Study examines MPFL reconstruction in adolescents with instability vs no reconstruction
Medial patellofemoral ligament reconstruction in adolescent patients with patella instability results in less instability and subsequent surgery compared with no reconstruction surgery, according to presented findings.
“Patella instability, as we all know, is common adolescent population and recurrent instability rates are as high as 50% to 90%, depending on the number of risk factors that the patient has,” Andrew T. Pennock, MD, of Rady Children’s Hospital in San Diego, said in a presentation for the American Orthopaedic Society for Sports Medicine Annual Meeting. The meeting was held virtually. Pennock said, “It tends to require surgical intervention, either removal or open reduction internal fixation. The question remains: What should be done with the MPFL at the time of this surgery?”
In a retrospective study, investigators analyzed data of 51 adolescent patients (mean age: 14 years) who sustained a patellar instability that resulted in an intra-articular loose body for “MPFL neglect” (n= 21) vs. MPFL reconstruction (n=23) outcomes. Researchers performed chart and radiographic reviews and evaluated other variables including Insall-Salvati ratios.
Study results showed the reconstruction cohort developed significantly less instability compared to the MPFL-neglected cohort (16.7% vs. 58.7%, respectively), as well as fewer patients requiring subsequent surgery . Further, investigators found statistically significant differences in Insall-Salvati ratios (mean 1.3 vs. mean 1.4, respectively), while no other statistically significant differences were found among other evaluated variables.
“MPFL reconstruction in the setting of an adolescent athlete with patellar dislocation of the intra-articular was spotty. This results in a significantly lower rate of recurrent instability compared to those who did not undergo ligament reconstruction,” Pennock concluded. “It really raises the question what is worse for the knee: having further episodes of recurrent instability or potentially over-constraining with MPFL reconstruction, and that is why the future follow-up will be important.”
Perspective
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The authors have previously reported on a cohort of adolescent patients with first-time patellar dislocation who underwent loose body/osteochondral fracture treatment with concomitant MPFL repair/neglect. In the current study, they compare this historical control to another cohort of patients who underwent loose body treatment with concomitant MPFL reconstruction and found significantly lower recurrent instability rates and a trend for higher satisfaction in the latter group. The preexisting anatomic risk factors and postoperative clinical outcome scores were comparable in both groups.
This study further reinforces the evolving trend of MPFL reconstruction over MPFL repair. Though MPFL repair may have a role in certain situations, like avulsion injuries or tears in patients with normal patellofemoral anatomy, the selection of ideal candidates for repair and overall clinical results have been variable and suboptimal. In comparison, isolated MPFL reconstruction has yielded consistent and satisfactory outcomes with decreased rates of recurrent instability in short- and medium-term follow-up studies. The methodology of the current study where treatment approach has changed over a period, produce an inherent bias as the neglect/repair group would have an increased duration of follow-up to report a complication compared to the reconstruction group.
In previous studies, young age has been reported as a risk factor for recurrent instability and for failure of MPFL reconstruction. This effect is compounded in presence of anatomic risk factors. Thus, for a young cohort of adolescent patients as in the current study, longer follow-up would be important to determine if the advantages of MPFL reconstruction over neglect/repair and clinical outcomes after MPFL reconstruction, would hold up over time. The association of ACL reconstruction and osteoarthritis at long-term follow-up should be kept in mind as MPFL reconstruction is offered to young patients with first-time patellar dislocation.
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Gurusamy P, et al. ePoster 191. Presented at: American Orthopaedic Society for Sports Medicine Annual Meeting; July 8-9, 2020 (virtual meeting).