Indications, contraindications, and pitfalls of patellofemoral arthroplasty

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.

Should we recommend patellofemoral arthroplasties to patients?

Aims

With up to 40% of patients having patellofemoral joint osteoarthritis (PFJ OA), the two arthroplasty options are to replace solely the patellofemoral joint via patellofemoral arthroplasty (PFA), or the entire knee via total knee arthroplasty (TKA). The aim of this study was to assess postoperative success of second-generation PFAs compared to TKAs for patients treated for PFJ OA using patient-reported outcome measures (PROMs) and domains deemed important by patients following a patient and public involvement meeting.

Methods

MEDLINE, EMBASE via OVID, CINAHL, and EBSCO were searched from inception to January 2022. Any study addressing surgical treatment of primary patellofemoral joint OA using second generation PFA and TKA in patients aged above 18 years with follow-up data of 30 days were included. Studies relating to OA secondary to trauma were excluded. ROB-2 and ROBINS-I bias tools were used.

Results

A total of nine studies were included, made up of four randomized controlled trials (domain 1) and five cohort studies (domain 2). PROMs and knee function specific scores developed for reporting TKA were unable to detect any difference between PFA and TKA. There was no significant difference in complications between PFA and TKA. PFAs were found to have a better postoperative range of motion.

Conclusion

TKA and PFA are both viable options for patients with primary PFJ OA. Over time, we have seen an emphasis on patient satisfaction and better quality of life. Recommending sacrificing healthy medial and lateral compartments to treat patellofemoral joint arthritis should be given further thought.

Patellofemoral arthroplasty: expert opinion

Isolated patellofemoral osteoarthritis (PFOA) is a common cause of anterior knee pain in patients over the age of 40 years. Patellofemoral arthroplasty (PFA) is an option to address PFAO when the non-operative or joint preserving management has failed.The goals of PFA are to reduce pain and increase function of the knee in a bone and ligament preserving fashion while maintaining or optimizing its kinematics. Over the last decades advances have been made in optimizing implants designs, addressing complications and improving functional and patient reported outcomes. Appropriate patient selection has proven to be imperative. Proper surgical technique and knowledge of pearls and pitfalls is essential.The indications and surgical technique for patellofemoral arthroplasty will be reviewed here.Level of evidence: Therapeutic Level V.

Pre-operative patella alta does not affect midterm clinical outcomes and survivorship of patellofemoral arthroplasty

PURPOSE

The purpose of this study was to evaluate the effect of preoperative patella alta on clinical outcomes, survivorship, and complication and reoperation rates on patellofemoral arthroplasty (PFA).

METHODS

All patients who underwent PFA for isolated patellofemoral arthritis by a single surgeon at our institution were identified. Preoperative radiographs were measured by two independent observers for patellar height using the Caton Deschamps (CD), Insall-Salvati (IS), and Blackburne-Peele (BP) methods. Patients were classified as either "patella alta" or "non-patella alta" for all three measurement methods. Clinical scores including KSS Pain, KSS Function, and Tegner Activity Scores were collected pre- and post-operatively. Failure was defined as conversion to total knee arthroplasty (TKA). Clinical outcomes and survivorship were compared between patients with "patella alta" and "non-patella alta" height measurements.

RESULTS

There were 119 patients with 153 knees (86% female) included in the study with a mean age of 55.8 years. Outcome scores improved from pre-operative to post-operative for both patella alta and non-patella alta patients for Tegner, KSS pain and KSS function scores. The mean change in Tegner scores for patella alta and non-patella alta patients were not significantly different for CD (p = 0.24), IS (p = 0.25) or BP measurements (p = 0.39). The mean change in KSS pain scores between groups were not significantly different for CD (p = 0.33) or IS measurements (p = 0.22), but was improved more significantly in patella alta patients vs non-patella alta patients (21.2 and 14.4; p = 0.02) for BP measurement. The mean change in KSS function scores between groups was not significantly different for CD (p = 0.61) IS (p = 0.90) or BP measurements (p = 0.79). The overall survivorship from conversion to total knee arthroplasty (TKA) was 94.1% at a mean follow-up time of 5.0 (SD 2.6) years. There were no significant differences in survivorship from TKA between patella alta and non-patella alta groups (CD: p = 0.72, IS: p = 0.63, BP: p = 0.66).

CONCLUSIONS

This study suggests that there are no significant differences in clinical outcome scores or survivorship from TKA between patella alta and non-patella alta patients who underwent onlay design PFA. Both patella alta and non-patella alta patients demonstrated excellent improvement in outcome scores from pre-operative to post-operative.

LEVEL OF EVIDENCE

IV.

Patellofemoral arthroplasty versus total knee arthroplasty for isolated patellofemoral osteoarthritis: a systematic review and meta-analysis

BACKGROUND

Isolated patellofemoral osteoarthritis (PF-OA) is a common subtype of knee osteoarthritis, leading to a huge economic burden on health care systems. Although previous studies have shown that patellofemoral arthroplasty (PFA) and total knee arthroplasty (TKA) have good clinical effects, it remains largely unclear which treatment is more effective for patients with isolated PF-OA. We aimed to compare postoperative function, complications, revision rates, level of physical activity, and satisfaction rate between the two surgical techniques.

