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Particulated Juvenile Cartilage Allograft Transplantation for the Treatment of Osteochondral Lesions of the Talus
Particulated Juvenile Cartilage Allograft Transplantation for the Treatment of Osteochondral Lesions of the Talus Samuel B. Adams Jr., MD,* Mark E. Easley, MD,* and Lew C. Schon, MD† Osteochondral lesions of the talus present a formidable treatment challenge to the orthopaedic surgeon. Although debridement with either microfracture, drilling, or curettage is often successful in relieving pain and growing fibrocartilage within a standard lesion, the option of implanting particulated juvenile cartilage allograft has become a promising treatment alternative for patients who have failed routine treatment or who have osteochondral lesions that are known to do poorly from the onset. Particulated juvenile cartilage allograft transplantation delivers 1 mm3 of fresh juvenile cartilage, which contain live cells in their native extracellular matrix, that are secured into the osteochondral defect with the use of a fibrin adhesive. The current evidence, indications, and surgical technique for the use of particulated juvenile cartilage allograft transplantation in the management of osteochondral lesions of the talus have been reviewed. Oper Tech Orthop 24:181-189 C 2014 Published by Elsevier Inc.
KEYWORDS Talus, osteochondral, DeNovo, particulated juvenile cartilage allograft transplantation, microfracture
Introduction
T
he term osteochondral lesion of the talus (OLT) refers to any pathology of the talar articular cartilage and corresponding subchondral bone. Kappis1 initially described this pathology as osteochondritis dissecans, suggesting spontaneous necrosis of bone as the primary etiology. However, contemporary data support trauma as the cause of most OLTs, with repetitive microtrauma, avascular necrosis, and congenital factors as the remaining etiologies.2 OLTs present a treatment challenge secondary to the innate inability of cartilage to heal. Ideally, OLTs could intrinsically heal from cell migration from the surrounding cartilage. However, although chondrocytes migrate and proliferate well in vitro, they have limited ability to replicate these actions *Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC. †Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD. Address reprint requests to Lew C. Schon, MD, MedStar Union Memorial Orthopedics and Sports Medicine, MedStar Union Memorial Hospital 3333 N. Calvert St Suite 400, Baltimore, MD 21218. E-mail: [email protected]
http://dx.doi.org/10.1053/j.oto.2014.04.002 1048-6666/& 2014 Published by Elsevier Inc.
in vivo. It is thought that in vivo chondrocyte migration is limited because of the rigidity of the extracellular matrix.3-5 Therefore, modern options to treat OLTs typically employ methods to deliver autologous or allogenic cells. Even marrow stimulation (microfracture) attempts to deliver bone marrow cells by penetrating the subchondral plate. However, the fibrocartilage formed from this procedure has been shown to be biomechanically weaker than native hyaline cartilage.6 Osteochondral autograft transplantation transfers viable chondrocytes with native extracellular matrix and subchondral bone from either minimal weight-bearing areas of patient’s own femoral condyle or even the anterior aspect of the talus into the OLT. However, donor site morbidity, poor interface integration, need for perpendicular access via an osteotomy, and the idiosyncratic 3-dimensional geometry of talar shoulder OLTs limit the application of this technique.7,8 Techniques such as autologous chondrocyte implantation (ACI) and matrix-induced ACI have been successful in forming hyalinelike cartilage at repair sites,9 but their widespread use has been limited because of the technical and financial burden of chondrocyte expansion and the need for 2 procedures.8 Bulk fresh osteochondral allografts have also demonstrated success in treating OLTs,10 but this treatment option is limited by 181
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performed on each lot (one lot of tissue comes from a single donor). The first clinical implantation of DeNovo NT Graft was performed in May 2007 for a patella lesion.12 The advantages of this technique are that it is a surgically simple procedure without the need for graft press-fitting or contouring (as needed for osteochondral autograft or allograft transplantation), it does not require osteotomy in most cases (as is often needed for osteochondral autograft transfer or allograft transplantation), it is a single-stage procedure, there is no donor site morbidity, and there is a minimal chance for immunologic reaction (cartilage is considered immune privileged). The disadvantages of this technique are the fact that it is a relatively new procedure with limited patient data, there is a limited supply of juvenile donor cartilage, it is a relatively expensive treatment option compared with other techniques, and as with any allograft tissue, disease transmission concerns exist.
Basic Science Evidence
Figure 1 (A) Medial talar shoulder OLT accessed through an anteromedial arthrotomy with plafondplasty. (B) The lesion underwent PJCAT. Notice the mechanically minced pieces in the surrounding fibrin glue. (Color version of figure is available online.)
donor availability, geometric contour discrepancies, and the uncertainty of delivering truly viable chondrocytes after allograft processing and impacting into place. Particulated juvenile cartilage allograft transplantation (PJCAT) is a new technique of transplantation of multiple fresh juvenile cartilage allograft tissue pieces, containing live cells within their native extracellular matrix, with fibrin adhesive securing the tissue pieces firmly inside the lesion (Fig. 1). This technique is in many ways similar to the osteochondral autograft transfer with the following differences: transplantation of particulated cartilage pieces instead of osteochondral plugs, the use of juvenile cartilage instead of adult cartilage, and graft fixation with fibrin adhesive instead of bony press-fit. Currently, the only graft material available for this procedure is DeNovo NT Natural Tissue Graft (Zimmer, Inc, Warsaw, IN). The cartilage pieces of this product are obtained, in compliance with Good Tissue Practice, from donors ranging in age from newborn to 13 years old; however, it is typically obtained from neomorts younger than 2 years.11 No stillborn or fetal tissue is used. Standard disease screening is
The concept of hyaline cartilage repair using particulate articular cartilage was first proposed in 1983 by Albrecht et al.13 The authors created full-thickness articular defects down to subchondral bone in adult rabbit patellae. The lesions were treated with nothing, collagen foam, collagen foam plus fibrin glue, autologous mechanically minced cartilage plus fibrin glue, or autologous mechanically minced cartilage plus collagen foam. None of the defects in the groups without minced cartilage demonstrated hyaline cartilage. On the contrary, 61% of the defects treated with minced cartilage demonstrated filling consistent with hyaline cartilage at 16 weeks. The authors reported an increase in the number of implanted chondrocytes and a change in morphology similar to juvenile chondrocytes. They speculated that the transformation of the chondrocytes to this quasi-“juvenile” status was because of the opening of the subchondral vessels, which provided an abundant supply of oxygen and nutrients resembling the physiological state before the end of skeletal maturity. Subsequently, Lu et al8 demonstrated, in a mouse subcutaneous pouch model, that chondrocytes from minced cartilage pieces were able to outgrow into polyglycolide-polylactide and polyglycolide-polycaprolactone scaffolds. The outgrowth was uniform by 6 weeks and the cells were surrounded by newly deposited extracellular matrix. Interestingly, the authors found an inverse relationship with minced cartilage piece size and efficiency of the outgrowth. In this same study, the authors filled goat trochlear defects with autologous minced cartilage pieces. At 6 months, hyalinelike cartilage with complete integration to the surrounding cartilage and subchondral bone was found. These data indicate that viable chondrocytes found in particulated cartilage grafts can migrate, multiply, and form a new hyalinelike cartilage tissue matrix within the host tissue. Adkisson et al14 compared the chondrogenic activity of human juvenile and adult chondrocytes. Chondrocytes from juvenile (o10 years) donors showed significantly greater extracellular matrix synthesis (sulfated glycosaminoglycan; S-GAG) than chondrocytes from mature donors. Moreover, the rate of
Particulated juvenile cartilage allograft transplantion S-GAG synthesis was greater than 100-fold for the juvenile chondrocytes. The authors also demonstrated 100- and 700fold decreased amounts of messenger RNA for type II and type IX collagen, respectively, in mature chondrocytes compared with the juvenile chondrocytes. They speculate that the decreased gene expression directly affects the ability of adult chondrocytes to form neocartilage in vivo. Likewise, they demonstrated a significantly increased growth rate for juvenile chondrocytes and that this cell population did not elicit an immunogenic reaction when transplanted into a xenogenic goat model, indicating immunoprivilage for juvenile chondrocytes. In an interesting study comparing adult and juvenile cartilage coculture, Bonasia et al15 demonstrated that juvenile chondrocytes cultured alone produced significantly more proteoglycans and S-GAG than juvenile chondrocytes cultured with adult chondrocytes in various proportions. More germane to PJCAT, coculture of mechanically minced juvenile and adult cartilage pieces resulted in a significantly higher proteoglycanDNA ratio than that by adult pieces alone in culture and a higher proteoglycan-DNA ratio than that by juvenile pieces alone in culture, but this was not significant. The proteoglycanDNA ratio was used as an outcome measure because it was considered the best approximation of the real amount of matrix production per cell. The authors proposed an explanation for the increased neocartilage produced with coculture of minced juvenile and adult cartilage fragments as follows: less neocartilage is produced in monoculture of juvenile pieces because of the relative absence of chemotactic factors contributed by the adult cartilage, whereas monoculture of adult cartilage produced less neocartilage because of the absence of juvenile cells capable of responding growth factors.
