Effect of partial meniscectomy at the medial posterior horn on tibiofemoral contact mechanics and meniscal hoop strains in human knees

We examined the influence of partial meniscectomy of 10 mm width on 10 human cadaveric knee joints, as it is performed during the treatment of radial tears in the posterior horn of the medial meniscus, on maximum contact pressure, contact area (CA), and meniscal hoop strain in the lateral and medial knee compartments. In case of 0° and 30° flexion angle, 20% and 50% partial meniscectomy did not influence maximum contact pressure and area. Only in case of 60° knee flexion, 50% partial resection increased medial maximum contact pressure and decreased the medial CA statistically significant. However, 100% partial resection increased maximum contact pressure and decreased CA significantly in the meniscectomized medial knee compartment in all tested knee positions. No significant differences were noted for meniscal hoop strain. From a biomechanical point of view, our in vitro study suggests that the medial joint compartment is not in danger of accelerated cartilage degeneration up to a resection limit of 20% meniscal depth and 10 mm width. Contact mechanics are likely to be more sensitive to partial meniscectomy at higher flexion angles, which has to be further investigated.     

Is repeated repair of the meniscus worthwhile?

Meniscal injuries are one of the most commonly encountered problems by orthopaedic surgeons. It is well established that meniscectomy will result in increased joint surface contact forces and the predictable progression of arthritis. The management of meniscal tears has evolved and current evidence would suggest that every attempt should be made to repair meniscal tears when appropriate. The reported success rate of meniscal repair is encouraging, but relatively little is known about the outcome of repeated repair of a re-torn meniscus. This review presents an illustrative case of a recurrent lateral meniscal tear in a young female, that has required surgical repair on three occasions over a fourteen year period. Despite recurrent tears of her lateral meniscus, the patient was symptom-free in the intervening periods and at her latest operation, her articular cartilage showed minimal evidence of chondral damage. Longer-term follow-up is required to determine whether repair of a re-torn meniscus prevents the progression of degenerative changes within the knee joint that is associated with meniscectomy.     

Meniscectomy

To review the meniscus from a historical perspective especially on surgical management and general guidelines for arthroscopic meniscectomy procedures for various types of meniscal tears. We searched MEDLINE and PubMed for the years of 1980-2010 using the terms meniscus, meniscal repair, menisectomy, and arthroscopy. Orthopedic surgeons frequently encounter patients with pain or functional impairment of the knee joint and repair or resection of the injured meniscus is one of the most common orthopedic operative procedures. The object of meniscal surgery is to reduce pain, restore functional meniscus and prevent the development of degenerative osteoarthritis in the involved knee. Historically, total meniscectomy was a common procedure performed for meniscus tear symptoms. However, it has been reported that total meniscectomy has deleterious effects on the knee. In the past, the menisci were thought as a functionless remnant tissue. Currently, it is known that the meniscus is an important structure for knee joint function. Menisci provide several vital functions including mechanical support, localized pressure distribution, and lubrication to the knee joint. It is widely accepted that the function of the meniscus can be preserved through minimal excision. An arthroscopic partial meniscectomy preserving more of the meniscus is preferred over total meniscectomy. In recent decades, this shift toward arthroscopic partial meniscectomy has led to the development of new surgical techniques.     

