A Meta-Analysis of Patellar Replacement in Total Knee Arthroplasty for Patients With Knee Osteoarthritis

Patellar resurfacing in contemporary total knee arthroplasty: Frequency of complications in a matched cohort

Introduction

Optimum patient selection and outcomes following patellar resurfacing are ongoing debates amongst the arthroplasty community. This study compared the outcomes of patients who had a total knee arthroplasty (TKA) with patellar resurfacing to those left with their native patella.

Methods

A retrospective review of 1941 TKAs performed between 2016 and 2020 was conducted. 41 TKAs without patellar resurfacing and with 2-years of minimum follow-up were identified. Of these, 38 TKAs were matched on age (exact), sex (exact), and body mass index (±10) to 38 TKAs that had patellar resurfacing. The indications for patella resurfacing were subjective based upon the surgeon preference and assessment of cartilage quality. Paired t-tests and chi-square tests were used for analysis.

Results

There was 1 major patellofemoral complication in both the resurfaced group (patellar fracture) and the non-resurfaced group (patellar tendon tear), requiring nonoperative management and revision surgery, respectively. However, in the non-resurfaced group there were 4 cases of subjective patellofemoral pain compared to none in the resurfaced group (p = 0.37). Additionally, 3 non-resurfaced patients required manipulation under anesthesia (MUA) compared to none in the resurfaced group (p = 0.44).

Discussion

There was no difference in the frequency of major patella-specific complications between the groups. However, there was a non-statistically significant trend towards increased patellofemoral pain and MUA in the non-resurfaced group. Based on this study both methods of treatment remain viable options, but the trend towards increased pain and stiffness should continue to be closely evaluated.

Patellar Resurfacing in Total Knee Arthroplasty: A Contentious Matter

Orthopaedic surgeons hold differing opinions on replacing the patella during total knee arthroplasty (TKA) for knee osteoarthritis, sparking a continued discussion on the optimal approach. Patellar resurfacing (PR) replaces the patella's surface with a prosthetic component, aiming to enhance joint function and reduce anterior knee pain. However, it has potential complications such as avascular necrosis, fractures, and patellar clunk syndrome. This analysis evaluates the effectiveness of TKA with and without PR, highlighting the variations in outcomes between the two methods. Findings suggest that resurfacing is associated with improved clinical outcomes, activity level, patient satisfaction, and pain relief. Nevertheless, the decision should be individualized based on patient preferences and circumstances. Additional long-term randomised controlled trials incorporating outcome measures specific to patellar function are required to better understand the effects of PR versus non-resurfacing in TKA.

Total knee arthroplasty without patella resurfacing leads to worse results in patients with patellafemoral osteoarthritis Iwano Stages 3-4: a study based on arthroplasty registry data

PURPOSE

To determine whether the preoperative degree of degeneration of the patellofemoral joint really affects the outcome of total knee arthroplasty (TKA) surgery without patella resurfacing and thus to establish a parameter that might serve as a guiding factor to decide whether or not to perform retropatellar resurfacing. It was hypothesized that patients with preoperative mild patellofemoral osteoarthritis (Iwano Stages 0-2) would significantly differ from patients with preoperative severe patellofemoral osteoarthritis (Iwano Stages 3-4) in terms of patient-reported outcome (Hypothesis 1) and revision rates/survival (Hypothesis 2) after TKA without patella resurfacing.

METHODS

Application of a retrospective-comparative design on the basis of Arthroplasty Registry data that included patients with primary TKA without patella resurfacing. Patients were allocated to the following groups based on preoperative radiographic stage of patellofemoral joint degeneration: (a) mild patellofemoral osteoarthritis (Iwano Stage ≤ 2) and (b) severe patellofemoral osteoarthritis (Iwano Stages 3-4). The Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC) score was assessed preoperative and 1 year postoperative (0: best, 100 worst). In addition, implant survival was calculated from the Arthroplasty Registry data.

RESULTS

In 1209 primary TKA without patella resurfacing, postoperative WOMAC total and WOMAC subscores did not differ significantly between groups, but potentially suffered from type 2 error. Three-year survival was 97.4% and 92.5% in patients with preoperative mild and severe patellofemoral osteoarthritis, respectively (p = 0.002). Five-year survival was 95.8% vs. 91.4% (p = 0.033) and 10-year survival was 93.3% vs. 88.6% (p = 0.033), respectively.

CONCLUSIONS

From the study findings, it is concluded that patients with preoperative severe patellofemoral osteoarthritis have significantly higher risks for reoperation than do those with preoperative mild patellofemoral osteoarthritis-when treated with TKA without patella resurfacing. Hence, it is recommended that patella resurfacing be applied in patients with severe Iwano Stage 3 or 4 patellofemoral osteoarthritis during TKA.

LEVEL OF EVIDENCE

III, Retrospective comparative.

Patellar resurfacing was not associated with a clinically significant advantage when a modern patellar friendly total knee arthroplasty is employed: A systematic review and meta-analysis

BACKGROUND

Modern total knee arthroplasty (TKA) femoral components are designed to provide a more optimal articular surface for the patella whether or not it has been resurfaced. Previous systematic reviews comparing outcomes of patellar resurfacing and no resurfacing combine both historic and modern designs.

AIMS

The aim of this study was to investigate the effect of patellar resurfacing in modern "patellar friendly" implants on (1) incidence of anterior knee pain, (2) patient reported outcomes (3) complication rates, and (4) reoperation rates compared with unresurfaced patellae in primary TKA.

METHODS

MEDline, PubMed and google scholar studies were evaluated using SIGN assessment tool and data analysis was conducted using Review Manager 5.2 on only randomised controlled trials. The search terms were: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, patellar retaining.

