DFS Hip Distractor. Surgical Technique

Transcription

1 DFS Hip Distractor Surgical Technique

2 Contents Introduction... Page 1 Hip Distractor Associated... Page 2 Components And Instrumentation Radiographs... Page 4 Fixator Orientation... Page 5 Initial Screw Placement... Page 6 Remaining Proximal Screw Insertion... Page 7 Distal Assembly... Page 8 Distal Bone Screw Insertion... Page 9 Necessary Outriggers... Page 11 Option 1... Page 12 Option 2... Page 13 Flexion... Page 14 Distraction... Page 14 Post-Operative Care... Page 15 Problems/Solutions... Page 15 Suggested Screw Site Care... Page 16 Further Information... Page 17

3 Introduction The DFS Hip Distractor provides unloading of the hip joint while permitting free range of motion. This treatment has very specific applications and should be performed only in cases where off loading the joint is expected to provide a distinct advantage in patient treatment. Hinged distraction arthroplasty is a treatment modality commonly associated with Avascular Necrosis of the femoral head, Legg-Calves-Perthes Disease, chondrolysis, protection of the joint after femoral head fracture, and after labral reconstruction. Dynamic Joint Distraction has proven effective for several joints such as the elbow and ankle for secondary arthritis. Off loading the joint while allowing cartilage nutrition and healing of the subchondral bone may restore a functioning joint surface in processes such as Osteonecrosis and Chondrolysis. After femoral head fracture or labral reconstruction joint distraction and movement will allow healing while preventing stiffness. The DFS Hip Distractor is comprised of three basic components: 1) Hip Distractor clamp (PN-01220) 2) Construx Fixator (PN-01801) 3) Bone screw clamps for hip clamp (PN-06240) 4) Accessory components to build outriggers are also available. With the exception of the Hip Distractor clamp, these components hold similarities to other Biomet Trauma components. This clamp is unique due to its hemi-arc shape, which offers variable bone screw placement, and most importantly due to its ability to distract up to 5cm. The key attribute of this system is in its ability to distract proximally and not distally. When distracting from the proximal end of the device the hinge maintains its orientation to the femoral head, which serves as the center of rotation of the joint. If one were to distract from the distal end of the fixator, the center of rotation would be fixated on the hip socket and not the femur. Therefore the fixator ultimately would articulate off center. 1

4 Hip Distractor Associated Components And Instrumentation Part # Description Construx Fixator Hip Distractor Clamp Hip Distraction CD Wrench* mm Allen Wrench* mm Wire Guide* mm Bone Clamp* Soft Tissue Clamp / Template* Angulating Screw Clamp Trocar T-Wrench for Bone Screws Soft Tissue Guide 100mm mm Drill Guide mm Drill Bit 240mm mm Drill Guide mm Drill Bit 200mm *Included with

5 Part # Description mm Supplemental Carbon Rod (x2) Supplemental Bone Screw Clamp (x4) Part # Description Vision MRI Safe Pin-To-Bar Clamp (x2) or SL Rapid 6.0 mm Screw Clamp Part # Description mm Carbon Rod or mm Carbon Rod 3

6 Radiographs The patient should be placed supine on the radiolucent table, with a small bolster under the affected hip. The fluoroscope should be positioned so that an appropriate A/P and lateral images can be taken with minimal effort (NOTE: Expect to use several sterile covers for the fluoroscope head as it will be used for both lateral and A/P projections). The center of the femoral head is judged to be the center of rotation for the hip. Under fluoroscopic guidance, the center of the femoral head is found and marked. If the femoral head is collapsed and does not appear as a true sphere, the center should be assumed at the center of the femoral head as though the head was complete and intact. A line from the top of the greater trochanter to the center of the femoral head in neutral hip position is marked as well using a 2.0 mm k-wire. This newly marked point is the center of rotation for the hip, our hinge will be located at this point. 4

7 Fixator Orientation The center of the pivot body is cannulated (2.0mm), depicting the center of rotation for the fixator. The pivot body assembly should now be placed over the k-wire used to identify the center of rotation for the joint. The proximal bone screws can now be placed. The fixator should be pre-spaced away from the patient to contend with any swelling or pistoning of the soft tissue that may occur during treatment. Before drilling your first proximal bone screw, the degree (if any) of abduction should be determined. If 10 of abduction is preferred, the bone screw must be abducted before it is placed (i.e. superolateral to inferomedial). The first screw should be templated through the proximal clamp. To avoid soft tissue damage, templates are provided. The templates look very similar to the bone screw holding clamps but are designed to hold soft tissue guides, whereas the bone screw clamps cannot. If the templates are used, they should be exchanged for the actual clamps only after all proximal clamp bone screws are placed. 5

