- Email: [email protected]
Microfracture and Ability to Return to Sports After Cartilage Surgery
Microfracture and Ability to Return to Sports After Cartilage Surgery D. Josh Miller, MD, and Robert H. Brophy, MD Microfracture is a simple, effective first-line treatment for small articular cartilage defects in the knee joint. The lesions should be isolated to the articular cartilage with no loss of bone and have a circumferential shoulder of intact cartilage. Postoperative rehabilitation involves 4-6 weeks of protected weight bearing and continuous passive motion. Younger, lighter patients with a shorter duration of symptoms have better outcomes after microfracture. Femoral lesions are associated with better outcomes than patellofemoral lesions are. The repair tissue generated by microfracture is fibrous with uncertain durability, especially in more active patients. Athletes can return to sport after articular cartilage surgery, but the data regarding this are relatively limited. Optimal indications, rehabilitation, timing of return to sport, and durability of repair deserve further study in the athletic patient population. Oper Tech Orthop 24:240-245 C 2014 Elsevier Inc. All rights reserved. KEYWORDS microfracture, marrow stimulation, cartilage defect, grade IV chondromalacia
Introduction
A
rticular cartilage injuries are being identified with increasing frequency, particularly in young and athletic individuals. Although the articular joint surface can tolerate substantial stress and load, injuries to this surface can be caused by either acute direct trauma or chronic repetitive overloading. These injuries can occur in isolation or in conjunction with other conditions, particularly ligamentous or meniscal injury, joint instability, or extremity malalignment. Injuries to articular cartilage have limited healing potential owing to their avascularity and minimal migration and propagation of chondrocytes. As such, these injuries rarely demonstrate spontaneous healing and can be a source of persistent pain and functional limitation.1,2 In addition, the damage caused by the injury can initiate a series of mechanical and chemical events that may lead to further degeneration and eventual end-stage arthritis.2 Therefore, the goals of articular cartilage treatment are focused on restoring a durable joint
Department of Orthopaedic Surgery, Washington University School of Medicine, St Louis, MO. Address reprint requests to Robert H. Brophy, MD, Department of Orthopaedic Surgery, Washington University School of Medicine, 14532 South Outer Forty Dr, Chesterfield, MO 63017. E-mail: brophyr@wudosis. wustl.edu
240
http://dx.doi.org/10.1053/j.oto.2014.05.003 1048-6666/& 2014 Elsevier Inc. All rights reserved.
surface to alleviate pain, restore function, and minimize further chondral degeneration. Although there are multiple modalities to treat articular cartilage lesions, microfracture has been recognized as a viable first-line treatment option for management of articular cartilage injuries because of its availability, minimal morbidity, low cost, and technical simplicity.3 The technique involves penetrating the subchondral bone at the site of the articular lesion to stimulate clot formation.4-6 The clot contains pluripotent mesenchymal stem cells derived from bone marrow that can ultimately produce fibrocartilage within the defect. Although this fibrocartilage does fill the defect, it contains variable amounts of type II collagen and has been shown to have different mechanical properties than the hyaline cartilage found on the normal articular surface.3,7 Consequently, the long-term durability of the repair and clinical outcomes following microfracture are unclear.3-6,8-10 Microfracture performed in combination with additional techniques intended to promote regeneration of cartilage is commonly referred to as enhanced microfracture. These techniques use different commercially available products to form a scaffold or substrate over the chondral lesion on which cartilage can grow. These products may include minced allograft extracellular matrix, hydrogels, or biocompatible polymers and are mixed with autologous blood to form a paste that is applied directly to the lesion immediately
Return to sports after cartilage surgery following standard microfracture. Following this, a biocompatible adhesive such as fibrin glue is then typically applied, securing the mixture in the lesion. The goal of these different methods is to increase the quantity of cartilage formation, while also improving the quality by creating more hyalinelike cartilage. Ongoing research focuses on further determining the efficacy and outcomes of these enhanced microfracture techniques compared with standard microfracture technique.11,12 Other marrow stimulation techniques including subchondral drilling have also been described.11,12 Although there are commercially produced drills specifically designed for these techniques, a small regular drill bit (o2 mm) can also be used. Advocates of drilling argue that it provides better access and flow to the bone marrow through open, unimpacted tunnels. However, concerns with drilling include the potential risks of thermal damage to surrounding bone, the hole shape (cylindrical vs conical), and the benefits of bone impaction vs removal. Although current trends show that microfracture is used more commonly than drilling techniques, research in animal models has not shown significant differences between these techniques.13,14
Indications Microfracture is indicated for treatment of full-thickness cartilage defects in the articular, weight-bearing portions of the knee and has also been used on the articular surfaces of other joints including the hip, ankle, shoulder, and elbow.11-12,15-17 Microfracture is not an optimal choice for lesions with involvement of the underlying bone. Furthermore, the lesions should be surrounded by a shoulder of intact cartilage to facilitate clot formation and retention. Patients with acute symptomatic articular cartilage lesions should be treated surgically as soon as practically possible as these lesions have demonstrated poor healing potential. Furthermore, better outcomes have been demonstrated with shorter duration of symptoms before microfracture.18,19 Conservative management including anti-inflammatory drugs, articular injections, and activity modification is appropriate first-line treatment in chronically symptomatic chondral lesions, although these too have poor healing and may eventually require surgical management. Although there are few contraindications for this technique, several factors have been shown to significantly affect patient outcomes. Patient age has been shown to be a major factor influencing outcomes, with patients younger than 40 years showing significantly better results.4-6,8-10,18,19 Similarly, although microfracture has been used on lesions of varying sizes, better results have been found with defects smaller than 2 cm².3-6,8-10,18,19 Lower body mass index, contained lesions (those completely surrounded by good articular cartilage), and a shorter duration of symptoms have also shown improved results.3-6,8-10,18,19 Given the importance of strict compliance with postoperative rehabilitation, a relative contraindication would be patients who would be unable to comply with the restrictions
241 and instructions involved in their postoperative care. In addition, this procedure is contraindicated in patients who have substantial subchondral bone loss or damage at the lesion, as microfracture requires the subchondral architecture and morphology to be intact for the fibrocartilage layer to maintain joint congruity. Other relative contraindications include patients with diffuse or generalized joint degeneration, inflammatory arthritis, or advanced age.18,19 Given the low morbidity, technical ease, and low cost of this procedure, most factors are considered relative rather than absolute contraindications. However, because outcomes can be significantly influenced by these factors, patient expectations should be appropriately managed when microfracture is used in less-than-ideal clinical situations. Chondral injuries are often associated with other pathology including ligamentous injury, meniscal tears, knee instability, and joint malalignment. Irrespective of whether these issues caused the chondral lesion, the management of the chondral lesion should coincide with treatment of these concurrent problems to avoid poor outcomes or failure of the articular surface repair. Alignment is particularly important, and patients with mechanical overload of the treated compartment should be treated with concomitant realignment at the time of microfracture.8 Specifically when including microfracture with other procedures, the order of the procedures should be considered to minimize disruption of clot formation from arthroscopic flow, pump pressure, or irrigation. Owing to this, microfracture, and specifically penetration of the subchondral plate, is often delayed until the end of a procedure, just before removal of arthroscopic equipment.
Surgical Technique If performed in isolation, this procedure can be done on an outpatient basis with either regional or general anesthesia. Once adequate anesthesia has been achieved, the patient should be positioned supine on the operative table using the surgeon’s preferred setup and leg holder for standard knee arthroscopy. Tourniquet placement and use throughout the arthroscopic procedure is surgeon dependent. However, if inflated, the tourniquet should be released at the completion of the procedure to fully assess adequate depth of the microfracture holes by the presence of blood and fat droplet egress. We typically place but do not inflate the tourniquet in cases with planned microfracture. Standard arthroscopic portals (medial and lateral parapatellar portals with or without outflow) typically provide adequate access to most articular lesions, although the specific location of the lesion may influence particular placement of these portals. If necessary, accessory portals can be made; however, in our experience these are very rarely indicated. Open arthrotomy is almost never necessary, even for patellar lesions. Following portal placement, a thorough diagnostic knee arthroscopic examination is performed. The chondral lesion is identified and probed to assess the depth, size, and extent of the lesion particularly noting any unstable or loose cartilage
D. Josh Miller, R.H. Brophy
242
Figure 1 Cartilage lesion with intact shoulder. (Color version of figure is available online.)
flaps. The lesion is then debrided back to a stable chondral shoulder, removing all flaps and loose cartilage using arthroscopic shavers and biters (Fig. 1). Careful removal of the calcified cartilage layer is achieved with manual curettage and has been demonstrated to be important in optimizing results.20 However, overly aggressive curettage can destabilize the subchondral architecture or articular morphology, potentially impairing healing. Similarly, incomplete debridement or failure to completely remove cartilage from the subchondral surface may also lead to suboptimal outcomes. Therefore, care should be taken to create an appropriate bony surface for clot adhesion (Fig. 2). After the subchondral surface has been prepared, any concomitant surgical procedures should be completed. Microfracture should be the last part of any knee arthroscopy, following any meniscalor ligamentous procedures. Open extra-articular procedures may be completed after microfracture. Once the lesion is prepared and other intra-articular surgery completed, arthroscopic awls are used to manually create the microfracture holes. These awls are specifically designed to create a hole that is 2-4 mm in diameter and are available in variable angles usually ranging from 301-901 (Fig. 3). For most condylar lesions, a 451 or 601 awl provides adequate access to the lesion. For patellar lesions, a 901 awl is often
Figure 3 Microfracture awls. (Color version of figure is available online.)
necessary. A mallet should be used for impaction of the awls. However, when using higher degree awls or with softer subchondral bone, manual impaction can help prevent sheering and damage to the osseous architecture. The holes should be made perpendicular to the lesion surface, spaced approximately 3-4 mm apart to maintain the integrity of the osseous structure and rim of each hole. Adequate hole depth is typically 3-4 mm, but it should be verified by the presence of bleeding or fat droplets from the created hole. Holes are first made on the periphery along the cartilage shoulder (Figs. 4 and 5) and then advanced centrally in a honeycomb or grid pattern (Fig. 6). Holes can also be drilled rather than impacted. Commercially available microfracture drills provide preset depths of 4 or 6 mm. Drill holes of similar depth can be made using a standard drill bit (o2 mm). Hole configuration and depth assessment should be done in a similar fashion as with impaction microfracture, perpendicular to the subchondral plate in a honeycomb pattern. On completion of either technique, the tourniquet should be released and the arthroscopic pump turned down or off to visualize egress of bleed and fat droplets from all of the microfracture holes (Fig. 7). If this is not seen, the holes without egress should be carefully impacted deeper until blood or fat droplets are seen. Once all holes are verified and of adequate depth, the arthroscopic equipment can be removed. All portals are then closed and dressed according to surgeon preference. No drains should be used, as this can undermine clot formation and retention.
