Vaughan-Jackson Syndrome


Background

The term Vaughan-Jackson syndrome refers to disruption of the digital extensor tendons, beginning on the ulnar side of the hand and wrist with the extensor digiti minimi (EDM) and extensor digitorum communis (EDC) tendon of the small finger. If the underlying pathology is not treated, sequential rupture of the EDC tendons of the ring, long, and index fingers occurs; ultimately, rupture of the extensor indicis proprius (EIP) may follow. [1]

Vaughan-Jackson's first report of extensor tendon rupture described two elderly laborers with degenerative arthritis of the distal radioulnar joint (DRUJ). [2He found that the tendons were frayed and disrupted directly over a bony prominence projecting from the head of the ulna in both cases.

In a subsequent report, [3Vaughan-Jackson described the process of attritional rupture of the digital extensor tendons in the rheumatoid hand, with which his name has become associated. Rheumatoid arthritis (RA) is the most common underlying etiology of tendon rupture in the hand and wrist and is the usual clinical setting in which the term Vaughan-Jackson syndrome is employed.

Other, less common patterns of tendon rupture seen in RA include rupture of the extensor pollicis longus (EPL) in the vicinity of Lister's tubercle within the third dorsal compartment [4and rupture of the flexor pollicis longus (FPL) and index-finger flexor digitorum profundus (FDP) tendons within the carpal tunnel (ie, Mannerfelt syndrome). [5]

Pathophysiology

Tendon ruptures in Vaughan-Jackson syndrome are primarily caused by gradual attrition of the tendons on the ulnar head, which, in RA, may subluxate or dislocate dorsally as a result of loss of the normal supporting structures. The process of tendon wear may be exacerbated by osteophytes and sharp prominences resulting from primary or secondary degenerative changes of the bone. Attrition of the tendons on the unstable distal ulnar stump after partial ulnar excision (Darrach procedure) has also been described as a cause of digital extensor tendon rupture. [67]

Direct invasion of the tendons and interference with normal tendon blood supply resulting from rheumatoid tenosynovitis have also been implicated as contributing causative factors. The cascade of wrist and DRUJ deformities produced by RA often results in palmar and ulnar subluxation of the extensor carpi ulnaris (ECU) tendon, taking it out of harm's way. The ECU and stout radial wrist extensors are seldom ruptured. [489]

Rupture of the EPL tendon within the third dorsal compartment is occasionally seen as a complication after a minimally displaced fracture of the distal radius in patients without RA. Mechanical factors unrelated to rheumatoid disease that have been described as causes of extensor tendon rupture include the following:

  • Abnormalities of the ulnar head from either traumatic subluxation or Madelung deformity
  • Deformity of the radius or ulna following fracture
  • Orthopedic hardware on both the dorsal and palmar surfaces of the distal radius

Bony prominences resulting from Kienbock disease and carpal osteochondromata, as well as local inflammation related to gout and calcium pyrophosphate dihydrate crystal deposition disease (pseudogout) have also resulted in tendon rupture. [101112131415161718192021]

Etiology

Risk factors that have been associated with digital extensor tendon rupture in RA patients include the following:

  • Dorsal subluxation of the ulnar head
  • Radiographic erosion of the DRUJ (the scallop sign; see the image below) [22]
  • Dorsal tenosynovitis persisting for 6 months or longer
Posteroanterior radiograph of the wrist following Posteroanterior radiograph of the wrist following wrist arthrodesis and resection of the distal ulna displays the scallop sign, which is the term used to describe the scooped-out appearance of the sigmoid notch of the radius that results from synovial proliferation and bone erosion.

In a study of 58 rheumatoid hands with tendon rupture, [2373% of the hands had two or more of these risk factors, and 93% of the patients with tendon rupture were noted to have persistent tenosynovitis for 6 months, making this finding particularly worrisome.

A review of 41 wrists with extensor tendon rupture due to DRUJ osteoarthritis found that tendon disruption occurred only in those joints with severe radiographic changes. [24Specifically, widening and deepening of the sigmoid notch of the radius (the scallop sign) was the radiographic finding most strongly associated with tendon rupture in these osteoarthritic patients.

