Arthroscopic partial lateral meniscectomy in an otherwise normal knee: Clinical, functional, and radiographic results of a long-term follow-up study

Purpose: To determine the clinical, functional, and radiographic long-term results of patients who underwent arthroscopic partial lateral meniscectomy in an otherwise normal knee. Type of Study: This was a retrospective case-control study. Methods: Between 1982 and 1991, 107 arthroscopic partial lateral meniscectomies were performed; 75 of these patients had an isolated lateral meniscal tear and their data were evaluated using the Lysholm score and a questionnaire recording patients’ subjective satisfaction. Radiographic analysis was performed according to the Jäger-Wirth classification and Fairbank changes. Results: All 75 patients were examined by questionnaire, 55 underwent physical examination, and 58 had radiographic analysis. The follow-up period ranged from 5 to 15 years. Excellent and good Lysholm score results decreased from 77% at maximal improvement to 66% at follow-up; 43% of patients maintained their level of maximal improvement, 78% showed one or more Fairbank changes at follow-up, and using the Jäger-Wirth score, 84% showed radiographic deterioration. Conclusions: Although deterioration of functional and especially radiographic results occurred after arthroscopic partial lateral meniscectomy, the number of good results, even with mean follow-up of 12.3 years, is remarkable. There was a high percentage of radiographic changes in our study, but there is no significant correlation between them and subjective symptoms or between them and functional outcome. We believe that careful meniscectomy provides good results for a long period of time but, the longer the follow-up, the more radiographic changes have to be expected; when meniscal refixation is possible, it should be performed.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 9 (November-December), 2001: pp 946–952     

The effects of arthroscopic partial lateral meniscectomy in an otherwise normal knee: a retrospective review of functional,clinical, and radiographic results

A retrospective review of patients who underwent arthroscopic partial lateral meniscectomy for lateral meniscus tears in otherwise normal knees was conducted to review the long-term functional, clinical, and radiographic results. Twenty-six patients (27 knees) were evaluated by questionnaire; 20 patients (21 knees) also underwent physical examination and radiographic analysis. Minimum follow-up was 5 years and mean follow-up was 8 years. Patient data were obtained from detailed questionnaires, knee examinations, and radiographs. Excellent or good results decreased from 92% at the time of maximal improvement to 62% at the most recent follow-up: 85% of patients were initially able to return to their preinjury activity level; however, only 48% were able to maintain this level of activity at the most recent follow-up. Seventy-two percent of patients had either one or no Fairbank changes and there was no statistical difference when comparing radiographic criteria in the operated and nonoperated knee. Early results for partial lateral meniscectomy can be quite good; however, significant deterioration of functional results and decreased activity level can occur. Radiographic changes did not correlate with subjective sumptoms and functional outcome in our patient population. Our findings suggest that the functional outcome for patietns undergoing partial lateral meniscectomy may deteriorate with time and it may be helpful to counsel patients concerning long-term expectations.     

Meniscal allograft transplantation for symptomatic knee after meniscectomy of torn discoid medial meniscus: Report of three cases

In symptomatic discoid medial meniscus, partial meniscectomy is the principal treatment method and can yield promising short-term results. However, unlike the nondiscoid meniscus, discoid medial meniscus is frequently associated with horizontal cleavage tears, attributable to the presence of myxoid degeneration in the intrameniscal substance, in that it may potentially occur deteriorating long-term results because of re-tearing of remaining meniscus or secondary degeneration of cartilage of the medial compartment after meniscectomy. We experienced three rare cases of retear or secondary degeneration of cartilage of the medial compartment after meniscectomy for two patients with torn bilateral meniscus. Both patients were highly active young males. Meniscal allograft transplantation in complicated discoid medial meniscus was performed. At 2 years after meniscal allograft transplantation, clinical outcomes were improved with a normal range of motion. Orthopedic surgeons should recommend activity modification to prevent possible complicated injury of the discoid medial meniscus. Meniscal allograft transplantation may be an alternative option in highly active young patients undergoing complicated discoid medial meniscus to diminish pain, improve knee function, and prevent or delay degeneration.     

