Vanguard MPartial Knee. Lateral and Medial Surgical Technique

Transcription

1 Vanguard MPartial Knee Lateral and Medial Surgical Technique

2 One Surgeon. One Patient. Over 1 million times per year, Biomet helps one surgeon provide personalized care to one patient. The science and art of medical care is to provide the right solution for each individual patient. This requires clinical mastery, a human connection between the surgeon and the patient, and the right tools for each situation. At Biomet, we strive to view our work through the eyes of one surgeon and one patient. We treat every solution we provide as if it s meant for a family member. Our approach to innovation creates real solutions that assist each surgeon in the delivery of durable personalized care to each patient, whether that solution requires a minimallyinvasive surgical technique, advanced biomaterials, or a custom, patient-matched implant. When one surgeon connects with one patient to provide personalized care, the promise of medicine is fulfilled.

3 Vanguard M Partial Knee Contents Patient Selection... 2 Pre-operative X-rays... 2 Open vs Minimally Invasive Technique... 2 Lateral Compartment Replacement... 4 Positioning the Limb... 4 Incision... 4 Osteophyte Excision... 5 Tibial Plateau Resection... 6 Femoral Drill Holes... 9 Positioning the Femoral Drill Guide...12 Femoral Saw Cut...15 First Milling of the Condyle...17 Equalizing the Flexion and Extension Gaps...19 Confirming Equality of the Flexion Gaps...20 Final Preparation of the Tibial Plateau...21 Reducing Impingement...25 Final Trial Reduction...26 Cementing the Components (Two-stage Technique)...27 Medial Compartment Replacement...28 Positioning the Limb...28 Incision...28 Osteophyte Excision...30 Tibial Plateau Resection...31 Femoral Drill Holes...36 Positioning the Femoral Drill Guide...38 Femoral Saw Cut...39 First Milling of the Condyle...42 Equalizing the Flexion and Extension Gaps...43 Confirming Equality of the Flexion and Extension Gaps...44 Final Preparation of the Tibial Plateau...45 Reducing Impingement...49 Final Trial Reduction...50 Cementing the Components (Two-stage Technique)

4 Vanguard M Partial Knee Preoperative Planning Figure 1 Figure 2 Preoperative Planning Choose the femoral component size preoperatively using the X-ray template (Figure 1). Apply the template outlines to the X-ray image of the appropriate condyle. A lateral radiograph is required for medial compartment operation. When operating on the lateral compartment, use medial radiograph. The line along the central peg of the implant should be parallel with the long axis of the femoral shaft. The outer surface of the diagrammatic component should lie about 2 mm outside the radiographic image to allow for articular cartilage thickness. The posterior facet of the prosthesis should extend to, but not beyond, the superior margin of the posterior articular facet of the femur (Figure 2). A medium-sized femoral component is appropriate for most patients with medial disease. However, in small women or in the lateral compartment, it is better to employ the small size and in large men, the large size. The extra small and extra large are only needed in very small women and very large men, respectively. Open vs. Minimally Invasive Technique One advantage of unicompartmental arthroplasty is that it can be performed through a small incision without dislocating the patella, thus avoiding damage to the synovial reflections of the suprapatellar pouch. This reduces postoperative pain and allows more rapid and complete recovery of flexion. 1 Vanguard M partial knee operation can be performed through a small incision with great precision. Surgeons learning the procedure, however, can safely extend the soft tissue incision beyond the limits described here with very little increase in postoperative morbidity, as long as the integrity of the suprapatellar pouch is respected. The open approach, with dislocation of the patella, is not recommended. The instrumentation is designed for use through a small incision, and intraoperative dislocation of the patella distorts the ligaments which may make the operation more difficult to perform. This surgical technique is utilized by Keith Berend, M.D. Biomet as the manufacturer of this device, does not practice medicine and does not recommend this device or technique. Each surgeon is responsible for determining the appropriate device and technique to utilize on each individual patient. 2

5 Lateral Compartment Replacement Vanguard M Partial Knee

6 Vanguard M Partial Knee Lateral Compartment Replacement Figure 3 Figure 4 Positioning the Limb Inflate a thigh tourniquet and place the draped leg on a thigh support. The knee must be free to flex at least 90 degrees and preferably 120 degrees or more (Figure 3). The thigh support must not be placed in the popliteal fossa as this will increase the risk of damage to the popliteal vessels. Incision Make a lateral parapatellar incision or midline incision from just above the superior lateral edge of the patella extending distally below the lateral joint line (Figure 4). Deepen the incision through the joint capsule. Resect 4 5 mm of the lateral patellar edge with a sagittal saw. This improves access to the lateral femoral condyle, but may not be necessary in all cases. Do not release any fibers of the lateral collateral ligament. Surgeons who are learning the technique should make a larger incision to improve the exposure. The patella should be subluxed but not dislocated. Excise part of the retropatellar fat pad and insert retractors into the synovial cavity. The soft tissue surrounding the knee can now be inspected to ascertain that it is complete and sufficient. (Incomplete or deficient soft tissue is a contraindication and the operation should be abandoned in favor of a total knee replacement). 4

7 Figure 5 Figure 6 Osteophyte Excision All osteophytes must be removed from the lateral margin of the lateral femoral condyle and from both margins of the intercondylar notch (Figure 5). The assistant extends and flexes the knee, moving the incision up and down, allowing the various osteophytes to come into view. Osteophytes on the tibial plateau in front of the insertion of the ACL and in the top of the notch must be removed to allow the fixed flexion deformity to correct. If there are large osteophytes around the patella they should also be removed. With a narrow chisel (6 mm), remove the osteophytes from beneath the lateral collateral ligament (Figure 6) and from the posterolateral margin of the lateral condyle. This creates room to insert the saw blade into the intercondylar notch during the next step. 5

8 Vanguard M Partial Knee Lateral Compartment Replacement Figure 7 Figure 8 Tibial Plateau Resection Expose the front of the tibia in the lower part of the wound from the tibial tubercle to the rim of the plateau and Gehrty s tubercle. Excise as much of the lateral meniscus as possible in both planes (Figure 7). The ankle piece should be pointing towards the anterior superior iliac spine. The tibial saw guide has 7 degrees of posterior slope built in. The track of articulation on the lateral femoral condyle is internally rotated. Therefore, the component must be internally rotated to allow for accurate femoral articulation. Use the right medial resection guide for the left lateral tibial plateau and vice versa. Manipulate the upper end of the guide so that its face lies against the exposed bone. A recess accommodates the skin and the patellar tendon medially (Figures 8). 6

9 Figure 9 Figure 10 Tibial Plateau Resection (cont.) The saw cut should pass 2-3 mm below the deepest part of erosion unless erosion is very deep. Fix the guide to the bone with nails passed through the lower set of holes in the tibial cut head. One nail should have a head, while the other should be headless (Figure 9). Advance the saw vertically down until it rests on the surface plateau of the saw guide (Figure 10). The saw must remain parallel to the guide. Use a reciprocating saw with a stiff, narrow blade to make the vertical tibial cut. The presence of the patellar tendon may cause external rotation of the cut. Expose the anterior surface of the patellar tendon. Make a vertical splice into the mid-patellar tendon. Insert a stiff sagittal saw through the patellar tendon above the tibial plateau. This allows correct internal rotation of the tibial component in cases where the patellar tendon is tight and visualization is difficult. The saw cut should be just lateral to the apex of the lateral tibial spine. Point the blade toward the anterior superior iliac spine or flexion plane. 7

10 Vanguard M Partial Knee Lateral Compartment Replacement Figure 11 Figure 12 Tibial Plateau Resection (cont.) Use a 12 mm wide oscillating saw blade to excise the plateau (Figure 11). Ensure that the blade freely moves to the back of the joint. When the plateau is loose, lever it up with a broad osteotome and remove. Excise and remove remaining soft tissue attachments posteriorly with a knife. Use the excised plateau with the tibial templates to choose the tibial implant size. Place templates of the opposite side on the cut surface of the excised plateau to choose the best fit. This is routinely a size A or B for women and B or C for men. The thickness of bone removed from the tibia must be enough to accommodate (at least) the thinnest tibial component. As the lateral side is normally more lax in flexion, the surgeon may want to balance this to 2 mm larger than anticipated. To check that sufficient bone has been excised, insert the tibial template and a 5 mm feeler gauge; or 7 mm feeler gauge if the surgeon desires slight laxity in flexion (Figure 12). Note: Whenever a feeler gauge is used to measure a gap, remove the retractors. If left in, they will tighten the soft tissues, which artificially diminishes the gap. 8

11 Figure 13 Figure 14 Tibial Plateau Resection (cont.) If the 5 mm feeler gauge (or 7 mm feeler gauge) cannot be inserted or feels tight, then excise more bone from the tibia. To remove more bone from the tibia, remove the headed nail and the tibial resector. Replace the tibial guide with the headless nail passing through one of the upper holes. Then replace the headed nail in its original bone hole, which displaces the saw guide 3 mm distally (Figure 13). Remove an additional layer of bone and then recheck the gap with the tibial template in place to ensure that the 5 mm feeler gauge can now be easily inserted. Femoral Drill Holes With the knee in about 45 degrees of flexion, make a hole in the intramedullary canal of the femur with the 4 mm drill. This should be completed with the 5 mm awl (Figure 14). If the tibial component of appropriate width appears short, consider repeating the vertical cut 2-3 mm further medial so a wider and longer component may be used. 9

12 Vanguard M Partial Knee Lateral Compartment Replacement Figure 15 Figure 16 Femoral Drill Holes (cont.) The hole must be situated 1cm anteriorly to the anterolateral corner of the intercondylar notch (Figure 15). Insert the I/M rod until its shoulder stops against the bone (Figure 16). 10

13 Figure 17 Figure 18 Femoral Drill Holes (cont.) Alternatively, extramedullary alignment may be used if the patellar tendon is tight or exposure is difficult (Figures 17 and 18). 11

14 Vanguard M Partial Knee Lateral Compartment Replacement Incorrect Placement Figure 19 Figure 20 Femoral Drill Holes (cont.) Flex the knee to 90 degrees. This must be done with care as the lateral border of the patella may abut the I/M rod. Replace the tibial template, insert the femoral drill guide and place a 4 mm feeler gauge between them (Figure 19). Tibial plateau resection ensured that enough tibial bone had been removed to accommodate the tibial template and at least a 5 mm (or 7 mm) feeler gauge. Note: The shoe of the femoral drill guide is 1 mm thick. Therefore, at least a 4 mm feeler gauge can be inserted. If the 4 mm feeler gauge is too loose, insert a thicker feeler gauge until desired tightness is achieved. Positioning the Femoral Drill Guide When viewed from the top, the tendency is to align the medial side of the seven degree fin of the drill handle with the I/M rod. This is incorrect for the lateral side guide (Figure 20). If aligned this way, the tibial template and feeler gauge will be excessively rotated internally, causing the femoral alignment guide and component to be malpositioned. The lateral side of the guide is used for lateral unicompartmental knee arthroplasty (UKA). 12

15 Figure 21 Figure 22 Positioning the Femoral Drill Guide (cont.) When viewed from the front, manipulate the femoral drill guide until it is in the middle of the condyle. Align the handle parallel with the long axis of the tibia and at a right angle to the horizontal tibial plateau. By internally and externally rotating the tibia, make the lateral surface of the seven degree fin of the drill guide parallel with the I/M rod when viewed from above (Figure 22). The anterior face of the femoral drill guide must touch the femoral condyle (Figure 21). By adjusting the degree of flexion, make the upper surface of the drill guide lie parallel with the I/M rod when viewed from the side (Figure 21). 13

