Medial Patellofemoral Ligament Reconstruction Using a Femoral Loop Button Fixation Technique Jonathan A. Godin, M.D., M.B.A., Vasili Karas, M.D., M.S., Julia D. Visgauss, M.D., and William E. Garrett, M.D., Ph.D.
Abstract: Medial patellofemoral ligament (MPFL) reconstruction is a common procedure used to treat both acute and chronic patellar instability. Although many variations of MPFL reconstruction have been described, there is no consensus regarding the optimal surgical technique. We describe a technique for MPFL reconstruction with a looped gracilis tendon autograft using suture anchors to secure the graft to the patella and a suspensory loop button system for fixation to the femur. This technique replicates the native shape of the MPFL while minimizing the risk of patellar fracture and allowing for gradual tensioning of the graft.
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umerous techniques for reconstruction of the medial patellofemoral ligament (MPFL) have been described, but none stands out as the generally accepted standard of care. Technical variationsdfor example, in the number of graft bundles, graft sources, and fixation methodsdexist, and much has been published on this topic in recent years.1-7 However, because it is known that a nonanatomic reconstruction of the MPFL can lead to nonphysiological patellofemoral loads and kinematics, the goal of surgical intervention must be an anatomic reconstruction predicated on correct identification of the anatomic insertion sites of the MPFL on the patella and femur, secure fixation of the graft to the insertion sites, and appropriate graft tensioning.8 We present a surgical technique for MPFL reconstruction using a looped gracilis tendon with suture anchor patellar fixation and suspensory loop cortical button femoral fixation. The use of a loop button system allows gradual tensioning that can be checked while cycling the knee to find the isometric fixation
point and allowing for optimal tensioning of the graft. The surgical technique, along with step-by-step instructions, is available for viewing in a cadaveric specimen in Video 1. In addition, all specialized instrumentation needed for the procedure is listed in Table 1 and depicted in Figure 1.
From the Department of Orthopaedic Surgery, Duke University, Durham, North Carolina, U.S.A. The authors report the following potential conflict of interest or source of funding: W.E.G. receives support from DJO, GlaxoSmithKline, Arthrex, and RTI. Received March 10, 2015; accepted June 11, 2015. Address correspondence to Jonathan A. Godin, M.D., M.B.A., Department of Orthopaedic Surgery, Duke University, DUMC Box 3000, Durham, NC 27710, U.S.A. E-mail: [email protected] Ó 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved. 2212-6287/15233/$36.00 http://dx.doi.org/10.1016/j.eats.2015.06.005
MPFL Reconstruction The patient is brought to the operating room and positioned supine on the operative table with all bony prominences well padded (Table 2). A thigh tourniquet is placed on the operative extremity; this may or may not be used. At our institution, we prefer to perform the procedure with the patient under regional anesthesia in addition to monitored anesthesia care. It is important to note that the obturator nerve should be blocked if regional anesthesia is administered. General anesthesia may also be used. An examination under anesthesia is
Surgical Technique Preoperative Assessment A thorough history and physical examination should be conducted. Moreover, anteroposterior and lateral radiographs of the affected knee, as well as bilateral sunrise views, should be obtained to detect differences in patellar tilt and alignment. Magnetic resonance imaging is performed to evaluate for articular cartilage injury, identify loose bodies, and rule out associated soft-tissue injuries to the menisci and ligaments. In addition, the tibial tubercleetrochlear groove distance should be calculated and is useful for predicting the need for a tibial tubercle transfer.
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Table 1. Special Equipment and Implants 3.5-mm titanium Corkscrew suture anchors Radiodense template 4.0-mm spade-tipped guide pin Graft-sizing paddle Tenodesis reamer (Arthrex) TightRope No. 2 FiberWire
performed on both knees to allow comparison with the contralateral side. An intravenous antibiotic is administered before incision. The operative extremity is then prepared and draped in sterile fashion. Diagnostic arthroscopy is performed next, with particular attention paid to patellofemoral chondral injuries, dysplasia, alignment, and loose bodies. A lateral retinacular release may be performed as necessary for significant lateral tightness, but we infrequently perform this procedure for instability. At this time, concomitant arthroscopic procedures, such as loose body removal, chondral debridement, abrasion chondroplasty, and microfracture of osteochondral lesions, are performed. After completion of arthroscopy, the tourniquet is insufflated. The knee is marked, with estimation of the locations of the pes anserinus, the midpoint between the medial epicondyle and adductor tubercle, and finally, the superomedial border of the patella. Either an allograft or autograft may be used. If an autograft is selected, then the gracilis or semitendinosus is harvested at this time through a 3-cm longitudinal incision centered over the pes anserinus. Alternatively, a 2-cm transverse or oblique incision can be made over the hamstring tendons in the posteromedial popliteal fossa for a proximal harvest. The graft is then cleaned, measured, and set aside in saline solutionesoaked sponges. The graft should be a minimum of 18 cm in
length and approximately 4 to 5 mm in diameter. Next, the medial patellar border is identified, and a 2-cm skin incision is made from the superomedial corner extending to the center of the medial edge of the patella. Dissection is taken down to expose the medial edge of the patella while staying superficial to the capsule. The surgeon should be sure to maintain the integrity of the periosteal layer because this will be the first, and deepest, layer of closure over the graft fixation on the patellar side. Under fluoroscopic guidance, at a point approximately 3 mm distal to the proximal-medial corner of the patella, the surgeon drills a hole to approximately 15 mm with a 2-mm drill. A second hole is drilled approximately 15 to 20 mm distal and parallel to the first hold (Fig 2). The surgeon should be sure to aim slightly anterior while drilling the holes to avoid joint penetration (Table 3). Alternatively, a 1.1-mm drill tip guide pin may be used to place the patellar fixation sites, and these are then over-drilled. Two 3.5-mm titanium Corkscrew suture anchors (Arthrex, Naples, FL) are placed into the prepared patellar fixation sites. Two 3.5-mm Bio-Corkscrew suture anchors (Arthrex) may be used in place of the titanium suture anchors. Thereafter a soft-tissue tunnel is created between layers 2 and 3 at the level of the MPFL. This tunnel is superficial to the joint capsule (layer 3) but deep to the medial retinaculum and fascia (layer 2). This interval is depicted in Figure 3. The space between the vastus medialis and the capsule is then identified and bluntly developed toward the femoral insertion, leaving the capsule intact. A right-angle clamp is inserted into the prepared layer down to the medial epicondyle, and the tip of the clamp is turned toward the skin. After palpation of the medial femoral condyle, a longitudinal incision of approximately 2 cm is made just anterior to
Fig 1. Instrumentation.