Advances in arthroscopic surgery

Removal of the whole meniscus from the knee has been shown to be associated with a high incidence of degenerative change. The degeneration is proportional to the amount of meniscus removed. After meniscal injury, retention of the meniscus in part (partial meniscectomy) or in whole (meniscal suture) is preferable. Replacement of a previously removed meniscus (meniscal transplantation) may be feasible in the future. Fifty patients had arthroscopic partial meniscectomies performed alternately by standard mechanical techniques or by electrosurgical techniques. The latter group was found to have less pain and swelling. Another 46 patients had meniscal sutures performed on one or more menisci. Twenty-one of these patients had a follow-up arthroscopy for recurrence of symptoms and only one meniscus had not healed. Another single patient had a meniscal transplant, and a follow-up arthroscopy six months after surgery revealed the meniscus to be largely intact.     

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.     

The degenerative effects of partial and total resection of the medial meniscus in dogs' knees.

An experimental effort to determine the degenerative effects in the articular cartilage of the knee joint caused by meniscectomy was performed by doing partial and total meniscectomies on the medial compartment of dogs' knees. Gross and microscopic pathological changes in teh articular cartilage were studied by sacrificing the dogs at intervals of three to ten months. Results indicated that meniscectomy is not a benign procedure, and the removal of a meniscus in itself can lead to degenerative changes in the knee joint. Partial meniscectomy leads to less severe degenerative changes with the degree of change directly related to the amount of meniscus removed. In total meniscectomies when meniscus regeneration occurred, the cartilage surfaces where the meniscus had regenerated were protected. The degree of degenerative change was directly related to the amount of fibrocartilage that remained absent. Therefore, the knee menisci function to protect the articular cartilages from degenerative damages, but the exact mechanism of this is unknown.     

Arthroscopic partial meniscectomy: a 12-year follow-up and two-step evaluation of the long-term course

The long-term results after arthroscopic partial meniscectomy of 119 patients with a mean follow-up of 12 years are presented in this study. The same series of patients had an earlier follow-up 4 years postoperatively. Thus, an evaluation of the actual long-term course and not only a single result after partial meniscectomy is presented. Arthroscopic partial meniscectomy is shown to be the definitive means of therapy for meniscal lesion of the knee joint; 91.7% of patients had an excellent or good result 4 years after surgery, and 78.1% rated excellent or good 12 years after surgery. Full recovery regarding ability to work and sports activity level was achieved in a very high percentage of patients. Early results were mostly representative and did not change significantly during the long-term course for the isolated meniscal lesion. The factor with the highest impact on long- term results was damage to the articular cartilage, which did not influence knee function for several years after surgery but became increasingly symptomatic over time after 5 years and more. Only 62% of patients with additional cartilage damage rated excellent and good 12 years after surgery, in contrast with 94.8% good and excellent results in patients with isolated meniscal tears. Similar observations were made for the untreated rupture of the anterior cruciate ligament.Arthroscopy 1998 Mar;14(2):136-42     

The long-term effects of hyaluronan during development of osteoarthritis following partial meniscectomy in a rabbit model

OBJECTIVE: The long-term effect of hyaluronan (HA) on meniscus remodeling and articular cartilage preservation was assessed during the development of osteoarthritis following partial meniscectomy in a rabbit model. DESIGN: Approximately 60% of the region of each medial meniscus of 20 rabbit knees was excised bilaterally. The left knee joint was treated with five weekly intraarticular injections of 0.3 ml of HA, beginning 1 week after surgery. The right control knee was injected with PBS on the same schedule. Six months after surgery, animals were killed and the medial menisci and tibial articular cartilage were evaluated morphologically, histologically and biochemically. RESULTS: Meniscal regeneration was observed as newly synthesized translucent tissue, and image analysis revealed that the amount of this tissue was significantly greater in the HA-treated menisci than in the vehicle-treated menisci. Safranin-O staining and image analysis revealed the increased presence of glycosaminoglycans in the HA-treated menisci relative to vehicle-treated menisci while vascularity and biochemical parameters (hydration, total GAGs and reducible collagen crosslinks) were statistically similar in HA- and vehicle-treated menisci. Gross morphologic grading with India ink revealed a trend for less deterioration of tibial articular cartilage in the HA group (P=0.09) while Mankin's score of the HA-treated tibial articular cartilage was marginally lower than that of the vehicle group (P=0.06). Biochemical assessments showed a trend for higher total GAGs concentration in the HA-treated articular cartilage when compared to the vehicle treatment group (P=0.06). CONCLUSION: The present study has demonstrated that following partial meniscectomy, treatment with hyaluronan can enhance meniscal regeneration and may inhibit articular cartilage degeneration as long as six months post surgery.     

