Lateral Patellofemoral Ligament Reconstruction With a Hamstring Allograft

Abstract

Background:

Medial patellar instability is rare but may occur after lateral retinacular release. The lateral patellofemoral ligament is a significant stabilizer for medial and lateral patellar displacement, and soft tissue–based reconstruction may restore its stabilizing effect.

Indications:

Lateral patellofemoral ligament reconstruction (LPFLR) is indicated for patellar instability failing exhaustive nonoperative measures.

Technique Description:

Diagnostic arthroscopy for medial patellofemoral ligament (MPFL) status, patellar tracking, chondral status, and postoperative changes of lateral retinacular release is conducted. A 5-cm incision is made between the midpoint of the patella and the lateral epicondyle, or a single midline incision can be used if performing a concomitant MPFL reconstruction. Dissection is carried down to the lateral retinaculum and capsule, and two 1-cm incisions are made at the distal and proximal patella through the patellar and quadriceps tendon, respectively. The lateral epicondyle is then directly palpated, and two 1-cm incisions are made directly anterior and posterior to the epicondyle into the iliotibial band in full extension. A hamstring allograft is then shuttled in a V-shaped configuration from the quadriceps tendon through the iliotibial band and finally to the patellar tendon. Excess graft is trimmed and doubled over proximally and distally to replicate the normal (or contralateral) 0° to 15° of patellar eversion. Trial resting length and tension is set with temporary sutures through the proximal and distal doubled graft in full extension. The knee is taken through full range of motion to ensure there is no graft tightening in flexion or loosening in full extension. Eversion and patellar translation are then examined. Heavy nonabsorbable sutures are used to set length of the doubled allograft proximally and distally.

Results:

Case series of LPFLR have demonstrated significant improvements in patients’ pain, Lysholm score and Knee Injury and Osteoarthritis Outcome Score, and kinesiophobia with no instability events and normal range of motion at short-term follow-up.

Discussion/Conclusion:

Medial patellar instability can occur following lateral retinacular release and patients experiencing instability despite nonoperative treatment are likely to benefit from a soft tissue–based LPFLR. Although other nongraft-based techniques may confer similar outcomes, the authors find it more reliable to perform a lateral reconstruction as described.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This is a technique demonstrating lateral patellofemoral ligament (LPFL) reconstruction with hamstring allograft. Our disclosures are listed here as well as available online. In general, medial patellar instability is less common than its lateral counterpart and typically happens after lateral retinacular release. Some patients have symptomatic medial instability that can benefit from surgical treatment: 1 option being an LPFL reconstruction. To understand this anatomy as it is less commonly discussed, the lateral patellofemoral complex is a series of structures that help prevent medial translation as well as lateral translation of the patella. The most significant component of these structures is the LPFL that will be our focus on this presentation.

It has an osseous femoral insertion that is distal and lateral to the lateral epicondyle and has both a patellar osseous insertion as well as a soft tissue insertion on the patellar tendon that is analogous to the medial patellofemoral complex but inversed as its soft tissue insertion is distal. Here, we can see a gross dissection during a patellofemoral arthroplasty as well as arthroscopic visualization of the LPFL as it courses as a band-like structure to the femur on the lateral side just distal and anterior to the lateral femoral condyle. These structures change in length depending on their location, and most specifically, the LPFL loosens approximately 1.5 cm when going from 0° to 90° of flexion. Most of this lengthening happens throughout its change from 0° to 90° without any significant change early in flexion. When we look at the biomechanics of the LPFL, it plays an important role in preventing both medial and lateral displacement, as it is a secondary restraint to lateral patellar instability.

Here, we can see an arthroscopic video of a normal medial patellofemoral ligament (MPFL), and when we look to the other side, we see a prior arthroscopic lateral release. In these patients, we not only lose control of directing the patella medially but also lose control directing the patella laterally. A good analogy is that if a horse was pulling too far to the right if you let go of the right rein, you would no longer be able to control the horse versus ideally you would loosen up on the right rein to get the horse to steer in a straightforward manner. Here, we can see an example of a patient who underwent an arthroscopic lateral release. We can see that there is significant lateral eversion that is possible, whereas medially, it is not as possible. We also see a sulcus form laterally because the LPFL has been released, and we no longer see that band of the retinaculum tethering the patella to the lateral femur. This also leads to increased lateral and, as mentioned, medial translation, and some patients can be fully dislocated medially after a significant lateral release as can be visualized.

Examination of the contralateral patella is crucial to understand normal translation compared with the affected side assuming the symptoms are unilateral. Most importantly, we look for tilt with lateral translation, and we see that on her affected side, she has significant patellar tilt and eversion with a sulcus deep to where the lateral release was performed prior. Here, we can see on the unaffected knee there is no significant medial translation in flexion; however, this is able to be performed on the affected side due to the latter retinacular release.

