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Medial Patellofemoral Ligament Reconstruction using Healicoil Anchors (Smith and Nephew)

    Overview

    Learn the Medial Patellofemoral Ligament Reconstruction using Healicoil Anchors (Smith and Nephew) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Medial Patellofemoral Ligament Reconstruction using Healicoil Anchors (Smith and Nephew) surgical procedure.
    This is a presentation of the reconstruction of a medial patellofemoral ligament (MPFL) in a 31 year old female with recurrent patellar instability. The gracilis hamstring tendon is used and fixed using 4.5mm Healicoil PEEK bone anchors on the patellar side and Smith and Nephew Biosure PK interference screw in the femur.
    The technique includes:
    the use of pre-operative arthroscopy to assess tracking and patellar articular integrity. This case shows very clearly that the knee needs to be assessed “dry” to truly reflect patellar in vivo tracking
    the use of an image intensifier to help identify the correct position for the isometric femoral tunnel
    The operation utilises a graft to replace a damaged native medial patellofemoral ligament, a distinct thickening within the medial retinaculum. Recurrent lateral dislocation often leads to rupture and/or stretching of this defunctioned structure and risks further dislocations. Each episode is not only very uncomfortable but leads to long term irreversible chondral damage to the patellofemoral joint. Various options for reconstruction are available (listed below) but my preference is the hamstring graft as, in my hands it is a reproducible operation leading to excellent reduction in recurrent dislocation. The size, thickness and consistency of the gracilis tendon is the closest option to a direct replacement of the native MPFL. The graft acts as a check-rein to further dislocation. Soft tissue knee surgeons are quite familiar with hamstring harvesting from ACL reconstruction.
    The use of Smith and Nephew Healicoil (PEEK) anchors carry several potential advantages including:
    avoiding drilling across the patella, thereby reducing the potential risk of patella fracture
    the fact that the modulus of elasticity of PEEK is close to bone reduces the risk of creating a stress riser in the patella
    excellent demonstrable pull out strength of this implant
    ease of use of the Healicoil.