Simple arthroscopic partial meniscectomy associated with anterior cruciate-deficient knees

Twenty-five patients with combined tears of the meniscus and anterior cruciate ligament in the same knee were evaluated for the results of a simple arthroscopic meniscectomy that preserved the meniscal rim. These patients, classified as "recreational athletes," were analyzed to determine their postoperative functional capabilities. Using the presence or absence of the pivot shift sign as the most important indicator of functional capability, we found that partial meniscectomy was effective in allowing patients to regain a high degree of normal functional ability and in permitting forward motion activities. However, all patients were left with an anterior cruciate-deficient knee that caused laxity in the anterior plane and frequently in the rotatory plane. Rotatory laxity markedly limits activities, and those patients unable to adjust to their instability are considering further surgery.     

Lateral meniscal variant with absence of the posterior coronary ligament.

We reviewed the cases of 3468 patients who had had arthroscopy of the knee between January 1976 and December 1988. Twenty-six patients (0.8 per cent) had a partial or a complete discoid lateral meniscus, and seven (0.2 per cent) had the Wrisberg-variant-type lateral meniscus. Of the seven patients, six had operative stabilization of the meniscus and one had a partial lateral meniscectomy because of an irreparable complex tear. Subjective, objective, and radiographic evaluations were performed on the patients who had had stabilization of the meniscus. According to the scale of Tegner and Lysholm, the result was excellent in four patients, good in one, and fair in one. None of the six patients had a tear of the sutured meniscus after an average follow-up of thirty-two months (range, twenty-four to forty months). Two patients had progressive symptoms attributable to osteoarthrosis, but the changes in the articular cartilage had been present at the time of the index procedure. None of the seven Wrisberg-variant-type menisci demonstrated a true discoid shape of the meniscus. We therefore classified this lesion as a lateral meniscal variant with absence of the posterior coronary ligament.     

Arthroscopic medial meniscectomy on stable knees

We reviewed 74 partial medial meniscectomies in 57 patients with stable knees, to assess the long-term functional and radiological outcome. The International Knee Documentation Committee score and the residual laxity were assessed in both knees. At the time of surgery the mean age of the patients was 36 +/- 11 years and the mean follow-up was 12 +/- 1 years. All had a limited medial meniscectomy. The anterior cruciate ligament was intact in all cases. The meniscal tear was vertical in 95% and complex in 5%. The posterior part of the meniscus was removed in 99%. A peripheral rim was preserved in all cases. After 12 years 95% of the patients were satisfied or very satisfied with their knee(s). Objectively, 57% had grade A function and 43% were grade B. The outcome correlated only with the presence of anterior knee pain at final follow-up. In the 49 cases of arthroscopic meniscectomy for which there was a contralateral normal knee there was narrowing of the 'joint-space' in 16% of the operated knees. There was no correlation between this and other parameters such as age or different meniscal pathologies.     