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Table 2. Step-by-Step Surgical Technique Step 1. Position patient 2. Perform examination under anesthesia 3. Perform diagnostic arthroscopy 4. Harvest autograft or thaw allograft 5. Perform medial patellar dissection
6. Prepare medial patella for graft fixation
7. Place Corkscrew suture anchors in patella 8. Create soft-tissue tunnel for graft
9. Identify femoral insertion of MPFL
10. Prepare femoral tunnel for graft fixation
11. Prepare graft (this can be done simultaneously with steps 5-10) 12. Secure patellar limb of graft 13. Pass graft through medial tissue tunnel 14. Deliver TightRope through femoral tunnel
15. Deliver graft through femoral tunnel 16. Tension graft 17. Evaluate reconstruction 18. Perform wound closure
Description Position the patient supine with a tourniquet on the operative extremity. Examine and compare with the contralateral side. Assess for patellofemoral chondral injuries, loose bodies, trochlear dysplasia, and malalignment. Address associated pathologies as indicated. If using autograft, harvest gracilis or semitendinosus and ensure adequate length and diameter (18 cm and 4-5 mm, respectively). If size is not adequate, use allograft. Make a 2-cm skin incision from the superomedial corner to the center of the medial edge of the patella. Dissect through the subcutaneous tissue while staying superficial to the capsule. Drill a hole using a 3.5-mm cannulated reamer to a depth of 15 mm on the medial surface of the patella, just 3 mm distal to the superomedial pole. Drill a second hole 15-20 mm distal and parallel to the first hole. Place two 3.5-mm titanium or bioabsorbable Corkscrew suture anchors into the predrilled patellar holes. Identify the interval between layers 2 and 3 of the medial knee (superficial to joint capsule and deep to medial retinaculum). Using a right-angle or tonsil clamp with the tips turned toward the skin, continue dissection to the medial epicondyle to create a tunnel for the graft. Make a 2-cm incision in the skin just anterior to the medial epicondyle to the depth of the tissue tunnel created. Using fluoroscopy, identify the MPFL insertion on the femur. Anatomically, this is between the medial epicondyle and adductor tubercle, 2 mm anterior and 4 mm distal to the adductor tubercle. Radiographically, this is 1 mm anterior to the posterior femoral cortical line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to the level of the posterior point of the Blumensaat line. Starting at the identified MPFL insertion site, drill the 4-mm Beath pin across the femur, aiming slightly proximal and anterior, exiting at the lateral epicondyle. Ream over the pin to the appropriate graft size, up todbut not throughdthe lateral cortex. Pass the TightRope around the graft, and suture the 2 limbs with about 15 mm of overlap with No. 2 FiberWire to form a loop. Confirm the size of the double-stranded graft (away from the sutured limbs). Tie 1 suture from each of the medial patellar suture anchors around the looped graft (at the portion of the sutured limbs), securing it down to the bone. Using a right-angle or tonsil clamp, bring the TightRope and graft through the tissue tunnel and out of the incision overlying the medial epicondyle. Thread the passing sutures (blue) into the Beath pin, and pull them out of the lateral femur. Pull the sutures to deliver the button through the femoral canal until it is flipped on the lateral cortex. Using a clamp as a pulley on the looped graft to maintain equal tension on the graft limbs, pull the tensioning sutures (white) to deliver the graft into the femoral tunnel. With the knee in 30 of flexion, pull on the tensioning sutures to achieve the desired graft tension. Do not over-tighten. Evaluate the graft tensioning and patellar tracking through full knee ROM. Perform layered closure of soft tissues after thorough irrigation and hemostasis of wounds.
MPFL, medial patellofemoral ligament; ROM, range of motion.
the epicondyle, and dissection is carried down to the level of the previously created soft-tissue tunnel. Next, the femoral insertion site of the MPFL is identified under fluoroscopic guidance. This point is located on a line between the medial femoral epicondyle and the adductor tubercle, approximately 2 mm anterior and 4 mm distal to the adductor tubercle. The radiographic location has been described as 1 mm anterior to the posterior femoral cortical line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to the level of the posterior point of the Blumensaat line on a perfect lateral radiograph of the knee (Fig 4).9 We use a radiodense template (Arthrex) to
confirm positioning. Then, a 4-mm spade-tipped drill pin (Arthrex) is drilled across the femur and out through the lateral femoral cortex at the level of, or slightly proximal to, the lateral epicondyle. The pin should be aimed slightly proximal and anterior to avoid the intercondylar notch and to avoid injury to the neurovascular structures (Fig 5). If the prepared graft diameter is larger than 4 mm, then reaming over the spade-tipped pin with the appropriately sized tenodesis reamer is required for graft placement. This allows for the creation of the tunnel as far as possible to prevent the graft from seizing within the tunnel. Care must be taken so that the reamer does not breach the lateral
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Fig 2. Preparation of drill holes in medial patella. (A) Two parallel holes are drilled on the medial side of the patella through a 2-cm skin incision. (B) Two suture anchors are then passed through each drill hole.