RESULTS

Thirty-two randomised controlled studies were identified that reported the type of TKA implant used: 11 used modern "patellar friendly" implants; and 21 older "patellar non-friendly" implants. Among "patellar friendly" TKAs there were no significant differences in anterior knee pain rates between resurfaced and unresurfaced groups. Patellar resurfacing with "patellar friendly" implants had significantly higher clinical (mean difference (MD) -0.77, p = 0.007) and functional (MD -1.87, p < 0.0001) knee society scores (KSS) than unresurfaced counterparts but these did not exceed the minimal clinically important difference (MCID). Resurfacing with "patellar friendly" implants was not associated with a significant (p = 0.59) difference in the Oxford knee score (OKS), in contrast when a "patellar non-friendly" implant was used there was a significant difference (MD 3.3, p = 0.005) in favour of resurfacing. There was an increased risk of reoperation for unresurfaced TKAs with "non-patellar friendly" implants (Odds ratio (OR) 1.68, 95% CI 1.03-2.74, p = 0.04), but not for unresurfaced patellae with "patellar friendly" implants (OR 1.17, CI 0.59-2.30).

CONCLUSIONS

Patellar resurfacing in combination with a modern patellar friendly implant was not associated with a lower rate of anterior knee pain, complications, or reoperations compared to not resurfacing, nor did it give a clinically significant improvement in knee specific function. In contrast patellar resurfacing in combination with a "non-friendly" TKA implant was associated with a significantly better OKS and lower reoperation rate. Implant design should be acknowledged when patellar resurfacing is being considered.

Patella resurfacing is not associated with a difference in the Oxford knee score after total knee arthroplasty but stair descent is enhanced

BACKGROUND

The primary aim was to assess the Oxford knee scores (OKS) on patients who underwent a total knee arthroplasty (TKA) with patellar resurfacing compared to those who did not. Secondary aims were to identify: (1) factors associated with resurfacing, (2) the effect of resurfacing on specific components of the OKS related to patellofemoral function, (3) the influence on patient satisfaction, and (4) whether a subgroup of patients had an improved outcome when resurfacing was undertaken.

METHODS

A retrospective cohort study was undertaken using outcome data from the arthroplasty database held at the study centre. Patient demographics and OKS were collected preoperatively and at 1 and 2 years postoperatively. Patient satisfaction was assessed at 1 and 2 years postoperatively.

RESULTS

Three thousand one hundred and twenty-two patients met the inclusion criteria of which 46.5% (n = 1453) underwent resurfacing. There were no differences in the OKS change at 1 or 2 years between those undergoing and not undergoing resurfacing (difference 0.2, p ≥ 0.469). Patients undergoing resurfacing were more likely to be female (odds ratio (OR) 1.53, 95% CI 1.30-1.79, p < 0.001), undergo a posterior stabilised knee (OR 6.87, 95% CI 5.71-8.27, p < 0.001) or had a worse response to question 5-standing from a chair, (p = 0.011) or 12-stair descent, (p = 0.017) of the OKS preoperatively. There was no difference in postoperative patient satisfaction (p ≥ 0.180). There was a significantly greater improvement in question 12 of the OKS at 1 year (p = 0.019) in the resurfaced group. There were no patient-related factors or symptoms that were associated with a clinically significant (≥ 5 points) greater postoperative OKS.

CONCLUSION

Patella resurfacing was not associated with a clinically important improvement in OKS. No specific indications for patella resurfacing were identified that offered an improved outcome, but when it was undertaken there was a greater improvement in the ability to descend stairs. Level of evidence Retrospective diagnostic study, Level III.

Does Choice of Patellar Implant in Total Knee Arthroplasty Matter?: A Randomized Comparative Trial of 3 Commonly Used Designs

BACKGROUND

There is currently a lack of evidence to identify the optimal patellar implant design in total knee arthroplasty (TKA). The aim of this study was to assess clinical, intraoperative, radiographic, and scintigraphic differences between inlay (IN), onlay round (OR), and onlay oval (OO) patellar implants.

METHODS

A parallel-group, double-blinded, randomized trial compared IN, OR, and OO patellar implants using the same posterior-stabilized TKA prosthesis for each. Patient outcomes were prospectively followed for a minimum of 2 years, with survivorship outcomes followed for a mean of 5 years. The primary outcome was the between-group differences in the mean Kujala score change from preoperatively to 2 years postoperatively. The secondary outcomes included differences in other knee-specific and general health outcomes, intraoperative characteristics, radiographic parameters, patellar vascularity, and implant survivorship.

RESULTS

A total of 121 participants (40 in the IN group, 41 in OR group, 40 in the OO group) were allocated to 1 of 3 implant designs. At 2 years postoperatively, there were no significant differences in Kujala score changes between groups (p = 0.7; Kruskal-Wallis test). Compared with the IN group, the OR group showed greater improvements in Knee injury and Osteoarthritis Outcome Score (KOOS) Activities of Daily Living and in KOOS Quality of Life compared with the OO group. However, the OO design exhibited better bone coverage and lower lateral facetectomy rates compared with the IN and OR designs. The IN group had more lateral contact compared with the OO group (p = 0.02; Fisher exact test), but the overall value for lateral contact was not significant (p = 0.09; chi-square test). There were no differences in postoperative scintigraphic vascularity (p = 0.8; chi-square test). There was 1 revision for infection at 3 years postoperatively in the OO group, and no revision in the other groups.

CONCLUSIONS

Patellar design did not influence patellofemoral outcomes or survivorship. However, OR implants showed improvements in some secondary patient-reported outcome measures, and OO implants exhibited superior bone coverage and improvements in several intraoperative, radiographic, and scintigraphic outcomes. These findings, combined with superior long-term implant survivorship from previous studies, add support for the use of onlay designs in TKA.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Patellar resurfacing in total knee arthroplasty leads to better isokinetic performance

BACKGROUND

For decades there have been concerns about patellar resurfacing (PR) in total knee arthroplasty (TKA) and the individual preference of the surgeon is still the main determinant of whether or not resurfacing is applied. According to preference, surgeons can be categorized in 3 main groups of those who usually, selectively, or rarely resurface. The aim of this prospective, randomized, controlled study was to compare the isokinetic performance and clinical outcome of TKAs with PR and without PR.

METHODS

A total of 50 patients scheduled to undergo TKA for primary osteoarthritis of the knee were randomly assigned to either the PR or non-PR groups. There were no significant differences between the groups in respect of age, BMI, gender and preoperative Knee Society Score (KSS) and isokinetic performance. Patients were evaluated at postoperative 3, 6, and 12 months with KSS and at 6 months and 1 year with isokinetic measurements.

RESULTS

The PR group had a higher mean score, especially in the functional component of KSS, but the difference was not statistically significant. Knee extension peak torque was significantly higher in the PR group at 6 months (p = 0.029) and 1 year (p = 0.004) postoperatively. There were no significant differences between the groups in respect of knee flexion peak torque values following TKA.

CONCLUSIONS

The results of this study demonstrated that PR during TKA is associated with better isokinetic performance and higher knee scores. These results support routine/usually resurfacing of the patella. For surgeons who selectively resurface the patella, the advantage of better isokinetic performance may be taking into consideration in favor of resurfacing the patella where they are undecided.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Factors associated with a clinically significant improvement in health-related quality of life after total knee arthroplasty

BACKGROUND

The aim was to identify independent preoperative factors associated with changes in health-related quality of life (HRQoL) following total knee arthroplasty (TKA), and whether these could be used as indicators for surgery.

METHODS

A retrospective study of 3127 TKA patients was undertaken that included 1194 (38.2%) male and 1933 (61.8%) female patients, with a mean age of 70.5 years (standard deviation 9.0). Patient demographics, body mass index and ASA grade, Oxford Knee Score (OKS) and EuroQol 5-dimension (EQ-5D) 3-level, which was used to assess HRQoL, were collected preoperatively and 2 years postoperatively.

RESULTS

When adjusting for confounding factors, obesity grade II (p = 0.002), ASA grade 3 (p = 0.002), and a better preoperative OKS (p < 0.001) or EQ-5D score (p < 0.001) were associated with a decreased improvement in the HRQoL at 2-years. A preoperative EQ-5D of < 0.8 (95.7% specific, AUC ≥ 67.0%) or an OKS of < 36 (97.1% specific, AUC ≥ 58.1%) was associated with a clinically significant improvement HRQoL. Patella resurfacing (n = 1454, 46.5%) was not independently associated with a clinical or statistically significant improvement in HRQoL. According to preoperative factors, no subgroup of patients benefited more from patella resurfacing according to improvement in their HRQoL.

CONCLUSION

ASA grade 3, grade II obesity, a better preoperative EQ-5D or OKS were independently associated with a lesser improvement in HRQoL. The thresholds identified in the EQ-5D or OKS for a clinically significant improvement in HRQoL may be used as potential indicators for referral for TKA. Patella resurfacing was not independently associated with a clinically important improvement in HRQoL.

LEVEL OF EVIDENCE

Retrospective diagnostic study, Level III.

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-analysis and Trial Sequential Analysis of 50 Randomized Controlled Trials

OBJECTIVE

During total knee arthroplasty, femur and tibia parts are regularly replaced, while resurfacing the patellar or not is an ongoing discussion. To compare revision rate, anterior knee pain rate, patient-reported outcome measures, complication, radiographic, and clinical outcomes after patellar resurfacing versus non-resurfacing in total knee arthroplasty.

METHODS

PubMed, Medline, EMBASE, CENTRAL, and CINAHL databases were searched on 25 April 2021 to enroll randomized controlled trials that compared patellar resurfacing versus non-resurfacing. We used the grading of recommendations assessment, development and evaluation (GRADE) framework to assess the certainty of evidence. Our primary outcome was revision rate and secondary outcomes was anterior knee pain rate. Outcomes were pooled using the random-effect model and presented as risk ratio (RR), or mean difference (MD), with 95% confidence interval (CI).

RESULTS

Fifty studies (5586 knees) were included. Significant reductions in patellar revision rate (RR 0.41, 95% CI [0.19, 0.88]; P = 0.02; I²  = 24.20%) and non-patellar revision rate (RR 0.64, 95% CI [0.55, 0.75]; P < 0.001; I²  = 0%) were seen after patellar resurfacing. Patellar resurfacing significantly reduced the anterior knee pain rate than nonresurfacing (RR 0.72, 95% CI [0.57, 0.91]; P = 0.006; I²  = 69.5%). Significant differences in patient-reported outcome measures were found. However, these differences were inconsistent and lacked clinical importance. Patellar resurfacing resulted in a significant lower rate of patellar clunk (RR 0.58, 95% CI [0.38, 0.88]; P = 0.01; I²  = 0%), a higher patellar score (MD 1.24, 95% CI [0.67, 0.81]; P < 0.001; I²  = 73.8%), but prolonged surgical time (MD 8.59, 95% CI [5.27, 11.91]; P < 0.001; I²  = 88.8%).

CONCLUSIONS

The clear relationship is that patellar resurfacing reduces revisions, anterior knee pain, and patellar clunk. It will be interesting to compare the initial cost with the revision cost when required and cost-utility analysis with long-term results in future studies.

