Abstract
Background:
Medial patellofemoral ligament reconstruction (MPFLR) is a common surgical procedure for the treatment of recurrent patellar instability. Techniques vary by graft type, fixation method, number of graft limbs, graft placement, and tensioning. Hamstring tendons are most commonly used, but autograft causes donor-site morbidity, while allograft increases cost and requires availability. Recent anatomic studies have described a medial patellofemoral complex (MPFC) with a broad attachment to both the superomedial patella and the distal medial quadriceps tendon, suggesting the need to restore a broad footprint across both sites.
Indications:
MPFLR may be performed in isolation or in combination with bony procedures that address structural malalignment. Recent evidence suggests a role for isolated MPFLR regardless of coronal alignment and patellar height, in the absence of severe dysplasia or jumping J sign. We present a modification of the MPFLR technique described by Fink et al, utilizing quadriceps tendon autograft to restore a broad footprint of the MPFC.
Technique Description:
A 6 to 7 mm–diameter partial-thickness strip of tendon is harvested from the medial quadriceps tendon, leaving a thin cuff of tendon intact medially for side-to-side repair. The graft is left intact at the patellar insertion and redirected 90°, beneath the intact medial tendon insertion. The graft base is attached to exposed bone on the medial aspect of the superomedial corner of the patella using an all-suture anchor. The free end is passed between layers 2 and 3 and fixed within a socket at the Schottle point on the medial femoral condyle using a resorbable interference screw.
Results:
The described technique utilizes the quadriceps tendon autograft for MPFLR. The graft is easily obtained through a slight proximal extension of the incision required for patellar graft fixation. Harvest is reliable and reproducible, with extremely low donor site morbidity.
Discussion/Conclusion:
Maintenance of graft origin at the proximal patella with secondary fixation at the superomedial patella combines the traditional construct for MPFLR (bone fixation at superomedial patella) with that described by Tanaka as medial quadriceps tendon femoral ligament reconstruction (attachment at medial quadriceps tendon insertion). Thus, the technique described here restores a larger footprint of the entire MPFC, more closely approximating normal anatomy.
Patient Consent Disclosure Statement:
The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.
This is a visual representation of the abstract.
Keywords
Video Transcript
We present a technique for medial patellofemoral ligament (MPFL) reconstruction utilizing an autograft quadriceps tendon.
Background
The medial patellofemoral ligament (MPFL) originates on the femur between the adductor tubercle and medial epicondyle, as identified by the red circles, and inserts upon the superomedial patella and the distal medial quadriceps tendon.
It is an important stabilizer of the patella and provides 60% of lateral translation restraint. Of all the dynamic and static stabilizers, the MPFL is the strongest medial restraint.6,9
Recent anatomic studies have described the medial patellofemoral complex, redefining the MPFL as a variable structure with a broad insertion on the medial aspect of the distal quadriceps tendon, in addition to the superomedial border of the patella. 11
Based on these studies, an alternative insertion point for the MPFL has been proposed at the distal medial quadriceps tendon.8,11 However, this technique completely bypasses the patellar origin. We will present an alternative technique that attempts to duplicate both the patellar and quadriceps tendon origins.
The senior author (T.A.S.) has used the technique presented in this video for the past 5 years with excellent anecdotal results—it provides a combined origin at the distal quadriceps tendon and the superomedial patella, recreating the broad footprint described as the medial patellofemoral complex.
Treatment of recurrent patellar instability is aimed at correcting underlying pathoanatomy2,4 and essentially falls into 3 categories: isolated MPFL reconstruction, bony procedures, or a combined approach. MPFL repair is also another option, but this will not be covered in this technique video.
Pathoanatomic factors that affect surgical decision-making include trochlear dysplasia as defined by the DeJour classification. 1
Patella alta as defined by the Caton-Deschamps Index (CDI).
Coronal malalignment, such as elevated tibial tubercle-trochlear groove (TT-TG) distance, as well as increased quadriceps angle of the femur.
Jumping J-sign as shown in the video on the right.
Hyperlaxity, which can be quantified by the Beighton criteria.
The patient's activity or sport level.
The patient's age.
Or evidence of chondral injury.
There are several benefits of an isolated MPFL reconstruction—including restoring appropriate anatomy to prevent lateral translation with a smaller surgical insult. Studies have shown that isolated MPFL reconstruction can effectively restore stability in patients with low TT-TG distances and minimal patella alta.3,10
More recent evidence suggests that isolated MPFL reconstruction is successful for the treatment of recurrent patellar instability, regardless of TT-TG distance or patellar alta. Erickson et al, 7 found good results in 90 patients who underwent isolated MPFL reconstruction irrespective of bony pathology. Importantly, patients with a jumping J sign were excluded.
A 5-year follow-up study of the patient population originally examined by Erickson et al, conducted by Dennis et al, 5 demonstrated maintenance of clinical outcomes, with 6 patients reporting recurrent instability at a mean of 3 years postoperatively.
Indications
Our patient is an 18-year-old male adolescent who presents with 1 year of left patellar instability after a dislocation event while wrestling.
His physical examination is notable for no evidence of hyperlaxity and a 2-quadrant lateral glide at 15° to 20° of flexion. He has no evidence of apprehension or J-sign on examination.
On imaging, his CDI is 0.62.
Axial magnetic resonance imaging shows lateral patellar tilt and subluxation with a bone bruise over the lateral femoral condyle consistent with previous lateral patellar dislocation.
The lateral trochlear inclination angle is nearly 3°, indicative of trochlear dysplasia.
