Management of Lost Pronosupination

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CHAPTER 53 Management of Lost Pronosupination

Pronosupination is important in most activities of daily living. A loss of forearm rotation may be compensated by internally or externally rotating the humerus with the elbow semiextended, but this implies a high risk of developing degeneration of the rotator cuff. Without pronosupination, numerous common tasks, such as pouring water from a pitcher into a glass, or fastening a brassiere, are extremely difficult. A forearm with limited pronosupination is a substantial handicap, almost as serious as an unstable distal radioulnar joint (DRUJ).

For a full forearm rotation, not only do proximal and distal radioulnar joints need to be well aligned, with matching lengths and congruent cartilages, but also the soft tissue stabilizing structures must function properly.¹^–³ Pronosupination is a multifactorial phenomenon that can be affected in many different ways, the more common being distal radius misalignment, radioulnar length discrepancy, joint incongruity, and soft tissue (capsule or muscle or both) contracture.⁴

As in any other complex problem, treatment of DRUJ stiffness is based on a thorough clinical examination and adequate radiographic investigation of the cause of the problem. Properly obtained lateral radiographs and axial tomograms are helpful in assessing the spatial relationship of the bones involved. Arthroscopy is an excellent tool to evaluate the status of all intracapsular soft tissues involved in pronosupination, whereas magnetic resonance imaging provides information on the extracapsular DRUJ stabilizers.

Frequently, the loss of supination is secondary to a dorsally malunited distal radial fracture. In such instances, if the triangular fibrocartilage complex (TFCC) has been stretched out or avulsed off the basistyloid fovea, the ulnar head is forced into a dorsally subluxed position relative to the sigmoid notch. Such joint incongruity prevents the normal combination of joint spinning and gliding necessary for a full forearm rotation. Treatment in these cases consists of a radial corrective osteotomy.⁵

In other circumstances, the ulna may be excessively long as a result of trauma (shortened distal radial fracture) or a congenital defect, and may impinge the lunate during supination and wrist extension, producing pain. Such an abutment may explain a reduced range of forearm rotation. In these cases, any form of ulnar length reduction (i.e., ulnar shortening osteotomy or wafer procedure) is mandatory.⁶

If the lack of rotation is due to joint incongruity secondary to trauma or cartilage degeneration, many different options exist ²: (1) total ulnar head resection,⁷ (2) “matched ulna” resection,⁸ (3) hemiresection and fibrous interposition,⁹ (4) DRUJ fusion plus creation of a metaphyseal pseudarthrosis,¹⁰ (5) ulnar head implants,^11,¹² and (6) total DRUJ prosthesis.¹³ All of these options are discussed elsewhere in this book, so they are not covered here. This chapter concentrates on the loss of forearm rotation secondary to soft tissue (capsular or muscle or both) contracture.

Pathomechanics

To understand the consequences of specific DRUJ soft tissue contractures, it is important to analyze how the radius is prevented to rotate around the ulna beyond its normal limits.

Supination Constraints

As the radius rotates from neutral toward supination, very few changes in ligament tension appear in either the palmar or the dorsal radioulnar ligaments. The horizontal portion of the TFCC, consisting of the articular disc (central zone) and the two peripheral radioulnar ligaments, moves as a unit (Fig. 53-1A and B).^3,¹⁴ Tension in the palmar radioulnar ligament does not increase until a certain degree of supination is reached (Fig. 53-1C). At this point, the distance between the two ends of the ligament (fovea and palmar corner of the radius) starts increasing until the palmar radioulnar ligament is fully taut, at about 70 degrees of supination.¹⁴ If the palmar capsule was not elastic, that would be the limit of supination. The capsule is very lax, however,¹⁵ and allows some degree of dorsal subluxation of the radius, with the ulnar head displacing palmarward, decreasing tension in the anterior radioulnar ligament (Fig. 53-1D). This decrease in tension allows further supination up to about 80 degrees, until the dorsal radioulnar ligament becomes fully taut.¹