Clinical Evidence for PJCAT Recently, Coetzee et al16 presented a retrospective case series of 23 patients (24 ankles) treated with PJCAT at a mean follow-up of 16.2 months. The mean lesion surface size was 125 mm2 (range: 50-300 mm2) with a mean depth of 7 mm (range: 3-20 mm). All lesions had at least 1 dimension greater than or equal to 10 mm. The lesions were accessed via an open approach in 12 cases, an arthroscopic approach in 3 cases, and through an extended-portal open approach in 9 cases. Bone grafting was performed on lesions deeper than 5 mm. The mean postoperative 100 mm visual analog scale for pain was 24 (range: 0-93) and the mean American Orthopaedic Foot and Ankle Society ankle-hindfoot score was 85 (range: 23-100). The mean Foot and Ankle Ability Measure for activities of daily living was 55.1 (range: 52-58) and the mean Foot and Ankle Ability Measure for sports was 63.4 (range: 52-75). The mean postoperative SF-12 physical composite score was 46.4 (range: 42-51). The authors note that these outcomes scores are similar to published reports on patients who were treated with bone marrow stimulation, ACI, and matrix-induced ACI. Overall, 5 patients required reoperation to remove symptomatic osteotomy hardware, and 1 patient required an additional procedure to treat anterior
183 impingement. At the time of 2 of these procedures, the juvenile cartilage was minimally debrided. Additionally, during 3 reoperations, the International Cartilage Repair Society Cartilage Repair Assessment (protocol A) was used to assess the repair tissue. The 3 lesions were assessed at grade 2 (nearly normal repair). There was 1 partial graft delamination ( 25% of the graft) that was diagnosed at 16 months. The original lesion size of this patient was 180 mm2. Schon and Oji17 presented a case series of 57 OLTs treated with PJCAT. Data were collected prospectively on 17 ankles and retrospectively on 40 ankles. All patients had a minimum of 1-year follow-up. Approximately 73% of patients had more than 60% improvement (pain, function, and quality of life) at final follow-up. Of the patients, 80% were satisfied without or with minor reservation, 8% were satisfied with major reservations, and 12% were dissatisfied; 9% of them did not experience any relief of symptoms. On 1-year postoperative magnetic resonance imaging (MRI), using the magnetic resonance observation of cartilage repair tissue scoring system, 20% of defects were completely filled, 50% of defects demonstrated cartilage hypertrophy, and 30% were incompletely filled. Kruse et al18 presented a case of arthroscopically performed PJCAT to an OLT in a 30-year-old woman with a full-thickness posteromedial lesion that measured 7 mm 5 mm. At 2years following surgery, the patient was found to be pain free with no activity limitations. Bleazey and Brigido19 retrospectively reported on a series of 7 patients treated using a cylindrical allograft plug and PJCAT. The surgical technique was performed through a medial malleolar or fibular osteotomy in all patients. The lesion was assessed and then a size-matched reamer was used to ream past the subchondral plate into the cancellous bone. A cylindrical sponge allograft of matched diameter was then inserted and recessed to the level of the subchondral plate. The graft was then formed ex vivo by mixing particulated cartilage and fibrin glue into a size-matched mold. It was then secured with additional fibrin glue. All patients demonstrated significant improvement in each category of a custom 10-point scale that assessed their ability to ambulate upstairs, downstairs, and over 4 city blocks. The greatest improvement was in the ability to walk 4 city blocks. All patients would have the surgery performed again. However, all patients were followed up for only 6 months. PJCAT has also been used in lesions outside the talus. Bonner et al12 reported on PJCAT for a full-thickness patellar cartilage defect in a 36-year-old man. At 2-year follow-up, the patient demonstrated clinical improvement in both pain and function, based on International Knee Documentation Committee and Knee Injury and Osteoarthritis Outcome Score outcome measures. MRI demonstrated filling of the defect with repair tissue and near-complete resolution of preoperative bony edema. Tompkins et al20 reported on 15 knees of 13 patients who had Outerbridge grade 4 articular cartilage defects of the patella. The patients underwent open application of particulated juvenile cartilage and were followed up for a mean of 28.8 ⫾ 10.2 months. They were assessed with postoperative MRI and outcomes questionnaires. The mean International
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184 Cartilage Repair Society cartilage repair assessment score on MRI was 8.0 ⫾ 2.8, which the authors mention is a nearly normal score. In fact, 11 of 15 patients had normal or nearly normal scores. Of the 15 knees, 5 repairs demonstrated graft hypertrophy. The mean percentage of surface filled was 89.9% ⫾ 19.6% with all but 3 knees showing 90% filling or greater. Functionally, the mean postoperative visual analog scale (1-10) pain score was 1.9 ⫾ 1.4. The mean Tegner score was 5, consistent with a return to recreational sports or heavy labor.
PJCAT Indications and Contraindications The authors’ recommended indications for PJCAT include a symptomatic patient who has a primary OLT that is larger than 15 mm in 1 dimension or a patient who has undergone an unsuccessful marrow stimulation technique with continued symptoms and an OLT as evidenced on MRI. Shoulder and cystic lesions are not excluded. Contraindications to surgical management of OLTs include infection, medical comorbidities that preclude a surgical procedure, diffuse ankle arthritis, or uncorrected ankle malalignment. Specific recommended contraindications to PJCAT include large cystic or necrotic bony defects. Small cystic lesions with bony defects can be managed with concomitant bone grafting with PJCAT. In these instances, the authors have performed local bone grafting from the calcaneus, tibia, or iliac crest with application of the PJCAT graft in the same surgical setting.
Preoperative Planning An MRI is essential to assess the size of the cartilage defect for the purposes of defining the quantity of juvenile allograft needed. A computed tomography scan can be helpful to define the true extent of the bony lesion, as MRI often demonstrates the more diffuse surrounding bony reaction. Per the manufacturer of the only currently available PJCAT product, 1 pack of DeNovo NT Natural Tissue graft (Zimmer, Inc, Warsaw, IN) is recommended to treat each 2.5 cm2 of lesion surface area, with a recommended fill ratio of at least 50% of the lesion size (e.g., each pack of tissue graft contains enough cartilage to cover 1.25cm2 of surface area and the rest of the surface area is composed of the fibrin carrier). In practice, the authors attempt to completely fill the lesion’s surface area to the depth of the surrounding healthy cartilage, while allowing fibrin adhesive to interpose between cartilage pieces for good tissue fixation.
