The Triple Varus Knee: A Case Presentation

Abstract

Background:

Knee instability due to posterior cruciate ligament (PCL) and posterolateral corner (PLC) deficiency is a devastating condition that negatively affects patient quality of life. This video presents the surgical management of a triple varus knee, including combined high tibial osteotomy (HTO), revision PCL and PLC reconstruction, and meniscus root repair.

Indications:

Combined HTO and revision PCL and PLC reconstruction is indicated for patients with previously failed PCL and PLC reconstruction in the setting of varus malalignment.

Technique Description:

The procedure begins with a medial opening-wedge biplanar HTO, which is fixed with a patient-specific locking plate. The PCL femoral tunnel is drilled via a low anterolateral portal, and the tibial insertion is debrided via a posteromedial portal. The medial meniscus is carefully freed from the posterior capsule, and 2 luggage tag sutures are placed through the posterior root. The PCL tibial tunnel and meniscus root tunnels are drilled via their respective guides. The meniscal sutures are passed through the tunnel but not fixed. An Achilles bone-block allograft is passed through the PCL tibial tunnel and fixed with suspensory fixation and an interference screw on the femoral side, while the tibial side is left free. A peroneal nerve neurolysis is performed. A fibular tunnel is drilled, and a semitendinosus allograft is whip-stitched on both sides and passed through the tunnel. A Beath pin is inserted into the femur, and the tunnel is over drilled. Both limbs of the graft are passed deep to the iliotibial band and into the tunnel. The tibial side of the PCL is fixed with an interference screw at 90° of knee flexion. The PLC grafts are fixed with an interference screw at 30° of knee flexion with slight valgus. The medial meniscus root sutures are tied over a button, with 60° of knee flexion. Screws from osteotomy fixation are replaced as needed.

Results:

Although outcomes following the combined procedure are lacking, good to excellent clinical outcomes have been reported in isolation following each procedure.

Conclusion:

A combination of HTO and revision PCL and PLC reconstruction should be considered for patients with persistent instability and/or pain in the setting of triple varus knee.

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 is a case presentation of the operative management of a triple varus knee, presented by Dr Volker Musahl, as well as clinical and research orthopaedic sports medicine fellows at the University of Pittsburgh Medical Center.

The authors’ relevant disclosures are listed.

The triple varus knee is the combination of a variety of chondral and ligamentous pathologies about the knee. ⁶ While primary varus represents deficiency of the medial meniscus and cartilage with an associated change in coronal alignment of the knee, double varus incorporates opening of the lateral joint space secondary to deficient lateral soft tissue stabilizers, including the posterolateral corner (PLC). Finally, a triple varus knee encompasses the above pathology with the addition of increased external tibial rotation and recurvatum due to chronic insufficiency of the posterior cruciate ligament (PCL). Patients presenting with a triple varus knee may note symptoms of instability, pain, or gait abnormality. ⁶

Our patient is a 26-year-old man who underwent right PCL and lateral collateral ligament (LCL) reconstruction 2 years prior, at an outside facility, following an injury to the knee. He subsequently presented with chronic ipsilateral knee pain and feelings of recurrent instability. He denied a new injury or inciting event. On examination, he demonstrated symmetrical varus alignment bilaterally. On the affected limb, he had a 2+ posterior drawer, as well as 2+ opening to varus stress in full extension. Dial test demonstrated 10° of increased external rotation at 30° and 90°, compared to the contralateral side. Neurological examination demonstrated decreased sensation in the deep peroneal nerve distribution, as well as weakness with dorsiflexion of the ankle and hallux. Sensory motor examination was otherwise intact, and he had palpable pulses.

Anteroposterior (AP) and lateral radiographs of the knee, as well as standing alignment films, demonstrated a 10° posterior tibial slope, as well as 9° of varus on the affected side, versus 10° of varus on the contralateral side.

Magnetic resonance imaging (MRI) demonstrated a midsubstance tear of the PCL graft, as well as attenuation of the LCL graft. A likely radial tear of the medial meniscus at the junction of the posterior horn and root was also noted.

Given the patient's symptoms, as well as physical examination and imaging findings, he elected to proceed with surgery. The planned surgical procedure included single-stage revision PCL and PLC reconstruction with an allograft, medial opening-wedge high tibial osteotomy (HTO) with patient-specific instrumentation, peroneal neurolysis, and possible medial meniscus repair versus meniscectomy. A fibular-based PLC reconstruction was chosen per the surgeon's preference as excellent outcomes have been demonstrated with this technique in combination with PCL reconstruction.

Planning for the osteotomy is performed according to the method of Fujisawa. ⁴ In this patient with a triple varus knee without significant osteoarthritis of the medial compartment, the goal of correction is to position the weightbearing axis of the extremity through or slightly lateral to the center of the knee joint, corresponding to a valgus position of 50% to 55% of the width of the tibial plateau. ⁴

The operative setup is depicted. The patient is positioned supine with an L-bar to allow knee flexion to 90°, as well as a lateral side post, with care taken not to impair lateral exposure for the PLC reconstruction. Planned incisions for the medial opening-wedge HTO and PLC reconstruction are marked. Portals are also marked, including a high anterolateral portal, an accessory low anterolateral portal, and an anteromedial portal. A posteromedial portal will also be used to assist in PCL reconstruction and repair of the posterior root of the medial meniscus.

Preoperative examination demonstrates a grade 2 posterior drawer, 2+ opening to varus stress in full extension, and 3+ opening to varus stress in 30° of flexion.

