High mid-term revision rate after treatment of large, full-thickness cartilage lesions and OA in the patellofemoral joint using a large inlay resurfacing prosthesis: HemiCAP-Wave®

Return to Sports in Patients Aged 50 Years or Younger After Robotic-Assisted Patellofemoral Arthroplasty: A 10-Year Experience Reporting High Clinical Benefits and High Patient Satisfaction With Return to an Active Lifestyle

BACKGROUND

Limited data are available on return to sports and patient psychometric ratings of success after patellofemoral arthroplasty (PFA) in younger patients with high expectations to return to an active lifestyle.

PURPOSE/HYPOTHESIS

The purpose of this article was to determine the role of PFA and its success in meeting patient expectations regarding the return to low-impact recreational sports and an active lifestyle in younger, active patients. It was hypothesized that PFA would allow younger patients to return to low-impact sports and an active lifestyle and achieve high patient psychometric ratings.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

In this 10-year prospective study (2009-2018), robotic-assisted PFA was performed on 44 patients (32 women and 12 men; n = 51 consecutive knees), with a mean age of 37.2 years (range, 21-50 years). The follow-up rate was 98%, with a mean of 5.3 years (range, 2-9.3 years). Primary clinical outcomes were as follows: the validated Cincinnati Knee Rating System sports activity and symptom rating scales, patient psychometric ratings of the substantial clinical benefit (SCB), and the Patient Acceptable Symptom State (PASS). Secondary outcomes were the Cincinnati Knee Rating System occupational rating, visual analog pain scale, and the 12-Item Short Form Health Survey. Survivorship was defined by conversion to total knee replacement (TKR).

RESULTS

Before PFA, 78% of patients (35/45 knees) were symptomatic and unable to perform recreational sports, with only 20% of patients (9/45 knees) performing some low-impact sports. After PFA, 80% of patients (36/45 knees) were able to perform low-impact sports, and 7% (3/45 knees) performed jumping-pivoting sports (P < .001). The SCB scored by the patient showed 87% of knees as good, very good, or normal. On the PASS analysis, 89% of patients (95% CI, 76%-96%) were "pleased," and 93% (95% CI, 82%-99%) would undergo surgery again. There were clinically relevant improvements in symptoms of pain, swelling, and giving way (P = .0001). Preoperatively, 91% of knees had moderate to severe pain with activities of daily living, and only 11% of knees had pain at the follow-up. Five of the 50 knees (10%) underwent TKR conversion with one patient lost to follow-up.

CONCLUSION

PFA resulted in a high return of patients to low-impact sports with high SCB and PASS psychometric ratings. The robotic-assisted 3-dimensional preoperative planning allowed precise intraoperative trochlear implant alignment in knees with severe trochlear dysplasia. PFA is recommended as an alternative treatment in younger patients with end-stage symptomatic patellofemoral arthritis.

REGISTRATION

NCT02738476 (ClinicalTrials.gov identifier).

Clinical outcomes of patellofemoral arthroplasty: robotic assistance produces superior short and mid-term outcomes

INTRODUCTION

Patellofemoral arthroplasty (PFA) has been shown to provide symptomatic improvement for isolated patellofemoral osteoarthritis (PFOA). The efficacy of robotic-assisted PFA and the most suitable PFA implant design, however, remain ongoing matters of debate. This study sought to compare clinical outcomes between patients who underwent robotic-assisted versus conventional PFAs with inlay and onlay prosthetic designs.

METHODS

A single-center retrospective review found 237 knees (211 patients) which underwent PFA between 2011 and 2021. One hundred eighty-four knees were included in the final analysis after cases were excluded for having indications other than osteoarthritis or having less than one year of follow-up. There were 90 conventional PFAs and 94 robotic-assisted PFAs performed. Inlay components were implanted in 89 knees and onlay components were implanted in 95 knees. Propensity score matching was utilized to address demographic differences between groups.