Open Technique The patient is positioned supine on the operating room table. A thigh tourniquet is applied. The operative leg may be placed in a padded leg holder for arthroscopy. In most cases, standard ankle arthroscopy is performed to confirm the size and location of the lesion. The location of the lesion is assessed while the ankle joint is ranged. This allows a better assessment as to whether the lesion can be approached though an arthrotomy with or without plafondplasty vs a medial or lateral malleolar osteotomy. The arthroscopy has additional benefit in diagnosing and potentially addressing additional pathology. Initial debridement can be performed using standard arthroscopic technique, although we routinely perform our local lesion debridement during the open part of the procedure to save operating room time. The arthroscopic equipment is then removed from the joint and preparation for the open procedure is undertaken. The arthroscopic light source is then turned off, until needed again, but keep the equipment sterile. Having the arthroscopic camera available during the open procedure allows visualization to the back of the joint to assess whether any cartilage pieces may have been dislodged during defect filling. The shaver can be helpful in debriding the lesion and the arthroscope can be used to assess lesion fill. Typically, the medial or lateral arthroscopy portal is incorporated into the arthrotomy skin incision. The soft tissues are retracted and bluntly dissected from the joint capsule. The capsule is then incised longitudinally. Every attempt should be made to preserve this tissue plane for capsular closure. The foot is plantar flexed to assess the visibility of the OLT. If the entire lesion is not visible, an anterior tibial plafondplasty is performed, but it is important to remember that perpendicular access is not needed for PJCAT. Most of the talus is accessible through an anterior medial or lateral arthrotomy and tibial plafondplasty.22 Using a curved quarter-inch osteotome, the superior and medial or lateral aspect of the anterior tibial plafond is removed (Fig. 2). Careful attention should be made
Techniques Both open and arthroscopic PJCAT techniques have been described.11,21 Open techniques include the use of an anterior tibial plafondplasty or a medial or lateral malleolar osteotomy.
Figure 2 A quarter-inch osteotome is used to create an anteromedial plafondplasty. (Color version of figure is available online.)
Particulated juvenile cartilage allograft transplantion to not remove more than 1 cmof the nonarticular tibia in any dimension. Only the minimal amount of tibia necessary to debride and fill the lesion should be removed. Smaller plafondplasties are generally not repaired. If the plafondplasty approaches 1 cm in any dimension or if loss of structural integrity is a concern, then consideration should be given to small-fragmentary screw or bioabsorbable pin fixation. Visualization may be further enhanced using of a Hintermann-style distractor or a lamina spreader secured to the tibia and talus with pins. If, after debridement, the base of the OLT requires bone grafting, the bone from the plafondplasty can be used. Alternatively, trephine obtained bone from the calcaneus, tibia, or iliac crest can be used. Occasionally, a medial or lateral malleolar osteotomy is necessary to access the lesion. This determination must be made after arthroscopy and an anteromedial or lateral arthrotomy should not be made. The techniques for medial or anterolateral tibial osteotomies are beyond the scope of this article. However, in 67 cases personally performed by the senior author (L.C.S.) to date, no osteotomies have been performed. If the lesion is posterior, then the patient should be positioned prone and a posterior approach is used to the ankle. Large lesions with margins within the posterior quarter of the talar dome are unlikely to be visualized with an anterior plafondplasty. However, it is important to stress the necessity of preoperative planning regarding lesion location. If the surgeon is unsure as to whether an osteotomy would be necessary, the small amount of time it takes to determine the location of the OLT during the initial arthroscopy can be very helpful for decision making. Once the lesion is visualized, a combination of a #15 blade and small curette can be used to debride the OLT. Debride the lesion until stable margins are achieved on all sides. Careful attention should be paid to the shoulder of the talus. If it is felt that the shoulder is not involved, every attempt should be made to leave the medial or lateral cartilage border at the shoulder. This helps to contain the cartilage-fibrin mixture in the lesion and not have it spill into the medial or lateral gutter. There is debate regarding the preparation of the base of the lesion for the addition of marrow stimulation (microfracture) by violating the subchondral plate. In all reality, with adequate debridement, the subchondral plate is often penetrated in at least 1 location. We routinely perform a microfracture at the base of the lesion. This is typically done with the tourniquet deflated to confirm the establishment of a bleeding bone base (Fig. 3A). Subsequently, we advise reinflating the tourniquet to maintain a dry base during defect filling (Fig. 3B). Next, the joint should be thoroughly irrigated and dried. Leave a sponge in the joint while preparing the particulated graft. The dry lesion bed permits better incorporation of the cubes by the fibrin glue within the defect. Prepare a fibrin adhesive. It is important to have extra fibrin delivery tips available as they can become clogged in between applications of fibrin glue to the defect. Now take the DeNovo NT Graft packet and turn it so that the pointed end of the plastic well faces the ground. For the DeNovo NT Graft, position the packet so that the narrow end of the plastic well faces
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Figure 3 The same anteromedial OLT from Figure 2. (A) The lesion underwent microfracture with the tourniquet deflated. Notice the bleeding base. (B) The same lesion after tourniquet inflation, joint irrigation, and drying with a sponge. Notice the marrow stimulation holes. In this case, marrow stimulation was performed using a 0.045in Kirschner wire and irrigation. (Color version of figure is available online.)
downward to allow the cartilage pieces to settle to the bottom. Peel back the foil covering, and using a 20-25 gauge needle and syringe, carefully aspirate the medium without removing any of the cartilage pieces. The foot can be positioned in plantar flexion and may then be swung over the side of the table to situate the base of the lesion as parallel to the floor as possible. This facilitates defect filling without the loss of fibrin glue or cartilage pieces into the back of the joint. Several methods can be employed to deliver the particulated cartilage to the lesion. Typically, the foil lid is cut into a strip and bent in the center to create a trough or the plastic packaging can be cut to a point (Fig. 4A). The cartilage pieces are then scooped into the trough (Fig. 4B), and the trough is brought into the joint space. Next, an elevator or equivalent instrument is used to push the cartilage pieces into the bed of the lesion until particulated cartilage completely covers the base. Fibrin glue and additional particulated
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Arthroscopic Technique Performing an all-arthroscopic PJCAT can be challenging. The diagnostic arthroscopy serves to ensure that complete access to the OLT can be obtained. The authors have a low threshold to move to an extended-portal approach or arthrotomy if OLT access or instrument working room is limited. An anterior arthroscopy is described here but the same procedure can be performed using posterior arthroscopy. The patient is placed supine on the operating room table with the foot at the end of the bed. The operative leg is placed in a leg holder to keep the hip and knee flexed. The extremity is then prepared for surgery and draped in the usual sterile fashion. A thigh tourniquet is used throughout the case. Next, noninvasive distraction is applied. Standard anteromedial and anterolateral portals are used, and routine arthroscopic examination of the ankle joint is performed. A probe is used to define and measure the lesion in multiple dimensions to ensure there is enough PJCAT material available. An arthroscopic shaver is introduced to debride any invaginated synovium that obscures
Figure 4 (A) The foil backing has been removed and a strip has been cut. The strip is bent longitudinally in the middle to act as a trough to contain the pieces. Alternatively, the plastic container can be cut into a point to deliver the pieces from the package. (B) The pieces have been loaded into the foil trough. (Color version of figure is available online.)
cartilage pieces are added in a layered fashion until the depth of the lesion is completely filled without the construct being raised (Fig. 5). An additional amount of fibrin glue is applied to the lesion to complete the particulated cartilage-fibrin glue construct. At this point, before the fibrin glue has completely set up, dorsiflex the ankle until the lesion is completely covered. Apply axial compression to use the contour of the tibial articular surface to mold the superior surface of the talar lesion. Maintain compression for 5 minutes. Suction out any residual fluid and excess congealed fibrin glue. Plantar flex the ankle and assess the lesion. Next, gently take the ankle through range of motion to assess the stability of the lesion. Do not irrigate the joint. If the joint requires irrigation, dorsiflex the ankle to protect the filled lesion and gently irrigate. Close the capsular tissue with size 0 absorbable figure-of-eight stitches. Irrigate the remaining wound, and close the subcutaneous layer with 3-0 absorbable suture and either 4-0 nonabsorbable vertical mattress stitches or a running 4-0 MONOCRYL stitch. Apply a well-padded splint with the ankle in neutral flexion.