Higher risk of knee arthroplasty during ten-year follow-up if baseline radiographic osteoarthritis involves the patellofemoral joint: a CHECK Cohort Study

Background

Patellofemoral OA is a strong risk factor for progression to generalized whole knee OA, but it is unknown whether involvement of the patellofemoral joint in early radiographic OA (ROA) is associated with risk of undergoing future knee arthroplasty. This is clinically relevant because patellofemoral OA likely requires a different treatment approach than tibiofemoral OA, and identifying prognostic factors for future arthroplasty might assist clinicians with prioritizing and guiding early interventions that could improve long-term outcomes. Therefore, we evaluated association of baseline patellofemoral or tibiofemoral ROA with undergoing knee arthroplasty over 10 years.

Methods

Using the multicenter Cohort Hip and Cohort Knee (CHECK) study, we acquired three views of radiographs in both knees of individuals aged 45–65 years with complaints of knee symptoms in at least one knee. From baseline radiographs, we categorized each knee as having one of four patterns of ROA: no ROA, isolated patellofemoral ROA, isolated tibiofemoral ROA, or combined ROA. We evaluated the 10-year relative hazard for undergoing going arthroplasty, based on baseline ROA pattern, using Cox proportional hazard models, adjusting for age, sex body mass index, and pain severity.

Result

Our sample (n = 842) included 671 (80%) women and had mean (SD) age 56 (5) years, and BMI 26.3 (4.0) kg/m². Arthroplasties were undertaken in 44/1678 knees. In comparison to having no ROA at baseline, adjusted hazard ratios (aHR) for arthroplasty were highest for combined ROA (aHR 14.2 [95% CI 5.8, 34.6]) and isolated patellofemoral ROA (aHR 12.7 [5.6, 29.0]). Isolated tibiofemoral ROA was not significantly associated with arthroplasty (aHR 2.9 [0.6, 13.6]).

Conclusions

In a sample of middle-aged individuals with complaints in one or both knees, the 10-year relative hazard for undergoing arthroplasty, compared to no ROA, was increased when OA involved the patellofemoral joint, regardless of whether it was isolated to the patellofemoral joint or occurred in combination with tibiofemoral OA. Further research is needed to confirm this association and to clarify the causal mechanism of this relationship. However, our results provide preliminary evidence that identifying patellofemoral ROA may be a clinically useful prognostic indicator in early knee OA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05549-6.

No difference between resurfaced and non-resurfaced patellae with a modern prosthesis design: a prospective randomized study of 250 total knee arthroplasties

PURPOSE

Despite numerous well-conducted studies and meta-analyses, the management of the patella during total knee arthroplasty (TKA) remains controversial. The aim of our study was to compare the clinical and radiological outcomes between patients with and without patellar resurfacing and to determine the influence of resurfacing on patellar tracking with a "patella-friendly" prosthesis.

METHODS

A single-centered prospective randomized controlled study was performed between April 2017 and November 2018. Two hundred and forty-five consecutive patients (250 knees) scheduled for TKA were randomized for patellar resurfacing or patella non-resurfacing. All patients received the same total knee prosthesis and were evaluated clinically and radiologically, including the International Knee Society Score (KSS knee and function), Forgotten Joint Score (FJS), anterior knee pain (AKP), pain when climbing stairs, patellar tilt, and patellar translation.

RESULTS

Two hundred and twenty-nine knees were available for clinical evaluation and 221 knees for radiographic analysis. The revision rate for patellofemoral cause was 3.1% (7 cases) with no difference between the groups (p = 0.217). There was no difference in survival rate between patellar resurfacing (88.3%) and non-resurfacing (85.3%) after 24 months (p = 0.599). There were no differences in KSS functional component (p = 0.599), KSS knee component (p = 0.396), FJS (p = 0.798), and AKP (p = 0.688) at a mean follow-up of 18 months. There was twice as much stair pain for the non-resurfacing group (17.1% versus 8.5%) (p = 0.043). There was patellar tilt in 43% of resurfaced knees (n = 50/116) versus 29% in non-resurfaced knees (n = 30/105) (p = 0.025); however, there was more patellar translation in the non-resurfaced group (21.0% versus 7.8%) (p < 0.001). There were no specific complications attributed to the patellar resurfacing procedure. There were four secondary patellar resurfacing procedures (3.6%) in the non-resurfaced group after a mean of 10 ± 7 months (1-17) postoperatively.

CONCLUSION

There is no superiority of patellar resurfacing or non-resurfacing in terms of clinical or radiological outcomes at mid-term. Secondary patellar resurfacing is rare. There is not enough evidence to recommend systematic patellar resurfacing with a "patella-friendly" prosthesis.

To Resurface or Not to Resurface the Patella in Total Knee Arthroplasty, That Is the Question: A Meta-Analysis of Randomized Controlled Trials

Background and Objetives: Currently, total knee arthroplasty is one of the most common surgeries, increasing with the increase in life expectancy. Whether or not to replace the patella has been a subject of debate over the years, remaining in controversy and without reaching a consensus. Over the years, different meta-analyses have been carried out in order to provide evidence on the subject, although, in recent times, there have not been many new studies in this regard. Therefore, it is considered necessary that the latest works form part of a new meta-analysis. Materials and Method: We searched the literature using PUBMED, SCOPUS, the Cochrane database and VHL from 2010 to 2020. The search terms used were “patellar” AND “resurfacing” OR “Replacement” and “no resurfacing” OR “no replacement”. A meta-analysis was performed with Stata software (Stata version 15.1). Forest plots were generated to illustrate the overall effect of knee arthroplasty interventions. Results: As a result, it was obtained that there is a significantly higher risk of suffering AKP in the non-resurfacing group, in addition to a significant increase in the risk of undergoing a reoperation in the non-resurfacing group. On the other hand, significant differences were obtained in favor of the resurfacing group in both the clinical and Feller KSS, with functional KSS being inconclusive. After analyzing different variables throughout the literature, it does seem clear that the non-resurfacing group may present a higher risk of reoperation than the resurfacing group. Conclusion: For all these reasons, we think that, although it does seem that not replacing the patella can precipitate a reoperation, it is not clear whether this reoperation is a direct consequence of not having replaced the patella. Therefore, in our opinion, the treatment must be individualized for each patient.

