Secondary patellar resurfacing in the treatment of patellofemoral pain after total knee arthroplasty

What are the Outcomes of Secondary Patella Resurfacing for Dissatisfaction Following Primary Knee Arthroplasty? A Systematic Review and Meta-Analysis of 604 Knees

BACKGROUND

Secondary patella resurfacing is often performed for dissatisfaction following primary knee arthroplasty where the native patella was retained. The purpose of this meta-analysis was to evaluate outcomes of secondary patella resurfacing.

METHODS

The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies reporting on patients who underwent secondary patella resurfacing after previous primary knee arthroplasty with retention of the native patella were considered eligible. The risk of bias was assessed using the Methodological Index for Non-Randomized studies tool. A random-effects model and the inverse-variance weighting method was used for meta-analysis. There were sixteen retrospective studies including 604 knees (594 patients) with a mean follow up of 42 months (range, 2 to 197).

RESULTS

An overall improvement in patient-reported outcomes (PROMs) was achieved in 53% of cases from pooled data available for 293 knees [95% Confidence Interval (CI) (0.44, 0.62), I2=68% - moderate heterogeneity]. The pooled proportion of patients satisfied with the procedure was 59% [95% CI (48, 68), I2 = 70% - moderate heterogeneity] in a sample size of 415. There was a minimal rate (2%) of complication incidence when performing secondary patella resurfacing and a pooled rate of revision surgery of 10%.

CONCLUSIONS

An improvement in pain, satisfaction, and PROMs was achieved in slightly more than half of the patients following secondary patella resurfacing. However, studies lacked standardized objective selection criteria for the procedure and the available data was predominantly retrospective, with high heterogeneity and variation in outcome reporting.

The Fate of Unresurfaced Patellae in Contemporary Total Knee Arthroplasty: Early to Midterm Results

BACKGROUND

Leaving the patella unresurfaced in total knee arthroplasty (TKA) has increased significantly over the past decade in the United States, likely due to modern patella-friendly implants, complications with resurfacing, and the knowledge that historical studies were scientifically confounded. This study evaluated revision-free survivorship out to 8.5 years in a cohort of contemporary primary TKAs with patella-friendly femoral components and unresurfaced patellae.

METHODS

A total of 1,053 consecutive primary TKAs with unresurfaced patellae were retrospectively reviewed. A selective patellar nonresurfacing protocol was used for all cases. Kaplan-Meier survivorship estimates were calculated based on patellar revision and the latest follow-up. An aggressive lateral patellar facetectomy was performed in 78% (823 of 1,053) of cases. The cohort was 62% women and 43% American Society of Anesthesiologists physical status classification I or II with a mean age and body mass index of 65 years (range, 35 to 94) and 35 kg/m2 (range, 18 to 65), respectively.

RESULTS

A total of 4 (0.4%, 4 of 1,053) unresurfaced patellae were revised. Three were resurfaced as part of other procedures: 2 for global instability and one for aseptic loosening at a mean of 1.6 years; and one patella was resurfaced by an outside surgeon for unexplained pain. The all-cause revision-free survivorship estimate specifically related to the patella was 98.9% (95% confidence interval, 98 to 100) out to 8.5 years. No significant difference in survivorship was related to patellae with or without a lateral patellar facetectomy (99.5 versus 98.1%, P ≥ .191); however, 3 of 4 patellar revisions occurred in TKAs without a lateral patellar facetectomy (P = .035).

CONCLUSIONS

The results of this study demonstrate excellent revision-free survivorship related to unresurfaced patellae, particularly when a lateral facetectomy was performed. These early to midterm results using modern patella-friendly femoral components are promising and comparable to resurfaced patellae in the literature.

LEVEL OF EVIDENCE

IV.

Higher failure rate of secondary patellar resurfacing following bicompartmental knee arthroplasty

INTRODUCTION

The role of secondary patellar resurfacing (SPR) in anterior knee pain (AKP) is still debated in literature. A regional arthroplasty registry was investigated, aiming to: (1) assess the survival rate of SPR; and (2) compare SPR to tricompartmental TKA.

MATERIALS AND METHODS

The regional arthroplasty registry RIPO was investigated about all SPRs performed after bicompartmental arthroplasty. The survival rates and the reasons for revision were assessed as any other factor that could have influenced implants failure. SPR survivorship was compared to tricompartmental TKAs.