Rehabilitation
Figure 2 Curette is used to remove calcified cartilage. (Color version of figure is available online.)
Although there is some variability between different rehabilitation protocols, compliance with the postoperative rehabilitation program is imperative to optimize patient outcomes. Initial rehabilitation focuses on providing an environment to encourage clot adherence and fibrocartilage formation while also maintaining joint range of motion (ROM). The most
Return to sports after cartilage surgery
243 cutting, pivoting, and jumping should be delayed for 4-6 months.
Return to Sports Return to sport after articular cartilage surgery has a limited but growing body of evidence, with the most extensive literature on return to sport after microfracture. There are slightly fewer data available on return to sport after cellular techniques, followed by autograft and allograft. Recovery from articular cartilage surgery is particularly important and challenging in athletes as they want to get back to as much as possible as soon as possible. Return to sport has been studied most extensively in athletes undergoing microfracture. In a systematic review of chondral defects in athletes, 8 of 11 studies reported return to play after
Figure 4 Initiate microfracture around the periphery of the lesion. (Color version of figure is available online.)
common rehabilitation protocols use a combination of continuous passive motion (CPM) and protected weight bearing based on the location of the lesion.19 Microfracture performed on the tibiofemoral joint (femoral condyles and tibial plateau) requires a period of 4-6 weeks of non–weight bearing. A CPM machine is utilized immediately postoperatively, starting at 01-301, advancing up to 01-1201 as tolerated, for 6-8 hours a day. Patellofemoral lesions on the trochlea or patella protect the clot with a leg brace locked in extension while weight bearing for 4-6 weeks. CPM for these lesions is typically limited to 01-301 for 6-8 hours a day to minimize shear on the clot. After 4-6 weeks, weight bearing and ROM are advanced, with full weight bearing and ROM achieved at 6-8 weeks. Leg strengthening and resistance training then becomes the focus of rehabilitation and can include stationary bike, band training, and closed chain exercises. However, activities involving
Figure 5 Continue along periphery of lesion with microfracture. (Color version of figure is available online.)
D. Josh Miller, R.H. Brophy
244 microfracture with an overall average of 59% (range: 25%100%).21 In another review pooling data from studies of athletes undergoing knee articular cartilage surgery, the rate of return to play was 66% ⫾ 6% (range: 44%-100%) in 787 athletes treated with microfracture.22 In a couple of studies with athletes from a variety of sports undergoing microfracture, the rate of return to play ranged from 44%-77%, with 57%71% getting back to the same or higher level of competition.23 Professional basketball players have been shown to have a 67%-79% return to play by 25-30 weeks after undergoing a microfracture.24,25 Athletes were 8.2 times less likely to return the next season than controls were.25 Those who returned to professional basketball played at a significantly lower level than they were before injury and only 58% were able to play at least one more season.24 Professional American football players have a 76% rate of return to play after undergoing a microfracture, getting to an additional 4.6 seasons and 56 games on average.6 There are also reasonable data on return to sport after autologous cellular implantation (ACI) in athletes, with a 67%78% rate of return to sport.21,22 A significant proportion of return to sport data after ACI come from soccer players and the return to sport tends to occur later after ACI compared with microfracture. There are less data on return to sport after osteochondral autograft transfer (OAT), but the available studies are encouraging, with a rate of return to sport of 91%-93%.21,22 A study has reported an 88% rate of return to activity in athletes with chondral injury of the knee treated with osteochondral allografts.26
Figure 7 Let down the pump pressure and tourniquet (if necessary) to confirm blood flow through microfracture.
A couple of comparative studies have looked at return to sport after articular cartilage surgery. In a comparison of microfracture to OAT in a cohort of predominantly soccer and basketball players, there was a higher return to preinjury level of competition after undergoing OAT (93%) compared with after undergoing microfracture (52%).27 This study reported a decrease in outcomes associated with lesions larger than 2 cm for microfracture not seen for OAT. Another comparison of microfracture to second-generation ACI in soccer players reported similar return to sport rates (80% vs 86%, respectively) with a quicker return after microfracture (median ¼ 8 months) than ACI (median ¼ 12.5 months).28 The limited body of evidence available to date suggests that athletes can get back to sport after surgery to restore articular cartilage in the knee. Although microfracture may facilitate a relatively quick return to sport, it may not be ideal for larger lesions, and its durability is unclear. Tissue transplantation and implantation may have some advantages in return to sport and durability but face limitations in availability and cost. Athletes should be counseled about their various treatment options and the potential tradeoffs and more investigation is needed to better define the optimal indications, techniques, rehabilitation, and outcomes in these high-demand patients.
Summary Microfracture is a readily available single-stage, arthroscopic technique. Technically easy and relatively low cost, it is ideal for smaller lesions with a stable shoulder of surrounding cartilage and can be used for incidental lesions discovered at the time of surgery. Microfracture results in tissue fill with fibrocartilage, which can be unpredictable. Even with complete filling of the lesion, the durability of the tissue is uncertain, with an estimated lifespan of 2-5 years in high-demand individuals.29 Overall, microfracture is a safe, cost-effective first-line treatment with relatively low morbidity.
