Patellofemoral crepitus in high flexion rotating platform knee arthroplasty.

Introduction: Recently, implant manufacturers have made modifications to currently available implants in an attempt to improve postoperative flexion. The Low Contact Stress (LCS) RPS (DePuy Orthopaedics Inc., Warsaw, IN, USA) is one such prosthesis which is a modification of the established LCS RP design. Satisfactory results have been obtained without patella resurfacing in the original LCS RP design.

Methods: We report on a single surgeon series showing an alarmingly high incidence of patellofemoral crepitus when this new prosthesis, LCS RPS, is used without patella resurfacing. In addition, the outcomes for this prosthesis from the Australian National Joint Replacement registry will be reported. These results show a high revision rate with most revisions being patella resurfacing for patellofemoral pain.

Results: Affected patients who elected to have a revision procedure underwent either an arthroscopic patellaplasty procedure or revision to resurface the patella. Both of these procedures resulted in satisfactory resolution of symptoms in the majority of patients.

Discussion: Potential causes for this complication are discussed. It is the recommendation of the authors that when using this prosthesis the patella is resurfaced.