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Knee arthroscopy

    Overview

    Professional Guidelines Included
    Learn the Knee arthroscopy surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Knee arthroscopy surgical procedure.

    Knee arthroscopy was first introduced into the UK in the 1970s and it has now become one of the most versatile and successful of all orthopaedic operations. The key is identifying which patients would benefit from arthroscopic surgery as a diagnostic tool or as part of a reconstructive procedure. With the advent of MRI diagnostic arthroscopies are becoming less frequent.
    With the development of techniques and technology more and more knee procedures are performed arthroscopically which traditionally would have been performed as open procedures. It is now for example very rare to perform meniscal surgery as an open procedure, and the same can be said of ACL and PCL reconstruction surgery. New techniques in cartilage repair have also evolved to become arthroscopic procedures, often leading to reduced recovery times.




    Indications


    Indications for surgery
    With the advent of MRI diagnostic arthroscopy has become a much less common procedure. The diagnosis is usually identified through examination and imaging prior to arthroscopy and consent for the possible definitive procedure is obtained. The exceptions to this include small chondral defect, plicas, and small soft tissue loose bodies which can be missed on MRI.
    Arthroscopy has largely replaced open procedures for common knee procedures including meniscal resection and repair,ACL and PCL reconstruction surgery, synovial biopsy and synovectomy, and removal of loose bodies. Some cartilage procedures are performed arthroscopically such as micro fracture and OATS.
    Symptoms & Examination
    Mechanical symptoms of the knee should be considered such as true locking, clunking and symptoms of instability. Meniscal tears often present with joint line pain but underlying osteoarthritis should be assessed for prior to arthroscoping non traumatic meniscal tears. The pain from OA is often a constant dull ache rather than the shape pain associated with a loose body or displaces meniscal fragment. Patients with ACL tears describe episodes of instability when performing pivoting type exercise such as changing direction when running. When treating patellofemoral pain try to identify symptoms of subluxation and maltracking. In the awake patient you can better examine for patella matracking by looking at the movement of the patella in active extension.
    Careful examination of the knee is an imperative before embarking on arthroscopy. Assess both active and passive range of movements as well as palpate for joint line tenderness and a possible step off of the articular margin. Ligament examination should be performed in clinic but can usually be better assessed in the anaesthetised patient. When examining for ACL tears it is important to perform a lachman test as well as an anterior draw in the presence of a partial single bundle rupture.
    Imaging
    Plain X-rays are still the first investigation of choice for knee disorders. AP and Lateral weight bearing views are essential for identifying joint space narrowing and skyline patella views for patellofemoral issues.
    Rossenberg views performed as a PA radiograph with weight bearing and 45 degrees flexion is more sensitive than standard weight bearing radiographs for the detection of joint space narrowing.
    Magnetic resonance imaging, with its multiplanar capabilities and excellent soft-tissue contrast, has established itself as the leading modality for noninvasive evaluation of the knee. It is possible to evaluate a wide range of anatomy and pathology varying from ligamentous injuries to articular cartilage lesions.
    Currently, most clinical evaluation of the musculoskeletal system is performed at intermediate field strengths of 1.5 T or lower. High field systems, like 3.0 T, are now becoming increasingly available for musculoskeletal imaging. The most notable advantage includes an increased signal-to-noise ratio (SNR) which can lead to a shorter imaging time or improved image resolution. The increase in resolution and visualization of anatomy and pathology provide the advantage of improved preoperative planning.
    The ligamentous structures of the knee joint have been shown to be better visualized at 3.0 T when compared with lower field imaging. 3.0 T imaging also offers the possibility of delineation of fine detail. Articular cartilage anatomy has been demonstrated to be displayed with enhanced visibility while meniscal pathology obtained at 3.0 T has been shown to allow for better clinical assessment as demonstrated by the superior sensitivity. Bone marrow edema has also been demonstrated to be seen with greater resolution and detail providing for increasing diagnostic accuracy of knee joint pathology.
    Contraindications
    Traditionally arthroscopic debridements have been used for the treatment of osteoarthritis but recently has become labelled as a procedure of limited clinical value. Evidence has shows inconsistent results with minimal short term benefit. Similarly the practice of excising degenerate meniscal tears is becoming controversial and shown to have limited clinical benefit.
    In the presence of septic arthritis or an infected prosthesis arthroscopic synovectomy can be performed but DAIR (debridement antibiotics and implant retention) procedures are more adequately performed as an open operation.
    General contraindications include the presence of blood clots, skin plaques or broken skin over the port sites, local infection and medical fitness issues.