References Figure 6 Move into the central portion of the lesion after microfracture of the periphery has been completed.
1. Shapiro F, Koide S, Glimcher MJ: Cell origin and differentiation in the repair of full-thickness defects of articular cartilage. J Bone Joint Surg Am 75:532-553, 1993
Return to sports after cartilage surgery 2. O’Driscoll SW: The healing and regeneration of articular cartilage. J Bone Joint Surg Am 80:1795-1812, 1998 3. Mithoefer K, Williams 3rd RJ, Warren RF, et al: The microfracture technique for the treatment of articular cartilage lesions in the knee. A prospective cohort study. J Bone Joint Surg Am 87:1911-1920, 2005 4. Steadman JR, Rodkey WG, Singleton SD, et al: Microfracture technique for full-thickness chondral defects. Technique and clinical results. Oper Tech Orthop 7:300-304, 1997 5. Steadman JR, Briggs KK, Rodrigo JJ, et al: Outcomes of microfracture for traumatic chondral defects of the knee: Average 11-year follow-up. Arthroscopy 19:477-484, 2003 6. Steadman JR, Rodkey WG, Rodrigo JJ: Microfracture: Surgical technique and rehabilitation to treat chondral defects. Clin Orthop Relat Res 391 (suppl):S362-S369, 2001 7. Frisbee DD, Oxford JT, Southwood L, et al: Early events in cartilage repair after subchondral bone microfracture. Clin Orthop Relat Res 407:215-227, 2003 8. Gobbi A, Karnatzikos G, Kumar A: Long-term results after microfracture treatment for full-thickness knee chondral lesions in athletes. Knee Surg Sports Traumatol Arthrosc 2013 Sep 20. [Epub ahead of print] 9. Solheim E, Øyen J, Hegna J, et al: Microfracture treatment of single or multiple articular cartilage defects of the knee: A 5-year median follow-up of 110 patients. Knee Surg Sports Traumatol Arthrosc 4:504-508, 2010 10. Goyal D, Keyhani S, Lee EH, et al: Evidence-based status of microfracture technique: A systematic review of level I and II studies. Arthroscopy 29:1579-1588, 2013 11. Tuan RS, Chen AF, Klatt BA: Cartilage regeneration. J Am Acad Orthop Surg 21:303-311, 2013 12. Steinwachs MR, Guggi T, Kreuz PC: Marrow stimulation techniques. Injury 1(suppl):S26-S31, 2008 13. Chen H, Sun J, Hoemann CD, et al: Drilling and microfracture lead to different bone structure and necrosis during bone-marrow stimulation for cartilage repair. J Orthop Res 27:1432-1438, 2009 14. Kok AC, Tuijthof GJ, den Dunnen S, et al: No effect of hole geometry in microfracture for talar osteochondral defects. Clin Orthop Relat Res 471:3653-3662, 2013 15. El Bitar YF, Lindner D, Jackson TJ, et al: Joint-preserving surgical options for management of chondral injuries of the hip. J Am Acad Orthop Surg 22:46-56, 2014 16. Hannon CP, Murawski CD, Fansa AM, et al: Microfracture for osteochondral lesions of the talus: A systematic review of reporting of outcome data. Am J Sports Med 41:689-695, 2013
245 17. Gross CE, Chalmers PN, Chahal J, et al: Operative treatment of chondral defects in the glenohumeral joint. Arthroscopy 28:1889-1901, 2012 18. Salzmann GM, Sah B, Sudkamp NP, et al: Clinical outcome following the first-line single lesion microfracture at the knee joint. Arch Orthop Trauma Surg 133:303-310, 2013 19. Mithoefer K, McAdams T, Williams RJ, et al: Clinical efficacy of the microfracture technique for articular cartilage repair in the knee: An evidence-based systematic analysis. Am J Sports Med 37:2053-2063, 2009 20. Frisbie DD, Trotter GW, Powers BE, et al: Arthroscopic subchondral bone plate microfracture technique augments healing of large chondral defects in the radial carpal bone and medial femoral condyle of horses. Vet Surg 28:242-255, 1999 21. Harris JD, Brophy RH, Siston RA, et al: Treatment of chondral defects in the athlete’s knee. Arthroscopy 26:841-852, 2010 22. Mithoefer K, Hambly K, Della Villa S, et al: Return to sports participation after articular cartilage repair in the knee: Scientific evidence. Am J Sports Med 37(suppl 1):167S-176S, 2009 23. Blevins FT, Steadman JR, Rodrigo JJ, et al: Treatment of articular cartilage defects in athletes: An analysis of functional outcome and lesion appearance. Orthopedics 21:761-767, 1998. [discussion 7-8] 24. Cerynik DL, Lewullis GE, Joves BC, et al: Outcomes of microfracture in professional basketball players. Knee Surg Sports Traumatol Arthrosc 17:1135-1139, 2009. ([Epub 2009 Mar 20]) 25. Namdari S, Baldwin K, Anakwenze O, et al: Results and performance after microfracture in National Basketball Association athletes. Am J Sports Med 37:943-948, 2009 26. Krych AJ, Robertson CM, Williams 3rd RJ: Return to athletic activity after osteochondral allograft transplantation in the knee. Am J Sports Med 40:1053-1059, 2012 27. Gudas R, Stankevicius E, Monastyreckiene E, et al: Osteochondral autologous transplantation versus microfracture for the treatment of articular cartilage defects in the knee joint in athletes. Knee Surg Sports Traumatol Arthrosc 14:834-842, 2006 28. Kon E, Filardo G, Berruto M, et al: Articular cartilage treatment in highlevel male soccer players: A prospective comparative study of arthroscopic second-generation autologous chondrocyte implantation versus microfracture. Am J Sports Med 39:2549-2557, 2011 29. Mithoefer K, Williams 3rd RJ, Warren RF, et al: High-impact athletics after knee articular cartilage repair: A prospective evaluation of the microfracture technique. Am J Sports Med 34:1413-1418, 2006
Introduction
A
rticular cartilage injuries are being identified with increasing frequency, particularly in young and athletic individuals. Although the articular joint surface can tolerate substantial stress and load, injuries to this surface can be caused by either acute direct trauma or chronic repetitive overloading. These injuries can occur in isolation or in conjunction with other conditions, particularly ligamentous or meniscal injury, joint instability, or extremity malalignment. Injuries to articular cartilage have limited healing potential owing to their avascularity and minimal migration and propagation of chondrocytes. As such, these injuries rarely demonstrate spontaneous healing and can be a source of persistent pain and functional limitation.1,2 In addition, the damage caused by the injury can initiate a series of mechanical and chemical events that may lead to further degeneration and eventual end-stage arthritis.2 Therefore, the goals of articular cartilage treatment are focused on restoring a durable joint
Department of Orthopaedic Surgery, Washington University School of Medicine, St Louis, MO. Address reprint requests to Robert H. Brophy, MD, Department of Orthopaedic Surgery, Washington University School of Medicine, 14532 South Outer Forty Dr, Chesterfield, MO 63017. E-mail: brophyr@wudosis. wustl.edu