Management of the Patella During Total Knee Arthroplasty

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The optimal management of the patella during total knee arthroplasty (TKA) remains a controversial topic with no consensus.

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Patellar management techniques during TKA include patellar retention or resurfacing with or without patellaplasty, as well as circumferential denervation and partial lateral facetectomy (PLF).

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Special considerations such as patient age, etiology of disease, implant design, and surgeon preference should be accounted for when determining optimal management.

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We recommend that most patellae be circumferentially denervated, regardless of whether they are resurfaced, as the potential benefits outweigh the small associated risks.

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Evidence demonstrates improved functional outcomes with the addition of PLF to nonresurfaced patellae. There is currently a paucity of evidence of this technique with respect to resurfaced patellae.

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Patellar resurfacing adds additional costs and health-care resources that should be considered in the decision-making process.

Anthropometric measurements of patellar ridge using computed tomography-based three-dimensional computer models

Background

The objectives of this study were to investigate the anatomic morphology of patellar ridge using computed tomography-based three-dimensional (3D) computer models and to assess the center of the patellar ridge after virtual resections.

Methods

We selected 80 patients, 40 males (age, 33.2±6.8 years) and 40 females (age, 30.6±7.2 years), who were slightly symptomatic with soft tissue injury of the knee joint. The right or left knees were scanned by computed tomography (CT). The CT data of 160 knees was used to construct 3D computer models by image analysis software (Mimics). Variables such as the angle between the patellar ridge and patellar long axis, the distance between the center of the patellar ridge and the center of patellar cut after virtual resections were measured. We detect differences between the sides and genders with the 3D computer models by Student’s t test. Simple linear regression and correlation test was used to correlate the patellar ridge center to the center of the patellar cut.

Results

According to the available data, there were significant gender differences in the length and width of patellar cut after virtual resections even with strict control for the height and weight of the patients. The angle between the patellar ridge and the patellar long axis was 11.24° ± 3.62°. The angle in male patients was 10.17° ± 4.82°, and it was 12.28°± 3.78° in female patients. The morphological difference was statistically significant (P < 0.05). After using the subchondral method to virtually resect the patellae, with reference to the center of the patellar cut, the center of the patellar ridge lies superiorly and medially in 88.75%, inferiorly and medially in 8.75%, laterally and superiorly in 2.5%, and in no case laterally and inferiorly. The intra-observer reliability regarding the dimensional measurements was excellent in this study.

Conclusions

Advances in 3D computer models had resulted in the availability of preoperative measurement and virtual planning. The anthropometric dimensions of this study could provide general information for guiding surgical management of the patella in total knee arthroplasty (TKA) and were useful in designing patellar implants.

Clinical relevance

The placement of the patellar component during TKA differs from one patella to another. The anatomic morphology information of the patellar ridge is helpful for surgeons to perform patellar resurfacing in TKA.

Explanatory Factors for Periprosthetic Infection in Total Knee Arthroplasty

There are many studies whose results reveal possible risk factors for developing an infection after a total knee arthroplasty (TKA). The objective of this study is to analyse the risk factors that depend on the hospital and, especially, if the patellar replacement influences the appearance of periprosthetic infection. A retrospective study was performed, where data from the electronic registry of patients of people over 18 and who had undergone TKA, between the years 2015 and 2018, were reviewed. Dependent variables on the patients and the health care system were collected. The possible associations between the factors and the appearance of infection after TKA were studied using univariate and multivariate regression analyses. A total of 907 primary knee arthroplasties were included in the study. Those patients who had their patella replaced had a significantly higher risk of developing an infection (OR 2.07; 95% confidence interval 1.01–6.31). Likewise, patients who underwent surgery by surgeons with more than 10 years of experience were more than twice as likely to become infected than those operated on by younger surgeons (OR 2.64; 95%CI 1.01–6.97). Male patients were also found to be three times more likely to be infected than women (OR 2.99; 95%CI 1.32–5.74). Those interventions that were longer had a higher risk of infection. The same happened with patients who stayed in the hospital for a longer period of time. The rest of the variables did not show statistically significant results. In this study, it was found that the replacement of the patella may be a factor of infection, but it should be corroborated with randomized clinical trials. Furthermore, patients who underwent longer surgeries or those with prolonged hospital stays should be closely monitored to detect infection as soon as possible and establish the most appropriate treatment.

Clinical Trial Registry Use in Orthopaedic Surgery Systematic Reviews

BACKGROUND

Results from systematic reviews and meta-analyses, which have the highest level of evidence (Level I), often drive clinical decision-making and health policy. Often, unpublished trial data are omitted from systematic reviews, raising concerns about the extent of the reliability and validity of results that have been drawn from systematic reviews. We aimed to determine the extent to which systematic review authors include searches of clinical trial registries for unpublished data when conducting systematic reviews in orthopaedic surgery.

METHODS

Systematic reviews and/or meta-analyses were gathered from the top 5 orthopaedic surgery journals based on the h5-index from Google Scholar Metrics. Systematic reviews that had been published in the Cochrane Database of Systematic Reviews, which requires the inclusion of a clinical trial registry search, served as controls. For the primary outcome, each systematic review from the top 5 orthopaedic journals was screened to determine whether the authors of each study searched for unpublished data in clinical trial registries. We then compared the rate of registry searches with those in the control group. For the secondary analysis, a search of ClinicalTrials.gov was performed for unpublished trial data for 100 randomized systematic reviews.

