The Avon patellofemoral arthroplasty: five-year survivorship and functional results

Almost 79% survival rate at 10-year follow-up for the patellofemoral joint arthroplasty: An Italian prosthetic registry study

PURPOSE

The aims of the present study were (1) to evaluate the survival of patellofemoral joint (PFJ) arthroplasty in a large cohort of patients using data obtained from an Italian regional arthroplasty registry and (2) to collect clinical outcomes of a subgroup of patients, with a minimum follow-up of 4 years. The hypotheses were that PFJ arthroplasty is a procedure that had good survival and clinical outcomes, not inferior to those reported in the literature for primary total knee arthroplasty (TKA).

METHODS

The Register of Orthopaedic Prosthetic Implants (RIPO) of Emilia-Romagna (ER) (Italy) database was searched for the inclusion of all PFJ arthroplasties implanted between 2003 and 2019. PFJ arthroplasties were excluded if they were implanted in patients who lived outside of the ER. The survival information was extrapolated from the RIPO considering the partial or total revision of the implant as failure; moreover, a subgroup of patients was contacted and interviewed by telephone to collect clinical outcomes. Descriptive statistics were used to summarise the data. The survival curve was calculated and plotted using the Kaplan-Meier method.

RESULTS

A total of 126 arthroplasties in 114 patients were included in the final analysis (mean age at surgery 60.1 ± 11.5 years old). The main causes of patellofemoral arthroplasty were primary osteoarthritis (88%) and posttraumatic arthritis (7%). The survival was 90.4 ± 30.6 and 78.8 ± 51.5 at 5 and 10 years of follow-up, respectively. At the latest follow-up, 23 implants failed (18.3%). The main cause of revision was osteoarthrosis progression (34.8%). A total of 44 patients were contacted by telephone to collect clinical outcomes: Western Ontario and McMaster Universities Osteoarthritis Index, functional Knee Society Score, Forgotten Joint Score and Oxford Knee Score. These patients reported good to excellent scores at a medium follow-up of 10.3 ± 4.7 years.

CONCLUSIONS

The PFJ showed good survival and clinical outcomes and could be considered a valuable option for patients affected by isolated patellofemoral osteoarthritis.

LEVEL OF EVIDENCE

Level IV.

Robotic-assisted patellofemoral arthroplasty provides excellent implant survivorship and high patient satisfaction at mid-term follow-up

PURPOSE

Robotic adoption in knee surgery has yielded several benefits, but its application in patellofemoral arthroplasty (PFA) remains barely reported. The purpose of this study was to determine implant survival, patient satisfaction, and functional outcomes after robotic-assisted PFA at an intermediate follow-up.

METHODS

This prospective analysis targeted 18 knees of 16 consecutive patients who underwent robot-aided PFA with three-year minimum follow-up (range, 3 to 6 years). Each patient was evaluated collecting pre-operative and post-operative medical record data, including range of motion, radiographic images, and multiple scores, such as VAS, APKS, and OKS.

RESULTS

At surgery, the mean age was 55.4 years ± 14.4 (range, 32 to 78 years), and the mean BMI was 26.8 kg/m² ±5.2 (range, 20 to 36). Etiologies of patellofemoral osteoarthritis included idiopathic degeneration (28%), post-traumatic (33%), and dysplasia (39%). Pre-implantation scores were VAS 7.9 ± 1.4, AKPS 34.6 ± 23.3, and OKS 17.3 ± 10.3. One implant was revised with primary total knee arthroplasty for osteoarthritis progression. Clinical and radiographic follow-up showed no signs of loosening or infection. The maximum flexion reached an average of 131.1°±10.5° (range, 110° to 145°), accompanied by significantly improved score results (P-value < 0.01): VAS 1.1 ± 1.4, AKPS 90.2 ± 8.6, and OKS 46.3 ± 1.8.

CONCLUSIONS

At 3 years after robotic assisted patellofemoral arthroplasty, excellent implant survival and patient satisfaction rates can be expected along with significantly improved functional and pain control outcomes. Although the limitations imposed by the restricted cohort, these findings indicate that robotic assistance in PFA is both safe and effective at intermediate follow-up.

Short-term Functional Outcomes and Complications of Custom Patellofemoral Arthroplasty

Background

Patellofemoral arthroplasty (PFA) is a treatment option for isolated patellofemoral arthritis. Custom PFA is an innovative procedure utilizing patient-specific instrumentation. The purpose of this study is to evaluate short-term functional outcomes and complications of the custom PFA in treatment of isolated patellofemoral arthritis.

Methods

A retrospective study was conducted to analyze patients who received a PFA operation from a single surgeon. Inclusion criteria were surgical patients from 2012 to 2018 who underwent PFA using a custom prosthesis implant. Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) and Lower Extremity Functional Scale (LEFS) were collected before and after surgery.

Results

A total of 79 patients (94 knees) participated in the study; 55 (69.6%) were women. The median age was 57 at the time of index arthroplasty; 15 patients (30 knees) were bilateral. Follow-up rate was 94%. Median follow-up duration was 3.6 years (2-8.9). Overall prefunctional and postfunctional scores differed significantly for both KOOS, JR and LEFS. Postoperative scores increased for KOOS, JR by 27.5 points, and for LEFS, they increased 26.0 points; P < .001 for both. Complications included 6 reoperations (6.7%) related to PFA: 4 conversions (4.4%) to total knee arthroplasty at a median of 2.5 (1.5-3) years after the index procedure, one vastus medialis oblique advancement (1.1%) secondary to patellar maltracking, and one manipulation under anesthesia (1.1%).

Conclusions

Custom PFA in patients with isolated patellofemoral arthritis showed good short-term functional outcomes and low revision rates with very few complications.

Occupational and Functional Outcomes following Patellofemoral Arthroplasty in U.S. Military Servicemembers

The functional outcomes in patients undergoing patellofemoral arthroplasty (PFA) with high occupational demands have not been fully examined. This study assessed return to work and conversion to TKA rates following PFA in a young, military cohort. Patient demographics, pain scores, and surgical information were retrospectively collected for all active-duty military members who underwent PFA over a 4-year period. The data were then analyzed to calculate return to work, conversion to TKA, and perioperative complications rates. A total of 48 servicemembers with 60 total PFAs (36 unilateral, 12 bilateral) were included, with a mean follow up of 2.2 years. At the final follow-up, 83% of servicemembers returned to military service or completed their service obligation after PFA. Conversion to TKA occurred in three (6.2%) patients at an average of 2.4 years after PFA, resulting in a PFA annual revision rate of 2.3%. The mean numeric rating scale for pain improved from 4.9 ± 2.6 at baseline to 2.5 ± 2.0 postoperatively (p < 0.001). Servicemembers with at least one prior ipsilateral knee procedure had a significantly decreased odds ratio (OR) for both occupational outcome failure (OR, 0.03; 95% confidence interval [CI], 0-0.29) and overall failure (OR, 0.13; 95% CI, 0.02-0.78). At an average of 2 years following PFA, 83% of military members returned to duty, with a low rate of revision to TKA. Prior ipsilateral knee procedure decreased the probability of medical separation. LEVEL OF EVIDENCE:  IV.

[Isolated Patellofemoral Osteoarthritis]

Isolated patellofemoral osteoarthritis is a complex pathology. It occurs frequently in women over 40 years and leads to a high degree of suffering. The causes of femoropatellar degeneration are manifold and require stage-specific therapy. This is very challenging for the treating physician. This article is intended to provide a structured overview of the symptoms, diagnostics and stage-specific therapy of patellofemoral osteoarthritis.

The landscape of patellofemoral arthroplasty research: a bibliometric analysis

PURPOSE

Patellofemoral arthroplasty (PFA) was shown to be a potentially effective surgical technique for isolated patellofemoral osteoarthritis but varying reports on PFA-related implant failure and complications have rendered the procedure controversial. This study aimed to identify impactful publications, research interests/efforts, and collaborative networks in the field of PFA research.

METHODS

The study used the Web of Science Core Collection (WOSCC) database, Medline, Springer, BIOSIS Citation Index, and PubMed to retrieve relevant publications on PFA research published between 1950-2022. Statistical tests in R software were used for analysis while VOSviewer, Bibliometrix, and CiteSpace were employed for data visualization.

RESULTS

Two hundred forty-one articles were analyzed with the number of published papers increasing over time. Knee was the most frequent journal and Clinical Orthopaedics and Related Research was the most cited journal. Clinical outcomes, such as prosthesis survival, revision, and complications, were researched most frequently as demonstrated by keyword analysis. The United States was the top contributor to cooperative networks, followed by the United Kingdom while Technical University Munich formed close ties among authors.

CONCLUSION

Publications on PFA research have witnessed a notable surge. They primarily came from a limited number of centers and were characterized by low-level evidence. The majority of studies primarily focused on the clinical outcomes of PFA, while revision of PFA and patient satisfaction have emerged as new research areas.

Outcomes of isolated patellofemoral arthroplasty

Osteoarthritis of the patellofemoral compartment can cause significant functional impairment. Isolated patellofemoral osteoarthritis affects greater than 10% of males and females over the age of 60. Patellofemoral arthroplasty (PFA) was developed as a joint-preserving procedure that maintains natural knee kinematics in those with isolated patellofemoral disease. First-generation implants were fraught with complications, a high rate of revision, and early conversion to total knee arthroplasty (TKA). Second-generation implants have demonstrated significant improvements in patient-reported outcome measures, complication rates and implant survivorship. Factors that can affect outcomes include surgical indications, patient selection, and PFA prosthesis design. Modern PFA for isolated patellofemoral osteoarthritis has comparable outcomes to TKA for isolated patellofemoral osteoarthritis. In this article, we discuss the use of PFA, implant design, the indications and factors affecting outcomes, and comparison to TKA.

Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) as a treatment option for isolated patellofemoral disease continues to evolve. Enhancement in patient selection, surgical technique, implant design, and technology has led to improved short-term and midterm outcomes. Furthermore, in the setting of a younger patient with isolated patellofemoral arthritis, PFA represents an option for improved function with faster recovery times, bone preservation, maintenance of ligamentous proprioception, and the ability to delay total knee arthroplasty (TKA). The most common reason for revising PFA to a TKA is progression of tibiofemoral arthritis. In general, conversion of PFA to TKA leads to successful outcomes with minimal bone loss and the ability to use primary TKA implants and instrumentation. PFA seems to be a cost-effective alternative to TKA in appropriately selected patients with 5-, 10-PFA survivorships of 91.7% and 83.3%, respectively, and an annual revision rate of 2.18%; however, more long-term clinical studies are needed to determine how new designs and technologies affect patient outcomes and implant performance.

Modern Patellofemoral Arthroplasty

INTRODUCTION

The ideal procedure for isolated patellofemoral arthritis is a controversial topic. Patellofemoral arthroplasty (PFA) is an option that aims to restore normal kinematics to the knee while preserving bone. PFA has been shown to have benefits compared with total knee arthroplasty (TKA) in this patient population but has historically had a high failure rate. Revision rates are improving with modern implants and tight indications but still remain higher than TKA. This review summarizes current thinking around PFA using modern implants and techniques in 2023, provides an implant-specific analysis, and assesses how we can improve outcomes after PFA based on the current literature. The aim was to provide an outline of the evidence around PFA on which surgeons can make decisions to optimize patient outcome in this young and active population.

METHODS

Four databases (MEDLINE, Embase, Scopus, and SPORTDiscus) were searched for concepts of patellofemoral joint arthroplasty. After abstract and text review, a screening software was used to assess articles based on inclusion criteria for studies describing indications, outcomes, and techniques for isolated PFA using modern implants, with or without concomitant procedures.

RESULTS

A total of 191 articles were included for further examination, with 62 articles being instructional course lectures, systematic reviews, technique articles, narrative reviews, expert opinions, or meta-analyses. The remaining articles were case reports, trials, or cohort studies. Articles were used to create a thorough outline of multiple recurrent topics in the literature.

CONCLUSIONS

PFA is an appealing option that has the potential to provide a more natural feeling and functioning knee for those with isolated PF arthritis. The high rate of revision is a cause for concern and there are several technical details that should be stressed to optimize results. The uncertain outcome after revision to TKA also requires more investigation. In addition, the importance of strict selection criteria and firm indications cannot be stressed enough to optimize longevity and attempt to predict those who are likely to have progression of tibiofemoral osteoarthritis. The development of new third-generation implants is promising with excellent functional outcomes and a much lower rate of maltracking and implant complications compared with earlier generations. The impact of these implants and improvement in surgical techniques on the revision rate of PFA will be determined from longer-term outcomes.

Outcomes are Compromised When Revising Patellofemoral Arthroplasties for Patellar Component Failures

BACKGROUND

Outcomes of patellofemoral arthroplasty (PFA) to total knee arthroplasty (TKA) conversion are reported to be similar to primary cases. The purpose of this study was to determine whether the cause for conversion from PFA to TKA correlated to outcomes when compared to a matched cohort.

METHODS

A retrospective chart review was performed to identify aseptic PFA to TKA conversions between 2000 and 2021. A cohort of primary TKAs was matched by patient sex, body mass index, and American Society of Anesthesiology score. Clinical outcomes, including range of motion, complication rates, and patient reported outcomes measurement information systems scores, were compared. Chi-squared, Fisher's Exact, and t-tests were performed. There were 20 PFA to TKA conversions that met inclusion criteria and were matched to 60 primary cases.

RESULTS

There were 7 cases revised for arthritis progression, 5 for femoral component failure, 5 for patellar component failure, and 3 for patellar maltracking. PFA to TKA conversions for patellar failure (fracture, component loosening) had worse postoperative flexion (115 versus 127°, P = .023) and more complications of stiffness (40 versus 0%, P = .046) than primary TKAs. Conversions for failed patellar components had worse patient reported outcomes measurement information systems physical function (32 versus 45, P = .0046), physical health (42 versus 49, P = .0258), and pain scores (45 versus 24, P = .0465). No differences were found in rates of infection, manipulations under anesthesia, or reoperations.

CONCLUSION

PFA to TKA conversion outcomes were similar to primary TKA, except in patients who had failed patellar components and demonstrated worse postoperative range of motion and patient-reported outcomes. Surgeons should avoid thin patellar resections and extensive lateral releases to minimize patellar failures.

Midterm outcomes of patellofemoral arthroplasty

BACKGROUND

The purpose of this study is the evaluation of the patellofemoral arthroplasty (PFA) survival and clinical and radiological outcomes in our institution.

METHODS

A retrospective evaluation of our institution patellofemoral arthroplasty cases from 2006 to 2018 was performed; the n sample after applying exclusion and inclusion criteria was 21. All patients excepting one were female with a median age of 63 (20-78). A Kaplan-Meier survival analysis at ten years was calculated. Informed consent was obtained from all patients prior being included in the study.

RESULTS

The total revision rate was 6 out of 21 patients (28.57%). The progression of the osteoarthritis in the tibiofemoral compartment was the main cause (50% of revision surgeries). The degree of satisfaction with the PFA was high, with a mean Kujala score of 70.09 and a mean OKS of 35.45 points. The VAS score improved significantly (P<.001) from a preoperative mean of 8.07 to a postoperative mean of 3.45, with an average improvement of 5 (2-8). Survival at 10 years, with revision for any reason as the endpoint, was 73.5%. A significant positive correlation between BMI and the WOMAC pain (r=.72, P<.01) and between BMI and the post-operative VAS (r=.67, P<.01) was observed.

CONCLUSIONS

The results of the case series under consideration suggest that PFA could be a possibility in the joint preservation surgery on the isolated patellofemoral osteoarthritis. BMI >30 seems to be a negative predictor factor in relationship with the postoperative satisfaction, increasing the pain proportionally to this index and requiring more replacement surgery than patients with BMI <30. Meanwhile the radiologic parameters of the implant are not correlated with the clinical or functional outcomes.

Functional Outcomes, Survival Rate, and Complications of Patellofemoral Arthroplasty: Mid-Term Results From Independent Center

Background Patellofemoral arthroplasty (PFA) is indicated for isolated patellofemoral arthritis. PFA is a less invasive, bone-preserving procedure with faster recovery when compared to total knee replacement. We aim to present the functional outcome, survival rate, and complications of PFA from our center. Methods A total of 45 consecutive PFA performed (mean age 58.02 ± 9.2 years; 34 females and 11 males; Avon prosthesis) during the study period was included. Prosthesis survivorship was measured using revision as the endpoint, and functional outcome was assessed using Oxford knee scores (OKSs), EQ-5D, and satisfaction scores. Postoperative complications, the number of revisions, and the reasons causing them were collected. Results The mean follow-up was 48.7 (range 16-66) months. As compared to preoperative scores, OKS and Eq5d showed significant improvements (p<0.001). The satisfaction scores indicated that 28 patients (62%) were very satisfied, 10 (26.7%) were satisfied, and seven (15.5%) were dissatisfied. Four patients (8.9%) underwent revision surgery with a total knee replacement. Out of four patients requiring revision, two had progressive arthritis of the medial compartment, one had aseptic loosening of the implants, and one had trauma. Five patients showed persistent anteromedial knee pain (12.2%); one patient had maltracking requiring lateral release; one patient developed stiffness with knee flexion less than 60 degrees requiring manipulation under anesthesia. Conclusion Our results indicated that good or excellent functional outcomes can be expected in >80% of patients with survivorship of 91.1% at mid-term. Careful patient selection and counseling should be done informing of the risk of dissatisfaction/persistent pain and revision surgery in the mid and long term. Long-term outcomes and factors determining good outcomes need to be evaluated in future research.

Patellofemoral Arthroplasty Results in Better Time-weighted Patient-reported Outcomes After 6 Years than TKA: A Randomized Controlled Trial

BACKGROUND

In a previous study, we reported the 2-year outcomes of a parallel-group, equivalence, randomized controlled trial (RCT; blinded for the first year) comparing patellofemoral arthroplasty (PFA) and TKA for isolated patellofemoral osteoarthritis (PF-OA). We found advantages of PFA over TKA for ROM and various aspects of knee-related quality of life (QOL) as assessed by patient-reported outcomes (PROs). Register data show increases in PFA revision rates from 2 to 6 years after surgery at a time when annual TKA revision rates are decreasing, which suggests rapidly deteriorating knee function in patients who have undergone PFA. We intended to examine whether the early advantages of PFA over TKA have deteriorated in our RCT and whether revision rates differ between the implant types in our study after 6 years of follow-up.

QUESTIONS/PURPOSES

(1) Does PRO improvement during the first 6 postoperative years differ between patients who have undergone PFA and TKA? (2) Does the PRO improvement at 3, 4, 5, and 6 years differ between patients who have undergone PFA and TKA? (3) Do patients who have undergone PFA have a better ROM after 5 years than patients who have had TKA? (4) Does PFA result in more revisions or reoperations than TKA during the first 6 postoperative years?

METHODS

We considered patients who had debilitating symptoms and PF-OA as eligible for this randomized trial. Screening initially identified 204 patients as potentially eligible; 7% (15) were found not to have sufficient symptoms, 21% (43) did not have isolated PF-OA, 21% (43) declined participation, and 1% (3) were not included after the target number of 100 patients had been reached. The included 100 patients were randomized 1:1 to PFA or TKA between 2007 and 2014. Of these, 9% (9 of 100) were lost before the 6-year follow-up; there were 12% (6 of 50) and 0% (0 of 50) deaths (p = 0.02) in the PFA and TKA groups, respectively, but no deaths could be attributed to the knee condition. There were no differences in baseline parameters for patients who had PFA and TKA, such as the proportion of women in each group (78% [39 of 50] versus 76% [38 of 50]; p > 0.99), mean age (64 ± 9 years versus 65 ± 9 years; p = 0.81) or BMI (28.0 ± 4.7 kg/m 2 versus 27.8 ± 4.1 kg/m 2 ; p = 0.83). Patients were seen for five clinical follow-up visits (the latest at 5 years) and completed 10 sets of questionnaires during the first 6 postoperative years. The primary outcome was SF-36 bodily pain. Other outcomes were reoperations, revisions, ROM, and PROs (SF-36 [eight dimensions, range 0 to 100 best, minimum clinically important difference {MCID} 6 to 7], Oxford Knee Score [OKS; one dimension, range 0 to 48 best, MCID 5], and Knee Injury and Osteoarthritis Outcome Score [KOOS; five dimensions, range 0 to 100 best, MCID 8 to 10]). Average PRO improvements over the 6 years were determined by calculating the area under the curve and dividing by the observation time, thereby obtaining a time-weighted average over the entire postoperative period. PRO improvements at individual postoperative times were compared for the patients who had PFA and TKA using paired t-tests. Range of movement changes from baseline were compared using paired t-tests. Reoperation and revision rates were compared for the two randomization groups using competing risk analysis.

RESULTS

Patients who underwent PFA had a larger improvement in the SF-36 bodily pain score during the first 6 years than those who underwent TKA (35 ± 19 vs. 23 ± 17; mean difference 12 [95% CI 4 to 20]; p = 0.004), and the same was true for SF-36 physical functioning (mean difference 11 [95% CI 3 to 18]; p = 0.008), KOOS Symptoms (mean difference 12 [95% CI 5 to 20]; p = 0.002), KOOS Sport/recreation (mean difference 8 [95% CI 0 to 17]; p = 0.048), and OKS (mean difference 5 [95% CI 2 to 8]; p = 0.002). No PRO dimension had an improvement in favor of TKA. At the 6-year time point, only the SF-36 vitality score differed between the groups being in favor of PFA (17 ± 19 versus 8 ± 21; mean difference 9 [95% CI 0 to 18]; p = 0.04), whereas other PRO measures did not differ between the groups. At 5 years, ROM had decreased less from baseline for patients who underwent PFA than those who had TKA (-4° ± 14° versus -11° ± 13°; mean difference 7° [95% CI 1° to 13°]; p = 0.02), but the clinical importance of this is unknown. Revision rates did not differ between patients who had PFA and TKA at 6 years with competing risk estimates of 0.10 (95% CI 0.04 to 0.20) and 0.04 (95% CI 0.01 to 0.12; p = 0.24), respectively, and also reoperation rates were no different at 0.10 (95% CI 0.04 to 0.20) and 0.12 (95% CI 0.05 to 0.23; p = 0.71), respectively.

CONCLUSION

Our RCT results show that the 2-year outcomes did not deteriorate during the subsequent 4 years. Patients who underwent PFA had a better QOL throughout the postoperative years based on several of the knee-specific outcome instruments. When evaluated by the 6-year observations alone and without considering earlier observations, we found no consistent difference for any outcome instruments, although SF-36 vitality was better for patients who underwent PFA. These combined findings show that the early advantages of PFA determined the results by 6 years. Our findings cannot explain the rapid deterioration of results implied by the high revision rates observed in implant registers, and it is necessary to question indications for the primary procedure and subsequent revision when PFA is in general use. Our data do not suggest that there is an inherent problem with the PFA implant type as otherwise suggested by registries. The long-term balance of advantages will be determined by the long-term QOL, but based on the first 6 postoperative years and ROM, PFA is still the preferable option for severe isolated PF-OA. A possible high revision rate in the PFA group beyond 6 years may outweigh the early advantage of PFA, but only detailed analyses of long-term studies can confirm this.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Midterm results of modern patellofemoral arthroplasty versus total knee arthroplasty for isolated patellofemoral arthritis: systematic review and meta-analysis of comparative studies

BACKGROUND

Both Patellofemoral Arthroplasty (PFA) and Total Knee Arthroplasty (TKA) are accepted surgical options for end-stage isolated patellofemoral osteoarthritis (PFOA). We performed a systematic review and meta-analysis to compare outcomes of PFA and TKA by evaluation of the patient-reported outcome measures (PROMs).

METHODS

We systematically identified publications reporting on patients that underwent either TKA or modern PFA for isolated PFOA. Meta-analysis software was used to screen for potential articles with at least two years' follow-up. Data were extracted and analysed for all PROMs operating time, postoperative inpatient time, complications and cost. We included five studies in our cumulative meta-analysis and reviewed them using Review Manager V.5.0. We computed the risk ratio as a measure of the treatment effect, taking into account heterogeneity. We used random-effect models.

RESULTS

No significant difference was found between both TKA and PFA in the context of operating time. No significant difference after five years' follow-up was found between the two treatment options in terms of UCLA score and patient satisfaction. PFA showed significant improvement in WOMAC score at five-year follow-up, less postoperative inpatient time, better cost-effectiveness and significantly less blood loss.

CONCLUSION

PFA seems to be a viable alternative to TKA for treatment of isolated PFOA in appropriately selected patients. PFA showed less postoperative inpatient time and blood loss with similar PROMs to the TKA. Moreover, it is an economically beneficial joint-preserving procedure.

Rotational alignment of the femoral trochlea in Asians: Implication on implant choice and position for managing isolated patellofemoral osteoarthritis

Introduction

Maltracking of the patella is a key contributor to early failure of patellofemoral arthroplasty (PFA). Native femoral trochlear morphology dictates implant rotation and patella tracking of in-lay PFA implants. This is the first study amongst Asians designed to assess the normal rotational alignment of the trochlear groove and evaluate its implication on PFA implant choice and position.

Methods

Trochlear inclination angle (TIA) was measured from 211 magnetic resonance images of Asian knees retrieved from a single centre in Hong Kong. TIA assesses rotation of the femoral trochlear groove relative to the axis perpendicular to Whiteside’s line (anteroposterior axis of the femur).

Results

The mean trochlear inclination in normal Asian knees was 11.5°  ±  2.5° (mean  ±  standard deviation) internal rotation. High-grade dysplastic knees, according to Dejour classification, were significantly more internally rotated with a mean of 12.8°  ±  3.6° (p = 0.025).

Conclusion

Trochlear inclination in Asians is comparable to Caucasians. In-lay PFA implants do not alter native pathological bony trochlear anatomy, and may result in patella maltracking in patients with high grade trochlear dysplasia or excessive trochlear inclination. These patients may benefit from on-lay implants, which allows restoration of normal trochlear inclination, as well as lateralisation and deepening of the trochlear groove. Patella tracking is however, dynamic and multi-factorial. Further clinical studies are therefore warranted to reconcile our anatomical findings with clinical outcomes.