240
http://dx.doi.org/10.1053/j.oto.2014.05.003 1048-6666/& 2014 Elsevier Inc. All rights reserved.
surface to alleviate pain, restore function, and minimize further chondral degeneration. Although there are multiple modalities to treat articular cartilage lesions, microfracture has been recognized as a viable first-line treatment option for management of articular cartilage injuries because of its availability, minimal morbidity, low cost, and technical simplicity.3 The technique involves penetrating the subchondral bone at the site of the articular lesion to stimulate clot formation.4-6 The clot contains pluripotent mesenchymal stem cells derived from bone marrow that can ultimately produce fibrocartilage within the defect. Although this fibrocartilage does fill the defect, it contains variable amounts of type II collagen and has been shown to have different mechanical properties than the hyaline cartilage found on the normal articular surface.3,7 Consequently, the long-term durability of the repair and clinical outcomes following microfracture are unclear.3-6,8-10 Microfracture performed in combination with additional techniques intended to promote regeneration of cartilage is commonly referred to as enhanced microfracture. These techniques use different commercially available products to form a scaffold or substrate over the chondral lesion on which cartilage can grow. These products may include minced allograft extracellular matrix, hydrogels, or biocompatible polymers and are mixed with autologous blood to form a paste that is applied directly to the lesion immediately
Return to sports after cartilage surgery following standard microfracture. Following this, a biocompatible adhesive such as fibrin glue is then typically applied, securing the mixture in the lesion. The goal of these different methods is to increase the quantity of cartilage formation, while also improving the quality by creating more hyalinelike cartilage. Ongoing research focuses on further determining the efficacy and outcomes of these enhanced microfracture techniques compared with standard microfracture technique.11,12 Other marrow stimulation techniques including subchondral drilling have also been described.11,12 Although there are commercially produced drills specifically designed for these techniques, a small regular drill bit (o2 mm) can also be used. Advocates of drilling argue that it provides better access and flow to the bone marrow through open, unimpacted tunnels. However, concerns with drilling include the potential risks of thermal damage to surrounding bone, the hole shape (cylindrical vs conical), and the benefits of bone impaction vs removal. Although current trends show that microfracture is used more commonly than drilling techniques, research in animal models has not shown significant differences between these techniques.13,14
Indications Microfracture is indicated for treatment of full-thickness cartilage defects in the articular, weight-bearing portions of the knee and has also been used on the articular surfaces of other joints including the hip, ankle, shoulder, and elbow.11-12,15-17 Microfracture is not an optimal choice for lesions with involvement of the underlying bone. Furthermore, the lesions should be surrounded by a shoulder of intact cartilage to facilitate clot formation and retention. Patients with acute symptomatic articular cartilage lesions should be treated surgically as soon as practically possible as these lesions have demonstrated poor healing potential. Furthermore, better outcomes have been demonstrated with shorter duration of symptoms before microfracture.18,19 Conservative management including anti-inflammatory drugs, articular injections, and activity modification is appropriate first-line treatment in chronically symptomatic chondral lesions, although these too have poor healing and may eventually require surgical management. Although there are few contraindications for this technique, several factors have been shown to significantly affect patient outcomes. Patient age has been shown to be a major factor influencing outcomes, with patients younger than 40 years showing significantly better results.4-6,8-10,18,19 Similarly, although microfracture has been used on lesions of varying sizes, better results have been found with defects smaller than 2 cm².3-6,8-10,18,19 Lower body mass index, contained lesions (those completely surrounded by good articular cartilage), and a shorter duration of symptoms have also shown improved results.3-6,8-10,18,19 Given the importance of strict compliance with postoperative rehabilitation, a relative contraindication would be patients who would be unable to comply with the restrictions
241 and instructions involved in their postoperative care. In addition, this procedure is contraindicated in patients who have substantial subchondral bone loss or damage at the lesion, as microfracture requires the subchondral architecture and morphology to be intact for the fibrocartilage layer to maintain joint congruity. Other relative contraindications include patients with diffuse or generalized joint degeneration, inflammatory arthritis, or advanced age.18,19 Given the low morbidity, technical ease, and low cost of this procedure, most factors are considered relative rather than absolute contraindications. However, because outcomes can be significantly influenced by these factors, patient expectations should be appropriately managed when microfracture is used in less-than-ideal clinical situations. Chondral injuries are often associated with other pathology including ligamentous injury, meniscal tears, knee instability, and joint malalignment. Irrespective of whether these issues caused the chondral lesion, the management of the chondral lesion should coincide with treatment of these concurrent problems to avoid poor outcomes or failure of the articular surface repair. Alignment is particularly important, and patients with mechanical overload of the treated compartment should be treated with concomitant realignment at the time of microfracture.8 Specifically when including microfracture with other procedures, the order of the procedures should be considered to minimize disruption of clot formation from arthroscopic flow, pump pressure, or irrigation. Owing to this, microfracture, and specifically penetration of the subchondral plate, is often delayed until the end of a procedure, just before removal of arthroscopic equipment.