    Indications

    A recent 21 year population based study by Sanders et al demonstrated an incidence of 23.2 per 100000 of lateral dislocation (Sanders TL, Pareek A, Hewett TE, Stuart MJ, Dahm DL, Krych AJ. Incidence of First-Time Lateral Patellar Dislocation: A 21-Year Population-Based Study.Sports Health. 2018 Mar/Apr;10(2):146-151.)
    MPFL reconstruction is a powerful technique used in the stabilisation of the patellofemoral joint. It is often used in conjunction with realignment of the extensor mechanism as described by Mr James Murray on OrthOracle’s https://www.orthoracle.com/library/patella-stabilisation-tibial-tubercle-osteotomy-and-medial-patellofemoral-ligament-reconstruction/
    It is vital for the surgeon to assess all factors contributing to the individual patient’s patellar instability. These include:
    traumatic versus non-traumatic initial “first-episode” dislocation – as we recognise in the shoulder these two conditions have very different aetiologies and require different approaches. It is more likely that the non-traumatic dislocators have anatomical predispositions to instability as outlined below
    systemic hyperlaxity including soft tissue disorders (e.g. Ehlers-Danlos syndrome)
    persistent femoral and/or tibial malrotation
    trochlear dysplasia
    increased tibial tubercle offset
    patellar alta – increased height of the patellar secondary to long patellar tendon
    Furthermore the consequences of the dislocations must be assessed, including damage to the retropatellar and trochlear articular surfaces, MPFL rupture and medial retincular stretching.
    In this case all these assessment were made using a careful history, examination and appropriate investigations.
    Symptoms and assessment
    The patient presented with a 5 year history of unilateral patellar dislocation following a traumatic event in the sports arena. Despite a course of intensive physiotherapy her instability symptoms did not settle. Over the period of 5 years the patient suffered in excess of 5 further dislocations.
    She also gave a history of pain and occasional swelling. The concern with these symptoms are longstanding damage to the articular cartilage in the patellofemoral joint, which despite not being evident on the MRI scan, warranted assessment with the arthroscope at the time of reconstruction surgery.
    In the acute setting the surgeon must be aware of the potential of osteochondral fragments being chipped of the patella or the troclear at the time of dislocation / relocation. The patient may complain of loose body symptoms including locking and giving way. Some patients even see or feel the fragment moving around.
    Overall limb alignment is assessed with the patient standing. Patients with a coronal valgus deformity are at increased risk of lateral patellar tracking and therefore patellar dislocation. I have performed distal femoral varus osteotomies for patients with recurrent patellar instability and significant isolated valgus coronal deformity (i.e. no rotational element). Assessment includes foot position.
    Generalised laxity is assessed according the Beighton score:
    1. Passive dorsiflexion and hyperextension of the fifth MCP joint beyond 90°
    2. Passive apposition of the thumb to the flexor aspect of the forearm
    3. Passive hyperextension of the elbow beyond 10°
    4. Passive hyperextension of the knee beyond 10°
    5. Active forward flexion of the trunk with the knees fully extended so that the palms of the hands rest flat on the floor
    1, 2, 3 and 4 are assessed on both left and right sides. Each element is given a score of 1 if present (0 if absent) giving a total out of 9. Although there is debate on the definition of hyperlaxity based on this scoring system a score of greater than 5 is highly suggestive.
    The knee is assessed for swelling and concomitant injury. Further detail of the assessment of the knee itself is explained in the detail of the operation.
    Investigations
    Xray
    CT scan
    MRI
    Long-leg alignment views
    Operative alternatives
    Assessment must include the need for tibial tubercle transfers in addition to MPFL reconstruction
    Lateral release
    Medial plication procedures
    MPFL reconstruction using other grafts:
    quads tendon
    artificial grafts (e.g. lars ligament) especially in patients with connective tissue disorders such as Ehlers-Danlos
    Non-operative alternatives
    All cases require targetted physiotherapy prior to considering surgery, and certainly is the mainstay treatment for first-time and some repeated patellar dislocations.
    Contraindications
    Active infection
    Patients with poor compliance with post-operative rehab
    Although not true contra-indications the surgeon must ensure that all factors for patellar dislocation have been considered before proceeding to an isolated MPFL reconstruction as failure rates would expected to be higher in e.g. trochlear dysplasia, connective tissue disorders and high tibial tubercle offset

    Setup

    Set up includes:
    high thigh tourniquet
    antibiotics at induction
    arthroscopy stack
    side support and foot plate / sand bag
    image intensifier
    bone anchors
    interference screw
    ACL set (to harvest and prepare the graft; ream the femoral tunnel)

    Operation – 1

    The operation should allows start with a thorough examination under anaesthetic (EUA) prior to inflation of the high-thigh tourniquet.
    The operation should allows start with a thorough examination under anaesthetic (EUA) prior to inflation of the high-thigh tourniquet. This includes assess dynamic patellar tracking. The knee is taken from full extension into full flexion whilst observing the patellar passage into the trochlear, known as patellar engagement. In the physiological knee this should occur around 20-30 degrees of flexion. “Late” engagement of angles greater than 30 degrees suggests patellar alta or hyperextension of the knee. A inverted J-shaped route, where the patellar starts far lateral in full extension and flicks into the midline on engagement suggests patellar lateral maltracking, seen in cases of increased tibial tubercle offset, often necessitating an osteotomy.
    Next the patella is assessed for tilt in the axial plane, often associated with a tight lateral retinaculum and/or significant medial retinacular laxity. In extreme cases it is possible the manipulate the patellar into a near-vertical position in the trochlear.
    The image shows the assessment of lateral patellar glide by putting pressure on the medial border of the patellar. In this case the patella can be shifted lateral by 75-100% of the width of the lateral femoral condyle and easily dislocated. It is vital to take note of this as the reconstruction should aim to reduce this is 0-25% of this width at the end of the procedure.

    Hyperextension is assessedHyperextension is assessed as shown.

