Technique. Linea Anatomic Revision Implant.

Transcription

1 Surgical Technique

2 CONTENTS CONTENTS Cementless range with optional locking 1. Assessing pathological hip 2. Reconstructing the acetabulum 3. Choosing and positioning femoral implant 4. Refining reconstruction 5. Phase 1: Exposure and ablation of implants 6. Phase 2: Acetabulum reconstruction 7. Phase 3: Femoral preparation 8. Phase 4: Final implant and optional locking 9. Postoperative recovery INTRODUCTION p. 1 SURGICAL TECHNIQUE p INSTRUMENTS p IMPLANTS p. 22 Surgical Technique Linea Anatomic Revision Implant UHRT101

3 INTRODUCTION CEMENTLESS RANGE WITH OPTIONAL LOCKING Anatomic anchoring reinforced primary stability maximization of the remodeled contact surface better positioning of femoral head Lateralization and neck length increase with size Stem length mm ø 6mm ø 4,5mm Proximal threaded interlocking screw solid core ø 4,5mm better resistance Distal anteroexternal bevel prevents contact in sensitive zones Overall anteversion 13 Metaphyseal helitorsion 7 Size ø Stem (mm) Neck length (mm) Lateralization (mm) Stem length (mm) Size 5* Size Size Size Size Size * Not lockable and on specific request 1 Surgical Technique UHRT101

4 ASSESS, ANTICIPATE, PREPARE: THE 4 MAIN PLANNING PHASES 1. Assessing the pathological hip Identify radiological enlargement Usually 1.15 with metallic landmark for verification on anterior and exterior side of the thigh. If digitized images are used, select the templates with the closest magnification factor. Measure leg length difference Using a line connecting the tear drops and a line connecting the upper or lower edges of the lesser trochanters. The femoral, acetabular, or combined origin of length difference is identified. Identify the stage of femoral loosening, an essential step The SOFCOT classification is the best-adapted classification, with perhaps an additional stage III subdivision depending on the involvement in terms of height (this point is developed in the section on therapeutic indications). The LINEA Anatomic revision implant is not recommended for stage IV cases. Assess the quality of bone support Evaluate not only the pathological hip, but also the healthy hip: trabecular pattern (SINGH), corticomedullary index, flare index, lateral femoral curvature ++. Surgical Technique Linea Anatomic Revision Implant UHRT101 2

5 Identify high risk lesions Metaphyseal curvatures suspected by tracing the axis of the canal (frontal and sagittal); are indicative of severe loosening; can be limited superior metaphyseal curvatures (varus, retroversion caused by implant motion) or complete curves involving the entire loosening area. Bone discontinuities Perforations, microfractures, and fractures that can reach the greater trochanter, the isthmus or the diaphysis; they are easily aggravated by implant ablation. Granulomas Caused by osteolysis; granulomas weaken the bone cortices in involved zones and present a risk of intraoperative fracture. 2. Reconstructing the acetabulum Reconstruction in the anatomic position (height/lateralization) should be preferred. Positioning the test acetabulum high either as originally or deliberately, can only be suggested for a patient with limited functional needs. The hip s new center of rotation is then determined. 3 Surgical Technique UHRT101

6 3. Choosing and positioning the femoral implant The choice of the cementless femoral implant size is crucial: it is even more difficult than with first-intention implantation and requires time and care. The aspects of the choice differ greatly depending on whether an endofemoral approach or a femoral flap is decided upon. Endofemoral approach Standard cases The choice of an implant with optimal and non-maximal metaphyseal filling is based on three essential factors: Metaphyseal volume: the largest contact area should be achieved in the remodeled anchoring zone (metaphysis isthmus, proximal diaphysis), 3 5 cm under the lesser trochanter. Distal diaphyseal diameter: the optimal stem diameter is normaly 1 mm smaller than the diameter of the femoral canal. Position of the center of the femoral head : it should be, in principle, at the same level as the top of the greater trochanter. A special case: oversizing In certain stage III enlarged, but aligned or in elderly persons with a wide femoral canal and bone cortices of mediocre quality, isthmic anchoring zone should be much wider (at least 5 cm below the lesser trochanter). In certain cases, an implant whose size is greater in the metaphysis may be preferred, which requires distal reaming one or two sizes larger. Distance C Distance C is measured from the medial tray of the implant to the summit of the lesser trochanter to verify insertion if the femur is intact. Surgical Technique Linea Anatomic Revision Implant UHRT101 4