RESULTS

406 SPRs performed after bicompartmental arthroplasty were analyzed. The survival rates were 80.6% (CI 95% 75.9-84.5) at 5 years and 77.6% (CI 95% 72.4-82) at 7 years. Half of the SPRs was performed 0.9-2.4 years after the index bicompartmental arthroplasty. SPR achieved lower survival than tricompartmental TKA (80.6% vs 96.7%, p < 0.001), with an adjusted hazard ratio for failure of 5.5 (CI 95% 4.2-7.1, p < 0.001). SPRs performed within 2 years after primary implant had a significantly higher rates of failure when compared to tricompartmental TKA (HR: 6.4, CI 95% 4.8-8.4, p < 0.001).

CONCLUSION

SPR after bicompartmental knee arthroplasty showed modest 5- and 7-year survival rates, worse than primary tricompartmental TKA. When SPRs are performed within 2 years after primary arthroplasty, a significant higher risk of failure should be expected, highlighting than appropriate pre-operative work-up and patient selection is crucial for SPR successful outcome.

LEVEL OF EVIDENCE

III, therapeutic study.

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.

Management of the Patella During Total Knee Arthroplasty

»

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

»

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

»

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

»

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

»

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.

»

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

Age and Prosthetic Design as Risk Factors for Secondary Patella Resurfacing

BACKGROUND

Selectively resurfacing the patella based on a patient's risk of secondary patella resurfacing (SPR) may be the optimal strategy for primary total knee arthroplasty (TKA). However, exactly which factors increase the risk of SPR is unknown. Utilizing New Zealand Joint Registry data, we investigated the following: (1) What patient and surgical factors are more prevalent among TKA patients who received SPR compared to those who did not? and (2) What is the difference in Oxford Knee Scores (OKS) between those who receive SPR and those who do not?

METHODS

Prevalence of various patient and surgical factors was compared between 197 non-resurfaced TKAs that proceeded to SPR and 31,399 that did not. Multivariate analysis was used to determine the odds ratio for each factor that differed between groups. Six-month postoperative OKS for each group was utilized for comparison.

RESULTS

Posterior-stabilized designs had an odds ratio of 1.86 (95% confidence interval [CI] 1.31-2.66; P = .001) when compared to cruciate-retaining designs. When compared to age less than 55, age >75 and age 65-74 had odds ratios of 0.27 (95% CI 0.16-0.46; P < .001) and 0.44 (95% CI 0.28-0.69; P < .001) respectively. Six-month OKS was lower among those who received SPR (37.27 vs 27.26; P < .001).

CONCLUSION

Younger age, posterior-stabilized design, and a low 6-month OKS were associated with SPR.

Usually, Selectively, or Rarely Resurfacing the Patella During Primary Total Knee Arthroplasty: Determining the Best Strategy

BACKGROUND

Surgeons may "usually" resurface the patella during total knee arthroplasty (TKA), "rarely" resurface, or "selectively" resurface on the basis of certain criteria. It is unknown which of these 3 strategies yields superior outcomes. Utilizing New Zealand Joint Registry data, we investigated (1) what proportion of surgeons employs each of the 3 patellar resurfacing strategies, (2) which strategy is associated with the lowest overall revision rate, and (3) which strategy is associated with the highest 6-month and 5-year Oxford Knee Score (OKS).

METHODS

Two hundred and three surgeons who performed a total of 57,766 primary TKAs from 1999 to 2015 were categorized into the 3 surgeon strategies on the basis of how often they resurfaced the patella during primary total knee arthroplasty; with "rarely" defined as <10% of the time, "selectively" as ≥10% to ≤90%, and "usually" as >90%. For each strategy, the cumulative incidence of all-cause revision was calculated and utilized to construct Kaplan-Meier survival curves. The mean 6-month and 5-year postoperative OKS for each group were utilized for comparison.

RESULTS

Overall, 57% of surgeons selectively resurfaced, 37% rarely resurfaced, and 7% usually resurfaced. The usually resurfacing group was associated with the highest mean OKS at both 6 months (38.57; p < 0.001) and 5 years postoperatively (41.34; p = 0.029), followed by the selectively resurfacing group (6-month OKS, 37.79; 5-year OKS, 40.87) and the rarely resurfacing group (6-month OKS, 36.92; 5-year OKS, 40.02). Overall, there was no difference in the revision rate per 100 component years among the rarely (0.46), selectively (0.52), or usually (0.46) resurfacing groups (p = 0.587). Posterior-stabilized TKAs that were performed by surgeons who selectively resurfaced had a lower revision rate (0.54) than those by surgeons who usually resurfaced (0.64) or rarely resurfaced (0.74; p < 0.001).

