TaperFit Cement-in-Cement Revision Femoral Stem Surgical technique

Transcription

1 Cement-in-Cement Revision Femoral Stem Surgical technique

2 Contents Introduction 4 Rationale 4 Advantages 4 Operative summary 5 Operative technique 6 1. Pre-operative planning 6 2. Removal of cement above shoulder of implant 6 3. Assessment of proximal cement-bone interface and stem removal 6 4. Assessment of exposed cement mantle 7 5. Abrasion of exposed PMMA surface 7 6. Accommodation of the distal wingless void 7 7. Insertion of the trial stem with locating pin 7 8. Cleaning and drying the existing cement mantle 8 9. Introduction of bone cement Implantation of revision stem and wingless void Trial reduction Definitive head impaction Post-operative management 9 Ordering information 10 Indications 10 Contraindications 10 Sizing information 11 References 11 2

3 Design I History I Function Responsible Innovation 3

4 Introduction If a primary cemented hip component fails, the polymethyl methacrylate (PMMA) bone cement mantle is often intact and well integrated with the cancellous bone. This is particularly the case when modern cementing techniques have been implemented during the index procedure. Should the cement mantle and cement-bone interface remain in this potentially viable condition following the removal of the failed cemented component, it may be advisable to leave the cement mantle in situ. The cement mantle can then be used as part of a cement-in-cement revision procedure, where a new femoral component is re-cemented onto the existing PMMA layer. Rationale In the late 1970s the routine practice of completely removing a mechanically sound cement mantle during revision hip procedures was questioned by Greenwald et al 1. It was demonstrated that preserving a well-fixed cement mantle and cementing a new component within it may be beneficial. If a pre-existing, well-fixed and intact bone cement mantle was prepared correctly (by roughening, cleaning and drying the exposed surface) the shear strength at the interface between the newly-applied cement and the old cement mantle would be approximately 94% of that observed for a single cement block. However, it was reported that the shear strength at the interface between new cement and a poorly prepared pre-existing cement mantle would be reduced by approximately one third compared to a single block of bone cement. This reduction in shear strength has been reported elsewhere 2 using an experimental model with human femora; a 30% reduction in shear strength was found at the newly applied cement-bone revision interface when compared to the revised cement-cement interface. There have been numerous clinical reports supporting the use of cement-incement revision procedures. Survivorship data on 19 and 23 cement-in-cement revision femoral procedures was gathered and followed up to a mean 5 and 12 years respectively, with no stem loosening reported 3,4. Stem migration rates for cement-in-cement procedures have been shown to be similar to those reported for primary procedures 4. In terms of radiological outcomes, 42 patients were followed up to a mean of 29 months with no impending failures reported 5 and more recently data on 136 cement-in-cement revision stem cases resulted in no stem loosening (aseptic and radiological) out to 8 years mean follow-up 6. Advantages In appropriate circumstances the intra-operative advantages of cement-in-cement femoral revision include reduced bone loss, reduced blood loss and reduced operating time 3,4,5,6. When a primary cemented stem is being revised with a similar sized cemented stem the challenging task of removing the existing distal cement can result in major intraoperative complications. Perhaps the most significant of these is femoral perforation and/or fracture. By leaving the cement in situ this risk can be minimised by revising to either a 38mm or 45mm offset TaperFit cement-in-cement revision stem. These devices are approximately 25mm shorter than Corin s primary TaperFit stem range (with the exception of the CDH primary option which is contraindicated for revision applications). Consequently, the need for distal cement removal is reduced or even avoided, depending on the exact size and shape of the stem being removed. Each of these dedicated cement-in-cement revision options are slightly slimmer than the equivalent size 1 TaperFit primary stem. Stem version may be adjusted during the revision procedure without the need for excessive, or even any, removal of existing proximal cement. The TaperFit cement-in-cement revision stems are supplied with a wingless void which should be fitted to the tip of the femoral stem prior to implantation. This ensures that the stem can act as a true, self-tightening taper once the freshly applied mix of PMMA bone cement has cured and post-operative load is applied. An end-cutting drill is also available in the system to facilitate safe distal cement removal and ensure that there is enough space for the wingless void prior to inserting the new mix of cement and the definitive revision stem. By opting for this comparatively simple and quick method of femoral component revision, the risk of infection may be reduced. Post-operative advantages might include full weight bearing and early patient mobilisation, unless acetabular or other patient considerations prevent this. Careful stem removal (and subsequent re-implantation) may also be used to facilitate acetabular exposure for revision purposes. Please refer to Corin s TaperFit primary surgical technique (I1078) and product rationale (I1154) for more details. 4

5 Operative summary a. Stem removal c. Cement assessment d. Cement abrasion e. Stem trial f. Cement cleaning g. Cement introduction h. Stem implantation i. Trial reduction j. Head impaction Responsible Innovation 5