16 Vanguard M Partial Knee Lateral Compartment Replacement Figure 23 Positioning the Femoral Drill Guide (cont.) Pass the 4 mm drill through the upper hole in the guide. Drill into the bone to its depth stop and leave in place. Confirm alignments. Advance the 6 mm drill through the second hole in the guide until its depth stop (Figure 23). Remove both drills and all instrumentation from the joint. The I/M rod can be removed with the rod removal hook. 14

17 Figure 24 Figure 25 Femoral Saw Cut Insert the femoral saw block of corresponding size and color into the drilled holes and tap home (Figure 24). Using the 12 mm broad sagittal saw, excise the posterior facet of the femoral condyle, guiding the blade against the underside of the saw block (Figure 25). Take care to avoid damaging the lateral collateral and anterior cruciate ligaments. Avoid undercutting or over resecting the posterior condyle by keeping the saw parallel to the posterior resection guide. Remove the saw block with the slap hammer extractor, taking care not to distort the drill holes. There is now sufficient access to the back of the joint and any remnants of the medial meniscus should be completely removed. 15

18 Vanguard M Partial Knee Lateral Compartment Replacement Before advancing to the following surgical steps, consult the special note below. Special Note The numbers marked on the feeler gauges and the meniscal bearings represent their minimum thicknesses in millimeters. The scale of numbers of the spigots is in 1 mm increments, in inverse ratio to the thickness of their flanges. The spigots must be used as described below: First Milling The 0 spigot is designed to automatically remove sufficient bone to allow the femoral component to seat. This amount varies with the degree of arthritic erosion of the condyle. Second Milling Spigots 1 to 7 allow bone to be removed in measured quantities (in mm) from the level of the first mill cut. Thus, the number 3 spigot removes 3 mm, the number 4, 4 mm, etc. Subsequent Milling If the last spigot used was a number 3, a number 4 spigot will remove an additional 1 mm of bone (i.e. a total of 4 mm since the first milling). However, if the last spigot used was a number 4, a number 5 spigot is required to remove 1 mm of bone (i.e. a total thickness of 5 mm since the first milling). Remember: The spigot number represents the total thickness of bone it removes from the level of the first mill cut. 16

19 First Milling of the Condyle Figure 26 Figure 27 Insert the 0 spigot (it has the thickest flange) into the large drill hole and tap it home until its flange abuts the bone (Figure 26). By slightly extending the knee and retracting the soft tissues, maneuver the spherical cutter of corresponding size and color onto the spigot (Figure 27) and into the wound so that its teeth touch the bone (Figure 28). Take care to avoid trapping soft tissues or milling the anterior portion of the tibia. 17

20 Vanguard M Partial Knee Lateral Compartment Replacement Figure 28 Figure 29 First Milling of the Condyle (cont.) When milling, push firmly in the direction of the axis of the spigot, taking care not to tilt the tool. Mill until the cutter will no longer advance and the spigot can be seen in the window to have reached its end stop. Remove the mill and spigot and trim off the bone protruding from the posterior corners of the condyle, found outside the periphery of the cutting teeth (Figure 29). Note: The numbers on the feeler gauges match the numbers on the tibial components. For example, if a C template is in place and the 6 mm feeler gauge is a good fit, then a C6 tibial component will also be a good fit. 18

21 Figure 30 Figure 31 Equalizing the Flexion and Extension Gaps With the leg in 90 degrees of flexion, insert the tibial template and apply the femoral trial component of corresponding size and color to the milled condyle, tapping it home with the femoral impactor. Step A Remove all retractors. Carefully measure the flexion gap at 90 degrees of flexion with the feeler gauges (Figure 30). (Tibial Plateau Resection has already ensured that the gap is wide enough to accept at least the 5 mm feeler gauge.) The feeler gauge thickness is correct when natural tension in the ligaments is achieved and it will slide in and out easily without tilting. Tension between two fingers is usually sufficient to remove the feeler gauge if the gap is well balanced. Step B Remove the feeler gauge. It is important to remove this before extending the knee because the extension gap is always narrower than the flexion gap at this stage. If left in place, the gauge may stretch or rupture the ligaments as the knee extends. Step C Measure the extension gap in 20 degrees of flexion,not full extension (Figure 31). In full extension, the posterior capsule is tight and its influence gives a false under-measurement. The extension gap is usually less than 4 mm so use the metal feeler gauges (1, 2 and 3 mm thicknesses) to measure it. If the thinnest feeler gauge cannot be inserted, the gap is 0 mm. The formula for balancing the flexion and extension gaps is as follows: Flexion Gap (mm) Extension Gap (mm) = Thickness of bone to be milled from femur (mm) = Spigot number to be used 19

22 Vanguard M Partial Knee Lateral Compartment Replacement Figure 32 Figure 33 Equalizing the Flexion and Extension Gaps (cont.) If the flexion gap measured 5 mm and the extension gap 2 mm, then the amount of bone to be milled is 3 mm. To achieve this, insert a number 3 spigot and mill until the cutter stops advancing. After each milling, it is necessary to remove the bone at the posterior corners of the condyle (Figure 29). Also, if the circular disc of bone under the flange of the spigot is more than 1 mm thick, it should be removed. The reference for the spigot will not be lost as its tip continues to reference off the bottom of the drill hole. Confirming Equality of the Flexion and Extension Gaps Re-measure the flexion and extension gaps with the tibial template and the femoral trial component in place. The flexion and extension gaps should be equal. The thickness of the feeler gauge, which fits both gaps, indicates the thickness of the tibial component to be used (Figures 32 and 33). If the extension gap (at 20 degrees of flexion) is still smaller than the flexion gap, re-measure both gaps and use the mill to remove more bone. This can be done 1 mm at a time by using the sequence of spigots. Note: In the example above, an additional 1 mm of bone could be removed by using a No. 4 spigot. Usually the knee is balanced with a 3, 4 or 5 spigot. 20