METHODS

Our study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Search of literature was conducted in MEDLINE, EMBASE, Cochrane Library, and Web of Science until November 2020. The included studies were those that provided direct comparison of postoperative outcomes between PFA and TKA. Data were extracted from eligible studies and combined to calculate the pooled odds ratio (OR) and 95% confidence interval (CI). Sensitivity analysis and subgroup analysis were conducted to evaluate heterogeneity between the two groups.

RESULTS

A total of 7 eligible studies (3 recent randomized controlled trials and 4 nonrandomized controlled trials) were included in this meta-analysis. The pooled results showed that both the PFA group and the TKA group had improved postoperative indicators, suggesting that the two operation modes could improve the knee function and quality of life of patients. Throughout the first 2 years postoperatively, higher activity level, and better functional recovery were observed for PFA compared with TKA in this study; moreover, the differences between the two operation modes were statistically significant (p < 0.05). We found no significant difference in complications, revision rates, and satisfaction rate between the two procedures.

CONCLUSION

Although there was no observed difference in the complications, revision rates, and satisfaction rate between PFA and TKA, PFA was superior to TKA in terms of knee function and physical activity in the first 2 years postoperatively. Therefore, PFA is a safe, effective, and less invasive treatment for patients with isolated PF-OA. Our findings are consistent with the systematic review of current evidence that PFA may be more suitable for younger patients with high activity needs. Patient selection is, therefore, thought to be of paramount importance. Individualized surgical plan should be designed according to the patient's age, BMI, KOA site, and activity level and combined with the doctor's personal experience.

Comparing Return to Sports After Patellofemoral and Knee Arthroplasty in an Age- and Sex-Matched Cohort

Background

Return to sports is an important outcome in ensuring patient satisfaction after knee-replacement surgery. However, few studies have directly compared unicompartmental knee arthroplasty (UKA), total knee arthroplasty (TKA), and patellofemoral arthroplasty (PFA).

Hypothesis

TKA will result in lower rates of return to sports than either UKA and PFA due to increased complexity and invasiveness.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients who underwent UKA, TKA, or PFA with 1 to 2 years of follow-up were sent a questionnaire regarding return to sports, satisfaction with return to sports, pain, the University of California, Los Angeles activity scale, and the High Activity Arthroplasty Score (HAAS). The patients who underwent either TKA or UKA were matched 2:1 with regard to age and sex to patients who underwent PFA. Differences were compared using analysis of variance, t tests, and chi-square tests.

Results

A total of 202 patients were eligible. After matching, the final cohort consisted of 23 PFA patients, 46 UKA patients, and 46 TKA patients. The majority of patients were female (87%), and the mean ± SD age was 56 ± 9.1 years. The UKA group had higher HAAS values than the TKA group pre- and postoperatively (9.9 vs 7.1 [P = .001] and 12.4 vs 9.5 [P < .001], respectively). Patients with UKA had higher rates of return to sports after surgery than those with TKA or PFA (UKA, 80.5%; TKA, 71.7%; PFA, 69.5%; P = 0.08). In addition, the UKA group had the highest satisfaction with this outcome. Improvement between pre- and postoperative scores was similar in all 3 groups.

Conclusion

Patients who underwent UKA reported better activity scores and return-to-sports rates than patients who had TKA and PFA. No differences were found in improvement after surgery, suggesting that preoperative differences were reflected postoperatively. These findings inform shared decision making and can help to manage patient expectations after surgery.

What Is the Risk of Repeat Revision When Patellofemoral Replacement Is Revised to TKA? An Analysis of 482 Cases From a Large National Arthroplasty Registry

BACKGROUND

Patellofemoral replacements (PFRs) have a higher rate of revision than unicompartmental knee arthroplasty or TKA. However, there is little information regarding why PFRs are revised, the components used for these revisions, or the outcome of the revision procedure. Some contend that PFR is a bridging procedure that can easily be revised to a TKA with similar results as a primary TKA; however, others dispute this suggestion.

QUESTIONS/PURPOSES

(1) In the setting of a large national registry, what were the reasons for revision of PFR to TKA and was the level of TKA constraint used in the revision associated with a subsequent risk of rerevision? (2) Is the risk of revision of the TKA used to revise a PFR greater than the risk of revision after a primary TKA and greater than the risk of rerevision after revision TKA?

METHODS

Data were obtained from the Australian Orthopaedic Association Joint Replacement Registry through December 31, 2016, for TKA revision procedures after PFR. Because revisions for infection may be staged procedures resulting in further planned operations, for the revision analyses, these were excluded. There were 3251 PFRs, 482 of which were revised to TKA during the 17-year study period. The risk of second revision was calculated using Kaplan-Meier estimates of survivorship for PFRs revised to TKAs, and that risk was compared with the risk of first revision after TKA and also with the risk of a second revision after revision TKA. Hazard ratios (HRs) from Cox proportional hazards models were used to compare second revision rates among the different levels of prosthesis constraint used in the index revision after PFR (specifically, cruciate-retaining versus cruciate-substituting).

