We have examined the differences in clinical outcome of total knee replacement (TKR) with and without patellar resurfacing in a prospective, randomised study of 181 osteoarthritic knees in 142 patients using the Profix total knee system which has a femoral component with features considered to be anatomical and a domed patellar implant. The procedures were carried out between February 1998 and November 2002. A total of 159 TKRs in 142 patients were available for review at a mean of four years (3 to 7). The patients and the clinical evaluator were blinded in this prospective study. Evaluation was undertaken annually by an independent observer using the knee pain scale and the Knee Society clinical rating system. Specific evaluation of anterior knee pain, stair-climbing and rising from a seated to a standing position was also undertaken. No benefit was shown of TKR with patellar resurfacing over that without resurfacing with respect to any of the measured outcomes. In 22 of 73 knees (30.1%) with and 18 of 86 knees (20.9%) without patellar resurfacing there was some degree of anterior knee pain (p = 0.183). No revisions related to the patellofemoral joint were performed in either group. Only one TKR in each group underwent a re-operation related to the patellofemoral joint. A significant association between knee flexion contracture and anterior knee pain was observed in those knees with patellar resurfacing (p = 0.006).
"Diagnosing AKP with patient-administered questionnaires only provides data about patients’ subjective perceptions about their knee; patient interviews supplemented with patella-specific questions and manual tests, such as palpation of the patella, detect both subjective and objective information. Studies relying only on patients’ subjective symptoms usually report lower rates of AKP (Burnett et al. 2007, Epinette and Manley 2008, Smith et al. 2008) than studies using both subjective and objective data (Baldini et al. 2006, Campbell et al. 2006). We diagnosed AKP using the HSS patella score, containing patella-specific and manual tests, which is perhaps the reason for the high prevalence of pain in the front part of the knee (60%)—compared to previous reports of 13–50% (Baldini et al. 2006, Campbell et al. 2006, He et al. 2011, Li et al. 2011, Meftah et al. 2011, Pilling et al 2012). "
[Show abstract][Hide abstract] ABSTRACT: Background
Attempts to relate patellar cartilage involvement to anterior knee pain (AKP) have yielded conflicting results. We determined whether the condition of the cartilage of the patella at the time of knee replacement, as assessed by the OARSI score, correlates with postsurgical AKP.
Patients and methods
We prospectively studied 100 patients undergoing knee arthroplasty. At surgery, we photographed and biopsied the articular surface of the patella, leaving the patella unresurfaced. Following determination of the microscopic grade of the patellar cartilage lesion and the stage by analyzing the intraoperative photographs, we calculated the OARSI score. We interviewed the patients 1 year after knee arthroplasty using the HSS patella score for diagnosis of AKP.
57 of 95 patients examined had AKP. The average OARSI score of painless patients was 13 (6–20) and that of patients with AKP was 15 (6–20) (p = 0.04). Patients with OARSI scores of 13–24 had 50% higher risk of AKP (prevalence ratio = 1.5, 95% CI: 1.0–2.3) than patients with OARSI scores of 0–12.
The depth and extent of the cartilage lesion of the knee-cap should be considered when deciding between the various options for treatment of the patella during knee replacement.
"The literature search resulted in 5,290 hits for the survival review and 56 studies were included, with a total of 20.599 patients; see Figure 1 (Goldberg et al. 1988, Laskin 1990, Samuelson et al. 1990, Wright et al. 1990, Moran et al. 1991, Grewal et al. 1992, Ranawat et al. 1993, 1994, Rinonapoli et al. 1994, Weir et al. 1996, Knight et al. 1997, Scott 1997, Ansari et al. 1998, Hsu et al. 1998, Ewald et al. 1999, Mont et al. 1999, Buehler et al. 2000, Emerson et al. 2000, Robertsson et al. 2000, Stukenborg-Colsman et al. 2000, Berger et al. 2001a,b
Faraj et al. 2001, Gill et al. 2001, Khaw et al. 2001, Schroder et al. 2001, Sextro et al. 2001, Fetzer et al. 2002, Forster et al. 2002, Khaw et al. 2002, Worland et al. 2002, Mayman et al. 2003, Goldberg et al. 2004, Arora et al. 2005, Bozic et al. 2005, Campbell et al. 2006, Clayton et al. 2006, Gioe et al. 2006, Lachiewicz et al. 2006, Vessely et al. 2006, Bertin 2007, Kim et al. 2007, Rodricks et al. 2007, Zaki et al. 2007, Anderson et al. 2008, Chana et al. 2008, Dalury et al. 2008, Parsch et al. 2008, Ritter et al. 2008, Santini et al. 2008, Smith et al. 2008). The mean quality score of the survival studies was 6.0 (SD 1.8) on an 11-point scale. "
[Show abstract][Hide abstract] ABSTRACT: Purpose
We performed two parallel systematic reviews and meta-analyses to determine the association between early migration of tibial components and late aseptic revision.
