Leclercq syndrome, commonly known as Mannerfelt syndrome, refers to the isolated rupture of the flexor pollicis longus (FPL) tendon in patients with rheumatoid arthritis (RA). Chronic inflammation within the carpal tunnel leads to tendon degeneration and eventual rupture. Timely identification and intervention are crucial for restoring thumb function and preventing further disability.
Patients typically exhibit the following features:
Sudden Loss of Thumb Flexion: Inability to actively flex the thumb’s interphalangeal (IP) joint.
Pain or Discomfort: Preceding localized discomfort or pain in the volar wrist or thumb area.
Swelling: Visible swelling over the volar wrist or thumb.
Weakness: Difficulty gripping, pinching, or performing tasks requiring thumb flexion.
Crepitus: Audible or palpable creaking sensation prior to rupture.
Triggering: Catching or locking sensation before tendon rupture.
Visible Deformity: Chronic cases may show deformity from muscle atrophy.
Tenderness: Tenderness upon palpation over the carpal tunnel region.
Stiffness: Reduced range of motion in the thumb.
Functional Impairment: Difficulty with daily thumb-related tasks.
Conditions to differentiate from isolated FPL rupture include:
Anterior Interosseous Nerve (AIN) Palsy: Weakness of FPL and flexor digitorum profundus to index finger without sensory deficits.
Trigger Thumb: Thumb locking or catching from stenosing tenosynovitis; thumb flexion generally preserved.
Carpal Tunnel Syndrome: Median nerve compression causing sensory symptoms and weakness without isolated FPL rupture.
Flexor Tendon Laceration: Associated with trauma and visible skin injury.
Primarily clinical, supported by imaging:
Ultrasonography: Confirms tendon rupture and surrounding inflammation.
MRI: Detailed visualization of tendon discontinuity, synovitis, and bony abnormalities.
Plain Radiographs: Detect bony spurs or erosions contributing to tendon attrition.
Surgical intervention is required for thumb function restoration:
Tendon Transfer: Transfer of the flexor digitorum superficialis (FDS) tendon from ring or long finger to the distal FPL stump.
Tendon Grafting: Palmaris longus tendon graft bridging in cases unsuitable for direct tendon transfer.
Tenosynovectomy: Removal of inflamed synovium within the carpal tunnel to prevent further damage.
Carpal Tunnel Release: Simultaneous decompression to reduce pressure on median nerve and tendons.
Arthrodesis: Fusion of thumb IP joint for stability in severe or irreparable cases.
Essential for optimal recovery, including:
Splinting and controlled mobilization.
Progressive strengthening exercises.
Supervised therapy under a specialized hand therapist.
Prompt recognition and surgical management of isolated FPL rupture in RA are crucial for thumb function restoration and improved patient quality of life. A multidisciplinary team approach involving rheumatologists, orthopedic surgeons, and hand therapists ensures optimal outcomes.