RESULTS

All 38 of the Cochrane systematic reviews (100%) included clinical trial registry searches, while the top 5 orthopaedic journals had only 31 of 480 studies (6.5%) that looked at clinical trial registries. The secondary analysis yielded 59 of 100 systematic review articles (59.0%) that could have included unpublished clinical trial data from ≥1 studies to their sample.

CONCLUSIONS

Systematic reviews that have been published in the top orthopaedic surgery journals seldom included a search for unpublished clinical trial data.

CLINICAL RELEVANCE

The exclusion of clinical trial registry searches potentially contributes to publication bias within the orthopaedic literature. Moving forward, systematic review authors should include clinical trial registry searches for unpublished clinical trial data to provide the most accurate representation of the available evidence for systematic reviews and meta-analyses.

The Patellar Resurfacing in Total Knee Prosthesis: Indications for Bone Stock and Patellar Morphology

The patellar resurfacing is still a controversial and unresolved problem. The choice to use the patellar resurfacing in the total knee prosthesis (TKP) is decided by the surgeon's experience; he analyzes the thickness, the shape, consumption of the surface and he chooses the use of patellar resurfacing or to limit itself to cheiloplasty, denervation, or often to the release of the lateral wing ligament. He also assesses the metabolic state of the bone linked to Osteoporosis and the potential fragility of the joint and kneecap in particular. Bone loss after total knee arthroplasty (TKP) may lead to periprosthetic fractures that are associated with significant costs (morbidity, economic, etc.) and pose a challenge to operative fixation. The literature doesn't express a definitive judgment on the two options, since the results can be overlapped on average. Each option has advantages and disadvantages to be considered in the overall balance of the patellar operation. In reality, however, this technical choice requires more consolidated decision-making criteria so as to minimize the incidence of post-surgical femoral-patellar pain syndrome, the second cause of failure, which frequently leads to revision of the implant. The balance between experience and evidence can be a compromise in the choice of surgery. The experience documented in the literature must identify the parameters capable of constructing an algorithm aimed not only at the secondary resurfacing rate, but at the overall clinical evaluation. This has implications also for the rehabilitation of these patients after surgery.

Patellar resurfacing versus nonresurfacing in total knee arthroplasty: an updated meta-analysis of randomized controlled trials

BACKGROUND

Whether resurface the patella or not in total knee arthroplasty (TKA) was controversial. In 2013, we conducted a meta-analysis of randomized controlled trials (RTCs). After that, plenty of studies have been carried out, but there still existed a great deal of controversy. In order to update our previous study, we conducted this update meta-analysis to evaluate the efficacy of patellar resurfacing in TKA.

METHODS

Databases were searched for RCTs comparing the outcomes of patellar resurfacing and nonresurfacing in TKA. Outcomes of knee relevant indicators were analysed. To see the short- and long-term effects, we calculated the data in total and divided the patients who were followed up for ≤ 3 years and ≥ 5 years into two subgroups as well.

RESULTS

Thirty-two trials assessing 6887 knees were eligible. There was a significant difference in terms of reoperation (in total and ≥ 5 years), Knee Society Score (KSS), function score (in total and ≥ 5 years) and noise. While no significant difference was found in the following items: reoperation (≤ 3 years), anterior knee pain (AKP), function score (≤ 3 years), range of motion (ROM), Oxford score, the Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analogue score (VAS), Feller score, patellar tilt and the patients' satisfaction.

CONCLUSIONS

We found that patellar resurfacing could reduce the occurrence of reoperation and noise after surgery, as well as increase the KSS and function score, while it might not influence the outcomes such as AKP, ROM, Oxford score, KOOS, VAS, Feller score, patellar tilt and the patients' satisfaction. The results are different from our previous finding in the meta-analysis. In conclusion, we prefer patellar resurfacing in TKA.

Characteristics of three different patellar implant designs in total knee arthroplasty

BACKGROUND

Despite debate over the role of patellar resurfacing in total knee arthroplasty, many surgeons feel it decreases re-operation rates and anterior pain, and an increasing number are adopting resurfacing. This study compares intra-operative characteristics of different patellar implants to assist surgeons in gaining better understanding of these implants.

METHODS

The three most commonly used patellar implants (inset, onlay round and onlay oval) were allocated randomly to 120 patients undergoing total knee arthroplasty. We compared the groups in terms of implant size, bone coverage, lateral underhang (uncovered lateral facet) and need for partial lateral facetectomy. We also compared the patient-reported outcome measures between the groups at 6 months post-operatively.

RESULTS

The inset, onlay round and onlay oval designs had bone coverage of 48.5%, 65.9% and 85.9%, respectively (P < 0.01). Similarly, the onlay-oval implant was found to have the smallest lateral underhang of all three designs (inset 11.6 mm; onlay round 6.9 mm, onlay oval 1.6 mm, P < 0.01). The onlay-oval design was the largest implant with a median size of 35 mm, compared to 23 mm for the inset and 32 mm for the onlay round (P < 0.01). In addition, patellae using onlay-oval implants required significantly fewer lateral facetectomies due to improved bone coverage (inset 95%; onlay round 87%; onlay oval 3%; P < 0.01). Finally, comparison of patient-reported outcome measures between the groups showed no difference at an early assessment of 6 months.

CONCLUSION

Onlay-oval design allows for the use of a larger implant, improving bone coverage and reducing the need for partial lateral facetectomy; however, early assessment of outcomes shows no difference between the three designs.

Trends in Total Knee Arthroplasty in a Developing Region: A Survey of Latin American Orthopaedic Surgeons

INTRODUCTION

A number of different total knee arthroplasty techniques are available. There is also a degree of surgeon preference for these, and the variation across orthopaedic surgeons in Latin America is currently unknown.

METHODS

A survey on members of Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte was performed, with questions based on categories within worldwide national joint registries. In total, 315 Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte members received the survey via e-mail, and the return answers were compared with the latest worldwide national joint registry annual reports.