A Newly Identified Complication of Patellofemoral Arthroplasty: Case Report and Literature Review

Background

Patellofemoral arthroplasty (PFA) is a surgical option for patients older than 40 years old who are affected by patellofemoral osteoarthritis. Regarding the complications of PFAs, few studies have investigated periprosthetic fractures. The purpose of this literature review was to highlight a previously overlooked complication of primary prosthetic surgery of the patellofemoral joint.

Methods

Three literature databases were searched for studies published between 2000 to 2020 using relevant keywords. A total of 4,942 articles were originally identified. After excluding duplicates and analysing the titles and abstracts, 20 studies were considered. From these, data regarding the number of cases, clinical outcomes and complications were extracted.

Results

Among the 20 selected articles, only one described periprosthetic fractures as a complication of PFAs. Herein, we also report an illustrative case of an unknown fracture complication. No cases in the literature were found that described the type of complications experienced by our patient during the postoperative period.

Conclusions

This review confirms the lack of data about clinical outcomes and fracture complications of PFAs. In primary prosthetic surgery of the patellofemoral joint, patient selection and close consideration of demographic factors (such as BMI and age) and intraoperative factors (such as patellar thickness and size of the trochlear component) play a key role in optimising pre-operative planning to avoid intraoperative periprosthetic fractures.

[When nothing else works: patellofemoral joint arthroplasty]

Patellofemoral joint replacement is the best treatment option available for isolated patellofemoral arthritis. Especially young patients should be operated on with bone-sparing techniques that also preserve the soft tissues, since these patients are very likely to be revised at some point in their lifetime. Correct patient selection is important for the success of surgery and should include a meticulous clinical examination and imaging. Special attention should be paid to additional pathologies that may also need to be addressed. For the trochlea, there are two different options for treatment with the inlay and onlay system. The retropatellar surface should be replaced. Patellofemoral joint replacement is still rarely performed, so treatment in specialised centres is recommended. National joint registry data show high revision rates, while data from centres show promising results.

Conversion Total Knee Arthroplasty

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Conversion total knee arthroplasty (TKA) represents a heterogeneous group of procedures and most commonly includes TKA performed after ligamentous reconstruction, periarticular open reduction and internal fixation (ORIF), high tibial osteotomy (HTO), and unicompartmental knee arthroplasty (UKA).

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Relative to patients undergoing primary TKA, patients undergoing conversion TKA often have longer operative times and higher surgical complexity, which may translate into higher postoperative complication rates.

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There is mixed evidence on implant survivorship and patient-reported outcome measures when comparing conversion TKA and primary TKA, with some studies noting no differences between the procedures and others finding decreased survivorship and outcome scores for conversion TKA.

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By gaining an improved understanding of the unique challenges facing patients undergoing conversion TKA, clinicians may better set patient expectations, make intraoperative adjustments, and guide postoperative care.

Onlay Patellofemoral Arthroplasty in Patients With Isolated Patellofemoral Arthritis: A Systematic Review

BACKGROUND

Patellofemoral arthroplasty (PFA) for isolated patellofemoral osteoarthritis (OA) remains controversial due to variable postoperative outcomes and high failure rates. Second-generation (2G) onlay prostheses have been associated with improved postoperative outcomes. This systematic review was performed to assess the current overall survivorship and functional outcomes of 2G PFA.

METHODS

A search was performed using PubMed, Cochrane Library, EMBASE, and Google Scholar. Thirty-three studies published in the last 15 years (2005-2020) were included; of these 22 studies reported patient-reported outcome measures. Operative and nonoperative complications were analyzed. Pooled statistical analysis was performed for survivorship and functional scores using Excel 2016 and Stata 13.

RESULTS

The mean age of the patients was 59.7. When analyzing all studies, weighted survival at mean follow-up of 5.52 was 87.72%. Subanalysis of studies with minimum 5 years of follow up showed a survival of 94.24%. Fifteen studies reported Oxford Knee Score with a weighted mean postoperative Oxford Knee Score of 33.59. Mean American Knee Society Score pain was 79.7 while mean American Knee Society Score function was 79.3. The most common operative complication was OA progression for all implants. The percentage of revisions and conversions reported after analyzing all studies was 1.37% and 7.82% respectively.

CONCLUSION

Safe and acceptable results of functional outcomes and PFA survivorship can result from 2G PFAs at both short and mid-term follow-up for patients with isolated patellofemoral OA. However, long-term follow-up outcomes are still pending for the newer implants. More extensive studies using standardized functional outcomes and long-term cost benefits should be evaluated.

Patient-related outcomes of patellofemoral arthroplasty: experience of a single center

Purpose

The purpose of this prospective study was to present the experience of a single center on patellofemoral arthroplasty, in terms of patient-related outcomes.

Method

From January 2005 to January 2016, 42 patients with isolated patellofemoral osteoarthritis were treated. The patients were assessed using the Oxford Knee Score preoperatively, and one, five, and eight year(s) after surgery. The data of the patients were analyzed using linear mixed effects models. A P value of 0.05 was considered statistically significant.

Results

Among 42 patients who underwent patellofemoral arthroplasty, only 25 patients (31 limbs involved) had records up to 5 years. There was a significant clinical improvement of Oxford Knee Score postoperatively (P < 0.05), lowering the score on average by 10.4 ± 1.5 one year after surgery and 8.9 ± 1.9 five years after surgery. This improvement was independent of the types of implants (P > 0.05), gender (P > 0.05), age (P < 0.05), and body mass index (BMI) (P < 0.05).

Conclusion

Patellofemoral arthroplasty can significantly improve the knee function, and this improvement is independent of the type of implant, gender, age, and BMI. However, further studies will need to assess the long-term outcomes of PFA.

Operative Treatment Options for Patellofemoral Arthritis: An Expert Recommendation of the AGA Patellofemoral Committee

Background:

The operative therapy of patellofemoral arthritis requires an individual approach depending on the underlying injury. However, the literature lacks recommendations for its course of action.

Purpose:

To generate an expert recommendation of therapy for different patellofemoral abnormalities in patients suffering from isolated patellofemoral arthritis.

Study Design:

Consensus statement.

Methods:

To generate recommendations, the AGA Patellofemoral Committee performed a consensus process using the Delphi method based on the available literature on isolated patellofemoral arthritis.

Results:

In most statements and recommendations, a high percentage of consensus could be found. However, also in the expert group of the AGA Patellofemoral Committee, some controversies on the treatment of patellofemoral arthritis exist.

Conclusion:

The operative therapy of isolated patellofemoral arthritis is a challenging topic that leads to controversial discussions, even in an expert group. With this consensus statement of the AGA Patellofemoral Committee, recommendations on different operative treatment options were able to be generated, which should be considered in clinical practice.

[Patellofemoral inlay implants-an innovation in patellofemoral joint arthroplasty?]

Isolated arthrosis of the patellofemoral joint is a rare and complex disease. After conservative therapy has been exhausted, the orthopedist has various soft-tissue and bone reconstructive procedures as well as cartilage regenerative procedures at his hands. In cases of failed or unsatisfactory therapy, patellofemoral arthroplasty continues to be controversially discussed as an alternative therapy. A closer look at these studies reveals promising results with the correct indication and patient selection. The different prosthesis designs provide good postoperative results while considering general and specific risks. The current generation of patellofemoral inlay prostheses shows high patient satisfaction with significant improvements in knee function and pain relief in mid-term outcomes. However, a relatively high revision rate must be considered.

Combined patellofemoral arthroplasty and medial patellofemoral ligament reconstruction for chronic patellar instability with trochlear dysplasia: a report of two cases

Deepening trochleoplasty combined with other patella stabilization procedures is often performed to correct patellar instability with trochlear dysplasia. However, various complications following trochleoplasty including patellofemoral osteoarthritis and anterior knee pain can be negative factors affecting the clinical results. Here, we describe two cases of chronic patellar instability with trochlear dysplasia on whom we performed patellofemoral arthroplasty (PFA), instead of trochleoplasty, in conjunction with medial patellofemoral ligament (MPFL) reconstruction. In both cases, PFA, acting as metallic trochleoplasty, improved the congruency of patellofemoral joint, and achieved good clinical results for up to 3 years postoperatively without recurrent patellar instability. This procedure could be considered as one option for cases of chronic patellar instability with trochlear dysplasia.

Smoking, unemployment, female sex, obesity, and medication use yield worse outcomes in patellofemoral arthroplasty

PURPOSE

The purpose of this study was to identify effects of psychosocial and demographic factors on patellofemoral arthroplasty (PFA) outcomes.

METHODS

Patients who underwent PFA by a single surgeon between 2002 and 2013 (min. 2 year follow-up) were included. Knee Society scores (KSS), UCLA, and Tegner Scores were prospectively collected in a designated arthroplasty registry. Patient records were retrospectively reviewed and univariate and multivariate statistical analyses were performed to assess the effect of psychosocial factors and demographic variables including patient sex, BMI, smoking and medication use, psychiatric history, and employment status on improvement between pre- and post-operative scores.

