Abstract
Objectives:
The medial patellofemoral ligament (MPFL) ligament is one of the most important medial stabilizers of the knee joint. Reconstruction of the MPFL restores knee joint stability in most appropriately selected patients with patellar dislocations. Although rare, revision procedures are performed when primary MPFL reconstruction fails. There are limited data characterizing patients who undergo revision MPFL surgery. The objective of this study is to compare demographic and imaging characteristics of patients undergoing revision MPFL reconstruction with those undergoing primary patellofemoral ligament (PFL) reconstruction.
Methods:
Patients who underwent MPFL reconstruction between 2008 and 2021 were included in this retrospective study. Demographic information (age, sex, body mass index [BMI]), surgical procedures, preoperative imaging (Caton-Deschamps index (CDI), tibial tuberosity to trochlear groove [TT-TG] distance, sulcus angle and depth), clinical findings (J-sign), and intra-op findings (cartilage status) were extracted from the electronic medical records. The above characteristics were compared between the primary and revision cohorts.
Results:
A total of 223 patients underwent MPFL reconstruction within the study period, including 30 revision and 193 primary procedures. For the revision cohort, mean patient age was 23.3 years and the population included 10 males and 20 females, with an average BMI of 29.8 kg/m2. For the primary cohort, the mean age was 23.7 years and the population included 71 males and 120 females, with an average BMI of 27.0 kg/m2. Concomitant tibial tubercle osteotomy was performed in 35 primary cases (18.3%) and in 8 revision cases (26. 7%). The mean TT-TG distance was 24.7mm in the revision group and 17.5 mm in the primary group (p = 0.022). The mean sulcus angle revision group was 145 degrees and 140 degrees for the primary group (p = 0.007). A J sign was noted in 40 % of the revision group and 25% of the primary group (p = 0.011). Articular cartilage damage was noted in the patella in 24 cases (80%) in the revision group and 61 cases (32%) of primary cases and on the trochlea in 3 cases in the revision group (10%) and 31 cases (16.2%) in the primary group.
Conclusions:
Patients undergoing revision MPFL surgery had a higher BMI, larger TT-TG distance and sulcus angle, and were more likely to have a J-sign than those undergoing primary surgery. Further work is necessary to characterize the outcomes of these revision procedures.