femoral cortex because this may prevent button fixation. The graft is then prepared by passing the TightRope (Arthrex) through 1 end of the graft. Next, the 2 ends of the graft are overlapped approximately 15 mm, and a No. 2 FiberWire (Arthrex) is used to suture the 2 free ends of the graft together to form a loop (Fig 6). One suture should be placed approximately 5 mm from one free end of the overlapped, looped graft, and the second suture should be placed approximately 5 mm from the other free end of the graft. The graft is then sized using a graft-sizing paddle (Arthrex). The looped graft is sutured in place along the medial edge of the patella. One free suture limb from each suture anchor is passed around the looped graft, and the suture limbs are tied down (Fig 7). Next, a right-angle clamp is passed through the soft-tissue tunnel connecting the patellar and femoral incisions to bring the TightRope and graft through the soft-tissue tunnel and out of the incision overlying the medial femoral epicondyle. It is very important to maintain equal tension on both graft bundles during this step to ensure proper biomechanics of the patellofemoral joint. The TightRope sutures are delivered out of the medial incision, and with equal tension on both graft bundles, the graft is pulled down to the medial epicondyle. The TightRope passing sutures (blue) are fed into the eyelet of the spade pin and deliver the suture tails out of the lateral femur before the graft enters the femoral socket. By use of a clamp as a pulley, pre-tensioning of
the graft and insertion into the socket with equal tension on both graft bundles are performed as the TightRope is pulled out of the lateral side. Maintenance of tension on the graft until the TightRope button is flipped on the lateral femoral cortex is key at this time. If the button cannot be flipped because the sutures are too short or if excessive force must be used to flip the button, then the TightRope sutures should be lengthened manually before passing and filling the button. Manual fixation of the lateral patellar facet flush with the lateral femoral condyle is performed with the knee in 30 of flexion. Final fixation can be accomplished by pulling the TightRope’s tightening sutures (white) on the medial side, with alternating tension on each strand (Fig 8). It is crucial that the tensioning sutures are not overtightened because the TightRope cannot be loosened. Over-tightening of the TightRope could result in an overconstrained patellofemoral joint. Tracking and tension of the patella are evaluated throughout knee range of motion (ROM). If any adjustments need to be made, the TightRope can be cut out, tensioning adjustments can be made, and a BTB TightRope or BioComposite Interference Screw (Arthrex) can be used to perform fixation of the graft. The tourniquet is then deflated, and a layered closure is performed. Aftercare Weight bearing is allowed with crutches and a brace locked in extension. Isometric quadriceps strengthening
Table 3. Pearls and Pitfalls Aim anterior when drilling the patellar bone tunnels to avoid intra-articular penetration. The patellar fixation sites should be centered on the lateral plane. When drilling across the distal femur, aim slightly anterior and proximal to prevent neurovascular injury and to protect against violation of the joint and intercondylar notch. Do not ream >4 mm in diameter through the lateral distal femoral cortex. Be sure to pass the TightRope through 1 end of the graft before suturing the graft ends together to form a loop. If the button cannot be flipped because the sutures are too short or if excessive force must be used to flip the button, then lengthen the TightRope sutures manually before passing and filling the button. Confirm with fluoroscopy that the TightRope button is flipped and flush on the lateral femoral cortex. Do not over-tension the graft. Only tighten the white sutures with small increments at a time to prevent over-tensioning.
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Fig 3. Tunnel for graft placement. In the right knee of a male cadaver, proper tunnel dissection for graft placement during medial patellofemoral ligament reconstruction is shown. The tunnel is made between anatomic layers 2 (medial retinaculum and fascia) and 3 (capsule) of the knee. The sutures in the image stem from single-loaded suture anchors already placed in the medial aspect of the patella.
and patellar mobilization exercises are initiated. The use of crutches and brace use are discontinued after 6 weeks. No closed kinetic chain exercises are allowed for 6 weeks. During the first 6 weeks, ROM exercises are
Fig 4. Radiographic placement of femoral starting point. This is a fluoroscopic perfect lateral image of a cadaveric left knee with the radiopaque guide placed on the medial aspect of the knee. The guide is placed in line with the posterior cortex of the femur, with the distal intersection overlying the posteriormost aspect of the Blumensaat line and the proximal intersection over the point at which the posterior cortex meets the medial condyle proximally. The black cross indicates proper placement of the pin.
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Fig 5. Reaming of femoral tunnel. On the basis of the sizing guide, an appropriately sized reamer is selected, and the guide pin is over-reamed beginning at the femoral insertion of the medial patellofemoral ligament. The tunnel is drilled unicortically, with the lateral cortex spared to have a stable resting place for the flipped button.
performed from 0 to 60 of flexion. The hinged knee brace is unlocked for ambulation at 6 weeks postoperatively. Sports training is initiated 3 to 4 months after surgery, and most patients are cleared to return to sports and full activity at 6 months.
Fig 6. Graft preparation. A 20-cm gracilis graft has been prepared and looped within the TightRope. Two knots affix the ends of the graft to form a loop. As shown in Video 1, these knots are placed approximately 2 cm apart by initially passing a suture through both limbs of the graft, looping around the limbs twice, and finally, passing the suture through the free ends of the graft before tying the knot. In this fashion the knot lies between the 2 limbs of the graft. The placement and spacing of knots for affixing the looped graft to the patella are depicted here with the free ends of suture from 2 anchors. These knots should be tied between the graft retention knots.
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Fig 7. Graft fixation to medial patella. After the placement of 2 suture anchors, the graft is sutured to the medial side of the patella. Suturing the graft in the described fashion decreases the interosseous surface area removed from within the patella and may reduce the likelihood of patellar fracture as compared with interference fit.
Discussion The MPFL is an important soft-tissue checkrein of the patellofemoral joint because it provides 50% to 60% of the restraint to lateral patellar displacement from 0 to 30 of knee ROM, when the patella is not yet engaged in the trochlea.10 As such, the MPFL is ruptured in as many as 90% of acute dislocations and is either ruptured or attenuated in almost 100% of recurrent instability cases.11 Anatomic MPFL reconstruction was first described in 1992,12 and a number of techniques have since been reported, including suture repair of the MPFL, the use of autogenous tendon graft sutured to the periosteal and fibrous tissue overlying the patella, autogenous tendon transfer, the use of single patellar tunnels, the use of double transverse patellar tunnels, and the use of suture anchors in shallow patellar tunnels. Although many variations on the surgical technique for MPFL reconstruction have been described, there is no consensus regarding the surgical approach, graft choice, graft positioning, and fixation method. Only a handful of studies have directly compared different surgical techniques, and they suggest that there may be better outcomes when both bundles of the MPFL are reconstructed, as compared with singlebundle reconstruction.13,14 Otherwise, a single superior operative technique has not emerged. Complications associated with surgical intervention include persistence of instability, pain localized to the femoral fixation point, restriction of knee flexion, degeneration of the patellofemoral joint, and patellar fracture. A significant percentage of complications associated with MPFL reconstruction occur because of technical errors, which typically involve improper graft position or tension (or both).15,16 Recurrent instability
can occur when the graft is too loose or if fixation on either the femoral or patellar side fails. Conversely, over-tightening or malpositioning of the graft can lead to maltracking, stiffness, and excessive medial compressive forces.17 Patellar fracture is a major complication after MPFL reconstruction, and this has been described most commonly after techniques involving patellar bone tunnels.16,18-20 We are aware of only 2 described MPFL reconstruction techniques involving suspensory adjustable-loop cortical button femoral fixation,21,22 and this is the first described technique using the TightRope system on the femoral side. Golant et al.21 described knotless suture anchor patellar fixation and the use of a hybrid adjustable-loop cortical button with interference screw fixation on the femoral side. Meanwhile, Nakagawa et al.22 used transpatellar bone tunnels and EndoButton (Smith & Nephew Endoscopy, Andover, MA) patellar fixation with adjustable-loop cortical button femoral fixation. We believe that suture anchor fixation without interference fit on the patellar side minimizes the risk of patellar fracture while providing a reconstruction that exceeds the ultimate load to failure of the native MPFL.10,23 We add suspensory adjustable-loop cortical button fixation of the graft on the femoral side because it allows us to provisionally secure the graft in the femoral tunnel and then gradually adjust graft tension while directly monitoring patellofemoral alignment and stability. Another advantage of this technique is the lack of interference screw fixation on the femoral side. This is especially important when performing MPFL reconstruction in skeletally immature patients because anatomic reconstruction places the femoral tunnel close to the physis. The described MPFL reconstruction technique using a looped, double-bundle graft replicates the native shape of the MPFL while effectively limiting rotation throughout ROM and minimizing postoperative instability. This is a reproducible technique for patellar
Fig 8. Tightening of graft. After graft passage and flipping of the TightRope button, the graft is tightened with alternating pulls on the medial side while tension is kept on the graft with a hemostat through the loop.
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stabilization in patients with acute or recurrent patellar instability that, if performed anatomically, may also provide for more aggressive rehabilitation protocols and an earlier return to activity.24
References 1. Bollier M, Fulkerson J, Cosgarea A, Tanaka M. Technical failure of medial patellofemoral ligament reconstruction. Arthroscopy 2011;27:1153-1159. 2. McCarthy M, Amendola A, Wolf B, Albright J, Bollier M. Femoral tunnel placement in medial patellofemoral ligament reconstruction (SS-76). Arthroscopy 2012;28:e40 (abstr). 3. Joyner P, Roth T, Winnier S, et al. Biomechanical analysis of current medial patellofemoral ligament reconstruction techniques using human gracilis allograft. Arthroscopy 2014;30:e14-e15. 4. Lenschow S, Schliemann B, Gestring J, Herbort M, Schulze M, Kösters C. Medial patellofemoral ligament reconstruction: Fixation strength of 5 different techniques for graft fixation at the patella. Arthroscopy 2013;29:766-773. 5. Fisher B, Nyland J, Brand E, Curtin B. Medial patellofemoral ligament reconstruction for recurrent patellar dislocation: A systematic review including rehabilitation and return-to-sports efficacy. Arthroscopy 2010;26:1384-1394. 6. Song S, Yoo Y, Seo Y. The isometric point for medial patellofemoral ligament reconstruction: An in vivo analysis using 3-dimensional computed tomography (SS-79). Arthroscopy 2012;28:e41-e42 (abstr). 7. Balcarek P, Ammon J, Frosch S, et al. Magnetic resonance imaging characteristics of the medial patellofemoral ligament lesion in acute lateral patellar dislocations considering trochlear dysplasia, patella alta, and tibial tuberosityetrochlear groove distance. Arthroscopy 2010;26:926-935. 8. Amis AA, Firer P, Mourtney J, Senavongse W, Thomas NP. Anatomy and biomechanics of the medial patellofemoral ligament. Knee 2003;10:215-220. 9. Schöttle PB, Schmeling A, Rosenstiel N, Weiler A. Radiographic landmarks for femoral tunnel placement in medial patellofemoral ligament reconstruction. Am J Sports Med 2007;35:801-804. 10. Russ SD, Tompkins M, Nuckley D, Macalena J. Biomechanical comparison of patellar fixation techniques in medial patellofemoral ligament reconstruction. Am J Sports Med 2014;43:195-199. 11. Sallay PI, Poggi J, Speer KP, Garrett WE. Acute dislocation of the patella. A correlative pathoanatomic study. Am J Sports Med 1996;24:52-60.