RESULTS

Seventy-four knees in 55 patients (88% female) with a mean age of 51.8 (SD 8.8) and mean follow-up of 46.5 (SD 26.9) months were included. Patients showed significant improvement in all functional outcomes (p < 0.001). Mean improvement in KSS-F scores and median improvement in Tegner scores was greater in males compared to females (37.8 vs 16.1, p = 0.007; 3.0 vs 2.0, p = 0.07, respectively). Smokers showed less improvement in KSS-P compared to non-smokers (17.2 vs 30.0, p = 0.028). Retired or employed patients had a greater mean improvement in KSS-F and median improvement in Tegner Scores compared to those were unemployed or on work disability (p = 0.022, p = 0.01). Patients who reported using opioids and/or anti-depressants pre-operatively showed less improvement in UCLA scores (p = 0.006). Obese patients showed less improvement in both KSS-F and Tegner score compared to non-obese patients (p = 0.009, p = 0.004).

CONCLUSION

Psychosocial factors influence the degree of improvement following PFA. Although patients showed overall improvement compared to their baseline scores, obese patients, smokers, unemployed/work disabled, and pre-operative use of opioids and/or anti-depressants were risk factors for decreased improvement… The consideration of psychosocial variables are clinically important when assessing a patient's candidacy for PFA and improve pre-operative patient selection and counselling.

LEVEL OF EVIDENCE

Level IV.

The PAT randomized clinical trial

AIMS

A pragmatic, single-centre, double-blind randomized clinical trial was conducted in a NHS teaching hospital to evaluate whether there is a difference in functional knee scores, quality-of-life outcome assessments, and complications at one-year after intervention between total knee arthroplasty (TKA) and patellofemoral arthroplasty (PFA) in patients with severe isolated patellofemoral arthritis.

METHODS

This parallel, two-arm, superiority trial was powered at 80%, and involved 64 patients with severe isolated patellofemoral arthritis. The primary outcome measure was the functional section of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at 12 months. Secondary outcomes were the full 24-item WOMAC, Oxford Knee Score (OKS), American Knee Society Score (AKSS), EuroQol five dimension (EQ-5D) quality-of-life score, the University of California, Los Angeles (UCLA) Physical Activity Rating Scale, and complication rates collected at three, six, and 12 months. For longer-term follow-up, OKS, EQ-5D, and self-reported satisfaction score were collected at 24 and 60 months.

RESULTS

Among 64 patients who were randomized, five patients did not receive the allocated intervention, three withdrew, and one declined the intervention. There were no statistically significant differences in the patients' WOMAC function score at 12 months (adjusted mean difference, -1.2 (95% confidence interval -9.19 to 6.80); p = 0.765). There were no clinically significant differences in the secondary outcomes. Complication rates were comparable (superficial surgical site infections, four in the PFA group versus five in the TKA group). There were no statistically significant differences in the patients' OKS score at 24 and 60 months or self-reported satisfaction score or pain-free years.

CONCLUSION

Among patients with severe isolated patellofemoral arthritis, this study found similar functional outcome at 12 months and mid-term in the use of PFA compared with TKA. Cite this article: Bone Joint J 2020;102-B(3):310-318.

Minimally Invasive Robotic-Assisted Patellofemoral Arthroplasty

Isolated patellofemoral arthritis is a common debilitating condition in adults older than 40 years of age. Surgical options such as patellofemoral arthroplasty exist for those who failed to respond to nonoperative treatment. However, early patellofemoral arthroplasty techniques often resulted in poor outcomes due to mal-tracking and malalignment of components. Robotic-assisted surgery recently has been introduced as an alternative to classic patellofemoral arthroplasty, with the potential to improve the anatomical fit and reproducibility of implant positioning. We present the technique for minimally invasive robotic-assisted patellofemoral arthroplasty system.

Isolated Patellofemoral Joint Arthroplasty: Can Preoperative Bone Scans Predict Survivorship?

BACKGROUND

Isolated patellofemoral joint arthritis has been identified in 10% of the population presenting with symptomatic knee osteoarthritis. Patient selection is important in order to improve survivorship following PF arthroplasty. The purpose of this study is to compare the use of a preoperative bone scan vs a magnetic resonance imaging (MRI) to identify the patient with isolated PF arthritis.

METHODS

This is a retrospective review of 32 patients undergoing isolated PF arthroplasty for PF arthritis using the same implant design. Sixteen consecutive patients received a preoperative bone scan to confirm isolated PF arthritis. These patients were matched by age and gender to patients where an MRI was used to determine isolated PF arthritis. The bone scan cohort contained 13 females and three males with an average age of 48 years and average follow-up of 52 months. There was no significant difference in age, body mass index, follow-up, or preoperative range of motion between the groups. The MRI and bone scan results were reported by a radiologist specializing in orthopedic radiology.

RESULTS

Survivorship was 100% in the PF arthroplasty group selected using a preoperative bone scan. Revision surgery with conversion to TKA was required in 5 of 16 patients (31%) when an MRI was used to identify isolated PF arthritis. Revision in all patients in the MRI group was due to progression of knee arthritis in the tibial-femoral joint. There were no cases of implant-related failures.

CONCLUSION

Patellofemoral arthroplasty using a modern design implant demonstrated 100% survivorship when a preoperative bone scan was used for patient selection to confirm isolated PF arthritis. In the group where only an MRI was used, there was a 31% failure due to progression of the disease. Based on this study, we would recommend the use of a bone scan as a tool in the selection criteria for patients undergoing PF arthroplasty.

Mid-term survivorship and patient-reported outcomes of robotic-arm assisted partial knee arthroplasty

Aims

Limited evidence is available on mid-term outcomes of robotic-arm assisted (RA) partial knee arthroplasty (PKA). Therefore, the purpose of this study was to evaluate mid-term survivorship, modes of failure, and patient-reported outcomes of RA PKA.

Methods

A retrospective review of patients who underwent RA PKA between June 2007 and August 2016 was performed. Patients received a fixed-bearing medial or lateral unicompartmental knee arthroplasty (UKA), patellofemoral arthroplasty (PFA), or bicompartmental knee arthroplasty (BiKA; PFA plus medial UKA). All patients completed a questionnaire regarding revision surgery, reoperations, and level of satisfaction. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were assessed using the KOOS for Joint Replacement Junior survey.

Results

Mean follow-up was 4.7 years (2.0 to 10.8). Five-year survivorship of medial UKA (n = 802), lateral UKA (n = 171), and PFA/BiKA (n = 35/10) was 97.8%, 97.7%, and 93.3%, respectively. Component loosening and progression of osteoarthritis (OA) were the most common reasons for revision. Mean KOOS scores after medial UKA, lateral UKA, and PFA/BiKA were 84.3 (SD 15.9), 85.6 (SD 14.3), and 78.2 (SD 14.2), respectively. The vast majority of the patients reported high satisfaction levels after RA PKA. Subgroup analyses suggested tibial component design, body mass index (BMI), and age affects RA PKA outcomes. Five-year survivorship was 98.4% (95% confidence interval (CI) 97.2 to 99.5) for onlay medial UKA (n = 742) and 99.1% (95% CI 97.9 to 100) for onlay medial UKA in patients with a BMI < 30 kg/m2 (n = 479).

Conclusion

This large single-surgeon study showed high mid-term survivorship, satisfaction levels, and functional outcomes in RA UKA using metal-backed tibial onlay components. In addition, favourable results were reported in RA PFA and BiKA. Cite this article: Bone Joint J 2020;102-B(1):108–116

The midterm results of a cohort study of patellofemoral arthroplasty from a non-designer centre using an asymmetric trochlear prosthesis

PURPOSE

Patellofemoral arthroplasty (PFA) prosthesis with asymmetric trochlear component was introduced as an improvement from existing designs for surgical treatment of symptomatic isolated patellofemoral arthritis. The purpose of this study was to evaluate midterm results in patients who underwent PFA procedure using such prosthesis.

METHODS

Our study involved a continuous retrospective cohort of patients who underwent PFA using Journey PFA prosthesis with an asymmetric trochlear component, performed between June 2007 and July 2016 at a non-designer centre. The Patient Reported Outcome Measures and patient satisfaction questionnaires were collected for final evaluation.

RESULTS

A total of 103 PFA performed on 79 patients were evaluated. Median age at the time of surgery was 58years (range 42 to 78years); the mean follow-up period was 6 years (range 2 to 11years). Four knees were revised to Total Knee Arthroplasty for reasons not related to the implant. The cumulative survival estimated by the Kaplan-Meier method was 94.3% (95% confidence interval: 88.4%-100%). There were statistically significant improvements in functional outcome scores.

CONCLUSION

This series of patients who underwent PFA with the asymmetric trochlear component has shown promising mid-term results with no implant-related complications.