FIGURE 53-1 Schematic representation of the interaction that exists between the distal radioulnar joint and the surrounding soft tissues during supination. A and B, As the radius initiates a rotation around the ulna, very few changes in tension of the palmar and dorsal radioulnar ligaments appear. C, Tension in the palmar radioulnar ligament does not increase significantly until a certain degree of supination is reached (yellow arrow). This tension generates a palmar translation vector to the ulnar head. D, As the ulna subluxes palmarly (white arrow), the dorsal radioulnar ligament becomes taut (yellow arrow), preventing further displacement. The palmar radioulnar capsule (in pink) helps in stabilizing the joint at the extreme of supination and the pronator quadratus muscle (in green).

An important dynamic control of the final stages of supination is the pronator quadratus, which in supination becomes stretched and promotes coaptation of the joint, avoiding its subluxation (Fig. 53-2).^3,^16,¹⁷ The palmar radioulnar ligament can be thought of as the primary stabilizer of the early stages of supination,¹ whereas the dorsal radioulnar ligament,¹⁴ the palmar capsule,¹⁵ and the pronator quadratus muscle^16,¹⁷ are secondary stabilizers avoiding dorsal dislocation of the radius relative to the ulna.

FIGURE 53-2 The pronator quadratus muscle is fully stretched during supination, increasing its mechanical advantage as distal radioulnar joint dynamic stabilizer. If this muscle sustains a disruption, it is most likely to occur during supination. In pronation the muscle belly of the pronator quadratus does not offer resistance to a palmar displacement of the ulnar head.

Pronation Constraints

A similar phenomenon occurs during pronation: No substantial changes in tension develop in the two radioulnar ligaments until a certain degree of pronation is achieved (Fig. 53-3A, B). At about 60 degrees of pronation, the dorsal ligament becomes maximally taut (Fig. 53-3C).¹⁴ This would stop pronation if it were not for the elastic dorsal capsule, which allows some palmar subluxation of the radius relative to the ulna. As the ulna glides dorsally, there is increasing tensioning of the anterior radioulnar ligament and the dorsal capsule, the two ultimate constraints of pronation (Fig. 53-3D).¹

FIGURE 53-3 Soft tissue interaction around the distal radioulnar joint during pronation. A and B, Rotation around the neutral position does not imply significant changes in tension of the radioulnar ligaments. C, The dorsal radioulnar ligament becomes taut (yellow arrow) before reaching the extreme of pronation. With this, the ulna is forced toward the dorsum. D, As the ulna subluxes dorsally, the palmar radioulnar ligament becomes taut preventing further displacement. The dorsal radioulnar capsule (in pink) and the extensor carpi ulnaris tendon (in green) stabilize the joint at the extreme of pronation.

The extensor carpi ulnaris muscle has a similar role to that of the pronator quadratus in that it is an effective dynamic stabilizer of the DRUJ during pronation. As emphasized by Spinner and Kaplan,¹⁸ the extensor carpi ulnaris tendon is maintained in a close relationship with the head of the ulna by a fibrous tunnel, independent from the rest of the extensor retinaculum. Because of this, at full pronation, the extensor carpi ulnaris tendon lies medial to the ulnar head and promotes coaptation of this bone against the dorsal rim of the sigmoid cavity, maximizing stability (Fig. 53-4).^3,¹⁸ The dorsal radioulnar ligament can be thought of as the primary stabilizer of the early stages of pronation,¹⁴ whereas the palmar radioulnar ligament,¹ the dorsal capsule,¹⁵ and the extensor carpi ulnaris muscle¹⁸ are secondary stabilizers avoiding palmar dislocation of the radius relative to the ulna.