23 Figure 34 Figure 35 Final Preparation of the Tibial Plateau Insert the chosen size tibial template and position its posterior margin flush with the posterior tibial cortex. Facilitate this by passing a small hook over the posterior margin of the tibia (Figure 34). Saw Blade Options When preparing the 10 mm deep slot for the tibial keel, use the keel-cut saw blade (Figure 35). 21

24 Vanguard M Partial Knee Lateral Compartment Replacement Figure 36 Figure 37 Final Preparation of the Tibial Plateau (cont.) Introduce the saw into the front of the slot until sunk to its shoulder (Figure 36). In soft bone, the saw can be driven to the back of the slot. In hard bone, the saw may need to be partially lifted out of the slot before being driven to the back of the slot. Once the saw cuts are complete, remove the tibial template and complete the slot by carefully using the tibial gauge. Use of Drill/Nail Puller The vibration from the keel-cut saw may cause the tibial template to move (Figure 37). To combat the vibration, use the drill/nail puller to hold the tibial nail in place while sawing. 22

25 Figure 38 Figure 39 Remove the tibial template and transfixing tibial nail. Excavate the groove to the correct depth by scooping out the bone with the blade of the tibial gouge, taking care not to damage the anterior and posterior cortices (Figures 38 and 39). 23

26 Vanguard M Partial Knee Lateral Compartment Replacement Figure 40 Final Preparation of the Tibial Plateau (cont.) Insert the tibial trial component and tap home with the tibial impactor (Figure 40). The tibial trial component should be flush to the bone and its posterior margin should extend to the back of the tibia. During impaction of the tibial implant, the leg should be supported with a hand under the foot to avoid damage to knee ligaments. Only a light hammer should be used to avoid the risk of plateau fracture. Remove the tibial trial component once confirmed that it sits flush to the bone. 24

27 Figure 41 Figure 42 Reducing Impingement Final preparation of the femur requires trimming of the condyle anteriorly and posteriorly to reduce the risk of impingement of bone against the polyethylene bearing surface in full extension and full flexion. Use a chisel to remove anterior bone until there is at least 4 mm of clearance between the bone and the polyethylene in full extension (Figure 42). Apply the femoral posterior trimming block of corresponding size and color to the condyle and use the osteophyte chisel to remove any posterior osteophytes (Figure 41). Take care not to damage the capsule. 25

28 Vanguard M Partial Knee Lateral Compartment Replacement Figure 43 Figure 44 Figure 45 Final Trial Reduction Insert the femoral trial component and fully seat it using the femoral impactor (Figure 43). Reinsert the chosen tibial trial component (Figure 44). Manipulate the knee through a full range of motion to demonstrate stability of the joint and absence of impingement (Figure 45). The thickness of the tibial component should restore the ligaments to their natural tension. Note: Take care not to overcorrect the knee into varus or damage the LCL by inserting too thick of a tibial component. 26

29 Figure 46 Figure 47 Cementing the Components (Two-stage Technique) Roughen the femoral and tibial surfaces by making multiple small drill holes with the cement key drill (Figure 46). Tibial Component Place a small amount of cement on the tibial bone surface and flatten to produce a thin layer. Insert the component and press down, first posteriorly and then anteriorly, so that excess cement is squeezed out at the front. Use the rightangled tibial impactor (with a small hammer) to complete the insertion. Remove excess cement with a small curette from the margins of the component. Insert the femoral trial component and pressurize the cement. During setting, hold the leg in 45 degrees of flexion. Do not fully extend the leg, as pressure in this position may tilt the tibial component anteriorly. When the cement has set, remove the trial femoral component and cement that may have extruded. Femoral Component Push a small amount of cement into the large femoral drill hole and load the concave surface of the femoral component with cement. Apply the loaded component to the condyle and impact with the femoral impactor held at 45 degrees to the long axis of the femur. Remove excess cement from the margins with a knife and a small curette. Pressurize the cement as it sets and hold the leg in 45 degrees of flexion as explained previously. Close the wound in routine fashion. 27

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31 Medial Compartment Replacement Vanguard M Partial Knee

32 Vanguard M Partial Knee Medial Compartment Replacement Figure 48 Figure 49 Positioning the Limb Inflate a thigh tourniquet and place the draped leg on a thigh support. The knee must be free to flex at least 90 degrees and preferably 120 degrees or more (Figure 48). The thigh support must not be placed in the popliteal fossa as this will increase the risk of damage to the popliteal vessels. Incision Make a medial parapatellar incision or midline incision from just above the superior medial edge of the patella extending distally below the medial joint line (Figure 49). Deepen the incision through the joint capsule. Resect 4 5 mm of the medial patellar edge with a sagittal saw. This improves access to the medial femoral condyle, but may not be necessary in all cases. Do not release any fibers of the medial comedial ligament. Surgeons who are learning the technique should make a larger incision to improve the exposure. The patella should be subluxed but not dislocated. Excise part of the retropatellar fat pad and insert retractors into the synovial cavity. The soft tissue surrounding the knee can now be inspected to ascertain that it is complete and sufficient. (Absence of functioning soft tissue is a contraindication. Incomplete or deficient soft tissue is a contraindication and the operation should be abandoned in favor of a total knee replacement.. 30

33 Figure 50 Figure 51 Osteophyte Excision All osteophytes must be removed from the medial margin of the medial femoral condyle and from both margins of the intercondylar notch (Figure 50). The assistant extends and flexes the knee, moving the incision up and down, allowing the various osteophytes to come into view. Osteophytes on the tibial plateau in front of the insertion of the ACL and in the top of the notch must be removed to allow the fixed flexion deformity to correct. If there are large osteophytes around the patella they should also be removed. With a narrow chisel (6 mm), remove the osteophytes from beneath the medial collateral ligament (Figure 51) and from the posteromedial margin of the medial condyle. This creates room to insert the saw blade into the intercondylar notch during the next step. 31

