Less instability seen with MPFL reconstruction vs no reconstruction in adolescents
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Medial patellofemoral ligament reconstruction in adolescent patients with patella instability resulted 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 - San Diego, said at the American Orthopaedic Society for Sports Medicine Annual Meeting.
He 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?”
Patellar instability, loose body
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 outcomes (n=23). 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 with the MPFL-neglect cohort (16.7% vs. 58.7%, respectively) and had fewer patients who required subsequent surgery. Further, investigators found statistically significant differences in Insall-Salvati ratios (mean 1.3 vs. mean 1.4, respectively), although no other statistically significant differences were found for 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 said. “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.”
Avoid graft over-tensioning
In an interview with Orthopedics Today, Pennock said, “Technically, I think one of the keys with an MPFL reconstruction that is often overlooked is not over-tensioning the graft. This tends to occur in cases where there is higher grade dysplasia and the graft is tensioned in greater amounts of extension.”
He said, “An easy trick that I have found to avoid this complication is to hyperflex the knee prior to fixing the graft on the femur. I then pull the slack out of the graft with the knee hyperflexed. At this point, I bring the knee into 30° to 60° flexion and secure the graft, but I make sure to not tension it further. After the graft is secure, I then double check the graft tension one final time and confirm the patient still has full range of motion (ROM) with improved tracking of the patella. If the graft is over-tensioned, the knee may not be able to be flexed completely or the patient’s patella may track with a ‘reverse J-sign’ where it subluxates medially over a dysplastic lateral trochlea through a ROM. In these situations, the graft needs to be loosened.”
Successful return to sports with reconstruction
Pennock said in the interview after the meeting, “Since looking at our data and evaluating our institution’s experience, I have changed my surgical approach when managing an adolescent patient with a first-time dislocation with an associated loose body that needs surgical intervention. Historically, in these situations, I either fixed the osteochondral fracture or removed the loose body, but I did not reconstruct the MPFL. In select situations, we did repair or imbricate the medial soft tissues, particularly when an open arthrotomy was being performed, to address a fracture involving the medial facet of the patella. Unfortunately, with this approach, irrespective of whether the medial soft tissues are neglected or repaired, a majority of patients experienced recurrent patella instability within 5 years. Since we have moved towards reconstructing the MPFL in these patients, we have not only dropped our recurrent instability rate to around 10%, but we also have better success returning athletes to sport and we have equivalent, if not superior, patient-reported outcomes. In my experience adding the MPFL reconstruction adds little to the postoperative recovery since many of these patients will already be out for a minimum of 3 months to enable their osteochondral fracture to heal. Ultimately, longer term data will be necessary to determine what is worse for the knee — recurrent instability if the MPFL is not reconstructed or any possible over-constraint of the knee from an MPFL reconstruction.”
- For more information:
- Andrew T. Pennock, MD, can be reached at 3030 Children's Way, San Diego, CA 92123; email: apennock@rchsd.org.
Perspective
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Shital N. Parikh, MD
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, however, it does 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).
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