7 Transfemoral approach The choice of the component is made preoperatively. Absolute indications: stage III +, significant metaphyseal curvatures, remodeled bone implant interface. Relative indications: predictable extraction problems with risk of worsening lesions (adherent cement, fragile cortices, loosened subsided implants, very distal cement plugs, varus stem position). Choice of femoral component in cases of transfemoral approach requires a methodical analysis in several stages. The minimum flap height required for implant extraction should be determined. This is distance V: summit of the greater trochanter, lower extremity of the flap. The femoral implant should be chosen for best diaphyseal adaptation Distal diameter of the stem 1 mm less than the medullary canal. Insertion distance R separates the 2/3 of the rasp (shaded transition on the illustration) from the lower extremity of the flap: this is a practical surgical landmark to be used with an extended flap. It is advisable to respect a sufficient insertion length E to guide the stem and preserve the safety distance. This safety distance S should be greater than or equal to the medullary canal and it is measured between the most proximal interlocking screw and the lower edge of the flap. V S R T C E However, proper matching with the metaphysis should be verified: do not oversize this. A flap requires an interlocking system: using the template, the number of interlocking screws, their position, and their length are specified. The choice of the size of the femoral implant in cementless revisions is more difficult than firstline implantation, particularly if a femoral flap is planned. 5 Surgical Technique UHRT101

8 4. Refining reconstruction It is possible to alter the correction of the difference in length by the choice of the neck length. Drawing a horizontal line from the center of the femoral head retained checks its position in relation to the summit of the greater trochanter (vertical distance T). In addition, adequate lateralization can restore the lever arm of the gluteus muscles (contralateral reference: the distance between the vertical axis of the template lowered from the center of the femoral head and the femoral axis). At this stage, it is very important to anticipate stability and not hesitate to modify the acetabulum or femur choices. Surgical Technique Linea Anatomic Revision Implant UHRT101 6

9 RECONSTRUCTING THE FEMUR: THE 4 STAGES OF FEMORAL REVISION 5. PHASE 1 : Implants exposure and ablation Excellent exposure is necessary for implants ablation: it is essential not to worsen the femoral bone lesions during this ablation. The choice of the approach should take into account: - previous approaches, - whether loosening is bipolar, - operator s training and preferences, - type of femoral bone approach, - the particular surgical difficulties anticipated during preoperative planning stage, The posteroexternal approach is usually preferred. Exteriorization of the upper extremity of the femur is indispensable whatever approach is chosen. Resection of the capsular fibrosis, even if the acetabular component is not revised, facilitates this exteriorization. The possibility of flexion, internal rotation make it possible to work within the femoral canal axis. Two very different options are presented for this ablation: - endofemoral surgery (femur closed), - femoral flap (open femur). The choice of the option must be made during preoperative planning, keeping in mind that: - endofemoral surgery, whenever possible, should be preferred: the metaphysis should never be sacrificed to facilitate exposure. - The flap option chosen intraoperatively is a failure due to poorly prepared surgery. It necessarily promotes poor surgical conditions. 7 Surgical Technique UHRT101

10 5. PHASE 1 : Implant exposure and ablation (continued) Endocavitary surgery This method should be favored: preferably with the patient in the lateral decubitus position, possibly with the image intensifier (for periodic verification, aiming arm, sterile drape). After implant ablation, the cement is extracted in 3 stages: metaphyseal, isthmic, distal. Opening the trochanter wide Sufficient opening is necessary for working on the femur axis, sclerosis is removed using the bone rongeur or the reamer. Outside the canal axis, this manoeuvre makes vertical positioning of the cement bone interface possible so that cement removal can be started using adapted small files. Ablation of isthmic and diaphyseal cement When removing the cement, it s important to always be in alignment with the femoral axis, and avoid misdirections due to well-fixed patches of cement. Well-adapted instrumentation is indispensable: - long, thin chisels with moderate counter curvature to prevent perforations; - fine suction tube and optic light cable penetrating well into the femur, for good intramedullary viewing; - sometimes rigid hand reamers, more rarely flexible reamers, can complete the chisel work; - motorized instruments, sometimes advised, should be used with utmost caution because of the risk of excentric work, going off course, as well as fractures. Surgical Technique Linea Anatomic Revision Implant UHRT101 8

