Medial Patellofemoral Ligament Reconstruction Using Bone Tunnels
Najeeb Khan
Anthony Yu
Donald Fithian
INTRODUCTION
This chapter discusses the surgical technique of medial patellofemoral ligament (MPFL) reconstruction using bone tunnels.
In this described technique, femoral fixation of MPFL graft is performed first, followed by patellar fixation. This is in contrast to the technique described in Chapter 27, where patellar fixation is performed first, followed by femoral fixation.
Chapter 5 includes surgical considerations and preoperative planning for MPFL reconstruction in general. It also includes pertinent physical examination findings and findings on imaging studies.
Table 6.1 lists indications and contraindications for MPFL reconstruction.
SURGICAL MANAGEMENT
Preoperative Planning
Preoperative planning includes ensuring the availability of a fluoroscopy machine and technician, standard arthroscopy tower and instruments (if arthroscopy is planned), instruments for hamstring harvesting (if autograft harvest is planned), a drill set (3.2-, 3.5-, and 4.5-mm drill bits are sufficient), a curved suture passing device (the authors fashion one from a #18 wire), and sutures (#2 braided nonabsorbable suture to be used as a pull-out suture, 0-vicryl suture to secure the graft to the patella and for imbrication and closure of the retinaculum, and multiple #0 absorbable sutures on a taper needle to whipstitch the free and looped graft ends).
Semitendinosus autograft is preferred, but is an option.
TABLE 6.1 Indications and Contraindications for Medial Patellofemoral Ligament Reconstruction | ||||
|---|---|---|---|---|
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Equipment and Surgical Implants
Standard large C-arm fluoroscopy
Tendon stripper for hamstring harvest (if autograft is selected)
3.2-, 3.5-, and 4.5-mm drill bits
18-gauge wire or proprietary suture passer
7- and 8-mm Acorn reamers
Beath pin
Surgical Technique (Video 6.1 
)
)
The schematic diagrams for the surgical technique for MPFL reconstruction are illustrated using anteromedial (Figure 6.1) and axial (Figure 6.2) views.
Anesthesia and Positioning
General anesthesia is routinely used, with the option of a regional block.
Figure 6.1 Anteromedial schematic view of a right knee. The medial patellofemoral ligament (MPFL) is shown, along with the medial collateral ligament and adductor magnus tendon attachments to the medial femur. The MPFL originates from a ridge connecting the adductor tubercle and the epicondyle. The MPFL fans out as it runs anteriorly and laterally, to insert onto the proximal two-thirds of the medial patellar border. The MPFL is reconstructed by making one blind tunnel at the femoral attachment and two tunnels on the patella that enter at the medial articular margin and exit on the anterior (ventral) patellar surface. Reprinted from Miller MD, Chhabra A, Konin JG. Sports Medicine Conditions: Return to Play: Recognition, Treatment, Planning. Philadelphia, PA: Wolters Kluwer; 2013 with permission.
Figure 6.2 Axial schematic view of a right knee after medial patellofemoral ligament reconstruction. Reprinted from Miller MD, Chhabra A, Konin JG. Sports Medicine Conditions: Return to Play: Recognition, Treatment, Planning. Philadelphia, PA: Wolters Kluwer; 2013 with permission.
An adductor canal block is preferred because this does not typically alter motor function of the quadriceps.
The patient is positioned supine with the feet at the end of the operating table to allow visualization and control of the operative leg.
Tourniquet is applied and routinely used during surgery to provide a bloodless field.
A bump under the contralateral hip may occasionally be necessary to allow access to the anterior and medial knee.
Use of a sandbag at the foot to hold the knee in slight flexion (ideally 30°) can aid fluoroscopy and isometry testing of the graft. This position can also help tension the patellar tendon if this procedure is performed in conjunction with a tibial tubercle osteotomy.
The surgeon can stand either on the contralateral side from the operative extremity or at the foot end of the bed.
Prophylactic parenteral antibiotics are administered within 30 minutes of inflating the tourniquet and making an incision.
Examination Under Anesthesia/Arthroscopy
Examination under anesthesia includes an assessment of patellar mobility. The diagnosis of patellar instability requires that there be a soft or no endpoint to lateral patellar displacement at full extension and that
the patella be mobile enough to allow displacement out of the trochlea with the knee at 30° flexion.
A diagnostic arthroscopy may be done to diagnose and treat any chondral lesions. This is not routinely done unless there is an effusion and/or any evidence of a loose body or chondral lesion.
If arthroscopy is undertaken, the surgeon should include a view from the superolateral or the superomedial portal in order to better understand the degree and type of trochlear dysplasia (Figure 6.3). A trochleoplasty should be considered if a lateral trochlear bump that displaces the patella is encountered.
Graft Harvest and Preparation
A 3-cm vertical incision is made over the pes anserinus, midway between the anterior tibial crest and the posteromedial border of the tibia. Once the sartorius fascia is exposed, the gracilis and semitendinosus tendons can be palpated through the fascia. An incision is made through the fascia with care taken to avoid injury to the underlying hamstring tendons and the medial collateral ligament.
With the gracilis tendon left undisturbed, the semitendinosus tendon is identified immediately inferior to the gracilis and then sharply detached from the tibia. The gracilis and semitendinosus tendons coalesce distally, making identification of the semitendinosus easier proximally.
Metzenbaum scissors are used to free adhesions and fascial slips from the semitendinosus to the underlying structures.
Adequate graft length is a concern, whereas girth is not, because the harvested tendon will greatly exceed the reported biomechanical characteristics of the native MPFL.1 Ideal graft length is at least 240 mm. The gracilis typically does not meet the aforementioned length requirements and is, therefore, not harvested.
After placing a whipstitch in the free end of the semitendinosus tendon using a #0 absorbable suture, it is harvested using a closed tendon stripper.
The harvested tendon is prepared on the back table where residual muscle is removed and a whipstitch is placed on the other end, using #0 absorbable suture.
The doubled, or looped, graft should be at least 120 mm after trimming (240 mm total graft length). A longer graft will not pose a problem, but a shorter graft will not allow secure fixation at both ends without undue tension.
Figure 6.3 Arthroscopy from the superolateral portal.
Figure 6.4 The semitendinosus graft is prepared by suturing each of its ends, looping it over another suture to create a doubled graft, and then suturing the looped end for a length of 20 mm (dashed arrow). The total length of the doubled graft is around 120 mm. Both ends of the graft are tapered (black arrows) to allow easier passage through patellar tunnels.
Once both sides of the graft have been secured with #0 suture, the graft is folded in half and a nonabsorbable braided suture is passed through the loop. This will be used to pull the doubled graft into the femoral tunnel. The two free ends should be prepared to pass through the individual medial patellar tunnels. A baseball stitch 20 mm in length with a 2-0 absorbable suture is placed at the looped end of the graft, which almost always will fit into a 7- or 8-mm femoral tunnel (Figure 6.4).
Alternatively, a semitendinosus allograft is used. For patients who choose a semitendinosus allograft, the length requirement remains at least 240 mm. It is our experience that most semitendinosus allografts are too thick, requiring stripping or thinning of the terminal 15 to 20 mm of each graft end in order for the allograft to fit into the patellar tunnels. The looped section, measured for a 7-mm blind femoral tunnel, rarely needs to be trimmed.Related posts:
Surgical Considerations During Patellar Stabilization
Surgical Considerations for Tibial Tubercle Osteotomy
Lateral Retinacular Release and Lengthening
Chondral Lesions and Patellar Instability
Proximal Femur Rotational Osteotomy
Failed Medial Patellofemoral Ligament Reconstruction: Causes and Treatment
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