Asymmetric patella resurfacing in total knee arthroplasty

Three hundred consecutive primary, cemented, condylar total knee arthroplasties (TKAs) were reviewed for the presence of asymmetric patella resurfacing using a postoperative Merchant or sunrise patellar radiograph. Twenty-one knees in 14 patients were found to have the patella asymmetrically resurfaced. Asymmetric resurfacing typically involved the inadvertent preferential resurfacing of the lateral facet with underresection of bone from the medial patellar facet. All patients underwent follow-up for a minimum of 5 years, with a mean follow-up of 7.5 years. Of the 21 knees, 3 revisions were required for patellar complications. One patellar component was loose on radiographs and there was marked patellofemoral pain in 6 knees. Overall, 11 of 21 knees (52%) underwent revision or were recommended for revision for patellar complications or had anterior knee pain that limited activities. Inadvertent asymmetric patella resurfacing using the kinematic condylar implant adversely affects the outcome after TKA.     

Secondary patella resurfacing in painful non-resurfaced total knee arthroplasties

Purpose

In Norway, 19 % of revisions of non-resurfaced total knee arthroplasties done for knee pain between 1994 and 2011 were Secondary Patella Resurfacing (SPR). It is, however, unclear whether SPR actually resolves the pain. The aim was to investigate prostheses survival and clinical outcomes following SPR.

Method

A total of 308 knees (301 patients) with SPR were used to assess implant survival, and a sub-cohort (n?=?114 out of 301 patients) with Patient Reported Outcome Measures (PROMs) data were used to assess the clinical outcomes. The EuroQol (EQ-5D), the Knee Injury and Osteoarthritis Outcome Score, and Visual Analogue Scales on satisfaction and pain were used to collect PROM data. Outcomes were analysed by Kaplan-Meier, Cox regression, and multiple linear regression.

Results

The five- and ten-year Kaplan-Meier survival percentages were 91 % and 87 %, respectively. Overall, 35 knees were re-revised at a median follow-up of eight years and pain alone (10 knees) was the main cause of re-revision. Younger patients (<60 years) had nearly nine times higher risk of re-revision compared to older patients (>70 years) (RR?=?8.6; p?<?0.001). Mean EQ-5D index score had improved from 0.41 (SD 0.21) preoperative to 0.56 (SD 0.25) postoperative following SPR. A total of 63 % of patients with PROM data were satisfied with the outcomes of SPR.

Conclusion

The long-term prostheses survival following SPR was satisfactory, although not as good as for primary knee replacement. Patients’ health related quality of life improved significantly following SPR. Still, more than a third of patients with PROMs data were dissatisfied with the outcomes of the SPR procedure.

     

Failure of total knee arthroplasty with or without patella resurfacing

Background and purpose

Patella resurfacing during primary total knee arthroplasty (TKA) is disputed and new prosthesis designs have been introduced without documentation of their survival. We assessed the impact on prosthesis survival of patella resurfacing and of prosthesis brand, based on data from the Norwegian Arthroplasty Register.

Patients and methods

5 prosthesis brands in common use with and without patella resurfacing from 1994 through 2009 were included n = 11,887. The median follow-up times were 9 years for patella-resurfaced implants and 7 years for implants without patella resurfacing. For comparison of prosthesis brands, also brands in common use with only one of the two treatment options were included in the study population (n = 25,590). Cox regression analyses were performed with different reasons for revision as endpoints with adjustment for potential confounders.

Results

We observed a reduced overall risk of revision for patella resurfaced (PR) TKAs, but the statistical significance was borderline (RR = 0.84, p = 0.05). At 15 years, 92% of PR and 91% of patella non resurfaced (NR) prostheses were still unrevised. However, PR implants had a lower risk of revision due to pain alone (RR = 0.1, p < 0.001), but a higher risk of revision due to loosening of the tibial component (RR = 1.4, p = 0.03) and due to a defective polyethylene insert (RR = 3.2, p < 0.001).At 10 years, the survival for the reference NR brand AGC Universal was 93%. The NR brands Genesis I, Duracon, and Tricon (RR = 1.4–1.7) performed statistically significantly worse than NR AGC Universal, while the NR prostheses e.motion, Profix, and AGC Anatomic (RR = 0.1–0.7), and the PR prostheses NexGen and AGC Universal (RR = 0.4–0.5) performed statistically significantly better. LCS, NexGen, LCS Complete (all NR), and Tricon, Genesis I, LCS, and Kinemax (all PR) showed no differences in this respect from the reference brand. A lower risk of revision (crude) was found for TKAs performed after 2000 as compared to those performed earlier (RR = 0.8, p = 0.001).

