Revision Transtibial Medial Meniscal Root Repair With Concomitant Medial Opening-Wedge Proximal Tibial Osteotomy

Abstract

Background:

Complete meniscal root tears disrupt dispersion of axial loading forces through hoop stresses. This increases point-loading on tibiofemoral cartilage and leads to chondromalacia and accelerated osteoarthritis (OA). Posterior root tears may be treated successfully with a transtibial pullout repair. Varus malalignment also leads to increased medial compartment pressures, increasing the risk of early OA and putting increased stress on the meniscus and stabilizing knee ligaments. In particular, revision medial meniscal root repairs without correction of varus malalignment are at increased risk of failure. Genu varum may be corrected with a medial opening-wedge proximal tibial osteotomy (OW PTO).

Indications:

Meniscal root repairs are indicated for acute or chronic tears in active patients with healthy cartilage. OW PTO is indicated for varus malalignment in ambulatory patients with healthy cartilage, or who are at risk for failure of meniscal or ligamentous procedures.

Technique Description:

After exposure of the osteotomy site, arthroscopy is performed through the incision and the revision posterior meniscus root repair is performed via a double-tunnel transtibial pullout technique. The positioning of these tunnels is modified superiorly so as to not cross the planned osteotomy site. The osteotomy is then performed by drilling 2 guide pins under fluoroscopy to delineate the plane of the cut. An OW plate is placed, and the root repair is tensioned last.

Results:

Double-tunnel transtibial pullout repairs increase meniscal fixation contact surface and have been shown to be biomechanically superior to all-inside fixation techniques. Medial OW PTO restores knee alignment and reduces supra-anatomic stresses in the medial compartment, additionally decreasing the risk of a revision medial meniscus repair failure.

Discussion:

Biomechanical studies have shown that meniscal root tears are functionally equivalent to complete meniscectomy. Varus malalignment increases the risk of medial meniscal tears, and reduces the risk of a successful long-term repair. We describe a technique for a revision transosseous posterior root repair with concomitant proximal tibial osteotomy, with discussion of surgical pearls and pitfalls. This technique restores anatomic position and native function of the medial meniscus while correcting tibiofemoral malalignment that could jeopardize the repair.

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.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

This is a video presentation depicting a revision transtibial pullout repair of the medial meniscus posterior root with a concomitant medial opening-wedge proximal tibial osteotomy (OW PTO).

Shown here are the authors’ disclosures.

Biomechanical and clinical studies have shown that meniscal root tears, left untreated, are functionally equivalent to complete meniscectomy in terms of progression to osteoarthritis (OA). ⁵ Due to disruption of meniscal circumferential integrity, axial loading forces from the femoral condyles are not adequately dispersed into hoop stresses as depicted by the black and yellow arrows (Video 1). ³ This leads to reduced contact areas and increased point-loading which may rapidly develop into chondromalacia and early accelerated OA.^1,5 Transtibial pullout repair is a common fixation technique for posterior meniscal root tears, and has been shown to restore contact area and decrease contact pressures and point-loading to near native conditions while improving posterior meniscal extrusion and patient-reported outcomes.^4,6 Varus alignment of the knee is a common condition which increases medial compartment contact pressures and stresses on the meniscus and stabilizing ligaments, ultimately predisposing to the progression of medial compartment OA.^2,7 Medial OW PTO may be used to effectively restore coronal alignment, and to reduce the symptoms and decrease the progression of OA. ²

A 37-year-old otherwise healthy female presented to our office for a second opinion after a failed transtibial medial meniscal root repair with a concurrent peripheral stabilization with a suture anchor a little over 1 year after the procedure. The original injury was suspected to occur during box jumps.

Examination of the patient's left knee revealed mildly increased Lachman and anterior drawer tests compared to the contralateral side but was otherwise largely unremarkable other than noted hyperlaxity with a Beighton score of 9. The history and physical exam were consistent with a retear of the patient's medial meniscal root.

Plain film radiographs revealed a marked varus alignment on long-leg views obtained in office, and were also suggestive of a subchondral cyst in the presumed location of the anchor from previous root fixation. Her joint space remained largely intact bilaterally. Measurements depicted here show the determination for a 5-mm OW osteotomy plate.

Magnetic resonance imaging (MRI) revealed signal hyperintensities at the left medial meniscal posterior root on T2 axial and sagittal views suggestive of disruption of the meniscal root. A radial tear in the medial meniscal body was also noted on axial MRI which corresponded with the location of the peripheral stabilization stitch.

The final diagnosis was failure of the medial meniscal root repair with varus alignment of the knee and a concurrent radial midbody medial meniscus tear. The MRI did not show any major medial compartment cartilage defects. The patient's conditions were discussed in detail, and the risks and benefits of surgical treatment were provided. The patient elected to undergo surgery, and revision medial meniscal root repair via double-tunnel transtibial pullout repair with a concomitant inside-out radial repair was planned. In light of the patient's re-injury, hypermobility, and varus alignment, medial OW PTO was planned to off-load the medial compartment.

An examination under anesthesia was consistent with the previous clinical exam, including +1 Lachman and pivot-shift exams.

The approach to the osteotomy site was performed first, with a vertical anterior incision extending from the inferior patella distally. Subperiosteal dissection was carried out posteriorly under the medial collateral ligament, and continuing posterior along the posterior cortex of the tibia. Anteriorly the dissection was carried under the deep infrapatellar bursa and patellar tendon. The osteotomy site was planned and marked with a bovie to use as a guide for placement of the transtibial tunnels.

