Summary Flexor carpi radialis tendinitis is a condition characterized by pain over the volar radial wrist caused by inflammation of the FCR tendon sheath. Diagnosis is made clinically with pain over the FCR tendon that worsens with resisted wrist flexion. Treatment usually involves immobilization, NSAIDs and injections. In rare refractory cases operative release of the FCR tendon sheath may be indicated. Epidemiology Incidence rare < 1 per 100,000 annually Risk factors repetitive wrist flexion golfers and racquet sports manual labor Etiology Pathoanatomy primary stenosing tenosynovitis within the fibroosseous tunnel (see Anatomy) secondary tendinitis associated with scaphoid fracture scaphoid cysts distal radius fracture scaphoid-trapezium-trapezoid joint arthritis thumb CMC joint arthritis Anatomy Flexor carpi radialis musculotendinous unit FCR muscle bipennate FCR tendon enveloped by sheath from musculotendinous origin to trapezium no fibrous sheath distal to trapezium enters fibroosseous tunnel at the proximal border of the trapezium boundaries radial = body of the trapezium palmar = trapezial crest, transverse carpal ligament ulnar = retinacular septum from transverse carpal ligament (separates FCR from carpal tunnel) dorsal = reflection of retinacular septum on trapezium body space within the tunnel the FCR tendon occupies 90% of space is in direct contact with the roughened surface of the trapezium more prone to constriction, tendinitis, attrition, rupture proximal to the tunnel the FCR tendon occupies 50-65% of space within FCR sheath proximal to the tunnel less prone to constriction but more prone to mechanical irritation from osteophytes insertion small slip (1-2mm) inserts into trapezial crest 80% of remaining tendon inserts into 2nd metacarpal 20% of remaining tendon inserts into 3rd metacarpal Presentation Symptoms volar radial aspect of the wrist Physical exam tenderness over volar radial forearm along FCR tendon at distal wrist flexion crease provocative test resisted wrist flexion triggers pain resisted radial wrist deviation triggers pain Imaging Radiographs findings in primary tendinitis, radiographs are unremarkable in secondary tendinitis, the following may be present healed scaphoid fracture healed distal radius fracture exostosis or arthritis of scaphotrapezoid joint or thumb CMC MRI views best seen on T2 findings increased signal around FCR sheath on T2 image may find associated conditions in secondary tendinitis ganglion scaphoid cyst Studies Diagnostic injection injection of local anesthetic along FCR sheath relieves symptoms Differentials Thumb CMC arthritis Scaphoid cyst Ganglion cyst De Quervain's tenosynovitis Carpal tunnel syndrome Diagnosis Clinical and MRI diagnosis is made with careful history and physical examination and can be confirmed with MRI studies Treatment Nonoperative immobilization, NSAIDS, steroid injection indications first line of treatment technique direct steroid injection in proximity, but not into tendon outcomes usually effective for primary tendinitis unsuccessful in secondary tendinitis if other lesions are present (e.g. osteophytes) Operative surgical release of FCR tendon sheath indications rarely needed but can be effective in recalcitrant cases TechniqueS Surgical release of FCR tendon sheath approach volar longitudinal incision starting proximal to the wrist crease, extending over proximal thenar eminence care taken to avoid palmar cutaneous branch of median nerve lateral antebrachial cutaneous nerve superficial sensory radial nerve technique elevate and reflect thenar muscles radially expose FCR sheath open FCR sheath proximally in the distal forearm, and extend to the trapezial crest at the trapezial crest, the tendon enters the FCR tunnel at this point, incise the sheath along the ulnar margin, taking care not to injure the tendon mobilize tendon from trapezoidal groove (releasing trapezial insertion) Complications Complications of disease FCR attrition and rupture Complications of surgical release cutaneous nerve injury palmar cutaneous branch of median nerve lateral antebrachial cutaneous nerve superficial sensory radial nerve injury to deep palmar arch injury to FPL tendon (lies superficial to FCR tendon) injury to FCR tendon within the tunnel decompression is easy proximal to the tunnel (incision of FCR sheath) within FCR fibroosseous tunnel, take care to avoid cutting FCR tendon Prognosis Poor prognostic variables history of overuse worker's compensation failure to respond to local injection long duration of symptoms