Relationship between bony tunnel and knee function in patients after patellar dislocation triple surgeries-a CT-based study

The Effects of Inaccurate Femoral Tunnel Placement During Medial Patellofemoral Ligament Reconstruction on Midterm Clinical Outcomes in Treatment of Recurrent Patellar Dislocation

BACKGROUND

There is a lack of evidence and continuous debate on whether femoral tunnel displacement substantially influences the clinical efficacy of medial patellofemoral ligament reconstruction (MPFL-R) in addressing recurrent patellar dislocation.

PURPOSE

To investigate possible associations between inaccurate femoral tunnel placement during MPFL-R and clinical outcomes, with a specific focus on proximal tunnel malpositioning.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who were diagnosed with recurrent patellar dislocation and underwent MPFL-R were retrospectively analyzed. A true lateral view on 3-dimensional computed tomography was obtained, and the distance from the center of the femoral tunnel to the Schöttle point (DF-to-S) was measured. Accordingly, femoral tunnels were divided into the suboptimal group (DF-to-S > 10 mm) and the optimal group (DF-to-S≤ 10 mm). Patient data were collected and pathoanatomic risk factors were evaluated. Clinical assessments included patient-reported outcome measures, including the International Knee Documentation Committee (IKDC), Kujala, Lysholm, and Tegner scores; subjective satisfaction; and postoperative complications. A subgroup analysis was performed between proximally malpositioned tunnels and tunnels lying in other directions.

RESULTS

A total of 112 patients (112 knees) were included, with 34 in the suboptimal group and 78 in the optimal group. Patient characteristics and pathoanatomic abnormalities were comparable between the 2 arms, with mean follow-ups of 52.90 ± 23.80 months and 60.14 ± 27.88 months in the suboptimal and optimal groups, respectively (P = .259). At the final follow-up, inferior IKDC (76.3 ± 12.8 vs 85.9 ± 6.3; P < .001), Kujala (87.7 ± 9.3 vs 93.8 ± 4.9; P = .001), and Lysholm (87.0 ± 11.8 vs 94.5 ± 5.3; P = .001) scores and subjective satisfaction (8.2 ± 1.4 vs 9.3 ± 0.9; P < .001) were observed in the suboptimal group compared with the optimal group. Lower proportions of patients met the minimal clinically important difference for the IKDC (82.4% vs 100.0%; P = .001) and Lysholm (79.4% vs 98.7%; P = .001) scores in the suboptimal group compared with the optimal group. Subgroup analysis demonstrated that the final IKDC (P = .002), Kujala (P = .001), and Lysholm (P = .001) scores and subjective satisfaction (P = .031) were statistically worse in the proximally located group, with insignificant improvements compared with preoperative levels. The suboptimal group showed a higher rate of overall complications, and anterior knee pain was more often reported in the proximally located subgroup.

CONCLUSION

Inaccurate femoral tunnel positioning was associated with inferior midterm subjective functional scores and a higher rate of postoperative complications after MPFL-R. Proximal displacement in particular was associated with adverse clinical outcomes.

Does medial patellofemoral ligament reconstruction result in femoral tunnel enlargement? A systematic review

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is a common surgical procedure for treating patellar instability. The primary aim of this systematic review was to determine whether MPFL reconstruction (MPFLR) leads to femoral tunnel enlargement (FTE). The secondary aims were to explore the clinical effects and risk factors of FTE. Electronic databases (MEDLINE, Global Health, Embase), currently registered studies, conference proceedings and the reference lists of included studies were searched independently by three reviewers. There were no constraints based on language or publication status. Study quality assessment was conducted. 3824 records were screened in the initial search. Seven studies satisfied the inclusion criteria, evaluating 380 knees in 365 patients. Rates of FTE following MPFLR ranged from 38.7 to 77.1%. Five low quality studies reported FTE did not lead to detrimental clinical outcomes as assessed with the Tegner, Kujala, IKDC, and Lysholm scores. There is conflicting evidence regarding change in femoral tunnel width over time. Three studies (of which two had a high risk of bias) reported age, BMI, presence of trochlear dysplasia and tibial tubercle-tibial groove distance did not differ between patients with and without FTE, suggesting these are not risk factors for FTE.

CONCLUSION

FTE is a common postoperative event following MPFLR. It does not predispose poor clinical outcomes. Current evidence lacks the ability to identify its risk factors. The reliability of any conclusions drawn is hindered by the low level of evidence of the studies included in this review. Larger prospective studies with long-term follow up are required to reliably ascertain the clinical effects of FTE.

Diagnostic Performance of Multi-Direction Adjusted Multi-Planar Reconstruction with Helical CT for Evaluating Continuity of the Anterior Cruciate Ligament

RATIONALE AND OBJECTIVES

To analyze the diagnostic performance of MDA-MPR with CT for evaluating ACL structural continuity.

