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 [].
A 70-year-old man had a 5-year history of bilateral knee pain, which had gradually worsened over the last one year, along with reduced walking distance secondary to bilateral osteoarthritis of the knee. He had no difficulty in daily life activities during childhood or adulthood. He had worked as a barber and had no history of trauma. There was no relevant family history. He walked with two crutches since developing bilateral knee pain and could not negotiate stairs. Conservative therapy at another medical clinic, including injection of hyaluronic acid into both knees, was not effective.\nWhen he first visited our institution, physical examination revealed conspicuous bilateral quadriceps atrophy. Both quadriceps were rated as having strength 3 on a muscle testing scale of 0–5. The patellas were palpable at the lateral side of the bilateral femoral condyle and had no mobility during flexion and extension. The proximal tibiae were rotated outward. Preoperatively, the passive range of motion in both knees was −10° to 130°. There was an extension lag of 45° at both knees. Effusions were present in both knees. The knees showed no signs of instability or ligamentous deficiency.\nRoentgenograms and computed tomography (CT) showed patellar dislocation and severe osteoarthritis of the bilateral knees with complete loss of the lateral compartment joint space (Figures –). Valgus deformity of 10° was observed in each knee on standing with the lower extremities aligned. The patient had more pain in the left knee than the right knee. TKA with correction of the extensor mechanism was planned first for the more painful left knee.\nA midline longitudinal skin incision was made under tourniquet control and lateral parapatellar arthrotomy was performed. The patella was located in the lateral gutter of the knee; the femoral condyle was hypoplastic. The medial retinaculum was thin. The vastus medialis oblique muscle was found to be located over the anterior aspect of the femur. For realignment of the extensor mechanism, we performed extensive medial and lateral retinacular release and distal realignment by tibial tubercle transfer. A posterior stabilized prosthesis (NexGen LPS-Flex; Zimmer, Inc., Warsaw, IN) was implanted and held in place with cement. Patellar resurfacing was not performed. The femoral component prosthesis was placed in 9° external rotation with reference to the posterior condyle line to facilitate patellar tracking. The iliotibial tract was partially detached from Gerdy's tubercle subperiosteally. The lateral collateral ligament and the popliteus tendon were also partially released from the lateral femoral condyle. The rotational alignment of the tibial component was based on the locations of the femoral components. After cementing the selected implants, the dislocated patella could not be reduced, so a proximal realignment procedure was performed as described by Insall et al. [], and the rectus femoralis tendon was lengthened by Z-plasty. Thereafter, the patella was in the groove during extension, but passive flexion angle was limited to 90° of flexion of the knee with the hip flexed to 90°. The lateral side of the arthrotomy could not be closed. Medial plication was performed as possible as we could. Finally, the patella could not be reduced fully and did not track centrally, but more laterally, in the patellofemoral groove throughout the full range of movement ().\nFull weight-bearing walking was allowed 7 days postoperatively with a brace for 0° angle restriction for 2 weeks. Range of motion (ROM) exercise using a continuous passive motion device was started 1 week after the operation. At 4 weeks after the operation, ROM was 0°–90° in the left knee and the patient was discharged with one crutch.\nAt 5 weeks after the operation, the patient slipped at home and fractured his left tibia. He was readmitted and conservative therapy was performed with a brace against the fracture. Three months later, his fracture was healed and he was discharged walking with one crutch ().\nOne year after the operation on the left knee, he had hoped to undergo right knee surgery because of pain. He was not satisfied with the restriction of flexion angle of the left knee and was concerned about future fractures. Therefore, he asserted that it was not necessary to reduce the dislocated patella and realign the extensor mechanism in the right knee.\nWe performed TKA using the same prosthesis in the right knee without realignment of the extensor mechanism and reduction of the patella. A midline longitudinal skin incision was made under tourniquet control, and medial parapatellar arthrotomy was performed. The femoral component prosthesis was placed in 3° external rotation with reference to the posterior condyle line. The right patella was located on the lateral side of the femoral component.\nAt the final follow-up one year after the right knee operation, the patient had full extension and 90° flexion in the left knee. There was an extension lag of 45° and flexion angle was 125° in the right knee. Left side quadriceps strength was improved to a rating of 4 on the muscle testing scale of 0–5, but that on the right side was not improved as before surgery. His walking ability was improved and he was satisfied with pain relief in both knees and walked with one crutch ().\nThe preoperative Knee Society score and functional scores were 40 and 15, respectively, which improved to 83 and 60, respectively, at the final follow-up.