FIGURE 53-4 Mechanism of stabilization of the distal radioulnar joint by the extensor carpi ulnaris tendon. The extensor carpi ulnaris has its own compartment over the groove on the dorsum of the ulnar head. The sheath that covers the tendon is independent from the extensor retinaculum. In pronation, that compartment is located on the medial aspect of the bone. The tendon in that position has an S-shaped configuration. Contracture of the extensor carpi ulnaris muscle produces a radial directed force that compresses the joint and helps prevent a dorsal subluxation of the ulna relative to the radius.

Clinical Forms of Soft Tissue Contractures around the Distal Radioulnar Joint

Contractures around the DRUJ may cause three forms of forearm limitation: (1) loss of pronation, (2) loss of supination, and (3) combined pronation and supination loss. The third form of forearm limitation, combining pronation and supination losses, usually falls into the category of intra-articular stiffness (arthrofibrosis), and often results from complex trauma or inflammatory disease generating intra-articular cartilage destruction and invasion by scarring fibrotic tissue.² This is a difficult condition to treat effectively and most often requires a salvage intervention.⁴ It is rarely seen after a common distal radial fracture. If releasing an arthrofibrotic joint is believed to be necessary, however, a double palmar and dorsal approach following the guidelines proposed by Kleinman and Graham¹⁵ is recommended (see later).

Loss of Pronation

Of the four structures the scarring or contracture of which may theoretically affect pronation (see Fig. 53-3D), only the dorsal capsule is shown to be directly involved in the rare cases where there is truly an isolated lack of pronation owing to soft tissue contracture.¹⁵ The dorsal capsule may disrupt, lose its elasticity, and become thick in several ways; most often, this occurs as the consequence of an extra-articular, palmarly angulated distal radial fracture (Smith type), or in Galeazzi’s fracture-dislocation.⁴ If the fracture is not properly reduced and stabilized, and particularly if the forearm is immobilized in an above-elbow cast for too long, these injuries may induce a deficit of pronation. Plate fixation and early mobilization of these types of fractures is common practice because the need for a secondary dorsal capsular release is almost anecdotic.

Permanent scar retraction of a partial injury to the radioulnar ligaments producing limitation of forearm rotation is very rare. When they fail, these ligaments tend to avulse or disrupt creating instability, but seldom stiffness.¹⁹ Detaching the radioulnar ligaments to achieve increased pronosupination should be considered only exceptionally.

Extensor carpi ulnaris tendinitis may result in muscle contracture and slight limitation of pronation.²⁰ Reduction of forearm rotation is not static, but most often the result of pain produced by the synovitic tendon when stretched during pronation. Proper treatment of the condition (e.g., splinting, glucocorticoid injections, eventually a synovectomy) is all that is needed to recover full pronosupination.

Loss of Supination

Post-traumatic palmar capsular thickening inducing a supination deficit is common.¹⁵ Distal radial fractures with mild dorsal displacement are particularly prone to create DRUJ capsular defects in the palm, which may eventually cause this problem. The reason for it is as follows.

The hyperextended carpus pulls the ulnar head anteriorly by means of the strong ulnocarpal ligaments (Fig. 53-5).³ As the distal radius displaces dorsally, a shear stress in the DRUJ is created. If the TFCC, including the ulnocarpal ligaments, does not fail, the ulnar head promotes tearing of the palmar capsule in its attempt to sublux palmarly relative to the dorsally angulated distal radius. If, in addition, there is a supination moment involved in the injury, the fully stretched pronator quadratus muscle may be unable to resist the palmar push of the ulna, and may sustain substantial elongation. Such muscle injury would not have major consequences, however, if not for the fact that this muscle is contained in its own small compartment,^21,²² which the fracture fills with abundant hematoma, creating the conditions for a localized compartment syndrome.^23,²⁴ Increased pressure on the muscle may seriously affect its contractability, inducing its later fibrotic retraction and subsequent limitation of supination.

