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Rotational proximal tibial Osteotomy

    Overview

    Learn the Rotational proximal tibial Osteotomy surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Rotational proximal tibial Osteotomy surgical procedure.

    Anterior knee pain and patella instability is a common orthopaedic problem. It is estimated that the overall incidence of primary patella dislocation in the population is approximately 5.8 per 100,000, with a 5-fold increase in incidence between the ages of 10 to 17 years. Furthermore, the likelihood of recurrent instability after a primary dislocation is significantly higher (OR= 6.6, P<0.001) in individuals with preceding patella-femoral joint (PFJ) symptoms7. Young active individuals are particularly prone to develop sequelae that impair function with some studies reporting that up to 55% of patients fail to return to sports activity after this injury2,4. It is therefore paramount that once the diagnosis of PFJ dysfunction is made the precise cause is established in order to deliver optimal treatment.
    PFJ pain and instability is a multifactorial problem. In addition to the soft tissue constraints around the knee, the osseous architecture together with overall rotational limb alignment (femoral version (FV), tibial torsion (TT) and knee joint rotation angle (KJRA)) contributes to the normal workings of the joint.
    Paediatric orthopaedists are more likely to deal with these issues than their orthopaedic colleagues who see only adults. However, many adolescents transition into adulthood without the benefit of detection and correction of their malalignment and resultant patellar instability. Significant torsional malalignment is more common than generally appreciated and very often missed, despite being easy to detect. The approach to adults with patellar instability rarely includes evaluation, let alone correction of rotational abnormalities. Instead, most orthopaedists choose to deal independently with the consequences of the malalignment, such as patellar instability, patella alta, shallow femoral sulcus, increased Q-angle, lateral patellar compression, and so forth. Many of the corrective procedures for these associated conditions have enjoyed popular acceptance with good short-term results. However, there is concern regarding the development of late symptoms and arthritis. Thus, in many cases, these other procedures may need to be performed in combination with torsional realignment procedures, or may even be avoided altogether by restoring normal mechanical alignment. Relative to the inconsistent results of tibial tubercle transfer, many surgeons have chosen to use only proximal soft tissue procedures. In our opinion, failure to correct significant limb malalignment and the resultant valgus vector (patella) may ultimately invite soft tissue fatigue and stretching, even with the most robust reconstructions
    With relation to lower limb rotational alignment, deformities of increased femoral neck anteversion, torsional deformities of the femoral shaft and external tibial torsion increase the risk of PFJ instability. Though there have been a number of studies that have been published on the methodology of measuring lower limb alignment, few studies quote a normal range for the various rotational parameters in a control population. Those that do, appear to have a high data range and subsequent standard deviation in the values calculated, likely due to limited sample sizes. The values I generally use as normal are:
    Femoral anteversion 15 degrees
    Knee Joint Rotation 8 degrees
    Tibial torsion 23 degrees

    Indications

    SYMPTOMS & EXAMINATION
    Clinically, a full assessment of the patellofemoral joint is carried out. Patients with rotational mal-alignment are usually in valgus however they can occasionally be in varus. Patients walk with a typical “knee-in” gate secondary to tibial torsion. Patella height is assessed and the patella tracking observed. A positive J sign and apprehension sign is commonly present. Patients with tibial torsion may present with an increased Q angle however, this is not always the case.
    IMAGING
    Standard AP, Lateral and Skyline x-rays are obtained routinely. When rotational malalignment is present the AP view of the knee will show a AP of the tibia and an oblique view of the femur. The lateral view is used to calculate Blackburn peel index.
    The severity of the rotational deformity and its location if suspected should be confirmed with a rotational CT scan. The Tibial Tubercle Trochlea Groove distance (TTTG) is calculated on the CT scan as this has been should to be more accurate than MRI.
    The femoral neck axis was measured using the described technique by Hernandez et al., in 1981 as the axis created by a line passing through the centre of the femoral head and midpoint of the femoral neck in a cross-sectional CT cut where the femoral head, isthmus of the femoral neck and superior border of the greater trochanter are evident10. The transmalleolar axis 11 was measured as the axis created by a line connecting the centres of medial and lateral malleoli. Both these measurements have been advocated as being reliable methods of measurement by Liodakis et al as they are associated with lower inter and intra-observer variability13. The dorsal condylar line of the proximal tibia was taken as the axis line just distal to the articular surface of the tibial plateau and proximal to the fibular head. 11 Finally the distal femur reference was taken as the dorsal condylar line as described by Jend H.
    MRI is undertaken if there is concern over the cartilage surfaces and to rule out other pathologies.

