Sports Medicine: Just the Facts

CHAPTER 71 • COMMON INJECTIONS IN SPORTS MEDICINE: GENERAL PRINCIPLES AND SPECIFIC TECHNIQUES 427

INDICATIONS

• Injections/aspirations are indicated for both diagnosis
  and therapy.
  
  
  1. Diagnosis:
     a. Synovial fluid analysis to rule out infection,
     traumatic, rheumatic, or crystal-induced etiol-
     ogy (see Table 71-1).
     b.To perform a therapeutic trial to differentiate
     various etiologies
     c. Imaging studies
     d. Synovial biopsy
  
  
  2. Therapy:
     a. To remove tense effusions to relieve pain and
     improve function
     b.To remove blood or pus from a joint
     c. For injection of steroids and other intra-articular
     therapies
     d. For therapeutic lavage of joints
  
  
  
  

Risks/Complications (Turner and McKeag,
2002 (see Table 71-2)

• Infection: The risk of postinjection infection is
  extremely rare, on the order of one infection per
  20,000 to 50,000 when sterile technique is used.


• Tendon rupture:Collagen atrophy and tendon rup-
  ture are rare but have been described in the literature.
  Injections into tendons should be avoided. In addition,
  injections into the synovial sheath or peritendinous
  region of major weight-bearing tendons (Achilles,
  patellar, and plantar fascia) should be done with cau-
  tion, and the athlete protected from weight-bearing
  exercise for a period of 2 to 4 weeks.


• Postinjection flare:This entity is seen in 2 to 10% of
  patients. In this setting the patient actually gets worse in
  the immediate 6–12 h after an injection. The steroid
  postinjection flare is thought to be secondary to a local
  reaction to the microcrystalline steroid suspension and
  is self-limited. The postinjection flare has also been

attributed to the preservative that accompanies the

anesthetic. The postinjection flare may be treated with

ice, activity modification, and a short-course of a nons-

teroidal anti-inflammatory drug (NSAID). Patients

with pain beyond 36 h should be evaluated for a septic

joint.

• Skin atrophy/depigmentation/hyperpigmentation:
  Whenlocal steroid is applied to close to the surface of
  the skin, local atrophy as well as depigmentation/
  hyperpigmentation can occur. These changes may be
  irreversible.


• Hyperglycemia: In some diabetics there may be
  short-term difficulties with glycemic control second-
  ary to the local absorption of corticosteroid.


• Cartilage degeneration: Limit injections into a
  weight-bearing joint to no more than three injections
  per year, as there is some concern about weakening
  articular cartilage (Turner and McKeag, 2002;
  Pfenninger, 1994; Genovese, 1998).


• Injection of a steroid/anesthetic agent into a vein or
  artery.


• Traumatic injection:Possible to cause a pneumoth-
  orax, damage articular cartilage, local nerves, or soft
  tissue structures.
  •Vasovagal reactions.

TABLE 71-1 Classification of Synovial Fluid

CLASSIFICATION APPEARANCE WBC PMNs% CRYSTALS CULTURE

Normal Clear to straw colored <150 <25 None Negative
Noninflammatory Yellow <3000 <30 None Negative
Inflammatory Yellow or cloudy 3000–75,000 >50 None Negative
Infectious Yellow or purulent 50,000–200,000 >90 None Positive
Crystal-induced Cloudy, turbid 500–200,00 <90 Ye s N e gative
Hemorrhagic Red-brown 50–10,000 <50 Νο Negative

SOURCE: O’Connell TX: Interpreting tests from joint aspirates, in Phenninger JL (ed.): The Clinics Atlas of
Office Procedures—Joint Injection Techniques:vol. 5 (no. 4). December 2002.

TABLE 71-2 Common Adverse Outcomes

COMPLICATION ESTIMATED INCIDENCE (%)

Postinjection flare 2 to 10

Steroid arthropathy 0.8

Tendon rupture < 1

Facial flushing < 1

Skin atrophy, depigmentation < 1

Iatrogenic infectious arthritis <0.001 to 0.072

Transient paresis of injected Rare

extremity

Hypersensitivity reaction Rare

Asymptomatic pericapsular 43

calcification

Acceleration of cartilage attrition Unknown

SOURCE: Gray RG, Gottleib NL: Intra-articular corticosteroids:

An updated assessment. Clin Orthop 177:253–263, 1983.