FIGURE 53-5 Most palmar capsular derangements, eventually resulting in a deficit of supination, are the result of distal fractures without detachment of the triangular fibrocartilage complex (TFCC). If the ulnocarpal ligaments maintain the normal origin of the TFCC into the fovea, wrist extension promotes a palmar translation of the ulna relative to the radius. If there is a concomitant dorsal displacement of the radius, the ulnar head protrudes further palmarly and may disrupt the palmar capsule. By contrast, if there is avulsion of the TFCC, including the ulnocarpal ligaments, there is no palmar translation force to the ulna, and the chances for a palmar capsular derangement are minimal.

As stated earlier, supination contractures usually appear after poorly displaced distal radial fractures. This can be easily understood by considering the pathomechanism of injury. The deep fascia usually is disrupted in badly displaced fractures. This disruption eliminates the possibility of a pronator quadratus compartment syndrome and later pronator quadratus muscle retraction. If the fracture is grossly displaced, the TFCC is most often pulled off the ulna. With this, the antepulsion vector created by the ulnocarpal ligaments onto the ulna no longer appears. As a consequence, the ulnar head does not cause any substantial volar capsular disruption, eliminating the chances for later scar retraction and lack of supination.

Management of Distal Radioulnar Joint Soft Tissue Contracture

The management of a patient with reduced pronosupination depends on the chronicity of the problem and the location of the structures involved. As stated earlier, if there is bone deformity or joint incongruity, this needs to be resolved first. No soft tissue release would ever correct a bone-related stiffness problem. If this problem has been ruled out, an aggressive supervised therapy program is always recommended. The aim is to recover progressively the elasticity of all retracted structures through deep massage, gentle passive mobilization, and application of passive splints with progressive rotation angles. Dynamic splinting also may be considered. Failing this, surgery is indicated.

Distal Radioulnar Joint Capsular Release

A volar approach to the DRUJ capsule is usually performed through a 5-cm longitudinal or zigzag incision along the medial border of the flexor carpi ulnaris tendon. Alternatively, the joint may be approached through a longitudinal incision along the interval between the ulnar neurovascular bundle and the flexor digitorum tendons (see Fig. 53-6D). In the first case, a careful dissection and protection of the dorsal branch of the ulnar nerve is mandatory. Gentle retraction of the neurovascular bundle allows exposure of the deep fascia that covers the pronator quadratus muscle. Complete fasciectomy of the area covering the DRUJ is recommended. Excision of the volar capsule is accomplished, as described by Kleinman and Graham,¹⁵ by first incising its insertion on the radius. A second transverse incision paralleling the proximal margin of the palmar edge of the TFCC is then made. The proximal border of the capsule is cut, circumscribing the area of the ulna covered by cartilage. With this, a volar “silhouette” resection of the DRUJ capsule is excised, while protecting the articular surfaces of the distal ulna and sigmoid notch of the radius (see Fig. 53-6F).¹⁵ At this point, if the only problem is capsular thickening, full passive supination should be obtained. If there is still a lack of supination, the procedure needs to address the associated pronator quadratus muscle problem.

When there is a true pronator quadratus muscle contracture owing to muscle disruption, its distal and ulnar fibers usually appear whitish and fibrotic (see Fig. 53-6E). By contrast, when contracture is the consequence of a localized compartment syndrome, the entire muscle looks fibrotic and does not contract when stimulated with the scalpel.^23,²⁴ In the first instance, the superficial belly of the muscle is detached off the ulna, and its fibrotic portion is excised. In the second case, the entire muscle needs to be released and extracted.

Aside from capsular and muscle contracture, the joint may have developed arthrofibrosis (intra-articular adhesions) requiring further arthrolysis (see Fig. 53-6G). A blunt Freer elevator is used to unblock the joint until full passive supination is achieved, and the ulnar head can be passively displaced back and forth on the sigmoid notch. Detachment of the foveal insertion of the TFCC is seldom indicated. If liberation of all intra-articular adhesions does not allow full forearm rotation, a dorsal approach is preferred.