CONCLUSIONS

Usually resurfacing the patella was associated with improved patient-reported outcomes, but there was no difference in overall revision rates among the 3 strategies.

LEVEL OF EVIDENCE

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

The outcome of secondary resurfacing of the patella following total knee arthroplasty: Results from the Trent and Wales Arthroplasty Register

BACKGROUND

We sought to determine whether patients undergoing secondary patella resurfacing (SPR) benefited from the procedure by assessing postoperative satisfaction via a postal questionnaire.

METHODS

All such patients included in the Trent and Wales Arthroplasty Register were invited to participate using patient-reported outcome measures (PROMs). We identified 223 patients who had undergone SPR over a 20-year period. Forty-two had died according to death register checks. Eighty-eight of 181 (48.6%) questionnaires were completed. The mean age at resurfacing was 67 (min. 42, max. 81); 52% were female. The median time to follow-up was 55months (interquartile range (IQR) 41-111). Median time to SPR was 28months (IQR 20-42).

RESULTS

Thirty-nine patients (44%) felt that SPR resolved the problem of pain in the front of their knee. All PROMs were significantly better for those who felt that the resurfacing had worked (Oxford Knee Score 29 vs. 16, P<0.05, modified Kujala 51 vs. 32, P<0.05, EQ5D-3L 0.616 vs. 0.384, P<0.05). Based on PROMs, SPR produces a satisfactory outcome in two of every five patients.

CONCLUSIONS

Surgeons must be clear on the cause of anterior knee pain post-total knee replacement, and patients must be made aware of what outcomes can be reasonably expected from this procedure.

The predictive factors of secondary patellar resurfacing in computer-assisted total knee arthroplasty. A prospective cohort study

PURPOSE

The decision to resurface the patella during total knee arthroplasty (TKA) remains controversial. This prospective cohort study aimed to evaluate the outcome and survivorship of the native patella in computer-assisted TKA (CAS TKA) implanted for primary knee osteoarthritis, and to determine the predictive factors of secondary patellar resurfacing (SPR).

METHODS

A prospective cohort of 273 cementless ultra-congruent mobile-bearing CAS TKA implanted without patellar resurfacing was included in our total joint registry. Patients were evaluated with the International Knee Society (IKS) and Hospital for Special Surgery Patellar (HSSP) scores. Radiographic evaluation was focused on the patellofemoral (PF) compartment to assess: the patellar dysplasia (Wiberg classification), PF osteoarthritis (Iwano classification), femoral trochlear dysplasia (femoral sulcus angle), patellar maltracking (patellar tilt and lateralization), and patella height (Blackburne-Peel ratio).

RESULTS

At a six-year median follow-up, the CAS TKA survivorship using SPR as end-point was 95% (range, 91-99%). The IKS and HSSP improved significantly after SPR (p = 0.001 and 0.004, respectively). No significant difference in the IKS and HSSP was detected between TKA with native patella and SPR-TKA at latest follow-up. Importantly, four pre-operative radiographic PF parameters were significantly associated with SPR: higher stages of patellar dysplasia and PF osteoarthritis, and higher sulcus angle and patellar lateralization (hazard ratios = 5.1 to 11.6, p = 0.009 to 0.04).

CONCLUSION

When preserving the native patella, surgeons should be aware of pre-operative PF radiographic parameters that could influence the outcome and survivorship of CAS TKA leading to SPR. Particularly, evidence of PF dysplasia, osteoarthritis and maltracking should be determined pre-operatively to resurface the patella at the time of TKA.

LEVEL OF EVIDENCE

Therapeutic Level II (prospective cohort study).