Surgical Technique If performed in isolation, this procedure can be done on an outpatient basis with either regional or general anesthesia. Once adequate anesthesia has been achieved, the patient should be positioned supine on the operative table using the surgeon’s preferred setup and leg holder for standard knee arthroscopy. Tourniquet placement and use throughout the arthroscopic procedure is surgeon dependent. However, if inflated, the tourniquet should be released at the completion of the procedure to fully assess adequate depth of the microfracture holes by the presence of blood and fat droplet egress. We typically place but do not inflate the tourniquet in cases with planned microfracture. Standard arthroscopic portals (medial and lateral parapatellar portals with or without outflow) typically provide adequate access to most articular lesions, although the specific location of the lesion may influence particular placement of these portals. If necessary, accessory portals can be made; however, in our experience these are very rarely indicated. Open arthrotomy is almost never necessary, even for patellar lesions. Following portal placement, a thorough diagnostic knee arthroscopic examination is performed. The chondral lesion is identified and probed to assess the depth, size, and extent of the lesion particularly noting any unstable or loose cartilage
D. Josh Miller, R.H. Brophy
242
Figure 1 Cartilage lesion with intact shoulder. (Color version of figure is available online.)
flaps. The lesion is then debrided back to a stable chondral shoulder, removing all flaps and loose cartilage using arthroscopic shavers and biters (Fig. 1). Careful removal of the calcified cartilage layer is achieved with manual curettage and has been demonstrated to be important in optimizing results.20 However, overly aggressive curettage can destabilize the subchondral architecture or articular morphology, potentially impairing healing. Similarly, incomplete debridement or failure to completely remove cartilage from the subchondral surface may also lead to suboptimal outcomes. Therefore, care should be taken to create an appropriate bony surface for clot adhesion (Fig. 2). After the subchondral surface has been prepared, any concomitant surgical procedures should be completed. Microfracture should be the last part of any knee arthroscopy, following any meniscalor ligamentous procedures. Open extra-articular procedures may be completed after microfracture. Once the lesion is prepared and other intra-articular surgery completed, arthroscopic awls are used to manually create the microfracture holes. These awls are specifically designed to create a hole that is 2-4 mm in diameter and are available in variable angles usually ranging from 301-901 (Fig. 3). For most condylar lesions, a 451 or 601 awl provides adequate access to the lesion. For patellar lesions, a 901 awl is often
Figure 3 Microfracture awls. (Color version of figure is available online.)
necessary. A mallet should be used for impaction of the awls. However, when using higher degree awls or with softer subchondral bone, manual impaction can help prevent sheering and damage to the osseous architecture. The holes should be made perpendicular to the lesion surface, spaced approximately 3-4 mm apart to maintain the integrity of the osseous structure and rim of each hole. Adequate hole depth is typically 3-4 mm, but it should be verified by the presence of bleeding or fat droplets from the created hole. Holes are first made on the periphery along the cartilage shoulder (Figs. 4 and 5) and then advanced centrally in a honeycomb or grid pattern (Fig. 6). Holes can also be drilled rather than impacted. Commercially available microfracture drills provide preset depths of 4 or 6 mm. Drill holes of similar depth can be made using a standard drill bit (o2 mm). Hole configuration and depth assessment should be done in a similar fashion as with impaction microfracture, perpendicular to the subchondral plate in a honeycomb pattern. On completion of either technique, the tourniquet should be released and the arthroscopic pump turned down or off to visualize egress of bleed and fat droplets from all of the microfracture holes (Fig. 7). If this is not seen, the holes without egress should be carefully impacted deeper until blood or fat droplets are seen. Once all holes are verified and of adequate depth, the arthroscopic equipment can be removed. All portals are then closed and dressed according to surgeon preference. No drains should be used, as this can undermine clot formation and retention.
Rehabilitation
Figure 2 Curette is used to remove calcified cartilage. (Color version of figure is available online.)
Although there is some variability between different rehabilitation protocols, compliance with the postoperative rehabilitation program is imperative to optimize patient outcomes. Initial rehabilitation focuses on providing an environment to encourage clot adherence and fibrocartilage formation while also maintaining joint range of motion (ROM). The most
Return to sports after cartilage surgery
243 cutting, pivoting, and jumping should be delayed for 4-6 months.