RESULTS

The main reasons for revising a PFR to TKA were progression of disease (56%), loosening (17%), and pain (12%). With the numbers available for analysis, there was no difference in the risk of a second revision when a PFR was revised to a cruciate-retaining TKA than when it was revised to a cruciate-substituting TKA (HR, 1.24 [0.65-2.36]; p = 0.512). A total of 204 (42%) of the PFR revisions had the patella component revised when the PFR was converted to a TKA. There difference in rates of second revision when the patella component was revised or not revised (HR, 1.01 [0.55-1.85]; p = 0.964). When we eliminated the devices that ceased to be used before 2005 (older devices), we found no change in the overall risk of repeat revision. The risk of a PFR that was revised to a TKA undergoing a second revision was greater than the risk of TKA undergoing a first revision (HR, 2.39 [1.77-3.24]; p < 0.001), but it was less than the risk of a revision TKA undergoing a second revision (HR, 0.60 [0.43-0.81]; p = 0.001).

CONCLUSIONS

The risk of second revision when a PFR is revised is not altered if cruciate-retaining or posterior-stabilized TKA is used for the revision nor if the patella component is revised or not revised. The risk of repeat revision after revision of a PFR to a TKA was much higher than the risk of revision after a primary TKA, and these findings did not change when we analyzed only devices in use since 2005. When PFR is used for the management of isolated patellofemoral osteoarthritis, patients should be counselled not only about the high revision rate of the primary procedure, but also the revision rate after TKA. Further studies regarding the functional outcomes of these procedures may help clarify the value of PFRs and subsequent revisions.

LEVEL OF EVIDENCE

Level III, therapeutic study.

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.

Advances in Patellofemoral Arthroplasty

PURPOSE OF REVIEW

To describe current indications, implants, economic benefits, comparison to TKA, and functional and patient-reported outcomes of patellofemoral arthroplasty.

RECENT FINDINGS

Modern onlay implants and improved patient selection have allowed for recent improvements in short- and long-term outcomes after patellofemoral joint replacement surgery. Patellofemoral arthroplasty has become an increasingly utilized technique for the successful treatment of isolated patellofemoral arthritis. Advances in patient selection, implant design, and surgical technique have resulted in improved performance and longevity of these implants. Although short- and mid-term data for modern patellofemoral arthroplasties appear promising, further long-term clinical studies are needed to evaluate how new designs and technologies will affect patient outcomes and long-term implant performance.

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.

Predictors of and outcomes following orthopaedic joint surgery in patients with early rheumatoid arthritis followed for 20 years

Objectives

To analyse predictors and outcomes of major orthopaedic surgery in a cohort of RA patients followed for 20 years.

Methods

Patients were recruited to the Norfolk Arthritis Register from 1990 to 1994. Demographic and clinical variables (including the HAQ and swollen and tender joint counts) were assessed at baseline; the 2010 ACR/EULAR RA classification criteria were applied. Patients reported incident comorbidities and major orthopaedic joint surgery (replacement, synovectomy, fusion, excision) when reassessed at years 1, 2, 3, 5, 7, 10, 15 and 20. Baseline and time-varying predictors of orthopaedic surgery were assessed using a conditional risk set model, a type of multiple-failure survival analysis. Change in disability after surgery was assessed using weighted mixed-effects linear regression.

Results

Of 589 RA patients [median age 56 years (IQR 45–68); 66.7% women] recruited to the Norfolk Arthritis Register with at least one follow-up, 102 reported a total of 180 major surgeries, with hip replacement being the most common (n = 68/180). Patients reporting major surgery had worse functional disability at all time points, but similar swollen/tender joint counts to those without major surgery. Each unit increase in HAQ score was associated with a doubling of the patient’s risk of having surgery by the next assessment [hazard ratio 2.11 per unit increase in HAQ (95% CI 1.64, 2.71)]. Patients had worse HAQ scores after surgery than patients not undergoing surgery [β = 0.17 (95% CI 0.03, 0.32)].

Conclusion

HAQ was the strongest predictor of future major surgery. This supports the argument that HAQ should be included in routine clinical assessment.

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.

Understanding the human knee and its relationship to total knee replacement

The knee is the intermediate joint of the lower limb and it allows the movement between the femur, tibia and patella. Under normal conditions there is a normal distribution of the load forces on these three articular components in both the static load and during ambulation. The understanding of anatomy and knee biomechanics is important for the gait analysis, the diagnosis of joint diseases and the design and development of prosthetic implants. In the last decades comprehension of knee physiology and kinematics has led to the introduction of a wide range of enhanced prosthetic implant designs for a variety of indications. There are a number of types of total knee arthroplasty implant designs, which are intended to offer the surgeon options for individual patients. The various choices imply that each specific problem has a corresponding implant that provides a reliable solution. However, until the current date, it has not been possible to produce a prosthetic design fully restoring the complex kinematics of the normal knee joint.

Isolated patellofemoral arthroplasty reproduces natural patellofemoral joint kinematics when the patella is resurfaced

PURPOSE

The objectives of this in vitro project were to compare the dynamic three-dimensional patellofemoral kinematics, contact forces, contact areas and contact pressures of a contemporary patellofemoral prosthetic implant with those of the native knee and to measure the influence of patellar resurfacing and patellar thickness. The hypothesis was that these designs are capable to reproduce the natural kinematics but result in higher contact pressures.

METHODS

Six fresh-frozen specimens were tested on a custom-made mechanical knee rig before and after prosthetic trochlear resurfacing, without and with patellar resurfacing in three different patellar thicknesses. Full three-dimensional kinematics were analysed during three different motor tasks, using infrared motion capture cameras and retroflective markers. Patellar contact characteristics were registered using a pressure measuring device.

