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Journal Club

February 2010

Cartilage Lesions and the Development of Osteoarthritis After Internal
Fixation of Ankle Fractures: A Prospective Study

Sjoerd A. Stufkens, Markus Knupp, Monika Horisberger, Christoph Lampert and Beat Hintermann
J Bone Joint Surg Am. 2010;92:279-286.

Study Type

• Prospective cohort observational study
• Level II evidence

Location

• Liestal, and Kantonsspital, St. Gallen, Switzerland

Funding

• AO grant and SUVA grant
• Swiss accident insurance fund

Aim

• Examine correlation between cartilage damage at arthroscopy after a displaced ankle fracture and the clinical and radiographic long-term.

Hypothesis

• That the more extensive the initial cartilage damage, the higher the chance of osteoarthritis developing later

Inclusion/exclusion criteria

• Inclusion
  • ORIF of ankle fracture
  • Had an ankle arthroscopy after surgery
  • Available for follow –up
• Exclusion
  • Systemic inflammatory disease
  • Previous ankle injury
  • Suboptimal fixation
  • Lateral displacement/fibula shortening

Outcome Parameters

• Clinical results
  • American foot and ankle society hindfoot score
• AP and Lateral X rays
  • Kannus arthritis score
  • Based on; Sclerosis/osteophytes/calcification of ligaments/ joint space narrowing/cysts

Method

• Arthroscopy prior to ORIF ankle
• Grading of defect to type and location
• Follow up with X- rays and clinical asssesment by independent clinician
• Mean follow up 12.9 years  (11.3 – 14.8)

Site of lesion

• ten possible locations of the cartilage lesions
  • medial malleolus
  • lateral malleolus
  • anterior, medial, lateral, and posterior aspects of the tibia
  • anterior, medial, lateral, and posterior aspects of the talus

Statiscal analysis

• Divided into 2 groups
  • No lesion
  • Lesion
    • < 50% depth
    • >50% depth
  • Kannus arthritis score set to <90 points = joint degeneration
  • AOFAS score set to <90 points = less than optimal outcome 
  • Multiple regression analysis
    • Odds ratios with 95% confidence intervals of OA occuring versus not.

  Age, sex, BMI included in analysi

Results

• 81% have some form of cartilage lesion
• 65% talus have lesion
• 50% lesion on tibia
• 39% lesion in fibula
• 21% all three surfaces
• 19% no cartilage damage

Incidence of OA

• Osteoarthritis  Kappan < 90
  • 43%
• Clinical signs of osteoarthritis, AOFAS < 90   
• 39%

Results statistics

• If cartilage damage present
  • Suboptimal Clinical odds 5:1
  • Xray changes odds 3.5:1
• Sites:
  • Tibia – 2.7
  • Talus – 3.7
  • Fibula – no increase
• Depth >50%
  • Anterior talus  - 12.3
  • Lateral talus   - 5.4
  • Medial M . – 5.2
  • Post plafond – 4.7

Conclusions

• Initial cartilage damage after an ankle fracture is an independent predictor of posttraumatic osteoarthritis.
• Lesions on the talus and tibia are associated with negative long-term results, whereas lesions on the fibula do not correlate with a worse long-term outcome.
• Specifically, deep lesions on the anterior and lateral aspects of the talus and on the medial malleolus correlated with an unfavorable clinical outcome.

Pros.

• Defining a clinical natural history which has previously not been well documented
• Prospective cohort study with reasonable follow up period
• Clear outcome variables with blinded clinicians

Cons.

• State that cartilage damage is an independent predictor
  • Do not correlate a no lesion group with development of OA
• No specification of ankle fracture grade and the location – grade of lesions or correlation of arthritic changes
• Poor follow up
• Stated no patient did not return due to a poor outcome
• 109 out of 288
• No specification of type of fixation / diastasis screw which may affect outcome
• No arthroscopy, MRI at follow up

Applicability

• Guide to advise patients of risk of developing OA
  • May allow lifestyle modifications
  • Who to follow up more regularly