RESULTS

Overall, there was a revision-free survivorship rate of 89.7% with an average time to follow-up of 4.6 years (range 1.2 to 11.1). Twenty-nine knees (15.8%) required various non-conversion procedures. The conventional matched cohort exhibited a higher all-cause revision rate, accounting for revision PFAs and conversions to TKA, (18.8 vs. 6.4%, p = 0.014) and a shorter mean time to revision than the robotic-assisted cohort (3.1 vs. 5.8 years, p = 0.026). A Kaplan-Meier survivorship curve showed differences between the conventional and robotics cohorts (p = 0.041). All revisions following robotic-assisted PFA were caused by progression of osteoarthritis, whereas conventional PFAs also required revision due to aseptic loosening and patellar maltracking. The rate of infection resulting in irrigation and debridement was higher for conventional cases (4.3 vs. 0%, p = 0.041). No significant differences in clinical outcomes between the inlay and onlay prosthetic design matched cohorts were identified.

CONCLUSION

PFA is an effective treatment for addressing advanced patellofemoral arthritis. Robotic-assisted surgery may lead to improved clinical outcomes.

LEVEL OF EVIDENCE

III.

Revision of inlay resurfacing prosthesis with patellar realignment surgery and a new inlay prosthesis for persistent patellofemoral pain und patella subluxation

We present the case of a 35-year-old patient who underwent inlay patellofemoral arthroplasty (I-PFA) followed by secondary patellar realignment surgery and inlay-to-inlay revision. Revision was performed because of ongoing pain, crepitation, and lateral subluxation of the patella. The original patella component (30-mm button) was replaced with a 35-mm dome, while the Hemi-Cap Wave® (7 × 5 mm) I-PFA was replaced with the Hemi-Cap Kahuna® (10 × 5 mm). At the 1-year follow-up, the clinical symptoms were resolved. Radiography revealed an aligned patellofemoral compartment with no signs of loosening. Inlay-to-inlay PFA revision appears to be a reasonable alternative to total knee arthroplasty and conversion to onlay-PFA (O-PFA) for symptomatic patients with primary I-PFA failure. Thorough patellofemoral evaluation and appropriate patient and implant selection are key for successful I-PFA, while additional procedures for patellar realignment may also be required for satisfactory long-term outcomes.

Establishing the Minimal Clinically Important Difference and Patient Acceptable Symptomatic State following Patellofemoral Inlay Arthroplasty for Visual Analog Scale Pain, Western Ontario and McMaster Universities Arthritis Index, and Lysholm Scores

BACKGROUND

The purposes of the study were to define the minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) after patello-femoral inlay arthroplasty (PFA) and to identify factors predictive for the achievement of clinically important outcomes (CIOs).

METHODS

A total of 99 patients who underwent PFA between 2009 and 2019 and had a minimum of 2-year postoperative follow-up were enrolled in this retrospective monocentric study. Included patients had a mean age of 44 years (range, 21 to 79). The MCID and PASS were calculated using an anchor-based approach for the visual analog scale (VAS) pain, Western Ontario and McMaster Universities Arthritis Index (WOMAC), and Lysholm patient-reported outcome measures. Factors associated with CIO achievement were determined using multivariable logistic regression analyses.

RESULTS

The established MCID thresholds for clinical improvement were -2.46 for the VAS pain score, -8.5 for the WOMAC score, and + 25.4 for the Lysholm score. Postoperative scores corresponding to the PASS were <2.55 for the VAS pain score, <14.6 for the WOMAC score, and >52.5 points for the Lysholm score. Preoperative patellar instability and concomitant medial patello-femoral ligament reconstruction were independent positive predictors of reaching both MCID and PASS. Additionally, inferior baseline scores and age were predictive of achieving MCID, whereas superior baseline scores and body mass index were predictive of achieving PASS.

CONCLUSION

This study determined the thresholds of MCID and PASS for the VAS pain, WOMAC, and Lysholm scores following PFA implantation at 2-year follow-up. The study demonstrated a predictive role of patient age, body mass index, preoperative patient-reported outcome measure scores, preoperative patellar instability, and concomitant medial patello-femoral ligament reconstruction in the achievement of CIOs.

LEVEL OF EVIDENCE

Prognostic Level IV.

Patellofemoral arthroplasty with onlay prosthesis leads to higher rates of osteoarthritis progression than inlay design implants: a systematic review

PURPOSE

The aim of this study was to report the clinical and functional outcomes, complication rates, implant survivorship and the progression of tibiofemoral osteoarthritis (OA), after new inlay or onlay patellofemoral arthroplasty (PFA), for isolated patellofemoral OA. Comparison of different implant types and models, where it was possible, also represented one of the objectives.

