Fig. 46.1
Cartilage surface incongruency after mosaicoplasty
Fig. 46.2
Representative Fuji pressure-sensitive film imprints for the seven different conditions. Note increased color density at margins of empty defect and on elevated (proud) plugs
With respect to reconstructive surgical options to treat osteochondral injury, the concept of a cell-based “sandwich” technique has the potential for widespread use, if there is sufficient mitigation of associated costs and resource need. Of the available techniques described, the dual-layer, cell-based technique has the greatest potential to restore articular congruity. This is achievable through the surgical contouring of the restored osteochondral surface to match the native radius of curvature and the postoperative plastic adjustments that inherently occur as result of the forces from the opposing articular surface. Additionally, progress in biomaterial engineering has allowed for the development of three-dimensional scaffolds that are more malleable and therefore more amenable to secure seating within chondral defects, as opposed to periosteal tissue that was used by Petersen in the original method. Another important advancement in cell-based cartilage repair is the elimination of the two-stage ACI procedure. The use of autologous bone marrow aspirate concentrate in conjunction with biologic scaffolds, as described by Gobbi [7–9], has been introduced widely into clinical practice and is performed as a one-stage procedure, at considerably reduced cost compared to autologous chondrocyte procedures.
Recent advances in arthroscopic instrumentation have enabled the provision of minimally invasive procedures to treat chondral and osteochondral injury by methods of one-stage, single- or dual-layer, cell-based reconstruction techniques [10]. These developments in instrumentation and biomaterials have greatly reduced the need for procedures that involve invasive arthrotomies to treat chondral and osteochondral defects.
46.3 Knee
46.3.1 Introduction
Full-thickness cartilage injury may be associated with significant subchondral bone pathology and deficiency, leading to further challenges when undertaking cartilage restoration procedures of the knee. In cases of combined cartilage injury and subchondral bone loss, lesions may not be amenable to treat by conventional chondral only repair techniques. Numerous techniques of cartilage and subchondral bone restoration are currently used: debridement, bone marrow stimulation, autologous or allogenic osteochondral grafting, AMIC-like procedures, cell-based techniques such as autologous chondrocyte implantation (ACI, MACI), and mesenchymal stem cell scaffold-based implantation combined with subchondral bone restoration procedures.
Considering OCL treatment is needed to ask several important questions. Is osteochondral defect reconstruction in the knee necessary? Can procedure be done arthroscopically or with the use of arthrotomy? Is bone grafting necessary or maybe only chondral reconstruction procedure is sufficient? What is the depth of a lesion which needs bone grafting?
The first choice in OCL treatment in the knee is only debridement with loose body removal if necessary. Although some papers describe good results after this procedure in the case of OCD, Linden in his work revealed that almost all patients developed osteoarthritis in 33 years with noticeable worsening after 20 years from OCD identification [11].
Bone marrow stimulation technique like microdrilling, microfracture, or spongiolization in OCL treatment can be performed in smaller lesions <2cm2 with short- and mid-term good results, but poor quality and fulfillment don’t support knee joint congruence and don’t improve enough distribution of load; therefore, authors do recommend this technique only for small (<2cm2), shallow (<5 mm in depth) lesion in young patient pursuing sedentary lifestyle.
With respect to the knee joint OCL, autologous osteochondral transfers or osteochondral allograft transplantation is a well-accepted method of repair for a wide range of cartilage lesion size and depth of bony deficiency. Autologous osteochondral transfer repair technique is recommended to treat lesions about 1–4 cm2 and is limited by 8 cm2 lesion size [12]. Although this technique can be performed arthroscopically, lesion bigger than 2–3 cm2 is really challenging without miniarthrotomy. The advantage of this method is fast recovery, in sport especially. Autologous osteochondral transfer can cause donor site morbidity, particularly in the case of bone blocks >1–1.5 cm2 in diameter. A limitation of mosaicplasty is requirement to use one or more cylindrical plugs of any given diameter, and for that reason OCL can’t be fulfilled. The necessity of partly removing healthy cartilage and subchondral bone in the case of noncircular or irregular osteochondral lesions is further OATS technique limitation. Osteochondral allograft transplantation is further technique capable of repairing the damaged osteochondral unit; however, this is typically performed in an open fashion due to technique limitations. The use of allograft is reserved for large lesion, especially on the edge of the condyle, often after unsuccessful previous surgeries. Reconstitution of the anatomic contour of the articular surface may also be problematic with bigger osteochondral transfer or transplantation procedures, particularly if a mosaicplasty technique is employed.