Figure 5 (A) DeNovo pieces have been added to the base of the lesion. Fibrin glue is being applied. Often, some DeNovo pieces “cling” to the surrounding tissues; these are removed in the process. (B) The same lesion after addition of DeNovo pieces and fibrin glue in a layered fashion. (Color version of figure is available online.)
Particulated juvenile cartilage allograft transplantion the view of the OLT or that instruments form the working portal may pass by during the case. At this point, the arthroscopic water flow is shut off, and the joint is evacuated of fluid. The lack of fluid relaxes the soft tissues, and there may be additional soft tissue invagination. This allows the surgeon to assess the need for any additional soft tissue debridement. The arthroscopic flow is restored. Combinations of ring and scoop curettes are used to debride the lesion back to stable cartilage margins (Fig. 6A). The arthroscopic flow is again shut off and the joint is evacuated of arthroscopic fluid (Fig. 6B). A small suction tip, the shaver with suction on and the tip in the open position, or cotton-tipped applicators or pledgets are used to dry the joint (Fig. 7). The lack of arthroscopic fluid pressure allows the base of the lesion to bleed. Profuse bleeding from the base would make the rest of the procedure difficult and can be addressed using a small amount of fibrin glue at the base of the lesion. Additionally, epinephrine in the arthroscopic fluid throughout the case or epinephrine-soaked cotton-tipped applicators or pledgets can be used to decrease bleeding from the synovium. In cases of subtle bleeding, a fibrin glue base is not needed.
Figure 6 (A) A debrided medial shoulder lesion in which previous microfracture was unsuccessful. The lesion is viewed from the medial arthroscopic portal and has been debrided to stable margins. (B) The same lesion viewed from the lateral arthroscopic portal. Fluid flow has been turned off and the fluid has been evacuated. (Color version of figure is available online.)
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Figure 7 A cotton-tipped applicator is being used to dry the lesion bed. (Color version of figure is available online.)
Now take the DeNovo NT Graft packet and turn it so that the pointed end of the plastic well faces the ground. For the DeNovo NT Graft, position the packet so that the narrow end of the plastic well faces downward to allow the cartilage pieces to settle to the bottom. Peel back the foil covering, and using a 20-25 gauge needle and syringe, carefully aspirate the medium without removing any of the cartilage pieces. Next, the pieces are carefully loaded, in retrograde fashion, into the tip of a 2.7-mm arthroscopic cannula using a Freer elevator and the trocar. It is very important to recess the pieces so that they are not exposed and do not get caught in the soft tissues when introduced into the joint (Fig. 8A). Do not load all of the pieces at once. The authors routinely make 2-3 passes with 1 package of DeNovo NT. Under arthroscopic visualization, carefully insert the cannula into the ankle joint and dock it at the near edge of the lesion. Insert the cannula and very slowly push the pieces into the joint (Fig. 8B). Remove the cannula and trocar and insert a Freer elevator or similar arthroscopic tool to arrange the pieces uniformly in the lesion. Next, insert the fibrin glue tip through the arthroscopic portal and apply a small amount of glue. Occasionally, the tip provided with fibrin glue is too short and an angiocatheter without the needle is used or a needle itself can be used (Fig. 9A). Insert a Freer elevator or similar arthroscopic tool to mold the pieces uniformly in the lesion while the glue is increasing in viscosity (Fig. 9B). Repeat these steps until the lesion is completely filled. Allow the fibrin glue to set for 5-10 minutes until opaque (Fig. 10), and then gently range the ankle. The arthroscopic portals are closed with nylon and a wellpadded splint is placed with the ankle in a position to fully contain the lesion under the tibial plafond.
Postoperative Management The patient is kept with the splint in a non–weight-bearing state for 10-14 days. The sutures are removed at that point and the patient is placed in a removable boot brace. The patient remains non–weight-bearing except for range-of-motion
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Figure 8 (A) The 2.7-mm cannula is being introduced through the medial arthroscopic portal. Notice that the DeNovo pieces are recessed so they do not get lost going through the portal. (B) The cannula is placed on the lesion and the trocar is used to push the pieces into the joint. (Color version of figure is available online.)
exercises. Range-of-motion exercises entail weight-bearing deep knee bends for 20 minutes, 5 times per day out of the boot. At night, a night splint can be used to keep the lesion contained. Also, if the patient required lateral or medial ligament reconstruction the night splint will protect the repair. At the 6-week postoperative period, the patient may progress to full weight-bearing walking. The boot brace can be removed between the 6th and the 12th week as tolerated and a cloth lace-up brace can be used. Full plantar flexion is allowed during this time, provided there is no contraindication based on concomitant performed procedures. Physical therapy, strengthening exercises, the exercise bicycle, and water activities may be initiated at 6 weeks. Impact activities are not started until 6 months. If the patient can hold off from beginning major activities for as long as 2 years, there may be additional benefit to the healing cartilage graft.
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Figure 9 (A) A needle is used to introduce fibrin glue. (B) A Freer elevator is used to mold the DeNovo pieces into the lesion as the fibrin glue sets. (Color version of figure is available online.)
Reports of early follow-up demonstrate patient improvement. Basic science evidence demonstrates that this technique can restore hyaline cartilage. PJCAT delivery can be performed through all-open, arthroscopically assisted open, and allarthroscopic techniques.
Conclusion PJCAT is viable treatment option for OLTs that have failed previous operative management or primary OLTs that are likely to be unresponsive to marrow stimulation techniques.
Figure 10 The final appearance of the lesion after the fibrin glue has set and become opaque. (Color version of figure is available online.)