METHODS

A systematic literature search following PRISMA guidelines was conducted on PubMed, Scopus, Embase and Cochrane databases, to identify possible relevant studies, published from the inception of these databases until 11.11.2022. Randomized control trials (RCTs), case series, case control studies and cohort studies, written in English or German, and published in peer-reviewed journals after 2010, were included. Not original studies, case reports, simulation studies, systematic reviews, or studies that included patients who underwent TKA or unicompartmental arthroplasty (UKA) of the medial or lateral compartment of the knee, were excluded. Additionally, only articles that assessed functional and/or clinical outcomes, patient-reported outcomes (PROMs), radiographic progression of OA, complication rates, implant survival rates, pain, as well as conversion to TKA rates in patients treated with PFA, using inlay or onlay trochlea designs, were included. For quality assessment, the Methodological Index for Non-Randomized Studies (MINORS) for non-comparative and comparative clinical intervention studies was used.

RESULTS

The literature search identified 404 articles. 29 of them met all the inclusion criteria following the selection process. Median MINORS for non-comparative studies value was 12.5 (range 11-14), and for comparative studies 20.1 (range 17-24). In terms of clinical and functional outcomes, no difference between onlay and inlay PFA has been described. Both designs yielded satisfactory results at short, medium and long-term follow-ups. Both designs improved pain postoperatively and no difference between them in terms of postoperative VAS has been noted, although the onlay groups presented a higher preoperative VAS. When comparing the inlay to onlay trochlea designs, the inlay group displayed a lower progression of OA rate.

CONCLUSION

There is no difference in functional or clinical outcomes after PFA between the new inlay and the onlay designs, with both presenting an improvement in most of the scores that were used. A higher rate of OA progression was observed in the onlay design group.

LEVEL OF EVIDENCE

III.

Outcomes and complications of inlay versus onlay patellofemoral arthroplasty: A systematic review

PURPOSE

The purpose of this systematic review was to evaluate outcomes and complications rates between inlay and onlay patellofemoral arthroplasty (PFA).

METHODS

According to the PRISMA statement, 42 studies with 2552 patients were included. Data considered for quantitative analysis consisted of the Knee Society Score (KSS), the range of motion (ROM), the visual analogue score (VAS), and the Western Ontario and McMaster Universities questionnaire (WOMAC). Complications and revision surgery were considered.

RESULTS

Data on postoperative KSS showed no differences between the groups. The ROM was evaluated in 8 studies for 70 and 331 inlay and onlay PFA, respectively. Onlay group was favorable in terms of postoperative ROM. Postoperative VAS was available for 64 inlay and 110 onlay and no differences were found. Data on postoperative WOMAC were available for 49 inlay and 527 onlay PFA and inlay group showed better scores. A statistically significant higher rate of instability, persistent pain, malposition, stiffness, deep infection, disease progression, and wear of the patellar component were noted in the inlay group. A higher rate of lateral release was noted in the onlay group. A higher number of manipulations under anesthesia was noted in the inlay group. The revision to total knee arthroplasty was reported more frequently in the inlay group.

CONCLUSION

A higher rate of conversion to total knee arthroplasty and complication rates after inlay technique was found. The potential of achieving better WOMAC scores with the inlay technique should be weighed against the higher complication and revision rates compared to the onlay technique.

LEVEL OF EVIDENCE

IV.

The lack of retropatellar resurfacing at index surgery is significantly associated with failure in patients following patellofemoral inlay arthroplasty: a multi-center study of more than 260 patients

PURPOSE

To evaluate the clinical outcomes of patients with a minimum 2-year follow-up following contemporary patellofemoral inlay arthroplasty (PFIA) and to identify potential risk factors for failure in a multi-center study.

METHODS

All patients who underwent implantation of PFIA between 09/2009 and 11/2016 at 11 specialized orthopedic referral centers were enrolled in the study and were evaluated retrospectively at a minimum 2-year follow-up. Clinical outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Tegner Scale, the visual analogue scale (VAS) for pain, and subjective patient satisfaction. Pre- and perioperative risk factors were compared among failures and non-failures to determine potential risk factors.

