Radiological evaluation of patellofemoral instability and possible causes of assessment errors

Patellofemoral instability(PI)is the disruption of the patella’s relationship with the trochlear groove as a result of abnormal movement of the patella.To identify the presence of PI,conventional radiographs(anteroposterior,lateral,and axial or skyline views),magnetic resonance imaging,and computed tomography are used.In this study,we examined four main instability factors:Trochlear dysplasia,patella alta,tibial tuberosity–trochlear groove distance,and patellar tilt.We also briefly review some of the other assessment methods used in the quantitative and qualitative assessment of the patellofemoral joint,such as patellar size and shape,lateral trochlear inclination,trochlear depth,trochlear angle,and sulcus angle,in cases of PI.In addition,we reviewed the evaluation of coronal alignment,femoral anteversion,and tibial torsion.Possible causes of error that can be made when evaluating these factors are examined.PI is a multi-factorial problem.Many problems affecting bone structure and muscles morphologically and functionally can cause this condition.It is necessary to understand normal anatomy and biomechanics to make more accurate radiological measurements and to identify causes.Knowing the possible causes of measurement errors that may occur during radiological measurements and avoiding these pitfalls can provide a more reliable road map for treatment.This determines whether the disease will be treated medically and with rehabilitation or surgery without causing further complications.

Radiological evaluation of patellofemoral instability and possible causes of assessment errors:Letter to the editor

This letter to the editor is a commentary on the study titled"Radiological evaluation of patellofemoral instability and possible causes of assessment errors".There are some pertinent structural changes and radiological findings that should be considered in the setting of traumatic knee injuries,as their recognition is of paramount importance.

Deepening trochleoplasty combined with balanced medial patellofemoral ligament reconstruction for an adequate graft tensioning

AIM To evaluate our modified deepening trochleoplasty com-bined with a balanced medial patellofemoral ligament(MPFL) reconstruction for soft tissue alignement. METHODS Thirty-three knees with with recurrent patellar dislocations and a trochlear dysplasia in 30 patients(m/f = 12/21, mean age 24 ± 9 years) underwent a combination of a modified deepening trochleoplasty and a balanced MPFL reconstruction for a medial soft tissue alignement. After a mean follow-up period of 29 ± 23 mo, patients' return to sports, possible complications as well as the clinical outcomes using the Kujala, International Knee Documentation Committee(IKDC) and Lysholm scoring were evaluated. Moreover, patients' satisfaction with the general outcome, the cosmetic outcome, the pre-and postoperative pain and a potential avoidance behaviour were assessed with additional standardized questionnaires which also included different visual analog scales. RESULTS There were no signs of a persistent instability. The Kujala score improved from a mean of 64 ± 16 points to 94 ± 9 points, the Lysholm score improved from a mean of 63 ± 17 to 95 ± 6 points and the IKDC score from 58 ± 11 to 85 ± 12 points, P < 0.0001, respectively. The assessment of pain using a visual analog scale showed a significant pain reduction from a mean of 4.8 ± 2.0 to 1.3 ± 3.4 points(P < 0.0001). Two of 26 cases(92%) who were engaged in regular physical activity before surgery did not return to full sporting activities. One patient felt that his sport was too risky for his knee and reported an ongoing avoidance behaviour. The other patient preferred to wait for surgery of her contralateral knee. Of the eight patients who were not engaged in sporting activities before surgery, three started regular sporting activities after surgery. In 31 of the 33 cases(94%), the patients were very satisfied with the clinical outcome of the surgery. Regarding the cosmetic results, no patients felt impaired in their self-confidence and in their clothing decisions. CONCLUSION Our technique shows a good clinical outcome in terms of the common scorings as well as in terms of pain, return to sports and patient satisfaction.

Interference screws vs.suture anchors for isolated medial patellofemoral ligament femoral fixation:A systematic review

Purpose:The present study aimed to systematically review and compare 2 femoral autograft fixation techniques,namely,interference screws and suture anchors,for isolated medial patellofemoral ligament reconstruction in patients with recurrent patellofemoral instability at mid-to long-term follow-up.Methods:A literature search was performed in September 2020.All studies reporting the outcomes of primary isolated medial patellofemoral ligament reconstruction for recurrent patellofemoral instability were considered for inclusion.Only studies reporting the type of femoral autograft fixation under examination were considered.Studies reporting data from patients with elevated tibial tuberosity-tibial groove,patella alta,and/or Dejour’s trochlear dysplasia types C and D,were not included.Only articles reporting data with a minimum follow-up period of 18 months were considered.Results:Data from 19 studies(615 patients)were retrieved.The overall age was 24.4±6.7 years(mean±SD).The mean follow-up was 46.5±20.9 months.There were 76 patients in the anchor group and 539 in the screw group.Comparability was found with regard to age and follow-up duration between the 2 study groups.There was comparability between the Kujala,Lysholm,and Tegner scores at baseline.At the last follow-up,no worthy differences were found in terms of mean Kujala(+2.1%;p=0.04),Lysholm(+1.7%;p=0.05),and Tegner(+15.8%;p=0.05)scores.Although complications occurred almost exclusively in the screw cohort,no statistically significant difference was found.Conclusion:Femoral autograft fixation through interference screws or suture anchors report similar clinical scores and rate of apprehension test,persistent joint instability,re-dislocations,and revisions.These results must be interpreted within the limitations of the present study.