Meniscal Repair with Anterior Cruciate Ligament Reconstruction




Introduction


Meniscus tears are commonly encountered in the setting of anterior cruciate ligament (ACL) injury. For decades, the importance of the meniscus was not recognized. Previously the standard treatment for meniscus tears was excision. While we have improved on returning patients to high-level activities after ACL injuries, posttraumatic osteoarthritis in the decades that follow reconstruction continues to be problematic. The meniscus is becoming increasingly recognized for its role in knee stability, dissipating forces across the femorotibial joint, and protecting the articular cartilage. Meniscus repair has been demonstrated to provide satisfactory outcomes at mid-term follow-up. It is important for surgeons to recognize injuries to the meniscus during ACL reconstruction (ACLR) and address tears that warrant treatment. Meniscal preservation should be of upmost importance in both preserving knee stability and preventing degeneration of the knee at long-term follow-up.




Epidemiology of Meniscus Tears in Anterior Cruciate Ligament Injury


Tears to the medial and lateral menisci frequently occur during acute ACL disruptions. Meniscus tears may also be observed during reconstruction in chronically ACL-deficient knees. Meniscal tears have been reported to be present in 41%–82% of acute ACL injuries and 58%–100% of chronic injuries. The incidence of meniscal tears increases with time between injury and reconstruction. The laterality of meniscal injury patterns appears to differ depending on the length of time between ACL disruption and reconstruction. Cipolla et al. demonstrated differences in meniscal tear patterns between acute ACL injuries and patients with chronic ACL deficiency. In a retrospective review of 1103 ACLRs, the authors attempted to define the natural history of meniscal injury in the setting of ACL disruption. They found that 59% of acute ACL injuries had lateral meniscal tears; medial meniscal tears were half as common (29%) in acute settings. The inverse was true in chronic ACL deficiency, as Cipolla reported a 42% rate of lateral meniscus tears and 74% rate of medial meniscus tears in chronically cruciate-deficient knees.


There appears to be certain patterns of meniscal tears that occur during ACL injury. Smith and Barrett prospectively described the location of meniscal tears found at the time of ACLR. They determined the posterior horn of either meniscus was involved in 94% of tears. Further, more than 99% of medial meniscal tears involved the posterior one-third of the meniscus. They also demonstrated that more than 60% of tears involved the peripheral zone of the meniscus and/or the meniscal-capsular junction. Tears have been reported to be longitudinal in nature in greater than 70% of cases. Further more, the incidence of both medial and lateral meniscal tears has been demonstrated to increase with delays in reconstruction. Therefore the most common meniscal tears that result from ACL injury would be a peripheral longitudinal tear located posteriorly and potentially involving the posterior horn.




Epidemiology of Meniscus Tears in Anterior Cruciate Ligament Injury


Tears to the medial and lateral menisci frequently occur during acute ACL disruptions. Meniscus tears may also be observed during reconstruction in chronically ACL-deficient knees. Meniscal tears have been reported to be present in 41%–82% of acute ACL injuries and 58%–100% of chronic injuries. The incidence of meniscal tears increases with time between injury and reconstruction. The laterality of meniscal injury patterns appears to differ depending on the length of time between ACL disruption and reconstruction. Cipolla et al. demonstrated differences in meniscal tear patterns between acute ACL injuries and patients with chronic ACL deficiency. In a retrospective review of 1103 ACLRs, the authors attempted to define the natural history of meniscal injury in the setting of ACL disruption. They found that 59% of acute ACL injuries had lateral meniscal tears; medial meniscal tears were half as common (29%) in acute settings. The inverse was true in chronic ACL deficiency, as Cipolla reported a 42% rate of lateral meniscus tears and 74% rate of medial meniscus tears in chronically cruciate-deficient knees.


There appears to be certain patterns of meniscal tears that occur during ACL injury. Smith and Barrett prospectively described the location of meniscal tears found at the time of ACLR. They determined the posterior horn of either meniscus was involved in 94% of tears. Further, more than 99% of medial meniscal tears involved the posterior one-third of the meniscus. They also demonstrated that more than 60% of tears involved the peripheral zone of the meniscus and/or the meniscal-capsular junction. Tears have been reported to be longitudinal in nature in greater than 70% of cases. Further more, the incidence of both medial and lateral meniscal tears has been demonstrated to increase with delays in reconstruction. Therefore the most common meniscal tears that result from ACL injury would be a peripheral longitudinal tear located posteriorly and potentially involving the posterior horn.