6 Operative technique 1. Pre-operative planning A radiographic assessment is undertaken to determine the most likely cause(s) of failure. Co-existing biomechanical issues, such as leg length discrepancy or implant version, should also be considered at this time. The indications and contraindications for Corin s TaperFit cement-in-cement revision femoral stems are found on page 10. Templating is extremely important at this stage as the cavity within the in situ cement mantle should be able to accommodate a similar sized cemented stem to the one being removed without the need for excessive removal of the existing cement mantle. Alternatively, the cavity should be able to accommodate a shorter and slimmer dedicated TaperFit cement-in-cement revision component. When making the above choice between cemented stem sizes, the weight of the patient and size of the replacement stem should be taken into account. AP and lateral x-rays should be available to help confirm how much the cement cavity can be extended (see step 6) if needed. 2. Stem removal Use a high speed burr (as depicted) or small osteotome to carefully clear an exit channel for the implant before attempting to remove the prosthesis itself. If the cemented stem used in the primary surgery was a highly polished double tapered design, it should be relatively simple to remove it from its cement mantle without disrupting the PMMA-bone interface or damaging the PMMA construct. This does not preclude the revision of a matt or roughened stem to a TaperFit cement-in-cement revision stem. A robust instrument, which grips the implant and allows a strong axial force to be applied is used to remove the stem. 3. Assessment of exposed cement mantle Once the femoral component has been removed, the innermost pre-cured PMMA surface is cleaned and carefully assessed for damage etc. The calibrated 8mm diameter drill is used to probe the cement cavity and determine its depth (as depicted) so that distal cement removal extends no further than necessary (see step 6). The drill must be able to freely enter the cavity to a depth of approximately 150mm, depending on specific patient anatomy, relative to the tip of the greater trochanter. Remove any loose cement from the greater trochanteric region. Remove any non-viable bone from the greater trochanteric region and bone graft if necessary. Only proceed with the cement-in-cement revision procedure if the existing PMMA layer is intact and well-fixed from the level of the lesser trochanter and distal to that point. 6

7 4. Abrasion of exposed PMMA surface Roughen and clean the PMMA surface using a high speed burr (as depicted), rasp or reamers using a light reciprocating action. This allows the new mix of bone cement, to be applied later in the procedure, to come into direct contact with any residual activator and residual monomer within the old cement mantle. This also improves the mechanical interlock between the existing PMMA and the new cement layer. 5. Accommodation of the distal wingless void If required, the calibrated 8mm diameter drill is used (see steps 1 and 4), in conjunction with irrigation, to carefully clear just enough space to accommodate the tip of the revision stem when the wingless void is fitted (see page 11). 6. Insertion of the trial stem with locating pin This trial construct is used to ensure that there is enough space inside the existing bone cement mantle for the definitive revision stem, complete with wingless void, to be inserted to the required depth. If needed, proximal cement can be carefully removed with a high speed burr or reamer until the desired version is achieved. The locating pin (shown) will be required to stabilise the cement-in-cement revision trial stem within the existing bone cement cavity. Joint stability, leg length, stem version and range of motion are then assessed during trial reduction. The proximal femur is marked, referring to the holes on the trial stem (which corresponds to marks on the definitive implant), to aid in the final placement of the revision stem. 7. Cleaning and drying the existing cement mantle This facilitates the direct apposition of freshly mixed cement against the existing PMMA mantle. Thoroughly clean the cavity with pulse lavage, aspirate and dry the cavity with gauze in conjunction with a narrow suction catheter. Leave the latter in place until just before cement insertion. Responsible Innovation 7

8 8. Introduction of bone cement In order to optimise the potential for re-polymerisation, early retrograde introduction of the liquid cement (bearing the cement manufacturer s mixing instructions in mind) is recommended. A cement gun with a narrow nozzle should be used so that contemporary cement pressurisation techniques can be applied. 9. Implantation of revision stem and wingless void Make sure that the wingless void is fitted to the chosen stem and, having referred to the cement manufacturers instructions, insert the implant to the appropriate depth while maintaining proximal pressure until polymerisation is complete. A small amount of cement should be placed over the lateral shoulder of the implant to prevent it from being pulled out of the mantle. 10. Trial reduction Once the newly-applied bone cement has hardened, trial heads should be used in conjunction with the definitive stem to determine which neck length is required to give the best available range of motion and joint stability. 8

9 11. Definitive head impaction Once the acetabular cup is implanted, but before placing the definitive head on the stem, the stem taper should be thoroughly rinsed and carefully dried to ensure that it is free from debris. The head is then placed on the stem taper by twisting lightly and applying axial manual pressure until it is seated firmly. The plastic head impactor is placed on the pole of the head and impacted with a light tap using a hammer in an axial direction. Never use a metal hammer directly on the surface of the definitive head, only the plastic head impactor provided. The hip can then be carefully reduced and closure performed using the surgeon s preferred technique. 13. Post-operative management As long as there are no issues arising from acetabular considerations or other unforeseen complications, full weight bearing is allowed at the surgeon s discretion. Responsible Innovation 9