RESULTS

A total of 263 patients (85% follow-up rate) could be enrolled. The mean age at the time of index surgery was 49 ± 12 years with a mean postoperative follow-up of 45 ± 18 months. The overall failure rate was 11% (28 patients), of which 18% (5 patients) were patients with patella resurfacing at index surgery and 82% (23 patients) were patients without initial patella resurfacing. At final follow-up, 93% of the patients who did not fail were satisfied with the procedure with a mean transformed WOMAC Score of 84.5 ± 14.5 points, a mean KOOS Score of 73.3 ± 17.1 points, a mean Tegner Score of 3.4 ± 1.4 points and a mean VAS pain of 2.4 ± 2.0 points. An increased BMI was significantly correlated with a worse postoperative outcome. Concomitant procedures addressing patellofemoral instability or malalignment, the lack of patellofemoral resurfacing at the index surgery and a high BMI were significantly correlated with failure in our patient cohort.

CONCLUSION

Patellofemoral inlay arthroplasty shows high patient satisfaction with good functional outcomes at short-term follow-up and thus can be considered a viable treatment option in young patients suffering from isolated patellofemoral arthritis. Patellar resurfacing at index surgery is recommended to decrease the risk of failure.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

HemiCAP Knee Implants: Mid- to Long-Term Results

PURPOSE

The aim of the study was to investigate the long-term outcomes of the Focal Femoral Condyle Resurfacing Prosthesis (HemiCAP) using clinical and radiographic assessments, and to evaluate the revision and survival rates.

METHODS

Clinical evaluation was performed in those not revised and was able to participate. This was a prospective single-center cohort study of HemiCAP patients with 7 to 10 years of clinical and radiographic follow-up. The clinical examination included the Knee Society Score (KSS) and visual analogue scale (VAS) score. The radiographic examination included the Kellgren-Lawrence (KL) grade. Survival was estimated by Kaplan-Meier survival analysis, and potential risk factors for revision was evaluated by a regression analysis.

RESULTS

Of the 62 patients with 64 HemiCAP prostheses, 37 were HemiCAP condyle, 11 HemiCAP PF, and 16 HemiCAP Wave; 27 (42%) were revised-HemiCAP condyle 17 (42%), HemiCAP PF 4 (36%), HemiCAP Wave 6 (37%), and 1 died. Examinations were performed on 31 patients (86%). When compared with the preoperative data, there were significant increases in the KSS objective (mean = 51.5, standard deviation [SD] = 5.9 vs. mean =94.2, SD = 5.0) and function (mean = 51.0, SD = 6.2 vs. mean = 93.7, SD = 4.8) scores, a decrease in the VAS score (mean = 7.1, SD = 0.7 vs. mean = 2.7, SD = 1.7) and a decrease in the KL lateral score (mean = 1.1, SD = 0.3 vs. mean = 0.6, SD = 0.6). The mean follow-up was 7.3 years (SD 1.4) with minimum 4.2 years and maximum 10.2 years. No failures occurred in the series beyond 5 years.

CONCLUSIONS

As hypothesized, we found good clinical and radiographic outcomes, and for those patients who did not require revisions, there were long-term improvements in disability and function. This suggests that patient selection is a key element to successfully applying these devices in clinical practice.

The partial femoral condyle focal resurfacing (HemiCAP-UniCAP) for treatment of full-thickness cartilage defects, systematic review and meta-analysis