Meniscal Root Tears

Meniscus root tears are a specific type of meniscal injury that have gained attention over the past 5 years and have been reported to account for 10% to 21% of all meniscal tears, affecting nearly 100,000 patients annually. Meniscal root tears either are defined as an avulsion of the insertion of the meniscus attachment or complete radial tears that are located within 1 cm of the meniscus insertion. Biomechanical studies have demonstrated that meniscal root injuries interrupt the continuity of the circumferential fibers, and hence lead to failure of the normal meniscal function to convert axial loads into transverse hoop stresses. The most common presenting symptoms in meniscal root tears are posterior knee pain and joint line tenderness, especially with deep squatting.Another common symptom is a popping sound heard while participating in light activities such as ascending stairs or squatting. Magnetic resonance imaging signs of medial meniscus root tears include: (1) medial meniscal extrusion of ≥3 mm in a coronal section; (2) high signal indicating a disruption of the posterior meniscal root region in an axial view; and (3) a “ghost sign,” which is the absence of an identifiable meniscus in the sagittal plane, or increased signal replacing the normally dark meniscal tissue signal at the posterior root attachment. Active patients, regardless of age, should be referred early and considered for a meniscal root repair. Indications for a meniscal root repair include acute, traumatic root tears in patients with nearly normal or normal cartilage and chronic symptomatic root tears in young or middle-aged patients without significant preexisting osteoarthritis.Meniscal root repair has been demonstrated to have high satisfaction rates and superior outcomes to arthroscopic meniscectomy for root tears. To restore the function of the meniscus after medial meniscus root tears, a transosseous meniscal root repair technique is most commonly used. The advantage of this technique is the ability to reduce and fix the meniscal root to the broad anatomic footprint to maximize its healing potential. In addition, the transtibial tunnels may contribute to the release of biological factors that can enhance the healing of the meniscal root repair.     

Is it important to secure the horns during lateral meniscal transplantation? A cadaveric study

The purpose of this investigation was to determine if secure attachment of the horns of the lateral meniscus during transplantation affects the load-bearing function of the meniscus. Six knee joints were loaded in compression (310 N) and the interarticular contact pressure in the joint measured using pressure-sensitive film inserted into the joint. Each knee was tested first with the original intact meniscus and then after each of the following surgical procedures involving the original lateral meniscus: (1) total meniscectomy; (2) meniscal transplantation with a tibial bone bridge; (3) meniscal transplantation with neither horn secured; (4) meniscal transplantation with the anterior horn secured; (5) meniscal transplantation with the posterior horn secured; and (6) meniscal transplantation with both horns secured. The results are as follows, (1) The intact joint gave the largest contact area and the smallest peak contact pressure. The joint with the total meniscectomy gave the smallest contact area and the largest peak contact pressure. (2) A meniscal transplantation with either a tibial bony bridge or with both horns secured gave results similar to those for the intact joint. (3) A meniscal transplantation with only one horn secured gave results somewhere in between those for the intact joint and those for the joint without a meniscus. A meniscal transplantation with neither horn secured gave results similar to those for a joint without a meniscus.     

The effect of complete radial lateral meniscus posterior root tear on the knee contact mechanics: a finite element analysis

Background

In recent years, with technological advances in arthroscopy and magnetic resonance imaging and improved biomechanical studies of the meniscus, there has been some progress in the diagnosis and treatment of injuries to the roots of the meniscus. However, the biomechanical effect of posterior lateral meniscus root tears on the knee has not yet become clear. The purpose of this study was to determine the effect of a complete radial posterior lateral meniscus root tear on the knee contact mechanics and the function of the posterior meniscofemoral ligament on the knee with tear in the posterior root of lateral meniscus.

Methods

A finite element model of the knee was developed to simulate different cases for intact knee, a complete radial posterior lateral meniscus root tear, a complete radial posterior lateral meniscus root tear with posterior meniscofemoral ligament deficiency, and total meniscectomy of the lateral meniscus. A compressive load of 1000 N was applied in all cases to calculate contact areas, contact pressure, and meniscal displacements.

Results

The complete radial posterior lateral meniscus root tear decreased the contact area and increased the contact pressure on the lateral compartment under compressive load. We also found a decreased contact area and increased contact pressure in the medial compartment, but it was not obvious compared to the lateral compartment. The lateral meniscus was radially displaced by compressive load after a complete radial posterior lateral meniscus root tear, and the displacement took place mainly in the body and posterior horn of lateral meniscus. There were further decrease in contact area and increases in contact pressure and raidial displacement of the lateral meniscus in the case of the complete posterior lateral meniscus root tear in combination with posterior meniscofemoral ligament deficiency.

