Disorders of the Patellofemoral Joint

Anatomical patella instability risk factors on MRI show sensitivity without specificity in patients with patellofemoral instability: a systematic review

“…There are reference ranges for patellar height ratios measured on radiograph, with patella alta defined as CD index >1.2,52 IS ratio >1.2 28 53 54. There is not yet consensus on the reference range for normal patellar height on CT and MRI.…”

Midterm Results of Comprehensive Surgical Reconstruction Including Sulcus-Deepening Trochleoplasty in Recurrent Patellar Dislocations With High-Grade Trochlear Dysplasia

“…Patients with recurrent patellar dislocations and trochlear dysplasia were treated according to the presence of concomitant predisposing anatomic abnormalities, and trochleoplasty was combined with other procedures when needed. 12,14,15,18,28,31 If the TT-TG distance was greater than 20 mm, tibial tuberosity medialization osteotomy was performed to obtain a TT-TG distance between 10 and 15 mm 14,18 ; if patella alta was recorded (Caton-Deschamps index .1.2), distalization osteotomy was performed to obtain a normal patellar index of 1.0 14,18 ; if the lateral patellar tilt was greater than 20°, a correction was performed with vastus medialis obliquus (VMO) plasty or reconstruction of the medial patellofemoral ligament (MPFL) using a double-looped gracilis tendon graft. 3,14,18,30 Sulcus-deepening trochleoplasty was performed with the same surgical technique in all patients 16 (see Video Supplement for details).…”

The development, validation and internal consistency of the Norwich Patellar Instability (NPI) score

“…Patellar instability is a generic term encompassing patellar dislocation, subluxation and symptoms of generalised patellar laxity or instability [1, 13]. It is a disabling condition most prevalent in younger people and more frequently seen in females compared with males [9].…”