Introduction
Abundant research has elucidated the many biomechanical and functional characteristics of the meniscus, including its role in providing translational stability, rotational stability, proprioception and absorption of a significant proportion of load dispersed at the tibiofemoral joint. , , Thus with time orthopaedic surgeons have arrived at an increasingly cohesive mindset that the meniscus is a structure whose healthy native anatomy is of significant advantage to spare, or restore, when possible. Meniscectomy continues to play a role in the management of certain meniscal tear patterns. However, the indications are becoming increasingly limited to tears that are not amenable to repair. When comparing meniscectomy with meniscal repair, studies have reported that a larger proportion of intact meniscal mass is correlated with better long-term patient-reported outcomes, a higher rate of return to previous activity level and a decreased progression of degenerative changes of the articular cartilage surfaces of the knee. , The trend in the number of reported meniscal repairs among orthopaedic surgeons has continued to rise in the last 10 years, a reflection of the critical importance of the native meniscus.
This chapter reviews the present indications for meniscectomy versus meniscal repair, discusses the techniques used for the common meniscal tear patterns and reviews biomechanical and clinical outcome studies associated with these procedures. It also reviews some of the repair-enhancing measures that may be taken, including biological augmentation procedures.
The ‘Routine’ Meniscectomy
‘If it is torn, take it out, take it all out. Even if you just think it’s torn, take it out’. This is a quote that was excerpted from a paper by I.S. Smillie in 1967, reflecting the perspective of the meniscus at that time as a useless anatomical structure in the knee. The prevailing idea was that total resection was inconsequential apart from its early relief of pain and mechanical symptoms. Research has since clarified not only the native function of the menisci but also the consequence of removing part or all of either meniscus. Fast forward to today’s evidence-based understanding of the consequences of removing menisci. A study in 2015 evaluated patients 1 year after partial meniscectomy and demonstrated that these patients have a higher rate of radiographic evidence of osteoarthritis compared with either patients without meniscal tears or patients treated nonoperatively for their meniscal tears. To clarify, patients with surgically unaddressed meniscal tears had better outcomes than those treated with arthroscopic partial meniscectomy. Biomechanical changes occur after treating any tear patterns with a meniscectomy. For instance, although horizontal tears do not significantly alter the total contact surface area or contact pressures of the tibia and femur, meniscectomy involving debridement of a single leaflet reduces contact surface area and increases tibial and femoral contact pressures equivalent to resection of both leaflets. ,
Once considered a measure to accelerate the return to sport, partial meniscectomy at the time of anterior cruciate ligament (ACL) reconstruction may not empirically improve short-term outcomes after surgery for athletes. In a 2018 retrospective study of 426 primary double bundle ACL reconstruction cases, meniscectomy was found to reduce the rehabilitation protocol’s prescribed rate of return to running from 91% to 76%. It was also found to increase the mean time of return to running from approximately 6 to 11 months. Even in athletes who do functionally return to sport after meniscectomy, there can be radiographic evidence of degenerative changes to the knee ( Fig. 15.1 ). Brophy et al. demonstrated in 2009 that meniscectomy is correlated with a shorter than expected career in the US National Football League (NFL), and a literature review by Chahla et al. reported significantly increased incidence of full-thickness chondral defects and poorer objective performance measures in players with history of meniscectomy at the NFL combine from 2009–15.
It has been reported that in some patients nonoperative management of meniscal tears may be more effective in managing symptoms than a meniscectomy. , This puts into question the efficacy of the meniscectomy in some cases when no mechanical symptoms are present. A randomised, double-blind, sham-controlled trial with 146 patients between ages 35 to 65 demonstrated that clinical outcome measures of patients with partial meniscectomy were no better than patients who received a sham operation.
Despite some of the aforementioned consequences of the procedure, meniscectomy does play an important role as a reasonable operative management option for some meniscal tears. Specifically, in radial tears of the nonvascularised, most central zone of the meniscus, a meniscectomy may provide relief of symptoms when healing is less likely. Although studies may suggest revision meniscal repair or even re-revision repair as a viable option to save the meniscus, partial meniscectomy for macerated or degenerative tears that cannot be repaired can provide symptomatic relief to a patient with a failed meniscal repair.
