chapter 13: Surgical Treatment of Patellofemoral Chondrosis and Arthrosis
Particularly important are findings such as those reported by Leslie and Bentley (15), in which normal patellar articular cartilage (Fig. 13.3) was found in many patients with patellofemoral pain. The peripatellar retinaculum may be a primary source of pain in many of these patients (16). The same patellar imbalance that causes retinacular stretching and injury may lead later to articular cartilage breakdown and arthrosis because of abnormal contact pressure distribution. Lateral release alone often will help the patient with patellar tilt and minimal arthrosis, which have not responded to nonoperative rehabilitation. The approach to such patients has been reviewed thoroughly in Chapter 8.
When advanced arthrosis accompanies patellar instability, the treatment becomes more difficult. Grana et al (17) pointed out that unsatisfactory results of arthroscopic treatment are related to painful crepitation. In such patients, extensor mechanism realignment or decompression by anteriorization of the extensor mechanism may be necessary. There are some patients with patellar arthrosis in whom extensor mechanism anteriorization may be desirable at the same time as realignment such that anteromedial or anterolateral tibial tubercle becomes necessary..
Whereas some patients develop patellar arthrosis after trauma to the patella, patellar arthrosis is frequently caused by longstanding extensor mechanism malalignment and poor distribution of articular contact pressures. Fortunately, many such patients will respond to nonoperative treatment or lateral retinacular release. When lateral facet arthrosis is severe (Outerbridge Grades 3‑4), however, and pain is attributed to articular breakdown with resulting subchondral bone irritation, realignment and/or anteriorization of the patella may be indicated (18). Kolowich et al have pointed out that the most predictable indicator of a good result from lateral release is a chronic tilt of the patella associated with a tight lateral retinaculum (19).
Anteromedial tibial tubercle transfer (20) achieves both unloading of the patella and improved alignment in one operation, assuming that there is preoperative lateral patellar tilt and/or subluxation. Although the same mechanical result is possible using bone graft behind an elevated tibial tubercle, as described by Bandi (21), Maquet (22), Ferguson (23, 24), and Radin (25, 26), similar benefit may be achieved with anteromedial tibial tubercle transfer which does not require bone graft or distraction of the osteotomized tibial tubercle.
When there is significant malalignment and clinically evident chondromalacia or arthrosis, surgical treatment will be determined best using simple logic. One must correct malalignment by realigning the joint and treating the effect (articular degeneration), when significant, by unloading and either debriding or resurfacing the deficient area. Tables 13.1 and 13.2 present an overview of my classification and treatment program.
Simple lateral retinacular release will usually reduce abnormal patellar tilt, particularly if articular cartilage softening has not progressed to the point of joint collapse. Many patients with Outerbridge Grades 1 and 2 lesions of patellar articular cartilage and associated tilt respond very well to lateral retinacular release, particularly if pain is most prominent in the lateral retinaculum. Patients with Outerbridge Grades 3 to 4 arthrosis of the lateral facet must be evaluated carefully, and if lateral release is chosen as the treatment, the patient should be warned that there is some risk of recurrent pain, particularly if the arthrosis itself is symptomatic.
Inside Chapter 13: