Recurrent patellar dislocations may be associated with increased trochlear chondral damage
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Key takeaways:
- More than five patellar dislocations may increase patients’ risk for trochlear chondral damage.
- Researchers found no association between the number of dislocations and occurrence of patellar chondral lesions.
Published results showed recurrent patellar dislocations were associated with increased incidence and severity of trochlear chondral damage but not patellar chondral damage.
Joshua Turner Bram, MD, a resident in the department of pediatric orthopedic surgery at Hospital for Special Surgery, and colleagues performed a prospective, multicenter, cohort study of 938 patients (mean age, 16.2 years) who underwent primary surgery for patellofemoral instability between December 2016 and September 2022. Bram and colleagues assessed the relationship between recurrent patellar dislocations and cartilage lesions, which were classified using the International Cartilage Repair Society classification system, according to the study.
Among the cohort, 580 patients (61.8%) had a chondral lesion. Lesions were commonly found in the patella (n = 498; 53.1%), the lateral femoral condyle (n = 117; 12.5%) and trochlea (n = 109; 11.6%).
Bram and colleagues found patients with more than five patellar dislocations had increased incidences of trochlear chondral lesions (19.8%) compared with patients with one dislocation (7.6%) or two to five dislocations (11%). In addition, they found patients with a higher number of patellar dislocations were more likely to have ICRS grade 2 to 4 trochlear lesions.
After multivariable regression analysis, Bram and colleagues more than five recurrent patellar dislocations were a significant predictor of trochlear lesions (OR = 3.03). Bram and colleagues also found no relationship between the number of patellar dislocations and the incidence of patellar chondral lesions.
“This may be reflective of thicker cartilage on the patella, providing protection against chondral injuries with subsequent dislocation events, whereas lateral femoral condylar lesions may be more likely to occur only with an initial traumatic dislocation in deeper flexion with recurrent instability from a deficient medial patellofemoral ligament in extension,” Bram and colleagues wrote in the study.
However, they noted combined patellar and trochlear lesions were more common in patients with more than five patellar dislocations.
“These findings should caution surgeons regarding prolonged nonoperative treatment,” Bram and colleagues concluded.
Perspective
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The authors aimed to assess the association between increasing patellar dislocation events and chondral injuries. They reported that more than five dislocation events were associated with greater than a threefold increase in incidence and severity of chondral lesions of the trochlea. There were no differences in the presence or grade of patellar lesions.
While there is generalized agreement among practitioners as to the need for patellar stabilization in patients with recurrent dislocations of the patella, the treatment of first-time dislocation continues to be debated. This study adds additional data that continued progressive damage occurs with subsequent dislocation events.
Moreover, it should be noted that patellar chondral injuries still represent most lesions found on evaluation (53.1% in this study). The advent of trochlear lesions, in addition to the commonly found patellar lesions, portends the advancement of early stage patellofemoral arthritis and may complicate successful joint preservation strategies. Patients and surgeons should not become complacent with the status quo – as can often happen when patients feel that recurrent dislocation is their new “normal.”
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