Particulated juvenile cartilage allograft transplantion
References 1. Kappis M: Weitere Beitrage zur traumatisch-mechanischen Entstehung der “spontanen” Knorpelablosungen (sogen. Osteohondrisit dessecans). Dtsch Z Chir 171:13-20, 1922 2. Cambell C, Ranawat C: Osteochondritis Dissecans: The question of etiology. J Trauma 6:201-221, 1966 3. Giurea A, DiMicco MA, Akeson WH, et al: Development-associated differences in integrative cartilage repair: Roles of biosynthesis and matrix. J Orthop Res 20:1274-1281, 2002 4. Hunziker EB, Kapfinger E: Removal of proteoglycans from the surface of defects in articular cartilage transiently enhances coverage by repair cells. J Bone Joint Surg Br 80:144-150, 1998 5. Qiu W, Murray MM, Shortkroff S, et al: Outgrowth of chondrocytes from human articular cartilage explants and expression of alpha-smooth muscle actin. Wound Repair Regen 8:383-391, 2000 6. Nehrer S, Spector M, Minas T: Histologic analysis of tissue after failed cartilage repair procedures. Clin Orthop Relat Res 365:149-162, 1999 7. McGahan PJ, Pinney SJ: Current concept review: Osteochondral lesions of the talus. Foot Ankle Int 31:90-101, 2010 8. Lu Y, Dhanaraj S, Wang Z, et al: Minced cartilage without cell culture serves as an effective intraoperative cell source for cartilage repair. J Orthop Res 24:1261-1270, 2006 9. Peterson L, Minas T, Brittberg M, et al: Two- to 9-year outcome after autologous chondrocyte transplantation of the knee. Clin Orthop Relat Res 374:212-234, 2000 10. Adams Jr. SB, Viens NA, Easley ME, et al: Midterm results of osteochondral lesions of the talar shoulder treated with fresh osteochondral allograft transplantation. J Bone Joint Surg Am 93: 648-654, 2011 11. Adams SB, Yao J, Schon LC: Particulated juvenile article cartilage allograft transplantation for osteochondral lesions of the talus. Tech Foot Ankle Surg 10:92-98, 2011
189 12. Bonner KF, Daner W, Yao JQ: 2-year postoperative evaluation of a patient with a symptomatic full-thickness patellar cartilage defect repaired with particulated juvenile cartilage tissue. J Knee Surg 23:109-114, 2010 13. Albrecht F, Roessner A, Zimmermann E: Closure of osteochondral lesions using chondral fragments and fibrin adhesive. Arch Orthop Trauma Surg 101:213-217, 1983 14. Adkisson HD, Martin JA, Amendola RL, et al: The potential of human allogeneic juvenile chondrocytes for restoration of articular cartilage. Am J Sports Med 38:1324-1333, 2010 15. Bonasia DE, Martin JA, Marmotti A, et al: Cocultures of adult and juvenile chondrocytes compared with adult and juvenile chondral fragments: In vitro matrix production. Am J Sports Med 39:2355-2361, 2011 16. Coetzee JC, Giza E, Schon LC, et al: Treatment of osteochondral lesions of the talus with particulated juvenile cartilage. Foot Ankle Int 34:1205-1211, 2013 17. Schon LC, OjiD: Particulated juvenile cartilage allograft for treatment of osteochondral lesions in the ankle: The Medstar Union Memorial Hospital experience in American Orthopaedic Foot and Ankle Society Annual Meeting, Hollywood, FL, 2013 18. Kruse DL, Ng A, Paden M, et al: Arthroscopic De Novo NT((R)) juvenile allograft cartilage implantation in the talus: A case presentation. J Foot Ankle Surg 51:218-221, 2012 19. Bleazey S, Brigido SA: Reconstruction of complex osteochondral lesions of the talus with cylindrical sponge allograft and particulate juvenile cartilage graft: Provisional results with a short-term follow-up. Foot Ankle Spec 5:300-305, 2012 20. Tompkins M, Hamann JC, Diduch DR, et al: Preliminary results of a novel single-stage cartilage restoration technique: Particulated juvenile articular cartilage allograft for chondral defects of the patella. Arthroscopy 29:1661-1670, 2013 21. Giza E, Howell S: Allograft juvenile articular cartilage transplantation for treatment of talus osteochondral defects. Foot Ankle Spec 6:141-144, 2013 22. Peters PG, Parks BG, Schon LC: Anterior distal tibia plafondplasty for exposure of the talar dome. Foot Ankle Int 33:231-235, 2012
KEYWORDS Talus, osteochondral, DeNovo, particulated juvenile cartilage allograft transplantation, microfracture
Introduction
T
he term osteochondral lesion of the talus (OLT) refers to any pathology of the talar articular cartilage and corresponding subchondral bone. Kappis1 initially described this pathology as osteochondritis dissecans, suggesting spontaneous necrosis of bone as the primary etiology. However, contemporary data support trauma as the cause of most OLTs, with repetitive microtrauma, avascular necrosis, and congenital factors as the remaining etiologies.2 OLTs present a treatment challenge secondary to the innate inability of cartilage to heal. Ideally, OLTs could intrinsically heal from cell migration from the surrounding cartilage. However, although chondrocytes migrate and proliferate well in vitro, they have limited ability to replicate these actions *Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC. †Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD. Address reprint requests to Lew C. Schon, MD, MedStar Union Memorial Orthopedics and Sports Medicine, MedStar Union Memorial Hospital 3333 N. Calvert St Suite 400, Baltimore, MD 21218. E-mail: [email protected]
http://dx.doi.org/10.1053/j.oto.2014.04.002 1048-6666/& 2014 Published by Elsevier Inc.
in vivo. It is thought that in vivo chondrocyte migration is limited because of the rigidity of the extracellular matrix.3-5 Therefore, modern options to treat OLTs typically employ methods to deliver autologous or allogenic cells. Even marrow stimulation (microfracture) attempts to deliver bone marrow cells by penetrating the subchondral plate. However, the fibrocartilage formed from this procedure has been shown to be biomechanically weaker than native hyaline cartilage.6 Osteochondral autograft transplantation transfers viable chondrocytes with native extracellular matrix and subchondral bone from either minimal weight-bearing areas of patient’s own femoral condyle or even the anterior aspect of the talus into the OLT. However, donor site morbidity, poor interface integration, need for perpendicular access via an osteotomy, and the idiosyncratic 3-dimensional geometry of talar shoulder OLTs limit the application of this technique.7,8 Techniques such as autologous chondrocyte implantation (ACI) and matrix-induced ACI have been successful in forming hyalinelike cartilage at repair sites,9 but their widespread use has been limited because of the technical and financial burden of chondrocyte expansion and the need for 2 procedures.8 Bulk fresh osteochondral allografts have also demonstrated success in treating OLTs,10 but this treatment option is limited by 181
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performed on each lot (one lot of tissue comes from a single donor). The first clinical implantation of DeNovo NT Graft was performed in May 2007 for a patella lesion.12 The advantages of this technique are that it is a surgically simple procedure without the need for graft press-fitting or contouring (as needed for osteochondral autograft or allograft transplantation), it does not require osteotomy in most cases (as is often needed for osteochondral autograft transfer or allograft transplantation), it is a single-stage procedure, there is no donor site morbidity, and there is a minimal chance for immunologic reaction (cartilage is considered immune privileged). The disadvantages of this technique are the fact that it is a relatively new procedure with limited patient data, there is a limited supply of juvenile donor cartilage, it is a relatively expensive treatment option compared with other techniques, and as with any allograft tissue, disease transmission concerns exist.
Basic Science Evidence
Figure 1 (A) Medial talar shoulder OLT accessed through an anteromedial arthrotomy with plafondplasty. (B) The lesion underwent PJCAT. Notice the mechanically minced pieces in the surrounding fibrin glue. (Color version of figure is available online.)
