chapter 13: Surgical Treatment of Patellofemoral Chondrosis and Arthrosis
In general, most patients with anterior knee pain will not need arthroscopy. Precise radiographs (Fig. 13.1), including a true lateral computerized tomography (CT) and radionuclide scanning, permit the physician to gain considerable understanding of the patellofemoral joint without introducing instruments. The arthroscope, nonetheless, is a powerful tool and may be helpful in both adults and children (1) before performing definitive procedures such as lateral retinacular release, anteromedial tibial tubercle transfer, patellar debridement, or tibial tubercle anteriorization. I use the superomedial approach described by Schreiber (2) and an inferolateral approach to view the patellofemoral joint. It helps to view the patella from both above and below.
There are patients who have normal patellar alignment (sometimes as a result of earlier corrective surgery), yet there is patellar articular fibrillation (Fig. 13.2) causing mechanically and enzyme induced (3) aggravation of the entire knee joint. In such cases, arthroscopic debridement of the fibrillated articular surface may provide symptomatic relief and joint preservation. On occasion, there may be a finite area of exposed bone, and abrasion arthroplasty may give relief, particularly when combined with a specific procedure to unload the affected area.
Abnormal patellar alignment will usually be apparent at the time of arthroscopy, but there is some risk of creating distortion of patellar alignment at the time of arthroscopy. Anesthesia, paralysis, tourniquet pressure, intra‑articular fluid, and distension may create an impression of malalignment in some patients who have functionally normal alignment. Therefore, patellofemoral arthroscopy should confirm preoperative clinical radiographic findings and quantitate articular damage, but one need not rely on arthroscopy alone to evaluate patellofemoral alignment.
The arthroscope is helpful in identifying a pathological plica semilunaris or synovial shelf (4‑6), and arthroscopic resection of a painful snapping shelf may be very helpful in the appropriate patient. Munzinger et al (7) and Broom (8) have noted residual problems in some patients after plica resection, although Richmond and McGinty (9) reported 86% good and excellent results after resection of a hypertrophic mediopatellar plica in 64 knees. Residual problems after plica resection may result from articular lesions or associated patellar imbalance. The true symptomatic plica is fairly uncommon, and diagnosis can generally be made preoperatively when a painful snapping band is palpable in the infrapatellar areas. Rarely, the arthroscopic surgeon may encounter a painful synovial thickening proximal to the medial femoral condyle, and resection of this mass may give symptomatic relief (10).
Lindberg et al (11) noted the importance of recognizing the relationship between chondral damage and patellar malalignment. Most often, however, an arthroscope will help in defining the extent of articular degeneration (12, 13) before definitive surgery. The difference between Outerbridge Grade 2 fibrillation and Outerbridge Grade 4 exposed bone on the lateral facet may be the difference between a lateral retinacular release and an anteromedial tibial tubercle transfer in some patients. One can distinguish such lesions using the arthroscope.
Resection of chondral flaps may be helpful in relieving anterior knee pain. One must question, however, the reason for articular cartilage breakdown and decide if more definitive treatment is necessary to correct a causative mechanical abnormality. Ogilvie-Harris and Jackson (14) emphasized the importance of resecting loose articular cartilage in patients with post‑traumatic patellar lesions.
Inside Chapter 13: