Chondroplasty, or débridement, is the most commonly performed cartilage procedure. This technique is invasive and is performed arthroscopically. It consists of debriding the unstable cartilage tissue to a stable rim. In general, the indication for this procedure includes small (1-2 cm²) contained chondral lesions. Reports of the outcomes after chondroplasty in the PF joints are limited. Postoperative physical therapy is important for a good outcome. Recently, Anderson et al³ reported good clinical outcomes with 2-year follow-up in patients who underwent mechanical chondroplasty in isolation in the cohort of patients, in which approximately half of those had chondral lesions in the PF joints. However, long-term outcomes still remain unclear.

This procedure includes débridement of chondral lesions with removal of the calcified layer of cartilage tissue to
enhance repair integration to the subchondral bone and penetration into the subchondral bone to release bone marrow elements to the defect surface. This allows stem cells and growth factors to form a “super clot” and stimulate cartilage repair via a cell-based repair. In general, the indication for this procedure has included an acute (<3-6 months post injury) small chondral and contained lesion (<2-3 cm²). Bipolar lesions and uncontained lesions are contraindications to this procedure. Strict adhesion to the principle of the technique is necessary for a favorable outcome as well as a strict postoperative protocol of touch weight-bearing for 6 weeks and the use of continuous passive motion. Kreuz et al noted the decline of clinical outcomes after 2 years for chondral lesions treated with microfracture.⁴ This is likely due to the nature of the repair tissue consisting of collagen type I instead of collagen type II. They also evaluated the outcomes after microfracture based on the compartment treated: PF versus TF. They demonstrated unfavorable results for the PF joints compared to TF joints.⁴ The best results occurred when the patient was less than 40 years old, when surgery was performed within 12 months of the injury, and the body mass index was less than 30 kg/mm². In addition, although technically simple to perform, microfracture may require a mini arthrotomy to access the patella, and as the results for the patella are unpredictable one must always consider a subsequent salvage procedure such as ACI.⁵,⁶ Unfortunately, following microfracture, ACI has been shown to have an increased failure rate. Microfracture can in fact “burn bridges” for future treatments.

Osteochondral autograft transplantation (OAT) is generally indicated for a lesion area of approximately 2 to 4 cm². This technique involves harvesting 10- to 15-mm-deep autologous osteochondral plugs from the femoral condyle and/or trochlea and transplanting them into the cartilage defect (Fig. 20-1). The defect is filled with harvested hyaline cartilage and the underlying subchondral bone as an “osteochondral unit.” However, OAT takes from “Peter to pay Paul” and consequently may result in donor tissue morbidity. The osteochondral donor plugs should be harvested from the margins of the distal lateral and medial trochlea or intercondylar notch and stay out of the load-bearing portion of the PF joint. Further concerns include the unmatched shape or incongruous shape of the host and donor cartilage surfaces in addition to the limitation of defect size for relatively small lesions. Realistically lesions of 1.5 to 2 cm² are what most surgeons utilize as a cutoff for not causing donor site problems. The surgical technique requires a precise graft fit and making a smooth articular surface for the PF joint for a satisfactory outcome. The unique anatomy of the patella and trochlea specifically impose surgical difficulties in matching the articular geometry of the donor to the patella or the trochlea. In addition, the articular thickness of the cartilage from the femoral surfaces is only 2 to 3 mm, whereas the patella thickness is 5 to 7 mm. In matching the surface topography, the donor plug is usually surrounded by articular cartilage and not subchondral bone and is therefore prone to resorption and collapse over time.

The outcomes of OAT in the PF joints are inconsistent. Hangody et al reported 79% good to excellent results in patients with chondral lesions in the PF joints, and 92% in the femoral condyle.⁷ On the other hand, most others found almost a universal failure of OAT in the patella.⁸ Bentley recommended universal abandonment of the technique in the patella because of the abysmal results when compared to ACI.⁸ A recent study with a larger sample size by Astur and colleagues demonstrated OAT for patellar defects had better outcomes at 2 years for lesions smaller than 2.5 cm².⁹ The inconsistency in outcomes may be explained by the fact that the results are likely dependent on the exacting surgical technique required, the importance of grafting perpendicular, and flush to the adjacent cartilage in order for satisfactory results in the PF joints.¹⁰