11 The distal plug Patience, method, and perseverance on the part of the operator in most cases provide problem-free distal plug work. This is where the image intensifier is the most useful: - a long and thin drill (4.5 cm) is centered in the plug with AP and lateral verification. - if the drill is poorly centered, correct the centering using a power reamer, - the diameter of the drills is then increased until it is possible to insert a flexible reamer stem guide or straight, long, and thin reamers; caution should be exercised to prevent excentric reaming, - bone curettes or cement scrapers can be used to remove residual cement. The intramedullary canal must be checked with instruments or radiographically to ensure that it is empty of all cement. Complements of the endofemoral approach Temporary final cerclage 1 to 2 cerclages (or slightly tightened cables) can be encircled preventively around the metaphysis or the isthmus if there is risk of fracture (osteolysis, osteoporosis with adherent cement) Trochanterotomy Infrequently used, trochanterotomy is useful in certain indications: - Fragile trochanter: a well-controlled trochanterotomy is better than an unforeseen surgical incident. - The loosened impacted implant with a high risk of fracture during its ablation. - Metaphyseal curvature (in both planes): anteroposterior varus, lateral retroversion (or both); this gives direct preoperative AP and lateral access in the axis of the canal). Chandler s trochanteric slide osteotomy (preserving the continuity of the gluteus muscles and the vastus lateralis). 9 Surgical Technique UHRT101

12 5. PHASE 1 : Implant exposure and ablation (continued) Enlarged trochanterotomy or mini-flap (Paprosky type) is preferred by some, prolonging the resection along the lateral side of the femur; reinsertion is thus facilitated. Trochanterotomies are designed to allow working in the femoral axis. Diaphyseal window Preferentially planned preoperatively, this window is lateral or anterolateral; Its limits (2 4 cm) are made with a drill; it is cut in wedge shape to facilitate its placement (± metallic circle); It will be bridged by the revision implant s distal stem (at least 2 diameters larger); Its best indications are: - substantial varus of a cemented implant with no major metaphyseal deformity, - a distal cement plug that is difficult to acces. At this stage, verification that the medullary canal is completely empty is indispensable with careful interventional verification, with the image intensifier or better yet, with good-quality x-ray. Surgical Technique Linea Anatomic Revision Implant UHRT101 10

13 The transfemoral approach The flap procedure, planned beforehand, must be clearly codified. This uses a classical anteroexternal flap such as the Wagner flap. Previous ablation of the femoral implant from its cement molding facilitates this approach. The distance V is measured between the summit of the greater trochanter and the distal limit of the stem; placement of a drill bit or landmark is a wise precaution. The vastus lateralis is disinserted from the intermuscular septum to the linea aspera, which may have been decorticated. Make the first cut far posteriorly with an ascillating saw. This cut ends above the trochanteric fossa. The distal limit of the flap is cut with the oscillating saw between the two drilled holes. This operation can be performed using a small-diameter drill which engages the far cortex. If the implant is voluminous in the diaphysis, it is prudent to prepare the opposite cortex with a thin osteotome inserted through the muscles, making multiples thin perforations (creating a dotted line). Including the entire greater trochanter, the flap is then tipped around the intact muscle insertions. The flap is carefully mobilized and moved away to prevent its fracture. Forceps protection of the femoral flap diaphysis junction prevents secondary fractures. When ablation has been completed, the degree of ovalization of the femoral metaphysis is assessed, which is difficult on preoperative x-rays: the physiological femoral anteversion must be clearly identified. The stage of implant loosening must again be determined, whether or not it is identical to the stage indicated during the preoperative planning. The result of this reclassification after implant and cement ablation can modify the therapeutic options planned. 11 Surgical Technique UHRT101

14 6. PHASE 2 : Acetabulum reconstruction If the acetabulum must be reconstructed, it must be planned at this stage: the position of the joint s new center of rotation can influence the choices for femoral reconstruction. Reconstruction of a center of rotation in the anatomical position is always recommended. 7. PHASE 3 : Femoral preparation Femoral sizing Use of trial centering rodes with increasing diameters (ø mm) can be used to map the intramedullary canal. These trials are screwed onto the centering guide and inserted using a graduated centering rod impactor. One should always begin by the smallest diameters to prevent premature jamming. Compared to the data from the preoperative planning stage, this mapping step can anticipate possible risks in femoral preparation, always delicate with cementless implants. Use of trial rasps Starting point The smallest size trial rasp/prosthesis must be used to start, leaving the centering rod in place, centered in the canal. Cautious descent One should begin in the canal s axis (avoiding varus), carefully controlling anteversion (watching out for metaphysis ovalization) until reaching the planned size. Distal reaming is sometimes indicated in this step - either planned preoperatively in view of substantial metaphyseal filling, - or necessary intraoperatively because of unforeseen jamming of the rasp. After again ensuring that the intramedullary canal is free of obstacles (thus avoiding the risk of excentric reaming), the rasps and reamers are used alternatively until the desired size is attained. Surgical Technique Linea Anatomic Revision Implant UHRT101 12

