ORTHOPEDICS April 2011;34(4):276.

Posterior Reattachment of a Radial Tear in the Posterior Root of the Medial Meniscus

by Kyung Wook Nha, MD; Kook Hyun Wang, MD; Gautam M. Shetty, MD; Chang Soo Lee, MD; Jong In Kim, MD

The new posterior vertical mattress suture technique is technically easier to perform and provides more secure fixation than the arthroscopic simple or horizontal stitch techniques and may contribute to restoring function of the medial meniscus.

Cover illustration © Scott Holladay

The meniscus is known to have a role in shock absorption and dispersing load transmission, thereby protecting and enhancing stability of the knee joint. A radial tear at the posterior root of the medial meniscus is not uncommon. A root tear has been defined as a radial tear that occurs within 1 cm of the posterior horn insertion.¹ Recent studies have shown a relatively high incidence of complete posterior medial meniscus root tear, especially in east Asia.² A complete posterior medial meniscus root tear leads to a loss of hoop tension, resulting in a reduction of contact surface, thereby increasing contact pressure within the joint and leading to accelerated degenerative changes.³

Several reports have concluded that radial tears of the meniscus have a clinically different outcome when compared to other types of meniscal tears.⁴ Meniscectomy in these patients does not seem to prevent acceleration of osteoarthritis. Recently, an arthroscopic pullout suture technique has been described in the literature as a mode of surgical treatment for complete posterior medial meniscus root tear.^5,6 However, in this technique, a simple suture is placed along the direction of the circumferential collagen fibers within the meniscus, and hence is liable to failure when increased tensile forces are present.⁴ This article describes a more secure fixation method to restore the function of the meniscus by posterior reattachment using a vertical mattress suture.

Materials and Methods

From May 2004 to December 2008, a prospective study was performed in 25 patients with 31 meniscal tears who underwent meniscal repair and partial menisectomy at 1 institution. We reviewed the records of these patients after Institutional Review Board approval. Inclusion criteria were complete posterior medial meniscus root tear and a minimum 2-year follow-up. Patients with considerable articular cartilage degeneration defined as Kellgren-Lawrence⁷ grade >2; with associated ligament injury; who underwent additional procedures such as microfracture, chondroplasty, and synovial shaving; and with <2 years of follow-up were excluded. Surgery was performed when the remnant tissue of the posterior medial meniscus root tear was insufficient to direct repair (<3 mm).

Four men and 21 women had a mean age of 53.4 years (range, 23-70 years). Mean follow-up was 38 months (range, 27-60 months). Duration of symptoms preoperatively was <3 months in 21 patients (84%) who presented during the early phase and varied from 3 to 10 months for the remaining 4 patients (16%). All patients reported knee joint pain with no history of trauma or with trivial trauma. Of the patients, 9 (36%) had a history of a popping sound that preceded the onset of symptoms.¹ On physical examination, all patients were found to have medial or posteromedial joint line tenderness, a positive McMurray test for the medial meniscus, restriction of deep flexion, and an inability to squat. Joint aspiration was done in patients presenting with an effusion. Blood-tinged joint fluid,¹ confirmed by joint aspiration, was detected in 11 patients who presented in the early phase. Each radiograph was graded from 0 to 4 for osteoarthritis by the original criteria of Kellgren and Lawrence.⁷ All patients were evaluated with magnetic resonance imaging (MRI) preoperatively, and the complete posterior medial meniscus root tear was confirmed by arthroscopic examination (Figure 1).

Figure 1: Preoperative MRI showing complete posterior medial meniscus root tear (arrow) in the coronal section (A). Intraoperative arthroscopic image showing complete radial tear of the posterior horn of the medial meniscus (arrow) (B).