The Delayed Trend Towards Repair
Beaufils and Pujol reviewed evidence since 2000 supporting meniscal repair over meniscectomy, while questioning the corresponding lag in rate of meniscal repairs reported by surgeons reflecting these persuasive findings. There are several explanations that may describe some of the potential motivations for resistance to embracing repair of the meniscus as the first-line consideration for symptomatic meniscus tears:
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Surgeons may be most comfortable with their proficient technique of meniscectomy, which happens to yield positive short- and medium-term patient outcomes.
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The learning curve to master meniscal repair techniques not only can be difficult but also has been changing and undergoing refinement, requiring regular adjustments to the literature-supported standards.
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Patients may receive pressure from coaches or others who recommend the operative management option with a speedier recovery. ‘I heard meniscectomy can get you back on the field faster’.
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Lastly, health economic factors related to patient insurance coverage can affect decision making. This may be interpreted as a motivation towards lower cost burden for the surgeon or fear of increased cost burden for postoperative therapies or work restrictions, which could impart additional cost to the patient.
The Decision for Athletes
Meniscectomy may be viewed as a simpler procedure that requires less time in the operating room, and some patients admittedly do report feeling their knee is normal or near normal at 10 years postoperative. However, they may still have underlying osteoarthritic changes to the knee that are not yet symptomatic. , In 2003 a multicentre French study followed 362 isolated medial and 109 isolated lateral arthroscopic meniscectomies at greater than 10 years postoperative. Even in the setting of overall knee stability, more than 22% of medial and 39% of lateral meniscectomies demonstrated joint space narrowing on x-ray examination at follow-up.
A 2016 literature review demonstrated a higher rate of return to sport for NFL athletes who underwent meniscectomy rather than repair, with the caveat that speed-dependent position players (i.e. receivers, running backs, defensive backs) were four times less likely to return to sport after meniscectomy. Additionally, a study of players participating in the NFL combine from 2009–15 evaluated the effects of prior meniscectomy on chondral defects and objective performance measures. There were 322 knees with history of previous meniscectomy that qualified for evaluation. Prior meniscectomy heavily correlated with full-thickness chondral defects, which in turn also correlated with significant worsening of performance measures at the combine.
A 2019 systematic review demonstrated a rate of return to preoperative level of sporting activity from 81% to 89% after meniscal repair, with another study showing a mean time to preoperative level of performance of 10.4 months for 45 elite athletes. Rate of return to sport was greater after meniscectomy than repair, with most athletes returning to sport competitions between 7 to 9 weeks. During the early return period, 69% of knees after lateral meniscectomy and 8% after medial meniscectomy experienced effusions or ongoing joint-line pain. Given the desire to return to competition weighed against the popularly described long-term consequences of meniscectomy, athletes in particular are faced with a difficult decision on course of management and should be presented with accurate expectations for short-, medium- and long-term outcomes.
Indications for Meniscal Repair
The biomechanical data are consistent across the board in favour of a meniscal repair over meniscectomy in most settings. In addition, a 2016 US-based projection of cost effectiveness comparing meniscectomy with meniscal repair suggested lower overall long-term cost associated with meniscal repair than with meniscectomy. However, it is important to also consider the patient clinical outcomes of pain, functionality scoring, risk of nonhealing, time of the season and potential need for a subsequent operation. Nonhealing may result in ongoing pain, mechanical symptoms or a recurrent operation that entails additional surgery-associated insult and risk of complication.
Therefore the risk of nonhealing is a major factor in the decision to repair a torn meniscus. Tear location, tear pattern, traumatic onset versus degenerative onset and concomitant ligamentous injuries are all important considerations when evaluating potential healing capacity.
Traumatic Versus Degenerative Tears
Meniscal tears can be classified as traumatic or degenerative. Traumatic tears tend to occur in an event in which forces are exerted on the knee that supersede the physiological stability of the meniscus. Traumatic tears often occur in the setting of concomitant ligamentous knee injury. By contrast, degenerative tears are almost always horizontal cleavage or complex tears, which may be often accompanied by osteoarthritic changes to the tibiofemoral joint. , Although traumatic meniscal tears that are symptomatic are considered for operative management, nonoperative management entailing use of nonsteroidal antiinflammatory medications and physical therapy has been shown to improve pain and mechanical symptoms in the case of degenerative meniscal tearing. , Given the less predictable outcomes associated with partial meniscectomy for degenerative meniscal tears, nonoperative management is recommended as the first-line approach for managing symptoms related to degenerative meniscal tears.