Arthroscopy proceeded with the use of standard medial and lateral portals created through the incision. Diagnostic arthroscopy revealed intact lateral compartment and cartilage, as well as the anterior cruciate ligament and posterior cruciate ligament. The medial compartment demonstrated grade 1 or 2 chondromalacia forming on the posterior aspect of her medial femoral condyle, and a cystic blistering area on the medial tibial cartilage where the suture anchor had been placed. There was also a 70% radial tear in the midbody of the medial meniscus, and the posterior root repair had failed with the root displaced nearly 1 cm from the bony attachment site.

The root attachment site is then decorticated using a curette and curved shaver until there is a bleeding bony bed for increased bony ingrowth. The previous sutures were removed using the curved shaver during this step.

The meniscus was extruded, and a scissor biter was required to perform an extensive release of the meniscocapsular and meniscotibial junctions in order to appropriately reduce the meniscal root.

A root repair guide is placed to aim the guide pins for the tibial tunnels from the anteromedial tibia to the decorticated bony bed. The tunnels were aimed at 35° due to the necessity of staying above the osteotomy site. A beath pin is drilled for the posterior tunnel first, then removed while leaving the cannula for suture passage. The second anterior pin is aimed using a parallel guide at a distance of 5 mm apart, and the cannula is again left in the tunnel.

Using a left-curved suture passing device, a suture tape is passed through the meniscal root in a vertical mattress configuration. The posterior suture is placed first. A wire loop is passed through the posterior cannula, and the suture tape is shuttled through. Another vertical mattress is placed with suture tape more anteriorly and shuttled down the anterior tunnel. Working posterior to anterior helps avoid potential suture entanglement. The suture tapes are pulled tight, and the root is reduced to an anatomic position.

Attention is now turned to the inside-out radial repair, and the external incision site is located by using a probe to palpate from the inside. Dissection commenced down the medial joint capsule. Using a self-passing suture device, 2 suture needles are used on each meniscal flap to create vertical mattress “rip-stop” sutures parallel to the tear site. These are tied to each other over the medial capsule such that they help bring the tear edges together. Two bridging horizontal mattress sutures are placed around the vertical mattress sutures in a hashtag configuration. Tension is applied to the meniscal root prior to tying the radial repair, to ensure a good reduction will be present at both tear sites.

The leg holder is then removed by a non-sterile assistant and the foot of the bed raised so the leg rests in extension.

Fluoroscopy is brought in and 2 guide pins are drilled to delineate the plane of osteotomy. The pins are positioned to aim the cut toward the fibular head. The first cut is made with an oscillating saw to a depth of 5 mm to break the anteromedial cortex. A small osteotome is then introduced to create a controlled osteotomy cut along the anterior cortex. A medium osteotome is then introduced to further the cut centrally. Then finally the posterior cortex is addressed with a small osteotome again, with a finger and retractor placed posteriorly to guide the osteotome and ensure there is not excessive protrusion of the osteotome posteriorly. Finally, an opening spreader device is introduced to complete the osteotomy, after which it is opened slowly to a width of 5 mm and then left for 5 minutes to allow stress relaxation of the 1-cm lateral cortical hinge. An opening tine device replaces the spreader, and a 5-mm OW osteotomy plate is placed, ensuring it is posterior to the tunnels for the root repair so the screws do not cut the transtibial suture tapes or interfere with the placement of a cortical button when tying the root repair. Further slightly posterior placement of the plate helps to avoid inducing iatrogenic changes to posterior tibial slope.

The posterior distal 4.5-mm cortical screw is placed first after drilling and measuring the depth. These are followed by a 6.5-mm fully threaded cancellous screw proximally. The 2 remaining fixation screws are then placed. No bone grafting was required. Fluoroscopy is used to ensure the hardware is in good position.

A cortical button is then used to tie down the meniscal root repair, which is done under direct visualization to ensure proper tensioning. The deep and superficial layers are closed with suture.

The patient will be non-weightbearing to the left lower extremity for 8 weeks, and range of motion will be restricted to 90° passive flexion for the first 2 weeks after which they may advance as tolerated. At 8 weeks radiographs will be obtained to verify sufficient healing, at which time the patient may advance weightbearing by 25% body weight per week until full weightbearing by 3 months. If further radiographs are still positive, the patient may be weaned off crutches at that time.

Given the complexity of this case there are a number of things to consider. One potential complication to avoid is convergence of the tibial tunnels with the osteotomy site. This may be avoided by preoperative planning, and understanding the placement for the plane of osteotomy by marking the osteotomy site prior to placing the tibial tunnels. Inadequate varus correction may be avoided by adequate preoperative planning. Long-leg mechanical axis films need to be obtained and mechanical axis deviation needs to be measured, followed by measurements of appropriate correction necessary to correct the mechanical axis such that it passes through the lateral tibial spine. Inadequate reduction of the meniscal root repair may be avoided by a strong knowledge of anatomic landmarks and the precise location of the meniscal root attachment, as well as by checking reduction with graspers prior to the repair and performing a meniscocapsular and/or meniscotibial release as necessary to mobilize the extruded meniscal root into the appropriate anatomic location.

A systematic review and meta-analysis by Perry et al with 876 patients found that patient-reported outcomes improved after posterior meniscal root repair, and that concomitant PTO resulted in an even greater preoperative to postoperative improvement in reported outcomes.

A recent biomechanical cadaveric study by Park et al also found that transtibial pullout repair with concomitant osteotomy was able to significantly restore contact area and reduce contact pressures, with no change when compared to various angles of OW osteotomy.

Postoperative day 1 images show improved coronal alignment with cortical button and osteotomy plate and screws in good position.