Scope and Cartilage: Débridement and Microfracture

Andrew S. Greenberg

Nicholas A. Sgaglione

Adam S. Levin

INTRODUCTION

Achieving a predictable and durable repair after an articular cartilage injury has remained a clinical challenge. Over the past decade, advancements in arthroscopy and magnetic resonance imaging (MRI) have led to an increase in the acute recognition of articular cartilage injuries. Several investigators have reported on the incidence of such lesions. Curl et al. (12) retrospectively reviewed 31,516 knee arthroscopies and reported lesions in 63% of patients. Similarly, Aroen et al. (2) published a survey of 993 consecutive knee arthroscopies, which revealed articular cartilage pathology in 66%, with a localized full-thickness lesion in 11%. Hjelle et al. (20) reported chondral or osteochondral lesions in 61% of 1,000 knee arthroscopies, 5% of which were full thickness.

Articular cartilage defects can result in pain, swelling, clicking, instability, and ultimately, progression to a more diffuse, degenerative process (10,37). Current surgical options include arthroscopic débridement and lavage using mechanical shavers or radiofrequency (RF) devices, arthroscopic marrow stimulation and microfracture techniques, osteochondral autograft transplantation (OAT) or allograft transplantation, and cell-based therapies, such as autologous chondrocyte implantation (ACI). More recently, second-generation methods to augment and improve upon the ACI procedure using three-dimensional scaffolds have been described.

The response of articular cartilage to injury, and thus healing, depends upon the type, location, and mechanism of the injury. Due to the avascular nature of cartilage, superficial injuries fail to stimulate a predictable healing response (10,35). However, full-thickness injuries that penetrate subchondral bone have vascular access and, consequently, have a greater capacity for healing. The repair tissue has the structure, histology, and biomechanical properties of a fibrocartilagenous mosaic. Despite the altered biomechanics and potentially inferior long-term durability, most patients report symptomatic and functional improvement (15,30,35,52).

Current articular cartilage biological resurfacing procedures can be characterized as either primary or secondary. Primary procedures can be carried out as a first-line treatment, usually arthroscopically, and include débridement, fixation techniques, marrow stimulation techniques, and OAT procedures. Secondary procedures are those that attempt to restore or replace hyaline cartilage in larger lesions or in those cases that fail primary treatment and must therefore be revised. These procedures include osteochondral allograft transplantation and ACI. This chapter focuses on the surgical techniques of two primary treatment methods: débridement and microfracture.

PREOPERATIVE PLANNING

A thorough history should be taken with any patient presenting with a possible articular cartilage injury and clinically correlative symptoms. Treatment indications optimally include those patients with defined symptoms and whose potential confounding pathology can be precisely characterized. Historically, clinical results for both débridement and microfracture vary depending on the type of chondral injury (degenerative vs. acute), as well as the age, body mass index (BMI), surgical history, and activity level of the patient. Thus, the timing, symptoms, mechanism of injury, occupation, and activity level of the patient should be appreciated. In an effort to distinguish traumatic or focal lesions from degenerative lesions associated with osteoarthritis, the type, timing, and location of symptoms as they relate to the injury must be defined, with distinction between focal mechanical symptoms from those that are more diffuse and general. Traumatic chondral and osteochondral lesions commonly present acutely with a hemarthrosis, pain, and often, mechanical symptoms suggestive of a loose body, while a subset of patients will describe a more chronic clinical scenario. The chronic patients will commonly present with progressive pain that is exacerbated with use and frequently demonstrate an effusion. A complete exam should follow, specific for the affected joint, and assessed relative to the unaffected limb. General appearance and focal tenderness to palpation should be noted, as well as an evaluation of ligamentous laxity. Range of motion should be measured in addition to the presence of crepitus. Furthermore, the mechanical and anatomical axis, as well as gait analysis should be assessed and measured.

Plain radiography should always be obtained including weight-bearing radiographs of the affected limb, as well as a standing hip to ankle radiographs. Additional views, such as a patellar skyline, notch or tunnel views, and 45-degree flexion weight-bearing posteroanterior views are helpful. MRI offers the ability to evaluate for coexistent meniscal or ligamentous injuries. Modern advancements in MRI technique have aided in both the early diagnosis and the subsequent treatment of osteochondral defects. With the use of cartilage-specific MRI and, more specifically, modified fast spin-echo sequence techniques, Potter et al. have demonstrated great precision in MRI detection of cartilage lesion size and depth. Newer, more specific cartilage-sensitive pulse sequences, in addition to fat suppression techniques, can better evaluate subchondral bone, thus distinguishing an osteochondral defect from an isolated shear injury, as well as better defining an acute, isolated osteochondral defect, from a more degenerative lesion. Furthermore, the use of three-dimensional pulse sequences and the addition of isotropic voxels allow a more precise measurement of lesion size, cartilage volume, and postoperative tissue fill (46,47).

