Increased TT–TG distance caused by excessive tibiofemoral rotation predicts poor clinical outcomes after tibial tubercle osteotomy in recurrent patellar dislocation

Zhang, Zhi‐jun; Feng, Zheng; Di, Menglinqian; Cao, Yan‐wei; Zheng, Tong; Zhang, Hui

doi:10.1007/s00167-023-07587-6

Cited by 5 publications

(1 citation statement)

References 42 publications

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“…A recent study also found that patients with unaddressed femoral torsion >30°, where MPFL and a TTO were performed, have lower clinical outcomes than patients with less torsion [ 36 ]. In light of these findings, it might be advisable to systematically assess torsion in addition to TT‐TG and correct at the morphologically most altered bone [ 56 ].…”

Section: Discussionmentioning

confidence: 99%

Promising results following derotational femoral osteotomy in patellofemoral instability with increased femoral anteversion: A systematic review on current indications, outcomes and complication rate

Klasan,

Compagnoni,

Grassi

et al. 2024

J. exp. orthop.

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PurposePatellofemoral joint instability (PFJI) can surgically be treated with a multitude of approaches, depending on the underlying pathology. In the presence of increased femoral anteversion, some authors have reported good results with a derotational distal femoral osteotomy (DeDFO). The purpose of the study was to investigate the indications, outcomes and complication rate of DeDFO for PFJI.MethodsA systematic review was performed according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta‐analyses) by searching Medline, Embase, Web of Science and Cochrane Library databases through 1 December 2023. Included were levels 1–4 clinical studies of skeletally mature patients undergoing a DeDFO for PFJI irrespective of concomitant procedures. Study characteristics, indications, radiological and clinical outcomes, surgical technique and concomitant procedures, re‐dislocation and complication rate were all analysed, as was methodological quality.ResultsA total of 12 studies including 310 patients (325 knees) were included. Three studies were cohort studies, all others were case series. The mean patient age across the studies was 22 years, and the mean follow‐up was 29.4 months. Femoral anteversion cut‐off was between 20° and 30°. Every study included at least one concurrent soft tissue, bony or combined procedure. Across all studies, one case of re‐dislocation was reported (0.3%) and four implant or osteotomy‐related complications (1.2%) were reported. All studies reported a statistically significant increase in clinical scores.ConclusionThis systematic review of DeDFO for patellofemoral instability in the presence of increased femoral anteversion demonstrates promising clinical results and an extremely low dislocation and complication rate. The heterogeneity of the cut‐off in anteversion and concomitant procedures, especially tibial tubercle osteotomy with seemingly identical results, indicates the need for high‐quality evidence for treating patellofemoral instability. Based upon this systematic review, we strongly recommend that DeDFO be added to the ‘menu à la carte’ of PFJI.Level of EvidenceLevel III Systematic Review.

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Section: Discussionmentioning

confidence: 99%

Promising results following derotational femoral osteotomy in patellofemoral instability with increased femoral anteversion: A systematic review on current indications, outcomes and complication rate

Klasan,

Compagnoni,

Grassi

et al. 2024

J. exp. orthop.

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Habitual patellar dislocation exhibits less severe rotational deformities but poorer trochlear development and higher incidence of patella baja compared with recurrent patellar dislocation in skeletally mature patients

Zhang,

Feng,

et al. 2024

Knee surg. sports traumatol. arthrosc.