Concomitant Ligamentous Injuries
Two theories describe the mechanism leading to improved meniscal repair outcomes in the setting of concomitant ACL injuries. One suggests that the vulnerability of the meniscus is due to increased anterior tibial subluxation at the tibiofemoral joint on rupture of the ACL, whereas a meniscus that tears in isolation was otherwise vulnerable to tearing in its native disposition independent of ligamentous instability. According to this manner of thinking, restoring anteroposterior stability via ACL reconstruction theoretically can address the meniscal vulnerability. The second theory explains the improved meniscal repair outcomes in the setting of ACL reconstruction as a function of releasing growth factors and pluripotent cells that are accessed in the bone marrow at the time of initial injury and during bone tunnelling for ACL graft placement.
It is a well-documented pattern that repair of meniscal tears associated with ACL reconstructions yields better patient outcomes than repair of isolated meniscal tears. , , However, there are also methods described to enhance meniscal repair and provide biological augmentation to parallel the outcomes seen in the setting of concomitant ligamentous injury, which are discussed later in this chapter.
Vascularity of Torn Region
The location of a meniscal tear has been demonstrated in numerous studies to be consequential in its capacity to heal. This is assumed to be in large part because of the gradation of decreasing vascular supply extending from the periphery to the central zone of the menisci. The central two-thirds of the meniscus has historically been at highest risk for nonhealing because it lacks both vascular and neural supply. By contrast, the outer third of the meniscus receives a blood supply from the perimeniscal capillary plexus originating from the medial, lateral and middle genicular arteries, which is thought to explain the increased healing capacity of region, commonly known as the red zone ( Fig. 15.2 ). However, more recent data demonstrates improved meniscal repair outcomes regardless of tear zone. A 2019 study with 173 patients reported significant improvements on subjective outcome measures regardless of the meniscal tear zone, including the white-white zone ( Fig. 15.3 ).
Common Tear Patterns
The meniscus tear pattern has additionally correlated with healing rates. A vertical tear statistically demonstrates the highest likelihood to heal, most obviously when present in the periphery with a concomitant ACL rupture. This finding was affirmed by Espejo-Reina et al. analysing more than 2000 patients with meniscal tears. Radial, oblique and horizontal cleavage tears all by definition incorporate the avascular central zone of the meniscus and have historically correlated with lower healing rates. An increased length of the tear has also been described to correlate independently with a decreased rate of healing, both in an isolated setting and in the setting of concomitant ACL injury. In particular, when sufficient tear length of a vertical tear results in a bucket handle pattern that allows for the torn fragment to flip on itself, a worse healing rate has been observed. ,
Vertical Tear
A vertical longitudinal tear occurs when the more superficial radial fibres of the meniscus are disrupted and the deeper longitudinal fibres are left intact. This creates a tear path that is tangential to the curvature of the meniscus ( Fig. 15.4 ). When it is sufficiently long, the tear can flip on itself in a bucket handle fashion (see Fig. 15.4 ), often protruding into the intercondylar notch, predisposing patients to more pronounced mechanical symptoms. Repair should be strongly considered, knowing that a debridement of the vertical tear can result in up to a threefold increase in load absorbed at the articular cartilage surfaces. This increased tibiofemoral load may result in downstream chondral degenerative change.
Operative Management for Vertical Tears
Vertical tear patterns are often amenable to arthroscopic repair with sutures. In a study of 194 meniscus tears (169 classified as vertical longitudinal) in the setting of ACL tears, 96.8% of tears less than 10 mm did not require a recurrent operation at more than 6 years postoperative. Of tears greater than 10 mm, 88.5% required no recurrent operation at more than 6 years postoperative.