In 1997 Kevin Stone published his own technique based on autologous osteochondral plugs (received like in mosaicplasty) impacted to paste. A paste was impacted into osteochondral lesion after its debridement to the level of cartilage base, but cartilage layer remained not fulfilled. The author presents good results after 10–23 years, but it is only case series without any control group [13].
Autologous chondrocyte implantation has been shown to provide durable cartilage repair and may also be used in conjunction with bone grafting to reconstitute subchondral bone deficiency [14]. There is no consensus about lesion depth which require filling with bone graft. In most papers authors used to perform this technique in bone loss from 5 to 10 mm in depth [15–17]. In cases of deep subchondral bone loss, “sandwich”-type ACI procedure may be used to reconstruct osteochondral lesions. Originally described by Peterson, the technique uses bone grafting in association with autologous chondrocytes contained between layered periosteal graft [17]. This technique has been modified by Bartlett et al., using a matrix-assisted chondrocyte implantation (MACI) technique in conjunction with bone grafting [18]. Unfortunately, the use of cell-based cartilage repair techniques with autologous chondrocytes may be limited by costs, as this is a two-stage procedure that requires expansion of chondrocyte cell lines off-site.
Single-stage cell-free scaffold-based AMIC-like techniques are available (described in chapter E.KON) [19]. Another single-stage scaffold-based cartilage repair technique using mesenchymal stem cells sourced from bone marrow (BMAC—bone marrow aspirate concentrate) has been developed. The hyaluronic acid-based scaffold embedded with bone marrow aspirate concentrate (HA-BMAC) provides comparable durability of repair to ACI techniques, at significantly reduced cost and operative time [7, 8, 20]. Cartilage repair using implantation HA-BMAC has demonstrated durable cartilage restoration at medium-term follow-up, with preferential formation of hyaline-like repair tissue [21]. This technique has provided good to excellent clinical outcomes in a wide range of lesion sizes within the knee, including multicompartment lesions over 20 cm2 in size [9].
Minimally invasive techniques of cartilage repair (ACI, AMIC-like techniques, HA-BMAC) are favored due to the lessened morbidity of surgery and the reduced postoperative recovery period. Arthroscopic cartilage restoration using a hyaluronic acid-based scaffold and activated bone marrow aspirate concentrate has been described previously and is used regularly by our institutions [10]. In cases of significant subchondral bone loss, this technique of cartilage repair may be used arthroscopically in conjunction with bone grafting to reconstruct a wide variety of osteochondral lesion types. We present the one-step arthroscopic technique of Biologic Inlay Osteochondral Reconstruction (BIOR) in the knee (Fig. 46.3a–e), using HA-BMAC and autologous bone graft inlay, to treat full-thickness cartilage lesions associated with significant subchondral bone loss.
Fig. 46.3
(a) An osteochondral defect of the femoral condyle cross-section; (b) biologic inlay consists of autogenous morselized bone with fibrin glue and bone marrow aspirate concentrate (BMAC) impacted into the defect; (c) the bone inlay covered with hyaluronate or collagen scaffold embedded with BMAC fixed with fibrin glue, (d) BIOR (biologic inlay osteochondral repair) the inlay consists of compacted and autologous bony chips with BMAC (bone marrow aspirate concentrate) molded in its surface which is covered with collagen or hyaluronic scaffold immersed with BMAC, (e) the regenerate 2 years after BIOR procedure, the remodeled bone layer usually seems to be more compact than surrounding
46.3.2 Surgical Technique
46.3.2.1 Patient Positioning and Arthroscopic Preparation of Cartilage Defect
The patient is positioned supine in a typical manner for knee arthroscopy, and the operative knee is appropriately exposed. The ipsilateral iliac crest is prepared in anticipation of bone marrow aspiration, and the planned site of autologous bone graft harvest is also exposed. We prefer the ipsilateral proximal tibia as the site for bone graft harvest, with exception of cases that require a larger volume of graft, where the ipsilateral iliac crest may be used. Preoperative MRI is routinely performed to measure the size of the osteochondral lesion and to estimate the required volume of bone graft inlay. The patient is typically given a general anesthesia. An examination of the knee under anesthesia is performed, and concurrent treatment of associated pathology may proceed as indicated. Treatment of bony malalignment and restoration of knee stability will provide the optimal environment for cartilage repair tissue to mature and remodel.
