Only 57% of the patients with a pathological TT-TG distance (≥20 mm) had lateralization of the tibial tubercle in relation to the posterior cruciate ligament. The TT-PCL distance is an alternative method for determining the position of the tibial tubercle.

Pain after total knee arthroplasty (TKA) represents a common observation in about 20% of the patients after surgery. Some of these painful knees require early revision surgery within 5 years. Obvious causes of failure might be identified with clinical examinations and standard radiographs only, whereas the unexplained painful TKA still remains a challenge for the surgeon. It is generally accepted that a clear understanding of the failure mechanism in each case is required prior considering revision surgery. A practical 10-step diagnostic algorithm is described for failure analysis in more detail. The evaluation of a painful TKA includes an extended history, analysis of the type of pain, psychological exploration, thorough clinical examination including spine, hip and ankle, laboratory tests, joint aspiration and test infiltration, radiographic analysis and special imaging techniques. It is also important to enquire about the length and type of conservative therapy. Using this diagnostic algorithm, a sufficient failure analysis is possible in almost all patients with painful TKA.

We established a difference between neck, mid, and distal femoral torsion with reproducible measurements. Our data suggest that all 3 levels of the femur contribute to the total femoral torsion, with a different pattern among patients with high torsion and patellar instability.

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