Arthroscopic Repair of Medial Meniscus Posterior Root Tear with Adjustable Titanium Plate Fixation

Riepilogo

This article describes a surgical approach to repairing a medial meniscus posterior root tear (MMPRT) using a single-suture, double-loop, adjustable titanium plate internal fixation under arthroscopy.

Abstract

Medial meniscus injury is one of the most prevalent knee disorders, with posterior root tears occurring in approximately 10% to 21% of affected individuals. A posterior root tear disrupts the meniscus's continuous annular structure, compromising its ability to absorb pressure and protect the knee's articular cartilage. If left untreated, this can result in increased stress on the cartilage, leading to conditions such as varus deformity and accelerated joint degeneration. Partial removal (resection) of the medial meniscus further exacerbates these issues, often leading to quicker joint deterioration. Repairing medial meniscus posterior root tears (MMPRTs) plays a crucial role in restoring the meniscus's structural integrity and improving knee biomechanics. Studies have shown that compared to partial medial meniscectomy or conservative treatments, repairing MMPRTs enhances clinical outcomes and significantly delays the onset of arthritis. This article details a surgical procedure that uses a single-suture, double-loop, adjustable titanium plate fixation technique under arthroscopy for effective MMPRT repair.

Introduzione

The meniscus consists of fibrocartilage and cannot repair itself after an injury, except for partial injuries to the margins, which can heal on their own. A normal meniscus increases the depth of the tibial condyle and cushions the medial and external femoral condyles, enhancing joint stability and absorbing shock. After a meniscus injury, joint space pain can occur, and in severe cases, it may be accompanied by symptoms such as joint locking. Posterior root tears occur in 10% to 21% of patients with medial meniscus injuries^1,2,3,4. The attachment point of the medial meniscus posterior root (MMPR) to the posterior region of the tibial intercondylar spine firmly anchors the meniscus to the tibial plateau, and its integrity plays an important role in maintaining the position and function of the normal meniscus⁵. A tear at the MMPR is an avulsion of the posterior tibial attachment of the medial meniscus or a radial tear within 1 cm of the bony attachment of the MMPR⁶, first reported by Pagnani et al. in 1991⁷. MMPRTs are mostly degenerative injuries of the meniscus and commonly affect middle-aged and elderly patients⁸. Risk factors for posterior root tears of the medial meniscus include age, female sex, obesity (high Body Mass Index), and knee varus^1,9. Activities such as descending stairs and jogging place twice the amount of stress on the MMPR compared to ordinary walking⁹, meaning poor exercise habits can also increase the likelihood of posterior root tears.

The MMPR is anchored to the tibial plateau to maintain the annular structure of the meniscus, which helps redistribute axial pressure across the joint, reducing the load on the cartilage^10,11,12,13. When the knee joint experiences axial pressure, the meniscus is compressed and dislocated outward, which prevents it from adequately alleviating the axial stress on the knee joint, thereby accelerating joint degeneration and the development of osteoarthritis^{10,11,14,15,16}. MMPRTs carry a higher risk of articular cartilage damage compared to other types of degenerative meniscal injuries^3,17. Additionally, the larger the tear gap caused by the posterior root tear, the more severe the impact on the cartilage^17,18,19.

Treatment options for MMPRTs include posterior root repair, partial meniscectomy, and conservative treatment. It has been reported that patients who undergo posterior meniscus root repair experience a significant delay in the progression of arthritis compared to those treated with partial meniscectomy or conservative methods, as shown by K-L grading on anterior lateral knee radiographs pre-operation versus post-operation²⁰. After a tear at the MMPR, there is no functional or biomechanical difference from partial meniscectomy, as the absence of a ring-like stabilizing structure reduces the dispersion of axial forces²¹. MMPRT repair improves clinical outcomes, with 87% of patients unresponsive to conservative treatment and 31% requiring knee arthroplasty within 5 years^11,22,23. A follow-up of patients with MMPRTs receiving conservative treatment for at least 10 years reported failure in approximately 95% of cases, with around 64% undergoing knee arthroplasty²⁴. Numerous studies have shown that repair surgery is superior to partial meniscectomy and conservative treatment in terms of efficacy and function for patients with MMPRT, significantly delaying the progression of osteoarthritis^4,24,25,26. This article describes a surgical approach to repairing MMPRT using a single-suture, double-loop, adjustable titanium plate internal fixation under arthroscopy.

Protocollo

This protocol was approved by the Ethics Committee of Hebei Medical University Third Hospital (K2023-086-1). The patient and their family agreed upon the surgical plan, and an informed consent form was signed. The inclusion criteria for the surgical approach were patients with knee MMPRT and Kellgren-Lawrence grade 0-III osteoarthritis without severe varus deformity. Exclusion criteria were: patients with knee MMPRT with injury to the medial meniscus body or anterior horn, injury to the anterior or posterior cruciate ligament, injury to the medial collateral ligament, or Kellgren-Lawrence grade IV osteoarthritis²⁷. The details of the reagents and equipment used in this study are listed in the Table of Materials.