RESULTS

The survey was completed in full by 262 surgeons (83%). It was answered that 19% of surgeons perform less than 10 total knee arthroplasties per year, 54% perform less than 30, and only 9% perform more than 100. Seventy-three percent of surgeons use a posterior stabilized total knee replacement, 18% use a cruciate retaining total knee replacement, and 9% use a medial pivot design. Forty-nine percent of surgeons resurface the patella, 27% never resurface it, and 24% choose to resurface it based on an individual case scenario. Ninety-eight percent of surgeons use cemented fixation in the femur and tibia, with the remaining 2% choosing hybrid fixation and 1% using fully noncemented fixation.

CONCLUSION

This survey among Latin American surgeons has demonstrated important differences in surgical technique and implants choice compared with worldwide national registries.

Effect of Patellar Resurfacing on Clinical Outcomes, Range of Knee Motion and Anterior Knee Pain in Patients with Total Knee Arthroplasty

Objectives: In this study, we retrospectively compare the clinical results, range of knee motion and anterior knee pain in patients on whom we performed knee arthroplasty with and without patellar resurfacing.

Thirty-eight patients were evaluated in the study. Knee Society scores, knee range of motion and anterior knee pain before and 12 months after surgery were detected. Patients were divided into two groups: resurfaced patellas and nonresurfaced patellas. There were 18 patients in the resurfaced group and 20 patients in the nonresurfaced group.

Mean Knee Society score was 40.72±13.09 in the resur-faced group and 38.55±5.88 in the nonresurfaced group before surgery. Mean Knee Society score was 80.38±7.78 in the resur-faced group and 80.10±3.22 in the nonresurfaced group in the last control. Mean knee range of motion was 92.83±12.12 degrees in the resurfaced group and 91.05±10.10 degrees in the nonresurfaced group before surgery. Mean range of motion was 106.22±9.13 degrees in the resurfaced group and 97.25±8.50 degrees in the nonresurfaced group after surgery. There were twelve patients with anterior pain before surgery in the resur-faced group and 13 patients with anterior knee pain before surgery in the nonresurfaced group. After surgery, there was one patient with anterior pain in the resurfaced group and 9 patients with anterior knee pain in the nonresurfaced group.

Anterior knee pain ratio was smaller in the resurfaced group than in the nonresurfaced group, and there was a significant difference in range of knee motion as a result of our study. We offered to resurface the patella.

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The management of the patella during total knee arthroplasty (TKA) remains controversial. The aim of this study is to evaluate the evidence regarding the use of patellar resurfacing in TKA.

METHODS

A meta-analysis of randomized controlled trials (RCTs) was performed to compare outcomes between knees receiving patellar resurfacing vs those not receiving resurfacing during primary TKA. Outcomes of interest were the Knee Society Scores, reoperation rates, anterior knee pain, patient satisfaction, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score subscores, and range of motion.

RESULTS

Twenty RCTs met all eligibility criteria and were included in the analysis. There were statistically significant differences favoring the resurfaced group in the knee component and functional component of Knee Society Scores that were not clinically significant. There was an increased risk of reoperation among knees that did not receive resurfacing with number needed to treat to prevent one case of reoperation of 25 knees (for reoperation for any reason) and 33 knees (for reoperation for anterior knee pain). There were no statistically significant differences in any other outcomes.

CONCLUSION

The only clear relationship is that knees that do not receive patellar resurfacing are more likely to receive reoperation, most often for secondary resurfacing. However, the disease burden of differing complication profiles associated with resurfacing and nonresurfacing groups remains unclear. Continuing to collect data from large, well-designed RCTs would be beneficial in guiding management of the patella during TKA.

Better outcomes with patellar resurfacing during primary total knee arthroplasty: a meta-analysis study

BACKGROUND

Total knee arthroplasty (TKA) is a feasible and cost-effective procedure. However, resurfacing of the patella sparks a heated debate. Anterior knee pain after TKA was supposed to be correlated to the patellofemoral joint, and the resurface of the patella was believed to be effective to avoid this complication.

AIM

A meta-analysis was performed to update current evidence concerning the outcomes of patellar resurfacing versus retaining for total knee arthroplasty. The first outcomes of interest were to compare the rate of anterior knee pain and revision surgeries.

MATERIAL AND METHODS

This study was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA). A comprehensive review of the literature was conducted accessing the main databases: Embase, Google Scholar, PubMed, Scopus. All the prospective clinical trials comparing the outcomes between patellar resurfacing versus retaining were included in this study. Only articles classified as level of evidence I to II were considered for inclusion. Only studies reporting a minimum 24 months follow-up were included. The following data were extracted: demographic baseline, anterior knee pain, reoperations, clinical scores (HSS, KSS and related subscales) and range of motion (ROM). Studies solely reporting quantitative data under the outcomes of interest were included.

RESULTS

In favor of the resurfacing group, we observed a statistically significant reduced rate of anterior knee pain (odd ratio 1.73) and reoperation (odd ratio 3.24). In the resurfacing group, a prevalence of anterior knee pain of 11.15% was detected, whereas in the retaining group it amounted to 17.39%. Furthermore, a greater KSS pain (+ 0.97%), KSS clinical (+ 0.23%), KSS functional (+ 2.44%), KSS overall (+ 2.47%) and HSS (+ 5.64%) were reported. In the retaining group, we found a better range of motion (+ 3.09°).

CONCLUSION

Based on the main findings of this meta-analysis, patellar resurfaced TKA was demonstrated to have performed superior overall. Patellar resurfacing detected a lower rate of postoperative anterior knee pain and reoperation. Moreover, the resurfacing group showed greater value of the HSS, KSS and related subscales. In favor of the retaining group, a slightly better ROM was evidenced.