Knee osteochondral defects are a common problem among people, especially young and active patients. So effective joint preserving surgeries is essential to prevent or even delay the onset of osteoarthritis for these group of patients. This study aims to critically appraise and evaluate the evidence for the results and effectiveness of femoral condyle resurfacing (HemiCAP/ UniCAP) in treatment of patients with focal femoral condyle cartilage defect. Using the search terms : HemiCAP, UniCAP, Episurf, focal, femoral, condyle, inlay and resur-facing, we reviewed the PubMed and EMBASE and the Cochrane Database of Systematic Reviews (CDSR) to find any articles published up to March 2020. The short term follow-up of the HemiCAP shows (6.74 %) revision rate. However, 29.13 % loss of follow up let us consider these results with caution especially if the revision rate progressively increased with time to 19.3 % in 5-7 years with no enough evidence for the long term results except the data from the Australian Joint Registry 2018, where the cumulative revision rate was 40.6 % (33.5, 48.4) at ten years. The UniCAP that used for defect more than 4 cm 2 has a high revision rate (53.66 %) which is considered unacceptable revision rate in com-parison to another similar prosthesis such as Uni-Knee Arthroplasty (UKA). The evidence from published studies and our meta- analysis suggests that partial resurfacing of the femoral condyle (HemiCAP) doesn’t support its usage as a tool to treat the focal cartilage defect in middle- aged patients. The UniCAP as femoral condyle resurfacing has very high revision rate at 5-7 years (53.66 %) which make us recommend against its usage.

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

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

Reliable improvements in participation in low-impact sports following implantation of a patellofemoral inlay arthroplasty at mid-term follow-up

PURPOSE

The aim of this study was, to investigate the rate of return to sports (RTS) and physical activity after implantation of PFIA and to identify factors predictive of improved postoperative sporting ability.

METHODS

Sixty-two patients with a mean age of 46 ± 11 years, who underwent implantation of PFIA at the senior authors' institution, were enrolled. They were prospectively evaluated preoperatively and at a minimum of 2 years postoperatively with a mean follow-up of 60 ± 25 months. Clinical outcomes, return to sports and activity, type of sport or activity, subjective satisfaction, and frequency were evaluated by questionnaire.

RESULTS

The transformed overall Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score improved from 67 ± 16 to 77 ± 19 (p = 0.003), Tegner activity scale results improved from 3 ± 2 points to 4 ± 1 points (p < 0.001), and scores on the visual analog scale (VAS) pain scale decreased from 6 ± 2 points to 3 ± 2 points (p < 0.001). The sports frequency increased from 1 ± 2 sessions to 2 ± 1 sessions per week (p = 0.001). Ninety-four percent of the patients who did not fail could return to the same or higher level of sports, with 74% of the patients reporting an improved ability to perform sports. No preoperative factors could be detected to significantly influence RTS after surgery.

CONCLUSIONS

PFIA is a valid treatment option for the active patient with end-stage isolated patellofemoral OA. Reliable improvements in knee function, pain, and participation in low-impact sports were found.

LEVEL OF EVIDENCE

IV.

Patient-Specific Implants for Focal Cartilage Lesions in The Knee: Implant Survivorship Analysis up to Seven Years Post-Implantation

In the quest for increased surgical precision and improved joint kinematics, Computer-Assisted Orthopedic Surgery (CAOS) shows promising results for both total and partial joint replacement. In the knee, computer-assisted joint design can now be applied to the treatment of younger patients suffering pain and restriction of activity due to focal defects in their femoral articular cartilage. By taking MRI scans of the affected knee and digitally segmenting these scans, we can identify and map focal defects in cartilage and bone. Metallic implants matched to the defect can be fabricated, and guide instrumentation to ensure proper implant alignment and depth of recession in the surrounding cartilage can be designed from segmented MRI scans. Beginning in 2012, a series of 682 patient-specific implants were designed based on MRI analysis of femoral cartilage focal defects, and implanted in 612 knees. A Kaplan-Meier analysis found a cumulative survivorship of 96% at 7-year follow-up from the first implantation. Fourteen (2.3%) of these implants required revision due to disease progression, incorrect implant positioning, and inadequate lesion coverage at the time of surgery. These survivorship data compare favorably with all other modes of treatment for femoral focal cartilage lesions and support the use of patient-specific implants designed from segmented MRI scans in these cases.

Preoperative patellofemoral anatomy affects failure rate after isolated patellofemoral inlay arthroplasty

PURPOSE

To analyze whether preoperative patellofemoral anatomy is associated with clinical improvement and failure rate after isolated patellofemoral arthroplasty (PFA) using a modern inlay-type trochlear implant.