Return to Sports Return to sport after articular cartilage surgery has a limited but growing body of evidence, with the most extensive literature on return to sport after microfracture. There are slightly fewer data available on return to sport after cellular techniques, followed by autograft and allograft. Recovery from articular cartilage surgery is particularly important and challenging in athletes as they want to get back to as much as possible as soon as possible. Return to sport has been studied most extensively in athletes undergoing microfracture. In a systematic review of chondral defects in athletes, 8 of 11 studies reported return to play after
Figure 4 Initiate microfracture around the periphery of the lesion. (Color version of figure is available online.)
common rehabilitation protocols use a combination of continuous passive motion (CPM) and protected weight bearing based on the location of the lesion.19 Microfracture performed on the tibiofemoral joint (femoral condyles and tibial plateau) requires a period of 4-6 weeks of non–weight bearing. A CPM machine is utilized immediately postoperatively, starting at 01-301, advancing up to 01-1201 as tolerated, for 6-8 hours a day. Patellofemoral lesions on the trochlea or patella protect the clot with a leg brace locked in extension while weight bearing for 4-6 weeks. CPM for these lesions is typically limited to 01-301 for 6-8 hours a day to minimize shear on the clot. After 4-6 weeks, weight bearing and ROM are advanced, with full weight bearing and ROM achieved at 6-8 weeks. Leg strengthening and resistance training then becomes the focus of rehabilitation and can include stationary bike, band training, and closed chain exercises. However, activities involving
Figure 5 Continue along periphery of lesion with microfracture. (Color version of figure is available online.)
D. Josh Miller, R.H. Brophy
244 microfracture with an overall average of 59% (range: 25%100%).21 In another review pooling data from studies of athletes undergoing knee articular cartilage surgery, the rate of return to play was 66% ⫾ 6% (range: 44%-100%) in 787 athletes treated with microfracture.22 In a couple of studies with athletes from a variety of sports undergoing microfracture, the rate of return to play ranged from 44%-77%, with 57%71% getting back to the same or higher level of competition.23 Professional basketball players have been shown to have a 67%-79% return to play by 25-30 weeks after undergoing a microfracture.24,25 Athletes were 8.2 times less likely to return the next season than controls were.25 Those who returned to professional basketball played at a significantly lower level than they were before injury and only 58% were able to play at least one more season.24 Professional American football players have a 76% rate of return to play after undergoing a microfracture, getting to an additional 4.6 seasons and 56 games on average.6 There are also reasonable data on return to sport after autologous cellular implantation (ACI) in athletes, with a 67%78% rate of return to sport.21,22 A significant proportion of return to sport data after ACI come from soccer players and the return to sport tends to occur later after ACI compared with microfracture. There are less data on return to sport after osteochondral autograft transfer (OAT), but the available studies are encouraging, with a rate of return to sport of 91%-93%.21,22 A study has reported an 88% rate of return to activity in athletes with chondral injury of the knee treated with osteochondral allografts.26
Figure 7 Let down the pump pressure and tourniquet (if necessary) to confirm blood flow through microfracture.
A couple of comparative studies have looked at return to sport after articular cartilage surgery. In a comparison of microfracture to OAT in a cohort of predominantly soccer and basketball players, there was a higher return to preinjury level of competition after undergoing OAT (93%) compared with after undergoing microfracture (52%).27 This study reported a decrease in outcomes associated with lesions larger than 2 cm for microfracture not seen for OAT. Another comparison of microfracture to second-generation ACI in soccer players reported similar return to sport rates (80% vs 86%, respectively) with a quicker return after microfracture (median ¼ 8 months) than ACI (median ¼ 12.5 months).28 The limited body of evidence available to date suggests that athletes can get back to sport after surgery to restore articular cartilage in the knee. Although microfracture may facilitate a relatively quick return to sport, it may not be ideal for larger lesions, and its durability is unclear. Tissue transplantation and implantation may have some advantages in return to sport and durability but face limitations in availability and cost. Athletes should be counseled about their various treatment options and the potential tradeoffs and more investigation is needed to better define the optimal indications, techniques, rehabilitation, and outcomes in these high-demand patients.
Summary Microfracture is a readily available single-stage, arthroscopic technique. Technically easy and relatively low cost, it is ideal for smaller lesions with a stable shoulder of surrounding cartilage and can be used for incidental lesions discovered at the time of surgery. Microfracture results in tissue fill with fibrocartilage, which can be unpredictable. Even with complete filling of the lesion, the durability of the tissue is uncertain, with an estimated lifespan of 2-5 years in high-demand individuals.29 Overall, microfracture is a safe, cost-effective first-line treatment with relatively low morbidity.
References Figure 6 Move into the central portion of the lesion after microfracture of the periphery has been completed.
