Medial Patellofemoral Ligament Reconstruction Using Quadriceps Tendon

Christian Fink

Mirco Herbort

INTRODUCTION

Pathogenesis

Tear of the medial patellofemoral ligament (MPFL) has been reported in 95% to 100% of patients with acute patellar dislocation.¹,²,³ Therefore, reconstruction of the MPFL for the treatment of patellar instability has achieved increased attention over the past few years, either as an isolated procedure or with concomitant tibial tuberosity transfer, trochleoplasty, or rotational osteotomy.
MPFL reconstruction has a high rate of success for patellar stabilization.⁴,⁵,⁶,⁷ However, in a systematic review on MPFL reconstruction, Shah et al reported an overall complication rate of 26.1%.⁸ In this review, 4 patients sustained a patellar fracture through transpatellar bone tunnels, and 22 patients had residual flexion loss of which 9 underwent manipulation under anesthesia. Similarly, Parikh et al⁹ reported an overall complication rate of 16.2% in 179 knees that underwent MPFL reconstruction; 6 patients had patellar fractures, and 8 patients had stiffness with flexion deficits.
Two potential reasons are attributed to these complications. First, an incorrect placement of the MPFL femoral insertion may lead to patellofemoral overload and loss of flexion. Second, the higher stiffness of the reconstructed MPFL compared to the native MPFL can lead to increased stress on the patellofemoral joint.¹,¹⁰
Hamstring grafts are more commonly used for MPFL reconstruction compared to the quadriceps tendon (QT) grafts. In a biomechanical study, Lenschow et al¹¹ found that the stiffness of hamstring construct was about three times higher than the native MPFL; thus, even minimal malpositioning or overtensioning of the graft may lead to increased stress on the patellofemoral joint. In a human cadaveric study, the authors investigated the biomechanical characteristics of a 3-mm-thick and 10-mm wide QT graft and found that the maximum load to failure, yield load, and stiffness were similar to the native MPFL.¹²
Despite potential biomechanical and anatomic advantages of MPFL reconstruction using QT graft, the cosmetic appearance of longitudinal scars over the thigh (Figure 8.1) as well as the technical difficulties in harvesting a uniform 2- to 3-mm strip of the QT have may precluded widespread use of this technique.

Figure 8.1 Example of a hypertrophic scar following conventional, open quadriceps tendon harvest.

TABLE 8.1 Indications and Contraindications for Medial Patellofemoral Ligament Reconstruction Using Quadriceps Tendon

Indications	Contraindications
Acute or recurrent patellar instability Ideal when combined with trochleoplasty because no additional skin incision is necessary Revision setting where hamstring tendons were utilized at index surgery Revision setting where previous tunnels or hardware would preclude patellar fixation Small or fractured patella where drilling is not desirable	Previous injury to the quadriceps tendon and/or at its insertion onto the patella Weak or atrophied quadriceps muscle If risk factors such as severe torsional malalignment or severe trochlear dysplasia are not taken into consideration, isolated medial patellofemoral ligament reconstruction is more likely to fail.

There are few clinical studies focused on MPFL reconstruction using a strip of QT.¹³,¹⁴,¹⁵,¹⁶ In these studies, an open QT harvesting technique has been utilized. The harvest is performed using a longitudinal skin incision from the superior pole of the patella extending proximally for about 6 cm. Good-to-excellent results with minimal complications have been reported with MPFL reconstruction using QT.¹³,¹⁶
To reduce further the morbidity and facilitate graft harvest, the authors have developed a minimally invasive surgical technique for QT harvest.¹⁷,¹⁸
MPFL reconstruction using QT has several other advantages: It would avoid implants or tunnels in the patella; thus, it would avoid risk of patellar fracture. Because no implants are used, it would be economically advantageous. It would be applicable in the presence of open growth plates and would represent an ideal revision option for a failed hamstring MPFL reconstruction. It would also spare hamstring tendons for potential use in future ligament reconstructive procedures (Table 8.1).

Figure 8.2 Cadaveric dissection of (A) native medial patellofemoral ligament (MPFL) (white arrows) compared to (B) MPFL reconstruction using quadriceps tendon strip (white arrows) in a right knee specimen.

Applied Anatomy

The MPFL is flat bandlike structure. Gross morphologic appearance of a QT strip more closely resembles the native MPFL compared to tubular hamstring graft construct (Figure 8.2).
The insertion of the quadriceps femoris into the patella is through a common tendon with a trilaminar arrangement.¹⁹,²⁰,²¹ The superficial fibers originate from rectus femoris, the deepest layer from the vastus intermedius and the intermediate layer from the vastus lateralis and vastus medialis. The laminae fuse with a degree of individual variation over a 13- to 90-mm region (mean 44 mm) proximal to the superior pole of the patella.²⁰

Figure 8.3 Positioning of the patient. A, The operative, left knee is placed in an electric leg holder. B, Access and visualization by fluoroscopy is checked prior to draping.
The QT inserts into the patella via an expansion that passes over the anterior aspect of the patella, most commonly comprised of fibers from the rectus femoris portion of the tendon.²⁰ A partial-thickness graft can be harvested by identification of the superficial lamina of the QT (rectus femoris) approximately 2 to 3 cm proximal to the patella. This is the preferred area to start QT harvest.

SURGICAL MANAGEMENT

Preoperative Planning

Physical examination of the patient should include patellar tracking with knee motion, evaluation of medial and lateral soft-tissue restraints of the patella, Q-angle and coronal plane alignment, and rotational alignment of the tibia and the femur.
Radiographic and magnetic resonance imaging evaluation should be completed to assess for trochlear dysplasia, tibial tuberosity-trochlear groove (TT-TG) distance, patellar height, patellar tilt, and medial structures.

Surgical Technique (Video 8.1

)

Positioning and Arthroscopy

Patient positioning has to allow free knee motion between 0° and 120°. A well-padded tourniquet is applied.
Examination under anesthesia is performed to assess patellar translation medially and laterally and to assess if the patella can be dislocated.
Intraoperative access for the fluoroscope is important and is checked prior to draping. The authors prefer to place the operative leg in an electric leg holder (Figure 8.3).
Arthroscopy is performed initially to inspect the articular cartilage in the patellofemoral joint and to evaluate patella tracking. The latter is best visualized through a superolateral portal.