Epidemiology

In the United States, the vast majority of tendon ruptures occur in patients with RA, and the incidence of extensor tendon involvement is 10-15 times that of flexor tendon involvement. Although some studies have reported tendon rupture to be more common in the dominant hand, this has not been a universal finding. [4]

Tendon rupture caused by osteoarthritis, though relatively rare, is more common in older persons, whereas no age restriction exists for tendon rupture caused by RA. The pattern of rheumatoid joint involvement can vary dramatically among individuals, sometimes even from one extremity to the other in the same patient. Tendon ruptures have been seen in patients who have had RA for as little as 2 years to as long as 25 years, though in most series, rheumatoid disease has been present for an average of 10-15 years. [25]

Prognosis

Hands with single-digit tendon ruptures exhibit better results than do those with multiple-digit involvement. [426 In particular, extension lag following reconstruction seems to increase in direct proportion to the number of digits involved. [27 A functional 70° arc of metacarpophalangeal (MCP) joint motion is commonly restored. [4 Delays in initiating surgical treatment are sometimes associated with poorer outcomes, although this is not a universal finding. [2627]

Patients with RA are remarkably adept at coping with hand deformity and dysfunction. In patients with relatively normal MCP joint function, loss of the ability to extend the digits and open the hand to grasp large objects imparts obvious functional limitations. Other individuals with severe MCP joint deformity or subluxation may not even be aware that extensor tendon rupture has occurred.

Patient Education

The services of a certified hand therapist are invaluable in educating patients on the postoperative regimen. Splint use and activity restriction must be adhered to in order to prevent disruption of the tendon graft or transfer.

Perhaps the most important lesson that can be imparted to these patients is an understanding of the warning signs and risk factors that may indicate the possibility of impending tendon rupture in the contralateral limb.



History

Patients who have Vaughan-Jackson syndrome usually present with sudden inability to actively extend the metacarpophalangeal (MCP) joint of the small finger. This is seldom associated with significant discomfort, though symptoms of pain, instability, or catching of the distal radioulnar joint (DRUJ) may be present.

Often, a history of swelling is reported on the dorsum of the hand and wrist as a result of extensor tenosynovitis and underlying joint synovitis that may have been present for months to years. If medical attention is not sought in a timely fashion, patients may note that active MCP extension of the ring finger, long finger, and, finally, index finger is lost in succession. [9A study that included 29 patients with multiple extensor tendon ruptures due to rheumatoid arthritis (RA) found that the mean duration between the first tendon rupture and involvement of the subsequent digit was 2.9 months. [28]

It is important to elicit a history of wrist and MCP joint pain or dysfunction that preceded the inability to extend the digits. Anatomic abnormalities of these articulations may influence the choice of available surgical reconstruction.

Warning signs of impending tendon rupture include the following:

  • MCP joint extensor weakness
  • Extension lag
  • Active tenosynovitis on the dorsum of the hand and wrist
  • Pain on the dorsum of the wrist associated with digital extension

Physical Examination

The MCP joints are among the most commonly affected articulations in patients with RA; subluxation of the extensor tendons and subluxation of the joints are particularly common deformities. In patients with RA who have relatively normal MCP joints, loss of active extension is clinically obvious. Extensor tendon subluxation is usually visible, and patients with these deformities are often able to maintain MCP extension once the joint is passively positioned, a finding that further distinguishes such patients from those with tendon rupture. (See the image below.)

Typical appearance of the hand following rupture oTypical appearance of the hand following rupture of the extensor tendons of the ring and small finger.

The presence of a fixed deformity that cannot be passively corrected and radiographic findings confirming MCP joint subluxation or dislocation suggest that treatment of the joints is required in conjunction with treatment of the tendon rupture. Patients with significant fixed MCP deformity may require exploration of the tendons on the dorsum of the hand and wrist at the time of joint reconstruction to determine if the tendons are intact. [929]

The DRUJ usually must be reconstructed at the time tendon continuity is restored. Range of motion (ROM), pain, synovitis, and instability of this joint must be documented. Wrist motion and stability must be evaluated because these findings may impact the choices made for surgical reconstruction of the DRUJ. Volar and ulnar subluxation of the carpus with respect to the radius and ulna often accompanies pathology involving the extensor tendons and the DRUJ. [23]

Posterior interosseous nerve (PIN) palsy caused by synovial proliferation at the elbow may also result in the loss of active MCP extension. [30Nerve palsy does not usually produce the same pattern of loss of digital extension. When the PIN is involved, the ring and long fingers tend to lose extension first, and the tenodesis effect of wrist flexion resulting in MCP extension is still present. This finding can sometimes be difficult to demonstrate in the rheumatoid limb, in which passive ROM of the wrist or MCP joints may be limited by underlying disease.

