Results of a trochlear osteotomy for patellar instability in patients with trochlear dysplasia: a 12 year follow-up

Patellofemoral instability (patellar dislocations) is a frequent problem in
orthopaedic practice. In general, a patellar dislocation can be treated
conservatively. However, in case of recurrent patellar dislocations an anatomic
malformation might underly the instability. In this case an operative
correction of this malformation is indicated. One of these malformation is
trochlear dysplasia. In trochlear dysplasia the femoral trochlear groove is
more shallow, which leads to less osseous restraint on the patella which tracks
through the trochlear groove. Therefore the patella is allowed to track more
laterally and even dislocate. This condition can be treated by a trochlear
osteotomy in which an anterior open wedge osteotomy of the lateral femoral is
performed. This open wedge osteotomy is secured by a small bone graft.
We have been performing this technique over years with satisfactory results. In
the past we have published the short (2 year) results (Trochlear osteotomy for
patella instability: satisfactory minimum 2-year results in patients with
dysplasia of the trochlea. Koëter et al. Knee Surgery Sports Traumatology and
Arthroscopy (2007) 15:228-232). However it remains unclear what the long-term
results are. In particular, the development of patellofemoral osteoarthritis as
the tracking of the extensor mechanism of the knee has been altered.
Therefore we want to describe the long term results (12 years) of a trochlear
osteotomy in this group of patients.

The aim of this study is to evaluate the long-term (12 year) results of the
above described trochlear osteotomy.

This objective can be further specified by the following:
Do the results a trochlear osteotomy at 12 years follow-up remain identical to
the results at 2 years follow-up or is there a change in the effect over time?
Do patients with a trochlear osteotomy develop patellofemoral osteoarthritis
and/or tibiofemoral osteoarthritis?

The patients have all been included at the time of operation for this study
(1995-2002). Recently, all patients were again approached if they still wanted
to participate in this study and the vast majority has responded positively.
Patients will be contacted for a single outpatient visit to the Radboud
University Medical Center, Nijmegen.

The patients will be asked a to fill out a number of function scores: VAS-pain,
Lysholm and Kujala scores and a short interview will be conducted with regard
to patellar instability and any procedure which might have been performed since
the last follow-up. In addition, specific physical examination and additional
conventional radiography of the operated knee are carried out (AP, lateral and
skyline patella).

The results of this study will be described in a scientific article similar to
the article in which the 2-year results were published (Trochlear osteotomy for
patella instability: satisfactory minimum 2-year results in patients with
dysplasia of the trochlea. Koëter et al. Knee Surgery Sports Traumatology and
Arthroscopy (2007) 15:228-232).

The risks associated with this study consist of the risks of an AP, lateral and
axial radiographs of the operated knee(s). The burden consists of a single
outpatient visit to the Radboud University Medical Center where conventional
radiographs of the knee(s) will be made and they will be interviewed and will
undergo a physical examination.