Summary Basilar Thumb Arthritis is a form of arthritis that causes pain at the base of the thumb and difficulty with pinching and grasping due to carpal-metacarpal (CMC) joint arthritis. Diagnosis is made clinically with a painful CMC grind test and radiographs of the hand showing osteoarthritis of the 1st CMC joint. Treatment can be conservative (bracing, injections) or operative depending on the severity of symptoms and the stage of disease. Epidemiology Incidence common arthritis of the hand 2nd only to DIP arthritis DIP > thumb CMC > PIP > MCP seen in 25% of men and 40% of women aged > 75 years old Demographics more common in women thumb CMC arthritis is more common in Caucasians hand OA is more common in native Americans than Caucasians/African Americans Risk factors female gender Ehler-Danlos syndrome increased BMI Etiology Pathoanatomy theorized to be due to attenuation of anterior oblique ligament (Beak ligament) leading to instability, subluxation, and arthritis of CMC joint Associated conditions MCP hyperextension deformity MCP arthritis concomitant carpal tunnel syndrome occurs in up to 50% Anatomy Osteology thumb carpal-metacarpal joint is a biconcave saddle joint consists of 4 articulations trapeziometacarpal (TM) trapeziotrapezoid scaphotrapezial (ST) trapezium-index metacarpal trapezium has a palmar groove for the flexor carpi radialis (FCR) tendon Ligaments anterior oblique (volar beak) ligament primary stabilizing static restraint to subluxation of CMC joint originates from the palmar tubercle of the trapezium and inserts on the articular margin of the ulnar metacarpal base intermetacarpal ligament attaches from the radial base of the 2nd metacarpal to the ulnar base of the 1st metacarpal primary restraint to radial translation of the base of the 1st metacarpal assisted by the dorsoradial and posterior oblique ligaments posterior oblique ligament dorsoradial ligament primary restraint to dorsal dislocation injured in dorsal CMC dislocation strongest and thickest ligament Biomechanics CMC joint reactive force is 13x applied pinch force Classification Eaton and Littler Classification of Basilar Thumb Arthritis Stage I Slight joint space widening (pre-arthritis) Stage II Slight narrowing of CMC joint with sclerosis, osteophytes <2mm Stage III Marked narrowing of CMC joint with sclerosis, osteophytes >2mm Stage IV Pantrapezial arthritis (STT involved) Presentation Symptoms pain pain at base of thumb symptoms of concomitant carpal tunnel syndrome function difficulty pinching and grasping Physical exam inspection swelling and crepitus metacarpal adduction and web space contractures later findings may have adjacent MCP fixed hyperextension (zig-zag or "Z" deformity) occurs during pinch as a sequlae of CMC arthritis provocative tests painful CMC grind test combined axial compression and circumduction Imaging Radiographs recommended views AP lateral Roberts view X-ray beam is centered on trapezium and metacarpal with thumb flat on cassette and thumb hyperpronated findings joint space narrowing osteophytes may show MCP hyperextension Differential Diagnosis C6 Radiculopathy De Quervains tenosynovitis STT arthritis Scaphoid nonunion/SNAC Radioscaphoid arthritis Treatment Nonoperative NSAIDS, thumb spica bracing indications first line of treatment for mild symptoms injections indications second line of treatment for mild to moderate disease types steroid injections good evidence to support hyaluronic acid injections not indicated - studies show no difference for the relief of pain and improvement in function when compared to placebo and corticosteroids Operative CMC arthroscopic debridement indications early stages of disease 1st metacarpal osteotomy indications early Stage I-II disease contraindications hypermobility or fixed subluxation of the CMC joint MCP hyperextension > 10° technique performed with closing wedge dorsal extension trapeziectomy +/- ligament reconstruction indications Stage I-IV disease multiple techniques with none showing clear benefit over the others trapeziectomy + LRTI (ligament reconstruction and tendon interposition) most common procedure and favored in most patients hematoma arthroplasty (trapeziectomy without LRTI) trapeziectomy + suture suspension (suture suspension with APL to FCR) newer technique growing in popularity volar ligament reconstruction with FCR useful for Stage I disease when joint is hypermobile and unstable (pain with varus valgus stress) excision of proximal third of trapezioid ideal for patients with concomitant scaphotrapezioid arthritis (present in 62%), especially in Stage IV disease CMC arthrodesis indications Stage II-III disease in young male heavy laborers preserves grip strength contraindications scaphotrapeiotrapezoidal (STT) arthritis CMC denervation indications Stage I-IV disease CMC prosthetic arthroplasty indications not recommended Techniques CMC Arthroscopic Debridement technique portals dorsal 1R radial to the APL tendon dorsal 1U ulnar to the EPB tendon between the EPL and EPB tendons 1st Metacarpal Osteotomy technique redirects the force to the dorsal, more uninvolved portion of the 1st CMC joint perform closing dorsal wedge extension osteotomy fixation using K wires, intraosseous wiring, or plates outcomes gained in popularity 93% have symptom improvement at 7 years Trapeziectomy +/- Ligament Reconstruction technique many different surgical options are available trapezial excision is most important, regardless of other specifics of CMC arthroplasty FCR tendon most commonly used in LRTI to suspend metacarpal can also use ECRL or APL for suspension can use PL around FCR to correct subluxation outcomes can expect ~25% subsidence postoperatively with no change in outcomes results in improved grip and pinch strengths CMC Arthrodesis technique CMC joint fused in 35° radial abduction 30° palmar abduction 15° pronation outcomes good pain relief, stability, and length preservation decreased ROM, inability to put hand down flat nonunion rate of 12% CMC Denervation technique can be performed using 2 incisions dorsal apex of the first interosseous space volar distal wrist flexion crease, extending from the ulnar side of the FCR tendon to the 1st extensor compartment resect 4 nerves thenar cutaneous branch of the median nerve palmar cutaneous branch of the median nerve superficial branch of the radial nerve, via the dorsal articular nerve of the 1st interosseous space of the hand lateral antebrachial cutaneous nerve of the forearm, via the branch of Cruveilhier complications specific to this treatment injury to the sensory brach of the radial nerve outcomes improved hand function, grip strength, and pain comparable results to trapeziectomy and CMC arthrodesis in terms of pain improved ROM compared to CMC arthrodesis CMC Prosthetic Arthroplasty technique several implant types exist most experience has been using silicone implants complications specific to this treatment implant fracture or loosening subluxation silicone synovitis Complications 1st metacarpal subsidence and narrowing of trapezial space height occurs after trapeziectomy ± tendon suspension treatment LRTI with ECRL tendon or APL tendon if FCR is already used/ruptured MCP hyperextension deformity treatment depends on degree of hyperextension <10° - no surgical intervention 10-20° - percutaneous pinning of MCP in 25-35° flexion x 4wk ± EPB tendon transfer 20-40° - volar capsulodesis or sesamoidesis >40° - MCP fusion Prognosis Osteoarthritis in 1 joint in a row (proximal row) predicts for osteoarthritis in other joints in same row