Conclusions

Complete radial posterior lateral meniscus root tear is not functionally equivalent to total meniscectomy. The posterior root torn lateral meniscus continues to provide some load transmission and distribution functions across the joint. The posterior meniscofemoral ligament prevents excessive radial displacement of the posterior root torn lateral meniscus and assists the torn lateral meniscus in transmitting a certain amount of stress in the lateral compartment.     

Importance of the medial meniscus in the anterior cruciate ligament-deficient knee.

The incidence of meniscal tears in the chronically anterior cruciate ligament-deficient knee is increased, particularly in the medial meniscus because it performs an important function in limiting knee motion. We evaluated the role of the medial meniscus in stabilizing the anterior cruciate ligament-deficient knee and hypothesized that the resultant force in the meniscus is significantly elevated in the anterior cruciate ligament-deficient knee. To test this hypothesis, we employed a robotic/universal force-moment sensor testing system to determine the increase in the resultant force in the human medial meniscus in response to an anterior tibial load following transection of the anterior cruciate ligament. We also measured changes in the kinematics of the knee in multiple degrees of freedom following medial meniscectomy in the anterior cruciate ligament-deficient knee. In response to a 134-N anterior tibial load, the resultant force in the medial meniscus of the anterior cruciate ligament-deficient knee increased significantly compared with that in the meniscus of the intact knee; it increased by a minimum of 10.1 N (52%) at full knee extension to a maximum of 50.2 N (197%) at 60 degrees of flexion. Medial meniscectomy in the anterior cruciate ligament-deficient knee also caused a significant increase in anterior tibial translation in response to the anterior tibial load, ranging from an increase of 2.2 mm at full knee extension to 5.8 mm at 60 degrees of flexion. Conversely, coupled internal tibial rotation in response to the load decreased significantly, ranging from a decrease of 2.5 degrees at 15 degrees of knee flexion to 4.7 degrees at 60 degrees of flexion. Our data confirm the hypothesis that the resultant force in the medial meniscus is significantly greater in the anterior cruciate ligament-deficient knee than in the intact knee when the knee is subjected to anterior tibial loads. This indicates that the demand on the medial meniscus in resisting anterior tibial loads is increased in the anterior cruciate ligament-deficient knee compared with in the intact knee, suggesting a mechanism for the increased incidence of medial meniscal tears observed in chronically anterior cruciate ligament-deficient patients. The large changes in kinematics due to medial meniscectomy in the anterior cruciate ligament-deficient knee confirm the important role of the medial meniscus in controlling knee stability. These findings suggest that the reduction of resultant force in the meniscus may be a further motive for reconstructing the anterior cruciate ligament, with the goal of preserving meniscal integrity.     

The role of the meniscus in the anterior-posterior stability of the loaded anterior cruciate-deficient knee. Effects of partial versus total excision

The effects of progressive removal of the menisci on the anterior-posterior force-versus-displacement response of the anterior cruciate-deficient knee were studied in fresh cadaver specimens at 20 degrees of flexion without and with tibial-femoral contact force (joint load). In the absence of joint load, removal of the medial meniscus increased total anterior-posterior laxity measured at 200 newtons of applied tibial force by 10 per cent, and subsequent lateral meniscectomy produced an additional 10 per cent increase. When a bucket-handle tear of the medial meniscus was removed, the application of joint load caused the tibia to displace (subluxate) forward on the femur, thereby changing the balance condition of the knee. Subsequent removal of the remainder of the medial meniscus and complete lateral meniscectomy both produced additional smaller anterior tibial subluxations. Changes in total anterior-posterior laxity due to progressive meniscectomy in the loaded knee were dependent on both the amount of applied anterior-posterior force and the level of compressive force. At 200 newtons of anterior-posterior tibial force, increases in laxity in the loaded knee due to progressive meniscal removal were not significantly different than those recorded in the unloaded condition. At applied forces of fifty newtons or less, the laxities for loaded specimens were always significantly less than those for unloaded specimens at comparable stages of meniscal removal. Bilateral meniscectomy had no significant effect on the posterior response curve, as posterior tibial translation was effectively checked by the intact posterior cruciate ligament.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolated lateral meniscectomy. A study of twenty-six patients with isolated tears

