Posterior tibial tubercle measured by the sagittal TT-TG distance correlates with increased risk for patellofemoral chondral lesions

Abstract

Purpose To evaluate the variation in tibial tubercle sagittal alignment in patients with and without patellofemoral (PF) cartilage wear. Methods This was a single-centre, retrospective review of patients that underwent a cartilage restoration procedure for isolated PF cartilage wear from 2014 to 2020. Patients were matched in a 1:2 ratio for age, sex and BMI to partial meniscectomy patients as controls. The sagittal TT-TG (sTT-TG) distance was measured on preoperative axial T2 magnetic resonance imaging (MRI) and was deined as the distance between a point at the nadir of the trochlear cartilage and the most anterior point of the tibial tubercle. Results One hundred and forty patients (47 cartilage restoration, 94 meniscectomy) were included. Mean age, BMI, and height for the total cohort were 34.01 ± 8.7, 26.6 ± 6.4, and 173.0 ± 17.7 respectively, with 78 males (55%) and 63 females (45%). There were no signiicant diferences between groups for age, BMI or sex (n.s). The cartilage restoration group (− 2.5 mm ± 5.9) was found to have a signiicantly more posterior (negative) sTT-TG compared to the meniscectomy group (1.72 mm ± 6.7) (p < 0.001). Interrater reliability was excellent (ICC = 0.931, p < 0.001). Patients with less than − 3.4 mm sTT-TG were 2.74 times more likely to have a cartilage restoration procedure compared to those with greater than − 3.4 mm (OR 2.7, 95% CI 1.3-5.85). Patients with < − 10 mm posterior translation were 13.7× (CI 1.6-111.1) more likely to have a cartilage restoration procedure. Conclusion Patients that underwent isolated cartilage restoration procedures had a signiicantly more posterior tibial tubercle than partial meniscectomy controls based on the sagittal TT-TG. The more posterior the tubercle, the more likely the patient had a cartilage restoration procedure. Surgeons should consider the sTT-TG measurement in patients presenting with anterior knee pain, particularly patellofemoral lesions. Level of evidence III.

Risk Factors for Atraumatic Medial Patellar Facet Lesions

“…We found that a more posterior tibial tubercle relative to trochlear groove was a risk factor for atraumatic medial patellar facet lesions, which is in line with previous investigations that demonstrated an increased risk for patellofemoral chondral lesions in patients with a more posterior tibial tubercle relative to the trochlear groove. 16,17 Given the high rates of patellofemoral osteoarthritis following the posteromedializing Hauser procedure, 4 a more posterior tibial tubercle relative to the trochlear groove may be associated with patellar overload, which could explain the preponderance for atraumatic medial patellar facet lesions in patients with a relatively posteriorized tibial tubercle. Although medial trochlear facet hypoplasia is associated with trochlear dysplasia, 8 and thus patellar instability, 9 the converse (medial trochlear facet hypertrophy) has not been described previously in the literature as a risk factor for medial patellar facet chondral lesions.…”

“… 11 , 17 Several recent studies have demonstrated that sagittal TT-TG distance (also referred to as tibial tubercle height) is a significant risk factor for the development of isolated atraumatic patellofemoral cartilage lesions. 16 , 17 , 27 These studies suggest that a more posterior position of the tibial tubercle relative to the trochlear groove may predispose patients to the development of patellofemoral cartilage lesions in the absence of trauma or instability.…”

“…12,28 In the majority of cases, patellar chondral lesions secondary to patellofemoral instability are linked to a number of predisposing anatomic factors, including patella alta, torsional malalignment (ie, increased axial tibial tubercle-trochlear groove [TT-TG] distance), trochlear dysplasia, and ligamentous laxity. 2,13,15,16,25,27 In these patients, optimal treatment typically involves an anteromedializing tibial tubercle osteotomy (AMZ TTO) in combination with patellofemoral cartilage restoration procedures. 13,14,17,21 Underlying anatomic abnormalities must be addressed in these patients not only to prevent recurrent instability but also to decrease contact pressure on the patella.…”

Magnetic resonance imaging is able to detect patellofemoral focal cartilage injuries: a systematic review with meta-analysis

“…Magnetic resonance imaging (MRI) plays a major role in the early diagnosis of PF joint disorders [1, 6, 9, 22, 33, 51, 59]. Cartilage injuries are often present and it is thus a cornerstone to know how reliable and accurate it is for detecting and grading PF cartilage defects.…”