1. Pre-operative preparation

1. Abstain from eating and drinking for 6 h before the operation. Choose neuraxial anesthesia or general anesthesia based on the anesthesiologist's pre-operative assessment of the patient's physical condition (following institutional guidelines).
2. Position the patient in the supine position on the operating bed.
3. Apply a tourniquet to the proximal one-third of the affected limb. Disinfect the affected limb with 2% iodine, covering all areas distal to the tourniquet. Wait 2-3 min for the iodine to dry. Perform deiodination twice with 75% medical alcohol.
4. Place the operating sheet, elevate the affected limb, and use a pneumatic tourniquet to expel venous blood from the distal to the proximal end of the limb. Inflate the tourniquet to SBP + 100 mmHg and set the timer for 90 min.

2. Checking the lesions

1. Use an 11 G sharp knife to make an incision 5 mm from the joint capsule at the upper edge of the tibial plateau, extending 1 cm on both sides of the parapatellar joint. Establish the anteromedial and anterolateral approaches to the knee joint, respectively²⁸.
   NOTE: This procedure is performed with the knee flexed at 90 degrees.
2. Insert the arthroscope through the anterolateral approach to the knee. Insert a probe through the anteromedial approach. Examine the knee to locate the MMPRT (Figure 1A).
   NOTE: Apply valgus and external rotation stress to the knee joint to fully expose the posterior medial compartment.

3. Creating a single-suture single-loop knot

1. Use an epidural needle to puncture the skin on the posteromedial aspect of the knee joint. Insert the needle into the joint at the upper edge of the MMPR.
2. Insert the needle 3 mm outward from the center of the MMPRT and thread a 2-0 PDS suture along the core of the epidural needle (Figure 1B).
3. Establish an anteromedial approach to the knee.
   NOTE: The incision should be positioned at the midline of the patellar ligament, 1 cm below the inferior pole of the patella.
4. Place wire grabbers through the anteromedial approach and pull the PDS suture out below the meniscus.
5. Fix one end of the PDS suture at the anteromedial approach and use a thread grabber to pull the PDS suture above the meniscus.
6. Tie the PDS suture with a No. 2 non-absorbable suture outside the anteromedial approach. Pull the PDS suture through the meniscus until it emerges outside the joint, then untie the PDS knot.
   NOTE: The reflexed end of the non-absorbable suture should be drawn out from the anteromedial incision, with the two free ends remaining outside the incision.
7. Pull the free ends of the non-absorbable suture to draw the body loop of the suture into the joint. Place a thread grabber through the anteromedial approach inside the joint. Capture a free end of the non-absorbable suture through the single loop and pull it out through the anteromedial approach.
8. Use a thread grabber to hold the free ends of the non-absorbable suture and pull them outside the anteromedial approach to form a single-suture, single-loop knot (Figure 1C).

4. Creating a single-suture double-loop knot

1. Repeat steps 3.1-3.2, placing a PDS suture 3 mm outside the first puncture point of the MMPR.
2. Repeat steps 3.4-3.7, and use a thread grabber through the anteromedial approach. Pull the other free end of the non-absorbable suture through the second loop to form a single-suture double-loop knot (Figure 1D).

5. Creating a single-suture double-loop adjustable titanium plate complex

1. Make a 1 cm incision at Gerdy's tubercle²⁹, extending to the bone cortex to serve as the external entrance of the tunnel.
2. Locate the inner entrance of the tunnel 5 mm inward from the tear of the posterior root.
3. Insert the guide needle from the outside to the inside, ensuring the tip of the needle pierces through the inner entrance of the tunnel.
   NOTE: Use the anterior cruciate ligament (ACL) reconstruction locator to accurately locate the inner and outer openings of the tunnel.
4. Use a 5 mm drill, following the guide needle from the outside to the inside, to create the bone tunnel.
   NOTE: Use two retractors to pull back the skin and subcutaneous soft tissues to expose the outer opening of the tunnel; otherwise, it may be difficult to locate the outer opening.
5. Place the PDS thread loop in the anteromedial approach to the inner entrance of the tunnel. Insert a thread grabber from the outer entrance of the tunnel to the inner entrance. Capture the PDS thread loop and a free end of the non-absorbable suture.
   NOTE: The two free ends of the PDS thread should be outside the anteromedial approach, and the PDS thread loop and a free end of the non-absorbable suture should be pulled out to the outer entrance of the bone tunnel.
6. Pass the free end of the non-absorbable suture through the adjustable titanium plate loop and then through the PDS thread loop. Pull the free ends of the PDS thread and the non-absorbable suture outside the anteromedial approach.
7. Tighten the free end of the non-absorbable suture and locate the adjustable loop in the single-suture double-loop configuration (Figure 1E).
8. Use a knotter to tie the non-absorbable sutures, forming the single-suture double-loop adjustable titanium plate complex.
   NOTE: The first knot must be tied tightly, and the first knot should remain secure when tying the second knot.