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12. Ellera Gomes JL. Medial patellofemoral ligament reconstruction for recurrent dislocation of the patella: A preliminary report. Arthroscopy 1992;8:335-340. 13. Kang H, Cao J, Yu D, Zheng Z, Wang F. Comparison of 2 different techniques for anatomic reconstruction of the medial patellofemoral ligament: A prospective randomized study. Am J Sports Med 2013;41:1013-1021. 14. Wang CH, Ma LF, Zhou JW, et al. Double-bundle anatomical versus single-bundle isometric medial patellofemoral ligament reconstruction for patellar dislocation. Int Orthop 2013;37:617-624. 15. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med 2012;40:1916-1923. 16. Parikh SN, Nathan ST, Wall EJ, Eismann EA. Complications of medial patellofemoral ligament reconstruction in young patients. Am J Sports Med 2013;41:1030-1038. 17. Beck P, Brown NA, Greis PE, Burks RT. Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction. Am J Sports Med 2007;35:1557-1563. 18. Mikashima Y, Kimura M, Kobayashi Y, Miyawaki M, Tomatsu T. Clinical results of isolated reconstruction of the medial patellofemoral ligament for recurrent dislocation and subluxation of the patella. Acta Orthop Belg 2006;72:65-71. 19. Lippacher S, Reichel H, Nelitz M. Patellar fracture after patellar stabilization. Orthopade 2010;39:516-518 [in German]. 20. Thaunat M, Erasmus PJ. Recurrent patellar dislocation after medial patellofemoral ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2008;16:40-43. 21. Golant A, Quach T, Rosen J. Medial patellofemoral ligament reconstruction with a looped semitendinosus tendon, using knotless anchor fixation on the patella and hybrid fixation on the femur. Arthrosc Tech 2014;3: e211-e216. 22. Nakagawa S, Arai Y, Kan H, et al. Medial patellofemoral ligament reconstruction procedure using a suspensory femoral fixation system. Arthrosc Tech 2013;2: e491-e495. 23. Mourtney J, Senavongse W, Amis AA, Thomas NP. Tensile strength of the medial patellofemoral ligament before and after repair or reconstruction. J Bone Joint Surg Br 2005;87:36-40. 24. Schottle PB, Hensler D, Imhoff AB. Anatomical doublebundle MPFL reconstruction with an aperture fixation. Knee Surg Sports Traumatol Arthrosc 2010;18:147-151.
Abstract: Medial patellofemoral ligament (MPFL) reconstruction is a common procedure used to treat both acute and chronic patellar instability. Although many variations of MPFL reconstruction have been described, there is no consensus regarding the optimal surgical technique. We describe a technique for MPFL reconstruction with a looped gracilis tendon autograft using suture anchors to secure the graft to the patella and a suspensory loop button system for fixation to the femur. This technique replicates the native shape of the MPFL while minimizing the risk of patellar fracture and allowing for gradual tensioning of the graft.
N
umerous techniques for reconstruction of the medial patellofemoral ligament (MPFL) have been described, but none stands out as the generally accepted standard of care. Technical variationsdfor example, in the number of graft bundles, graft sources, and fixation methodsdexist, and much has been published on this topic in recent years.1-7 However, because it is known that a nonanatomic reconstruction of the MPFL can lead to nonphysiological patellofemoral loads and kinematics, the goal of surgical intervention must be an anatomic reconstruction predicated on correct identification of the anatomic insertion sites of the MPFL on the patella and femur, secure fixation of the graft to the insertion sites, and appropriate graft tensioning.8 We present a surgical technique for MPFL reconstruction using a looped gracilis tendon with suture anchor patellar fixation and suspensory loop cortical button femoral fixation. The use of a loop button system allows gradual tensioning that can be checked while cycling the knee to find the isometric fixation
point and allowing for optimal tensioning of the graft. The surgical technique, along with step-by-step instructions, is available for viewing in a cadaveric specimen in Video 1. In addition, all specialized instrumentation needed for the procedure is listed in Table 1 and depicted in Figure 1.
From the Department of Orthopaedic Surgery, Duke University, Durham, North Carolina, U.S.A. The authors report the following potential conflict of interest or source of funding: W.E.G. receives support from DJO, GlaxoSmithKline, Arthrex, and RTI. Received March 10, 2015; accepted June 11, 2015. Address correspondence to Jonathan A. Godin, M.D., M.B.A., Department of Orthopaedic Surgery, Duke University, DUMC Box 3000, Durham, NC 27710, U.S.A. E-mail: [email protected] Ó 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved. 2212-6287/15233/$36.00 http://dx.doi.org/10.1016/j.eats.2015.06.005
MPFL Reconstruction The patient is brought to the operating room and positioned supine on the operative table with all bony prominences well padded (Table 2). A thigh tourniquet is placed on the operative extremity; this may or may not be used. At our institution, we prefer to perform the procedure with the patient under regional anesthesia in addition to monitored anesthesia care. It is important to note that the obturator nerve should be blocked if regional anesthesia is administered. General anesthesia may also be used. An examination under anesthesia is
Surgical Technique Preoperative Assessment A thorough history and physical examination should be conducted. Moreover, anteroposterior and lateral radiographs of the affected knee, as well as bilateral sunrise views, should be obtained to detect differences in patellar tilt and alignment. Magnetic resonance imaging is performed to evaluate for articular cartilage injury, identify loose bodies, and rule out associated soft-tissue injuries to the menisci and ligaments. In addition, the tibial tubercleetrochlear groove distance should be calculated and is useful for predicting the need for a tibial tubercle transfer.
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Table 1. Special Equipment and Implants 3.5-mm titanium Corkscrew suture anchors Radiodense template 4.0-mm spade-tipped guide pin Graft-sizing paddle Tenodesis reamer (Arthrex) TightRope No. 2 FiberWire
performed on both knees to allow comparison with the contralateral side. An intravenous antibiotic is administered before incision. The operative extremity is then prepared and draped in sterile fashion. Diagnostic arthroscopy is performed next, with particular attention paid to patellofemoral chondral injuries, dysplasia, alignment, and loose bodies. A lateral retinacular release may be performed as necessary for significant lateral tightness, but we infrequently perform this procedure for instability. At this time, concomitant arthroscopic procedures, such as loose body removal, chondral debridement, abrasion chondroplasty, and microfracture of osteochondral lesions, are performed. After completion of arthroscopy, the tourniquet is insufflated. The knee is marked, with estimation of the locations of the pes anserinus, the midpoint between the medial epicondyle and adductor tubercle, and finally, the superomedial border of the patella. Either an allograft or autograft may be used. If an autograft is selected, then the gracilis or semitendinosus is harvested at this time through a 3-cm longitudinal incision centered over the pes anserinus. Alternatively, a 2-cm transverse or oblique incision can be made over the hamstring tendons in the posteromedial popliteal fossa for a proximal harvest. The graft is then cleaned, measured, and set aside in saline solutionesoaked sponges. The graft should be a minimum of 18 cm in
length and approximately 4 to 5 mm in diameter. Next, the medial patellar border is identified, and a 2-cm skin incision is made from the superomedial corner extending to the center of the medial edge of the patella. Dissection is taken down to expose the medial edge of the patella while staying superficial to the capsule. The surgeon should be sure to maintain the integrity of the periosteal layer because this will be the first, and deepest, layer of closure over the graft fixation on the patellar side. Under fluoroscopic guidance, at a point approximately 3 mm distal to the proximal-medial corner of the patella, the surgeon drills a hole to approximately 15 mm with a 2-mm drill. A second hole is drilled approximately 15 to 20 mm distal and parallel to the first hold (Fig 2). The surgeon should be sure to aim slightly anterior while drilling the holes to avoid joint penetration (Table 3). Alternatively, a 1.1-mm drill tip guide pin may be used to place the patellar fixation sites, and these are then over-drilled. Two 3.5-mm titanium Corkscrew suture anchors (Arthrex, Naples, FL) are placed into the prepared patellar fixation sites. Two 3.5-mm Bio-Corkscrew suture anchors (Arthrex) may be used in place of the titanium suture anchors. Thereafter a soft-tissue tunnel is created between layers 2 and 3 at the level of the MPFL. This tunnel is superficial to the joint capsule (layer 3) but deep to the medial retinaculum and fascia (layer 2). This interval is depicted in Figure 3. The space between the vastus medialis and the capsule is then identified and bluntly developed toward the femoral insertion, leaving the capsule intact. A right-angle clamp is inserted into the prepared layer down to the medial epicondyle, and the tip of the clamp is turned toward the skin. After palpation of the medial femoral condyle, a longitudinal incision of approximately 2 cm is made just anterior to
Fig 1. Instrumentation.