Even after tendon rupture, associated synovitis may fix the distal tendon stump to adjacent soft tissues, resulting in an apparent tenodesis effect and further confounding efforts to distinguish these processes.



History

Patients who have Vaughan-Jackson syndrome usually present with sudden inability to actively extend the metacarpophalangeal (MCP) joint of the small finger. This is seldom associated with significant discomfort, though symptoms of pain, instability, or catching of the distal radioulnar joint (DRUJ) may be present.

Often, a history of swelling is reported on the dorsum of the hand and wrist as a result of extensor tenosynovitis and underlying joint synovitis that may have been present for months to years. If medical attention is not sought in a timely fashion, patients may note that active MCP extension of the ring finger, long finger, and, finally, index finger is lost in succession. [9A study that included 29 patients with multiple extensor tendon ruptures due to rheumatoid arthritis (RA) found that the mean duration between the first tendon rupture and involvement of the subsequent digit was 2.9 months. [28]

It is important to elicit a history of wrist and MCP joint pain or dysfunction that preceded the inability to extend the digits. Anatomic abnormalities of these articulations may influence the choice of available surgical reconstruction.

Warning signs of impending tendon rupture include the following:

  • MCP joint extensor weakness
  • Extension lag
  • Active tenosynovitis on the dorsum of the hand and wrist
  • Pain on the dorsum of the wrist associated with digital extension

Physical Examination

The MCP joints are among the most commonly affected articulations in patients with RA; subluxation of the extensor tendons and subluxation of the joints are particularly common deformities. In patients with RA who have relatively normal MCP joints, loss of active extension is clinically obvious. Extensor tendon subluxation is usually visible, and patients with these deformities are often able to maintain MCP extension once the joint is passively positioned, a finding that further distinguishes such patients from those with tendon rupture. (See the image below.)

Typical appearance of the hand following rupture oTypical appearance of the hand following rupture of the extensor tendons of the ring and small finger.

The presence of a fixed deformity that cannot be passively corrected and radiographic findings confirming MCP joint subluxation or dislocation suggest that treatment of the joints is required in conjunction with treatment of the tendon rupture. Patients with significant fixed MCP deformity may require exploration of the tendons on the dorsum of the hand and wrist at the time of joint reconstruction to determine if the tendons are intact. [929]

The DRUJ usually must be reconstructed at the time tendon continuity is restored. Range of motion (ROM), pain, synovitis, and instability of this joint must be documented. Wrist motion and stability must be evaluated because these findings may impact the choices made for surgical reconstruction of the DRUJ. Volar and ulnar subluxation of the carpus with respect to the radius and ulna often accompanies pathology involving the extensor tendons and the DRUJ. [23]

Posterior interosseous nerve (PIN) palsy caused by synovial proliferation at the elbow may also result in the loss of active MCP extension. [30Nerve palsy does not usually produce the same pattern of loss of digital extension. When the PIN is involved, the ring and long fingers tend to lose extension first, and the tenodesis effect of wrist flexion resulting in MCP extension is still present. This finding can sometimes be difficult to demonstrate in the rheumatoid limb, in which passive ROM of the wrist or MCP joints may be limited by underlying disease.

Even after tendon rupture, associated synovitis may fix the distal tendon stump to adjacent soft tissues, resulting in an apparent tenodesis effect and further confounding efforts to distinguish these processes.


Diagnostic Considerations

Other problems to be considered include the following:

  • Extensor tendon subluxation at the metacarpophalangeal (MCP) joint
  • MCP joint subluxation or dislocation
  • Posterior interosseous nerve (PIN) palsy.


Imaging Studies

Radiography

Plain radiographs are imperative to assess the status of the distal radioulnar joint (DRUJ) and the wrist. The degree of joint destruction, subluxation, or dislocation, as well as the presence of bony prominences that may be directly responsible for tendon attrition, can be determined by obtaining good-quality plain radiographs in three projections (posteroanterior [PA], lateral, and oblique). (See the images below.)

