Total knee arthroplasty in patients with isolated patellofemoral arthritis

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.

Arthroscopic Lateral Patellar Facetectomy and Lateral Release Can Be Recommended for Isolated Patellofemoral Osteoarthritis

PURPOSE

To analyze the clinical outcomes and survival curve of arthroscopic lateral patellar facetectomy and lateral release for isolated patellofemoral osteoarthritis (PFOA).

METHODS

All patients undergoing arthroscopic lateral patellar facetectomy and lateral release between January 2008 and January 2018 were evaluated retrospectively. The inclusion criteria were 1) diagnosis of isolated symptomatic lateral PFOA, 2) PFOA with kissing lesions (defined as a lesion on both the patella and trochlea, which were in direct contact, 3) arthroscopic lateral patellar facetectomy and lateral release, and 4) two-year minimum follow-up. Evaluation included preoperative and postoperative subjective International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS) scores, and visual analogue pain scale (VAS). The primary end point determining the survival curve was revision of lateral facetectomy.

RESULTS

A retrospective analysis was conducted of 61 consecutive arthroscopic lateral patellar facetectomy and lateral release procedures, performed in 55 patients for a diagnosis of isolated PFOA. Five patients were lost to follow-up, leaving 56 knees (50 patients) available at a mean follow up of 7.5 years (range: 2-10). The cohort included 37 women and 13 men with a mean age of 59 years (range: 34-87). Nine patients (18%) underwent revision surgery: six total knee replacements (TKR), two high tibial osteotomies, and one revision arthroscopic lateral patellar facetectomy. The mean time from arthroscopic facetectomy to TKR was 51 months (range: 10-114). The survival curve rate was 86% at 7.5 years. Both KOOS and IKDC scores improved significantly. These results are confirmed by an analysis of MCID. The mean VAS decreased from 6.98 ± 1.2 preoperatively to 2.06 ± 1.6 at the last follow-up (ΔCI95% = [-5.6; -4.4]; P = .0001).

CONCLUSION

Arthroscopic lateral patellar facetectomy and lateral release for isolated PFOA demonstrates sustained significant improvement in knee clinical outcome scores and pain with a low rate of complications and revision surgery at mid-term follow-up. This operation can be recommended in cases of symptomatic isolated PFOA.

LEVEL OF EVIDENCE

IV, case series.

Has the modern design of Attune total knee replacement improved outcome in patients with isolated patellofemoral arthritis?

INTRODUCTION AND AIM

Modern knee replacements aim to improve patient function in arthritis affecting different compartments of the knee. This study evaluates the Patient Reported Outcome Measure (PROM) and functional outcome of a modern total knee replacement (Attune, DePuy) in patients with isolated patellofemoral arthritis.

METHODS

A total of 50 consecutive patients with isolated unilateral patellofemoral arthritis having had Attune total knee replacements at a single institution between 2010 and 2016 were prospectively studied. Five patients who developed symptoms on the opposite side during the study and two patients lost to follow-up were excluded. One patient needed early revision for loosening, leaving a total of 42 patients to be followed up over a period of 4 years. The Oxford Knee score (OKS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) recorded pre-operatively and at follow-up was compared. A Functional assessment at around 8 months after operation was undertaken.

RESULTS

At average follow-up of 24 months the mean OKS score improved by 15 points and the KOOS score improved by 20 points. Final KOOS sub-score for Pain was 80, Symptom 80, and ADL 82, Sports & Recreation 32 and QOL 60. Functional assessment at mean 8 months showed that a significant number of patients were able to Kneel (50%); Sit cross legged (23%); sit on their heel (23%) and were able do a single leg dip test (86%).

CONCLUSION

This unique study of a modern design total knee replacement (Attune) in patients with isolated unilateral patellofemoral arthritis shows good PROM scores at 2 years and good functional assessment results at 8 months. The PROM scores are marginally better than the published results with Attune's predecessor, in a similar cohort of patients, but falls short of the published results of patellofemoral replacement implants. Large randomised comparative studies between traditional and the modern implant design is recommended to answer the question if design modification has influenced clinical outcome in patients with patellofemoral arthritis.

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.

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.

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.

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.

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 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 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.

