally, studies by Trumble et al. reported that screw placement within the central third of the proximal pole reduced time to union by 50% [81, 109, 110]. Several companies have now developed compression screws, and little data exists comparing their effectiveness. Therefore, screw choice remains largely dependent on surgeon preference.
