**4.11 Postoperative rehabilitation protocol**

Postoperatively, the patient is weight bearing as tolerated with the brace in 0° to 30° of flexion for the first week, progressing to 60° of flexion by week 2 and 90° of flexion by week 4. With the assistance of a physical therapist, the patient


#### **Table 2.**

*Pearls and pitfalls of patellar footprint technique of MPFL reconstruction.\**


*Advantages and disadvantages of patellar footprint technique of MPFL reconstruction.\**

undertakes quadriceps strengthening (especially, the VMO) exercises for the first 6 weeks. At more than 6 weeks postoperatively, if patients have achieved a near-full range of motion and can maintain a strong quadriceps contraction, discontinuation of the brace is acceptable. **Table 2** highlights the pearls and pitfalls of the Patella Footprint Technique of MPFL reconstruction. **Table 3** outlines the advantages and disadvantages of our described operative technique. The surgical technique described in this chapter provides an easy to replicate anatomical MPFL reconstruction with suture anchor patellar fixation. However, future studies are warranted comparing the outcomes between different fixation options, as well as evaluating long-term clinical outcomes.

#### **5. Discussion**

Patellofemoral instability typically affects the young and athletically active patient population. Most physicians recommend an initial trial of nonoperative management for patients who present with first-time patellar dislocation, without intra-articular osteochondral fragments, severe injury to the medial patellar soft tissue stabilizers, and significant patellofemoral malalignment or dysplasia. One of the challenges around nonoperative management of patellar dislocation is the complexity of interventions offered and the various rehabilitation regimens that are practiced in different institutions. Numerous physical therapy protocols have been described. The goals of physical therapy are to decrease pain, restore the range of motion of the knee, strengthen the quadriceps musculature, address the deficiencies in the trunk, hip or foot biomechanics that may predispose to patellar instability, improve the joint function, enhance the quality of life, and increase patient satisfaction. Unfortunately, there are little data or validated, objective evidence to determine which nonoperative treatment regimen is best for the management of patients with acute patellar dislocation.

We are aware that some physicians recommend nonoperative management as the first-line treatment for patients with chronic, recurrent patellar instability. However, in our clinical experience (expanding over a period of 40 years), the nonoperative treatment of chronic patellar dislocations treated by an initial period of immobilization (using a cast or a brace) followed by rehabilitation has produced

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

less satisfactory clinical outcomes; many of these patients have continued knee symptoms and recurrent patellar dislocations. There remains a paucity of scientific evidence on how to optimally manage patients with recurrent patellar dislocation (particularly, whether these patients should be given an initial trial of nonoperative treatment, how long the nonoperative treatment should be continued, and when surgical intervention should be recommended). This remains a subject of further clinical research. We believe many of the patients with chronic, symptomatic, recurrent patellar dislocations have predisposing anatomical risk factors (**Table 1**) and these patients invariably require operative treatment.

The natural history of acute patellar dislocation is that of a relatively high rate of recurrent instability, and long-term functional limitations and inability to return to baseline level of activity. Hence, surgery often plays an important role in the management of these patients. Prospective randomized trials comparing different surgical techniques are needed to determine which treatment options provide optimal clinical outcomes with restoration of knee function, low recurrence rate of patellar instability, and decreased risk of patellofemoral arthritis. The main goal of surgery is to restore the integrity of the MPFL and optimize the alignment of the lower extremity.

The MPFL acts as an important checkrein during the first 30 degrees of flexion (before the patella engages with the trochlea), thus allowing for a smooth knee motion. Rupture of the MPFL is often seen in patients with recurrent lateral patellar dislocation, leading to abnormal patellofemoral contact pressures, and resulting in pain, knee dysfunction, and early-onset arthritis. Hence, it is vital to undertake anatomic MPFL reconstruction to restore the kinetics and biomechanics of the patellofemoral joint.

Medial patellofemoral ligament reconstruction has become one of the most common and widely used surgical 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. No gold standard currently exists for MPFL reconstruction. Various surgical techniques of MPFL reconstruction have been reported employing different methods of graft fixation and tensioning. A detailed description of all available surgical techniques is beyond the scope of this chapter. Shah and associates [146] performed a systematic review to determine the rate of complications associated with MPFL reconstruction. In their study, a total of 164 complications occurred in 629 knees (26%). Therefore, efforts must be made to develop new operative techniques in order to minimize potentially devastating complications and optimize clinical outcomes.