Patient Satisfaction and Functional Outcomes Following Secondary Patellar Resurfacing

When secondary patellar resurfacing is performed, a uniformly and widely used scoring system that is validated for anterior knee pain caused by a retropatellar degeneration will give more insight into the results of this procedure. The cause of anterior knee pain following total knee arthroplasty (TKA) is not always related to the patella itself. Other causes have been identified, such as an insufficient posterior cruciate ligament in the case of a posterior cruciate-retaining TKA or an internally rotated femoral and/or tibial component. Treatment of anterior knee pain following primary TKA with secondary patellar resurfacing is a controversial procedure with uncertain outcomes. The purpose of this study is to systematically review the available peer-reviewed literature on patient satisfaction and functional outcomes of secondary resurfacing. The authors performed a systematic computerized database search of the Cochrane Database of Systematic Reviews, MEDLINE, and EMBASE in October 2014. The quality of the included studies was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. A total of 15 articles met the inclusion criteria. In total, 148 (64%) of 232 patients were satisfied with the outcomes of secondary patellar resurfacing. A statistically significant improvement in knee scores was noted in all 9 studies that reported functional outcomes, although no clinically significant improvement in knee scores was observed. Reported complications include infections and impaired wound healing, patellar instability, and patellar fracture. Because the available evidence is of generally low quality, the results of this systematic review only support a weak recommendation for secondary patellar resurfacing if patient satisfaction and clinically important improvement of functional outcomes are the desired endpoints. [Orthopedics.2016; 39(5):e850-e856.].

Secondary Patellar Resurfacing as a Rescue Procedure for Persistent Anterior Knee Pain After Primary Total Knee Arthroplasty: Do Our Patients Really Improve?

BACKGROUND

Secondary patellar resurfacing (SPR) is a procedure that can be used in patients with persistent anterior knee pain (AKP) after a primary total knee arthroplasty. The aim of our study was to analyze the clinical and functional outcomes as well as the complications of this procedure and identify predictive factors for a favorable outcome.

METHODS

Forty-six patients who underwent SPR for persistent AKP after primary total knee arthroplasty were retrospectively studied. The patient's mean age was 68 years (range, 36-86 years). The average follow-up time after SPR was 74 months (range, 24-197 months). Demographic data, Knee Society Score scale, range of motion, pain improvement (Visual Analogue Scale), overall satisfaction, and complications were recorded. The statistical analysis was performed using STATA tm/SE v10.

RESULTS

There was an improvement of the Knee Society scale (from 54 ± 11 to 64 ± 16 points; P < .05). However, in 59% of the cases, there was no pain improvement, and 65% of patients were not satisfied. Four patients showed complications, and in 2 cases, reoperation was necessary. We did not find any preoperative predictive factor for a favorable outcome after SPR.

CONCLUSION

Despite improvement of the Knee Society scale, many patients continue with AKP and are dissatisfied with this procedure; therefore, we do not recommend it in this clinical scenario.

Secondary patella resurfacing in painful non-resurfaced total knee arthroplasties : A study of survival and clinical outcome from the Norwegian Arthroplasty Register (1994-2011)

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.

Proximalize osteotomy of tibial tuberosity (POTT) as a treatment for stiffness secondary to patella baja in total knee arthroplasty (TKA)

INTRODUCTION

Stiffness after a total knee arthroplasty (TKA) is one of the most common post-operative complications. The purpose of this study is the evaluation of the effectiveness of TT proximalization osteotomy of improving a lack of flexion and secondary pain in patella baja (infera) post-TKA.

MATERIALS AND METHODS

Between April 2007 and July 2012, TT proximalization osteotomy was performed on 21 patients. The average preoperative flexion was 70° (in a range of 60-80). Clinical pre- and post-operative evaluations were performed with Knee Society Score, Western Ontario and McMaster Universities Arthritis Index scales and a satisfaction survey. Modified Blackburn-Peel index and Portner angle were used to evaluate patellar height.

RESULTS

After an average follow-up of 35 months (range 18-48), an average flexion of 100° (range 90-100) and an overall satisfaction were obtained. Clinical scores improved significantly. The Blackburn-Peel index and Portner angle improved significantly from 0.3 (range 0.1-0.5) to 0.4 (0.3-0.5) and from 9 (3-15) to 12 (9-18), respectively. Three patients showed no signs of osteotomy consolidation. However, this was not linked to a lack of extension or an increase in local pain.

CONCLUSION

TT proximalization osteotomy provides satisfactory results in improving a lack of flexion and pain in patella baja post-TKR.

Update on the etiology of revision TKA -- Evident trends in a retrospective survey of 1449 cases

BACKGROUND

A working and complete knowledge of the different causes of dysfunction and pain after TKA is essential for the ability to correctly determine the cause of failure and to address this problem specifically. The purpose of this study was to update the etiology of implant failure. New diagnosis and current trends should be displayed.