Survivorship and functional outcomes of patellofemoral arthroplasty: a systematic review

PURPOSE

Historically poor results of survivorship and functional outcomes of patellofemoral arthroplasty (PFA) have been reported in the setting of isolated patellofemoral osteoarthritis. More recently, however, fairly good results of PFA were reported, but the current status of PFA outcomes is unknown. Therefore, a systematic review was performed to assess overall PFA survivorship and functional outcomes.

METHODS

A search was performed using PubMed, Embase and Cochrane systems, and the registries were searched. Twenty-three cohort studies and one registry reported survivorship using Kaplan-Meier curve, while 51 cohort studies reported functional outcomes of PFA.

RESULTS

Twelve studies were level II studies, while 45 studies were level III or IV studies. Heterogeneity was mainly seen in type of prosthesis and year the cohort started. Nine hundred revisions in 9619 PFAs were reported yielding 5-, 10-, 15- and 20-year PFA survivorships of 91.7, 83.3, 74.9 and 66.6 %, respectively, and an annual revision rate of 2.18. Functional outcomes were reported in 2587 PFAs with an overall score of 82.2 % of the maximum score. KSS and Knee Function Score were 87.5 and 81.6 %, respectively.

CONCLUSION

This systematic review showed that fairly good results of PFA survivorship and functional outcomes were reported at short- and midterm follow-up in the setting of isolated patellofemoral osteoarthritis. Heterogeneity existed mainly in prosthesis design and year the cohort started.

CLINICAL RELEVANCE

These results provide a clear overview of the current status of PFA in the setting of isolated patellofemoral osteoarthritis.

LEVEL OF EVIDENCE

IV.

Why do patellofemoral arthroplasties fail today? A systematic review

BACKGROUND

Historically poor results of patellofemoral arthroplasty (PFA) were reported in the setting of isolated patellofemoral osteoarthritis (OA). In order to lower PFA failure rates, it is important to identify failure modes using a standardized method. In this systematic review, PFA failure modes were assessed and compared in early vs. late failures and older vs. recent studies.

METHODS

Databases of PubMed, Embase and Cochrane and annual registries were searched for studies reporting PFA failures. Failure modes in studies with mean follow-up <5years were classified as early failures while >5years were classified late failures. Cohorts started before 2000 were classified as older studies and started after 2000 as recent studies.

RESULTS

Thirty-nine cohort studies (10 level II and 29 level III or IV studies) and three registries were included with overall low quality of studies (GRADE criteria). A total of 938 PFA failures were included and were caused by OA progression (38%), pain (16%), aseptic loosening (14%) and patellar maltracking (10%). Pain was responsible for most early failures (31%), while OA progression was most common in late failures (46%). In older studies, OA progression was more commonly reported as failure mode than in more recent studies (53% vs. 39%, p=0.005).

CONCLUSION

This level IV systematic review with low quality of studies identified OA progression and pain as major failure modes. Reviewing these studies, appropriate patient selection could prevent PFA failures in select cases. Future studies assessing the role of PFA in isolated patellofemoral OA are necessary.

Patellofemoral Joint Arthroplasty: Our Experience in Isolated Patellofemoral and Bicompartmental Arthritic Knees

INTRODUCTION

Isolated patellofemoral (PF) arthritis is rare, and there is no complete agreement about the best surgical treatment. The operative treatments are total knee arthroplasty and patellofemoral replacement (PFR). The incidence of many early complications of PF arthroplasty has decreased with the introduction of newer designs. Nowadays, the main cause of revision surgery is the progression of tibiofemoral osteoarthritis. In the past, PF arthroplasty was contraindicated in patients with evidence of osteoarthritis or pain in medial or lateral tibiofemoral compartments. The improvement in implant designs and surgical techniques has allowed the addition of a monocompartmental arthroplasty for the medial or lateral tibiofemoral compartment. In this work, we evaluate our first experience with PF arthroplasty and its combination with unicompartmental knee arthroplasty.

MATERIALS AND METHODS

From May 2014 to March 2016, we treated 14 patients. An isolated PF arthroplasty was performed in six knees (five patients), and a combined PF and unicompartmental knee arthroplasty was performed in nine cases. We observed a significant improvement in the clinical and functional Knee Society Scores (KSSs) after surgery in our patients.

RESULTS

We obtained good results in our cases both for clinical and functional KSSs. Patellar clunk was recorded in one case.

DISCUSSION AND CONCLUSION

We are going toward a new attitude in which partial osteoarthritic changes could be treated with partial resurfacing prosthetic solutions such as unicompartmental, bi–unicompartmental or PFR alone, or unicompartmental combined, which respects the cruciates and achieves maximal bone preservation, which is vital, particularly, for young patients.

Proposal of a therapeutic protocol for selected patients with patellofemoral knee osteoarthritis: arthroscopic lateral retinacular release followed by viscosupplementation

BACKGROUND

Lateral retinacular release has been demonstrated to reduce articular patellofemoral pressures, while intra-articular injection of hyaluronic acid can improve the biological and rheological knee pathway. We evaluated whether treatment protocol consisting on combination of these two therapies can provide significant symptomatic improvement in patients with patellofemoral osteoarthritis (PFO) and patellar tilt.

MATERIALS AND METHODS

We retrospectively analyzed the clinical and radiological data of 28 knees (25 patients with anterior knee pain) who underwent arthroscopic lateral retinacular release followed by viscosupplementation for isolated patellofemoral osteoarthritis without clinical or radiological signs of patellar instability. Clinical evaluation was performed at a mean follow-up of 32.4 months (range 24-47 months) by an independent surgeon using the Kujala score, visual analog scale (VAS), and patient satisfaction scale. Univariate and multivariate analysis was used to identify best determinants to have a good clinical outcome.

RESULTS

Mean Kujala score improved from 45.8 points before surgery (range 33-65 points) to 82.7 points after treatment protocol (range 52-100 points). VAS improved of 68.5 % from preoperative and all patients except one were satisfied. Linear multiple regression modeling showed that younger age (OR 1.134, 95 % CI 1.018-1.263, p = 0.022) and short time delay between the onset of symptoms and treatment (OR 1.207, 95 % CI 0.982-1.484, p = 0.007) were the best determinants for a good final outcome.

CONCLUSIONS

Arthroscopic lateral retinacular release followed by viscosupplementation is an effective treatment protocol for PFO, simple and minimally invasive with respect to other therapeutic options.

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.

Osteochondral Allograft Transplantation of the Femoral Trochlea

BACKGROUND

Osteochondral allograft (OCA) transplantation is a recognized treatment modality for cartilage damage in the knee. Few reports are available on outcomes of OCA in the patellofemoral joint, and there are no reports on lesions isolated to the femoral trochlea.

PURPOSE

To evaluate graft survivorship and clinical outcomes in patients who had an OCA to the femoral trochlea.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

An OCA database was used to identify 29 knees in 28 patients (mean age, 30.2 years; range, 12-47 years; 8 female, 20 male) who were treated with a fresh OCA transplant limited to the femoral trochlea. The primary outcome was graft survivorship, and the minimum follow-up was 2 years. Clinical outcomes were assessed by the modified Merle d'Aubigné-Postel (18-point) score; Knee Society function (KS-F) score; International Knee Documentation Committee (IKDC) pain, function, and total scores; and University of California, Los Angeles (UCLA) activity score. The OCA patient satisfaction score (5-point scale from extremely satisfied to dissatisfied) was also reported.

RESULTS

The mean follow-up period was 7.0 years (range, 2.1-19.9 years). Graft survivorship was 100% at 5 years and 91.7% at 10 years. One patient was converted to a total knee arthroplasty 7.6 years after OCA surgery. The mean modified Merle d'Aubigné-Postel score improved from 13.0 to 16.1, the mean KS-F score from 65.6 to 85.2, and the mean IKDC total score from 38.5 to 71.9; the mean UCLA score was 7.9 postoperatively. Eighty-nine percent of patients were extremely satisfied or satisfied with the outcome of surgery.

CONCLUSION

Fresh OCA transplantation resulted in excellent clinical outcomes in this patient cohort with articular cartilage damage to the femoral trochlea. The procedure resulted in improved pain and function and high patient satisfaction.

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.