    The knee is set up with a high-thigh tourniquet, side-support and foot-plate / sand-bag in flexion.The knee is set up with a high-thigh tourniquet, side-support and foot-plate / sand-bag in flexion.
    As some stages of the operation thereafter takes place in extension it is advisable to not have the sandbag sitting too high, as it risks leaving the knee in the hyperextended position.

    Skin incisions are marked outThe skin incisions are marked as follows:
    2 short horizontal marks anteromedially and anterolaterally for the arthroscopy portals
    The dotted line for the hamstring harvest incision.
    Short lines more proximally adjacent to the medial border of patella (bone anchors) and over the medial femoral epicondyle (femoral tunnel).

    A pre-operative arthroscopy can be very helpfulDue to the patient complaining of pain and swelling the knee is initially assessed with an arthroscope. In the absence of these symptoms and normal patello-femoral joint articular cartilage on the MRI scan I find it unnecessary to perform an arthroscopy, which is open to debate as to whether MRI is accurate enough for this assessment.
    This view shows the trochlear with the knee insufflated with normal saline at 40mmHg. Note the patella is not sitting in the groove.

    The retropatellar surface is fully assessed.The retropatellar surface is fully assessed.

    Pre-operative arthroscopic assessment can be performed in a “dry knee”Note that caution should be employed when assess the dynamic tracking of the patellofemoral joint in a knee filled with water under pressure, which would naturally lift the patella up and out (laterally) from the trochlear groove. In the image the fluid has been largely removed to assess the tracking in a “dry” knee.
    In this case the tracking was reasonable apart from evidence of patellar tilt. The articular surfaces where entirely intact.

    With the arthroscopy assessment complete the next stage is to harvest the gracilis tendon.A longitudinal incision is made 3 finger breadths below the medial joint line, over the pes anserinus.
    The incision is continued through the subcutaneous fat layer onto the fascia overlying the sartorial bursa and pes tendons.

    The tendons of gracilis and semitendinous can be palpated on the anterior tibial surface by rolling a finger over the top.The overlying bursa is elevated using fine toothed forceps with the gracilis tendon and lifted away from the tibial surface. A closed pair of Metzenbaum scissors is then pushed down behind the tendon which opens the bursa with a pop. This opening is carefully opened with blunt dissection to expose the underlying gracilis.

    The gracilis tendon is the more proximal and thinner of the pes anserinus tendons. It is hooked with a tendon hook and pulled distally.Any vinculae are released under direct vision. Often the use of two hooks is helpful working proximally to release the tendon. Also increasing knee flexion gives more length and slack to pull the tendon out of the incision.

    A finger is then hooked under the tendon to check that is springy and comes easily.A solid endpoint tends to suggest that there may be more proximal vinculae tethering the tendon to the medial head of gastrocnemius (although this is more common in semi-tendinosus).

    A Linvatec stripper is used to harvest the tendon.Counterpull is applied with the finger while the stripper passes proximally. Again a sudden stop in advancement should alert the surgeon to a potential incomplete release.

    Once harvested any residual muscle fibres are stripped off the tendon with the dissecting scissors.

    The free end of the tendon is whipstitched using 2 vicryl.

    The tip of the tendon is “bullet-nosed” to a tapering tip to allow easier passage of the tendon into the femoral tunnel.

    The distal end of the tendon is carefully amputated, avoiding damage to the adjacent semi-tendinosus attachment.

    The harvested graft can be checked for length topographically.Prior to whipstitching the second end of the tendon I like to assess the rough distance from the medial border of the patella to the femoral tunnel. If there is excessive length to the graft then the tendon may need to be shortened at a later stage (if the excess is over 60mm, which is the average width of the distal femur, the femoral tunnel cannot be blindending else the tendon will ruck up in the tunnel). However here there will be around 40-45mm of tendon in the tunnel which will sit entirely in the femoral tunnel. Whipstitching can therefore be done at this stage.
    1 = incision for femoral tunnel
    2 = length of tendon that will sit within the femoral tunnel ideally 35-45mm

    Next a 5cm incision is made over the medial border of the patella.Deep dissection is continued through layer 1 (superficial fascia) and layer 2 (medial retinaculum and MPFL) avoiding opening layer 3 (joint capsule).