donor availability, geometric contour discrepancies, and the uncertainty of delivering truly viable chondrocytes after allograft processing and impacting into place. Particulated juvenile cartilage allograft transplantation (PJCAT) is a new technique of transplantation of multiple fresh juvenile cartilage allograft tissue pieces, containing live cells within their native extracellular matrix, with fibrin adhesive securing the tissue pieces firmly inside the lesion (Fig. 1). This technique is in many ways similar to the osteochondral autograft transfer with the following differences: transplantation of particulated cartilage pieces instead of osteochondral plugs, the use of juvenile cartilage instead of adult cartilage, and graft fixation with fibrin adhesive instead of bony press-fit. Currently, the only graft material available for this procedure is DeNovo NT Natural Tissue Graft (Zimmer, Inc, Warsaw, IN). The cartilage pieces of this product are obtained, in compliance with Good Tissue Practice, from donors ranging in age from newborn to 13 years old; however, it is typically obtained from neomorts younger than 2 years.11 No stillborn or fetal tissue is used. Standard disease screening is
The concept of hyaline cartilage repair using particulate articular cartilage was first proposed in 1983 by Albrecht et al.13 The authors created full-thickness articular defects down to subchondral bone in adult rabbit patellae. The lesions were treated with nothing, collagen foam, collagen foam plus fibrin glue, autologous mechanically minced cartilage plus fibrin glue, or autologous mechanically minced cartilage plus collagen foam. None of the defects in the groups without minced cartilage demonstrated hyaline cartilage. On the contrary, 61% of the defects treated with minced cartilage demonstrated filling consistent with hyaline cartilage at 16 weeks. The authors reported an increase in the number of implanted chondrocytes and a change in morphology similar to juvenile chondrocytes. They speculated that the transformation of the chondrocytes to this quasi-“juvenile” status was because of the opening of the subchondral vessels, which provided an abundant supply of oxygen and nutrients resembling the physiological state before the end of skeletal maturity. Subsequently, Lu et al8 demonstrated, in a mouse subcutaneous pouch model, that chondrocytes from minced cartilage pieces were able to outgrow into polyglycolide-polylactide and polyglycolide-polycaprolactone scaffolds. The outgrowth was uniform by 6 weeks and the cells were surrounded by newly deposited extracellular matrix. Interestingly, the authors found an inverse relationship with minced cartilage piece size and efficiency of the outgrowth. In this same study, the authors filled goat trochlear defects with autologous minced cartilage pieces. At 6 months, hyalinelike cartilage with complete integration to the surrounding cartilage and subchondral bone was found. These data indicate that viable chondrocytes found in particulated cartilage grafts can migrate, multiply, and form a new hyalinelike cartilage tissue matrix within the host tissue. Adkisson et al14 compared the chondrogenic activity of human juvenile and adult chondrocytes. Chondrocytes from juvenile (o10 years) donors showed significantly greater extracellular matrix synthesis (sulfated glycosaminoglycan; S-GAG) than chondrocytes from mature donors. Moreover, the rate of
Particulated juvenile cartilage allograft transplantion S-GAG synthesis was greater than 100-fold for the juvenile chondrocytes. The authors also demonstrated 100- and 700fold decreased amounts of messenger RNA for type II and type IX collagen, respectively, in mature chondrocytes compared with the juvenile chondrocytes. They speculate that the decreased gene expression directly affects the ability of adult chondrocytes to form neocartilage in vivo. Likewise, they demonstrated a significantly increased growth rate for juvenile chondrocytes and that this cell population did not elicit an immunogenic reaction when transplanted into a xenogenic goat model, indicating immunoprivilage for juvenile chondrocytes. In an interesting study comparing adult and juvenile cartilage coculture, Bonasia et al15 demonstrated that juvenile chondrocytes cultured alone produced significantly more proteoglycans and S-GAG than juvenile chondrocytes cultured with adult chondrocytes in various proportions. More germane to PJCAT, coculture of mechanically minced juvenile and adult cartilage pieces resulted in a significantly higher proteoglycanDNA ratio than that by adult pieces alone in culture and a higher proteoglycan-DNA ratio than that by juvenile pieces alone in culture, but this was not significant. The proteoglycanDNA ratio was used as an outcome measure because it was considered the best approximation of the real amount of matrix production per cell. The authors proposed an explanation for the increased neocartilage produced with coculture of minced juvenile and adult cartilage fragments as follows: less neocartilage is produced in monoculture of juvenile pieces because of the relative absence of chemotactic factors contributed by the adult cartilage, whereas monoculture of adult cartilage produced less neocartilage because of the absence of juvenile cells capable of responding growth factors.
Clinical Evidence for PJCAT Recently, Coetzee et al16 presented a retrospective case series of 23 patients (24 ankles) treated with PJCAT at a mean follow-up of 16.2 months. The mean lesion surface size was 125 mm2 (range: 50-300 mm2) with a mean depth of 7 mm (range: 3-20 mm). All lesions had at least 1 dimension greater than or equal to 10 mm. The lesions were accessed via an open approach in 12 cases, an arthroscopic approach in 3 cases, and through an extended-portal open approach in 9 cases. Bone grafting was performed on lesions deeper than 5 mm. The mean postoperative 100 mm visual analog scale for pain was 24 (range: 0-93) and the mean American Orthopaedic Foot and Ankle Society ankle-hindfoot score was 85 (range: 23-100). The mean Foot and Ankle Ability Measure for activities of daily living was 55.1 (range: 52-58) and the mean Foot and Ankle Ability Measure for sports was 63.4 (range: 52-75). The mean postoperative SF-12 physical composite score was 46.4 (range: 42-51). The authors note that these outcomes scores are similar to published reports on patients who were treated with bone marrow stimulation, ACI, and matrix-induced ACI. Overall, 5 patients required reoperation to remove symptomatic osteotomy hardware, and 1 patient required an additional procedure to treat anterior
183 impingement. At the time of 2 of these procedures, the juvenile cartilage was minimally debrided. Additionally, during 3 reoperations, the International Cartilage Repair Society Cartilage Repair Assessment (protocol A) was used to assess the repair tissue. The 3 lesions were assessed at grade 2 (nearly normal repair). There was 1 partial graft delamination ( 25% of the graft) that was diagnosed at 16 months. The original lesion size of this patient was 180 mm2. Schon and Oji17 presented a case series of 57 OLTs treated with PJCAT. Data were collected prospectively on 17 ankles and retrospectively on 40 ankles. All patients had a minimum of 1-year follow-up. Approximately 73% of patients had more than 60% improvement (pain, function, and quality of life) at final follow-up. Of the patients, 80% were satisfied without or with minor reservation, 8% were satisfied with major reservations, and 12% were dissatisfied; 9% of them did not experience any relief of symptoms. On 1-year postoperative magnetic resonance imaging (MRI), using the magnetic resonance observation of cartilage repair tissue scoring system, 20% of defects were completely filled, 50% of defects demonstrated cartilage hypertrophy, and 30% were incompletely filled. Kruse et al18 presented a case of arthroscopically performed PJCAT to an OLT in a 30-year-old woman with a full-thickness posteromedial lesion that measured 7 mm 5 mm. At 2years following surgery, the patient was found to be pain free with no activity limitations. Bleazey and Brigido19 retrospectively reported on a series of 7 patients treated using a cylindrical allograft plug and PJCAT. The surgical technique was performed through a medial malleolar or fibular osteotomy in all patients. The lesion was assessed and then a size-matched reamer was used to ream past the subchondral plate into the cancellous bone. A cylindrical sponge allograft of matched diameter was then inserted and recessed to the level of the subchondral plate. The graft was then formed ex vivo by mixing particulated cartilage and fibrin glue into a size-matched mold. It was then secured with additional fibrin glue. All patients demonstrated significant improvement in each category of a custom 10-point scale that assessed their ability to ambulate upstairs, downstairs, and over 4 city blocks. The greatest improvement was in the ability to walk 4 city blocks. All patients would have the surgery performed again. However, all patients were followed up for only 6 months. PJCAT has also been used in lesions outside the talus. Bonner et al12 reported on PJCAT for a full-thickness patellar cartilage defect in a 36-year-old man. At 2-year follow-up, the patient demonstrated clinical improvement in both pain and function, based on International Knee Documentation Committee and Knee Injury and Osteoarthritis Outcome Score outcome measures. MRI demonstrated filling of the defect with repair tissue and near-complete resolution of preoperative bony edema. Tompkins et al20 reported on 15 knees of 13 patients who had Outerbridge grade 4 articular cartilage defects of the patella. The patients underwent open application of particulated juvenile cartilage and were followed up for a mean of 28.8 ⫾ 10.2 months. They were assessed with postoperative MRI and outcomes questionnaires. The mean International
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184 Cartilage Repair Society cartilage repair assessment score on MRI was 8.0 ⫾ 2.8, which the authors mention is a nearly normal score. In fact, 11 of 15 patients had normal or nearly normal scores. Of the 15 knees, 5 repairs demonstrated graft hypertrophy. The mean percentage of surface filled was 89.9% ⫾ 19.6% with all but 3 knees showing 90% filling or greater. Functionally, the mean postoperative visual analog scale (1-10) pain score was 1.9 ⫾ 1.4. The mean Tegner score was 5, consistent with a return to recreational sports or heavy labor.