METHODS

A total of 145 patients with highly suspected ACL injury admitted to our hospital between January 2016 and May 2021 were retrospectively enrolled. All patients had undergone examination with MRI, CT, and arthroscopy. Taking arthroscopy results as the gold standard, the diagnostic accuracy for identifying ACL rupture by MRI and MDA-MPR with CT were compared.

RESULTS

The receiver operator characteristic curves demonstrated that both MRI and MDA-MPR with CT performed well in the diagnosis of ACL tears. The sensitivities of MRI and MDA-MPR with CT for diagnosing complete ACL tears were 95.16% (59/62) and 90.32% (56/62), respectively. Their specificities in this regard were 77.11% (64/83) and 84.34% (70/83), respectively. MRI had a higher sensitivity but MDA-MPR with CT had a higher specificity for detecting complete ACL tears, and the differences were statistically significant (p <.05). The sensitivities of diagnosing partial ACL tears using MRI and MDA-MPR with CT were 78.79% (26/33) and 75.76% (25/33), respectively, while the specificities were 86.61% (97/112) and 90.18% (101/112), respectively. These differences were non-significant (p >.05).

CONCLUSION

MDA-MPR with CT has high diagnostic efficiency for ACL injuries, especially in the diagnosis of complete ACL tears.

Correlation Analysis between Tibial Tuberosity-Trochlear Groove Distance and Other Patellar Stability Parameters in Young and Middle-aged Populations

OBJECTIVE

The exact mechanism of patellofemoral instability has not been clearly clarified. The current study aims to explore the correlation between the tibial tuberosity-trochlear groove (TT-TG) distance and other patellar stability parameters.

METHODS

A total of 60 individuals aged 18 to 40 years who underwent knee computed tomography (CT) examination between September 2014 and December 2017 were retrospectively recruited. Five reference sites were selected on the femoral trochlear articular surface in every CT image. The TT-TG distance and the trochlear groove angles (TGA) at the five reference sites were measured. The patellar ligament length (PLL), patellar length (PL), medial patellar retinaculum length (MPRL) and lateral patellar retinaculum length (LPRL) were quantitatively analyzed. The TT-TG distances on different knee sides or in different sexes were compared. The relationships between the TT-TG distance and TGA, PLL/PL, MPRL, and LPRL were analyzed by Spearman's method. Comparison analysis among patellar stability parameters was analyzed using ANOVA or two-tailed Student's t test.

RESULTS

Variance analysis revealed no significant differences in the TT-TG distances among the five positions of the femoral trochlea (F = 0.67, P = 0.62) but significant differences among the five femoral TGAs at the five reference sites (F = 380.37, P < 0.01). Notably, an increasing tendency of the TT-TG distance was observed in the sexes (male, range 16.61-19.68 mm; female, range 14.37-17.38 mm) and knee sides (left knee, range 14.37-18.43 mm; right knee, range 15.80-19.68 mm). The TGA at site 1 of the femoral trochlear cartilage was the largest, with an angle of 151.97° ± 10.4°, and then gradually decreased to the smallest when the cartilage disappeared at site 5, with an angle of 92.05° ± 10.01°. Interestingly, there was a positive relationship between the TT-TG distance at site 1 and TGA in the right knees of males (r = 0.490, P = 0.033) as well as LPRL in the left knees of males (r = -0.420; P = 0.046). There were no correlations between the TT-TG distance and the other patellar stability parameters, including TGA, PLL/PL, MPRL, and LPRL.

CONCLUSION

Among young and middle-aged populations, patella surgeries should be carefully determined based on the comprehensive consideration of these patellar stability parameters rather than the TT-TG distance alone. Differences in sex and knee side should also be considered.

Malalignment sign on knee magnetic resonance imaging: a new predictor for excessive femoral anteversion in patients with patellar dislocation

PURPOSE

To evaluate the clinical relevance of the newly identified malalignment sign in predicting excessive femoral anteversion in patients with patellar dislocations.

METHODS

A total of 55 patients with patellar dislocation who underwent surgical treatment between 2016 and 2019 were included in this study. Femoral anteversion, tibial torsion, and the femorotibial index were measured via a CT scan. The malalignment sign on the knee MRI was defined as a malalignment between the lateral side of the intercondylar fossa of the femur and the lateral intercondylar eminence of the tibial plateau.

RESULTS

A positive malalignment sign was observed in 36 of the 55 patients. Increased femoral anteversion was significantly correlated with the number of frames with a positive malalignment sign (r = 0.511, P < 0.001). The value of femoral anteversion was significantly greater in the group with a positive malalignment sign (P = 0.02). For a femoral anteversion value of 32°, the sensitivity and specificity of the malalignment sign reached the maximal level of 89.5% and 47.2%, respectively.

CONCLUSION

Increased femoral anteversion correlated significantly with a positive malalignment sign on knee MRI. However, tibial torsion did not affect the malalignment sign. A positive malalignment sign is evidence for femoral derotation osteotomy.

LEVEL OF EVIDENCE

Level IV.