RESULTS

The patellofemoral kinematic behaviour of the patellofemoral arthroplasty was similar to that of the normal knee when the patella was resurfaced, showing only significant (p < 0.0001) changes in patellar flexion. Without patellar resurfacing, significant more patellar flexion, lateral tilt and lateral rotation was noticed. Compared to the normal knee, contact pressures were significantly elevated after isolated trochlear resurfacing. However, the values were more than doubled after patellar resurfacing. Changes in patellar thickness only influenced the antero-posterior patellar position. There was no other influence on the kinematics, and only a limited influence on the contact pressures in the low flexion angles.

CONCLUSION

The investigated design reproduced the normal patellofemoral kinematics acceptable well when the patella was resurfaced. From a kinematic point of view, patellar resurfacing may be advisable. However, the substantially elevated patellar contact pressures remain a point of concern in the decision whether or not to resurface the patella. This study therefore not only adds a new point in the discussion whether or not to resurface the patella, but also supports the claimed advantage that a patellofemoral arthroplasty is capable to reproduce the natural knee kinematics.

Obesity and the absence of trochlear dysplasia increase the risk of revision in patellofemoral arthroplasty

PURPOSE

Proper indications and patient selection are of paramount importance in patellofemoral arthroplasty (PFA). Although factors predicting outcomes in total knee arthroplasty (TKA) have been studied, there are no such studies for modern PFA. This retrospective study reports the midterm clinical and radiological outcomes and survivorship of PFA, investigating the risk factors associated with poorer outcomes and higher revision rates.

METHODS

Fifty-one patients (51 knees) with isolated patellofemoral arthritis underwent PFA with a second-generation implant. The mean follow-up duration was 4.1 years (range, 2.2 to 6.1). The cohort was stratified into obese (body mass index (BMI)≥30 kg/m(2), n=16), overweight (BMI 25 to 29.9 kg/m(2), n=20) and control (BMI 18.5 to 24.9 kg/m(2), n=15) groups. The same cohort was stratified based on the presence (n=11) or absence (n=40) of trochlear dysplasia (TD).

RESULTS

The mean Knee Society objective and function scores, the Melbourne Knee score and the Physical Component Score of Short Form 36 improved significantly. Obesity was associated with no significant improvement in the Melbourne Knee score and the Knee Society function score (p>0.05), a higher incidence of radiographic outliers and lower patient satisfaction. There was no significant difference in outcomes between the TD and non-TD groups at two years (p>0.05), with a survivorship of 92.2%. Three revisions for progression of tibiofemoral osteoarthritis were noted in the non-TD and obese or overweight groups.

CONCLUSIONS

Patients with obesity and the absence of TD are at a potentially higher risk of revision surgery to TKA, and they should be counselled that PFA may represent a 'bridging' procedure.

LEVEL OF EVIDENCE

III.

Significant Functional Improvement at 2 Years After Isolated Patellofemoral Arthroplasty With an Onlay Trochlear Implant, But Low Mental Health Scores Predispose to Dissatisfaction

INTRODUCTION

We reviewed the clinical and radiographic outcomes of a consecutive series of patients who underwent patellofemoral arthroplasty (PFA) using a modern onlay-style trochlear design and all-polyethylene patellar component. An additional goal of the study was to elucidate, for the first time, the extent to which patients were satisfied with their implant and whether expectations were met after undergoing PFA.

METHODS AND MATERIALS

We identified a consecutive series of 70 knees (53 patients) treated with primary isolated PFA between October 2007 and May 2012. For our clinical outcomes analysis, we included patients with a minimum follow-up of 2 years and available preoperative original Knee Society scores.

RESULTS

At an average 4.9 years of follow-up, the mean range of motion and Knee Society Knee and Function scores improved significantly, and less than 4% of patients required revision arthroplasty. There was no radiographic evidence of component loosening or wear. Despite these improvements, new Knee Society scores indicated that fewer than two-thirds of patients were satisfied or had their expectations met. Dissatisfied patients and those whose expectations were not met had significantly lower Mental Health scores according to the Short Form-36 following PFA.

CONCLUSIONS

Despite the clinical and radiographic success of this implant, patient satisfaction remained low, which may be partially explained by poor mental health.

Patellar Fracture Following Patellofemoral Arthroplasty

This study aims to report the incidence of patellar fracture after patellofemoral arthroplasty (PFA) and to determine associated factors as well as outcomes of patients with and without this complication. 77 knees in 59 patients with minimum two-year follow-up were included. Seven (9.1%) patients experienced a patellar fracture at a mean of 34 (range 16-64) months postoperatively. All were treated nonoperatively. Lower BMI (P = 0.03), change in patellar thickness (P < 0.001), amount of bone resected (P = 0.001), and larger trochlear component size (P = 0.01) were associated with a greater incidence of fracture. Fewer fractures occurred when the postoperative patellar height exceeded the preoperatively measured height. No statistically significant differences were found in outcome scores between groups at mean four-year follow-up.

