Meniscal Tears: Meniscectomy Versus Repair

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.

Fig. 15.1, Anteroposterior knee radiograph of a 23-year-old man 5 years after left lateral meniscectomy. Substantial lateral joint space narrowing of the left knee is noted.

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:

Surgeons may be most comfortable with their proficient technique of meniscectomy, which happens to yield positive short- and medium-term patient outcomes.
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.
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’.
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 ).

Fig. 15.2, The peripheral third of the menisci, shown in red, receives blood supply from the perimeniscal capillary plexus originating from the medial, lateral and middle genicular arteries.

Fig. 15.3, Arthroscopic view of vertical mattress sutures placed using the inside-out technique at the three different vascularity zones of the meniscus: (A) white-white, (B) red-white and (C) red-red.

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.

Fig. 15.4, Left: Longitudinal tear disrupts radial fibres while leaving intact circumferential fibres from anterior to posterior. Middle: Radial tear disrupts circumferential fibres from central to peripheral. Right: Vertical longitudinal tear of sufficient length to produce the bucket handle tear pattern.

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. ^,

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