Outcomes After Derotational Distal Femoral Osteotomy for Recurrent Patellar Dislocations With Increased Femoral Anteversion: A Systematic Review and Meta-analysis

Femoral inherent torsion is more accurate than femoral anteversion angle in evaluating femoral torsion to determine whether combine derotational distal femoral osteotomy or not

BACKGROUND

Previous view is that femoral anteversion angle (FAA) is equivalent to femoral torsion (FT) and as an indication for derotational distal femoral osteotomy (DDFO) combined with medial patellofemoral ligament reconstruction (MPFLR), but posterior femoral condylar deformity affects FAA. Therefore, FAA is not accurate in assessing FT. Whether the femoral inherent torsion (FIT), which avoids the influence of the posterior condyle, can better reflect FT during surgery remains unknown. Meanwhile, the impact of the posterior femoral condyle on surgical outcomes remains unclear.

METHODS

Twenty-five patellar dislocation (PD) patients from 2017 to 2021 were conducted. All patients underwent both preoperative and postoperative computed tomography scans. Categorized by posterior condylar angle (PCA), they were divided into Group A (PCA ≤ 6.4°) and Group B (PCA > 6.4°). Radiographic measurements included FAA, femoral inherent torsion (FIT), patellar tilt angle, congruence angle and tibial tubercle-trochlear groove distance. For clinical outcomes, the Kujula score, Lysholm score, IKDC score to reflect the knee function. The Tegner activity score was used to assess the activity level. The VAS score was used to assess the pain control.

RESULTS

In both groups, the postoperative radiographic outcomes demonstrated a statistically significant improvement. Preoperatively, the FAA was similar in the two groups, but the FIT was greater in the Group A (21.7° ± 1.2° vs 18.4° ± 1 .3°, P < 0.001). However, there was no statistically significant difference between them in the postoperative period (7.4° ± 1.5° vs 7.1° ± 1.8°). In terms of clinical outcomes, both groups demonstrated a significant improvement in the postoperative period. However, the scores of the Group A significantly better (Kujula: 85.7 ± 5.0 vs 79.6 ± 4.8, P = 0.005; Lysholm: 86.8 ± 5.3 vs 80.2 ± 5.7, P = 0.006; IKDC: 86.1 ± 8.8 vs 75.5 ± 7.6, P = 0.004).

CONCLUSION

FIT may be a more reliable indicator than FAA for evaluating FT in PD to determine whether combine DDFO or not, especially in the presence of posterior femoral condylar deformity. Posterior femoral condylar deformity appeared to result in a pseudo-increase in FAA. Simultaneous evaluation of FIT and FAA to identify true posterior condylar deformity offers the potential to prevent enlargement of DDFO and enable precision treatment.

The efficacy of medial patellofemoral ligament reconstruction combined with distal femoral varus osteotomy in recurrent patellar dislocation and genu valgum

Medial patellofemoral ligament (MPFL) reconstruction is a widely recognized treatment for recurrent patellar dislocation. However, limited research addresses the outcomes of combining MPFL reconstruction with distal femoral varus osteotomy, particularly in patients with genu valgum. This study aims to evaluate the clinical outcomes of this combined surgical approach in individuals experiencing recurrent patellar dislocation associated with genu valgum. A systematic review followed PRISMA guidelines by searching the PubMed, Scopus, and Cochrane Library databases through July 1, 2024. Studies included patients whose MPFL reconstruction was combined with distal femoral varus osteotomy to treat recurrent patellar dislocation and genu valgum. A meta-analysis was performed to evaluate pain, clinical and functional outcomes, with data reported as mean difference (MD) and 95% confidence interval (CI). A total of three studies with 58 knees were included. Most of the patients were female 62.5%, with a mean patient age of 20.5 years and a mean follow-up of 26.4 months. The mean preoperative mechanical leg axis was 6.8° of valgus. After MPFL reconstruction with distal femoral varus osteotomy significant improvements were found in the Kujala score (MD, 33.64 [95% CI 31.3-35.99]), Lysholm score (MD, 34.89 [95% CI 23.27-46.51]), visual analog scale score for pain (MD, - 3.99 [95% CI - 5.66 to - 2.31]), and Tegner Activity Score (MD, 1.96 [95% CI 1.63-2.29]). No subluxation or redislocation occurred in any study during the follow-up period, and all reported radiological correction of genu valgum. Combined medial patellofemoral ligament reconstruction and distal femoral varus osteotomy in patients with recurrent patellar dislocation and genu valgum lead to significant improvements in clinical outcomes, such as pain relief and functional scores, as well as effective radiological correction of valgus deformity. However, further high-quality studies are needed to confirm these findings and establish stronger evidence for this combined approach. Systematic review and meta-analysis, level IV.

