Cross-linked polyethylene in total hip arthroplasty has demonstrated excellent long-term wear resistance, leading to its acceptance as the standard bearing used in hip replacement. Adoption in knee replacement has been tentative, as the cross-linking process can decrease the polyethylene mechanical properties. The current study's purpose was examining survivorship of a fixed bearing knee replacement system featuring a moderately cross-linked polyethylene (MXLK) bearing, a cobalt chrome (CoCr) tibial tray with a highly polished top surface, and a new polyethylene-to-tray locking mechanism. The MXLK is made of ultra-high molecular weight GUR1020 resin irradiated with 5 Mrad gamma radiation, followed by a free radical quenching remelting annealing process, above the 135 degree melting point, that provides wear and fatigue resistance, and oxidative stability. From November 2005 to June 2008, 539 PFC Sigma primary total knee replacements (TKA's) were prospectively entered into this non-comparative, multicenter, multinational study. Average age at time of surgery was 67 years, 57% were female, average body mass index was 30.4 kg/m2, and the dominant diagnosis was osteoarthritis (97%). Kaplan-Meier (KM) survivorship was the primary endpoint with primary event definition being removal of any component for any reason. The time variable was one of the following: time to revision, time to death, or time to last follow-up. Additional endpoints included: American Knee Society scores (knee and function), Oxford Knee score (range 12 to 60), SF-12 scores; radiographically assessed rates of radiolucent lines (RLL's) and osteolysis. RLL's greater than 2mm were counted. Progressive RLL's were those increasing in width from an earlier follow-up interval. Adjacent RLL's were defined as RLL's in adjacent zones. Complete RLL's were defined as RLL's completely around a component. This report provides 5-year results in this ongoing study with a 10-year final endpoint.Introduction
Materials & Methods
54% of meniscal tears were medial, 12% lateral and 10% bilateral. Patients with a lateral tear were significantly younger (45 Vs 51 yrs, p<
0.001). The most common type of medial tear was a flap tear (34%), followed by horizontal cleavage tears [HCT] (18%). The posterior 1/3 is the most common position. Laterally the tear morphology shows HCT comprising 25% and degenerative tears 17%, with the most common position a middle 1/3 tear. Lateral tears are more common in females (p<
0.05) Patients with bucket handle tears were significantly younger (41 Vs 53yrs, p<
0.001) and more likely to have a history of trauma (p<
0.001). Medial joint line tenderness was the most sensitive test (79%) and had the highest positive predictive value (81%). McMurry’s test is the most specific for both medial and lateral tears (90%) but is not sensitive. Medial meniscal tears are more accurately diagnosed clinically than lateral (79% Vs 50%).
Infection in total knee replacement is a devastating complication. Current literature supports two-stage revision as the gold standard treatment. The alternative single stage procedure has been reported to have favourable results. We assessed the early clinical results of single stage revision for infected total knee replacement. Between February 2005 and August 2007, 12 patients had revision total knee replacement for infection by the senior authors at two centres. In the majority of the patients, the infective organism was isolated by arthroscopic synovial biopsy prior to revision. Standard single stage procedure included the explantation, debridement and re-implantation of the prosthesis. All the patients received intravenous antibiotics for six weeks and oral antibiotics were continued for further 6 weeks. All the patients had the inflammatory markers monitored during follow-up. Significant improvement was noted in the SF-12 PCS, WOMAC pain and stiffness scores at the latest follow-up. None of these patients required re-revision. Radiological evaluation was done using the Knee Society system. None of the knees showed evidence of progressive loosening. Radio-opaque lines were found around the stems and were present on immediate post-operative radiographs; this did not indicate loosening or infection at a mean follow-up of two years. Early clinical and radiological results of the single stage revision for infected total knee replacement appear to be promising. One operation, one anaesthetic and quicker recovery are the advantages for the patient and with the reduced hospital stay it is cost-effective. The problems of stiffness in the knee and muscle wasting with cement spacer are avoided.
The principles of revision total knee replacement are to understand the cause of failure, adequate surgical exposure, achieving appropriate soft tissue balance, restoration of limb and joint line alignment, correct implant alignment, and a good range of motion. It is a technically and economically demanding procedure and its successful performance requires thorough preoperative planning, adherence to the principles, availability of diverse implant options and adequate bone graft. We prospectively assessed the survivorship of Co-ordinate Ultra prosthesis (DePuy, Warsaw, Ind) used for revision knee arthroplasty. Forty-nine patients had 53 revision knee replacements performed by the senior author between April 1999 and September 2001. Seven patients (7 knees) had died. At a mean follow-up of 6 years (range: 5–7 years), 46 knees in 42 patients were available for review. None were lost to follow-up. There were 31 women and 11 men, with a mean age of 74.2 years. The reason for revision was instability in 39 knees, infection in 3 knees, pain in 2 knees and stiffness in 2 knees. Significant improvement was noted in the SF-12 PCS and WOMAC pain and stiffness scores at the latest follow-up. None of these patients required re-revision. None of the knees showed evidence of progressive loosening. Radio-opaque lines were found around the stems and were present in immediate post-operative radiographs; this did not indicate loosening or infection on further follow-up. Cumulative survival analysis (Kaplan-Meier method) was 100% at 7 years. Clinical and radiological outcome analysis has revealed that the Co-ordinate Ultra revision knee system continues to function satisfactorily at a mean follow-up of 6 years.
