Keywords
gout - uric acid - tendon insufficiency - flexor tendon rupture - hand
Introduction
Gout is a crystalline arthropathy characterized by synovial deposition of monosodium
urate crystals in the upper or lower extremity. Classically, patients present with
acute onset monoarticular joint pain, swelling, and erythema in the absence of inciting
trauma. Less common presentations of gout in the hand include flexion contracture,
flexor tenosynovitis, and flexor tendon rupture.[1]
[2]
[3]
[4]
[5]
[6] While gouty infiltration of flexor tendons is relatively common among patients with
uncontrolled disease, there exists only one published report of flexor tendon rupture
in the hand secondary to gout.[6] This previously reported case describes a patient with gouty infiltration of the
right index finger resulting in rupture of the flexor digitorum profundus (FDP) and
flexor digitorum superficialis (FDS).[6] The present case report highlights a patient with gouty infiltration of flexor tendons
in the right middle finger resulting in rupture of both the FDP and FDS requiring
two-stage tendon reconstruction.
Case
A 57-year-old right hand dominant female with a 2-year history of gout afflicting
the right hand presented with 6 months of restricted right middle finger flexion.
Her symptoms started following an episode of acute right hand pain and swelling several
weeks prior. She denied any history of hand trauma or surgery. Physical examination
revealed generalized swelling of the right middle finger with 0 degrees of active
flexion of the proximal interphalangeal (PIP) or distal interphalangeal joint ([Fig. 1A, B]). The serum uric acid was 11.1 mg/dL. Radiographic studies demonstrated no abnormalities
of the right middle finger. The leading diagnosis was rupture of the FDP and FDS tendons.
The patient was encouraged to continue taking febuxostat (80 mg daily) and scheduled
for surgery.
Fig. 1 Preoperative physical examination demonstrated generalized swelling of the right
middle finger (A) with inability to actively flex the proximal interphalangeal (PIP) or distal interphalangeal
(DIP) joints (B).
Following extensive consultation regarding the complexity of injury and demands of
postoperative rehabilitation, informed consent was obtained and the patient was taken
to the operating room for right middle finger exploration and single-stage versus
two-stage flexor tendon reconstruction. Zigzag incisions were designed to expose the
involved tendons. Extensive scar tissue was visualized surrounding the pulley system
and tendon sheath. The flexor tendon sheath was entered to reveal gross gouty infiltration
of the FDP and FDS tendons with zone II rupture ([Fig. 2A]). Both tendons were excised from the lumbrical muscle belly to the distal phalanx.
Given the extent of gouty infiltration and need for pulley reconstruction, a two-stage
flexor tendon reconstruction was indicated. A silicone rod was passed under the preserved
pulleys and sutured to the distal FDP tendon stump. The A2 pulley was reconstructed
over the silicone rod with a remnant of excised FDS tendon. The silicone rod was cut
proximal to the A1 pulley and left free in the palm to avoid distal rupture. Final
pathology confirmed the diagnosis of tophaceous gout ([Fig. 2B]). All cultures were negative. Aggressive passive range of motion exercises were
initiated starting 1 week postoperatively. The patient was prescribed prednisone (5 mg
daily) in addition to febuxostat (80 mg daily) between the first- and second-stage
operations.
Fig. 2 Intraoperative evaluation during the first-stage operation demonstrated extensive
gouty infiltration with tendon rupture of both the flexor digitorum profundus and
flexor digitorum superficialis (A). Pathologic analysis demonstrated eosinophilic amorphous gout deposits surrounded
by chronic inflammatory cells. The three arrows highlight examples of such deposits
on a representative pathology slide (B).
Approximately 3 months later, the patient returned to the operating room for silicone
rod removal and tendon grafting. The previous incisions were opened to reveal the
silicone rod gliding smoothly within a well-established pseudosheath. The palmaris
longus tendon was absent in the right wrist. Therefore, the remaining proximal FDS
tendon was selected for use as a tendon graft. The carpal tunnel was released to ensure
the proximal FDS tendon remnant was safely identified and dissected free prior to
division of the FDS tendon at the myotendinous junction ([Fig. 3A, B]). The tendon graft was split longitudinally to decrease the tendon bulk and passed
from proximal to distal through the pseudosheath. The distal end of the tendon graft
was secured to the distal phalanx using a tie-over button bolster. Specifically, a
Prolene suture was placed in the tendon using the Bunnell technique, and the suture
ends were passed through the distal phalanx using two Keith needles. Then, the suture
ends were tied over a sterile button on the nail plate at maximal tension to secure
the tendon end to the bone. The proximal end of the tendon graft was secured to the
distal aspect of the native FDP tendon in the palm using a Pulvertaft weave technique.
Tension was set with the middle finger in slightly greater flexion compared with the
normal cascade. The patient was then placed in a dorsal blocking splint for 6 weeks
to protect the reconstruction. Hand therapy following the Duran protocol was started
1 week postoperatively. Febuxostat (80 mg daily) was continued postoperatively.
Fig. 3 Intraoperative photographs during the second-stage operation demonstrating the flexor
digitorum superficialis tendon graft in situ (A) and along the planned site of inset (B).