Meniscus—Basic Science


Blood Supply


A comprehensive understanding of the normal blood supply to the menisci is important when considering meniscus repair. The implications of blood supply are important when considering the ability of these structures to heal after injury. The menisci receive blood supply from the superior, middle, and inferior geniculate arteries. Arnoczky and Warren evaluated the meniscal capillary plexus networks using India ink arterial injection techniques in cadavers aged 53–94 years. They determined that the adult meniscus only has vascularity present in the outer 10%–30% of the medial meniscus and 10%–25% of the lateral meniscus. Further more, they also concluded that anterior and posterior horn attachments retained a greater blood supply compared with the central one-third of each meniscus in the axial plane. Additionally, there appears to be an age-dependent relationship regarding meniscal vascularity, with younger patients having vascularity penetrating further from the meniscal circumference. Petersen and Tillman demonstrated that the meniscus is completely vascularized at 1 year; they describe a decrease in vascularity in the central one-third of the meniscus in the axial plane from age 1 year to age 18 years from 100% to 33%, and a decrease from age 18 to 50 years from 33% to 25%. They also reported that anterior and posterior horns of both menisci were well vascularized (100%) regardless of age. Therefore microvascular studies suggest there is ample blood supply to heal repairs involving the anterior or posterior horns and the peripheral one-third of the meniscus. It may be more reasonable to suggest younger patients have a slightly larger portion of vascularized menisci and may benefit from meniscal repair.


Load Transmittance


The medial and lateral menisci play important roles in transmitting forces across the knee. Preservation of torn menisci by repair is important, as the menisci protect the knee’s articular cartilage. The menisci increase the congruency of the knee joint and account for differences in tibial and femoral geometric differences. The medial meniscus is responsible for 50% of the load transmission through the medial joint at full extension, and 85% at 90 degrees of flexion. The lateral meniscus transmits 70% of the load across the lateral joint in full extension, and 85% in 90 degrees of flexion. The meniscus protects the articular cartilage in both compartments. Knees without menisci carry a fourfold relative risk of osteoarthritis at long-term follow-up. Meniscus repair and preservation are of upmost importance to protect articular cartilage after ACL injuries.


Knee Stability


The role the medial meniscus plays in stabilizing the ACL deficient knee was first described by Levy et al. in 1982. The authors demonstrated that anteroposterior stability of the knee relied on both the ACL and the medial meniscus. The medial meniscus was determined to be an important secondary stabilizer in the ACL-deficient knee. Further more, this role as a secondary stabilizer has been associated with carrying increased load. In an ACL-deficient knee, Allen et al. demonstrated 52% and 197% increases in force on the medial meniscus with the knee in extension and 60 degrees of flexion, respectively. Increased load carried by the medial meniscus while stabilizing the medial joint in the ACL-deficient knee may partially explain the increasing incidence of medial meniscal tears as time from injury to ACLR increases. The lateral meniscus plays a small role in joint stability, as it is hypermobile compared with its medial counterpart.




Meniscal Healing After Repair


Conventionally, many consider the healing potential of the meniscus to be improved in the setting of ACLR. There are several biologically plausible explanations offered in the literature. First, patients undergoing ACLR are often subject to strict postoperative physical therapy regimens. This mechanically protective environment may be conducive to meniscal healing by avoiding excess stresses on the repair. Also, growth factors and progenitor cells introduced to the joint by drilling during ACLR may produce a rich biological milieu. Finally, meniscal tears that occur concurrently with ACL injuries may be more amenable to repair compared with isolated meniscal injuries that are more commonly associated with degenerative changes. While several single-center studies report improved healing in conjunction with ACLR, a systematic review with minimum 5-year follow-up detected no differences between clinically successful meniscus repairs performed with and without ACLR.