    A trough is created in the proximal half of the patella using a pair of bone nibblers, down to bleeding cancellous bone.

    The anchors are planned for the proximal 2 thirds of the patellar medial border.The fixation will involve 2 bone anchors. Therefore it is beneficial to plan out the entry points of the anchors to ensure that the trough is long enough to allow a safe separation of the entry points, in this case 3 cm was measured out.
    The anchors are planned for the proximal 2 thirds of the patellar medial border. Studies have suggested that the patellar insertion of the MPFL is variable but more consistently in the proximal to the midpoint. One advantage of laying the graft a trough between two separate anchor points is to spread the load and reduce inadvertent rotation of the patella, as well as increasing the surface area for healing. It is my preference to avoid drilling across the patella for fear of iatrogenic fracture.

    A 4.5mm Healicoil PK (PEEK) anchor with Ultrabraid sutures is chosen.The open architecture of the anchor allows for bone ingrowth to reduce the risk of pull-out. The PEEK material has a modulus of elasticity very similar to bone and therefore is less likely to act as a stress riser within the patella. From a technical perspective the anchors are easy to insert.
    1 = anchor
    2 = cannulated delivery shaft containing Ultrabraid sutures
    3 = release trigger
    4 = handle
    5 = Ultrabraid sutures

    Tip: at this stage of the operation is it often helpful for the primary surgeon to switch sidesThe entry points for the anchors are prepared with the prerequisite Smith and Nephew awl. I have found that opening the cancellous bone as far as but not including the threads is all that is required for the 4.5mm anchor. Caution must be employed to ensure that the tip of the awl is orientated perpendicular to the medial border to avoid perforating the anterior or posterior surfaces.

    The anchor is screwed into the patella until it is buried.There is a dark line to assist the depth.

    The anchor is screwed into the patella until it is buried.There is a dark line to assist the depth.

    Once the anchor is seated the Ultrabraid suture is unwound from the handle.

    Operation – 2

    Once the anchor is seated the Ultrabraid suture is unwound from the handle.

    The blue release trigger is pulled as the anchor is released from the delivery device.

    The blue release trigger is pulled as the anchor is released from the delivery device.

    The process is then repeated for the second anchor at a minimum distance of 15mm from the first anchor.

    The final skin incision is made over the medial epicondyle of the femur.Dissection is continued onto the medial femoral condyle. The femoral tunnel is topographical between the epicondyle and the adductor tubercle.

    An image intensifier is used to identify the optimal isometric femoral tunnel positionIn order to find the isometric entry point for the femoral tunnel the image intensifier is a very helpful adjunct as described by Redfern et al in AJSM in 2010 (For full reference see results section). It is important to take the time to ensure that a direct lateral view is achieved to avoid parallax. The aim is to have the posterior cortices of the medial and lateral condyles directly overlapping (see next image).

    The image intensifier is used to position the tip of the passing pin.The femoral tunnel should commence in the area as shown. The bone triangle is created by the Blumensaat’s line (A), which is the line formed by the roof of the intercondylar notch, and a line continuing along the posterior femoral cortex (B).

    The passing pin is advanced to the lateral femoral cortex aiming slightly cranially and anteriorlyWith the starting point established with the image intensifier the passing pin is advanced to the lateral femoral cortex aiming slightly cranially and anteriorly to avoid damage to the common peroneal nerve, which runs close to the biceps femoris tendon.

    The next step is to tie the graft into its trough on the medial border of the patellaThe graft is laid between the sutures at its midpoint.

    Each anchor is loaded with 2 Ultrabraid suturesEach anchor is loaded with 2 Ultrabraid sutures thus fixation will be with 4 knots in total.

    Once fixed to the patella the graft is wrapped around the passing pin to check for isometryOnce fixed to the patella the graft is wrapped around the passing pin to check for isometry, whilst taking the knee through a range of motion. Both limbs of the graft should remain static and not slip.

