Three-Dimensionally Measured TT-TG Distance Remains After Medial Open-Wedge High Tibial Osteotomy and Correlates With Internal Rotation of Distal Tibial Segment Below the Osteotomy Site

Abstract

Objective To evaluate perioperative changes in anatomical parameters related to patellofemoral biomechanics, as well as cartilage repair outcomes following additional arthroscopic marrow stimulation for full-thickness trochlear cartilage defects (TCDs) during medial open-wedge high tibial osteotomy (MOWHTO). Design A total of 38 patients (38 knees) who underwent arthroscopic marrow stimulation (microfracture or microdrilling) for TCDs combined with MOWHTO were retrospectively reviewed. The mean follow-up period was 27.0 months. Three-dimensional measurements of parameters associated with patellar biomechanics were performed. Magnetic resonance imaging and second-look arthroscopy were used to assess repaired cartilage, using Magnetic Resonance Observation of Cartilage Repaired Tissue (MOCART) knee score and International Cartilage Repair Society Cartilage repair assessment (ICRS CRA). Results In 3-dimensional measurements, the tibial tubercle-trochlear groove (TT-TG) distance was maintained (mean difference: -0.6 mm, P = 0.227), whereas the modified Q-angle significantly decreased (mean difference: -1.9 degrees, P = 0.002). The distal femur-distal tibial rotation (DF-DTR) decreased, indicating internal rotation of the distal tibial segment (mean difference: -5.3 degrees, P < 0.001). TT-TG distance was associated with DF-DTR (r = 0.583, P = 0.001). Arthroscopic marrow stimulation for TCDs showed favorable cartilage repaired tissue, especially for the microdrilling group (median MOCART score, 70; ICRS CRA grade 1-2, 82.8%). Conclusion The 3-dimensionally measured TT-TG distance was maintained after MOWHTO and was associated with internal rotation of the distal tibial segment below the osteotomy site. Arthroscopic marrow stimulation for TCDs in patients undergoing MOWHTO achieved favorable cartilage repaired tissue in short term.