Interpretation

Although revision risk was similar for PR and NR TKAs, we found important differences in reasons for revision. Our results also indicate that survivorship of TKAs has improved.Use of a patellar component (patella resurfacing) during primary total knee arthroplasty (TKA) is still disputed. The search for improvements has resulted in the introduction of several new designs that are widely used nowadays, although there is no documentation about their survival.The question of whether or not primary patella resurfacing should be recommended has led to several observational studies, randomized clinical trials (RCT), and meta-analyses (Forster 2004, Parvizi et al. 2005, Nizard et al. 2005, Pakos et al. 2005) and review articles (Meneghini 2008). In a critical appraisal of the available evidence, Calvisi et al. (2009) were not able to find any clear superiority between either of the two treatments due to methodological limitations in the published studies. Studies based on data from arthroplasty registers have found a higher risk of revision when the patella was left untreated (Furnes et al. 2002, the Swedish Knee Arthroplasty Register Annual Report 2009, Clements et al. 2010). Furnes et al. 2002) found that the increased revision risk was mainly related to revisions due to pain. Some recent studies have, however, indicated that there is no difference in patients'' perception of postoperative pain in the two groups of treatment (Johnston et al. 2009, Lygre et al. 2010) and that the observed differences in risk of revision due to pain may be caused by the exclusive option of a secondary patella resurfacing of the originally patella unresurfaced knee. This is supported by a recent study from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) that suggested that surgeons may be more inclined to revise a patella non resurfaced implant knee with a secondary patella resurfacing if the patient presents later with knee pain, given that the option is still available (Clements et al. 2010)Few studies have compared survival of different prosthesis brands and implant designs, but a previous study (Furnes et al. 2002) from the Norwegian Arthroplasty Register (NAR) did not find any statistically significant short-term differences in revision rates between the most commonly used brands in Norway. Other national arthroplasty registers with longer follow-up have reported statistically significant differences between some commonly used brands in their annual reports (Australian Orthopaedic Association National Joint Replacement Registry Annual Report 2009, The Swedish Knee Arthroplasty Register Annual Report 2009).Based on data in the NAR, we compared overall survival of cemented knee prostheses with and without resurfacing of the patella, and assessed the survival of some widely used TKA brands.     

Secondary resurfacing of the patella in mobile-bearing total knee arthroplasty

OBJECTIVE: We aim to evaluate the impact of secondary patellar resurfacing in patients with patellar-related anterior knee pain who have undergone a mobile-bearing primary knee arthroplasty without resurfacing. MATERIALS: A total of 2950 primary Low Contact Stress (DePuy, Warsaw, Ind) mobile-bearing knee arthroplasties without patellar resurfacing were carried out between March 1992 and March 2003. Thirteen patients (0.4%) underwent secondary patellar resurfacing for patellar-related anterior knee pain. The mean age of the patients was 67.8 years. There was a mean time of 28 months to the secondary resurfacing procedure. RESULTS: Only 4 patients had an unequivocal improvement in their symptoms at a mean follow-up of 45 months (range, 3-92 months). No morbidity was noted from the procedure. CONCLUSION: The success rate of secondary patellar resurfacing is poor and patients should be counseled carefully.     

膝关节置换术中髌骨置换与非髌骨置换比较的Meta分析

[目的]系统评价全膝关节置换术中髌骨置换与否对术后疗效的影响,为临床治疗提供参考。[方法]全面搜索国内外关于膝关节置换术中髌骨置换和非髌骨置换的随机对照研究资料,按照既定的纳入、排除标准,核定检出符合评价标准的文献,提取所需研究数据,采用RevMan 4.2软件进行Meta分析。[结果]纳入随机对照研究16篇,共计1 922例膝关节置换术。Meta分析结果显示,髌骨置换组术后5年内发生膝前痛的风险降低,加权后RR=0.53,95%CI(0.30,0.94),但5年后二者无明显统计学差异。髌骨置换组术后5年以上发生再手术的风险低,加权后RR=0.35,95%CI(0.18,0.66),但5年内二者无明显统计学差异。膝关节KSS评分不论是亚组分析还是总体分析,均无统计学差异。总体分析结果,KSS评分加权均数差值为0.44,95%CI(-1.22,2.09)。[结论]全膝关节置换术中髌骨置换与非髌骨置换相比,术后5年内膝前痛发生率低,术后5年以上再手术的风险低,关节评分无明显差别。髌骨置换与非髌骨置换的优劣仍需大规模多中心的RCT来进一步研究。     