To better define the role that the lateral meniscus plays in stabilizing the knee, a study was made of twenty-six patients who had an uncomplicated lateral meniscectomy between 1972 and 1977. Patients with any degree of ligament instability, cruciate or collateral, prior to lateral meniscectomy were eliminated from the study. Also eliminated were any patients with roentgenographic evidence of degenerative arthrits, osteochondritis dissecans, or loose bodies. Only patients whose operative reports stated that the articular cartilage of the lateral compartment was either grossly normal or showed Grade-1 chondromalacia (less than one centimeter in diameter and only softening of the cartilage) at the time of surgery were included in the review. The meniscal lesions included bucket-handle tears, horizontal cleavage tears, and multiple linear defects. No grossly cystic menisci were included in the study. Two menisci demonstrated cystic degenerative changes on histological section. In sixteen patients some degree of ligament instability developed. The longer the interval between injury to the meniscus and its excision, the less satisfactory the result. Only fifteen (54 per cent) of the patients reported satisfactory results, and twenty lost some motion of the knee. We concluded that stability of the knee joint is a multifactorial problem, in which the lateral meniscus certainly plays an important part.     

Arthroscopic treatment of cysts of the menisci. A preliminary report

A retrospective clinical study evaluated the results of arthroscopic management of cysts of the menisci. From 1979 to 1984, 24 patients with a diagnosis of meniscal cysts associated with tears of the semilunar cartilage were treated with partial meniscectomy and cyst decompression. The mean age was 29.9 years (range, 14-52 years). Each patient had tenderness over the joint line with a palpable mass. There were 25 cases of meniscal cysts, with one patient having a bilateral cyst. Twenty-two cysts involved the lateral meniscus, and three cysts were on the medial side of the knee. The follow-up period ranged from 16 to 48 months (mean, 33.5 months). All patients had a meniscal tear; most tears were either horizontal or transverse, with or without flap formation. The pathology was in the middle or anterior one-third of the meniscus. The arthroscopic surgery consisted of partial excision of the meniscal tear, leaving a peripheral rim at times, coupled with aspiration of the cyst material or manipulation of its contents into the joint cavity. No cyst recurred, and in every patient except one, preoperative symptoms disappeared. All patients but one were satisfied with the results. Two patients had a second arthroscopy, and no evidence of instability of the peripheral rim was found.     

Arthroscopic surgery of the knee in local anaesthesia

Summary Arthroscopy of the knee joint was performed in 356 consecutive outpatients in local anaesthesia and without premedication. A continuous pressure-irrigation system was used with 0.2% lidocaine chloride solution in the irrigation fluid, following administration of 5–7 ml prilocaine with epinephrine in each portal. All patients had clinical symptoms of internal derangement of the knee, such as meniscal, cruciate ligament injury or osteoarthritis. Associated intra-articular pathology was registered. Intra-articular surgery was performed in 228 cases. This included partial or subtotal meniscectomy in 207 cases and meniscus suture in 3 cases. In 18 of 228 cases (8%) the operative procedure had to be terminated due to patient discomfort. Of the meniscal injuries 84% were medial and 16% lateral. The age distribution of the medial meniscus tears was as follows: bucket handles 33 ± 9 years; flap tears 42 ± 10 years and degenerative tears 53 ± 10 years. For the lateral meniscus the age distribution was: bucket handles 34 ± 9 years, cleavage and radiating tears 37.5 ± 12 years, flap tears 29 ± 7 years, peripheral tears 32 ± 9 years and degenerative tears 48 ± 11 years. Osteoarthritis was observed in 52% of all medial degenerative tears, whereas a low frequency was found in the remaining tears. The majority of patients tolerated the procedure well. In summary, 64% of the consecutive arthroscopies were operative, including 3 meniscal sutures. Only 8% of these procedures had to be abandoned due to patient discomfort. Thus, arthroscopic surgery in local anaesthesia with no premedication is an efficient and well-tolerated method in outpatient practice.     