The dorsal DRUJ capsule is approached by retracting the extensor digiti quinti from the fifth extensor compartment.²⁵ An ulnar retinacular flap is elevated from the underlying dorsal capsule. The thickened and adhesive capsule is excised following the “silhouette” method of capsulectomy described for the palmar side.¹⁵ After passive intraoperative assessment of forearm rotation and translation of the ulnar head within physiological limits, the dorsal retinaculum is repaired, and all wounds are closed. A bulky compression dressing with an above-elbow supination splint is placed for 1 week, after which patients are encouraged to pursue active hand therapy. Night splints in full supination may be used eventually.

Results

We have recently reviewed six patients (five women and one man, average 36 years old [range 20 to 51 years old]) who had undergone a DRUJ capsular release for a loss of forearm rotation. Three of the six patients had sustained mildly displaced fractures of the distal radius, all having been treated nonoperatively in a cast. One had had a radial head fracture treated with internal plate fixation, one had a direct blow to the palmar surface of his wrist, just proximal to the palmar crease, and the last one had an episode of intense wrist pain after a racket ball game. All patients with a radial fracture had acceptable radial length and congruent articular surfaces at the DRUJ (see Fig. 53-6B).

Careful clinical and radiographic examination excluded any other bone pathology that could affect pronosupination. All patients except one had marked limitation of supination (average 15 degrees [range 0 to 35 degrees]) and an almost normal pronation (average 72 degrees). The patient who had a proximal radial head fracture had supination and pronation limited to less than 20 degrees. All patients had a volar capsular excision, plus detachment of the pronator quadratus muscle. The patient with the radial head fracture required further dorsal capsulectomy to increase pronation. One patient required extensive arthrolysis to remove fibrotic tissue obliterating the empty spaces of a chronic dorsally subluxed DRUJ.

The average interval between injury and surgery was 16 months (range 4 to 30 months). At an average follow-up of 15 months (range 7 to 52 months), patients were evaluated for pain relief, range of motion, and grip strength. Pain relief at rest was obtained in all patients, with two complaining of mild discomfort during strenuous activity. All patients resumed their normal activities except one who had to downgrade the strength level of her job. Average ranges of forearm rotation at follow-up were for supination 68 degrees (84% of contralateral) and pronation 80 degrees (95%). Average grip strength relative to the contralateral normal side improved from 45% to 65%. A case example of the technique and the results obtained is shown in Figure 53-6.

FIGURE 53-6 Illustrative case of a 52-year-old woman who presented with lack of supination 6 months after a mildly displaced distal radius fracture treated conservatively. The patient recalled having had intense pain at the palmar aspect of the wrist after the fracture (possibly pronator quadratus compartment syndrome). A, Clinical photographs of the maximum range of active supination that was present before surgery. Passive motion was identically reduced. B, Neither joint incongruity nor length discrepancy could be blamed for the lack of rotation. C, Transverse magnetic resonance imaging showed retraction of the pronator quadratus muscle. D, The joint was approached palmarly along the lateral border of the flexor carpi ulnaris tendon, taking care to protect the ulnar neurovascular bundle that courses behind the tendon. E, Appearance of the pronator quadratus muscle, with a whitish distal medial corner (arrow) as a result of fibrosis.F, Despite excision of the volar distal radioulnar joint capsule and detachment of the pronator quadratus muscle (arrow), supination was still blocked. G, Elevation of the pronator quadratus muscle disclosed the existence of fibrotic bands within the joint, excision of which allowed recovery of full supination. H, The arm was immobilized in an above-elbow supination splint for 1 week followed by an active program of supervised physiotherapy. In this case, it took 5 months to obtain full active pronosupination. I and J, At 1 year, the range of forearm rotation was still normal and painless.

Our results are similar to the results published by Kleinman and Graham in 1998.¹⁵ In their series, six patients with recalcitrant limited forearm rotation required a palmar capsulectomy, whereas three had a combined palmar and dorsal capsulectomy. Their range of forearm rotation improved from an average 54 to 21 degrees of pronation-supination to 82 to 72 degrees at follow-up.