Purpose: Patellar Clunk is associated with posterior stabilized (PS) femoral components in which a scarred synovial suprapatellar nodule catches on the femoral box with active extension of the flexed knee. We investigated whether a rotating platform tibial component increases the incidence of patellar clunk.

Methods: From December 1998 to June 2006, a single surgeon performed 659 primary TKAs. 329 fixed-bearing tibial components and 330 rotating platforms were implanted. The same PS femoral component was used in all cases. All components were from the PFC Sigma Total Knee System (DePuy, Warsaw, IN, USA). The incidence of patellar clunk requiring reoperation was evaluated prospectively.

Results: There were 17 arthroscopies performed on 16 knees in 15 patients. One patient required bilateral arthroscopies, and one a repeat arthroscopy. 6 (1.8%) arthroscopies were required in the fixed bearing group, and 10 (3%) in the rotating platform group (p< 0.10 NS). The repeat arthroscopy was in the rotating platform group. Time to arthroscopy from the index surgery was 13.6 months (Range 5–40) for the entire group, 15.2 months (Range 8–40) for the fixed-bearing group, and 12.6 months (Range 5–20) for the rotating platform group (p< 0.10 NS).

Conclusions: The incidence of patellar clunk is not increased by the use of a rotating platform tibial component in TKA. While the mobile bearing may improve patellar tracking, causing the extensor mechanism to seat deeper in the trochlear groove, it does not seem to represent a risk factor for the development of the suprapatellar scarring that predisposes to patellar clunk.

Purpose: The original C-STEM (DePuy, Warsaw, IN, USA), a triple tapered polished collarless cemented stem, has an established clinical record. The new C-stem-AMT retains the identical intramedullary design, but enhances the extramedullary portion of the stem with a high offset option, and a mini-taper which is fully covered by the head, and accommodates a broad range of head diameters and neck lengths. This is an early report of clinical experience with the C-STEM AMT.

Methods: From March 2005 to June 2006, 34 C-STEMAMTs were implanted in 32 patients (21 females, 13 males) with mean age of 69 years (R 52–89). Diagnoses were Osteoarthritis in 30, AVN in 2, DDH in 1, and loose femoral implant in 1. Average follow-up was 9.7 months (R 3–18).

Preoperative and postoperative Harris Hip Scores, radiographs, and postoperative complications were recorded prospectively and compared to an early cohort of 66

C-Stems previously implanted between May 1999 and July 2001.

Results: Harris Hip Scores improved from 38 to 99 at one year. There has been no loosening, significant subsidence or reoperations. No dislocations have occurred, in contrast to 6 (9%) dislocations in the original C-Stem group.

Conclusions: As expected, the behaviour of the intramedullary portion of the C-Stem AMT is mirroring the experience with the C-Stem. The enhanced extramedullary design which accommodates additional neck lengths and head sizes, improves range of motion and provides additional offset has substantially reduced dislocation by facilitating accurate reconstruction of appropriate hip biomechanics.