全膝关节置换术中髌骨置换与否对膝前痛发生的影响

[目的]回顾性分析、比较全膝关节置换术中髌骨置换与否对膝前痛发生的影响,为临床治疗提供参考。[方法]对1994年10月~2004年10月行人工全膝关节置换术病人125例(148膝)按髌骨置换(84膝)和未置换(64膝)分为2组,并对其随访资料进行分析,膝关节评分采用HSS评分系统,髌骨评分采用Feller评分标准。结果使用SPSS统计软件进行统计学分析。[结果]置换组HSS评分由术前的(39.6±39.8)分进步为末次随访时的(90.9±8.2)分,髌骨评分由(14.4±6.4)分进步到(25.2±4.8)分,膝前痛分数也由(4.6±3.9)分进步为(10.6±4.1)分;未置换组HSS评分由术前的(38.8±9.8)分进步为(90.2±8.9)分,髌骨评分由(14.2±6.2)分进步到(25.1±4.8)分,膝前痛分数也由(4.8±3.8)分进步为(10.3±4.1)分。2组患者末次随访时膝前痛均较术前明显减轻,差异有显著性意义;置换组与未置换组比较,膝前痛减轻的差别无显著性意义。[结论]无论髌骨置换与否,患者的合理选择和正确的手术操作是避免术后膝前痛的关键所在。     

Radiolucent zone of the patella following total knee arthroplasty without patellar resurfacing

Background

The radiolucent zones in the patella are sometimes observed in patients who have undergone total knee arthroplasty (TKA) without patellar resurfacing. On the basis of radiological findings from our clinical experience, we hypothesize that the pathogenesis of this lesion may be similar to that of the lesions of spontaneous osteonecrosis, and this lesion may be due to both osteoporosis and stress concentration. The present study aimed to determine the incidence of the radiolucent zone after TKA without patellar resurfacing. Moreover, the roles of osteoporosis and patellar morphology, which are related to the stress distribution in the patella, were also investigated.

Methods

We studied 48 knees of 38 patients who underwent primary TKA using the Genesis II prosthesis. Axial radiographs taken 1 year postoperatively were used to assess the incidence of the radiolucent zone. The World Health Organization fracture risk assessment tool (FRAX) score and the preoperative patellar facet angle were compared between patients with and without the radiolucent zones.

Results

Five patellae (10.4 %) showed the radiolucent zones postoperatively (the radiolucent group), whereas no such lesions were found in the remaining 43 patellae (the normal group). The major osteoporotic fracture risk of the radiolucent group calculated using the FRAX was 24.8 % and significantly higher than that in the normal group (14.7 %; p = 0.01). The average patellar facet angle in the radiolucent group was 123.6°, which was significantly smaller than that in the normal group (133.6°; p = 0.003).

Discussion and conclusions

The results of the present study suggest that both underlying osteoporosis and a steep patellar facet angle may play an important role in the pathogenesis of the radiolucent zones in patellae after TKA without patellar resurfacing. Patellar resurfacing may be considered, particularly in osteoporotic patients who have a steep patellar facet angle, to avoid the appearance of the postoperative radiolucent zone in the patella.     

Results of contralateral total knee arthroplasty in patients with a history of stiff total knee arthroplasty

This study seeks to evaluate the clinical outcomes of a second primary total knee arthroplasty in patients whose initial (contralateral) primary total knee arthroplasty was complicated by stiffness. We retrospectively compared the preoperative and postoperative range of motion and Knee Society Scores from a study group of 15 patients with an age-matched control group. Statistical analysis did not reveal a significant difference in final postoperative range of motion or Knee Society Scores between the 2 groups. However, there was a statistically significant higher rate of closed manipulation in the study group. Therefore, although the study group did show a higher rate of early stiffness, eventual functional outcome was comparable with a nonstiffness control group.     

Patellar resurfacing in total knee arthroplasty

Routine patella resurfacing in total knee arthroplasty has been debated for decades. The early total knee designs and surgical techniques lead to a high complication rate following patellar resurfacing. This lead to many surgeons abandoning this practice and either leaving the patella unresurfaced routinely or selectively resurfacing. Modern day randomized control trials and meta-analyses of these trials reveal a higher incidience of anterior knee pain and a resultant higher reoperation rate in nonresurfaced patellae. We argue that with modern day designs and surgical techniques, there is a low complication rate to resurfacing and little downside to resurfacing.     

