For patients struggling with chronic knee instability, the decision to undergo surgery often comes with a heavy set of questions regarding risk and recovery. A new analysis suggests that for those undergoing medial patellofemoral ligament (MPFL) reconstruction, obesity may not increase the risk of surgical complications, challenging some traditional assumptions about preoperative weight.
The findings, presented at the American Academy of Orthopaedic Surgeons Annual Meeting in New Orleans, indicate that patients with a body mass index (BMI) of 30 kg/m² or greater experienced complication rates similar to those with a BMI below that threshold. This suggests that the surgical stabilization of the patella—the kneecap—remains a viable and safe option for a broader range of patients than previously presumed.
While the safety profile remains consistent across weight groups, the study highlighted a distinct gap in how patients perceive their recovery. Those in the higher BMI category reported significantly lower satisfaction and functional outcomes both before and after the procedure, suggesting that while the surgery is technically successful, the overall experience of recovery differs.
The research utilized prospectively collected data from the Justifying Patellar Instability Treatment by Early Results (JUPITER) cohort, following 713 patients through their surgical journeys. Of this group, 603 patients had a BMI of less than 30 kg/m², while 110 patients had a BMI of 30 kg/m² or greater.
The limitations of BMI in surgical planning
The study underscores a growing conversation in orthopedic medicine regarding the reliance on BMI as a primary metric for surgical risk. While BMI is a standard tool for screening, clinicians argue it is an incomplete picture of a patient’s actual health status.
Elizabeth R. Dennis, MD, MS, FAAOS, an assistant professor in the department of orthopedics at Icahn School of Medicine at Mount Sinai Hospital, noted that BMI is an imperfect measure of obesity. According to Dennis, while the measurement is quick and easy, it fails to capture essential variables such as body composition, musculoskeletal health, strength and functional status—all of which play critical roles in how a patient responds to surgery.
This nuance is particularly critical in MPFL reconstruction, a procedure designed to prevent the kneecap from sliding out of place. Because the surgery relies on the integrity of the surrounding tissues and the patient’s ability to engage in postoperative rehabilitation, a patient’s functional strength may be a more accurate predictor of success than their weight alone.
Comparing complications and patient outcomes
The research team, led by Lasun O. Oladeji, MD, PhD, an assistant professor of clinical orthopedics at the University of Miami, focused on specific clinical failures, including patellar subluxation (partial dislocation), full dislocation, and the need for reoperation. The data showed no significant difference in these critical complications between the two groups.
However, the “patient-reported outcomes”—how the patients felt and functioned in their daily lives—told a different story. Patients with a BMI of 30 kg/m² or greater consistently reported worse scores across several standardized metrics, including the Kujala score and the Knee Injury and Osteoarthritis Outcomes Score for Joint Replacement (KOOS JR).
| Timeline | BMI < 30 kg/m² | BMI ≥ 30 kg/m² |
|---|---|---|
| Baseline | Higher functional scores | Significantly lower scores (Kujala, Pediatric IKDC, KOOS JR) |
| 1 Year Post-Op | Improved outcomes | Lower scores (Pediatric IKDC, KOOS JR) |
| 5 Years Post-Op | Sustained stability | Lower scores (Kujala, KOOS JR) |
The disparity in these scores suggests that while the surgery effectively stabilizes the joint regardless of weight, the associated challenges of obesity—such as increased joint stress or comorbidities—may hinder the patient’s subjective sense of recovery and overall knee function over the long term.
Clinical implications for knee stabilization
The takeaway for surgeons and patients is that obesity should not be a barrier to receiving necessary stabilization procedures for recurrent instability. The evidence suggests that patients with a higher BMI still have the potential to achieve meaningful clinical improvement and successful surgical outcomes.
Instead of using BMI as a reason to defer surgery, the researchers suggest it should be used as a prompt for more comprehensive preoperative counseling. Dennis emphasized the importance of helping patients optimize “modifiable risk factors” and functional status before entering the operating room. This approach—focusing on preoperative strength and health—may help bridge the gap in postoperative outcomes for patients with higher BMIs.
For those seeking more information on knee instability and surgical options, the American Academy of Orthopaedic Surgeons provides patient resources on patellar dislocation and reconstruction.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Patients should consult with a board-certified orthopedic surgeon to determine the best treatment plan for their specific condition.
The medical community continues to refine the JUPITER cohort data to better understand the long-term trajectory of knee stability. Further updates on patient outcomes and the impact of preoperative optimization are expected as more long-term follow-up data becomes available from the study participants.
We invite readers to share their experiences with knee reconstruction and recovery in the comments below.