Four-Year Follow Up Outcome Study of Patellofemoral Arthroplasty at a Single Institution

Patellofemoral arthroplasty (PFA) is an option for younger patients with isolated patellofemoral arthritis. Older PFAs had high failure rates due to poor design. This retrospective study reports the outcomes of PFA at a single institution using a second-generation implant. Fifty-one patients (51 knees) with isolated patellofemoral arthritis underwent PFA. Mean follow-up was 4.1 years (range, 2.2-6.1). Mean Knee Society objective and function scores, Oxford Knee score, Melbourne Knee score and Physical Component Score improved significantly. 76% had their expectations fulfilled and 76% experienced good satisfaction. Mean Insall-Salvati and Caton-Deschamps ratios increased significantly. Two wound infections (3.92%) were encountered. Survivorship was 92.2% with four revisions, two due to progression of arthritis, one due to patella maltracking, and one due to anterior knee pain.

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.

What is the level of evidence substantiating the Medicare local coverage determinations?

Total joint arthroplasty (TJA) accounts for large expenditures of Medicare resources. Recovery audit contractors (RACs) utilize Local Coverage Determinations (LCDs) documents to retrospectively assess the medical necessity of performed procedures. The Florida LCD requires 3 months of documented unsuccessful nonoperative care prior to TJA. The purpose of our study was to evaluate the applicability and quality of the evidence cited in the Florida LCD for patients undergoing TJA. Applicability was assessed by evaluating the efficacy of nonoperative treatment in candidates for TJA. There were 23 citations, of which 11 mentioned nonoperative treatment and only 5 provided references. No citations provided Level I or II evidence substantiating the effectiveness of 3 months of nonoperative treatment in patients who would otherwise be candidates for TJA.

Patellofemoral arthroplasty influences tibiofemoral kinematics: the effect of patellar thickness

PURPOSE

Although controversy still remains, isolated patellofemoral arthroplasty recently gained in popularity as a treatment option for patellofemoral osteoarthritis. It has compared to total knee arthroplasty the advantage of preserving the tibiofemoral articulation, which in theory would allow the preservation of natural tibiofemoral kinematics. Today, however, no data exist to support this assumption. This study was therefore performed in order to investigate the effect of isolated patellofemoral arthroplasty on the native three-dimensional tibiofemoral kinematic behaviour and whether a change in patellar thickness would have an influence.

METHODS

Six fresh-frozen cadavers were fixed on a custom-made mechanical knee rig. Full 3D kinematics was analysed during passive flexion-extension cycles, open chain extension, with and without mechanical resistance, as well as deep knee squats, using infrared motion capture cameras and retroflective markers. Measurements were taken for the native knee and after prosthetic trochlear resurfacing with and without patellar resurfacing in three different patellar thicknesses.

RESULTS

Compared to the natural knee, patellofemoral arthroplasty resulted in significant changes in tibiofemoral kinematics, which were most pronounced in the most loaded motor tasks. Increased internal tibial rotation was noted in the mid- and high flexion ranges, reaching at 120° of flexion a mean difference of 4.5°±4.3° (p<0.0001) during squat motion, over the whole flexion range during open chain motion and in deeper flexion beyond 50° (mean at 70°, 1.9°±3.7°) during resisted open chain. During squats, also, a more posterior translation of the lateral femoral condyle was observed. The effect was accentuated in case of patella overstuffing, whereas kinematics was closer to normal with patellar thinning.

CONCLUSION

Isolated patellofemoral arthroplasty alters natural tibiofemoral kinematics, and the effects become more pronounced in case of increased patellar thickness. Therefore, it might be recommended to aim for a slight over-resection of patellar bone if sufficient bone stock is available.

Patellofemoral arthroplasty in the athlete

Patellofemoral arthritis is multifactorial and more prevalent in women and in those with high patellofemoral loading (eg, from athletics and obesity). More patients are presenting with end-stage patellofemoral arthritis at earlier ages, which is increasingly being treated with patellofemoral arthroplasty. However, these patients often desire to continue with some level of sporting activities. The goal of the surgeon is to allow the highest postoperative activity level, with safety being paramount. Unfortunately, current guidelines for sports participation after arthroplasty are based primarily on literature for total joint arthroplasty, which is largely derived from laboratory findings and level 5 evidence.

Association and impact of patellofemoral dysplasia on patellofemoral arthropathy and arthroplasty

BACKGROUND

The association of patellar and trochlear anomalies resulting in isolated patellofemoral osteoarthritis has often been postulated but rarely studied. The purpose of this study was to examine the association of patellofemoral dysplasia, specifically trochlear anomalies, which are a cause for degenerative disease and may result in a worse outcome after arthroplasty for isolated patellofemoral arthritis.

METHODS

Eighteen consecutive patients who underwent robotic image-based patellofemoral arthroplasty were compared with an age and sex-matched group of patients who underwent medial unicompartmental arthroplasty using the same image-based navigation system and had no patellofemoral, lateral disease or malalignment. The compared parameters were the patellofemoral-trochlear angle and Dejour score in the preoperative radiographs and patellofemoral-trochlear angle and internal rotation of the trochlea compared to the intercondylar line in the proximal, middle and distal trochlea.

RESULTS

Significantly higher rates of patella alta (T=5, P=0.0001) and trochlear dysplasia (6% vs. 55%) were found, as manifested by an increase in the trochlear angle and Dejour score. Furthermore, the trochlea was found to have a higher degree of internal rotation in patients with isolated patellofemoral arthritis compared to the control group.