Posteroanterior radiograph of the wrist following Posteroanterior radiograph of the wrist following wrist arthrodesis and resection of the distal ulna displays the scallop sign, which is the term used to describe the scooped-out appearance of the sigmoid notch of the radius that results from synovial proliferation and bone erosion.
Radiograph of a rheumatoid hand with metacarpophalRadiograph of a rheumatoid hand with metacarpophalangeal joint dislocations. These joints are incapable of active or passive extension.

Radiographic and clinical evaluation of the radiocarpal joint is necessary because the condition and function of this articulation may influence the choice of reconstructive options for the DRUJ. [31If a mobile wrist is to be maintained, simple excision of the distal ulna may not be advisable, and alternatives (eg, the Sauve-Kapandji procedure) may help prevent or delay subsequent ulnar translation of the carpus. [3233]

Because the purpose of reestablishing extensor tendon function is to restore active metacarpophalangeal (MCP) joint extension, the MCP joints should be evaluated radiographically. Most authors would suggest that the reconstruction or replacement of badly damaged MCP joints should precede tendon restoration, though this point can be debated. Regardless of whether one favors primary MCP arthroplasty or combined tendon reconstruction and arthroplasty, adequate planning is impossible unless the condition of the MCP joints is known.

MRI, ultrasonography, and CT

Although magnetic resonance imaging (MRI) depicts effusion, synovitis, and even tendon involvement quite accurately, it has not proved to be predictive in the risk assessment of tendon rupture. [34]

Both ultrasonography and three-dimensional (3D) computed tomography (CT) have been utilized to demonstrate tendon ruptures on the dorsum of the hand and wrist and to evaluate the risk for potential tendon rupture. These techniques have not yet progressed to the point where they can provide a reliably accurate identification of tendons at risk for rupture. [353637383940]

Proper diagnosis can almost always be made on the basis of careful physical examination and plain radiography. Advanced imaging seldom influences the decision for surgery or the procedure itself; therefore, routine use of these studies is not currently advocated.

Preoperative Evaluation

Thorough preoperative evaluation must precede any surgical procedure. This is particularly important in the case of the patient with rheumatoid disease who may be significantly debilitated. Rheumatoid arthritis (RA) is something of a misnomer; it is a systemic disease that may produce cardiac, pulmonary, and other organ system dysfunction.

Preoperative laboratory, cardiac, and respiratory evaluation is most appropriately directed by the primary care provider; the rheumatologist may function in this capacity. Other subspecialty evaluation may also be necessary because of specific organ system involvement. [41]

Medications used to treat rheumatoid disease may produce significant hematologic, hepatic, or renal effects that must be evaluated preoperatively. Certain medications (eg, corticosteroids, penicillamine, and methotrexate) may alter wound-healing potential and possibly increase the risk of infection.

Tumor necrosis factor (TNF) antagonists have improved the lives of many patients who have RA, but they are associated with an increased risk of opportunistic infection. Data regarding possible increased risk of postoperative infection in patients treated with these agents are scant and sometimes conflicting. [42]

It may be advantageous to adjust the dosing regimen of these agents in the perioperative period, though evidence-based recommendations cannot be made at this time. The desire to avoid surgical complications must be balanced against the fact that a flare of the rheumatoid process in the perioperative period from alterations in medication can also contribute significantly to morbidity. Rheumatologic consultation is recommended.

Rheumatoid involvement of the cervical spine leading to instability is a common occurrence that must be anticipated preoperatively. Even when regional anesthesia is planned in cases of upper-extremity reconstruction, the possibility always exists that general anesthesia and tracheal intubation will be necessary. Preoperative evaluation of cervical spine stability will allow appropriate precautions to be taken and potentially devastating complications to be avoided. 


Medical Therapy

Tendon continuity cannot be restored by means of medical therapy; in fact, the occurrence of tendon rupture may indicate that the current regimen of medical management is inadequate and that additional remittive therapy should be considered. Adequate medical control of rheumatoid disease is imperative to minimize synovial proliferation, which may otherwise jeopardize the results of surgical reconstruction, place other anatomic areas at risk, or both.

Pharmacologic preparation for surgery

Most authors recommend a single intravenous (IV) dose of an antibiotic (usually a cephalosporin) immediately before surgery, and some follow this with 24 hours of postoperative therapy as a prophylactic measure. The postoperative antibiotic can be administered orally on an outpatient basis. This author is not aware of a controlled study that demonstrates the advisability of any particular perioperative antibiotic regimen.