    Setup

    Operation

    Examination under general anaesthetic is first performed. Look for ligament laxity and range of movement. Check for collateral ligament instability perform a Lachman test and anterior draw. Rotational instability can be checked for more accurately under anaesthetic and before performing an ACL reconstruction it is important to perform a pivot shift test and DIAL test for associated PLC injury.

    An above knee tourniquet is applied with a lateral support positioned to allow the surgeon to abduct the leg and flex as required. The lateral support is used to lean the thigh against to help open the medial compartment.

    The leg should be prepped and draped to allow posteromedial or posterolateral ports if required.
    The patella and patella tendon is marked as well as the joint line.
    The knee initially is flexed to 90 degrees and in this position the anterolateral port is made 3 mm above the joint line and 2mm lateral to the patella tendon. A low port allows a good view of the posterior horn of the medial meniscus but too low risks damage to the anterior horn of the lateral meniscus. A vertical or horizontal incision can be used.

    The trocar is then inserted with the knee flexed 30 degrees and aiming under the patella, towards the notch.

    Diagnostic arthroscopy is performed using a 30 degree arthroscope. Angled scopes are required because the bony structure of the knee allows the arthroscope to be positioned only in certain positions. The angled scope allows the surgeon a greatly increased view within the joint. Rotating the scope will show a series of views angled at 30 degrees from the axis of the scope.

    Initially view the patellofemoral joint by turning the camera to look proximally.
    The patellas’ articular surface(1) should be visualised as should the femoral trochlea (2).
    If formal assessment of patella tracking is required then this is best assessed viewing though a superolateral port.

    To gain access to the medial compartment follow the medial articular border of the medial femoral condyle as the knee is allowed to hang over the side of the table. Avoid getting stuck in the medial gutter.

    The medial compartment can be opened by applying a vagus force against the lateral support with the knee flexed to 30 degrees.
    In very tight knees a needle can be used to make perforations in the MCL to help open the medial compartment. This can be useful when performing posterior horn tear repairs.

    The knee is then placed in a figure of four position to enter the lateral compartment.
    Visualisation of structures in the knee can be achieved in several ways. Advancing or withdrawing the scope will show structures in front or behind your original view. Remember the 30 degree view means advancing the scope will not be in the same direction as the view.
    Angling the scope will change the direction of the view as well as rotating the scope. It is also possible to change the view by moving the joint while leaving the arthroscope in the same position. this manoeuvre can also aid in checking for patella tracking at various degrees of flexion.

    Going back into the medial compartment the medial portal is made.
    A needle is inserted through the antero-medial skin. In the case of a posterior third medial meniscal tear it must be remembered that the handheld instruments need to reach under the femoral condyle. Therefore the portal must be as low and midline as possible. The needle must therefore emerge 2mm above the menisco-capsular junction. This differs from the portal for a lateral meniscal tear which will need to be higher in order to pass over the tibial eminences. In the case of both medial and lateral meniscal tear the surgeon may choose to make the portal vertical to allow extension (as made under direct vision this reduces the risk of iatrogenic anterior horn injury).

    A low portal close to the patella tendon allows good instrumentation of the posterior horn of the medial meniscus. A higher portal is required for the lateral meniscus so the instrument can pass over the tibial spine. A more medial portal can be used for the patellofemoral joint.

