The paradigm change in the operative treatment of meniscal injuries from meniscectomy to repair when possible has significantly transformed the management of these injuries. A better understanding of the important roles of the meniscus and the devastating consequences of complete or extensive partial meniscectomy, as well as the introduction of new techniques and sophisticated devices for meniscus repair, , , , may all play a role in this ongoing process. In addition, the literature shows that patients have better long-term patient-reported outcomes and better activity levels after meniscal repairs than after a meniscectomy. , ,
The type of meniscal tear, size of tear, location of tear, vascularity of the area, mechanism of injury, and chronicity of injury are all important characteristics that influence the reparability of meniscal tears. In addition, the patient’s age, function, goals, and expectations are also important factors to consider. ,
Meniscal repair can be performed with either an arthroscopic, open, or combined technique. The arthroscopic technique can be divided in to four categories: (1) the inside-out technique; (2) the outside-in technique; (3) the all-inside technique; and (4) a combined technique.
In this chapter we review the complications of meniscal repair in the setting of preoperative, intraoperative, and postoperative management.
Incorrect or Partial Diagnosis
Knee symptoms can be difficult to diagnose properly, especially in the presence of several findings in the patient’s history, clinical exam, and imaging. Meniscus pathology will not always be the patient’s pain source, and operative treatment with meniscus repair in these instances will lead to a dissatisfied patient and worse outcomes. ,
Prevention: The surgeon must correlate the patient’s complaints and symptoms with the patient’s history, physical examination findings, and imaging findings to rule out other possible etiologies for the patient’s symptoms. In terms of physical examination findings, joint line tenderness, a positive McMurray test, and mechanical catching or locking can be highly suggestive of a meniscal source of knee pain and dysfunction. Examination under anesthesia and the diagnostic part of arthroscopy are additional tools by which a surgeon can identify additional pathologies that can contribute to the patient’s condition and symptoms.
Recognition: No improvement in symptoms after the surgical intervention.
Management: Thorough evaluation for additional possible sources of knee symptoms.
Poor Patient Selection
Patient selection is a crucial element of successful outcomes after meniscal repairs. Preserving and repairing the meniscus should be reserved for tears with adequate healing potential. For example, a combination of a complex degenerative tear located in the avascular inner third of the meniscus in an older patient who has not had an acute injury has very limited healing potential, and will probably fail if repaired. Furthermore, a patient’s expected clinical outcome, daily function, and expected adherence to a specific postoperative rehabilitation protocol should also be considered when tailoring the optimal treatment for the patient. , , ,
Prevention: Appropriate evaluation of patients and assessment of both their characteristics and the characteristics of the meniscal tear. Meniscal tear characteristics should be evaluated by all tools available to the surgeon: history, physical examination, imaging, and the diagnostic part of the arthroscopy when an arthroscopy is planned.
Patient age. There is conflicting literature as to the effect of patient age on surgical outcomes after meniscal repair. On the one hand, meniscal tissue from patients over 40 years of age has less cellularity and decreased healing response than tissue from younger patients, suggesting a lower failure rate in young patients. However, on the other hand, it has been shown that the healing of repaired meniscal tears is poor in young patients (children and adolescents), despite better intrinsic healing potential. Furthermore, a large database study showed that older age is associated with decreased risk of subsequent meniscectomies after meniscal repair. One possible reason is the higher demands in daily living, occupation, and sports in the young population. Published evidence suggests , suggests that there is no significant difference in meniscal repair failures as a function of age. Therefore, age alone should not be considered as an absolute contraindication to meniscal repair, and should be taken into consideration with other factors.
Meniscal tear chronicity. Chronicity of symptoms could indicate a degenerative meniscal tear and osteoarthritic joint changes. A comprehensive arthroscopic evaluation of the meniscal tear tissue and chondral status could also indicate a degenerative etiology. It has been shown that the healing potential in the setting of chronic degeneration is low, , and repair is not recommended in this scenario.
Meniscal tear patterns. Favorable tear patterns with better healing potential are vertical longitudinal tears, , whereas less favorable patterns include complete radial, oblique, horizontal cleavage, and complex patterns. , , , Nevertheless, the usage of new techniques and instrumentation shows encouraging results in more challenging meniscal tears patterns, including complete radial tears , and meniscal root tears or avulsions, where repair is believed to aid in delayed progression of knee osteoarthritis. , Lastly, medial meniscocapsular tears (“Ramp” lesions), which have regained attention in recent years have shown good healing potential and clinical outcomes after repair ( Fig. 2.1 and 2.2 ).
Meniscal injury not indicated for repair. Small or partial-thickness tears can heal without intervention. In addition, stable peripheral tears can be treated with abrasion and trephination only (e.g., lateral meniscus tears near the popliteal hiatus). , , Overtreatment with unnecessary repair or over repair exposes patients to avoidable risks.
Medial versus lateral tears. There is no conclusive evidence as to whether or not the healing potential in the medial and lateral meniscus is different. Older reports suggested better healing potential in the lateral meniscus; however, more recent literature did not support these findings. Regardless of healing potential, it has been shown that lateral meniscectomy has more severe consequences than medial meniscectomy, and this should be considered in the decision-making process.
Vascularity. The outer third of the meniscus (the red-red zone) has the greatest healing potential owing to the presence of the perimeniscal capillary plexus. In contrast, limited healing capacity should be expected in the central and inner thirds, which are avascular and aneural. A distance of 0 to 2 mm of the tear from the menisco capsular junction has been identified as the greatest predictor for healing. Nevertheless, it has been shown that repairing tears in the avascular zones can also have good clinical outcomes in a high percentage of patients. ,
Instability. Knee instability jeopardizes meniscal repair integrity and healing. Biomechanical and clinical studies have proved the protective effect of regaining knee stability by anterior cruciate ligament reconstruction (ACLR) on meniscal repairs. Surgeons must not rely only on physical examination and imaging to rule out instability, but must also assess it by examination under anesthesia before performing meniscal repair. When instability is diagnosed, it should be addressed, preferably at the same time the meniscus is repaired.
Concomitant ACLR. Multiple studies have reported higher healing rates of meniscal repairs in conjunction with an ACLR in comparison to isolated meniscal repairs. , Growth factors and pluripotent cells released after bone-tunnel drilling, as well as favorable mechanism of injury secondary to instability in comparison to isolated meniscal injury mechanisms, are acceptable theories. ,
Recognition: No improvement or worsening of symptoms after the surgical intervention, failure of repair proven be physical examinations and imaging (magnetic resonance imaging [MRI], computed tomography [CT] arthrography).
Management: Thorough evaluation for of all aforementioned conditions. Repair failure because of poor patient selection will require a reoperation with partial meniscectomy.
Improper Repair Technique
The location, pattern, and size of tears should dictate the preferred repair technique. Improper choice of technique will result in more challenging procedure and cause unnecessary additional injury. ,
Prevention: Arthroscopic assessment of meniscal tear characteristic before choosing a repair technique. Preferable combinations are anterior horn tear with an outside-in technique and body/posterior horn tears with inside-out or all-inside techniques. Inside-out is still considered the gold standard.
Recognition: Technical difficulty performing the repair in a specific technique.
Management: Surgeons must be prepared to change repair techniques intraoperatively and consider hybrid repair in specific scenarios.
Improper Suture Material and Pattern
Using unsuitable suture material or suture pattern may result inferior biomechanical construct and lead to failure and poor clinical outcomes.
Prevention: Braided, nonabsorbable suture is the preferred suture for meniscal repair. Nonabsorbable suture allows stable and longer fixation, supporting the healing and remodeling process. Monofilaments increase the risk of cut-through. Vertical mattress suture pattern is biomechanically superior to horizontal configurations. It is recommended that sutures be placed in 3-to 5-mm intervals. , ,
Recognition: Postrepair assessment with arthroscopic probe will demonstrate compromised integrity and strength of the repair.
Management: Replace inappropriate sutures. Place vertical mattress configuration when possible.
Over- or Undertensioning of Sutures
Improper tension of sutures will compromise the repair construct. Undertension will result in an unstable construct, and overtension can damage meniscal tissue. In both cases healing capacity will be compromised. ,
Prevention: Surgeons should tighten sutures under visual control and consider use of instrumentation that facilitates tensioning the sutures (knot pushers, arthroscopic probe).
Recognition: Postrepair assessment with arthroscopic probe will demonstrate over- or undertensioning of the repair.
Management: Replace inappropriate sutures.
Iatrogenic Meniscal and Chondral Injuries
The manipulation of instruments inside the knee during arthroscopic meniscal repair may result in iatrogenic chondral or meniscal damage, especially in more challenging tear locations such as the posterior horn of medial meniscus, particularly in stiff or tight knees.
