Abstract
Several combined procedures have been reported for treating recurrent patellofemoral
instability (RPI) with various types and severity of morphological abnormalities,
but none have identified absolute threshold values as indications for surgery. We
performed medial patellofemoral ligament (MPFL) reconstruction combined with a modified
Elmslie–Trillat (ET) procedure on 24 knees (10 male and 11 female patients) to treat
RPI with morphological abnormalities corresponding to elevated tibial tubercle–trochlear
groove (TT–TG) distance, significant patella alta, and trochlear dysplasia. The inclusion
criteria were RPI with morphological abnormalities corresponding to one or more of
the following: sulcus angle > 160 degrees, trochlear dysplasia of Dejour classification
C or D, Caton–Deschamps index > 1.5, lateral shift ratio > 50%, congruence angle > 15 degrees,
or TT–TG distance > 20 mm, including habitual dislocation of the patella. Skeletally
immature patients and those with congenital dislocation of the patella were excluded.
The Kujala score, International Knee Documentation Committee subjective score, Knee
Injury and Osteoarthritis Outcome score (KOOS), and each item of the KOOS improved
significantly after surgery. Patellar apprehension sign was present preoperatively
in all cases, but all disappeared postoperatively. No instance of postoperative redislocation
was observed. On radiographic examination, the mean Q angle, tilting angle, lateral
shift ratio, congruence angle, Caton–Deschamps index, Insall–Salvati index, and TT–TG
distance improved significantly after surgery. There were no significant differences
in sulcus angle after surgery. These results suggest MPFL reconstruction combined
with a modified ET procedure provides satisfactory outcomes based on radiological
and clinical evaluations for RPI with morphological abnormalities corresponding to
elevated TT–TG distance, significant patella alta, and trochlear dysplasia.
Keywords
recurrent patellofemoral instability (RPI) - medial patellofemoral ligament (MPFL)
reconstruction - Elmslie-Trillat procedure