PJCAT Indications and Contraindications The authors’ recommended indications for PJCAT include a symptomatic patient who has a primary OLT that is larger than 15 mm in 1 dimension or a patient who has undergone an unsuccessful marrow stimulation technique with continued symptoms and an OLT as evidenced on MRI. Shoulder and cystic lesions are not excluded. Contraindications to surgical management of OLTs include infection, medical comorbidities that preclude a surgical procedure, diffuse ankle arthritis, or uncorrected ankle malalignment. Specific recommended contraindications to PJCAT include large cystic or necrotic bony defects. Small cystic lesions with bony defects can be managed with concomitant bone grafting with PJCAT. In these instances, the authors have performed local bone grafting from the calcaneus, tibia, or iliac crest with application of the PJCAT graft in the same surgical setting.
Preoperative Planning An MRI is essential to assess the size of the cartilage defect for the purposes of defining the quantity of juvenile allograft needed. A computed tomography scan can be helpful to define the true extent of the bony lesion, as MRI often demonstrates the more diffuse surrounding bony reaction. Per the manufacturer of the only currently available PJCAT product, 1 pack of DeNovo NT Natural Tissue graft (Zimmer, Inc, Warsaw, IN) is recommended to treat each 2.5 cm2 of lesion surface area, with a recommended fill ratio of at least 50% of the lesion size (e.g., each pack of tissue graft contains enough cartilage to cover 1.25cm2 of surface area and the rest of the surface area is composed of the fibrin carrier). In practice, the authors attempt to completely fill the lesion’s surface area to the depth of the surrounding healthy cartilage, while allowing fibrin adhesive to interpose between cartilage pieces for good tissue fixation.
Open Technique The patient is positioned supine on the operating room table. A thigh tourniquet is applied. The operative leg may be placed in a padded leg holder for arthroscopy. In most cases, standard ankle arthroscopy is performed to confirm the size and location of the lesion. The location of the lesion is assessed while the ankle joint is ranged. This allows a better assessment as to whether the lesion can be approached though an arthrotomy with or without plafondplasty vs a medial or lateral malleolar osteotomy. The arthroscopy has additional benefit in diagnosing and potentially addressing additional pathology. Initial debridement can be performed using standard arthroscopic technique, although we routinely perform our local lesion debridement during the open part of the procedure to save operating room time. The arthroscopic equipment is then removed from the joint and preparation for the open procedure is undertaken. The arthroscopic light source is then turned off, until needed again, but keep the equipment sterile. Having the arthroscopic camera available during the open procedure allows visualization to the back of the joint to assess whether any cartilage pieces may have been dislodged during defect filling. The shaver can be helpful in debriding the lesion and the arthroscope can be used to assess lesion fill. Typically, the medial or lateral arthroscopy portal is incorporated into the arthrotomy skin incision. The soft tissues are retracted and bluntly dissected from the joint capsule. The capsule is then incised longitudinally. Every attempt should be made to preserve this tissue plane for capsular closure. The foot is plantar flexed to assess the visibility of the OLT. If the entire lesion is not visible, an anterior tibial plafondplasty is performed, but it is important to remember that perpendicular access is not needed for PJCAT. Most of the talus is accessible through an anterior medial or lateral arthrotomy and tibial plafondplasty.22 Using a curved quarter-inch osteotome, the superior and medial or lateral aspect of the anterior tibial plafond is removed (Fig. 2). Careful attention should be made
Techniques Both open and arthroscopic PJCAT techniques have been described.11,21 Open techniques include the use of an anterior tibial plafondplasty or a medial or lateral malleolar osteotomy.
Figure 2 A quarter-inch osteotome is used to create an anteromedial plafondplasty. (Color version of figure is available online.)
Particulated juvenile cartilage allograft transplantion to not remove more than 1 cmof the nonarticular tibia in any dimension. Only the minimal amount of tibia necessary to debride and fill the lesion should be removed. Smaller plafondplasties are generally not repaired. If the plafondplasty approaches 1 cm in any dimension or if loss of structural integrity is a concern, then consideration should be given to small-fragmentary screw or bioabsorbable pin fixation. Visualization may be further enhanced using of a Hintermann-style distractor or a lamina spreader secured to the tibia and talus with pins. If, after debridement, the base of the OLT requires bone grafting, the bone from the plafondplasty can be used. Alternatively, trephine obtained bone from the calcaneus, tibia, or iliac crest can be used. Occasionally, a medial or lateral malleolar osteotomy is necessary to access the lesion. This determination must be made after arthroscopy and an anteromedial or lateral arthrotomy should not be made. The techniques for medial or anterolateral tibial osteotomies are beyond the scope of this article. However, in 67 cases personally performed by the senior author (L.C.S.) to date, no osteotomies have been performed. If the lesion is posterior, then the patient should be positioned prone and a posterior approach is used to the ankle. Large lesions with margins within the posterior quarter of the talar dome are unlikely to be visualized with an anterior plafondplasty. However, it is important to stress the necessity of preoperative planning regarding lesion location. If the surgeon is unsure as to whether an osteotomy would be necessary, the small amount of time it takes to determine the location of the OLT during the initial arthroscopy can be very helpful for decision making. Once the lesion is visualized, a combination of a #15 blade and small curette can be used to debride the OLT. Debride the lesion until stable margins are achieved on all sides. Careful attention should be paid to the shoulder of the talus. If it is felt that the shoulder is not involved, every attempt should be made to leave the medial or lateral cartilage border at the shoulder. This helps to contain the cartilage-fibrin mixture in the lesion and not have it spill into the medial or lateral gutter. There is debate regarding the preparation of the base of the lesion for the addition of marrow stimulation (microfracture) by violating the subchondral plate. In all reality, with adequate debridement, the subchondral plate is often penetrated in at least 1 location. We routinely perform a microfracture at the base of the lesion. This is typically done with the tourniquet deflated to confirm the establishment of a bleeding bone base (Fig. 3A). Subsequently, we advise reinflating the tourniquet to maintain a dry base during defect filling (Fig. 3B). Next, the joint should be thoroughly irrigated and dried. Leave a sponge in the joint while preparing the particulated graft. The dry lesion bed permits better incorporation of the cubes by the fibrin glue within the defect. Prepare a fibrin adhesive. It is important to have extra fibrin delivery tips available as they can become clogged in between applications of fibrin glue to the defect. Now take the DeNovo NT Graft packet and turn it so that the pointed end of the plastic well faces the ground. For the DeNovo NT Graft, position the packet so that the narrow end of the plastic well faces
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Figure 3 The same anteromedial OLT from Figure 2. (A) The lesion underwent microfracture with the tourniquet deflated. Notice the bleeding base. (B) The same lesion after tourniquet inflation, joint irrigation, and drying with a sponge. Notice the marrow stimulation holes. In this case, marrow stimulation was performed using a 0.045in Kirschner wire and irrigation. (Color version of figure is available online.)