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Table 2. Step-by-Step Surgical Technique Step 1. Position patient 2. Perform examination under anesthesia 3. Perform diagnostic arthroscopy 4. Harvest autograft or thaw allograft 5. Perform medial patellar dissection
6. Prepare medial patella for graft fixation
7. Place Corkscrew suture anchors in patella 8. Create soft-tissue tunnel for graft
9. Identify femoral insertion of MPFL
10. Prepare femoral tunnel for graft fixation
11. Prepare graft (this can be done simultaneously with steps 5-10) 12. Secure patellar limb of graft 13. Pass graft through medial tissue tunnel 14. Deliver TightRope through femoral tunnel
15. Deliver graft through femoral tunnel 16. Tension graft 17. Evaluate reconstruction 18. Perform wound closure
Description Position the patient supine with a tourniquet on the operative extremity. Examine and compare with the contralateral side. Assess for patellofemoral chondral injuries, loose bodies, trochlear dysplasia, and malalignment. Address associated pathologies as indicated. If using autograft, harvest gracilis or semitendinosus and ensure adequate length and diameter (18 cm and 4-5 mm, respectively). If size is not adequate, use allograft. Make a 2-cm skin incision from the superomedial corner to the center of the medial edge of the patella. Dissect through the subcutaneous tissue while staying superficial to the capsule. Drill a hole using a 3.5-mm cannulated reamer to a depth of 15 mm on the medial surface of the patella, just 3 mm distal to the superomedial pole. Drill a second hole 15-20 mm distal and parallel to the first hole. Place two 3.5-mm titanium or bioabsorbable Corkscrew suture anchors into the predrilled patellar holes. Identify the interval between layers 2 and 3 of the medial knee (superficial to joint capsule and deep to medial retinaculum). Using a right-angle or tonsil clamp with the tips turned toward the skin, continue dissection to the medial epicondyle to create a tunnel for the graft. Make a 2-cm incision in the skin just anterior to the medial epicondyle to the depth of the tissue tunnel created. Using fluoroscopy, identify the MPFL insertion on the femur. Anatomically, this is between the medial epicondyle and adductor tubercle, 2 mm anterior and 4 mm distal to the adductor tubercle. Radiographically, this is 1 mm anterior to the posterior femoral cortical line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to the level of the posterior point of the Blumensaat line. Starting at the identified MPFL insertion site, drill the 4-mm Beath pin across the femur, aiming slightly proximal and anterior, exiting at the lateral epicondyle. Ream over the pin to the appropriate graft size, up todbut not throughdthe lateral cortex. Pass the TightRope around the graft, and suture the 2 limbs with about 15 mm of overlap with No. 2 FiberWire to form a loop. Confirm the size of the double-stranded graft (away from the sutured limbs). Tie 1 suture from each of the medial patellar suture anchors around the looped graft (at the portion of the sutured limbs), securing it down to the bone. Using a right-angle or tonsil clamp, bring the TightRope and graft through the tissue tunnel and out of the incision overlying the medial epicondyle. Thread the passing sutures (blue) into the Beath pin, and pull them out of the lateral femur. Pull the sutures to deliver the button through the femoral canal until it is flipped on the lateral cortex. Using a clamp as a pulley on the looped graft to maintain equal tension on the graft limbs, pull the tensioning sutures (white) to deliver the graft into the femoral tunnel. With the knee in 30 of flexion, pull on the tensioning sutures to achieve the desired graft tension. Do not over-tighten. Evaluate the graft tensioning and patellar tracking through full knee ROM. Perform layered closure of soft tissues after thorough irrigation and hemostasis of wounds.
MPFL, medial patellofemoral ligament; ROM, range of motion.
the epicondyle, and dissection is carried down to the level of the previously created soft-tissue tunnel. Next, the femoral insertion site of the MPFL is identified under fluoroscopic guidance. This point is located on a line between the medial femoral epicondyle and the adductor tubercle, approximately 2 mm anterior and 4 mm distal to the adductor tubercle. The radiographic location has been described as 1 mm anterior to the posterior femoral cortical line, 2.5 mm distal to the posterior origin of the medial femoral condyle, and proximal to the level of the posterior point of the Blumensaat line on a perfect lateral radiograph of the knee (Fig 4).9 We use a radiodense template (Arthrex) to
confirm positioning. Then, a 4-mm spade-tipped drill pin (Arthrex) is drilled across the femur and out through the lateral femoral cortex at the level of, or slightly proximal to, the lateral epicondyle. The pin should be aimed slightly proximal and anterior to avoid the intercondylar notch and to avoid injury to the neurovascular structures (Fig 5). If the prepared graft diameter is larger than 4 mm, then reaming over the spade-tipped pin with the appropriately sized tenodesis reamer is required for graft placement. This allows for the creation of the tunnel as far as possible to prevent the graft from seizing within the tunnel. Care must be taken so that the reamer does not breach the lateral
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Fig 2. Preparation of drill holes in medial patella. (A) Two parallel holes are drilled on the medial side of the patella through a 2-cm skin incision. (B) Two suture anchors are then passed through each drill hole.