Patellar resurfacing in total knee arthroplasty

Whether or not to resurface the patella when performing a primary total knee arthroplasty remains an open question. A number of recent studies have added new information relevant to this controversy. Anatomic studies show that there is normally substantial variability in the anatomy of the trochlear groove. Implanting a femoral component therefore results in a change in the surface topography of the knee in a high percentage of cases. Even though a number of intraoperative techniques have been described in an attempt to accurately reproduce femoral and tibial component rotation, studies of the application of these techniques reveal that component malpositioning or malrotation of a measurable degree occurs in 10% to 30% of cases, depending on the surgical technique and landmarks used. There has been substantial change in the design of both femoral and patellar components in recent years. Even with current designs, biomechanical studies indicate that some degree of change in kinematics and contact stresses occurs following total knee arthroplasty. However, the results of clinical studies have been extremely variable, with most showing either no difference or very little difference between resurfaced and nonresurfaced patellae in osteoarthritic knees. The decision to resurface the patella or not must be individualized on the basis of the surgeon's training and experience and an intraoperative assessment of the patellofemoral articulation.     

Patellar resurfacing in total knee arthroplasty

Technical errors in patellar resurfacing at the time of total knee arthroplasty (TKA) are responsible for many of the complications that affect the patellofemoral joint. Instability, patellar fracture, and wear of metal-backed patellar implants are significantly affected by errors of patellar resurfacing. A review of 50 TKAs using a condylar prosthesis and a standardized technique for patellar resurfacing was performed to evaluate the accuracy of the technique. The patients were evaluated at a mean of 2.5 years (range, two to five years) after surgery. The Hospital for Special Surgery Knee Score improved from a preoperative mean of 56 to 92 at the last evaluation. The Hospital for Special Surgery Knee Scores were excellent in 92% and good in 8%. The Knee Society Knee Score improved from a preoperative mean of 28 for pain and 49 for function to a last evaluation mean of 96 for pain and 85 for function. None of the patients had symptoms referable to the patellofemoral joint. There were no patellar fractures, dislocations, or instances of implant loosening of the patella. Roentgenograms revealed nine asymmetrically resurfaced patellae and five tilted patellae. There were no patellar subluxations. Patellar thickness was maintained at the preoperative level of 21 mm. Joint-line height was elevated 1 mm. The patellar height was decreased 2 mm from the preoperative height. Using a standard technique, satisfactory clinical results can be achieved, but minor errors in resurfacing and alignment will still occur.     

Should the patella be resurfaced in total knee arthroplasty? Efficacy of patellar resurfacing

To assess the long-term efficacy of patellar resurfacing, 100 knees were evaluated in 84 patients. The operations were performed between 1978 and 1982. The follow-up period ranged from 60 to 103 months. The diagnosis was degenerative joint disease (DJD) in 83%, rheumatoid arthritis in 12%, and miscellaneous in 5% of the knees. The implant (47 knees) and nonimplant (53 knees) groups were comparable with respect to age, body size, and length of follow-up period. The analysis revealed equivocal results. Considering all diagnostic categories combined, rest pain was marginally better in the resurfaced group (p = 0.04), but this difference resulted from an unequal distribution of subjects between mild and zero pain categories. Pain with walking, maximum walking distance, ability to climb stairs and rise from a chair, active arc of motion, extensor lag, and quadriceps strength were similar in the two groups. When the DJD group was considered separately, no significant difference emerged. There was little evidence to support a recommendation for routine patellar resurfacing in total knee arthroplasty.     

Functional improvement after knee arthroplasty without resurfacing of patella

There has been no universal agreement so far regarding the necessity of patellar resurfacing in total knee arthroplasty. As resurfacing has been reported to be associated with high incidence of complications, this practice has been avoided in our Department. A report is given on the analysis of the functional outcome of 60 knee arthroplasties without patellar resurfacing in 53 patients (7 bilateral) followed up for twelve to thirty months, with special regard to the functions closely related to patelloformal articulation. The underlying diagnosis was osteoarthritis in 78.3%, rheumatoid arthritis in 13.3%, and posttraumatic arthritis in 8.3% of the patients. Graded according to the modified knee-rating system of the Hospital for Special Surgery, excellent or good results were obtained in the case of 55 knees (91.6%) and the mean score improved from 53.6 points preoperatively to 82.6 points following arthroplasty. Subjective and objective functional assessment of stair climbing and transfer activities have shown no functional deficit attributed to the patellofemoral joint of the replaced knee.     