    NON-OPERATIVE MANAGEMENT
    All patients undergo a minimum of 3 months physiotherapy prior to considering operative intervention. A significant number of individuals can compensate for their rotational abnormality with focused therapy to improve their core strength, hip external rotators and general lower limb strength.
    INDICATIONS FOR SURGERY
    -Anterior knee pain originating from the PFJ
    -Patella instability
    -Tibial torsion: The threshold for correction is not fully established. A number of authors quote different value which are largely based on clinical examination. Indications suggested are a foot thigh angle of >30 degrees alternatively and tibial torsion of greater than 35 degrees. My personal indication for surgery is a rotational difference of greater that 50 degrees between the distal femoral angle and the transmaleolar angle.

    Setup

    The equipment required for the procedure includes:
    A sagital saw – dimensions 2omm wide, 70mm long and approximately 0.89mm thick.
    A 4.5mm AO basic set
    Step staples of 5 and 10mm offset (traditionally used for closing wedge tibial osteotomy)
    Newclip osteotomy plate and set.
    2 x 3mm Steinman pins
    Sterile goniometer

    Operation – 1

    The patient is positioned on a radiolucent table with a tourniquet applied to the operative leg. A side post and foot roll is used so that leg can be positioned at approximately 90 degrees of flexion. The leg is prepared with alcoholic betadine and then prepped and draped in the usual manor for a knee arthroscopy.

    A diagnostic knee arthroscopy is then undertaken to confirm the pathology. If a significant chondral lesion of the patellofemoral joint is expected, this can be addressed simultaneously. Currently this would be with the use of Bone Marrow Concentrate on a Hyaluronic acid or Collagen scaffold, however hopefully ACI will soon be an option again in the near future.

    A midline incision approximately 8cm is made starting 2 cm proximal to the tibial tubercle.

    Full thickness skin flaps are created. The patella tendon is identified and the medial and lateral boarders are incised extending to the distal pole of the patella. A lateral release is not carried out at this stage.

    The anterior compartment of the leg is then opened along the length of the proposed tubercle osteotomy site and the muscle of tibialis anterior is stripped off the lateral boarder of the tibia using a periosteal elevator and diathermy.

    The proximal tib-fib joint is then located within the proximal portion of the anterior compartment. Its localisation can be confirmed by palpating the joint from within the anterior compartment whilst translating the fibula externally. The anterior and posterior capsule is disrupted using a cob elevator. Sufficient release is achieved once the proximal tib-fib joint can be easily translated in the anterior-posterior direction externally . Occasionally an osteotome needs to be used for this step as the capsule can be quite tough and therefore requires a sharper instrument than the cob. As long as one remains within the confines of the joint the risk of damaging the peroneal nerve is very low.

    The proximal insertion of the patella tendon to the tubercle is identified and a 6cm length of tubercle is measured. The outline of a proposed 6cm tubercle osteotomy is carried out using the diathermy.

    A sagital saw is used to create a tubercle osteotomy whilst simultaneously dripping arthroscopy fluid onto the saw in order to reduce the risk of thermal injury.

    The tubercle osteotomy is reflected proximally

    The retro-patella fat pad is stripped from the posterior aspect of the patella tendon.

    A ruler is used from the superior aspect of the tibial plateau to measure the proposed osteotomy site, 2.5cm below the joint line. This is then marked with the diathermy. At this level, the MCL is then released from the anteromedial aspect if the tibia. The minimum amount of release is carried out in order to prevent MCL laxity post-operatively. Enough of a release needs to be carried out so that the osteomy can be visualised and a jimmy retractor can be inserted in order to prevent MCL injury with the saw.

    An extra-medullary TKR tibial guide in then used to create the initial osteotomy cut. A 0-degree cutting block is used. The jig is used in a similar fashion to when undertaking total knee replacement in order to achieve a perpendicular cut relative to the anatomic axis of the tibia. Failure to achieve a perpendicular cut can result in inadvertent tibial slope change of the tibia when it is rotated. An initial guide cut is made at the previously marked osteotomy site which is deep enough to guide a subsequent free hand cut in the coronal and sagittal planes.

    The tibial jig is then removed. A 2.5-3mm Steinman pin is then inserted from front to back above the initial osteotomy cut. This should be a bi-cortical pin in order to achieve good purchase. A large diameter Steinman pin is used in order to allow for good manual feedback on the posterior cortex and thus preventing plunging into the posterior aspect of the knee.

    A second Steinman pin is then inserted below the initial osteotomy cut at a 35degree angle to the first pin. The direction of this pin is from anterolateral to posteromedial. The angle of insertion is determined with the use of a sterile goniometer. The pin is placed in a bi-cortical fashion. The pins should be placed approximately 1cm above and below the osteotomy cut.

    A Hohmann retractor is then placed at the level of the proposed osteotomy site in the anterior compartment. It is placed around the posterolateral aspect of the tibia in order to protect the posterior structures. A Jimmy retractor is then placed medially in the tunnel created by the previous medial release. Care is taken not to retract this too medially and cause excessive stripping of the MCL.
    The osteotomy is then completed free hand using the previous guide cut as a cutting slot. Water is again dripped onto the saw blade to reduce the risk of thermal injury.
    The adequacy of the osteotomy can be assessed by using the superior Steinman pin. If the osteotomy is sufficiently complete superior pressure on the pin should allow easy opening of the osteotomy site. If the gap does not increase easily then the osteotomy is incomplete and further division of the tibia is required using the saw or a broad osteotome. It is usually the postero-medial or posterior-lateral cortices which require further division. By ensuring the retractors on the medial and lateral side are at the level of the osteotomy the risk of damage to the medial and lateral structures is minimised. The risk of damaging the posterior neurovascular structures is ones main concern. It is important to develop good tactile feedback from the saw in order to be aware when one is cutting the posterior cortex. Resting the hand that is not operating the saw onto the leg and using it to steady the blade and prevent large movements (plunging) is an important safety aspect.

    Once happy with the osteotomy the foot is grasped with one hand and the Steinman pins with the other. The lower leg is then internally rotated and Steinman pins simultaneously compressed. This results in internal rotation of the tibia and usually divides any remaining posterior cortex. The tibia is internally rotated until the Steinman pins are parallel.
    During internal rotation of the tibia, there is often lateral translation of the proximal fragment, this can be corrected by placing a hohlman retractor in the osteotomy gap medially and levering it back medially. The shaft of the tibia will commonly not match the proximal fragment after it has been rotated.
    A shows a Hohmann retractor inserted in osteotomy site medially to correct lateral and posterior translation of proximal tibia

    The Osteotomy is then stabilised initially with a step staple laterally. The osteotomy reduction is maintained by the assistant keeping the Steinman pins held parallel. Usually a 5 or 10mm offset staple is sufficient to accommodate the mismatch between the proximal and distal fragments. The staple is impacted initially into the proximal fragment, it is then passed anterior to the anterior compartment musculature before being impacted into the distal tibia.

    The proposed hole for the distal arm of the staple is pre-drilled with a small 1.6mm k-wire in order to make insertion easier. The position of the Steinman pins needs to be taken into account when selecting the staple insertion points. The staple should be positioned as far lateral as possible.

    A decision can then be with made with regards to the remaining method of fixation. In older patients or in those where there is concern over bone quality a low-profile osteotomy plate can be used. In patients with good bone quality then a 2nd step staple can be chosen.
    A decision can then be with made with regards to the remaining method of fixation. In older patients or in those where there is concern over bone quality a low-profile osteotomy plate can be used. In patients with good bone quality then a 2nd step staple can be chosen.
    In this case a 2nd staple is used medially as the bone quality was felt to be very good. If a Newclip osteotomy plate is chosen, it is placed medially over the anteromedial aspect of the tibia. Given that this is a stable osteotomy not all screws need to be used. Usually we place 2 screws within the proximal fragment and 2 in the distal fragment. When placing these screws, the Steinman pins can be removed if they are in the way. When deciding on the placement of the staples and plate the position of the tibial tubercle fixation needs to be borne in mind.
    The average correction post fixation is approximately 25 degrees.