Meniscal “Healing”


When performing a meniscal repair, the objective is for biologic healing. Healing requires nutrient supply, and the meniscus is best supplied in the outer 25%–30% and in the anterior and posterior horns. Vascularity is also higher in younger patients. The most precise measure to assess meniscal healing after repair is by second-look arthroscopy. In a study by Cannon and Vittori, 22 patients underwent lateral meniscal repair and ACLR, and all of them had healed by the time of second-look arthroscopy (mean, 7 months). There were two medial meniscal tears (out of 15) that failed to heal, and one patient with bilateral repairs (out of 17 patients) that failed to heal the meniscal repair at a mean 7 months s/p ACLR and meniscus repair. Asahina et al. evaluated 98 meniscal repairs by second-look arthroscopy at a mean 16 months. They determined that 73 out of 98 (74.5%) had completely healed. They reported higher healing rates in medial repairs (78%) compared with lateral repairs (63%). Healing was most successful in the peripheral one-third of the meniscus, with healing rates exceeding 85%. The authors did report that 15% of patients without meniscal symptoms had incompletely or nonhealed repairs. In a second-look arthroscopy study by Tachibana et al. they identified a group of 38 patients who underwent clinically successful ACLR and meniscus repairs. The consented to second-look arthroscopy and hardware removal, and only 60.5% of the meniscal tears had completely healed; 23.7% had incompletely healed, and 15.8% had failed to heal. Noyes evaluated the influence of rim width and healing rates by second-look arthroscopy after meniscus repair and ACLR. He found that the central one-third repairs healed in 79% of cases, and this was with statistically inferior healing rates compared with the outer rim repairs.


The optimal result of a meniscus repair is a biologically healed, well-functioning meniscus that is able to protect the articular cartilage. This would ideally relieve pain and promote function. Studies suggest that patients who are considered clinically “successful” may have incompletely healed or nonhealed meniscal repairs in 15% to 39.5% of cases. Perhaps second-look arthroscopy should not be the gold standard in assessing the clinical success of meniscal repairs. What is unclear is how well a partially or nonhealed meniscal repair is able to adequately protect articular cartilage and prevent osteoarthritis. Magnetic resonance imaging (MRI) may be used to assess the status of the meniscus after repair. Menisci often heal with a fibrocartilaginous scar; these findings can be difficult to interpret on follow-up MRI studies. A healing criteria has been proposed by Henning: a scar or cleft less than 10% of the thickness of the meniscus is considered healed, 10%–50% residual cleft, and a scar or cleft greater than 50% of the meniscal thickness is considered not healed. There is discrepancy between clinical outcomes and meniscus healing similar to that seen in the second-look arthroscopy literature.


Repeat arthroscopic procedures and MRI studies do not correlate well with how patients are doing clinically and symptomatically after meniscal repair. The combination of repeat arthroscopic procedures addressing the repaired meniscus and patient-reported outcomes has become the most common metric to evaluate the success of meniscal repairs. The largest study in current literature evaluating meniscal repairs in conjunction with ACLR was performed by Westermann et al. A total of 235 patients from the Multicenter Orthopaedics Outcomes Network (MOON) were assessed at minimum 6-years follow-up after combined ACLR and meniscal repair; 14% had underwent subsequent arthroscopic procedures addressing the meniscus that had undergone repair at the index procedure. Median International Knee Documentation Committee (IKDC) scores of patients undergoing combined meniscus repair and ACLR in the MOON cohort were 47.1 at time equal to 0, 85.1 at 2 years, and 87.4 at 6 years, indicating minimal clinically important differences for IKDC scores (11.5 points ) had been reached.


Time from injury to meniscus repair in conjunction with ACLR has been investigated with different results. Barber et al. evaluated 46 patients with acute meniscal repairs and compared these with 19 patients with chronic meniscal repairs; he determined the failure rate was 15% for acute meniscal repairs, compared with 0% (0 out of 19) for chronic repairs. They concluded there was no difference in outcomes between menisci that were repaired acutely compared with chronic injuries. Conversely, Cannon and Vittori determined that meniscus tears that were repaired within 8 weeks of injury had improved healing rates. They evaluated 25 patients who underwent acute ACLR and meniscus repair and compared those with 43 patients who underwent ACLR and repair of chronically torn menisci. While the overall failure rates were similar (4% in acute vs. 9% in chronic), complete healing was significantly better with acute repair (73%) compared with chronic repairs (47%). Meniscal healing may be improved with acute repairs (<8 weeks); however it is difficult to say if this correlates with improved clinical symptoms, avoiding repeat surgery, or patient-reported outcomes.




