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Isolated MPFL reconstruction was effective to treat instability in patients with trochlear dysplasia
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Isolated medial patellofemoral ligament reconstruction is indicated for patients with recurrent instability and moderate to severe dysplasia and who have a normal tibial tubercle trochlear groove and normal patellar height, according to presented results.
“A patient with relatively normal [tibial tubercle-trochlear groove] TT-TG and normal patellar height can successfully undergo isolated [medial patellofemoral ligament] MPFL reconstruction despite the presence of moderate to severe dysplasia,” Joseph N. Liu, MD, orthopedic resident at Hospital for Special Surgery, said.
Liu and his colleagues retrospectively reviewed 121 patients (73% were women) who underwent isolated MPFL reconstructions for recurrent patellar instability, but did not have concomitant bony procedures. They collected patient demographics, including age, BMI, comorbidities and the number of preoperative dislocation events, and then assessed MRI results for the presence of osteochondral lesions or fractures, trochlear dysplasia or TT-TG distance.
“Trochlear dysplasia was graded using the Dejour classification by the senior surgeon, and our primary outcome was whether the patient had patellar subluxation or dislocation postoperatively,” Liu said. “Patient-reported outcomes were also collected preoperatively and at final follow-up and were considered secondary outcomes.”
Results showed significant trochlear dysplasia in most patients and a TT-TG of greater than 20 mm in one patient.
“Three of our patients had either a postoperative dislocation or subluxation event and, although no significance can be drawn due to the low numbers, not only did all these patients have trochlear dysplasia, they also had patella alta,” Liu said.
There were no reports of deep vein thrombosis, pulmonary embolism, infection, hospital readmission, arthrofibrosis, fracture or compartment syndrome. However, Liu noted repeat arthroscopic debridement was performed in one patient for persistent pain. An improvement was seen in all patient-reported outcome measures (PROMs) with no independent associations between PROMs and Dejour classification, Caton Deschamps ratio or TT-TG, he added.
“We did find that preoperatively there was a decreased Kujala score with increased trochlear dysplasia, but at final follow-up there was no difference in any of the PROMs,” Liu said.
Despite the positive study outcomes, data are needed to predict which patients with a first-time dislocation should undergo surgery vs. nonoperative care, Liu told Orthopedics Today.
“What our research is focused on right now is determining risk factors, such as ... trochlear dysplasia or ligament laxity, which can help push surgeons to identify those patients who need surgery upon their first dislocation,” Liu said. “The treatment algorithm is not so clear on which [patients] need [surgical treatment] and which ones might be able to get away with nonoperative care,” he said. – by Casey Tingle
- Reference:
- Liu JN, et al. Paper #15. Presented at: American Orthopaedic Society for Sports Medicine Specialty Day Meeting. March 18, 2017; San Diego.
- For more information:
- Joseph N. Liu, MD, can be reached at Hospital for Special Surgery, 535 East 70th St., New York, NY 10021; email: liuj@hss.edu.
Disclosure: Liu reports no relevant financial disclosures.
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Jack Farr, MD
Liu and colleagues are to be congratulated on this important contribution that improves the treatment algorithm for recurrent patellar instability. This information is germane in light of the current increase in the number of trochleoplasties performed in the United States. With the known complexity and guarded long-term chondral changes that can be associated with trochleoplasty, surgeons now have a rationale for first addressing the MPFL deficiency alone (fully appreciating the literature would suggest there is a higher recurrence of instability in the subset with advanced trochlear dysplasia and extremes of patella alta). Caution is also warranted in determining a normal TT-TG, because in severe dysplasia there is often no ability to accurately identify the trochlear groove and thus have the advantage of checking the TT-PCL distance. The researchers are encouraged to proceed to similar prospective studies and a randomized controlled trial.
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Vicente Sanchis-Alfonso, MD, PhD
The authors reached this conclusion: In patients with normal TT-TG ratios, isolated MPFL reconstruction provides safe and effective treatment for patellofemoral instability, despite the presence of Dejour class C or D trochlear grooves. I agree with this conclusion, which fully coincides with my clinical experience. The presence of severe trochlear dysplasia (Dejour class C or D) does not imply, in all cases, the need to perform a sulcus-deepening trochleoplasty in addition to the MPFL reconstruction. The trochleoplasty is an aggressive procedure, which is technically demanding and not without complications. It should be used only in selected cases. In primary surgery, I only perform the Dejour sulcus-deepening trochleoplasty in selected patients with lateral patellar instability who are extremely disabled and have a severe trochlear dysplasia. However, if the patella does not dislocate beyond 45° knee flexion and there is no clear patellofemoral maltracking, I never perform a trochleoplasty, even if the patient has a severe trochlear dysplasia. In my personal series, the clinical results of an isolated MPFL reconstruction in patients with severe trochlear dysplasia in whom the patella does not dislocate beyond 45° knee flexion and with no clear patellofemoral maltracking are highly satisfactory, as are the results of Liu and his colleagues. In the patellofemoral joint, we should always do as little as we can surgically. Less is more in the surgical treatment of patellofemoral conditions.
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