Insurance Status and Income Proxies Are the Most Consistent Predictors of Disparities in Access to Care and Outcomes After Medial Patellofemoral Ligament Reconstruction in the United States: A Systematic Review

Purpose

To evaluate the influence of health care access, insurance coverage, racial and ethnic identity, income-related proxies, employment status, preventive care use, and geographic location on the diagnosis, treatment, and outcomes after medial patellofemoral ligament reconstruction (MPFLR).

Methods

A systematic review of electronic databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify Level II-IV clinical studies related to patellar instability that were published between January 2010 and January 2025. Studies were included if they were peer-reviewed English-language studies detailing the socioeconomic and demographic factors of outcomes after MPFLR. Case reports, systematic reviews, animal and cadaver studies, and publication formats other than peer-reviewed journal studies were excluded.

Results

Seven studies met inclusion criteria, which resulted in a total 983,985 patients (983,658 female, 99.97%, and 327 male, 0.03%). Three studies (42.9%) found that insurance status affected the evaluation and treatment of patients with patellar instability, and subsequent outcomes after MPFLR, with those who were privately insured experiencing a better clinical course with regards to evaluation, treatment, and outcomes. Four (57.1%) studies identified race or ethnicity as a factor that influenced the prevalence of patellar instability, treatment, cost, and outcomes. One study (12.5%) found certain markers of high income such as home ownership, full-time employment, and having a recent health check-up positively affected the evaluation, treatment, and postoperative outcomes of patients with patellar instability.

Conclusions

This systematic review found that lower socioeconomic status, public insurance coverage (as opposed to private coverage), and minority racial or ethnic identity were associated with delayed evaluation, lower likelihood of surgical intervention, and reduced postoperative compliance or satisfaction among patients undergoing MPFLR. Patients with these characteristics experience longer wait times from injury to clinic evaluation and have reduced odds in selection as a candidate for surgery. Postoperative satisfaction was also markedly worse for surgical patients with these characteristics.

Level of Evidence

Level IV, systematic review of Level III and IV studies.

The primary factor responsible for preventing lateral movement of the patella is the medial patellofemoral ligament (MPFL), which is frequently torn when the patella is dislocated. Untreated recurrent lateral patellar instability has been associated with intra-articular cartilage damage that may impact knee function in both daily and athletic activities. Medial patellofemoral ligament reconstruction (MPFLR) is one of the most common surgical treatments for patellar instability. Socioeconomic factors (income, level of education, insurance status, etc.) may impact the early recognition of patellar instability and the ability to pursue appropriate treatment.

Disparities in health care outcomes manifest in various forms, including differences in access to care, insurance coverage, quality and timeliness of treatment, and geographic availability of specialized services. Understanding the underlying cause of these disparities is essential to develop effective strategies for eliminating them. In investigating the influence of these disparities, we operationally define social determinants of health as health care access, insurance coverage, racial and ethnic identity, income-related proxies, employment status, preventive care use, and geographic location. These measures of disparities play a significant role in the health care disparities that patients experience when undergoing orthopaedic procedures, including MPFLR. Previous studies have found that socioeconomic and patient-related factors such as age, sex, socioeconomic status, and race impact the odds of undergoing many orthopaedic surgeries (eg, anterior cruciate ligament reconstruction, total joint arthroplasty, and spine surgery) as well as the associated outcomes. ^,^, Identifying the socioeconomic and demographic factors that influence care for patients with patellar instability may enable orthopaedic surgeons to intervene at an earlier stage in the disease process and potentially lead to more favorable postoperative outcomes.

The few studies published regarding the socioeconomic factors that influence treatment of patellar instability have found that race, sex, and insurance status may be significant predictors of access to surgical care, timing of initial evaluation and surgery, and cost of treatment. ^, In 2023, Shankar et al. performed a single-institution retrospective case study investigating socioeconomic predictors of time to initial evaluation, time to surgery, and postoperative outcomes among patients with lateral patellar instability undergoing MPFLR. The authors found that markers of greater socioeconomic status, including having a general check-up in the year before surgery, home ownership, and full-time employment were predictive of shorter time to initial evaluation, shorter time to surgery, and superior postoperative outcomes after MPFLR. In addition, previous studies have reported that patient sex is a social determinant of health that impacts outcomes after MPFLR. Female patients have a 5.45 times greater risk of any postoperative complications; greater 1-, 5-, and 8-year risk of recurrent dislocation or instability, and worse postoperative outcome scores. ^,^, Associations between several socioeconomic factors, treatment delays, and poor postoperative outcomes are well-documented in the literature for procedures including but not limited to shoulder arthroplasty and anterior cruciate ligament reconstruction. ^,^,^, However, there is a paucity of literature regarding the impact of socioeconomic and demographic factors on outcomes after MPFLR. The purpose of this study was to evaluate the influence of health care access, insurance coverage, racial and ethnic identity, income-related proxies, employment status, preventive care use, and geographic location on the diagnosis, treatment, and outcomes after MPFLR. We hypothesized that health care access, insurance coverage, racial and ethnic identity, income-related proxies, employment status, preventive care use, and geographic location would significantly influence treatment and outcomes in patients with patellar instability.