CONCLUSIONS

In conclusion, patellofemoral anomalies such as patella alta and trochlear dysplasia are present in association with isolated patellofemoral arthritis. Isolated patellofemoral arthritis is also associated with higher rates of trochlear internal rotation. Correction of this internal rotation is essential in the success of arthroplasty in patients with patellofemoral disease.

LEVEL OF EVIDENCE

Level III study, It is a case control study.

Patellofemoral arthroplasty

Patellofemoral arthroplasty remains controversial, primarily due to the high failure rates reported with early implants. Several case series have been published over the years, which describe the results with various first- and second-generation implants. The purpose of this work was to summarize results published up to now and identify common themes for implants, surgical techniques, and indications. First-generation resurfacing implants had relatively high failure rates in the medium term. Second-generation implants, with femoral cuts based on TKA designs, have yielded more promising medium-term results. The surgical indications are quite specific and must be chosen carefully to minimize poor results. Short-term complications are generally related to patellar maltracking, while long-term complications are generally related to progression of osteoarthritis in the tibiofemoral joint. Implant loosening and polyethylene wear are rare. Overall, recent improvements in implant design and surgical techniques have resulted in better short- and medium-term results. But more work is required to assess the long-term outcomes of modern implant designs.

Patellofemoral joint replacement, an evolving concept

Isolated patellofemoral arthritis is a rare disease, whose management is challenging and controversial. Patellofemoral joint replacement can be an effective treatment for this condition. The very concept of a patellofemoral implant has evolved throughout the years, resulting in more anatomic designs and reproducible surgical techniques. The clinical outcomes of this procedure are strictly related to surgical indications, implant design and appropriate surgical technique.

[Dislocation of the polyethylene in a patello-femoral replacement with a movable patella]

Patellofemoral arthroplasty is an infrequently used surgical technique because of its controversial results. In an attempt to improve the results, a design with a mobile-bearing poliethylene patellar component has been developed. We describe a clinical case with an unusual complication: the dislocation of poliethylene from the metal backing; and accordingly, we carried out a literature review of this complication.

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.

Patellofemoral arthroplasty: a systematic review of the literature

Identification and management of patients with isolated patellofemoral osteoarthritis are challenging. Many of these patients present at a young age and it is important to distinguish degenerative change in the patellofemoral articulation from the other various causes of anterior knee pain. Once the diagnosis of isolated patellofemoral arthrosis has been made non-operative and conservative surgical techniques should be exhausted fully before prosthetic arthroplasty is considered. This review focuses on the use of arthroplasty for isolated patellofemoral arthrosis, in particular comparing the use of total knee against selective patellofemoral joint replacements.

Patellofemoral arthroplasty, where are we today?

PURPOSE

Patellofemoral arthroplasty remains controversial, primarily due to the high failure rates reported with early implants. Numerous case series have been published over the years detailing results of various first- and second-generation implants. The purpose of this work is to summarize results published to date and identify common themes regarding implants, surgical techniques, and indications in order to maximize results of future procedures.

METHODS

A comprehensive review of the MEDLINE database was carried out to identify all clinical studies related to patellofemoral arthroplasty.

RESULTS

First-generation resurfacing implants were associated with relatively high failure rates in the medium term. Second-generation implants, with femoral cuts based on TKA designs have yielded more promising medium-term results. Surgical indications are specific and must be carefully followed to minimize poor results. Short-term complications are generally related to patellar maltracking, while long-term complications are generally related to progression of osteoarthritis in the tibiofemoral joint. Implant loosening and polyethylene wear are rarely reported. Short-term results are favourable for new technology including custom implants and computer navigated surgery.

CONCLUSIONS

Overall, recent improvements in implant design and surgical techniques have resulted in improvements in short- and medium-term results. More work is required to assess the long-term outcomes of modern implant designs.

LEVEL OF EVIDENCE

IV.

Patellofemoral arthroplasty: 7-year mean follow-up

Patellofemoral arthroplasty has had renewed interest with the purpose of this study to evaluate its outcomes. Between 2001 and 2006, 43 were performed in 37 patients who had a mean follow-up of 7 years (range, 4-8 years). Patient outcomes were determined using Knee Society objective and function scores, revision rates, and complication rates. The 5-year Kaplan-Meier survivorship was 95%. Knee Society objective scores improved from a mean of 64 points (range, 57-68 points) to 87 points (range, 50-100 points), and functional scores improved from a mean of 48 points (range, 45-50 points) to 82 points (range, 20-100 points). This study shows maintained successful clinical and radiographic results at mean 7-year follow-up for patellofemoral arthroplasty.

The patellar thinning osteotomy in patellofemoral arthritis: four to 18 years' follow-up

Isolated patellofemoral osteoarthritis can be a disabling disease. When conservative treatment fails, surgical options can be unpredictable and may be considered too aggressive for middle-aged and active people. We analysed the clinical and radiological results of a new coronal osteotomy involving thinning of the patella in a selected group of patients with isolated patellofemoral osteoarthritis. Since 1991, 31 patients (35 knees) have been treated, of whom 34 were available for follow-up at a mean of 9.1 years. The Knee Society Score, the Patellar score and the Short-form-36 questionnaire were used for clinical evaluation. We also examined the radiological features to confirm bone consolidation and assess the progression of osteoarthritis. A significant improvement in the functional scores and radiological parameters was noted. All patients except one were satisfied with the operation. Radiological progression of the patellofemoral osteoarthritis was slowed but radiological femorotibial osteoarthritis progressed in 23 (65%) cases, with a total knee replacement becoming necessary in four cases without technical problems in resurfacing the patella. We compared the results with other forms of surgical treatment reported in the literature. This treatment offers good clinical and radiological results, presenting an alternative method of managing patellofemoral osteoarthritis.