The Clinical Outcome of Patellofemoral Arthroplasty vs Total Knee Arthroplasty in Patients Younger Than 55 Years

BACKGROUND

Patellofemoral osteoarthritis affects 10% of patients older than 40 years and is commonly treated by patellofemoral joint arthroplasty (PFA) or a total knee arthroplasty (TKA). PFA is a more conservative approach with documented faster recovery. No study to date has compared both approaches with respect to patient-reported outcome measures in patients younger than 60 years.

METHODS

A retrospective case-matched cohort based on age, sex, body mass index, and side of 23 PFAs (in 19 patients) operated on by 2 surgeons and of 23 TKAs (23 patients) operated on by 6 surgeons was included in the study. All patients were younger than 55 years and operated on between March 2010 and September 2015. The Western Ontario and McMaster Osteoarthritic Index, Knee injury and Osteoarthritis Outcome scores, Tegner, and University of California, Los Angeles activity scores were compared between preoperative and minimum 2-year postoperative timepoints between groups.

RESULTS

TKA and PFA were comparable on all patient-reported outcome measures at minimum 2-year follow-up; however, PFA patients exhibited statistically significantly larger improvement between 1 year postoperative and 2 years postoperative timepoints (P < .05). All patients improved between preoperative and postoperative timepoints (P < .05).

CONCLUSION

Although TKA performed better with respect to functional outcomes at the 1-year mark, at 2-year follow-up, PFA and TKA performed equally well. Our results allow us to conclude that in younger patients with isolated patellofemoral osteoarthritis who desire a more conservative, kinematic-preserving approach, PFA continues to be a practical treatment option yielding early outcomes that compare favorably with TKA.

Failure modes of patellofemoral arthroplasty-registries vs. clinical studies: a systematic review

Background and purpose - Patellofemoral arthroplasty (PFA) has been debated since early studies showed poor implant survival. Recent studies show better results. This review reports failure modes for PFA and investigates differences in data reported from registries and clinical studies. Additionally, we report differences in failure modes among implant designs. Methods - A systematic search was performed in September 2018. All studies and registers describing failure modes of PFA were included and implant design was noted for each revision. Results - This review includes 1,299 revisions of a primary PFA reported in 47 clinical studies and 3 registers. The failure modes were: 42% OA progression, 16% pain, 13% aseptic loosening, 12% surgical error, 4% wear, 2% infection, 2% broken patellar component, 1% stiffness, 1% fracture, and 7% other. The data from registries and cohort studies differed statistically significantly in 7 out of 12 failure modes. Significant differences were found in several failure modes among implant designs. Interpretation - OA progression is the most common failure mode of PFA. There are significant differences in data on failure modes between registers and protocolled studies, notably for surgical error. The implant design significantly influences several of the failure modes. In conclusion, indication, surgical technique, and implant design are important for a successful PFA, and register-based failure modes should be interpreted with caution.

Similar postoperative patient-reported outcome in both second generation patellofemoral arthroplasty and total knee arthroplasty for treatment of isolated patellofemoral osteoarthritis: a systematic review

INTRODUCTION

Due to inconsistent results and high failure rates, total knee arthroplasty (TKA) is more often used to treat isolated patellofemoral osteoarthritis (PFOA) despite the theoretical advantage of patellofemoral arthroplasty (PFA). It is perceived that second-generation PFA may have improved the outcomes of surgery. In this systematic review, the primary aim was to compare outcomes of second-generation PFA and TKA by assessment of patient-reported outcome measures (PROMs).

METHODS

A systematic search was made in PubMed, Medline, Embase, Cinahl, Web of Science, Cochrane Library and MeSH to identify studies using second-generation PFA implants or TKA for treatment of PFOA. Only studies using The American Knee Society (AKSS), The Oxford Knee Score (OKS) or The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) to report on PROMs were included.

RESULTS

The postoperative weighted mean AKSS knee scores were 88.6 in the second-generation PFA group and 91.8 in the TKA group. The postoperative weighted mean AKSS function score was 79.5 in the second-generation PFA group and 86.4 in the TKA group. There was no significant difference in the mean AKSS knee or function scores between the second-generation PFA group and the TKA group. The postoperative weighted mean OKS score was 36.7 and the postoperative weighted mean WOMAC score was 24.4. The revision rate was higher in the second-generation PFA group (113 revisions [8.4%]) than in the TKA group (3 revisions [1.3%]). Progression of OA was most commonly noted as the reason for revision of PFA, and it was noted in 60 cases [53.1%]; this was followed by pain in 33 cases [29.2%].

CONCLUSION

Excellent postoperative weighted mean AKSS knee scores were found in both the second-generation PFA group and in the TKA group, suggesting that both surgical options can result in a satisfying patient-reported outcome. Higher revision rates in the second-generation PFA studies may in part be due to challenges related to patient selection. Based on evaluation of PROMs, the use of second-generation PFA seems to be an equal option to TKA for treatment of isolated PFOA in appropriately selected patients. Hopefully, this can be considered by physicians in their daily clinical work.

LEVEL OF EVIDENCE

IV.

Patella alta and patellar subluxation might lead to early failure with inlay patello-femoral joint arthroplasty

PURPOSE

With the growing interest in resurfacing procedures, several new implants have been recently introduced for isolated patello-femoral joint arthroplasty (PFA). However, not much data are available for these new techniques or about the right indications for each type of implant.

METHODS

Out of a retrospective cohort of 20 inlay PFA, 11 PFA with an elevated Insall-Salvati index and an increased patello-femoral congruence angle showed an initial satisfactory result, but presented thereafter with recurrent pain and "clunk" phenomena. They were all revised after a median time of 25 months (range 8-28 months) into an onlay technique PFA and analyzed for their failure mode and revision technique.

RESULTS

Clinical symptoms such as clunking, as well as abraded areas craniolateral of the inlay implant found intraoperatively, were the main observations of this study. The modified Insall-Salvati index (mISI) was significantly higher in the revised knees compared to the unrevised (median 1.8 versus 1.6; p = 0.041). VAS and KSS significantly improved after revision (median VAS reduction in pain of 4.0 points, median KSS improvement of 20.0 points; p < 0.05).

CONCLUSION

Patients with high-normal patellar height index or patella alta, as well as a craniolateral type of arthritis with additional lateralization, should be considered contra-indicated for an inlay technique PFA. They could be considered for a PFA system reaching further proximal into the distal femur. An onlay PFA can be an option for early revision of failed inlay implants. The clinical relevance of this study is that patella alta and patellar subluxation are more difficult to adjust for with an inlay PFJ component.

LEVEL OF EVIDENCE

Level IV.

Return to the operating room after patellofemoral arthroplasty versus total knee arthroplasty for isolated patellofemoral arthritis-a systematic review

PURPOSE

Patellofemoral arthroplasty (PFA) and total knee arthroplasty (TKA) are accepted treatments for end-stage isolated patellofemoral osteoarthritis (PFOA). However, complications and re-operations have historically differed between the two procedures. We performed a systematic review to report on the re-operation rates between TKA and modern PFA for isolated PFOA.

METHODS

Systematically identified publications reporting on patients that underwent either TKA or modern PFA for isolated PFOA were reviewed. Meta-analysis software was used to screen potential articles with at least one year follow-up that detailed reasons for re-operation. Data was extracted and analyzed for all re-operations. Survival of the implant was used as the primary outcome; return to the operating room (OR) for any reason was used as a secondary outcome.

RESULTS

The weighted rate of either conversion or revision arthroplasty in the PFA group and the TKA group was 6.34 and 0.11, respectively. The weighted rate of return to the OR for bony and soft tissue procedures was 1.06 and 0.79, respectively. The weighted rate of manipulation under anaesthesia (MUA) was 0.32 and 1.23, respectively.

CONCLUSION

Patients who undergo PFA may be more likely to return to the operating room for conversion to TKA and/or revision surgery than those who undergo TKA.

Patellofemoral arthroplasty versus total knee arthroplasty for patients with patellofemoral osteoarthritis: equal function and satisfaction but higher revision rate for partial arthroplasty at a minimum eight years’ follow-up

AIMS

The primary aim of this study was to compare the knee-specific functional outcome of patellofemoral arthroplasty with total knee arthroplasty (TKA) in the management of patients with patellofemoral osteoarthritis.

PATIENTS AND METHODS

A total of 54 consecutive Avon patellofemoral arthroplasties were identified and propensity-score-matched to a group of 54 patients undergoing a TKA with patellar resurfacing for patellofemoral osteoarthritis. The Oxford Knee Score (OKS), the 12-Item Short-Form Health Survey (SF-12), and patient satisfaction were collected at a mean follow up of 9.2 years (8 to 15). Survival was defined by revision or intention to revise.

