Anatomic Reconstruction of the Posterolateral Bundle of the Anterior Cruciate Ligament and Posterolateral Corner with Lateral Capsule,Biceps Femoris Tendon,and Lateral Meniscal Repairs

Abstract

Background:

Multiligament injuries can severely impair knee stability and function, leading to long-term complications if not managed. Injuries involving the posterolateral corner (PLC), especially when combined with anterior cruciate ligament (ACL) tears, require prompt anatomic reconstruction to restore normal knee function.

Indications:

Unrecognized or inadequately treated PLC injuries can lead to persistent varus and rotational instability, increasing stress on cruciate ligament grafts and compromising reconstruction outcomes. Thus, timely surgical reconstruction of all 3 primary PLC stabilizers (the fibular collateral ligament [FCL], popliteus tendon, and popliteofibular ligament [PFL]) is critical to restoring native biomechanics and maintaining long-term knee function.

Technique Description:

This technique describes an anatomic reconstruction of the posterolateral (PL) bundle of the ACL, along with repairs of the lateral capsule, biceps femoris tendon, and lateral meniscus, in a patient presenting with complete foot drop. After careful neurolysis of the surrounding common peroneal nerve scar tissue, anatomic tunnels were drilled for reconstruction of the PLC—including the FCL, popliteus tendon, and PFL. Sutures were placed in the lateral capsule for a repair later in the case. Next, arthroscopy was performed to evaluate the ACL bundles, during which a PL bundle tear was identified. A semitendinosus tendon autograft was then harvested. The ACL PL bundle femoral tunnel was drilled, followed by an inside-out repair of the lateral meniscus. The ACL PL bundle tibial tunnel was then created. Grafts were passed and fixed sequentially, with the PLC grafts secured first, followed by fixation of the ACL graft in full extension. The procedure concluded with open repairs of the avulsed biceps femoris tendon and lateral capsule.

Results:

Geeslin et al reported that acute PLC injuries treated surgically within 3 weeks had more favorable outcomes with reconstruction or hybrid techniques, while primary repair followed by staged cruciate reconstruction was associated with higher failure rates.

Discussion/Conclusion:

Timely anatomic reconstruction of the main PLC static stabilizers with a concurrent repair of the tendon and capsular structures effectively and reliably restores native knee stability in acute settings. Compared with delayed or staged procedures, early reconstruction often leads to improved outcomes and reduces the risk of graft failure.

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.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This video presentation depicts an anatomic reconstruction of the posterolateral (PL) bundle of the anterior cruciate ligament (ACL) and the posterolateral corner (PLC), including repairs of the lateral capsule, biceps femoris tendon, and lateral meniscus repairs.

Background

As an overview, an anatomic PLC reconstruction using an Achilles tendon allograft, ACL (PL bundle) reconstruction using a semitendinosus autograft, biceps femoris tendon, and lateral capsule repairs, and an inside-out lateral meniscal meniscocapsular repair was performed.

Multiligament knee injuries disrupt native biomechanics and cause significant instability, often requiring complex surgical intervention to prevent joint degeneration and long-term functional impairment.^2,8 PLC injuries frequently occur alongside ACL or posterior cruciate ligament (PCL) tears and call for timely anatomic reconstruction to restore varus and rotational stability.^2,5

Current biomechanical and clinical studies support reconstructing all 3 primary PLC stabilizers (the fibular collateral ligament [FCL], popliteus tendon, and popliteofibular ligament [PFL]) as part of a comprehensive anatomic approach. ⁶ If unrecognized or untreated, PLC injuries can place excessive stress on cruciate ligament grafts and may contribute to graft failure.^4-6 Anatomic reconstruction techniques have been reported to restore native knee stability and produce excellent functional outcomes.^2,4-6,8

Indications

We present the case of a 15-year-old healthy male high school sophomore who injured his right knee while running in the dark and stepping into a hole. He reported an acute onset of right knee pain and swelling with right foot numbness and an inability to dorsiflex his right foot. He was subsequently seen at a local hospital, where a computed tomography angiography was performed to rule out a vascular injury. He was then placed in a knee immobilizer and presented to the clinic 5 days later.

On physical examination, the patient's right knee demonstrated a grade 2+ Lachman, grade 3 varus stress at 0° and 30°, a positive dial test at 90°, and a negative posterior drawer, indicating an ACL tear and complete PLC injury. His knee range of motion (ROM) demonstrated 1 cm of heel height to 100° of flexion (compared to 10 cm of heel height to 140° on the left). His right knee was stiff, and he was apprehensive of hyperextension. He had 0/5 motor strength to his extensor hallucis longus and tibialis anterior with concomitant first webspace and medial two-thirds numbness of the dorsal foot.