[Patellofemoral arthroplasty: indication, technique and results]

BACKGROUND

Although patellofemoral arthroplasty has been used for more than 30 years, it is still a challenging subject in orthopedics. The reason for this are the complex kinematics of the patellofemoral joint which are influenced by dynamic and static factors. New implant concepts that incorporate multiple coronal and sagittal curvatures and surface controlled inlay implantation show a positive direction in modern patellofemoral arthroplasty.

OBJECTIVES

The purpose of this work is the review of the literature on patellofemoral arthroplasty and the presentation of our own experience.

METHODS

We present indications and surgical techniques of patellofemoral arthroplasty as well as the most important aspects of preoperative evaluation. The patellofemoral joint can be reconstructed using either an inlay or an onlay prosthesis. Both arthroplasty concepts are discussed. Additional pathologies like chronic patellofemoral instabilities due to dysplasia, valgus/varus or rotational malalignment, and soft-tissue alterations are addressed with concomitant procedures.

RESULTS

Both inlay and onlay arthroplasty have demonstrated good functional outcome scores in patients with patellofemoral osteoarthritis. Patients with patellofemoral instability and/or trochlear dysplasia may benefit more from patellofemoral arthroplasty than patients with primary osteoarthritis because not only pain but also secondary pathologies are addressed.

CONCLUSION

Patellofemoral arthroplasty is an effective and safe procedure if the indication criteria are respected and the specific surgical technique is used. However, comparative results on current inlay and onlay prostheses have not been published in the literature to date.

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.

Are results of total knee arthroplasty for isolated patellofemoral OA as good as for medial compartment OA? A medium-term retrospective comparative study

PURPOSE

The aim of this study was to compare the results of isolated patellofemoral arthritis (IPFA) treated using a total knee arthroplasty (TKA) compared to the results of medial tibiofemoral arthritis treated with a TKA. We hypothesised that there would be no difference between functional outcomes for the two groups.

METHODS

Between 2003 and 2009, 32 TKAs were performed for IPFA (group I). Over this time period, a total of 813 primary TKAs were performed from which we identified a second group of patients who had undergone TKA for isolated medial tibiofemoral arthritis (group II: n = 32). These patients were matched based on age, sex, body mass index and average follow-up. The average age of patients in group I was 72.81 ± 6.6 years (59-83) and 71.97 ± 6.8 years in group II. The global International Knee Society (IKS) score was statistically significantly better in group I (114.72 ± 22 points) than in group II (84.9 ± 23.8). This difference was accounted for by better passive flexion, better walking distance and the absence of any coronal plane deformity.

RESULTS

A total of 29 patients from group I were reviewed at an average follow-up of 64.58 ± 23.4 months, and 30 patients in group II were reviewed at an average follow-up of 66.13 ± 23.9 months (three were lost to follow-up in group I and two in group II). At final follow-up, there was statistically no difference between the two groups IKS score (175.34 ± 19.26 in group I vs. 170.13 ± 24.14 for group II) or Hospital for Special Surgery patella score (89.31 ± 9.98 points for group I vs. 89.16 ± 11.45 points for group II). We found no significant radiological difference between the two groups including patella height and orientation on axial views.

CONCLUSIONS

The results of TKA for IPFA are as good as the results of TKA for isolated medial tibiofemoral arthritis with well-functioning prosthetic patellofemoral articulations. These results support our institutional preference for using TKA as treatment for IPFA in patients over 65-70 years old.

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.

Partial lateral facetectomy plus Insall's procedure for the treatment of isolated patellofemoral osteoarthritis: survival analysis

PURPOSE

The purpose of this study was to report the survival analysis of partial lateral facetectomy and Insall's procedure in patients with isolated patellofemoral osteoarthritis, and to assess the risk and protective factors for failure of this procedure.

METHODS

From 1992 to 2004, all subjects with isolated patellofemoral osteoarthritis who met the inclusion criteria and underwent this procedure were enrolled. Risk and protective factors for failure (failure considered as the need for total knee arthroplasty) were assessed by comparing obtained baseline data between failed and non-failed cases. Eighty-seven cases (mean (SD) age 61.8 (7.7) years, mean (SD) follow-up 9.6 (3.2) years) were included.