The preferred suture pattern is the vertical mattress technique, which has been reported to provide superior biomechanical stability to the horizontal mattress. Sutures should be placed every 3 to 5 mm along the length of the tear. Options for arthroscopic approach include the more classically used inside-out technique and the all-inside approach. Functional outcomes, postoperative pain and documented complications remain consistent overall between these two techniques. , These outcome measures hold true for bucket handle–specific pathological conditions. Biomechanical testing has shown no difference in stability between all-inside and inside-out techniques for these repairs. In addition, patients experience no difference in short- and medium-term outcomes between these two techniques. Given these findings, selecting the appropriate technique should entail consideration of the accessibility and the surgeon’s preference and familiarity with each available technique.
Horizontal Cleavage Tear
Horizontal meniscal tears leave intact the circumferential meniscal fibres from anterior to posterior while creating a horizontal separation that gives rise to a superior and inferior leaflet. This dual-leaflet pattern can be seen in Fig. 15.5 . Meniscectomy involving one leaflet may resolve mechanical symptoms, but tibiofemoral contact pressures resemble those of a dual-leaflet resection, whereas in the biomechanics laboratory, repair of horizontal cleavage tears restores tibiofemoral contact pressures to normal or near normal levels. Horizontal tears were once thought to have too little healing capacity to undergo a repair, so either nonoperative management or meniscectomy was the recommended management option. However, in response to abundant research demonstrating the impacts of meniscal deficiency and the subsequent risk of progression of osteoarthritis, attempts have been made to preserve both leaflets of the horizontal tear and restore native meniscal anatomy, particularly in younger patients. The rate of successful healing in the younger population is similar to that of other tear patterns, contrary to historical assumptions about the horizontal cleavage tear. However, the data do suggest a negative correlation between age and success rate when repairing this specific tear pattern. Most often, horizontal tears in patients older than 50 years can be classified as degenerative. Meniscectomy for patients with degenerative tear patterns demonstrates unfavourable outcomes compared with patients whose tears are more likely to be traumatic. ,
Operative Management for Horizontal Cleavage Tears
Despite a historical tendency to perform partial or subtotal meniscectomy in patients with complex horizontal cleavage tears, even these tears are showing strong evidence in favour of repair. Introducing a horizontal cleavage tear pattern in the biomechanics laboratory results in a 70% increase in contact forces between the tibia and femur. Subsequent repair restores the contact pressure to with 15% of baseline at all angles of knee flexion. Meniscectomy significantly increases contact pressures at all angles of knee flexion. Particularly in young patients, repair of complex horizontal tears mimics outcomes of other tear patterns. One study demonstrated a 91% rate of return to previous level of sporting activity after repair combined with partial meniscectomy of complex horizontal meniscal lesions in young athletes.
Radial Tear
Radial tears of the meniscus disrupt the circumferential meniscal fibres (see Fig. 15.4 ), and these tears are often associated with ACL injuries or multiligamentous injuries to the knee. These specific tears most often occur in athletes and other highly active individuals. When radial tears disrupt the meniscus fully, there is a dramatic increase in tibiofemoral contact pressures. This has been described to be functionally and biomechanically equivalent to a total meniscectomy. , When left surgically unaddressed, knees with radial meniscal tears have been described to rapidly develop tibiofemoral osteoarthritis. Radial meniscal tears, which are most commonly found in the posterior horn of the medial or lateral meniscus, typically cause pronounced mechanical symptoms in addition to joint-line tenderness and posterior knee pain with deep squatting. ,
Operative Management for Radial Tears
Radial tears that extend 60% of the distance or less from the centre of the meniscus may be candidates for meniscectomy when symptomatic, because tears of this magnitude may not cause significantly increased tibiofemoral contact pressures. When radial tears extend to 90% of the meniscal thickness, the contact pressures at the tibiofemoral joint are more severely increased, and repair or staged meniscal transplant should be considered. Further research is warranted to clarify contact pressures with radial tears extending between 60% and 90% of the meniscus. In young individuals, in an effort to prevent the progression of osteoarthritis, primary repair should be considered. , Operative treatment options for radial tears include meniscectomy, meniscal repair and meniscal allograft transplant. Given the relatively high risk of advancement of osteoarthritis, repair should be considered for larger radial tears. This can be accomplished using all-inside, inside-out, or transtibial techniques. , In a systematic review of six studies enrolling 55 total patients with arthroscopically repaired radial meniscal tears, International Knee Documentation Committee (IKDC) scores increased from 57 preoperatively to 81.6 to 92 postoperatively. Four studies incorporated a second-look arthroscopy, and the majority demonstrated healing with no serious complications, consistent with outcomes for other tear patterns. A two-tunnel transtibial technique for repair of radial tears has demonstrated equivalent outcomes to inside-out repair of vertical longitudinal tears.
