Tibial tubercle more posteriorly positioned in patients with patellar cartilage lesions vs intact cartilage
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New data showed the tibial tubercle was more posteriorly positioned in patients with patellar cartilage lesions compared with patients with intact patellar cartilage.
Researchers retrospectively reviewed 17 patients who underwent patellofemoral cartilage restoration or repair procedures, 20 control patients who underwent partial meniscectomy with normal patellar cartilage and 15 patients with asymptomatic patellar chondrosis who underwent partial meniscectomy with patellar cartilage wear. Preoperative axial They used T2 MRI sequence to measure the sagittal tibial tubercle–trochlear groove (sTTTG) distance. The nadir of the anterior trochlear cartilage was the first point and the second point was the anterior tibial tubercle. Investigators compared the patient groups with analysis of variance testing with Bonferroni corrections.
Results showed patients who underwent patellofemoral cartilage restoration or repair procedures had a significantly more posterior mean sTTTG distance compared with control patients who underwent partial meniscectomy with normal patellar cartilage (5.9 mm vs. 0.8mm). Patients with asymptomatic patellar chondrosis had a mean value that fell between the other two groups; however, it was not significantly different (2.7 mm). Sulcus angle, Caton-Deschamps Index, TTTG or knee flexion angle on the MRI scan were not significantly different between the groups. – by Monica Jaramillo
Disclosures: Landsdown reports he receives fellowship-related educational support from Smith & Nephew and Arthrex Inc., and hospitality related payments from Tornier/Wright. Please see the full study for all other authors’ relevant financial disclosures.
Perspective
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Michael J. Alaia, MD
Symptomatic patellar chondral lesions remain one of the most perplexing injuries to treat in sports medicine, as they are often confounded by several anatomical variables as well as the potential for patellar maltracking and instability. Additionally, it is well known that osteotomy is extremely useful in joint preservation procedures. This well-done study attempted to correlate symptomatic patellofemoral chondral lesions with a more posterior position of the tibial tubercle with reference to the trochlear groove. The authors found, quite significantly, that those with symptomatic PF lesions had a more posteriorly oriented tibial tubercle, approximately 5 mm more posterior than those with normal PF cartilage. (5.9 ± 5.5 mm posterior to the trochlear groove vs. 0.8 ± 5.3 mm posterior; P = .018).
The authors appropriately excluded patients with patellar instability and those with knee flexion of greater than 10°, however the cohort size is small and the results could be skewed by even relatively low flexion angle differences in the MRI scanner. But it is understood that anteriorization of the tubercle significantly lowers PF contact pressures, and conversely, posteriorly directing the tubercle increases these forces. The results of this study reinforce the concept of anteriorization osteotomy (or anteromedialization), as a mandatory component of patellofemoral chondral restoration procedures.
Associate director, Sports Medicine Fellowship
NYU Langone Medical Center
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