METHODS

All TKA revisions performed in our institution between 2001 and 2010 were reviewed retrospectively. Patient demographics and the precise indication for the surgery were documented. Descriptive statistical analyses and association analyses of both the diagnosis and patient demographics were performed.

RESULTS

Within our collective of 1449 revision TKA a total of 40 different pathologies leading to revision surgery were identified and categorized. Overall 68.5% of the revisions were categorized aseptic, 31.5% as septic implant failure. Some recently debated diagnoses like low-grade-infection showed a high increase in incidence whereas classic failure mechanisms like polyethylene wear showed a decrease over the time.

CONCLUSION

We believe that this study successfully updates the current knowledge of different failure mechanisms in revision TKA, which have to be considered on dysfunction or pain after surgery. We were able to evaluate the clinical relevance of each pathology and could shift from implant related problems like wear to more surgical problems like instability and or malalignment over the last years. With a higher alertness to chronic low-grade-infections the incidence of infection is even increasing.

LEVEL OF EVIDENCE

Level II, economic and decision analysis.

Prospective evaluation of anatomic patellofemoral inlay resurfacing: clinical, radiographic, and sports-related results after 24 months

PURPOSE

To prospectively evaluate the clinical, radiographic, and sports-related outcomes at 24 months after isolated and combined patellofemoral inlay resurfacing (PFIR).

METHODS

Between 2009 and 2010, 29 consecutive patients with patellofemoral osteoarthritis (OA) were treated with the HemiCAP(®) Wave Patellofemoral Resurfacing System (Arthrosurface, Franklin, MA, USA). Based on preoperative findings, patients were divided into two groups: group I, isolated PFIR (n = 20); and group II, combined PFIR with concomitant procedures to address patellofemoral instability, patellofemoral malalignment, and tibiofemoral malalignment (n = 9). Patients were evaluated preoperatively and at 24 months postoperatively. Clinical outcomes included WOMAC, subjective IKDC, Pain VAS, Tegner activity score, and a self-designed sports questionnaire. Kellgren-Lawrence grading was used to assess progression of tibiofemoral OA. The Caton-Deschamps Index was used to assess differences in patellar height.

RESULTS

Twenty-seven patients (93 %) were available for 24-month follow-up. Eighty-one per cent of the patients were either satisfied or very satisfied with the overall outcome. Significant improvements in the WOMAC, subjective IKDC, and Pain VAS were seen in the overall patient cohort and in both subgroups. The median Tegner score and sports frequency showed a significant increase in the overall patient cohort and in group II. The number of sports disciplines increased significantly in both subgroups. No significant progression of tibiofemoral OA or changes in patellar height were observed.

CONCLUSION

Patellofemoral inlay resurfacing is an effective and safe procedure in patients with symptomatic patellofemoral OA. Significant improvements in functional scores and sports activity were found after both isolated and combined procedures.

LEVEL OF EVIDENCE

Prospective case series, Level III.

Secondary patellar resurfacing following total knee arthroplasty : A cohort study in fifty eight knees with a mean follow-up of thirty one months

PURPOSE

If anterior knee pain (AKP) emerges or persists following total knee arthroplasty (TKA), secondary patellar resurfacing (SPR) may offer relief of AKP. The purpose of our study was to evaluate the mid-term clinical outcomes after secondary patellar resurfacing for persistent AKP. Secondary objectives were to correlate surgical outcomes with clinical and radiological parameters including 99 m-technetium bone scintigraphy.

METHODS

In this study, 57 patients (58 knees, 51 women and 6 men) with a mean age of 70 years at the time of SPR were included. Patients were asked about their satisfaction regarding the outcome of the procedure. Patellar position was assessed by axial radiographs, and we reassessed the preoperatively performed bone scintigraphy.

RESULTS

After a median follow-up of 31 (6-76) months, 42 patients (43 knees) were satisfied and 15 were dissatisfied regarding the outcome of the procedure. Dissatisfied patients had more often a shorter time interval between TKA and SPR, patellar tilt on axial radiographs, and a 'hot' bone scan.

CONCLUSION

In patients with persistent AKP following TKR, secondary resurfacing leads to patient satisfaction in a relatively large number of patients. Better results were seen in patients without tilting of the patella. The added value of a bone scan as an indicator to perform SPR is not clarified in the present study.