The complete posterior medial meniscus root tear was repaired by a posterior reattachment using vertical mattress sutures, and partial menisectomy was performed in 6 patients combined with meniscal horizontal tear. No additional procedures such as microfractures, synovial shaving, or chondroplasty were performed. Intraoperatively, arthroscopic evaluation and grading of the articular cartilage damage to the medial compartment of the knee joint were performed with the Outerbridge grading system.⁸International Knee Documentation Committee (IKDC) and modified Lysholm knee scores⁹ were obtained to evaluate knee function preoperatively and at last follow-up. Evaluation consisted of McMurray test and assessment of joint line tenderness, swelling, and blocking. Statistical analysis was performed with SPSS software version 12.0 (SPSS, Inc, Chicago, Illinois). A 2-tailed t test was used for comparison of pre- and postoperative IKDC and Lysholm scores, with significance determined to be <.05.

Surgical Technique

All procedures were performed with the patient under spinal or general anesthesia. Arthroscopy was performed through a routine anterolateral and anteromedial portal. First, arthroscopic examination identified a complete posterior medial meniscus root tear. The patient was turned over to the prone position. A 10-cm curved incision was made over the popliteal fossa, and dissection was performed between the semimembranosus and the medial head of the gastrocnemius (Figure 2A). The medial head of the gastrocnemius was retracted laterally, and care was taken to protect the popliteal artery and nerve (Figure 2B). The posterior aspect of the proximal tibia near the posterior cruciate ligament attachment was palpated to identify the posteromedial capsule. A longitudinal incision of approximately 3 cm was made over the posterior capsule to expose the torn posterior horn of the medial meniscus (Figure 3). The capsule was separated from the medial meniscus and the posterior aspect of the proximal tibia. The posterior tibial condyle around the posterior horn was decorticated using a curette to improve the healing process of the bone to the meniscus.

Figure 2: A 10-cm curved incision is made over the popliteal fossa (A). The medial head of the gastrocnemius (GCM) is retracted laterally, and care is taken to protect the popliteal artery and nerve (B).

Figure 3: Intraoperative view showing a complete posterior medial meniscus root tear (arrow) and K-wire being used to create bone tunnels on the posteromedial aspect of the proximal tibia. Figure 4: Photograph showing the 2 tibial tunnels with wire loops passed to help deliver the suture threads.

Two tunnels 5 mm apart were drilled from the posterior aspect of the proximal tibia using 2.0-mm K-wires, to exit just below the inferior aspect of the medial meniscus. Two wire loops were then passed through each of the tunnels to exit at the inferior surface of the meniscus (Figure 4). A nonabsorbable suture (Ethibond No. 2; Ethicon, Somerville, New Jersey) was first passed from the undersurface of the medial meniscus to its posterior aspect, which is perpendicular to the direction of the circumferential fibers. Another suture was then passed again from the posterior aspect of the meniscus to the undersurface of the medial meniscus so that there were 2 sutures on the undersurface of the meniscus (Figure 5). The sutures were then pulled out through the tibial tunnels with wire loops and tied to each other over the posteromedial surface of the proximal tibia, thereby recreating a posterior attachment site of the meniscus (Figure 6). By this technique, the posterior horn of the medial meniscus was rigidly fixed over the posterior aspect of the proximal tibia using a nonabsorbable suture material.

Figure 5: Schematic diagram showing the vertical mattress suture and posterior reattachment technique for posterior medial meniscus root tear. Abbreviations: Lat, lateral; MM, medial meniscus; MTC, medial tibial condyle.

Figure 6: Photograph (A) and schematic diagram (B) showing the suture threads delivered out through the tibial tunnels from the posteromedial aspect of the proximal tibia after securing the meniscus.

The procedure was performed with the knee in 30° of flexion. The wound was closed in layers, and an above-knee splint was applied with the knee in 30° of flexion. Quadriceps-strengthening and straight-leg raising exercises were started postoperatively. Range of motion exercises were started on postoperative day 3. The patient was allowed partial weight bearing and crutch walking for 6 weeks postoperatively. From postoperative weeks 6 to 10, crutch walking with 50% weight-bearing exercise was allowed. After 10 weeks postoperatively, the patient was instructed to walk bearing full weight.

