Bipartite Patella

synonyms: bipartite, tripartite patella

Bipartite Patella ICD-9

• 755.64 (congenital deformity of knee joint): absence of patella, genu valgum, genu varum, rudimentary patella

Bipartite Patella Etiology / Epidemiology / Natural History

• Failure of ossification of complete ossification of the patella.
• Occurs in 2-6% of the population.
• 50% will be bilateral
• Male:female = 9:1

Bipartite Patella Anatomy

• The patella is the largest sesmoid bone in the body.
• Primary ossification center appears to 4-6 years old. Secondary centers at 12 years old.

Bipartite Patella Clinical Evaluation

• Generally asymptomatic. 2% symptomatic.
• Generally men <20years old involved in sports.
• Anterior knee pain. May initially become symptomatic after an injury. Worse with squatting, climibing stairs
• May have localized tenderness on exam.

Bipartite Patella Xray / Diagnositc Tests

• Generally easily identified on plain knee films.
• Bone scan: low specificity for symptomatic bipartite patella. 81% of asymptomatic patients will have increased uptake. (Oohashi Y, Knee Surg Sports Traumatol Arthrosc 2007;15:1395)
• MRIL fat-suprressed T2-Weighted images may demonstrate bone marrow edema in the bipartite fragment in symptomatic patients.

Bipartite Patella Classification / Treatment

• Saupe Classification: Type I:inferior pole of the patella (5%). Type II:lateral margin (20%). Type III:superolateral pole (75%) (Saupe H, Deutshe Z Chir 1943;258:386).
• Conservative: rest, reduced sports, NSAIDs, quad stretching, dynamic patellar brace
• Surgery: excision, lateral retinacular release, vastus lateralis release, ORIF

Bipartite Patella Associated Injuries / Differential Diagnosis

• Patella Fracture
• nail-patella syndrome

Bipartite Patella Complications

• Patellar instability
• Incomplete relief of pain
• Nonunion

Bipartite Patella Follow-up Care

Bipartite Patella Review References

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