Radiological assessment of lower limb torsional deformities: a narrative review

Background and Objective

The evaluation of both femoral and tibial torsional profiles remains a challenge in the orthopedic practice since there is no agreement on the most precise and reliable measurement method and technique. The aim of this review is to collect and critically report the most relevant and up-to-date evidence on the radiological techniques available to determine lower limb torsional deformities and to discuss the advantages and limitations of each technique to better define their optimal field of application.

Methods

Literature research on PubMed, Embase, and Google Scholar databases was performed, utilizing the following search string: "torsion" AND ("lower limb" OR "femur" OR "tibia"). Relevant clinical and preclinical studies evaluating different radiological techniques to assess lower limb torsional deformities, and possibly comparing them, were collected and critically reviewed.

Key Content and Findings

Computed tomography (CT) is still considered the best method to measure both femoral and tibial torsional angles. Its main limitation, the radiation exposure, has been recently addressed with ultra-low dose protocols that were proven to be as accurate as standard protocols. On the other hand, magnetic resonance imaging (MRI) offers a nonionizing, radiation-free option that is now considered almost equivalent to CT. However, MRI consists in a long and expensive procedure that can be hindered by issues linked to metal implants, patient's positioning and measurement variabilities. Lastly, three-dimensional (3D) reconstructions derived from low-dose biplanar radiographies (LD-BRs) have been proposed as a low-radiating, quick and reliable solution to overcome the limitations of both MRI and CT scans.

Conclusions

To date, CT has still to be considered the gold standard for the radiological assessment of lower limb torsional deformities. Nonetheless, MRI and LD-BR have been proven to be valid and reliable alternatives, especially in specific clinical settings.

Decreased femoral trochlea axial orientation corrected by derotational distal femur osteotomy in patients with patellar dislocation yields satisfactory outcomes

PURPOSE

The femoral trochlea axial orientation has been shown to be a better predictor of patellar dislocation than the femoral anteversion angle. However, no study has investigated the importance of the femoral trochlea axial orientation in the surgical treatment of patellar dislocation. It is aimed to explore the pathological threshold of the femoral trochlea axial orientation and its guiding implications for surgical interventions in the study.

METHODS

Sixty-four patients with patellar dislocation and 64 controls were included for measurement of the femoral trochlea axial orientation. The ability to predict the patellar dislocation and the pathologic threshold of the femoral trochlea axial orientation were evaluated using the receiver operating characteristic curve. One hundred patients with medial patellofemoral ligament reconstruction and 25 patients with derotational distal femur osteotomy were divided into two groups based on the femoral trochlea axial orientation cut-off value and their postoperative knee functions, and patellar tilt angles were compared.

RESULTS

There were significant differences in the femoral trochlea axial orientation (60.8 ± 7.9 vs. 67.8 ± 4.6, p < 0.05) between patients with patellar dislocation and the normal population. The sensitivity and specificity of the femoral trochlea axial orientation were 0.641 and 0.813, respectively, at the femoral trochlea axial orientation smaller than 63.8°. Amongst patients having had isolated medial patellofemoral ligament reconstruction with decreased femoral trochlea axial orientation, knee function was poorer after surgery. The prognosis of patients with the femoral trochlea axial orientation correction in derotational distal femur osteotomy was better than that for patients without correction.

CONCLUSIONS

The femoral trochlea axial orientation had good predictive efficiency for patellar dislocation. Isolated medial patellofemoral ligament reconstruction is not sufficiently effective for patients with patellar dislocation and decreased femoral trochlea axial orientation. Patients with a decreased femoral trochlea axial orientation can have better surgical outcomes after correction by derotational distal femur osteotomy.

LEVEL OF EVIDENCE

Level III.

