Soft tissue impingement at the femorotibial joint after a posterior cruciate ligament-retaining total knee arthroplasty

Abstract

Abstract Introduction: Impingement of soft tissue at the femorotibial (FT) joint after a total knee arthroplasty (TKA) can lead to poor postoperative performance and pain. In this report, we have described a case of FT joint impingement by scar tissue formation extending over the anterior surface of the intercondylar fossa after a posterior cruciate ligament (PCL)-retaining TKA. Patient concerns: A 78-year-old woman developed crepitations and discomfort during left knee extension and stair climbing at about 10 months after TKA. Diagnosis: Plain radiographs of her knee revealed that the patella baja present from before her TKA had progressed. Impression marks in the distal pole of the patella caused by the impingement of the scar tissue between the femoral component of PCL-retaining TKA and the PCL insertion during knee extension were also observed. The impingement was confirmed by direct arthroscopy. Interventions: We treated her by performing a resection of the scar tissue, excision of the distal pole of the patella, and replacement of the patella. Outcomes: Recovery period was unremarkable, with no recurrence of symptoms over the subsequent 5-year follow-up period. Conclusion: Our case demonstrates that a chronic mechanical irritation can induce proliferation of the residual synovial tissue at the insertion of the PCL. This, in turn, could result in the growth of a scar-like tissue, which could extend over the anterior surface of the intercondylar fossa and grow into the distal pole of the patella, causing an impingement at the FT joint. The presence of a patella baja before TKA could be a risk factor for FT impingement after PCL-retaining TKA, warranting a careful follow-up of these patients.