1. Shapiro F, Koide S, Glimcher MJ: Cell origin and differentiation in the repair of full-thickness defects of articular cartilage. J Bone Joint Surg Am 75:532-553, 1993
Return to sports after cartilage surgery 2. O’Driscoll SW: The healing and regeneration of articular cartilage. J Bone Joint Surg Am 80:1795-1812, 1998 3. Mithoefer K, Williams 3rd RJ, Warren RF, et al: The microfracture technique for the treatment of articular cartilage lesions in the knee. A prospective cohort study. J Bone Joint Surg Am 87:1911-1920, 2005 4. Steadman JR, Rodkey WG, Singleton SD, et al: Microfracture technique for full-thickness chondral defects. Technique and clinical results. Oper Tech Orthop 7:300-304, 1997 5. Steadman JR, Briggs KK, Rodrigo JJ, et al: Outcomes of microfracture for traumatic chondral defects of the knee: Average 11-year follow-up. Arthroscopy 19:477-484, 2003 6. Steadman JR, Rodkey WG, Rodrigo JJ: Microfracture: Surgical technique and rehabilitation to treat chondral defects. Clin Orthop Relat Res 391 (suppl):S362-S369, 2001 7. Frisbee DD, Oxford JT, Southwood L, et al: Early events in cartilage repair after subchondral bone microfracture. Clin Orthop Relat Res 407:215-227, 2003 8. Gobbi A, Karnatzikos G, Kumar A: Long-term results after microfracture treatment for full-thickness knee chondral lesions in athletes. Knee Surg Sports Traumatol Arthrosc 2013 Sep 20. [Epub ahead of print] 9. Solheim E, Øyen J, Hegna J, et al: Microfracture treatment of single or multiple articular cartilage defects of the knee: A 5-year median follow-up of 110 patients. Knee Surg Sports Traumatol Arthrosc 4:504-508, 2010 10. Goyal D, Keyhani S, Lee EH, et al: Evidence-based status of microfracture technique: A systematic review of level I and II studies. Arthroscopy 29:1579-1588, 2013 11. Tuan RS, Chen AF, Klatt BA: Cartilage regeneration. J Am Acad Orthop Surg 21:303-311, 2013 12. Steinwachs MR, Guggi T, Kreuz PC: Marrow stimulation techniques. Injury 1(suppl):S26-S31, 2008 13. Chen H, Sun J, Hoemann CD, et al: Drilling and microfracture lead to different bone structure and necrosis during bone-marrow stimulation for cartilage repair. J Orthop Res 27:1432-1438, 2009 14. Kok AC, Tuijthof GJ, den Dunnen S, et al: No effect of hole geometry in microfracture for talar osteochondral defects. Clin Orthop Relat Res 471:3653-3662, 2013 15. El Bitar YF, Lindner D, Jackson TJ, et al: Joint-preserving surgical options for management of chondral injuries of the hip. J Am Acad Orthop Surg 22:46-56, 2014 16. Hannon CP, Murawski CD, Fansa AM, et al: Microfracture for osteochondral lesions of the talus: A systematic review of reporting of outcome data. Am J Sports Med 41:689-695, 2013
245 17. Gross CE, Chalmers PN, Chahal J, et al: Operative treatment of chondral defects in the glenohumeral joint. Arthroscopy 28:1889-1901, 2012 18. Salzmann GM, Sah B, Sudkamp NP, et al: Clinical outcome following the first-line single lesion microfracture at the knee joint. Arch Orthop Trauma Surg 133:303-310, 2013 19. Mithoefer K, McAdams T, Williams RJ, et al: Clinical efficacy of the microfracture technique for articular cartilage repair in the knee: An evidence-based systematic analysis. Am J Sports Med 37:2053-2063, 2009 20. Frisbie DD, Trotter GW, Powers BE, et al: Arthroscopic subchondral bone plate microfracture technique augments healing of large chondral defects in the radial carpal bone and medial femoral condyle of horses. Vet Surg 28:242-255, 1999 21. Harris JD, Brophy RH, Siston RA, et al: Treatment of chondral defects in the athlete’s knee. Arthroscopy 26:841-852, 2010 22. Mithoefer K, Hambly K, Della Villa S, et al: Return to sports participation after articular cartilage repair in the knee: Scientific evidence. Am J Sports Med 37(suppl 1):167S-176S, 2009 23. Blevins FT, Steadman JR, Rodrigo JJ, et al: Treatment of articular cartilage defects in athletes: An analysis of functional outcome and lesion appearance. Orthopedics 21:761-767, 1998. [discussion 7-8] 24. Cerynik DL, Lewullis GE, Joves BC, et al: Outcomes of microfracture in professional basketball players. Knee Surg Sports Traumatol Arthrosc 17:1135-1139, 2009. ([Epub 2009 Mar 20]) 25. Namdari S, Baldwin K, Anakwenze O, et al: Results and performance after microfracture in National Basketball Association athletes. Am J Sports Med 37:943-948, 2009 26. Krych AJ, Robertson CM, Williams 3rd RJ: Return to athletic activity after osteochondral allograft transplantation in the knee. Am J Sports Med 40:1053-1059, 2012 27. Gudas R, Stankevicius E, Monastyreckiene E, et al: Osteochondral autologous transplantation versus microfracture for the treatment of articular cartilage defects in the knee joint in athletes. Knee Surg Sports Traumatol Arthrosc 14:834-842, 2006 28. Kon E, Filardo G, Berruto M, et al: Articular cartilage treatment in highlevel male soccer players: A prospective comparative study of arthroscopic second-generation autologous chondrocyte implantation versus microfracture. Am J Sports Med 39:2549-2557, 2011 29. Mithoefer K, Williams 3rd RJ, Warren RF, et al: High-impact athletics after knee articular cartilage repair: A prospective evaluation of the microfracture technique. Am J Sports Med 34:1413-1418, 2006