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Patellar redislocation rate up to 20% with MPFL reinsertion or conservative care
Kujala subscores showed more stability for medial patellofemoral ligament refixation patients.
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FLORENCE — Danish investigators studying the role the medial patellofemoral ligament plays in patellar stability found that surgically reinserting it after a patellar dislocation did little to prevent secondary dislocation.
"Delayed primary repair of the medial patellofemoral ligament (MPFL) after primary patella dislocation does not, in our hands, reduce the risk for redislocation, nor does it lead to a better subjective functional outcome," Svend E. Christiansen, MD, said. He presented results of the prospective, randomized study at the 2007 International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Congress.
Christiansen and his colleagues from Aarhus, Denmark, received the ISAKOS 2007 Patellofemoral Research Excellence Award and a $2,500 honorarium.
Prospective study
About 50% of patients with primary lateral patellar dislocations will experience continued instability or redislocations because they develop an MPFL lesion associated with ligament disruption at the medial femoral condyle insertion, according to the study abstract.
Christiansen and colleagues studied patients after primary patellar dislocation to see whether surgically reinserting the MPFL would be more effective at preventing redislocations than conservative care.
Investigators randomized 80 patients into two groups to receive surgery or conservative treatment. Forty was the minimum number per group that their power analysis showed was needed for statistical significance. "We succeeded to follow up with 77 patients; 42 of these patients had the repairs and 35 of them had the conservative treatment," Christiansen explained.
Similar redislocations rates
The researchers included patients aged 13 to 30 years without a prior history of patellar dislocations who were similar in age, gender, height and body mass index. "In our redislocation rates [at 2 years' minimum follow-up], we could see no difference in the operated group and the conservative group," Christiansen said. The operated group's redislocation rate was 16.7% vs. 20% for the conservative group, which was not significantly different.
Investigators found no difference between the groups using the Knee Injury and Osteoarthritis Outcome Score and overall Kujala scores. "However, when we looked at the [Kujala] subscores, we felt that the score was definitely related to the stability of the patella, and it was significantly higher in the operated group compared to the conservatively treated group," he said.
For more information:
- Svend E. Christiansen, MD, can be reached at University Hospital Aarhus, Tage Hansens Gade 2, Aarhus, Denmark DK-8000; +45-8949-5566; e-mail: sec@dadlnet.dk. He indicated he has no financial conflicts to disclose.
- Christiansen SE, Lind M, Maul M, et al. Repair of the medial patellofemoral ligament in primary dislocation of the patella: A prospective randomized study. #136. Presented at the 2007 International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine Congress. May 27-31, 2007. Florence.