Future of 34 meniscectomies after bucket-handle meniscus tear: a retrospective study with a follow-up over 22 years

After a bucket-handle meniscus tear, a partial meniscectomy by arthroscopy is recommended, when a meniscal suture is impossible. Short-term results of meniscectomy after bucket-handle meniscus tear, without cartilage or ligament additional injury, are mostly excellent: pain and blocking disappear, return to sports activities is possible. The aim of this retrospective study is to follow a partial meniscectomy evolution with a long follow-up between March 1990 and April 1994, and a senior surgeon operated 34 meniscectomies for bucket-handle meniscus tear by 34 patients (29 male and 5 female) with a mean age of 31.7 years (16–52 years) at time of surgery. The bucket-handle meniscus tear had a traumatic etiology on a knee with no cartilage lesion. The functional results were assessed by IKDC subjective score (International Knee Documentation Committee) and ARPEGE score (Association pour la Recherche et la Promotion de l’Etude du Genou). These scores were obtained by phone call questionnaire in March 2014 with a mean follow-up of 22.7 years (20–24 years). In this study, patients were reviewed and got a clinical examination to determine the Lequesne score, a radiological knee assessment according to Ahlbäck classification and a weight-bearing teleradiography. With an IKDC mean score of 85.8 after surgery, we observed that 29 patients go back to sports activities with the same level as before injury. The level of sports activity, with a regular practice after a mean follow-up of 22.7 years, was the same as immediately after surgery or just the level under for 85.3 % of patients. With ARPEGE score, 48.5 % of patients had a global excellent result and 38.2 % had a global good result after a long follow-up. With a mean Lequesne score of 2.38, osteoarthritis of knee is still clinical minimal after meniscectomy at long term. The score was worse after external meniscectomy (EM) than after an internal meniscectomy (IM). 57.7 % of patients have osteoarthritis on X-rays. In our study, functional results after partial meniscectomy for bucket-handle meniscus tear are similar than in the literature. More than half of our patients, reviewed after a long follow-up, had radiological osteoarthritis of knee with a variable clinical result, but often minimal to moderate, intensity modulated by the lower limb axis.     

Effects of radial tears and partial meniscectomy of lateral meniscus on the knee joint mechanics during the stance phase of the gait cycle—A 3D finite element study

The purpose of the current study was to evaluate influences of radial tears and partial meniscectomy of lateral meniscus on the knee joint mechanics during normal walking by using computational modeling. A 3D geometry of a knee joint of a healthy patient was obtained from our previous study, whereas the data of normal walking were taken from the literature. Cartilage tissue was modeled as a fibril reinforced poroviscoelastic material, whereas meniscal tissue was modeled as a transverse isotropic elastic material. The realistic gait cycle data were implemented into the computational model and the effects of radial tears and partial meniscectemy of lateral meniscus on the knee joint mechanics were simulated. Middle, posterior, and anterior radial tears in lateral meniscus increased stresses by 300%, 430%, and 1530%, respectively, at the ends of tears compared to corresponding areas in the model with intact lateral meniscus. Meniscus tears did not alter stresses and strains at the tibial cartilage surface, whereas partial meniscectomy increased contact pressures, stresses, strains and pore pressures in the tibial cartilage by 50%, 44%, 21%, and 43%, respectively. Increased stresses and strains were observed primarily during the first ～50% of the stance phase of the gait cycle. The present study suggests that anterior radial tear causes the highest risk for the development of total meniscal rupture, whereas partial meniscectomy increases the risk for the development of OA in lateral tibial cartilage. Highest risks for meniscus and cartilage failures are suggested to occur during the loading response and mid‐stance of the gait cycle. In the future, the present modeling may be further developed to offer a clinical tool for aid in decision making of clinical interventions for patients with knee joint injuries. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1208–1217, 2013     

Need Room to Operate? Partial and Intentional Release of the Knee Medial Collateral Ligament for Medial Meniscal Surgery

Cutting the medial collateral ligament (MCL), even in part, seems counterintuitive. However, medial meniscal surgery is not always easy, and iatrogenic articular cartilage damage can be a complication of partial meniscectomy, meniscus repair, and/or allograft transplantation in a tight knee. Fortunately, partial tears of the MCL tend to heal, and most patients do tolerate iatrogenic, partial MCL tearing without negative long-term sequelae. However, rather than accidentally tearing the MCL during medial meniscal surgery, if you need room to operate, partially release the MCL.     

