All reported cases of patellofemoral cartilage restorative procedures and palliative procedures between 2016 and 2021 were included from the database using CPT codes associated with laterality-specific ICD-10 codes ( Appendix Table 1 , available at www.arthroscopyjournal.org ) for patellofemoral joint and cartilage disorder linked to the same day. CPT codes for cartilage restorative procedures included 27412 (autologous chondrocyte implantation, knee), 29867 (arthroscopy, knee, surgical; osteochondral allograft), and 29866 (arthroscopy, knee, surgical; osteochondral autografts). CPT codes for cartilage palliative procedures included 29877 (arthroscopy, knee, surgical; debridement) and 29879 (arthroscopy, knee, surgical; abrasion arthroplasty). These cohorts were additionally queried for concomitant TTO at the time of index patellofemoral cartilage restorative or palliative procedure using the CPT code 27418 (anterior tibial tubercleplasty). Patients were excluded if they had same-day laterality-specific ICD-10 codes for chondromalacia of the knee (as opposed to the patella), primary osteoarthritis of the knee, articular cartilage tear of the knee, and osteochondritis dissecans of the knee. Articular cartilage of the knee was excluded, given the likelihood of significant overlap with cartilage restoration procedures of the femoral condyles from that given ICD code. PearlDiver also allows for “active” tracking of patients, which confirms they maintained insurance enrollment and follow-up with a provider during a specified time period. This function was used as a proxy for ensuring patients were not lost to follow-up for at least 2 years postoperatively. Additionally, use of ICD-10 coding allows for laterality-specific tracking to ensure ipsilateral revision on the same side as the index procedure. Demographic variables queried included year of surgery, patient age at time of surgery, sex, Charlson Comorbidity Index (CCI), and obesity.

We used t tests and χ ² tests were, respectively, to compare numerical and categorical demographic data between those who underwent patellofemoral cartilage restorative surgery and those who underwent index patellofemoral cartilage palliative surgery. Analysis of variance with a Tukey honestly significant differences post hoc test was used to compare age and CCI between a patient who underwent a specific cartilage restorative surgery and those who had other cartilage restorative surgeries. For example, this analysis allows us to directly compare the age of patients who underwent ACI compared to the age of patients who underwent either OCA or OAT. The change in annual patellofemoral cartilage restorative and palliative procedures performed from 2016 to 2021 was analyzed using multiple linear regression. Overall fit of the model was evaluated through F statistic, degrees of freedom, and its significance ( P <.05). The χ ² analysis was used to compare the incidence of 5-year revision rates for patellofemoral cartilage restorative and palliative procedures. Descriptive analysis was used to evaluate the rate of subsequent total joint arthroplasty (TJA), as determined by procedure CPT codes ( Appendix Table 1 , available at www.arthroscopyjournal.org ). Multivariable logistic regression was used to evaluate the association between 5-year patellofemoral cartilage revision surgery (cartilage restorative or palliative surgery) and index cartilage restoration procedure with and without concomitant TTO, as well as baseline demographics. Patellofemoral cartilage revision surgery was defined by the same CPT codes used to query for patients undergoing patellofemoral cartilage palliative or restorative surgery as described above (CPT codes 27412, 29867, 29866, 29877, 29879). All graphing analyses were performed using Excel Version 16.46 (Microsoft), while statistical analysis was performed via PearlDiver’s internal R statistical analysis tool. Significance was defined as P <.05. Exact P values were provided when able but rounded to <.001 if smaller than such values.