OSTEOARTHRITIS FINGER/THUMB (MP, PIP, DIP & IP)

Osteoarthritis (OA), a degenerative joint disease, is the most common form of arthritis. OA causes bone change, loss of cartilage, and joint swelling. Ultimately, osteoarthritis causes damaged joint surfaces which rub against each other and cause more joint damage. OA of the hand is a complex disorder because the 29 bones of the hand and wrist contain multiple small joints that allow fine movement. The impact of OA on hand function depends on the digits affected. The thumb and index finger are important for pinching and fine motions, while the middle, ring, and small fingers are important for grip. OA in any of the three radial digits is associated with more severe upper-extremity disabilities. Older age and gender are well-known risk factors for OA.  Hand OA is especially common in women.

Pathophysiology

• Normally, a dynamic remodeling process balances degradation and synthesis of the extracellular matrix. 
• When the balance of degradation and synthesis of the extracellular matrix is lost then osteoarthritis develops.
• In OA, degrading enzymes are overexpressed, and collagen is lost.
• Inflammatory repair attempts are overwhelmed by progressive disease activity.

Related Anatomy

• Two of the most common sites where OA occurs:
  • Distal interphalangeal (DIP) joint
  • Proximal interphalangeal (PIP) joint
• Of all the joints in the body, the DIP and PIP joints of the hand are least likely to be symptomatic. Frequently the thumb IP joints and the thumb MP joints are also at risk for OA.
• OA involving the index, long, ring and little MP joints is relatively rare; however, trauma and hemochromatosis can accelerate OA in these MP joints.

Prevalence and Related Conditions

• Incidence rates of OA in specific joints of the hand vary widely.
• Prevalence of radiographic OA in the hand increases with age. Prevalence is high among the elderly, ranging from 13–47% in Asian populations and 80–94% in white populations.
• In one Korean study population (N=378) with a mean age of 75 years, prevalence was 58% in men and 67% in women.
• The radiographic signs of OA and the symptoms of OA frequently do not correlate very closely.  Patients will present with mild radiographic joint changes and significant pain while other patients have severe radiographic changes and NO symptoms.

Differential Diagnosis

• Bursitis
• Gout
• Injury (occupational, sport-related, trauma)
• Lupus
• Malignancy
• Periostitis
• Polymyalgia rheumatica
• Rheumatoid arthritis
• Sepsis
• Tendonitis 

The patient is typically older than 35 years and female. She will describe gradual onset of symptoms, and the main symptom will be pain. The patient is likely to have difficulty opening a jar or turning a key and may describe a grinding sensation at the affected joint. A parent may have a history of OA.

Surgical complications;

• Infection
• Persistent deformity
• Pain
• Decreased hand function

• Due to the complexity of the hand, OA treatment outcomes depend on the location of disease, rapidity of disease progression, degree of degeneration, patient characteristics (eg, compliance), activities of daily living and occupation and myriad other factors.  
• If surgery is successful, patients usually return to full function in ~3 months. 
• Surgery is especially helpful when there are a limited number of joints with symptomatic OA.

• A dynamic remodeling process usually maintains cartilage volume, but in OA the balance shifts, and progressive degradation results. 
• Loss of normal joint space, bone spurs, and other changes may indicate the presence of OA
• Mucoid cysts are frequently associated with DIP joint OA³
• Osteoarthritis develops as abnormal joint forces stimulate the chondrocytes to release inflammatory mediators which include aggrecanases and matrix metalloproteinases (MMPs).  These proteolytic enzymes cause the cartilage matrix destruction that leads to osteoarthritis.⁴
• Severe thumb MP joint osteoarthritis can be treated with MP joint arthrodesis (fusion).  Thumb MP fusion is also indicated when the thumb MP joint hyperextends excessively and a thumb CMC fascial arthroplasty is needed.⁵
• Hemochromatosis is rare, but early disease often involves the index and long finger MP joints.  Additional findings include chondrocalcinosis (as seen in pseudogout) and hooked osteophytes on the radial aspect of the metacarpal head.  If expected, patients with possible hemochromatosis should be referred to a hematologist for a laboratory workup and appropriate treatment.⁶
• Thumb MP joint pain can also becaused by thumb/sesamoid osteoarthritis
• Pyrocarbon arthroplasties have a higher revision rate than other finger protheses.⁷
• All finger joint arthroplasties have a limited long term longevity.
• Finger PIP arthodeses have excellent longevity but patients miss PIP flexion.

1. Deans VM, Naqui Z, Muir LT. Scaphotrapeziotrapezoidal joint osteoarthritis: A systematic review of surgical treatment. J Hand Surg Asian Pac Vol 2017;22(1):1-9.PMID: 28205478
2. Østerås N, Kjeken I, Smedslund G, et al. Exercise for hand osteoarthritis. Cochrane Database Syst Rev2017;1:CD010388. PMID: 28141914
3. Budoff JE. Mucous cysts. j Hand Surg Am.2010; 35A: 828-830.
4. Carballo CB, Nakagama Y, Sekiya I, Rodeo SA. Basic science of articular cartilage. Clin sporets med. 2017; 36(3): 413-425.
5. Poulter RJ, Davis TRC. Management of hypertension of the metacarpalphalangeal joint in association with trapezometacarpal joint osteoarthritis. J Hand Surg Eur.q2011; 30:280-284.
6. Umberhandt R, Isaacs J. Diagnostic considerations for monarticular arthritis of the hand and wrist. J Hand Surg Am.2012; 37(7); 1480-1485.
7. Dickson DR et al. Pyrocarbon proximal interphalangeal joint arhtroplasty: minimal five-year follow-up. J Hand Surg Am 2015; 40(11); 2142-2148.

Classics

1. Marmor L, Peter JB. Osteoarthritis of the hand.Clin Orthop Relat Res1969;64:164-74.PMID: 5793008
2. Plato CC, Norris AH. Osteoarthritis of the hand: age-specific joint-digit prevalence rates.  Am J Epidemiol1979;109(2):169-80. PMID: 425956