Die arthroskopische Meniskusteilresektion

OBJECTIVE: Excision of damaged meniscal tissue whereby the mechanical obstacles to joint movement are eliminated. As much functional, intact meniscal tissue should be retained as possible. Resection of only the bare minimum. INDICATIONS: Symptomatic, irreparable lesions of the meniscus due to trauma or degeneration. CONTRAINDICATIONS: Reparable lesions of the meniscus. Local skin affections. SURGICAL TECHNIQUE: Introduction of the arthroscope through an anterolateral or central portal. The instrument portal is positioned in accordance with the situation of the meniscal lesion to be treated. The tissue to be excised is either broken into fragments with different punches or resected en bloc. POSTOPERATIVE MANAGEMENT : Functional postoperative management without immobilization. Full loading on the leg. RESULTS: Very good and good clinical results can be achieved in the short and long term after arthroscopic partial meniscectomy. In a study by Burks et al., 88% of 146 patients with stable knee joints had a very good or good result 14.7 years after partial meniscectomy. 95% of 57 patients were satisfied or very satisfied with the result 12 years after partial medial meniscectomy. A degenerative meniscal tear, axial deformity, higher age, and anterior cruciate ligament insufficiency are factors associated with an increased rate of arthrosis in the long term.     

Fifteen-year follow-up of arthroscopic partial meniscectomy

From an original pool of 283 patients, 146 patients who had undergone arthroscopic partial meniscectomy an average of 14.7 years before were followed-up. Lysholm score, Tegner activity level, satisfaction index on a scale of 1 to 10, and standing anteroposterior and flexion weight-bearing radiographs of both knees, were obtained. A physical examination was performed on each knee emphasizing motion, swelling, and ligament evaluation. Radiographs were graded for degenerative changes for each knee. Each knee joint space was also measured in millimeters and compared, operative knee with unoperated knee. The unoperated knee had no injuries or surgeries and was used as a control. Patients were 83% male and 17% female; 78% had undergone medial meniscectomies, 19% lateral, and 3% both. There were 88% good and excellent results in anterior cruciate liagment—stable knees. The radiographic grade side-to-side difference showed the operative knee to be only a 0.23 grade worse than the nonoperative knee. Age at the time of meniscectomy was not found to be a factor. Male patients had better radiographic results than female patients, but not better functional scores. Medial meniscus and lateral meniscus results were not significantly different. Knees with a femoral-tibial anatomic alignment of >0° valgus compared with ≤0° and that had undergone medial meniscectomy had significantly better radiographic results. Patients with anterior cruciate ligament tears and meniscectomy did significantly poorer than stable knees with meniscectomy in regards to radiographic grade change, Lysholm, satisfaction index, Tegner level, and medial joint space narrowing.     

Articular cartilage changes following meniscal lesions. Repair and meniscectomy studied in the rabbit knee

A well-defined, longitudinal lesion in the avascular part of the medial meniscus of the right knee was made in 30 rabbits. After 3 months, the lesion was repaired surgically in 12 rabbits, was untreated in 12 rabbits, and a meniscectomy was performed in 6 rabbits. The articular cartilage was studied macroscopically and microscopically at 3-month intervals. Cartilage changes 3 months after meniscectomy were more pronounced than after meniscal repair or than in untreated lesions. However, meniscal repair did not reverse the cartilage changes.     

1310例侧膝关节半月板损伤关节镜下诊治效果分析

目的　分析关节镜下半月板损伤不同修复方法的效果 ,提出半月板损伤修复较适用方法。方法　随访 1310例侧膝关节半月板损伤镜下修复的患者 ,从发病年龄、损伤类型、镜下修复方法及效果进行分析 ,其中男性 880例 (90 9例侧 ) ,女性 374例 (4 0 1例侧 ) ,平均 2 5 5岁 ,平均患病时间半年。半月板缝合 6 8例侧 ,部分切除成形术 75 6例侧 ,半月板全切除 4 80例侧 ,6例儿童半月板损伤镜检确定后未行镜下处理 ,于镜检后石膏固定。结果　术后平均随访 4年 3个月 ,Lysholm评分 :半月板缝合术前 4 7 5分 ,术后 86 3分 ;半月板部分切除成形术前 4 5 1分 ,术后 84 0分 ;半月板全切除术前4 5 4分 ,术后 76 1分。 6例少年儿童半月板损伤 ,Lysholm评分术前 4 5 0分 ,术后 98 7分。三种治疗方法效果有显著性差异 (t=2 876 ,P <0 0 1)。结论　半月板损伤应在关节镜下行缝合或部分切除成形治疗 ,避免半月板切除 ;<14岁盘状半月板损伤需部分切除成形 ,半月板损伤非手术治疗可获得较好疗效     

