J Korean Orthop Assoc.  2014 Jun;49(3):239-243.

Arthroscopic Treatment of Delayed Patella Infera

• Yoon JR
• Oh KJ
• Seo HS
• Yang JH

Abstract

Patella infera (baja) is a rare condition that can result from several etiologies including trauma around the knee. Risk factors include scar tissue formation in the retropatella fat pad, extensor mechanism dysfunction, immobilization in extension position of the knee joint, etc. Unawareness and delayed recognition are known to be associated with long-term disability. In this condition, arthroscopic treatment is generally recommended only for early cases. In this report, we present a case with reasonable outcome of delayed patella infera treated by arthroscopic treatment. Prudent arthroscopic debridement of the responsible scar tissue and accelerated rehabilitation therapy is necessary for achievement of a successful outcome.

Keyword

patella infera; delayed; arthroscopic debridement; accelerated rehabilitation

MeSH Terms

Adipose Tissue
Cicatrix
Debridement
Immobilization
Knee
Knee Joint
Patella*
Rehabilitation
Risk Factors

Figure

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  Figure 1 Preoperative radiographs. Patella infera is shown at 7, 8 months after initial trauma. (A) Initial radiograph showing a minimally displaced transverse fracture at the inferior pole of the patella. (B) Post-trauma 5 month radiograph showing progression of union without patella infera. (C) Post-trauma 7 months, and (D) 8 months after trauma.

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  Figure 2 Hypertrophied soft tissue (white arrows) extending from the retropatella fat pad area to the medial retinaculum was observed on preoperative magnetic resonance imaging. Thickened patella tendon with signal change (arrowheads) was also identifiable. (A) Axial T2 proton density fat suppression images. (B) Saggital T2 fat suppression images.

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  Figure 3 Arthroscopic examination revealed thickened fibrotic scar tissue (asterisks) extending from the retropatella fat pad area to the medial retinaculum tethering the patella tendon.

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  Figure 4 Postoperative follow-up radiographs. Progressive improvement of patella position is visible. (A) Postoperative 1 month, (B) postoperative 6 months and (C) 12-month follow up radiograph. The Insall-Salvati ratio was calculated to 0.55.

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