Finally, the patient's TT-TG distance is roughly 20 mm. Thus, given our patient's history of recurrent patellar instability, low CDI, and borderline TT-TG distance, he was indicated for a left knee diagnostic arthroscopy with isolated MPFL reconstruction utilizing a quadriceps tendon autograft.
Technique Description
The patient is positioned supine with a tourniquet.
Examination under anesthesia shows a 2 to 3-quadrant lateral glide.
A diagnostic knee arthroscopy is performed to assess the patellofemoral joint for chondral injury and intra-articular loose bodies.
An incision is made slightly medial to the superior pole of the patella to allow access to the quadriceps tendon for graft harvest as well as the medial face of the patella.
The Schottle point is estimated by palpating the medial epicondyle and adductor tubercle with an incision at the midpoint between these 2 anatomic structures.
An injection of 0.25% bupivacaine with epinephrine is injected at the incision sites. The senior author prefers to avoid preoperative nerve blocks due to postoperative quadriceps deactivation and the possible delay in strength recovery.
The incision is made sharply with a No. 10 blade.
After incision, superficial dissection is performed, and the paratenon is incised, exposing the quadriceps tendon in preparation for harvest. Ensure exposure of the superior pole of the patella to maximize the length of the harvested graft.
Ideally, a graft 80 mm in length is preferred for harvest.
A precut ruler is used to measure from the superior pole of the patella to the proximal margin of the quadriceps tendon, ensuring a graft length of 80 mm.
A No. 10 blade is used to harvest the medial portion of the graft, leaving a small cuff of tissue on the vastus medialis oblique for later repair.
The cut is remeasured to ensure the length is adequate.
The lateral edge of the autograft is then harvested with a No. 10 blade. We generally harvest a partial-thickness graft 6 to 7 mm in width and depth. This is done by angling both knife cuts toward each other to cut in a triangular shape. The leg is flexed to place the quadriceps tendon under tension and assist with graft harvest.
The graft is truncated proximally.
The soft tissue attachments of the graft on the underside of the patella, as well as medially and laterally, are freed to maximize the length of the harvested graft.
The graft is measured to be 80 mm in length, and the distal attachment to the patella is maintained.
The proximal end of the graft is whipstitched with a locking nonabsorbable suture to conserve length and tubularize the graft for easy passage into the femoral tunnel.
A graft sizer is used to approximate the size of the graft and to determine the size of the femoral tunnel that should be reamed. The graft in this case is measured to be 7 mm.
The quadriceps tendon defect is closed with an interrupted 0-Vicryl suture with buried knots to prevent postoperative irritation.
The superomedial border of the patella is cleared of residual soft tissue with electrocautery.
A 2.3-mm all-suture anchor is placed at the superomedial face of the patella, aiming the drill between the patellar cortices and in an inferior direction to avoid violation of the articular surface.
The anchor is set, and the limbs of the suture anchor are placed through the proximal base of the graft in a horizontal mattress fashion.
The 2 ends of the suture are then tied, securing the graft to the anchor. This establishes the graft at the MPFL patellar origin.
After the incision is made, the medial epicondyle and adductor tubercle are palpated. A space between these 2 structures is chosen to roughly approximate the area of the Schottle point.
The leg is brought into a figure-4 position, and a Beath pin is drilled bicortically, aiming proximal and avoiding excessive anteroposterior position. The Schottle point is approximated by palpation.
A hemostat is passed between layers 2 and 3 of the knee in preparation for graft passage.
The proximal end of the graft is then passed through these layers of the knee.
The graft is wrapped once around the Beath pin and held with gentle tension to assess lateral glide and isometry through a range of motion. Lateral glide testing in 20° of flexion shows less than a 1-quadrant lateral glide.
Isometric testing is then performed. In full extension, the graft will often loosen slightly but should remain isometric in flexion.
The femoral tunnel is reamed to 7 mm based on our original graft measurement during harvest. Because of the graft's length, a tunnel 30 to 35 mm in diameter is reamed to ensure full seating of the graft.
The graft is then guided into the femoral tunnel.
A hemostat is used to hold tension on the graft while patella tension and isometry are tested before final fixation.
A guidewire for the interference screw is placed posteriorly in the graft socket to avoid injury to the graft, and the knee is positioned between 45° and 60° of flexion for screw insertion.
A biocomposite interference screw is inserted, ensuring the screw is not too proud to avoid irritation of the overlying soft tissue.
The guidewire is left within the tunnel, and final patellar tension and isometry are tested. If the graft is found to be too short to use an interference screw, the authors prefer to utilize suspensory fixation on the lateral cortex of the femur as an alternative.
The medial retinacular tissue is repaired using the suture from the previously placed suture anchor in a pants-over-vest fashion.
The subcutaneous layer is closed with 2-0 Monocryl.
This is followed by a 3-0 running, subcuticular Monocryl suture for final closure.
Results
The return-to-sport (RTS) protocol is shown here. Patients may RTS once their quadriceps strength deficit is <10% on Biodex strength testing and dynamic muscle control is restored on several functional tests. Important aspects of each phase of recovery are highlighted. The full rehabilitation protocol is publicly available for patients to use; a link is available in the bottom left-hand corner.
Discussion/Conclusion
The described technique uses a readily available and reproducibly harvested quadriceps tendon autograft to reconstruct the medial patellofemoral complex. Preservation of the patellar insertion site with secondary attachment at the superomedial patellar border restores the broad footprint of this complex—more closely approximating normal anatomy.
Footnotes
The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.