Unusual mechanical complications of unicompartmental low contact stress mobile bearing patellofemoral arthroplasty: a cause for concern?

The Low Contact Stress Patellofemoral Arthroplasty (LCS PFA) is a newer design belonging to the second generation of inlay type implants, addressing the problems encountered in the first generation models (Lubinus & Richard's). The cemented mobile bearing metal backed patellar component in this system is "modular"; allowing interchangeable usage with either the trochlear component in a PFA or the femoral component of a total knee arthroplasty, thus obviating the need for patellar revision during conversion of PFA to TKA. The younger active patient with a PFA may exert extreme joint reaction forces on their patellar implant, rendering early loosening of the patellar implant. The endurance of this implant with repeated flexion beyond 90 degrees is also a concern. We describe a series of three unusual mechanical failures associated with this particular design of metal backed patellar component of the unicompartmental LCS patellofemoral arthroplasty.

Patellofemoral arthroplasty

Isolated patellofemoral arthritis can occur in as many as 9% of patients older than 40 years and is particularly common in women, who often have subtle patellofemoral maltracking or malalignment. In fact, 24% of women with symptomatic knee arthritis have localized patellofemoral arthritis. Arthroplasty options can provide predictable pain relief, whereas other surgical measures for refractory patellofemoral arthritis--arthroscopic debridement, cartilage grafting, patellectomy, tibial tubercle unloading procedures--often have unsatisfactory results. While total knee arthroplasty (TKA) yields excellent results in >90% of patients with isolated patellofemoral arthritis, it is not desirable in patients who are young and active. Therefore, patellofemoral arthroplasty has a legitimate role in the treatment of isolated anterior compartment arthritis. Early patellofemoral implants were plagued by a high incidence of patellar maltracking, catching and subluxation, due to design features of the trochlear components, inadequate soft tissue balancing, and component malposition. Most importantly, contemporary onlay style trochlear components, implanted perpendicular to the anteroposterior axis of the femur, have substantially reduced the patellar maltracking that was so prevalent with inlay style prostheses for 3 decades. With onlay trochlear designs, early patella instability problems have been reduced, leaving late tibiofemoral degeneration as the primary cause of failure of patellofemoral arthroplasties. Several long-term studies have shown a rate of tibiofemoral degeneration of approximately 20% at 15 years. Finally, the results of TKA do not seem to be compromised by the presence of a prior patellofemoral arthroplasty.

Isolated patellofemoral osteoarthritis

BACKGROUND AND PURPOSE

The optimal treatment for isolated patellofemoral osteoarthritis is unclear at present. We systematically reviewed the highest level of available evidence on the nonoperative and operative treatment of isolated patellofemoral osteoarthritis to develop an evidenced-based discussion of treatment options.

METHODS

A systematic computerized database search (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), and EMBASE) was performed in March 2009. The quality of the studies was assessed independently by two authors using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We extracted data from 44 articles. The best available evidence for treatment of isolated patellofemoral osteoarthritis is sparse and of generally low methodological quality. Nonoperative treatment using physiotherapy (GRADE: high quality, weak recommendation for use), taping (GRADE: moderate quality, weak recommendation for use), or injection therapy (GRADE: very low quality, weak recommendation for use) may result in short-term relief. Joint-preserving surgical treatment may result in insufficient, unpredictable, or only short-term improvement (GRADE: low quality, weak recommendation against use). Total knee replacement with patellar resurfacing results in predictable and good, durable results (GRADE: low quality, weak recommendation for use). Outcome after patellofemoral arthroplasty in selected patients is good to excellent (GRADE: low quality, weak recommendation for use).

INTERPRETATION

Methodologically good quality comparative studies, preferably using a patient-relevant outcome instrument, are needed to establish the optimal treatment strategy for patients with isolated patellofemoral osteoarthritis.

Scientific evidence for the use of modern patellofemoral arthroplasty

Patellofemoral arthroplasty has been utilized as a treatment for isolated patellofemoral arthritis for more than 30 years. However, the use of this procedure remains controversial, as many surgeons prefer to use total knee arthroplasty, even for isolated patellofemoral arthritis. While historically, the results with this procedure have been inconsistent, recent developments in prosthesis design and surgical indications have improved the outcomes of patellofemoral arthroplasty. Potential advantages of patellofemoral arthroplasty include a less invasive approach, less bone resection, less tissue destruction, shorter operative time, less blood loss, shorter rehabilitation, and more normal knee kinematics. However, proper indications and surgical technique are crucial in order to obtain optimal results. Some future modifications have the potential to further improve the outcomes of the procedure, although additional investigations are needed to further explore some of these aspects. This report will describe current knowledge regarding the indications and contraindications for patellofemoral arthroplasty, present the results and complications of this procedure, discuss alternative treatments for patellofemoral disease, and explore future directions for arthroplasty of the patellofemoral compartment.