Editorial Commentary: Save the Meniscus? Show Me the Money!

The meniscus is known to play a vital role in the knee joint from, shock absorption to increased contact area to joint lubrication. Repairing a torn meniscus costs money, but it can be even more expensive to perform a partial meniscectomy over the long term. Moreover, meniscal repair may result in an improved quality of life for the patient. One must consider both quality of life and costs when addressing repairable meniscal tears in patients. Repairing a vertical meniscus tear in the red-red zone in a young adult is a cost-effective strategy.     

Nonoperative treatment of partial-thickness meniscal tears identified during anterior cruciate ligament reconstruction

The reported incidence and treatment of partial-thickness meniscal tears seen at anterior cruciate ligament (ACL) reconstruction varies widely. The success of nonoperative treatment of partial meniscal tears identified during ACL reconstruction at our institution was reviewed. All incomplete meniscal tears were treated with observation, all full-thickness tears were treated with repair or partial meniscectomy. Partial tears of the lateral meniscus were noted three times more commonly than in the medial meniscus and were seen more acutely after ACL injury than full-thickness tears. At 2-year follow-up, excellent knee function was noted when these tears were treated nonoperatively.     

Meniscal Replacement With a Silk Fibroin Scaffold Reduces Contact Stresses in the Human Knee

The aim of the current study was to verify if a previously developed silk fibroin scaffold for meniscal replacement is able to restore the physiological distribution of contact pressure (CP) over the articulating surfaces in the human knee joint, thereby reducing peak loads occurring after partial meniscectomy. The pressure distribution on the medial tibial articular surface of seven human cadaveric knee joints was analysed under continuous flexion–extension movements and under physiological loads up to 2,500 N at different flexion angles. Contact area (CA), maximum tibiofemoral CP, maximum pressure under the meniscus and the pressure distribution were analysed for the intact meniscus, after partial meniscectomy as well as after partial medial meniscal replacement using the silk fibroin scaffold. Implantation of the silk fibroin scaffold considerably improved tibiofemoral contact mechanics after partial medial meniscectomy. While the reduced CA after meniscectomy was not fully restored by the silk fibroin scaffold, clinically relevant peak pressures on the articular cartilage surface occurring after partial meniscectomy were significantly reduced. Nevertheless, at high flexion angles static testing demonstrated that normal pressure distribution comparable to the intact meniscus could not be fully achieved. The current study demonstrates that the silk fibroin implant possesses attributes that significantly improve tibiofemoral CPs within the knee joint following partial meniscectomy. However, the failure to fully recapitulate the CAs and pressures observed in the intact meniscus, particularly at high flexion angles, indicates that the implant's biomechanical properties may require further improvement to completely restore tibiofemoral contact mechanics. © 2019 The Authors. Journal of Orthopaedic Research^® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2583–2592, 2019     

Editorial Commentary: Degenerative Meniscal Tear: Sojourn to the Oracle

Degenerative meniscal tears are prevalent and give rise to more than 400,000 arthroscopic partial meniscectomies annually in the United States. These lesions often occur in the setting of knee osteoarthritis and are generally regarded as a component of the tissue damage (to cartilage, meniscus, bone, synovium among others) that comprises osteoarthritis. A wide array of clinicians, ranging from orthopaedic surgeons to general practitioners, regularly encounter symptomatic degenerative meniscal tears, especially among patients with knee osteoarthritis. Clinical evidence suggests that initial treatment for these injuries should be nonoperative, with arthroscopic partial meniscectomy reserved for those whose pain persists despite physical therapy.     