Methods

Search Strategy

A systematic review of PubMed, Web of Science, Embase, and CINAHL was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses in January 2025. The primary socioeconomic or demographic factors of interest were health care access, insurance coverage, and racial and ethnic identity. Additional factors of interest not explicitly searched for were income-related proxies, employment status, preventive care use, and geographic location. Search terms included “medial patellofemoral ligament reconstruction,” “patellar instability,” “socioeconomic factors,” “insurance,” “race,” and “health services accessibility.” Studies published between January 2010 and January 2025 that were conducted in the United States were taken into consideration for inclusion. Appendix Table 1 , available at www.arthroscopyjournal.org , contains a complete documentation of the database search strategies.

Eligibility Criteria

Peer-reviewed English-language studies examining at least 1 socioeconomic or demographic factor impacting outcomes after MPFLR were included. Studies were excluded if they were case reports, systematic reviews, animal and cadaver studies, and publication formats other than peer-reviewed journal articles.

Study Selection Criteria and Procedures

The Covidence systematic review program was used to upload all identified studies. Independently and collaboratively, 2 reviewers (E.L.B. and K.T.N.) assessed the eligibility of studies that examined socioeconomic and demographic factors affecting outcomes after MPFLR. After full-text evaluation, studies that met inclusion criteria were included in this systematic review. Disputes regarding selection were settled by consensus. This was implemented to improve the protocol and data inclusion, strengthen the objectivity, and prevent errors in the research selected for the study. The Risk Of Bias in Non-Randomized Studies– of Interventions (ROBINS-I) tool was used to evaluate the risk of bias in observational studies, cross-sectional research, systematic reviews, and nonrandomized trials.

Data Extraction

The following data were extracted from all studies that met inclusion criteria: race/ethnicity, insurance, household income, socioeconomic status, as well as validated outcome scores such as visual analog scale (VAS) satisfaction and the Kujala score.

Results

The initial search identified 316 studies. After eliminating 178 duplicates, the 2 authors screened 138 abstracts and titles. After this, 22 studies underwent a full-text review. Seven studies met inclusion criteria with a total of 983,985 patients (983,658 female, 99.97%, and 327 male, 0.03%) ( Fig 1 , Table 1 ). ^,^,^,^,^,^,

Image, AltText currently not available — Fig 1

Table 1

Characteristics of Studies Included in the Systematic Review

Study	Study Design	Level of Evidence	Number of Participants	Patient Sex	Follow-Up Time	Barrier(s) Identified
Allahabadi et al, 2022	Retrospective case series	III	78	46 female, 32 male	601 ± 418 d	Sex, age, race/ethnicity, insurance status
Li et al., 2021	Retrospective cohort	III	2,557	1,384 female, 1,173 male	Not explicitly stated	Sex, age, race/ethnicity, insurance status
Shankar et al., 2023	Retrospective case series	IV	70	51 female, 19 male	45.7 ± 25.3 mo	Sex, age, race/ethnicity, insurance, markers of high income
Hiemstra and Kerslake, 2019	Cohort	III	298	225 female, 73 male	26.4 mo	Sex
Howard et al., 2024	Retrospective cohort	III	85	48 female, 37 male	4-7 mo	Race/ethnicity, socioeconomic status
Walawski et al., 2024	Prospective cohort	III	39	26 female, 13 male	Both 6 mo and 12 mo	Geographic, rural vs urban locations
Martinazzi et al, 2023	Cross-sectional study	III	980,878	980,878 female	Not explicitly stated	Sex, contraceptive use

Risk of Bias Assessment

The ROBINS-I tool was used to evaluate the risk of bias in eligible studies ( Table 2 ). Most studies reported strong methodologic quality and had low concern for bias attributable to the selection of participants, classification of interventions, deviations from intended interventions, missing data, measurement outcomes, and in the selection of the reported results. Thus, all of the studies only had low-to-moderate concerns for overall bias.

Table 2

Quality and Risk of Bias Assessment Using the Risk Of Bias in Non-Randomized Studies– of Interventions (ROBINS-I) Tool

Study	Confounding Bias	Participant Selection Bias	Intervention Classification Bias	Bias due to Deviations From Intended Interventions	Bias due to Missing Data	Bias in Measurement Outcomes	Bias in Selection of the Reported Results	Overall Bias
Allahabadi et al., 2022	Moderate	Low	Low	Low	Low	Low	Moderate	Moderate
Li et al., 2021	Low	Low	Low	Low	Low	Moderate	Low	Low
Shankar et al., 2023	Moderate	Low	Low	Low	Low	Moderate	Low	Moderate
Hiemstra and Kerslake, 2019	Low	Low	Low	Low	Low	Low	Low	Low
Martinazzi et al., 2023	Low	Low	Low	Low	Low	Low	Low	Low
Walawski et al., 2024	Low	Low	Low	Low	Moderate	Low	Low	Moderate
Howard et al., 2024	Low	Low	Low	Low	Moderate	Low	Low	Low