10 Ordering information TaperFit Cement-in-cement revision stem mm offset mm offset TaperFit Cement-in-cement revision instruments mm offset trial mm offset trial TaperFit setting pin Calibrated 8mm drill TaperFit wingless void Pack of 5 TaperFit Cement-in-cement revision stem X-ray set AT AT AT AT % magnification 110% magnification 115% magnification 120% magnification CoCr modular heads (12/14) from the Trinity acetabular system E Extra short -5.0mm 28mm E Extra short -6.0mm 32mm E Extra short -8.0mm 36mm E Extra short -8.0mm 40mm E Short -3.5mm 28mm E Short -4.0mm 32mm E Short -4.0mm 36mm E Short -4.0mm 40mm E Medium 0.0mm 28mm E Medium 0.0mm 32mm E Medium 0.0mm 36mm E Medium 0.0mm 40mm E Long +3.5mm 28mm E Long +4.0mm 32mm E Long +4.0mm 36mm E Long +4.0mm 40mm E Extra long +7.0mm 28mm E Extra long +7.0mm 32mm E Extra long +8.0mm 36mm E Extra long +8.0mm 40mm BIOLOX delta ceramic modular heads (12/14) from the Trinity acetabular system Short -3.5mm 28mm Short -4.0mm 32mm Short -4.0mm 36mm Short -4.0mm 40mm Medium 0.0mm 28mm Medium 0.0mm 32mm Medium 0.0mm 36mm Medium 0.0mm 40mm Long +3.5mm 28mm Long +4.0mm 32mm Long +4.0mm 36mm Long +4.0mm 40mm Extra long +7.0mm 32mm Extra long +8.0mm 36mm Extra long +8.0mm 40mm 10

11 Indications The cement-in-cement revision femoral technique is suitable for both matt and polished cemented stems. Pre-existing cement mantle quality should ideally be intact and well-fixed along its entire length or intact and well-fixed distally (i.e. from the level of the lesser trochanter and below) Stem removal to facilitate: acetabular exposure exchange of damaged and/or broken components exchange of incompatible component combinations change of version change of length for the treatment of instability and/or leg length discrepancy revision for stem fracture or loosening at the prosthesis-cement interface Contraindications One-stage revision for infection Rupture of the cement-bone interface which extends below the level of the lesser trochanter either before, during or after removal of the pre-existing femoral stem Presence of an in situ cement mantle which cannot be cleaned and dried adequately prior to re-cementation Removal of anatomic cemented femoral components Osteomyelitis Sepsis Osteomalacia Distant foci of infections Severe osteoporosis Marked bone loss or bone resorption Metabolic disorders which may impair bone formation Vascular insufficiency Muscular atrophy Neuromuscular disease The TaperFit cement-in-cement revision stem is not intended for use in primary procedures. When making the choice between using a TaperFit cement-in-cement revision stem and one of the other stems from the TaperFit range, the weight of the patient and size of the replacement stem should be taken into account Sizing information Approximate level of greater trochanter tip Minimum approximate drill depth Stem + void length (135mm) Stem length (125mm) + 38mm 40mm Offset + Neck length 34mm (38mm stem) 36.5mm (45mm stem) Responsible Innovation 11

12 References 1. Greenwald AS, Narten NC, Wilde AH. Points in the technique of recementing in the revision of an implant arthroplasty. J Bone Joint Surg 1978: 60B: 1: Rosenstein A, MacDonald W, Iliadis A, McLardy-Smith P. Revision of cemented fixation and cement-bone interface strength. Proc Inst Mech Eng (H) 1992: 206: 1: Leiberman JR, Moeckel BH, Evans BG, Salvati EA, Ranawat CS. Cement-within-cement revision hip arthroplasty. J Bone Joint Surg 75B: 6: Mandziak DG, Howie DW, Neale SD, McGee MA. Cement-within-cement stem exchange using the collarless polished double taper stem. J Arthroplasty 2007, 22(7): Quinlan JF, O Shea K, Doyle F, Brady OH. In-cement technique for revision hip arthroplasty. J Bone Joint Surg [Br] 2006, 88-B (6): Duncan WW, Hubble MJW, Howell JR, Whitehouse SL, Timperley AJ, Gie GA. Revision of the cemented femoral stem using cement in cement technique: a 5 to 15 year review. J Bone Joint Surg [Br] 2009, 91-B (5): The Corinium Centre Cirencester, GL7 1YJ, UK t: +44 (0) f: +44 (0) e: info@coringroup.com 100% Printed on Cocoon 100 which contains 100% total recycled fibre and is produced at a mill which folds the ISO for Environmental Management Systems. The pulp is bleached using Elemental Chlorine Free processes Corin P No I1232 Rev1 04/2015 ECR 13464