Midterm clinical results of the Autocentric II patellofemoral prosthesis

We studied the outcome of patellofemoral arthroplasties using the Autocentric prosthesis implanted in our clinic between 1994 and 2004. New insight on indications and contraindications motivated us to find risk factors in the failure of this prosthesis. Twenty-four patients had surgery for patellofemoral arthritis not responding to exhaustive nonoperative measures. The mean age at the time of patellofemoral arthroplasty (PFA) was 63.4 (SD 11.3, range 38-81) years with a mean follow-up of 4.8 (SD 2.9, range 2-11) years. Additional interventions were necessary in 21 knees during follow-up in our population, and seven knees required total knee arthroplasty (TKA) mainly due to progressive tibiofemoral osteoarthritis and maltracking of the patella. The patient outcomes and quality of life scores showed disappointing results, even after revision to TKA. This retrospective analysis underlines the importance of strict indications for patellofemoral arthroplasty and, in particular, of contraindications.

Patellofemoral arthroplasty: a multi-centre study with minimum 2-year follow-up

Recently, patellofemoral arthroplasty has attracted increased interest as a salvage treatment for isolated patellofemoral arthritis. However, there are very few reports of the experience with modern generation patellofemoral arthroplasties. This investigation describes a collective experience of four centres reporting on the outcome in patients of the use of one patellofemoral arthroplasty device. There were 70 patients (79 knees) who had failed an extensive non-operative treatment regimen and/or various conventional alternative surgical treatments. At a mean follow-up of three years (range: 2-6 years), there were 66 knees that had Knee Society Scores greater than 80 points (84%). Seventy-one knees (90%) functioned without pain in daily activity and stair climbing. Symptomatic isolated patellofemoral arthritis was successfully treated with a patellofemoral arthroplasty in the short term. We are encouraged by these excellent early results and await longer follow-up.

Optimizing patellofemoral arthroplasty

Patellofemoral arthroplasty (PFA) has been an option for patients with symptomatic patellofemoral osteoarthritis since the 1950's. Many of the early failures resulted from a combination of implant design and surgeon technique. The goal of this overview is not to review the history of PFA, but rather to explore options for surgeons to optimize long-term outcomes and improve patient knee function, while highlighting the differing techniques required in PFA with those routinely adopted in total knee arthroplasty (TKA).

Patellofemoral arthroplasty with a customized trochlear prosthesis

Successful patellofemoral arthroplasty depends on appropriate patient selection, proper prosthesis design, and correct surgical technique. Clinical results using off-the-shelf patellofemoral prostheses have reported mixed results primarily because of an inability to address these important characteristics adequately. This article reviews the design rationale, excellent clinical history, and straightforward surgical technique of a unique approach to patellofemoral arthroplasty that incorporates a customized trochlear prosthesis designed to fit the individual patient's patellofemoral groove. Clinical results using this customized approach demonstrate that it is a safe and effective treatment option for patients who have isolated patellofemoral arthritis.

Focal anatomic patellofemoral inlay resurfacing: theoretic basis, surgical technique, and case reports

Prosthetic patellofemoral inlay resurfacing is a novel treatment concept for degenerative and focal arthrosis of the patellofemoral joint. The theoretic basis of this type of arthroplasty entails recreating ambient anatomy based upon intraoperative topographic mapping. The implant is intrinsically stable by virtue of the inset position relative to the surrounding joint surface. Articular resurfacing, rather than traditional replacement arthroplasty, represents an extension of the concepts of biologic joint restoration. Early results have shown great efficacy. This surgery may be appropriate for a wide variety of indications, including younger patients and those with focal patellofemoral disease concurrent with morphologic or alignment abnormalities.

Patellofemoral arthroplasty in the treatment of patellofemoral arthritis: rationale and outcomes in younger patients

Patellofemoral degenerative disease encompasses a spectrum of articular wear from severe chondrosis to advanced arthrosis. The rationale and timing for many operative approaches currently advocated for the relief of symptomatic patellofemoral degeneration can be the subject of intense surgical debate in any one patient. Unfortunately, the limited efficacy of many commonly advocated operative procedures has left a legacy of patellofemoral disability in many younger individuals. While total knee arthroplasty has an established role in the treatment of advanced patellofemoral arthritis in the older patient (age >60 years), the performance of what some have called "a knee joint amputation" in younger patients (age <45 years) remains controversial and less acceptable to patients. The Avon patellofemoral prosthesis is a second-generation knee joint-conserving device that has consistently achieved good to excellent results in both the primary treatment and salvage of patellofemoral degenerative disease in younger patients. In addition, patellofemoral arthroplasty has demonstrated success as a unique functional, tibial-femoral joint-conserving solution in a variety of other patellofemoral extensor mechanism problems.

Results of total knee replacement for isolated patellofemoral arthritis: when not to perform a patellofemoral arthroplasty

Many procedures have been used to treat advanced isolated patellofemoral arthritis, with varying results. Patellofemoral arthroplasty (PFA) is a bone-conserving procedure that has shown short-term success but has relatively high revision rates. Total knee arthroplasty (TKA) has been recommended for treatment of this disease in patients who are older than 60 years of age. Recent literature indicates that PFA is most successful in patients who have isolated patellofemoral arthritis secondary to trochlear dysplasia or patellar fracture and in patients who are younger than 60 years; TKA is recommended for older patients who have primary or idiopathic isolated patellofemoral arthritis.