Basal Joint Osteoarthritis of the Thumb

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Basal Joint Osteoarthritis of the Thumb

• By
• Prof. Eissa R. Refaie
• Professor of Orthopedic surgery,
• Al-Azhar University

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The basal joint of the thumb consist of 4
trapezial articulation

• Trapezio metacarpal (TM).
• Trapeziem- index metacarpal.
• Trapeziotrapezoid.
• Scaphotrapezial (ST).

Only TM and ST joints lie along the longitudinal
compression axis of the thumb
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• TM joint is the second most commonly involved
  site of primary degenerative osteoarthritis in
  the hand

First that require treatment
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• Why degenerative arthritis has predilection for
  these joints?

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• Grip and Pinch are the main function of the
  thumb

Cylinder grip
Spherical grip
Power grip
Ulnar side is gripping surface
Pad is gripping surface
Adducted thumb
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Pinch

• Pulp-to-pulp.
• Tip-to-tip.
• Key Pinch.
• Adducted thumb against index side.
• Pulp-to-pulp.

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• Grasping and pinching function of the thumb
  involves 3 arcs of motion
• flexion-extension
• Abduction-adduction
• Opposition

T.M. joint
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• All M.P. and I.P. joints in the hand are hinge
  joints allow only one arc of motion.

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• TM joint has biconcave saddle joints with two
  matching saddle shaped articular surface.

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• The matching articular surface of this saddle
  shaped joint permit free motion in flexion-
  extension and in abduction-adduction.

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• First metacarpal Rider seated comfortably in
  the saddle. It can rock back and forth into
  flexion and extension or anteriorly away from the
  second metacarpal
• abduction

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• Because the saddle is not deep and because the
  rider is usually not being compressed down into
  the saddle, it can also twist in its seat
• ? opposition.

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• This axial rotation results in increased contact
  forces between the opposing joint surface
  subjecting the cartilage to shear.

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• The capsule and ligaments provide
• Enough stability to keep 1st metacarpal securely
  tethered to the trapezium during pinch.
• Sufficient laxity to allow rotation of the
  metacarpal in the saddle.

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• Anterior oblique (Volar beak) ligament tethers
  the base of thumb metacarpal to the trapezium.

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• Adductor pollicis longus spans the ?V? between
  thumb and index metacarpal. Abductor pollicis
  longus inserts at the base of thumb metacarpal.

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• In the absence of sufficient ligamentous
  stability base of thumb metacarpal sublaxed
  dorsally and metacarpal adducted towards index
  metacarpal.

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• This unique anatomy of TM joint allows various
  function but predispose it to unusual wear
  pattern when the joint is unstable.

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Etiological Factors

• Axial rotation creates mild incongruity of the
  saddle shape contours.
• Compressive forces across the joint.
• Estrogen induced ligament laxity.
• Genetic factors.

N. Naam, 2002
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Pathogenesis
Pellegrini, 1986.

• Initial attritional changes in the beak ligament.
  
• Destabilization of thumb metacarpal.
• Increased shear forces in the palmar contact
  areas of the joint.
• Synovitis ? release of biochemical factors .

Biochemical factors alters the mechanical
properties of hyaline cartilage making it more
susceptible to failure under load.
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• Eburnation and erosion of the articular surface
  mostly plamar area.
• Narrow joint Space, secondary osteophytes.
• Adduction deformity of the thumb metacarpal.

Marked functional deficient
Hyperextension of M.P. joint
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Diagnosis

• Post menopausal women 50-70 years.
• PainRadial sided thumb
• increased by grip and pinch activities.
  
• Weakness of grip and pinch.
• dropping objects.
• Local tenderness.
• Swelling.
• Crepitus.
• Deformity.

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Forceful pinch Calibrated pinch gauge. ? Pain

• Grind test
• In the stage of synovitis.
• ve ? crepitus and pain.

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Plain Radiograph

• A.P.
• Lateral.

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• P.A. 30º oblique stress view
• demonstrates the potential for lateral shift
  of the metacarpal shaft off the saddle of
  traperzium in a subluxatable joint.

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Radiographic Classification
Eaton, 1998

• Stage I
• No degen. Changes ,may be widening.

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Radiographic Classification

• Stage II
• Narrowed J. space.
• Osteophytes lt 2mm in diameter.
• ST joint normal

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Radiographic Classification

• Stage III
• Marked narrowing.
• Subchondral sclerosis and cyst.
• Sublaxation.
• Ostephytes gt 2mm diameter
• ST joint normal.

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• Stage IV
• Advanced degen changes in both TM and ST joint

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• ?

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D.D.

• de Quervain tenosynovitis.
• Carpal tunnel syndrome.
• Trigger thumb.

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Treatment

• Conservative
• Stage I and II ? pain relief long period.
• Stage III and IV ? partial pain relief.

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• Conservative
• NSADs.
• Thumb spica splint.
• Full time 3 weeks.
• Part time 3 weeks.
• Activity modification and functional education.
• Steroid injection.
• Excellent Pain relief for unpredictable
  duration.

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Surgical Treatment

• Indications
• Persistent pain and functional disability after
  failed cons. Treatment.
• Severe deformity in active healthy patient.
• Patients who cannot use NSADs.

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Surgery in stage I early Stage II
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• Ligament reconstruction.
• Extension osteotomy, base thumb metacarpal.
• Arthroscopy
• Debridement.
• Ligament shrinkage.
• TM pinning.

Wilson 1973
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Surgery in late stages
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Arthrodesis

• Provides stability, pain relief and increased
  strength.
• Disadvantages
• Increased arthrosis in adjacent joint.
• Limitation in R.O.M.
• Compensatory hyperextension of M.P. joint.

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Arthrodesis

• Indication
• Young male patient with post traumatic arthritis.
  
• Position of fusion
• 40º palmar abduction.
• 15º Extension.

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Silicone Arthroplasty

• Dramatic relief of pain and restoration of
  motion.
• Early Complications
• Implant wear.
• Silicone synovitis.
• Erosive bony changes.

The principle use of silicone implants remains in
low- demand rheumatoid patient.
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Cemented Total joint Arthroplasty

• Different combination of metallic and
  polyethylene.
• High loosening rate.

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Ligament Reconstruction with tendon Interposition
Arthroplasty
Burtorn and Pellegrini, 1986

• Excision of trapezium ? remove painful arthritic
  surfaces.
• Reconstruction of oblique volar ligament by FCR
• FCR tendon interposition

Restore thumb metacarpal stability.
Prevent axial shortening .
To reduce impingement between bony surfaces.
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Post Operative Care

• Plaster and K.wire for one month.
• Removable thumb spica splint 4 times daily,
  exercises program / one month.
• Splinting discontinued at 3 months.
• Pinch and grip strengthening exercises.

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Case 1
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Case 2
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Results of LRTI

• Improve pinch strength.
• Increase grip strength.
• Restore thumb web space.
• Patient satisfaction.
• Thumbs continue to improve for as long as 6
  months- one year.

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Conclusion

• TM joint has a unique anatomy explain why it
  wears out.
• Diagnosis is easy.
• Conservative measures is effective in early cases
  and should be tried in severe one.

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Conclusion

• Several modalities of surgical treatment exist.
• Ligament reconstruction with tendon interposition
  arthroplasty is the most popular, effective,
  simple surgery.

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THANK YOU
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