Lateral patellar facetectomy and medial reefing in patients with lateral facet syndrome after patellar-retaining total knee arthroplasty

We analyzed clinical outcomes of partial lateral patellar facetectomy and medial reefing in patients with lateral patellar facet syndrome with painful patellar-retaining total knee arthroplasty. 34 patients were followed for a mean of 40 months. All 34 patients were matched with those having secondary patellar resurfacing without facetectomy. Both groups experienced significant pain relief and range of motion improvement. The facetectomy group had higher Kujala scores than those in patellar resurfacing group. Patients with facetectomy had significantly less pain postoperatively. There were significant differences in postoperative lateral patellar tilt and congruency angle in both groups. The mid-term results for LPF with medial reefing are promising to resolve pain in patients with lateral patellar facet syndrome in patellar-retaining TKA. Therapeutic level III (retrospective comparative study).

Less anterior knee pain with a routine lateral release in total knee arthroplasty without patellar resurfacing: a prospective, randomized study

PURPOSE

Anterior knee pain is a major cause of complaint in total knee arthroplasty (TKA) without patellar resurfacing. The concept of improved patellar tracking and decreased retropatellar contact pressure for lateral retinacular release theoretically suggests that patients with lateral retinacular release in TKA would achieve a lower incidence of anterior knee pain when compared without lateral retinacular release. We sought to determine (1) whether those patients who received a routine lateral retinacular release in TKA would attain lower incidence of anterior knee pain as compared to patients who received TKA without lateral retinacular release and (2) whether lateral retinacular release would increase the lateral retinacular release-related complications.

METHODS

A total of 148 patients who underwent TKA with the use of the Gemini MK II mobile bearing were randomized to receive either routine lateral retinacular release (intervention group) or not (control group). Patients were assessed by the visual analogue scale for anterior knee pain, the Knee Society clinical scoring system of knee score and function score, and patellar score for clinical function. Patients' satisfaction and lateral retinacular release-related complications were also evaluated.

RESULTS

The overall incidence of anterior knee pain in the intervention group at 18 months follow-up was 5.6%, while that of the control group was 20.6% (p = 0.009). No statistical difference was detected between the two groups in terms of lateral retinacular release-related complications (n.s.), patients' satisfaction (n.s.), knee score (n.s.), function score (n.s.), and patellar score (n.s.) at 18 months follow-up.

CONCLUSION

The present study suggests that routine lateral retinacular release can reduce anterior knee pain and does not increase lateral retinacular release-related complications, in TKA with the use of the Gemini MK II mobile bearing without patellar resurfacing.

LEVEL OF EVIDENCE

Therapeutic, Level I.

Anterior knee pain after total knee arthroplasty: a narrative review

Anterior knee pain is one of the most common causes of persistent problems after implantation of a total knee replacement. It can occur in patients with or without patellar resurfacing. As a result of the surgical procedure itself many changes can occur which may affect the delicate interplay of the joint partners in the patello-femoral joint. Functional causes of anterior knee pain can be distinguished from mechanical causes. The functional causes concern disorders of inter- and intramuscular coordination, which can be attributed to preoperative osteoarthritis. Research about anterior knee pain has shown that not only the thigh muscles but also the hip and trunk stabilising muscles may be responsible for the development of a dynamic valgus malalignment. Dynamic valgus may be a causative factor for patellar maltracking. The mechanical causes of patello-femoral problems after knee replacement can be distinguished according to whether they increase instability in the joint, increase joint pressure or whether they affect the muscular lever arms. These causes include offset errors, oversizing, rotational errors of femoral or tibial component, instability, maltracking and chondrolysis, patella baja and aseptic loosening. In these cases, reoperation or revision is often necessary.

Prospective clinical and radiological two-year results after patellofemoral arthroplasty using an implant with an asymmetric trochlea design

PURPOSE

The purpose was to prospectively evaluate the two-year results after implantation of the Journey PFJ(®) (Smith & Nephew, Andover, MA). The authors hypothesized that patellofemoral arthroplasty would result in improved outcomes after 24 months in patients treated with an isolated procedure as well as in patients demonstrating concomitant patellofemoral instability (PFI), which were treated with a combined surgical procedure.

METHODS

Patients were included between 02/2006 and 08/2008. According to the history and clinical findings, patients were grouped into group I with no history or clinical signs of PFI, and patients with concomitant PFI were assorted to group II. Patients were then treated with an isolated (group I) or a combined (group II) surgical procedure to additionally treat the PFI. Visual analogue scale (VAS), Lysholm score and WOMAC score were recorded preoperatively, 6, 12 and 24 months postoperatively. Patellar height was evaluated according to the index of Caton-Deschamps (CDI), and osteoarthritic changes were evaluated according to Kellgren and Lawrence.