Numerous graft sources, operative techniques, and fixation methods have been described with favorable clinical outcomes for reconstruction of the MPFL for patients with symptomatic patellofemoral instability. Several surgical techniques have been reported for fixation of the graft to the patella; these techniques include the use of suture anchors, interference screws, and transosseous tunnels. However, to date, no particular method has emerged as superior with regard to clinical outcome. Formation of a stress riser in the patella can result in a catastrophic complication after MPFL reconstruction. Large-diameter (4.5 mm), transverse, or long-oblique patellar bone tunnels have been associated with an increased risk of patellar fracture after MPFL reconstruction [147]. Schiphouwer et al. [159] reported a retrospective case series of 179 patients (192 knees) who underwent MPFL reconstruction, with or without additional bony realignment procedures. In their series, MPFL reconstruction was performed using two, transverse patellar bone tunnels. Seven patients (3.6%) sustained a patellar fracture without adequate trauma. This study highlights the associated, increased risk seen with the use of transverse

patellar bone tunnel while performing MPFL reconstruction. Recently, Deasey et al. [161] have shown that the use of small-diameter (3.2-mm), oblique patellar bone tunnels was not associated with an increased risk of patellar fracture in comparison with the use of suture anchors for patellar fixation. Deasey et al. [161] concluded that the use of small (3.2-mm), short, oblique patellar tunnels can be a safe and reliable method of patellar graft fixation in MPFL reconstruction.

Russ and colleagues [154] have shown that the use of transpatellar bone tunnels with interference screw fixation offers a biomechanically stronger fixation as compared to the use of suture anchors. Despite being biomechanically weaker, Russ et al. [154] did find that suture anchor fixation nevertheless allows for a reconstruction that withstands greater mechanical loads before failure than the native MPFL. The use of suture anchors also minimizes the risk of violating the articular surface when reaming the tunnels and decreases the risk of patellar fracture. Song and colleagues [150] prospectively evaluated the clinical and radiographic outcomes following anatomic MPFL reconstruction using patellar suture anchor fixation for patients with recurrent patellar instability. Twenty patients (20 knees) were enrolled in this study. The median age of the patients was 21 years, and the median follow-up was 34.5 months (range, 24 to 50 months). Reconstruction was performed using a hamstring autograft fixed with two suture anchors at native patellar site of the MPFL. The preoperative Kujala scores were 52.6 ± 12.4 and the postoperative Kujala scores were 90.9 ± 4.5 (p < 0.001). The preoperative Lysholm scores were 49.2 ± 10.7 and the postoperative Lysholm scores were 90.9 ± 5.2 (p < 0.001). The Tegner score increased from 3.0 (range 1 to 4) preoperatively to 5.0 (range 4 to 7) postoperatively (p < 0.001). No patient experienced a patellar fracture or recurrent dislocation in their series. This study shows that anatomic MPFL reconstruction using two suture anchors is a reliable treatment option for management of patients with recurrent patellofemoral instability.

We have previously reported our surgical technique of MPFL reconstruction that uses two suture anchors along the patella for graft fixation to provide a biomechanically favorable construct [130]. In our clinical experience, anatomic MPFL reconstruction (utilizing the autogenous gracilis tendon and patella footprint technique) has produced satisfactory clinical and functional outcomes in majority of the patients. We emphasize that MPFL reconstruction requires precise graft placement at the anatomic origin and insertion points of the MPFL. Anatomic graft placement, appropriate graft length and tension are critical to prevent over-constraint of the patellofemoral joint while undertaking reconstruction of the MPFL. By utilizing two suture anchors in the patella, the MPFL footprint was secured in a single-bundle setting to restore the native MPFL anatomy and patellar stability [130]. Furthermore, we ensure a secure fixation by submerging the tail of the gracilis graft with the interference screw at the femoral footprint. We believe our Patellar Footprint Surgical Technique provides an easy to replicate anatomical MPFL reconstruction utilizing an autogenous gracilis tendon graft that is secured to the medial border of the patella using two suture anchors [130]. **Table 2** highlights the pearls and pitfalls of the Patella Footprint Technique of MPFL reconstruction. The advantages and disadvantages of our described surgical technique are outlined in **Table 3**. Future studies are warranted comparing the outcomes between different fixation options, as well as exploring the long-term clinical and functional outcomes.

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.

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

Distal patellofemoral realignment procedure (such as the anteromedial tibial tuberosity transfer) is indicated for patients with recurrent instability, who have an increased TT-TG distance, abnormally high Q-angle, patella alta, lateral and/or distal patellar chondrosis, and absence of trochlear chondrosis. The degree of anteriorization, distalization, and/or medialization of the tibial tuberosity depends on the presence of associated arthrosis of the lateral patellar facet and/or the presence of patella alta. It is worth noting that the distal realignment procedure is contraindicated in patients who have a normal TT-TG distance or in those patients who have associated proximal and/or medial patellar chondrosis.

Groove-deepening trochleoplasty is a complex and technically challenging surgical procedure. This procedure is indicated for patients with Dejour type-B and type-D trochlear dysplasia, whereas a lateral elevation or proximal recession trochleoplasty is indicated for patients with Dejour type-C dysplasia.