LEVEL OF EVIDENCE

Level II, meta-analysis of prospective clinical trials.

The Effect of Surgeon Preference for Selective Patellar Resurfacing on Revision Risk in Total Knee Replacement: An Instrumental Variable Analysis of 136,116 Procedures from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

The optimum strategy regarding resurfacing the patella in total knee replacement (TKR) remains debated, with wide national and international variability. To minimize the confounders of a direct comparison of cases with or without resurfacing, we performed an instrumental variable analysis examining revision risk on the basis of surgeon preference for patellar resurfacing in TKR, specifically examining the subsequent patellar revision risk and all-cause revision risk among cases of surgeons preferring to perform resurfacing on a selective basis compared with those whose preference is to routinely resurface or who infrequently perform resurfacing.

METHODS

Data from the Australian Orthopaedic Association National Joint Replacement Registry from 1999 to 2016 were obtained to assess the cumulative percent revision, hazard ratio, and revision diagnoses for 3 cohorts, grouped according the surgeons' patellar-resurfacing preferences: infrequently (<10% of the time), selectively (10% to <90% of the time), or routinely (≥90% of the time). To avoid confounding from implant design or surgeon performance, only minimally stabilized TKRs using hybrid or cemented fixation and performed by surgeons performing ≥50 TKR procedures per year were included.

RESULTS

A total of 136,116 procedures were included, with patients in all 3 cohorts having similar demographics. The selectively resurfaced cohort had a higher patellar revision risk compared with the routinely resurfaced cohort, with this risk being greatest in the first 4.5 years following the primary procedure, including 306% higher in the first 1.5 years, and remaining 50% higher after 4.5 years. In a subgroup analysis, increased revision risk was observed among males, females, those <65 years of age, and those ≥65 years of age. The infrequently resurfaced cohort had the highest risk of subsequent patellar revision, up to 482% higher, as seen in the first 1.5 years after the primary procedure, compared with the routinely resurfaced cohort. Additionally, the risk of all-cause revision was 20% higher for the selectively resurfaced cohort compared with routinely resurfaced.

CONCLUSIONS

Surgeons who preferred selective resurfacing of the patella had a higher risk of patellar revision than those who had preference for routine resurfacing of the patella. Overall, a greater preference for resurfacing resulted in a lower risk of patellar revision.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Resurfacing versus not-resurfacing the patella in one-stage bilateral total knee arthroplasty: a prospective randomized clinical trial

Purpose

Resurfacing the patella in one-stage bilateral total knee arthroplasty (TKA) remains debatable. This study aimed to assess the mid-term outcomes of patients after one-stage bilateral TKA performed with and without patellar resurfacing, respectively, with at least five years of follow-up.

Methods

Sixty-six patients (132 knees) scheduled for first-ever one-stage bilateral TKA due to osteoarthritis received patellar resurfacing and retention, respectively, on one knee and the other, randomly selected. All patients received Scorpio NRG knee prostheses and were evaluated by radiology (anteroposterior, lateral, and axial views) pre-operatively and yearly post-operatively, for at least five years. Knee Society Score and Feller Score values were measured. Anterior knee pain, patellar clunk, and patient satisfaction were assessed.

Results

One patient died within five years of operation and four were lost to follow-up. One patient developed severe dementia and could not be constructively questioned. Therefore, 60 patients (120 knees) were finally analyzed. There were significantly improved Knee Society and Feller scores (P < 0.001) in the resurfacing group compared with the non-resurfacing group post-operatively. Anterior knee pain and patellar clunk rates were lower on the resurfaced side compared with the non-resurfaced side (P < 0.001). Meanwhile, 47% and only 7% patients preferred the resurfaced and non-resurfaced sides, respectively, at final follow-up. No revision was performed for patellofemoral complications, and no significant differences were found between the two groups in radiographic outcomes.

Conclusions

Using the Scorpio NRG knee prosthesis, patellar resurfacing is superior to non-resurfacing in patients with osteoarthritis observed for ≥ five years.

Registration trials number

NCT03600922

Key Points

• Findings Patellar resurfacing is superior to non-resurfacing in osteoarthritis (OA) patients undergoing total knee arthroplasty (TKA) with the Scorpio NRG knee prosthesis.

• Implications Patellar resurfacing should be performed in OA patients during TKA.

• Caution Several prosthesis types should be assessed in the same study setting, and multicenter studies are required before generalizability of the present findings.

Electronic supplementary material

The online version of this article (10.1007/s00264-019-04361-7) contains supplementary material, which is available to authorized users.

Therapeutic efficacy of extracorporeal shock wave combined with hyaluronic acid on knee osteoarthritis

This retrospective study investigated the efficacy and safety of extracorporeal shock wave (EPSW) combined with hyaluronic acid (HA) for patients with knee osteoarthritis (KOA).This retrospective study included 70 patients with KOA. Of those subjects, 35 of them received EPSW combined HA, and were allocated to a treatment group, while the other 35 participants received HA alone and were allocated to a control group. Patients in both groups were treated for a total of 8 weeks. The primary outcome was measured by visual analog scale (VAS). The secondary outcomes were measured by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and knee injury and osteoarthritis outcome score (KOOS). In addition, adverse events (AEs) were also evaluated. All outcomes were measured before and after the treatment.After the treatment, patients in the treatment group exhibited better efficacy in VAS (P < .01), WOMAC scale (pain, P < .01; function, P < .01; and stiffness, P < .01), and KOOS scores (pain, P < .01; function in daily living, P < .01; symptoms, P < .01; sport and recreation, P < .01; and quality of life, P < .01), than patients in the control group. In addition, no significant differences regarding the AEs were found between 2 groups.The findings of this study demonstrated that the efficacy of EPSW combined with HA is superior to the HA alone for patients with KOA.