An 18-year-old girl presented to us with recurrent dislocation of patella. She had two previous surgeries, first one at the age of 16 years and the second surgery a year later, in two different hospitals. Lateral release and medial plication was done in 2007 and extensive lateral release and vastus medialis advancement was done in 2008. Unfortunately, the problem persisted and the patella continued to dislocate when she presented to us. On clinical and radiological examination, she had generalized ligamentous laxity, apprehension test was positive and the medial patellar glide was <1/4, indicating a tight lateral retinaculum. Tibial tubercle- trochlear groove (TT-TG) distance, a measure of Quadriceps angle by CT scan was 23.2 mm. Patella alta measurement by Caton Deschamps's index was 1.2. CT showed Patellar tilt angle of 43 degrees, Type ‘C’ Dejour's trochlear dysplasia ie. lateral femoral convexity and medial femoral hypoplasia [Figures –].\nShe underwent sulcus deepening trochleoplasty as described by Dejour and medial patellofemoral ligament (MPFL) reconstruction along with lateral retinacular release. Through a midline skin incision and medial parapatellar arthrotomy, the trochlea was exposed under tourniquet control. The peritrochlear periosteum and synovium were incised about 5 mm from the trochlear cartilage margin. This width of 5 mm of the bone will correspond to the prominence of the trochlea (distance between the anterior cortex of the femur and the boundary of the trochlear cartilage). The cortex was osteotomized in the same plane and an osteochondral flap of about 5 mm thick was raised in “V” shape. The trochlear sulcus was referenced off the intercondylar notch, and was mapped proximally and 6° laterally. A thin layer of cancellous bone was removed with a curette up to the notch, more in the middle of the trochlea. The trochlear bone shell was impacted into the trough created in the cancellous bone. However, the sulcus formed was not deep enough. Hence, to achieve sufficient correction, we split the cartilage along the center of the groove. The newly established trochlea was fixed with two small staples astride the osteochondral junction, one on either side of the groove. There was no impingement as the knee was taken through its range of motion. The peritrochlear periosteum and the synovium were sutured.\nAfter this procedure, we reconstructed the MPFL, as described by Erasmus, but with a few variations. A double-looped semitendinosus tendon was anchored to the medial border of patella at the junction of upper and middle thirds, typically where the perimeter of patella becomes more vertical with a titanium anchor. A tunnel was drilled at the isometric point on the medial femoral epicondyle through which the tendon was pulled through and was fixed with a biodegradable interference screw []. Medial patellar retinaculum was repaired at this ligament. Lateral retinacular release was done from inside out prior to the reconstruction of medial patella ligament since medial patellar glide was restricted in our patient. Since the new trochlear groove was angled at 6° laterally, distal realignment by tibial tubercle osteotomy was not done.\nA hinged knee brace to allow 30° flexion was used for 3 weeks. Daily knee flexion exercises were allowed. Weight bearing was allowed from the first day using crutches.\nOne year following the surgery, she had slight medial parapatellar tenderness and no patellar apprehension. Presently, terminal 5° of flexion is restricted. Radiological signs of trochlear dysplasia were corrected and patellar tilt angle improved from 48° to 18° . Kujala score improved from 52 to 80 points. Staples were removed 1 year after surgery. Near-normal looking trochlea surface was seen in postoperative computed tomography (CT) scan and during arthroscopy [].
The patient was an 11-year-old Caucasian boy without any relevant familiar history or comorbidity. He referred to our clinic complaining disability in walking and running with frequent falls (due to the lack of power in knee extensor mechanism). His parents said that despite the absence of pain, the functional limitation of both his knees was at the base of a serious psychological discomfort, conditioning his relationship with peers.\nOn objective examination, his lower limbs revealed mild genu valgum and tibial proximal lateral torsion. Both patellae were on the lateral aspect of the femoral condyle displacing even further during knee flexion. Femoral quadriceps function was present but this muscle was working as a flexor instead of extensor of the knee. It was observed that he was unable to actively extend both knees from the flexed position; passive range of motion (ROM) was complete and was not painful. At the upper limbs, there was a mild deficit in ROM of both elbows. There were no pathological deviation of the spine; normal clinical finding of both feet. The anterior-posterior lateral and axial knee X-rays showed bilateral, superolaterally displaced and hypoplastic patellae and reduction of the trochlear groove (, , ).\nThe extensor mechanism was studied by magnetic resonance imaging (MRI): Both quadriceps were hypotrophic with the vastus medialis enveloped over the trochlear groove which appeared flattened and dysmorphic. The patellar tendons were bilaterally lateralized and stretched. The anterior cruciate ligament could not be identified. On both sides, MRI confirmed the lateral dislocation of the patellae ().\nElbows X-ray showed a slight posterior dislocation of the radial head and absence of radioulnar synostosis. The diagnosis of CDP was confirmed. Surgical correction of the deformity was then proposed to regain walking and running function, with the aim of reduce the grade of the deformity improving the patient quality of life and his psychological well-being.