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PurposeThis study compared the radiological characteristics between habitual and recurrent patellar dislocation in skeletally mature patients.MethodsFrom 2017 to 2019, 77 skeletally mature patients with habitual patellar dislocation were surgically treated at a single institution and reviewed retrospectively. A total of 55 knees from these patients were included in the habitual patellar dislocation group. During the same period, 55 knees with recurrent patellar dislocation were randomly selected from 242 patients and included in the recurrent patellar dislocation group. Various bony deformities were measured and compared between the two groups. Additionally, a subgroup analysis was conducted among patients with habitual patellar dislocation, comparing those with and without an ‘invisible patella’ observed on true lateral views with 30° of knee flexion.ResultsThe femoral anteversion angle (21.8° vs. 26.3°, p = 0.041), tibiofemoral rotation angle (9.7° vs. 12.4°, p = 0.042) and external tibial rotation angle (24.3° vs. 29.6°, p = 0.001) in the habitual patellar dislocation group were significantly lower than those in the recurrent patellar dislocation group. 54% of knees in the habitual patellar dislocation group had a patella baja, and this was in sharp contrast to the recurrent patellar dislocation group in which none of the knees had a patella baja. 49.1% of knees in the habitual patellar dislocation group showed ‘invisible patella’ at 30° of knee flexion, and knees with ‘invisible patella’ had significantly higher tibial tubercle‐trochlear groove (TT‐TG) distance (30.4 vs. 19.8, p < 0.001) and tibiofemoral rotation angle (13.2° vs. 6.4°, p < 0.001) than knees with a visible patella.ConclusionsA distinct difference in bony anatomical features was observed between habitual and recurrent patellar dislocation in skeletally mature patients. Habitual patellar dislocation exhibited less severe rotational deformities of the lower extremity but showed poorer trochlear and patellar development, a larger TT‐TG distance and a higher incidence of patella baja compared with recurrent patellar dislocation.Level of EvidenceLevel III.

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Femoral anteversion angle is more advantageous than TT‐TG distance in evaluating patellar dislocation: A retrospective cohort study

Chen,

Ma,

et al. 2024

Knee surg. sports traumatol. arthrosc.

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PurposeThe purpose of this study is to report the parameter characteristics of the femoral anteversion angle (FAA) and tibial tubercle–trochlear groove (TT‐TG) distance in patients with patellar instability compared to healthy individuals and to evaluate their reliability in predicting patellar dislocation, providing potential indications for osteotomy.MethodsA retrospective collection of consecutive patients with patellar instability constituted the study group, while individuals without patellofemoral disorder served as the control group. Measurement of the FAA and TT‐TG distance were conducted by lower extremity computed tomography scans and knees with true patellar dislocation were recorded. The diagnostic capability of the FAA and TT‐TG distance was assessed using receiver operating characteristic curves and area under the curve (AUC), determining the pathological values by sensitivity and specificity.ResultsThe FAA (21.6 ± 9.0°) and TT‐TG distance (20.1 ± 4.8 mm) in the study group were significantly greater than the control group (10.6 ± 7.9° and 15.6 ± 4.6 mm, respectively) (p < 0.001). The AUCs for patellar dislocation were 0.869 for FAA and 0.712 for TT‐TG distance, with pathological cut‐off values of 18.2° and 18.2 mm, respectively. The odds ratios for FAA and TT‐TG distance were 1.185 and 1.125, respectively (p < 0.05).ConclusionsPatients with patellar instability exhibited significantly greater FAA and TT‐TG distance compared to healthy individuals. The FAA demonstrated superior predictive capability for patellar dislocation compared to the TT‐TG distance. The FAA (>18.2°) measured by surgical transepicondylar axis and TT‐TG distance (>18.2 mm) were the potential pathological thresholds. Additionally, an increase of 1° in FAA and 1 mm in TT‐TG distance was associated with a 18.5% and 12.5% increased risk of patellar dislocation, respectively. Surgeons should be aware of the risk of patellar dislocation associated with rotational malalignment.Level of EvidenceLevel III.

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Increased TT–TG distance caused by excessive tibiofemoral rotation predicts poor clinical outcomes after tibial tubercle osteotomy in recurrent patellar dislocation

Cited by 5 publications

References 42 publications

Promising results following derotational femoral osteotomy in patellofemoral instability with increased femoral anteversion: A systematic review on current indications, outcomes and complication rate

Promising results following derotational femoral osteotomy in patellofemoral instability with increased femoral anteversion: A systematic review on current indications, outcomes and complication rate

Habitual patellar dislocation exhibits less severe rotational deformities but poorer trochlear development and higher incidence of patella baja compared with recurrent patellar dislocation in skeletally mature patients

Femoral anteversion angle is more advantageous than TT‐TG distance in evaluating patellar dislocation: A retrospective cohort study

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