6. Fixing the MMPR

1. Pull the adjustable loop to draw the single-suture double-loop adjustable titanium plate complex, pulling the torn MMPR into the inner entrance of the tunnel.
2. Gradually tighten the titanium plate towards the outer entrance of the tunnel until it adheres to the bone cortex.
   NOTE: When tightening the adjustable loop, proceed slowly because it is unidirectional and cannot be loosened once tightened.
3. Use a probe to examine the medial meniscus and ensure the MMPR is firmly fixed in the tibial plateau footprint (Figure 1F).
4. Cut the non-absorbable sutures at the base of the ties using a thread trimmer.

7. Closing the incisions

1. Suture the incisions using intermittent No. 4 silk sutures.
2. Cover the wound with sterile dressings.

8. Post-operative rehabilitation

1. On the first day after surgery, focus on strengthening the quadriceps muscles.
2. On the second day after surgery, begin knee flexion and extension exercises.
3. On the second day after surgery, ask the patient to start walking without weight-bearing, using a brace for protection.
4. From 1-6 weeks after surgery, ask the patient to walk with partial weight-bearing while using a brace for protection.
5. On the 12^th day after surgery, remove the sutures.
6. From 6-12 weeks after surgery, ask the patient to walk with full weight-bearing, under the protection of a brace, and gradually resume normal movement.
7. At 3 months post-surgery, remove the brace and gradually return to normal activities.

Risultati

A total of 35 patients participated in the study, consisting of 25 females and 10 males. The average age was 53.54 years ± 11.03 years, ranging from 28 years to 78 years. Among the patients, 15 had an MMPR tear accompanied by degeneration of the medial femoral condyle or tibial plateau articular cartilage, classified as grade 2 or lower (Figure 2). The other 20 patients had an MMPR tear with grade 3 degeneration of the medial femoral condyle or tibial plateau articular cartilage (

Discussione

Treatment options for MMPRTs include posterior root repair, partial meniscectomy, and conservative treatment. Many studies have shown that partial medial meniscectomy and conservative treatment are ineffective in preventing or delaying osteoarthritis^23,26,33. MMPRT repair, however, can effectively alleviate pain symptoms and prevent or delay the progression of osteoarthritis. For patients with MMPRTs accompanied by severe medial...

Materiali

Name	Company	Catalog Number	Comments
Adjustable loop titanium plate	star	F06003978	Φ60
Aimer,tip,drctr ACL guide	smith&nephew	7205519
Angled bullet	smith&nephew	7207282
Arthroscopic sheath	smith&nephew	72200829	6 mm
Arthroscopy	smith&nephew	72202087	30° 4 mm
Beam guide	smith&nephew	72204925	5 mm x 3.6 m
Beam guide-arthroscopy end connector	smith&nephew	2143
Beam guide-panel connector	smith&nephew	2147
Blood-repellent belt	selani	tpe15100	15 cm x1 m
Blunt puncture cone	smith&nephew	4356	4 mm
Camera	smith&nephew	72200561	NTSC/PAL
Canulated drill	smith&nephew	13498	5 mm
Coupler	smith&nephew	72200315
Drill guide wire	smith&nephew	14396	2.4 mm
DYONICS POWER II	smith&nephew	72200873	100-24VAC, 50/60Hz
DYONICS POWERMAX ELITE	smith&nephew	72200616
Elite Knot Manipulating Full Loop	smith&nephew	72201213
Elite Premium Bankart Rasp	smith&nephew	72201660
Elite premium suture loop vertical grasper,blue handle	smith&nephew	7209494
Elite sliding suture cutter	smith&nephew	7209492
Endoscopic camera system	smith&nephew	72201919	560P NTSC/PAL
Handle	smith&nephew	7205517
HD monitor	smith&nephew	LB500031	27 inch
Hook probe	smith&nephew	3312
Incisor plus platinum shaver	smith&nephew	72202531	4.5 mm
Lumbar needle  AN-E/S II	tuoren	AN-E/S	1.6 x 80 mm
Micropunch,teardrop,left	smith&nephew	7207602
Micropunch,teardrop,right	smith&nephew	7207601
Micropunch,teardrop,straight	smith&nephew	7207600
PDS II	Johnson&Johnson	D6451	2-0
Pitbull Jr. Grasper	smith&nephew	14845
Shoulder Elavator	smith&nephew	13949