34 Vanguard M Partial Knee Medial Compartment Replacement Figure 52 Figure 53 Tibial Plateau Resection Expose the front of the tibia in the lower part of the wound from the tibial tubercle to the rim of the plateau and Gehrty s tubercle. Excise as much of the medial meniscus as possible. Apply the tibial saw guide with its shaft parallel with the long axis of the tibia in both planes. The ankle piece should be pointing towards the anterior superior iliac spine. The tibial saw guide has 7 degrees of posterior slope built in. The track of articulation on the medial femoral condyle is internally rotated. Therefore, the component must be internally rotated to allow for accurate femoral articulation. Use the right medial resection guide for the left medial tibial plateau and vice versa. Manipulate the upper end of the guide so that its face lies against the exposed bone. A recess accommodates the skin and the patellar tendon medially (Figures 52 and 53). 32

35 Figure 54 Figure 55 Tibial Plateau Resection (cont.) The saw cut should pass 2 3 mm below the deepest part of erosion unless erosion is very deep. Fix the guide to the bone with nails passed through the lower set of holes in the tibial cut head. One nail should have a head, while the other should be headless (Figure 54). Advance the saw vertically down until it rests on the surface plateau of the saw guide (Figure 55). The saw must remain parallel to the guide. Use a reciprocating saw with a stiff, narrow blade to make the vertical tibial cut. The presence of the patellar tendon may cause external rotation of the cut. Expose the anterior surface of the patellar tendon. Make a vertical splice into the mid-patellar tendon. Insert a stiff sagittal saw through the patellar tendon above the tibial plateau. This allows correct internal rotation of the tibial component in cases where the patellar tendon is tight and visualization is difficult. The saw cut should be just medial to the apex of the medial tibial spine. Point the blade toward the anterior superior iliac spine or flexion plane. 33

36 Vanguard M Partial Knee Medial Compartment Replacement Figure 56 Figure 57 Tibial Plateau Resection (cont.) Use a 12 mm wide oscillating saw blade to excise the plateau (Figure 56). Ensure that the blade freely moves to the back of the joint. When the plateau is loose, lever it up with a broad osteotome and remove. Excise and remove remaining soft tissue attachments posteriorly with a knife. Use the excised plateau with the tibial templates to choose the tibial implant size. Place templates of the opposite side on the cut surface of the excised plateau to choose the best fit. This is routinely a size A or B for women and B or C for men. The thickness of bone removed from the tibia must be enough to accommodate (at least) the thinnest tibial component. To check that sufficient bone has been excised, insert the tibial template and a 5 mm feeler gauge (Figure 57). Note: Whenever a feeler gauge is used to measure a gap, remove the retractors. If left in, they will tighten the soft tissues, which artificially diminishes the gap. 34

37 Figure 58 Figure 59 Tibial Plateau Resection (cont.) If the 5 mm feeler gauge cannot be inserted or feels tight, then excise more bone from the tibia. To remove more bone from the tibia, remove the headed nail and the tibial resector. Replace the tibial guide with the headless nail passing through one of the upper holes. Then replace the headed nail in its original bone hole, which displaces the saw guide 3 mm distally (Figure 58). Remove an additional layer of bone and then recheck the gap with the tibial template in place to ensure that the 5 mm feeler gauge can now be easily inserted. Femoral Drill Holes With the knee in about 45 degrees of flexion, make a hole in the intramedullary canal of the femur with the 4 mm drill. This should be completed with the 5 mm awl (Figure 59). If the tibial component of appropriate width appears short, consider repeating the vertical cut 2-3 mm further medial so a wider and longer component may be used. 35

38 Vanguard M Partial Knee Medial Compartment Replacement Figure 60 Figure 61 Femoral Drill Holes (cont.) With the knee in about 45 degrees of flexion, make a hole in the intramedullary canal of the femur with the 4 mm drill. This should be completed with the 5 mm awl (Figure 60). The hole must be situated 1cm anteriorly to the anteromedial corner of the intercondylar notch (Figure 61). 36

39 Figure 62 Figure 63 Femoral Drill Holes (cont.) Insert the I/M rod until its shoulder stops against the bone (Figure 62). Flex the knee to 90 degrees. This must be done with care as the medial border of the patella abuts the rod. Replace the tibial template, insert the femoral drill guide and place a feeler gauge 1 mm smaller than the measured flexion gap between them (5 mm gap=4 mm feeler gauge and femoral alignment guide) (Figure 63). The femoral drill guide size and color should correspond with the templated size of the femoral component to be used. Tibial plateau resection ensured that enough tibial bone had been removed to accommodate the tibial template and at least a 5 mm feeler gauge. Note: The shoe of the femoral drill guide is 1 mm thick therefore at least a 4 mm feeler gauge can be inserted. The feeler gauge should be 1 mm thinner than the feeler gauge used to ensure adequate bone resection of the tibia. When viewed from the front, manipulate the femoral drill guide until it is in the middle of the condyle. Align the handle parallel with the long axis of the tibia at a right angle to the horizontal tibial plateau (Figure 63). 37

40 Vanguard M Partial Knee Figure 64 Figure 65 Positioning the Femoral Drill Guide (cont.) The anterior face of the femoral drill guide must touch the femoral condyle (Figure 64). By adjusting the degree of flexion, make the upper surface of the drill guide lie parallel with the I/M rod when viewed from the side (Figure 64). By internally and externally rotating the tibia, make the medial surface of the seven degree fin of the drill guide parallel with the I/M rod when viewed from above (Figure 65). 38

41 Medial Compartment Replacement Figure 66 Positioning the Femoral Drill Guide (cont.) Pass the 4 mm drill through the upper hole in the guide. Drill into the bone to its depth stop and leave in place. Confirm alignments. Advance the 6 mm drill through the other hole in the guide until its depth stop (Figure 66). Remove both drills and all instrumentation from the joint. The I/M rod can now be removed with the rod removal hook. 39