METHODS

Prospectively collected 24 months data of patients treated with isolated inlay PFA (HemiCAP^® Wave, Arthrosurface, Franklin, MA, USA) between 2009 and 2016, and available digitalized preoperative imaging (plain radiographs in three planes and MRI) were retrospectively analyzed. All patients were evaluated using the WOMAC score, Lysholm score, and VAS pain. Patients revised to TKA or not achieving the minimal clinically important difference (MCID) for the total WOMAC score or VAS pain were considered failures. Preoperative imaging was analyzed regarding the following aspects: Tibiofemoral OA, patellofemoral OA, trochlear dysplasia (Dejour classification), patellar height (Insall-Salvati index [ISI]; Patellotrochlear index [PTI]), and position of the tibial tuberosity (TT-TG and TT-PCL distance).

RESULTS

A total of 41 patients (61% female) with a mean age of 48 ± 13 years could be included. Fifteen patients (37%) were considered failures, with 5 patients (12%) revised to TKA and 10 patients (24%) not achieving MCID for WOMAC total or VAS pain. Failures had a significantly higher ISI, and a significantly lower PTI. Furthermore, the proportion of patients with a pathologic ISI (> 1.2), a pathologic PTI (< 0.28), and without trochlear dysplasia were significantly higher in failures. Significantly greater improvements in clinical outcome scores were observed in patients with a higher preoperative grade of patellofemoral OA, ISI ≤ 1.2, PTI ≥ 0.28, TT-PCL distance ≤ 21 mm, and a dysplastic trochlea.

CONCLUSION

Preoperative patellofemoral anatomy is significantly associated with clinical improvement and failure rate after isolated inlay PFA. Less improvement and a higher failure rate must be expected in patients with patella alta (ISI > 1.2 and PTI < 0.28), absence of trochlear dysplasia, and a lateralized position of the tibial tuberosity (TT-PCL distance > 21 mm). Concomitant procedures such as tibial tuberosity transfer may, therefore, be considered in such patients.

LEVEL OF EVIDENCE

Level III, retrospective analysis of prospectively collected data.

The Combination of Inlay Patellofemoral Arthroplasty and Medial Unicompartmental Knee Arthroplasty Versus Total Knee Arthroplasty for Mediopatellofemoral Osteoarthritis: A Comparison of Mid-Term Outcomes

BACKGROUND

To the best of our knowledge, there have been no studies in the literature related to the use of second-generation inlay patellofemoral arthroplasty and unicompartmental knee arthroplasty combination (inlay PFA/UKA) in the treatment of mediopatellofemoral osteoarthritis (MPFOA). The aim of this study is to evaluate the efficacy of inlay PFA/UKA in MPFOA.

METHODS

The study included 49 patients applied with inlay PFA/UKA because of MPFOA and 49 patients applied with TKA, matched one-to-one according to age, gender, body mass index, follow-up period, preoperative Knee Society Score, and range of motion. All the patients were evaluated clinically using the Knee Society Score, Knee Injury Osteoarthritis Outcome Score, and range of motion, and were also evaluated radiologically. Complication rates and length of hospital stay were compared.

RESULTS

The mean follow-up period was 54 ± 4 and 54.4 ± 3.9 months in inlay PFA/UKA and TKA groups, respectively. (P = .841). No statistically significant difference was determined between the 2 groups in respect of the mean clinical scores at the final follow-up examination (P ≥ .129). Total complications were fewer and length of hospital stay was shorter in the inlay PFA/UKA group than in the TKA group (P = .037 and P = .002). There was no radiographic evidence of progression of lateral compartment osteoarthritis according to Kellgren-Lawrence in any patient in the inlay PFA/UKA group.

CONCLUSION

In selected patient groups, inlay PFA/UKA is an alternative to TKA, with lower complication rates, shorter length of hospital stay, and clinical and functional results similar to those of TKA without osteoarthritis progression in the unresurfaced lateral compartment in the mid-term.

LEVEL OF EVIDENCE

III.

High patient satisfaction with significant improvement in knee function and pain relief after mid-term follow-up in patients with isolated patellofemoral inlay arthroplasty

PURPOSE

To prospectively evaluate the clinical and radiographic outcomes and survivorship at 2 and 5 years after isolated contemporary patellofemoral inlay arthroplasty.