RESULTS

A total of 25 patients were enrolled, of them three discontinued interventions and were excluded from final analysis. An isolated implantation of the Journey PFJ(®) was performed in 14 patients (group I) and a combined procedure in 8 (group II). Daily pain and clinical scores significantly improved at 6, 12 and 24 months compared to preoperative values (P < 0.05). Significant decrease (P = 0.02) of mean CDI could be noticed. Significant increase in tibiofemoral OA within the medial but not in the lateral tibiofemoral joint was assessed (P = 0.011; n.s.).

CONCLUSIONS

Patellofemoral arthroplasty using the Journey(®) PFJ for treatment of significant patellofemoral OA demonstrated improved clinical scores at the 2-year follow-up in both groups. Comparing the primary OA (I) and OA + instability (II) groups, patients with patellofemoral OA treated with a combined procedure for concomitant stabilization of patellofemoral instability may benefit more from such a combined procedure, than patients treated with an isolated procedure for treatment of isolated patellofemoral OA.

LEVEL OF EVIDENCE

Prospective case series, Level III.

Secondary Patellar Resurfacing after Primary Bicondylar Knee Arthroplasty did Not Meet Patients' Expectations

Secondary patella resurfacing is a controversial procedure which is applied in patients with anterior knee pain after a bicondylar knee arthroplasty (with unresurfaced patella). A group of 46 patients were submitted to this procedure and their satisfaction, range of motion and pain improvement was evaluated. 52.2% of the patients were satisfied with the procedure, with an improvement in pain (Visual Analogue Scale) of 65% and an improvement in range of motion in 56,5%, with roundabout half of the patients having no resolution to their complaints. Whilst an improvement was not achieved in all patients, as it was initially hypothesised, this procedure should be considered when a revision knee arthroplasty is performed with an unresurfaced patella.

Patellar morphology and femoral component geometry influence patellofemoral contact stress in total knee arthroplasty without patellar resurfacing

PURPOSE

The objective of this study was to determine the effect of patellar morphology and implant design on patellofemoral contact stress in total knee arthroplasty (TKA) without patellar resurfacing.

METHODS

Radiographic investigation: One hundred and fifty-seven knees of 127 patients were included in the study. Implants used in the present series were Low Contact Stress (LCS), Genesis II and NexGen. The relationship between the pre-operative patellar facet angle and newly identified post-operative osteosclerosis was assessed. Finite element analysis: Using patient-specific patellar three-dimensional finite element models, the relationship between the patellar facet angle and mean von Mises stress within the patella was calculated at flexion angles of 15°, 45°, 75° and 105°.

RESULTS

Radiographic investigation: Post-operative osteosclerosis was observed with decreasing patellar facet angle in the Genesis II (odds ratio = 0.72; 95% confidence interval, 0.55-0.93; P = 0.012) and NexGen implants (odds ratio = 0.87; 95% confidence interval, 0.77-0.99; P = 0.029). Patients treated with the Genesis II had significantly more advanced osteosclerosis than those treated with the other two implants. Finite element analysis: A negative correlation was found between the patellar facet angle and the mean von Mises stress for all three implants. The Genesis II showed significantly higher von Mises stress than the other two implants at flexion angles of 15°, 45° and 105°.

CONCLUSIONS

Both patellar morphology and femoral component geometry influence patellofemoral contact stress in total knee arthroplasty without patellar resurfacing.

LEVEL OF EVIDENCE

Case control study, Level III.

Causes of failure and etiology of painful primary total knee arthroplasty

The review provides an overview of the causes of failure and the many different aetiologies of a painful primary total knee arthroplasty (TKA). They can be classified into extra- and intraarticular disorders, the latter being divided into biological and mechanical origins. Whereas biological aetiologies like infections have remained stable over time, other causes of failure have changed. In the early times of knee arthroplasty, they were mainly related to technical insufficiencies. A better understanding of knee arthroplasty, patients' increasing functional demands as well as a continuous development of TKA techniques generated newer problems, which are increasingly related to the functioning of the soft-tissue envelope of the knee. From a therapeutic point of view, three situations can be considered: functional problems not needing reoperations, causes of reoperations not needing an exchange of prosthetic components as well as reoperations with exchange of at least one prosthetic component.