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Anteromedialisation tibial tubercle osteotomy

    Overview

    Learn the Anteromedialisation tibial tubercle osteotomy surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Anteromedialisation tibial tubercle osteotomy surgical procedure.
    Fulkerson originally designed the tibial tuberosity anteromedialization technique to address patellofemoral pain associated with patellofemoral chondrosis in conjunction with patellofemoral tilt and/or chronic patellar subluxation. It was devised to overcome the significant complication rate associated with the Maquet (anteriorisation) procedure.
    The anteromedialisation transferred areas of patellofemoral loading through medialisation, which also improves patellofemoral joint congruity (improved joint contact area), and anteriorisation to transfer forces proximally, while theoretically decreasing the absolute magnitude of the patellofemoral resultant force.
    This theoretical decrease in resultant force and increase in contact area would thus decrease joint surface stress, potentially decreasing the condition of overload contributing to pain.
    Currently, interest has been renewed in anteromedialisation in conjunction with cartilage restoration of the patello- femoral compartment. Results of cartilage procedures are improved when the patellofemoral forces are minimised.
    The examination of patient should include assessment of coronal alignment, rotational alognment, patella height and the Q-angle. Evidence of retinacula tightnes should also be undertaken.
    All patients will undergo a pre-operative MRI and rotational CT scan in order to assess patient alignment. The MRI is used to assess Patella height and the chondral surfaces of the patella. The CT scan is used to assess the patients rotational profile and the Tibial Tubercle Trochlea Distance.
    Prior to surgery all patients should undergo a period of conservative treatment which includes physiotherapy, directed at core stability, hip rotators and lower limb strengthening. This can be combined with oral analgesia, activity modification (to avoid impact and open chain exercise) and potentially intra-articular injections.

    Indications

    Antero-medialisation of the tibial tubercle is indicated for patients presenting with pain +/- instability within the PFJ. The procedure can be combined with or without associated cartilage surgery to the patella or trochlea. The procedure will off-load the lateral facet of the patella and transfer load to the medial facet. A central cartilage lesion will only be minimally off-loaded with this surgery.

    Setup

    Operation

    A diagnostic arthroscopy is undertaken to confirm the diagnosis and document the distribution of cartilage degeneration within the patella. If the degeneration is lateral and the medial aspect of joint is intact then the osteotomy can proceed. The osteotomy can be performed with all grades of chondral degeneration. The principal reason to perform the arthroscopy is to rule out patients with significant medial facet/medial trochlea degeneration.

    A midline incision approximately 8 cm in length is utilised, the proximal end 2cm above the tibial tubercle

    The incision is depened to the paratenon.

    Full thickness skin flaps are then raised medially and laterally.
    The medial and lateral edges of the patella tendon are identified and the facia on either side released superiorly to the level of the lower pole of the patella.

    The anterior compartment of the the leg is opened and the tibialis anterior muscle is subperiosteally removed from the lateral aspect of the tibia.

    The diathermy is used to map out the proposed osteotomy on the medial aspect from superior to inferior. The line begins on the medial aspect of the tibial tubercle and moves distally and laterally so that it reached the tibial crest at a point at least 6cm from the insertion point of the patella tendon on the tibial tubercle.

    3 x 1.6m K-wires are inserted to guide the osteotomy cut. The wires are inserted from medial to lateral at a pre-determined angle dependent on the amount of anteriorisation versus medialisation that is desirable. The maximum anteriorisation is achieved with an approximate 60 degree angle. This is achieved by the wires exiting the lateral aspect of the tibia just above the posterior tibial boarder. The middle wire is inserted first.

    A second wire is inserted below the middle wire.

    A third wire is then plced proximally.

    These wires are placed in the same plane so that the cut is continuous and in the same plane. Similar to the medial starting point the lateral exit point should move towards the anterior tibial crest in order to create an intact distal hinge that can be deformed during the anteriorisation.

    A 1.5cm oscillating saw is the used to create the osteotomy. The cut is made against the previously placed K-wires whilst the skin is carefully retracted in order to avoid an abrasion injury from the blade. The cut is made whilst the blade is cooled with a slow trickle of water from the arthroscopy giving set in order to avoid thermal necrosis. The osteotomy cut should stop superiorly 2mm above the patella tendon insertion and distally 5mm from the crest.

    The proximal tuberosity cuts are then completed with an osteotome. A small langenbeck is placed underneath the patella tendon from the medial side and the tendon is retracted anteriorly. A 5mm osteotome is then used to create an osteotomy underneath the tendon extending from the proximal medial saw cut to the lateral side of the tendon.

    A broad 2cm osteotome is then used to connect the proximal lateral osteotome cut and the proximal lateral saw cut.

    The wires are then removed and the broad osteotome is placed proximally within the osteotomy site and the proximal tubercle is freed. The osteotome is then moved into the centre of the osteotomy and an attempt is made to rotate the tubercle antero-medially on the distal pedicle. If the pedicle is still too thick then the saw or osteotome can be used to extend the distal cut and reduce the size of the pedicle. Ideally the pedicle should be kept intact as this decreases the complication rate and improves the construct stability.