downward to allow the cartilage pieces to settle to the bottom. Peel back the foil covering, and using a 20-25 gauge needle and syringe, carefully aspirate the medium without removing any of the cartilage pieces. The foot can be positioned in plantar flexion and may then be swung over the side of the table to situate the base of the lesion as parallel to the floor as possible. This facilitates defect filling without the loss of fibrin glue or cartilage pieces into the back of the joint. Several methods can be employed to deliver the particulated cartilage to the lesion. Typically, the foil lid is cut into a strip and bent in the center to create a trough or the plastic packaging can be cut to a point (Fig. 4A). The cartilage pieces are then scooped into the trough (Fig. 4B), and the trough is brought into the joint space. Next, an elevator or equivalent instrument is used to push the cartilage pieces into the bed of the lesion until particulated cartilage completely covers the base. Fibrin glue and additional particulated
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Arthroscopic Technique Performing an all-arthroscopic PJCAT can be challenging. The diagnostic arthroscopy serves to ensure that complete access to the OLT can be obtained. The authors have a low threshold to move to an extended-portal approach or arthrotomy if OLT access or instrument working room is limited. An anterior arthroscopy is described here but the same procedure can be performed using posterior arthroscopy. The patient is placed supine on the operating room table with the foot at the end of the bed. The operative leg is placed in a leg holder to keep the hip and knee flexed. The extremity is then prepared for surgery and draped in the usual sterile fashion. A thigh tourniquet is used throughout the case. Next, noninvasive distraction is applied. Standard anteromedial and anterolateral portals are used, and routine arthroscopic examination of the ankle joint is performed. A probe is used to define and measure the lesion in multiple dimensions to ensure there is enough PJCAT material available. An arthroscopic shaver is introduced to debride any invaginated synovium that obscures
Figure 4 (A) The foil backing has been removed and a strip has been cut. The strip is bent longitudinally in the middle to act as a trough to contain the pieces. Alternatively, the plastic container can be cut into a point to deliver the pieces from the package. (B) The pieces have been loaded into the foil trough. (Color version of figure is available online.)
cartilage pieces are added in a layered fashion until the depth of the lesion is completely filled without the construct being raised (Fig. 5). An additional amount of fibrin glue is applied to the lesion to complete the particulated cartilage-fibrin glue construct. At this point, before the fibrin glue has completely set up, dorsiflex the ankle until the lesion is completely covered. Apply axial compression to use the contour of the tibial articular surface to mold the superior surface of the talar lesion. Maintain compression for 5 minutes. Suction out any residual fluid and excess congealed fibrin glue. Plantar flex the ankle and assess the lesion. Next, gently take the ankle through range of motion to assess the stability of the lesion. Do not irrigate the joint. If the joint requires irrigation, dorsiflex the ankle to protect the filled lesion and gently irrigate. Close the capsular tissue with size 0 absorbable figure-of-eight stitches. Irrigate the remaining wound, and close the subcutaneous layer with 3-0 absorbable suture and either 4-0 nonabsorbable vertical mattress stitches or a running 4-0 MONOCRYL stitch. Apply a well-padded splint with the ankle in neutral flexion.
Figure 5 (A) DeNovo pieces have been added to the base of the lesion. Fibrin glue is being applied. Often, some DeNovo pieces “cling” to the surrounding tissues; these are removed in the process. (B) The same lesion after addition of DeNovo pieces and fibrin glue in a layered fashion. (Color version of figure is available online.)
Particulated juvenile cartilage allograft transplantion the view of the OLT or that instruments form the working portal may pass by during the case. At this point, the arthroscopic water flow is shut off, and the joint is evacuated of fluid. The lack of fluid relaxes the soft tissues, and there may be additional soft tissue invagination. This allows the surgeon to assess the need for any additional soft tissue debridement. The arthroscopic flow is restored. Combinations of ring and scoop curettes are used to debride the lesion back to stable cartilage margins (Fig. 6A). The arthroscopic flow is again shut off and the joint is evacuated of arthroscopic fluid (Fig. 6B). A small suction tip, the shaver with suction on and the tip in the open position, or cotton-tipped applicators or pledgets are used to dry the joint (Fig. 7). The lack of arthroscopic fluid pressure allows the base of the lesion to bleed. Profuse bleeding from the base would make the rest of the procedure difficult and can be addressed using a small amount of fibrin glue at the base of the lesion. Additionally, epinephrine in the arthroscopic fluid throughout the case or epinephrine-soaked cotton-tipped applicators or pledgets can be used to decrease bleeding from the synovium. In cases of subtle bleeding, a fibrin glue base is not needed.
Figure 6 (A) A debrided medial shoulder lesion in which previous microfracture was unsuccessful. The lesion is viewed from the medial arthroscopic portal and has been debrided to stable margins. (B) The same lesion viewed from the lateral arthroscopic portal. Fluid flow has been turned off and the fluid has been evacuated. (Color version of figure is available online.)
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Figure 7 A cotton-tipped applicator is being used to dry the lesion bed. (Color version of figure is available online.)
Now take the DeNovo NT Graft packet and turn it so that the pointed end of the plastic well faces the ground. For the DeNovo NT Graft, position the packet so that the narrow end of the plastic well faces downward to allow the cartilage pieces to settle to the bottom. Peel back the foil covering, and using a 20-25 gauge needle and syringe, carefully aspirate the medium without removing any of the cartilage pieces. Next, the pieces are carefully loaded, in retrograde fashion, into the tip of a 2.7-mm arthroscopic cannula using a Freer elevator and the trocar. It is very important to recess the pieces so that they are not exposed and do not get caught in the soft tissues when introduced into the joint (Fig. 8A). Do not load all of the pieces at once. The authors routinely make 2-3 passes with 1 package of DeNovo NT. Under arthroscopic visualization, carefully insert the cannula into the ankle joint and dock it at the near edge of the lesion. Insert the cannula and very slowly push the pieces into the joint (Fig. 8B). Remove the cannula and trocar and insert a Freer elevator or similar arthroscopic tool to arrange the pieces uniformly in the lesion. Next, insert the fibrin glue tip through the arthroscopic portal and apply a small amount of glue. Occasionally, the tip provided with fibrin glue is too short and an angiocatheter without the needle is used or a needle itself can be used (Fig. 9A). Insert a Freer elevator or similar arthroscopic tool to mold the pieces uniformly in the lesion while the glue is increasing in viscosity (Fig. 9B). Repeat these steps until the lesion is completely filled. Allow the fibrin glue to set for 5-10 minutes until opaque (Fig. 10), and then gently range the ankle. The arthroscopic portals are closed with nylon and a wellpadded splint is placed with the ankle in a position to fully contain the lesion under the tibial plafond.
Postoperative Management The patient is kept with the splint in a non–weight-bearing state for 10-14 days. The sutures are removed at that point and the patient is placed in a removable boot brace. The patient remains non–weight-bearing except for range-of-motion
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Figure 8 (A) The 2.7-mm cannula is being introduced through the medial arthroscopic portal. Notice that the DeNovo pieces are recessed so they do not get lost going through the portal. (B) The cannula is placed on the lesion and the trocar is used to push the pieces into the joint. (Color version of figure is available online.)
exercises. Range-of-motion exercises entail weight-bearing deep knee bends for 20 minutes, 5 times per day out of the boot. At night, a night splint can be used to keep the lesion contained. Also, if the patient required lateral or medial ligament reconstruction the night splint will protect the repair. At the 6-week postoperative period, the patient may progress to full weight-bearing walking. The boot brace can be removed between the 6th and the 12th week as tolerated and a cloth lace-up brace can be used. Full plantar flexion is allowed during this time, provided there is no contraindication based on concomitant performed procedures. Physical therapy, strengthening exercises, the exercise bicycle, and water activities may be initiated at 6 weeks. Impact activities are not started until 6 months. If the patient can hold off from beginning major activities for as long as 2 years, there may be additional benefit to the healing cartilage graft.
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Figure 9 (A) A needle is used to introduce fibrin glue. (B) A Freer elevator is used to mold the DeNovo pieces into the lesion as the fibrin glue sets. (Color version of figure is available online.)
Reports of early follow-up demonstrate patient improvement. Basic science evidence demonstrates that this technique can restore hyaline cartilage. PJCAT delivery can be performed through all-open, arthroscopically assisted open, and allarthroscopic techniques.
Conclusion PJCAT is viable treatment option for OLTs that have failed previous operative management or primary OLTs that are likely to be unresponsive to marrow stimulation techniques.
Figure 10 The final appearance of the lesion after the fibrin glue has set and become opaque. (Color version of figure is available online.)
Particulated juvenile cartilage allograft transplantion
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