    Following completion of the osteotomy fixation, the tibial tubercle needs to be relocated in an anatomic position taking into consideration patella height and the TTTG distance. Patients with rotational problems commonly have associated patella alta and this needs to be corrected. The knee is flexed to 30 degrees and the tibial tubercle is pulled until the inferior pole is approximately 18mm (1 finger breadth) above the tibial plateau.

    The position of the tibial tubercle relative to the previous osteotomy site is then marked with the diathermy on the tibia.

    The sagittal saw is then used to make a cut at the location of the previous diathermy mark.

    A curved osteotome is then used to extend the tibial tubercle osteotomy site distally to the saw cut. The tubercle is then distalised to its new location and the patella height checked again.

    When happy with the patella height the tubercle is fixated to its new location using 2 x 4.5cortical screws with washers drilled in a lag screw fashion. The distal screw is placed initially. A 4.5mm drill is used to drill the proximal cortex before drilling the distal cortex with a 3.2mm drill through a centralising top hat or drill guide.

    The screw and washer is then inserted but not fully tightened. The tubercle is allowed to rotate on the distal screw and the knee is repeatedly flexed in order to decide on the most appropriate position. Due to the internal rotation of the tibia it is not uncommon to lateralise the tubercle in order to prevent over medialisation of the tubercle with resultant pain and or instability. Occasionally the tubercle bed needs to be re-fashioned with the saw in order to get an appropriate flat surface in an anatomic position. This is mainly an issue with patients who do not have patella alta is their tibial tubercle consequently sits across the tibial osteotomy site. When happy with the tubercle position the second lag screw is inserted.

    Operation – 2

    In patients with patella instability the medial retinacula can be distalised and plicated to increase the medial restraint. Rarely a lateral release or lengthening is required to balance patella tracking.

    Prior to closing an image intensifier is used to ensure adequate fixation. If preferred Imaging can be used throughout the case to optimise implant placement, particularly when using the newclip plate.
    A small drain is then inserted in the anterior compartment which is not closed.
    The fat layer is closed with 2.0 Biosyn.

    The skin is then closed with either clips or a subcuticular suture

    Post Operative

    Two doses of antibiotics are given post-operatively. Patients are allowed to partial weightbear for 6 weeks. Flexion is limited to 40 degrees for 4 weeks and 0-90 between 4-6 weeks. A formal check x-ray is performed prior to discharge. Further X-rays are undertaken at 6 weeks prior to commencement of weightbearing to ensure evidence of healing. Caution should be used in patients with staple fixation in patients with little sign of healing as medial subsidence can occur. This risk is minimised with the use of a fixed angle plate construct.

    Recommended Reading

    Probably the best study to date comparing the results of rotational osteotomy versus tibial tubercle osteotomy for patients with a foot thigh angle of greater that 30degrees is by Paulos et al. Despite low numbers of patients they determined that simultaneous correction of ligament imbalance, excessive tubercle-sulcus angle, and lower limb torsional deformity produced significantly better results than conventional proximal-distal realignment. Gait analysis revealed patients who underwent rotational correction had more symmetrical gait patterns, with less variability and less compensatory gait changes, than those patients undergoing tibial tubercle osteotomy in isolation.

    References
    Surgical Correction of Limb Malalignment for Instability of the Patella. A Comparison of 2 Techniques. L. Paulos, S.C. Swanson, G. J. Stoddard, SB Westinll . AJSM Vol. 37, No. 7, 2009
    Server F, Miralles RC, Garcia E, Soler JM. Medial rotational tibial osteotomy for patellar instability secondary to lateral tibial torsion. Int Orthop. 1996;20(3):153-158.
    Lee TQ, Morris G, Csintalan RP. The influence of tibial and femoral rotation on patellofemoral contact area and pressure. J Orthop Sports Phys Ther. 2003;33(11):686-693.
    Meister K, James SL. Proximal tibial derotation osteotomy for anterior knee pain in the miserably malaligned extremity. Am J Orthop. 1995;24(2):149-155.
    Proximal tibial derotation osteotomy for torsional tibial deformities generating patello-femoral disorders. Fouilleron N, Marchetti E, Autissier G, Gougeon F, Migaud H, Girard. J.Orthop Traumatol Surg Res. 2010 Nov;96(7):785-92.

    Reference

    • orthoracle.com

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