RESULTS

There was no significant difference in the mean OKS (p > 0.60) or SF-12 scores (p > 0.28) between the groups. There was a lower rate of satisfaction at the final follow-up for the TKA group (78% vs 87%) but this was not statistically significant (odds ratio 0.56, p = 0.21). Length of stay was significantly shorter (p = 0.008) for the Avon group (difference 1.8 days, 95% confidence interval (CI) 0.4 to 3.2). The ten-year survival for the Avon group was 92.3% (95% CI 87.1 to 97.5) and for the TKA group was 100% (95% CI 93.8 to 100). This difference was not statistically significant (log-rank test, p = 0.10).

CONCLUSION

Patients undergoing an Avon patellofemoral arthroplasty have a shorter length of stay, and a functional outcome and rate of satisfaction that is equal to that of TKA. The benefits of the Avon arthroplasty need to be balanced against the increased rate of revision when compared with TKA.

Patient-reported outcome measures (PROMs) in patients undergoing patellofemoral arthroplasty and total knee replacement: A comparative study

BACKGROUND

Incongruity in the evaluation of outcomes between patients and surgeons has led to an increasing utilization of patient-reported outcome measures (PROMs) as an evaluation method of outcome.

OBJECTIVE

The aim of this study was to compare Oxford Knee Score (OKS), KOOS-PS and Kujala Score results in patients who received either PFA or TKA with and without patella resurfacing in the tretament of knee osteoarthritis.

METHODS

A total of 50 patients (PFA = 19 patients; TKA with patelloplasty = 15 patients; TKA with patellar resurfacing = 16 patients) undergone surgery between 2011 and 2014 and were included for final analysis.

RESULTS

No statistical significance was found for OKS, KOOS-PS and Kujala scores between the three groups. However, although patients with PFA experienced higher levels of pain.

CONCLUSIONS

According to our results, it is essential to discuss the treatment options and quality of life expectations with the patient prior joint replacement surgery in order to reduce patient dissatisfaction.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The Avon patellofemoral joint arthroplasty: two- to 18-year results of a large single-centre cohort

Aims

This study reports on the medium- to long-term implant survivorship and patient-reported outcomes for the Avon patellofemoral joint (PFJ) arthroplasty.

Patients and Methods

A total of 558 Avon PFJ arthroplasties in 431 patients, with minimum two-year follow-up, were identified from a prospective database. Patient-reported outcomes and implant survivorship were analyzed, with follow-up of up to 18 years.

Results

Outcomes were recorded for 483 implants (368 patients), representing an 86% follow-up rate. The median postoperative Oxford Knee Score (0 to 48 scale) was 35 (interquartile range (IQR) 25.5 to 43) and the median Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, 0 to 100 scale) was 35 (IQR 25 to 53) at two years. There were 105 revisions, 61 (58%) for progression of osteoarthritis. All documented revisions were to primary knee systems without augmentation. The implant survival rate was 77.3% (95% confidence interval (CI) 72.4 to 81.7, number at risk 204) at ten years and 67.4% (95% CI 72.4 to 81.7 number at risk 45) at 15 years. Regression analysis of explanatory data variable showed that cases performed in the last nine years had improved survival compared with the first nine years of the cohort, but the individual operating surgeon had the strongest effect on survivorship.

Conclusion

Satisfactory long-term results can be obtained with the Avon PFJ arthroplasty, with maintenance of patient-reported outcome measures (PROMs), satisfactory survival, and low rates of loosening and wear. Cite this article: Bone Joint J 2018;100-B:1162-7.

No bias for developer publications and no difference between first-generation trochlear-resurfacing versus trochlear-cutting implants in 15,306 cases of patellofemoral joint arthroplasty

PURPOSE AND HYPOTHESIS

The study aim was to assess the outcome of patellofemoral arthroplasty (PFA), paying particular interest to 'revisions for any reason'. The hypothesis was that there is a superior outcome of PFA reported in dependent clinical studies in contrast to independent clinical literature and that there is a superior outcome of 'trochlear-cutting' PFA in comparison with 'first-generation trochlear-resurfacing' implants.

METHODS

Studies on PFA from its market introduction in 1955 onwards were systematically reviewed. The revision rate, which was calculated as 'revisions per 100 component years (CY)', was evaluated in 45 studies published in indexed, peer-reviewed international scientific journals. In addition, 'first-generation trochlear-resurfacing' and 'trochlear-cutting' implants as well as dependent and independent clinical literature were analysed. Furthermore, the data of three arthroplasty registers were analysed.

RESULTS

A total of 15,306 PFA were included consisting of 2266 cases in worldwide literature data and of 13,040 cases in register data. 2.22 revisions per 100 CY were observed in worldwide literature data, which corresponds to a revision rate of 22.2% after 10 years. Revision rates between 18.9 and 27% after 10 years were shown by the included three national joint registers. In the group analyses no significant differences were detected.

CONCLUSIONS

This meta-analysis did not reveal significant differences in the comparison between developer over independent publications and between 'first-generation-resurfacing' over 'trochlear-cutting' implants. In conclusion the data of developer publications do not seem to be biased. 'Trochlear-cutting' devices of PFA had slightly superior outcomes, but that benefit was not statistically significant. Nevertheless, we would recommend 'trochlear-cutting' devices for further use in PFA.

LEVEL OF EVIDENCE

Meta-analysis of Level IV case series.

Mid-Term Clinical, Functional, and Radiographic Outcomes of 105 Gender-Specific Patellofemoral Arthroplasties, With or Without the Association of Medial Unicompartmental Knee Arthroplasty

BACKGROUND

The purpose of this study is to evaluate clinical and radiographic outcomes after gender-specific patellofemoral arthroplasty (PFA) either isolated or combined with unicompartmental knee arthroplasty (UKA).

METHODS

A total of 105 PFAs in 85 patients were reviewed: 64 knees had isolated patellofemoral osteoarthritis and received an isolated PFA, and 41 knees with bicompartmental osteoarthritis were treated with medial UKA and PFA. Preoperative and postoperative clinical and functional assessment included knee range of motion, Knee Society Score, University of California Los Angeles Activity Score, Tegner Activity Level Scale, and visual analogue scale pain. Preoperative and postoperative radiographs were evaluated for patellofemoral and tibiofemoral compartment osteoarthritis, trochlear dysplasia, changes in patellar height, and signs of osteolysis.

RESULTS

At a mean follow-up of 5.5 ± 1.6 years, both groups showed improvement in knee joint range of motion (P < .001), clinical and functional Knee Society Score (P < .001), University of California Los Angeles Activity Score (P < .001 in the PFA group and P = .004 in the UKA + PFA group), and visual analogue scale pain (P < .001). There were no statistically significant postoperative differences between the 2 groups. No signs of osteolysis or subsidence were recorded. Survivorship of these 105 implants was 95.2%.

CONCLUSION

Excellent clinical and radiographic outcomes were achieved after PFA with a gender-specific implant both as isolated replacement and when combined with medial UKA. Bicompartmental replacement with small implants can be considered in patients with bicompartmental osteoarthritis and intact anterior cruciate ligament.

Mid-term survivorship and clinical outcomes of the Avon patellofemoral joint replacement

BACKGROUND

We present the largest series of Avon patellofemoral joint (PFJ) replacements outside of the design centre. There is discussion over its efficacy and usefulness. We report an independent opinion of its indications, survivorship and outcomes.

METHODS

We prospectively collected demographic data and patient reported outcome measures (PROM's) on our cohort of Avon Patellofemoral replacements since its adoption in our unit in 2003 until 2014. We performed a retrospective review of radiographs.

RESULTS

We performed 103 PFJ replacements in 85 patients, 36 were male (mean age 61 - range 34 to 78) and 67 female (mean age 60 - range 38 to 82), mean follow up time was 5.6years (range 2.9 to 14.2years) with 93 implants still in situ. Their mean post-operative Oxford Knee Score was 36 (range seven to 48). There were nine conversions to TKR for disease progression and one revision of a femoral component for trochlear malpositioning. Mean time to revision was 2.9years (1.0 to 6.0years). Radiographic evidence of progression on Kellgren and Lawrence score in the un-replaced compartments was demonstrated in 23% of cases with imaging available. The Avon PFJ replacement delivers reproducible and effective pain relief and function to patients with isolated patellofemoral osteoarthritis. We believe PFJ replacement has an important role to play, and we will continue to perform this procedure for a carefully selected group of patients. Conversion to TKR does not and should not be regarded as failure of the index operation.

The Mark Coventry Award: Patellofemoral Arthroplasty Results in Better Range of Movement and Early Patient-reported Outcomes Than TKA

BACKGROUND

Controversy exists over the surgical treatment for severe patellofemoral osteoarthritis. We therefore wished to compare the outcome of patellofemoral arthroplasty (PFA) with TKA in a blinded randomized controlled trial.

QUESTIONS/PURPOSES

In the first 2 years after surgery: (1) Does the overall gain in quality of life differ between the implants based on the area under the curve of patient-reported outcomes (PROs) versus time? (2) Do patients obtain a better quality of life at specific points in time after PFA than after TKA? (3) Do patients get a better range of movement after PFA than after TKA? (4) Does PFA result in more complications than TKA?