Patients treated with corticosteroids require increased doses in the perioperative period to protect against the possibility of addisonian crisis brought on by the stress of surgery. [41]

Adequate pain control must be ensured; occasionally, this necessitates postoperative inpatient hospital admission.

Surgical Therapy

Prevention of tendon rupture

Prophylactic procedures intended to prevent tendon rupture are generally quite effective and provide function that is superior to the function provided by any method of tendon repair or reconstruction. Patients with risk factors such as dorsal prominence of the distal ulna, radiographic erosion involving the distal radioulnar joint (DRUJ), or persistent dorsal tenosynovitis that is unresponsive to medical management over a 6-month period should be considered candidates for such surgery. [23]

Weakness or extensor lag of the small-finger metacarpophalangeal (MCP) joint may indicate that one of the tendons that motor this joint has failed; this is usually caused by rupture of the extensor digiti minimi (EDM), with residual function resulting from the intact extensor digitorum communis (EDC) tendon. This warning sign or pain over the dorsum of the wrist associated with motion of the digital extensor tendons should also prompt early exploration. Tendon rupture after prophylactic surgery, which includes tenosynovectomy and DRUJ reconstruction, is rare (0-4%). [43]

Hsueh et al, in a retrospective review of 17 episodes of spontaneous tendon rupture (15 rheumatoid arthritis [RA] patients) and 14 episodes of tenosynovitis (12 RA patients), suggested that prophylactic extended tenosynovectomy to prevent more severe extensor tendon damage should be recommended in those with the following risk factors [44:

  • Rheumatoid disease of more than 8 years' duration
  • Persistent tenosynovitis of more than 1 year's duration
  • Larsen grade higher than 4

Tendon continuity restoration

Surgical efforts to restore tendon continuity must always include thorough dorsal tenosynovectomy with retinaculum transposition and resection or reconstruction of the DRUJ sufficient to remove the bony prominences that produced the tendon rupture. [29As noted previously, the choice of DRUJ reconstruction may vary, depending on the status of the wrist joint and other individual patient considerations. [31After the loss of small-finger extension, surgical exploration should be undertaken without delay to avoid sequential rupture of the adjacent tendons, which would further complicate reconstruction. (See the image below.)

Intraoperative image of a ruptured extensor tendonIntraoperative image of a ruptured extensor tendon with the hand to the left. Note that the tendon ends cannot be reapproximated despite maximum tension.

Direct repair

Direct repair of ruptured tendons is rarely possible, both because of the attritional nature of this process and because the zone of tendon injury is usually quite long. [9]

Bridge grafts

The use of bridge grafts to restore tendon continuity has been described with generally acceptable results. Bora et al reported 23 patients who recovered an average of 65° of MCP joint motion after free tendon grafting (average follow-up, 43 months). [45However, this technique has not gained widespread acceptance, because tendon graft harvest may require additional operating time and surgical exposure, sometimes at a remote site.

Many authors have also expressed concern that tendon grafting results in two tenorrhaphy sites in what is often a less than optimal tendon bed, possibly increasing the risks of scar formation and motion-limiting adhesions. [29]

In a study by Nakamura and Katsuki, grafting of multiple extensor tendon ruptures in 14 patients with RA resulted in good correction of extensor lag, but patients were dissatisfied with the accompanying loss of digital flexion. [46These authors postulated that this limitation of flexion is caused by contracture of the involved muscle and, thus, did not recommend tendon grafting.

Chung et al reported that MCP joint extension lag correlated with patient satisfaction scores, whereas pulp-to-palm distance in flexion did not. [47Their study of 51 wrists with extensor tendon ruptures found no significant differences in outcome between tendon grafting and tendon transfers.

Tendon transfer

Tendon transfer remains the most common method of restoring tendon continuity in the rheumatoid hand after extensor tendon rupture. [48However, it is associated with its own particular set of challenges, including the possibilities that the joints to be motored may be stiff or unstable, that the tendon beds may be less than ideal, that the motor tendons may have disease involvement or may be unavailable, and that tenodesis may be limited by wrist stiffness.