15 Oversizing is dangerous In case of jamming before attaining the size planned, radiological verification is highly recommended to determine the cause. Rasp insertion and stability tests Endofemoral surgery The rasp is impacted (reasonably!) avoiding varus and anteversion error, until it firmly jams, which should correspond to the planned height (distance). Using a rasp handle, the rotational stability of the assembly is tested; if doubt persists, the option of an additional distal interlocking system is preferred to placing a larger implant and the accompanying risk of fracture. At this stage, the utility of bone graft fillers (autografts/allografts) can be determined, anterior and internal, if the bone walls remain distant from the implant (> 2 mm). Femoral flap Although difficult, anteversion is verified in relation to knee flexion: mark the proper orientation with a vertical landmark on the external cortex of the femur. Insertion should take into account the flap length (distance V). The best landmark is the trial rasp s impaction landmark (which should be measured with a sterile ruler - distance R). The primary stability of this rasp should be just sufficient to hold against only manual impaction and rotation forces. Interlocking is mandatory with a flap. 20 mm 13 Surgical Technique UHRT101

16 Kinematic tests Kinematic tests are possible using the modular necks of different adapted lengths on the trial rasp/ prothesis left in place. The position of the center of the femoral head can be checked in relation to the summit of the greater trochanter using a horizontal broach in the trial head (distance T) or the trial neck. Make sure that adequate range of motion is achieved. Most particularly, the stability of the new joint in all the sectors of mobility should be tested. This step is vital: postrevision instability is frequent and difficult to manage. 8. PHASE 4 : The final implant and its optional locking Nonlocking implant The implant is progressively descended and its insertion at the neck stump should be equivalent to the insertion of the trial rasp (upper limit of HAP coating). Final and directional impaction is carried out with the specific stem impactor. The descent should be gentle and cautious. The interlocking implant: assembling the interlocking instrumentation Standard cases The final implant and the interlocking instrumentation are interlocked before any impaction. The surgeon has been careful to: - manually tighten the interlocking screws connecting the interlocking instrument to the implant. - check that the holes of the support piece match the implant holes. Special cases The guide can be mounted after final implant impaction and the new joint reduced. This assembly, implant in place, can be made difficult by the location and volume of the greater trochanter. Surgical Technique Linea Anatomic Revision Implant UHRT101 14

17 Impaction The assembly is progressively impacted in compliance with the planned anteversion. - If the femur is intact: distances C (lesser trochanter) and T (greater trochanter) are reliable landmarks. - With a flap: use the insertion landmark R between the limit of the implant s HAP coating and the lower limit of the flap. Interlocking procedure The joint is reduced with the trial head in place. The transversal gap of the adjustable interlocking guide varies depending on the volume of the soft tissues. The guide is brought as close as possible to the skin or the interlocking site in case of transfemoral approach. It is tightened with a hex screwdriver, ensuring the system s rigidity. It is important not to hold or lean on the device as soon as it is put in place. Guide placement The mobile guide is then mounted on the interlocking guide and should show the number corresponding to the prosthesis size in the notch provided for this purpose. 15 Surgical Technique UHRT101

18 The first drill bush, mounted on the awl, is inserted into the proximal hole until it makes contact with the skin. Interlocking The proximal hole is first drilled with the longest drill. This drill is left in place and the two distal holes are drilled with the second, shorter drill; it will be maintained in the last hole for maximum stability. The awl point and the teeth of each bush allow an approach to bone contact, facilitating passage through the soft tissues and the grip on the cortex. The first drill and its guide are withdrawn from the proximal hole to tap in the first cortex. The awl is removed, the drill bush is left in place, and the next two drill bushes are placed using the same procedure. The interlocking screw length is measured. The interlocking screw is placed using a hex screwdriver with its handle mounted in place. After withdrawing this detachable handle, the screwdriver axis is maintained on the screw to guarantee optimal stability. The two distal interlocking screws are then placed in the same way. Surgical Technique Linea Anatomic Revision Implant UHRT101 16

19 Checking the interlocking system Optimal anchoring for the three interlocking screws on the external cortex is checked (retightening). At this stage, the length and the position of the interlocking screws should be checked with the image intensifier. Then the vertical and transversal bars can be successively withdrawn from the interlocking instrument and the final femoral head put in place and the joint reduced. Closing the flap Trial closure The surgeon should check that the cortical bone is in contact with the implant, in case of significant metaphyseal deformity. At this stage, osteoclasia of the femur s internal cortical bone can be discussed to approach the internal valve. Some use morselized autografts in the junction zone or in contact with the valves. Reattachment of the flap The flap is reattached using two or three cerclages wires or cables (depending on the length), carefully tightened to prevent bone necrosis, particularly if the valves are porotic. In this case, a vertical cerclage sutture anchored in the internal cortex or under the lesser trochanter can be used; it prevents the risk of secondary ascension of the flap s external valve. 17 Surgical Technique UHRT101