    The posterior capsule can be viewed by passing the scope through the notch lateral to the PCL. This can be useful to identify RAMP lesions (a menisco-capsular separation of the posterior horn of the medial meniscus).
    Further portals can be used to view the posterior capsule or for instrumentation.
    Posteromedial portal: placed 1cm above the joint line, behind the MCL, risks damage to the Saphenous nerve but allows views of the posterior horns of menisci and PCL.
    A Posterolateral portal: placed 1cm above the joint line, between LCL and biceps tendon risks the common peroneal nerve and allows views of the posterior horns of menisci and PCL.
    The posteriolateral portal: is rarely used other than when performing an “outside-in” technique, for example during a lateral meniscal repair.

    In this case there was a loose body anteriorly at the notch which was removed.
    When looking for loose bodies make sure the whole of the supra patella pouch is viewed, excising any plicas to aid the view. Also explore the gutters especially the lateral gutter down to popliteus as loose bodies often hide there.

    In this case the body was fixed to the synovium so it was freed with a shaver.

    For larger loose bodies an artery clip can be useful rather than an arthroscopic grabber.

    Once the loose body was removed a good view of the ACL was obtained.
    The ACL can be probed to check for integrity but look for the femoral attachment footprint. A Lachman test and anterior draw can be performed while looking at the notch to assess for functional stability.

    The arthroscopy wound can be closed with steri-strips, suture or left open. The knee is infiltrated with 0.25% Bupivacaine and dressings applied. a wool and crepe dressing is then applied to reduce postoperative swelling. Stronger concentrations of local anaesthetic should not be used as this can be toxic to articular cartilage.

    Post Operative

    The patient is mobilised fully weight bearing and allowed home as a day case. TED stockings are used until mobility is regained to reduce the risk of thromboembolism. The dressing are reduced after 24 hours and the sutures removed after 2 weeks. Routine analgesia is used but consider avoiding NSAIDS when performing cartilage repair. The main risks following arthroscopy is that of developing infection and septic arthritis which is thankfully rare. Port site problems can occur with fistulas and chronic discharge which usually settle with conservative treatment. Chronic pain can occur at the port sites as a result of injury to the infra patella nerve or irritation and fibrosis of the fat pad. This can be a troublesome problem which is difficult to resolve. Nerve injury can be treated with desensitisation exercises or denervation. Fibrosis of Hoffa’s fat pad usually settles with the help of the physio or if inflamed with steroid injections.

    Recommended Reading

    Traditionally arthroscopy was used to debride or washout established osteoarthritis in knees. The published evidence shows little advantage to arthoscopic debridement or washout and so has become a procedure of limited clinical value. In this paper there was shown to be no clinical benefit of surgery compared to conservative treatment with established osteoarthritis.
    BMJ Open. 2017 May 11;7(5):e016114. doi: 10.1136/bmjopen-2017-016114.
    Knee arthroscopy versus conservative management in patients with degenerative knee disease: a systematic review.
    Brignardello-Petersen R1,2, Guyatt GH1, Buchbinder R3,4, Poolman RW5, Schandelmaier S1,5,6, Chang Y1, Sadeghirad B1,7, Evaniew N8, Vandvik PO9,10.
    Similarly the procedure of debriding degenerate meniscal tears has been shown to have limited clinical benefit which is short-lived. Evidence shows a marginal improvement of symptoms for one year compared to those treated conservatively.
    BMJ. 2015 Jun 16;350:h2747. doi: 10.1136/bmj.h2747.
    Arthroscopic surgery for degenerative knee: systematic review and meta-analysis of benefits and harms.
    Thorlund JB1, Juhl CB2, Roos EM3, Lohmander LS4.
    The indications for doing an arthroscopy with non traumatic meniscal tears is a controversial one. ESSKA has produces some guidance with a treatment algorithm. Patients over the age of 35 who present with medial joint line pain should have a plane weight bearing X-ray looking for sign of osteoarthritis. If there is no OA then consider performing an arthroscopy if they fail conservative treatment for three months and the MRI shows a non traumatic meniscal tear.
    esska.org/resource/resmgr/Docs/2016-meniscus-consensus-proj.pdf

    Reference

    • orthoracle.com

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