Radiographs of the right knee demonstrated a posterior tibial slope of 13.5° and a neutral mechanical axis. Varus stress radiographs revealed 3 mm of increased lateral gapping on the right knee. Magnetic resonance imaging (MRI) of the right knee demonstrated a complete PLC injury, partial-thickness ACL and PCL tears, a Segond fracture of the anterolateral capsule, a biceps femoris tendon avulsion off the fibular head, and a potential lateral meniscal tear at the posterior horn. In this case, the physes appear to be closing on radiographs. Therefore, graft reconstruction tunnel drilling would not be altered to avoid the physes. When open physes are present, care must be taken to avoid physeal injury, and the surgical technique may need to be modified based on skeletal maturity.

An examination under general anesthesia of the right knee demonstrated 15 cm of heel height to 140° of knee flexion compared with 10 cm and 140° of knee flexion on the left knee, a stable posterior drawer, and a 2A Lachman with a good endpoint, a 1 to 2+ pivot shift, and marked posterolateral instability with 3+ varus gapping.

Technique Description

The PLC was approached first to visualize landmarks before fluid extravasation. A standard lateral hockey stick incision was made with subsequent dissection down to the superficial layer of the iliotibial band (ITB) and over the anterior compartment of the leg. Next, a meticulous dissection was performed with an Adson point hemostat to identify the biceps femoris tendon avulsion. The biceps femoris tendon was completely detached from the fibular head. The fibular head was then cleaned off with a sponge to evaluate the location of the common peroneal nerve (CPN). MRI was used before the case to help calculate the CPN course. The CPN was scarred, swollen, and slightly thickened approximately 2 cm proximal to the fibular head, and it was otherwise intact. An 8-cm long common peroneal nerve neurolysis was then performed with an Adson point hemostat. The neurolysis occurred around the fibular head and anteriorly as the CPN was adhered to the lateral capsule and the biceps femoris retracted tendon. The CPN was then mobilized, and 5 to 7 mm of the peroneus longus fascia was incised to minimize the risk of further scar tissue entrapment over time. The native fibular head insertion site of the FCL was localized approximately 8 mm posterior to the anterior margin and 28 mm distal to the apex of the fibular styloid, and a guide pin was placed from lateral to posteromedial across the fibular head using a fibular head guide. This was then overreamed with a 7 mm reamer, and a passing stitch was placed. Next, a dissection was performed at the tibial flat spot located distal and medial to the Gerdy tubercle. Then, the popliteus musculotendinous junction posteriorly was identified. A guide pin was drilled anterior to posterior at the flat spot and exited at the popliteus musculotendinous junction on the tibia, located 1 cm medial and proximal to the fibular head tunnel. The tunnel was overreamed with a 9-mm reamer while a large Chandler retractor was used to protect the posterior neurovascular structures. A passing stitch was then placed.

Next, the ITB was split to identify the FCL and popliteus femoral attachments. Dissection was carried down to the lateral capsule, and a vertical lateral capsular incision was made so a Z-retractor could be placed anteriorly to identify the popliteus tendon. A guide pin was then drilled at the center of the popliteus attachment located at the anterior fifth of the popliteus sulcus. It was angled 40° anterior and slightly proximal to prevent convergence with the ACL graft. ⁷

The FCL femoral attachment site was then identified by measuring 18.5 mm posterior and proximal to the popliteus tendon attachment site and verifying with the lateral epicondyle location. ² A parallel guide pin was drilled at the FCL attachment site. Then, both pins were overreamed with a 9 mm reamer to a depth of 25 mm.

Subsequent dissection was directed toward the inferior aspect of the patient's ITB to separate the lateral capsule, which was completely detached from the tibia. A Z-retractor was placed under the patient's lateral meniscus to retract it and identify the lateral capsular attachment. Two Q-Fix anchors (Smith & Nephew) were placed at the lateral capsule tibial attachment, with care taken to avoid the tibial PLC tunnel. The sutures were then passed through the dissected lateral capsule.

Next, the avulsed biceps femoris tendon was identified, and both proximal and distal releases were performed. A tag stitch was placed, and dissection was continued until the tendon could be reduced to the fibular head in full knee extension to ensure proper anatomic tensioning. ¹⁰

Following this, a standard diagnostic arthroscopy was performed via anterolateral and anteromedial (AM) portals. The PCL was functional, although mild intrasubstance tearing was noted. The ACL had a complete PL bundle tear and minimal hemorrhage of the AM bundle, confirming that only a semitendinosus autograft would be harvested for a PL bundle reconstruction. The medial meniscus was normal. The lateral meniscus had a very large posterior meniscocapsular separation, which would require a repair.

Following this, a small incision was made over the pes tendons, and dissection was performed to identify the hamstrings tendons. The semitendinosus tendon was then harvested with an open hamstring harvester.

The Achilles tendon allograft was split into FCL and popliteus tendon grafts, with two 9-mm bone plugs and distal tubularized grafts. A semitendinosus tendon autograft was used for the ACL PL bundle, and it was sized to fit through a 6-mm diameter tunnel.

Next, an accessory medial portal was made, and an over-the-top guide was placed directly against the femoral anatomic attachment site of the PL bundle, where a guide pin was drilled. The attachment site was overreamed with an EndoButton (Smith & Nephew) reamer. It was determined that a 10-mm long EndoButton (Smith & Nephew) would be needed for fixation. The PL bundle attachment was then reamed with a 6 mm low-profile reamer to a depth of approximately 30 mm, leaving approximately 2 to 3 mm of the posterior wall cortex. A passing stitch was then placed.

