Anteriorizing Tibial Tubercle Osteotomy for Patellofemoral Cartilage Lesions

Risk Factors for Atraumatic Medial Patellar Facet Lesions

Background

Medial patellar facet lesions have been well-described in the setting of patellar instability. However, relatively little is known about risk factors for atraumatic medial patellar facet lesions.

Purpose/Hypothesis

To identify clinical and radiographic risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability. It was hypothesized that a posterior tibial tubercle relative to the trochlear groove would be a risk factor for atraumatic medial patellar facet lesions.

Study Design

Case-control study; Level of evidence, 3.

Methods

A total of 37 patients with atraumatic medial patellar facet lesions were matched by age, sex, and body mass index with 37 control patients without a history of patellofemoral dysplasia. Demographic and imaging characteristics were compared between groups. Plain radiography was used to evaluate Wiberg type, and magnetic resonance imaging was used to calculate Caton-Deschamps index, tibial tubercle-trochlear groove distance, trochlear facet asymmetry ratio, patellotrochlear index, sulcus depth, patellar bisect ratio, and tibial tubercle height. Statistically significant variables from univariate analysis were used as inputs to the multivariate regression model to assess independent risk factors.

Results

There were no differences between groups with respect to Wiberg type, Caton-Deschamps index, tibial tubercle-trochlear groove distance, sulcus depth, or patellotrochlear index (P > .05 for all). The medial facet lesion group had a larger medial trochlear facet (trochlear facet asymmetry ratio, 0.72 ± 0.11 vs 0.60 ± 0.09; P < .001), a more medial-lying patella in the trochlear groove (patellar bisect ratio, 0.57 ± 0.06 vs 0.55 ± 0.07; P = .035), and a more posterior tibial tubercle relative to the trochlear groove (tibial tubercle height, -3.13 ± 5.21 vs -0.23 ± 5.93 mm; P = .030) compared with the control group. Multivariate regression analysis identified trochlear facet asymmetry and tibial tubercle height as independent risk factors for medial patellar facet lesions (relative risk = 97.3 [95% CI, 14.9-635.1], P < .001 and relative risk = 0.95 [95% CI, 0.92-0.98], P = .004, respectively).

Conclusion

A relatively larger medial trochlear facet and a more posterior tibial tubercle relative to the trochlear groove were found to be risk factors for medial patellar facet lesions in patients without a history of trauma or patellar instability.

Young Age and Concomitant or Prior Bony Realignment Procedures are Associated with Decreased Risk of Failure of Osteochondral Allograft Transplantation in the Knee: A Nationwide Database Study

OBJECTIVE

Osteochondral allograft (OCA) transplantation is a restorative surgical option for large, full-thickness chondral or osteochondral defects in the knee. Variability in outcomes reporting has led to a broad range of graft survival rates. Using rate of salvage surgery following OCA as a failure metric, the purpose of this study was to analyze the incidence and risk factors for failure in a nationwide cohort.

DESIGN

The M151Ortho PearlDiver database was queried for patients aged 20 to 59 who underwent primary OCA between 2010 and 2020. Patients with prior cartilage procedures or arthroplasty were excluded. Kaplan-Meier survival analysis was performed to characterize cumulative rate of salvage surgery, defined as any patient subsequently undergoing revision OCA, autologous chondrocyte implantation (ACI), osteochondral autograft transfer system (OATS), unicompartmental knee arthroplasty (UKA), or total knee arthroplasty (TKA). Multivariable logistic regression was used to determine the effect of several variables on odds of salvage surgery.

RESULTS

Around 6,391 patients met inclusion criteria. Cumulative 5-year salvage rate was 1.71%, with 68.8% in the first 2 years. Age 20 to 29 and concomitant or prior bony realignment procedures were associated with significantly decreased rate of salvage surgery (age-adjusted odds ratio [aOR] = 0.49, 95% confidence interval [CI], 0.24-0.99, P = 0.046; realignment-aOR = 0.24, 95% CI, 0.04-0.75, P = 0.046).