    If there is a change in length during range this indicates that the pin is not in the isometric point and will need to be repositionedOnce fixed to the patella the graft is wrapped around the passing pin to check for isometry, whilst taking the knee through a range of motion. Both limbs of the graft should remain static and not slip.
    If there is a change in length during range this indicates that the pin is not in the isometric point and will need to be repositioned. I have found that this is rare when using the image intensifier technique for pin placement.

    The plane is created deep to the medial retinaculum and above the joint capsule with a curved clip.The tip of the clip is brought out through the femoral incision.

    A second clip is caught by the first and pulled back up to the patellar incision in the correct plane.A second clip is caught by the first and pulled back up to the patellar incision in the correct plane.

    A second clip is caught by the first and pulled back up to the patellar incision in the correct plane.

    The graft limbs are then pulled through their plane to the femoral incision.

    The excess length of tendon i.e. the amount that will passed into the femoral tunnel is measured.This determines the minimal length of the tunnel – often 30-45mm. Any length in excess of 55-60mm runs the risk of being too long and needs to be trimmed.

    The tunnel is drilled to the predetermined length over the passing pin with a 7mm reamer, taking care to protect the graft.

    With the blind ending tunnel drilled the passing pin is advanced through the skin on the lateral thigh and a non-braided heavy ethilon suture is slotted into the pin’s eyelet.The whipstitched sutures are passed into the loop of the suture as shown.
    This makes passage of the graft easier to control. The pin is pulled through followed by the graft, into the tunnel.

    The graft is fixed in the femoral tunnel with the knee positioned at the point at which the patella first engages in the trochlear often around 20-30 degrees of flexion.The graft should not be overtightened as it should act as a checkrein to prevent lateral subluxation rather than constraint. Overtensioning can lead to increased joint reaction forces coming into flexion and therefore pain. Worse still it could lead to medial patellar dislocation.
    A 7x35mm Biosure PK (PEEK) screw is inserted over a guidewire.

    The effectiveness of the reconstruction is tested.The knee is taken through a full range to ensure there is no restriction. Lateral glide is tested and should now be less than 25% of the width of the lateral femoral condyle.
    Once this is established excess sutures can be cut.

    Skin closure is completedThe wounds are closed with absorbable deep sutures and 3/0 ethilon to skin. The knee is infiltrated with 0.7% ropivacaine.
    The wounds are dressed with adherent dressings and wool and crepe.

    Post Operative

    The wool and crepe dressings can be reduced after 48 hours but the adherent dressings are kept in site until 14 days, at which point the sutures are removed. It is imperative that the wounds are kept dry.
    Once on the ward the physiotherapist can commence passive and supportive active range. Provided the patient recovers early quads recovery no brace is required. However if the patient does not have good static quads control a Range-of-Motion (ROM) brace can be applied with no limit to range. Early quads recovery is key to successful progression through rehab.
    If the patient is not fully weightbearing compression stockings with clexane 40mg is used until fully mobile.
    Active range should be pushed from the off. As the reconstruction is a checkrein there should be no stress across the fixation with normal activity. Failure to recover good VMO control will leave the reconstruction vulnerable if the patient suffers patellar instability hence the early unrestricted commencement of physio.

    Recommended Reading

    The use of image intensifier has improved the consistency of finding the isometric position of the femoral tunnel in my practice. It is well described in the following paper:
    John Redfern, Ganesh Kamath and Robert Burks. Anatomical Confirmation of the Use of Radiographic Landmarks in Medial Patellofemoral Ligament Reconstruction. Am J Sports Med 2010 38: 293-297.
    An excellent “current concepts” review of MPFL reconstruction was written up in the article below including differing techniques of fixation:
    James Bicos, John P. Fulkerson and Andrew Amis. Current Concepts Review: The Medial Patellofemoral Ligament. Am J Sports Med 2007 35: 484-492.
    Howells et al’s series of 219 isolated MPFL reconstructions showed no recurrent dislocations at an average of 16 months:
    Howells NR, Barnett AJ, Ahearn N, Ansari A, Eldridge JD. Medial patellofemoral ligament reconstruction: a prospective outcome assessment of a large single centre series. J Bone Joint Surg Br. 2012 Sep;94(9):1202-8.

    Reference

    • orthoracle.com

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