Despite these potential shortcomings, tendon transfer is often the best surgical alternative. The method of tendon transfer is determined primarily by the number of digits involved. [49]

Small-finger MCP joint extension may be lost after isolated rupture of the EDM in a patient without significant EDC tendon contribution to this digit, or it may follow rupture of both the EDM and a slip of the EDC. The distal tendon stump that produces strong MCP joint extension of the small finger (usually the EDM) may be transferred to the adjacent EDC of the ring finger. Occasionally, the distal stump is so short that such side-to-side suture tends to produce unacceptable abduction of the small finger. In these instances, the extensor indicis proprius (EIP) may be transferred to the EDM. [49]

Loss of ring- and small-finger MCP joint extension is usually best treated by using the EIP to motor both the EDM and the ring-finger EDC. Alternatively, the EIP may be transferred to the EDM, and the ring-finger EDC may be sutured in a side-to-side fashion to the intact long-finger EDC. [49]

Loss of long-, ring-, and small-finger MCP joint extension is usually treated by transfer of the EIP to both the EDM and the EDC of the ring finger and side-to-side suture of the long-finger EDC to the intact index-finger EDC. If the EIP is the only remaining extensor to the index finger, a flexor digitorum sublimis (FDS) tendon may be used to motor ring- and small-finger MCP joint extension in place of the EIP. Although one of the radial wrist extensors (preferably the extensor carpi radialis longus) can be considered as a motor tendon in this circumstance, it often is not long enough to reach the distal stumps of the ruptured tendons and lacks sufficient excursion to restore normal MCP joint motion. [49]

Loss of MCP joint extension of the index, long, ring, and small fingers constitutes the final stage of this process and should only be seen in neglected cases. Although one hesitates to remove power and joint stability from the volar surface of the rheumatoid hand, transfer of the FDS tendons to provide MCP joint extension, as originally described by Boyes in the treatment of radial nerve palsy, [50is often the best alternative. Many patients feel that flexor function is improved as a result of decompressing the digital flexor sheaths by tendon harvest.

Most authors use the ring-finger FDS to motor the ring and small fingers and the long-finger FDS to motor the index and long fingers. The classic Boyes transfer routed these tendons through a window in the interosseous membrane. However, adhesions may be limited in the rheumatoid hand by using the alternative of a subcutaneous tunnel around the forearm. [49The radial route is preferred because it tends to counteract the tendency for ulnar subluxation of the digital extensors on the dorsum of the MCP joints. [51Other motor tendons may, of course, be used, depending on the specific clinical circumstance.

Postoperative Care

Inpatient hospital care is seldom required after surgical treatment of ruptured extensor tendons unless these procedures are combined with other major joint reconstruction procedures.

Surgery on a single upper extremity may significantly affect the functional capabilities of patients with RA. These patients frequently have limited function of the contralateral hand, as well as a need for ambulatory aids or other assistive devices that they may be incapable of using in the postoperative period. The need for increased support and home health assistance should be anticipated.

Appropriate hand therapy and splinting are crucial to the success of these procedures. [39In the absence of supervised therapy, limitation of motion from scarring and adhesion formation may exceed the limitation that was present preoperatively. Joints adjacent to those that are being surgically treated are seldom entirely normal in the rheumatoid hand, and early motion is necessary to prevent stiffness and functional deterioration.

Although many authors advocate immobilization of the MCP joints in a position near full extension for 3-4 weeks after extensor tendon reconstruction, this author favors a program of graduated dynamic extension splinting in an attempt to maximize motion, particularly to avoid the loss of digital flexion. Therapy is usually initiated on postoperative day 3 or 4, after edema has declined and the wounds have settled. The overall pattern of patient disease and ongoing medical treatment may dictate accommodations in the usual course of postoperative therapy. [52]

Complications

Wound healing problems and infection are encountered in fewer than 5% of cases. [4]

Extension lag at the MCP joint is a frequently mentioned occurrence, [27though its incidence and magnitude are difficult to quantify. Most authors would agree, however, that extension contracture is very uncommon, and it generally is better to err on the side of increased tension when setting tendon transfers in the rheumatoid hand. [49]

Rerupture is distinctly uncommon, occurring in fewer than 5% of cases. This complication is usually related to inadequate reconstruction of the distal ulna, which allows recurrence of dorsal displacement and attritional tendon wear. [4]

Recurrent tenosynovitis develops in fewer than 7% of cases with medium-term (3- to 8-year) follow-up after tenosynovectomy. 


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