We report our experience with LCS Patellofemoral joint replacement. Between September 2003 and November 2007, 66 consecutive patients were reviewed retrospectively who underwent LCS patellofemoral joint replacement. There were 13 males and 51 females with a mean age of 61.6 years (range 43–78). The average follow-up was 22 months (range 11–51 months). To assess the outcome, revision for any cause was taken as the end point for this study. A total of 14 (21.2%) revision operations were carried out at an average of 15.6 months (range 8–29 months) from the initial operation. The reasons for revision were mal-tracking of patella (3), dislocated patellar button (2), persistent unexplained pain (5) and progression of arthritis (4). Amongst the remaining 52 patients, 8 are still experiencing pain and not entirely satisfied with the procedure. 42 patients (63%) have a satisfactory outcome so far. All of them who underwent revision to a total knee replacement were satisfied with their outcome with relief in their symptoms. Revision to a total knee replacement is not a straightforward procedure, especially removing the metal backed patellar component. The revision rate of over 21% is unacceptably high to recommend the procedure as a routine. Based on our experience, we conclude that LCS patellofemoral replacement should be used with caution.
We reviewed the clinical and radiological outcome of 72 Co-ordinate prostheses (DePuy, Warsaw, Ind) used for revision knee arthroplasty performed by a single surgeon from May 1994 to December 1997. Twenty-three patients (25 knees) since died. Two were lost to follow-up. At a mean follow-up of 10 years (range 9–12years), 45 knees in 43 patients were available for review. There were 12 men and 31 women with a mean age of 71.34 years (range 43 to 87 years). The reason for revision was instability in 38 knees, infection in 5 knees and stiffness in 2 knees. There was a significant improvement in the SF-12 PCS and WOMAC pain and stiffness scores at the latest follow-up. Five of these knees had to have re-revision surgery. One patient had a re-revision for aseptic loosening, one patient for recurrent dislocation of patella. Three patients underwent repeat procedures for infection. Radiological evaluation using the Knee Society system revealed well-fixed components in 35 knees (77.78%). The radiolucencies of varying degrees were present in 10 knees (22.22%). Eight had non-progressive radiolu-cencies and did not show any evidence of loosening. 25 (55.5%) knees had halo sign (radiopaque line) present around the prosthesis (7 were femoral side, 4 were tibial side and 14 around both the prosthesis). Using Kaplan Meier method the cumulative survival rate was 88.87% at 12 years, removal of the prosthesis or re-revision were used as end points. An analysis of clinical and standard radiographic outcomes has revealed that the Co-ordinate revision knee system continues to function satisfactorily at a mean of 10 years.
Stem dissociation in modular revision knee replacement due to failure of the frictional lock of the Morse taper has been reported in the literature. However, the medium and long-term implications of stem dissociation are unknown, as clinical outcomes have not been reported. We report a series of 10 cases in which there was intra-operative dissociation of the tibial stem. Between 1994 and 1999, 98 patients underwent revision total knee replacement for aseptic loosening at our institution. Ten of these patients were noted to have tibial stem dissociation, apparent on the immediate post-operative radiographs. The senior author (RWP) performed all procedures and used a standardized operative technique. The Co-ordinate modular knee revision system was used in all cases. The quality of the bone was noted in all the cases intra-operatively; and was graded as 1) sound bone, 2) soft but intact, 3) soft and fractured cortex. Our study demonstrates that the tibial stem dissociation did not cause any significant detriment to the clinical outcome on minimum follow-up of six years in nine cases where the tibial metaphyseal cortical rim was intact. In one case, where the medial tibial plateau had a cortical defect, the prosthesis drifted into varus mal-alignment and the patient required a further revision for aseptic loosening. We therefore question whether long canal filling tibial stems are necessary in all revision total knee replacements particularly when the cortical rim is intact and a non-constrained poly-ethylene insert is used.
To report the experience with the new device, the Long Proximal Femoral Nail (Long PFN) in patients with impending pathological femoral fractures to identify the advantages and complications associated with its usage. This is the first in the series on the use of Long PFN for patients with femoral metastases. Between April 2000 and September 2001, twenty-five consecutive patients with femoral pathological lesions were prophylactically stabilised using Long PFN. The nailings were performed using a percutaneous closed technique. Lateral femoral Line (LFL) technique was used for location of the entry point and easy insertion for the nail. Only the proximal one-fifth of the femur was reamed to accommodate the 17 mm diameter of the proximal part of the nail. We had technical problems in three patients. The overall mobility of the patients improved in twenty patients and the mobility remained the same as pre-operative level in five patients. Good to excellent pain relief achieved in eighteen patients. The pain relief was fair in five patients and poor in two patients. We had no mechanical failure of the implant in our series. Long PFN, a modified reconstruction nail, can be inserted percutaneously and has an easy operation technique. Our early experience with Long PFN in the management of impending femoral fractures has been favourable.
There has been speculation as to whether the outcome of revision total knee arthroplasty (TKA) is as successful as primary TKA. The purpose of this study was to assess patient outcomes following revision TKA and compare them to patient outcomes following primary TKA. This study collected data prospectively from patients operated upon by one surgeon using one prosthesis in each group. Patients completed SF12 and WOMAC questionnaires pre-operatively and at six and twelve months post-operatively. In the primary TKA group there were 84 patients. In the revision TKA group there were 60 patients. Statistical analysis was performed using paired and unpaired t-tests. Results showed that the improvements in SF12 physical scores and WOMAC pain, stiffness and function scores in both primary TKA and revision TKA patients were statistically significant (p <
0.0001). There was no significant difference in the magnitude of the improvement in SF12 physical (p = 0.7145) and WOMAC pain (p = 0.0902), stiffness (p = 0.1557) and function (p = 0.3152) scores between the primary and revision patients following surgery. The mental scores of patients in both groups showed no significant difference following surgery (Primary p = 0.823, Revision p = 0.7095). The findings show that primary and revision TKA lead to a comparable improvement in patient perceived outcomes of physical health parameters. However, there is no significant improvement in patient perception of mental health.