42 Vanguard M Partial Knee Figure 67 Figure 68 Femoral Saw Cut Insert the femoral saw block of corresponding size and color into the drilled holes and tap home (Figure 67). Using the 12 mm broad sagittal saw, excise the posterior facet of the femoral condyle, guiding the blade against the underside of the saw block (Figure 68). Take care to avoid damaging the medial comedial and anterior cruciate ligaments. Avoid undercutting or over resecting the posterior condyle by keeping the saw parallel to the posterior resection guide. Remove the saw block with the slap hammer extractor, taking care not to distort the drill holes. There is now sufficient access to the back of the joint and any remnants of the medial meniscus should be completely removed. 40

43 Medial Compartment Replacement Before advancing to the following surgical steps, consult the special note below. Special Note The numbers marked on the feeler gauges and the meniscal bearings represent their minimum thicknesses in millimeters. The scale of numbers of the spigots is in 1 mm increments, in inverse ratio to the thickness of their flanges. The spigots must be used as described below: First Milling The 0 spigot is designed to automatically remove sufficient bone to allow the femoral component to seat. This amount varies with the degree of arthritic erosion of the condyle. Second Milling Spigots 1 to 7 allow bone to be removed in measured quantities (in mm) from the level of the first mill cut. Thus, the number 3 spigot removes 3 mm, the number 4, 4 mm, etc. Subsequent Milling If the last spigot used was a number 3, a number 4 spigot will remove an additional 1 mm of bone (i.e. a total of 4 mm since the first milling). However, if the last spigot used was a number 4, a number 5 spigot is required to remove 1 mm of bone (i.e. a total thickness of 5 mm since the first milling). Remember: The spigot number represents the total thickness of bone it removes from the level of the first mill cut. 41

44 Vanguard M Partial Knee Medial Compartment Replacement Figure 68 Figure 69 Figure 70 First Milling of the Condyle Insert the 0 spigot (the thickest flange) into the large drill hole and tap it home until its flange abuts the bone (Figure 68). By slightly extending the knee and retracting the soft tissues, maneuver the spherical cutter of corresponding size and color onto the spigot (Figure 69) and into the wound so that its teeth touch the bone. Take care to avoid trapping soft tissues. When milling, push firmly in the direction of the axis of the spigot, taking care not to tilt the tool. Mill until the cutter will no longer advance. Remove the mill and spigot and trim off the bone protruding from the posterior corners of the condyle, found outside the periphery of the cutting teeth (Figure 70). Note: The spigot number represents the total thickness of bone it removes from the level of the first mill cut. The numbers on the feeler gauges match the numbers on the tibial components. For example, if a C template is in place and the 6 mm feeler gauge is a good fit, then a C6 tibial component will also be a good fit. 42

45 Vanguard M Partial Knee Medial Compartment Replacement Figure 71 Figure 72 Equalizing the Flexion and Extension Gaps With the leg in 90 degrees of flexion, insert the tibial template and apply the femoral trial component of corresponding size and color to the milled condyle, tapping it home with the femoral impactor. Step A Remove all retractors. Carefully measure the flexion gap at 90 degrees of flexion with the feeler gauges (Figure 71). (Tibial Plateau Resection has already ensured that the gap is wide enough to accept at least the 5 mm feeler gauge.) The feeler gauge thickness is correct when natural tension in the ligaments is achieved and it will slide in and out easily without tilting. Tension between two fingers is usually sufficient to remove the feeler gauge if the gap is well balanced. Step B Remove the feeler gauge. It is important to remove this before extending the knee because the extension gap is always narrower than the flexion gap at this stage. If left in place, the gauge may stretch or rupture the ligaments as the knee extends. Step C Measure the extension gap in 20 degrees of flexion, not full extension (Figure 72). In full extension, the posterior capsule is tight and its influence gives a false undermeasurement. The extension gap is usually less than 4 mm so use the metal feeler gauges (1, 2 and 3 mm thicknesses) to measure it. If the thinnest feeler gauge cannot be inserted, the gap is 0 mm. The formula for balancing the flexion and extension gaps is as follows: Flexion Gap (mm) Extension Gap (mm) = Thickness of bone to be milled from femur (mm) = Spigot number to be used 43

46 Vanguard M Partial Knee Figure 73 Figure 74 Equalizing the Flexion and Extension Gaps (cont.) If the flexion gap measured 5 mm and the extension gap 2 mm, then the amount of bone to be milled is 3 mm. To achieve this, insert a number 3 spigot and mill until the cutter stops advancing. After each milling, it is necessary to remove the bone at the posterior corners of the condyle (Figure 76). Also, if the circular disc of bone under the flange of the spigot is more than 1 mm thick, it should be removed. The reference for the spigot will not be lost as its tip continues to reference off the bottom of the drill hole. Confirming Equality of the Flexion and Extension Gaps Re-measure the flexion and extension gaps with the tibial template and the femoral trial component in place. The flexion and extension gaps should be equal. The thickness of the feeler gauge, which fits both gaps, indicates the thickness of the tibial component to be used (Figures 73 and 74). If the extension gap (at 20 degrees of flexion) is still smaller than the flexion gap, re-measure both gaps and use the mill to remove more bone. This can be done 1 mm at a time by using the sequence of spigots. The knee is usually balanced with a No. 3, 4 or 5 spigot. Note: In the example above, an additional 1 mm of bone could be removed by using a No. 4 spigot. 44

47 Medial Compartment Replacement Figure 75 Figure 76 Final Preparation of the Tibial Plateau Insert the chosen size tibial template and position its posterior margin flush with the posterior tibial cortex. Facilitate this by passing a small hook over the posterior margin of the tibia (Figure 75). Saw Blade Options When preparing the 10 mm deep slot for the tibial keel, use the keel-cut saw blade (Figure 76). 45