The advantages of the new technique are (1) a shorter lever arm is used as compared to the arthroscopic tibial pullout suture technique, and (2) the meniscus is rigidly fixed due to a double vertical suture, which renders it a more anatomical fixation as compared to other arthroscopic fixation methods.

Results

All 25 patients had complete posterior medial meniscus root tear confirmed by MRI and arthroscopy and underwent meniscal repair by a posterior reattachment using vertical mattress sutures. Partial menisectomy was performed in 6 patients with meniscal horizontal tear. Seven patients (28%) had normal articular cartilage (Outerbridge grade 0), 13 (52%) had Outerbridge grade I articular cartilage, and 5 (20%) had Outerbridge grade II articular cartilage on the medial compartment of the knee joint. The mean preoperative Lysholm score, which averaged 68 points (range, 61-79 points), significantly increased to an average 89 points (range, 83-97 points) at last follow-up (P<.01). The IKDC scores improved significantly from an average 66 points (range, 60-77 points) preoperatively to an average 88 points (range, 81-96 points) postoperatively (P<.05). All patients had good to excellent IKDC scores at last follow-up (excellent, 90-100; good, 80-89; fair, 70-79; poor, <70). The change in Lysholm score and IKDC score at last follow-up as compared with preoperative values according to Outerbridge grading is summarized in the Table. At last follow-up, when we evaluated standing knee radiographs for evidence of osteoarthritis progression, 1 patient (4%) showed progression of degeneration from Kellgren-Lawrence grade 0 to 2, and 24 patients (96%) showed no progression (Figure 7).

Figure 7: One-year postoperative MRI showing healed posterior medial meniscus root tear without subluxation and bone tunnel on the posteromedial aspect of the proximal tibia (white arrow).

Discussion

The complete posterior medial meniscus root tear is a recently described entity wherein there is loss of hoop stress with extrusion of the meniscus, causing accelerated degeneration of the knee joint. It is reported to be biomechanically equivalent to a total meniscectomy.³ The complete posterior medial meniscus root tear occurs frequently in degeneration of the meniscus. The radial tear occurs perpendicular to that of the circumferential fibers of the meniscus and is thereby morphologically different from other types of meniscal tears; it can be either a partial or full-thickness tear extending from the inner margin to the periphery.⁴ A narrow medial joint space and overlooking the site of the tear are possible obstacles that may prevent the surgeon from recognizing it.² Their high incidence in east Asia is thought to be due to the lifestyle of squatting and sitting on the floor with legs crossed and folded, wherein maximal knee flexion is needed in activities of daily living.²

Definitive surgical treatment for complete posterior medial meniscus root tear has not yet been identified. The preservation of the meniscus seems to prevent the progression of degenerative arthritis. The ideal treatment option in a complete posterior medial meniscus root tear would be a primary suture, which restores meniscal hoop tension to its preinjury state.⁴ However, it is difficult to perform primary suturing within approximately 3 to 5 mm of the remnant tibial end of the meniscus. Even if it is possible, the risk of retearing is high when the joint is loaded.

Ahn et al⁵ and Kim et al⁶ described an arthroscopic pullout suture technique wherein a simple stitch was passed through an anterior transtibial tunnel using a posterior transseptal portal. The technique is difficult due to narrow space in the knee joint and liable to failure of the pullout suture due to the simple suture method.

In a biomechanical cadaveric study, Tejwani and Harner¹⁰ compared different meniscal repair techniques in complete posterior medial meniscus root tear, using 2-0 braided suture in a tibial tunnel technique with an Endobutton (Smith & Nephew, Memphis, Tennessee). The horizontal mattress stitch (91 N) had less pullout strength than the modified Kessler stitch (132 N) but more strength than a simple stitch (70 N).

Conclusion

Our new posterior vertical mattress suture technique is technically easier to perform and provides more secure fixation than the arthroscopic simple or horizontal stitch techniques. We performed this new technique on 25 knees and followed them for at least 2 years. Most patients’ symptoms improved postoperatively. However, longer follow-up is needed, and osteoarthritis changes should be evaluated in simple radiograph and MRIs.

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