20 9. Operative recovery Good recover Cases with good recovery show good bone quality with mechanically satisfactory assembly. However: Postoperative caution for 6 weeks - Walking with two canes and partial weightbearing (20%) - Avoid rotational solicitations (stairs, rising from a chair, etc.) Full weightbearing at the 7 th week - If the radiological follow-up is satisfactory at this date, full weightbearing is authorized while retaining one cane. Follow-up at the 3 rd month (x-rays) decides on the patient s complete return to activities. Difficult recovery If the bone quality is mediocre or if a femoral flap was performed, primary stability will not be as good. Follow-up visits are spaced identically, but return to weightbearing is progressive and cautious. Crutches with no weightbearing for 6 weeks. Then two canes and partial weightbearing until the 3 rd month. Full weightbearing with one contralateral cane until 6 th month. Unlocking Unlocking is a simple intervention that should not be envisioned until the 12 th month provided the clinical and radiological signs permit it: local distal femoral discomfort but certain and longlasting proximal stability, with indisputable radiological signs of metaphyseal locking of the revision implant. Surgical Technique Linea Anatomic Revision Implant UHRT101 18

21 INSTRUMENTS LINEA BOX Ref YKAH25 Stem impactor MGH020 Head impactor MGH021 M6 extractor attachment MGH026 Tip LINEA for trial rasp MGH027 Hexagonal screwdriver MGH022 Neck for 12/14 taper Ø 22 MZC Ø 28 MZC * First thin rasp MGH023 Extractor attachment for neck clamp MGH025 Stem extractor MGH024 Extractor adaptor screw MGH028 * made to order 19 Surgical Technique UHRT101

22 INSTRUMENTS BOX 1 LINEA REVISION/RECONSTRUCTION IMPLANT Ref YKAH342 Trial rasp impactor (x2) MGH016 Right anatomic revision rasp MLI 800* Left anatomic revision rasp MLI 900* * made to order Surgical Technique Linea Anatomic Revision Implant UHRT101 20

23 INSTRUMENTS BOX 2 LINEA REVISION/RECONSTRUCTION IMPLANT Ref YKAH343 Interlocking instrumentation MLI822 Mobile size guide MLI823 Tap for Ø 6 mm interlocking screw MLI826 Interlocking support cover MLI834 Interlocking screw length gauge MLI827 Drill, diameter 4.5 mm, Lg. 250 mm MLI833 (x2) Lg. 190 mm MLI832 Hexagonal screwdriver rod /3.5 across flat (x2) MLI828 Screw holding clamp MLI803 Awl MLI824 Centering rod impactor MLI821 Drill bush (x3) MLI825 Screwdriver handle MLI829 Centering rod MLI820 Centering trial plug Ø 10 mm -> 18 mm MLI811 -> MLI Surgical Technique UHRT101

24 IMPLANTS Stem Linea anatomic revision implant 2/3 HAP Stem Linea anatomic revision implant All HAP left RIGHT left RIGHT N 5* HLI640 N 5* HLI630 N 6 HLI641 N 6 HLI631 N 7 HLI642 N 7 HLI632 N 8 HLI643 N 8 HLI633 N 9 HLI644 N 9 HLI634 N 10 HLI645 N 10 HLI635 N 5* HLI660 N 5* HLI650 N 6 HLI661 N 6 HLI651 N 7 HLI662 N 7 HLI652 N 8 HLI663 N 8 HLI653 N 9 HLI664 N 9 HLI654 N 10 HLI665 N 10 HLI655 * Noninterlocking and made to order Heads Ø SHORT MEDIUM LONG EXTRA-LONG MeTAL COCR CERAMIC BIOLOX DELTA 22, HZC HZC HZC281 0 HZC HZC HZC HZC321 0 HZC HZC ,5 HZL020 0 HZL ,5 HZL HZL023 0 HZL HZL HZL026 0 HZL HZL INTERLOCKING INTERLOCKING SCREWS - Ø 6 MM LENGTH LENGTH 15 VLI VLI VLI VLI VLI VLI VLI VLI650 UHRT rue Lavoisier, Montbonnot, Saint Ismier Cedex. France - Tel: +33 (04) Fax: +33 (0)