RESULTS

Twenty-three failed cases were found. Mean (SD) survival time was 13.6 (0.5) years. At 13 years (last failure case), the cumulative survival was 59.3 %. Baseline medial tibiofemoral pain, genu flexum, and worst grade of tibiofemoral osteoarthritis were significant risk factors for failure (p < 0.0001, p = 0.02, p < 0.0001, respectively). In contrast, higher anatomical (p = 0.02) and total (p = 0.03) knee society score (KSS) scores, absence of knee effusion (p = 0.03), higher value of the Caton-Deschamps index (p = 0.03), and lateral position of the patella (p = 0.01) were all protective factors against failure.

CONCLUSION

The treatment for isolated patellofemoral osteoarthritis through partial lateral facetectomy and Insall's procedure demonstrated good long-term survival. The presence of preoperative medial tibiofemoral pain, genu flexum, and incipient tibiofemoral osteoarthritis increased the risk of failure of this procedure. In contrast, higher anatomical and total KSS scores, absence of knee effusion, higher value of the Caton-Deschamps index, and lateral position of the patella were found to protect against failure.

Patellofemoral replacement

Isolated patellofemoral arthritis is a common condition and there are varying opinions on the most effective treatments. Non-operative and operative treatments have failed to demonstrate effective long-term treatment for those in an advanced stage of the condition. Newer designs and increased technology in patellofemoral replacement (PFR) have produced more consistent outcomes. This has led to a renewed enthusiasm for this procedure. Newer PFR prostheses have addressed the patellar maltracking issues plaguing some of the older designs. Short-term results with contemporary prostheses and new technology are described here.

Cite this article: Bone Joint J 2013;95-B, Supple A:124–8.

Clinical results of patellofemoral arthroplasty

Isolated patellofemoral arthritis can be a disabling condition that can be challenging to treat. Patients with symptoms recalcitrant to conservative measures are considered for total or partial knee arthroplasty. This retrospective study reports the results of patellofemoral arthroplasty at a single center using a variety of implant designs. Thirty patients (37 knees) with isolated patellofemoral disease treated with patellofemoral arthroplasty with a minimum of one year follow-up were evaluated. The majority of patients were female (83%) and the underlying diagnosis was osteoarthritis in 98% of knees. Reported follow-up averaged 31 months. Average Knee Society Pain, Functional, and Clinical Scores improved from pre-op to most recent follow-up. Two complications (5.4%) required intervention. One patient was converted to a total knee arthroplasty secondary to patella instability.

Early revisions of the Femoro-Patella Vialla joint replacement

The aim of this study was to review the early outcome of the Femoro-Patella Vialla (FPV) joint replacement. A total of 48 consecutive FPVs were implanted between December 2007 and June 2011. Case-note analysis was performed to evaluate the indications, operative histology, operative findings, post-operative complications and reasons for revision. The mean age of the patients was 63.3 years (48.2 to 81.0) and the mean follow-up was 25.0 months (6.1 to 48.9). Revision was performed in seven (14.6%) at a mean of 21.7 months, and there was one re-revision. Persistent pain was observed in three further patients who remain unrevised. The reasons for revision were pain due to progressive tibiofemoral disease in five, inflammatory arthritis in one, and patellar fracture following trauma in one. No failures were related to the implant or the technique. Trochlear dysplasia was associated with a significantly lower rate of revision (5.9% vs 35.7%, p = 0.017) and a lower incidence of revision or persistent pain (11.8% vs 42.9%, p = 0.045). Focal patellofemoral osteoarthritis secondary to trochlear dysplasia should be considered the best indication for patellofemoral replacement. Standardised radiological imaging, with MRI to exclude overt tibiofemoral disease should be part of the pre-operative assessment, especially for the non-dysplastic knee.

The clinical outcome of patellofemoral arthroplasty

Patellofemoral arthroplasty has a long record of use in the treatment of isolated patellofemoral arthritis, with outcomes influenced by patient selection, surgical technique, and trochlear implant design. The trochlear components have evolved from inlay-style to onlay-style designs, which have reduced the incidence of patellar instability. Minimizing the risk of patellar instability with onlay-design patellofemoral arthroplasties has enhanced mid-term and long-term results and leaves progressive tibiofemoral arthritis as the primary failure mechanism beyond 10 to 15 years.