METHODS

Thirty-four patients were prospectively enrolled in the study and were evaluated preoperatively and at 2 and 5 years postoperatively. Clinical outcomes included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and the visual analogue scale (VAS) for pain. Kellgren-Lawrence grading was used to assess the progression of tibiofemoral osteoarthritis and the Caton-Deschamps Index to determine patellar height. A Kaplan-Meier survival analysis was used to investigate the implant survivorship. Preoperative patient characteristics were compared among failures and success to determine potential risk factors and patient satisfaction was rated postoperatively.

RESULTS

Five of the 34 patients were lost to follow-up resulting in a final follow-up rate of 86%. The total WOMAC subscores of pain and function and the VAS Pain improved significantly at 2- and 5-years, with no significant difference between the two time points. The WOMAC stiffness subscale reached significant improvement at 2-year follow-up alone. No significant progressions of tibiofemoral arthritis or changes in patellar height were observed. A total of six patients (17.1%) failed leaving a survival rate of 91% after 2 years and 83% after 5 years. The main cause for postoperative failure was persistent knee pain; however, no significant preoperative risk factor in patient characteristics could be identified.

CONCLUSION

Patellofemoral inlay arthroplasty shows high patient satisfaction with significant improvement in knee function and pain relief after mid-term follow-up with no radiographic progression of tibiofemoral OA.

LEVEL OF EVIDENCE

Prospective case series, Level III.

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.

The cost-effectiveness of osteochondral allograft transplantation in the knee

PURPOSE

Osteochondral allografts (OCA) consist of a layer of hyaline cartilage and a layer of underlying bone. They are used to repair combined defects of articular cartilage and bone. Such defects often occur in people far too young to have knee arthroplasty, for whom the main alternative to OCA is conservative symptomatic care, which will not prevent development of osteoarthritis. The aim of this report was to assess the cost-effectiveness of osteochondral allograft transplantation in the knee.

METHODS

Systematic review of evidence on clinical effectiveness and economic modelling.

RESULTS

The evidence on osteochondral allograft transplantation comes from observational studies, but often based on good quality prospective registries of all patients having such surgery. Without controlled trials, it was necessary to use historical cohorts to assess the effect of osteochondral grafts. There is good evidence that OCA are clinically effective with a high graft survival rate over 20 years. If an OCA graft fails, there is some evidence that revision with a second OCA is also effective, though less so than primary OCA. Economic modelling showed that osteochondral allograft transplantation was highly cost-effective, with costs per quality adjusted life year much lower than many other treatments considered cost effective.

CONCLUSIONS

Osteochondral allograft transplantation appears highly cost-effective though the cost per quality adjusted life year varies according to the widely varying costs of allografts. Based on one small study, revision OCA also appears very cost-effective, but more evidence is needed.

LEVEL OF EVIDENCE

II.

The clinical outcome of the different HemiCAP and UniCAP knee implants: A systematic and comprehensive review

The focal metallic cartilage resurfacing is a surgical method that offers an appropriate step between the biological techniques and arthroplasty in middle-aged patients with full-thickness cartilage defects. The advantages of this technique are that it addresses the defect, respects healthy tissues and provides stability and contoured surface similar to a full arthroplasty. A systematic review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Two reviewers (MM and DC) independently conducted the search using the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews (CDSR). These databases were searched for the terms hemicap knee implant and unicap knee implant and knee focal metallic implant. From the initial 21 studies that were evaluated, 10 were eligible for analysis. Considering both the HemiCAP focal implant and the HemiCap^® Wave patellofemoral prosthesis, we found a lack of mid- to long-term clinical outcomes in well-designed prospective clinical studies. No Level I or II studies were found, while the limited number of patients who were included undermines the overall clinical results of these studies. The progression of osteoarthritis, the persisting pain and the subsequent high revision or failure rates in the limited available studies with long-term follow-up, seem to be the major drawbacks of these partial resurfacing techniques. Utilization of partial resurfacing for femoral or patellofemoral compartments results in good short-term outcome for middle-aged patients as a step between biological technique and total knee arthroplasty. The surgeon should be cognizant and also notify the patient of the high failure rates that are reported in the literature in mid- to longterm follow-up and ultimately, the decision to perform partial resurfacing should be taken by both the patient and the orthopedic surgeon.