MRI Evaluation of Isolated Arthroscopic Partial Meniscectomy Patients at a Minimum Five-Year Follow-up

Background The risk of radiographic knee degeneration after partial or total meniscectomy is well documented, but no prior study has employed cartilage-sensitive MRI technology to assess degenerative changes after meniscectomy. Hypothesis Arthroscopic partial meniscectomy results in early articular cartilage wear and subchondral bony degeneration, even in the absence of clinical symptoms, and these findings can be evaluated with cartilage-sensitive MRI. Study design Retrospective cohort. Methods Twenty-nine patients (ages: 15–40) who had undergone isolated arthroscopic partial medial or lateral meniscectomy with at least 5-year follow-up were evaluated. All patients had arthroscopically normal articular cartilage at the time of initial meniscectomy. Seventeen patients (18 knees) underwent partial medial meniscectomy (MM) and 12 patients underwent partial lateral meniscectomy (LM) with mean follow-up of 8.4 and 7.1 years, respectively. Follow-up evaluation included physical examination, outcome questionnaires, and cartilage-sensitive MRI examination with modified Outerbridge grading of articular surfaces. Results Outerbridge grades II–IV were noted in 64% of medial compartment joint surfaces in group MM knees versus 33% of lateral compartment joint surfaces in group LM knees. Abnormal cartilage surfaces (grades II–IV), subchondral sclerosis, and condylar squaring were all significantly more frequent after medial meniscectomy (p < 0.05). Groups MM and LM had no significant differences among outcome scores, which remained excellent in both groups. A significant negative correlation was found between the severity of cartilage wear and functional scoring in the MM group, suggesting that functional disability lags behind early MRI evidence of degeneration. Conclusions Despite optimal preoperative prognostic factors and excellent functional outcomes, MRI evidence of early articular cartilage degeneration was present in both partial medial and lateral meniscectomy patients at a minimum 5-year follow-up. Results support the use of cartilage-sensitive MRI as a noninvasive screening technique to evaluate cartilage changes after arthroscopic partial meniscectomy and may help to counsel the high-risk patient in regard to postoperative activity.     

Evaluation of small intestinal submucosa grafts for meniscal regeneration in a clinically relevant posterior meniscectomy model in dogs

Large meniscal defects are a common problem for which treatment options are limited. Successful meniscal regeneration has been achieved by using grafts of small intestinal submucosa in posterior, vascular meniscal defects in a dog model. This study investigates the long-term effects of a tibial tunnel fixation technique and a clinically based meniscectomy defect on meniscal regeneration using this model. Eight mongrel dogs underwent medial arthrotomy and partial meniscectomy. The dogs were divided into groups based on defect treatment: small intestinal submucosa (n = 4) or meniscectomy (n = 4). Dogs were scored for lameness by subjective scoring postoperatively, sacrificed at 6 months, and assessed for articular cartilage damage, gross and histologic appearance of the operated meniscus, amount of new tissue in the defect, and relative compressive stiffness of articular cartilage. Dogs in the meniscectomy group were significantly (P = .002) more lame than dogs treated with small intestinal submucosa. Small intestinal submucosa-treated joints had significantly (P = .01) less articular cartilage damage than meniscectomy joints. Small intestinal submucosa meniscal implants resulted in production of meniscal-like replacement tissue, which was consistently superior to meniscectomy in amount, type, and integration of new tissue, chondroprotection, and limb function during the study period. Small intestinal submucosa implants may be useful for treatment of large posterior vascular meniscal defects in humans. The tibial tunnel technique used for fixation may have clinical advantages and therefore warrants further investigation.