Traditional grading systems for articular cartilage lesions are commonly based upon the surgeon’s intraoperative visual assessment of the lesion. Classification systems include those described by Outerbridge (44), Insall (22), Bauer and Jackson (5), and Noyes Stabler (43). A more specific grading system was formulated in 2000 by the International Cartilage Repair Society (ICRS) in order to facilitate accurate mapping and description of cartilage lesions and osteochondral defects (8) (Table 40.1).

In those patients who remain symptomatic after a trial of nonoperative treatment, surgical intervention may be considered. The criteria used to indicate a patient for any chondral resurfacing procedure are multifactorial. Patient compliance is an important factor, as the success of many of these procedures is dependent upon the adherence to a strict physical therapy protocol. Patients who are unable to reliably follow postoperative weight
bearing and physical therapy orders are not candidates for chondral surgery. The age and preinjury activity level of the patient must also be considered, and patient expectations and goals should be addressed and discussed. Patients should be counseled as to the potential benefit and risks of the proposed procedure, as well as to the fact that, although often successful in providing pain relief and resumption of activities, no procedure can reliably reproduce the preinjury articular surface and uniform clinical success.

TABLE 40.1 Modified Outerbridge Classification versus ICRS^a Classification System

	Modified Outerbridge (22)	ICRS^a (8)
Grade 0	Normal	Normal
Grade I	Softening and swelling	Nearly normal: Soft indentation and/or superficial fissures and cracks
Grade II	Partial-thickness defect: Fissuring within softened areas	Abnormal: Lesion extending to < 50% of cartilage depth
Grade III	Full-thickness defect: Breakdown of the surface: Fibrillation	Severely abnormal: Lesion extending to
			A. > 50% of cartilage depth
			B. calcified layer
			C. to subchondral bone
			D. Includes blisters
Grade IV	Complete loss of cartilage Erosive changes and exposure of subchondral bone	Severely abnormal: Lesion extending through subchondral bone
^aInternational Cartilage Repair Society
Source: Brittberg M. ICRS clinical cartilage injury evaluation system-2000. Third ICRS Meeting, 2000; April 28, 2000; Insall J. Patellar pain. J Bone Joint Surg. 1982;64A(1):147-152.

DÉBRIDEMENT

Indications/Contraindications

Surgical débridement for articular cartilage lesions dates back to the early 1940s. The technique of cartilage débridement was initially utilized to address the pain and mechanical symptoms secondary to osteoarthritis (34). With the advent of arthroscopy and evolution of minimally invasive surgery, arthroscopic débridement became popular as a technically easy and efficient method to treat articular cartilage lesions and arthritic knees. Using high-speed arthroscopic rotary shavers, handheld basket punches, arthroscopic curettes, and RF ablative devices, the procedure consists primarily of the removal of incongruent, unstable cartilaginous flaps, the shaving of fibrillated tissue, the removal of all loose bodies, and the resection of any unstable meniscal tears.

The use of RF devices has been described as an alternative to the mechanical shaving of chondral lesions. Studies have shown that mechanical débridement may result in perimeter irregularities and incomplete resection, which often lead to the damage or removal of healthy articular cartilage, while arthroscopic RF ablation produces smooth edges. However, clinical and basic science studies determining superiority of one débridement method versus the other have been inconclusive. Turner et al. conducted an in vivo study comparing the effects of a bipolar RF probe and a mechanical shaver on roughened articular cartilage in ovine knees. Those in the bipolar-treated group graded better with respect to histologic appearance and showed no evidence of subchondral necrosis (59). Similarly, in an explant study of human arthritic cartilage, the authors reported that RF devices create a smooth articular surface with no histologic alterations (27). Amiel et al. (3) further assessed the viability of chondrocytes ex vivo after treatment with RF and concluded that there was a relatively insignificant margin of chondrocyte death (100 to 200 μm), which did not approach the subchondral bone in any sample. However, in contrast, other studies have shown large margins of chondrocyte death. Lu et al. (33) reported up to 1mm of cell death in bovine cartilage treated with RF, using confocal laser microscopy, suggesting that previous histologic evaluations underestimated the depth of cell death. Similarly, an experiment on explanted human cartilage resulted in chondrocyte death extending to subchondral bone (13).

