*4.2.5 Trochleoplasty*

Different surgical techniques have been developed to correct the pathologic trochlear morphology seen in patients with recurrent patellofemoral instability. These techniques include deepening of a shallow or flat trochlear groove (trochleoplasty), elevation of the anterior portion of the femoral condyles (trochlear osteotomy), and/or removal of a prominent trochlear bump. Numerous variations in these techniques and retrospective case series of their results have been reported. However, there are no prospective, randomized controlled studies in the literature that support the use of these techniques [30]. Trochleoplasty is more popular in Europe. There are concerns about possible irreversible damage to the articular cartilage and subchondral bone of the femoral trochlea, and these concerns have limited the use of trochleoplasty in the United States.

Trochleoplasty is a complex, challenging and technically demanding surgical procedure. Several authors have reported their experience with the use of trochleoplasty in the management of trochlear dysplasia in patients with patellofemoral instability [67, 68, 86–95]. Indications for a sulcus-deepening trochleoplasty include abnormal patellar tracking with a *J-sign*, usually manifested by a TT-TG distance of greater than 10 to 20 mm, and/or a dome-shaped trochlea noted on a perfect lateral radiograph of the knee with overlap of the posterior femoral condyles, and radiographic evidence of trochlear dysplasia in a patient with recurrent patellofemoral instability [89]. In a trochleoplasty procedure, a strip of cortical bone around the edge of the trochlea is elevated and the cancellous bone of the trochlea is exposed. The new trochlear sulcus is then created, proximal and about 3 to 6 degrees lateral to the previous sulcus, by removing the cancellous bone. Next, the trochlear bone shell is impacted into the new sulcus and fixed with two small staples. Alternatively, the bone shell can be secured using resorbable sutures [87, 90]. Early postoperative complications include arthrofibrosis and bothersome patellofemoral crepitus. Meticulous surgical technique in combination with postoperative continuous passive motion (CPM) are vital for maintaining range of motion of the knee and to ensure optimal clinical outcome.

Von Knoch et al. [90] reported the clinical and radiological outcome of trochleoplasty for recurrent patellar dislocation in association with trochlear dysplasia. Thirty-eight consecutive patients (45 knees) were treated by trochleoplasty, medial reefing, with or without reconstruction of the MPFL. The patients were reviewed at a mean follow-up of 8.3 years (range, 4 to 14 years). A total of 33 knees were available for radiological assessment. None of the patients had recurrence of dislocation after trochleoplasty. Preoperatively, patellofemoral pain was present in 35 knees. Postoperatively, 15 (43%) of 35 knees had worsening of the patellofemoral pain. The most recent Kujala score averaged 95 points (range, 80 to 100 points). The depth of the trochlea increased and the trochlear boss height was reduced. Although trochleoplasty was effective in preventing future patellar dislocations, it did not halt the progression of patellofemoral arthritis. At latest follow-up, ten (30%) of the 33 knees had osteoarthritic changes in the patellofemoral compartment.

Rouanet et al. [95] reported the long-term results of sulcus deepening trochleoplasty for patellofemoral instability. In their study, 34 cases were reviewed after a mean follow-up of 15 years (range, 12 to 19 years). No recurrent objective instability was observed. Seven knees had additional surgery after a mean follow-up of 7 years. Furthermore, 7 cases required conversion to total knee arthroplasty because of progression of osteoarthritis. Overall, there was an improvement in the knee function postoperatively. Patients were satisfied in 65% of the cases. At the time of the final follow-up, osteoarthritis was present in 33/34 cases. The authors concluded that the sulcus deepening trochleoplasty corrects patellofemoral instability in patients with severe trochlear dysplasia and the long-term functional outcome is better in this group. However, it does not prevent patellofemoral osteoarthritis. The sulcus deepening trochleoplasty procedure should be limited to patients who have severe trochlear dysplasia in conjunction with supratrochlear spurs, and this procedure should be combined with other surgical techniques to realign the extensor mechanism of the knee.

In conclusion, we believe that trochleoplasty has a limited but important role in the management of patients with recurrent patellofemoral instability with concurrent moderate-to-severe trochlear dysplasia. In such cases, trochleoplasty should be undertaken in combination with other surgical procedures, such as MPFL reconstruction or distal realignment procedure.

#### *4.2.6 Medial Patellofemoral Ligament (MPFL) Reconstruction*

Various authors have reported that the MPFL is universally disrupted in patients with lateral patellar dislocation and that its integrity is of primary importance to maintain stability of the patella [6, 8, 9, 72, 75, 96]. Hence, it is important to

#### *Patellofemoral Instability DOI: http://dx.doi.org/10.5772/intechopen.99562*

undertake reconstruction of MPFL (when indicated) in patients with recurrent patellofemoral instability to restore the patellofemoral biomechanics and kinematics. Medial patellofemoral ligament reconstruction has become one of the most common and widely used procedures to regain stability in patients with recurrent lateral dislocation of the patella. Recent studies have demonstrated low recurrence rates, improved patient-reported outcome measures, and a high rate of return to sports. Reconstruction of the MPFL is typically indicated for patients with recurrent patellofemoral instability, with or without trochlear dysplasia, who have a normal TT-TG distance and a normal patellar height. The procedure may be performed with concomitant procedures, such as distalization of the tibial tuberosity in a patient with patella alta, or trochleoplasty in a patient with high-grade trochlear dysplasia.

Numerous surgical techniques have been reported for reconstruction of the MPFL. A detailed description of all available techniques is beyond the scope of this chapter. The MPFL reconstruction can be performed using various sources of graft material, such as the medial retinaculum [97], adductor magnus tendon [98–102], patellar tendon [103, 104], quadriceps tendon [105–115], and most commonly, hamstring tendon (gracilis or semitendinosus tendon) [116–136]. In general, about 80–96% good to excellent results following isolated MPFL reconstruction have been reported.

Over the years, various methods of fixation of the tendon graft have been reported; these methods of fixation include staples, spiked washers, sutures, bone tunnels, interference screws, and bone anchors [30]. It is worth noting that variation in the location and length of the graft can greatly alter the compressive forces at the medial aspect of the patellofemoral joint [30].