The patient was examined in clinic 1 month postoperatively and found to have limited
active flexion of the PIP joint (∼45 degrees) with a passively correctable swan neck
deformity of the right middle finger. Additionally, a small draining wound was identified
on the volar aspect of the distal phalanx. The patient was prescribed a 10-day course
of amoxicillin-clavulanic acid and instructed to continue aggressive hand therapy
to improve her range of motion. She was subsequently evaluated in clinic 4 months
postoperatively. Physical examination of the right middle finger demonstrated complete
resolution of the draining wound, yet persistence of the limited active flexion of
the PIP joint (30 degrees) and associated swan neck deformity. The tendon reconstruction
appeared to be intact, suggesting the A2 pulley reconstruction may have failed resulting
in decreased active flexion of the digit. This scenario highlights the importance
of aggressive postoperative hand therapy to achieve full range of motion. The patient
was counseled on the risks and benefits of repeat pulley reconstruction, and she expressed
her desire to delay further operations.
Discussion
The flexor tendon sheath has been theorized to serve as a barrier against gouty infiltration
of flexor tendons.[7] However, recent publications have demonstrated that gouty infiltration can penetrate
the flexor tendon sheath leading to flexion contracture, flexor tenosynovitis, and
flexor tendon rupture.[1]
[2]
[3]
[4]
[5]
[6] The first and only previously reported case of flexor tendon rupture secondary to
gout was presented by Wurapa and Zelouf in 2002.[6] The authors performed a single-stage flexor tendon reconstruction given the intact
flexor tendon sheath and the patient's complex past medical history.[6] In the present case report, we further demonstrate that gouty infiltration of the
flexor tendon sheath may result in disruption of the underlying flexor tendon with
eventual tendon rupture. The extent of gouty infiltration and need for pulley reconstruction
in our patient required two-stage flexor tendon reconstruction.
Preoperatively, tendon rupture secondary to gouty infiltration should be high on the
differential diagnosis among patients with suspected or confirmed gout presenting
with tendon insufficiency. In patients lacking a formal diagnosis of gout, the presence
of needle-shaped negatively birefringent monosodium urate crystals on joint aspiration
is confirmatory. It is essential to optimize the medical treatment of gout preoperatively
to minimize further deposition of monosodium urate crystals. Baseline control of gout
is achieved with a xanthine oxidase inhibitor such as febuxostat or allopurinol. Additionally,
patients should be encouraged to avoid purine-rich foods (i.e., red meat and alcohol).
Gout flares are treated with a combination of nonsteroidal anti-inflammatory medications
(i.e., indomethacin), colchicine, and glucocorticoids. Many of the medications used
to treat gout flares have side effects that must be considered. For example, salicylates
may inadvertently decrease uric acid excretion and colchicine may cause gastrointestinal
or neuromyopathic symptoms. Importantly, xanthine oxidase inhibitors should not be
started during an acute gout flare to avoid transiently worsening symptoms. Our patient
presented with a known history of gout and her rheumatologist had previously started
her on febuxostat (80 mg daily). Therefore, we reinforced the importance of strict
compliance with febuxostat at the initial consultation given our concern that gout
was contributing to the patient's tendon insufficiency.
Intraoperatively, it is important to thoroughly evaluate the flexor tendon for gouty
infiltration and associated adhesions given the variable involvement of the pulley
system and flexor tendon sheath. Gouty infiltrates should be debulked to the extent
necessary to facilitate smooth motion of the involved tendon. Extensive adhesions
between the flexor tendon and surrounding flexor tendon sheath may require tenolysis
or tendon excision with reconstruction to restore range of motion, even in the absence
of gross tendon rupture.[8] In the case of flexor tendon rupture, single-stage versus two-stage flexor tendon
reconstruction is determined based on the extent of gouty infiltration of the pulley
system and tendon sheath. Regarding the present case report, we performed a two-stage
flexor tendon reconstruction given the severely damaged flexor tendon bed and need
for pulley reconstruction.[9] With respect to tendon grafting, Wurapa and Zelouf placed a short tendon graft from
the less involved proximal FDP stump to the less involved distal FDS stump.[7] During our stage two flexor tendon reconstruction operation, we placed a lengthy
segment of proximal FDS tendon from the distal phalanx to the proximal end of the
native FDP tendon in the palm as the patient lacked a palmaris longus tendon. It is
important to recognize that variable flexor tendon involvement in the affected digit
results in unpredictable tendon graft requirements.
Postoperatively, excised segments of flexor tendon and flexor tendon sheath should
be sent to pathology for analysis. The specimens must be fixed in alcohol rather than
formalin, as urate crystals are destroyed by routine formalin processing. Histologic
analysis of specimens excised during our first-stage operation demonstrated eosinophilic
amorphous gout deposits surrounded by chronic inflammatory cells. The presence of
chronic inflammatory cells on histologic analysis highlights the mechanism of tendon
rupture in patients with gout. Specifically, monosodium urate crystals within the
flexor tendon sheath and underlying flexor tendon induce a local inflammatory response.
Excessive inflammation causes macrophages to remain in the proinflammatory (rather
than profibrotic) state, and excessive macrophage-mediated remodeling eventually weakens
the tendon resulting in rupture.[10] The infiltration of cells from the intrasynovial tendon sheath to the injured tendon
during the healing process accounts for the dense adhesions we encountered during
the first-stage operation.[10]
In summary, the present case report highlights a patient with gouty infiltration of
flexor tendons in the right middle finger resulting in rupture of both the FDP and
FDS. This article provides additional evidence that the flexor tendon sheath does
not preclude flexor tendons from gouty infiltration. Thus, when patients with a history
of gout present with tendon insufficiency, tendon rupture secondary to gouty infiltration
is the most likely diagnosis.