CONCLUSIONS

In the largest OCA cohort studied to date, less than 2% of patients required salvage surgery. Young age and bony realignment were protective. These findings suggest that OCA in the knee is a durable cartilage-restoration procedure, especially in young patients with corrected alignment.

Editorial Commentary: A Posterior Tibial Tubercle Relative to the Trochlear Groove Is Associated With Increased Risk of Patellofemoral Arthritis: The Sagittal Tibial Tubercle-Trochlear Groove Distance

Arthritis of the patellofemoral compartment affects up to 24% of women and 11% of men over the age of 55 years who have symptomatic osteoarthritis of the knee. Patellofemoral cartilage lesions have been associated with several different geometric measures of patellar alignment, including the tibial tubercle-trochlear groove (TTTG) distance, trochlear sulcus angle, trochlear depth, and patellar height. Recently, there has been interest in the sagittal TTTG distance, which measures the position of the tibial tubercle with respect to the trochlear groove. This measurement is now being used in patients presenting with patellofemoral pain and/or cartilage pathology and may help guide surgical decision making as we gain more data on how changing the tibial tubercle alignment relative to the patellofemoral joint can improve outcomes. For now, there are not enough data to support isolated anteriorization tibial tubercle osteotomy in patients with patellofemoral chondral wear based on the sagittal TTTG distance. However, as we better understand geometric measures as risk factors for patellofemoral arthritis, realignment at a young age might be recommended as a preventative measure against end-stage osteoarthritis.

A More Posterior Tibial Tubercle (Decreased Sagittal Tibial Tubercle-Trochlear Groove Distance) Is Significantly Associated With Patellofemoral Joint Degenerative Cartilage Change: A Deep Learning Analysis

PURPOSE

To perform patellofemoral joint (PFJ) geometric measurements on knee magnetic resonance imaging scans and determine their relations with chondral lesions in a multicenter cohort using deep learning.

METHODS

The sagittal tibial tubercle-trochlear groove (sTTTG) distance, tibial tubercle-trochlear groove distance, trochlear sulcus angle, trochlear depth, Caton-Deschamps Index (CDI), and flexion angle were measured by use of deep learning-generated segmentations on a subset of the Osteoarthritis Initiative study with radiologist-graded PFJ cartilage grades (n = 2,461). Kruskal-Wallis H tests were performed to compare differences in PFJ morphology between subjects without PFJ osteoarthritis (OA) and those with PFJ OA. PFJ morphology was correlated with secondary outcomes of mean patellar cartilage thickness and mean patellar cartilage T2 relaxation time using linear regression models controlling for age, sex, and body mass index.

RESULTS

A total of 1,626 knees did not have PFJ OA, whereas 835 knees had PFJ OA. Knees without PFJ OA had an increased (anterior) sTTTG distance (mean ± standard deviation, 11.1 ± 12.8 mm) compared with knees with PFJ OA (8.4 ± 12.7 mm) (P < .001), indicating a more posterior tibial tubercle in subjects with PFJ OA. Knees without PFJ OA had a decreased sulcus angle (127.4° ± 7.1° vs 128.0° ± 8.4°, P = .01) and increased trochlear depth (9.1 ± 1.7 mm vs 9.0 ± 2.0 mm, P = .03) compared with knees with PFJ OA. Decreased patellar cartilage thickness was associated with decreased trochlear depth (β = 0.12, P = .002) and increased CDI (β = -0.07, P < .001). Increased patellar cartilage T2 relaxation time was correlated with decreased sTTTG distance (β = -0.08, P = .01), decreased sulcus angle (β = -0.12, P = .04), and decreased CDI (β = -0.12, P < .001).

CONCLUSIONS

PFJ OA, patellar cartilage thickness, and patellar cartilage T2 relaxation time were shown to be associated with the underlying geometries within the PFJ. This large longitudinal study highlights that a decreased sTTTG distance (i.e., a more posterior tibial tubercle) is significantly associated with PFJ degenerative cartilage change.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic trial.

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

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 defined 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 significant differences between groups for age, BMI or sex (n.s). The cartilage restoration group (- 2.5 mm ± 5.9) was found to have a significantly 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 significantly 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.