8 Initial Screw Placement With the templates and soft tissue guides (PN-03085) in place, the first screw is ready to be placed. Using a drill guide (PN ) to center the bit within the soft tissue guide, a 4.8 mm bit (PN-03010) is used to drill into the pelvic wall. The use of fluoroscopy is imperative to assure that over-penetration in not achieved (fluoroscopic Judet views can be utilized to confirm placement). Drill stops are recommended to prevent over-penetration. The first screw placed should be the most anterior screw as bone stock and bone screw placement is more limited in this area. Placement of the proximal bone screws is in the superoacetabular region, and these are placed approximately 2 cm above the joint. The first bone screw should be placed in the desired predetermined abduction or adduction position. After the hole is drilled, the drill guide is removed. The appropriate-length screw is selected and inserted into the template and soft tissue guide. Using a bone screw T-Wrench (PN-03125), the bone screw is inserted two to three threads past the far cortex by turning it clockwise. Judet views can be utilized to prevent over-penetration. NOTE: Care should be taken to avoid over-penetration as the bone screws are tapered and will lose purchase if they are backed out. 6

9 Remaining Proximal Screw Insertion NOTE: Make sure to select bone screws long enough to support the additional outriggers that will be placed on the screws as they protrude from the back of the clamp. It is also recommended to use Hydroxyapatite Coated bone screws for these procedures. The second (and third, if desired) proximal bone screw is templated and placed accordingly, making sure not to force placement through the template and move the hinge (this is reflected by bending the guide pin). In most cases, there will be two bone screws applied anterior to the distraction post and one placed posterior to the post. The remaining bone screws are placed in the same fashion as the first; template, drill, and insert the appropriate bone screw. If the ilium is small and cannot tolerate three bone screws at the same level than one bone screw can be placed 1 cm proximal. A 2.0 mm wire can be utilized to determine if it is safe to place posterior bone screws (i.e. not violating the sciatic notch). 7

10 Distal Assembly Once the proximal bone screws are placed, the distal portion of the fixator, comprised of a Construx Fixator (PN-01801) can be assembled. First remove the bolt connecting the Male knuckle of the fixator to the clamp assembly. This is depicted in the pictures below. Loosen all the locking bolts and setscrews so the fixator can be manipulated freely. If the fixator measures long on the patient, simply remove the necessary number of knuckles until the desired length is achieved. Using the bolt previously used to separate the Construx Fixator from its unused half, attach the Construx Fixator to the rest of the hip distractor assembly on the patient. Telescope the distal clamp on the Construx Fixator approximately 2 cm and lock it in position by tightening the set-screw on the inferior side of the clamp body. The knuckles of the fixator should be in a straight line. 8

11 Distal Bone Screw Insertion Using the fixator as a template, insert two to three soft tissue guides (PN-03085) and place the distal clamp laterally on the femur and parallel to the bone. The femur should be positioned while applying the distal bone screws in the same abduction as the perpendicular proximal bone screws in the ilium. Wire guides can be utilized as demonstrated below to template placement of the bone screws prior to initial drilling. 9

12 Distal Bone Screw Insertion (Continued) Using the 4.8 mm drill guide (PN-03060) and the corresponding drill bit, pre-drilling for the first bone screw can now take place. Bi-cortical penetration is required for this procedure. It is important to pre-drill one hole at a time and then insert the screw. (Do not attempt to pre-drill all three holes and then insert the bone screws.) The most distal bone screw is inserted first, followed by the most proximal, finishing with the third, centrally located bone screw. Once the remaining screws are placed in the recommended sequence, the soft tissue guides are removed. The clamps and fixator knuckles should now be definitively tightened from top to bottom. 10

13 Necessary Outriggers Supplemental bone screw fixation is strongly recommended due to the immense torsional forces being exerted on the bone screw sites. This additional support can be achieved by one of two approaches: 1) The addition of two convergent bone screws placed between the tables of the ilium, or 2) A single bone screw placed anterior-inferior to postero-superior at the level of the anterior inferior iliac spine. 11

14 Necessary Outriggers (Continued) Option 1 In pre-drilling the iliac wing screws, the hole does not need to be drilled deeply. A soft tissue guide, 4.8 mm drill guide, and 4.8 mm drill bit should be used as this size corresponds to the 5.0/6.0 mm bone screws. Both of these bone screws may be placed freehand. The pelvic wall of the iliac wing is very dense, whereas the bone stock within the wall is comprised of cancellous bone. This offers a unique advantage in placing bone screws, as the pelvic wall will guide the bone screws. Once the near cortex is drilled, the screw is inserted and should find its own path. Once the first hole is drilled, the bit and guide are removed and the appropriate bone screw is inserted using a bone screw T-Wrench. The next step is to connect the screws in the iliac wing to the proximal portion of the fixator. For option one, it is easiest to use two 250 mm supplemental bars (PN-13105), and four supplemental clamps (PN-01525) to attach the bars to the shanks of the screws coming out of the proximal clamp and the screw shanks protruding from the iliac wing. A small 150 mm supplemental bar (PN-01515) with two supplemental clamps may also be used to lag the two 300 mm rods together by the wing and add further stability to this Delta-style construct. 12