Several clinical studies have compared mechanical shaving to RF débridement. Owens et al. showed superior results with RF treatment of grades 2 and 3 chondral lesions compared with mechanical shaving (45). More recently, Barber et al. reported no subchondral bone damage or avascular necrosis, and significant clinical improvement in both groups when comparing the effects of monopolar RF and mechanical chondroplasty techniques on grade 3 femoral condyle lesions (4). While RF devices may have a role as an alternative method for chondroplasty, their superiority over mechanical shaving has yet to result in widespread acceptance, and clinical outcome comparisons have, thus far, been limited.

For appropriately indicated patients, arthroscopic débridement has been shown to produce early satisfactory outcomes in 50% to 90% of patients (1,21,24). Hubbard studied débridement versus lavage in 76 patients with a focal, degenerative grade 3 or 4 femoral condyle lesion, with no concomitant intra-articular pathology, joint deformity, or abnormal radiographs. He reported pain relief in 80% and 65% of patients in the débridement group at 1 and 5 years, respectively, compared with 20% and 11% for those patients who only received an arthroscopic lavage (21). Other satisfactory results have been seen in patients with symptoms <1 year, a specific history of trauma, and a low BMI (25).

In an effort to further establish and refine the indications for arthroscopic débridement and lavage for osteoarthritis, Aaron et al. noted that 90% of knees with mild arthritis experienced symptomatic relief, while only 25% with severe arthritis improved (1). Jackson and Dieterich (24) found, in a 4 to 6 year retrospective case series of 121 patients treated with arthroscopic débridement, more successful results in patients with earlier stages of arthritis. In a retrospective review of 204 knees with osteoarthritis, Harwin (19) reported on predictors of patient satisfaction following arthroscopic débridement and noted that those knees with minimal malalignment, no prior surgeries, and a low BMI had better results.

Despite the conclusions of these earlier nonrandomized, noncontrolled case series, recent investigators have found no benefit to arthroscopic joint débridement for arthritis without specific mechanical symptoms. In 2002, Moseley et al. performed a level 1 randomized controlled trial of 180 patients with osteoarthritis who failed medical management, comparing arthroscopic débridement, lavage alone, and placebo “sham” surgery. The results were similar in all three groups, with no surgical benefit proven (42). More recently, Kirkley et al. conducted a level 1 randomized controlled study of 188 patients treated with either arthroscopic débridement and lavage or physical therapy and medical management. Again, no significant improvement was realized in the surgical group (28).

In order to better define the indications for arthroscopic débridement of the symptomatic osteoarthritic knee, the American Academy of Orthopaedic Surgery convened a multidisciplinary expert panel to review the
body of literature and, as of December of 2008, established a set of guidelines for arthroscopic débridement for osteoarthritis. The guidelines recommend against performing an arthroscopic lavage, or débridement and lavage, for patients with a primary diagnosis of osteoarthritis but do state that arthroscopic débridement is indicated for those patients with a symptomatic torn meniscus and/or mechanical symptoms of a loose body and associated, underlying osteoarthritis (58). Furthermore, it should be noted that many focal lesions associated with traumatic etiologies or osteochondritis dissecans (OCD) may have associated perimeter nonviable pathologic chondral tissue that may require adjuvant débridement in association with a resurfacing procedure.

Arthroscopic débridement remains a potentially clinically useful, technically simple palliative treatment for focal, small chondral lesions, with minimal morbidity and few complications. The benefits, however, must be based upon the removal of mechanically unstable tissue, as well as the possible prevention of lesion propagation by débridement of flaps and blisters. The indications for the procedure include those symptomatic patients with well-aligned knees presenting with focal articular cartilage lesions (<1 cm) and lesions with associated flaps or loose bodies, including those associated with OCD or fractures, as well as unstable meniscal tears. Contraindications include diffusely arthritic knees, BMI > 25 to 30, underlying instability, rheumatologic and systemic disorders, sepsis, and joint malalignment.

Surgical Technique

Débridement and Lavage

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