Meniscal Tears To Repair


The indications for meniscal repair differ in patients with associated ACL disruptions compared with those with isolated meniscal tears. Noyes and Barber-Westin performed a systematic review that demonstrated about 26% of meniscus tears encountered during ACLR are treated with repair. Patients with acute ACL injuries are usually not distinctly symptomatic from meniscal tears. The indication for meniscal repair in the setting of ACLR, therefore, is directed at protecting the articular cartilage and restoring knee stability by meniscal preservation. Options for management of meniscal injuries in the setting of ACLR consist of leaving tears in situ without treatment, excision, repair, and meniscal allograft transplantation. When meniscal injuries are encountered during ACLR, it should be the foremost goal to preserve as much meniscus as possible. Posttraumatic osteoarthritis frequently follows ACLR. Several factors may contribute to the development of osteoarthritis after ACL injuries, including articular cartilage and meniscal injury. The menisci protect articular cartilage by dissipating stresses across the knee joint and providing anterior–posterior stability.


Leaving Meniscal Tears In Situ Without Treatment


Pujol and Beaufils performed a systematic review of meniscal tears left in situ at the time of ACLR. They reported failure rates between 0% and 22% (mean, 4.8%). Certain tears that are identified during ACLR can be left in situ without treatment and heal reliably. Cox et al. demonstrated patients with lateral meniscal tears left without treatment was a positive prognostic factor for patient-reported outcomes at 6-years follow-up after ACLR. The MOON group, a multicenter ACL study group, prospectively followed 194 patients with 208 meniscal tears left in situ without treatment for minimum of 6 years (123 lateral tears, 57 medial tears, and 14 both compartment tears). Lateral compartment tears had a mean length of 9.5 mm, and medial meniscal tears averaged 9.2 mm in length. They reported success rates of 98% in lateral tears and 94% in medial tears left in situ at the time of ACLR. They determined that younger age (<20 years of age) and tear length greater than 10 mm are instances where meniscal repair may be the favored treatment.


Indications for Lateral Meniscus Repair


Complete lateral meniscal tears greater than 1 cm should be repaired concurrently with ACLR. Lateral tears that typically follow acute ACL injuries are commonly longitudinal, peripheral, and extend into the posterior horn. Surgeons can expect greater than 85% success rates following meniscal repair in tears between 10 and 25 mm. In the MOON cohort, mean tear length for a successful lateral repair was 17 mm. Tears that went on to fail had a mean length of 19.6 mm, with no statistical difference between the groups. While peripheral one-third tears heal most reliably, central one-third tears when repaired produce good clinical outcomes in 81%–86% of cases. Outcomes following lateral meniscus repair are generally favorable.


Indications for Medial Meniscus Repair


The medial meniscus may be torn during acute ACL injuries; however it more commonly degenerates as the time from injury to reconstruction increases. Acute medial meniscal tears longer than 1 cm in length should be repaired. Tears involving the central one-third and the peripheral one-third of the medial meniscus have healing rates greater than 85% with repair. Tear length or location is not predictive of healing on the medial side. While clinical healing rates are similar to tears on the lateral side, Cox et al. found medial meniscal repairs to be an independent risk factor for worse outcomes after combined meniscal repair and ACLR. Further medial meniscal repairs have been associated with decreased joint space on x-ray; however, they fare better than meniscectomy in this regard.


When a repairable meniscus tear is encountered during ACLR, the surgeon must decide on the technique for repair. A systematic review of 19 studies showed similar success rates following meniscus repair with inside-out and all-inside techniques. They did find that incisional pain is more common with inside-out procedures. The review included patients with isolated meniscal repairs only and excluded cases of concurrent ACLR. Spindler et al. performed a prospective study evaluating consecutive ACLR and combined meniscal repairs with inside-out techniques between years 1991 and 1996. These patients were compared with a consecutive series of patients undergoing all-inside repairs concurrently with ACLR between 1996 and 1999. The authors concluded that success rates of meniscal repair were similar between the groups, at 88% and 89%, respectively. The success of inside-out and all-inside repairs was assessed by the MOON group at 6-years follow-up: all-inside techniques failed in 31 out of 208 (15%) cases, and inside-out repairs failed in only 1 out of 19 cases. Due to the low rate of failure in the inside-out group, the study was not powered to detect a difference between the techniques. Biomechanical studies have demonstrated similar mechanical properties between repair techniques. In the absence of high-quality studies with adequate power, surgeons should use the meniscal repair technique that best allows them to safely achieve a sound repair ( Table 101.1 ).


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Aug 21, 2017 | Posted by in ORTHOPEDIC | Comments Off on Meniscal Repair with Anterior Cruciate Ligament Reconstruction

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