Patellofemoral resurfacing at total knee arthroplasty

A retrospective review of 268 primary total knee arthroplasties (TKAs) with a mean follow-up of four years is presented. The patellae were resurfaced in all cases. There were six complications (2.2%) referable to the patellofemoral articulation: three subluxations, one patellar fracture, one loosening of a metal-backed patellar component, and one patellar tendon avulsion. Successful patellofemoral resurfacing (PFR) can be accomplished with minimal complications if the following technical considerations are met: 5-7 degrees of valgus alignment; medial placement of the patellar component; taking care not to increase either the AP diameter of the knee or the thickness of the patella; avoiding internal rotation of either the tibial or femoral components and proper soft tissue balancing. A thorough review of patellofemoral complications after TKA is presented, and technical considerations relevant to the successful performance of PFR are discussed.     

The anatomic total knee resurfacing arthroplasty

The long-term results of total knee arthroplasty are largely dependent on the degree to which the implants and the technique for their insertion duplicate the normal joint anatomy, mechanics, and kinematics. Aberrations in these modalities, occasioned by technical malalignment of the joint or by nonanatomic designing, sizing, or positioning of the implants, are the predominant causes of postoperative limitation of motion and loosening of the implants. Although inadequacies in the bonding effect of cement and in the structural strength of polyethylene have been cited as contributing factors in the incidence of loosening of the tibial component, this complication occurred in less than 2% of 532 cemented Anatomic Total Knee (ATK) replacements that were available for review at a follow-up period of two to 11 years. The long-term follow-up results, based on pain relief, motion, and level of activity, were judged excellent or good in 89% of the knees. Problems related to the patella and loosening of the tibial component were the predominant mechanical complications that required revision. The incidence of loosening was routinely related to technical malalignment of the knee joint or the prosthesis. However, experimental and recent clinical studies indicate that porous-surfaced implants may provide a more durable and long-lasting mode of stabilization. Except for the adaptation of the implants to the porous-coated, noncemented technique, the ATK arthroplasty ensemble has remained essentially unchanged from the original 1972 design.     

全膝关节置换术中髌骨处理

全膝关节置换术中是否进行髌骨置换仍有争论,术后膝前疼痛及髌股关节并发症是争论的焦点.膝前疼痛是多种因素共同作用的结果,不能简单地归咎为髌骨置换与否.全膝关节置换时是否置换髌骨应考虑原发病、病变程度、假体类型及患者活动量和体重等诸多因素.如果行髌骨置换,精湛的外科技术、合适的假体是全膝关节置换术后髌股关节并发症减少的关键;如果不行髌骨置换,患者的筛选标准是保证手术疗效的关键.     

国人类风湿关节炎术中髌骨厚度的测量及置换技术的探讨

[目的] 调查国人类风湿关节炎中髌骨的厚度及解剖学特点,探讨髌骨置换术的方法和安全性.[方法] 自2005年1月～2006年1月,对59例患者95个类风湿膝关节行全膝置换术,术中测量髌骨最厚处、最薄处和髌骨截骨后骨床的厚度以及安装髌骨假体后髌骨复合物厚度,术后对患者随访,观察膝前痛和髌骨骨折的发生率.[结果] (1)截骨前髌骨的厚度测量为最高处(22.01±1.64) mm(18～26 mm),最低处为(11.69±2.33) mm(6～16 mm).(2)截骨后髌骨的骨床厚度测量结果为(13.23±0.96) mm(11～16 mm),其中11 mm 4膝(4.2%),12 mm 15膝(12.7%),13 mm 38膝(40%),14 mm 32膝(33.7%),15 mm 5膝(5.3%),16 mm 1膝(1.1%).髌骨复合物的厚度平均为21.42 mm(20～25 mm),90.5%(86/95)的髌骨厚度在术后等于或稍低于原髌骨厚度.(3)术后随访轻度膝前痛3例,无髌骨骨折或髌骨松动病例.[结论] (1)类风湿膝关节中髌骨的厚度小于国人正常髌骨厚度的均值.(2)类风湿膝关节髌骨置换时保留12～14 mm厚度的骨床是一种安全的选择.(3)类风湿膝关节置换髌骨短期随访临床疗效肯定.