15 Option 2 Using a soft tissue guide, 4.8 mm drill guide, and 4.8 mm drill bit, the anterior screw is placed. Positioning of this screw should be verified fluoroscopically. This screw should be placed as deep as the surgeon feels is sufficient to provide adequate fixation. Bi-cortical penetration is NOT recommended. Once the bone screw is inserted, the outrigger can be attached. By linking a 150 mm rod (with use of clamps) to the proximal portion of the fixator and to the new screw site, supplemental fixation is achieved. 13

16 Flexion Once the frame is applied, the patient s leg should be flexed and extended under fluoroscopy. If the hinge has been aligned properly, articulation should occur freely. If the limb does not articulate freely, the orientation of the fixator is most likely off axis. There is a trouble-shooting segment at the end of this technique, which may prove helpful. Distraction Once the outriggers are secured in place, the distraction can be performed. Some surgeons may wish to distract their patients gradually; others prefer to perform it intra-operatively and all at once. Regardless, the steps are the same. First loosen the distraction locking set-screw. This is the silver setscrew located on the front of the hip distractor clamp below the distraction nut. Turning the set-screw counterclockwise will loosen it, and clockwise will lock it. Once the set-screw has been loosened, the distraction nut can be turned. Using the distractor wrench (PN-01227), turn the distraction nut counterclockwise (viewing the adjustment nut from top down) until the desired amount of distraction is achieved. When not adjusting the distraction nut always lock it using the setscrew. Distraction may either be done acutely or slowly, to achieve restoration of Shenton s line, distraction typically is between 5.0 mm and 8.0mm. The proximal distractor should be utilized, thereby moving the hinge and the femoral head together and achieving a smooth range of motion, even after distraction. After this is achieved the distractor is locked. 14

17 Post-Operative Care Patient may benefit from postoperative knee CPM (0-30 ) which brings the hip to nearly 70 of flexion An epidural may be utilized with the CPM for initial pain management Antibiotic, bone screw care and showering as per physician protocol Ordinarily patient may weight-bear as tolerated, but this is case-dependant Duration of frame-wear is case-dependent averaging three to five months for avascular necrosis Problems/Solutions Problem Hinge placement is too proximal (or distal), noted prior to applying the femoral bone screws. Solution Simply lengthen or shorten the proximal distractor. In the rare event that the hinge is too distal and there is no more room to shorten the distractor, the problem can be solved by doing a distraction from the femoral clamp after the femoral bone screws have been applied. This will effectively bring the femoral head down to the level of the hinge. Problem After the frame is on, the hinge is too proximal. Solution This is solved by distracting through the proximal distractor and then compressing distally at the femur. This will bring the hinge distally. Once the hinge is aligned, distraction from the proximal device may continue. Problem The hip is not able to be brought into the neutral position prior to surgery. Solution Soft tissue release should be performed prior to pin placement as needed. Problem Post-operatively the patient has a tendency to hold the hip in flexion and may be developing a contracture. Solution Lock frame in extension at night. 15

18 Suggested Screw Site Care At the conclusion of fixator application and fracture reduction, wounds are dressed in routine sterile fashion. Care should be taken to insure all fixator fittings are securely tightened. Dry sterile gauze is wrapped around the shanks of the bone screws to prevent pistoning of the soft tissues on the bone screws. Once wounds have healed and sutures are removed, routine postoperative screw site care is recommended. Screw sites should be monitored during subsequent clinic visits. All fixator fittings should be evaluated for tightness during subsequent clinic visits. 16

19 Further Information This brochure describes the surgical technique used by David S. Feldman, M.D., Chief, Pediatric Orthopedic Surgery NYU & Hospital for Joint Diseases. Biomet Trauma, as the manufacturer of this device, does not practice medicine, a nd does not recommend this product or any specific surgical technique for use on any individual patient. The surgeon who performs any implant procedure is responsible for determining the appropriate product(s) and utilizing the appropriate technique(s) for said implantation in each individual patient. For further information, please contact the Customer Service Department at: Biomet Trauma 56 East Bell Drive P.O. Box 587 Warsaw, Indiana x

20 All trademarks herein are the property of Biomet, Inc. or its subsidiaries unless otherwise indicated. This material is intended for the sole use and benefit of the Biomet sales force and health care professionals. It is not to be redistributed, duplicated or disclosed without the express written consent of Biomet. For product information, including indications, contraindications, warnings, precautions and potential adverse effects, see the package insert and Biomet s website. Responsible Manufacturer Biomet, Inc. P.O. Box E. Bell Drive Warsaw, Indiana USA Rx only Biomet Orthopedics Form No. BMET REV