Intraoperative analysis of patellofemoral joint morphology before and after total knee arthroplasty: A feasibility study

BACKGROUND: Patellofemoral problems after total knee arthroplast (TKA) are frequent and often associated with a change in the geometry of the trochlear groove. OBJECTIVE: The present study aimed to analyze the feasibility of intraoperative examination of the patellofemoral joint geometry before and after the implantation of bicondylar total knee replacements without exposing the patient to radiation. MATERIAL AND METHODS: The patellofemoral joint morphology geometries of 33 patients before and after implantation of a bicondylar total knee replacement was intraoperatively analyzed using a digital scanning method. Femoral surface geometries were extracted from intraoperatively recorded tactile scanning data using an in-house algorithm. The geometries were then characterized by sulcus height, medial femoral condyle height and lateral femoral condyle height. RESULTS: Our preliminary results show that these key geometric parameters are only partially restored after TKA leading to a distinctly different shaped profile of the anterior distal femur. Maximum and minimum mean differences in sulcus height, medial femoral condyle height, and lateral femoral condyle height before and after surgery were 2.00 mm/−3.06 mm, 2.51 mm/−6.25 mm and 2.74 mm/−3.58 mm, respectively. CONCLUSION: A new method for intraoperative analysis of the patellofemoral joint morphology before and after TKA without radiation exposure was developed and utilized. Even with the use of modern total knee designs, the patellofemoral articulation is considerably changed postoperatively as quantified by the key parameters of sulcus height, medial femoral condyle height, and lateral femoral condyle height. This may result in altered knee biomechanics and might explain persistent patellofemoral disorders, which are often reported by patients after TKA.