48 Vanguard M Partial Knee Figure 77 Figure 78 Final Preparation of the Tibial Plateau (cont.) Introduce the saw into the front of the slot until sunk to its shoulder (Figure 77). In soft bone, the saw can be driven to the back of the slot. In hard bone, the saw may need to be partially lifted out of the slot before being driven to the back of the slot. Once the saw cuts are complete, remove the tibial template and complete the slot by carefully using the tibial gauge. Use of Drill/Nail Puller The vibration from the keel-cut saw may cause the tibial template to move (Figure 78). To combat the vibration, use the drill/nail puller to hold the tibial nail in place while sawing. 46

49 Medial Compartment Replacement Figure 79 Figure 80 Final Preparation of the Tibial Plateau (cont.) Remove the tibial template and transfixing tibial nail. Excavate the groove to the correct depth by scooping out the bone with the blade of the tibial gouge, taking care not to damage the anterior and posterior cortices (Figures 79 and 80). Insert the tibial trial component and tap home with the tibial impactor. The tibial trial component should be flush to the bone and its posterior margin should extend to the back of the tibia. During impaction of the tibial implant, the leg should be supported with a hand under the foot to avoid damage to knee ligaments. Only a light hammer should be used to avoid the risk of plateau fracture. Remove the tibial trial component once confirmed that it sits flush to the bone. 47

50 Vanguard M Partial Knee Figure 81 Figure 82 Reducing Impingement Final preparation of the femur requires trimming of the condyle anteriorly and posteriorly to reduce the risk of impingement of bone against the polyethylene bearing surface in full extension and full flexion. Use a chisel to remove anterior bone until there is at least 4 mm of clearance between the bone and the polyethylene in full extension (Figure 82). Apply the femoral posterior trimming block of corresponding size and color to the condyle and use the osteophyte chisel to remove any posterior osteophytes (Figure 81). Take care not to damage the capsule. 48

51 Medial Compartment Replacement Figure 83 Figure 84 Figure 85 Final Trial Reduction Insert the femoral trial component and fully seat it using the femoral impactor (Figure 83). Reinsert the chosen tibial trial component (Figure 84). Manipulate the knee through a full range of motion to demonstrate stability of the joint and absence of impingement (Figure 85). The thickness of the tibial component should restore the ligaments to their natural tension. When a valgus force is applied to the knee the artificial joint surfaces should distract 1 2 mm. Complete this test with the knee in 20 degrees of flexion. In full extension, the bearing will be fully gripped because of the tight posterior capsule. Note: Take care not to overcorrect the knee into valgus or damage the MCL by inserting too thick a tibial component. 49

52 Vanguard M Partial Knee Figure 86 Figure 87 Cementing the Components (Two-stage Technique) Roughen the femoral and tibial surfaces by making multiple small drill holes with the cement key drill (Figure 86). Tibial Component Place a small amount of cement on the tibial bone surface and flatten to produce a thin layer. Insert the component and press down, first posteriorly and then anteriorly, so that excess cement is squeezed out at the front. Use the rightangled tibial impactor (with a small hammer) to complete the insertion. Remove excess cement with a small curette from the margins of the component. Insert the femoral trial component and pressurize the cement. During setting, hold the leg in 45 degrees of flexion. Do not fully extend the leg, as pressure in this position may tilt the tibial component anteriorly. When the cement has set, remove the trial femoral component and cement that may have extruded. Femoral Component Push a small amount of cement into the large femoral drill hole and load the concave surface of the femoral component with cement. Apply the loaded component to the condyle and impact with the femoral impactor held at 45 degrees to the long axis of the femur. Remove excess cement from the margins with a knife and a small curette. Pressurize the cement as it sets and hold the leg in 45 degrees of flexion as explained previously (Figure 87). Close the wound in routine fashion. 50