Further dissection was performed proximal to the biceps femoris tendon, and blunt dissection was carried out anterior to the lateral gastrocnemius tendon and posterior to the posterolateral capsule. A retractor was then placed in the interval to protect the neurovascular bundle. An inside-out lateral meniscocapsular repair was performed with 6 vertical mattress sutures for a posterior horn repair. ¹

Next, a guide pin was drilled through the tibial attachment site for the PL bundle of the ACL, located just medial to the anterior horn of the lateral meniscus, with the use of an ACL guide. ¹⁰ This was followed by reaming with a 6-mm reamer, and a passing suture was then placed. The ACL graft was then passed from the tibial tunnel into the femoral tunnel utilizing the passing sutures. Next, the bone plugs for the popliteus tendon and the fibular collateral ligament were then passed into their femoral tunnels and fixated with 7 × 20 mm titanium screws. The popliteus tendon graft was passed down the popliteal hiatus, and the FCL graft was passed under the remaining ITB and superficial to the popliteus tendon graft. This was then passed through the fibular head tunnel from anterolateral to posteromedial.

Next, the lateral capsule was repaired using the previously passed Q-Fix anchors (Smith & Nephew) with the knee flexed to 20°, which was felt to reduce the varus gapping by 50%. The FCL graft was then fixed in the fibular head tunnel with a 7 × 20 mm bioabsorbable screw, with 20° of knee flexion before the ACL, based on the tensioning sequence for combined PLC and ACL reconstructions described by Wentorf et al. ¹¹ The remaining section of the FCL graft, which converts into the PFL graft, and the popliteus tendon grafts were then passed posterior to anterior through the tibial tunnel and fixed in the tibial tunnel with a 9 × 20 mm bioabsorbable screw with the knee flexed to 60° and the foot in neutral rotation.

Another Q-Fix anchor (Smith & Nephew) was placed in the posterolateral aspect of the fibular styloid, and the biceps femoris tendon was repaired to the fibular head with the knee in full extension. The ACL graft was then fixed to the tibia using 2 small Richards staples (Smith & Nephew) with the knee in full extension. The patient's Lachman test, varus stress testing, and posterolateral drawer testing were then all noted to be stable.

The tourniquet was then let down. Deep and superficial closure was accompanied by application of a sterile dressing and a knee immobilizer in full extension.

Postoperatively, the patient will be nonweightbearing on his right lower extremity for 6 weeks. Knee flexion will be limited to 90° for the first 2 weeks, after which ROM may be advanced as tolerated. Additionally, because this is a hyperextension injury, hyperextension should be avoided for the first 6 weeks. Because of complete foot drop before surgery, the patient was placed in an ankle-foot orthosis to support the ankle.

Results and Discussion

Recovery following CPN injury is variable, and observation for 6 to 12 months is often appropriate to assess return of function. If no meaningful recovery is observed, surgical options such as tendon transfer or nerve grafting may be considered.

A systematic review by Geeslin et al ³ examined outcomes of acute PLC knee injuries treated surgically within 3 weeks of injury, reporting that failure rates varied depending on the surgical approach, as patients who underwent primary repair with staged cruciate reconstruction experienced higher failure rates, whereas those treated with PLC reconstruction or hybrid techniques had more favorable outcomes. These findings support the use of reconstruction as a more reliable option compared with delayed cruciate reconstruction after a primary repair. In conjunction, another systematic review was conducted to evaluate the outcomes of chronic grade 3 PLC injuries. ⁹ Moulton et al ⁹ reported that surgical reconstruction of chronic PLC injuries led to a 90% success rate based on physical examinations and stress radiographs; however, they determined that further research is needed to determine the optimal technique for chronic grade 3 PLC injuries.

Conclusion

Postoperative day 1 radiographs were normal with good tunnel and screw placement. The cortical button position on the immediate postoperative radiographs appears offset due to the radiographic trajectory and the thickness of the patient's periosteum. The button was confirmed intraoperatively and on subsequent imaging to be fully seated in cortical bone. At the patient's 15-month postoperative visit, varus stress radiographs demonstrated 0.9 mm increased varus gapping on the right compared to the left, consistent with a well-healing PLC reconstruction. The right (surgical knee) was 2.0 mm tighter for anterior tibial translation compared with the left (contralateral) knee on ACL stress radiographs, indicating a well-healed PLB ACL reconstruction. Strength testing demonstrated a 99% quadriceps limb symmetry index, and he had regained full function of his CPN.

Complications to be considered include the risk of a CPN injury. A careful dissection during the neurolysis is essential to ensure adequate nerve protection and minimize the risk of further nerve injury due to postoperative swelling. Second, the sequence of graft fixation and the forces applied during fixation are critical to preserving proper tibiofemoral alignment. Lastly, to reduce the risk of postoperative fibrosis, early emphasis should be placed on restoring ROM and minimizing swelling.