Prevention: Adequate visualization and access to the tear site is key to a successful intervention. Better visualization can be achieved with changing portal locations, adding additional portal, changing camera/instrumentation portal, changing to 70 degrees arthroscope, applying additional varus or valgus load to improve exposure, using cannulas, and performing percutaneous pie-crusting of the superficial medial collateral ligament (MCL) for medial-sided pathology , .
Recognition: Postrepair assessment of the knee joint and intraarticular structures, specifically meniscus and cartilage.
Management: Excessive meniscal injury may require debridement of injured tissue. Cartilage injury may require debridement or repair of unstable lesions. Microfracture or chondroplasty are also options.
Saphenous Nerve and Vein Injury
The saphenous nerve travels on the undersurface of sartorius, anterior to gracilis and superficial to semimembranosus, between layer 1 and 2 of the MCL. Medial-sided repairs are associated with injury to these structures, especially repair of the posterior horn of the medial meniscus.
Prevention: Surgeons must be familiar with the anatomy, using safety medial incisions through layer 1 of MCL and making sure sutures adhere to layer 2 (superficial MCL). Transillumination of the saphenous vein from the inferolateral portal is another technique described to help with saphenous nerve identification. The nerve is just posterior to the vein.
Recognition: Sensation deficits on the medial foot/leg, persistent medial-sided neuropathic pain, and positive Tinel sign.
Management: Neuropathic pain may require surgical exploration and excision of neuroma or release of nerve.
Peroneal Nerve Injury
The common peroneal nerve travels medially to the biceps femoris muscle and laterally to the lateral head of gastrocnemius. At the joint line it lies posterior and deep to the biceps femoris. Lateral-sided repairs are associated with injury to the common peroneal nerve, especially the more posterior the repair and the more divergent the sutures. , ,
Prevention: Surgeons must be familiar with the anatomy. Safe lateral zone for suture passage is between the iliotibial band anteriorly and the biceps femoris posteriorly. One must use a spoon or Henning retractor positioned by an assistant who can retrieve needles as they exit the posterolateral capsule. The procedure must be done with the knee flexed to 90 degrees, which further removes the peroneal nerve from the joint capsule.
Recognition: Motor deficits with ankle/toe dorsiflexion and sensation deficit in the lateral leg/dorsal foot. Electromyography may help with diagnosis and monitoring nerve function.
Management: Purely sensory deficits are usually treated nonoperatively. Exploration is indicated for complete neurapraxia that does not resolve. If significant laceration or injury is found, primary repair or grafting is indicated.
Popliteal Vessels Injury
The popliteal neurovascular bundle is in close proximity to the posterior horn of the lateral meniscus. It has been shown that penetrating posterior meniscal tissue in the direction of popliteal vessels without a depth limiter can result popliteal artery injury. ,
Prevention: Surgeons must be familiar with the anatomy. In case visualization of needle tips is not possible, mechanical restriction of penetration to meniscal tissue should be used.
Recognition: Excessive intraoperative bleeding should warrant a prompt assessment for possible popliteal artery or vein injury. This should include hemodynamic evaluation, distal pulses palpation, presence of late bruits or thrills behind the knee (as a manifestation of pseudoaneurysm), and vascular studies.
Management: Vascular consultation and intervention in case of popliteal artery injury. Fasciotomies should be considered if arterial injury leads to prolonged ischemia.
Lateral Genicular Artery Injury
The lateral genicular artery (LGA) crosses the knee capsule in proximity to the lateral meniscus at the level of the joint line, and lateral meniscal repair can cause injury to this vessel.
Prevention: Surgeons must be familiar with the anatomy. Adequate surgical exposure in cases of concern will enable preservation of this artery.
Recognition: Postoperative hematoma or hemarthrosis. Can potentially inhibit healing of meniscal repair because of disruption of local blood supply.
Management: Close follow-up in the initial postoperative period. In case of large hematoma and significant knee effusion, aspiration and compressive dressing are options.
Failure of Repair Construct
Meniscal repairs can fail for various reasons: incomplete diagnosis and additional pathology not addressed during surgery, contraindications to surgery (relative or absolute), compromised local healing capacity, or technical error while performing the repair (all of these were discussed previously). Additional reasons are hardware failure or migration (most relevant to all-inside devices, especially earlier generation rigid devices) and nonadherence to postoperative ambulation recommendations and the rehabilitation protocol, which will increase stresses on the repair construct before the healing process is complete. , , , , ,
Prevention: Flexible, suture-based devices are less prone to hardware failure and migration. Whenever using an implant-based device ensure proper deployment and stability of the implant. Rigid implants (darts, arrows) are more prone to fracture and migration and may cause chondral injury while displaced within the joint. Probing the meniscal repair after each device/implant is inserted can detect hardware problems.