One review comprised early migration data from radiostereometric analysis (RSA) studies, while the other focused on revision rates for aseptic loosening from long-term survival studies. Thresholds for acceptable and unacceptable migration were determined according to that of several national joint registries: < 5% revision at 10 years.
Following an elaborate literature search, 50 studies (involving 847 total knee prostheses (TKPs)) were included in the RSA review and 56 studies (20,599 TKPs) were included in the survival review. The results showed that for every mm increase in migration there was an 8% increase in revision rate, which remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. Consequently, migration up to 0.5 mm was considered acceptable during the first postoperative year, while migration of 1.6 mm or more was unacceptable. TKPs with migration of between 0.5 and 1.6 mm were considered to be at risk of having revision rates higher than 5% at 10 years.
There was a clinically relevant association between early migration of TKPs and late revision for loosening. The proposed migration thresholds can be implemented in a phased, evidence-based introduction of new types of knee prostheses, since they allow early detection of high-risk TKPs while exposing only a small number of patients.
"Similar findings were reported by Feller et al.  who found that the stair climbing ability in the non-resurfaced patient group was significantly better compared with those with patella resurfacing. Two RCTs found no significant difference regarding the performance of functional tasks between resurfaced and non-resurfaced patients [46, 139], whilst two other RCTs showed a trend toward increased pain with stair ascend and descend, although values did not reach statistical significance [25, 156]. "
[Show abstract][Hide abstract] ABSTRACT: Early arthroplasty designs were associated with a high level of anterior knee pain as they failed to cater for the patello-femoral joint. Patellar resurfacing was heralded as the saviour safeguarding patient satisfaction and success but opinion on its necessity has since deeply divided the scientific community and has become synonymous to topics of religion or politics. Opponents of resurfacing contend that the native patella provides better patellar tracking, improved clinical function, and avoids implant-related complications, whilst proponents argue that patients have less pain, are overall more satisfied, and avert the need for secondary resurfacing. The question remains whether complications associated with patellar resurfacing including those arising from future component revision outweigh the somewhat increased incidence of anterior knee pain recorded in unresurfaced patients. The current scientific literature, which is often affected by methodological limitations and observer bias, remains confusing as it provides evidence in support of both sides of the argument, whilst blinded satisfaction studies comparing resurfaced and non-resurfaced knees generally reveal equivalent results. Even national arthroplasty register data show wide variations in the proportion of patellar resurfacing between countries that cannot be explained by cultural differences alone. Advocates who always resurface or never resurface indiscriminately expose the patella to a random choice. Selective resurfacing offers a compromise by providing a decision algorithm based on a propensity for improved clinical success, whilst avoiding potential complications associated with unnecessary resurfacing. Evidence regarding the validity of selection criteria, however, is missing, and the decision when to resurface is often based on intuitive reasoning. Our lack of understanding why, irrespective of pre-operative symptoms and patellar resurfacing, some patients may suffer pain following TKA and others may not have so far stifled our efforts to make the strategy of selective resurfacing succeed. We should hence devote our efforts in defining predictive criteria and indicators that will enable us to reliably identify those individuals who might benefit from a resurfacing procedure. Level of evidence V.
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