MRI-associated classification to evaluate the outcome after autologous reconstruction of the medial patellofemoral ligament: a preliminary study

Classification and Reconstruction of Biomedical Signals Based on Convolutional Neural Network

The efficient biological signal processing method can effectively improve the efficiency of researchers to explore the work of life mechanism, so as to better reveal the relationship between physiological structure and function, thus promoting the generation of major biological discoveries; high-precision medical signal analysis strategy can, to a certain extent, share the pressure of doctors’ clinical diagnosis and assist them to formulate more favorable plans for disease prevention and treatment, so as to alleviate patients’ physical and mental pain and improve the overall health level of the society. This article in biomedical signal is very representative of the two types of signals: mammary gland molybdenum target X-ray image (mammography) and the EEG signal as the research object, combined with the deep learning field of CNN; the most representative model is two kinds of biomedical signal classification, and reconstruction methods conducted a series of research: (1) a new classification method of breast masses based on multi-layer CNN is proposed. The method includes a CNN feature representation network for breast masses and a feature decision mechanism that simulates the physician’s diagnosis process. By comparing with the objective classification accuracy of other methods for the identification of benign and malignant breast masses, the method achieved the highest classification accuracy of 97.0% under different values of c and gamma, which further verified the effectiveness of the proposed method in the identification of breast masses based on molybdenum target X-ray images. (2) An EEG signal classification method based on spatiotemporal fusion CNN is proposed. This method includes a multi-channel input classification network focusing on spatial information of EEG signals, a single-channel input classification network focusing on temporal information of EEG signals, and a spatial-temporal fusion strategy. Through comparative experiments on EEG signal classification tasks, the effectiveness of the proposed method was verified from the aspects of objective classification accuracy, number of model parameters, and subjective evaluation of CNN feature representation validity. It can be seen that the method proposed in this paper not only has high accuracy, but also can be well applied to the classification and reconstruction of biomedical signals.

MRI following medial patellofemoral ligament reconstruction: assessment of imaging features found with post-operative pain, arthritis, and graft failure

OBJECTIVE

To assess MR features following MPFL reconstruction and determine their influence on post-operative pain, progressive arthritis, or graft failure.

MATERIALS AND METHODS

Retrospective study on 38 patients with MPFL reconstruction and a post-operative MRI between January 2010 and June 2019. Two radiologists assessed MPFL graft signal, graft thickness, femoral screw, femoral tunnel widening, and patellofemoral cartilage damage. The third performed patellofemoral instability measurements. All three assessed femoral tunnel position with final result determined by majority consensus. Imaging findings were evaluated in the setting of post-operative pain, patellofemoral arthritis, and MPFL graft failure including need for MPFL revision. Statistics included chi-square, Fisher's exact test, t test, and kappa.

RESULTS

Mean graft thickness was 6.0 ± 1.8 mm; 24% of the grafts were diffusely hypointense. Mean femoral tunnel widening was 2.5 ± 1.8 mm; 34% of the femoral screws were broken or extruded. Fifty-two percent of the patients had no interval cartilage change. Non-anatomic femoral tunnels were found in 66% of patients, including in all 9 patients requiring revision MPFL reconstruction (p = 0.013). Revised MPFL grafts had more abnormal femoral screws compared to those that did not (67% vs. 24%) (p = 0.019). Other MR features did not significantly influence the evaluated outcomes.

CONCLUSION

The need for revision MPFL reconstruction occurs more frequently when there is a non-anatomic femoral tunnel and broken or extruded femoral screws. The appearance of the MPFL graft itself is not an influencing factor for post-operative pain, progression of patellofemoral arthritis, or graft failure.

Does patella alta lead to worse clinical outcome in patients who undergo isolated medial patellofemoral ligament reconstruction? A systematic review

INTRODUCTION

The aim of this systematic review is to determine the effect of patella height on clinical outcomes after isolated MPFL reconstruction for patella instability. Our primary hypothesis is that patients with patella alta report similar outcomes after isolated MPFL reconstruction compared to patients with normal patella height.

METHODS

A review of the literature was performed according to the PRISMA guidelines. PubMed, EMBASE, and the Cochrane Library were searched from inception to January 10th 2018. Studies were identified using synonyms for "medial patellofemoral ligament", "reconstruction" and "patella alta".

RESULTS

The search resulted in 467 reports on PubMed, 175 on EMBASE and 3 on the Cochrane Library. We included and analyzed in detail six studies describing outcomes after isolated medial patellofemoral ligament reconstruction with regard to patellar height. We found that both patients with patella alta and normal patella height reported satisfactory outcomes after isolated medial patellofemoral ligament reconstruction. However, because of applied exclusion criteria in the included studies the total number of patients with severe patella alta was small (13/74 patients with patella alta, 18%).

CONCLUSIONS

Based on the current literature we suggest that additional tibial tubercle distalisation is not mandatory in patients with mild patella alta (Caton-Deschamps Index 1.2-1.4). To assess the best indications for different surgical procedures for patients with patella instability future research is needed to develop a clear and uniform definition of relevant patella alta.

LEVEL OF EVIDENCE

III.

Femoral tunnel widening is associated with tunnel malposition but not with clinical failure after medial patellofemoral ligament reconstruction with a free gracilis tendon graft

INTRODUCTION

MPFL reconstruction is widely and successfully used for treating patella instability, either as a standalone procedure or in combination. Although different techniques allow for MPFL reconstruction, the use of a free tendon graft is one of the most commonly used. The phenomenon of tunnel widening or tunnel enlargement is well described in ACL reconstruction, but so far only little effort has been put into evaluating this phenomenon after MPFL reconstruction.

MATERIALS AND METHODS

Patients who received an MPFL reconstruction with a free gracilis tendon graft were identified by review of patient files. Additional clinical examination and magnetic resonance imaging were performed to assess tunnel enlargement and clinical outcome.

RESULTS

Fifty-one knees of 49 patients (34 female, 17 male) with a mean follow-up of 3.0 ± 1.4 years were included in this study. Mean age at the time of surgery was 22.6 ± 8.5 years. Mean Tegner score decreased from preoperative 5.3 ± 2.0 to 4.0 ± 1.4 postoperative. Postoperative IKDC and Kujala scores were 74 ± 16 and 80 ± 15, respectively. Twenty-three patients showed a tunnel enlargement at follow-up examination. Of these 23 patients, 20 showed a tunnel that was positioned too proximal, whereas only 13 of the 28 patients showing no enlargement had a tunnel that was positioned too proximal (p = 0.0033). Interestingly, patients showing a tunnel enlargement at follow-up examination also showed significantly better Kujala (84 ± 12 vs. 75 ± 16; p = 0.03) and IKDC scores (80 ± 7 vs. 70 ± 19; p = 0.02) when compared to the non-enlarged group.

CONCLUSION

Tunnel enlargement after MPFL reconstruction with a free gracilis tendon graft seems to be connected to mechanical overload due to a proximal malposition of the femoral tunnel. Interestingly, this did not influence clinical outcome as patients with tunnel enlargement showed better Kujala and IKDC scores.