Recognition: Postoperative mechanical symptoms, joint effusion, and pain. Imaging studies such as CT arthrography or MRI can confirm diagnosis.
Management: Revision arthroscopy which will include removal of failed implants and repair versus debridement and partial meniscectomy. Discomfort without evidence of construct failure can resolve spontaneously in some cases, whereas in other cases discomfort persists and requires construct removal.
Arthrofibrosis and Stiffness
Limited knee range of motion and pain with motion postoperatively are known complications of arthroscopic procedures in the knee.
Prevention: Postoperative rehabilitation protocol should be based on knee range of motion. Excessive immobilization time is not recommended.
Recognition: Postoperative extension or flexion lag with pain. Failure to meet rehabilitation milestones.
Management: Intensive physiotherapy and, in refractory cases, manipulation under anesthesia or arthroscopic lysis of adhesions can be considered.
Perimeniscal Cyst Formation
Local synovial fluid cysts can form adjacent to the repair and be accompanied by pain. Reasons for cyst formation can include irritation from the suture or implant material, failure of the construct, and more .
Prevention: Meniscal trephination and the number of sutures passed through the meniscus should be reasonable and not excessive. Use of nonabsorbable sutures may cause inflammatory reaction.
Recognition: Clinical evaluation confirmed with imaging.
Management: Treatment options include aspiration of cyst, arthroscopic or open resection of cyst, and consideration of meniscal rerepair or meniscectomy in cases of failure of repair construct.
Post meniscal repair infections can be superficial or deep. Deep infections are considered septic arthritis, and their incidence based on a large database in the United States is reported to be 0.17% to 0.30%. Delayed or improper management of an infected joint can have devastating results.
Prevention: Use of appropriate sterile technique during the arthroscopy. Avoidance of intraarticular intraoperative corticosteroid injections. Layered and meticulous surgical wound closure. Close follow-up in the immediate postoperative period.
Recognition: Clinical symptoms of infection (fever, local or joint tenderness, effusion, redness, warmth, swelling, wound dehiscence and drainage), laboratory supporting findings (elevated erythrocyte sedimentation rate, serum C-reactive protein, white blood cell count), knee aspiration with supporting Gram stain, cell counts, and culture findings.
Management: Sequential arthroscopic irrigation and debridement and intravenous antibiotics are the mainstay of treatment. The literature has shown that it is generally recommended to save the repaired meniscus in these cases and follow up closely.
Additional injury, joint instability, and an aggressive rehabilitation protocol which involves early full weight bearing and deep squats can all be reasons for recurrent tear at the repaired meniscus location.
Prevention: Guiding and educating patients and therapists on the importance of adhering to a proven postoperative rehabilitation protocol and avoiding high-risk activities. Addressing and treating joint instability during the meniscal repair or staging it.
Recognition: A brief period of improvement in symptoms followed by recurrence of symptoms. Supportive imaging studies: MRI, magnetic resonance arthrography, CT arthrography. Second-look arthroscopy is the gold standard.
Management: Arthroscopic meniscal repair versus partial meniscectomy.
Meniscal repair provides improved long-term outcomes and less severe postoperative radiographic degenerative changes when compared with partial meniscectomy. Complication rates as high as 18% have been reported for meniscal repairs; however, these rates may significantly differ based on patients and tear characteristics, repair techniques, concomitant procedures performed with repair, and more.
Accurate diagnosis, clear indications, and proper patient selection are all essential to avoiding complications. Once meniscal repair is considered, surgeons must rule out additional pathologies, specifically instability, which should be addressed during or close to the time of the repair (staged procedures). Repair technique should be tailored to meniscal tear characteristics, while avoiding iatrogenic injury to meniscus or cartilage. Additionally, an in-depth understanding of the anatomy of the knee is crucial for lowering the risks of neurovascular injury. Postoperatively, the rehabilitation protocol should protect the repair and allow for optimal healing while promoting protected joint motion.
Complications of meniscal repairs can be detected as early as during the initial arthroscopy and should be addressed at that time. Postoperatively, frequent follow-up will enable detection of additional possible postoperative complications. Diagnosis of complications will usually be based on the patient’s symptoms, physical examination, and imaging or additional studies. Diagnostic or revision arthroscopy may be required for specific complications.
Adhering to all the aforementioned recommendations will ensure optimal outcomes after meniscal repairs.