53 Biomet Orthopedics P.O. Box 587 Date: 10/06 56 East Bell Drive Warsaw, Indiana USA Biomet Unicondylar Knee Joint Replacement Prostheses ATTENTION OPERATING SURGEON DESCRIPTION The Unicondylar Knee Joint Replacement Prosthesis incorporates a low profile cobalt chromium or titanium femoral component and three styles of tibial components. The three styles of tibial components available include an all-polyethylene, a modular metal-backed component, and a single-piece, polyethylene/metal-backed component. Reconstruction with this implant rebalances the knee utilizing the remaining undisturbed compartmental structures and appropriate soft tissue tensions as reference points. Materials Femoral Components CoCrMo Alloy/Titanium Alloy Tibial Components ArCom UHMWPE/Tantalum/ Titanium/CoCrMo Alloy Tibial Plates Titanium Alloy INDICATIONS Partial replacement of the articulating surfaces of the knee when only one side of the joint is affected due to the compartmental primary degenerative or post-traumatic degenerative disease, previous tibial condyle or plateau fractures, deformity or revision of previous arthroplasty. These devices are single-use implants intended for implantation with bone cement. CONTRAINDICATIONS Absolute contraindications include: infection, sepsis, and osteomyelitis. Relative contraindications include: 1) uncooperative patient or patient with neurologic disorders who are incapable of following directions, 2) osteoporosis, 3) metabolic disorders which may impair bone formation, 4) osteomalacia, 5) distant foci of infections which may spread to the implant site, 6) rapid joint destruction, marked bone loss or bone resorption apparent on roentgenogram, 7) vascular insufficiency, muscular atrophy, neuromuscular disease, 8) incomplete or deficient soft tissue surrounding the knee. WARNINGS Improper selection, placement, positioning, alignment and/or fixation of the implant components may result in unusual stress conditions which may lead to subsequent reduction in the service life of the prosthetic components. Malalignment of the components or inaccurate implantation can lead to excessive wear and/or failure of the implant or procedure. Inadequate preclosure cleaning (removal of surgical debris) can lead to excessive wear. Improper preoperative or intraoperative implant handling or damage (scratches, dents, etc.) can lead to crevice corrosion, fretting, fatigue fracture, and/or excessive wear. Use clean gloves when handling implants. Laboratory testing indicates that implants subjected to body fluids, surgical debris, or fatty tissue have lower adhesion strength to cement than implants handled with clean gloves. Do not modify implants. The surgeon is to be thoroughly familiar with the implants, instruments, and surgical technique prior to performing surgery. 1. The all-polyethylene and the single-piece polyethylene/metal-backed tibial components are designed to be used in treatment of low demand, less active sedentary patients. Patients that will remain active and/or overweight patients are not candidates for all- polyethylene and/or single-piece polyethylene/metal-backed tibial components. 2. Malalignment or soft tissue imbalance can place inordinate forces on the components, which may cause excessive wear to the patellar or tibial bearing articulating surfaces. Revision surgery may be required. 3. Care is to be taken to assure complete support of all parts of the device embedded in bone cement to prevent stress concentrations, which may lead to failure of the procedure. Complete preclosure cleaning and removal of bone cement debris, metallic debris, and other surgical debris at the implant site is critical to minimize wear of the implant articular surfaces. Implant fracture due to cement failure has been reported. implantation of the prosthetic components. The use of instruments or implant components from other systems can result in inaccurate fit, sizing, excessive wear, and/or device failure. Intraoperative fracture or breaking of instruments has been reported. Surgical instruments are subject to wear with normal usage. Instruments that have experienced extensive use or excessive force are susceptible to fracture. Surgical instruments should only be used for their intended purpose. Biomet recommends that all instruments be regularly inspected for wear and disfigurement. Do not reuse implants. While an implant may appear undamaged, previous stress may have created imperfections that would reduce the service life of the implant. Do not treat patients with implants that have been placed, even if momentarily, in a different patient. POSSIBLE ADVERSE EFFECTS 1. Material sensitivity reactions. Implantation of foreign material in tissues can result in histological reactions involving various sizes of macrophages and fibroblasts. The clinical significance of this effect is uncertain, as similar changes may occur as a precursor to or during the healing process. Particulate wear debris and discoloration from metallic and polyethylene components of joint implants may be present in adjacent tissue or fluid. It has been reported that wear debris may initiate a cellular response resulting in osteolysis or osteolysis may be a result of loosening of the implant. 2. Early or late postoperative infection and/or allergic reaction. 3. Intraoperative bone perforation or fracture may occur particularly in the presence of poor bone stock caused by osteoporosis, bone defects from previous surgery, or bone resorption. 4. Loosening and/or migration/subsidence of the implants can occur due to loss of fixation, trauma, malalignment, bone resorption, and/or excessive activity. 5. Periarticular calcification or ossification, with or without impediment of joint mobility. 6. Inadequate range of motion due to improper selection or positioning of components. 7. Undesirable shortening of limb. 8. Dislocation and subluxation due to inadequate fixation and improper positioning. Muscle and fibrous tissue laxity can also contribute to these conditions. 9. Fatigue fracture of component can occur as a result of loss of fixation/loosening, migration/ subsidence, strenuous activity, malalignment, trauma, non-union, and/or excessive weight. 10. Fretting and crevice corrosion can occur at interfaces between components. 11. Wear and/or deformation of articulating surfaces. 12. Valgus-varus deformity. 13. Transient peroneal palsy secondary to surgical manipulation and increased joint movement has been reported following knee arthroplasty in patients with severe flexion and valgus deformity. 14. Patellar tendon rupture and ligamentous laxity. 15. Intraoperative or postoperative bone fracture and/or postoperative pain. Intraoperative and early postoperative complications can include: 1) damage to blood vessels, 2) temporary or permanent nerve damage resulting in pain or numbness to the affected limb, 3) cardiovascular disorders including venous thrombosis, pulmonary embolism or myocardial infarction, 4) hematoma, and 5) delayed wound healing. STERILITY Prosthetic components are sterilized by exposure to a minimum dose of 25 kgy of gamma radiation. Do not resterilize. Do not use any component from an opened or damaged package. Do not use implants after expiration date. Caution: Federal law (USA) restricts this device to sale by or on the order of a physician. Comments regarding this device can be directed to Attn: Regulatory Dept., P.O. Box 587, Warsaw, IN USA, Fax: Authorized Representative: Biomet U.K., Ltd. Waterton Industrial Estates Bridgend, South Wales CF31 3XA, U.K Biomet joint replacement prostheses provide the surgeon with a means of reducing pain and restoring function for many patients. While these devices are generally successful in attaining these goals, they cannot be expected to withstand the activity levels and loads of normal healthy bone and joint tissue. Accepted practices in postoperative care are important. Failure of the patient to follow postoperative care instructions involving rehabilitation can compromise the success of the procedure. The patient is to be advised of the limitations of the reconstruction and the need for protection of the implants from full load bearing until adequate fixation and healing have occurred. Excessive activity, trauma, and/or weight gain have been implicated with premature failure of the implant by loosening, fracture, and/or wear. All-polyethylene and single-piece, polyethylene/metal-backed implants may fracture due to loosening and/or migration/subsidence. Loosening of the implants can result in increased production of wear particles, as well as accelerate damage to bone making successful revision surgery more difficult. The patient is to be made aware and warned of general surgical risks, possible adverse effects as listed, and to follow the instructions of the treating physician including follow-up visits. PRECAUTIONS Patient selection factors to be considered include: 1) need to obtain pain relief and improve function, 2) ability and willingness of the patient to follow instructions, including control of weight and activity level, 3) a good nutritional state of the patient, and 4) the patient must have reached full skeletal maturity, 5) unicompartmental disease with correctable deformity with minimal to no ligament releases, and 6) intact anterior cruciate ligament. Specialized instruments are designed for Biomet joint replacement systems to aid in the accurate The information contained in this package insert was current on the date this brochure was printed. However, the package insert may have been revised after that date. To obtain a current package insert, please contact Biomet at the contact information provided herein.