Updated: 6/11/2021

TKA Heterotopic Ossification

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  • summary
    • TKA Heterotopic Ossification is a complication of TKA with bone formation in the soft tissues that develops after surgery with or without a precipitating event.
    • Diagnosis can be made with plain radiographs of the knee.
    • Treatment is observation in majority of cases as HO rarely impacts clinical outcome. Surgical excision is indicated in the presence of quadriceps muscle snapping, patellofemoral tracking difficulties, or patellofemoral instability.
  • Epideomiology
    • Incidence
      • rates range from 1% to 42%, but less than 1% have any impact on clinical outcome
      • much less frequent than after total hip arthroplasty (THA)
    • Risk factors
      • hypertrophic arthrosis
      • male gender
      • obesity
      • periosteal injury/stripping off anterior femur
      • post-op knee effusion or hematoma
      • post-op forced manipulation for restricted motion
  • Etiology
    • Pathophysiology
      • any bone formation in the soft tissues (other than periosteum) that develops after surgery with or without a precipitating event
      • distinct from myositis ossificans, which evelops after traumatic muscle injury and inflammation
  • Classification
    • Furia and Pellegrini classification system
      IA
      Island of bone localized to suprapatellar soft tissues;  less than or equal to 5 cm
       
      IB
      Island of bone localized to suprapatellar soft tissues; greater than 5 cm
      IIA
      bone organized into areas of ossification contiguous with the anterior distal femur; less than or equal to 5 cm
       
      IIB
      bone organized into areas of ossification contiguous with the anterior distal femur; greater than 5 cm
  • Presentation
    • Symptoms (rare)
      • loss of motion
      • pain
      • quadriceps muscle snapping
      • patellofemoral instability
  • Imaging
    • Radiographic evaluation
      • recommended views
        • AP
        • lateral
      • findings
        • ossification along anterior distal aspect of femur and within quadriceps mechanism
          • typically visible 3-4 weeks post-operatively and matures within 1-2 years
  • Prevention
    • High-risk patients, generally those undergoing THA and not TKA
      • external beam radiation therapy
      • pharmaceutical prophylaxis with NSAIDs
    • no literature regarding these therapies in TKA patients
  • Treatment
    • Nonoperative
      • observation
        • indications
          • in majority cases as HO rarely impacts clinical outcome
    • Operative
      • surgical excision
        • indications
          • quadriceps muscle snapping
          • patellofemoral tracking difficulties
          • patellofemoral instability
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Flashcards (2)
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Questions (1)

(OBQ10.270) A 55-year-old patient is scheduled for total knee arthroplasty. A radiograph is provided in Figure A. Each of the following are risk factors for heterotopic ossification EXCEPT?

QID: 3253
FIGURES:
1

Incorrect sizing of femoral and/or tibial components

58%

(1300/2232)

2

Male gender

11%

(236/2232)

3

Obesity

18%

(391/2232)

4

History of trauma

3%

(56/2232)

5

Presence of preoperative osteophytes (hypertrophic arthrosis)

11%

(238/2232)

L 3 B

Select Answer to see Preferred Response

Evidence (2)
EXPERT COMMENTS (1)
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