Arthroscopic cartilage regeneration facilitating procedure for osteoarthritic knee

Osteoarthritis (OA) of the knee affects a large population worldwide and is associated with an extremely high economic burden largely attributable to the effects of disability, comorbid disease, and the expense of treatment [1]. To date the established therapies have been directed towards symptom control. Since the initiating events that result in the cartilage degradation are poorly understood, there has been very limited success in demonstrating disease modification in clinical trials of potential therapies [2].

Arthroscopy for the management of OA knees, as a relative minor procedure, is popular in spite of the controversy concerning its effectiveness. Joint lavage [3, 4], debridement [5‐7], abrasion arthroplasty [7‐11], and microfracture [12‐14] are among the most commonly employed arthroscopic procedures for OA knees. The precise mechanism and consensus by which these procedures improve the course of degenerative conditions of the knee have not been established. A recent retrospective review of the current literature on the arthroscopic treatment of OA knee [15] has demonstrated limited evidence-based research to support the use of arthroscopy as a treatment method for OA knee.

In 2008, a concept of arthroscopic medial release (AMR) for the treatment of osteoarthritis of the medial compartment of the knee joint was reported [16]. The clinical outcome of this series lured us to believe that, by eradication of the abrasion phenomenon between the tight, fibrotic and hypertrophied medial structure and the adjacent medial femoral condyle, the pain of most patients could be reduced and the degenerative process in the medial compartment of these patients might be decelerated or arrested. In this report, we propose a concept of arthroscopic cartilage regeneration facilitating procedure (ACRFP) that combines arthroscopic medial release (AMR), percutaneous lateral release (PLR) and conventional debridement as a rationale for the deliberate arthroscopic management of OA knee. We hypothesized that the elimination of the detrimental factors including synovitis, chondral flaps, and abnormal focal stress caused by medial abrasion and lateral compression phenomena will provide a preferable environment for the regeneration of damaged cartilage. The details of this procedure and its clinical results are reported in this study.

There were 505 knees in 326 patients available with more than 3 years follow-up and the mean follow-up period was 38 months (SD 3). Ten of 59 knees (16.9%) with grade I osteoarthritic knees in six patients; twenty-five of 235 knees (10.6%) with grade II osteoarthritis in fifteen patients, twenty-six of 233 knees (11.2%) with grade III osteoarthritis in seventeen patients, and five of 44 knees (11.4%) with grade IV osteoarthritis in three patients were lost to follow-up. The total follow-up rate was 88.5%. One hundred and thirty-four knees returned and completed thorough outcome study including x-ray examination, KSS and KOOS evaluation. Another 371 knees completed the subjective outcome evaluation by telephone questionnaires. All of the knees were found to have the structure of pathologic medial plica. The mean age of these patients at the time of surgery was 60 (SD 10). The mean age and distribution of different grade of OA stratified by the procedure they received were shown in Table 1. There were 406 knees (80.4%) of 269 patients received AMR and 99 knees (19.6%) of 57 patients received AMR+PLR. The mean age of the patients were positively correlated with the severity of OA by ANOVA in both surgical groups. In the group received AMR+PLR, the F/M ratios were more prominent compared to that of the AMR group.

In this report we present the clinical and radiographic outcomes of our procedure of arthroscopic cartilage regeneration facilitating procedure (ACRFP) for OA knees involving mainly medial and patellofemoral compartments. Overall, the subjective satisfactory rate was 85.5%. Even in grade IV OA, 59% of satisfactory rate could be anticipated after at least 3 years’ follow-up. Besides the improvement of clinical symptoms and life quality according to the KSS and KOOS surveys, revitalizing of the degenerated cartilage and reversal of the degeneration process were perceived in 81.2% of the knees by radiographic evaluation.

Therapeutic arthroscopic techniques including lavage, debridement, abrasional chondroplasty and microfracture are widely used for OA knee despite their unpredictable outcomes. A double-blinded, randomized, placebo-controlled trial to compare the effectiveness of arthroscopic lavage and arthroscopic debridement versus a sham procedure has been performed and the data suggest that the benefits of arthroscopy for the treatment of osteoarthritis of the knee are to provide subjective pain relief via a placebo effect [24]. The American Academy of Orthopaedic Surgeons (AAOS) clinical practice guideline on the treatment of OA knee also recommends against performing arthroscopy with debridement or lavage in patients with a primary diagnosis of symptomatic OA of the knee [25]. Dandy’s abrasion chondroplasty [26] was popularized in the late 1980s. In 1993, Bert et al. found it appears to offer little benefit over partial meniscectomy and debridement in the degenerative knee [8]. It was also thought that this technique provide unpredictable results. Concerns include the durability of the fibrocartilage repair tissue and thermal damage to subchondral bone and adjacent normal articular cartilage during this procedure [27]. Microfracture, a modification of chondroplasty, might provide increase in joint space by growth of fibrocartilage and achieve functional improvement for patients with full-thickness chondral defects in the osteoarthritic knees [28]. But an evidence-based systematic analysis declared that this technique could only provide short-term functional improvement. Shortcomings of this technique include limited hyaline repair tissue, variable repair cartilage volume and possible functional deterioration [12]. Autologous chondrocyte implantation (ACI) has become an accepted option for the treatment of chondral defects in carefully selected patients. Current recommendations limit this procedure to younger patients, as insufficient data are available to conclusively evaluate outcomes in patients older than 45 years, especially in OA patients [29]. The unconfirmed pathogenesis of OA knee and a lack of a clear consensus on the indications and surgical techniques as well as the variable outcomes make these commonly used arthroscopic techniques remain a source of controversy.

