The influence of subchondral vascularisation on chondromalacia patellae

Relation of the chondromalatia patellae to proximal tibial anatomical parameters, assessed with MRI

Background Magnetic resonance imaging (MRI) is a non-invasive highly sensitive tool for diagnosing chondromalacia patellae in the early stages. Many studies have evaluated patellar and trochlear morphology with different radiologic indices. We aimed to assess the discriminative power of tibial, patellar, and femoral indices in MRI for chondromalacia patellae. Patients and methods 100 cases of chondromalacia, as well as 100 age-matched controls among the patients who underwent knee MRI between February 2017 and March 2019, were included. The standard protocol of knee MRI was applied and the diagnosis of chondromalacia was made on MRI findings. Chondromalacia subjects were also classified as grade 1 to 4 according to the Modified Outerbridge's MRI grading system. We measured 25 MRI parameters in the knee and adjacent structures to determine the relation between chondromalacia patellae and anatomical MRI parameters. Results Tibial slope, trochlear depth, lateral trochlear inclination, and lateral patellar tilt angle had significant correlation with chondromalacia. Any increase in lateral trochlear inclination and lateral patellar tilt angle could increase the probability of the disease (Odds ratio [OR] 1.15, 1.13; 95% CI: 1.03-1.30; 1.02-1.26, respectively), while any increase in medial tibial slope and trochlear depth could decrease the probability of chondromalacia (OR 0.85, 0.06; 95% CI: 0.73-0.98, 0.02-0.17, respectively). We also designed a model for the severity of disease by using the patellar height index (relative odds ratio: 75.9). Conclusions The result of this study showed the novelty role of tibial anatomy in developing chondromalacia and its mechanism. We also concluded that patellar height might be an important factor in defining disease severity.

The relationship between early-onset chondromalacia and the position of the patella

Background

There are many underlying accelerator factors for chondromalacia and one of the well-known factors is patellar malalignment.

Purpose

To evaluate the relationship between early-onset chondromalacia and patellar position; and, second, to evaluate the value of patellar malalignment criteria.

Material and Methods

Patients aged 18–40 years with advanced chondromalacia were included. For comparison, a control group was defined with the same number of individuals of the same mean age. The magnetic resonance imaging (MRI) sagittal view with the greatest patellar length was used to obtain the patellar height measurement with the Insall-Salvati index. For the remaining three indices—modified Insall-Salvati, Caton-Deschamps, and Blackburne-Pell—a sagittal view with the greatest patellar articular surface was used. Discordance was defined as contradiction with the measured index and the other three indices.

Results

Both patella alta and baja were found to be predisposing factors for chondromalacia. Modified Insall-Salvati index was the most concordant measurement to define patella alta.

Conclusion

Both patella alta and patella baja were found to predispose to chondromalacia. Patella baja is rare, which may explain why it is not often mentioned as a predisposing factor. The modified Insall-Salvati index ratio was the best patella alta indicator that showed chondral status, more than patellar placement, and was more concordant with the other indices. Blackburne-Pell had the second highest number and ratio of discordance. BP cannot be optimally calculated because deciding the location of the tibial plateau seems to be problematic since it is a three-dimensional and complicated structure.

The Patello-Femoral Joint Degeneration and the Shape of the Patella in the Population Needing an Arthroscopic Procedure

Background: the main goal of the study was to investigate the prevalence of the articular cartilage defects (ACD) in the patellofemoral (PF) region of the knee joint based on the anatomical shapes of patella and its impact on the level of physical activity in the population needing arthroscopic procedures for all types of pathologies in the knee. Methods: The articular cartilage status of the PF region was obtained from 1098 arthroscopic procedures of the knee joint. The ACD were correlated to Wiberg’s shape of the patella and classified according to the degree, size and depth of the ACD in the PF region using the ICRS (International Cartilage Repair Society) system: group I consisting of patients with Wiberg type I shape (W1), group II—patients with Wiberg type II shape (W2) and group III—patients with Wiberg type III shape (W3). The Tegner physical activity scale was used to evaluate the physical activity of the patients. Results: The mean of ACD size (PF region) in the W3 group was 3.10 ± 0.99 cm², which was a statistically significantly larger area in comparison with the W1 (1.90 ± 0.63 cm²; p < 0.0000) and W2 (1.95 ± 0.71 cm²; p < 0.0000). The patients from the W3 group (mean 3.10 ± 0.99) were less physically active (<4 Tegner) compared to the W2 group (mean of 4.48 ± 0.88; p = 0.004) and W1 group (mean of 4.55 ± 0.72; p = 0.002). Conclusions: The patients with the Wiberg type III patella shape had a higher incidence and larger size of ACD in the PF of the knee compared to the groups of Wiberg type I and II. Wiberg III patients with a lower level of physical activity had a larger size of ACD in the PF joint.

Quantitative and qualitative assessment of bone perfusion and arterial contributions in a patellar fracture model using gadolinium-enhanced magnetic resonance imaging: a cadaveric study

BACKGROUND

The purpose of the present study was to evaluate the anatomy and contribution of the patellar vascular supply and to quantify the effect of a transverse fracture on patellar perfusion.

METHODS

In twenty matched pairs of fresh-frozen cadaveric knees, the superficial femoral artery, anterior tibialis artery, and posterior tibialis artery were cannulated. One side of each matched pair was randomly selected to undergo one of two osteotomies: (1) midpatellar osteotomy or (2) distal-pole osteotomy. For volumetric analysis, comparisons were performed between contrast-enhanced magnetic resonance images and precontrast magnetic resonance images as well as between osteotomized patellar bone fragments and the corresponding intact areas on the control side. We then injected a urethane polymer compound and dissected all specimens to examine extraosseous vascularity.

RESULTS

Magnetic resonance imaging demonstrated that the largest arterial contribution to the patella entered at the inferior pole in 100% of the specimens; in 80% of these specimens, the artery entered inferomedially. It also revealed an overall decrease in contrast enhancement in both transverse osteotomy groups, with an average reduction in enhancement in the proximal fragment of 36%.

CONCLUSIONS

If possible, surgical interventions about the knee should be carefully planned to preserve the peripatellar ring (the source of the entire patellar blood supply), especially the inferior patellar network. Distal-pole patellectomy should be avoided to retain vascularized bone at the reduced fracture site.