METHODS

Patients were eligible if they had debilitating symptoms and isolated patellofemoral disease. One hundred patients were included from 2007 to 2014 and were randomized to PFA or TKA (blinded for the first year; blinded to patient, therapists, primary care physicians, etc; quasiblinded to assessor). Patients were seen for four clinical followups and completed six sets of questionnaires during the first 2 postoperative years. SF-36 bodily pain was the primary outcome. Other outcomes were range of movement, PROs (SF-36, Oxford Knee Score [OKS], Knee injury and Osteoarthritis Outcome Score [KOOS]) as well as complications and revisions. Four percent (two of 50) of patients died within the first 2 years in the PFA group (none in the TKA group), and 2% (one of 50) became ill and declined further participation after 1 year in the PFA group (none in the TKA group). The mean age at inclusion was 64 years (SD 8.9), and 77% (77 of 100) were women.

RESULTS

The area under the curve (AUC) up to 2 years for SF-36 bodily pain of patients undergoing PFA and those undergoing TKA was 9.2 (SD 4.3) and 6.5 (SD 4.5) months, respectively (p = 0.008). The SF-36 physical functioning, KOOS symptoms, and OKS also showed a better AUC up to 2 years for PFA compared with TKA (6.6 [SD 4.8] versus 4.2 [SD 4.3] months, p = 0.028; 5.6 [SD 4.1] versus 2.8 [SD 4.5] months, p = 0.006; 7.5 [SD 2.7] versus 5.0 [SD 3.6] months, p = 0.001; respectively). The SF-36 bodily pain improvement at 6 months for patients undergoing PFA and those undergoing TKA was 38 (SD 24) and 27 (SD 23), respectively (p = 0.041), and at 2 years, the improvement was 39 (SD 24) and 33 (SD 22), respectively (p = 0.199). The KOOS symptoms improvement at 6 months for patients undergoing PFA and those undergoing TKA was 24 (SD 20) and 7 (SD 21), respectively (p < 0.001), and at 2 years, the improvement was 27 (SD 19) and 17 (SD 21), respectively (p = 0.023). Improvements from baseline for KOOS pain, SF-36 physical functioning, and OKS also differed in favor of PFA at 6 months, whereas only KOOS symptoms showed a difference between the groups at 2 years. No PRO dimension showed a difference in favor of TKA. At 4 months, 1 year, and 2 years, the ROM change from baseline for patients undergoing PFA and those undergoing TKA was (-7° [SD 13°] versus -18° [SD 14°], p < 0.001; -4° [SD 15°] versus -11° [SD 12°], p = 0.011; and -3° [SD 12°] versus -10° [SD 12°], p = 0.010). There was no difference in the number of complications. During the first 2 postoperative years, there were two revisions in patients undergoing PFA (one to a new PFA and one to a TKA).

CONCLUSIONS

Patients undergoing PFA obtain a better overall knee-specific quality of life than patients undergoing TKA throughout the first 2 years after operation for isolated patellofemoral osteoarthritis. At 2 years, only KOOS function differs between patients undergoing PFA and those undergoing TKA, whereas other PRO dimensions do not show a difference between groups. The observations can be explained by patients undergoing PFA recovering faster than patients undergoing TKA and the functional outcome being better for patients undergoing PFA up to 9 months. Patients undergoing PFA regain their preoperative ROM, whereas patients undergoing TKA at 2 years have lost 10° of ROM. We found no differences in complications.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Patellofemoral arthroplasty: Current concepts

Isolated patellofemoral arthritis (IPA) is a debilitating condition characterised by a loss of articular cartilage on the patella facets, the trochlear groove or both. By definition, patients with IPA must have normal cartilage in the tibiofemoral compartments of their knee. It is therefore logical to pursue arthroplasty which corrects the abnormality while sparing healthy bone and preserving the knee's native kinematics, which is the premise underpinning patellofemoral arthroplasty (PFA). However, its use remains controversial, with many surgeons still favouring total knee replacement (TKR) in these patients. This paper provides a comprehensive review of PFA in the literature to date and concludes, in carefully selected patients, PFA is worthy of consideration as a functionally superior and economically beneficial joint-preserving procedure - delaying TKR until implant failure or tibiofemoral osteoarthritis progression.

Patellofemoral Arthroplasty: Current Concepts and Review of the Literature

Patellofemoral osteoarthritis (PFOA) can be associated with anterior knee pain, stiffness, and functional impairment. Some authors report that PFOA affects approximately 9% of patients older than 40 years with a greater prevalence in females. Etiology of PFOA is multifactorial and is related to the presence of abnormal stresses at the PF joint due to knee- and patient-related factors. The need for a joint preserving treatment by isolated replacement of the injured compartment of the knee led to the development of PF arthroplasty (PFA). When a correct PF replacement is performed, PFA preserves physiologic tibiofemoral joint, thus allowing patients for a rapid recovery with a high satisfaction. The outcomes for PFA are quite variable with a trend toward good to excellent results, mainly owing to the improvement in surgical techniques, patient selection, and implant design. The development of the second generation of PFA improved the outcomes, which is attributed to the different trochlear designs. Recently, encouraging results have been provided by the association of PFA and unicompartmental knee arthroplasty (UKA). In many studies, the main cause of PFA failure is progression of tibiofemoral OA. The aim of this brief review of literature is to summarize the clinical features, indications and contraindications, surgical techniques, complications, and outcomes of PFA.

A matched-pair comparison of inlay and onlay trochlear designs for patellofemoral arthroplasty: no differences in clinical outcome but less progression of osteoarthritis with inlay designs

PURPOSE

To compare clinical and radiographic results after isolated patellofemoral arthroplasty (PFA) using either a second-generation inlay or onlay trochlear design. The hypothesis was that an inlay design will produce better clinical results and less progression of tibiofemoral osteoarthritis (OA) compared to an onlay design.

METHODS

Fifteen consecutive patients undergoing isolated PFA with an onlay design trochlear component (Journey™ PFJ, Smith & Nephew) were matched with 15 patients after isolated PFA with an inlay design trochlear component (HemiCAP^® Wave, Arthrosurface). Matching criteria were age, gender, body mass index, and follow-up period. An independent observer evaluated patients prospectively, whereas data were compared retrospectively. Clinical outcome was assessed using WOMAC, Lysholm score, and pain VAS. Kellgren-Lawrence grading was used to assess progression of tibiofemoral OA.

RESULTS

Conversion to total knee arthroplasty was necessary in one patient within each group, leaving 14 patients per group for final evaluation. The mean follow-up was 26 months in the inlay group and 25 months in the onlay group (n.s.). Both groups displayed significant improvements of all clinical scores (p < 0.05). No significant differences were found between the two groups with regard to the clinical outcome and reoperation rate. No significant progression of tibiofemoral OA was observed in the inlay group, whereas 53 % of the onlay group showed progression of medial and/or lateral tibiofemoral OA (p = 0.009).

CONCLUSION

Isolated PFA using either a second-generation inlay or onlay trochlear component significantly improves functional outcome scores and pain. The theoretical advantages of an inlay design did not result in better clinical outcome scores; however, progression of tibiofemoral OA was significantly less common in patients with an inlay trochlear component. This implant design may therefore improve long-term results and survival rates after isolated PFA.

LEVEL OF EVIDENCE

III.

Patellofemoral Joint Arthroplasty: Early Results and Functional Outcome of the Zimmer Gender Solutions Patello-Femoral Joint System

Background

Improved knee prosthesis designs have led to an increase in the use of patellofemoral arthroplasty as a primary treatment option in recent times. We report the early results and outcomes of the Zimmer Gender Solutions Patello-Femoral Joint (PFJ) system used to treat isolated patellofemoral osteoarthritis (PFA).

Methods

We retrospectively reviewed and analysed data of patients who underwent PFJ replacement (PFJR) at our institution with a minimum follow-up of 2 years.

Results

Median Oxford Knee score (OKS) was 38 (interquartile range, 28 to 42) at the latest follow-up with a significant improvement from preoperative scores (p < 0.0005). Median OKS was 40 for unilateral PFJRs and 39 for nonobese patients (body mass index [BMI] < 30 kg/m²). There was no significant difference in OKS between unilateral and bilateral procedures (p = 0.462). Likewise, there was no significant difference in OKS between obese and nonobese patients (p = 0.272). Two knees (4%) were revised for progression of osteoarthritis. No complications were reported related to infectious or thromboembolic causes.

Conclusions

Our study showed good early results of the PFJ system, at least equal to those of other leading brands in the National Joint Registry for England, Wales and Northern Ireland (NJR). There have been no complications related to either the implantation technique or prosthetic design for this new implant. Progression of tibiofemoral arthritis remains a major concern. Our study also suggests that PFJR in obese patients and bilateral procedures can have good results.