    The tubercle is anteriorised up to a maximum of 15mm, this usually results in approximately 10mm of medialisation. A paper ruler that comes with the marker pen can be used to quantify the displacement prior to fixation.
    A temporary K-wire can be used to hold the tubercle in the desired position before fixation.
    2x 4.5mm cortical lag screws with washers are used to stabilise the osteotomy. Initially a 4.5mm drill is used and then a 3.2mm drill through a drill guide as a centraliser.

    The screws are placed perpendicular to the osteotomy from antero-lateral to postero-medial.

    Once the second screw is inserted the patella tracking can be assessed and the stability of the fixation.

    Following completion of the osteotomy the tension within the lateral retinacula is assessed. If there is less that ¼ translation of the patella medially then a lateral release or lengthening can be undertaken.
    A lengthening is the preferred technique, particularly in patients with instability.
    A longitudinal lateral parapatella incision is made extending over the length of the patella.

    The skin is divided down to the retinacula and full thickness flaps created.

    The inferior flap must be developed as far posteriorly as possible in order to perform a sufficient lengthening.

    The retinacula is incised through approximately 50% of the thickness 5mm from the lateral boarder of the patella.

    The retinacula is then undermined posteriorly at least 1cm within the confines of the exposure.
    The remaining 50% of the tissue thickness is then divided as far posteriorly as possible. This creates a Z lengthening of the retinacular.

    The ends of the retinacula are then sutured together with 0 vicryl, effectively lengthening the retinacula. The translation within the patella is then reassessed.

    The fat layers are then closed with 2.0 Biosyn and either clips or subcuticular prolene for skin.

    Post Operative

    2 doses of antibiotics are administered post-surgery and a check x-ray is performed
    The patient remains partial weight bearing for 6 weeks and flexion is limited to 40degrees in a brace for 4 weeks before being unlocked for the remaining 2 weeks.
    Once the tuberosity osteotomy has healed, the patient is progressed with a standard core-strengthening program with patellar protection components as dictated by the articular surfaces. If the patient wants to participate in sporting activities and the articular surfaces allow that level of activity, the patient advances through a program of functional progression as per an ACL program of return to sport.
    In patients who undergo a steep (65degree) cut it is important that a strict PWB is observed as tibial fracture has been reported in these patients.
    Repeat x-rays are obtained at 6 weeks and then 3 months with the majority of osteotomies healing by this point. Delayed union can occur, particularly in patients where the distal hinge has lost its integrity. Revision surgery is only required in less that 5% of patients and this is not performed until after 12 months unless there is significant loss of position or tubercle fracture. In cases of revision surgery for non-union the tubercle can be stabilised with the use of a semi-tubular plate or a wrist T plate. This allows good compression of the fragment whilst reducing the risk of tubercle fracture through the drilling of more holes.
    Patients can complain of pain from the metalwork both in primary and revision cases due to the superficial position of the tubercle. Removing the metalwork can easily be undertaken as a day case procedure usually after 12 months post surgery. It cab be difficult to assess union fully on plain x-rays due to the oblique cut and so if there is any doubt prior to metalwork removal a CT scan can be obtained.

    Recommended Reading

    Fulkerson originally described anteromedial transfer of the tibial tuberosity in 1983, and followed up with a clinical series in 1990. The series focused on the out- comes of 30 patients observed for 2 years with 12 patients observed for 5 years. Fulkerson reported a 93% success rate subjectively, and 89% success rate by objective parameters. In a subgroup of patients with advanced arthrosis, 75% of patients experienced good results, with 0% experiencing excellent results.
    Pidoriano et al retrospectively reviewed a series of patients over a 10-year period, attempting to compare results relative to the geographic location of the articular cartilage disease. Eighty-seven percent of 23 patients with disease primarily located in either the distal or lateral por- tion of the patella experienced successful outcomes; 55% of 9 patients with medial disease experienced successful outcomes; and only 20% of 5 patients with either proximal or distal disease experienced a satisfactory outcome. A correlation was also noted between advanced disease of the central trochlea and a poor outcome.

    Fulkerson originally described anteromedial transfer of the tibial tuberosity in 1983, and followed up with a clinical series in 1990. The series focused on the out- comes of 30 patients observed for 2 years with 12 patients observed for 5 years. Fulkerson reported a 93% success rate subjectively, and 89% success rate by objective parameters. In a subgroup of patients with advanced arthrosis, 75% of patients experienced good results, with 0% experiencing excellent results.
    Pidoriano et al retrospectively reviewed a series of patients over a 10-year period, attempting to compare results relative to the geographic location of the articular cartilage disease. Eighty-seven percent of 23 patients with disease primarily located in either the distal or lateral por- tion of the patella experienced successful outcomes; 55% of 9 patients with medial disease experienced successful outcomes; and only 20% of 5 patients with either proximal or distal disease experienced a satisfactory outcome. A correlation was also noted between advanced disease of the central trochlea and a poor outcome.

    Fulkerson JP, Becker GJ, Meaney JA, Miranda M, Folcik MA. Anteromedial tibial tubercle transfer without bone graft. Am J Sports Med. 1990;18:490-497.
    Pidoriano AJ, Weinstein RN, Buuck DA, Fulkerson JP. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;25:533-537.
    Pidoriano AJ, Weinstein RN, Buuck DA, Fulkerson JP. Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med. 1997;25:533-537.

    Reference

    • orthoracle.com

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