The procedure begins with an HTO. An anteromedial tibial incision is made. The patellar tendon and medial collateral ligament (MCL) are identified and protected. The planned biplanar osteotomy is marked with guide pins, confirmed under fluoroscopy, and initiated with a sagittal saw. A step cut is made to preserve the tibial tubercle, and the osteotomy is completed with an osteotome, taking care to preserve a lateral hinge. The osteotomy is opened to a width of 10 mm and an 8-mm wedge is inserted, in accordance with preoperative planning. The osteotomy is then fixed with the patient-specific locking plate and screws.

Attention is then turned to diagnostic arthroscopy. A 5-mm area of grade 2 chondrosis is noted at the medial femoral condyle. A low accessory anterolateral portal is established through which the PCL femoral tunnel is drilled. The tibial insertion is then debrided via a posteromedial portal. At this point, a tear of the posterior root of the medial meniscus is identified and noted to be scarred to the posterior capsule. The meniscus is carefully freed from the capsule, and 2 luggage tag sutures are placed through the posterior root. Although not visualized here, a tip aimer guide is used to drill the tibial tunnel for the meniscus root repair, and the sutures are passed through the tunnel for later fixation.

The PCL tibial tunnel is then drilled with a PCL-specific guide, which may necessitate screw removal in some cases. The pin is advanced into the guide and protected during tunnel reaming. The pin is overreamed with an 11-mm reamer. The tunnel edges are then smoothed with a flexible rasp to mitigate the effect of the acute turn on graft attenuation. The rasp is then used to pass the Achilles allograft, which has been prepared on the back table with an 11-mm bone block on the femoral side. The graft is fixed with suspensory fixation on the femoral side. Due to the discrepancy in tunnel and graft diameter, an interference screw is added to enhance contact between the native bone and the allograft. The tibial side is left free for later fixation.

Attention is then turned to PLC reconstruction and peroneal neurolysis. An incision is made on the lateral aspect of the knee, anterior to the fibular head. The peroneal nerve is identified and protected with a vessel loop. In this case, extensive scarring is noted about the peroneal nerve and careful neurolysis is performed proximally and distally. A wire is then passed from anterior to posterior and a tunnel is drilled within the fibular head. A semitendinosus allograft is whip-stitched on both sides and passed through the fibular tunnel. The iliotibial (IT) band is incised, and the previous graft is identified. A Beath pin is then inserted into the femur, proximal and posterior to the lateral epicondyle, and the tunnel is over drilled. Both limbs of the graft are then passed into the tunnel.

Attention is then turned to final fixation. The tibial side of the PCL is fixed with an interference screw at 90° of knee flexion, with an anterior drawer. The PLC grafts are fixed with an interference screw at 30° of knee flexion with slight valgus. The medial meniscus root sutures are then tied over a button, with the knee flexed to 90°. Finally, previously removed screws are replaced with screws of shorter length. The incisions are irrigated and closed in a layered fashion.

Here, we highlight tips and tricks for this complex procedure. Precise preoperative planning is necessary for the osteotomy, as well as determining the appropriate order of the procedures. The use of K-wires, as well as intraoperative fluoroscopy, to outline the planned osteotomy is helpful in ensuring an appropriate trajectory and in minimizing complications. All tunnels should be drilled prior to tibial fixation, and it is important to ensure the appropriate degree of knee flexion and force applied to the knee when fixing the PLC, PCL, and meniscus root. Finally, the use of accessory portals, such as the low anterolateral and posteromedial, enables adequate visualization throughout the joint while obviating the need for a 70° arthroscope.

Pearls of this procedure include thorough preoperative planning with standing alignment films, as well as the use of a fibular-based PLC reconstruction technique, in the absence of significant recurvatum, to avoid tibial tunnel congestion. It is also beneficial to perform and fix the osteotomy prior to completing any of the ligamentous procedures and to replace the osteotomy screws with shorter screws as needed following tunnel drilling. The primary pitfall of this procedure is the lateral hinge fracture, which can be avoided by performing an osteotomy appropriately aimed for the tip of the fibular head while preserving an adequate lateral hinge of 5 to 10 mm. Gradual opening of the osteotomy with a lamina spreader can also help with force distribution to prevent fracture. If there is any concern for intraoperative fracture, postoperative computed tomography (CT) should be performed.

Potential complications of the procedure are listed. Particularly in the revision setting, the patient should be made aware of the possibility of arthrofibrosis, graft failure, and the occurrence or persistence of peroneal nerve symptoms.^2,5,7,9

Although there are few reports of outcomes following combined HTO, revision PCL and PLC reconstruction, and meniscus root repair, in isolation the procedures result in good to excellent clinical outcomes. HTO is associated with decreased pain and improved patient-reported outcome (PRO) scores, while revision PCL reconstruction yields improved stability and PROs.^1,3 Similarly, meniscus root repair results in superior PROs compared with meniscectomy. ⁸

Our postoperative protocol is highlighted. The patient is typically kept non-weightbearing for 6 weeks postoperatively. Range of motion commences at 2 weeks and is limited to passive motion until 6 weeks, at which point active knee flexion is permitted. By 3 to 6 months postoperatively, the patient should regain full range of motion and work on improving strength and proprioception. Agility and endurance progression occur around the 6-to-9-month mark.

Return to sport is permitted when the patient demonstrates full and painless range of motion with no effusion, as well as quadriceps and hamstring strength 90% of the contralateral side. Low-impact sports are permitted around 6 months postoperatively, and high-level sports at 9 months to 1 year postoperatively.

This patient is doing well almost half a year postoperatively. He has had resolution of his peroneal nerve palsy and demonstrates a stable knee on examination. He is planning to undergo contralateral medial opening-wedge HTO in the near future.

Our references are listed here.

And thank you very much for watching.