中老年膝内侧半月板后角放射裂的临床研究

目的讨论膝内侧半月板后角放射状撕裂的临床特点和关节镜下半月板部分切除术后的随访结果。方法自2000年6月至2006年6月对386例（418膝）关节镜下治疗的膝内侧半月板撕裂患者进行回顾性研究,其中后角放射状撕裂93膝（22．2％）,全部行半月板部分切除术。在详细的手术记录和关节镜图像资料基础上,分析患者术前体征、MRI结果、术中所见和术后Lysholm膝关节评分。结果中老年患者中膝内侧半月板后角放射状撕裂有较高的发生率,大多数患者表现出机械卡压或撞击症状,MRI很难发现这种撕裂,有特点的疼痛症状和物理检查有助于诊断。虽然大多数患者年龄较大,关节软骨已发生退变,但关节镜下半月板部分切除术后,症状会明显改善。结论膝内侧半月板放射状撕裂比较常见,但因为多数患者同时伴有骨关节炎症状,且MRI上假阴性率较高,诊断比较困难。在严格掌握手术指征下,关节镜下半月板部分切除术有助于改善症状。     

Factors affecting long-term results after arthroscopic partial meniscectomy

The purpose of this study was to determine functional and radiographic changes on long-term followup of knees with isolated meniscal tears. Sixty-seven patients were evaluated retrospectively with an average of 12.2 years' followup using the scale of Tapper and Hoover. The criteria for the radiographic results were the Fairbank's changes as the standard comparing the preoperative and the postoperative conditions of the affected knee with the contralateral knee. Seventy-nine percent of the patients had a satisfactory outcome in terms of function. The amount of meniscus removed and the Outerbridge classification of the articular cartilage at the time of the meniscectomy were determining factors for long-term functional results. Osteoarthritic deterioration was seen in 48% of patients after the surgery, but radiographic deterioration after arthroscopic partial meniscectomy was mild on long-term followup. Medial meniscectomy and the amount of meniscus removed were risk factors for postoperative radiographic change. Age, gender, and the degree of cartilage degeneration at the time of operation, in contrast, showed no significant association. Arthroscopic partial meniscectomy for isolated meniscal injury yields favorable functional results but leads to significantly increased osteoarthritic change in the long-term.     

Arthroscopic meniscectomy for discoid lateral meniscus in children

We reviewed the cases of forty-six children who were less than fifteen years old and in whom total, subtotal, or partial arthroscopic meniscectomy was performed for symptomatic discoid lateral meniscus in fifty-three knees. The average length of follow-up was 31.2 months. A meniscal tear was evident in each knee. The extent of the meniscectomy depended on the site and shape of the tear, as did the symptoms and signs. We tried to establish the width of partial meniscectomy of a discoid meniscus that would prevent new tears.     

自体游离骨膜再造膝关节半月板的实验研究

目的：对于严重损伤的半月板全切除术后行自体游离骨膜重建半月板，以维持膝关节结构、生理及功能特性。方法：使用１７只成年犬，５只幼犬。外侧半月板全切除以后，胫骨内侧近端的骨膜游离并移植到外侧半月板部位。于２、４、８、１２、２４、４８周取下重建半月板及不同部位的关节面软骨进行大体、光镜及电镜观察。结果：术后２个月，重建半月板的大体形态、组织结构与正常半月板近似。外侧股骨软骨面及没有被覆盖的胫骨软骨面表现退行性改变，被移植物覆盖的软骨面退变较轻。幼犬的退变更早、更严重。结论：本研究说明了自体游离骨膜在滑液环境及受到合适的应力刺激会向纤维软骨演化，在半月板全切除后，应用游离骨膜重建半月板是可行的