Here, on the arthroscopic examination, we see the MPFL native fibers here in normal alignment, and when we come over to the area of where the LPFL should be located, we see the prior incision for the arthroscopic lateral release, which is created a patchless lateral retinaculum that no longer provides its normal medial or lateral restraints. Lateral patellofemoral ligament reconstruction occurs through an open laterally based incision—that is at the midpoint between the patella and the lateral epicondyle. We will plan on reconstruction through the patellar tendon at its insertion and its quad tendon at its insertion at the patella looped around the iliotibial band (IT) band just over the lateral epicondyle. We incise sharply through skin and use bovie electrocautery for subcutaneous tissues and take care to not take dissection too deep quickly as this area is usually very thin. And the blue tinted tissue is usually the capsule, as there is no lateral retinaculum overlying it after the release. We make two 1-cm incisions that we will mark out ahead of time at the patellar tendon where it attaches to the patella laterally, and we are incising sharply making sure we are deep to the patellar tendon. We place an Ethibond passing stitch here for later graft passage and keep this in place as we move on to the quad tendon component. This graft spans the patella from proximal to distal as opposed to having a true osseous insertion. We incise sharply proximally with 2 additional 1-cm incisions through the quadriceps tendon. Again these are full thickness placing a passing stitch for later graft passage. After these 2 are placed, we then move down to the lateral epicondyle, which is palpated directly and is a relative isometric point for this reconstruction. We place 2 final 1-cm incisions directly over the lateral epicondyle in full extension and then place our final and third passing stitch here for later graft passage. We do not suture the graft to this location, as this allows for some dynamic movement of the graft as necessary in case there is different limb length and isometry. We then pass a preprepared semi-tendinosis graft, which could also be a gracilis graft based on the overall structural integrity. We whipstitch a single end that will be nonstructural in nature—it is only for passing and pass in a V-shaped configuration through the extensor mechanism incisions, then through the IT band, and through the final incision at the patellar tendon. After these sutures are passed, the excess graft is folded onto itself, and we tried to set the appropriate amount of patellar eversion based on what was palpated on the contralateral knee and what is normal for most patients, which is somewhere between 0° and 15°. You will see there is plenty of graft available, and we will trim the excess graft after this is complete. We set the resting tension or resting length in full extension with no significant force being placed on this using a Vicryl suture (J&J; New Brunswick, NJ), that will be a temporary suture, depending on how the overall eversion and translation feels. After these are in place, we take the knee through a full range of motion, we make sure that the graft does not tighten in flexion, and we see that it maintains its tension or length in full extension. The patient now has normal translation in their eversion which is about 10° to 15°. We see that we have spanned the native lateral retinaculum or the LPFL insertion proximal and distal to it with a soft tissue reconstruction, which is likely more forgiving than osseous-based reconstruction. After confirming that we are happy with examination under anesthesia, we use #5 or #2 Ethibond sutures (Medline; Northfield, IL) and interrupted figure-8 fashion, and we make sure that the knots are deep to the graft. Care should be taken to decrease graft prominence on the patellar and quad tendon insertion, as in young patients that are relatively thin, this can be visible cosmetically under the skin if the graft is too prominent to the soft tissue. After we place a total of at least 3 of these sutures, the excess graft is trimmed and we recheck our examination under anesthesia which demonstrates that the patient should have decreased lateral and medial translation to the point of a normal patella without overconstraint, and then, we reverify that there are normal length changes with flexion. Ideally, we shoot for 1A lateral translation and 2B of medial translation with 15° or less of patellar eversion.

After surgery, the patients can weight bear in full extension in a brace. We unlock the brace after they have good quad control and could do a straight leg raise without a lag. We work on range of motion as fast as tolerated with a minimum of 15° of flexion per week, but they are allowed to advance faster than this if possible.

After 6 weeks, the patient can discontinue the brace assuming they have appropriate quadriceps strength work on obtaining full range of motion if not done already and starting cardiac training including elliptical and bike work until 12 weeks after surgery after 3 months, the patient should work on running in linear activities with no restrictions with regard to strengthening but still hold off on lateral based cutting movements; after 4-month work on progressing to full activity, assuming they have been able to sprint and not have any issues, the patient may fully return to sport as able by 6 months at the latest.

Complications after this procedure are uncommon but could include infection, blood loss, and wound dehiscence. Outcomes after this procedure have been reported by at least 2 groups and demonstrated improvement of clinical outcome scores, as well as decreased catastrophizing sensations, as well as decreased risk for redislocation or sensations of subluxation. No patients in these series had recurrent instability, and all had normal range of motion. Thank you.