Nearly two-thirds of patients who undergo isolated MAT have subchondral BML on preoperative MRI. Our findings suggest that increasing BML size (Welsch et al) is correlated with worse postoperative pain measures (KOOS pain, WOMAC pain) and worse activity ratings (Marx Activity Rating Scale). Additionally, increasing disruption or depression of the normal contour of the cortical surface, with or without lesion contiguity with the subjacent articular surface (Costa-Paz et al), is correlated with greater postoperative satisfaction.
PurposeA comprehensive understanding of the biomechanical properties of the medial patellofemoral complex (MPFC) is necessary when performing an MPFC reconstruction. How components of the MPFC change over the course of flexion can influence the surgeon’s choice of location for graft fixation along the extensor mechanism. The purpose of this study was to (1) determine native MPFC length changes throughout a 90° arc using an anatomically based attachment and using Schöttle’s point, and (2) compare native MPFC length changes with different MPFC attachment sites along the extensor mechanism. MethodsEight fresh‐frozen (n = 8), cadaveric knees were dissected of all soft tissue structures except the MPFC. The distance between the femoral footprint (identified through anatomical landmarks and Schottle’s point) and the MPFC was calculated at four attachment sites along the extensor mechanism [midpoint of the patella [MP], the center of the osseous footprint of the MPFC (FC), the superomedial corner of the patella at the quadriceps insertion (SM), and the proximal extent of the MPFC along the quadriceps tendon (QT)] at 0°, 20°, 40°, 60°, and 90° of flexion. ResultsLength changes were investigated between the MPFL femoral attachment site and the radiographic surrogate of the MPFL attachment site, Schottle’s Point (SP). Paired t tests at each of the four components showed no differences in length change from 0° to 90° when comparing SP to the anatomic MPFC insertion. MPFL length changes from 0° to 90° were greatest at the QT point (13.9 ± 3.0 mm) and smallest at the MP point (2.7 ± 4.4 mm). The FC and SM points had a length change of 6.6 ± 4.2 and 9.0 ± 3.8, respectively. Finally, when examining how the length of the MPFC components changed through flexion, the greatest differences were seen at QT where all comparisons were significant (p < 0.01) except when comparing 0° vs 20° (n.s.). ConclusionThe MPFC demonstrates the most significant length changes between 0° and 20° of flexion, while more isometric behavior was seen during 20°–90°. The attachment points along the extensor mechanism demonstrate different length behaviors, where the more proximal components of the MPFC display greater anisometry through the arc of motion. When performing a proximal MPFC reconstruction, surgeons should expect increased length changes compared to reconstructions utilizing distal attachment sites.
Objective. To measure the sagittal alignment of the tibial tubercle through the sagittal tibial tubercle–trochlear groove (sTTTG) distance in patients with and without patellar chondral lesions. Design. Patients treated with patellofemoral cartilage restoration or repair procedures were retrospectively reviewed (group 1; N = 17). A control group of patients (group 2; N = 20) undergoing partial meniscectomy with normal patellar cartilage was included. An asymptomatic patellar chondrosis group (group 3; N = 15) was identified as patients undergoing partial meniscectomy with patellar cartilage wear. The sTTTG was measured on the preoperative axial T2 magnetic resonance imaging (MRI) sequence. The first point was the nadir of the anterior trochlear cartilage, and the second point was the anterior tibial tubercle. A line was drawn between these points, perpendicular to the posterior condylar axis. Comparisons were made between the 3 groups using analysis of variance testing with Bonferroni corrections. Significance was defined as P < 0.05. Results. The mean sTTTG was significantly more posterior in group 1 (5.9 ± 5.5 mm posterior to the trochlear groove) relative to group 2 (0.8 ± 5.3 mm posterior; P = 0.018). The mean value for group 3 (2.7 ± 5.3 mm posterior) fell between group 1 and 3 but was not significantly different from group 1 ( P = 0.31) or group 2 ( P = 0.89). There were no significant differences with regards to sulcus angle, Caton-Deschamps Index, TTTG, or knee flexion angle on the MRI scan. Conclusions. A more posteriorly positioned tibial tubercle was observed in patients with patellar cartilage lesions relative to those with intact patellar cartilage. Intermediate positioning was observed in patients with asymptomatic patellar chondral wear. Level of Evidence. Level 3 diagnostic study.
Objectives:Traumatic joint injury results in an acute inflammatory response. If uncontrolled, this can progress to chronic inflammation, which can expedite the onset of post-traumatic osteoarthritis (PTOA). Normal synovium plays an important protective role for cartilage, while inflamed synovium can lead to degenerative changes. Previous studies have investigated the cartilage-synovium in limited conditions, but the effect of normal synovium on damaged cartilage remains unknown. The purpose of this study is to investigate the effect of normal synovium on two types of damaged cartilage: IL-1β or impaction-induced.Methods:Fresh human tali and distal femoral condyles were obtained from 7 human donors (mean age; 39 years-old, 4 male and 3 female) with no history of joint disease. Gross morphology was assessed using Collins grading 0-4 and only normal joints of grade 0-1 were used. Two damage models were introduced: 1) treatment with IL-1β (10ng/ml) at 48 hours before co-culture; or 2) controlled mechanical impaction (600 N within 2 ms). Cartilage explants (8mm) and grossly normal synovium (8 mm) from both joints were harvested and randomized to one of six treatment groups (n = 5 in each group): non-treated cartilage without or with synovium (Group 1 or 2), IL-1β-treated cartilage without or with synovium (Group 3 or 4), impacted cartilage without or with synovium (Group 5 or 6). Samples were collected at 0, 2, and 14 days and assessed for the percentage of live cells and histology with Safranin O staining. Cell survival was measured using calcein AM and ethidium bromide homodimer-1. Image analysis was performed on the superficial and middle/deep zone. Live cells were counted using Image J. Histological grading was based on modified Mankin score. The level of significance for all analysis was set at P < .05.Results:The percentage of live cells in Group 1 was mostly unchanged, 79.9 - 87.9% in the superficial layer and >90% in the middle/deep layer with no significant differences between Group 1 and 2 (Figure 1). All damaged cartilage displayed elevated cell death, especially in the superficial layer at all time points (Group 3; 56.4 ± 20.0%, 44.5 ± 11.5%, and 57.6 ± 16.3%, Group 5; 14.8 ± 5.3, 12.8 ± 13.2%, and 20.1 ± 4.1%, respectively). In the presence of synovium, chondrocyte survival significantly increased at 2 and 14 days (Group 4; 75.3 ± 4.7% and 77.8 ± 7.8%, P < 0.01 and 0.02, Group 6; 31.8 ± 13.7% and 33.4 ± 14.3%, P = 0.03 and 0.04, respectively). By contrast, the percentage of cells in the middle/deep layer remained unchanged for both damaged cartilage with or without synovium. For histological analysis, non-treated cartilage (Group 1 and 2) had a normal structure through 14 days. Mankin score progressively increased in damaged cartilage (Group 3; 1.0 ± 1.41, 2.2 ± 1.8, and 3.25 ± 1.64, Group 5; 3.0 ± 1.2, 3.6 ± 1.1, and 4.6 ± 0.5 at 0, 2, and 14 days). In the presence of synovium, Mankin score decreased at 2 and 14 days (Group 4; 0.8 ± 1.3, and 0.8 ± 0.8, P = 0.087 and < 0.01, Group 6; 1.0 ± 0.0 and 1.6 ± 0...
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