femoral cortex because this may prevent button fixation. The graft is then prepared by passing the TightRope (Arthrex) through 1 end of the graft. Next, the 2 ends of the graft are overlapped approximately 15 mm, and a No. 2 FiberWire (Arthrex) is used to suture the 2 free ends of the graft together to form a loop (Fig 6). One suture should be placed approximately 5 mm from one free end of the overlapped, looped graft, and the second suture should be placed approximately 5 mm from the other free end of the graft. The graft is then sized using a graft-sizing paddle (Arthrex). The looped graft is sutured in place along the medial edge of the patella. One free suture limb from each suture anchor is passed around the looped graft, and the suture limbs are tied down (Fig 7). Next, a right-angle clamp is passed through the soft-tissue tunnel connecting the patellar and femoral incisions to bring the TightRope and graft through the soft-tissue tunnel and out of the incision overlying the medial femoral epicondyle. It is very important to maintain equal tension on both graft bundles during this step to ensure proper biomechanics of the patellofemoral joint. The TightRope sutures are delivered out of the medial incision, and with equal tension on both graft bundles, the graft is pulled down to the medial epicondyle. The TightRope passing sutures (blue) are fed into the eyelet of the spade pin and deliver the suture tails out of the lateral femur before the graft enters the femoral socket. By use of a clamp as a pulley, pre-tensioning of
the graft and insertion into the socket with equal tension on both graft bundles are performed as the TightRope is pulled out of the lateral side. Maintenance of tension on the graft until the TightRope button is flipped on the lateral femoral cortex is key at this time. If the button cannot be flipped because the sutures are too short or if excessive force must be used to flip the button, then the TightRope sutures should be lengthened manually before passing and filling the button. Manual fixation of the lateral patellar facet flush with the lateral femoral condyle is performed with the knee in 30 of flexion. Final fixation can be accomplished by pulling the TightRope’s tightening sutures (white) on the medial side, with alternating tension on each strand (Fig 8). It is crucial that the tensioning sutures are not overtightened because the TightRope cannot be loosened. Over-tightening of the TightRope could result in an overconstrained patellofemoral joint. Tracking and tension of the patella are evaluated throughout knee range of motion (ROM). If any adjustments need to be made, the TightRope can be cut out, tensioning adjustments can be made, and a BTB TightRope or BioComposite Interference Screw (Arthrex) can be used to perform fixation of the graft. The tourniquet is then deflated, and a layered closure is performed. Aftercare Weight bearing is allowed with crutches and a brace locked in extension. Isometric quadriceps strengthening
Table 3. Pearls and Pitfalls Aim anterior when drilling the patellar bone tunnels to avoid intra-articular penetration. The patellar fixation sites should be centered on the lateral plane. When drilling across the distal femur, aim slightly anterior and proximal to prevent neurovascular injury and to protect against violation of the joint and intercondylar notch. Do not ream >4 mm in diameter through the lateral distal femoral cortex. Be sure to pass the TightRope through 1 end of the graft before suturing the graft ends together to form a loop. If the button cannot be flipped because the sutures are too short or if excessive force must be used to flip the button, then lengthen the TightRope sutures manually before passing and filling the button. Confirm with fluoroscopy that the TightRope button is flipped and flush on the lateral femoral cortex. Do not over-tension the graft. Only tighten the white sutures with small increments at a time to prevent over-tensioning.
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Fig 3. Tunnel for graft placement. In the right knee of a male cadaver, proper tunnel dissection for graft placement during medial patellofemoral ligament reconstruction is shown. The tunnel is made between anatomic layers 2 (medial retinaculum and fascia) and 3 (capsule) of the knee. The sutures in the image stem from single-loaded suture anchors already placed in the medial aspect of the patella.
and patellar mobilization exercises are initiated. The use of crutches and brace use are discontinued after 6 weeks. No closed kinetic chain exercises are allowed for 6 weeks. During the first 6 weeks, ROM exercises are
Fig 4. Radiographic placement of femoral starting point. This is a fluoroscopic perfect lateral image of a cadaveric left knee with the radiopaque guide placed on the medial aspect of the knee. The guide is placed in line with the posterior cortex of the femur, with the distal intersection overlying the posteriormost aspect of the Blumensaat line and the proximal intersection over the point at which the posterior cortex meets the medial condyle proximally. The black cross indicates proper placement of the pin.
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Fig 5. Reaming of femoral tunnel. On the basis of the sizing guide, an appropriately sized reamer is selected, and the guide pin is over-reamed beginning at the femoral insertion of the medial patellofemoral ligament. The tunnel is drilled unicortically, with the lateral cortex spared to have a stable resting place for the flipped button.
performed from 0 to 60 of flexion. The hinged knee brace is unlocked for ambulation at 6 weeks postoperatively. Sports training is initiated 3 to 4 months after surgery, and most patients are cleared to return to sports and full activity at 6 months.
Fig 6. Graft preparation. A 20-cm gracilis graft has been prepared and looped within the TightRope. Two knots affix the ends of the graft to form a loop. As shown in Video 1, these knots are placed approximately 2 cm apart by initially passing a suture through both limbs of the graft, looping around the limbs twice, and finally, passing the suture through the free ends of the graft before tying the knot. In this fashion the knot lies between the 2 limbs of the graft. The placement and spacing of knots for affixing the looped graft to the patella are depicted here with the free ends of suture from 2 anchors. These knots should be tied between the graft retention knots.
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Fig 7. Graft fixation to medial patella. After the placement of 2 suture anchors, the graft is sutured to the medial side of the patella. Suturing the graft in the described fashion decreases the interosseous surface area removed from within the patella and may reduce the likelihood of patellar fracture as compared with interference fit.