A diagnostic arthroscopy of all knee compartments is performed to locate sites of osteochondral injury and to completely delineate the cartilage defect dimensions (Fig. 46.4). A thorough assessment is necessary to ensure visualization of the entire defect to confirm the appropriateness of arthroscopic treatment. Loose osteochondral fragments should be identified and removed. Comfortable access to the relevant knee compartment may be improved by strategic placement of retraction instruments to manipulate adjacent joint capsule and synovium (Arthroscopic Retracting System, ATMED-Z. Rafalski, Katowice, Poland) [22]. Preparation of the cartilage defect begins with excision of all unstable chondral flaps. The defect margins should be debrided back to a stable, vertical wall of cartilage that is perpendicular to the natural contour of the subchondral plate. A prepared defect that is well contained circumferentially is preferred, as this provides a more favorable environment for cartilage repair tissue to mature. Specialized arthroscopic instruments are often used at our institution to achieve consistent perpendicularity of the cartilage wall surrounding the defect (Chond-rectomes Set, ATMED-Z. Rafalski, Katowice, Poland) (Fig. 46.5a). The condition of subchondral bone at the base of the defect should be examined in detail to identify bone deficiency that will be amenable to application of a bone graft inlay to restore the natural radius of curvature of the subchondral articular surface. Any calcified cartilage located within the base of the defect should be removed, and areas of planned bone grafting should be debrided back to healthy bone. The surface area of the defect should be assessed using an arthroscopic measuring device or a template in order to accurately size-match the HA-BMAC graft.
Fig. 46.4
OCL assessment during knee joint arthroscopic inspection
Fig. 46.5
Biologic Inlay Osteochondral Reconstruction: (a) cartilage debridement with chondrectomes – loose cartilaginous tissue removing, defect periphery preparing to obtain a wellshouldered cartilage walls; base of defect preparing (layer of calcified cartilage removing); subchondral bone debriding to expose healthy bone, (b) prepared bone graft is applied to the base of the defect using the specialized applicator, (c) arthroscopic paddle uses to contour and compress the graft (matching the natural radius of curvature of the subchondral surface), (d) HA-BMAC graft is securely press-fit into the defect (fibrin glue may be applied to the periphery of the graft to further secure the implant), (e) arthroscopic look of reconstructed OCL
46.3.2.2 HA-BMAC and Bone Graft Inlay Preparation
After estimating the volume of required bone graft, autologous cancellous bone harvest should proceed from either the ipsilateral proximal tibia or iliac crest. Bone marrow is aspirated from the ipsilateral iliac crest and a commercially available system is used to prepare the bone marrow concentrate (Harvest BMAC System, Terumo BCT). The morselized bone chips are inserted into the box chamber of the graft applicator. Several drops of BMAC and fibrin glue are added to the bone chips, and the graft is compressed into the 10 mm diameter barrel of the applicator. In the absence of such a bone inlay applicator, the bone chips may simply be mixed in a dish and later applied to the defect using an arthroscopic paddle or spoon via a valveless cannula or a halfpipe.
The three-dimensional hyaluronic acid-based scaffold (Hyalofast, Anika Therapeutics, Srl, Abano Terme, Italy) is appropriately size-matched to the defect dimensions to more easily contain the BMAC and apply it to the scaffold. The malleable HA-BMAC graft is created by combining BMAC with the hyaluronic acid-based scaffold.
46.3.2.3 Dry Arthroscopic Biologic Inlay Osteochondral Reconstruction Procedure
A fluid form the joint is drained from the knee and reevaluated the prepared osteochondral defect to confirm complete visualization. Prepared bone graft is applied to the base of the defect using the specialized applicator or a preferred chosen arthroscopic instrument (Fig. 46.5a). Bony deficiency at the base of the defect is reconstituted with the bone graft inlay using an arthroscopic paddle to contour and compress the graft. Recreation of the natural radius of curvature of the articular surface is a priority (Fig. 46.5a). Using a grasper or non-toothed forceps, HA-BMAC is inserted into the appropriate knee compartment via a valveless cannula or halfpipe, and the graft is placed into the repair site. Graft is securely press-fit within the defect, and the contour of the dual-layer repair structure is reexamined circumferentially to ensure that the expected radius of curvature has been achieved (Fig. 46.5b–d). Under arthroscopic visualization, the knee is gently cycled repeatedly to confirm secure seating of the BIOR construct. Fibrin glue may be added to the graft to provide greater security [23] (Fig. 46.5e). All surgical wounds are closed and covered by sterile dressings. The operative knee is immobilized in a brace set to correspond to the articular tibiofemoral contact angle (typically 40° of flexion) after the repair of osteochondral lesions within the medial or lateral compartments. The advantages/limitations of this surgical procedure are summarized in Table 46.1.
Table 46.1.
Advantages and limitations of biologic inlay osteochondral reconstruction
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