Abrasion or impingement phenomenon between the medial plica and the opposite medial femoral condyle has been described in recent studies in patients with medial compartment OA knee [30‐33]. The consequent study [34] found that the repeated injuries elicited by this abrasion phenomenon might trigger IL-1ß production, thus enhance the expression of MMP-3. Their demonstration of the expression of IL1-ß mRNA, MMP-3 mRNA and MMP-3 in medial plica of early stage OA knee suggests that this structure and its interplay with the facing medial femoral condyle might play an important role in the pathogenesis of medial compartment OA knee. These findings coincide with the fact that eradication of this structure by arthroscopic release could be effective in symptom relief or even might modify the disease process of medial compartment OA knees [16, 35].

Based on these constitutional studies, we proposed a concept that by a purposeful eradication of all prejudicial factors in the degenerative knee, the jeopardized cartilage would have the chance to regenerate by its innate healing response. In comparison with the uncertain beneficial mechanism and the diversity of outcomes of current popular arthroscopic techniques for osteoarthritis of the knee, our concept of ACRFP had more precise rationale of treatment. The main theme of ACRFP was to remove any abnormal abrasion or impingement phenomenon and reestablish soft tissue balance around the patellofemoral joint. For knees demonstrating medial abrasion phenomenon, medial release [16] was performed to relief the tension and abrasion between the tight, fibrotic and hypertrophied medial plica and the adjacent medial femoral condyle. On the other hand, in knees demonstrating lateral compression syndrome over patellofemoral joint, percutaneous lateral capsular release that has the benefits of tension release and denervation [36‐40] was added. The immediate effect of ACRFP was obtained by releasing the tension around patella caused by chronically inflamed soft tissue and by eradication of the hypertrophied and inflamed synovium that may cause pain in these degenerative knees over the medial compartment and patellofemoral joint. Furthermore, by eliminating these stress/inflammatory responses that are the key events on the onset and progression of osteoarthritis, this procedure would also bring forth to long-term favorable effects as a consequence of the global improvement of the environment of the knee joint for cartilaginous regeneration.

Although articular hyaline cartilage was classically considered having no or low potential for regeneration [41‐46], some still thought that it does have the capacity to grow and remodel extensively during pre- and post-natal development and after trauma [47, 48]. Both direct and indirect evidence of articular cartilage regeneration have been reported after correction of varus deformity for osteoarthritis of the knee by some authors. According to their investigations about the beneficial effects of valgus osteotomy for medial gonarthrosis, the main repair feature was proliferation of fibrocartilage, which covered bone and areas of fibrillated cartilage and filled vertical clefts in hyaline cartilage. The hyaline cartilage was found to show an increased cellularity with numerous nests of proliferating chondrocytes [49]. There was also arthroscopic visible improvement of the articular surface after this procedure [50]. Moreover, it was observed by direct vision that mature regeneration was more frequently found in the knees with radiographic increased width of the medial joint space after high tibial valgus osteotomy, and this even happened in the knees with eburnation of the subchondral bone [51].

Recent studies also point out that, unlike the first impression of a more or less static tissue, articular cartilage shows a slow turnover. Anabolic and catabolic pathways were thought to be very much intermingled in articular cartilage metabolism [52]. Under normal conditions, chondrocytes maintain the dynamic equilibrium between synthesis and degradation of extracellular matrix components. In osteoarthritic states, however, there is a disruption of matrix equilibrium leading to progressive loss of cartilage tissue [53]. Thus, the aim of osteoarthritis therapy might neither to stimulate anabolism nor to knock down catabolism, but to titrate the balance of anabolic-catabolic activities. In this study, the clinical outcomes and the radiographic findings have given light to us that, by removal of all existed catabolic factors, the anabolism of the damaged cartilage might become dominant and regeneration unveiled.

Although it was claimed that compared with the extended weight-bearing anterior-posterior (AP) radiograph, posteroanterior (PA) imaging of the knee in 20–30 degrees flexion (the schuss position) increases the reproducibility of radiographic JSW measurements in OA knees [21], standing AP radiographic views of the knee have still been widely used to determine the rate of disease progression in OA knee by measuring joint space narrowing and bony alignment [21, 54‐59]. Contrary to our observation, they all obtained the common finding of progressive narrowing of the joint space as the natural course of OA knee. Never the less, in order to get more convincing evidence, we need more precise methodology such as magnetic resonance images study for the evaluation of cartilage regeneration. Properly conducted randomized control clinical trials are also warranted.

According to the experience of performing this procedure, the data support our contention that arthroscopic cartilage regeneration facilitating procedure (ACRFP) is a good modality for the treatment of osteoarthritis of the knee joint if only medial and/or patellofemoral joint were involved. It could modify the natural course of this common disease. This novel concept of treatment might give hope to the majority of patients who are in the ambiguous stages of OA knee before arthroplasty could be beneficial for them.