Blood loss and transfusion rates following patellofemoral arthroplasty

Patellofemoral arthroplasty (PFA) is a viable treatment option of the patient with isolated patellofemoral arthritis. Some of the purported advantages of PFA compared with total knee arthroplasty (TKA) include less invasive approach, less bone resection and tissue destruction, decreased operative time, shorter rehabilitation, better knee kinematics, and decreased blood loss. This study compared the blood loss associated with PFA with that of a cohort of patients with TKA. A proposed benefit of partial knee arthroplasty is less blood loss. Patellofemoral replacement seems not to have this benefit and blood loss prevention initiatives similar to those of TKA should be maintained.

Complications after patello-femoral versus total knee replacement in the treatment of isolated patello-femoral osteoarthritis. A meta-analysis

PURPOSE

Both patellofemoral arthroplasty (PFA) and total knee arthroplasty (TKA) are successful in treating isolated patellofemoral osteoarthritis, but the complication rates after PFA are concerning. We performed a meta-analysis to compare the incidence of complications, re-operations, and revision following PFA and TKA for patellofemoral osteoarthritis.

METHODS

We systematically identified publications with patients who underwent PFA or TKA for patellofemoral osteoarthritis with minimum 1.5 year follow-up. Demographics, implant (TKA, first [1G] or second-generation [2G] PFA), complications, and cause of re-operations were extracted. Random-effects meta-analysis was used to pool incidence data, which was compared between groups using logistic regression to adjust for length of follow-up.

RESULTS

Twenty-eight observational studies and no randomized trials were included in this meta-analysis, which limits its generalizability. There was a higher likelihood of any re-operation (odds ratio 8.06) and revision (OR 8.11) in PFA compared to TKA. Re-operation (OR 4.33) and revision (OR 4.93) were more likely in 1G-PFA than 2G-PFA. When comparing 2G-PFA to TKA, there was no significant difference in re-operation, revision, pain, or mechanical complications.

CONCLUSIONS

Patients who undergo PFA rather than TKA are more likely to experience complications and require re-operation or revision, but subgroup analysis suggests a relation to implant design. There is no significant difference in re-operation, revision, pain, or mechanical complications between 2G-PFA and TKA.

LEVEL OF EVIDENCE

Systematic review of Level III therapeutic studies, Level III.

Patellofemoral osteoarthritis treated by partial lateral facetectomy: results at long-term follow up

Excision of the eroded lateral patellar facet has been suggested as an acceptable treatment for short-term pain reduction in patients with isolated patellofemoral osteoarthritis. The outcome of this procedure at long-term is however not known. We therefore reviewed the results of 155 consecutive patients (168 knees) treated at our institution with lateral facetectomy at an average follow up of 10.9 years (± 6.9 years SD). During follow up 62 knees (36.9%) had failed and were revised to either TKA (60 knees), patellofemoral arthroplasty (one case) or total patellectomy (one case). Average time to reoperation in the failure group was 8.0 years (± 6.2 years SD). Kaplan-Meier survival rates with reoperation as endpoint were 85% at 5 years, 67.2% at 10 years, and 46.7% at 20 years respectively. At final follow up 79 (74.5%) of the knees that had not been re-operated were rated as either good or fair, which corresponds to 47% of the original group. Our study therefore demonstrates that a satisfactory outcome after lateral patellar facetectomy for isolated patellofemoral osteoarthritis can be expected in approximately half of the cases at 10 year follow up.

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.

Medium term results of Avon patellofemoral joint replacement

BACKGROUND

Ten to fifteen percent of knee arthritis is reported to be isolated patellofemoral arthritis. Total knee arthroplasty is not recommended for isolated patella femoral arthritis particularly in young patients. We present the retrospective review of 45 consecutive patellofemoral replacements performed in 41 such patients, between June 2002 and January 2007.

MATERIALS AND METHODS

All patients were operated by single surgeon (SM) or under his supervision. All forty five patients had minimum three year followup and had the data collected prospectively. No patient was lost to followup. This data was later collated by review of notes, radiographs, and a clinical followup. The patients were assessed using knee function score and Melbourne patellofemoral score.

