Knee arthroscopic techniques provide a superior avenue for preservation of the meniscus when there is an acute vertical circumferential tear in the “red zone.” Degenerative tears are usually horizontal and may result in impinging flaps; they typically occur in older individuals and can bring about mechanical symptoms. The American Academy of Orthopaedic Surgeons was “unable to recommend for or against arthroscopic partial meniscectomy in patients with osteoarthritis of the knee with a torn meniscus.”1
Similar to the situation involving the knee meniscus, there are two types of labral tears in the hip, traumatic and degenerative. The traumatic tears tend to occur in a younger, highly active population including professional athletes and military personnel. Many labral tears are associated with an acetabular cam or pincer deformity. Repairs are performed by shaving the reattachment site to bleeding bone2. Short-term improvement has been well documented, but the long-term preventative effect of labral repair is unknown3. Unlike knee meniscal tears, the distinction between acute labral tears and degeneration is not as reliable4. The outcome of labral debridement in older individuals is in question.
The study by Wilkin et al. was a prospective evaluation of forty-one patients who were at least forty-five years old and had no radiographic evidence of hip deformity (as indicated by the center-edge and alpha angles). The mean age of the patients at the time of surgery was 52.7 years (range, 45.5 to 67.0 years). All had mechanical complaints or impingement findings and evidence of labral tears on magnetic resonance imaging. None had degenerative changes greater than Tönnis grade 2 on radiographs. Unstable labral tears were debrided to a stable rim, and unstable articular cartilage flaps were debrided to a stable base. The mean follow-up duration was 2.9 years. Eighty percent had chondral damage. Only thirteen patients (32%) had a good or excellent clinical outcome as indicated by achieving a postoperative modified Harris hip score of >80. The authors concluded that it remains difficult to predict which individuals forty-five years of age or older will derive a clinically important benefit from arthroscopic debridement of acetabular labral tears and that this procedure should be utilized with caution.
This article is very relevant to the controversy surrounding hip arthroscopy for labral tear resection, particularly in older individuals. Because the authors used rather narrow criteria for performance of surgery, they excluded a number of individuals with more advanced osteoarthritis or apparent hip deformity as indicated by the two radiographic measures. However, the addition of femoral head coverage and Tönnis angle to the radiographic measures might have detected an underlying deformity. In a recent contrasting report, the degree of radiographic osteoarthritic changes was found to be more important than age in a group of patients with a comparable age range. Fewer than 30% of the patients in that report had femoral acetabular impingement (FAI)5. It is not clear what role other hip deformities or a more severe radiographic osteoarthritis grade may have played in the difference between the results of these two studies.
The influence of age on the treatment outcome should not be a surprise. Normally, adult articular cartilage has a relatively low rate of turnover of collagen and aggrecan with no substantial release of inflammatory signals. With the development of osteoarthritis, collagen cleavage and degradation occurs, and this is associated with other metabolic changes and the stimulation of inflammatory cytokines. In a recent study, articular cartilage was harvested from hips undergoing dysplastic acetabuloplasty (the control group), hips undergoing open femoral head-neck arthroplasty for FAI (early osteoarthritis group), and hips with end-stage osteoarthritis6. The articular cartilage from the impingement zone of the hips with FAI was metabolically hyperactive, supporting the concept that such impingement is a structural precursor to hip osteoarthritis. Of note, an early anabolic response was also observed, with increased expression of the genes for type-II collagen (COL2A1) and aggrecan (ACAN). Furthermore, that work showed that the hips with FAI had higher levels of the inflammatory chemokines IL-8 and CCL3L1 as well as of matrix-degrading ADAMTS-4. The COL2A1 and ACAN overexpression disappeared in the patients who had osteoarthritis, which involves more advanced articular cartilage changes. This may indicate a progressive loss of anabolic activity and an imbalance favoring catabolism.
Wilkin et al. have presented evidence to support the effect of age on the outcome of labral debridement even in patients with mechanical symptoms. Further studies need to be done before recommendations regarding the role of age and osteoarthritic changes in the selection of patients for resection of unstable labral tears can be made.