Discussion The MPFL is an important soft-tissue checkrein of the patellofemoral joint because it provides 50% to 60% of the restraint to lateral patellar displacement from 0 to 30 of knee ROM, when the patella is not yet engaged in the trochlea.10 As such, the MPFL is ruptured in as many as 90% of acute dislocations and is either ruptured or attenuated in almost 100% of recurrent instability cases.11 Anatomic MPFL reconstruction was first described in 1992,12 and a number of techniques have since been reported, including suture repair of the MPFL, the use of autogenous tendon graft sutured to the periosteal and fibrous tissue overlying the patella, autogenous tendon transfer, the use of single patellar tunnels, the use of double transverse patellar tunnels, and the use of suture anchors in shallow patellar tunnels. Although many variations on the surgical technique for MPFL reconstruction have been described, there is no consensus regarding the surgical approach, graft choice, graft positioning, and fixation method. Only a handful of studies have directly compared different surgical techniques, and they suggest that there may be better outcomes when both bundles of the MPFL are reconstructed, as compared with singlebundle reconstruction.13,14 Otherwise, a single superior operative technique has not emerged. Complications associated with surgical intervention include persistence of instability, pain localized to the femoral fixation point, restriction of knee flexion, degeneration of the patellofemoral joint, and patellar fracture. A significant percentage of complications associated with MPFL reconstruction occur because of technical errors, which typically involve improper graft position or tension (or both).15,16 Recurrent instability
can occur when the graft is too loose or if fixation on either the femoral or patellar side fails. Conversely, over-tightening or malpositioning of the graft can lead to maltracking, stiffness, and excessive medial compressive forces.17 Patellar fracture is a major complication after MPFL reconstruction, and this has been described most commonly after techniques involving patellar bone tunnels.16,18-20 We are aware of only 2 described MPFL reconstruction techniques involving suspensory adjustable-loop cortical button femoral fixation,21,22 and this is the first described technique using the TightRope system on the femoral side. Golant et al.21 described knotless suture anchor patellar fixation and the use of a hybrid adjustable-loop cortical button with interference screw fixation on the femoral side. Meanwhile, Nakagawa et al.22 used transpatellar bone tunnels and EndoButton (Smith & Nephew Endoscopy, Andover, MA) patellar fixation with adjustable-loop cortical button femoral fixation. We believe that suture anchor fixation without interference fit on the patellar side minimizes the risk of patellar fracture while providing a reconstruction that exceeds the ultimate load to failure of the native MPFL.10,23 We add suspensory adjustable-loop cortical button fixation of the graft on the femoral side because it allows us to provisionally secure the graft in the femoral tunnel and then gradually adjust graft tension while directly monitoring patellofemoral alignment and stability. Another advantage of this technique is the lack of interference screw fixation on the femoral side. This is especially important when performing MPFL reconstruction in skeletally immature patients because anatomic reconstruction places the femoral tunnel close to the physis. The described MPFL reconstruction technique using a looped, double-bundle graft replicates the native shape of the MPFL while effectively limiting rotation throughout ROM and minimizing postoperative instability. This is a reproducible technique for patellar
Fig 8. Tightening of graft. After graft passage and flipping of the TightRope button, the graft is tightened with alternating pulls on the medial side while tension is kept on the graft with a hemostat through the loop.
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stabilization in patients with acute or recurrent patellar instability that, if performed anatomically, may also provide for more aggressive rehabilitation protocols and an earlier return to activity.24
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12. Ellera Gomes JL. Medial patellofemoral ligament reconstruction for recurrent dislocation of the patella: A preliminary report. Arthroscopy 1992;8:335-340. 13. Kang H, Cao J, Yu D, Zheng Z, Wang F. Comparison of 2 different techniques for anatomic reconstruction of the medial patellofemoral ligament: A prospective randomized study. Am J Sports Med 2013;41:1013-1021. 14. Wang CH, Ma LF, Zhou JW, et al. Double-bundle anatomical versus single-bundle isometric medial patellofemoral ligament reconstruction for patellar dislocation. Int Orthop 2013;37:617-624. 15. Shah JN, Howard JS, Flanigan DC, Brophy RH, Carey JL, Lattermann C. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med 2012;40:1916-1923. 16. Parikh SN, Nathan ST, Wall EJ, Eismann EA. Complications of medial patellofemoral ligament reconstruction in young patients. Am J Sports Med 2013;41:1030-1038. 17. Beck P, Brown NA, Greis PE, Burks RT. Patellofemoral contact pressures and lateral patellar translation after medial patellofemoral ligament reconstruction. Am J Sports Med 2007;35:1557-1563. 18. Mikashima Y, Kimura M, Kobayashi Y, Miyawaki M, Tomatsu T. Clinical results of isolated reconstruction of the medial patellofemoral ligament for recurrent dislocation and subluxation of the patella. Acta Orthop Belg 2006;72:65-71. 19. Lippacher S, Reichel H, Nelitz M. Patellar fracture after patellar stabilization. Orthopade 2010;39:516-518 [in German]. 20. Thaunat M, Erasmus PJ. Recurrent patellar dislocation after medial patellofemoral ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2008;16:40-43. 21. Golant A, Quach T, Rosen J. Medial patellofemoral ligament reconstruction with a looped semitendinosus tendon, using knotless anchor fixation on the patella and hybrid fixation on the femur. Arthrosc Tech 2014;3: e211-e216. 22. Nakagawa S, Arai Y, Kan H, et al. Medial patellofemoral ligament reconstruction procedure using a suspensory femoral fixation system. Arthrosc Tech 2013;2: e491-e495. 23. Mourtney J, Senavongse W, Amis AA, Thomas NP. Tensile strength of the medial patellofemoral ligament before and after repair or reconstruction. J Bone Joint Surg Br 2005;87:36-40. 24. Schottle PB, Hensler D, Imhoff AB. Anatomical doublebundle MPFL reconstruction with an aperture fixation. Knee Surg Sports Traumatol Arthrosc 2010;18:147-151.