RESULTS

The average followup was 4.5 years. The preoperative average Melbourne (Bartlett) score was 10 (range 5-21). Preoperative knee functional score averaged 57 (range 23-95). The average range of movement was 116° (range 100°-140°). Postoperatively, the average Melbourne knee score improved to 25 (range 11-30), while the knee function score was 85 (range 28 - 100). The difference was statistically significant (P<0.05). Eighty-five percent rated the result as good or excellent, while 12% rated it as fair. Five percent thought the result was poor. The most common complaint was clicking at 40° of flexion (n=7). Six patients underwent arthroscopic lateral release, which improved the symptoms in four patients. Two knees were revised one due to progression of tibiofemoral arthritis and the other due to persistent clicking, yielding a survival rate of 95.6% at an average five year followup.

CONCLUSION

The Avon patellofemoral joint replacement provides predictably good results and excellent survivorship in the medium term, for isolated patellofemoral arthritis. However, progression of tibiofemoral arthritis remains unpredictable and therefore patient selection is crucial to ensure success. Clicking remains a potential problem and can compromise the postoperative results in upto 15% of the cases.

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.

Long-term outcomes of patellofemoral arthroplasty

The purpose of this study was to correlate the long-term survival of patellofemoral arthroplasty with primary diagnosis, age, sex, and body mass index. One hundred eighty-five consecutive Richards type II patellofemoral arthroplasties were performed in 161 patients with isolated patellofemoral osteoarthritis. Diagnoses included primary patellofemoral osteoarthritis, posttraumatic patellofemoral osteoarthritis, and patellofemoral osteoarthritis with a previous realignment procedure for patellar subluxation or trochlear dysplasia. Median time to follow-up was 13.3 (range, 2.0-30.6) years. Patellofemoral arthroplasty survival was 84% at 10 years and 69% at 20 years. Primary diagnosis, sex, or age at patellofemoral arthroplasty did not significantly affect the rate of revision (P=.35, P=.24, and P=.65, respectively). The rate of revision in obese patients (body mass index>30 kg/m2) was higher than that in nonobese patients (P=.02).

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.

Surgical options for patients with osteoarthritis of the knee

Osteoarthritis (OA) of the knee is a progressive disease that ultimately damages the entire joint. Knee OA should initially be treated conservatively, but surgery should be considered if symptoms persist. Surgical treatments for knee OA include arthroscopy, osteotomy and knee arthroplasty; determining which of these procedures is most appropriate will depend on several factors, including the location and severity of OA damage, patient characteristics and risk factors. Arthroscopic lavage and debridement do not alter disease progression, and should not be used as a routine treatment for the osteoarthritic knee. Bone marrow stimulation techniques such as microfracture are primarily used to treat focal chondral defects; the evidence for the use of these techniques for knee OA remains unclear. The goal of osteotomy for unicompartmental knee OA is to transfer the weight load from the damaged compartment to undamaged areas, delaying the need for joint replacement. This procedure should be considered in young and active patients who are not suitable candidates for knee arthroplasty. For patients with severe OA, total knee arthroplasty can be a safe, rewarding and cost-effective treatment. In selected patients with isolated medial or patellofemoral OA, unicompartmental knee arthroplasty and patellofemoral replacement, respectively, can be successful.

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).

[Isolated arthrosis of the patellofemoral joint in younger patients (<50 years)]

In the majority of cases, arthrosis of the patellofemoral joint (PFJ) is combined with arthrosis of the femorotibial compartment and thus assumes a somewhat secondary role. Nevertheless, it can occur as an isolated entity. Several radiological studies evidenced isolated degenerative alterations in the PFJ in the age group >55 years (13.6-24.0% in women and 11.0-15.4% in men). In younger patients the incidence is lower and is mainly associated with patellar instability or post-traumatic arthrosis. Just the same, the choice of appropriate treatment for these patients is challenging. Total replacement can be recommended for older and less active patients. In contrast, for younger and more active patients, various conservative treatment options and more demanding operative techniques are available to the surgeon to avoid arthroplasty. This article describes the different therapeutic possibilities for managing arthrosis of the PFJ in patients aged <50 years.