Meniscal Repair With Sutures: Techniques
There are four main approaches to repairing meniscal tears with sutures: all-inside, inside-out, outside-in and transtibial (radial and root tears). These techniques are reported to be applicable in various scenarios, and the literature often suggests equivalent clinical or biomechanical outcomes. However, it is still advantageous for a surgeon to be familiar with the various techniques in order to be adaptable to the variety of different pathological conditions seen with meniscal injury.
Diagnostic Arthroscopy
Diagnosis of the tear is confirmed visually through the arthroscope at the time of surgery. A hook probe is used to verify the location of the tear and quality of the meniscal tissue. Standard anteromedial and anterolateral portals are used with the knee in approximately 30 degrees of flexion. Additional portals can be made as necessary for repair accessibility. Using a shaver, the outer and inner parts of the meniscus are refreshed as necessary. , Meniscocapsular adhesions are released as indicated for proper reduction of the tear.
All-Inside Repair
Although the inside-out technique remains the gold standard for the majority of meniscus tears, the all-inside approach has been steadily increasing in popularity and is continually being refined. A 2017 study demonstrated equal healing rates, complications and functional outcomes between all-inside and inside-out approaches for isolated meniscal repairs. Although still warranting further study, there may be indications for all-inside technique over the inside-out technique, such as the all-inside vertical mattress suture technique, which has shown biomechanical stability superior to the inside-out horizontal mattress suturing of radial meniscal tears in a porcine model. This study did not take into account the larger suture holes because of device insertion and did not include comparison with the two-tunnel transtibial approach, which has also demonstrated stability superior to horizontal repair of radial tears in the biomechanical laboratory. An additional advantage to the all-inside technique is the potential decreased risk for minor vascular injury, exemplified by the relatively higher risk of lateral genicular artery obliteration with extraarticular knots tied during inside-out repair of lateral meniscus tears.
All-inside technique
The senior author describes the all-inside technique using the FAST-FIX (Smith & Nephew, London, UK), which allows the deployment of sutures that are seeded through an outer meniscal button to be self-retrieved and secured in the joint using a pretied knot. These devices can reproduce the vertical, horizontal or oblique mattress suture pattern.
Inside-Out Repair
The inside-out technique is a method that passes sutures from inside the knee perpendicularly across the torn portion of the meniscus and out of the joint, where sutures are tied against the joint capsule. It is considered the gold standard for meniscal repairs and usually is also the least expensive technique. Advantages include the ability to place a greater number of sutures; the fact that smaller holes are created for passage of suture through the meniscus, leading to decreased risk of tear propagation; and the absence of bulky interference because of an intraarticular device. , Reasonable indications include vertical longitudinal tears, , , radial tears , , and horizontal cleavage tears. ,
Inside-out technique
Repair of the lateral meniscus uses an oblique incision made over the lateral joint line, following the posterior border of the iliotibial band extending to Gerdy tubercle. A medial meniscal repair uses an oblique vertical incision made from the adductor tubercle to the posterior medial tibial plateau. Dissection to the joint capsule is performed, while taking care to protect the saphenous nerve and other neurovascular structures. The surgical interval for a medial meniscal repair extends to the posteromedial joint capsule anteriorly, the medial gastrocnemius posteriorly and the semimembranosus inferiorly. For a lateral approach, the incision is made through the iliotibial band (ITB) approximately 5 mm anterior to the posterior margin of the superficial ITB layer and extending down to Gerdy tubercle. The surgical interval is created via careful dissection through the distal ITB and is bordered by the posterolateral joint capsule anteriorly and the lateral gastrocnemius posteriorly. The surgeon passes sutures across the tear and out of the joint at the site of posteromedial or posterolateral dissection. Sutures are then tied over the joint capsule ( Fig. 15.6 ).