Derotational distal femoral osteotomy corrects excessive femoral anteversion in patients with patellofemoral instability: A systematic review

PURPOSE

Patellofemoral instability (PFI) is a common condition that can be caused from multiple factors, including lower limb rotational malalignments. Determining precise criteria for performing corrective torsional osteotomy can be a daunting task due to the lack of consensus on normal and excessive values and the limited evidence-based data in the postoperative results. The purpose was to assess the clinical, functional and imaging outcomes following derotational distal femoral osteotomy (DDFO) in patients with PFI and/or anterior knee pain (AKP) associated with lower limb rotational malalignments.

METHODS

Searches were conducted on PubMed, EMBASE and Web of Science databases up to October 2023. Studies reporting outcomes after DDFO in patients with PFI and/or AKP were eligible for the systematic review. The primary outcome was imaging metrics, especially femoral anteversion. Secondary outcomes included the patient-reported outcome measures (PROMs) (clinical and functional). Quantitative synthesis involved the use of weighted averages to calculate pre- to postoperative mean differences (MD) and compare them against the minimal clinically important difference (MCID).

RESULTS

Ten studies (309 knees) were included with a mean follow-up of 36.1 ± 11.7 months. Imaging outcomes consistently indicated the correction of femoral anteversion (MD = -19.4 degrees, 95% confidence interval: -20.1 to -18.7) following DDFO. PROMs showed significant improvements in most studies, exceeding the MCID. Patient satisfaction with the DDFO was high (93.3%).

CONCLUSIONS

The DDFO was an effective treatment option for correcting excessive femoral anteversion in patients with PFI associated with clinically relevant functional and clinical improvement and a high satisfaction rate.

LEVEL OF EVIDENCE

Level IV, systematic review of level II-IV studies.

Clinical outcomes of derotational femoral osteotomy combined with medial patellofemoral ligament reconstruction in patients with patellar dislocation and increased femoral anteversion unaffected by the pattern of distribution of femoral torsion

PURPOSE

The aim of this study was to evaluate the clinical effect of derotational femoral osteotomy combined with medial patellofemoral ligament reconstruction for patellar dislocation and the effect of the distribution of femoral torsion at different segments on postoperative function.

METHODS

Forty-two patients with patellar dislocation who underwent derotational femoral osteotomy from 2017 to 2021 were retrospectively analysed. All patients received computed tomography scans from the hip to the knee to evaluate correction of the femoral anteversion (FA) angle, patellar tilt angle (PTA) and congruence angle (CA) after derotational femoral osteotomy. Subjective scores, such as the Kujala, Lysholm, International Knee Documentation Committee (IKDC), Tegner and visual analog scale (VAS) scores, were used to evaluate knee function before and after the operation. Patients with supracondylar torsion > distal torsion were categorized into the supracondylar torsion group and patients with distal torsion > supracondylar torsion were categorized into the distal torsion group. Subgroup analyses were performed.

RESULTS

No presentation of redislocation occurred in these patients at the minimum 2-year follow-up visit. The mean preoperative FA angle in the supracondylar torsion group was 30.2° ± 4.2°, and the mean postoperative FA angle was 14.5° ± 2.5° (p < 0.001). The mean preoperative FA angle was 26.7° ± 1.4° and the mean postoperative FA angle was 14.1° ± 1.4° in the distal torsion group. In addition, postoperative PTA and CA were significantly corrected in both groups (p < 0.001). The postoperative Kujala, Lysholm, IKDC, Tegner and VAS scores were significantly improved in both groups (p < 0.001). Subgroup analyses showed a higher preoperative FA in the supracondylar torsion group and a higher occurrence of high-grade trochlear dysplasia in the distal torsion group. However, there was no significant difference in their postoperative clinical outcomes.

CONCLUSION

Through a minimum of 2-year follow-up visits of patients with patellar dislocation and increased FA, it was found that derotational femoral osteotomy could significantly reduce FA and improve subjective knee function. The pattern of torsion distribution did not significantly affect the clinical outcomes of derotational femoral osteotomy. These findings readvised orthopaedic surgeons that derotational femoral osteotomy remains the preferred procedure for correcting rotational malalignment, but that they should be more cautious about its indications.

LEVEL OF EVIDENCE

Level IV.